A vaccine based on exosomes secreted by a dendritic cell line confers protection against T. gondii infection in syngeneic and allogeneic mice

The biology and function of extracellular vesicles in immune response and immunity

Extracellular vesicles (EVs), such as ectosomes and exosomes, contain DNA, RNA, proteins and are encased in a phospholipid bilayer. EVs provide intralumenal cargo for delivery into the cytoplasm of recipient cells with an impact on the function of immune cells, in part because their biogenesis can also intersect with antigen processing and presentation. Motile EVs from activated immune cells may increase the frequency of immune synapses on recipient cells in a proximity-independent manner for local and long-distance modulation of systemic immunity in inflammation, autoimmunity, organ fibrosis, cancer, and infections. Natural and engineered EVs exhibit the ability to impact innate and adaptive immunity and are entering clinical trials. EVs are likely a component of an optimally functioning immune system, with the potential to serve as immunotherapeutics. Considering the evolving evidence, it is possible that EVs could be the original primordial organic units that preceded the creation of the first cell.

Potential of extracellular vesicles in the pathogenesis, diagnosis and therapy for parasitic diseases

Parasitic diseases have a significant impact on human and animal health, representing a major hazard to the public and causing economic and health damage worldwide. Extracellular vesicles (EVs) have long been recognized as diagnostic and therapeutic tools but are now also known to be implicated in the natural history of parasitic diseases and host immune response modulation. Studies have shown that EVs play a role in parasitic disease development by interacting with parasites and communicating with other types of cells. This review highlights the most recent research on EVs and their role in several aspects of parasite-host interactions in five key parasitic diseases: Chagas disease, malaria, toxoplasmosis, leishmaniasis and helminthiases. We also discuss the potential use of EVs as diagnostic tools or treatment options for these infectious diseases.

Extracellular vesicles derived from plasmodium-infected red blood cells alleviate cerebral malaria in plasmodium berghei ANKA-infected C57BL/6J mice

RTS,S is the first malaria vaccine recommended for implementation among young children at risk. However, vaccine efficacy is modest and short-lived. To mitigate the risk of cerebral malaria (CM) among children under the age of 5, it is imperative to develop new vaccines. EVs are potential vaccine candidates as they obtain the ability of brain-targeted delivery and transfer plasmodium antigens and immunomodulators during infections. This study extracted EVs from BALB/c mice infected with Plasmodium yoelii 17XNL (P.y17XNL). C57BL/6J mice were intravenously immunized with EVs (EV-I.V. + CM group) or subcutaneously vaccinated with the combination of EVs and CpG ODN-1826 (EV + CPG ODN-S.C. + CM group) on days 0 and 20, followed by infection with Plasmodium berghei ANKA (P.bANKA) on day 20 post-second immunization. We monitored Parasitemia and survival rate. The integrity of the Blood-brain barrier (BBB) was examined using Evans blue staining.The levels of cytokines and adhesion molecules were evaluated using Luminex, RT-qPCR, and WB. Brain pathology was evaluated by hematoxylin and eosin and immunohistochemical staining. The serum levels of IgG, IgG1, and IgG2a were analyzed by enzyme-linked immunosorbent assay. Compared with those in the P.bANKA-infected group, parasitemia increased slowly, death was delayed (day 10 post-infection), and the survival rate reached 75 %-83.3 % in the EV-I.V. + ECM and EV + CPG ODN-S.C. + ECM groups. Meanwhile, compared with the EV + CPG ODN-S.C. + ECM group, although parasitemia was almost the same, the survival rate increased in the EV-I.V. + ECM group.Additionally, EVs immunization markedly downregulated inflammatory responses in the spleen and brain and ameliorated brain pathological changes, including BBB disruption and infected red blood cell (iRBC) sequestration. Furthermore, the EVs immunization group exhibited enhanced antibody responses (upregulation of IgG1 and IgG2a production) compared to the normal control group. EV immunization exerted protective effects, improving the integrity of the BBB, downregulating inflammation response of brain tissue, result in reduces the incidence of CM. The protective effects were determined by immunological pathways and brain targets elicited by EVs. Intravenous immunization exhibited better performance than subcutaneous immunization, which perhaps correlated with EVs, which can naturally cross BBB to play a better role in brain protection.

Bioengineered small extracellular vesicles deliver multiple SARS-CoV-2 antigenic fragments and drive a broad immunological response

The COVID-19 pandemic highlighted the clear risk that zoonotic viruses pose to global health and economies. The scientific community responded by developing several efficacious vaccines which were expedited by the global need for vaccines. The emergence of SARS-CoV-2 breakthrough infections highlights the need for additional vaccine modalities to provide stronger, long-lived protective immunity. Here we report the design and preclinical testing of small extracellular vesicles (sEVs) as a multi-subunit vaccine. Cell lines were engineered to produce sEVs containing either the SARS-CoV-2 Spike receptor-binding domain, or an antigenic region from SARS-CoV-2 Nucleocapsid, or both in combination, and we tested their ability to evoke immune responses in vitro and in vivo. B cells incubated with bioengineered sEVs were potent activators of antigen-specific T cell clones. Mice immunised with sEVs containing both sRBD and Nucleocapsid antigens generated sRBD-specific IgGs, nucleocapsid-specific IgGs, which neutralised SARS-CoV-2 infection. sEV-based vaccines allow multiple antigens to be delivered simultaneously resulting in potent, broad immunity, and provide a quick, cheap, and reliable method to test vaccine candidates.

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.

Immune system roles in pathogenesis, prognosis, control, and treatment of Toxoplasma gondii infection

Toxoplasma gondii is the protozoan causative agent of toxoplasmosis in humans and warm-blooded animals. Recent studies have illustrated that the immune system plays a pivotal role in the pathogenesis of toxoplasmosis by triggering immune cytokines like IL-12, TNF-α, and IFN-γ and immune cells like DCs, Th1, and Th17. On the other hand, some immune components can serve as prognosis markers of toxoplasmosis. In healthy people, the disease is often asymptomatic, but immunocompromised people and newborns may suffer severe symptoms and complications. Therefore, the immune prognostic markers may provide tools to measure the disease progress and help patients to avoid further complications. Immunotherapies using monoclonal antibody, cytokines, immune cells, exosomes, novel vaccines, and anti-inflammatory molecules open new horizon for toxoplasmosis treatment. In this review article, we discussed the immunopathogenesis, prognosis, and immunotherapy of Toxoplasma gondii infection.

