A molecular basis for the association of the HLA-DRB1 locus, citrullination, and rheumatoid arthritis

J Exp Med. 2013 Nov 18;210(12):2569-82. doi: 10.1084/jem.20131241. Epub 2013 Nov 4.

Abstract

Rheumatoid arthritis (RA) is strongly associated with the human leukocyte antigen (HLA)-DRB1 locus that possesses the shared susceptibility epitope (SE) and the citrullination of self-antigens. We show how citrullinated aggrecan and vimentin epitopes bind to HLA-DRB1*04:01/04. Citrulline was accommodated within the electropositive P4 pocket of HLA-DRB1*04:01/04, whereas the electronegative P4 pocket of the RA-resistant HLA-DRB1*04:02 allomorph interacted with arginine or citrulline-containing epitopes. Peptide elution studies revealed P4 arginine-containing peptides from HLA-DRB1*04:02, but not from HLA-DRB1*04:01/04. Citrullination altered protease susceptibility of vimentin, thereby generating self-epitopes that are presented to T cells in HLA-DRB1*04:01(+) individuals. Using HLA-II tetramers, we observed citrullinated vimentin- and aggrecan-specific CD4(+) T cells in the peripheral blood of HLA-DRB1*04:01(+) RA-affected and healthy individuals. In RA patients, autoreactive T cell numbers correlated with disease activity and were deficient in regulatory T cells relative to healthy individuals. These findings reshape our understanding of the association between citrullination, the HLA-DRB1 locus, and T cell autoreactivity in RA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aggrecans / genetics
  • Aggrecans / immunology
  • Aggrecans / metabolism
  • Amino Acid Sequence
  • Animals
  • Antigen Presentation
  • Arthritis, Rheumatoid / genetics*
  • Arthritis, Rheumatoid / immunology*
  • Arthritis, Rheumatoid / metabolism
  • Autoantigens / chemistry
  • Autoantigens / genetics
  • Autoantigens / metabolism
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • Citrulline / metabolism
  • Epitopes / chemistry
  • Epitopes / genetics
  • Epitopes / metabolism
  • Genetic Association Studies
  • HLA-DR beta-Chains / chemistry
  • HLA-DR beta-Chains / genetics
  • HLA-DR beta-Chains / metabolism
  • HLA-DR4 Antigen / chemistry
  • HLA-DR4 Antigen / genetics
  • HLA-DR4 Antigen / metabolism
  • HLA-DRB1 Chains / chemistry
  • HLA-DRB1 Chains / genetics*
  • HLA-DRB1 Chains / metabolism*
  • Humans
  • Mice
  • Mice, Transgenic
  • Models, Molecular
  • Molecular Sequence Data
  • Polymorphism, Genetic
  • Vimentin / genetics
  • Vimentin / immunology
  • Vimentin / metabolism

Substances

  • ACAN protein, human
  • Aggrecans
  • Autoantigens
  • Epitopes
  • HLA-DR beta-Chains
  • HLA-DR4 Antigen
  • HLA-DRB1 Chains
  • Vimentin
  • Citrulline