Salidroside-Mitigated Inflammatory Injury of Hepatocytes with Non-Alcoholic Fatty Liver Disease via Inhibition TRPM2 Ion Channel Activation

Purpose: Oxidative stress plays an important role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). TRPM2 ion channel functions as a molecular sensor for oxidative stress. The aim of this study was to examine the protective effects of Salidroside, a powerful antioxidative plant, on TRPM2 in an established in vitro model of NAFLD. Methods: NAFLD model was established by palmitic acid (PA) in hepatic L02 cell lines and was added to the media at a final concentration of 400 mu M. Cells were used as normal group, PA group and PA receiving varied concentrations of Salidroside (75 mu g/mL, 150 mu g/ mL, 300 mu g/mL). After treating 24 hrs, MTT assay was used to detect cell viability, and ALT level was measured using an appropriate kit assay. Intracellular lipid accumulation was observed by Oil red O staining. Cytosolic Ca2+ concentrations were evaluated by flow cytometer with Fluo-3/AM. Quantitative RT-PCR was used to measure the mRNA expression of TRPM2, IL-1 beta and IL-6, and the protein expressions of TRPM2, p-CaMKII and autophagy (LC3B, p62) were determined using Western blot. Results: Treatment with Salidroside effectively restored liver injury and alleviated lipid droplet deposition in a dose-dependent manner, which was associated with inhibition of TRPM2/Ca2+/CaMKII pathway. Additionally, autophagic clearance was enhanced by intervention with Salidroside in a dose-dependent manner. Further investigation indicated that Salidroside down-regulated the mRNA expression of IL-1 beta and IL-6-pro-inflammatory cytokines. Conclusion: These results suggest that Salidroside could alleviate inflammatory injury and steatosis via autophagy activation mediated by downregulation of the TRPM2/Ca2+/CaMKII pathway. Targeting the TRPM2 ion channel is a novel treatment strategy for oxidative stress-induced liver in NAFLD.