Immunomodulatory Properties of Leishmania Extracellular Vesicles During Host-Parasite Interaction: Differential Activation of TLRs and NF-κB Translocation by Dermotropic and Viscerotropic Species

Extracellular Vesicles From Mycoplasma gallisepticum: Modulators of Macrophage Activation and Virulence

Extracellular vesicles (EVs) mediate intercellular communication by transporting proteins. To investigate the pathogenesis of Mycoplasma gallisepticum, a major threat to the poultry industry, we isolated and characterized M. gallisepticum-produced EVs. Our study highlights the significant impact of M. gallisepticum-derived EVs on immune function and macrophage apoptosis, setting them apart from other M. gallisepticum metabolites. These EVs dose-dependently enhance M. gallisepticum adhesion and proliferation, simultaneously modulating Toll-like receptor 2 and interferon γ pathways and thereby inhibiting macrophage activation. A comprehensive protein analysis revealed 117 proteins in M. gallisepticum-derived EVs, including established virulence factors, such as GapA, CrmA, VlhA, and CrmB. Crucially, these EV-associated proteins significantly contribute to M. gallisepticum infection. Our findings advance our comprehension of M. gallisepticum pathogenesis, offering insights for preventive strategies and emphasizing the pivotal role of M. gallisepticum-derived EVs and their associated proteins. This research sheds light on the composition and crucial role of M. gallisepticum-derived EVs in M. gallisepticum pathogenesis, aiding our fight against M. gallisepticum infections.

Extracellular vesicles in parasitic diseases - from pathogenesis to future diagnostic tools

Parasitic diseases are still a major public health problem especially among individuals of low socioeconomic status in underdeveloped countries. In recent years it has been demonstrated that parasites can release extracellular vesicles that participate in the host-parasite communication, immune evasion, and in governing processes associated with host infection. Extracellular vesicles are membrane-bound structures released into the extracellular space that can carry several types of biomolecules, including proteins, lipids, nucleic acids, and metabolites, which directly impact the target cells. Extracellular vesicles have attracted wide attention due to their relevance in host-parasite communication and for their potential value in applications such as in the diagnostic biomarker discovery. This review of the literature aimed to join the current knowledge on the role of extracellular vesicles in host-parasite interaction and summarize its molecular content, providing information for the acquisition of new tools that can be used in the diagnosis of parasitic diseases. These findings shed light to the potential of extracellular vesicle cargo derived from protozoan parasites as novel diagnostic tools.

Exploiting Leishmania-Primed Dendritic Cells as Potential Immunomodulators of Canine Immune Response

Dendritic cells (DCs) capture pathogens and process antigens, playing a crucial role in activating naïve T cells, bridging the gap between innate and acquired immunity. However, little is known about DC activation when facing Leishmania parasites. Thus, this study investigates in vitro activity of canine peripheral blood-derived DCs (moDCs) exposed to L. infantum and L. amazonensis parasites and their extracellular vesicles (EVs). L. infantum increased toll-like receptor 4 gene expression in synergy with nuclear factor κB activation and the generation of pro-inflammatory cytokines. This parasite also induced the expression of class II molecules of major histocompatibility complex (MHC) and upregulated co-stimulatory molecule CD86, which, together with the release of chemokine CXCL16, can attract and help in T lymphocyte activation. In contrast, L. amazonensis induced moDCs to generate a mix of pro- and anti-inflammatory cytokines, indicating that this parasite can establish a different immune relationship with DCs. EVs promoted moDCs to express class I MHC associated with the upregulation of co-stimulatory molecules and the release of CXCL16, suggesting that EVs can modulate moDCs to attract cytotoxic CD8+ T cells. Thus, these parasites and their EVs can shape DC activation. A detailed understanding of DC activation may open new avenues for the development of advanced leishmaniasis control strategies.

