EGR2 deletion displays similar and differential effects on immunological development and function in autoinflammation-prone B6/lpr and normal B6 mice

Abstract Transcription factor early growth response protein 2 (EGR2) prevents the development of lupus-like autoimmune disease in C57BL/6 (B6) mice by negatively regulating T cell activation, inflammatory cytokine IFNγ and IL-17 production and by suppressing humoral responses. However, increased EGR2 expression has been observed in lupus and also other autoimmune disorders, which contradicts the autoimmune suppressive role of EGR2. Here, we derived conditional EGR2−/−B6/lpr and EGR2−/−B6 mice to investigate and compare the immune regulatory role of EGR2 in autoinflammation (B6/lpr) versus normal physiological (B6) conditions. Significantly, we found that in B6/lpr mice, but not in B6 mice, EGR2 deletion dramatically suppressed serum levels of anti-dsDNA autoantibodies, total IgG, IgG1, IgG2a, and IgM. We further demonstrated that while EGR2 deletion promoted germinal center B (GCB) cell development in both B6 and B6/lpr mice, it significantly reduced the differentiation of plasma and plasmablasts cells in B6/lpr mice. EGR2 deletion promoted splenomegaly and T cell activation in both B6 and B6/lpr mice, but it differentially regulated the profiles of immune cell subpopulations in the spleens of B6 and B6/lpr mice. Especially, EGR2 deletion dramatically suppressed the development of double negative T cells in B6/lpr mice. Moreover, we found that EGR2 had an opposite role in regulating IL-17 production in in vitro activated splenocytes from B6/lpr and B6 mice, although EGR2 had a similar suppressive role for IFNγ production. Together, our data strongly suggest that the immune and autoimmune regulatory roles of EGR2 are context dependent, and should not be generalized in normal physiology and different pathological conditions. Supported by VMCVM-VCOM Center for One Heath Research Seed Grant Program