Epstein-Barr virus reprograms autoreactive B cells as antigen-presenting cells in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by antinuclear antibodies (ANAs). Epstein-Barr virus (EBV) infection has been epidemiologically associated with SLE, yet its role in pathogenesis remains incompletely defined. Here, we developed an EBV-specific single-cell RNA-sequencing platform and used it to demonstrate that EBV infection reprograms autoreactive antinuclear antigen B cells to drive autoimmunity in SLE. We demonstrated that, in SLE, EBV⁺ B cells are predominantly CD27⁺CD21^low memory B cells that are present at increased frequencies and express <i>ZEB2</i>, <i>TBX21</i> (T-bet), and antigen-presenting cell transcriptional pathways. Integrative analysis of chromatin immunoprecipitation sequencing (ChIP-seq), assay for transposase-accessible chromatin sequencing (ATAC-seq), and RNA polymerase II occupancy data revealed EBV nuclear antigen 2 (EBNA2) binding at the transcriptional start sites and regulatory regions of <i>CD27</i>, <i>ZEB2</i>, and <i>TBX21</i>, as well as the antigen-presenting cell genes demonstrated to be up-regulated in SLE EBV⁺ B cells. We expressed recombinant antibodies from SLE EBV⁺ B cells and demonstrated that they bind prototypical SLE nuclear autoantigens, whereas those from healthy individuals do not. We further found that SLE EBV⁺ B cells can serve as antigen-presenting cells to drive activation of T peripheral helper cells with concomitant activation of related EBV^- antinuclear double-negative 2 B cells and plasmablasts. Our results provide a mechanistic basis for EBV being a driver of SLE through infecting and reprogramming nuclear antigen-reactive B cells to become activated antigen-presenting cells with the potential to promote systemic disease-driving autoimmune responses.