Exosomes in Human Immunodeficiency Virus Type I Pathogenesis: Threat or Opportunity?

Exosomes multifunctional roles in HIV-1: insight into the immune regulation, vaccine development and current progress in delivery system

Human Immunodeficiency Virus (HIV-1) is known to establish a persistent latent infection. The use of combination antiretroviral therapy (cART) can effectively reduce the viral load, but the treatment can be costly and may lead to the development of drug resistance and life-shortening side effects. It is important to develop an ideal and safer in vivo target therapy that will effectively block viral replication and expression in the body. Exosomes have recently emerged as a promising drug delivery vehicle due to their low immunogenicity, nanoscale size (30-150nm), high biocompatibility, and stability in the targeted area. Exosomes, which are genetically produced by different types of cells such as dendritic cells, neurons, T and B cells, epithelial cells, tumor cells, and mast cells, are designed for efficient delivery to targeted cells. In this article, we review and highlight recent developments in the strategy and application of exosome-based HIV-1 vaccines. We also discuss the use of exosome-based antigen delivery systems in vaccine development. HIV-1 antigen can be loaded into exosomes, and this modified cargo can be delivered to target cells or tissues through different loading approaches. This review also discusses the immunological prospects of exosomes and their role as biomarkers in disease progression. However, there are significant administrative and technological obstacles that need to be overcome to fully harness the potential of exosome drug delivery systems.

[Exosomes in the life cycle of viruses and the pathogenesis of viral infections]

Exosomes are extracellular vesicles of endosomal origin, with a bilayer membrane, 30160 nm in diameter. Exosomes are released from cells of different origins and are detected in various body fluids. They contain nucleic acids, proteins, lipids, metabolites and can transfer the contents to recipient cells. Exosome biogenesis involves cellular proteins of the Rab GTPase family and the ESCRT system, which regulate budding, vesicle transport, molecule sorting, membrane fusion, formation of multivesicular bodies and exosome secretion. Exosomes are released from cells infected with viruses and may contain viral DNA and RNA, as well as mRNA, microRNA, other types of RNA, proteins and virions. Exosomes are capable of transferring viral components into uninfected cells of various organs and tissues. This review analyzes the impact of exosomes on the life cycle of widespread viruses that cause serious human diseases: human immunodeficiency virus (HIV-1), hepatitis B virus, hepatitis C virus, SARS-CoV-2. Viruses are able to enter cells by endocytosis, use molecular and cellular pathways involving Rab and ESCRT proteins to release exosomes and spread viral infections. It has been shown that exosomes can have multidirectional effects on the pathogenesis of viral infections, suppressing or enhancing the course of diseases. Exosomes can potentially be used in noninvasive diagnostics as biomarkers of the stage of infection, and exosomes loaded with biomolecules and drugs - as therapeutic agents. Genetically modified exosomes are promising candidates for new antiviral vaccines.

Treatment Advances in EBV Related Lymphoproliferative Diseases

Epstein Barr virus (EBV) can affect 90% of the human population. It can invade B lymphocytes, T lymphocytes and natural killer cells of the host and remain in the host for life. The long latency and reactivation of EBV can cause malignant transformation, leading to various lymphoproliferative diseases (LPDs), including EBV-related B-cell lymphoproliferative diseases (EBV-B-LPDs) (for example, Burkitt lymphoma (BL), classic Hodgkin's lymphoma (cHL), and posttransplantation and HIV-related lymphoproliferative diseases) and EBV-related T-cell lymphoproliferative diseases (EBV-T/NK-LPDs) (for example, extranodal nasal type natural killer/T-cell lymphoma (ENKTCL), aggressive NK cell leukaemia (ANKL), and peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). EBV-LPDs are heterogeneous with different clinical features and prognoses. The treatment of EBV-LPDs is usually similar to that of EBV-negative lymphoma with the same histology and can include chemotherapy, radiotherapy, and hematopoietic stem cell transplant (HSCT). However, problems such as serious toxicity and drug resistance worsen the survival prognosis of patients. EBV expresses a variety of viral and lytic proteins that regulate cell cycle and death processes and promote the survival of tumour cells. Based on these characteristics, a series of treatment strategies for EBV in related malignant tumours have been developed, such as monoclonal antibodies, immune checkpoint inhibitors, cytotoxic T lymphocytes (CTLs) and epigenetic therapy. These new individualized therapies can produce highly specific killing effects on tumour cells, and nontumour cells can be protected from toxicity. This paper will focus on the latest progress in the treatment of EBV-LPDs based on pathological mechanisms.

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.

