EGR2 plays a differential immune regulatory role in normal C57BL/6 mice and autoimmune-prone B6/lpr mice

Early growth response protein 2 (EGR2) is a zinc-finger transcription factor that belongs to the early growth response (Egr) gene family. Recent studies have shown that EGR2 is required to induce T cell anergy, and it plays an important role in T cell immunity and autoimmunity. Conditional depletion of EGR2 in T lymphocytes in C57BL/6 (B6) mice (EGR2−/−B6) was able to break immune tolerance and induce T cell-driven, a lupus-like autoimmune disease. In EGR2−/−B6 mice, there was also enhanced GC response and humoral responses. However, increased EGR2 expression has been observed in lupus and autoimmune disorder systemic sclerosis. These observations seem to contradict the autoimmune suppressive role of EGR2 in B6 mice. To investigate further the immune regulatory role of EGR2 in an autoimmune context, we derived EGR2−/−B6/lpr mice with EGR2 deficiency in both T and B cells. We found that EGR2 depletion promoted splenomegaly and increased IFNγ, IL-10, IL-2 in both B6 and B6/lpr mice. Significantly, we found that in B6/lpr mice, EGR2 depletion reduced serum levels of anti-dsDNA autoantibodies, total IgG, IgG1, IgG2a, and IgM. Furthermore, in B6/lpr mice, depletion of EGR2 promoted germinal center B (GCB) cell development, but suppressed plasma cell (PC) differentiation. However, in wild-type B6 mice, EGR2 depletion significantly increased anti-dsDNA autoantibodies, accompanied by a significant increase of GCB cell development and a trend of increase in PC differentiation. Together, we demonstrated that EGR2 has a differential role in the normal and autoimmune state, particularly in regulating GCB transition into plasma cell during late B cell development.