ABSTRACT
ObjectiveTo investigate the mechanism of action of Xiayuxue decoction in inhibiting nonalcoholic fatty liver disease （NAFLD） induced by high-fat diet in mice by regulating nucleotide binding oligomerization domain like receptor containing pyrin domain protein 6 （NLRP6）. MethodsA total of 15 male C57BL/6 mice were randomly divided into low-fat diet （LFD） group， high-fat diet （HFD） group， and Xiayuxue decoction-HFD group （XYXD group）， with 5 mice in each group. Liver function parameters （alanine aminotransferase ［ALT］ and aspartate aminotransferase ［AST］） and blood lipid metabolic indicators （triglycerides ［TG］ and total cholesterol ［TC］） were measured； HE staining and oil red O staining were performed for liver tissue to observe histomorpholoty and lipid droplet deposition； quantitative real-time PCR was used to measure the expression levels of inflammatory factors （tumor necrosis factor-α ［TNF-α］， interleukin-1β ［IL-1β］， interleukin-18 ［IL-18］， and NLRP6） in liver tissue； Western blot was used to measure the protein expression levels of NLRP6， nuclear factor-kappa B （NF-κB）， and NF-κB p65； immunohistochemistry was used to measure the expression of NLRP6 and CD68. Mouse Raw264.7 cells were treated with palmitic acid （PA）， lipopolysaccharide， and serum containing Xiayuxue decoction to observe inflammation. A one-way analysis of variance was used for comparison of continuous data between multiple groups， and the least significant difference t-test was used for further comparison between two groups. ResultsCompared with the LFD group， the HFD group had significant increases in the serum levels of ALT， AST， TC， and TG （all P<0.05）. Liver histopathological examination showed that the HFD group had marked hepatic steatosis and a signficant increase in NAS score （P<0.05）， and quantitative real-time PCR showed significant increases in the inflammatory factors such as IL1β and IL-18 and a significant reduction in the expression of NLRP6 （all P<0.05）. Immunohistochemistry showed that the expression of NLRP6 showed a similar trend as that of the macrophage marker CD68. Western blot showed that after the downregulation of NLRP6 expression， there was a significant increase in phosphorylated NF-κB p65 （P<0.05）. Compared with the HFD group， Xiayuxue decoction effectively improved liver inflammation， upregulated the expression of NLRP6， and downregulated phosphorylated NF-κB p65 in HFD mice （all P<0.05）. After Raw264.7 cells were treated with PA， NLRP6 was downregulated to promote the progression of inflammation （P<0.05）， and treatment with Xiayuxue decoction could upregulate NLRP6 and inhibit inflammation NF-κB （P<0.05）. ConclusionXiayuxue decoction can effectively improve hepatic steatosis and liver inflammation in a mouse model of NAFLD， possibly by regulating NLRP6/NF-κB to alleviate macrophage activation.