Velocity Gradient Separation Reveals a New Extracellular Vesicle Population Enriched in miR-155 and Mitochondrial DNA

Extracellular vesicles (EVs) and their contents (proteins, lipids, messenger RNA, microRNA, and DNA) are viewed as intercellular signals, cell-transforming agents, and shelters for viruses that allow both diagnostic and therapeutic interventions. EVs circulating in the blood of individuals infected with human immunodeficiency virus (HIV-1) may provide insights into pathogenesis, inflammation, and disease progression. However, distinguishing plasma membrane EVs from exosomes, exomeres, apoptotic bodies, virions, and contaminating proteins remains challenging. We aimed at comparing sucrose and iodixanol density and velocity gradients along with commercial kits as a means of separating EVs from HIV particles and contaminating protein like calprotectin; and thereby evaluating the suitability of current plasma EVs analysis techniques for identifying new biomarkers of HIV-1 immune activation. Multiple analysis have been performed on HIV-1 infected cell lines, plasma from HIV-1 patients, or plasma from HIV-negative individuals spiked with HIV-1. Commercial kits, the differential centrifugation and density or velocity gradients to precipitate and separate HIV, EVs, and proteins such as calprotectin, have been used. EVs, virions, and contaminating proteins were characterized using Western blot, ELISA, RT-PCR, hydrodynamic size measurement, and enzymatic assay. Conversely to iodixanol density or velocity gradient, protein and virions co-sedimented in the same fractions of the sucrose density gradient than AChE-positive EVs. Iodixanol velocity gradient provided the optimal separation of EVs from viruses and free proteins in culture supernatants and plasma samples from a person living with HIV (PLWH) or a control and revealed a new population of large EVs enriched in microRNA miR-155 and mitochondrial DNA. Although EVs and their contents provide helpful information about several key events in HIV-1 pathogenesis, their purification and extensive characterization by velocity gradient must be investigated thoroughly before further use as biomarkers. By revealing a new population of EVs enriched in miR-155 and mitochondrial DNA, this study paves a way to increase our understanding of HIV-1 pathogenesis.

Extracellular vesicles and leishmaniasis: Current knowledge and promising avenues for future development

Extracellular vesicles (EVs) are small, membrane-bound "delivery trucks" that are present in the extracellular environment, including biological fluids. EVs are capable of inducing changes in the physiological status of neighboring cells through the transfer of key macromolecules, and are thought to play a role in a number of pathological processes. Leishmaniasis, caused by the protozoan parasite Leishmania, is an important example. The biology of Leishmania EVs has been studied in detail, and findings point to their role in exacerbation of disease and potential involvement in the perpetuation of drug resistance. Furthermore, the use of EVs for development of vaccines has been explored, as well as their potential use in a number of fields as biomarkers of disease and drug resistance. Here we discuss the latest findings on EVs, with a particular focus on Leishmania, as well as potential avenues for their future development and clinical applications.

Recent Progress on Exosomes in RNA Virus Infection

Recent research indicates that most tissue and cell types can secrete and release membrane-enclosed small vesicles, known as exosomes, whose content reflects the physiological/pathological state of the cells from which they originate. These exosomes participate in the communication and cell-to-cell transfer of biologically active proteins, lipids, and nucleic acids. Studies of RNA viruses have demonstrated that exosomes release regulatory factors from infected cells and deliver other functional host genetic elements to neighboring cells, and these functions are involved in the infection process and modulate the cellular responses. This review provides an overview of the biogenesis, composition, and some of the most striking functions of exosome secretion and identifies physiological/pathological areas in need of further research. While initial indications suggest that exosome-mediated pathways operate in vivo, the exosome mechanisms involved in the related effects still need to be clarified. The current review focuses on the role of exosomes in RNA virus infections, with an emphasis on the potential contributions of exosomes to pathogenesis.

The role of tumor-isolated exosomes on suppression of immune reactions and cancer progression: A systematic review

Background: Exosomes are extracellular cells (EVs) emancipated by various cell types and are involved in cell-to-cell transmission. In cancer diseases, exosomes emerge as local and systemic cells to cell mediators of oncogenic information and play a significant role in the advancement of cancer through the horizontal transfer of various molecules, such as proteins and miRNAs.

Methods: In this study, 66 articles from PubMed, MEDLINE, Science Direct, Cochrane, EMBASE, and Scopus were used as English sources.

Results: The biological distribution of cancer cell-derived exosomes in tumor tissue is an important factor in detecting their role in tumor increase; on the other hand, a limited number of studies have examined the biodistribution of exosomes in tumor tissues. While exosomes function as cancer biomarkers and support cancer treatment, we have a long way to improve the antitumor treatment of exosomes and develop exosome-based cancer diagnostic and therapeutic strategies.

Conclusion: This review describes the science and significance of cancer pathogenesis and exosomes relative to cancer treatment resistance.

