Zhuyu pill mitigates NAFLD through activation of IL22/JAK1/STAT3 signaling pathway

Abstract

This study aims to investigate the lipid-lowering, anti-inflammatory, and antioxidant effects of Zhuyu Pill in non-alcoholic fatty liver disease (NAFLD), and to determine whether its therapeutic action is mediated through modulation of the IL-22/JAK1/STAT3 signaling pathway. In animal experiments, C57BL/6 mice were fed a high-fat diet for 17 weeks to induce a NAFLD model. They were randomly divided into a control group, a Zhuyu Pill treatment group, and a positive control group, and the intervention lasted for 6 weeks. Mouse liver tissue and serum were collected for biochemical analysis of blood lipids and liver enzyme activities. Liver sections were processed for HE staining and Oil Red O staining to evaluate histopathological changes and lipid accumulation. ELISA was employed to quantify inflammatory factor levels, while DCFH-DA and MitoSOX staining used to detect reactive oxygen species (ROS) in the liver. In cell experiments, mouse liver cells AML-12 were used as a model, and cells were treated with free fatty acids to simulate the NAFLD microenvironment. ELISA was used to detect changes in the expression of inflammatory factors and detecting the levels of cellular ROS and mitochondrial ROS. In addition, siRNA technology was used to silence IL-22 and activate the JAK/STAT signaling pathway with Colivelin. The changes in lipid deposition and ROS signaling in cells were observed, and the expression changes of IL-22/JAK1/STAT3 signaling pathway related proteins were detected by WB method. In animal experiments, the detection results of serum biochemical indicators in mice showed that Zhuyu Pill can effectively reduce the levels of ALT, AST, TC, TG, LDL-C, and HDL-C. HE and Oil Red O staining revealed that Zhuyu Pill markedly alleviated hepatic lipid accumulation and inflammatory infiltration. The results of inflammatory factors showed that treatment with Zhuyu Pill significantly reduced the levels of pro-inflammatory factors IL-6, TNF-α, IL-1 β, and MCP-1 in mouse serum, while increasing the expression of IL-22. The results of DCFH-DA and MitoSOX staining methods showed that Zhuyu Pill could significantly reduce the level of ROS in the liver tissue of NAFLD mice. In vitro experiments showed that treatment with Zhuyu Pill significantly reduced the levels of pro-inflammatory cytokines IL-6, TNF-α, IL-1 β, and MCP-1 in NAFLD cell models, increased the expression of IL-22, significantly reduced ROS levels, increased the expression of p-JAK1 protein, p-STAT3 protein, BCL-2 protein, and reduced the expression of BAX protein. SiRNA-mediated IL-22 silencing markedly attenuated the therapeutic effects of Zhuyu Pill on reducing lipid deposition and enhancing antioxidant defense, and also diminished its ability to activate the IL-22/JAK1/STAT3 signaling pathway. Meanwhile, STAT3 activator Colivelin was able to partially reverse the effects of IL-22 silencing. Zhuyu Pill can regulate lipid metabolism, inhibit inflammatory response, alleviate oxidative stress, and activate the IL-22/JAK1/STAT3/BCL-2 signaling pathway to improve NAFLD.