Subcellular particles for characterization of host-parasite interactions

Parasitic diseases remain a major global health problem for humans. Parasites employ a variety of strategies to invade and survive within their hosts and to manipulate host defense mechanisms, always in the pathogen's favor. Extracellular vesicles (EVs), membrane-bound nanospheres carrying a variety of bioactive compounds, were shown to be released by the parasites during all stages of the infection, enabling growth and expansion within the host and adaptation to frequently changing environmental stressors. In this review, we discuss how the use of existing nanotechnologies and high-resolution imaging tools assisted in revealing the role of EVs during parasitic infections, enabling the quantitation, visualization, and detailed characterization of EVs. We discuss here the cases of malaria, Chagas disease and leishmaniasis as examples of parasitic neglected tropical diseases (NTDs). Unraveling the EVs' role in the NTD pathogenesis may enormously contribute to their early and reliable diagnostic, effective treatment, and prevention.

Extracellular Vesicles from Leishmania (Leishmania) infantum Contribute in Stimulating Immune Response and Immunosuppression in Hosts with Visceral Leishmaniasis

Visceral leishmaniasis (VL) is a chronic systemic disease. In Brazil this infection is caused by Leishmania (Leishmania) infantum. Extracellular vesicles (EVs) released by Leishmania species have different functions like the modulation of host immune systems and inflammatory responses, among others. This study evaluated the participation of EVs from L. (L.) infantum (Leish-EVs) in recognition of the humoral and cellular immune response of hosts with VL. Promastigotes were cultivated in 199 medium and, in the log phase of growth, they were centrifuged, washed, resus-pended in RPMI medium, and incubated for 2 to 24 h, at 25 °C or 37 °C to release Leish-EVs. This dynamic was evaluated using transmission (TEM) and scanning (SEM) electron microscopies, as well as nanoparticle tracking analysis (NTA). The results suggested that parasite penetration in mammal macrophages requires more Leish-EVs than those living in insect vectors, since promastigotes incubated at 37 °C released more Leish-EVs than those incubated at 25 °C. Infected THP-1 cells produced high EV concentration (THP-1 cells-EVs) when compared with those from the control group. The same results were obtained when THP-1 cells were treated with Leish-EVs or a crude Leishmania antigen. These data indicated that host-EV concentrations could be used to distinguish infected from uninfected hosts. THP-1 cells treated with Leish-EVs expressed more IL-12 than control THP-1 cells, but were unable to express IFN-γ. These same cells highly expressed IL-10, which inhibited TNF-α and IL-6. Equally, THP-1 cells treated with Leish-EVs up-expressed miR-21-5p and miR-146a-5p. In conclusion, THP-1 cells treated with Leish-EVs highly expressed miR-21-5p and miR-146a-5p and caused the dysregulation of IL-10. Indirectly, these results suggest that high expression of these miRNAs species is caused by Leish-EVs. Consequently, this molecular via can contribute to immunosuppression causing enhanced immunopathology in infected hosts.

Extracellular Vesicles Released by Leishmania (Leishmania) amazonensis Promastigotes with Distinct Virulence Profile Differently Modulate the Macrophage Functions

Leishmania spp. is the aetiologic agent of leishmaniasis, a disease endemic in several developing countries. The parasite expresses and secretes several virulence factors that subvert the macrophage function and immune response. Extracellular vesicles (EVs) can carry molecules of the parasites that show immunomodulatory effects on macrophage activation and disease progression. In the present work, we detected a significantly higher expression of lpg3 and gp63 genes in Leishmania amazonensis promastigotes recovered after successive experimental infections (IVD-P) compared to those cultured for a long period (LT-P). In addition, we observed a significantly higher percentage of infection and internalized parasites in groups of macrophages infected with IVD-P. Macrophages previously treated with EVs from LT-P showed higher percentages of infection and production of inflammatory cytokines after the parasite challenge compared to the untreated ones. However, macrophages infected with parasites and treated with EVs did not reduce the parasite load. In addition, no synergistic effects were observed in the infected macrophages treated with EVs and reference drugs. In conclusion, parasites cultured for a long period in vitro and recovered from animals' infections, differently affected the macrophage response. Furthermore, EVs produced by these parasites affected the macrophage response in the early infection of these cells.

