Extracellular Vesicle Activation of Latent HIV-1 Is Driven by EV-Associated c-Src and Cellular SRC-1 via the PI3K/AKT/mTOR Pathway

[Exosomes' role in intercellular interactions in different variants of lung injury in fatal cases of COVID-19]

BACKGROUND

Extracellular vesicles are surrounded by a phospholipid bilayer, carrying various active biomolecules and participating in many physiological and pathological processes, including infectious ones.

OBJECTIVE

To research the role of exosomes in intercellular interactions in the pathogenesis of various types of lung damage in fatal cases of COVID-19.

MATERIAL AND METHODS

We conducted a clinical and morphological analysis of 118 fatal cases caused by coronavirus infection in Moscow. We selected 32 cases with morphological signs of various types of lung lesions for immunohistochemical reaction (IHC) with antibodies against tetraspanin proteins (CD63, CD81), which are involved in the assembly of exosomes, as well as with antibodies against viral proteins: nucleocapsid and spike protein. We determined the main producing cells of extracellular vesicles and cells containing viral proteins, carried out their comparison and quantitative analysis.

RESULTS

IHC reaction with antibodies against CD63 showed cytoplasmic granular uniform and subapical staining of cells, as well as granular extracellular staining. We determined similar staining using antibodies against viral proteins. Extracellular vesicles were found in the same cells as viral proteins. The main producing cells of vesicles and cells containing viral proteins were found to be macrophages, type II pneumocytes, and endothelial cells.

CONCLUSION

Taking into account the results of the literature, the localization of viral proteins and extracellular vesicles in the same cells indicates the key role of vesicles in the pathogenesis of various forms of lung damage by the SARS-CoV-2 virus, in the dissemination of the pathogen in the organism, which leads to interaction with the adaptive immune system and the formation of immunity.

Occludin: a gatekeeper of brain Infection by HIV-1

Compromised structure and function of the blood-brain barrier (BBB) is one of the pathological hallmarks of brain infection by HIV-1. BBB damage during HIV-1 infection has been associated with modified expression of tight junction (TJ) proteins, including occludin. Recent evidence indicated occludin as a redox-sensitive, multifunctional protein that can act as both an NADH oxidase and influence cellular metabolism through AMPK kinase. One of the newly identified functions of occludin is its involvement in regulating HIV-1 infection. Studies suggest that occludin expression levels and the rate of HIV-1 infection share a reverse, bidirectional relationship; however, the mechanisms of this relationship are unclear. In this review, we describe the pathways involved in the regulation of HIV-1 infection by occludin. We propose that occludin may serve as a potential therapeutic target to control HIV-1 infection and to improve the lives of people living with HIV-1.

The Use of CBD and Its Synthetic Analog HU308 in HIV-1-Infected Myeloid Cells

Currently, there is no cure for human immunodeficiency virus type 1 (HIV-1) infection. However, combined antiretroviral therapy (cART) aids in viral latency and prevents the progression of HIV-1 infection into acquired immunodeficiency syndrome (AIDS). cART has extended many lives, but people living with HIV-1 (PLWH) face lifelong ailments such as HIV-associated neurocognitive disorders (HAND) that range from asymptomatic HAND to HIV-1-associated dementia. HAND has been attributed to chronic inflammation and low-level infection within the central nervous system (CNS) caused by proinflammatory cytokines and viral products. These molecules are shuttled into the CNS within extracellular vesicles (EVs), lipid bound nanoparticles, and are released from cells as a form of intercellular communication. This study investigates the impact of cannabidiol (CBD), as a promising and potential therapeutic for HAND patients, and a similar synthetic molecule, HU308, on the EVs released from HIV-1-infected myeloid cells as well as HIV-1-infected 3D neurospheres. The data shows that both CBD and HU308 decrease non-coding and coding viral RNA (TAR and env) as well as proinflammatory cytokines as IL-1β and TNF-α mRNA. This decrease in viral RNA occurs in in vitro differentiated primary macrophages, in EVs released from HIV-1-infected cells monocytes, and infected neurospheres. Furthermore, a 3D neurosphere model shows an overall decrease in proinflammatory mRNA with HU308. Finally, using a humanized mouse model of HIV-1 infection, plasma viral RNA was shown to significantly decrease with HU308 alone and was most effective in combination with cART, even when compared to the typical cART treatment. Overall, CBD or HU308 may be a viable option to decrease EV release and associated cytokines which would dampen the virus spread and may be used in effective treatment of HAND in combination with cART.