Potential applications of using tissue-specific EVs in targeted therapy and vaccinology

Many cell types secrete spherical membrane bodies classified as extracellular vesicles (EVs). EVs participate in intercellular communication and are present in body fluids, including blood, lymph, and cerebrospinal fluid. The time of EVs survival in the body varies depending on the body's localisation. Once the EVs reach cells, they trigger a cellular response. Three main modes of direct interaction of EVs with a target cell were described: receptor-ligand interaction mode, a direct fusion of EVs with the cellular membrane and EVs internalisation. Studies focused on the medical application of EVs. Medical application of EVs may require modification of their surface and interior. EVs surface was modified by affecting the parental cells or by the direct amendment of isolated EVs. The interior modification involved introducing materials into the cells or direct administrating isolated EVs. EVs carry proteins, lipids, fragments of DNA, mRNA, microRNA (miRNA) and long non-coding RNA. Because of EVs availability in liquid biopsy, they are potential diagnostic markers. Modified EVs could enhance the treatment of diseases such as colorectal cancer, Parkinson's disease, leukaemia or liver fibrosis. EVs have specific tissue tropisms, which makes them convenient organ-directed carriers of nucleic acids, drugs and vaccines. In conclusion, recently published works have shown that EVs could become biomarkers and modern vehicles of advanced drug forms.

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.

Host-pathogen interactions mediated by extracellular vesicles in Toxoplasma gondii infection during pregnancy

Molecular communication between a pathogen and its host is crucial for a successful interplay. Extracellular vesicles (EVs) act as mediators for the delivery of molecular signals among pathogens or between pathogens and the host. Toxoplasma gondii (T. gondii), an intracellular parasite with a worldwide presence, produces EVs itself, or induces the secretion of EVs from infected host cells potentially having capacities to modulate the host immune response. T. gondii infection is particularly important during pregnancy. Depending on the gestational age at the time of infection, the parasite can be transmitted through the placenta to the fetus, causing clinical complications such as jaundice, hepatosplenomegaly, chorioretinitis, cranioencephalic abnormalities, or even death. T. gondii infection is related to a pro-inflammatory immune response in both mother and fetus, which may enhance parasite transmission, but the implication of EV signaling in this process remains unclear. In this review, we summarize the current knowledge on EV release from T. gondii and its human host cells in regard to the immunological consequences and the passage through the placenta.

The potential application of encapsulated exosomes: A new approach to increase exosomes therapeutic efficacy

Cell therapy is one of the methods that have shown promising results in treating diseases in recent decades. However, the use of different types of cells comes with limitations. The application of immune cells in cell therapy can lead to cytokine storms and inappropriate responses to self-antigens. Also, the use of stem cells has the potential to create tumors. Also, cells may not migrate to the injury site after intravenous injection. Therefore, using exosomes from different cells as therapeutic candidates were proposed. Due to their small size and favorable characteristics, such as biocompatibility and immunocompatibility, the easy storage and isolation, exosomes have attracted much attention. They are used in treating many diseases, including cardiovascular diseases, orthopedic diseases, autoimmune diseases, and cancer. However, the results of various studies have shown that the therapeutic efficiency of exosomes (Exo) can be increased by loading different drugs and microRNAs inside them (encapsulated exosomes). Therefore, analyzing studies investigating encapsulated exosomes' therapeutic ability is critical. In this study, we have examined the studies related to the use of encapsulated exosomes in treating diseases such as cancer and infectious diseases and their use in regenerative medicine. Compared to intact exosomes, the results show that the application of encapsulated exosomes has a higher therapeutic ability. Therefore it is suggested to use this method depending on the treatment type to increase the treatment's efficiency.

Exosomes: from biology to immunotherapy in infectious diseases

Exosomes are extracellular vesicles derived from the endosomal compartment, which are released by all kinds of eukaryotic and prokaryotic organisms. These vesicles contain a variety of biomolecules that differ both in quantity and type depending on the origin and cellular state. Exosomes are internalized by recipient cells, delivering their content and thus contributing to cell-cell communication in health and disease. During infections exosomes may exert a dual role, on one hand, they can transmit pathogen-related molecules mediating further infection and damage, and on the other hand, they can protect the host by activating the immune response and reducing pathogen spread. Selective packaging of pathogenic components may mediate these effects. Recently, quantitative analysis of samples by omics technologies has allowed a deep characterization of the proteins, lipids, RNA, and metabolite cargoes of exosomes. Knowledge about the content of these vesicles may facilitate their therapeutic application. Furthermore, as exosomes have been detected in almost all biological fluids, pathogenic or host-derived components can be identified in liquid biopsies, making them suitable for diagnosis and prognosis. This review attempts to organize the recent findings on exosome composition and function during viral, bacterial, fungal, and protozoan infections, and their contribution to host defense or to pathogen spread. Moreover, we summarize the current perspectives and future directions regarding the potential application of exosomes for prophylactic and therapeutic purposes.

SARS-CoV-2 Spike Protein-Activated Dendritic Cell-Derived Extracellular Vesicles Induce Antiviral Immunity in Mice

The onset and spread of the SARS-CoV-2 virus have created an unprecedented universal crisis. Although vaccines have been developed against the parental SARS-CoV-2, outbreaks of the disease still occur through the appearance of different variants, suggesting a continuous need for improved and effective therapeutic strategies. Therefore, we developed a novel nanovesicle presenting Spike protein on the surface of the dendritic cell-derived extracellular vesicles (DEVs) for use as a potential vaccine platform against SARS-CoV-2. DEVs express peptide/MHC-I (pMHC-I) complexes, CCR-7, on their surface. The immunogenicity and efficacy of the Spike-activated DEVs were tested in mice and compared with free Spike protein. A 1/10 Spike equivalent dose of DEVs showed a superior potency in inducing anti-Spike IgG titers in blood of mice when compared to dendritic cells or free Spike protein treatment. Moreover, DEV-induced sera effectively reduced viral infection by 55-60% within 15 days of booster dose administration. Furthermore, a 1/10 Spike equivalent dose of DEV-treated mice was found to be equally effective in inducing CD19+CD38+ T-cells in the spleen and lymph node; CD8 cells in the bone marrow, spleen, and lymph node; and CD4+CD25+ T-cells in the spleen and lymph node after 90 days of treatment. Thus, our results support the immunogenic nature of DEVs, demonstrating that a low dose of DEVs induces antibodies to inhibit SARS-CoV-2 infection in vitro, therefore warranting further investigations.