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.

Extracellular Vesicles and Their Impact on the Biology of Protozoan Parasites

Extracellular vesicles (EVs) are lipid-membrane-bound structures produced naturally by all cells and have a variety of functions. EVs act as vehicles for transporting important molecular signals from one cell to another. Several parasites have been shown to secrete EVs, and their biological functions have been extensively studied. EVs have been shown to facilitate communication with the host cells (such as modulation of the host's immune system or promoting attachment and invasion into the host cells) or for communication between parasitic cells (e.g., transferring drug-resistance genes or factors modulating stage conversion). It is clear that EVs play an important role in host-parasite interactions. In this review, we summarized the latest research on the EVs secreted by protozoan parasites and their role in host-parasite and parasite-parasite communications.

The Exosome-like Vesicles of Giardia Assemblages A, B, and E Are Involved in the Delivering of Distinct Small RNA from Parasite to Parasite

The genetically related assemblages of the intestinal protozoa parasite Giardia lamblia are morphologically indistinguishable and are often derived from specific hosts. The Giardia assemblages are separated by large genetic distances, which might account for their relevant biological and pathogenic differences. In this work, we analyzed the RNAs cargo released into exosomal-like vesicles (ElVs) by the assemblages A and B, which differentially infect humans, and the assemblage E, which infects hoofed animals. The RNA sequencing analysis revealed that the ElVs of each assemblage contained distinct small RNA (sRNA) biotypes, suggesting a preference for specific packaging in each assemblage. These sRNAs were classified into three categories, ribosomal-small RNAs (rsRNAs), messenger-small RNAs (msRNAs), and transfer-small RNAs (tsRNAs), which may play a regulatory role in parasite communication and contribute to host-specificity and pathogenesis. Uptake experiments showed, for the first time, that ElVs were successfully internalized by the parasite trophozoites. Furthermore, we observed that the sRNAs contained inside these ElVs were first located below the plasma membrane but then distributed along the cytoplasm. Overall, the study provides new insights into the molecular mechanisms underlying the host-specificity and pathogenesis of G. lamblia and highlights the potential role of sRNAs in parasite communication and regulation.

Next-Generation Leishmanization: Revisiting Molecular Targets for Selecting Genetically Engineered Live-Attenuated Leishmania

Despite decades of research devoted to finding a vaccine against leishmaniasis, we are still lacking a safe and effective vaccine for humans. Given this scenario, the search for a new prophylaxis alternative for controlling leishmaniasis should be a global priority. Inspired by leishmanization-a first generation vaccine strategy where live L. major parasites are inoculated in the skin to protect against reinfection-live-attenuated Leishmania vaccine candidates are promising alternatives due to their robust elicited protective immune response. In addition, they do not cause disease and could provide long-term protection upon challenge with a virulent strain. The discovery of a precise and easy way to perform CRISPR/Cas-based gene editing allowed the selection of safer null mutant live-attenuated Leishmania parasites obtained by gene disruption. Here, we revisited molecular targets associated with the selection of live-attenuated vaccinal strains, discussing their function, their limiting factors and the ideal candidate for the next generation of genetically engineered live-attenuated Leishmania vaccines to control leishmaniasis.

Protozoa-Derived Extracellular Vesicles on Intercellular Communication with Special Emphasis on Giardia lamblia

Parasitic diseases are an important worldwide problem threatening human health and affect millions of people. Acute diarrhea, intestinal bleeding, malabsorption of nutrients and nutritional deficiency are some of the issues related to intestinal parasitic infections. Parasites are experts in subvert the host immune system through different kinds of mechanisms. There are evidences that extracellular vesicles (EVs) have an important role in dissemination of the disease and in modulating the host immune system. Released by almost all types of cells, these nanovesicles are a natural secretory product containing multiple components of interest. The EVs are classified as apoptotic bodies, microvesicles, exosomes, ectosomes, and microparticles, according to their physical characteristics, biochemical composition and cell of origin. Interestingly, EVs play an important role in intercellular communication between parasites as well as with the host cells. Concerning Giardia lamblia, it is known that this parasite release EVs during it life cycle that modulate the parasite growth and adherence as well the immune system of the host. Here we review the recently updates on protozoa EVs, with particular emphasis on the role of EVs released by the flagellate protozoa G. lamblia in cellular communication and its potential for future applications as vaccine, therapeutic agent, drug delivery system and as diagnostic or prognostic biomarker.

