Abstract: Type 1 diabetes results from a T cell-mediated destruction of insulin-producing pancreatic beta cells. Little is known on local factors contributing to migration of T cells to pancreatic tissue. We recently demonstrated evidence of viral infection in beta cells in several recent-onset type 1 diabetes patients. Islet inflammation was analysed in a series of new- or recent-onset type 1 diabetic patients and non-diabetic control subjects. Autoimmune T cell reactivity was studied in lymphocytes derived from pancreas-draining lymph nodes of one recent-onset type 1 diabetes patient in partial clinical remission. Insulitic lesions were characterized by presence of beta cells, elevated levels of the chemokine CXCL10 and infiltration of lymphocytes expressing the corresponding chemokine receptor CXCR3 in all pancreatic lesions of type 1 diabetes patients, regardless of enterovirus infection of beta cells. CXCR3 and CXCL10 were undetectable in pancreata of non-diabetic control subjects. T cells isolated from draining lymph nodes of a recent-onset patient with virally infected beta cells and in clinical remission reacted with multiple islet autoantigens and displayed a mixed interferon (IFN)-gamma/interleukin (IL)-10 cytokine pattern. Our data point to CXCL10 as an important cytokine in distressed islets that may contribute to inflammation leading to insulitis and beta cell destruction, regardless of local viral infection. We demonstrate further pro- and anti-inflammatory islet autoreactivity, indicating that different adaptive and innate immune responses may contribute to insulitis and beta cell destruction.
Abstract: OBJECTIVE: Cytotoxic T lymphocyte antigen-4 (CTLA4) gene polymorphism has been associated with human autoimmune diseases, but discordant data are available on its association with autoimmune Addison's disease (AAD). We tested the human leukocyte antigen (HLA)-independent association of CTLA4+49 (A/G) (Ala 17) and/or CTLA4 CT60 (A/G) polymorphism with AAD. DESIGN: DNA samples from 180 AAD patients and 394 healthy control subjects from continental Italy were analyzed, and association statistical analyses and meta-analysis of published studies were performed. Methods TaqMan minor groove binder chemistry assays and PCR fragment length polymorphism assays were used. RESULTS: Frequency of allele G of CTLA4+49 was significantly increased among AAD patients (40% alleles) than among healthy controls (27% alleles; P<0.0001). CTLA4 CT60 polymorphism was associated with AAD only in the heterozygous A/G individuals. The frequency of +49 AG+GG genotypes was significantly higher among AAD patients than among healthy control subjects, in both a co-dominant (P<0.0001) and G dominant model (P<0.0001). CTLA4+49 allele G was significantly associated with disease risk in both patients with isolated AAD and in patients with autoimmune polyendocrine syndrome. Multivariate logistic regression analysis showed that CTLA4+49 allele G was positively associated with AAD (P<0.0001, odds ratio (OR)=2.43, 95% confidence interval=1.54-3.86) also after correction for DRB1*03-DQA1*0501-DQB1*0201, DRB1*04-DQA1*0301-DQB1*0302, and sex. Meta-analysis of five studies revealed a significant association of CTLA4+49 allele G with AAD (P<0.0001) with an overall OR of 1.48 (1.28-1.71). CONCLUSIONS: The CTLA4+49 polymorphism is strongly associated with genetic risk for AAD, independently from the well-known association with HLA class II genes.
Abstract: AIM: To compare the efficacy and safety of vildagliptin and metformin initial combination therapy with individual monotherapies in treatment-naive patients with type 2 diabetes mellitus (T2DM). METHODS: This was a 24-week, randomized, double-blind, active-controlled study. Treatment-naive patients with T2DM who had a glycated haemoglobin (HbA(1c)) of 7.5-11% (N = 1179) were randomized equally to receive vildagliptin plus high-dose metformin combination therapy (50 mg + 1000 mg twice daily), vildagliptin plus low-dose metformin combination therapy (50 mg + 500 mg twice daily), vildagliptin monotherapy (50 mg twice daily) or high-dose metformin monotherapy (1000 mg twice daily). The primary objective was to demonstrate that HbA(1c) reduction from baseline with either combination therapy is superior to both monotherapies at the week 24 endpoint. Patients who failed glycaemic-screening criteria [HbA(1c )>11% or fasting plasma glucose (FPG) >15 mmol/l (270 mg/dl)] could enter a 24-week, single-arm substudy. These patients (N = 94) received open-label vildagliptin plus high-dose metformin combination therapy (100 mg + 1000 mg twice daily). RESULTS: From comparable baseline values (8.6-8.7%), HbA(1c) decreased in all four treatment groups, to the greatest extent with vildagliptin plus high-dose metformin combination therapy. Mean (SE) HbA(1c) change from baseline was -1.8% (0.06%), -1.6% (0.06%), -1.1% (0.06%) and -1.4% (0.06%) with vildagliptin plus high-dose metformin combination therapy, vildagliptin plus low-dose metformin combination therapy, and vildagliptin and metformin monotherapies respectively. The between-group difference was superior with vildagliptin plus high-dose metformin combination therapy (p < 0.001 vs. both monotherapies) and vildagliptin plus low-dose metformin combination therapy (p < 0.001 and p = 0.004, vs. vildagliptin and metformin monotherapies, respectively). Higher baseline HbA(1c) values were linked to greater HbA(1c) reductions, with changes of -3.2% (0.22%), -2.7% (0.22%), -1.5% (0.24%) and -2.6% (0.26%) respectively, occurring in patients with baseline HbA(1c)>or=10%. Reductions in FPG were superior with vildagliptin plus high-dose metformin combination therapy [change from baseline -2.63 (0.13) mmol/l] compared with both monotherapies [-1.26 (0.13) mmol/l and -1.92 (0.13) mmol/l, respectively; p < 0.001]. There was no incidence of hypoglycaemia or severe hypoglycaemia with either combination therapy, and neither was associated with weight gain. All treatments were well tolerated and displayed a comparable incidence of adverse events overall. Despite superior HbA(1c) lowering, the vildagliptin plus low-dose metformin combination therapy group demonstrated a favourable gastrointestinal (GI) tolerability profile compared with metformin monotherapy. CONCLUSIONS: In treatment-naive patients, combinations of vildagliptin and both high-dose and low-dose metformin provide superior efficacy to monotherapy treatments with a comparable overall tolerability profile and low risk of hypoglycaemia. The potential dose-sparing effect of adding vildagliptin to low-dose metformin in preference to the up-titration of metformin may allow patients to achieve equivalent or superior HbA(1c) lowering without the GI tolerability issues associated with higher doses of metformin.
Abstract: Some attempts have been made in assaying glutamic-acid decarboxylase autoantibodies (GADA) in type 1 diabetic patient (T1DM) saliva. However, these salivary assays did not show sufficient sensitivity and specificity in comparison to serum assays. In this study we evaluated the ability of a fluid-phase (35)S-radioimmunoassay to detect GADA and tyrosine phosphatase 2 autoantibodies (IA-2A) in 70 T1DM, 24 T1DM first degree relatives (FDR) and 76 healthy subject saliva. Paired saliva and serum samples were collected from each subject and analyzed. GADA were detected in 45/70 (64.3%) sera and 43/70 (61.4%) T1DM saliva, respectively. IA-2A were detected in 33/70 (47.1%) sera and 30/70 (42.9%) T1DM saliva, respectively. All FDR serum/saliva samples were autoantibody negative. In conclusion, we here report that GADA and IA-2A are detectable with high sensitivity and specificity in human saliva, a specimen which can be easily collected by non-invasive procedures and may represent a reliable tool for the study of T1DM autoimmunity.
Abstract: AIM: To compare the tolerability and efficacy of vildagliptin to pioglitazone as add-on therapy in patients with type 2 diabetes inadequately controlled with metformin monotherapy over 1-year duration. METHODS: This 52-week, multicentre, randomized, active-controlled study compared vildagliptin (50 mg b.i.d., n = 295) and pioglitazone (30 mg daily, n = 281) in patients with inadequate glycaemic control [haemoglobin A1c (HbA(1c)) 7.5-11%] receiving a stable dose of metformin (>or=1500 mg). The primary objective was to demonstrate non-inferiority of vildagliptin at 24 weeks in the change in HbA(1c) from baseline. The objective of the additional 28 weeks of the study was to assess long-term safety, while also assessing mean change from baseline to study end in HbA(1c), fasting plasma glucose and body weight. RESULTS: When added to a stable dose of metformin (mean baseline dose approximately 2 g/day), the non-inferiority of HbA(1c) lowering of vildagliptin to pioglitazone over 24 weeks was established at the non-inferiority margin of 0.3% (between-group difference = 0.1%). During the remaining 28 weeks, comparable HbA(1c) decreases were recorded in both groups. Overall adverse event (AE) rates were similar in both groups, as was the occurrence of peripheral oedema. Hypoglycaemia occurred rarely in both groups. Serious AEs occurred more frequently with pioglitazone group. While mean body weight increased significantly in the pioglitazone group (+2.6 kg) from baseline, there was no significant weight gain with vildagliptin (+0.2 kg). CONCLUSIONS: When added to metformin, vildagliptin demonstrates favourable safety and tolerability over 1 year. Vildagliptin provided additional HbA(1c) lowering to that achieved with metformin alone and comparable to that achieved with pioglitazone, with only pioglitazone causing weight gain.
Abstract: The availability of new immunosuppressive drugs has led to improvement in outcome for transplanted patients, but these drugs have also led to the increase of metabolic abnormalities, such as dyslipidemia and hyperglycemia, which can affect graft and patient outcome. Posttransplant diabetes mellitus (PTDM) or new-onset diabetes after transplantation is defined as the onset of diabetes in previously nondiabetic transplant recipients. Several clinical studies have demonstrated the involvement of PTDM in death due to infectious and cardiovascular disease. This article reviews recent concepts on pathophysiology, diagnosis, and treatment of PTDM.
Abstract: In Western countries, thyrotoxic periodic paralysis (TPP) is a rare condition with only sporadic cases described so far. Here, we describe a 29-year-old Italian man who presented with leg weakness and hypokalaemia. Treatment with intravenous potassium resulted in a rapid resolution of symptoms. TPP as the underlying cause was suggested by suppressed thyroid-stimulating hormone (TSH), elevated free T3 and free T4, and the presence of TSH-receptor antibodies (TRAB). Genetic analysis showed no mutations in the candidate exons of calcium (CACN1AS), potassium (KCNE3) and sodium (SCN4A) channel genes. However, we identified the presence of two single nucleotide polymorphisms (SNPs), 1491C > T and 1551 T > C, in exon 11 of the CACN1AS gene. Although the 1491C > T SNP is not apparently involved in the pathogenesis of the disease, the 1551 T > C SNP has been associated with TPP in Asians and reported in only one case in European Caucasians. Further investigations are needed to clarify whether such polymorphisms have a role in the disease pathogenesis in Caucasians.
Abstract: AIMS/HYPOTHESIS: In patients with type 2 diabetes, reduced levels of circulating endothelial progenitor cells have been reported and these have been correlated with disease severity. In this study, we examined a panel of markers widely used to identify progenitor and/or stem cells, and determined their association with disease severity in diabetic patients. Since expression of chemokine (C-X-C motif) receptor 4 (CXCR4) has been associated with mobilisation and recruitment of progenitor cells, CXCR4 expression was also analysed. METHODS: Peripheral blood mononuclear cells (PBMCs) from 98 patients with type 2 diabetes and 39 control individuals were analysed by flow cytometry for surface marker expression. RESULTS: Cells expressing different combinations of progenitor and/or stem cell markers were severely reduced in PBMCs of diabetic patients compared with those of control participants. Moreover, a number of these putative progenitor cell populations were negatively associated with disease severity. Reduced expression of CXCR4 and CD34/CXCR4-positive cells was also observed in diabetic patients. PBMCs expressing CXCR4 positively correlated with levels of progenitor cells in control participants but not in diabetic patients. Levels of putative progenitor and CXCR4-positive cells were further decreased in patients with diabetic complications, including cardiovascular and microvascular diseases. CONCLUSIONS/INTERPRETATION: A generalised decrease in a range of progenitor cell populations was observed in type 2 diabetic patients. This reduction was also negatively associated with disease severity.
Abstract: Type 2 diabetes is the most common form of diabetes in humans. It results from a combination of factors that impair beta-cell function and tissue insulin sensitivity. However, growing evidence is showing that the beta-cell is central to the development and progression of this form of diabetes. Reduced islet and/or insulin-containing cell mass or volume in Type 2 diabetes has been reported by several authors. Furthermore, studies with isolated Type 2 diabetic islets have consistently shown both quantitative and qualitative defects of glucose-stimulated insulin secretion. The impact of genotype in affecting beta-cell function and survival is a very fast growing field or research, and several gene polymorphisms have been associated with this form of diabetes. Among acquired factors, glucotoxicity, lipotoxicity and altered IAPP processing are likely to play an important role. Interestingly, however, pharmacological intervention can improve several defects of Type 2 diabetes islet cells in vitro, suggesting that progression of the disease might not be relentless.
