Study On The Effect Of Jujube Polysaccharide Extract On Improving The Intestinal Mucosal Barrier Function Of Immunosuppressive Egg-type Chicks

This experiment was conducted to study the effects of jujube polysaccharide extract(JPE)on the average daily gain(ADG),average daily feed intake(ADFI),feed to weight ratio(F/G),tibia length,intestinal mucosal immunity,chemical and mechanical barrier function of immunosuppressed egg-type chicks induced by cyclophosphamide(Cy)were studied to determine the feasibility of JPE in the diet of immunosuppressed egg-type chicks,and to provide a scientific basis for its development and utilization as an immune enhancer.A total of 750 healthy 1-day-old Jinghong No.1 laying hens with similar body weight were selected and randomly divided into BC group,CY Group,JPE low(L),medium(m)and high(H)dose groups after 6 days of adaptation.There were 6 replicates in each group and 25 chickens in each replicate.There was no significant difference in body weight(BW)between groups.The BC group was injected with normal saline at the age of 7～9,and the other groups were injected with 100 mg/kg·BW Cy once a day to induce growth inhibition and intestinal mucosal barrier damage,and 0,400,800 and 1 600 mg/kg JPE were added to the basic diet from the age of 10.The experiment was terminated at the age of 42.The main results are as follows:(1)Growth performance:Compared with the BC group,in the Cy group,except for the BW and tibial length at the old of 7,the difference was not significant(P>0.05),while the BW,tibial length,ADG and ADFI at other stages were significantly reduced(P<0.05);The F/G at the age of 22～42 and 7～42 increased significantly(P<0.01).Which indicated that Cy caused growth inhibition of egg-type chicks.Compared with the Cy group,BW at 42 d,ADG at 22～42 d and 7～42 d in the JPEM group,and tibia lengths at 22 and 42 d in the JPEL,JPEM and JPEH groups were significantly increased(P<0.05).The F/G of JPEM and JPEH groups decreased significantly at 22～42 and 7～42 d(P<0.05).This shows that JPE can significantly alleviate the growth inhibition caused by Cy,and 800 mg/kg has the best effect.(2)Body immunity:Compared with BC group,serum immunoglobulin(Ig)A and G content,thymus and bursa index of Cy group were significantly reduced(P<0.05),indicating that Cy caused immunosuppression.Compared with the Cy group,the immunoglobulin content and thymus index of the JPEL,JPEM and JPEH groups and the bursal index of the JPEL and JPEH groups were significantly increased(P<0.05),indicating that JPE could significantly alleviate immunosuppression.(3)Intestinal mucosal immune barrier function:Compared with the BC group,the secretory immunoglobulin(SIg)A content in the Cy group was significantly reduced(P<0.05),indicating that Cy caused the decline of the intestinal mucosal immune barrier function;compared with the Cy group,the JPEL,JPEM and JPEH groups all increased significantly(P<0.01)and the JPEM group is the highest,indicating that JPE can effectively alleviate the decline of immune barrier function,800mg/kg is better.In order to explore the mechanism of action of JPE on SIgA,this test determined the content of its constituent IgA and polymeric immunoglobulin receptor(PIgR).The results showed that compared with the BC group,the content of IgA and PIgR(P<0.01)in the Cy group were reduced;compared with the Cy group,the IgA and PIgR in the JPEL,JPEM and JPEH groups were significantly increased(P<0.05),which indicates JPE affects the content of SIgA by affecting IgA and PIgR.Next,in order to explore the mechanism of action of JPE on IgA,this test carried out content determination of the factors that influence IgA+B cell differentiation.The results showed that compared with the BC group,the content of interferon-γ(IFN-γ)and interleukin(IL)-(5 and 6)in the Cy group were significantly reduced(P<0.05),indicating that Cy can hinder the differentiation of B cells and the IgA category Transformation and terminal differentiation;Compared with Cy group.Toll-like receptor(TLR)4,microfold(M)cells,transforming growth factor(TGF)-β,IFN-γ and IL(2,4,5,6 and 10)in JPE group increase in varying degrees,which indicates that JPE promotes the secretion of IgA by affecting the differentiation process of IgA+B cells.(4)Mechanical barrier function of intestinal mucosa:Compared with the BC group,the gene expression of Claudin-1 and Occludin in the Cy group were significantly reduced(P<0.05),indicating that Cy caused the intestinal mucosal mechanical barrier damage;Compared with the Cy group,the gene expression levels of Claudin-1 in the JPEL,JPEM and JPEH groups and Occludin in the JPEM and JPEH groups were significantly increased(P<0.05).It is concluded that JPE can effectively repair mechanical barrier damage,and the appropriate dosage is 800～1600mg/kg.In order to explore whether the promoting effect of JPE on the expression of tight junction protein is related to IL-1β and TNF-α,the content of it was determined in this experiment.The results showed that compared with the BC group,the content of IL-1β and TNF-α in the Cy group was not significantly different(P>0.05);Compared with the Cy group,IL-1β and TNF-α in the JPEL and JPEM groups were significantly reduced(P<0.05),which indicates that the promotion effect of JPE on Claudin-1 and Occludin is comparable to the pro-inflammatory factors L-1β and TNF-αeffect of α is related,and it shows that the high expression of IgA is not caused by intestinal inflammation.(5)Intestinal mucosal chemical barrier function:Compared with the BC group,the Mucin-2 gene expression in the Cy group was not significantly different(P>0.05);compared with the Cy group,the JPEM and JPEH groups increased significantly(P<0.05),indicating that JPE can significantly improve the intestine Mucosal chemical barrier function.In conclusion:JPE can repair intestinal mucosal injury by regulating the immune,mechanical and chemical barrier functions of intestinal mucosa under the condition of ensuring growth performance,and 800 mg/kg is the best.