Leishmania Viannia guyanensis, LRV1 virus and extracellular vesicles: a dangerous trio influencing the faith of immune response during muco-cutaneous leishmaniasis

Parasites of Leishmania genus have developed various strategies to overcome host immune response favoring its infection and development toward leishmaniasis. With an array of virulence factors, those parasites modify host macrophage signaling and functions. Depending of the species involved, visceral or cutaneous leishmaniasis will develop. Several years ago, Leishmania Viannia guyanensis that is naturally infected with the endosymbiotic virus Leishmania RNA Virus 1 was found to cause a particularly aggressive form of South-American mucocutaneous leishmaniasis. This virus, when co-transmitted with the parasite was shown to strongly modulate RNA sensors and NLRP3 inflammasome network that could explain in part the exacerbated skin pathology caused by this particular parasite. In this review, we will be discussing how this endosymbiotic virus-infected Leishmania in conjunction with Leishmania exosomes partner together to manipulate host immune response in their favor.

Exosomal miR-145-5p derived from orthohantavirus-infected endothelial cells inhibits HTNV infection

Human infection of orthohantavirus can cause potentially fatal diseases, such as hemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus (HTNV) in Eurasia. Exosomes are new carriers for information exchange between cells. Cumulative findings suggest that exosomes released from parental infected cells can block or promote viral infection in recipient cells, but the role of exosomes in hantavirus infection is poorly understood. In our study, we identified the exosomes derived from HTNV-infected human vascular endothelial cells (HUVECs) (Exo-HV) and found the antiviral properties of Exo-HV in the uninfected recipient cells. High-throughput sequencing revealed the distinctly expressed miRNAs transcriptomes in Exo-HV. MiR-145-5p, one of the abundant miRNAs packaged into Exo-HV, was found to be able to transferred to recipient cells and functioned by directly targeting M RNA of HTNV 76-118 and inducing type I interferon (IFN-I) response, thus, blocking the viral replication. Concluding, this study indicated that exosomes released by HTNV-infected HUVECs were able to transfer active molecules, miR-145-5p as a proving sample, to mediate novel anti-HTNV activity in the neighboring uninfected cells, which will help us to explore new strategies for the treatment of infectious disease utilizing exosomes with miRNA.

Shedding Light on the Role of Extracellular Vesicles in HIV Infection and Wound Healing

Extracellular vesicles (EVs) play an important role in intercellular communication. They are naturally released from cells into the extracellular environment. Based on their biogenesis, release pathways, size, content, and function, EVs are classified into exosomes, microvesicles (MVs), and apoptotic bodies (ApoBDs). Previous research has documented that EVs, specifically exosomes and MVs, play an important role in HIV infection, either by promoting HIV infection and pathogenesis or by inhibiting HIV-1 to a certain extent. We have also previously reported that EVs (particularly exosomes) from vaginal fluids inhibit HIV at the post-entry step (i.e., reverse transcription, integration). Besides the role that EVs play in HIV, they are also known to regulate the process of wound healing by regulating both the immune and inflammatory responses. It is noted that during the advanced stages of HIV infection, patients are at greater risk of wound-healing and wound-related complications. Despite ongoing research, the data on the actual effects of EVs in HIV infection and wound healing are still premature. This review aimed to update the current knowledge about the roles of EVs in regulating HIV pathogenesis and wound healing. Additionally, we highlighted several avenues of EV involvement in the process of wound healing, including coagulation, inflammation, proliferation, and extracellular matrix remodeling. Understanding the role of EVs in HIV infection and wound healing could significantly contribute to the development of new and potent antiviral therapeutic strategies and approaches to resolve impaired wounds in HIV patients.

MicroRNAs and exosomes: key players in HIV pathogenesis

OBJECTIVES

HIV infection is well known to cause impairment of the human immune system, and until recently was a leading cause of death. It has been shown that T lymphocytes are the main targets of HIV. The virus inactivates T lymphocytes by interfering with a wide range of cellular and molecular targets, leading to suppression of the immune system. The objective of this review is to investigate to what extent microRNAs (miRNAs) are involved in HIV pathogenesis.

METHODS

The scientific literature (Pubmed and Google scholar) for the period 1988-2019 was searched.

RESULTS

Mounting evidence has revealed that miRNAs are involved in viral replication and immune response, whether by direct targeting of viral transcripts or through indirect modulation of virus-related host pathways. In addition, exosomes have been found to act as nanoscale carriers involved in HIV pathogenesis. These nanovehicles target their cargos (i.e. DNA, RNA, viral proteins and miRNAs) leading to alteration of the behaviour of recipient cells.