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.

Immune Cell-Derived Extracellular Vesicles in the Face of Pathogenic Infections

Extracellular Vesicles (EVs) are a collection of vesicles released from cells that play an important role in intercellular communication. Microbial infections are known as one of the major problems in the medical field. Considering the increasing resistance of strains to routine drug treatments, the need for new therapies seems to be more than ever. Recent studies have shown that the EVs released from immune cells during microbial infections had anti-microbial effects or were able to induce neighbouring cells to display anti-microbial effects. This mini-review aimed to explore the latest studies on immune cell-derived EVs in viral, bacterial, fungal, and parasitic infections. Review of the literature demonstrated that specific cargos in EVs were involved in the fight against pathogenic infections. Additionally, the transport of appropriate bioactive molecules including miRNAs, mRNAs, and proteins via EVs could mediate the anti-microbial process. Thus, it could be a proof-of-principle that therapeutic approaches based on EVs derived from immune cells could offer a promising path forward, which is still in early stages and needs further assessments.

Stem Cell-based therapies for COVID-19-related acute respiratory distress syndrome

As the number of confirmed cases and resulting death toll of the COVID-19 pandemic continue to increase around the globe - especially with the emergence of new mutations of the SARS-CoV-2 virus in addition to the known alpha, beta, gamma, delta and omicron variants - tremendous efforts continue to be dedicated to the development of interventive therapeutics to mitigate infective symptoms or post-viral sequelae in individuals for which vaccines are not accessible, viable or effective in the prevention of illness. Many of these investigations aim to target the associated acute respiratory distress syndrome, or ARDS, which induces damage to lung epithelia and other physiologic systems and is associated with progression in severe cases. Recently, stem cell-based therapies have demonstrated preliminary efficacy against ARDS based on a number of preclinical and preliminary human safety studies, and based on promising outcomes are now being evaluated in phase II clinical trials for ARDS. A number of candidate stem cell therapies have been found to exhibit low immunogenicity, coupled with inherent tropism to injury sites. In recent studies, these have demonstrated the ability to modulate suppression of pro-inflammatory cytokine signals such as those characterizing COVID-19-associated ARDS. Present translational studies are aiming to optimize the safety, efficacy and delivery to fully validate stem cell-based strategies targeting COVID-19 associated ARDS for viable clinical application.

Therapeutically harnessing extracellular vesicles

The field of extracellular vesicle (EV) research has developed rapidly over the last decade from the study of fundamental biology to a subject of significant clinical relevance. The potential of harnessing EVs in the diagnosis and treatment of diseases - including cancer and neurological and cardiovascular disorders - is now being recognized. Accordingly, the applications of EVs as therapeutic targets, biomarkers, novel drug delivery agents and standalone therapeutics are being actively explored. This Review provides a brief overview of the characteristics and physiological functions of the various classes of EV, focusing on their association with disease and emerging strategies for their therapeutic exploitation.

Exogenous and Endogenous Dendritic Cell-Derived Exosomes: Lessons Learned for Immunotherapy and Disease Pathogenesis

Immune therapeutic exosomes, derived exogenously from dendritic cells (DCs), the 'directors' of the immune response, are receiving favorable safety and tolerance profiles in phase I and II clinical trials for a growing number of inflammatory and neoplastic diseases. DC-derived exosomes (EXO), the focus of this review, can be custom tailored with immunoregulatory or immunostimulatory molecules for specific immune cell targeting. Moreover, the relative stability, small size and rapid uptake of EXO by recipient immune cells offer intriguing options for therapeutic purposes. This necessitates an in-depth understanding of mechanisms of EXO biogenesis, uptake and routing by recipient immune cells, as well as their in vivo biodistribution. Against this backdrop is recognition of endogenous exosomes, secreted by all cells, the molecular content of which is reflective of the metabolic state of these cells. In this regard, exosome biogenesis and secretion is regulated by cell stressors of chronic inflammation and tumorigenesis, including dysbiotic microbes, reactive oxygen species and DNA damage. Such cell stressors can promote premature senescence in young cells through the senescence associated secretory phenotype (SASP). Pathological exosomes of the SASP amplify inflammatory signaling in stressed cells in an autocrine fashion or promote inflammatory signaling to normal neighboring cells in paracrine, without the requirement of cell-to-cell contact. In summary, we review relevant lessons learned from the use of exogenous DC exosomes for immune therapy, as well as the pathogenic potential of endogenous DC exosomes.

Strategies for Engineering Exosomes and Their Applications in Drug Delivery

Exosomes are representative of a promising vehicle for delivery of biomolecules. Despite their discovery nearly 40 years, knowledge of exosomes and extracellular vesicles (EVs) and the role they play in etiology of disease and normal cellular physiology remains in its infancy. EVs are produced in almost all cells, containing nucleic acids, lipids, and proteins delivered from donor cells to recipient cells. Consequently, they act as mediators of intercellular communication and molecular transfer. Recent studies have shown that, exosomes are associated with numerous physiological and pathological processes as a small subset of EVs, and they play a significant role in disease progression and treatment. In this review, we discuss several key questions: what are exosomes, why do they matter, and how do we repurpose them in their strategies and applications in drug delivery systems. In addition, opportunities and challenges of exosome-based theranostics are also described and directions for future research are presented.

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.

Exosome-Based Vaccines: History, Current State, and Clinical Trials

Extracellular vesicles (EVs) are released by most cell types as part of an intracellular communication system in crucial processes such as inflammation, cell proliferation, and immune response. However, EVs have also been implicated in the pathogenesis of several diseases, such as cancer and numerous infectious diseases. An important feature of EVs is their ability to deliver a wide range of molecules to nearby targets or over long distances, which allows the mediation of different biological functions. This delivery mechanism can be utilized for the development of therapeutic strategies, such as vaccination. Here, we have highlighted several studies from a historical perspective, with respect to current investigations on EV-based vaccines. For example, vaccines based on exosomes derived from dendritic cells proved to be simpler in terms of management and cost-effectiveness than dendritic cell vaccines. Recent evidence suggests that EVs derived from cancer cells can be leveraged for therapeutics to induce strong anti-tumor immune responses. Moreover, EV-based vaccines have shown exciting and promising results against different types of infectious diseases. We have also summarized the results obtained from completed clinical trials conducted on the usage of exosome-based vaccines in the treatment of cancer, and more recently, coronavirus disease.