Abstract: OBJECTIVE: The presence of autoantibodies to islet antigens GAD and/or tyrosine phosphatase 2 (IA-2) in type 2 diabetic patients (latent autoimmune diabetes in adults [LADA]) identifies subjects at high risk to develop insulin dependency. The aim of this study was to dissect humoral anti-IA-2 immune response in Caucasian LADA patients, identifying the most sensitive construct to evaluate IA-2 immunoreactivity and comparing LADA IA-2 epitope specificities to those found in type 1 diabetes. RESEARCH DESIGN AND METHODS: We analyzed 177 LADA and 978 type 2 diabetic patients with different disease duration, collected in a nationwide Italian survey, the Non-Insulin Requiring Autoimmune Diabetes (NIRAD) study aimed at assessing prevalence and characteristics of autoimmune diabetes in type 2 diabetic patients and 106 newly diagnosed type 1 diabetic patients (53 children, 53 adults). By radioimmunoassay, we analyzed humoral immunoreactivity to seven IA-2 constructs: IA-2(PTP (687-979)), IA-2((761-964)), IA-2((256-760)), IA-2(JM (601-630)), IA-2(IC (605-979)), IA-2(BDC (256-556:630-979)), and IA-2(FL (1-979)). RESULTS: IA-2((256-760)) fragment was identified as the marker with the highest sensitivity for detection of humoral IA-2 immunoreactivity in LADA patients, identifying IA-2 autoantibodies in approximately 30% of GAD antibody (GADA)-positive LADA patients and in 3.4% of GADA-negative type 2 diabetic patients. LADA IA-2((256-760))A positivity was associated with an increased frequency of autoimmune diabetes HLA-susceptible genotypes and with a higher risk for developing thyroid autoimmunity compared with autoantibody-negative type 2 diabetic patients. At disease diagnosis, adult-onset type 1 diabetic and LADA patients showed a lower IA-2 COOH-terminal immunoreactivity compared with childhood-onset type 1 diabetic patients. CONCLUSIONS: IA-2 immunoreactivity in LADA patients has thus far been underestimated, and IA-2((256-760)) autoantibody detection may represent a novel diagnostic tool for the identification of islet autoimmunity in these patients.
Abstract: AIM: The aim of this study was to compare the efficacy and tolerability of vildagliptin vs. pioglitazone as add-on therapy in patients with type 2 diabetes inadequately controlled with metformin monotherapy. METHODS: This 24-week, multicentre, double-blind, randomized, active-controlled study compared vildagliptin (100 mg daily, given as equally divided doses, n = 295) and pioglitazone (30 mg daily, given as a single q.d. dose, n = 281) in patients with inadequate glycaemic control (A1C 7.5-11%) while receiving a stable metformin dose (> or =1500 mg daily). The adjusted mean changes from baseline to study endpoint (AMDelta) in A1C, fasting plasma glucose (FPG), fasting lipids and body weight were compared by analysis of covariance. RESULTS: When added to a stable dose of metformin (mean dose at baseline >2000 mg/day), both vildagliptin and pioglitazone decreased A1C (AMDelta = -0.9 +/- 0.1% and -1.0 +/- 0.1%, respectively) from identical baseline values (8.4 +/- 0.1%). The between-group difference in AMDelta A1C was 0.1 +/- 0.1%, and non-inferiority of vildagliptin to pioglitazone was established at both 0.4 and 0.3% margins for upper limit of the 95% confidence intervals. Pioglitazone decreased FPG (AMDelta = -2.1 +/- 0.1 mmol/l) to a greater extent than vildagliptin (AMDelta = -1.4 +/- 0.1 mmol/l), but only pioglitazone increased body weight (AMDelta = +1.9 +/- 0.2 kg: between-group difference = -1.6 +/- 0.3 kg, p < 0.001). Adverse events (AEs) were reported by 60% of vildagliptin-treated patients and by 56.4% of pioglitazone-treated patients; serious AEs were reported by 2.0 and 4.6% of patients receiving vildagliptin and pioglitazone respectively. Mild hypoglycaemia was reported by one patient (0.3%) in the vildagliptin group and by no patients receiving pioglitazone. CONCLUSIONS: When added to metformin, the efficacy of vildagliptin is non-inferior to that of pioglitazone. The treatments were similarly well tolerated, but only pioglitazone increased body weight.
Abstract: AIM: The onset of posttransplant diabetes mellitus (PTDM) among kidney recipients is associated with an increased risk of graft failure and death. Minimizing the risk of PTDM is a priority for long-term improvement in survival rates. We sought to evaluate the prevalence of PTDM and impaired fasting glucose (IFG) among a population of kidney transplant recipients to identify the risk factors and to evaluate graft and patient survivals. METHODS: We analyzed 250 consecutive Caucasian patients who received kidney allografts in our center between May 2000 and December 2005, with a median follow-up of 32 months (range, 1-78 months). RESULTS: We observed altered glucose metabolism in 17% of patients; specifically, the prevalences of PTDM and IFG were 12.2% and 4.8%, respectively. Patients who developed PTDM or IFG were overweight (BMI, 26.4+/-3.4 and 28.1+/-3.4 kg/m(2), respectively), whereas the normal glucose (NG) group's BMI was 23.8+/-3.5 kg/m(2) (P= .002 and P= .004, respectively). Prevalence of acute rejection was higher in the PTDM and IFG patients compared with the NG patients (60.7%, 63.6%, and 32.1%, respectively; P= .006; P< .04), while no difference was observed in terms of graft and patient overall survival. CONCLUSION: In our series of patients, we showed that being overweight represents a major risk factor for the development of PTDM, which results in an increased acute rejection rate. These results confirmed the importance of appropriate weight control among patients undergoing kidney transplantation, which should also be strictly monitored for all risk factors associated with the development of impaired glucose metabolism.
Abstract: Type 1 diabetes is caused by the autoimmune destruction of insulin-producing cells with consequent hyperglycemia and serious chronic complications. Both innate and adaptive immune responses participate in disease pathogenesis. Studies in animal models and in man have shown that NK cells are involved both in disease progression and in disease protection, thus suggesting that NK cells can represent a potential therapeutic target in type 1 diabetes, once the contribution of these cells to islet autoimmunity has been fully elucidated.
Abstract: A detailed understanding of the molecular process involved in the proliferation of pancreatic precursor cells would provide key elements for developing new therapeutic strategies to cure type 1 diabetes. In the present study we investigated the potential involvement of hedgehog signaling in proliferating human pancreatic islet-derived mesenchymal (hPIDM) cells, a population of cells that can be successfully expanded and induced to differentiate into an insulin-secreting phenotype. Here we report that in these precursor cells a hedgehog signaling pathway is activated, as shown by Gli1 expression, and that a dose-dependent inhibition of such a pathway by cyclopamine results in a significant reduction of cell proliferation.
Abstract: OBJECTIVE: The aim of the present study was to define heterogeneity of adult-onset autoimmune diabetes based on characterization of GAD antibodies (GADAs). RESEARCH DESIGN AND METHODS: Patients enrolled in a nationwide survey, the Non Insulin Requiring Autoimmune Diabetes (NIRAD) Study, have been screened for GADAs and IA-2 antibodies (IA-2As) and further characterized for GADA titer, antibodies to thyroid peroxidase (TPO), and HLA DRB1-DQB1 polymorphisms. RESULTS: Of 4,250 consecutive type 2 diabetic patients, 4.5% had either GADAs and/or IA-2As. Patients with autoimmune diabetes showed a clinical phenotype significantly different from that of type 2 diabetes, including higher fasting glucose and A1C, lower BMI and uric acid, lower prevalence of metabolic syndrome and its components, and higher frequency of TPO antibodies. More interestingly, analysis of GADA titers showed a bimodal distribution that identified two subgroups of patients with high (>32 GADA arbitrary units) and low (< or =32 GADA arbitrary units) GADA titers. Compared with those with low GADA titers, patients with high GADA titers had more prominent traits of insulin deficiency and a profile of more severe autoimmunity resulting in higher A1C, lower BMI, a lower prevalence of metabolic syndrome and its components (P < 0.02 for all), a higher prevalence of IA-2As, TPO antibodies (P < 0.003 for both), and DRB1*03-DQB1*0201 (50 vs. 26.8%, P = 0.001), and a decreasing frequency of DQB1*0602 and DRB1*0403 (from type 2 to low and to high GADA titer autoimmune diabetes; P < 0.001 for trend for both comparisons). CONCLUSIONS: GADA titers identify two subgroups of patients with adult-onset autoimmune diabetes having distinct clinical, autoimmune, and genetic features.
Abstract: Type 1 diabetes is characterized by T cell-mediated autoimmune destruction of pancreatic beta cells. Several studies have suggested an association between Coxsackie enterovirus seroconversion and onset of disease. However, a direct link between beta cell viral infection and islet inflammation has not been established. We analyzed pancreatic tissue from six type 1 diabetic and 26 control organ donors. Immunohistochemical, electron microscopy, whole-genome ex vivo nucleotide sequencing, cell culture, and immunological studies demonstrated Coxsackie B4 enterovirus in specimens from three of the six diabetic patients. Infection was specific of beta cells, which showed nondestructive islet inflammation mediated mainly by natural killer cells. Islets from enterovirus-positive samples displayed reduced insulin secretion in response to glucose and other secretagogues. In addition, virus extracted from positive islets was able to infect beta cells from human islets of nondiabetic donors, causing viral inclusions and signs of pyknosis. None of the control organ donors showed signs of viral infection. These studies provide direct evidence that enterovirus can infect beta cells in patients with type 1 diabetes and that infection is associated with inflammation and functional impairment.
Abstract: Cellular models and culture conditions for in vitro expansion of insulin-producing cells represent a key element to develop cell therapy for diabetes. Initial evidence that human beta-cells could be expanded after undergoing a reversible epithelial-mesenchymal transition has been recently negated by genetic lineage tracing studies in mice. Here, we report that culturing human pancreatic islets in the presence of serum resulted in the emergence of a population of nestin-positive cells. These proliferating cells were mainly C-peptide negative, although in the first week in culture, proliferating cells, insulin promoter factor-1 (Ipf-1) positive, were observed. Later passages of islet-derived cells were Ipf-1 negative and displayed a mesenchymal phenotype. These human pancreatic islet-derived mesenchymal (hPIDM) cells were expanded up to 10(14) cells and were able to differentiate toward adipocytes, osteocytes and chondrocytes, similarly to mesenchymal stem/precursor cells. Interestingly, however, under serum-free conditions, hPIDM cells lost the mesenchymal phenotype, formed islet-like clusters (ILCs) and were able to produce and secrete insulin. These data suggest that, although these cells are likely to result from preexisting mesenchymal cells rather than beta-cells, hPIDM cells represent a valuable model for further developments toward future replacement therapy in diabetes.
Abstract: BACKGROUND: Absence or segmental distribution of the alpha5(IV) collagen chain along the epidermal basement membrane (EBM) is diagnostic of X-linked Alport syndrome (X-AS), but the typical morphologic alterations usually observed along the glomerular basement membrane (GBM) are lacking. However, several differences in protein composition exist between GBM and EBM, and such differences could account for a different phenotype with the same genetic defect. Type VII collagen is one of the major collagenous components of the EBM; the purpose of this study was to investigate the modifications of protein synthesis and expression of type VII collagen in the skin of patients with X-AS. METHODS: The distribution of type VII collagen has been studied in 15 skin biopsies (10 from X-AS patients and 5 controls) by means of electron microscopy, immunofluorescence and confocal microscopy; type VII collagen mRNA expression was also measured by RT-PCR on the same skin fragments. RESULTS: Protein and mRNA amounts for type VII collagen were significantly higher in skin samples from X-AS patients than in controls (P < 0.001); highest values were in cases in which alpha5(IV) was completely absent. CONCLUSIONS: Our results indicate that lack of alpha5(IV) molecule significantly alters the assembly of extracellular matrix molecules other than alphax(IV) chains also at the EBM level. We suggest that the increased synthesis and deposition of type VII collagen is likely to balance the absence of stabilizing activity normally exerted by alpha5(IV).
Abstract: The aim of the present study was to evaluate the epitope specific humoral human tissue transglutaminase (tTG) immunoreactivity against 3 different human recombinant tTG constructs [(full-length tTG (a.a. 1-687), tTG (a.a. 227-687); tTG (a.a. 473-687)] before and after the introduction of a gluten-free diet (GFD). To this end, sera from 64 celiac disease (CD) subjects on a gluten-containing diet (44 f, 20 m) and after 0.6 +/- 0.3 years and 2.1 +/- 1.3 years of GFD were studied using a quantitative radioimmunoprecipitation assay. All 64 CD patients at diagnosis were full-length anti-tTG (a.a. 1-687)Ab positive. These Abs significantly decreased in frequency and titer after 6 months and 2 years of GFD. However, at low titers, 64.1% (41/64) of CD patients were still fl-tTG (a.a. 1-687)Ab positive after 2 years of GFD. At disease diagnosis, 70.3% (45/64) of the CD patients had Abs directed against fragments (227-687) and/or (473-687) of the tTG protein. This percentage, after 2 years of GFD, significantly decreased to 18.7%, whereas almost 50% of GFD patients had no tTG (227-687) and tTG (473-687) fragment reactivity, but only persistent, low-titer full-length tTG (1-687)Abs. We suggest that the selective loss of immunoreactivity against tTG (227-687) and tTG (473-687) fragments in CD patients with a GFD, could be due to quantitative decrease of autoreactivity driven by tTG-gliadin interaction underlying celiac disease pathogenesis.