CONCLUSIONS

miRNAs and exosomes are important players in HIV pathogenesis. Additionally, there are potential diagnostic applications of miRNAs as biomarkers in HIV infection.

Macrophages exposed to HIV viral protein disrupt lung epithelial cell integrity and mitochondrial bioenergetics via exosomal microRNA shuttling

Antiretroviral therapy extends survival but does not eliminate HIV from its cellular reservoirs. Between immune and stromal cells in the tissue microenvironment, a dynamic intercellular communication might influence host viral immune responses via intercellular transfer of extracellular vehicles (EVs) (microvesicles, exosome, or apoptotic bodies). It is increasingly recognized that HIV-infected macrophage-secreted nucleotide-rich exosomes might play a critical role in mediating communication between macrophages and other structural cells; however, molecular mechanisms underlying cell–cell crosstalk remain unknown. Here we show that HIV-1-infected macrophages and HIV-1 proteins Tat or gp120-treated macrophages express high levels of microRNAs, including miR-23a and miR-27a. Identical miRNAs expression patterns were detected in macrophage-secreted exosomes isolated from bronchoalveolar lavage fluid of HIV transgenic rats. Tat-treated macrophage-derived exosomal miR-23a attenuated posttranscriptional modulation of key tight junction protein zonula occludens (ZO-1) 3′-UTR in epithelial cells. In parallel, exosomal miR-27a released from Tat-treated macrophages altered the mitochondrial bioenergetics of recipient lung epithelial cells by targeting peroxisome proliferator-activated receptor gamma (PPARγ), while simultaneously stimulating glycolysis. Together, exosomal miRNAs shuttle from macrophages to epithelial cells and thereby explain in part HIV-mediated lung epithelial barrier dysfunction. These studies suggest that targeting miRNAs may be of therapeutic value to enhance lung health in HIV.

Seminal exosomes and HIV-1 transmission

Exosomes are endosomal‐derived membrane‐confined nanovesicles secreted by many (if not all) cell types and isolated from every human bodily fluid examined up to now including plasma, semen, vaginal secretions and breast milk. Exosomes are thought to represent a new player in cell‐to‐cell communication pathways and immune regulation, and be involved in many physiological and pathological processes. Susceptibility to HIV‐1 infection can be impacted by exosomes, while HIV‐1 pathogenesis can alter exosomal function and composition. Exosomes isolated from semen and vaginal fluid of healthy individuals can inhibit HIV‐1 infection and/or potently block viral transfer in vitro. However, the role of exosomes in HIV‐1 transmission and progression is not fully understood yet and some studies show conflicting results, mainly for exosomes isolated from plasma and breast milk. Determining the composition of exosomes from infected donors and studying their interaction with HIV‐1 in vitro compared to exosomes isolated from uninfected donors will provide insights into the role exosomes play in HIV‐1 transmission during sexual intercourse and breastfeeding.

Modulation of Host-Pathogen Communication by Extracellular Vesicles (EVs) of the Protozoan Parasite Leishmania

Leishmania genus protozoan parasites have developed various strategies to overcome host cell protective mechanisms favoring their survival and propagation. Recent findings in the field propose a new player in this infectious strategy, the Leishmania exosomes. Exosomes are eukaryotic extracellular vesicles essential to cell communication in various biological contexts. In fact, there have been an increasing number of reports over the last 10 years regarding the role of protozoan parasite exosomes, Leishmania exosomes included, in their capacity to favor infection and propagation within their hosts. In this review, we will discuss the latest findings regarding Leishmania exosome function during infectious conditions with a strong focus on Leishmania-host interaction from a mammalian perspective. We also compare the immunomodulatory properties of Leishmania exosomes to other parasite exosomes, demonstrating the conserved, important role that exosomes play during parasite infection.

Ras and exosome signaling

Ras gene (HRAS, NRAS, and KRAS) has been observed to be mutated and hyper-activated in a significant proportion of cancers. However, mutant Ras remains a challenging therapeutic target. Similarly, inhibition of targets upstream and downstream of Ras has shown limited clinical utility. There have been attempts to develop and deliver mutant K-Ras silencing RNAs either through their encapsulation in liposomes or nanoparticles. However, these approaches show very limited success due to the lack of stability of such carrier molecules alongside associated toxicity. There is a pressing need for the identification of better therapeutic targets for Ras or its associated pathways as well as improvements in the design of superior RNAi delivery systems to suppress mutant K-Ras. More than a decade ago, it was shown that aggregates of palmitoylated Ras isoforms (H-Ras and N-Ras) passage through the cytosol on rapidly moving nanosized particles ("rasosomes"). Fast forward a decade, considerable new knowledge has emerged in the area of small vesicles, microparticles, and exosomes. Exosomes are tiny vesicles and play a significant role in regulating cancer-related signaling pathways. Exosomes have also been studied as delivery vehicles to transport drugs, proteins, and microRNAs of choice for therapeutic purposes. K-Ras pathway proteins have been implicated in exosome biogenesis and extravasation processes. This review provides an update on the current knowledge related to K-Ras signaling and exosomes and also discusses how these tiny vesicles can be harnessed to successfully deliver the K-Ras silencing moieties.