S. Typhi derived vaccines and a proposal for outer membrane vesicles (OMVs) as potential vaccine for typhoid fever

Typhoid fever is a serious systemic infection caused by Salmonella Typhi (S. Typhi), spread by the feco-oral route and closely associated with poor food hygiene and inadequate sanitation. Nearly 93% of S. Typhi strains have acquired antibiotic resistance against most antibiotics. Vaccination is the only promising way to prevent typhoid fever. This review covers the nature and composition of S. Typhi, pathogenecity and mode of infection, epidemiology, and nature of drug resistance. Several components (Vi-polysaccharides, O-antigens, flagellar antigens, full length OMPs, and short peptides from OMPs) of S. Typhi have been utilized for vaccine design for protection against typhoid fever. Vaccine delivery systems also contribute to efficacy of the vaccines. In this study, we propose to develop S. Typhi derived OMVs as vaccine for protection against typhoid fevers.

Characterization of extracellular vesicles isolated from types I, II and III strains of Toxoplasma gondii

This study investigated the participation extracellular vesicles (EVs) in Toxoplasma gondii-host interaction. EVs of three T. gondii strains (RH, ME-49 and VEG) were purified by chromatography and ELISA. Results of "nanoparticle tracking analysis" and scanning electron microscopy showed that RH strain released more EVs than other strains. Images of transmission electron microscopy showed that in beginning of incubation (culture medium), EVs were inside of tachyzoites preparing to be released. After 24 hours, they were largely produced inside tachyzoites and were released through plasma membrane. The parasite burden of mice infected with RH strain plus EVs was increased and with early death of 1-2 days compared of those that received only parasites. EV proteins of ME-49 and VEG strains were poorly reactive to sera of infected patients in imunoblot. However, those from RH strain were reactive against sera of patients with cerebral toxoplasmosis. EVs stimulated murine splenocytes caused similar production of IFN-γ and IL-10 levels. RH strain derived EVs stimulated more TNF-α than those stimulated by other strains. T. gondii and infected hosts can express the same miRNAs (miR-155-5p, miR-125b-5p, miR-423-3p). In conclusion, T. gondii derived EVs promote host-parasite interactions, modulate host immune responses, carry virulent factors and cause an imbalance in cellular immune response.

Selective Antimicrobial Therapies for Periodontitis: Win the "Battle and the War"

Traditional antimicrobial therapies for periodontitis (PD) have long focused on non-selective and direct approaches. Professional cleaning of the subgingival biofilm by instrumentation of dental root surfaces, known as scaling and root planning (SRP), is the mainstay of periodontal therapy and is indisputably effective. Non-physical approaches used as adjuncts to SRP, such as chemical and biological agents, will be the focus of this review. In this regard, traditional agents such as oral antiseptics and antibiotics, delivered either locally or systemically, were briefly reviewed as a backdrop. While generally effective in winning the “battle” against PD in the short term, by reducing its signs and symptoms, patients receiving such therapies are more susceptible to recurrence of PD. Moreover, the long-term consequences of such therapies are still in question. In particular, concern about chronic use of systemic antibiotics and their influence on the oral and gut microbiota is warranted, considering antibiotic resistance plasmids, and potential transfer between oral and non-oral microbes. In the interest of winning the “battle and the war”, new more selective and targeted antimicrobials and biologics for PD are being studied. These are principally indirect, blocking pathways involved in bacterial colonization, nutrient acquisition, inflammation or cellular invasion without directly killing the pathogens. This review will focus on current and prospective antimicrobial therapies for PD, emphasizing therapies that act indirectly on the microbiota, with clearly defined cellular and molecular targets.

Characterization of murine extracellular vesicles and Toxoplasma gondii infection

This study characterized extracellular vesicles (EVs) of sera from mice infected with Toxoplasma gondii or immunized with EVs derived T gondii. EVs were purified of sera from four groups (5 A/Sn mice/group). EV-IM: Mice immunized with T gondii-released EVs; ACT: mice in acute infection; CHR: mice in chronic infection; and NI: normal mice. EVs were purified by ultracentrifugation. Concentration of serum-derived EVs from NI group was smaller than EV-IM, ACT and CHR groups. Most of the EVs from ACT and CHR groups were microvesicles, and they were bigger than the NI group. The same results were shown by Transmission Electron Microscopy. The presence of exosomes was shown in immunoblotting by tetraspanin (CD63 and CD9) evidence. Splenocytes of EV-IM, CHR and NI groups were stimulated with T. gondii derived EVs. EV-IM and CHR groups up-expressed IFN-γ; TNF-α and IL-17, when compared with the NI group. IL-10 was up-expressed only in the EV-IM group. EV-IM, ACT and CHR groups expressed more miR-155-5p, miR-29c-3p and miR-125b-5p than the NI group. Host-T gondii interaction can occur, also, via EVs. miRNAs participate in the modulation of cellular immune response against T gondii. These data give subsidies to propose the differentiation between infect or noninfect hosts by concentration of EVs.

Exosomes in the pathogenesis and treatment of ocular diseases

Exosomes have diverse functions and rich content and are involved in intercellular communication, immune regulation, viral infection, tissue regeneration, and the occurrence, development and metastasis of tumours. Notably, various stem cell-derived exosomes are expected to become new therapeutic approaches for inflammatory diseases and tumours and have good clinical application prospects. However, few studies have examined exosomes in ophthalmic diseases. Therefore, based on the functions of exosomes, this paper summarizes progress in the possible use of exosomes as treatment for specific ophthalmic diseases, aiming to determine the pathogenesis of exosomes to achieve more effective clinical diagnosis and treatment of these diseases.

