Elucidation of the anti-inflammatory mechanism of Er Miao San by integrative approach of network pharmacology and experimental verification

Traditional Chinese medicine (TCM) has been long time used in China and gains ever-increasing worldwide acceptance. Er Miao San (EMS), a TCM formula, has been extensively used to treat inflammatory diseases, while its bioactive components and therapeutic mechanisms remain unclear. In this study, we conducted an integrative approach of network pharmacology and experimental study to elucidate the underlying mechanisms of EMS in treating human rheumatoid arthritis (RA) and other inflammatory conditions. Quercetin, wogonin and rutaecarpine were probably the main active compounds of EMS in RA treatment as they affected the most RA-related targets, and TNF-α, IL-6 and IL-1β were considered to be the core target proteins. The main compounds in EMS bound to these core proteins, which was further confirmed by molecular docking and bio-layer interferometry (BLI) analysis. Moreover, the potential molecular mechanisms of EMS predicted from network pharmacology analysis, were validated in vivo and in vitro experiments. EMS was found to inhibit the production of NO, TNF-α and IL-6 in lipopolysaccharide (LPS)-stimulated RAW264.7 cells; reduce xylene-induced mouse ear edema; and decrease the incidence of carrageenan-induced rat paw edema. The carrageenan-induced up-regulation of TNF-α, IL-6 and IL-1β mRNA expression in rat paws was down-regulated by EMS, consistent with the network pharmacology results. This study provides evidence that EMS plays a critical role in anti-inflammation via suppressing inflammatory cytokines, indicating that EMS is a candidate herbal drug for further investigation in treating inflammatory and arthritic conditions.