Proteomic analysis of bloodstream trypomastigotes and their extracellular vesicles reveals a complement evasion mechanism through EVs secretion in Trypanosoma cruzi

CAEIRO, L; TEKIEL, V

Caxambu

Congreso; XXXV Reunião Anual da Sociedade Brasileira de Protozoologia; XLVI Reunião Anual da Pesquisa Básica em Doença de Chagas.; 2019

Sociedad Brasileira de Protozoología

The trypomastigote (tryp) is the bloodstream circulating stage of Trypanosoma cruzi, the causative agent of Chagas disease. In vivo, parasites are highly adapted to survive into the mammalian host and to evade the immune system, in contraposition with tryps derived from in vitro cultures. Despite that the set of expressed proteins of in vivo bloodstream tryps should be differently enough to survive in this environment, we have little information about it. In this work, we carried out a proteomic analysis of bloodstream tryps (highly infective RA strain- TcVI) and their extracellular vesicles (EVs), to search for putative virulence factors and immune interaction proteins. Tryps were purified from infected mice and secreted EVs (shedding 6 hs, 37ºC in MEM) were obtained by ultracentrifugation (100000xg; 16 hs). The same procedure was performed on non-infected mice (control). Samples (triplicates of each condition) were processed in a Q Exactive HESI-Orbitrap coupled to a nano HPLC Easy-nLC 1000. MS/MS raw data were searched against both T. cruzi and Mus musculus databases, using PatternLab for Proteomics. Only a minor core of shared proteins between tryps and EVs (18/117) were found, including several HSPs. On the other hand, most of the T. cruzi proteins solely found in EVs were virulence factors and proteins related to immune system evasion (TS group II and V, GP63). Interestingly, mouse proteins, mostly involved in immune surveillance (i.e. complement (23/97) and antibodies (41/97)) were exclusively found associated to EVs. These data suggest that tryps are shedding mouse proteins through EV secretion, probably to avoid their action on the parasite surface during the acute phase of infection. The knowledgement of proteins differentially expressed on bloodstream tryp and their EVs may be helpful to understand the in vivo biology of T. cruzi, and also to identify novel targets for vaccine or drug development. Funding: ANPCyT PICT 2014-1151, PICT 2016-0108. Argentina.