Trypanosoma cruzi-Infected Human Macrophages Shed Proinflammatory Extracellular Vesicles That Enhance Host-Cell Invasion via Toll-Like Receptor 2

Abstract

Extracellular vesicles (EVs) shed by trypomastigote forms of Trypanosoma cruzi have the ability to interact with host tissues, increase invasion, and modulate the host innate response. In this study, EVs shed from T. cruzi or T.cruzi-infected macrophages were investigated as immunomodulatory agents during the initial steps of infection. Initially, by scanning electron microscopy and nanoparticle tracking analysis, we determined that T. cruzi-infected macrophages release higher numbers of EVs (50-300 nm) as compared to non-infected cells. Using Toll-like-receptor 2 (TLR2)-transfected CHO cells, we observed that pre-incubation of these host cells with parasite-derived EVs led to an increase in the percentage of infected cells. In addition, EVs from parasite or T.cruzi-infected macrophages or not were able to elicit translocation of NF-κB by interacting with TLR2, and as a consequence, to alter the EVs the gene expression of proinflammatory cytokines (TNF-α, IL-6, and IL-1β), and STAT-1 and STAT-3 signaling pathways. By proteomic analysis, we observed highly significant changes in the protein composition between non-infected and infected host cell-derived EVs. Thus, we observed the potential of EVs derived from T. cruzi during infection to maintain the inflammatory response in the host.

Perils and Promises of Pathogenic Protozoan Extracellular Vesicles

“…On the basis of biogenesis and size, and with respect to protozoan parasites, EVs are broadly classified into exosomes, ectosomes [microparticles or microvesicles (MVs)], and apoptotic bodies (Dong et al, 2019 ; Cronemberger-Andrade et al, 2020 ). Ectosomes are vesicles formed from protrusions on the plasma membrane (PM), while inward budding of endosomes forms microvesicle bodies (MVBs), which exocytically fuse with the plasma membrane to form exosomes (Lozano et al, 2017 ).…”

“…PPEVs can promote, re-direct, and suppress immune cell responses depending on the maturation of the immune cell, disease model, T. brucei EV concentration (Silverman et al, 2010b ), amount of T. cruzi EVs (Cronemberger-Andrade et al, 2020 ), site of T. cruzi EV inoculation (Lovo-Martins et al, 2018 ), and time. PPEVs cannot cause infection per se but it can aid subsequent parasitization and diverse innate and chronic immune responses (de Souza and Barrias, 2017 ).…”

“…Likewise, L. infantum EVs recruited more macrophages and dendritic cells than did other extracellular products or the parasite (Pérez-Cabezas et al, 2018 ). The derived mucin-like glycoproteins and glycoinositol phospholipids in T. cruzi trypomastigote EV were likely responsible for the induction of inflammatory responses in macrophages (Cronemberger-Andrade et al, 2020 ).…”

“…The release of immune molecules during protozoan parasite infections has a correlation with different immune pathways. T. cruzi EVs stimulated the JAK/STAT signaling pathway through cytokine receptor-linkage wherein there were expressions of STAT1 and STAT3 mRNAs in macrophages (Cronemberger-Andrade et al, 2020 ). Available data suggest that N. caninum EV could activate the mitogen-activated protein kinases (MAPK) signaling pathway in bone marrow-derived macrophages (BMDMs) through a component of secretory proteins in its EVs by phosphorylation of mitogen-activated proteins (P38, ERK, and JNK) via TLR 2.…”

“…Also, EVs of T. cruzi Y strain and Colombian strain activated MAPKs via TLR2 in peritoneal macrophages (Nogueira et al, 2015 ). Prior exposure of T. cruzi Y strain trypomastigote EVs to human macrophages transfected with TLR2 expressed CD25 and activated NF-κB via TLR2 (Cronemberger-Andrade et al, 2020 ). Meanwhile, TLR2 might be activated by N. caninum EVs in BMDMs because it contains some pathogen-associated molecular patterns (PAMPs) (Li et al, 2018c ).…”