The Preliminary Study On The Innate Immune Response Against Schistosoma Japonicum Infection In Mice And The Regulation Effect Of MiR-146a

Schistosomiasis,caused by blood flukes,is a serious parasitic zoonosis which is one of six key tropical diseases certificated by WHO and one of the most important public health concern in China.Practical experiences concerning prevention and treatment show that pharmacotherapy(Praziquantel,PZQ)is mainly efficient against adult worms but does not kill larvae nor prevent reinfection,thus screening and identifying efficient and safe vaccine candidate molecules against schistosomiasis have been the important technological requirements of schistosomiasis controls.There is a realization that the fundamental research of immunology of schistosomiasis infection should be paid greater attention to make progress in the process of vaccine development.In this study,the preliminary study on the innate immune response against schistosome infection in mice was carried out and considering the function of miR-146a in the innate immunity,we also explored the regulation effect of mi R-146a on the host’s response against Schistosoma japonicum infection,hoping to provide new ideas for schistosomiasis vaccine development.In this present assay,C57BL/6 mice were infected with Schistosoma japonicum cercaria firstly,and spleens and serum of mice were collected in 1d,2d,3d,4d,5d,7d,9d,11d,13d after infection.Dynamic changes in expression of important inflammatory factors in spleen and cytokines in peripheral blood serum were tested at the early stage of infection,and variation tendency of various immunocyte subsets in spleen and the expression of downstream signal molecules in signal pathways correlated with innate immune was analyzed.RT-qPCR revealed that the expression of granzyme GZMA、GZMB、GZMK,chemokine CCL2、CXCL10、CXCL11,interleukin IL-12a、L-4、IL-6、IL-10 and signal pathway molecules MyD88、TLR2、TLR4 et al was up-regulated in varying degrees after infection.Flow cytometry analysis showed that the cell ratio of CD3~+CD4~+T cell and CD3~+CD8~+T cell in the infected group was higher than the control group,at the same time,the percent of NK cell subsets was significantly up-regulated at 5d and 7d after infection.ELISA experiments demonstrated that the expression level of IL-2、IL-4、IL-6、IL-10、IL-12p70 was up-regulated at different time points after infection.This study preliminarily definited some immunizing molecules and cells which play an important role in the innate immune response against Schistosoma japonicum infection in mice,providing experimental evidences for increasing our understanding of the innate immune response mechanism of Schistosoma japonicum infection.Besides,we compared the content of miR-146a in the serum of BABL/c mice and Wistar rats at various time-points before and after infected with schistosomiasis infection,findings show that the content of miR-146a in the serum of two different susceptible hosts exists differences at different time points,specific performance are that the relative content of miR-146a of Wistar rats serum was higher markedly than those of BABL/c mice except for 24d post-infection.Considering that macrophages play a crucial role in the response to schistosoma japonicum infection,this assay further take murine macrophage RAW264.7 as the research object and RAW264.7 cell was stimulatied with soluble schistosomulum antigen(SSA),soluble egg antigen(SEA)to and TLR ligands LPS(TLR4 agonist),Poly(I:C)(TLR3 agonist),Pam3CSK4(TLR2 agonist)to observe the expression of miR-146a,research results showed that the expression of mi R-146a in macrophage RAW264.7 was down-regulated significantly,indicating that miR-146a may paly an immunomodulatory effect in the response against schistosome infection of different susceptible hosts,hence affecting the development and survival of schistosome in different susceptible hosts.The experimental results provide basic data for better understand of the innate immune mechanism of schistosome infection.