Design of Glycopeptides Used to Investigate Class II MHC Binding and T-Cell Responses Associated with Autoimmune Arthritis

Abstract

The glycopeptide fragment CII259–273 from type II collagen (CII) binds to the murine Aq and human DR4 class II Major Histocompatibility Complex (MHC II) proteins, which are associated with development of murine collagen-induced arthritis (CIA) and rheumatoid arthritis (RA), respectively. It has been shown that CII259–273 can be used in therapeutic vaccination of CIA. This glycopeptide also elicits responses from T-cells obtained from RA patients, which indicates that it has an important role in RA as well. We now present a methodology for studies of (glyco)peptide-receptor interactions based on a combination of structure-based virtual screening, ligand-based statistical molecular design and biological evaluations. This methodology included the design of a CII259–273 glycopeptide library in which two anchor positions crucial for binding in pockets of Aq and DR4 were varied. Synthesis and biological evaluation of the designed glycopeptides provided novel structure-activity relationship (SAR) understanding of binding to Aq and DR4. Glycopeptides that retained high affinities for these MHC II proteins and induced strong responses in panels of T-cell hybridomas were also identified. An analysis of all the responses revealed groups of glycopeptides with different response patterns that are of high interest for vaccination studies in CIA. Moreover, the SAR understanding obtained in this study provides a platform for the design of second-generation glycopeptides with tuned MHC affinities and T-cell responses.

Hydroxyethylene isosteres introduced in type II collagen fragments substantially alter the structure and dynamics of class II MHC Aq/glycopeptide complexes

“…The C-terminus on the other hand proved to be much more flexible and did not adopt a stable binding mode during the course of the simulations. This is consistent with previous MD simulations of the system, 10,13 as well as the fact that the minimal epitope required for binding to A q consists of the N-terminal octapeptide Ile 260 -Gln 267 . 7 The S-and R-hydroxyethylene-isosteric glycopeptides 2 and 3 displayed a different dynamic pattern compared to 1, with large variations between the repeated MD simulations (Table 1 and ESI †).…”

“…2). 9,10 Moreover, the galactosylated hydroxylysine at position 264 protrudes out of the binding site and is recognized by the TCR with exquisite specificity. 11 Modification of glycopeptides, through the incorporation of amide bond isosteres, has been used to probe molecular interactions in the MHC/glycopeptide/TCR system.…”

“…13 Furthermore, the dynamics of the complex were found to govern the response from the TCR; complexes that were more rigid than those of A q and 1 resulted in weaker T cell responses. 10,13 In this study, we further explore the molecular interactions in the MHC/glycopeptide/TCR system that are crucial for the development of CIA, and most likely also for RA, by synthesis and evaluation of two additional amide bond isosteres incorporated into glycopeptide 1.…”

Adaptive immune activation: glycosylation does matter

“…By employing a panel of synthetic glycopeptides, it was found that most T-cell hybridomas obtained in collagen-induced arthritis specifically recognize a β- D -galactopyranoside moiety located at Hyl264 of the peptide sequence CII256–270 (refs. 65,66). Further studies showed that the axial hydroxyl group of the galactoside was critical for T-cell activation.…”

Peptide screening to knockdown Bcl-2's anti-apoptotic activity: Implications in cancer treatment

“…2) were attempted to access their inhibitory efficacy on changing chemical states of termini. It has also been reported that glycopeptides could be used as therapeutic agent to design a vaccine [131] and a novel ligand [132]. Therefore, addition of glucose and deoxyglucose fragments was also considered to make IGD tripeptide specific to tumor cells, which have a high demand for glucose [133].…”