Abstract: CONTEXT: Activation-induced cell death (AICD) is a major mechanism in the regulation of peripheral tolerance, and caspase-3 represents its major executioner. AICD impairment contributes to the persistence of autoreactive T cells, and defective AICD has been reported in autoimmune thyroiditis as well as in type 1 diabetes mellitus. OBJECTIVE: The objective of this study was to evaluate the involvement of caspase-3 in the regulation of AICD resistance in thyroid and polyendocrine autoimmunity. DESIGN/SETTINGS/PATIENTS/INTERVENTION: Caspase-3 expression was analyzed in peripheral blood lymphocytes from 26 adults (A-AT) and 25 children (Y-AT) affected by autoimmune thyroiditis and 13 individuals affected by chronic autoimmune thyroiditis plus Addison's disease [autoimmune polyendocrine syndrome-2 (APS-2)] in comparison with 32 age-matched normal control subjects (NC). OUTCOME MEASURES: Caspase-3 mRNA expression in peripheral T cells was evaluated by quantitative real-time PCR; protein expression of both procaspase-3 and activated caspase-3 by Western blot analysis was followed by scanning densitometry. RESULTS: Caspase-3 mRNA expression was significantly reduced in resting lymphocytes from both A-AT (P = 0.001) and Y-AT (P = 0.016) compared with NC. After lymphocyte activation, protein levels of caspase-3 active form were significantly reduced in A-AT (P = 0.023) and Y-AT (P = 0.001) compared with NC. The APS-2 group displayed characteristics similar to the A-AT group because both caspase-3 mRNA and protein active form levels were significantly reduced compared with NC (P = 0.004 and 0.002, respectively). CONCLUSION: Our data show that peripheral lymphocytes of subjects affected by thyroid autoimmunity or APS-2 show defective expression of the major executioner of AICD, thus potentially contributing to AICD resistance and to the development of autoimmunity.
Abstract: The elucidation of mechanisms regulating the regeneration and survival of pancreatic beta cells has fundamental implications in the cell therapy of type 1 diabetes. The present study had the following three aims: 1. to investigate whether pancreatic ductal epithelial cells can be induced to differentiate into insulin-producing cells by exposing them to hepatocyte growth factor (HGF); 2. to characterize some of the molecular events leading to their differentiation toward a beta-cell-like phenotype; 3. to evaluate the susceptibility of newly differentiated insulin-secreting cells to cytokine-induced apoptosis, a mechanism of beta-cell destruction occurring in type 1 diabetes. We demonstrated that HGF-treated rat pancreatic ductal cell line (ARIP) cells acquired the capability to transcribe the insulin gene and translate its counterpart protein. HGF-treated cells also exhibited a glucose-dependent capability to secrete insulin into the cultured medium. Expression analysis of some of the genes regulating pancreatic beta-cell differentiation revealed a time-dependent transcription of neurogenin-3 and Neuro-D in response to HGF. Finally, we determined the susceptibility to proinflammatory cytokine (PTh1)-induced apoptosis by incubating HGF-treated and untreated ARIP cells with a cocktail of interleukin-1 beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). Such treatment induced apoptotic death, as determined by the TUNEL technique, in about 40% of HGF-treated, insulin-secreting ARIP cells, while untreated ARIP cells were resistant to PTh1-induced apoptosis. In conclusion, we showed that HGF promotes the differentiation of ARIP cells into pancreatic beta-cell-like cells, and that the differentiation toward an insulin-secreting phenotype is associated with the appearance of susceptibility to cytokine-induced apoptosis.
Abstract: Although graft and patient survival after solid organ transplantation have improved markedly in recent years, transplant recipients continue to experience an increased prevalence of cardiovascular disease (CVD) compared with the general population. A number of factors are known to impact on the increased risk of CVD in this population, including hypertension, dyslipidemia and diabetes mellitus. Of these factors, new-onset diabetes after transplantation has been identified as one of the most important, being associated with reduced graft function and patient survival, and increased risk of graft loss. In 2003, International Consensus Guidelines on New-onset Diabetes after Transplantation were published, which aimed to establish a precise definition and diagnosis of the condition and recommend management strategies to reduce its occurrence and impact. These updated 2004 guidelines, developed in consultation with the International Diabetes Federation (IDF), extend the recommendations of the previous guidelines and encompass new-onset diabetes after kidney, liver and heart transplantation. It is hoped that adoption of these management approaches pre- and post-transplant will reduce individuals' risk of developing new-onset diabetes after transplantation as well as ameliorating the long-term impact of this serious complication.
Abstract: OBJECTIVE: Activation-induced cell death (AICD) is a major mechanism in the regulation of peripheral tolerance and its impairment can determine the development of autoimmunity. In the present study, in order to evaluate the role of caspase-3 in type 1 diabetes mellitus (T1DM) AICD, caspase-3 expression was analyzed in peripheral blood lymphocytes from 37 new onset T1DM patients and from 36 normal control subjects (NC) in resting conditions and after anti-Fas-triggered apoptosis. METHODS: Caspase-3 expression was determined by semiquantitative RT-PCR and Western blot. Apoptosis was induced in activated lymphocytes by anti-Fas monoclonal antibody and quantified by flow cytometry and morphological analysis. RESULTS: Caspase-3 mRNA expression was reduced in resting lymphocytes in 18/37 T1DM patients and in 1/36 NC (P < 0.01). Patients studied for both Fas-mediated AICD and caspase-3 mRNA expression revealed that a reduced caspase-3 mRNA expression in resting lymphocytes occurred in all patients showing resistance to Fas-mediated apoptosis (T1DM vs NC, P < 0.02) with the exception of 3 patients who exhibited normal caspase-3 expression levels. Caspase-3 protein analysis confirmed mRNA data and showed an impaired expression of caspase-3 active form in T1DM subjects compared with NC. CONCLUSIONS: Our data show that defective expression and function of caspase-3 in peripheral lymphocytes of T1DM patients may contribute to the development of AICD resistance in type 1 diabetes.
Abstract: In mouse models, CD4+CD25+ T cells are involved in maintenance of peripheral tolerance. In humans, a subset of CD4+CD25+ T cells expressing high levels of CD25 (CD4+CD25high) with characteristics identical to murine CD4+CD25+ was recently described. We evaluated the characteristics of CD4+CD25high T cells in peripheral blood of type 1 diabetic subjects (T1D) and normal controls (NC). In contrast to a previous report, we found no difference in the number of CD4+CD25high and CD4+CD25+ T cells between T1D and NC. We confirmed previous studies that demonstrated that human CD4+CD25high cells can suppress the proliferation of co-cultured CD4+CD25- cells stimulated in conditions of sub-maximal cross-linking by anti-CD3 either with or without anti-CD28. However, we did not observe statistical differences between the normal controls and the chronic diabetic subjects we tested. Culturing of these cell populations did not appear to affect their ability to suppress proliferation in both groups. In conclusion, we found no significant differences in number or in vitro regulatory function of CD4+CD25high in chronic human T1D subjects.
Abstract: OBJECTIVE: Suppressor of cytokine signaling (SOCS) proteins negatively regulate signal transduction of several cytokines. Since cytokines participate in the pancreatic islet damage in type 1 diabetes, the aim of our study was to investigate the expression of SOCS-1, -2 and -3 in isolated human islets, in basal conditions and after exposure, in vitro, to a combination of interferon (IFN)-gamma, interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha cytokines and in control and in type 1 diabetic human pancreata, to establish (i) whether SOCS molecules are constitutively expressed in human pancreatic islets and (ii) whether their expression can be modulated in vitro by proinflammatory cytokines or ex vivo by an islet inflammatory process. METHODS: Gene expression of SOCS-1, -2 and -3 was evaluated by RT-PCR in untreated and cytokine-treated isolated human pancreatic islets and their protein expression by immunohistochemistry in control and in type 1 diabetic human pancreata paraffin-embedded sections. RESULTS: We found that SOCS-1, -2 and -3 mRNA is constitutively, although weakly, expressed in human pancreatic islets, similar to the expression observed in control pancreata by immunohistochemistry. SOCS-1, -2 and -3 mRNA expression was strongly increased in human islets after exposure, in vitro, to IFN-gamma, IL-1beta and TNF-alpha. Accordingly, an intense and islet-specific immunohistochemical staining for all three SOCS was detected in pancreata from type 1 diabetic patients. CONCLUSION: SOCS-1, -2 and -3 genes are constitutively expressed in human pancreatic islets; their expression increases after exposure to proinflammatory cytokines and during an autoimmune inflammatory process, raising the possibility that these molecules act as key regulators of cytokine signaling in pancreatic islets.
Abstract: Islet tyrosine phosphatase 2 (IA-2) is one of the major autoantigens in type 1 diabetes. The aim of this work was to evaluate which IA-2 construct(s) among those usually employed has the highest sensitivity and specificity for detecting IA-2 autoantibodies in autoimmune diabetes and whether the combination of different IA-2 constructs into a single assay allows the detection of immunoreactivities otherwise not detectable by a single construct. For this purpose, we tested the single immunoreactivities of IA-2 FL(aa 1-979), IA-2(BDC)(aa 256-556:630-979), IA-2 IC(aa 605-979), IA-2(aa 256-760), IA-2(aa 761-928), and of 7 combinations of these fragments in the sera of 203 newly diagnosed type 1 diabetic patient (DM: 109 males,94 females, mean age 12.9 +/- 7.5 years) and 43 prediabetic subject (PDM: 20 males, 23 females, mean age 10.3 +/- 6.0 years) sera. IA-2 IC was the single construct that showed the highest sensitivity and specificity both in DM and PDM subjects; however, all of the other IA-2 constructs investigated detected additional immunoreactivities with respect to it. The combined use into the same assay of IA-2 IC, IA-2 FL, and IA-2 (256-760) constructs allowed detection of IA-2 Abs in additional 13.3% DM and 30.4% PDM subjects compared to the single IA-2 IC construct, suggesting this methodology as a new, highly sensitive approach to the study of IA-2 autoimmunity in type 1 diabetes.
Abstract: 'Latent autoimmune diabetes in adults' (LADA) is the term coined to describe adults who have a slowly progressive form of autoimmune or type 1 diabetes that can be treated initially without insulin injections. The diagnosis of LADA is currently based on three clinical criteria: (1) adult age at onset of diabetes; (2) the presence of circulating islet autoantibodies, which distinguishes LADA from type 2 diabetes; and (3) insulin independence at diagnosis, which distinguishes LADA from classic type 1 diabetes. The prevalence of LADA in adults presenting with non-insulin-requiring diabetes is approximately 10%. Recognition of LADA expands the concept and prevalence of autoimmune diabetes, but LADA remains poorly understood at both a clinical and research level. In this perspective, we review the nomenclature, diagnostic criteria, genetics, pathology and therapy of LADA, to arrive at recommendations that might advance knowledge and management of this form of diabetes.
Abstract: AIMS/HYPOTHESIS: Recent observations suggest the involvement of the gastrointestinal tract in the pathogenesis of islet autoimmunity. Thus, the modulation of gut-associated lymphoid tissue may represent a means to affect the natural history of the disease. Oral administration of probiotic bacteria can modulate local and systemic immune responses; consequently, we investigated the effects of oral administration of the probiotic compound VSL#3 on the occurrence of diabetes in non-obese diabetic (NOD) mice. METHODS: VSL#3 was administered to female NOD mice three times a week starting from 4 weeks of age. A control group received PBS. Whole blood glucose was measured twice a week. IFN-gamma and IL-10 production/expression was evaluated by ELISA in culture supernatants of mononuclear cells isolated from Peyer's patches and the spleen, and by real-time PCR in the pancreas. Insulitis was characterised by immunohistochemistry and histomorphometric studies. RESULTS: Early oral administration of VSL#3 prevented diabetes development in NOD mice. Protected mice showed reduced insulitis and a decreased rate of beta cell destruction. Prevention was associated with an increased production of IL-10 from Peyer's patches and the spleen and with increased IL-10 expression in the pancreas, where IL-10-positive islet-infiltrating mononuclear cells were detected. The protective effect of VSL#3 was transferable to irradiated mice receiving diabetogenic cells and splenocytes from VSL#3-treated mice. CONCLUSIONS/INTERPRETATION: Orally administered VSL#3 prevents autoimmune diabetes and induces immunomodulation by a reduction in insulitis severity. Our results provide a sound rationale for future clinical trials of the primary prevention of type 1 diabetes by oral VSL#3 administration.
Abstract: 'Latent autoimmune diabetes in adults' (LADA) is the term coined to describe adults who have a slowly progressive form of autoimmune or type 1 diabetes that can be treated initially without insulin injections. The diagnosis of LADA is currently based on three clinical criteria: (1) adult age at onset of diabetes; (2) the presence of circulating islet autoantibodies, which distinguishes LADA from type 2 diabetes; and (3) insulin independence at diagnosis, which distinguishes LADA from classic type 1 diabetes. The prevalence of LADA in adults presenting with non-insulin-requiring diabetes is approximately 10%. Recognition of LADA expands the concept and prevalence of autoimmune diabetes, but LADA remains poorly understood at both a clinical and research level. In this perspective, we review the nomenclature, diagnostic criteria, genetics, pathology and therapy of LADA, to arrive at recommendations that might advance knowledge and management of this form of diabetes.
Abstract: The homeostatic control of beta-cell mass in normal and pathological conditions is based on the balance of proliferation, differentiation, and death of the insulin-secreting cells. A considerable body of evidence, accumulated during the last decade, has emphasized the significance of the disregulation of the mechanisms regulating the apoptosis of beta-cells in the sequence of events that lead to the development of diabetes. The identification of agents capable of interfering with this process needs to be based on a better understanding of the beta-cell specific pathways that are activated during apoptosis. The aim of this article is fivefold: (1) a review of the evidence for beta-cell apoptosis in Type I diabetes, Type II diabetes, and islet transplantation, (2) to review the common stimuli and their mechanisms in pancreatic beta-cell apoptosis, (3) to review the role of caspases and their activation pathway in beta-cell apoptosis, (4) to review the caspase cascade and morphological cellular changes in apoptotic beta-cells, and (5) to highlight the putative strategies for preventing pancreatic beta-cells from apoptosis.
