The C-terminal region of Trypanosoma cruzi MASPs is antigenic and secreted via exovesicles

Abstract

Trypanosoma cruzi is the etiological agent of Chagas disease, a neglected and emerging tropical disease, endemic to South America and present in non-endemic regions due to human migration. The MASP multigene family is specific to T. cruzi, accounting for 6% of the parasite’s genome and plays a key role in immune evasion. A common feature of MASPs is the presence of two conserved regions: an N-terminal region codifying for signal peptide and a C-terminal (C-term) region, which potentially acts as GPI-addition signal peptide. Our aim was the analysis of the presence of an immune response against the MASP C-term region. We found that this region is highly conserved, released via exovesicles (EVs) and has an associated immune response as revealed by epitope affinity mapping, IFA and inhibition of the complement lysis assays. We also demonstrate the presence of a fast IgM response in Balb/c mice infected with T. cruzi. Our results reveal the presence of non-canonical secreted peptides in EVs, which can subsequently be exposed to the immune system with a potential role in evading immune system targets in the parasite.

Characterization and Diagnostic Application of Trypanosoma cruzi Trypomastigote Excreted-Secreted Antigens Shed in Extracellular Vesicles Released from Infected Mammalian Cells

“…or T. cruzi released EVs contained both host and parasite proteins (38,40,41). Indeed, immunoelectron microscopy studies confirmed that EVs released by T. cruzi do not have a homogeneous composition, since some vesicles were found to contain the membraneanchored MASPs while other vesicle populations contained clathrin (58). Both of the latter proteins were also detected in this study (Tables S2 and S3).…”

“…Proteomic analysis showed that the TESA used in a number of diagnostic assays (9, 22-24) contains a mixture of Vero cell and T. cruzi proteins (see Table S1 in the supplemental material). Purified TESA EVs, which by transmission electron microscopy had a diameter of ϳ80 to 100 nm, were found to contain a preponderance of trans-sialidases, mucins, and MASPs, which may be anchored to the parasite cell surface via glycosyl phosphatidylinositol (GPI) lipid or inserted into the EV membrane via a conserved C-terminal region (58,60,61). This finding was in agreement with those of previous studies showing that trans-sialidases constitute the dominant group of proteins released by trypomastigotes in infected animals or cell cultures (32,45,62).…”

High-resolution profiling of linear B-cell epitopes from mucin-associated surface proteins (MASPs) of Trypanosoma cruzi during human infections

“…Notably, and despite previous reports claiming that sorting signals (i.e. GPI-addition sequence and/or SP) of MASPs elicited strong humoral responses in chronic Chagasic patients [ 24 , 25 ], all of the Chagas-chip identified motifs lied within the mature region of MASP molecules ( Fig 4A ). Within the MASP mature regions, antigenic motifs were broadly distributed ( Fig 4B ).…”

“…In addition, MASP products were also found associated to secreted plasma membrane-derived micro-vesicles (MVs) [ 23 – 25 ]. Intriguingly, and even though trypanosomatids have evolved fine-tuned transport mechanisms for efficient processing and surface display of large amounts of GPI-anchored molecules [ 26 , 27 ], ‘immature’ MASPs bearing non-cleaved sorting signals were recently found inside MVs [ 24 , 25 ]. Within the central and ‘mature’ region, i.e.…”

Immune complexes in chronic Chagas disease patients are formed by exovesicles from Trypanosoma cruzi carrying the conserved MASP N-terminal region

“…The release of EVs by pathogens and their role in disease progression by modulating the host immune response has been demonstrated in several studies4041424344. In T. cruzi , the existence of proteins belonging to surface proteins within these EVs, including the highly conserved C-term region of the MASP family19 has been previously reported45464748. Additionally, EVs could be also produced by the host cell in response to the presence of the parasite.…”