University of Queensland, Brisbane, Australia Woolloongabba, Queensland, Australia
Hendrik Nel1, Pascale Wehr2, Christopher Andoniou3, Iona Schuster3, Stephanie Gras4, Helen McGuire5, Helen Weedon6, Annabelle Small7, Katie Lowe7, Mariapia Degli-Esposti3, Mihir Wechalekar8 and Ranjeny Thomas9, 1University of Queensland, Brisbane, Australia, Woolloongabba, Australia, 2University of Queensland Diamantina Institute, Brisbane, Australia, 3Infection and Immunity Program and Department of Microbiology, Biomedicine Discovery Institute, Monash, Australia, 4Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia, 5The University of Sydney, Charles Perkins Centre, Camperdown, Australia, 6Flinders University of South Australia, Bedford Park, Australia, 7Flinders University, Adelaide, Australia, 8Flinders Medical Centre, Bedford Park, Australia, 9University of Queensland, Brisbane, Australia
Background/Purpose: Rheumatoid Arthritis (RA) is associated with specific HLA-DR genotypes with an emphasis on the role of CD4+ effector-memory T cells (Tem) in disease pathogenesis. However, single cell sequencing technologies identified large numbers of CD8+ cytotoxic T lymphocytes (CTL) with distinct granzyme expression profiles infiltrating RA synovial tissue (ST) in active, established RA. Here we assessed T cell clonotypes in ST and peripheral blood (PB) of patients with recent-onset untreated RA and addressed the contribution of virus-specific CD8+ T cells to development of antigen-induced inflammatory arthritis
Methods: Synovial tissues (ST) and paired PBMC from 4 DMARD-naïve recent-onset RA patients were assessed by combined single-cell RNA/TCR-Seq (10x Genomics Chromium 5’ platform) to determine clonal-specific T cell signatures. Models of Ovalbumin (OVA)-induced arthritis (AIA) were established in mice with murine cytomegalovirus (mCMV) latent infection or acute, resolved lymphocytic choriomeningitis virus (LCMV) infection. AIA footpad swelling, OVA- and virus-specific (tetramer+) T cell phenotypes, and functional responses to antigen-restimulation were assessed
Results: A large proportion of T cells in PBMC and ST of all RA patients had signatures of polyfunctional CD4 or CD8 CTL expressing TNF, IFNG, GZMK, GZMA and GZMB. Clonally-expanded TCR sequences from all donors included those predicted to be directed towards HLA class I-restricted CMV or EBV epitopes with 100% sequence identity. CMV epitope-specificity of a TCR sequence shared in PB and ST was confirmed with a CMV-specific tetramer. Imaging mass cytometry of ST identified perivascular clonotypic GZB+ CD8+ T cells, adjacent to DCs, monocytes and thy1+ fibroblasts. In mice with latent mCMV, OVA-AIA was more severe. OVA-specific and host bystander KLRG1- central-memory T cells and mCMV-specific and host bystander PD1+KLRG1- effector-memory CTL were expanded in popliteal draining lymph nodes compared to uninfected OVA-AIA mice. CD4+ and CD8+ T cells produced more IFN-g and TNF in response to OVA and mCMV-IE1 peptide respectively, in infected compared to uninfected mice. After recovering from acute LCMV, AIA was more severe and LCMV-specific CTL produced more cytokine, but the phenotype of OVA- and LCMV-specific and host T cells was unchanged
Conclusion: These findings suggest a model in which positive feedback from arthritogenic or viral CD4+ T cells to antigen-presenting cells (APC) carrying residual latent viral antigen enhances host CD4+ and CD8+ bystander autoreactive memory along with viral antigen-specific CTL expansion, TNF and IFN-g production. In RA, latent-virus-specific CD4+ and CD8+ CTL could contribute to inflammation and activation or lysis of APC targets, thus propagating autoimmunity.
Disclosures: H. Nel, None; P. Wehr, None; C. Andoniou, None; I. Schuster, None; S. Gras, None; H. McGuire, None; H. Weedon, None; A. Small, None; K. Lowe, None; M. Degli-Esposti, None; M. Wechalekar, None; R. Thomas, Sandoz, CSL, Horizon Therapeutics, Janssen-Cilag.