Abstract: BACKGROUND: Type 1 diabetes results from the destruction of pancreatic beta-cell as a consequence of an autoimmune process. To date, information on the properties of islets isolated from type 1 diabetic patients is very scant. METHODS: Some immunological and functional properties of islets prepared from the pancreas of type 1 diabetic patients were studied shortly after the isolation and after a period of culture in euglycemic condition. RESULTS: Compared to control islets, freshly prepared type 1 diabetic islets released a significantly higher amount of cytokines (pg/mL) into the culture medium (TNF-alpha: 112.9 +/- 5.6 vs 75.6 +/- 24.4; INF-gamma: 286.9 +/- 26.9 vs 58.6 +/- 6.2; IL-10: 41.8 +/- 4.3 vs 10.1 +/- 3.2; TGF-1 beta: 294.0 +/- 20.6 vs 45.1 +/- 3.5); had a significantly higher chemotactic index (1.9 +/- 0.2 vs 1.2 +/- 0.1); showed reduced insulin release (% of insulin content) in response to glucose (2.8 +/- 0.7 vs 5.3 +/- 1.9), arginine (3.0 +/- 0.6 vs 5.6 +/- 1.0), and glibenclamide (2.9 +/- 0.7 vs 5.4 +/- 0.9); and exhibited decreased glucose oxidation capability and diminished mRNA expression of glucokinase, aldolase, pyruvate kinase, and mitochondrial glycerolphosphate dehydrogenase. Ten days after isolation, a normalization of cytokine release (TNF-alpha: 55.7 +/- 2.3; INF-gamma: 53.9 +/- 4.3; IL-10: 8.6 +/- 0.7; TGF-1 beta: 60.7 +/- 12.4) and chemotactic index (1.3 +/- 0.2) were observed. Moreover, there was an improvement of insulin secretion (3.8 +/- 0.3, 4.7 +/- 0.6 and 3.5 +/- 0.2 respectively in response to glucose, arginine, and glibenclamide) and glucose oxidation, and a partial recovery of the measured mRNA expressions. CONCLUSIONS: These novel results, obtained with islets prepared from patients with type 1 diabetes, demonstrate that even after months after diabetes diagnosis, a period of culture of the islets in a more favorable environment has beneficial effects on the islet function.
Abstract: OBJECTIVE: To assess the independent association between the presence of spontaneous echo contrast in the aorta and recent stroke events. METHODS: Two hundred and twenty-four individuals with a diagnosis of recent stroke and 85 control individuals who were examined due to various present/suspected heart diseases were studied through transesophageal echocardiography. The effects of spontaneous contrast in the aorta and the presence of other potential sources of cardiac embolism associated with them were researched and a questionnaire was completed about patients' clinical risk factors at the time of examination. RESULTS: The effects of contrast in the aorta was associated with stroke (OR=2.83; CI = 95%, 1.65-4.46; P<0.001) in the bivariate analysis. In the multivariate analysis, it remained associated with recent stroke (OR=2.05; CI = 90%, 1.10-3.85; P=0.06). Age > 60 years, a history of systemic blood hypertension and smoking, and dyslipidemia were risk factors independently associated with the effects of contrast in the aorta. The presence of a spontaneous contrast effect in the left atrium and Lambl's excrescences were echocardiographic factors independently associated with the effects of contrast in the aorta. CONCLUSION: The effect of contrast in the aorta was independently associated with recent stroke and with its clinical risk factors. These results reinforce the hypothesis that the phenomenon is a predictor of several risk factors.
Abstract: Type 1 diabetes mellitus is a multifactorial autoimmune disease characterized by destruction of insulin producing pancreatic beta cells that results in insulin deficiency and fasting hyperglycemia. It is now well known that the clinical onset of the disease represents the end stage of an immunological process that occurs over a course of months to years. During this period the presence of autoantibodies against different islet antigens can be detected by the use of standardized assays. The rate of beta cell loss is quite variable among different individuals and at onset ketoacidosis represents still a life threatening complication of the disease. The Diabetes Control and Complication Trial (DCCT) has clearly shown that the preservation of beta cell function in type 1 diabetic subjects results in a better metabolic control and significantly reduces the risk of microvascular complications. Consequently, markers of beta cell function represent important tools to make an early diagnosis and to evaluate the impact of new therapies on the natural history of the disease. The present review will focus on clinical markers currently available (intravenous glucose tolerance test, i.v.GTT, oral glucose tolerance test, OGTT, basal and stimulated C-peptide) to assess the beta cell function in type 1 diabetes.
Abstract: Primary adrenal insufficiency (PAI) is clinically evident in one in 8000 individuals. A correct etiological classification is critical for correct disease management. To update the diagnostic criteria for the etiological classification of PAI, a multicentric network was established in Italy, and 222 patients with PAI were studied. Both 21-hydroxylase and adrenal cortex autoantibodies (21OHAb and ACA, respectively) were tested in two independent laboratories on coded samples and found in 65-66% and 58-61% of cases, respectively. Autoimmune polyendocrine syndrome I was diagnosed in 11 of the 222 patients. Of the remaining 211 patients, 38 (18%) had a nonautoimmune form of PAI. In 145 subjects (65%), the presence of adrenal autoantibodies, without signs of other forms of PAI, led to a diagnosis of autoimmune Addison's disease. In six cases (3%), PAI remained idiopathic. Logistic regression analysis showed a 92.2-92.7% probability of correct reclassification for the two 21OHAb assays and 84.5-85.9% for the ACA assays. We conclude that the simultaneous presence of both 21OHAb and ACA permits unambiguous diagnosis of autoimmune Addison's, whereas subjects with low antibody titers should undergo both instrumental and biochemical tests to exclude other causes of PAI. Lastly, we developed a comprehensive flowchart for the classification of PAI for use in routine clinical practice.
Abstract: OBJECTIVE: Peripheral benzodiazepine receptors (PBRs) are part of the mitochondrial permeability transition pore, and their activation may induce cell death. PBRs are expressed in human pancreatic islets, and cytokine-induced damage is accompanied by changes in their properties. We hypothesized that PBRs can have a role in human islet physiopathology, and evaluated the effects of prolonged exposure to two specific PBR ligands, PK11195 and Ro5-4864 on the function and survival of isolated human islets. DESIGN: Isolated human islets were prepared from the pancreas of 25 multiorgan cadaveric donors and incubated for 12 h in the presence of PK11195 or Ro5-4864. Insulin secretion studies and apoptosis experiments were then performed, together with assessment of intracellular pathways involved in islet cell function and survival. METHODS: Islets were prepared by enzymatic digestion and density gradient purification. Insulin secretion was assessed by the batch incubation method, and glucose oxidation was evaluated by the use of D-[U-(14)C]glucose. Apoptosis was studied using the TUNEL technique, ELISA methods, and electron microscopy evaluation. PCR experiments were performed by the use of specific primers. RESULTS: Glucose-stimulated insulin release was significantly lower after exposure to PK11195 than after exposure to Ro5-4864. This was accompanied by reduced glucose oxidation and no major change of insulin or GLUT-1 mRNA expression. Apoptosis was higher in PK11195-exposed islets, and electron microscopy demonstrated the involvement of beta-cells. The apoptotic effects were prevented by bongkrekic acid and low-dose cyclosporin A, which stabilize the mitochondrial membrane, and were associated with no evident change of inducible nitric oxide synthase (iNOS), B-cell leukemia/lymphoma-2 (Bcl-2) or Bcl-2-associated X protein (Bax) expression. Caspase inhibition markedly reduced the amount of apoptosis, and the role of these proteases was confirmed by the increased activity of caspase-3 and caspase-9. CONCLUSIONS: Prolonged binding to PBRs may cause human beta-cells functional damage and apoptosis, a phenomenon which is prevented by stabilizing the mitochondrial membrane; occurs without changes of iNOS, Bax and Bcl-2 mRNA expression; and involves caspase activation. These results suggest an involvement of PBRs in human pancreatic beta-cell function and survival.
Abstract: The contribution of age and/or sex to the transglutaminase (tTG) autoantibody response in celiac disease (CD) is not known. To gain insights into transglutaminase humoral autoimmunity at CD diagnosis, our aim was to characterize the autoimmune response against three tTG constructs [(full-length tTG(a.a.1-687), tTG(a.a.227-687), and tTG(a.a.473-687)] and to investigate into its relationship with CD patients' age and sex. One hundred seventy-five newly diagnosed CD patients (115 females and 60 males), subdivided into different groups according to age and sex, were studied using a serum 35S-radioimmunoassay. We found that among full-length tTG autoantibody-positive CD subjects (175/175), 50.9% (89/175) and 83.4% (146/175) had autoantibodies against tTG(227-687) and tTG(473-687) domains, respectively. Female patients of less than 4 years expressed tTG(227-687)Abs in significantly higher percentage and mean autoantibody titers vs. all other groups investigated, and tTG(473-687)Abs in significantly higher titers with respect to adult female patients. Our data identify a subset of CD patients showing a strong humoral tTG immunoreactivity at diagnosis, thus suggesting that age and sex influence the anti-tTG autoantibody response.
Abstract: In an effort to better understand the phenomenon of lipotoxicity in human beta-cells, we evaluated the effects of 48-h preculture with 1.0 or 2.0 mmol/l free fatty acid (FFA) (2:1 oleate to palmitate) on the function and survival of isolated human islets and investigated some of the possible mechanisms. Compared with control islets, triglyceride content was significantly increased and insulin content and glucose-stimulated insulin release were significantly reduced in islets precultured with increased FFA concentrations. These changes were accompanied by a significant reduction of glucose utilization and oxidation. By cell death detection techniques, it was observed that exposure to FFAs induced a significant increase of the amount of dead cells. Electron microscopy showed the involvement of beta-cells, with morphological appearance compatible with the presence of apoptotic phenomena. FFA-induced islet cell death was blocked by inhibition of upstream caspases and partially prevented by inhibiton of ceramide synthesis or serine protease activity, whereas inhibition of nitric oxide synthesis had no effect. RT-PCR studies revealed no major change of iNOS and Bax mRNA expression and a marked decrease of Bcl-2 mRNA expression in the islets cultured with FFA. Thus, prolonged exposure to FFAs has cytostatic and pro-apoptotic effects on human pancreatic beta-cells. The cytostatic action is likely to be due to the FFA-induced reduction of intraislet glucose metabolism, and the proapoptotic effects are mostly caspase mediated, partially dependent on ceramide pathway, and possibly Bcl-2 regulated.
Abstract: Cytokines produced by immune system cells infiltrating pancreatic islets are candidate mediators of islet beta-cell destruction in autoimmune insulin-dependent diabetes mellitus. After 72 h exposure of human pancreatic islets to a cytotoxic cytokine combination of interleukin 1 beta (50 U/ml), tumor necrosis factor alpha (1,000 U/ml), and interferon gamma (1,000 U/ml), an increase of cell death vs. control islets was demonstrated by TUNEL and cell death detection ELISA method. Islet death was associated with apoptosis and mitochondrial swelling as evidenced by electron microscopy. This effect was correlated with a marked decrease of Bcl-2 mRNA expression (without any major change of Bax mRNA) and a marked increase of inducible nitric oxide synthase mRNA. Since peripheral benzodiazepine receptors constitute the aspecific mitochondrial permeability transition pore, and that it has been suggested to be involved in cytokine-induced cell death, we evaluated the effects of the cytotoxic cytokines on PBR density and mRNA expression. We demonstrated that cytokine treatment of human islets induced an increase of maximum density of (3)H1-(2-chlorophenyl-N-methyl-1-methylpropyl)-3- isoquinolinecarboxamide binding sites, (5,110+/-193 vs. 3,421+/-336 fmol/mg proteins, P<0.05) with no significant change in the affinity constant value (9.45+/-0.869 vs. 8.7+/-1.159 nM). Moreover, an increase of the expression of peripheral benzodiazepine receptor mRNA was observed, suggesting an increased transcription from the coding gene. These results suggest a possible role of peripheral benzodiazepine receptors in the organism response to tissue damage associated with inflammatory mediator production.
Abstract: ICA512/IA-2, a tyrosine phosphatase-like protein, is one of the major autoantigens in type 1 diabetes. Following phage display characterization of ICA512 autoantigenic epitopes, we developed fluid phase autoantibody radioimmunoassays for a series of ICA512 fragments (F1 [amino acids (aa): 761-964], F2A [aa 256-760], F2B [aa 761-928], and F2C [aa 929-979]). With the hypothesis that 'non-diabetes associated' ICA512 autoantibodies would differ from diabetes associated ICA512 autoantibodies in terms of epitopes recognized, we analyzed ten such serum samples (two from normal control individuals, one from a general population subject with transient ICA512 autoantibodies and seven from relatives of patients with type 1 diabetes who had single transient ICA512 positivity). All but one of the 'non-diabetes associated' ICA512 positive samples (9/10) did not react with Fragment 1 which contains the major antigenic epitopes of the molecule that were recognized by almost all (51/52) ICA512 positive new onset patient samples and pre-diabetic relatives (P< 10(-6)). The great majority of samples (44/52) from the new onset patients and pre-diabetic relatives reacted with at least two fragments and 60% (31/52) with three or more fragments. In contrast, only one sample of the ICA512 'non-diabetes associated' sera reacted with multiple fragments (P< 10(-4)). Our findings suggest that diabetes associated anti-ICA512 autoantibodies react with multiple ICA512 epitopes while non-diabetes associated ICA512 autoantibodies may usually represent reactivity of antibodies with determinants of ICA512 unrelated to type 1 diabetes. The ability to distinguish diabetes associated from non-diabetes associated anti-ICA512 autoantibodies should provide prognostic information and more importantly suggests that even with highly specific radioassays positivity may occur unrelated to type 1 diabetes.