The interplay among HIV, monocytes/macrophages, and extracellular vesicles: a systematic review

Despite effective antiretroviral therapies, chronic inflammation and spontaneous viral "blips" occur in HIV-infected patients. Given the roles for monocytes/macrophages in HIV pathogenesis and extracellular vesicles in intercellular communication, we performed this systematic review to delineate the triad of HIV, monocytes/macrophages, and extracellular vesicles in the modulation of immune activation and HIV activities. We searched PubMed, Web of Science, and EBSCO databases for published articles, up to 18 August 2022, relevant to this triad. The search identified 11,836 publications, and 36 studies were deemed eligible and included in this systematic review. Data were extracted for the characteristics of HIV, monocytes/macrophages, and extracellular vesicles used for experiments and the immunologic and virologic outcomes in extracellular vesicle recipient cells. Evidence for the effects on outcomes was synthesized by stratifying the characteristics by outcomes. In this triad, monocytes/macrophages were potential producers and recipients of extracellular vesicles, whose cargo repertoires and functionalities were regulated by HIV infection and cellular stimulation. Extracellular vesicles derived from HIV-infected monocytes/macrophages or the biofluid of HIV-infected patients enhanced innate immune activation and HIV dissemination, cellular entry, replication, and latency reactivation in bystander or infected target cells. These extracellular vesicles could be synthesized in the presence of antiretroviral agents and elicit pathogenic effects in a wide range of nontarget cells. At least eight functional types of extracellular vesicles could be classified based on the diverse extracellular vesicle effects, which were linked to specific virus- and/or host-derived cargos. Thus, the monocyte/macrophage-centered multidirectional crosstalk through extracellular vesicles may help sustain persistent immune activation and residual viral activities during suppressed HIV infection.

Next-generation proteomics of serum extracellular vesicles combined with single-cell RNA sequencing identifies MACROH2A1 associated with refractory COVID-19

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic is widespread; however, accurate predictors of refractory cases have not yet been established. Circulating extracellular vesicles, involved in many pathological processes, are ideal resources for biomarker exploration.

METHODS

To identify potential serum biomarkers and examine the proteins associated with the pathogenesis of refractory COVID-19, we conducted high-coverage proteomics on serum extracellular vesicles collected from 12 patients with COVID-19 at different disease severity levels and 4 healthy controls. Furthermore, single-cell RNA sequencing of peripheral blood mononuclear cells collected from 10 patients with COVID-19 and 5 healthy controls was performed.

RESULTS

Among the 3046 extracellular vesicle proteins that were identified, expression of MACROH2A1 was significantly elevated in refractory cases compared to non-refractory cases; moreover, its expression was increased according to disease severity. In single-cell RNA sequencing of peripheral blood mononuclear cells, the expression of MACROH2A1 was localized to monocytes and elevated in critical cases. Consistently, single-nucleus RNA sequencing of lung tissues revealed that MACROH2A1 was highly expressed in monocytes and macrophages and was significantly elevated in fatal COVID-19. Moreover, molecular network analysis showed that pathways such as "estrogen signaling pathway," "p160 steroid receptor coactivator (SRC) signaling pathway," and "transcriptional regulation by STAT" were enriched in the transcriptome of monocytes in the peripheral blood mononuclear cells and lungs, and they were also commonly enriched in extracellular vesicle proteomics.

CONCLUSIONS

Our findings highlight that MACROH2A1 in extracellular vesicles is a potential biomarker of refractory COVID-19 and may reflect the pathogenesis of COVID-19 in monocytes.