Vehicles of intercellular communication: exosomes and HIV-1

The terms extracellular vesicles, microvesicles, oncosomes, or exosomes are often used interchangeably as descriptors of particles that are released from cells and comprise a lipid membrane that encapsulates nucleic acids and proteins. Although these entities are defined based on a specific size range and/or mechanism of release, the terminology is often ambiguous. Nevertheless, these vesicles are increasingly recognized as important modulators of intercellular communication. The generic characterization of extracellular vesicles could also be used as a descriptor of enveloped viruses, highlighting the fact that extracellular vesicles and enveloped viruses are similar in both composition and function. Their high degree of similarity makes differentiating between vesicles and enveloped viruses in biological specimens particularly difficult. Because viral particles and extracellular vesicles are produced simultaneously in infected cells, it is necessary to separate these populations to understand their independent functions. We summarize current understanding of the similarities and differences of extracellular vesicles, which henceforth we will refer to as exosomes, and the enveloped retrovirus, HIV-1. Here, we focus on the presence of these particles in semen, as these are of particular importance during HIV-1 sexual transmission. While there is overlap in the terminology and physical qualities between HIV-1 virions and exosomes, these two types of intercellular vehicles may differ depending on the bio-fluid source. Recent data have demonstrated that exosomes from human semen serve as regulators of HIV-1 infection that may contribute to the remarkably low risk of infection per sexual exposure.

Cytokine profiling of exosomes derived from the plasma of HIV-infected alcohol drinkers and cigarette smokers

Cytokines and chemokines circulate in plasma and may be transferred to distant sites, via exosomes. HIV infection is associated with dysregulation of cytokines and chemokines, which subsequently contribute to the pathogenesis of HIV. Alcohol and tobacco exposure, which are prevalent in HIV-infected individuals, may induce changes in the expression of cytokines and chemokines. Therefore, our aim in this study was to quantify plasma exosomal cytokines and chemokines that we expect to exacerbate toxicity or disease progression in HIV-positive drug abusers. We measured the levels of cytokines and chemokines in the plasma and plasma exosomes of 39 patients comprising six groups: HIV-negative and HIV-positive non drug abusers, HIV-negative and HIV-positive alcohol users, and HIV-negative and HIV positive tobacco smokers. We measured six cytokines (TNF-α, IL-1β, IL-8, IL-6, IL-1ra, IL-10) and two chemokines (MCP-1 and RANTES). All were present in exosomes of healthy subjects, but their levels varied between different study groups. HIV-positive alcohol drinkers had higher levels of plasma IL-8 compared to those of HIV-positive non-drinkers. The IL-1ra level was significantly higher in exosomes of non-HIV-infected alcohol drinkers compared to those of HIV-positive alcohol drinkers. Interestingly, the IL-10 level was higher in exosomes compared with their respective plasma levels in all study groups except HIV-positive non-alcohol drinkers. IL-10 was completely packaged in exosomes of HIV-positive smokers. HIV-positive smokers had significantly higher levels of plasma IL-8 compared with HIV-positive non-smokers and significantly higher exosomal IL-6 levels compared with HIV-negative subjects. HIV-positive smokers had significantly increased plasma levels of IL-1ra compared to HIV-positive non-smokers. The MCP-1 levels in the plasma of HIV-positive smokers was significantly higher than in either HIV-positive non-drug abusers or HIV-negative smokers. Overall, the findings suggest that plasma cytokines and chemokines are packaged in exosomes at varying degrees in different study groups. Exosomal cytokines and chemokines are likely to have a significant biological role at distant sites including cells in the brain.

MSC exosome works through a protein-based mechanism of action

Mesenchymal stem cell (MSC) exosome specifically defines the 50–200 nm vesicles that are secreted into the extracellular space when multivesicular bodies in the MSC fuse with the plasma membrane. However, the exosome is just one of several 50–200 nm extracellular vesicles (EVs) known to be secreted by cells. Nevertheless, the term ‘MSC exosome’ is often used to describe populations of 50–200 nm EVs that are prepared from culture medium conditioned by MSCs on the basis that these populations collectively exhibited typical exosome-associated proteins such as endosomal proteins, TSG101 and Alix, and tetraspanin proteins, CD9, CD63 and CD81. They also carry a rich diverse RNA cargo. MSC exosomes are increasingly implicated as the mediator of many of the MSC-associated therapeutic potencies. They elicit therapeutic activity by delivering their cargo of potentially therapeutic proteins and RNAs to the recipient cells. The therapeutic potency of MSC exosomes is usually rationalized on the presence of a biologically relevant protein or RNA in the MSC exosome. In the present paper, we expanded this rationale beyond a physical presence to include biologically relevant concentration, biochemical functionality and the potential to elicit an appropriate timely biochemical response. Based on these, we propose that MSC exosomes most probably work through the protein rather than the RNA.

