Validation And Mechanism Exploration Of Alleviating Liver Injury In Cadmium-exposed Mice Based On Engineered Bacteria EcN-MT

Cadmium(Cd)pollution is becoming increasingly serious,making Cd exposure a widespread problem.The liver is the main target organ for Cd exposure,but there is still a lack of effective means to treat liver injury caused by Cd exposure.Therefore,in this study,an engineered strain expressing metallothionein(MT),named Escherichia coli Nissle1917(Ec N)-MT,was constructed,and it is growth characteristics,plasmid stability,acid tolerance,bile salt tolerance,and antioxidant properties were evaluated from the perspective of the probiotic properties of EcN-MT,and the binding ability of EcN-MT to Cd ions was investigated in detail.Meanwhile,the therapeutic effects of EcN-MT on subchronic Cd-exposed mice models were evaluated in terms of histology,molecular biology,and microecology,and detailed studies were conducted from the perspectives of fibrosis,oxidative stress,inflammation,apoptosis,and intestinal microbiome disorders caused by Cd exposure.Finally,based on the determination that EcN-MT has good efficacy,the molecular mechanism of its specific action was further explored to clarify the compound relationship between MT therapeutic effect and Ec N probiotic properties in the therapeutic effect of EcN-MT engineered bacteria.The main research conclusions are as follows:(1)EcN-MT has excellent probiotic properties,and its ability to bind Cd is 3.6 times higher than that of Ec N probiotics,which has the potential to treat Cd exposure.(2)EcN-MT treatment reduced Cd content in liver tissues of Cd-exposed mice by 26.3% and increased Cd excretion in feces by 24.7%,while significantly reducing liver lesions,fibrosis,and oxidative stress,thus improving hepatotoxicity in subchronic Cd-exposed mice.(3)EcN-MT inhibited the activation of TLR4/NF-κB inflammatory signaling pathway through the expression of MT,which in turn inhibited the expression of regulatory death,inflammatory cytokines,fibrosis and oxidative stress associated with it,and reduced liver injury.(4)EcN-MT significantly increased the abundance of probiotic bacteria such as Akkermansia,Muribaculaceae,Lachnospiraceae,and Dubosiella in the mouse intestine through the probiotic nature of the host bacteria Ec N,which reshaped the intestinal microbiome homeostasis thereby reducing liver injury.