IFN-γ receptor and STAT1 signaling in B cells are central to spontaneous germinal center formation and autoimmunity

PP Domeier, SB Chodisetti, C Soni, SL Schell… - Journal of Experimental …, 2016 - rupress.org
PP Domeier, SB Chodisetti, C Soni, SL Schell, MJ Elias, EB Wong, TK Cooper, D Kitamura…
Journal of Experimental Medicine, 2016rupress.org
Spontaneously developed germinal centers (GCs [Spt-GCs]) harbor autoreactive B cells that
generate somatically mutated and class-switched pathogenic autoantibodies (auto-Abs) to
promote autoimmunity. However, the mechanisms that regulate Spt-GC development are not
clear. In this study, we report that B cell–intrinsic IFN-γ receptor (IFN-γR) and STAT1
signaling are required for Spt-GC and follicular T helper cell (Tfh cell) development. We
further demonstrate that IFN-γR and STAT1 signaling control Spt-GC and Tfh cell formation …
Spontaneously developed germinal centers (GCs [Spt-GCs]) harbor autoreactive B cells that generate somatically mutated and class-switched pathogenic autoantibodies (auto-Abs) to promote autoimmunity. However, the mechanisms that regulate Spt-GC development are not clear. In this study, we report that B cell–intrinsic IFN-γ receptor (IFN-γR) and STAT1 signaling are required for Spt-GC and follicular T helper cell (Tfh cell) development. We further demonstrate that IFN-γR and STAT1 signaling control Spt-GC and Tfh cell formation by driving T-bet expression and IFN-γ production by B cells. Global or B cell–specific IFN-γR deficiency in autoimmune B6.Sle1b mice leads to significantly reduced Spt-GC and Tfh cell responses, resulting in diminished antinuclear Ab reactivity and IgG2c and IgG2b auto-Ab titers compared with B6.Sle1b mice. Additionally, we observed that the proliferation and differentiation of DNA-reactive B cells into a GC B cell phenotype require B cell–intrinsic IFN-γR signaling, suggesting that IFN-γR signaling regulates GC B cell tolerance to nuclear self-antigens. The IFN-γR deficiency, however, does not affect GC, Tfh cell, or Ab responses against T cell–dependent foreign antigens, indicating that IFN-γR signaling regulates autoimmune, but not the foreign antigen–driven, GC and Tfh cell responses. Together, our data define a novel B cell–intrinsic IFN-γR signaling pathway specific to Spt-GC development and autoimmunity. This novel pathway can be targeted for future pharmacological intervention to treat systemic lupus erythematosus.
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