Exosome markers associated with immune activation and oxidative stress in HIV patients on antiretroviral therapy

Exosomes are nanovesicles released from most cell types including immune cells. Prior studies suggest exosomes play a role in HIV pathogenesis, but little is known about exosome cargo in relation to immune responses and oxidative stress. Here, we characterize plasma exosomes in HIV patients and their relationship to immunological and oxidative stress markers. Plasma exosome fractions were isolated from HIV-positive subjects on ART with suppressed viral load and HIV-negative controls. Exosomes were characterized by electron microscopy, nanoparticle tracking, immunoblotting, and LC-MS/MS proteomics. Plasma exosomes were increased in HIV-positive subjects compared to controls, and correlated with increased oxidative stress markers (cystine, oxidized cys-gly) and decreased PUFA (DHA, EPA, DPA). Untargeted proteomics detected markers of exosomes (CD9, CD63, CD81), immune activation (CD14, CRP, HLA-A, HLA-B), oxidative stress (CAT, PRDX1, PRDX2, TXN), and Notch4 in plasma exosomes. Exosomal Notch4 was increased in HIV-positive subjects versus controls and correlated with immune activation markers. Treatment of THP-1 monocytic cells with patient-derived exosomes induced expression of genes related to interferon responses and immune activation. These results suggest that exosomes in ART-treated HIV patients carry proteins related to immune activation and oxidative stress, have immunomodulatory effects on myeloid cells, and may have pro-inflammatory and redox effects during pathogenesis.

Macrophage-derived extracellular vesicles mediate smooth muscle hyperplasia: role of altered miRNA cargo in response to HIV infection and substance abuse

Our previous studies consistently demonstrate enhanced pulmonary vascular remodeling in HIV–infected intravenous drug users, and in simian immunodeficiency virus–infected macaques or HIV-transgenic rats exposed to opioids or cocaine. Although we reported an associated increase in perivascular inflammation, the exact role of inflammatory cells in the development of pulmonary vascular remodeling remains unknown. In this study, HIV–infected and cocaine (H+C)–treated human monocyte derived macrophages released a higher number of extracellular vesicles (EVs), compared to HIV-infected or uninfected cocaine-treated macrophages, with a significant increase in the particle size range to 100–150 nm. Treatment of primary human pulmonary arterial smooth muscle cells (HPASMCs) with these EVs resulted in a significant increase in smooth muscle proliferation. We also observed a significant increase in the miRNA-130a level in the EVs derived from H+C-treated macrophages that corresponded with the decrease in the expression of phosphatase and tensin homolog and tuberous sclerosis 1 and 2 and activation of PI3K/protein kinase B signaling in HPASMCs on addition of these EVs. Transfection of HPASMCs with antagomir-130a–ameliorated the EV-induced effect. Thus, we conclude that EVs derived from H+C-treated macrophages promote pulmonary smooth muscle proliferation by delivery of its prosurvival miRNA cargo, which may play a crucial role in the development of PAH.—Sharma, H., Chinnappan, M., Agarwal, S., Dalvi, P., Gunewardena, S., O’Brien-Ladner, A., Dhillon, N. K. Macrophage-derived extracellular vesicles mediate smooth muscle hyperplasia: role of altered miRNA cargo in response to HIV infection and substance abuse.

Review of Current Cell-Penetrating Antibody Developments for HIV-1 Therapy

The discovery of highly active antiretroviral therapy (HAART) in 1996 has significantly reduced the global mortality and morbidity caused by the acquired immunodeficiency syndrome (AIDS). However, the therapeutic strategy of HAART that targets multiple viral proteins may render off-target toxicity and more importantly results in drug-resistant escape mutants. These have been the main challenges for HAART and refinement of this therapeutic strategy is urgently needed. Antibody-mediated treatments are emerging therapeutic modalities for various diseases. Most therapeutic antibodies have been approved by Food and Drug Administration (FDA) mainly for targeting cancers. Previous studies have also demonstrated the promising effect of therapeutic antibodies against HIV-1, but there are several limitations in this therapy, particularly when the viral targets are intracellular proteins. The conventional antibodies do not cross the cell membrane, hence, the pathogenic intracellular proteins cannot be targeted with this classical therapeutic approach. Over the years, the advancement of antibody engineering has permitted the therapeutic antibodies to comprehensively target both extra- and intra-cellular proteins in various infections and diseases. This review aims to update on the current progress in the development of antibody-based treatment against intracellular targets in HIV-1 infection. We also attempt to highlight the challenges and limitations in the development of antibody-based therapeutic modalities against HIV-1.

