The Immune Mechanism Of Regulatory T Cell And Its Related Molecules In Echinococcus Multilocularis Infection

Objective:To observe the phenotype changes and expressions of CD4+CD25*regulatory T cells and its related molecules in BALB/c mice infected wi+h Echinococcus multilocularis and relationship between them and infection focus,in order to reaserch the relationship between CD4+CD25+regulatory T cells and its related molecules in Echinococcus multilocularis infection and to reaserch the function of CD4+CD25+regulatory T cells to Echinococcus multilocularis infection.Methods:96 female BALB/c mice were randomly divided into infection group and control group.The infection group was injected protoscoles of Echinococcus multilocularis by intraperitoneally.The control group was received corresponding volume of physiology saline.And then five mice in infection group and five mice in control group were sacrificed on 2 days,8 days,30 days,90 days,180 days and 330 days post inoculate.Flow cytometry was used to analyze the ratio of CD4+CD25+Foxp3+T cells in peripheral blood,lymphnote and spleen CD4+T cells;we measured the serum levels of TGF-? and IL-10 in each group by ELISA.The level of liver pathological alteration was observed by HE staining.The protein expressions and location of CD25,FOXP3,CTLA-4,TGF-?1 and IL-10 were analyzed by immuhistochemistry respectively.The expressions of Foxp3 and CTLA-4 mRNA were analyzed by QRT-PCR.Results:1)Flow cytometry results showed that compared with control,the ratio of CD4+CD25+Foxp3+T cells in peripheral blood CD4+T cells of infected mice had been significantly higher from 30 to 330 days after infection(P<0.05).The ratio of CD4+CD25+Foxp3+T cells in lymphaden CD4+T cells of infected mice was significantly higher from 90 to 330 days after infection(P<0.05).The rate of CD4+CD25+Foxp3+T cells in spleen CD4+T cells of infected mice was significantly higher from 180 to 330 days after infection.2)ELISA results showed that compared with control,the serum of TGF-? was significantly increased on 8 days post infection(P<0.05),and then decreased during the early stages.In the late stages of the infection,the levels of TGF-?and IL-10 in serum both significantly increased(P<0.01).3)HE staining reveals that the erosion of livers was getting worse during the infection.Lymphocyte infiltrated the livers,Echinococctts multislocularis cyst walls was formed.At the same time,the obvious inflammatory reaction zone can be seen between liver cells and Echinococcus multilocularis cyst walls.Moreover,sometime there are visible granuloma nodules.4)CD25,FOXP3,CTLA-4,TGF-?1 and IL-10 only observed in hepatic sinusoid,hyalomitome,fiber organization,focus germinal layer surrounding in infected group.Compared with control,during early stages,the expressions of CD25,FOXP3,CTLA-4,TGF-?1 and IL-10 both remain low or non,but they were both significantly increased in the late stages of infection(P<0.05).5)QRT-PCR demonstrated that in the early stages of the infection,the expressions of Foxp3 and CTLA-4 mRNA were both low,but significantly increased in the middle and late stages of the infection(P<0.05).Conclusion:CD4+CD25+ regulatory T cells may be the one reason of leading Echinococcus multilocularis infection immune suppression.In the early stages of Echinococcus multilocularis infection,the increasing CD4+CD25+regulatory T cells in mice peripheral blood promote Echinococcus multilocularis infection in host.In the middle stages,the peripheral blood and lymphnote CD4+CD25+regulatory T cells both participate in Echinococcus multilocularis infection development.And in the late stages,CD4+CD25+regulatory T cells in mice peripheral blood,lymphnote and spleen all participate in Echinococcus multilocularis persiste infection development.In the infection,CD4+CD25+regulatory T cells by secreting TGF-? and IL-10 play inhibit function.Furthermore,the high expressions of CD4+CD25+regulatory T cells related molecules CD25,Foxp3,CTLA-4,TGF-P and IL-10 are disadvantage of host clearancing livers Echinococcus multilocularis infection and promote Echinococcus multilocularis developing.