Abstract: A major goal of clinical proteomics was to identify biomarkers that can aid in the diagnosis and prognosis of different conditions. These biomarkers will not only assist the clinician in the diagnosis of a disease but they will also give directions as to which therapy may be more appropriate for each patient, thus contributing to the development of personalized medicine. This review discusses the current concepts in urine proteomics aimed at identifying predictive biomarkers that could detect the presence of acute rejection or chronic allograft dysfunction early on and for instance be used to personalize immunosuppressive therapies for kidney transplant patients.
Abstract: The advent of quantitative proteomics opens new opportunities in biomedical and clinical research. Although quantitative proteomics methods based on stable isotope labeling are in general preferred for biomolecular research, biomarker discovery is a case example of a biomedical problem that may be better addressed by using label-free MS techniques. As a proof of concept of this paradigm, we report the use of label-free quantitative LC-MS to profile the urinary peptidome of kidney chronic allograft dysfunction (CAD). The aim was to identify predictive biomarkers that could be used to personalize immunosuppressive therapies for kidney transplant patients. We detected (by LC-M/MS) and quantified (by LC-MS) 6000 polypeptide ions in undigested urine specimens across 39 CAD patients and 32 control individuals. Although unsupervised hierarchical clustering differentiated between the groups when including all the identified peptides, specific peptides derived from uromodulin and kininogen were found to be significantly more abundant in control than in CAD patients and correctly identified the two groups. These peptides are therefore potential biomarkers that might be used for the diagnosis of CAD. In addition, ions at m/z 645.59 and m/z 642.61 were able to differentiate between patients with different forms of CAD with specificities and sensitivities of 90% in a training set and, significantly, of approximately 70% in an independent validation set of samples. Interestingly low expression of uromodulin at m/z 638.03 coupled with high expression of m/z 642.61 diagnosed CAD in virtually all cases. Multiple reaction monitoring experiments further validated the results, illustrating the power of our label-free quantitative LC-MS approach for obtaining quantitative profiles of urinary polypeptides in a rapid, comprehensive, and precise fashion and for biomarker discovery.
Abstract: Despite optimal immunosuppressive therapy, more than 50% of kidney transplants fail because of chronic allograft dysfunction. A noninvasive means to diagnose chronic allograft dysfunction may allow earlier interventions that could improve graft half-life. In this proof-of-concept study, we used mass spectrometry to analyze differences in the urinary polypeptide patterns of 32 patients with chronic allograft dysfunction (14 with pure interstitial fibrosis and tubular atrophy and 18 with chronic active antibody-mediated rejection) and 18 control subjects (eight stable recipients and 10 healthy control subjects). Unsupervised hierarchical clustering showed good segregation of samples in groups corresponding mainly to the four biomedical conditions. Moreover, the composition of the proteome of the pure interstitial fibrosis and tubular atrophy group differed from that of the chronic active antibody-mediated rejection group, and an independent validation set confirmed these results. The 14 protein ions that best discriminated between these two groups correctly identified 100% of the patients with pure interstitial fibrosis and tubular atrophy and 100% of the patients with chronic active antibody-mediated rejection. In summary, this study establishes a pattern for two histologic lesions associated with distinct graft outcomes and constitutes a first step to designing a specific, noninvasive diagnostic tool for chronic allograft dysfunction.
Abstract: BACKGROUND: Sirolimus (SRL) is a potent and specific immunosuppressive drug used in organ transplantation, as basic therapy or in combination with calcineurin inhibitors. Although SRL is a nonnephrotoxic drug, many reports have related its use with the development of proteinuria, especially after conversion. Therefore, the aim of this study was to elucidate the interrelation between early and late SRL administration on the development of glomerular hypertrophy and proteinuria in a model of renal mass reduction (RMR). METHODS: Rats underwent 2/3 cryoablation of the left kidney and subsequent right nephrectomy (n=42) or sham operations (n=29). Two weeks before (early study) or 12 weeks after (late study) surgery, SRL or vehicle was administered three times weekly. Creatinine clearance and proteinuria were determined throughout the study, and a complete histologic analysis was performed at the end of the study. RESULTS: Treatment with SRL had no effect on creatinine clearance, independently of the administration time. Four weeks after RMR, a significant increase in proteinuria was observed. Proteinuria was stabilized after early and late SRL administration, whereas vehicle-treated animals showed a further increase in proteinuria. Glomerular hypertrophy was strongly associated with proteinuria, and early SRL introduction prevented glomerular enlargement. The histologic analysis showed less structural damage in the two groups of animals treated with SRL than in the control group. CONCLUSION: Although early SRL introduction blocked glomerular hypertrophy, SRL treatment revealed the potential to halt progression of proteinuria and histologic damage at any time of administration in a model of RMR.
Abstract: The aim was to study the influence of sirolimus (SRL) on body weight in a rat model and in kidney transplant patients. Wistar rats (15 weeks old) were either treated with vehicle (VEH; n = 8) or SRL (n = 7) 1.0 mg/kg three times per week for 12 weeks. Body mass and food intake were measured weekly. Adipocyte diameter was determined in hematoxylin-eosin stains. The body mass index (BMI) obtained from clinical kidney transplant trials comparing SRL-based with cyclosporine-based therapy was analyzed. Animals: SRL produced a decrease of the weight gain curve. At the end of the study, mean body weight in the SRL group was lower than in the VEH group (356 vs. 507 g, P < 0.01) in spite of comparable food intake normalized for body weight was not different. Mean adipocyte diameter was 36 mum in VEH and 25 mum in SRL rats (P = 0.009). Mean SRL blood trough concentration was 38 ng/ml. Kidney transplant patients: Two years after transplantation, BMI was significantly lower in the SRL-based treatment arm compared to cyclosporine (24.17 +/- 2.99 vs. 25.97 +/- 5.01 kg/m(2), P = 0.031). SRL treatment leads to less body mass. Adipocyte cell diameter was reduced in SRL-treated animals. A possible explanation may be the effects of SRL on metabolic regulation and cell growth.