Role of macrophages in HIV pathogenesis and cure: NIH perspectives

Macrophages play a significant role in HIV infection and contribute to pathogenesis of comorbidities as well as establishment of the viral reservoir in people living with HIV. While CD4+ T cells are considered the main targets of HIV infection, infected macrophages resist the cytopathic effects of infection, contributing to the persistent HIV reservoir. Furthermore, activated macrophages drive inflammation and contribute to the development of comorbidities, including HIV-associated CNS dysfunction. Better understanding the role of macrophages in HIV infection, persistence, and comorbidities can lead to development of innovative therapeutic strategies to address HIV-related outcomes in people living with HIV. In October 2021, the National Institute of Mental Health and the Ragon Institute of MGH, MIT, and Harvard conducted a virtual meeting on role of macrophages in HIV infection, pathogenesis, and cure. This review article captures the key highlights from this meeting and provides an overview of interests and activities of various NIH institutes involved in supporting research on macrophages and HIV.

The Role of Extracellular Vesicles in COVID-19 Pathology

Extracellular vesicles (EVs) have become a trending topic in recent years; they constitute a new intercellular communication paradigm. Extracellular vesicles are 30–4000 nanometers in diameter particles that are limited by a phospholipid bilayer and contain functional biomolecules, such as proteins, lipids, and nucleic acids. They are released by virtually all types of eukaryotic cells; through their cargoes, EVs are capable of triggering signaling in recipient cells. In addition to their functions in the homeostatic state, EVs have gained attention because of their roles in pathological contexts, eventually contributing to disease progression. In the Coronavirus disease 2019 (COVID-19) pandemic, aside from the scientific race for the development of preventive and therapeutic interventions, it is critical to understand the pathological mechanisms involved in SARS-CoV-2 infection. In this sense, EVs are key players in the main processes of COVID-19. Thus, in this review, we highlight the role of EVs in the establishment of the viral infection and in the procoagulant state, cytokine storm, and immunoregulation of innate and adaptive immune responses.

Methamphetamine Induces the Release of Proadhesive Extracellular Vesicles and Promotes Syncytia Formation: A Potential Role in HIV-1 Neuropathogenesis

Despite the success of combinational antiretroviral therapy (cART), the high pervasiveness of human immunodeficiency virus-1 (HIV)-associated neurocognitive disorders (HAND) poses a significant challenge for society. Methamphetamine (meth) and related amphetamine compounds, which are potent psychostimulants, are among the most commonly used illicit drugs. Intriguingly, HIV-infected individuals who are meth users have a comparatively higher rate of neuropsychological impairment and exhibit a higher viral load in the brain than infected individuals who do not abuse meth. Effectively, all cell types secrete nano-sized lipid membrane vesicles, referred to as extracellular vesicles (EVs) that can function as intercellular communication to modulate the physiology and pathology of the cells. This study shows that meth treatments on chronically HIV-infected promonocytic U1 cells induce the release of EVs that promote cellular clustering and syncytia formation, a phenomenon that facilitates HIV pathogenesis. Our analysis also revealed that meth exposure increased intercellular adhesion molecule-1 (ICAM-1) and HIV-Nef protein expression in both large (10 K) and small (100 K) EVs. Further, when meth EVs are applied to uninfected naïve monocyte-derived macrophages (MDMs), we saw a significant increase in cell clustering and syncytia formation. Furthermore, treatment of MDMs with antibodies against ICAM-1 and its receptor, lymphocyte function-associated antigen 1 (LFA1), substantially blocked syncytia formation, and consequently reduced the number of multinucleated cells. In summary, our findings reveal that meth exacerbates HIV pathogenesis in the brain through release of proadhesive EVs, promoting syncytia formation and thereby aiding in the progression of HIV infection in uninfected cells.

CounterAKTing HIV: Toward a “Block and Clear” Strategy?

The protein kinase B or Akt is a central regulator of survival, metabolism, growth and proliferation of the cells and is known to be targeted by various viral pathogens, including HIV-1. The central role of Akt makes it a critical player in HIV-1 pathogenesis, notably by affecting viral entry, latency and reactivation, cell survival, viral spread and immune response to the infection. Several HIV proteins activate the PI3K/Akt pathway, to fuel the progression of the infection. Targeting Akt could help control HIV-1 entry, viral latency/replication, cell survival of infected cells, HIV spread from cell-to-cell, and the immune microenvironment which could ultimately allow to curtail the size of the HIV reservoir. Beside the “shock and kill” and “block and lock” strategies, the use of Akt inhibitors in combination with latency inducing agents, could favor the clearance of infected cells and be part of new therapeutic strategies with the goal to “block and clear” HIV.

