Paeoniae Radix Alba effectively attenuates Polygonum multiflorum Thunb. -induced idiosyncratic liver injury by modulating M2 macrophage polarization

Objective: Polygonum multiflorum Thunb. (PM) is a commonly used tonic herb known to cause idiosyncratic drug-induced liver injury (IDILI). This study explored the detoxification effects and potential mechanisms of action of Paeoniae Radix Alba (PRA) on PM-induced IDILI. Methods: Network pharmacology analysis was utilized to predict the related targets of "PRA-PM-innate immunity.” A non-hepatotoxic lipopolysaccharide (LPS) and PM-induced IDILI model was used to evaluate the detoxification effects of PRA by measuring liver function indicators, pathological examinations, and macrophage-related factors. Bone marrow-derived macrophages (BMDMs) were stimulated with IL-4 to differentiate into M2 macrophages, and the effects of PM and PRA on M2 macrophage polarization were explored. Results: Target screening of "PRA-PM-innate immunity" identified 21 intersecting targets, most of which were closely associated with macrophage polarization. In rat models of IDILI induced by PM, the combined use of PRA significantly reduced the extent of liver damage and the levels of inflammatory factors, while promoting the expression of M2 macrophage-related factors such as IL-4, IL-10, Arg1, and CD206. In vitro, PM dose-dependently inhibited the expression of the Arg1 protein and M2 macrophage-related genes, whereas PRA exhibited the opposite effect. When used in combination, PRA ameliorated the inhibitory effect of PM on M2 macrophage polarization. Conclusions: Our results demonstrate that PRA has a therapeutic effect on PM-induced IDILI; its mechanism may involve alleviating liver injury by promoting M2 macrophage polarization, thus reducing the expression of inflammatory factors.