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 Overall design: 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.