The structural basis of MHC control of collagen-induced arthritis; binding of the immunodominant type II collagen 256 – 270 glycopeptide to H-2Aq and H-2Ap molecules

Abstract

The Aq major histocompatibility complex (MHC) class II molecule is associated with susceptibility to murine collagen-induced arthritis (CIA), whereas the closely related H-2Ap molecule is not. To understand the molecular basis for this difference, we have analyzed the ability of H-2Aq and H-2Ap molecules (referred to as Aq and Ap) to bind and present collagen type II (CII)-derived glycosylated and non-glycosylated peptides. T cell clones specific for the immunodominant CII 256-270 peptide and restricted to both Aq and Ap molecules were identified. When these clones were incubated with CII protein and either Aq- or Ap-expressing antigen-presenting cells (APC), only Aq-expressing APC were able to induce stimulation. With the use of A(beta) transgenic mice this could be shown to be solely dependent on the MHC class II molecule itself and to be independent of other MHC- or non-MHC genes. Peptide binding studies were performed using affinity-purified MHC class II molecules. The CII 256-270 peptide bound with lower affinity to the Ap molecule than to the Aq molecule. Using a set of alanine-substituted CII 256-270 peptides, MHC class II and T cell receptor (TCR) contacts were identified. Mainly the side chains of isoleucine 260 and phenylalanine 263 were used for binding both the Aq and Ap molecule, i.e. the peptide was orientated similarly in the binding clefts. The major TCR contact amino acids were lysine 264, which can be posttranslationally modified, and glutamic acid 266, which is the only amino acid in the heterologous peptide which differs from the mouse sequence. Glycosylation at positions 264 and 270 of the CII 256-270 peptide did not change the anchor positions used for binding to the Aq or Ap molecules. The autologous form of the peptide (with aspartic acid at position 266) bound with lower affinity to the Aq molecule as compared with the heterologous peptide. The variable affinity displayed by the immunodominant CII 256-270 peptide for different MHC class II molecules, the identification of MHC and TCR contacts and the significance of glycosylation of these have important implications for the understanding of the molecular basis for inherited MHC class II-associated susceptibility to CIA and in turn, for development of novel treatment strategies in this disease.

Tissue transglutaminase enhances collagen type II‐induced arthritis and modifies the immunodominant T‐cell epitope CII260‐270

“…1C), showed signals that were assigned to E-peptide (m/z 1476.766, shifted to 11 Da, deamidated Q) and cross-links between Q-peptides (m/z 2933.532). The MS data prove that both TG-mediated modifications, deamidation and cross-link formation, could be obtained after treatment of Previous studies have shown that amino acid residues I 260 and F 263 from the immunodominant epitope CII259-273 are the major MHC anchor residues occupying the P1 and P4 pockets of the I-A q molecule [29,30], and posttranslational modifications at position K 264 (hydroxylation and glycosylation) did not affect I-A q binding [30]. All these studies suggested that Q 267 from the immunodominant epitope is a TCR contact residue.…”

“…The peptide binding assay was performed by measurement of the ability of synthetic peptides (Q-and E-peptides) to inhibit the binding of biotinylated CLIP-peptide to purified MHC class II molecules as described [30] with slight modifications. In brief, a mixture of a fixed concentration of purified soluble recombinant I-A q molecules (0.1 mM), biotinylated CLIP peptide (2.5 mM), and increasing concentrations of competitor peptides (0, 0.8, 4, 20, 100 and 500 mM) was incubated for 48 h at room temperature and in the presence of a protease inhibitor cocktail (Complete TM , Roche Diagnostics GmbH, Mannheim, Germany).…”

HLA‐DM negatively regulates HLA‐DR4‐restricted collagen pathogenic peptide presentation and T cell recognition

“…It is thought that T and B cell responses to this autoantigen are associated with the development and pathogenesis of rheumatoid arthritis (RA) [2,3]. It is also widely believed that RA is genetically linked to HLA class II molecules, including some HLA-DR4 alleles, and that T cell responses in collagendependent RA are directed towards the immunodominant pathogenic epitope CII [261][262][263][264][265][266][267][268][269][270][271][272][273] [4,5]. Studies also suggest that T cells from patients with RA predominantly recognize the glycosylated form of the immunodominant CII peptide [6,7].…”

“…Studies also suggest that T cells from patients with RA predominantly recognize the glycosylated form of the immunodominant CII peptide [6,7]. Professional antigen-presenting cells (APC) such as B cells, macrophages and dendritic cells abundantly express HLA class II proteins and play critical roles in the pathogenesis of autoimmune arthritis by presenting autoantigens to T cells [4,5,8].In RA, cartilage proteins including CII undergo degradation by proteases, leading to the generation of peptides that can bind to HLA class II proteins and trigger CD4 + T cell activation [9]. Studies suggest that the peptides are loaded onto class II proteins Eur.…”

The major T cell epitope on type II collagen is glycosylated in normal cartilage but modified by arthritis in both rats and humans

“…The T cell response is directed towards the same immunodominant core, CII residues 260-270 [9,10]. This T cell determinant contains lysine residues at position 264 and 270, which can become posttranslationally modified by hydroxylation and further galactosylated and glucosylated, creating many different epitopes containing hydroxyl, mono-and disaccharide groups in both RA and CIA.…”