Small Joints, Big Insights: The Role of T Cell Receptor Diversity in Rheumatoid Arthritis

The present study examines the synovial T cell repertoire, T cell phenotypes, and T cell specificities in small joints of rheumatoid arthritis (RA) patients at the time of diagnosis. The study found that CD4+ T cells are dominant and peripheral helper T-like cells are present in both ACPA+ and ACPA- patients. The study identified over 4,000 unique TCR sequences and 225 clonal expansions, as well as a biased gene usage of the Vβ chain segment TRBV20-1 in CD4+ cells from ACPA+ patients. Additionally, the study found that clonally expanded, viral-reactive T cells account for part of the diverse CD4+ T cell repertoire. Minimally invasive biopsies of the RA synovium allow for single-cell TCR sequencing and phenotyping.