Pathogenic Role of Exosomes in Epstein-Barr Virus (EBV)-Associated Cancers

Exosomes are 40- to 100-nm membrane-bound small vesicles that carry a great variety of cellular cargoes including proteins, DNA, messenger RNAs (mRNAs), and microRNAs (miRNAs). These nanovesicles are detected in various biological fluids such as serum, urine, saliva, and seminal fluids. Exosomes serve as key mediators in intercellular communication by facilitating the transfer and exchange of cellular components from cells to cells. They contain various pathogenic factors whereby their adverse effects have been implicated in multiple viral infections and cancers. Interestingly, accumulating evidences showed that exosomes derived from tumour viruses or oncoviruses, exacerbate virus-associated cancers by remodelling the tumour microenvironment. In this review, we summarize the contributing factors of Epstein-Barr virus (EBV) products-containing exosomes in viral pathogenesis and their potential implications in EBV-driven malignancies. Understanding the biological role of these exosomes in the disease would undoubtedly boost the development of a more comprehensive strategy to combat EBV-associated cancers and to better predict the therapeutic outcomes. Furthermore, we also highlight the potentials and challenges of EBV products-containing exosomes being employed as diagnostic markers and therapeutic targets for EBV-related cancers. Since these aspects are rather underexplored, we attempt to underline interesting areas that warrant further investigations in the future.

Exosomes from uninfected cells activate transcription of latent HIV-1

HIV-1 infection causes AIDS, infecting millions worldwide. The virus can persist in a state of chronic infection due to its ability to become latent. We have previously shown a link between HIV-1 infection and exosome production. Specifically, we have reported that exosomes transport viral proteins and RNA from infected cells to neighboring uninfected cells. These viral products could then elicit an innate immune response, leading to activation of the Toll-like receptor and NF-κB pathways. In this study, we asked whether exosomes from uninfected cells could activate latent HIV-1 in infected cells. We observed that irrespective of combination antiretroviral therapy, both short- and long-length viral transcripts were increased in wild-type HIV-1-infected cells exposed to purified exosomes from uninfected cells. A search for a possible mechanism for this finding revealed that the exosomes increase RNA polymerase II loading onto the HIV-1 promoter in the infected cells. These viral transcripts, which include trans-activation response (TAR) RNA and a novel RNA that we termed TAR-gag, can then be packaged into exosomes and potentially be exported to neighboring uninfected cells, leading to increased cellular activation. To better decipher the exosome release pathways involved, we used siRNA to suppress expression of ESCRT (endosomal sorting complex required for transport) proteins and found that ESCRT II and IV significantly control exosome release. Collectively, these results imply that exosomes from uninfected cells activate latent HIV-1 in infected cells and that true transcriptional latency may not be possible in vivo, especially in the presence of combination antiretroviral therapy.

Exosomes carrying immunoinhibitory proteins and their role in cancer

Recent emergence of exosomes as information carriers between cells has introduced us to a new previously unknown biological communication system. Multi-directional cross-talk mediated by exosomes carrying proteins, lipids and nucleic acids between normal cells, cells harbouring a pathogen or cancer and immune cells has been instrumental in determining outcomes of physiological as well as pathological conditions. Exosomes play a key role in the broad spectrum of human diseases. In cancer, tumour-derived exosomes carry multiple immunoinhibitory signals, disable anti-tumour immune effector cells and promote tumour escape from immune control. Exosomes delivering negative signals to immune cells in cancer, viral infections, autoimmune or other diseases may interfere with therapy and influence outcome. Exosomes can activate tissue cells to produce inhibitory factors and thus can suppress the host immune responses indirectly. Exosomes also promise to be non-invasive disease biomarkers with a dual capability to provide insights into immune dysfunction as well as disease progression and outcome.

