Changes Of Intestinal Antigen Presentation And Mucosal Immunization In The Heat-stress Rats

The purpose of the study was to investigate the changes of immune-related gene expressions, the immune response and the antigen presentation of DCs in rat small intestine and in the mesenteric lymph nodes(MLNs) in response to heat stress.12Sprague Dawley (SD) rats were randomly divided into control and heat-stress groups. Both groups were housed in a25℃environment of60%relative humidity. The heat-stress group was subjected to40℃for2h daily over3days. Rats were sacrificed after heat treatment, sections of small intestine epithelial tissue were excised for morphological examination, microarray analyses, flow cytometry, Real-time PCR and ELISA. Lymphocytes isolated from the MLNs were cultured in vitro for3days. MLNs were excised for morphological examination and flow cytometry.Compared with the control group, rat rectal temperatures and serum cortisol levels were all significantly increased after heat stress, villi of the small intestine was damaged severely, consistanted with our previous studies. The white cells and mononuclear cells in the blood were decreased. The structure of the MLNs was disrupted in the heat stress group.Microarray analysis showed that23genes related to immune response were altered significantly (Fold Change>2, p<0.01) in response to heat stress,12genes were upregulated and11genes were downregulated. Subsequent bioinformatics analyses (including hierarchical clustering, Gene Ontology and KEGG pathway analysis) revealed that some genes were involved in the antigen processing and presentation pathway.After heat stress, the expression of slgA in the ileum was decreased significantly, which indicated heat stress suppressed the intestinal immune response. The expressions of the MHC-II and CD86on the dendritic cells (DCs) in the ileum showed no signifcant changes. IL-12mRNA expression in the ileum decreased significantly, the transcription of IFN-y, IL-4, and IL-10decreased significantly, while the Foxp3+Treg expression increased significantly, which meant that heat stress suppressed the immune response of the ileum.After heat stress, the morphology of the lymphocytes isolated from the MLNs changed after cultured in vitro for3days. The expressions of MHC II and CD86on the DCs in the MLNs were decreased significantly, the number of CD3+T cell and CD3+CD4+CD8" Th cells in the MLNs were decreased significantly, indicated that heat stress suppressed DCs’antigen presentation and the cell-mediated immune response of T cells in the MLNs.