The Role Of Autophagy In Perfluorooctanoic Acid-induced Liver Metabolic Disorder And NLRP3 Inflammasome Activation

Objective: Perfluorooctanoic acid(PFOA)is one of the most widely used perfluoroalkyl substances(PFASs).Its stability and wide application have attracted serious attention to the potential health risks.Exposure to excesive PFOA can lead to liver inflammation and induce imbalance of lipid synthesis and degradation,thus resulting in nonalcoholic fatty liver(NAFLD).However,the specific mechanism is not fully elucidated.This study explores the molecular mechanisms of liver lipid accumulation and inflammation caused by PFOA and provides scientific basis for the prevention and treatment of PFOA induced liver injury.Methods: Twelve male C57/B6 mice were randomly divided into the control group(corn oil)and the PFOA exposure group(1 mg/kg/day).Mice in the PFOA group were given direct gavage for 28 consecutive days.The control group was given the same amount of corn oil.During the period,the survival status and weight of each group were recorded.In vitro,L-02 cells were treated with 0,10,50 μM PFOA for 24 hours.After 28 days of experiment,liver samples were collected for further study.The liver histomorphological changes were observed by H&E staining,oil red staining,and the content of triglyceride(TG)in the liver tissues were detected to observe the lipid accumulation in the liver,and the blood glucose level was evaluated by oral glucose tolerance test(OGTT)and Insulin tolerance test(ITT).Immunohistochemical assay was performed to detect interleukin-1 levels,and Western blots were used to detect expression levels of NLRP3,clv-caspase-1,lipid-producing related proteins sterol regulatory element binding protein(SREBP1),fatty acid synthase(FAS),acetyl-coa carboxylase(ACC),stearyl coa desaturase(SCD1)and autophagy related proteins LC3 and p62 in mouse liver and L-02 cells.Autophagy flow was detected by adenovirus.Furthermore,autophagy activator-rapamycin or autophagy inhibitor-chloroquine were used to assess the effects of autophagy on lipid accumulation and NLRP3 inflammasome activation.Results: Compared with control group,mice exposed to PFOA for 28 days had no significant change in body weight but significantly increased liver weight.H&E and oil red O staining in the liver of PFOA treated mice showed Inflammatory cell infiltration and lipid droplet accumulation.OGTT as well as ITT showed impaired glucose tolerance and TG levels elevated in PFOA group.PFOA up-regulated levels of SREBP1 c and its downstream genes including FAS,ACC and SCD1.In addition,PFOA induced the activation of NLRP3 inflammaome and the release of IL-1β.Furthermore,compared to the control group,autophagy-related genes,including LC3 and p62 were also increased in PFOA group,suggesting that PFOA can cause dysfunction of autophagy degradation.Immunofluorescence results also suggested that PFOA treatment caused autophagy blockade in L-02 cells.Rapamycin,an autophagy attractor,and chloroquine,an autophagy inhibitor,can reduce and exacerbate PFOA-induced lipid accumulation and inflammation,respectively.Conclusion: Our study showed that,PFOA induced the blockade of autophagic flux caused the increase of lipid synthesis and inflammation in vivo and in vitro.