The current concepts for development of autoreactive B cells in SLE (systemic lupus erythematosus) focus on extrinsic stimuli and factors that provoke B cells into tolerance loss. Traditionally, major tolerance loss pathways are thought to be regulated by factors outside the B cell including autoantigen engagement of the B-cell receptor (BCR) with simultaneous type I interferon (IFN) produced by dendritic cells, especially plasmacytoid dendritic cells (pDCs). Later, in autoreactive follicles, B-cells encounter T-follicular helper cells (Tfh) that produce interleukin (IL)-21, IL-4 and pathogenic cytokines, IL-17 and IFN gamma (IFNɣ). This review discusses these mechanisms and also highlights recent advances pointing to the peripheral transitional B-cell stage as a major juncture where transient autocrine IFNβ expression by developing B-cells imprints a heightened susceptibility to external factors favoring differentiation into autoantibody-producing plasmablasts. Recent studies highlight transitional B-cell heterogeneity as a determinant of intrinsic resistance or susceptibility to tolerance loss through the shaping of B-cell responsiveness to cytokines and other environment factors.
Keywords: BXD2; IFNβ; IL-17; IL-21; SLE; autoantibodies; autoimmunity; follicular T-helper cells; germinal center B cells; lupus; lymphotoxin beta; marginal zone macrophages; marginal zone-precursor B cells; plasmacytoid dendritic cells; regulator of G-protein signaling; transitional stage 1 B cells; type I IFNs.
© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.