Extracellular vesicles derived from Trichinella Spiralis larvae promote the polarization of macrophages to M2b type and inhibit the activation of fibroblasts

Trichinella spiralis (T. spiralis) is a globally distributed food-borne parasite that can coexist with the host for a long time after infection. Trichinella-derived secretions can regulate the immune response and fibroblasts of the host, but the specific mechanisms involved are still unclear. The purpose of this study was to investigate the role of T. spiralis larvae-derived extracellular vesicles (EVs) and their key miRNAs in the process of T. spiralis–host interaction. In this study, we found that the EVs of T. spiralis larvae, as well as miR-1-3p and let-7-5p, expressed in T. spiralis larvae-derived EVs, can promote the polarization of bone marrow macrophages to M2b type while inhibiting the activation of fibroblasts. These findings will contribute to further understanding of the molecular mechanisms underlying T. spiralis–host interactions.

The state of the art of extracellular vesicle research in protozoan infection

Protozoan diseases seriously affect the health of human beings, livestock and poultry and lead to high economic and medical costs. Extracellular vesicles (EVs) are membranous structures formed through biological processes that play important roles in immune regulation. Studies have shown that parasites transmit information to hosts through EVs to modulate host immune responses. The major roles played by EVs released from parasites involve facilitating parasitization of the host. In this review, we discuss relevant recently obtained data on EVs secreted by different kinds of protozoa, including their molecular mechanisms, and discuss the roles played by EVs in the occurrence and development of parasitic diseases.

Isolation, characterization, and functional study of extracellular vesicles derived from Leishmania tarentolae

Leishmania (L.) species are protozoan parasites with a complex life cycle consisting of a number of developmental forms that alternate between the sand fly vector and their host. The non-pathogenic species L. tarentolae is not able to induce an active infection in a human host. It has been observed that, in pathogenic species, extracellular vesicles (EVs) could exacerbate the infection. However, so far, there is no report on the identification, isolation, and characterization of L. tarentolae EVs. In this study, we have isolated and characterized EVs from L. tarentolaeGFP+ (tEVs) along with L. majorGFP+ as a reference and positive control. The EVs secreted by these two species demonstrated similar particle size distribution (approximately 200 nm) in scanning electron microscopy and nanoparticle tracking analysis. Moreover, the said EVs showed similar protein content, and GFP and GP63 proteins were detected in both using dot blot analysis. Furthermore, we could detect Leishmania-derived GP63 protein in THP-1 cells treated with tEVs. Interestingly, we observed a significant increase in the production of IFN-γ, TNF-α, and IL-1β, while there were no significant differences in IL-6 levels in THP-1 cells treated with tEVs following an infection with L. major compared with another group of macrophages that were treated with L. major EVs prior to the infection. Another exciting observation of this study was a significant decrease in parasite load in tEV-treated Leishmania-infected macrophages. In addition, in comparison with another group of Leishmania-infected macrophages which was not exposed to any EVs, tEV managed to increase IFN-γ and decrease IL-6 and the parasite burden. In conclusion, we report for the first time that L. tarentolae can release EVs and provide evidence that tEVs are able to control the infection in human macrophages, making them a great potential platform for drug delivery, at least for parasitic infections.

Tissue tropism: Is it an intrinsic characteristic of Leishmania species?