Trans-dissemination of exosomes from HIV-1-infected cells fosters both HIV-1 trans-infection in resting CD4+ T lymphocytes and reactivation of the HIV-1 reservoir

Intact HIV-1 and exosomes can be internalized by dendritic cells (DCs) through a common pathway leading to their transmission to CD4⁺ T lymphocytes by means of mechanisms defined as trans-infection and trans-dissemination, respectively. We previously reported that exosomes from HIV-1-infected cells activate both uninfected quiescent CD4⁺ T lymphocytes, which become permissive to HIV-1, and latently infected cells, with release of HIV-1 particles. However, nothing is known about the effects of trans-dissemination of exosomes produced by HIV-1-infected cells on uninfected or latently HIV-1-infected CD4⁺ T lymphocytes. Here, we report that trans-dissemination of exosomes from HIV-1-infected cells induces cell activation in resting CD4⁺ T lymphocytes, which appears stronger with mature than immature DCs. Using purified preparations of both HIV-1 and exosomes, we observed that mDC-mediated trans-dissemination of exosomes from HIV-1-infected cells to resting CD4⁺ T lymphocytes induces efficient trans-infection and HIV-1 expression in target cells. Most relevant, when both mDCs and CD4⁺ T lymphocytes were isolated from combination anti-retroviral therapy (ART)-treated HIV-1-infected patients, trans-dissemination of exosomes from HIV-1-infected cells led to HIV-1 reactivation from the viral reservoir. In sum, our data suggest a role of exosome trans-dissemination in both HIV-1 spread in the infected host and reactivation of the HIV-1 reservoir.

Recent 5-year Findings and Technological Advances in the Proteomic Study of HIV-associated Disorders

Human immunodeficiency virus-1 (HIV-1) mainly relies on host factors to complete its life cycle. Hence, it is very important to identify HIV-regulated host proteins. Proteomics is an excellent technique for this purpose because of its high throughput and sensitivity. In this review, we summarized current technological advances in proteomics, including general isobaric tags for relative and absolute quantitation (iTRAQ) and stable isotope labeling by amino acids in cell culture (SILAC), as well as subcellular proteomics and investigation of posttranslational modifications. Furthermore, we reviewed the applications of proteomics in the discovery of HIV-related diseases and HIV infection mechanisms. Proteins identified by proteomic studies might offer new avenues for the diagnosis and treatment of HIV infection and the related diseases.

The emerging roles of tumor-derived exosomes in hematological malignancies

Exosomes are small (30-150 nm) membranous vesicles of endocytic origin produced by all cells under physiological and pathological conditions. They have recently emerged as vehicles for intercellular transfer of molecular and genetic contents from parent to recipient cells. Exosome-mediated transfer of proteins or genes (RNA, miRNA, DNA) results in reprogramming of recipient cell functions. Exosomes carry and deliver information that is essential for health, and they participate in pathological events, including malignant transformation. Within the hematopoietic system, exosomes maintain crosstalk between cells located in the bone marrow compartment and at distant tissue sites. In hematological malignancies, tumor-derived exosomes (TEX) reprogram the bone marrow environment, suppress anti-leukemia immunity, mediate drug resistance and interfere with immunotherapies. TEX are also viewed as promising biomarkers of malignant progression and as potential therapeutic targets. The involvement of TEX in nearly all aspects of malignant transformation has generated much interest in their biology, mechanisms responsible for information transfer and the role they play in cancer escape from the host immune system.

Does persistent HIV replication explain continued lymphoma incidence in the era of effective antiretroviral therapy?

Non-Hodgkin lymphomas are highly increased in incidence in individuals infected with HIV, and this continues to be the case in spite of highly effective combined antiretroviral therapy (cART). New evidence has demonstrated that while successful virtual recovery of CD4 counts and elimination of HIV from peripheral blood can be achieved with cART, viral replication can still occur in lymphoid tissues. In addition, recent studies have suggested that adipose tissue provides an additional reservoir for HIV-infected macrophages and T lymphocytes even in the context of successful cART therapy. In this review article, we discuss possible mechanisms leading to the development of lymphoma in the cART era.

Leishmania exosomes and other virulence factors: Impact on innate immune response and macrophage functions

Leishmania parasites are the causative agents of the leishmaniases, a collection of vector-borne diseases that range from simple cutaneous to fatal visceral forms. Employing potent immune modulation mechanisms, Leishmania is able to render the host macrophage inactive and persist inside its phagolysosome. In the last few years, the role of exosomes in Leishmania-host interactions has been increasingly investigated. For instance, it was reported that Leishmania exosome release is augmented following temperature shift, a condition mimicking parasite's entry into its mammalian host. Leishmania exosomes were found to strongly affect macrophage cell signaling and functions, similarly to whole parasites. Importantly, these vesicles were shown to be pro-inflammatory, capable to recruit neutrophils at their inoculation site exacerbating the pathology. In this review, we provide the most recent insights on the role of exosomes and other virulence factors, especially the surface protease GP63, in Leishmania-host interactions, deepening our knowledge on leishmaniasis and paving the way for the development of new therapeutics.