Characterization of murine extracellular vesicles and Toxoplasma gondii infection

Deregulation of MicroRNA-146a and 155 expression levels might underlie complicated pregnancy in Toxoplasma Gondii seronegative women

BACKGROUND

To evaluate the ability of the estimated plasma expression levels of genes of microRNA (MiR-) 146a and 155 to differentiate between samples of pregnant women suspected to be infected by T. gondii. 50 newly pregnant women who had at least one of the criteria of high risk for toxoplasma infection and 50 newly primigravida women free of these criteria gave blood samples for qualitative determination of serum toxoplasma antibodies and estimation of plasma expression levels of MiR-146a and 155 using the qRT-PCR. During the pregnancy course, the incidence of pregnancy complications was recorded.

RESULTS

Twenty-six women were IgM-/IgG-, 17 women were IgM+/IgG- and 7 women were IgM+/IgG+. Thirty-two women had pregnancy complications with significantly lower incidence in IgM-/IgG- women. Plasma expression levels of MiR-146a and 155 were significantly higher in total patients compared to control levels and were significantly higher in samples of IgM+/IgG+ patients than in other samples. Statistical analyses defined a high plasma level of MiR-155 as the highly significant predictor for oncoming pregnancy complications and high levels of both microRNAs as predictors for the presence of toxoplasmosis despite seronegativity. Kaplan-Meier regression analysis defined increasing cumulative risk of having toxoplasmosis despite seronegativity with plasma levels of MiR-146a and MiR-155 of 1.2 and 3, respectively.

CONCLUSION

The incidence of pregnancy complications is high, irrespective of the seronegativity of women at high risk of toxoplasmosis. Estimated plasma levels of MiR-155 might identify women liable to develop complications and differentiate seronegative women vulnerable to having T. gondii infection.

TRIAL REGISTRATION

The study protocol was approved preliminarily by the Local Ethical Committee at Benha Faculty of Medicine. Before enrollment, the study protocol was discussed in detail with the study participants, and those accepted to participate in the study signed written fully informed consents. The final approval of the study protocol was obtained after the end of case collection and registered by RC: 5-11-2022.

Protective efficacy of Toxoplasma gondii infected cells-derived exosomes against chronic murine toxoplasmosis

Exosomes were isolated from T. gondii infected human hepatoblastoma cells using the exosome isolation kit and characterized by electron microscopy and Western blotting. Exosomes adsorbed to alum adjuvant were evaluated as a potential immunizing agent against murine chronic toxoplasmosis compared to excretory secretory antigens (ESA)-alum. Mice were immunized at days 1, 15 and 29. The levels of IgG, IFN-γ, IL-4 and IL-10, CD4+ and CD8+ T cells were determined using sandwich enzyme-linked immunosorbent assay (sandwich ELISA) at days 14, 28 and 56 of the experiment. Then mice were infected orally with 10 cysts of T. gondii. The protective efficacy of the antigens were evaluated by counting the brain cysts and measuring the aforementioned humoral and cellular parameters 60 days post infection. The results showed that alum increased the protective efficacy of the exosomes. Immunization with exosome-alum induced both humoral and mixed Th1/Th2 cellular immune responses. Exosome-alum gave higher levels of the humoral and cellular parameters, compared to ESA-alum. After challenge infection, exosome-alum significantly reduced the brain cyst burden by 75 % while ESA-alum gave 42 % reduction and evoked higher humoral and cellular immune responses. Therefore, the possibility of using T. gondii infected cells-derived exosome-alum as a vaccine is a new perspective in toxoplasmosis.

Guidelines for the purification and characterization of extracellular vesicles of parasites

Parasites are responsible for the most neglected tropical diseases, affecting over a billion people worldwide (WHO, 2015) and accounting for billions of cases a year and responsible for several millions of deaths. Research on extracellular vesicles (EVs) has increased in recent years and demonstrated that EVs shed by pathogenic parasites interact with host cells playing an important role in the parasite's survival, such as facilitation of infection, immunomodulation, parasite adaptation to the host environment and the transfer of drug resistance factors. Thus, EVs released by parasites mediate parasite-parasite and parasite-host intercellular communication. In addition, they are being explored as biomarkers of asymptomatic infections and disease prognosis after drug treatment. However, most current protocols used for the isolation, size determination, quantification and characterization of molecular cargo of EVs lack greater rigor, standardization, and adequate quality controls to certify the enrichment or purity of the ensuing bioproducts. We are now initiating major guidelines based on the evolution of collective knowledge in recent years. The main points covered in this position paper are methods for the isolation and molecular characterization of EVs obtained from parasite-infected cell cultures, experimental animals, and patients. The guideline also includes a discussion of suggested protocols and functional assays in host cells.