The genus Leishmania comprises a wide range of species, some of which are pathogenic to humans and each of which has a different tissue preference, resulting in one of the three clinical forms of human leishmaniasis: visceral, cutaneous, or mucocutaneous. Although, all pathogenic species are deposited intradermally in the mammalian host upon an infectious sand fly bite, only the viscerotropic strains can leave the skin and reach the internal organs. We assume that Leishmania tissue tropism is not only the result of Leishmania genetic determinism but is also governed by the interaction of the parasite with different vectorial and human host elements. To shed light on these elements and key steps determining the course of the infection, we describe throughout this review the disease's progression from the early stages of infection taking place in the skin to the late stages succeeding in the parasite's visceral dissemination. Hence, we address the question of Leishmania tropism, through providing relevant hypotheses and answers gathered from the literature.

The Role of Nuclear Factor Kappa B (NF-κB) in the Immune Response against Parasites

The immune system consists of various cells, organs, and processes that interact in a sophisticated manner to defend against pathogens. Upon initial exposure to an invader, nonspecific mechanisms are raised through the activation of macrophages, monocytes, basophils, mast cells, eosinophils, innate lymphoid cells, or natural killer cells. During the course of an infection, more specific responses develop (adaptive immune responses) whose hallmarks include the expansion of B and T cells that specifically recognize foreign antigens. Cell to cell communication takes place through physical interactions as well as through the release of mediators (cytokines, chemokines) that modify cell activity and control and regulate the immune response. One regulator of cell states is the transcription factor Nuclear Factor kappa B (NF-κB) which mediates responses to various stimuli and is involved in a variety of processes (cell cycle, development, apoptosis, carcinogenesis, innate and adaptive immune responses). It consists of two protein classes with NF-κB1 (p105/50) and NF-κB2 (p100/52) belonging to class I, and RelA (p65), RelB and c-Rel belonging to class II. The active transcription factor consists of a dimer, usually comprised of both class I and class II proteins conjugated to Inhibitor of κB (IκB). Through various stimuli, IκB is phosphorylated and detached, allowing dimer migration to the nucleus and binding of DNA. NF-κB is crucial in regulating the immune response and maintaining a balance between suppression, effective response, and immunopathologies. Parasites are a diverse group of organisms comprised of three major groups: protozoa, helminths, and ectoparasites. Each group induces distinct effector immune mechanisms and is susceptible to different types of immune responses (Th₁, Th₂, Th₁₇). This review describes the role of NF-κB and its activity during parasite infections and its contribution to inducing protective responses or immunopathologies.

Long-Term In Vitro Passaging Had a Negligible Effect on Extracellular Vesicles Released by Leishmania amazonensis and Induced Protective Immune Response in BALB/c Mice

Depending on Leishmania species and the presence/absence of virulence factors, Leishmania extracellular vesicles (EVs) can differently stimulate host immune cells. This work is aimed at characterizing and evaluating the protective role of EVs released by Leishmania amazonensis promastigotes under different maintenance conditions. Initially, using a control strain, we standardized 26°C as the best release temperature to obtain EVs with a potential protective role in the experimental leishmaniasis model. Then, long-term (LT-P) promastigotes of L. amazonensis were obtained after long-term in vitro culture (100 in vitro passages). In vivo-derived (IVD-P) promastigotes of L. amazonensis were selected after 3 consecutive experimental infections in BALB/c mice. Those strains developed similar lesion sizes except for IVD-P at 8 weeks post infection. No differences in EV production were detected in both strains. However, the presence of LPG between LT-P and IVD-P EVs was different. Groups of mice immunized with EVs emulsified in the adjuvant and challenged with IVD-P parasites showed decreased lesion size and parasitic load compared with the nonimmunized groups. The immunization regimen with two doses showed high IFN-γ and IgG2a titers in challenged mice with either IVD-P or LT-P EVs. IL-4 and IL-10 were detected in immunized mice, suggesting a mixed Th1/Th2 profile. EVs released by either IVD-P or LT-P induced a partial protective effect in an immunization model. Thus, our results uncover a potential protective role of EVs from L. amazonensis for cutaneous leishmaniasis. Moreover, long-term maintenance under in vitro conditions did not seem to affect EV release and their immunization properties in mice.

