Hepatoprotective Activity And Mechanism Of Engineered Microbes S.C-AF On Aflatoxin B1-induced Liver Injury In Mice

Aflatoxin B1(AFB1)is an extremely lethal fungal toxin that is thought to be a major risk factor for liver cancer.There are no particularly effective control measures for reducing AFB1 pollution and inhibiting AFB1 toxicity.Therefore,we constructed an engineering fungus,S.cerevisiae-p YD1-Sc Fv-AFB1(S.C-AF),which can display anti-AFB1 single-chain antibody on the surface of Saccharomyces cerevisiae by using cell surface display technology.Firstly,the probiotic properties and AFB1 binding ability of S.C-AF were evaluated in vitro.On this basis,a mouse model of liver injury in mice induced by AFB1 exposure was further constructed to investigate the intervention effect and potential mechanism of S.C-AF on liver injury of mice induced by AFB1 based on environmental toxicology,histology,molecular biology,and intestinal microecology,thus to clarify the synergistic effect of S.C-AF engineering transformation and probiotic properties in the treatment of liver injury of mice induce by AFB1.The main results and conclusions are as follows:(1)Effect of S.C-AF on liver injury of mice induced by AFB11)S.C-AF possessed excellent probiotic properties of acid resistance,bile salt resistance and oxidation resistance,and its ability to bind AFB1 was about 1.7 times that of S.C.2)S.C-AF intervention reduced the content of AFB1-DNA adduct in the liver of mice exposed to AFB1 by 42.8%,and increased the excretion of AFB1 in feces by 5.7times.3)S.C-AF significantly reduced the liver injury of mice induced by AFB1 exposure,and inhibited cell apoptosis by increasing Bcl-2/Bax,reducing the expression of cleave caspase-3/caspase-3 pro-apoptotic gene,and simultaneously down-regulated the expression of pro-inflammatory factors IL-6,TNF-α and IL-1β in liver to alleviate liver inflammation.(2)Mechanism of S.C-AF in alleviating liver injury of mice induced by AFB11)S.C-AF promoted the production of T-AOC,SOD,GSH and CAT in the liver by activating the Nrf2 signal pathway and the expression of downstream antioxidant genes such as HO-1,NQO-1 and GCLC,so as to exert the antioxidant capacity and reduce the oxidative stress damage of the liver caused by AFB1.2)S.C-AF inhibited the expression of inflammatory factors IL-6,TNF-α and IL-1β in the intestinal tract to regulate immune responses.It also improved the intestinal barrier function by increasing the expression of Occludin-1 and ZO-1proteins.3)S.C-AF increased the abundance of Lactobacillus,Akkermansia,Muriaculacea,and Lachnospiracea through the probiotic properties of host fungus S.cerevisiae,reshaping the intestinal flora homeostasis and reducing liver damage.