Nanotechnology synergized immunoengineering for cancer

Novel strategies modulating the immune system yielded enhanced anticancer responses and improved cancer survival. Nevertheless, the success rate of immunotherapy in cancer treatment has been below expectation(s) due to unpredictable efficacy and off-target effects from systemic dosing of immunotherapeutic(s). As a result, there is an unmet clinical need for improving conventional immunotherapy. Nanotechnology offers several new strategies, multimodality, and multiplex biological targeting advantage to overcome many of these challenges. These efforts enable programming the pharmacodynamics, pharmacokinetics, and delivery of immunomodulatory agents/co-delivery of compounds to prime at the tumor sites for improved therapeutic benefits. This review provides an overview of the design and clinical principles of biomaterials driven nanotechnology and their potential use in personalized nanomedicines, vaccines, localized tumor modulation, and delivery strategies for cancer immunotherapy. In this review, we also summarize the latest highlights and recent advances in combinatorial therapies availed in the treatment of cold and complicated tumors. It also presents key steps and parameters implemented for clinical success. Finally, we analyse, discuss, and provide clinical perspectives on the integrated opportunities of nanotechnology and immunology to achieve synergistic and durable responses in cancer treatment.

Engineering of Extracellular Vesicles Based on Payload Changes for Tissue Regeneration

In the field of tissue regeneration and tissue engineering, many years ago, various nano to macroscopic-sized materials have been used to reduce inflammation and restore damaged tissue. Whether it is safe to study the regeneration of all tissues based on the biological mechanisms of an organism composed of cells is still debated, and studies using extracellular vesicles derived from cells have become popular in the past decade. It has been reported that exosomes with a size of 100 nm or less, which plays an important role in cell-cell communication, contain various factors, such as proliferation, anti-inflammatory, and growth factors. In addition, the payload of exosomes varies depending on the parent cell and the recipient cell, and a technology to differentiate the selective payload must treat specific diseases. In this review, we examined the current trends in research using exosomes derived from cells or tissues and analyzed various research reports on factors that can affect tissue regeneration.

Intravacuolar Pathogens Hijack Host Extracellular Vesicle Biogenesis to Secrete Virulence Factors

Extracellular vesicles (EVs) have garnered significant interest in recent years due to their contributions to cell-to-cell communication and disease processes. EVs are composed of a complex profile of bioactive molecules, which include lipids, nucleic acids, metabolites, and proteins. Although the biogenesis of EVs released by cells under various normal and abnormal conditions has been well-studied, there is incomplete knowledge about how infection influences EV biogenesis. EVs from infected cells contain specific molecules of both host and pathogen origin that may contribute to pathogenesis and the elicitation of the host immune response. Intracellular pathogens exhibit diverse lifestyles that undoubtedly dictate the mechanisms by which their molecules enter the cell’s exosome biogenesis schemes. We will discuss the current understanding of the mechanisms used during infection to traffic molecules from their vacuolar niche to host EVs by selected intravacuolar pathogens. We initially review general exosome biogenesis schemes and then discuss what is known about EV biogenesis in Mycobacterium, Plasmodium, Toxoplasma, and Leishmania infections, which are pathogens that reside within membrane delimited compartments in phagocytes at some time in their life cycle within mammalian hosts. The review includes discussion of the need for further studies into the biogenesis of EVs to better understand the contributions of these vesicles to host-pathogen interactions, and to uncover potential therapeutic targets to control these pathogens.

Immunization with extracellular vesicles excreted by Toxoplasma gondii confers protection in murine infection, activating cellular and humoral responses

The study aim was to analyze whether microvesicles and exosomes, named extracellular vesicles (EVs), purified from Toxoplasma gondii are able to stimulate the protective immunity of experimental mice when administered, as challenge, a highly virulent strain. EVs excreted from T. gondii tachyzoites (RH strain) were purified by chromatography and used for immunization assays in inbred mouse groups (EV-IM). Chronic infected (CHR) and naive (NI) mice were used as control groups, since the immune response is well known. After immunizations, experimental groups were challenged with 100 tachyzoites. Next, parasitemias were determined by real-time PCR (qPCR), and survival levels were evaluated daily. The humoral response was analyzed by detection of IgM, IgG, IgG1 and IgG2a, and opsonization experiments. The cellular response was evaluated in situ by immunohistochemistry on IFN-γ, IL-10, TNF-α and IL-17 expression in cells of five organs (brain, heart, liver, spleen and skeletal muscles). EV immunization reduced parasitemia and increased the survival index in two mouse lineages (A/Sn and BALB/c) infected with a lethal T. gondii strain. EV-IM mice had higher IgG1 levels than IgM or IgG2a. IgGs purified from sera of EV-IM mice were able to opsonize tachyzoites (RH strain), and mice that received these parasites had lower parasitemias, and mortality was delayed 48 h, compared with the same results from those receiving parasites opsonized with IgG purified from NI mice. Brain and spleen cells from EV-IM mice more highly expressed IFN-γ, IL-10 and TNF-α. In conclusion, EV-immunization was capable of inducing immune protection, eliciting high production of IgG1, IFN-γ, IL-10 and TNF-α.

Protective Immunity Against Neospora caninum Infection Induced by 14-3-3 Protein in Mice

Neospora caninum is an apicomplexan parasite that infects many mammals and remains a threatening disease worldwide because of the lack of effective drugs and vaccines. Our previous studies demonstrated that N. caninum 14-3-3 protein (Nc14-3-3), which is included in N. caninum extracellular vesicles (NEVs), can induce effective immune responses and stimulate cytokine expression in mouse peritoneal macrophages. However, whether Nc14-3-3 has a protective effect and its mechanisms are poorly understood. Here, we evaluated the immune responses and protective effects of Nc14-3-3 against exposure to 2 × 10⁷ Nc-1 tachyzoites. Antibody (IgG, IgGl, and IgG2a) levels and Th1-type (IFN-γ and IL-12) and Th2-type (IL-4 and IL-10) cytokines in mouse serum, survival rates, survival times, and parasite burdens were detected. In the present study, the immunostimulatory effect of Nc14-3-3 was confirmed, as it triggered Th1-type cytokine (IFN-γ and IL-12) production in mouse serum 2 weeks after the final immunization. Moreover, the immunization of C57BL/6 mice with Nc14-3-3 induced high IgG antibody levels and significant increases in CD8⁺ T lymphocytes in the spleens of mice, indicating that the cellular immune response was significantly stimulated. Mouse survival rates and times were significantly prolonged after immunization; the survival rates were 40% for Nc14-3-3 immunization and 60% for NEV immunization, while mice that received GST, PBS, or blank control all died at 13, 9, or 8 days, respectively, after intraperitoneal N. caninum challenge. In addition, qPCR analysis indicated that there was a reduced parasite burden and diminished pathological changes in the mice immunized with Nc14-3-3. Our data demonstrate that vaccination of mice with Nc14-3-3 elicits both cellular and humoral immune responses and provides partial protection against acute neosporosis. Thus, Nc14-3-3 could be an effective antigen candidate for vaccine development for neosporosis.