Extracellular Vesicles as a New Promising Therapy in HIV Infection

Combination antiretroviral therapy (cART) effectively blocks HIV replication but cannot completely eliminate HIV from the body mainly due to establishment of a viral reservoir. To date, clinical strategies designed to replace cART for life and alternatively to eliminate the HIV reservoir have failed. The reduced expression of viral antigens in the latently infected cells is one of the main reasons behind the failure of the strategies to purge the HIV reservoir. This situation has forced the scientific community to search alternative therapeutic strategies to control HIV infection. In this regard, recent findings have pointed out extracellular vesicles as therapeutic agents with enormous potential to control HIV infection. This review focuses on their role as pro-viral and anti-viral factors, as well as their potential therapeutic applications.

Anti-CD81 antibody blocks vertical transmission of avian leukosis virus subgroup J

Control of ALV-J in breed of chicken is still a serious issue that need more attention to be paid. Vertical transmission of ALV-J often give rise to more adverse pathogenicity. However, the way to elimination of ALV-J underlying vertical transmission remains not-well understood. In addition, effective vaccines or drugs have not been developed to prevent and control the transmission of ALV-J so far. CD81, a member of the tetraspanins superfamily, plays important roles in regulating membrane proteins, facilitating cells adhesion or fusion, and also participates in viral infection. The purpose of this study was to investigate whether antibodies against certain tetraspanins affect infection of ALV-J. Here, we showed that anti-CD81 antibody could inhibit viral RNA and protein level. We also found that anti-CD81 antibody interacts with viral protein p27, p32 and gp37. Moreover, treatment with antibody to CD81 can effectively prevent the vertical transmission of ALV-J in animal model. Collectively, current study provides new avenues for the control of ALV-J transmission.

Akt plays differential roles during the life cycles of acute and persistent murine norovirus strains in macrophages

Akt (Protein kinase B) is a key signaling protein in eukaryotic cells that controls many cellular processes such as glucose metabolism and cell proliferation for survival. As obligate intracellular pathogens, viruses modulate host cellular processes, including Akt signaling, for optimal replication. The mechanisms by which viruses modulate Akt and the resulting effects on the infectious cycle differ widely depending on the virus. In this study, we explored the effect of Akt serine 473 phosphorylation (p-Akt) during murine norovirus (MNV) infection. p-Akt increased during infection of murine macrophages with acute MNV-1 and persistent CR3 and CR6 strains. Inhibition of Akt with MK2206, an inhibitor of all three isoforms of Akt (Akt1/2/3), reduced infectious virus progeny of all three virus strains. This reduction was due to decreased viral genome replication (CR3), defective virus assembly (MNV-1), or diminished cellular egress (CR3 and CR6) in a virus strain-dependent manner. Collectively, our data demonstrate that Akt activation increases in macrophages during the later stages of the MNV infectious cycle, which may enhance viral infection in unique ways for different virus strains. The data, for the first time, indicate a role for Akt signaling in viral assembly and highlight additional phenotypic differences between closely related MNV strains. Importance Human noroviruses (HNoV) are a leading cause of viral gastroenteritis, resulting in high annual economic burden and morbidity; yet there are no small animal models supporting productive HNoV infection, or robust culture systems producing cell culture-derived virus stocks. As a result, research on drug discovery and vaccine development against norovirus infection has been challenging, and no targeted antivirals or vaccines against HNoV are approved. On the other hand, murine norovirus (MNV) replicates to high titers in cell culture and is a convenient and widespread model in norovirus research. Our data demonstrate the importance of Akt signaling during the late stage of the MNV life cycle. Notably, the effect of Akt signaling on genome replication, virus assembly and cellular egress is virus strain specific, highlighting the diversity of biological phenotypes despite small genetic variability among norovirus strains. This study is the first to demonstrate a role for Akt in viral assembly.

