Therapeutic effect of Shaoyao-Gancao Decoction on TLR9-mediated NETosis in MRL/lpr mice

Abstract Systemic lupus erythematosus (SLE) is a chronic, devastating autoimmune disorder associated with severe organ damage. The roles of Toll-like receptor 9 (TLR9) and NETosis in SLE have been described, suggesting the involvement of NETosis signaling in the development of SLE. Shaoyao-Gancao Decoction (SGT) is a potential medication for the treatment of SLE; however, its potential therapeutic mechanism remains unexplored. To determine the function of SGT in SLE, we treated MRL/lpr female mice with SGT, the main components of which were paeoniflorin (56.949 μg·mL -1) and glycyrrhizin (459.393 μg·mL -1). We found that SGT treatment relieved lymphadenectasis and splenomegaly, reduced urine protein and anti-dsDNA antibody concentrations, and relieved kidney pathology in MRL/lpr mice. SGT could also effectively regulate the oxidation/antioxidant balance, significantly reduce malondialdehyde (MDA) and nitric oxide (NO) contents and significantly increase superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in MRL/lpr mice. The neutrophil extracellular trap (NET) content of MRL/lpr mice also decreased to a certain extent after SGT treatment. All these results suggested that SGT might improve the inflammatory damage to tissues caused by oxygen free radicals, thereby regulating the NETosis process mediated by TLR9 and exerting a good therapeutic effect on SLE.