Dendrobium officinale polysaccharide ameliorates high-fat diet-induced hepatic lipid metabolic disorder via the SIRT6/PGC-1α signaling axis

Aims This study aims to explore the potential therapeutic effect of Dendrobium officinale polysaccharide (DOP) on non-alcoholic fatty liver disease (NAFLD) induced by high-fat diet (HFD), and to elucidate the underlying mechanism involving the SIRT6/PGC-1α signaling axis and the regulation of the gut microbiota. Methods We extracted and characterized DOP. We established a rat model of NAFLD induced by HFD and evaluated the efficacy of DOP by integrating multi-omics techniques (transcriptomics, metabolomics) and 16S rRNA sequencing. To verify the specific role of SIRT6, we introduced the SIRT6 inhibitor OSS_128167 in the primary hepatocyte model induced by oleic acid/palmitic acid (OA/PA). Results DOP significantly alleviated liver steatosis, oxidative stress, and lipid metabolism disorders induced by HFD. Multi-omics analysis indicated that DOP regulated liver glycerophospholipid metabolism and restored intestinal microbiota homeostasis, significantly increasing the abundance of beneficial bacteria such as Lactobacillus . Mechanistically, DOP activated the liver SIRT6/PGC-1α signaling axis, thereby enhancing antioxidant defense and inhibiting lipogenesis. Crucially, in vitro experiments confirmed that the SIRT6 inhibitor OSS_128167 eliminated the protective effect of DOP on lipid accumulation, confirming that the effect of DOP depends on SIRT6. Conclusion DOP improves NAFLD through dual mechanisms of regulating the gut-liver axis homeostasis and directly activating the liver SIRT6/PGC-1α signaling pathway. The results of this study provide a theoretical basis for developing DOP as a drug for the treatment of NAFLD.