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Epigallocatechin-3-gallate (EGCG) has been shown to attenuate obesity, fatty liver disease, hepatic inflammation and lipid profiles. Here, we validate the efficacy of EGCG in a murine model of non-alcoholic fatty liver disease (NAFLD) and extend the mechanistic insights. NAFLD was induced in mice by a high-fat diet (HFD) with 30% fructose. EGCG was administered at a low dose (25 mg/kg/day, EGCG-25) or high dose (50 mg/kg/day, EGCG-50) for 8 weeks. In HFD-fed mice, EGCG attenuated body and liver weight by ~22% and 47%, respectively, accompanied by ~47% reduction in hepatic triglyceride (TG) accumulation and ~38% reduction in serum cholesterol, resonating well with previous reports in the literature. In EGCG-treated mice, the hepatic steatosis score and the non-alcoholic steatohepatitis activity score were both reduced by ~50% and ~57%, respectively, accompanied by improvements in hepatic inflammation grade. Liver enzymes were improved ~2–3-fold following EGCG treatment, recapitulating previous reports. Hepatic flow cytometry demonstrated that EGCG-fed mice had lower Ly6C+, MHCII+ and higher CD206+, CD23+ hepatic macrophage infiltration, indicating that EGCG impactedM1/M2 macrophage polarization. Our study further validates the salubrious effects of EGCG on NAFLD and sheds light on a novel mechanistic contribution of EGCG, namely hepatic M1-to-M2 macrophage polarization. These findings offer further support for the use of EGCG in human NAFLD.

Background: In this study, we investigate the impact of epigallocatechin gallate (EGCG), the most abundant and potent catechin in green tea, on a mouse model of inflammatory bowel disease (IBD) and the underlying mechanisms of action. Methods: C57BL/6J mice were subjected to dextran sulfate sodium (DSS)-induced IBD-like disease and then randomly divided into three groups: Model group (MD), low-dose EGCG group (LE, 20 mg/kg/d), and high-dose EGCG group (HE, 50 mg/kg/d). DSS-induced clinical and macroscopic changes were monitored daily. Intestinal permeability was assessed by FITC-Dextran assay. Results: Both high- and low-dose EGCG treatment alleviated clinical manifestations including body weight loss and disease activity index (DAI) of DSS-induced colitis. The DAI score was significantly improved after two days of EGCG treatment. At the end of the study, the macroscopic severity score (MSS) of HE and LE treatment groups were 2.4 &plusmn, 1.2, and 2.2 &plusmn, 1.0, respectively, significantly lower than that of the controls (5.0 &plusmn, 2.1). EGCG treatment also prevented colon shortening, and improved intestinal permeability and histopathological changes. In addition, EGCG treatment attenuated colon inflammation by suppressing colonic levels of pro-inflammatory cytokines IL-6, MCP-1, and TNF-alpha, and inhibited CD3+ T cell and CD68+ macrophage infiltration. Conclusion: EGCG is effective in inflammatory colitis because it reduces cellular and molecular inflammation, and reduces intestinal permeability.