Abstract: Derangement of cellular immunity is central in the pathophysiology of multiple sclerosis (MS) and is often manifested by abnormal cytokine production. We investigated cytokine secretion in peripheral blood mononuclear cells (PBMC) of 18 MS patients and 15 controls and correlated cytokine polarization with the nature of antiorenic stimulus. We synthesized two novel citrullinated peptides, linear [Cit(91), Ala(96), Cit(97)]MBP87-99 and cyclo(87-99)[Cit(91), Ala(96), Cit(97)]MBP87-99 that resulted from citrullination of 91,97 Arg residues in antagonists, linear [Arg(91), Ala(96)]MBP87-99 and cyclo(87-99)[Arg(91), Ala(96)] MBP87-99 peptides. PBMC from MS patients and controls were Cultured with citrullinated peptides, and both peptides caused a Th1 polarization in all MS patients studied. In contrast, culture with noncitrullinated MBP peptides resulted in heterogeneous cytokine secretion that differed between individual patients. Thus, citrullination of self-antigens may potentially trigger disease in susceptible individuals. This finding may open new avenues in drug design of new substances that inhibit citrullination and arrest epitope spreading and worsening of MS.
Abstract: An efficient solid-phase synthesis of the TRH analogue Glp-His(N(im)-Trt)-Hyp-OH is described. N-alpha-Fmoc protected amino acids and DCC/HOBt activation were employed. The bulky and mild-acid-sensitive 2-chlorotrityl resin, utilised as the solid support, completely suppressed dioxopiperazine formation. The tripeptide is a key intermediate in the synthesis of TRH analogues incorporating cis- and trans-4-hydroxy-L-proline. The tripeptide was converted, with inversion of configuration at C-4 of the Hyp residue, to Glp-His(N(im)-Trt)-cHyp lactone in the presence of triphenylphosphine-diethyl azodicarboxylate (TPP-DEAD). One-pot MeOH-TPP-DEAD transesterification of the lactone, followed by N(im)-detritylation, provided Glp-His-cHyp-OMe. This ester gave the corresponding amide and acid on ammonolysis and saponification, respectively. A high-field H-1 NMR investigation of Glp-His-cHyp-OH and its diastereomer Glp-His-Hyp-OH, obtained by N(im)-detritylation of the key tripeptide, showed that the configuration at C-4 of the prolyl residues is critical for the determination of the preferred three-dimensional structure of the molecules.
