Protective Effect Of Coated Benzoic Acid On Intestinal Injury Of Mice Infected With Enterotoxigenic Escherichia Coli

This study was aimed to investigate the protective effects of coated benzoic acid(BA)on intestinal damage of mice infected with Enterotorigenic Escherichia coli(ETEC)and its mechanism.Select 90 only 3 weeks of BALB/c female mice,were randomly divided into 5groups,each group of 6 repeat,repeat 3 mice each.Hens in control group(CON group)and challenge group(ETEC group)were fed a basal diet,and the others in the three coated benzoic acid groups were fed the basal diet supplemented with 1.0%(BA-L),1.5%(BA-M)and 2.0%(BA-H)coated benzoic acid,respectively.On the 15th day of the experiment,mice in the CON group were intraperitoneally injected with PBS solution,and mice in the other four groups were intraperitoneally injected with enterotoxigenic Escherichia coli solution(1×10~5 CFU/m L)at an injection volume of 0.1 m L/10 g body weight.Then continued to feed the corresponding diets of each group.The experiment lasted for 21 days.The test results show that:(1)After challenge,the body weight of mice in ETEC group and BA-L group was significantly lower than that in CON group(P<0.05).Compared with CON group,spleen index of ETEC group(1,7 d;P<0.05)and renal index(1 d;P<0.05)were significantly increased,and the cardiac index and kidney index of mice in BA-L,BA-M and BA-H groups were significantly increased(1 d,P<0.05).Compared with ETEC group,serum contents of IL-1β(1,7 d),TNF-α(1,7 d)and INF-γ(1,7 d)in BA-M group were significantly decreased(P<0.05),the contents of TNF-α(1 d)and INF-γ(1 d)in serum of BA-H group were significantly decreased(P<0.05).(2)Compared with ETEC group,the villus height and V/C of jejunum in BA-M group were significantly increased(1,7 d;P<0.05),the V/C of jejunum in BA-H group was significantly increased(7 d;P<0.05).Compared with ETEC group,BA-L group significantly down-regulated ETEC-induced jejunal mucosa My D88 m RNA expression quantity(1 d;P<0.05),BA-M group could significantly down-regulate the expression quantity ETEC induced TLR-2 m RNA(1 d)and My D88 m RNA(1,7 d)in jejunum mucosa induced by ETEC(P<0.05),and BA-H group could significantly inhibit ETEC-induced up-regulation of My D88 m RNA expression quantity(7 d;P<0.05).Compared with ETEC group,serum D-LA content and DAO activity in BA-L,BA-M and BA-H groups were significantly decreased(1 d;P<0.05).Compared with ETEC group,BA-M group significantly up-regulated the expression quantity of ZO-1 m RNA(7 d)and Occludin m RNA(1 d,7 d)of jejunum mucosa induced by ETEC(P<0.05),BA-H group can significantly up-regulate ETEC-induced jejunum mucosal Occludin m RNA(7 d;P<0.05)expression quantity.(3)Compared with ETEC group,the observed＿species index of BA-L and BA-M groups was significantly increased(7 d;P<0.05);The simpson index of BA-H group was significantly higher than that of ETEC group(7 d;P<0.05).PCo A results showed that the intestinal flora composition of the BA-H group was significantly shifted to that of the CON group(7 d).After the challenge,Bacteroidetes and Firmicutes were dominant bacteria in the intestinal microbiota of mice(1,7 d),and Faecalibaculum was dominant bacteria(1,7d).Compared with CON group,ETEC group Erysipelatoclostridiaceae bacteria,Erysipelatoclostridium species abundance increased significantly(1 d;P<0.05).The relative abundance of Erysipelotrichaceae and Faecalibaculum in the intestinal microbiota of mice in BA-M group was significantly increased(7 d;P<0.05).The contents of acetic acid and butyric acid in caecal digesta of mice in BA-L group were significantly higher than those in ETEC group(1 d;P<0.05),the contents of acetic acid(1 d)and butyric acid(7 d)in cecal digesta of mice in BA-M group were significantly increased compared with ETEC group(P<0.05),and butyric acid content in BA-H group was significantly increased compared with ETEC group(7 d;P<0.05).At the genus level,on 1 days after challenge,the relative abundance of Bacteroides was significantly positively correlated with INF-γ,DAO and D-LA in serum(P<0.05).The relative abundance of Parasutterella was positively correlated with DAO activity in serum(P<0.05),and was significantly negatively correlated with butyric acid content in cecal digesta(P<0.01).On 7 days after challenge,the relative abundance of Megasphaera and Prevotella＿9 was significantly negatively correlated with serum IL-1βcontent and DAO activity(P<0.01),and had significant positive correlation with butyric acid content in cecal digesta(P<0.05).The relative abundance of Staphylococcus was positively correlated with serum DAO activity(P<0.05),and was negatively correlated with butyric acid content in cecal digesta(P<0.05).In conclusion,dietary cold-sprayed coated benzoic acid can improve the immune function,intestinal barrier function and intestinal flora structure of mice,so as to alleviate the intestinal injury induced by ETEC.