| Objective: To explore the potential mechanisms of Hypoxia inducible factor-2α(Hif-2α)affecting acute ulcerative colitis(UC)by regulating mitophagy in intestinal epithelial cells in mice on a high fat diet.This study aimed to further clarify the role of Hif-2α and and mitophagy in UC and find new therapeutic targets in UC.Methods: Forty-eight male SPF Balb/c mice aged 6-8 weeks were selected for the experiments.The mice were divided into a normal diet group and a high fat diet(HFD)group with 24 mice in each group according to whether the mice were on a high fat diet.Normal diet groups were given normal diet throughout the experiment,and high fat diet groups were constructed a high fat diet model: Adaptive feeding of high fat diet was performed for 7 days,and the proportion of high fat diet gradually increased while the proportion of normal diet gradually decreased.After high fat diet adaptive feeding,full high fat diet was fed for 30 days to establish a high fat diet model.Then,according to whether dextran sulfate sodium salt(DSS)was used and whether Hif-2α inhibitor PT2385 was used,the normal diet groups and the high fat diet groups were randomly divided into a normal diet control group(Control group,8 mice),a DSS-drinking normal diet group(DSS group,8 mice),a DSS-drinking normal diet group with PT2385treatment(DSS+PT2385 group,8 mice),a high fat diet group(HFD group,8 mice),a DSS-drinking high fat diet group(HFD+DSS group,8 mice),8),a DSS-drinking high fat diet group with PT2385 treatment(HFD+DSS+PT2385 group,8 mice).Mice in PT2385 treatment groups were given PT2385(10mg/kg)once a day by intragastric administration from the 18 th day of the experiment until the end of the experiment.Mice in the non-PT2385 treatment groups were given the same dose of blank solvent.Mice in DSS-drinking groups drank distilled water containing 3%DSS to drink continuously for 7days from the 38 th day of the experiment.On the eighth day of DSS modelling,all mice were sacrificed to collect serum and colon tissue samples.The changes of body mass,disease activity index(DAI)and colon histopathological scores were evaluated in each group.The expression levels of interleukin-6(IL-6),tumor necrosis factor-α(TNF-α)and interleukin-10(IL-10)in the serum of mice were detected by ELISA.The expression of Hif-2α and mitophagy key pathway PINK/Parkin in the intestinal mucosal tissues of mice in each group were detected by RT-q PCR and Western blotting.Results: The high-fat diet model in mice was successfully induced with high fat diet.The difference of body mass in high-fat diet groups was higher than that in normal diet groups(P<0.05).DSS successfully induced acute colitis model in mice.After drinking3%DSS,body weights of mice in DSS group,HFD+DSS group,DSS+PT2385 group and HFD+DSS+PT2385 group decreased(P<0.05),and the body weights of HFD+DSS group decreased more significantly(P<0.05),while the body weights of mice in non-DSS group still increased.The scores of DAI,colonic histopathological scores and serum levels of IL-6 and TNF-α in DSS group and HFD+DSS group were higher than those in Control group(P<0.05)and HFD group(P<0.05).HE staining of pathological slices of mice in HFD+DSS group showed the most severe inflammatory reaction in colon tissue and the highest pathological score.Serum IL-10 expression level in DSS group and HFD+DSS group was lower than that in corresponding Control group(P<0.05)and HFD group(P<0.05).Compared with Control group and HFD+DSS group,Hif-2αexpression and mitophagy pathway PINK/Parkin expression were up-regulated in DSS group and HFD+DSS group(P<0.05).After drinking DSS,compared with the non-PPT2385 treatment group(DSS group,HFD+DSS group),the body mass decline,DAI,colonic histopathological scores,serum IL-6 and TNF-α levels,the Hif-2αexpression level of PT2385 drug treatment group(DSS+PT2385 group,HFD+DSS+PT2385 group)were lower in colon tissues(P<0.05);Serum IL-10 expression level and mitophagy pathway PINK/Parkin expression level were higher(P<0.05).Conclusion: PT2385,a drug that inhibits Hif-2α,can induce up-regulated expression of PINK/Parkin in mitophagy pathway,relieve intestinal mucosal tissue inflammation,and reduce the levels of serum pro-inflammatory cytokines IL-6 and TNF-α under high-fat diet.It is suggested that Hif-2α may be negatively correlated with mitophagy level in mouse intestinal epithelial cells.Hif-2α inhibitor may regulate mitophagy in intestinal epithelial cells through PINK/Parkin pathway,thereby alleviating intestinal inflammation in mouse colitis model.Mitophagy may play an anti-inflammatory role in ulcerative colitis. |
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