Investigation Of Chronic Transient Hypoxia Treatment Of High-Fat-Induced Non-Alcoholic Fatty Liver Disease And The Underlying Molecular Mechanisms

Objective:This study explores the role and mechanism of long-term transient hypoxia in high fat induced non-alcoholic fatty liver disease mice based on transcriptomics and proteomics,so as to provide potential targets in strategies for prevention and treatment of NAFLD.Methods:C57BL/6 male mice were randomly divided into four groups: chow diet group,high fat diet group,chow diet hypoxia group,high fat hypoxia group.The mice in high fat diet group were fed on 60% high-fat diet for 12 weeks.After 4 weeks of a high-fat diet,the mice in high fat hypoxia group were fed on a 60% high-fat diet and treated with 10% oxygen for 1 h per day at room temperature and atmospheric pressure for 8 weeks.The mice in chow diet hypoxia group were fed on chow diet and treated with 10% oxygen for 1 h per day at room temperature and atmospheric pressure for 8 weeks.Blood and liver tissues were collected to detect the related lipid metabolites in serum and liver tissues.H&E staining was used to observe the liver tissue.RNA-Seq was used to sequence the transcriptome of liver tissue,and the results of normal diet group,high-fat diet group,and high-fat diet hypoxia stimulation group were analyzed for differences and pathway enrichment,and some of sequencing results was selected for validation by RT-qPCR.Proteomics was performed on liver of mice fed on high-fat diet group and high-fat diet hypoxia treatment group to identify molecules and pathways responsive to hypoxia.Results:Under conditions of chronic transient hypoxic stimulation,HFD-fed mice showed: 1)body weight loss,improvement of NAFLD and reduction of liver lipid droplets;2)decreases in levels of triglyceride,free fatty acid,total cholesterol and low-density lipoprotein cholesterol in serum(P<0.05)and increases in levels of high-density lipoprotein cholesterol(P<0.05).3)decreases in triglyceride and free fatty acid levels in the liver tissue(P<0.05).Furthermore,the Transcriptome sequencing analysis revealed that hypoxia treatment regulated liver cholesterol metabolism and the PPAR signaling pathway,where CYP27A1,Angptl4,KLF9,CDO1 and other genes was significantly up-regulated.In addition,the proteomic analysis showed that hypoxia regulated fatty liver oxidative phosphorylation and fatty acid degradation.Conclusion:Chronic transient hypoxia improves nonalcoholic fatty liver disease in mice by regulating cholesterol metabolism,PPAR signaling pathway and Fatty acid degradation.