Impact of the Extracellular Vesicles Derived From Trypanosoma cruzi: A Paradox in Host Response and Lipid Metabolism Modulation

Chagas disease is a major public health problem, especially in the South and Central America region. Its incidence is related to poverty and presents a high rate of morbidity and mortality. The pathogenesis of Chagas disease is complex and involves many interactive pathways between the hosts and the Trypanosoma cruzi. Several factors have been implicated in parasite-host interactions, including molecules secreted by infected cells, lipid mediators and most recent, extracellular vesicles (EVs). The EVs of T. cruzi (EVsT) were reported for the first time in the epimastigote forms about 42 years ago. The EVsT are involved in paracrine communication during the infection and can have an important role in the inflammatory modulation and parasite escape mechanism. However, the mechanisms by which EVs employ their pathological effects are not yet understood. The EVsT seem to participate in the activation of macrophages via TLR2 triggering the production of cytokines and a range of other molecules, thus modulating the host immune response which promotes the parasite survival. Moreover, new insights have demonstrated that EVsT induce lipid body formation and PGE₂ synthesis in macrophages. This phenomenon is followed by the inhibition of the synthesis of pro-inflammatory cytokines and antigen presentation, causing decreased parasitic molecules and allowing intracellular parasite survival. Therefore, this mini review aims to discuss the role of the EVs from T. cruzi as well as its involvement in the mechanisms that regulate the host immune response in the lipid metabolism and its significance for the Chagas disease pathophysiology.

Leishmania 360°: Guidelines for Exosomal Research

Leishmania parasites are a group of kinetoplastid pathogens that cause a variety of clinical disorders while maintaining cell communication by secreting extracellular vesicles. Emerging technologies have been adapted for the study of Leishmania-host cell interactions, to enable the broad-scale analysis of the extracellular vesicles of this parasite. Leishmania extracellular vesicles (LEVs) are spheroidal nanoparticles of polydispersed suspensions surrounded by a layer of lipid membrane. Although LEVs have attracted increasing attention from researchers, many aspects of their biology remain unclear, including their bioavailability and function in the complex molecular mechanisms of pathogenesis. Given the importance of LEVs in the parasite-host interaction, and in the parasite-parasite relationships that have emerged during the evolutionary history of these organisms, the present review provides an overview of the available data on Leishmania, and formulates guidelines for LEV research. We conclude by reporting direct methods for the isolation of specific LEVs from the culture supernatant of the promastigotes and amastigotes that are suitable for a range of different downstream applications, which increases the compatibility and reproducibility of the approach for the establishment of optimal and comparable isolation conditions and the complete characterization of the LEV, as well as the critical immunomodulatory events triggered by this important group of parasites.

Nanotechnology-aided diagnosis, treatment and prevention of leishmaniasis

Leishmaniasis is a prevalent parasitic infection belonging to neglected tropical diseases. It is caused by Leishmania protozoan parasites transmitted by sandflies and it is responsible for increased morbidity/mortality especially in low- and middle-income countries. The lack of cheap, portable, easy to use diagnostic tools exhibiting high efficiency and specificity impede the early diagnosis of the disease. Furthermore, the typical anti-leishmanial agents are cytotoxic, characterized by low patient compliance and require long-term regimen and usually hospitalization. In addition, due to the intracellular nature of the disease, the existing treatments exhibit low bioavailability resulting in low therapeutic efficacy. The above, combined with the common development of resistance against the anti-leishmanial agents, denote the urgent need for novel therapeutic strategies. Furthermore, the lack of effective prophylactic vaccines hinders the control of the disease. The development of nanoparticle-based biosensors and nanocarrier-aided treatment and vaccination strategies could advance the diagnosis, therapy and prevention of leishmaniasis. The present review intends to highlight the various nanotechnology-based approaches pursued until now to improve the detection of Leishmania species in biological samples, decrease the side effects and increase the efficacy of anti-leishmanial drugs, and induce enhanced immune responses, specifically focusing on the outcome of their preclinical and clinical evaluation.

