Characterization of exosomes derived from <em>Toxoplasma gondii</em> and their functions in modulating immune responses

Abstract

Introduction Exosomes are nanograde membrane-bound vesicles secreted from most cell types through the fusion of multivesicular bodies with plasma membranes. Some of these exosomes are well defined, and are known to have immunomodulatory properties as well as play critical roles in intercellular communications. In this study, we characterized the exosomes derived from Toxoplasma gondii and their functions in aspect of immune responses. Methods T. gondii exosomes were isolated and identified using electron microscopy, nanoparticle tracking analysis, and Western blotting. The viability of macrophage RAW264.7 cells affected by exosomes was evaluated using a Cell Counting Kit (CCK-8). Then the uptake of T. gondii exosomes by RAW264.7 cells was detected by labeling with fluorescent dye PKH67. After exosomes stimulation, in vitro the production of interleukin (IL)-12, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10 in RAW264.7 cells were investigated using enzyme-linked immunosorbent assay (ELISA). In immunized BALB/c mice, the antibodies, cytokines as well as the percentage of CD4+ and CD8+ T cells were determined using ELISA and flow cytometric analysis. Protective efficacy was evaluated by challenging intraperitoneally with tachyzoites of T. gondii . Results We successfully isolated and characterized the exosomes derived from T. gondii . Functionally, the viability of macrophage RAW264.7 cells was significantly affected by exosomes at a high concentration (160 μg/mL). The production of IL-12, TNF-α and IFN-γ in macrophage cells were increased, and the level of IL-10 was decreased. Furthermore, BALB/c mice immunized with T. gondii exosomes showed both humoral and cellular immune responses and also exhibited a prolonged survival time. Conclusion T. gondii exosomes could modulate macrophage activation in vitro and trigger humoral and cellular immune responses and partial protection against acute parasite infection in mice, which suggested that exosomes may serve as a potential candidate against toxoplasmosis.

Extracellular vesicles isolated from Toxoplasma gondii induce host immune response

“…These findings are correlated with other studies that described the participation of EVs in immune response purified from other pathogens (viruses, bacteria, fungi, and parasites) in modulation of the host immune system . In these pathogens, EVs present a complex of molecules considered pathogenic for the infected host .…”

“…Toxoplasma gondii infection alters cell proliferation mechanisms of infected cells, and exosomes secreted by T. gondii ‐infected cells can mediate such changes to neighbouring cells . Recently, Li et al characterized T. gondii exosomes and showed that they can modulate the host immune response. At the same time, Wowk et al demonstrated the first proteomic profile of T. gondii exosomes, containing a wide range of proteins, including the secretory proteins used by tachyzoites for invasion and posterior replication within host cells.…”

Human extracellular vesicles and correlation with two clinical forms of toxoplasmosis

“…Regarding on T. gondii, proteomic profile of exosomes containing a wide range of proteins [29]. T. gondii derived-EVs (exosomes and microvesicles) contain miRNA and they were immunologically recognized by host immune response inducing humoral and cellular responses as IL-10, TNF-α, and iNOS [30,31]. Exosomes excreted by infected host cells constituted an effective non-cellular vaccine with antigen and adjuvant properties for the immune response as well as, immunization [32,33].…”

Emerging roles of tetraspanins in plant inter-cellular and inter-kingdom communication

“…Exosomes have emerged as a ubiquitous mechanism for transferring information between cells and organisms across all three kingdoms of life. 67,68 Initially described in animal cells as a general signaling pathway that allows communication between tumor and distal tissue during metastases, exosomes have also been shown to function in immune surveillance in plant cells during host-pathogen interactions, [69][70][71][72] and we propose that exosomes could also contribute to the regulation of mutualistic interactions.…”