Multiparameter Flow Cytometry Analysis of the Human Spleen Applied to Studies of Plasma-Derived EVs From Plasmodium vivax Patients

The spleen is a secondary lymphoid organ with multiple functions including the removal of senescent red blood cells and the coordination of immune responses against blood-borne pathogens, such as malaria parasites. Despite the major role of the spleen, the study of its function in humans is limited by ethical implications to access human tissues. Here, we employed multiparameter flow cytometry combined with cell purification techniques to determine human spleen cell populations from transplantation donors. Spleen immuno-phenotyping showed that CD45⁺ cells included B (30%), CD4⁺ T (16%), CD8⁺ T (10%), NK (6%) and NKT (2%) lymphocytes. Myeloid cells comprised neutrophils (16%), monocytes (2%) and DCs (0.3%). Erythrocytes represented 70%, reticulocytes 0.7% and hematopoietic stem cells 0.02%. Extracellular vesicles (EVs) are membrane-bound nanoparticles involved in intercellular communication and secreted by almost all cell types. EVs play several roles in malaria that range from modulation of immune responses to vascular alterations. To investigate interactions of plasma-derived EVs from Plasmodium vivax infected patients (PvEVs) with human spleen cells, we used size-exclusion chromatography (SEC) to separate EVs from the bulk of soluble plasma proteins and stained isolated EVs with fluorescent lipophilic dyes. The integrated cellular analysis of the human spleen and the methodology employed here allowed in vitro interaction studies of human spleen cells and EVs that showed an increased proportion of T cells (CD4+ 3 fold and CD8+ 4 fold), monocytes (1.51 fold), B cells (2.3 fold) and erythrocytes (3 fold) interacting with PvEVs as compared to plasma-derived EVs from healthy volunteers (hEVs). Future functional studies of these interactions can contribute to unveil pathophysiological processes involving the spleen in vivax malaria.

Extracellular Vesicles during TriTryps infection: Complexity and future challenges

The trypanosomatid pathogens Leishmania spp., Trypanosoma cruzi, and Trypanosoma brucei, currently grouped as TriTryps, have evolved through the time to overcome the upfront innate immune response and establish the infection in humans adapting many aspects of the parasite-cell host interaction. Extracellular vesicles (EVs) emerge as critical structures carrying different key molecules from parasites and target cells that interact continuously during infection. Current information regarding the structure and composition of these vesicles provide new insights into the primary role of TriTryps-EVs reviewed in this work. Expanding knowledge about these critical vesicular structures will promote advances in basic sciences and in translational applications controlling pathogenesis in the neglected tropical diseases caused by TriTryps.

Exosomes and Lung Cancer: Roles in Pathophysiology, Diagnosis and Therapeutic Applications

Lung cancer is a malignancy with a high morbidity and mortality rate, and affected patients have low survival and poor prognosis. The therapeutic approaches for the treatment of this cancer, including radiotherapy and chemotherapy, are not particularly effective partly due to late diagnosis. Therefore, the search for new diagnostic and prognostic tools is a critical issue. Novel biomarkers, such as exosomes, could be considered as potential diagnostic tools for malignancies, particularly lung cancer. Exosomes are nanovesicles, which are associated with different physiological and pathological conditions. It has been shown that these particles are released from many cells, such as cancer cells, immune cells and to some degree normal cells. Exosomes could alter the behavior of target cells through intercellular transfer of their cargo (e.g. DNA, mRNA, long non-coding RNAs, microRNAs and proteins). Thus, these vehicles may play pivotal roles in various physiological and pathological conditions. The current insights into lung cancer pathogenesis suggest that exosomes are key players in the pathogenesis of this cancer. Hence, these nanovesicles and their cargos could be used as new diagnostic, prognostic and therapeutic biomarkers in the treatment of lung cancer. Besides the diagnostic roles of exosomes, their use as drug delivery systems and as cancer vaccines is under investigation. The present review summarizes the current information on the diagnostic and pathogenic functions of exosomes in lung cancer.

Ancient Evolutionary Origin and Properties of Universally Produced Natural Exosomes Contribute to Their Therapeutic Superiority Compared to Artificial Nanoparticles

Extracellular vesicles (EVs), such as exosomes, are newly recognized fundamental, universally produced natural nanoparticles of life that are seemingly involved in all biologic processes and clinical diseases. Due to their universal involvements, understanding the nature and also the potential therapeutic uses of these nanovesicles requires innovative experimental approaches in virtually every field. Of the EV group, exosome nanovesicles and larger companion micro vesicles can mediate completely new biologic and clinical processes dependent on the intercellular transfer of proteins and most importantly selected RNAs, particularly miRNAs between donor and targeted cells to elicit epigenetic alterations inducing functional cellular changes. These recipient acceptor cells are nearby (paracrine transfers) or far away after distribution via the circulation (endocrine transfers). The major properties of such vesicles seem to have been conserved over eons, suggesting that they may have ancient evolutionary origins arising perhaps even before cells in the primordial soup from which life evolved. Their potential ancient evolutionary attributes may be responsible for the ability of some modern-day exosomes to withstand unusually harsh conditions, perhaps due to unique membrane lipid compositions. This is exemplified by ability of the maternal milk exosomes to survive passing the neonatal acid/enzyme rich stomach. It is postulated that this resistance also applies to their durable presence in phagolysosomes, thus suggesting a unique intracellular release of their contained miRNAs. A major discussed issue is the generally poorly realized superiority of these naturally evolved nanovesicles for therapies when compared to human-engineered artificial nanoparticles, e.g., for the treatment of diseases like cancers.

