| Studies show that a variety of protozoa(Amiba, Trypanosoma cruzi, Eimeria tenella, Plasmodium, Toxoplasma gondii etc.) have antitumor effect. These protozoa infection or its lytic proteins can activate antigen presenting cells( APC) and lymphocyte, promotes T cells differentiation into Th1, improve tumor microenvironment, reduce local tumor suppressor cells and cytokines, suppression of cancer metastasis, and promote the apoptosis of cancer cells. Eimeria tenella antigen has produced good results in anticancer and antiviral infection and no toxicity to the body. In order to research the effect of Eimeria protein antitumor, and understanding of the immune regulating effect and mechanism of Eimeria protein, this study selected Eimeria stiedae that strongest pathogenicity of rabbit, soluble protein(ESCA) were extracted, and applying test method, such as flow cytometry(FCM), immunohistochemical, detection tumor cell growth, proliferation and tumor bearing mice immune index of ESCA anti mouse colon cancer(CT26). The main research contents are as follows:(1) Screening effective concentration of ESCA anti mouse colon cancer108 E.stiedai oocysts by grinding, ultrasonication, after centrifugation to obtain ESCA, establishment of subcutaneous tumor model of CT26, the application of intraperitoneal injection different doses of ESCA of tumor bearing mice, the tumor growth, and the survival rate of mice peripheral blood lymphocyte proliferation was observed, screened out best effective concentration of ESCA anti colon cancer(CT26) is 50 μg/day.(2) Study of ESCA anti mouse colon cancer immune mechanismSubcutaneous inoculation of colon cancer cells after ESCA(50 μg/d) 5 daily i.p, detect the change of immunity index after tumor cell injection 25 day. The results showed that ESCA could significantly inhibit the mouse colon cancer growth. Spleen dendritic cell major histocompatibility complex MHC I, MHCII and costimulatory molecules CD80, CD86 expression was significantly increased, and increased the secretion of IL-12 levels, activation of dendritic cells. ESCA enhanced the cytotoxicity of NK cells, the number of NK cells was increased of spleen, killing function associated molecules CD107 expression increased, significantly increased IFN-γ levels secreted by NK cells in spleen and axillary lymph node, that suggested NK cells function has enhance. ESCA increased mice spleen, axillary lymph node and mesenteric lymph nodes nodes IFN-γ levels of CD8+T cells, and the expression of CD107 in spleen and axillary lymph nodes was increased, indicating that ESCA can activate CD8+T cells,induce the CTL effect. The ratio of CD4+/CD8+ mice peripheral blood lymphocytes was increased, suggesting that immune enhancement of mice. The study shows that tumor angiogenesis, CD31 significantly decreased of vascular endothelial cells in tumor tissues in ESCA group. ESCA in sensitized lymphocytes can significantly inhibit the proliferation of CT26 tumor cells. Set up the model of CT26 tumor cell metastasis to the lung, research of ESCA on the tumor metastasis, results showed that the mice lung metastasis nodules number significantly decreased, the survival rate of mice significantly increased.ESCA can enhance the anti-tumor immune response in mice, inhibit the growth and metastasis of tumor, the immune mechanism will provide theoretical basis for the study of the anti tumor effect of protozoa. |
