Unveiling the dynamics of B lymphocytes in systemic lupus erythematosus patients treated with belimumab through longitudinal single-cell RNA sequencing.

The article focuses on investigating B lymphocyte dynamics in systemic lupus erythematosus (SLE) patients undergoing anti-BAFF (B cell-activating factor of the TNF family) treatment with belimumab, using longitudinal single-cell RNA sequencing (scRNAseq) of peripheral blood mononuclear cells. The study of four Korean SLE patients revealed distinct temporal changes in B cell subsets, including initial declines in naïve and transitional B cells and plasmablasts, with contrasting patterns in memory B cells, alongside downregulation of B cell activation pathways during treatment. Validation by flow cytometry and comparison with bulk transcriptome data from a Japanese cohort highlighted increased expression of NR4A1, a gene implicated in promoting peripheral B cell tolerance by restricting self-reactive B cells. These findings provide insights into the immunological mechanisms of anti-BAFF therapy in SLE and emphasize the potential for immune profiling to predict therapeutic responses.