Lactobacillus Bulgaricus Or Lactobacillus Rhamnosus Mitigate Liver Inflammatory Response Induced By AFB1 Via NF-?B Signaling Pathway

Aflatoxin B1(AFB1),a mycotoxin widely found in nature,is highly toxic and carcinogenic.AFB1 pollution is common in food and feed,posing significant threat to the development of the food industry and agriculture and animal husbandry,and indirectly endangering human health.In recent years,the strict requirements of feed ingredient procurement and quality control have led to a certain degree of control of mycotoxin contamination,but the detection rate of mycotoxins in corn,soybean meal and compound feed is still at a high level.Therefore,it is imperative to seek effective aflatoxin antidote.To overcome aflatoxin toxicity,probiotic-mediated detoxification has been proposed by some researchers.Our previous studies have found that the compound lactic acid bacteria CS could effectively alleviate the hepatic damage caused by AFB1 in chickens,but the strains that play a major role and their mechanism of action remains unclear.In this experiment,Lactobacillus bulgaricus and Lactobacillus rhamnosus,two major strains of compound lactic acid bacteria CS,was selected to explore their antagonism and protective mechanism against AFB1 poisoning.In the present study,to investigate the protective effects and molecular mechanisms of L.bulgaricus or L.rhamnosus against liver inflammatory responses to AFB1,the KM mice were randomly divided into five groups,and administered with AFB1(300 ?g/kg)?L.bulgaricus(10mg/mouse)?L.rhamnosus(10 mg/mouse)intragastrically for 8 weeks.After the experiment,the data of body weight and liver index of mice were counted.The histopathological changes were observed.The serum and liver were collected for measuring biochemical indices,cytokines and activation of the NF-?B signaling pathway.At the same time,different concentrations of L.bulgaricus and L.rhamnosus were used to stimulate mouse hepatocytes(AML12)to screen optimal concentration of lactic acid bacteria which had no effect on cell viability.Then,AML12 cells were cultured and treated with AFB1,BAY 11-7082(an NF-?B inhibitor),and the optimal concentrations of L.bulgaricus or L.rhamnosus for six different treatment in 1,2,4 and 12 h.After the stimulation,the cells and cell culture supernatant were collected for measuring the expression of NF-?B signaling pathway-related proteins,inflammatory cytokines and the concentration of inflammatory cytokines.The results of the vivo experiments showed that the liver tissue of AFB1 exposed miceshowed obvious lesions and partial hepatocyte necrosis;liver index increased significantly(P<0.05);serum liver function index AST and ALT levels increased significantly(P<0.05),liver function index TP and renal function index BUN and CREA content was significant decreased(P<0.05);the levels of serum inflammatory cytokines IL-1?,TNF-? and IL-6 levels were significantly increased(P<0.05,P<0.01),IFN-? level was significantly decreased(P<0.01);the expression of liver inflammatory cytokine TNF-? m RNA and inflammatory signaling pathway NF-?Bp65 m RNA and protein were significantly up-regulated(P<0.01),and the expression of I?B? protein was significantly decreased(P<0.01).However,supplementation of L.bulgaricus or L.rhamnosus reversed the changes in the above indicators caused by AFB1 to varying degrees.In vitro experiment,1.2 mg/m L L.bulgaricus and 0.5 mg/m L L.rhamnosus were selected for the final stimulation doses which had no significant effect on AML12 cell activity.The results of the vitro experiments showed that L.rhamnosus significantly reduced AFB1-induced the secretion of extracellular inflammatory cytokines in AML12 cell.Both L.bulgaricus and L.rhamnosus significantly inhibited AFB1-induced activation and expression of NF-?B and expression of IL-1? and TNF-? m RNA in AML12 cells.The final results of the vitro experiments were basically consistent with the results of the vivo experiments.The above results indicated that AFB1 exposure can cause hepatitis and hepatocyte injury,while L.bulgaricus or L.rhamnosus can antagonize AFB1-induced liver damage and inflammatory response and reduce the secretion amount of inflammatory cytokines by regulating the activation of the NF-?B signaling pathway.It also showed that L.bulgaricus and L.rhamnosus have the potential to antagonize the toxicity of AFB1,and can be further study and convert into feed additives to reduce the harm of mycotoxins to animal husbandry.