Signaling Machanism Of Astaxanthin Intervention In Alcoholic Liver Injury Inflammatory Response

The morbidity rates of alcoholic liver disease(ALD)are increased year by year.It has become a common disease that endangered human health in worldwide.Therefore,it has important significance to study the pathogenesis and intervention strategies of ALD.Long-term alcohol consumption could cause various types of injuries in the organs and tissues of the human body.Because of the obvious symptoms,liver has become the focus of the research.However,the proposition of gut-liver axis theory urged researchers to investigate the effect of gut microbiota on whole body.It is a theory that explained the relationship between gut and liver diseases from a holistic perspective.The inflammatory response is a self-protective reaction when the body was stimulated.When the regulatory function of inflammatory response is imbalanced,it will lead to a variety of diseases.Oxidative stress and inflammatoy response induced by alcohol stimulation are the major pathogenesis of ALD.The signaling pathways for inflammatory response,such as NF-?B,TLRs,NLRs and MAPK are closely related to the ALD development.The regulation of these signaling pathways will become a new strategy for the intervention and treatment of alcoholic liver injury.Astaxanthin(AST)is the only non-vitamin A pro-oxidized carotenoid with strong antioxidant activity,which not only exhibits excellent antioxidant function,but also has ability to anti-stress,anti-inflammatory,anti-apoptosis and immunoregulation.It is a functional natural pigment that need to be further explored and utilized.Recent studies have shown that AST can inhibit non-alcoholic fatty liver steatosis,fibrosis and alleviate insulin resistance.but until now,the mechanism of astaxanthin intervention in the long-term chronic alcoholic liver injury model has not been reported.C57BL/6J male mice were randomly divided into normal diet group(ND),highfat diet control group(Con),astaxanthin group(AST),alcohol group(Et)and astaxanthin intervention alcohol group(EtAST).Animals were fed Lieber-DeCarli control(isocaloric maltose-dextrin)or ethanol(5% w/v)liquid diets ad libitum for 10 weeks to establish ALD model and intervened with astaxanthin.The metabolic characteristics were detected,and the liver tissues histology were checked by immunohistochemical staining.In addition,feces were collected for gut microbiota 16 SrRNA genes amplification.Liver tissues were used for RNA-sequencing(RNA-Seq)and western blot analyses.The aim of this study is to evaluate the effect of astaxanthin intervention on the inflammatory response of alcoholic liver injury and its molecular mechanism.The results indicated:1.AST depressed the serum level of ALT,AST and LPS,inhibited liver inflammatory cytokines and reduced hepatocytes apoptosis.It could also decrease mice body weight and liver-body weight ratio.The content of serum TG,LDL and ADP showed a significant decrease in EtAST group compared with Et group.Histological examination of the liver samples and analysis of Oil-Red-O staining revealed that AST improves fat accumulation and reduces inflammatory cell infiltration.Taken togethor,these results indicate that AST has a protective effect on alcoholic liver injury.2.Based on the result of liver RNA-seq analysis,the number of DEGs in groups have a significant difference.Compared with Con group,Et group increased the genes expression level of inflammatory signaling pathway,such as Toll-like receptor signaling pathway,NOD-like receptor signaling pathway and chemokine pathway.However,AST intervention reversed the ethanol-mediated overexpression of inflammatory cytokine.Further study revealed that astaxanthin could inhibit the expression of inflammatory cytokines by regulating the inflammatory signaling pathway,such as Toll-like receptor signaling pathway,NOD-like receptor signaling pathway,MAPK signaling pathway and NF-?B signaling pathway.Thus,it can protective mice from liver injury.3.The Metastats analysis of feces 16 SrRNA indicate that astaxanthin intervention significantly decreased the abundance of Bacteroidetes and Proteobacteria phylum and increased the abundance Verrucomicrobia phylum,which is similar to Con group.However,Et group showed the opposite variation.These results indicated that astaxanthin intervention changed the composition of gut microbiota and improved the imbalance caused by alcohol.In conclusion,according to the gut-liver axis theory,we evaluated the effects of astaxanthin on alcoholic liver disease from several aspects such as blood,liver tissue,gut microbiota,gene and protein expression level.We found that astaxanthin can regulate the genes expression of inflammatory signaling pathway,affect the structure and composition of gut microbiota and promote the decrease of inflammatory factors in the serum.The blood levels of endotoxin and adiponectin are significantly reduced,the levels of enzymes related to liver damage were decreased.Furthermore,fat deposition in liver was also alleviated.These results confirmed that astaxanthin has obvious protective effect on alcoholic liver disease.This work provides a new direction for further studies and application of astaxanthin.