Quantitative proteomic analysis of local and systemic extracellular vesicles during Eimeria falciformis infectious cycle in the host

BACKGROUND

Extracellular vesicles (EVs) are membranous structures that are formed during pathophysiology, host-parasite interactions and parasite motility. Typically, apicomplexan-infected host cells secrete EVs which traverse local and systemic strata of the host as the parasites develop.

METHODS

Extracellular vesicles were isolated from the caecum and serum of Eimeria falciformis-infected mice during oocyst ingestion (0 h post-infection [0 hpi]), merozont stages 1 and 2 (68 and 116 hpi), oocyst shedding (7 days post-infection [7 dpi]) and host recovery (10 dpi) and subsequently characterized and profiled by tandem mass tag (TMT).

RESULTS

With the progression of E. falciformis life stages, subpopulation of EVs bearing EV biomarkers, including CD9, CD82, heat shock protein 70 (HSP70) and major histocompatibility complex (MHC) molecules, increased. A total of 860 and 1024 differentially expressed proteins were identified in serum EVs (sEVs) and caecum EVs (cEVs), respectively. Identified immune-related molecules (such as cytokines, receptors, immunoglobins, complements, hormones, inflammasomes), ion exchange and cell death-associated proteins were significantly expressed, at least during the E. falciformis first and second merozont stages. Bioinformatics assessment indicated that sEV proteins were at all time points implicated in antigen processing and presentation as well as natural killer cell-mediated cytotoxicity (68 hpi), complement activation/blood coagulation (116 hpi/10 dpi) and catabolic activities (7 dpi). In contrast, cEV proteins were involved in catabolic process, ion transport and antigen presentation (68 and 116 hpi). Host response to E. falciformis infection was similar to intestinal bacterium at 7 dpi and cell adhesion and intercellular protein transport at 10 dpi. In both systems, ferroptosis and necroptosis were common across the parasite's infectious cycle while apoptosis occurred at 68 hpi.

CONCLUSION

The proteomic data indicate that E. falciformis infection co-opts cellular and humoral responses through EV secretions, and that, host cell death and ionic imbalance are associated with E. falciformis infection. This study offers additional insight into host-parasite interactions and host regulatory EV proteins as potential disease indicators or diagnostic molecules.

Host-Derived Extracellular Vesicles in Blood and Tissue Human Protozoan Infections

Blood and tissue protozoan infections are responsible for an enormous burden in tropical and subtropical regions, even though they can also affect people living in high-income countries, mainly as a consequence of migration and travel. These pathologies are responsible for heavy socio-economic issues in endemic countries, where the lack of proper therapeutic interventions and effective vaccine strategies is still hampering their control. Moreover, the pathophysiological mechanisms associated with the establishment, progression and outcome of these infectious diseases are yet to be fully described. Among all the players, extracellular vesicles (EVs) have raised significant interest during the last decades due to their capacity to modulate inter-parasite and host-parasite interactions. In the present manuscript, we will review the state of the art of circulating host-derived EVs in clinical samples or in experimental models of human blood and tissue protozoan diseases (i.e., malaria, leishmaniasis, Chagas disease, human African trypanosomiasis and toxoplasmosis) to gain novel insights into the mechanisms of pathology underlying these conditions and to identify novel potential diagnostic markers.

Dogs with canine visceral leishmaniasis have a boost of extracellular vesicles and miR-21-5p up-expression