Abstract: Autoantigenic epitope mapping represents a critical issue in autoimmune diseases. The islet tyrosine phosphatase-like protein IA-2/ICA512bdc is a major autoantigen in type 1 diabetes (IDDM), but the epitopes responsible for autoantibody binding have been only partially defined. The aim of our study was to identify ICA512bdc epitopes, and in particular mini-epitopes, utilizing a novel strategy for autoimmune diseases. The study was performed in three sequential steps: (1) construction of a lambda-phage surface-displayed ICA512bdc cDNA library with the methodology of tagged random priming with peptides displayed as a fusion to the C terminus of the capsid protein D; (2) affinity selection of the resulting library, followed by immunoscreening, enzyme-linked immunosorbent assay and sequence analysis of positive clones, and (3) radioimmunoprecipitation to detect autoantibodies to the selected clones. This strategy resulted in the identification of two epitopes (IA-2 residues 761 - 964 and 929 - 979), which were recognized by 100 % and 62.9 % ICA512bdc-positive IDDM patients, respectively. Interestingly, the larger clone was detected also by a proportion (16.7 %) of new onset ICA512bdc-negative patients, thus suggesting that this region contains not only the main autoantigenic repertoire of ICA512bdc molecule, but is able to detect IA-2 autoantibodies in even higher percentages of patients. In addition, this study showed the existence of multiple epitopes located in the C-terminal domain of the IA-2 protein, one of which is formed by the 50 C-terminal amino acids, and provided evidence that the strategy used represents a valid tool for identification of epitopes within autoantigenic molecules.
Abstract: Fetal and newborn mammals have a limited ability to mount an immune response, both qualitatively and quantitatively, leading to an increased susceptibility to bacterial or viral infections. The incomplete development in the neonate of both innate and acquired immune system may well explain this increased susceptibility; however, the neonatal immune system, under certain circumstances, can mount an efficient immune response. Various immune-mediated disorders, including autoimmune syndromes, can take place in the early postnatal life, a period during which the immune system acquires key functions and undergoes a complex maturation and education process. Neonatal autoimmune syndromes involving endocrine glands include: IPEX/XLAAD/XPID, neonatal hyperthyroidism, Di George syndrome, ALPS, and Kabuki syndrome.
Abstract: In an effort to better understand the phenomenon of lipotoxicity in human beta-cells, we evaluated the effects of 48-h preculture with 1.0 or 2.0 mmol/l free fatty acid (FFA) (2:1 oleate to palmitate) on the function and survival of isolated human islets and investigated some of the possible mechanisms. Compared with control islets, triglyceride content was significantly increased and insulin content and glucose-stimulated insulin release were significantly reduced in islets precultured with increased FFA concentrations. These changes were accompanied by a significant reduction of glucose utilization and oxidation. By cell death detection techniques, it was observed that exposure to FFAs induced a significant increase of the amount of dead cells. Electron microscopy showed the involvement of beta-cells, with morphological appearance compatible with the presence of apoptotic phenomena. FFA-induced islet cell death was blocked by inhibition of upstream caspases and partially prevented by inhibiton of ceramide synthesis or serine protease activity, whereas inhibition of nitric oxide synthesis had no effect. RT-PCR studies revealed no major change of iNOS and Bax mRNA expression and a marked decrease of Bcl-2 mRNA expression in the islets cultured with FFA. Thus, prolonged exposure to FFAs has cytostatic and pro-apoptotic effects on human pancreatic beta-cells. The cytostatic action is likely to be due to the FFA-induced reduction of intraislet glucose metabolism, and the proapoptotic effects are mostly caspase mediated, partially dependent on ceramide pathway, and possibly Bcl-2 regulated.
Abstract: Studies in rodents have suggested that Th2 and Th3 cytokines can be effective in reducing proinflammatory and Th1 cytokine-induced islet damage. Whether this is the case with human islets and might be due to a direct action of Th2 and Th3 cytokines is not known. In the present study, we evaluated whether Th2 (500 U/ml IL-4 plus 100 U/ml IL-10) or Th3 (5 ng/ml TGF-1beta) cytokines may prevent the derangements induced on isolated human islets by prolonged (12 or 72 h) exposure to combined proinflammatory (50 U/ml IL-1beta, 1000 U/ml TNF alpha) and Th1 (1000 U/ml interferon gamma) cytokines. Compared with control islets, cells preincubated for 12 or 72 h with proinflammatory and Th1 cytokines showed a significant decrease of glucose-stimulated insulin secretion and a significant increase of nitrites production. The addition of IL-4 plus IL-10 or TGF-1beta in the medium prevented these cytostatic effects in the 12-h incubation experiments, but not after the 72-h exposure period. IL-1beta, interferon gamma, and TNF alpha caused no major change in either islet cell survival or Bcl-2 and Bax mRNA expression after a 12-h incubation; however, a marked increase in the amount of dead cells, with a major decrease of Bcl-2 mRNA expression, was observed after 72 h. The presence of Th2, but not of Th3, cytokines significantly reduced beta-cell death, without any major effect on Bcl-2 and Bax mRNA expression. These results suggest that Th2 and (at lower extent) Th3 cytokines may have a partial, direct protective effect on isolated human islets exposed to the cytostatic and cytotoxic action of proinflammatory and Th1 cytokines.
Abstract: Studies in rodents have suggested that Th2 and Th3 cytokines can be effective in reducing proinflammatory and Th1 cytokine-induced islet damage. Whether this is the case with human islets and might be due to a direct action of Th2 and Th3 cytokines is not known. In the present study, we evaluated whether Th2 (500 U/ml IL-4 plus 100 U/ml IL-10) or Th3 (5 ng/ml TGF-1beta) cytokines may prevent the derangements induced on isolated human islets by prolonged (12 or 72 h) exposure to combined proinflammatory (50 U/ml IL-1beta, 1000 U/ml TNF alpha) and Th1 (1000 U/ml interferon gamma) cytokines. Compared with control islets, cells preincubated for 12 or 72 h with proinflammatory and Th1 cytokines showed a significant decrease of glucose-stimulated insulin secretion and a significant increase of nitrites production. The addition of IL-4 plus IL-10 or TGF-1beta in the medium prevented these cytostatic effects in the 12-h incubation experiments, but not after the 72-h exposure period. IL-1beta, interferon gamma, and TNF alpha caused no major change in either islet cell survival or Bcl-2 and Bax mRNA expression after a 12-h incubation; however, a marked increase in the amount of dead cells, with a major decrease of Bcl-2 mRNA expression, was observed after 72 h. The presence of Th2, but not of Th3, cytokines significantly reduced beta-cell death, without any major effect on Bcl-2 and Bax mRNA expression. These results suggest that Th2 and (at lower extent) Th3 cytokines may have a partial, direct protective effect on isolated human islets exposed to the cytostatic and cytotoxic action of proinflammatory and Th1 cytokines.
Abstract: BACKGROUND: The potential benefits of islet xenografting in type 1 diabetes include the intriguing, but still unanswered, possibility that the grafted xenoislets may be less subjected to human autoimmune attack. Cytokines may play a major role in the pathogenesis of autoimmune diabetes by causing impairment of insulin release and pancreatic islet cell toxicity. METHODS: We compared insulin secretion, islet cell death and survival, inducible nitric oxide synthase (iNOS) mRNA expression, nitrite production, and Bcl-2 and Bax mRNA expression in isolated human and large mammal (bovine) islets exposed to 50 U/ml recombinant human interleukin-1, 1,000 U/ml recombinant human tumor necrosis factor-alpha and 1,000 U/ml recombinant human interferon-gamma. RESULTS: After 24-hr exposure, a marked decrease of glucose-stimulated insulin secretion was observed with human, but not with bovine islets. After 48-hr exposure, human, but not bovine, pancreatic islets showed a significantly higher percentage of apoptotic cells compared to controls. Treatment of human islets with human cytokines induced up-regulation of iNOS mRNA, increased levels of nitrites, and down-regulation of Bcl-2 mRNA, with unchanged levels of Bax mRNA. These parameters were not affected by cytokines in bovine islets. CONCLUSIONS: Bovine islets are less susceptible than human islets to the effects of human cytokines, which may be a potential advantage of xenotransplantation.
Abstract: BACKGROUND: The potential benefits of islet xenografting in type 1 diabetes include the intriguing, but still unanswered, possibility that the grafted xenoislets may be less subjected to human autoimmune attack. Cytokines may play a major role in the pathogenesis of autoimmune diabetes by causing impairment of insulin release and pancreatic islet cell toxicity. METHODS: We compared insulin secretion, islet cell death and survival, inducible nitric oxide synthase (iNOS) mRNA expression, nitrite production, and Bcl-2 and Bax mRNA expression in isolated human and large mammal (bovine) islets exposed to 50 U/ml recombinant human interleukin-1, 1,000 U/ml recombinant human tumor necrosis factor-alpha and 1,000 U/ml recombinant human interferon-gamma. RESULTS: After 24-hr exposure, a marked decrease of glucose-stimulated insulin secretion was observed with human, but not with bovine islets. After 48-hr exposure, human, but not bovine, pancreatic islets showed a significantly higher percentage of apoptotic cells compared to controls. Treatment of human islets with human cytokines induced up-regulation of iNOS mRNA, increased levels of nitrites, and down-regulation of Bcl-2 mRNA, with unchanged levels of Bax mRNA. These parameters were not affected by cytokines in bovine islets. CONCLUSIONS: Bovine islets are less susceptible than human islets to the effects of human cytokines, which may be a potential advantage of xenotransplantation.
Abstract: Studies in the NOD mouse model suggest that development of diabetes mellitus type I can be prevented and established disease cured by deviation towards a Th2-type response. To obtain insight into whether this approach may be applicable to human disease, we investigated the Th1/Th2 cytokine balance in pancreatic tissue from two patients with diabetes of recent onset (Case 1, accidental death; Case 2, ketoacidosis). Using the polymerase chain reaction to amplify reverse-transcribed cDNA, signals for actin and CD36 confirmed mRNA integrity and the presence of T cells in pancreatic tissue from both patients and from a control. IFN-gamma cDNA was also amplified from all three tissues. However, IL-4 (but not IL-10) cDNA, was amplified from the pancreas of Case 1. Conversely, IL-10 (but not IL-4) cDNA was amplified from the the pancreas of Case 2. The control pancreas yielded specific signals for both IL-4 and IL-10. Our data extend the limited database on Th1 and Th2 cytokine expression in human pancreatic tissue from recently diagnosed diabetics. Moreover, together with previous observations, our findings raise the possibility that the lack of both IL-4 and IL-10 may be associated with the development of IDDM in humans.
Abstract: BACKGROUND: In Caucasians, a small number of Type 1 diabetic patients do not show evidence of humoral islet autoimmunity at disease onset, at least with common screening procedures. In African- and Hispanic-American diabetic children at time of diagnosis, many show no evidence of autoimmunity but have an atypical clinical form of the disease. According to the recent American Diabetes Association classification, this subgroup of autoantibody negative patients is referred to as Type 1b diabetic subjects. In the present study, a homogeneous Caucasian Type 1 diabetic clinic-based cohort has been evaluated at diagnosis using a large panel of diabetes-related antibodies and then characterized for various genetic features in order to identify newly diagnosed Type 1 diabetics who are potentially autoantibody negative, i.e. possibly referrable to as idiopathic Type 1b diabetes. METHODS: Newly diagnosed Type 1 diabetic patients of Italian origin (n=141, mean age 12.0+/-7.6 years) were tested for anti-islet cell, anti-insulin, anti-65 kDa isoform of glutamic acid decarboxylase and anti-amino acid residues 256-979 of the tyrosine-phosphatase IA-2 molecule autoantibodies (Step 1). Only those patients found to be autoantibody negative were tested for anti-disialo-ganglioside GD3, anti-thyroid peroxidase, anti-thyroglobulin, anti-21-OH hydroxylase, anti-gastric parietal cell and anti-transglutaminase antibodies (Step 2). Sera negative for the presence of these six autoantibodies as well were characterized in terms of HLA DRB1, DQB1 and CTLA-4. RESULTS: Six out of 141 subjects (3.5%) were autoantibody negative in the first step of the study and five out of six in the second. These five autoantibody negative patients underwent genetic analysis. Three of them had at least one Type 1 diabetes-related high risk HLA haplotype (3/141, 2.1%) while the remaining two cases showed neutral (DR5-DQB1*0301/DR5-DQB1*0301) or strongly protective (DR2-DQB1*0602/DR2-DQB1*0602) HLA genotypes, respectively (2/141, 1. 4%). CONCLUSIONS: Clinically defined Type 1 diabetic patients with no sign of autoimmunity do exist in a Caucasian population. These patients (2 out of 141) that cannot be classified as Type 1a diabetic patients lack clinical characteristics of Type 1b diabetes and have to be reconsidered for a more appropriate ADA classification. These data suggest the need of further large population-based studies to understand if Type 1b diabetes really occurs in a Caucasian population. The patient with a strongly protective HLA genotype is particularly interesting considering that among Caucasians only a few sporadic cases with Type 1 diabetes and DQB1*0602, have been reported, none of whom was homozygous at DQB1 locus.
