Antagonistic Effects of Human Cyclic MBP_87-99Altered Peptide Ligands in Experimental Allergic Encephalomyelitis and Human T-Cell Proliferation

Abstract

The immunodominant myelin basic protein (MBP) peptide comprising residues 87-99 is a self-antigen in multiple sclerosis (MS). In Lewis rats this epitope induces experimental allergic encephalomyelitis (EAE), a demyelinating disease of the central nervous system, and is a model of MS. Structure-activity studies have shown that Lys(91) and Pro(96) residues are important for encephalitogenicity. Replacement of Lys and/or Pro residues with Arg and/or Ala, respectively, results in suppression of EAE. A potent linear altered peptide ligand of the immunodominant sequence MBP(83-99) has been selected for clinical trial (Nat. Med. 2000, 6, 1167, 1176). In the present report, two cyclic analogues, cyclo(91-99)[Ala(96)]MBP(87-99) and cyclo(87-99)[Arg(91), Ala(96)]MBP(87-99) were designed by NMR and molecular modeling data on human MBP(87-99) epitope (Val(87)-His-Phe-Phe-Lys-Asn-Ile-Val-Thr-Pro-Arg-Thr-Pro(99)) and its linear antagonist peptide analogue [Arg(91), Ala(96)]MBP(87-99). These analogues (altered peptide ligands) inhibited EAE in Lewis rats and decreased inflammation in the spinal cord. In addition, the analogue cyclo(87-99)[Arg(91), Ala(96)]MBP(87-99) induced proliferation of human peripheral blood T-cells. These cyclic MBP(87-99) peptide analogues may lead to the design of potent antagonist mimetics for treating MS.

Antigen Processing and Presentation in Multiple Sclerosis

“…By binding directly to MHC in the absence of costimulation, they are expected to induce tolerance to the epitope. Some groups have attempted to increase stability of the tolerizing peptide by circularising it or changing key residues to eliminate proteolytic cleavage sites (Burster et al 2007b;Tselios et al 2002).…”

Design of protease-resistant myelin basic protein-derived peptides by cleavage site directed amino acid substitutions

“…We incubated Mu20 with human blood serum for 24 h and found that Mu20 was stable from degradation by protease activity, suggesting a prolonged stability during in vivo use (data not shown). [26]. These cyclic analogues demonstrated less protease-resistance when lysosomal proteases from THP-1 were used as compared to the linear protease-resistant peptides synthesized by the method described here (data not shown).…”

Conformational analysis of the ΜΒΡ83–99 (Phe91) and ΜΒΡ83–99 (Tyr91) peptide analogues and study of their interactions with the HLA-DR2 and human TCR receptors by using Molecular Dynamics

“…Effort must be made to understand: (a) the forces that determine the folding of the epitope; (b) the conservation of the linearity and extended structure of the altered epitope; (c) the molecular features of the altered epitope that maximize the productive interactions with HLA-DR2 and minimize the contacts with TCR. The linear peptides were prepared on 2-chlorotrityl chloride resin (CLTR-Cl) using the Fmoc/tBu solid-phase methodology [28][29][30][31]. The first N a Fmoc (9-fluorenylmethyloxycarboxyl)-protected amino acid (Fmoc-Pro-OH) was esterified to the resin in the presence of diisopropylethylamine (DIPEA) in dichloromethane (DCM) in 1 h at RT [28][29][30][31].…”

“…The linear peptides were prepared on 2-chlorotrityl chloride resin (CLTR-Cl) using the Fmoc/tBu solid-phase methodology [28][29][30][31]. The first N a Fmoc (9-fluorenylmethyloxycarboxyl)-protected amino acid (Fmoc-Pro-OH) was esterified to the resin in the presence of diisopropylethylamine (DIPEA) in dichloromethane (DCM) in 1 h at RT [28][29][30][31]. DCM/MeOH/DIPEA (85:10:5) was then added and the resulting mixture was stirred for another 10 min at RT.…”

“…NMR spectroscopy is coupled with MD simulations to study the binding motif of the altered peptide epitopes of MBP 83-99 with HLA-DR2 [19][20][21][22][23][24][25][26][27][28][29][30][31].…”