Proteomic Analysis of Plasma-Derived Extracellular Vesicles From Mice With Echinococcus granulosus at Different Infection Stages and Their Immunomodulatory Functions.

Chunli Shi,Xiaojing Zhou,Mei Yin,Jiaqing Zhao,Hui Yang,Shuqin Ding,Wenjuan Yang,Min Bai,Wei Zhao,Xiaoping Gao,Atsushi Nagai,Jianwen Wu,Ying Zhang

doi:10.3389/fcimb.2022.805010

Abstract

The globally distributed cystic echinococcosis (CE) is caused by the larval stage of Echinococcus granulosus (E. granulosus), a cosmopolitan and zoonotic disease with potentially life-threatening complications in humans. The emerging roles for extracellular vesicles (EVs) in parasitic infection include transferring proteins and modifying host cell gene expression to modulate host immune responses. Few studies focused on the host-derived EVs and its protein profiles. We focused on the EVs from mouse infected with E. granulosus at different stages. ExoQuick kit was used for isolating EVs from mouse plasma and ExoEasy Maxi kit was used for isolating protoscolex culture supernatant (PCS) and hydatid cyst fluid (HCF). Firstly, EVs were characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and immunoblot. Secondly, the proteins of plasma EVs were identified using liquid chromatography-tandem mass spectrometry (LC–MS/MS). The resulting LC–MS/MS data were processed using Maxquant search engine (v 1.5.2.8). Tandem mass spectra were researched against the mice and E. granulosus proteins database in the NCBI. The differentially expressed proteins are performed by proteomic label-free quantitative analysis and bioinformatics. Thirdly, in vitro experiment, the results of co-culture of plasma EVs and spleen mononuclear cells showed that 7W-EVs can increase the relative abundance of regulatory T (Treg) cells and IL-10. We further verified that EVs can be internalized by CD4+ and CD8+ T cells, B cells, and myeloid-derived suppressor cells (MDSC). These results implied host-derived EVs are multidirectional immune modulators. The findings can contribute to a better understanding of the role of host-derived EVs which are the optimal vehicle to transfer important cargo into host immune system. In addition, we have found several important proteins associated with E. granulosus and identified in infected mouse plasma at different stages. Furthermore, our study further highlighted the proteomics and immunological function of EVs from mouse infected with E. granulosus protoscoleces at different infection stages. We have laid a solid foundation for the role of EVs in cystic echinococcosis in the future research and supplemented a unique dataset for this E. granulosus.

Highlights

Cystic echinococcosis (CE) is a chronic zoonotic helminthic disease with a worldwide distribution
To verify the successful establishment of the E. granulosus infection mouse model, we examined the development of protoscoleces from hydatid cysts in the abdominal cavity of mice
The typical structure of hydatid cysts had developed in mice at 20 weeks post-infection

Summary

Introduction

Cystic echinococcosis (CE) is a chronic zoonotic helminthic disease with a worldwide distribution. It is a highly endemic and serious disease causing a severe public health issue in western China (Wen et al, 2019). It is well known that the development of hydatid cysts has a significant in parasite persistence during chronic CE. It is known from the literatures that protoscoleces develop into hydatid cysts within 20 weeks (Diaz, 2017). Based on the life cycle of E. granulosus, the cysts are not yet formed in 7-weeks post-infection mouse (Rogan and Craig, 1997). The hydatid cysts build a barrier that protect from the host immune response and contributes to the immune escape of the parasite (Santos et al, 2016). Few studies have paid attention to the changes of immune response in host before and after the formation of cysts

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