The role of B cells in the pathogenesis of systemic sclerosis: an update

The pathogenesis of SSc is incompletely understood, but several lines of evidence suggest that B cells are involved. Effector B (Beff) cells are hyperactivated and produce autoantibodies (autoAbs), and regulatory B cells (Bregs) are decreased, although a recent study reported a defect in central B cell tolerance. AutoAbs appear before fibrosis, and some have direct profibrotic effects, while others also induce microvasculopathy. Recently, a study found that B cells reactive to topo I with high affinity produce IL-6 and cause fibrosis in mice, whereas B cells with low affinity for topo I produce IL-10 and inhibit fibrosis. Ibrutinib, a Bruton's tyrosine kinase inhibitor, promoted B cells with low affinity for topo I and decreased fibrosis. These findings provide a rationale for innovative B cell-directed strategies for managing SSc, such as ibrutinib or chimeric antigen receptor T cells, particularly in the early inflammatory stage of the disease.