The role of vascular endothelium and exosomes in human protozoan parasitic diseases

The vascular endothelium is a vital component in maintaining the structure and function of blood vessels. The endothelial cells (ECs) mediate vital regulatory functions such as the proliferation of cells, permeability of various tissue membranes, and exchange of gases, thrombolysis, blood flow, and homeostasis. The vascular endothelium also regulates inflammation and immune cell trafficking, and ECs serve as a replicative niche for many bacterial, viral, and protozoan infectious diseases. Endothelial dysfunction can lead to vasodilation and pro-inflammation, which are the hallmarks of many severe diseases. Exosomes are nanoscale membrane-bound vesicles that emerge from cells and serve as important extracellular components, which facilitate communication between cells and maintain homeostasis during normal and pathophysiological states. Exosomes are also involved in gene transfer, inflammation and antigen presentation, and mediation of the immune response during pathogenic states. Protozoa are a diverse group of unicellular organisms that cause many infectious diseases in humans. In this regard, it is becoming increasingly evident that many protozoan parasites (such as Plasmodium, Trypanosoma, Leishmania, and Toxoplasma) utilize exosomes for the transfer of their virulence factors and effector molecules into the host cells, which manipulate the host gene expression, immune responses, and other biological activities to establish and modulate infection. In this review, we discuss the role of the vascular endothelium and exosomes in and their contribution to pathogenesis in malaria, African sleeping sickness, Chagas disease, and leishmaniasis and toxoplasmosis with an emphasis on their actions on the innate and adaptive immune mechanisms of resistance.

Necroptotic extracellular vesicles - present and future

Necroptosis is a receptor-interacting protein kinase 3 (RIPK3)-/mixed lineage kinase domain-like(MLKL)-dependent and caspase-independent form of cell death that promotes inflammation. We, and others, have recently shown that necroptotic cells release extracellular vesicles (EVs). This finding has highlighted that the impact of necroptosis extends well beyond its cell death function. In this review, we summarize the general characteristics, biogenesis, and function of EVs, as well as their role in cancer. In addition, we outline our current knowledge regarding necroptotic EVs, including their recently discovered and analyzed proteome. We examine the accumulating evidence for a role for necroptosis in anti-tumor immunity. Finally, we suggest that necroptotic EVs play an important role in the necroptosis-induced immune response and may, therefore, be exploited in cancer immunotherapy applications.

Extracellular vesicles: new targets for vaccines against helminth parasites

The hunt for effective vaccines against the major helminth diseases of humans has yet to bear fruit despite much effort over several decades. No individual parasite antigen has proved to elicit full protective immunity, suggesting that combinatorial strategies may be required. Recently it has been discovered that extracellular vesicles released by parasitic helminths contain multiple potential immune modulators, which could together be targeted by a future vaccine. Increasing knowledge of helminth extracellular vesicle components, both enclosed by and exposed on the membrane, will open up a new field of targets for an effective vaccine. This review discusses the interactions between helminth extracellular vesicles and the immune system discovered thus far, and the advantages of targeting these lipid-bound packages with a vaccine. In addition, we also comment upon specific antigens that may be the best targets for an anti-helminth vaccine. In the future, extensive knowledge of the parasites' full arsenal in controlling their host may finally provide us with the ideal target for a fully effective vaccine.

Dendritic cells release exosomes together with phagocytosed pathogen; potential implications for the role of exosomes in antigen presentation

Dendritic cells (DC) have the unique capacity to activate naïve T cells by presenting T cell receptor specific peptides from exogenously acquired antigens bound to Major Histocompatibility Complex (MHC) molecules. MHC molecules are displayed on the DC plasma membrane as well as on extracellular vesicles (EV) that are released by DC, and both have antigen-presenting capacities. However, the physiological role of antigen presentation by EV is still unclear. We here demonstrate that the release of small EV by activated DC is strongly stimulated by phagocytic events. We show that, concomitant with the enhanced release of EV, a significant proportion of phagocytosed bacteria was expulsed back into the medium. High-resolution fluorescence microscopic images revealed that bacteria in phagosomes were surrounded by EV marker-proteins. Moreover, expulsed bacteria were often found associated with clustered HLA II and CD63. Together, these observations suggest that exosomes may be formed by the inward budding into phagosomes, whereupon they are secreted together with the phagosomal content. These findings may have important implications for selective loading of peptides derived from phagocytosed pathogens onto exosome associated HLA molecules, and have important implications for vaccine design.

Selectively-Packaged Proteins in Breast Cancer Extracellular Vesicles Involved in Metastasis

Cancer-derived extracellular vesicles are known to play a role in the progression of the disease. In this rapidly-growing field, there are many reports of phenotypic changes in cells following exposure to cancer-derived extracellular vesicles. This study examines the protein contents of vesicles derived from three well-known breast cancer cell lines, MCF-7, MDA-MB-231 and T47D, using peptide-centric LC-MS/MS and cytokine multiplex immunoassay analysis to understand the molecular basis of these changes. Through these techniques a large number of proteins within these vesicles were identified. A large proportion of these proteins are known to be important in cancer formation and progression and associated with cancer signaling, angiogenesis, metastasis and invasion and immune regulation. This highlights the importance of extracellular vesicles (EVs) in cancer communications and shows some of the mechanisms the vesicles use to assist in cancer progression.

Human extracellular vesicles and correlation with two clinical forms of toxoplasmosis

Aim

This study analyzed microvesicles and exosomes, called as extracellular vesicles (EVs) excreted in serum and cerebrospinal fluid (CSF) from patients with cerebral or gestational toxoplasmosis.

Methods

Clinical samples from 83 individuals were divided into four groups. Group I, 20 sera from healthy individuals and pregnant women (seronegative for toxoplasmosis); group II, 21 sera from seropositive patients for toxoplasmosis (cerebral or gestational forms); group III, 26 CSF samples from patients with cerebral toxoplasmosis/HIV co-infection (CT/HIV) (seropositive for toxoplasmosis); and group IV, 16 CSF samples from seronegative patients for toxoplasmosis, but with HIV infection and other opportunistic infections (OI/HIV). Serum and CSF samples were ultracentrifuged to recover EVs. Next, vesicle size and concentration were characterized by Nanoparticle Tracking Analysis (NTA).

Results

Concentrations of serum-derived EVs from toxoplasmosis patients (mean: 2.4 x 10¹⁰ EVs/mL) were statically higher than of non-infected individuals (mean: 5.9 x 10⁹ EVs/mL). Concentrations of CSF-derived EVs were almost similar in both groups. CT/HIV (mean: 2.9 x 10⁹ EVs/mL) and OI/HIV (mean: 4.8 x 10⁹ EVs/mL). Analyses by NTA confirmed that CSF-derived EVs and serum-derived EVs had size and shape similar to microvesicles and exosomes. The mean size of EVs was similar in serum and CSF. Thus, the concentration, and not size was able distinguish patients with toxoplasmosis than healthy individuals. Presence of exosomes was also confirmed by transmission electron microscopy and evidence of tetraspanins CD63 and CD9 in immunoblotting. Relative expressions of miR-146a-5p, miR-155-5p, miR-21-5p, miR-29c-3p and miR-125b-5p were estimated in exosomal miRNA extracted of EVs.