Abstract: BACKGROUND: Certain clinical conditions are associated with inappropriately high levels of circulating glucagon. To date, little information is available about the direct effects of prolonged exposure of human islet cells to pancreatic glucagon. In the present study we evaluated the function, antigenicity and survival of human islets exposed for 24 h to human pancreatic glucagon. METHODS: We prepared human islets of Langerhans by collagenase digestion and density-gradient purification, incubated them for 24 h with 44 or 430 pmol/l pancreatic glucagon at physiological (5.5 mmol/l) glucose level, and evaluated their insulin release function, which was then compared with that obtained from islets kept at high (11.1 mmol/l) glucose concentration. In addition, aliquots of the islets were evaluated to assess their chemotactic properties towards human monocyte-macrophage cells, and their potency to induce cytokine release from human lymphocytes. Finally, survival of the islet cells cultured under varying conditions was evaluated, and an assessment was performed of mRNA expression of Bcl-2 and Bax proteins. RESULTS: The insulin secretion results demonstrated that, compared to the control islets, the islets previously exposed to either 44 or 430 pmol/l glucagon exhibited changes in insulin release in response to glucose, consisting of augmented secretion at low glucose challenge, and no further significant increase at high glucose stimulation, similar to the effects observed with islets pre-cultured with high glucose. These effects were reversible, as documented by the recovery of normal islet sensitivity to glucose after an additional 24-h culture in medium lacking glucagon. Compared to control islets, the culture medium from islets pre-cultured with high glucagon or high glucose showed an increased chemotactic potency towards human monocyte-macrophage cells. In addition, human lymphocytes released a greater amount of tumour necrosis factor alpha when co-cultured with the islets pre-exposed to high glucagon or high glucose, whereas no significant difference was observed (in comparison with control islets) as regards the release of gamma-interferon, interleukin-2 and interleukin-10. The TUNEL technique and RT-PCR showed, respectively, no major difference in cell survival and expression of mRNA encoding for Bcl-2 and Bax protein between control islets and islets kept for 24 h in the presence of high glucagon or high glucose. CONCLUSIONS: Our results show that in vitro exposure of human islets to pancreatic glucagon for 24 h causes changes in the function and antigenicity of isolated human islets that are similar to the changes observed after pre-culture with increased glucose levels. Under our experimental conditions, these changes were not accompanied by any evidence of cytotoxicity.
Abstract: The aims of this study were to evaluate in an autoimmune diabetes animal model [low-dose streptozotocin (LD-STZ) mouse] (a) the efficacy of a prophylactic insulin treatment as a diabetes prevention tool, and (b) its possible mechanisms through both the insulitis evaluation and islets antigen expression. Diabetes was induced in male C57Bl6/J mice with STZ (50 mg/kg b/w for five consecutive days); insulin (1 U/day) was injected subcutaneously for ten consecutive days before the induction of diabetes and for a further ten days. Seventy-one male C57Bl6/J mice were grouped as follows: Group 1 (n = 25) made diabetic with i.p. STZ, Group 2 (n = 21) made diabetic with i.p. STZ and injected subcutaneously with insulin, Group 3 (n = 15) injected with insulin, while Group 4 (n = 10) comprised normal animals as controls. The animals of each group were killed at two intervals: half of them at day 12 and the remainder at day 24 from the beginning of the STZ treatment. A significant reduction of glycemia levels and insulitis severity was observed between mice of Group 1 vs. Group 2 at day 12 and day 24. Down-regulation of islet antigen expression (insulin, A2B5, GM2-1, ICA Ag) was achieved even without a complete metabolic suppression of beta-cell activity. In conclusion, prophylactic insulin treatment is effective to reduce glycemia levels and insulitis severity and down-regulates islet antigen expression in the LD-STZ model.
Abstract: The target molecules of the T-cell response in type 1 diabetes, despite their pathogenic importance, remain largely uncharacterized, especially in humans. Interestingly, molecules such as insulin and glutamic acid decarboxylase (GAD) have been shown to be a target not only of autoantibodies, but also of autoreactive T-lymphocytes both in man and in the non-obese diabetic (NOD) mouse. In the present study we aimed to determine the existence of a specific T-cell response towards the insulinoma-associated protein 2 (IA-2) islet tyrosine phosphatase, a recently identified autoantigen which is the target of autoantibodies strongly associated with diabetes development. Human recombinant IA-2 produced in Escherichia coli, was tested for its reactivity with peripheral blood lymphocytes obtained from 16 newly diagnosed type 1 diabetic patients and from 25 normal controls, 15 of whom were HLA-DR-matched. A T-cell proliferation assay was performed in triplicate employing freshly isolated cells in the absence or in the presence of the antigen to be tested (at two different concentrations: 2 microg/ml and 10 microg/ml). A specific T-cell proliferation (defined as a stimulation index (S.I.) >/=3) was observed against IA-2 used at a concentration of 10 microg/ml (but not of 2 microg/ml) in 8/16 diabetic patients, in 1/15 HLA-DR-matched control subjects (P<0.01 by Fisher exact test) and in 0/10 of the remaining normal individuals. A statistically significant difference (P<0.003 by Mann-Whitney U test) was also observed in S.I. values between patients (3.1+/-1.4) and HLA-DR-matched controls (1.7+/-0.54) employing IA-2 at a concentration of 10 microg/ml. However, when IA-2 was used at a concentration of 2 microg/ml, the difference in S. I. between patients (1.65+/-0.8) and controls (1.0+/-0.3) did not reach statistical significance. In conclusion, these data show the presence of a specific, dose-dependent T-lymphocyte response against the IA-2 islet tyrosine phosphatase at the onset of type 1 diabetes. Consequently, this molecule appears to be a target not only at the B-lymphocyte but also at the T-lymphocyte level, reinforcing the potential pathogenic role of this autoantigen in the islet destructive process.
Abstract: OBJECTIVE: To evaluate the existence of beta-cell differentiation and proliferation in the low-dose streptozotocin (ld-STZ) mouse model of autoimmune diabetes. DESIGN: We studied the expression of Reg protein and cytokeratin 20 (CK20), the presence of proliferative phenomena (judged by the incorporation of bromodeoxyuridine (BrdU)), and the co-expression of Reg, CK20 or BrdU with insulin. MATERIALS AND METHODS: Diabetes was induced in male C57Bl6/J mice by administration of ld-STZ. The animals were killed at days 10 and 23 from the beginning of the induction of disease. Five animals were used at each time point and each group was evaluated for blood glucose concentrations, insulitis, expression of Reg and CK20 pancreatic proteins and BrdU incorporation, together with staining for insulin by immunohistochemistry and laser confocal microscopy. RESULTS: All mice treated with ld-STZ were hyperglycemic and histological investigation showed a mild or severe insulitis both at day 10 and at day 23. At day 10, immunochemistry revealed an intense expression of Reg and CK20 in pancreatic ducts in ld-STZ mice, but not in control mice. Reg and CK20 immunoreactive cells were also positive for insulin. In contrast, at day 23, pancreatic sections reacted weakly with anti-Reg and anti-CK20 antibody; co-localization with insulin was observed for both Reg and CK20. The incorporation of BrdU was observed only in insulin-positive cells in pancreatic sections from mice killed at day 10. CONCLUSIONS: These observations show an islet regeneration mechanism in response to an autoimmune attack, and that the ld-STZ mouse is a suitable model in which to evaluate intervention strategies.
Abstract: The pancreatic islet monosialo-ganglioside (GM2-1), an autoantigen in insulin-dependent diabetes mellitus (IDDM) recently shown to be the target of autoantibodies associated with diabetes development in relatives of IDDM patients, is islet specific within the pancreas, and its expression is metabolically regulatable. In the present study we sought to establish 1) whether GM2-1 is beta-cell specific, and 2) its intracellular localization. To this end, we analyzed the pattern of ganglioside expression in highly purified beta- and non-beta-cells isolated from rat islets. In addition, ganglioside levels were determined in subcellular fractions of a rat beta-cell line (INS). No qualitative or quantitative difference was found in the pattern of ganglioside expression between beta and non-beta rat islet cells, with GM3, GM2-1, and GD3 gangliosides expressed in both cell populations. Within INS cells, GM2-1 ganglioside was expressed in the fraction containing secretory granules and, to a lesser extent, in plasma membranes; GM3 was expressed in secretory granules, whereas GD3 was found only in plasma membranes. These data indicate that the GM2-1 autoantigen is not beta-cell specific within the islets, in accordance with the observation that this molecule is a target of islet cell autoantibodies that bind to the whole pancreatic islet. Interestingly, this autoantigen is present in secretory granules similarly to other autoantigens in IDDM (insulin, carboxypeptidase H, 38-kDa protein, etc.), suggesting that the autoimmunity to the components of this organelle may be central to the pathogenesis of the disease.
Abstract: Type 1 diabetes mellitus is a disease caused by the autoimmune destruction of insulin-producing pancreatic beta-cells that takes place in genetically prodisposed individuals. Autoantibodies and autoreactive T lymphocytes reacting with islet target molecules or protein of glycolipid nature have been shown in the circulation of individuals and of animal models of type 1 diabetes (NOD mouse and BB rat) before and at the onset of the disease. As far as autoantigens of glycolipid nature is concerned, gangliosides such as GT3, GD3 and especially GM-1, have been shown to be target of autoantibodies associated to autoimmune diabetes. Of particular interest is the islet-specific monosialo-ganglioside GM2-1, which is target of an autoimmune response highly associated to future progression to diabetes development in first degree relatives of type 1 diabetic individuals. This molecule is recognized by IgG autoantibodies which have been detected before the appearance if clinical diabetes both in man and in the NOD mouse, representing a novel marker of beta-cell autoimmunity.
Abstract: We used random peptide libraries displayed on phage to search for ligands to insulin dependent diabetes mellitus-related antibodies and were able to identify several candidate disease-related peptides. One of them, clone 92, showed a significant difference in the frequency of reactivity with the sera of patients and normal controls. Human immunoglobulins immunopurified on phage 92 specifically stained the islets on human pancreatic sections. When injected into rabbits, the selected peptide elicited antibodies that also stained human and rat pancreatic sections, with a pattern similar to that observed with immunoglobulins purified from the sera of patients. No reactivity was observed in other tissues. Our results indicate that the peptide identified in this work mimics a novel, diabetes-related self-antigen.
Abstract: This paper describes a simple, rapid, routine method to detect anti-GAD65 autoantibodies by a solid-phase radioimmunoassay using human recombinant GAD65 coated microwells and 125I-protein A to reveal antibody binding. Both recombinant and radiolabelled proteins are commercially available. This new method was validated by investigating the presence of GAD65 autoantibodies in two different studies (A and B); the first including subjects originating from our own case histories (group A sera), the second made up of recoded subjects and standards sent to our lab by the Second International GAD Antibody Workshop organizers (group B sera). In study A we tested sera from 52 normal subjects, 25 newly diagnosed type 1 diabetics and 3 stiff man syndrome (SMS) subjects detecting GAD65 autoantibodies in 72% of IDDM and 100% of SMS patients. In study B we tested (in blind fashion) 89 recoded sample sera or standards that were part of the larger group used in the Second International GAD Antibody Workshop, finding GAD65 autoantibodies in 3.3% of healthy control subjects (1/30), 60% of IDDM patients (18/30), 100% of ICA + nondiabetic subjects (3/3) but in none of 4 nondiabetic patients with Graves disease. Comparing our solid-phase RIA results with those published for the same sera from the Second International GAD Antibody Workshop we obtained for our method a sensitivity of 85.7%, a specificity of 93.9% and a consistency of 100%. These result indicate that our assay, which is based on commercially available reagents, should be a useful tool for the detection of GAD65 autoantibodies in large scale studies.
Abstract: The GM2-1 islet ganglioside has been sequenced, found to be a novel ganglioside structure with a sialic acid moiety in the terminal position and two residues of non-acetylated galactosamine and also shown to be a target of autoantibodies in a subset of ICA+ relatives of type 1 diabetic patients who subsequently progressed to the overt disease. In the present study we determined whether antibodies to GM2-1 or to other pancreatic gangliosides (a) are also expressed at disease onset and (b) are correlated with other diabetes-associated autoantibodies. Pancreatic gangliosides were extracted from human pancreas and purified by thin layer chromatography (TLC). Anti-ganglioside autoantibodies were determined using an indirect immunoperoxidase technique performed directly on TLC plates in the following groups of patients: (a) newly diagnosed type 1 diabetic subjects before insulin therapy (n = 45); all were tested for GAD65 autoantibodies in a fluid-phase RIA using 35S-methionine-labelled recombinant human GAD65. Of these patients, 24 were also tested for insulin autoantibodies (IAA) by a competitive fluid phase radioimmunoassay and 21 were tested for GAD67 reactivity. (b) Forty-two age- and sex-matched normal control subjects. Autoantibodies to GM2-1, but not to other pancreatic gangliosides (GM3, GD3, GD1a), were expressed in 31 of 45 new-onset type 1 diabetic subjects and in one of 42 normal controls (P < 0.01), while anti-GAD65, IAA and anti-GAD67 were found in 31 of 45, 12 of 24 and three of 21 patients respectively, but not in the control group of subjects. Interestingly, occurrence of GM2-1 autoantibodies was significantly correlated (P < 0.005) with positivity for GAD65 autoantibodies, but not for IAA or GAD67 autoantibodies. It is of note that both GAD and gangliosides are mainly expressed in islets and in neuronal tissues and, therefore, type 1 diabetes may be regarded as a neuroendocrine autoimmune disease.
Abstract: In the present study we have evaluated the expression of different beta-cell markers, islet molecules and auto-antigens relevant in diabetes autoimmunity by a human insulinoma cell line (CM) in order to define its similarities with native beta cells and to discover whether it could be considered as a model for studies on immunological aspects of Type 1 diabetes. First, the positivity of the CM cell line for known markers of neuroendocrine derivation was determined by means of immunocytochemical analysis using different anti-islet monoclonal antibodies including A2B5 and 3G5 reacting with islet gangliosides, and HISL19 binding to an islet glycoprotein. Secondly, the expression and characteristics of glutamic acid decarboxylase (GAD) and of GM2-1 ganglioside, both known to be islet autoantigens in diabetes autoimmunity and expressed by human native beta cells, were investigated in the CM cell line. The pattern of ganglioside expression in comparison to that of native beta cells was also evaluated. Thirdly, the binding of diabetic sera to CM cells reacting with islet cytoplasmic antigens (ICA) was studied by immunohistochemistry. The results of this study showed that beta cell markers identified by anti-islet monoclonal antibodies A2B5, 3G5 and HISL-19 are expressed by CM cells; similarly, islet molecules such as GAD and GM2-1 ganglioside are present and possess similar characteristics to those found in native beta cells; the pattern of expression of other gangliosides by CM cells is also identical to human pancreatic islets; beta cell autoantigen(s) reacting with antibodies present in islet cell antibodies (ICA) positive diabetic sera identified by ICA binding are also detectable in this insulinoma cell line. We conclude that CM cells show close similarities to native beta cells with respect to the expression of neuro-endocrine markers, relevant beta cell autoantigens in Type 1 diabetes (GAD, GM2-1, ICA antigen), and other gangliosides. Therefore, this insulinoma cell line may be considered as an ideal model for studies aimed at investigating autoimmune phenomena occurring in Type 1 diabetes.