Abstract: INTRODUCTION: With the resurge of tuberculosis, due to the pandemic of the human immunodeficiency virus and the increase in the number of immunocompromised patients, osteoarticular tuberculosis has increased too. MATERIALS AND METHODS: We report of a 55-year-old patient, with chronic renal failure on haemodialysis, who presented with a painful knee and fever. Culture on Lowënstein-Jensen medium of joint liquid revealed a tuberculous affectation of the proximal tibia. Wide excision was performed, completed with 9 months of tuberculostatic drugs. At 1 year follow-up, the patient was free of symptoms. CONCLUSION: Tuberculous aetiology should be considered in the differential diagnosis of knee arthritis.
Abstract: Baclofen is a centrally acting gamma-ammino butyric acid agonist that is used like muscular relaxant in disorders with spasticity and intractable hiccups. Although encouraging and safe results were provided 5 mg/day in hemodialysis patients, his pharmacokinetic and pharmacodinamic properties are not well known in end stage renal disease. We present here the case of a hemodialysis patient with intractable hiccups who developed baclofen-associated encephalopathy with this recommended dose.
Abstract: The arachidonic acid-derived metabolite 12-(S)hydroxyeicosatetraenoic acid (12(S)-HETE), catalyzed by 12-lipoxygenase (12-LOX, ALOX12), exhibits a variety of biological activities with implications in cardiovascular disease. Previous studies have shown higher urinary excretion of this metabolite in essential hypertension. The aim of this study was to analyze the association of polymorphisms in ALOX12 with hypertension and urinary levels of 12(S)-HETE. We studied 200 patients with essential hypertension (aged 56+/-1 years, mean+/-s.e.m., 97 males) and 166 matched controls (aged 54+/-1 years, 91 males). Out of six polymorphisms in the coding region of ALOX12, only R261Q determined a nonconservative amino-acid change and was evaluated by polymerase chain reaction and restriction digestion. Urinary 12(S)-HETE was measured in Sep-Pack-extracted samples using specific enzyme-linked immunosorbent assay. The distribution of genotypes of the R261Q polymorphism was significantly different between patients and controls: patients 92 (0.46) GG, 84 (0.42) GA, 24 (0.12) AA vs controls 56 (0.34) GG, 78 (0.47) GA, 32 (0.19) AA (P=0.030). On the contrary, no association was observed for two intronic polymorphisms. The urinary excretion of 12(S)-HETE (ng/mg creatinine) was significantly higher in GG homozygous patients (13.0+/-1.5) than in GA (8.2+/-1.8) or in AA (8+/-1.5) patients (P=0.018). These results indicate that a nonsynonymous polymorphism in ALOX12 is associated to essential hypertension and to urinary levels of 12(S)-HETE, thus suggesting a role for this gene in this disease.
Abstract: The use of jugular temporary catheters as vascular access for hemodialysis, entails a risk of various complications. The most frequent problems are the arterial puncture and haematoma. However, there are other less frequent potentially serious complications, which constitute a therapeutic and diagnostic challenge for the nephrologists. We present a case of a patient that developed an acute renal failure in the context of cellulites for E. Coli treated with aminoglycosid, who required renal treatment with haemodialysis. After the placement of a polyurethane double-lumen catheter with ultrasound guidance at the level of the internal jugular vein, arterial blood streaming was observed through the lumen of the catheter. The angiographic study showed the tipo of the catheter placed at the level of the aortic arch. Ultrasound exam clearly despicted the track between the internal jugular vein and the internal carotid artery. An effective closing of the fistula was achieved with the placement of a covered stent-graft with the simultaneous withdrawal of the catheter. Reviewing the literature this is the first reported case of an iatrogenic jugulo-carotid fistula secundary to placement of hemodialysis catheter resolved by the implantation of carotid stent-graft.
Abstract: Symptomatic cytomegalovirus (CMV) infection usually affects immunocompromised patients, such as transplant recipients. From that point of view, the patient with endstage renal disease under maintenance dialysis is considered as immunocompetent. Thus, opportunistic infections, such as CMV infection, is not systematicaly searched in these patients, despite that an impaired cellular immunity has been reported in dialysis patients. We report a case of CMV esophagitis, clinically symptomatic, in a patient endstage renal disease under peritoneal dialysis, without other known immunosuppressive factors and with a good clinical response to gancyclovir treatment.
Abstract: Vascular access-related complications are a frequent cause of morbidity in haemodialysis patients and generate high costs. We present the case of an adult patient with end-stage renal disease and recurrent vascular access thrombosis associated with the prothrombin mutation G20210A and renal graft intolerance. The clinical expression of this heterozygous gene mutation may have been favoured by inflammatory state, frequent in dialysis patients. In this patient, the inflammatory response associated with the renal graft intolerance would have favored the development of recurrent vascular access thrombosis in a adult heterozygous for prothrombin mutation G20210A. In the case of early dysfunction of haemodialysis vascular access and after ruling out technical problems, it is convenient to carry out a screening for thrombophilia.
