The Effect And Mechanism Of Lactobacillus Brevis 23017 Against Intestinal Oxidative Damage

Oxidative stress can cause oxidative damage to the body,thereby inducing a wide range of syndromes in humans and animals.It has a high incidence,strong concealment,and great harm,which will pose a great threat to human health and the development of animal husbandry.At present,the intestinal diseases caused by pathogenic bacteria are mostly treated with antibiotics,but the use of antibiotics will make the bacteria easy to develop drug resistance,and thus cannot effectively control the intestinal diseases caused by bacterial infection.Probiotic lactic acid bacteria have many excellent properties such as regulating intestinal microecological balance,enhancing body immunity and antioxidant function,showing good application prospects in solving intestinal health problems,and can also effectively prevent the abuse of antibiotics and generate new drug resistance strains,etc.Current studies have found that the mechanism of lactic acid bacteria to protect the intestine includes maintaining the intestinal microbial barrier,inhibiting the colonization of pathogenic bacteria,promoting the secretion of intestinal mucus,promoting the immune response of the intestine,and inhibiting the apoptosis of intestinal epithelial cells.However,there are few studies on the mechanism of lactic acid bacteria protecting the intestine from the perspective of antioxidants,especially the role and mechanism of the most important Nrf2 antioxidant pathway in the process of probiotic lactic acid bacteria against bacterial infection-induced intestinal damage is not clear.L.brevis 23017,isolated in our laboratory,has been shown to alleviate mercury toxicity in the colon and antagonize Yersinia enterocolitica by modulating oxidative stress and inflammation through the interaction of the MAPK and NF-κB signaling pathway cascades Intestinal infection,is a probiotic with high anti-inflammatory and antioxidant activity.Our study aimed to use its effect on indomethacin(IND)and S.typhimurium in the BALB/c mouse model of intestinal oxidative damage,to verify the effect of L.brevis 23017 on intestinal antioxidant capacity and intestinal mucosal immunity.and whether L.brevis 23017 protects the gut from oxidative damage is regulated by the Nrf2 signaling pathway;and at the molecular level to analyze the mechanism by which the Nrf2 signaling pathway plays an antioxidant function in the antioxidant process of lactic acid bacteria,and establishes intestinal immune regulation The specific link between s Ig A and the Nrf2 antioxidant signaling pathway.First of all,we established an indomethacin mouse model of intestinal oxidative damage with a clear mechanism and quantitative control of drug dose,and used this model to detect the effects of L.brevis 23017 on the intestinal antioxidant capacity and intestinal mucosal immunity of mice.This model was used to detect the effects of L.brevis 23017 on the intestinal antioxidant capacity and intestinal mucosal immunity of mice.The results showed that:(1)L.brevis 23017 could significantly alleviate the body weight of mice caused by indomethacin after continuous feeding.decline.(2)The observation of pathological sections confirmed that L.brevis 23017 inhibited the pathogenic effect of indomethacin in vivo,and the infiltration of inflammatory cells in the ileum and duodenum of mice was reduced and the intestinal villi were more intact.(3)L.brevis 23017 positively regulates the dysregulation of the intestinal antioxidant enzyme system caused by indomethacin,and promotes the levels of antioxidant enzymes(GSH,SOD,T-AOC)in mice.(4)L.brevis 23017 can produce more s Ig A in the intestine of mice in the oxidative damage model,promote the occurrence of intestinal immunity,and maintain the healthy state of the intestine.The contents of IL-5,IL-10 and IL-13 cytokines in serum There is an upward trend.(5)In mice fed with L.brevis 23017,the levels of Nrf2,HO-1,NQO1 m RNA in intestinal tissue were significantly increased,and the m RNA contents of COX-2 and INOS were decreased.(6)L.brevis 23017 can induce and increase the protein expression levels of NQO1,Nrf2,HO-1 and Keap1,indicating that L.brevis 23017 promotes the expression of antioxidant proteins related to the Nrf2 signaling pathway and alleviates oxidative damage in the intestine.Then,the anti-oxidative damage of Salmonella by lactic acid bacteria was evaluated,and the change trend of each index was compared with the indomethacin mouse model,which made the study more convincing.The test results showed that:(1)After S.typhimurium infection,the intestinal tract of mice had obvious oxidative damage,and the intestinal antioxidant enzyme system of the mice was imbalanced(the levels of GSH,SOD,and T-AOC were decreased),which confirmed the occurrence of oxidative stress in the body.Intestinal oxidative damage is a novel pathogenic mechanism in the process of intestinal diseases caused by Salmonella infection.(2)L.brevis 23017 against S.typhimurium infection is manifested in alleviating the occurrence of clinical symptoms such as diarrhea and back hair standing,depression,and decreased diet in mice,slowing down the weight loss of mice,inhibiting the colonization of S.typhimurium in the intestinal tract and promotes its excretion and protects the healthy state and structural integrity of the intestinal mucosa.(3)The protection of the intestine by L.brevis 23017 is related to the promotion of the secretion of s Ig A in the intestinal mucus,and the faster secretion and function of intestinal antibodies.(4)L.brevis 23017 protects the intestinal tract and promotes the secretion of IL-5,IL-10 cytokines in serum,inhibits the inflammatory response in the intestinal tract of mice,and promotes the occurrence of cellular immunity in the body.(5)RT-q PCR detection results showed that the m RNA expression levels of Nrf2 signaling pathway-related factors and J-chain,and plg R intestinal immune-related factors in intestinal tissue increased,and the m RNA contents of COX-2 and INOS decreased.;IL-10 anti-inflammatory factor and OCLN,ZO-1 and other intestinal tight junction protein m RNA expression levels increased,indicating that L.brevis 23017 positively regulates inflammatory factors,lymphokines,intestinal mucosal barrier genes and Nrf2 signaling pathway related factor gene expression,reducing intestinal oxidative damage.(6)Western blot results showed that L.brevis 23017 could positively regulate the expression levels of NQO1,HO-1 and Keap1 antioxidant proteins,and reduce the oxidative damage of the intestinal tract caused by S.typhimurium infection,confirming that the Nrf2 signaling pathway is involved in L.brevis 23017 plays an important role in the process of anti-bacterial infection.Through the two established mouse models,we demonstrated that feeding L.brevis 23017 can activate the Nrf2 signaling pathway in mice under the condition of intestinal oxidative damage,induce and regulate the expression levels of NQO1,HO-1 and Keap1 antioxidant proteins,Reduce the oxidative damage of the intestine caused by the body’s oxidative stress.It is proposed for the first time that probiotic lactic acid bacteria can promote the expression of s Ig A-related factors in intestinal immunity through the Nrf2 antioxidant pathway,and can play an immunoregulatory role,reduce the degree of oxidative damage to the intestinal mucosa,affect the body’s innate immune response,and promote the body’s intestinal antibody.Faster secretion and action.This study provides new data reference and theoretical support for the analysis of the antibacterial effect and mechanism of lactic acid bacteria,and also lays the foundation for further research on the relationship between the anti-oxidative effect of probiotic lactic acid bacteria and intestinal mucosal immunity.