Abstract: Phage display technology represents a powerful tool for the identification of peptides reacting with disease-related antibodies present in human sera. The application of this technology to type 1 diabetes could provide a set of novel reagents for diabetes prediction and could also lead to the identification of novel autoantigens or even of environmental factors possibly causing the disease. In the present study, sera of prediabetic and high risk individuals were used to select candidate peptides from phage-displayed random peptide libraries. Diabetes specific phage clones were then identified from these through screening and counter screening, using sera from diabetic and non-diabetic individuals. The results presented in this paper demonstrate the feasibility of this methodology to identify peptides reacting preferentially with antibodies present in the serum of diabetic patients.
Abstract: Recently, the GM2-1 pancreatic islet ganglioside, proposed as a potential autoantigen in type I diabetes autoimmunity, has been biochemically characterized and found to be a novel ganglioside structure. In the present study, we aimed to determine whether an autoimmune response toward this novel islet molecule is 1) present in type I diabetes and is specifically directed against this molecule and not to gangliosides in general and 2) predictive of disease in high-risk subjects. To this end, the following patients have been studied: 1) 24 newly diagnosed type I diabetic subjects, 20 islet cell autoantibody (ICA)-negative first-degree relatives of type I diabetic subjects, and 25 age-matched normal control individuals; and 2) 31 prospectively evaluated ICA+ first-degree relatives of type I diabetic subjects who were followed for up to 10 years, during which 14 of them developed type I diabetes. A direct assay for autoantibodies to GM2-1 and to other pancreatic gangliosides (GM3, GD3, GD1a) was developed using an indirect immunoperoxidase technique performed directly on thin layer chromatography plates. Anti-GM2-1 autoantibodies (all belonging to the IgG class) were expressed in a high percentage of newly diagnosed type I diabetic subjects (71%), while no significant difference was found in the expression of antibodies directed against other pancreatic gangliosides (GM3, GD3, GD1a) among the different groups studied. Anti-GM2-1 autoantibodies were also present in ICA+ relatives (64%) (P < 0.001 vs. control subjects and ICA-relatives): in this group, life table analysis of progression to diabetes showed that anti-GM2-1 autoantibodies were significantly (P < 0.001) associated with disease, occurring in all relatives developing type I diabetes within 5 years and thus identifying a cohort of ICA+ subjects with markedly increased diabetes risk.
Abstract: Type 1 diabetes mellitus (IDDM) is a disease caused by the autoimmune destruction of insulin-producing pancreatic beta cells that takes place in genetically predisposed individuals. The results of the studies performed so far during the search for "the target antigen" in beta cell autoimmunity have indicated that, unlike many autoimmune disorders, type 1 diabetes appears to be the result of an autoimmune response to a multiplicity of autoantigens. Autoantibodies and autoreactive T lymphocytes reacting with islet target molecules of protein or glycolipid nature have been shown in the circulation of individuals and of animal models of type 1 diabetes (NOD mouse and BB rat) before and at the onset of the disease. In the present article we have reviewed the data available on the antigenic determinants in type 1 diabetes, with particular reference to those recognized by autoantibodies which represent the best available predictive marker of future disease development in large scale screening studies.
Abstract: Insulin dependent (type 1) diabetes mellitus appears to be a genetically determined autoimmune disease. Gangliosides have been implicated in type 1 diabetes as antigenic determinants recognized by islet cell antibodies (ICA) and shown to be able to modulate autoimmune phenomena in experimental diabetes. In order to explore in type 1 diabetes the humoral immune reactivity against gangliosides, taking into account their pancreatic localization and molecular characteristics, antibodies to gangliosides GM3, GM2, GM1, GD3, GD1a, GD1b, and GT1b have been investigated in sera from new onset type 1 diabetics and relatives of type 1 diabetic patients with or without insulin (CIAA) and/or islet cell autoantibodies. Using a purposefully designed sensitive ELISA method we found that presence of antibodies directed against the pacreatic disialo-ganglioside GD3 in a significant percentage of newly diagnosed type 1 diabetics (p < 0.001 vs normal controls) but not in CIAA and/or ICA positive relatives of type 1 diabetics. These findings confirm the involvement of gangliosides in autoimmune phenomena related to type 1 diabetes and suggest disialo-ganglioside GD3 as target of a humoral immune response associated with the onset of insulin-dependent diabetes.
Abstract: Recent studies have indicated that GM2-1, a pancreatic islet monosialo-ganglioside, is an islet-specific component whose expression is metabolically regulable and represents one of the target antigens of cytoplasmic islet cell antibodies. In the present study we aimed to biochemically characterize this molecule using a panel of biochemical techniques including gas chromatography, thin layer chromatography, enzymatic digestion and mass spectrometry. GM2-1 ganglioside was extracted from human pancreas and purified by thin-layer chromatography. Fatty acids in the ceramide (the hydrophobic portion of the molecule), identified by gas chromatography ranged from C16:1 to C24:1. The oligosaccharide chain was enzymatically digested by the sequential application of various exoglycosidases (neuraminidase followed by beta-galactosidase, followed by beta-hexosaminidase) and characterized by gas chromatography identification of the liberated sugars. The following structure was deducted from enzymatic studies and confirmed by mass spectrometry analysis: N-acetyl neuraminic acid-galactose-galactosamine-galactosamine-glucose-ceramide. This is a novel ganglioside structure, not yet described, which shares characteristics with a neuronal glycolipid autoantigen: the LM1 ganglioside. Both GM2-1 and LM1 have a single sialic acid residue in the terminal position, the same migration position on thin layer chromatography and the same number of carbohydrate moieties. In conclusion, we have characterized a novel islet-specific ganglioside molecule with unusual characteristics, such as the terminal sialic acid and the galactosamine residues, which may facilitate both its antigenicity and its involvement in beta-cell autoimmunity.
Abstract: Islet cell antibodies (ICA) bind antigens expressed in both human and rat pancreatic islets. Biochemical studies have shown that an ICA-autoantigen has the properties of a monosialo-ganglioside migrating between GM2 and GM1 standards (GM2-1). We therefore aimed to isolate and characterize gangliosides from whole pancreas and isolated islets of bio breeding diabetes-prone (BB-DP), bio breeding diabetes-resistant (BB-DR), and Wistar Furth (WF) rat strains. Gangliosides were characterized by TLC, HPLC, diode array analysis, and ganglioside-specific staining. ICA binding was studied by indirect immunostaining. The GM2-1 fraction was present in BB-DP, BB-DR, and WF rat pancreases (11, 17, and 9.5%, respectively, of total ganglioside content). Substantial differences were found in other fractions: in BB-DP pancreas, in addition to GM2-1, the main fractions were GM3 (49%), GD1a (12%), GT1b (5%), and a ganglioside migrating between GM1 and GD3 standards (23%), while in BB-DR pancreas the above components were 71, 5.5, 2, and 4.5%, respectively; in WF pancreas, the main fractions were GM3, GD3, GD1a, GT1b and a trisialoganglioside (GT*) migrating above the GT1b standard (42.7, 7, 20.2, 13.8, and 6.8, respectively). A different pattern of ganglioside expression was found in isolated islets of BB-DP, BB-DR, and WF rats: the GM2-1 fraction represented, respectively, 29.1, 30.4, and 31.6% of total ganglioside content; GM3 51.1, 66, and 68.4%. A fraction migrating between GM1 and GD3 standards was present only in BB-DP and BB-DR islets (19.8 and 3.6%, respectively). ICA-positive human sera reacted with pancreas of all rat strains studied, with similar end-point titers. In conclusion, (1) the GM2-1 ganglioside, in the same way as a putative target antigen of ICA, is equally expressed in BB-DP, BB-DR, and WF rat pancreata; and (2) the GM1-GD3 is expressed in higher amounts in BB-DP than in BB-DR pancreas and islets and is absent in WF.
Abstract: Gangliosides have been shown to modulate autoimmune phenomena in experimental diabetes. The effects of a pancreatic ganglioside preparation or of a commercial brain ganglioside mixture on the insulitis and blood glucose levels in the low-dose streptozotocin mouse model of diabetes have been investigated. Fifty-five C57BL/6J male mice were grouped as follows: Group 1 (n = 20) was injected intraperitoneally with repeated low doses of streptozotocin; Group 2 (n = 10) received streptozotocin as above but was also injected with a pancreatic ganglioside preparation equivalent to 2 micrograms sialic acid 2 h before each streptozotocin dose; Group 3 (n = 15) received streptozotocin and brain-derived gangliosides in the same dose as that of pancreatic gangliosides; Group 4 (n = 10) consisted of normal animals. Half of the mice were killed on day 12 and the others on day 24 from the beginning of treatment. On day 12, among the streptozotocin-injected animals only those treated with pancreatic gangliosides remained normoglycaemic, whereas on day 24 all streptozotocin mice were hyperglycaemic. Such a result paralleled the data pertaining to insulitis scores. In conclusion, pancreatic gangliosides have a short-term protective role on the development of diabetes in the low-dose streptozotocin model, an effect therefore linked to tissue-related differences in the glycosphingolipid composition.
Abstract: Recent observations have shown that the presumed target antigen of cytoplasmic islet cell antibodies (ICA) has properties of a monosialo-ganglioside migrating between GM2 and GM1 standards (GM2-1) and that ICA binding is higher in nonobese diabetic (NOD) than in C57BL/10SnJ mouse pancreatic frozen sections. This study aimed to characterize the ganglioside expression in NOD mouse islets in comparison with the control C57BL/10SnJ strain, taking into account possible sex differences, variations with age, and changes after autoimmune beta-cell destruction. Thus, acidic glycolipid composition was analyzed 1) in isolated islets from 11-week-old female and male NOD mice and age-matched female and male C57BL/10SnJ mice, and 2) in whole pancreas of both NOD and control mouse strains at different ages (4, 8, and 18 weeks) and of female NOD mice before and after diabetes onset. The acidic glycolipid GM2-1 is expressed in isolated female NOD islets, male NOD islets, and C57BL/10SnJ mouse islets, but quantitative analysis showed an increased amount of GM2-1 in NOD vs. C57BL/10 islets. GM3 is a ganglioside fraction expressed in female and male NOD mice and not in the C57BL/10 strain, whereas GD3 characterizes the C57BL/10 strain islets. GM2-1 is the sole ganglioside fraction in the whole pancreas to clearly decrease with age in the NOD mouse, and diabetes onset in this strain is associated with a significant decrease in the expression of this component as well as of GM3, whereas other pancreatic ganglioside (GD3, GD1a, and GT1b) levels did not significantly decrease; no age-related ganglioside change was observed in the C57BL/10SnJ mouse. Interestingly, the observed increased ICA binding in NOD islets is paralleled by the increased expression of GM2-1 islet ganglioside, and beta-cell destruction in NOD mice is associated with a significant decrease in the amount of this ganglioside in the pancreas.
Abstract: The development of autoimmune diabetes in the nonobese diabetic (NOD) mouse is controlled by multiple genes. At least one diabetogenic gene is linked to the major histocompatibility complex (MHC) of the NOD and is most likely represented by the two genes encoding the alpha and beta chains of the unique NOD class II molecule. Three other diabetogenic loci have recently been identified in the NOD mouse and are located on chromosomes 1, 3, and 11. In addition to the autoimmune diabetes which is caused by destruction of the insulin-producing beta cells in the pancreas, other manifestations of autoimmunity are seen in the NOD mouse. These include mononuclear cell inflammation of the submandibular and lacrimal glands, as well as the presence of circulating autoantibodies. To determine the effect of the non-MHC diabetogenic genes on the development of autoimmunity, we constructed the NOD.B10-H-2b (NOD.H-2b) strain, which possesses the non-MHC diabetogenic genes from the NOD mouse, but derives its MHC from the C57BL/10 (B10) strain. The NOD.H-2b strain does not develop insulitis, cyclophosphamide-induced diabetes, or spontaneous diabetes. It does, however, develop extensive lymphocytic infiltrates in the pancreas and the submandibular glands that are primarily composed of Thy 1.2+ T cells and B220+ B cells. In addition, autoantibodies are present in NOD.H-2b mice which recognize the "polar antigen" on the insulin-secreting rat tumor line RINm38. These observations demonstrate that the non-MHC genes in the NOD strain, in the absence of the NOD MHC, significantly contribute to the development of autoimmunity. The contribution of a single dose of the NOD MHC to autoimmunity was assessed with a (NOD x NOD.H-2b)F1 cross. Although only approximately 3% of F1 females developed spontaneous diabetes, approximately 50% of both female and male F1 mice developed insulitis, and 25% of females and 17% of males became diabetic after treatment with cyclophosphamide. These data demonstrate that the MHC-linked diabetogenic genes of the NOD mouse are dominant with decreasing levels of penetrance for the following phenotypes: insulitis greater than cyclophosphamide-induced diabetes greater than spontaneous diabetes.
