Role And Mechanisms Of Mitochondrial Fission And Mitophagy In Liver Injury Induced By Osahs Combined With Obesity

Objective:Chronic intermittent hypoxia(CIH)is the pathophysiological basis of obstructive sleep apnea hypopnea syndrome(OSAHS),which has been confirmed to be closely related to liver injury.A surge in obesity significantly increases the prevalence of OSAHS.This study established a mouse model of CIH combined with high fat diet(CIH+HFD)to study the changes of liver structure and function induced by OSAHS combined with obesity.This study further investigated the role of mitochondrial fission,mitophagy and NR4A1/ DNA-PKcs/p53 pathway in the liver injury induced by OSAHS combined with obesity.Methods:1.Mouse models of chronic intermittent hypoxia and high-fat diet were established.And the mice were divided into four groups: control group(Con group),chronic intermittent hypoxia group(CIH group),high-fat diet group(HFD group)and chronic intermittent hypoxia combined with high-fat diet group(CIH+HFD group).The body weight of mice in different groups was monitored every week,and the liver weight of mice was weighed after modeling.2.Biochemical kits were used to detect related biochemical indexes of mice in different groups,including alanine aminotransferase(ALT),aspartate aminotransferase(AST),glutathione(GSH),triglyceride(TG),total cholesterol(TC)and low density lipoprotein-C(LDL-C);HE staining was used to observe the changes of liver tissue structure in different groups;Western blot was used to examine the protein level of Caspase-3 in the liver tissue of different groups;RT-qPCR was used to detect the mRNA levels of inflammatory cytokines in mice of different groups.3.The mRNA and protein levels of factors related to mitochondrial function,mitochondrial fission and mitophagy in mice of different groups were detected by RT-qPCR and Western blot.4.The mRNA and protein levels of factors related to NR4A1/DNA-PKcs/p53 signaling pathway in mice of different groups were detected by RT-qPCR and Western blot.Results:1.This study successfully established the mouse model of chronic intermittent hypoxia combined with high-fat diet.Compared with the Con group,the body weight of mice in CIH group were decreased;the body weight of mice in HFD and CIH+HFD group were increased significantly,especially in HFD group.2.Compared with the Con group,the expression of ALT and AST in serum and liver tissue of mice in CIH+HFD group were significantly increased;the expression of serum TC,LDL-C and in liver TG were also significantly increased;and the mRNA levels of inflammatory cytokines IL-6,TNF-α and TGF-β were up-regulated.HE staining showed that hepatocytes in CIH and HFD groups were enlarged with obvious vacuole.While hepatocytes in CIH+HFD groupe also showed vacuole-like changes and disordered structure.Broken cells were also observed.Compared with the Con group,the protein level of apoptosis factor Caspase-3 was upregulated in CIH+HFD group.3.The mRNA levels of genes related to mitochondrial function,autophagy markers and mitophagy were significantly down-regulated in CIH,HFD and CIH+HFD groups,with CIH+HFD group being the most obvious down-regulated.Compared with the Con group,the protein levels of autophagy markers LC3 II and Beclin1,mitophagy receptor Bnip3 were also down-regulated in CIH+HFD group.The mRNA levels of mitochondrial fission related factors Drp1,Fis1 and protein level of Drp1 were significantly increased.4.Compared with the Con group,the mRNA and protein levels of related factors related to NR4A1/DNA-PKcs/p53 signaling pathway were significantly increased in CIH+HFD group.Conclusion:This study successfully established the mouse model of chronic intermittent hypoxia combined with high-fat diet.We found that chronic intermittent hypoxia combined with high-fat diet cause severe liver injury,excessive mitochondrial fission and disordered mitophagy,which may be related to the activation of NR4A1/DNA-PKcs/p53 pathway.