Roles Of IIEL And IIEL-associated Cytokines In The Progress Of Swine Toxoplasmosis

In order to research roles of intestinal intraepithelial lymphocytes (iIEL) and iIEL-associated cytokines IL-10, IFN-γ, IL-12 in the progress of swine toxoplasmosis. we chose diseased pigs about 60～70 day-age that were diagnosed with toxoplasmosis by the clinical observation, serological detection of Toxoplasma gondii, pathological autopsy and histopathological observation. Took the duodenum, jejunum, ileum, cecum, colon, rectum from the 5 about 60～70 day-age healthy pigs (control group) of clinical manifestations and serologic assays of T. gondii showed negative and the 5 T. gondii infected pigs (infected group), then the number of iIEL were measured by the hematoxylin and eosin (HE), used immunohistochemistry to detecte the expression of IL-10, IFN-γand IL-12 in intestine. According to the expression pattern of iIEL, IL-10, IFN-γ and IL-12, we can investigate the roles of them in the progress of swine toxoplasmosis. The results were as follows:1. Clinical symptoms of the sick pigs:temperature increased, dyspnea, hemorrhagic spots on the skin. Serologic assays showed positive by T. gondii antigen rapid kit. The majority of the organs were swollen, hemorrhagic, and the individual organs’surfaces were necrotic. There were T. gondii tachyzoite, cysts, false cysts and eosinophil infiltration in pathological tissues. Therefore, swine toxoplasmosis was diagnosed.2. The results of HE showed that the numbers of the iIEL increased significantly after the pigs T. gondii infection. Compared with the control group, the numbers of IEL in the jejunum, ileum and cecum of the infected group were significantly different (P<0.01), the numbers of the IEL in the duodenum and rectum of infected group were also higher than the control group, but not significantly different (P>0.05).3. The results of immnohistochemistry showed that the most of the IL-10 protein expressed in the intestinal villus epithelial cells, inflammatory cells in lamina propria, epithelial cells of enteraden, and inflammatory cells in submucosa when the pigs T. gondii infection. Compared with the control group, the staining intensity of the positive cells was weaker, and the expression of IL-10 reduced in the intestine of infected group, the expression of IL-10 in the duodenum of the infected group was most different significantly (P<0.01), and the expression of IL-10 in the ileum and colon of infected group was different significantly (P<0.05).4. The results of immnohistochemistry showed that the most of the IFN-γ and IL-12 protein expressed in the intestinal villus epithelial cells, inflammatory cells in lamina propria, epithelial cells of the enteraden, blood vessels and lymphatic vessels in submucosa after the pigs T. gondii infection. Compared with the control group, staining intensity was weaker and the expression of IFN-y and IL-12 were reduced in the intestine of the infected group. Compared with the control group, the expression of IFN-y in the duodenum, jejunum and cecum and IL-12 in the duodenum, ileum and cecum of infected group the difference was extremely significant (P<0.01), the expression of IFN-y in the ileum, colon and rectum and IL-12 in the rectum of infected group was also significantly lower (P<0.05).All of these results indicated that the number of ilEL were increased after the pigs T. gondii infection, but the expression of Th2 type cytokine IL-10 and Thl type cytokines IFN-y, IL-12 both were decreased, speculated that T. gondii regulate ilEL and iIEL-associated cytokines, and led to intestinal mucosa immunosuppression, ilEL maintain the homeostasis of intestinal tract after invasion of host by T. gondii, which showed that iIEL played no active role in host against T. gondii infection.