title: Identification and functional characterization of T cells reactive to citrullinated vimentin in HLA-DRB1*0401-positive humanized mice and rheumatoid arthritis patients.
abstract: OBJECTIVE
  Antibodies toward the citrullinated form of the synovial antigen vimentin are specific for rheumatoid arthritis (RA) and are associated with HLA-DRB1*0401. This suggests that T cells specific for peptides derived from citrullinated vimentin presented in the context of HLA-DRB1*0401 may contribute to the etiopathogenesis of RA. The aim of this study was to identify immunodominant epitopes from citrullinated vimentin presented by HLA-DRB1*0401 and to characterize the resulting T cell responses.
  
  
  METHODS
  We first predicted an HLA-binding T cell epitope from citrullinated vimentin based on the binding motif of HLA-DRB1*0401 and then confirmed its affinity. A class II major histocompatibility complex (MHC) tetramer loaded with the citrullinated form of vimentin aa 59-78 (cit-vimentin aa 59-78) was constructed and used to screen for specific T cells in HLA-DRB1*0401-transgenic mice, patients with RA, and healthy control subjects. Additionally, the cytokine output following cit-vimentin aa 59-78 challenge was analyzed in patients and healthy control subjects by multicolor flow cytometry and Luminex-based analysis.
  
  
  RESULTS
  The citrullinated form of vimentin aa 59-78 bound to HLA-DRB1*0401, but the native form could not. Subsequently, cit-vimentin aa 59-78-specific T cells were detected in immunized mice and in the periphery of both HLA-DR*0401-positive healthy control subjects and HLA-DR*0401-positive patients with RA, using class II MHC tetramers, CD154 up-regulation, and intracellular cytokine measurements. As demonstrated in cell culture supernatants, the production of cytokines (predominantly interferon-γ) in response to cit-vimentin aa 59-78 was significantly higher in patients compared with controls.
  
  
  CONCLUSIONS
  Here, we describe a posttranslational modification of an RA candidate autoantigen toward which HLA-DRB1*0401-restricted T cells can be detected in both patients with RA and healthy controls but for which a proinflammatory response is observed uniquely in patients with RA.
authors.affiliation: Rheumatology Unit, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Omri
authors.initials: O
authors.lastname: Snir
authors.forename: Mary
authors.initials: M
authors.lastname: Rieck
authors.forename: John A
authors.initials: JA
authors.lastname: Gebe
authors.forename: Betty B
authors.initials: BB
authors.lastname: Yue
authors.forename: Crystal A
authors.initials: CA
authors.lastname: Rawlings
authors.forename: Gerald
authors.initials: G
authors.lastname: Nepom
authors.forename: Vivianne
authors.initials: V
authors.lastname: Malmström
authors.forename: Jane H
authors.initials: JH
authors.lastname: Buckner
mesh_terms: D000328:Adult; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D059811:HLA-DRB1 Chains / Q000276:immunology*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D010456:Peptides, Cyclic / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014746:Vimentin / Q000276:immunology*
chemical_list: D018984:Epitopes, T-Lymphocyte; D059811:HLA-DRB1 Chains; C553505:HLA-DRB1*04:01 antigen; D010456:Peptides, Cyclic; D014746:Vimentin