Gene expresison studies of lupus and healthy B cell subsets through RNA sequencing

Dramatic expansions of class switched B cells lacking IgD and CD27 (double negative; DN), are characteristic of Systemic Lupus Erythematous (SLE). However, their origin, clinical and immunological significance and their relationship to CD27+ memory B cells remain unclear. We demonstrate that SLE DN expansions are dominated by a CXCR5- CD21- subset with a pre-plasma cell phenotype and distinctive transcriptional, and functional properties. SLE patients with an expansion of CXCR5- DN are predominantly African-American with higher disease activity and anti-Smith/RNP autoantibodies. CXCR5- DN cells display a distinct transcriptome characterized by differential expression of cytokine receptors, transcription factors, and signaling molecules. DN express high levels of the key INFg effector factor, T-bet and associated transcription factor Zeb2 and uniquely among B cell subsets, do not express TRAF5, a negative regulator of TLR signaling. Consistent with this pattern gene expression SLE DN have enhanced responsiveness to TLR7 and can differentiate into autoantibody secreting plasma cells Based on the expression of IgD, CD27, and CXCR5, 4 different B cell subsets were isolated from 3 healthy control donors and 3 SLE patients, gene expression was compared both between SLE and HCD B cells within each subset and between B cell subsets.