Tianhuang formula ameliorates non-alcoholic fatty liver diseases in type 2 diabetic mice through CRLS1-ATF3/ChREBP pathway

Objective

Tianhuang Formula (THF) is a hospital formula summarized by Professor Jiao Guo's 30 years of clinical experience. Some studies have shown that it can alleviate dyslipidemia in the body. The purpose of this study is to confirm whether THF can improve non-alcoholic fatty liver diseases (NAFLD) in type 2 diabetic mice induced by high-fat diet (HFD)/streptomycin (STZ) and to clarify its potential mechanism.

Methods

After induction of diabetes, mice were administrated with THF (60 ​mg/kg or 120 ​mg/kg) once daily for 10 weeks. Blood glucose (FBG), glucose tolerance, and insulin resistance (IR) were assayed by oral glucose tolerance test (OGTT) and insulin tolerance test (ITT). Blood lipids, alanine transaminase (ALT), and aspartate transaminases (AST) were detected. Serum fasting insulin (INS) and adiponectin (APN) levels were measured using ELISA. Histological changes in liver and pancreatic islets were observed by H&E staining, followed by Oil Red O staining for liver lipid quantification and periodic acid-Schiff (PAS) staining to detect glycogen accumulation. Western blotting detected the levels of fatty cardiolipin synthase 1 (CRLS1), transcription factor activator 3 (ATF3), and carbohydrate-responsive element binding protein (ChREBP) in the liver. The mRNA transcripts of hepatic inflammatory factors, lipogenesis and lipolysis-related genes, and gluconeogenic enzyme-phosphoenolpyruvate carboxykinase (PEPCK), CRLS1, ATF3, and ChREBP mRNA levels were evaluated by RT-qPCR.

Results

THF restored impaired glucose tolerance and insulin resistance, respectively. There was an improvement in HFD/STZ-induced liver and islet damage, high serum HDL-C and ANP levels, and a significant decrease in FBG, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), FFA, INS, ALT, and AST, and lipid droplet counts in the T2DM mice treated with THF. CREBBP binding protein ATF3 mediated the insulin resistance signaling pathway, which regulated glucose and lipid metabolism in the liver. THF upregulated CRLS1, and ChREBP downregulated the expression of downstream ATF3 in the liver. RT-qPCR analysis also systemically indicated that THF suppressed the pathway and key regulators related to inflammation, lipid accumulation, and gluconeogenesis.

Conclusion

Our findings demonstrated that THF ameliorated lipid profile and attenuated liver steatosis in T2DM mice through CRLS1-ATF3/ChREBP pathway activation.