The Molecular Mechanism Of The Regulation Of Th2 Immune Response Induced By Trichinella Spiralis Through Activating Macrophages And Its Impact On Toxoplasma Gondii Co-infection

The zoonotic Trichinella spiralis and Toxoplasma gondii which are important foodborne parasites,share the same infection route and host rages,induce different immune responses while infect the same host.Trichinella spiralis infection induces Th2 biased responses but Toxoplasma gondii infection induces Th1 biased responses.Macrophages play a crucial role in regulating Th1and Th2 immune responses.The aim of this study is to investigate on the regulation of Th2 immune response induced by Trichinella spiralis and its role on Toxoplasma gondii succeeded infection.In this study three different co-infection models were successfully built,including Trichinella spiralis primary infection-Toxoplasma gondii secondary infection models,Trichinella spiralis and Toxoplasma gondii concurrent infection models and Toxoplasma gondii primary infection-Trichinella spiralis secondary infection models.The Th1 cytokines and Th2 cytokines in infected mice peripheral blood were detected with ELISA,the T lymphocyte in infected mice peripheral blood were detected with flow cytometry,the Trichinella spiralis burden were counted by microscope and the Toxoplasma gondii burden were detected with q RT-PCR.The results indicated that,Trichinella spiralis infection induced Th2 immune responses characterized with increased levels of Th2 cytokines production along with the decreased levels of Th1 cytokines,Toxoplasma gondii infection induced Th1 immune responses characterized with decreased levels of Th2cytokines production along with the increased levels of Th1 cytokines,Trichinella spiralis and Toxoplasma gondii co-infection induced the Th1/Th2 mixed immune responses,and Trichinella spiralis infection increased the Toxoplasma gondii burden but Toxoplasma gondii infection failed to regulate Trichinella spiralis burden in co-infection mice.Trichinella spiralis infection can induce macrophages into the alternatively activated phenotype,which is primarily associated with the development of a polarized Th2 immune response.In the present study,we examined the immunomodulatory effect of Trichinella spiralis thioredoxin peroxidase-2（Ts TPX2）,a protein derived from Trichinella spiralis ES products,in the regulation of Th2 response through direct activation of macrophages.The location of Ts TPX2 was detected by immunohistochemistry and immunofluorescence analyses.The immune response in vivo induced by r Ts TPX2 was characterized by analyzing the Th2 cytokines and Th1 cytokines in the peripheral blood.The r Ts TPX2-activated macrophages(Mr _{Ts TPX2})were tested for polarization,their ability to evoke na?ve CD4⁺T cells,and resistance to the larval infection after adoptive transfer in BALB/c mice.The immunolocalization analysis showed Ts TPX2 in cuticles and stichosome of Trichinella spiralis ML.The immunostaining was detected in cuticles and stichosome of Trichinella spiralis Ad3 and ML,as well as in tissue-dwellings around ML after the intestines and muscle tissues of infected mice were incubated with anti-r Ts TPX2.Immunization of BALB/c mice with r Ts TPX2could induce a Th1-suppressing mixed immune response in view of the increased levels of Th2cytokines（IL-4 and IL-10）production along with the decreased levels of Th1 cytokines（IFN-γ,IL-12,and TNF-α）.In vitro studies showed the r Ts TPX2 could directly drive RAW 264.7 and peritoneal macrophages to the M2 phenotype.Moreover,M_{r Ts TPX2}could promote CD4⁺T cells to polarize into Th2 type in vitro.Adoptive transfer of M_{r Ts TPX2} into mice suppressed the Th1 responses by enhancing the Th2 responses and exhibited a 44.7%reduction in adult worms and 52.9%reduction in muscle larvae upon being challenged with Trichinella spiralis infective larval,suggesting that the Ts TPX2 is a potential vaccine candidate against trichinosis.Our study indicated that Ts TPX2 would be at least one of the molecules to switch macrophages into the M2 phenotype during Trichinella spiralis infection,which provided new therapeutic approaches to various inflammatory disorders such as allergies or autoimmune diseases.In the last part,we investigate the role of Trichinella spiralis activated macrophages in regulating Toxoplasma gondii infection.The macrophage molecular markers in Trichinella spiralis activated RAW264.7 and peritoneal macrophages were detected with q RT-PCR and Western Blotting methods,the Toxoplasma gondii replication were measured by Western Blotting.The results indicated that,Trichinella spiralis induced macrophages to an AAMs phenotype in vivo and in vitro,characterized with increased expression of Arg-1 and MRC-1 accompany by decreased expression of i NOS-1,The AAMs could accelerate the infection of Toxoplasma gondii in vitro.In conclusion,in this study,we clarified the molecular mechanism of the polarization of Th2immune response induced by Trichinella spiralis,identified the regulation of Trichinella spiralis induced Th2 immune responses in Toxoplasma gondii infection,clarified the cellular mechanism of Trichinella spiralis influences Toxoplasma gondii infection through directly inducing alternatively activated macrophages.