Effects Of Escherichia Coli Infection On The Expression Of β-defensin And Cytokine Factors In Piglets

Defensins are a class of low-molecular peptides with antibacterial activity.They have a killing effect on a variety of pathogenic microorganisms and are an important part of the natural immunity of animals.They can also act as immunomodulators to activate and regulate the body’s immune system.E.coli diarrhea has always been an important cause of growth in piglets.The role of endogenous defensin in piglet diarrhea is a worthwhile study.This experiment is mainly to study the effect of enterotoxin-producing Escherichia coli K8 8(ETEC K88)infection on the expression of endogenous β-defensins and inflammatory cytokines in weaned piglets.Ten ternary crossbred piglets(Duroc pigs × Landrace pigs × Large White pigs)weighing about 7.5±0.14 kg were selected and randomly divided into E.coli infection group and blank control group.The pre-feeding period was 10 days.In the infected group,E.coli 15 mL/head was administered orally every morning(the concentration of the bacterial solution was 1×1011 CFU/mL).The water was stopped one night before the infection,and the water supply was started two hours after the infection.The piglets were slaughtered after three days of continuous infection.Collecting samples.Observe the morphology changes of the small intestine of piglets.Detection of endogenous pBD-1(porcine beta defensin-1),pBD-2(porcine beta defensin-2),pBD-3(porcine beta defensin-3),and cytokines in immune-related tissues and intestinal tissues Expression levels of_interleukin-8(IL-8),tumor necrosis factor-a(TNFa),and_interleukin-13(IL-13).The concentration of inflammatory cytokines(IL-8,IL-13,TNF-a)in serum was determined by ELISA.The test results show:Compared with the control group,different degrees of pathological changes appeared in each organ,and the lung interstitial of the piglets was widened after E.coli infection;Hemorrhage in the liver portal area;Renal tubular vesicle degeneration,fibrous exudate within cytoplasmic rupture;Diffuse bleeding of the spleen.After E.coli infection,the ratio of villus length to crypt depth decreased in the duodenum,jejunum,and ileum compared with the control group,and the duodenum and ileum were significantly different(p<0.05).Real-time fluorescence quantitative results show:The expression of pBD-1 in spleen,thymus and jejunum was significantly decreased after E.coli infection(p<0.05),but increased significantly in bone marrow(p<0.05).After infection with E.coli,pBD-2 was significantly decreased in the ileum compared with the control group(p<0.05).The expression level of pBD-3 was significantly decreased in the mesenteric lymph nodes and duodenum compared with the control group(p<0.01).In E.coli infection,IL-8 expression levels were significantly decreased in mesenteric lymph nodes,inguinal lymph nodes,and cervical lymph nodes(p<0.05),while TNF-α expression levels were in mesenteric lymph nodes,inguinal lymph nodes,duodenum,and ileum.It was also significantly decreased(p<0.05).Compared with the control group,E.coli infection significantly reduced the expression of IL-13 in the superficial lymph nodes,duodenum and ileum(p<0.01).The results showed that there was no regularity in the expression of defensin in piglets after E.coli infection.Defensin and cytokine expression trends are different in different tissues,and have certain organizational differences.