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0000-0002-6944-6591
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George K.
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Publisher: American Society for Clinical Investigation
Date: 05-2003
DOI: 10.1172/JCI200317166
Publisher: BMJ
Date: 11-08-2017
DOI: 10.1136/ANNRHEUMDIS-2017-211300
Abstract: The pathogenetic mechanisms by which HLA-DRB1 alleles are associated with anticitrullinated peptide antibody (ACPA)-positive rheumatoid arthritis (RA) are incompletely understood. RA high-risk HLA-DRB1 alleles are known to share a common motif, the ‘shared susceptibility epitope (SE)’. Here, the electropositive P4 pocket of HLA-DRB1 accommodates self-peptide residues containing citrulline but not arginine. HLA-DRB1 His/Phe13β stratifies with ACPA-positive RA, while His13βSer polymorphisms stratify with ACPA-negative RA and RA protection. Indigenous North American (INA) populations have high risk of early-onset ACPA-positive RA, whereby HLA-DRB1*04:04 and HLA-DRB1*14:02 are implicated as risk factors for RA in INA. However, HLA-DRB1*14:02 has a His13βSer polymorphism. Therefore, we aimed to verify this association and determine its molecular mechanism. HLA genotype was compared in 344 INA patients with RA and 352 controls. Structures of HLA-DRB1*1402-class II loaded with vimentin-64Arg 59-71 , vimentin-64Cit 59-71 and fibrinogen β−74Cit 69-81 were solved using X-ray crystallography. Vimentin-64Cit 59-71 -specific and vimentin 59-71 -specific CD4+ T cells were characterised by flow cytometry using peptide-histocompatibility leukocyte antigen (pHLA) tetramers. After sorting of antigen-specific T cells, TCRα and β-chains were analysed using multiplex, nested PCR and sequencing. ACPA + RA in INA was independently associated with HLA-DRB1*14:02 . Consequent to the His13βSer polymorphism and altered P4 pocket of HLA-DRB1*14:02, both citrulline and arginine were accommodated in opposite orientations. Oligoclonal autoreactive CD4+ effector T cells reactive with both citrulline and arginine forms of vimentin 59-71 were observed in patients with HLA-DRB1*14:02 + RA and at-risk ACPA - first-degree relatives. HLA-DRB1*14:02-vimentin 59-71 -specific and HLA-DRB1*14:02-vimentin-64Cit 59-71 -specific CD4+ memory T cells were phenotypically distinct populations. HLA-DRB1*14:02 broadens the capacity for citrullinated and native self-peptide presentation and T cell expansion, increasing risk of ACPA+ RA.
Publisher: Elsevier BV
Date: 03-2002
DOI: 10.1016/S0198-8859(01)00377-9
Abstract: Three different HLA-DQ0602 restricted T-lymphocyte clones (clones 5, 44, and 48) specific for two different Herpes simplex virus type 2 (HSV-2) VP16 peptides were used in a series of proliferation assays with BLS-1 cell lines expressing mutated HLA-DQ0604 molecules as APC. Up to four residues in the peptide-binding region of DQ0604 were replaced by the respective DQ0602 residue. For all three clones, residue beta70 played a crucial role in TCR recognition beta30 and beta57 were important, although beta86 was less significant. Clone 5 and 48, specific to the HSV-2 VP16 369--379 peptide, responded to the same mutated DQ0604 molecules. Both clones could be stimulated only when the antigen presenting DQ molecule contained the DQ0602-like Gly at position beta70. Stimulation of clone 44, which recognized a different HSV-2 VP16 epitope (VP16 40-50), was less restricted. Molecular homology modeling showed that the beta70Arg of DQ0604 partially covered the peptide around P5/P6. Interactions of beta70 with residues from the antigen-peptide and polymorphic residues at positions beta30 and beta57 can modulate this effect. Supported by molecular modeling data, we conclude that the distinct molecular topography of DQ0602 is not contributed by a single residue, but rather the interactions of various polymorphic DQ residues with particular antigenic peptides.
Publisher: Springer Science and Business Media LLC
Date: 05-05-2015
DOI: 10.1038/NCOMMS7681
Abstract: The HLA locus is the strongest risk factor for anti-citrullinated protein antibody (ACPA)(+) rheumatoid arthritis (RA). Despite considerable efforts in the last 35 years, this association is poorly understood. Here we identify (citrullinated) vinculin, present in the joints of ACPA(+) RA patients, as an autoantigen targeted by ACPA and CD4(+) T cells. These T cells recognize an epitope with the core sequence DERAA, which is also found in many microbes and in protective HLA-DRB1*13 molecules, presented by predisposing HLA-DQ molecules. Moreover, these T cells crossreact with vinculin-derived and microbial-derived DERAA epitopes. Intriguingly, DERAA-directed T cells are not detected in HLA-DRB1*13(+) donors, indicating that the DERAA epitope from HLA-DRB1*13 mediates (thymic) tolerance in these donors and explaining the protective effects associated with HLA-DRB1*13. Together our data indicate the involvement of pathogen-induced DERAA-directed T cells in the HLA-RA association and provide a molecular basis for the contribution of protective redisposing HLA alleles.
No related grants have been discovered for George K Papadopoulos.