Cerebrospinal Fluid-Derived Microvesicles From Sleeping Sickness Patients Alter Protein Expression in Human Astrocytes

Abstract

Human African trypanosomiasis (HAT) caused by the extracellular protozoon Trypanosoma brucei, is a neglected tropical disease affecting the poorest communities in sub-Saharan Africa. HAT progresses from a hemolymphatic first stage (S1) to a meningo-encephalitic late stage (S2) when parasites reach the central nervous system (CNS), although the existence of an intermediate stage (Int.) has also been proposed. The pathophysiological mechanisms associated with the development of S2 encephalopathy are yet to be fully elucidated. Here we hypothesized that HAT progression toward S2 might be accompanied by an increased release of microvesicles (MVs), sub-micron elements (0.1–1 μm) involved in inflammatory processes and in the determination of the outcome of infections. We studied the morphology of MVs isolated from HAT cerebrospinal fluid (CSF) by transmission electron microscopy (TEM) and used flow cytometry to show that total-MVs and leukocyte derived-CD45+ MVs are significantly increased in concentration in S2 patients' CSF compared to S1 and Int. samples (n = 12 per group). To assess potential biological properties of these MVs, immortalized human astrocytes were exposed, in vitro, to MVs enriched from S1, Int. or S2 CSF. Data-independent acquisition mass spectrometry analyses showed that S2 MVs induced, compared to Int. or S1 MVs, a strong proteome modulation in astrocytes that resembled the one produced by IFN-γ, a key molecule in HAT pathogenesis. Our results indicate that HAT S2 CSF harbors MVs potentially involved in the mechanisms of pathology associated with HAT late stage. Such vesicles might thus represent a new player to consider in future functional studies.

New Biomarker in Chagas Disease: Extracellular Vesicles Isolated from Peripheral Blood in Chronic Chagas Disease Patients Modulate the Human Immune Response

“…In patients with periodontitis, there is a higher concentration of EVs in gingival crevicular fluid, which correlates with the clinical inflammatory periodontal parameters [ 37 ]. A similar phenomenon is observed in patients with human African trypanosomiasis, where late stage patients have a higher concentration of EVs in cerebrospinal fluid when compared to early and intermediate stages, with these EVs also showing different functional properties such as altering astrocyte protein expression in vitro [ 38 ]. In our study, as the EV concentration in patients was lower than that in controls, we hypothesized that this might have led to a loss of function in the human immune response, which in turn contributed to infection persistence and severity, as in a previously described in vitro model of Pseudomonas aeruginosa infection where the infected cells released fewer EVs that, in turn, carried less CCL4 mRNA, contributing to a less effective immune response [ 39 ].…”

Extracellular Vesicles in Trypanosomatids: Host Cell Communication

“…Additionally, microvesicles (MVs) isolated from T. brucei infected hosts induce a progression meningo-encephalitic late stage (S2), inflammatory processes and modulation in astrocytes that resembled the one produced by IFN-γ, a central mechanism in HAT pathogenesis ( Dozio et al, 2019 ).…”

Biogenesis of extracellular vesicles in protozoan parasites: The ESCRT complex in the trafficking fast lane?

“…Most of the current knowledge on trypanosomatid EV biogenesis stems from T. brucei studies. T. brucei-derived EVs have been implicated in multiple biological functions relevant to pathogenesis, including antigen and virulence factor transference (mainly of the variant surface glycoproteins) [103], survival of the extracellular parasites in blood [98], host erythrocyte lysis [103], immune response manipulation [104], and central nervous system inflammation [105]. This wide range of cellular targets points towards different EV subpopulations with different possible biogenetic origins.…”