Characteristics of the IgM repertoires in the peripheral blood of early rheumatoid arthritis patients

Rheumatoid arthritis is a common autoimmune disease, but little is known about the characteristics of the B cell repertoires in the peripheral blood. In this study, the peripheral IgM repertoires of early rheumatoid arthritis (ERA) patients were analyzed by high-throughput sequencing and bioinformatics analyses. Clonal expansion was observed in IgM repertoires of ERA patients. Interestingly, a subset of the dominant clones in ERA repertoires showed self- and polyreactivity to several autoantigens. The clones were also identified in IgM repertoires of healthy adults but they were not expanded, suggesting that they may originate from the natural autoreactive B cell repertoire. Additionally, the ERA repertoires exhibited a greater extent of somatic hypermutations, particularly in the ERA dominant clones, resulting in an enrichment of amino acids important for antigen-antibody interaction. The in-depth analysis of B cell repertoires improved our knowledge of the IgM repertoires in ERA, offering potential insights into the disease's pathogenesis.