Exosomes Derived From Toxoplasma Gondii Stimulate An Inflammatory Response Through JNK Signaling Pathway

Background:Exosomes are nanoscale membranous vesicles secreted by most cell types able to transfer bioactive molecules among cells,which play crucial roles in intercellular communication.They are also enabled to transfer its components from pathogens to hosts as well as parasites.Hitherto,exosomes derived from parasites,such as Schistosoma japonicum,Trypanosoma brucei,Trypanosoma cruzi and Neospora caninum have been verified in several researchers.Toxoplasma gondii(T.gondii)is an obligate intracellular protozoan and causes toxoplasmosis contributing to a worldwide epidemic.However,knowledge of exosomes derived from T.gondii or T.gondii-infected host cells is still very limited.Objectives:Our aim is to investigate the isolation and characterization of exosomes derived from T.gondii ME49 strain.Moreover,we analyze the miRNAs of T.gondii exosomes and predict the target gene and signal pathway in host cells associated with the miRNAs.Especially,we focus on the role of MAPK signaling pathway by which T.gondii exosomes modulate immune response in host cells.Methods:We characterized the exosomes derived from T.gondii and detected the immune response in macrophages.We used transmission electron microscopy(TEM),Nanotracking analysis(NTA)and Western blotting to identify T.gondii exosomes.And we also analyzed the small RNA distribution in T.gondii exosomes.Functional experiments were performed in RAW264.7 cells for the induction of cytokines,MAPKs(p38,ERK 1-2 and JNK),mRNAs and nuclear translocation of phosphorylated JNK protein.Results:We successfully characterized the T.gondii exosomes.According to small RNA analysis,we detected the small RNA distribution from T.gondii exosomes.Furthermore,JNK pathway was activated by T.gondii exosomes,and the production of IL-12,IFN-y and TNF-a was significantly increased in macrophages.Conclusion:Our findings demonstrated that T.gondii exosomes elicit innate immune through JNK activation,which could provide new insight into the essential regulators of host-pathogen interactions.