Study On The Expression Characteristics Of ACE2 In Broiler Chickens Of Different Ages,Sexes And Salmonella Enteritidis Infection

Angiotensin-converting enzyme Ⅱ(ACE2)can reduce intestinal inflammation,regulate the absorption of intestinal amino acids and maintain the homeostasis of intestinal flora.Salmonella enteritidis is a zoonotic disease that can induce poultry intestinal inflammation and reduce broiler performance.Therefore,to study the expression characteristics of ACE2 in broiler tissues,explore the changes of ACE2 and related genes in Salmonella infection,in order to bring a new breakthrough in the treatment of Salmonella enteritidis.Trial 1 Expression characteristics of ACE2 mRNA in broiler tissuesAA broilers were fed to 9 and 42 days old,and six male and female females of each age were randomly selected for slaughter.The heart,lung,liver,trachea,gallbladder(bile removal),kidney,duodenum,cecum,bursa farce,thymus,jejunum and ileum were collected aseptic,and the expression of ACE2 mRNA in each tissue was measured.The results show that:(1)The expression of ACE2 mRNA in ileum and jejunum of females AA broilers at 9 days old was significantly higher than that in other tissues(P<0.05).and the expression of ACE2 mRNA in trachea,lung and bursa was the lowest(P<0.05).(2)The expression of ACE2 mRNA in the duodenum,cecum,kidney,liver,jejunum,heart and trachea of male AA broiler was significantly higher than that of female(P<0.05).The opposite results were found in the ileum,gallbladder and lung tissues(P<0.05).(3)The ACE2 mRNA expression in duodenum,jejunum,cecum,lung,trachea,bursa of fabric,thymus,heart,gallbladder and kidney tissues of 42 days were significantly lower than those of 9 days of age AA broilers(P<0.05),meanwhile,the results were opposite in the ileum and liver tissues(P<0.05).Trial 2 Expression characteristics of ACE2 and related genes in broilers infected with Salmonella enteritisThe experiment was divided into 3 groups with 30 birds in each group.The blank control group(NC group)and salmonella enteritis challenge group(SE group)were fed with basal diet,while the antibiotic group(SE+EnFX group)was fed with 200g/t enrofloxacin basal diet.When the chicks in SE group and SE+EnFX group were fed to 8 days old,the concentration of 500 μL was 2×109 cfu/mL salmonella enteritis solution(CMCC50041,purchased from Beijing BeiNa Chuanglian Biotechnology Research Institute Mall Branch)were fed orally,and that of NC group was fed orally 500 μL PBS solution.The feeding experiment lasted for 9 days,and the body weight and morbidity of 1,8 and 9 day were recorded.24 hours after challenge,6 animals in each group were randomly slaughtered and samples were collected to determine the changes of intestinal morphology,ACE2 and related genes in Salmonella enteritis infection.The results show that:(1)The body weight of broilers in the SE group was lower than that in the NC group for 24 hours(9 days of age)after challenge(P=0.08)(2)Salmonella content in liver and spleen of SE group was significantly higher than that of NC group(P<0.05).In SE group,heterophil infiltration was found in the liver and slight bleeding in the white pulp of the spleen.The results showed that the infection model of Salmonella enteritis was successfully constructed.(3)Salmonella enteritidis infection was significantly reduced the duodenal VH,MT and VCR,and significantly increase CD of the duodenal.reduce jejunum VH and MT,and reduce the ileal VCR(P<0.05).(4)Salmonella enteritidis infection caused a significant increase in duodenal ACE2 mRNA expression and a significant decrease in cecal ACE2 mRNA expression(P<0.05).(5)The expression of mTOR mRNA in the small intestine and cecum of the NC group was significantly higher than that of the SE group(P<0.05).The expression of B0AT1 mRNA in the duodenum,jejunum and cecum of the NC group was significantly higher than that of the SE group(P<0.05).(6)Salmonella enteritidis infection can significantly reduce the expression of AvBD9 mRNA in the small intestine and cecum of broilers,and decrease the expression of CATH2 mRNA in the duodenum,jejunum,and cecum.The addition of antibiotics can restore the expression of CATH2 mRNA in the duodenum and jejunum(P<0.05)(7)Salmonella enteritidis infection can significantly reduce the expression of Occludin mRNA in the cecum of broilers,decrease the expression of Claudin-1 mRNA in the duodenum,and decrease the expression of ZO-1 mRNA in the small intestine and cecum(P<0.05).(8)Salmonella enteritidis infection will change the abundance of the intestinal flora of broilers,increasing the abundance of the pro-inflammatory Megamonas,and the addition of antibiotics can increase the abundance of intestinal Lactobacillus.In summary,the expression of ACE2 mRNA in the intestine of broilers is the highest,and it is specific between the age and sex of the broiler,which suggests that ACE2 is related to the age,sex and physiological function of the intestinal tract of the broiler.In addition,Salmonella enteritidis infection can affect the expression of ACE2 and related genes in the intestine of broilers,and increase the relative abundance of harmful bacteria in the cecum.This suggests that ACE2 and related pathways may play a role in anti-Salmonella enteritidis infection.