Serum-derived EVs from group II (cerebral and gestational toxoplasmosis) up-expressed miR-125b-5p and miR-146a-5p. CSF-derived EVs from CT/HIV patients) up-expressed miR-155-5p and miR-21-5p and were unable to express miR-29c-3p.

Conclusion

These data suggest the participation of EVs and exosomal miRNAs in unbalance of immune response as elevation of TNF-α, IL-6; and downregulation of IFN-γ in cerebral and gestational forms of toxoplasmosis.

Purity Determines the Effect of Extracellular Vesicles Derived from Mesenchymal Stromal Cells

Extracellular vesicles (EVs) have been recently identified as vital components of cell-based therapies based on the observation that conditioned media from cultured stromal cells reproduce some of the beneficial effects of intact cells. In order to obtain clinically active EVs derived from Mesenchymal Stromal Cells (MSCs) different procedures have been reported in the literature. Usually, non-confluent cells are incubated with culture medium for 48 h either with EV-depleted Fetal Bovine Serum (FBS) or without FBS. Our aim was to compare the effects of EVs isolated by ultracentrifugation from human umbilical cord MSC conditioned media obtained using these two conditions: with EV-depleted FBS (UC) or without FBS (UC_w/o) on the mRNA expression levels of extracellular matrix related genes using the mouse chondrogenic cell line ATDC-5. We observed a deleterious effect on chondrogenic cells treated with UC_w/o, showing higher mRNA expression levels of different metalloproteinases and decorin (Dcn) and lower collagen (Col1a1 and Col2a1) and aggrecan (Acan) mRNA levels. To elucidate whether this deleterious effect was induced by the EVs or by any proteins co-purified in the EV pellet, we used size exclusion chromatography (SEC) to further purify the EV pellet, obtaining an EV enriched fraction (EV or EV_w/o) and a protein enriched fraction (Prot or Prot_w/o). Our results pointed that the negative effect on the chondrogenic cell line was due to the contaminant proteins coisolated with the EVs by ultracentrifugation and not from the EVs themselves. Thus, these results highlight the importance of working with well purified EV preparations to specifically achieve their therapeutic effect.

The potential of exosomes as theragnostics in various clinical situations

Exosomes are membrane-bound cargo measuring 30–140 nm comprised of a lipid bilayer containing various proteins, RNAs, DNAs, and bioactive lipids that can be transferred between cells. They have been shown to be produced and released by many different types of healthy and diseased cells. Exosomes are secreted by all types of cells in culture, and are also found in various body fluids including blood, saliva, urine, and breast milk. Exosomes are essential for healthy physiological as well as pathological processes. In addition to their normal function, exosomes are involved in the development and progression of various diseases, potentiating cellular stress and damage. Pathogens take advantage of exosome release from infected host cells by manipulating host-derived exosomes to evade the immune system responses. Exosomes are involved in other pathological conditions such as neurodegenerative diseases, liver diseases, heart failure, cancer, diabetes, kidney diseases, osteoporosis and atherosclerotic cardiovascular disease. Hence, we can exploit exosomes as biomarkers and vaccines and modify them rationally for therapeutic interventions including tissue engineering. Further studies on exosomes will explore their potential and provide new methodology for effective clinical diagnostics and therapeutic strategies: such uses can be called exosome theragnostics. This chapter reviews the potential theragnostic (diagnostic and therapeutic) application of exosomes in major organ systems in clinical fields.

Research progress on the composition and function of parasite-derived exosomes

Parasites use excretory-secretory pathways to communicate with the host. Characterization of exosomes within the excretory-secretory products reveal by which parasites manipulate their hosts. Parasite derived exosomes provide a mechanistic framework for protein and miRNAs transfer. Transcriptomics and proteomics of parasite exosomes identified a large number of miRNAs and proteins being utilized by parasites in their survival, reproduction and development. Characterization of proteins and miRNAs in parasite secreted exosomes provide important information on host-parasite communication and forms the basis for future studies. In this review, we summarize recent advances in isolation and molecular characterization (protein and miRNAs) of parasite derived exosomes.

Extracellular Vesicle-Mediated Communication Within Host-Parasite Interactions

Extracellular vesicles (EVs) are small membrane-surrounded structures released by different kinds of cells (normal, diseased, and transformed cells) in vivo and in vitro that contain large amounts of important substances (such as lipids, proteins, metabolites, DNA, RNA, and non-coding RNA (ncRNA), including miRNA, lncRNA, tRNA, rRNA, snoRNA, and scaRNA) in an evolutionarily conserved manner. EVs, including exosomes, play a role in the transmission of information, and substances between cells that is increasingly being recognized as important. In some infectious diseases such as parasitic diseases, EVs have emerged as a ubiquitous mechanism for mediating communication during host-parasite interactions. EVs can enable multiple modes to transfer virulence factors and effector molecules from parasites to hosts, thereby regulating host gene expression, and immune responses and, consequently, mediating the pathogenic process, which has made us rethink our understanding of the host-parasite interface. Thus, here, we review the present findings regarding EVs (especially exosomes) and recognize the role of EVs in host-parasite interactions. We hope that a better understanding of the mechanisms of parasite-derived EVs may provide new insights for further diagnostic biomarker, vaccine, and therapeutic development.

A new level of complexity in parasite-host interaction: The role of extracellular vesicles

Humans and animals have co-existed with parasites in a battle of constant adaptation to one another. It is becoming increasingly clear that extracellular vesicles (EVs) play important roles in this co-existence and pathology. This chapter reviews the current research on EVs released by protozoa, nematodes, trematodes, and cestodes with a special focus on EVs in parasite life cycles. The environmental changes experienced by the parasite during its life cycle is associated with distinct changes in EV release and content. The function of these EV seems to have a significant influence on parasite pathology and survival in the host by concomitantly modulating host immune responses and triggering parasite differentiation. The role of EVs in communication between the parasites and the host adds a new level of complexity in our understanding of parasite biology, which may be a key to further understand the complexity behind host-parasite interactions and communication. This increased understanding can, in turn, open up new avenues for vaccine, diagnostic, and therapeutic development for a wide variety of diseases such as parasite infection, cancers, and immunological disorders.