| Liver injury is one of the most serious complications in heat stress(HS)cases,and its mechanisms include oxidative stress(OS)and inflammation.A large number of bioactive peptides produced by hydrolysis of camel whey protein(CWP)have obvious antioxidant and anti-inflammatory activities,but their protective effects on hepatocyte injury induced by HS have not been reported.Therefore,the purpose of this study is to explore whether hydrolyzed CWP(S-CWP)can protect BRL-3A rat hepatocytes from HS through antioxidant and anti-inflammatory mechanisms.CWP was prepared from fresh camel milk samples by centrifugation and ammonium sulfate precipitation,and CWP was hydrolyzed by pepsin and trypsin according to the simulated gastrointestinal digestion procedure.BRL-3A cells were treated with HS in 43 °C cell incubator for 1 h to establish the model of hepatocyte injury induced by HS.The protective effect of S-CWP on this kind of liver injury was evaluated by analyzing cell OS,inflammatory reaction,apoptosis,biomarkers of liver function,activities of several antioxidant enzymes and cell survival rate.Western blotting method was used to detect the expression level of key proteins in related signal pathways to analyze the protective mechanism of S-CWP on hepatocyte injury induced by HS.The results showed that S-CWP decreased the production of reactive oxygen species(ROS),nitric oxide(NO)and 8-hydroxy-2-deoxyguanosine(8-OHd G)induced by HS,and inhibited lipid peroxidation(LPO),protein carbonylation(PCO)and nicotinamide adenine dinucleotide phosphate(NADPH)oxidase activity.At the same time,it enhanced the activities of superoxide dismutase(SOD),catalase(CAT),glutathione peroxidase(GSH-Px)and heme oxygenase-1(HO-1)in hepatocytes,and finally alleviated the induced oxidative stress in hepatocytes.S-CWP reduces the expression of NLR family pyrin domain protein 3(NLRP3)inflammatory bodies and cysteine protease-1(caspase-1)by inhibiting HS-induced phosphorylation of nuclear factor-κ B(NF-κ B)p65 in hepatocytes,thereby alleviating HS-induced inflammation and finally reducing cysteine protease-3(caspase-3)-mediated hepatocyte apoptosis.S-CWP decreased the levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST)and alkaline phosphatase(ALP)in the supernatant of cell culture,indicating that it finally alleviated the hepatocyte injury induced by HS.In addition,S-CWP significantly enhanced the expression of NF-E2-related nuclear factors erythroid 2(Nrf2)and HO-1 in hepatocytes,and the specific Nrf2 inhibitor ML385 weakened its antioxidant and anti-inflammatory effects.Zinc protoporphyrin(Zn PP),a specific HO-1 inhibitor,significantly reversed the inhibitory effect of S-CWP on NF-κ Bp65 phosphorylation.Therefore,these results suggest that S-CWP can inhibit NF-κ B/NLRP3 axis by activating Nrf2/HO-1 signal pathway to protect hepatocytes from oxidative stress,inflammation,apoptosis and injury induced by HS. |
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