Abstract
Chagas disease, a neglected tropical disease (NTD) caused by the flagellated protozoan Trypanosoma cruzi (T. cruzi), is a major public health problem. It was initially restricted to Latin America, but it is now expanding globally. Host and pathogen interactions are crucial in the establishment of disease, and since 1970, it has been known that eukaryotic cells release extracellular vesicles (EVs), which in turn have an important role in intercellular communication in physiological and pathological conditions. Our study proposed to characterize and compare circulating EVs isolated from the plasma of chronic Chagas disease (CCD) patients and controls. For this, peripheral blood was collected from patients and controls, and mononuclear cells (PBMCs) were isolated and stimulated with parasite EVs, showing that patient cells released fewer EVs than control cells. Then, after plasma separation followed by EV total shedding enrichment, the samples were subjected to ultracentrifugation to isolate the circulating EVs, which then had their size and concentration characterized by nanoparticle tracking analysis (NTA). This showed that patients had a lower concentration of circulating EVs while there were no differences in size, corroborating the in vitro data. Additionally, circulating EVs were incubated with THP-1 cells (macrophages) that, after the interaction, had their supernatant analyzed by ELISA for cytokine detection. In relation to their ability to induce cytokine production, the CCD patient EVs were able to induce a differential production of IFN-γ and IL-17 in relation to controls, with differences being more evident in earlier/less severe stages of the disease. In summary, a decreased concentration of circulating EVs associated with differential activation of the immunological system in patients with CCD is related to parasite persistence and the establishment of chronic disease. It is also a potential biomarker for monitoring disease progression.
Highlights
Trypanosoma cruzi is a protozoan parasite and the causative agent of Chagas disease (CD), called American trypanosomiasis
In a previous work by our group, we showed that T. cruzi trypomastigotes derived from infected mammalian cells released vesicles into the medium and that extracellular vesicles (EVs) of different sizes were associated with both the parasite membrane and the culture medium ([17]; [18])
Since EVs were demonstrated to be important for the development of heart parasitism and inflammation in animal models of infection, we proposed to characterize the peripheral blood circulating population of EVs in chronic Chagas disease (CCD) patients as well as their immunomodulatory capacity in vitro
Summary
Trypanosoma cruzi is a protozoan parasite and the causative agent of Chagas disease (CD), called American trypanosomiasis. In a previous work by our group, we showed that T. cruzi trypomastigotes derived from infected mammalian cells released vesicles into the medium and that EVs of different sizes were associated with both the parasite membrane and the culture medium ([17]; [18]). These EVs carry glycoproteins are responsible for cell activation via TLR2, and it modulates the host innate immune response and increases the number of cell infections and intracellular parasites [19, 20]. Since EVs were demonstrated to be important for the development of heart parasitism and inflammation in animal models of infection, we proposed to characterize the peripheral blood circulating population of EVs in CCD patients as well as their immunomodulatory capacity in vitro
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