Experimental Study Of Intestinal Trefoil Factor On Intestinal Mucosal Immune Function In Burned Mice

Objective To observe the effects of intestinal trefoil factor (ITF) on intestinal mucosal immune function in burned mice and explore its possible mechanism.Methods108BALB/c mice (weighing20-25g) were randomly divided into normal control group (C), burn control group (B) and burn+ITF treatment group (B+I). Group C was only given anesthesia and shaving, not burns. Group B and B+I were soaked in90℃water for7seconds and resulted in30%total body surface area III degree burns. Group B+I was received intragastric administration of ITF (lmg/kg.d, bid)6h after injury (awake from anesthesia); Group B was given the same amount of saline gavage administration twice daily; after injury each group were given a normal diet and water. Observed6mice from each group at the time point of24h,48h and72h after injury, and extracted intra epithelial lymphocyte (IEL) in mouse by density gradient centrifugation.1. Detected the surface antigen CD3+、CD4+、CD8+and CD4+/CD8+rate of IEL by flow cytometry, and observed changes in lymphocyte subsets of mice in each group.2. Mixed the IEL and intestinal epithelial cells (IEC-6) by co-culture for48h and stored the co-culture supernatant in a dry freezer. Detected the changes in the secretion of supernatant IL-2, IL-4, IL-5, IFN-y and TNF content of inflammatory mediators by Flow Cytometry Bead Array technology (Cytometric Beads Array, CBA).Results (1) Compared with group C, the surface antigen CD3+、CD4+、CD4+/CD8+rate of IEL decreased in group B, especially at24and72post-burn hours(PBH)(P<0.01), and the surface antigen CD8+rate of IEL increased, especially at PBH72(P<0.01).Compared with group B, the surface antigen CD3+、CD4+、CD4+/CD8+rate of IEL increased in group B+I, both of them had significant differences at PBH72(P<0.01), while the surface antigen CD8+rate of IEL gradually reduced,72h after injury was remarkably lower(P<0.01).(2) Compared to group C, the secretion of5culture supernatants (IL-2, IL-4, IL-5, IFN-γ and TNF content of inflammatory mediators) all improved in group B:At PBH24, IFN-y and TNF secretion notably increased (P<0.01); at PBH48, not only IFN-y and TNF, but also IL-4and IL-5 remarkably raised (P<0.01), at PBH72, all five cytokines were statistically significantly increased (P<0.01).Compared to group B, the secretion of5culture supernatants all declined at different extent at each time point after the injury from group B+I:IL-2、 IL-4、TNF was remarkably lower (P<0.05), reduction in IFN-γ was statistically significant (P<0.01), while decrease in IL-5was not statistically significant (P>0.05).Conclusion (1) After severe burns, intestinal mucosal immune barrier disruptions, prompting IEL surface antigen conversion changes, CD4+decreased and CD8+rised obviously after injury, a significant decreased in CD4+/CD8+ratio, and the intestinal immune obviously disordered. Giving ITF after injury can reduce the percentage of CD8+, CD4+/CD8+ratio back to normal control level, to stabilize the intestinal immune function;(2)Severe burns lead to intestinal mucosa dysfunction, lead to type Th1cytokine secretion increased. Intestinal promote the inflammatory reaction obviously increased and Th1/Th2type dynamic balance between inflammatory mediators are destroyed. ITF by lowering Th1cytokine secretion can rebuilt the balance between Th1and Th2, and maintain the intestinal mucosal immune homeostasis.