Abstract: RINmRH cells are a cloned cell line derived from a transplantable rat insulinoma. These cells display only some of the differentiated structure/function features of native pancreatic B-cells. In particular, they do not efficiently or reproducibly express islet B-cell surface antigens, which would otherwise render them useful for screening for the presence of anti-islet cell surface antibodies in the serum of suspected diabetic patients or their relatives. This study examines whether sodium butyrate can enhance expression of B-cell differentiation antigens on RIN cells. RIN cells were exposed to 1,2 or 4 mM butyrate for nine days, and cell growth followed. At 1 mM, butyrate inhibited cell growth by 90%. At the higher concentrations, there was a net loss in the number of cells per culture dish. Exposing the cells to 1 mM or 2 mM butyrate for two days, resulted in a 50% increase in cellular insulin content at the expense of a partial (1 mM) or complete (2 mM) loss of stimulated insulin release in response to glyceraldehyde or serine. A concentration of 1 mM butyrate was therefore used for subsequent studies. The binding to RIN cells of a panel of monoclonal antibodies (mAb's) known to bind native islet cells (R2D6, A2B5, A1D2, 3G5) as well as of serum from a diabetic patient known to carry anti-islet cell antibodies, was screened by cytofluorography or by a radio-binding assay. The relative binding affinity of the mAb's was 3G5 greater than A1D2 greater than A2B5 greater than R2D6. Only 2-3% of the cells were bound by the diabetic patient serum.(ABSTRACT TRUNCATED AT 250 WORDS)
Abstract: A large body of data generated during the past two decades has led to the ability to predict the development of Type I diabetes in the majority of relatives of diabetics. In particular we have recently proposed a dual parameter linear model to aid in predicting the onset of diabetes [years to diabetes = 1.5 + .03(IVGTT insulin secretion) - 0.008 (concn of insulin autoantibodies)]. The concentration of insulin autoantibodies in prediabetics appears to remarkably correlate with the age at which diabetes develops and the rate at which islet cell antibody-positive individuals progress to diabetes. Children developing diabetes before Age 5 often express more than 1000 nU/ml of such antibodies with the upper limit of normal of 39 nU/ml. Each prediabetic appears to be set at a characteristic level of insulin autoantibodies which does not consistently vary prior to the development of diabetes. During the prodromal phase preceding diabetes first phase insulin secretion is progressively lost, and the combination of insulin release which appears to reflect beta cell damage and the level of insulin antibodies accounts for more than 75% of the variation in time to diabetes over a 6-year interval. A subset of NOD mice also expresses insulin autoantibodies, and in addition essentially all NOD mice, but not F1 crosses of NOD by BALB/c, have antibodies to a target antigen of a RIN islet line protein (termed "polar antibodies"). In addition patients but not NOD mice have cytoplasmic islet cell antibodies which appear to react with a glycolipid islet target antigen. In the NOD mice the inheritance of disease is multigenic with a gene on chromosome 9, linked to the T cell marker theta, determining the bulk of islet cell destruction. In crosses of NOD mice with a series of normal strains, inheritance overt diabetes is correlated with inheritance of the NOD's unique I-A beta gene, though the bulk of islet destruction and insulitis can occur independent of MHC inheritance. Until the additional genes outside of the MHC, associated with the development of Type I diabetes, are identified for man, the NOD mouse, and the BB rat, one can only speculate concerning pathogenic mechanisms. To date islet cell destruction appears to be independent of polymorphic genes acting at the level of the islet target, and crucially dependent upon bone marrow precursor cells.(ABSTRACT TRUNCATED AT 400 WORDS)
Abstract: Recent biochemical studies have shown that the cytoplasmic islet cell-antibody autoantigen has properties of a monosialoganglioside (GM). To characterize islet glycolipids and ascertain whether islets express unique gangliosides, we determined the pattern of ganglioside expression in whole human pancreas and isolated human islets using high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC). The major gangliosides detected in glycolipid extracts of whole human pancreas were GM3, GD3 (disialoganglioside), and in a lesser amount, a GD1a-comigrating ganglioside. In contrast to whole human pancreas, isolated human islets were found to predominantly express GM3, an acidic glycolipid comigrating with GM2, and a ganglioside with mobility between GM2 and GM1 by both HPLC and HPTLC. Quantitation of the major ganglioside UV peaks seen on HPLC gave the following results. In whole pancreas, GM3 represented 66.7% of total gangliosides detected; an asialoglycolipid comigrating with GM2, 2.0%; a ganglioside migrating between GM2 and GM1, 2.6%; GD3, 22.6%; and a GD1a-comigrating ganglioside, 6.1%. In isolated islets, these components were found at the following levels: GM3, 14.9%; GM2-comigrating glycolipid, 74.2%; a ganglioside migrating between GM2 and GM1, 9.8%; GD3, 1.1%; and the GD1a-comigrating ganglioside, not detectable.
Abstract: Murine monoclonal antibodies (MAbs) HISL-5, -9, and -14, generated after immunization of mice with human pancreatic islet cell preparations, recognize a differentiation antigen expressed by the pancreatic islet cells. These MAbs react strongly with all endocrine cell subtypes of human pancreatic islets, but minimally if at all with the exocrine acinar cells, vascular cells, and stromal connective tissue cells of the pancreas. The antigen is located on the cell surface (plasma membranes), as indicated by immunofluorescence staining of viable cell preparations. Besides the pancreatic islets, HISL-5, -9, and -14 antigenic determinants are also expressed by thyroid follicular cells, parathyroid chief cells, and anterior pituitary cells, other commonly involved targets in organ-specific autoimmune disorders. Preliminary biochemical findings indicated that the MAb-defined epitope(s) is trypsin sensitive and resistant to periodate oxidation and exposure to chloroform-methanol. Further biochemical studies, including single step MAb immunoaffinity chromatographic purification, indicate that the antigen recognized by the MAbs HISL-5, -9, and -14 is a 100 K glycoprotein.
Abstract: Human sera from 51 recent-onset insulin-dependent (type I) diabetic patients and 47 unrelated control subjects were screened for the possible presence of circulating factors reacting with several anti-pancreatic islet monoclonal antibodies (MoAb.ISL) in solid-phase radioimmunoassay methods (the original goal being the detection of anti-idiotypic islet cell antibodies and/or specific islet cell antigen-bearing immune complexes). MoAbs from the parental myeloma cell line and purified immunoglobulins (Igs) from different animal species were controls. Type I diabetic sera showed significantly increased binding to MoAb.ISL-coated wells compared with normal subjects (P less than .001). However, the same sera also tended to show a higher binding to the control (non-islet-related) MoAb. Sera from type I diabetic patients also reacted with horse, bovine, pig, rabbit, and goat IgG. Displacement of the binding has been obtained by F(ab')2 and/or Fc fragments of IgG. Evidence has been obtained regarding a similar reaction with human IgM. All the sera were negative when tested for rheumatoid factor by nephelometry. The circulating antibodies described have been proven to be different from islet cell autoantibodies. An anti-Ig antibody is thus present in the sera of recent-onset diabetic patients and represents an additional immunological phenomenon with possible physiopathological and clinical significance.
Abstract: A recent international workshop documented marked interlaboratory variation in end point titers of standard islet cell antibody (ICA) positive sera. End titers were lower using a modified assay which utilizes fluorescein labeled protein A (ICA-pA) rather than fluoresceinated anti-IgG (ICA-IgG) to detect antibody binding to islets. In this study we sought to compare directly two ICA assays with respect to future development of IDDM. Sera were obtained from 26 prospectively evaluated high risk subjects identified by family screening or history of transient hyperglycemia and 12 normal controls. As expected, end point titers for ICA positive sera were 10 times greater using the ICA-IgG assay than with the ICA-pA assay. However, despite higher end point titers, the ICA-IgG assay failed to detect more 'prediabetics' and showed a prozone effect. Fourteen subjects were positive at a 1:2 dilution using the ICA-pA assay. Only 10 of these 14 were positive at a 1:2 dilution using the ICA-IgG assay but all became positive at greater sera dilutions. No normal controls were positive using either assay. A similar prozone was observed with anti-islet monoclonal antibodies A2B5 and 4F2. Sera from 14 long-standing IDDM patients (where titers of ICA may have decreased relative to time of onset of diabetes) which were negative using ICA-pA were also assayed using ICA-IgG. Five sera positive for ICA-IgG but negative for ICA-pA were identified. In addition two sera in which a prozone effect was seen with ICA-pA were identified.(ABSTRACT TRUNCATED AT 250 WORDS)
Abstract: A major problem in standardization of the islet cell cytoplasmic antibody (ICA) assay is variation in sensitivity of the different human pancreas substrates used in individual laboratories. To circumvent this problem, we have developed an assay that utilizes Wistar-Furth rat pancreas as substrate, an anti-islet monoclonal antibody (A2B5) to identify islets and fluorescein-conjugated protein A to identify patient autoantibodies. Sera from 85 control subjects, 27 type I diabetics, and 17 subjects at high risk for developing type I diabetes were assayed in parallel with our standard ICA assay on human pancreas substrate and with Wistar-Furth rat pancreas as substrate. Two sera from control subjects (2 of 85) were ICA positive with rat pancreas compared to 1 of 85 with human pancreas substrate. Sera from 11 of 27 type I diabetics and 15 of 17 sera from high-risk subjects were ICA positive with either rat or human pancreas substrate. A correlation between the specific islet fluorescence readings on human and rat pancreas sections was found with sera from high-risk and control subjects. Furthermore, end-point titers of an ICA-positive serum were identical with both assays. Finally, incubation of an ICA-positive serum with glycolipids, extracted from either human or Wistar-Furth rat pancreas, blocked subsequent ICA binding. These findings suggest that Wistar-Furth rat pancreas expresses an identical or similar autoantigen to human pancreas.
Abstract: Lymphocytes bearing surface antigens indicating early and full activation have been evaluated, in addition to T cell subsets, in blood samples from diabetic pregnant patients, neonates from diabetic mothers and control groups. The type of diabetes and the trimester of pregnancy were taken into account. Monoclonal antibodies were used to enumerate total T cells, helper/inducer, cytotoxic/suppressor Tlymphocytes and activated mononuclear cells using antibodies binding lymphocyte surface antigens as markers of early lymphocyte activation, and MHC Class II surface antigens as markers of late activation. A decrease in T-helper cells during the third trimester of pregnancy in Type 1 (insulin-dependent) and gestational diabetic patients (p less than 0.02) and a decrease in T-suppressor cells in Type 2 (non-insulin-dependent) diabetic pregnant patients during the third trimester (p less than 0.01) were observed in relation to normal values. As in normal pregnancy, 4F2-positive cells were increased in 48% of diabetic pregnant patients during the second and third trimesters of gestation. Class II-positive cells were increased in almost 60% of Type 1 and gestational diabetic patients during the last trimester of pregnancy in comparison with normal pregnant women and control subjects. A decrease in T-helper cells (p less than 0.02) and a clear increase in 4F2-positive cells (p less than 0.001) and Class II-positive lymphocytes (p less than 0.005) were observed in the infants of diabetic mothers in comparison with control subjects. The maternal cellular immune system, actively altered in pregnancy, is fully activated in a number of Type 1 and gestational diabetic pregnant patients. Activated lymphocytes are even found in the neonates of diabetic mothers, but these do not trigger the events leading to the onset of diabetes in the short term.
Abstract: Insulin antibodies, insulin complexes, T-cell subsets and T-cells bearing surface antigens indicating early activation were studied in 35 and 24 infants of diabetic and of normal mothers respectively, which were compared with normal adult control subjects. Anti-insulin antibodies were evaluated using a modified version of Andersen's method, insulin complexes were assessed by a method developed by us; total T cells, helper/inducer and cytotoxic/suppressor T lymphocytes, and early activated T lymphocytes were determined using the monoclonal antibodies OKT3, OKT4, OKT8 and 4F2 respectively. The presence of insulin antibodies was correlated to macrosomia, hypoglycaemia and respiratory distress syndrome. Insulin-anti-insulin complexes were found in some of the neonates and were likely to have been formed by maternal antibodies and insulin from the neonate. Modifications of T-cell subsets were found in the neonates both of diabetic and of normal mothers. --Despite the presence of these immune abnormalities in some infants of diabetic mothers, the clinical onset of diabetes was not diagnosed in any of the cases studied. Nevertheless, the immunological abnormalities in neonates of diabetic mothers have short-term pathogenetic effects which raises the question of their possible long-term effect.
Abstract: The phenotyping of T-cell subsets and T cells at different stages of activation was performed using a panel of monoclonal antibodies in samples from normal pregnant women at different stages of gestation and in the cord blood of neonates. The data obtained from pregnant women showed a slight decrease in the total number of T cells at the beginning of pregnancy, whereas there was a clear increase in 4F2-positive lymphocytes after a few months of gestation. No significant increase in Class II-positive lymphocytes was observed in normal pregnant women in comparison with adult healthy women. The data from neonates revealed a clear decrease of OKT3- and OKT4-positive cells and an increase of 4F2-positive cells in comparison with control subjects. These data indicate that alerted, but not fully activated, lymphocytes are present in the circulation of both the mother, after the first months of pregnancy, and the neonate. This finding reinforces the concept that during pregnancy there is an activation of certain immune components rather than a general depression of the immune system.
Abstract: The existence of a double catecholaminergic and cholinergic innervation was demonstrated in the human greater saphenous vein. Catecholamine-containing nerve fibres are organized in a network-like plexus localized at the adventitial-medial border. Acetylcholinesterase-containing nerve fibres are arranged in a plexus found at the adventitial-medial border as well. Catecholamine and acetylcholinesterase-containing nerve fibres, while localized in close apposition since they occupy the same portion of the vein, represent two distinct and independent populations of nerve fibres coming likely from the sympathetic and parasympathetic sections of the autonomic nervous system respectively. Our findings demonstrating a close relationship between catecholaminergic and cholinergic nerve fibres within the wall of the human greater saphenous vein offer morphological support to physiological and pharmacological results reported in the literature of a presynaptic control exerted by cholinergic nerves on norepinephrine release at the level of the saphenous vein.
