EAF2 deficiency attenuates autoimmune disease in Fas ^lpr mice by modulating B cell activation and apoptosis

MRL/lpr mice develop systemic lupus erythematosus-like autoimmunity due to defective FAS-mediated apoptosis. We generated Fas ^lpr mice deficient in EAF2, a transcription elongation-associated factor known to promote apoptosis in germinal center (GC) B cells and crucial for preventing autoimmunity. Contrary to expectations, EAF2 deficiency significantly reduced lymphadenopathy and splenomegaly, extended lifespan, and alleviated nephritis by decreasing renal immune complex deposition. Additionally, EAF2 deficiency markedly reduced accumulation of activated B cells, GC B cells, plasma cells, and the abnormal B220⁺CD3⁺ T cells in Fas ^lpr mice. Further analysis revealed that Eaf2 ^-/- Fas ^lpr B cells showed hyperactivation upon various stimulations, followed by increased death. RNA sequencing of the B220⁺CD3⁺ cells revealed a downregulation in survival-promoting genes such as Bcl-2 and Akt and an upregulation of proapoptotic genes. We conclude that the combined deficiency in FAS- and EAF2-mediated apoptotic pathways leads to B cell hyperactivation and subsequent death, thereby ameliorating systemic autoimmunity in this model.