Systemic lupus erythematosus (SLE) shows a significant gender difference. In addition to X chromosome inactivation (XCI) abnormalities, which may lead to the gender difference in SLE, studies have found that estrogen plays a key role in regulating Th17/Treg immune balance in SLE. Estrogen indirectly affects the quantity and function of Th17 and Treg cells by acting on B cells. In this process, the mutual influence and the interaction between B and T cells promote the development of SLE. Recent studies have reported gender differences in intestinal microbiota, which may lead to sex-dependent genetic susceptibility and epigenetic changes in autoimmune diseases represented by SLE. The interaction between estrogen and intestinal microbiota in SLE affects the immune balance of Th17/Treg cells. This paper mainly reviews the way estrogen works, and the mechanisms by which estrogen regulates Th17/Treg immune balance and the interaction between B and T cells in SLE, hoping to provide new targets for new therapeutic strategies such as selective estrogen receptor modulators.

Cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) pathway, as an important part of the innate immune system, is the main pathway for cytoplasmic DNA recognition and cGAS can be triggered by a variety of cytoplasmic dsDNA. This pathway has become an important bridge connecting autoimmunity, aseptic inflammatory response and cell aging. In recent years, cGAS-STING pathway has attracted increasing attention in autoimmune diseases. In rheumatoid arthritis (RA), neutrophil extracellular traps (NETs) induce typeⅠ interferon response and accelerate the production of anti-citrullinated peptide antibody (ACPA) through the cGAS-STING pathway. In addition, the cGAS-STING pathway also participates in synovitis, bone destruction and RA progression by promoting the proliferation and activation of fibroblast-like synovitis cells and the polarization of M1 macrophages. Inhibition of the cGAS-STING pathway or its downstream signaling pathway can reduce synovial inflammation in RA, suggesting that cGAS-STING pathway may be a potential therapeutic target for RA.