HIV-1 Latency and Viral Reservoirs: Existing Reversal Approaches and Potential Technologies, Targets, and Pathways Involved in HIV Latency Studies

Eradication of latent human immunodeficiency virus (HIV) infection is a global health challenge. Reactivation of HIV latency and killing of virus-infected cells, the so-called "kick and kill" or "shock and kill" approaches, are a popular strategy for HIV cure. While antiretroviral therapy (ART) halts HIV replication by targeting multiple steps in the HIV life cycle, including viral entry, integration, replication, and production, it cannot get rid of the occult provirus incorporated into the host-cell genome. These latent proviruses are replication-competent and can rebound in cases of ART interruption or cessation. In general, a very small population of cells harbor provirus, serve as reservoirs in ART-controlled HIV subjects, and are capable of expressing little to no HIV RNA or proteins. Beyond the canonical resting memory CD4⁺ T cells, HIV reservoirs also exist within tissue macrophages, myeloid cells, brain microglial cells, gut epithelial cells, and hematopoietic stem cells (HSCs). Despite a lack of active viral production, latently HIV-infected subjects continue to exhibit aberrant cellular signaling and metabolic dysfunction, leading to minor to major cellular and systemic complications or comorbidities. These include genomic DNA damage; telomere attrition; mitochondrial dysfunction; premature aging; and lymphocytic, cardiac, renal, hepatic, or pulmonary dysfunctions. Therefore, the arcane machineries involved in HIV latency and its reversal warrant further studies to identify the cryptic mechanisms of HIV reservoir formation and clearance. In this review, we discuss several molecules and signaling pathways, some of which have dual roles in maintaining or reversing HIV latency and reservoirs, and describe some evolving strategies and possible approaches to eliminate viral reservoirs and, ultimately, cure/eradicate HIV infection.

Extracellular Vesicles in HTLV-1 Communication: The Story of an Invisible Messenger

Human T-cell lymphotropic virus type 1 (HTLV-1) infects 5-10 million people worldwide and is the causative agent of adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) as well as other inflammatory diseases. A major concern is that the most majority of individuals with HTLV-1 are asymptomatic carriers and that there is limited global attention by health care officials, setting up potential conditions for increased viral spread. HTLV-1 transmission occurs primarily through sexual intercourse, blood transfusion, intravenous drug usage, and breast feeding. Currently, there is no cure for HTLV-1 infection and only limited treatment options exist, such as class I interferons (IFN) and Zidovudine (AZT), with poor prognosis. Recently, small membrane-bound structures, known as extracellular vesicles (EVs), have received increased attention due to their potential to carry viral cargo (RNA and proteins) in multiple pathogenic infections (i.e., human immunodeficiency virus type I (HIV-1), Zika virus, and HTLV-1). In the case of HTLV-1, EVs isolated from the peripheral blood and cerebral spinal fluid (CSF) of HAM/TSP patients contained the viral transactivator protein Tax. Additionally, EVs derived from HTLV-1-infected cells (HTLV-1 EVs) promote functional effects such as cell aggregation which enhance viral spread. In this review, we present current knowledge surrounding EVs and their potential role as immune-modulating agents in cancer and other infectious diseases such as HTLV-1 and HIV-1. We discuss various features of EVs that make them prime targets for possible vehicles of future diagnostics and therapies.

Extracellular Vesicles in Viral Infections: Two Sides of the Same Coin?

Extracellular vesicles are small membrane structures containing proteins and nucleic acids that are gaining a lot of attention lately. They are produced by most cells and can be detected in several body fluids, having a huge potential in therapeutic and diagnostic approaches. EVs produced by infected cells usually have a molecular signature that is very distinct from healthy cells. For intracellular pathogens like viruses, EVs can have an even more complex function, since the viral biogenesis pathway can overlap with EV pathways in several ways, generating a continuum of particles, like naked virions, EVs containing infective viral genomes and quasi-enveloped viruses, besides the classical complete viral particles that are secreted to the extracellular space. Those particles can act in recipient cells in different ways. Besides being directly infective, they also can prime neighbor cells rendering them more susceptible to infection, block antiviral responses and deliver isolated viral molecules. On the other hand, they can trigger antiviral responses and cytokine secretion even in uninfected cells near the infection site, helping to fight the infection and protect other cells from the virus. This protective response can also backfire, when a massive inflammation facilitated by those EVs can be responsible for bad clinical outcomes. EVs can help or harm the antiviral response, and sometimes both mechanisms are observed in infections by the same virus. Since those pathways are intrinsically interlinked, understand the role of EVs during viral infections is crucial to comprehend viral mechanisms and respond better to emerging viral diseases.