This retrospective cohort study analysed extracellular vesicles (EVs) and microRNAs (miRNAs) excreted in canine sera from dogs with canine visceral leishmaniasis (CanVL). A total of 56 canine sera were divided into Group I (28, from healthy dogs) and Group II (28, from the same dogs, but already with CanVL). CanVL was determined by clinical and laboratory diagnoses. Canine sera were ultra-centrifuged to recover EVs (Can-EVs). Analyses by transmission electron microscopy, nanoparticle tracking analysis (NTA), sodium dodecyl sulfate-poli-acrylammide gel eletroforesis (SDS-PAGE) and, Immunoblot confirmed the presence of (i) microvesicles/exosomes and (ii) the tetraspanins CD63 and CD9. EVs secreted by Leishmania (Leishmania) infantum-EVs were reactive against sera from dogs with CanVL (performed by ELISA and Immunoblot). NTA analyses exhibited that concentrations of Can-EVs from dogs with CanVL (7.78 × 1010 Can-EVs/mL) were higher (p < .0001) than the non-infected dogs (mean: 1.47 × 1010 Can-EVs/mL). These results suggested that concentrations of Can-EVs were able to distinguish dogs with CanVL from healthy dogs. The relative expressions of 11 miRNAs species (miR-21-5p, miR-146a-5p, miR-125b-5p, miR-144-3p, miR-194-5p, miR-346, miR-29c-3p, miR-155-5p, miR-24-3p, miR-181a-5p, and miR-9-5p) were estimated in purified miRNAs of 30 canine sera. Dogs with CanVL up-expressed miR-21-5p and miR-146a-5p when compared with healthy dogs. The other miRNA species were poorly or not expressed in canine sera. In conclusion, this study suggests that CanVL induces changes in size and concentration of Can-EVs, as well as, the up-expression of miR-21-5p and miR-146a-5p in infected dogs.

A Systematic Review of Apicomplexa Looking into Epigenetic Pathways and the Opportunity for Novel Therapies

Interest in host epigenetic changes during apicomplexan infections increased in the last decade, mainly due to the emergence of new therapies directed to these alterations. This review aims to carry out a bibliometric analysis of the publications related to host epigenetic changes during apicomplexan infections and to summarize the main studied pathways in this context, pointing out those that represent putative drug targets. We used four databases for the article search. After screening, 116 studies were included. The bibliometric analysis revealed that the USA and China had the highest number of relevant publications. The evaluation of the selected studies revealed that Toxoplasma gondii was considered in most of the studies, non-coding RNA was the most frequently reported epigenetic event, and host defense was the most explored pathway. These findings were reinforced by an analysis of the co-occurrence of keywords. Even though we present putative targets for repurposing epidrugs and ncRNA-based drugs in apicomplexan infections, we understand that more detailed knowledge of the hosts' epigenetic pathways is still needed before establishing a definitive drug target.

Extracellular Vesicles in Trypanosoma cruzi Infection: Immunomodulatory Effects and Future Perspectives as Potential Control Tools against Chagas Disease

Chagas disease, caused by the protozoa parasite Trypanosoma cruzi, is a neglected tropical disease and a major public health problem affecting more than 6 million people worldwide. Many challenges remain in the quest to control Chagas disease: the diagnosis presents several limitations and the two available treatments cause several side effects, presenting limited efficacy during the chronic phase of the disease. In addition, there are no preventive vaccines or biomarkers of therapeutic response or disease outcome. Trypomastigote form and T. cruzi-infected cells release extracellular vesicles (EVs), which are involved in cell-to-cell communication and can modulate the host immune response. Importantly, EVs have been described as promising tools for the development of new therapeutic strategies, such as vaccines, and for the discovery of new biomarkers. Here, we review and discuss the role of EVs secreted during T. cruzi infection and their immunomodulatory properties. Finally, we briefly describe their potential for biomarker discovery and future perspectives as vaccine development tools for Chagas Disease.

Toxoplasmosis in Human and Animals Around the World. Diagnosis and Perspectives in the One Health Approach

Toxoplasmosis is a unique health disease that significantly affects the health of humans, domestic animals, wildlife and is present in ecosystems, including water, soil and food. Toxoplasma gondii is one of the best-adapted parasites in the word. This parasite is able to persist for long periods in its hosts, in different geographic regions of the word. This review summarizes the current literature of these themes, focusing on: (1) toxoplasmosis, a zoonotic infection; (2) One health approach and toxoplasmosis; (3) human toxoplasmosis; (4) animal toxoplasmosis; (5) toxoplasmosis diagnosis, as immunological, parasitological and molecular diagnosis; (6) T. gondii outbreaks caused by infected meat, milk and dairy products, as well as, vegetables and water consume; (7) studies in experimental models; (8) genetic characterization of T. gondii strains; (9) extracellular vesicles and miRNA; and (10) future perspectives on T. gondii and toxoplasmosis. The vast prevalence of toxoplasmosis in both humans and animals and the dispersion and resistence of T. gondii parasites in environment highlight the importance of the one health approach in diagnostic and control of the disease. Here the different aspects of the one health approach are presented and discussed.