A Cyclic Altered Peptide Analogue Based on Myelin Basic Protein 87-99 Provides Lasting Prophylactic and Therapeutic Protection Against Acute Experimental Autoimmune Encephalomyelitis.

Mary Emmanouil,Iro Triantafyllakou,Agathi Nteli,Lesley Probert,Vivian Tseveleki,Theodore Tselios

doi:10.3390/molecules23020304

Abstract

In this report, amide-linked cyclic peptide analogues of the 87–99 myelin basic protein (MBP) epitope, a candidate autoantigen in multiple sclerosis (MS), are tested for therapeutic efficacy in experimental autoimmune encephalomyelitis (EAE). Cyclic altered peptide analogues of MBP87–99 with substitutions at positions 91 and/or 96 were tested for protective effects when administered using prophylactic or early therapeutic protocols in MBP72–85-induced EAE in Lewis rats. The Lys91 and Pro96 of MBP87–99 are crucial T-cell receptor (TCR) anchors and participate in the formation of trimolecular complex between the TCR-antigen (peptide)-MHC (major histocompability complex) for the stimulation of encephalitogenic T cells that are necessary for EAE induction and are implicated in MS. The cyclic peptides were synthesized using Solid Phase Peptide Synthesis (SPPS) applied on the 9-fluorenylmethyloxycarboxyl/tert-butyl Fmoc/tBu methodology and combined with the 2-chlorotrityl chloride resin (CLTR-Cl). Cyclo(91–99)[Ala96]MBP87–99, cyclo(87–99)[Ala91,96]MBP87–99 and cyclo(87–99)[Arg91, Ala96]MBP87–99, but not wild-type linear MBP87–99, strongly inhibited MBP72–85-induced EAE in Lewis rats when administered using prophylactic and early therapeutic vaccination protocols. In particular, cyclo(87–99)[Arg91, Ala96]MBP87–99 was highly effective in preventing the onset and development of clinical symptoms and spinal cord pathology and providing lasting protection against EAE induction.

Highlights

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system (CNS) causing demyelination and progressive neuronal damage [1]
The purification was achieved using semi preparative, reverse phase high performance liquid chromatography (RP-HPLC) while the peptide purity was assessed by analytical RP-HPLC and by electron spray ionization mass spectrometry (ESI-MS; Supplementary Materials)
Peptide-binding studies with rodent MHC class II molecules have not been performed for the cyclic analogues, and the possibility that MBP87–99 -based analogues compete with MBP72–85 antigen for MHC class II binding, when co-administered in Lewis rats, cannot be excluded

Summary

Introduction

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system (CNS) causing demyelination and progressive neuronal damage [1]. Altered peptide ligands (APLs) based on the MBP86–95 core epitope, in which primary T-cell receptor (TCR) anchors Lys and Pro at positions 91 and 96, are replaced with Arg and/or Ala, respectively, protecting mice against EAE [15,16] and induce differential activation of human T-cell lines [11]. APL stimulate differential T-cell receptor (TCR) signaling and cellular responses compared to wild-type peptides, and can antagonize [17], anergize [18] or partially activate [19] T cells. They can deviate immune responses away from autoimmune Th1 responses towards allergic Th2 responses, and thereby ameliorate EAE [20,21]. Over the last years our group has been involved in the rational design and synthesis of bioactive mutated cyclic peptides based on the

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Conclusion