The Emerging World of Membrane Vesicles: Functional Relevance, Theranostic Avenues and Tools for Investigating Membrane Function

Lipids are essential components of cell membranes and govern various membrane functions. Lipid organization within membrane plane dictates recruitment of specific proteins and lipids into distinct nanoclusters that initiate cellular signaling while modulating protein and lipid functions. In addition, one of the most versatile function of lipids is the formation of diverse lipid membrane vesicles for regulating various cellular processes including intracellular trafficking of molecular cargo. In this review, we focus on the various kinds of membrane vesicles in eukaryotes and bacteria, their biogenesis, and their multifaceted functional roles in cellular communication, host-pathogen interactions and biotechnological applications. We elaborate on how their distinct lipid composition of membrane vesicles compared to parent cells enables early and non-invasive diagnosis of cancer and tuberculosis, while inspiring vaccine development and drug delivery platforms. Finally, we discuss the use of membrane vesicles as excellent tools for investigating membrane lateral organization and protein sorting, which is otherwise challenging but extremely crucial for normal cellular functioning. We present current limitations in this field and how the same could be addressed to propel a fundamental and technology-oriented future for extracellular membrane vesicles.

Distinct immunomodulatory properties of extracellular vesicles released by different strains of Acanthamoeba

Free living amoeba of the genus Acanthamoeba are opportunist protozoan involved in corneal, systemic, and encephalic infections in humans. Most of the mechanisms underlying intraspecies variations and pathogenicity are still unknown. Recently, the release of extracellular vesicles (EVs) by Acanthamoeba was reported. However, comparative characterization of EVs from distinct strains is not available. The aim of this study was to evaluate EVs produced by Acanthamoeba from different genotypes, comparing their proteases profile and immunomodulatory properties. EVs from four environmental or clinical strains (genotypes T1, T2, T4, and T11) were obtained by ultracentrifugation, quantitated by nanoparticle tracking analysis and analyzed by scanning and transmission electron microscopy. Proteases profile was determined by zymography and functional properties of EVs (measure of nitrite and cytokine production) were determined after peritoneal macrophage stimulation. Despite their genotype, all strains released EVs and no differences in size and/or concentration were detected. EVs exhibited a predominant activity of serine proteases (pH 7.4 and 3.5), with higher intensity in T4 and T1 strains. EVs from the environmental, nonpathogenic T11 strain exhibited a more proinflammatory profile, inducing higher levels of Nitrite, tumor necrosis factor alpha and interleukin-6 via TLR4/TLR2 than those strains with pathogenic traits (T4, T1, and T2). Preincubation with EVs treated with protease inhibitors or heating drastically decreased nitrite concentration production in macrophages. Those data suggest that immunomodulatory effects of EVs may reflect their pathogenic potential depending on the Acanthamoeba strains and are dependent on protease integrity.

Extracellular Vesicles in Trypanosomatids: Host Cell Communication

Trypanosoma cruzi, Trypanosoma brucei and Leishmania (Trypanosomatidae: Kinetoplastida) are parasitic protozoan causing Chagas disease, African Trypanosomiasis and Leishmaniases worldwide. They are vector borne diseases transmitted by triatomine bugs, Tsetse fly, and sand flies, respectively. Those diseases cause enormous economic losses and morbidity affecting not only rural and poverty areas but are also spreading to urban areas. During the parasite-host interaction, those organisms release extracellular vesicles (EVs) that are crucial for the immunomodulatory events triggered by the parasites. EVs are involved in cell-cell communication and can act as important pro-inflammatory mediators. Therefore, interface between EVs and host immune responses are crucial for the immunopathological events that those diseases exhibit. Additionally, EVs from these organisms have a role in the invertebrate hosts digestive tracts prior to parasite transmission. This review summarizes the available data on how EVs from those medically important trypanosomatids affect their interaction with vertebrate and invertebrate hosts.