TCRβ Sequencing Reveals Spatial and Temporal Evolution of Clonal CD4 T cell Responses in a Breach of Tolerance Model of Inflammatory Arthritis

ObjectivesDevelopment of effective tolerogenic therapies for Rheumatoid Arthritis (RA) relies on understanding the evolution of articular antigen specific CD4 T cell responses. TCR clonality of the endogenous CD4 T cell infiltrate in early inflammatory arthritis was assessed to monitor the evolution of the TCR repertoire in the inflamed joint and its associated popliteal lymph node (pLN). MethodsMouse models of antigen-induced breach of self-tolerance and chronic polyarthritis were used to recapitulate the early and late phases of RA reported in patients. The infiltrating endogenous, antigen experienced CD4 T cells in inflamed joints and pLNs were analysed using flow cytometry and TCR{beta} sequencing. ResultsTCR repertoires from pLNs displayed increased clonality and diversity with disease progression, while inflamed joints maintain similar TCR repertoire clonality and diversity with time. Repertoires from late phase pLNs accumulated clones with a diverse range TRBV genes, while inflamed joints at both phases contain clones expressing similar TRBV genes. Repertoires from pLNs and joints at the late phase displayed reduced CDR3{beta} sequence overlap compared to the early disease phase, however correlation analysis revealed the most abundant clones in pLNs accumulate in the joint at the later phase. ConclusionsCD4 T cell clonality broadens and evolves with progression of inflammatory arthritis and is reflected in pLNs before potentially being mirrored in the joint. These observations imply that antigen specific tolerogenic therapies for RA will be more easily developed and more effective at earlier phases of the disease, when CD4 T cell clonality is least diverse. KEY MESSAGESO_LISelective accumulation of CD4 T cell clones has been observed in arthritic joints of RA patients, indicating the presence of antigen driven accumulation of CD4 T cells in these patients. C_LIO_LIThese antigen specific T cell clones are thought to be pathogenic and thus are targets for tolerogenic therapy. C_LIO_LIThis study suggests that CD4 TCR clonality is restricted at the early phases of disease and broadens with disease progression. Moreover, changes in CD4 TCR clonality are first reflected in joint draining lymph nodes before being mirrored in the inflamed joint. C_LIO_LIThus tolerogenic therapies will be more effective when CD4 TCR clonality is restricted i.e. at early disease stages. C_LIO_LIChanges in CD4 TCR clonality in the joint draining lymph node can also be a biomarker for disease state. C_LI