Effect Of Pathogenic E.Coli K99 From Bovine On Growth Of Intestinal Mucosa And Expression Of ITF And TGF-β1 MRNA In Mice

Escherichia coli(E.coli)is an integral part of the normal intestinal flora of animals and is generally non-pathogenic,but enteropathogenic escherichia coli(EPEC)and enterotoxigenic escherichia coli(ETEC)is the main pathogen causing primary cow diarrhea and sepsis,and it is also one of the major diseases causing the death of calves in large-scale dairy farms.Among them,the pathogenicity of strains of K99 fimbriae is the highest.E.coli disease is a disease that is common in many and common animals today.It is also caused by pathogenic E.coli.It has a greater impact on intestinal or extraintestinal infections and is a zoonotic disease.At present,there are many researches on pathogenic E.coli in pathogens,diagnosis,and treatment.There are few related studies on pathogenic mechanisms,such as intestinal mucosal injury,pathogenic E.coli infection and injury,There are few studies on the repair and regeneration of intestinal epithelial cells.In order to solve this problem,this study established a mouse model of intestinal injury by infecting with pathogenic E.coli K99.The effect of bovine pathogenic E.coli K99 on growth of intestinal villi and expression of ITF and TGF-β1 m RNA in mice was initially revealed to investigate the pathogenic E.coli K99 infection and intestinal mucosal epithelial cell injury and regeneration in bovine origin.Relationships.Intestine tissue including duodenum,jejunum,ileum in mice which were divided into control group,Brdu group(Brdu)and E.coli-infection group(E.coli +Brdu)was collected at 6 h,12 h,24 h,30 h,36 h,48 h,60 h post treatment.Histopathological changes,the length of intestinal villi and crypts,the location of Brdu positive cells and the population of goblet cells were measured by histopathological observation,immunohistochemical staining,PAS staining and q RT-PCR,respectively.The results showed that:(1)Atrophied villus and cells fragments were observed in E.coli group intestine tissue after treatment for 6 h ~ 36 h,while there was no changes between control and Brdu group.There were no changes in ileal indicators.(2)Measure migration distance of Brdu positive signal in intestinal villus crypts and epithelial cells: control group only had negative control,no positive cells appeared;significantly higher migration length than control and Brdu group during 6 h ~ 36 h after E.coli infection(p<0.01).there was no significant difference in other time(p>0.05).(3)The results of PAS staining showed that the population of goblet cells decreased dramatically after E.coli infection from 6 h~ 60 h,and continued to decrease from 12 h~36 h,and gradually increased from 48 h~60 h.(4)The q RT-PCR results showed the m RNA expression of ITF in E.coli group was significantly lower than control and Brdu group from 6 h ~ 36 h(p<0.01).There was no significant difference at other times(p>0.05).The expression of TGF-β1 m RNA in intestinal tissue was significantly higher in E.coli infected mice than in blank control group and Brdu group(p<0.01)30 h after infection.There was no significant difference in other time(p>0.05).It is demonstrated that intestinal mucosal epithelial cells injury and the growth of intestinal villus epithelial cells and the expression of TGF-β1m RNA.were induced by pathogenic E.coli,which inhibited the expression of ITF m RNA.