Interleukin 4-driven reversal of self-reactive B cell anergy contributes to the pathogenesis of systemic lupus erythematosus

Reactivation of anergic autoreactive B cells (BND cells) is a key aetiological process in systemic lupus erythematosus (SLE), yet the underlying mechanism remains largely elusive. This study aimed to investigate how BND cells participate in the pathogenesis of SLE and the underlying mechanism.A combination of phenotypical, large-scale transcriptome and B cell receptor (BCR) repertoire profiling were employed at molecular and single cell level on samples from healthy donors and patients with SLE. Isolated naïve B cells from human periphery blood were treated with anti-CD79b mAb in vitro to induce anergy. IgM internalisation was tracked by confocal microscopy and was qualified by flow cytometer.We characterised the decrease and disruption of BND cells in SLE patients and demonstrated IL-4 as an important cytokine to drive such pathological changes. We then elucidated that IL-4 reversed B cell anergy by promoting BCR recycling to the cell surface via STAT6 signalling.We demonstrated the significance of IL-4 in reversing B cell anergy and established the scientific rationale to treat SLE via blocking IL-4 signalling, also providing diagnostic and prognostic biomarkers to identify patients who are most likely going to benefit from such treatments.