HIV-1 Nef-induced cardiotoxicity through dysregulation of autophagy

IL-10 induces activated phenotypes of monocytes observed in virally-suppressed HIV-1-infected individuals

Despite viral suppression by effective combined antiretroviral therapy, HIV-1-infected individuals have an increased risk of non-AIDS-related overall morbidity, which is due to the persistent chronic inflammation exemplified by the activation of monocytes, such as increased CD16high subset, and elevated plasma level of soluble CD163 (sCD163) and soluble CD14 (sCD14). Here, we show that IL-10, which has been recognized as anti-inflammatory, induces these activated phenotypes of monocytes in vitro. IL-10 increased CD16high monocytes, which was due to the upregulation of CD16 mRNA expression and completely canceled by an inhibitor of Stat3. Moreover, IL-10 increased the production of sCD163 and sCD14 by monocytes, which was consistent with the upregulation of cell surface expression of CD163 and CD14, and mRNA expression of CD163. However, unlike the IL-10-indeuced upregulation of CD16, that of CD14 was minimally affected by the Stat3 inhibitor. Furthermore, the IL-10-induced upregulation of CD163 protein and mRNA was partially inhibited by the Stat3 inhibitor, but completely canceled by an inhibitor of AMPK, an upstream kinase of Stat3 and PI3K/Akt/mTORC1 pathways. In this study, we also found that HIV-1 pathogenic protein Nef, which is known to persist in plasma of virally-suppressed individuals, induced IL-10 production in monocyte-derived macrophages. Our results may suggest that IL-10, which is inducible by Nef-activated macrophages, is one of drivers for activated phenotypes of monocytes in virally-suppressed individuals, and that IL-10 induces the increased CD16high monocytes and elevated level of sCD163 and sCD14 through the activation of different signaling pathways.

The role of autophagy in the progression of HIV infected cardiomyopathy

Although highly active antiretroviral therapy (HAART) has changed infection with human immunodeficiency virus (HIV) from a diagnosis with imminent mortality to a chronic illness, HIV positive patients who do not develop acquired immunodeficiency syndrome (AIDs) still suffer from a high rate of cardiac dysfunction and fibrosis. Regardless of viral load and CD count, HIV-associated cardiomyopathy (HIVAC) still causes a high rate of mortality and morbidity amongst HIV patients. While this is a well characterized clinical phenomena, the molecular mechanism of HIVAC is not well understood. In this review, we consolidate, analyze, and discuss current research on the intersection between autophagy and HIVAC. Multiple studies have linked dysregulation in various regulators and functional components of autophagy to HIV infection regardless of mode of viral entry, i.e., coronary, cardiac chamber, or pericardial space. HIV proteins, including negative regulatory factor (Nef), glycoprotein 120 (gp120), and transactivator (Tat), have been shown to interact with type II microtubule-associated protein-1 β light chain (LC3-II), Rubiquitin, SQSTM1/p62, Rab7, autophagy-specific gene 7 (ATG7), and lysosomal-associated membrane protein 1 (LAMP1), all molecules critical to normal autophagy. HIV infection can also induce dysregulation of mitochondrial bioenergetics by altering production and equilibrium of adenosine triphosphate (ATP), mitochondrial reactive oxygen species (ROS), and calcium. These changes alter mitochondrial mass and morphology, which normally trigger autophagy to clear away dysfunctional organelles. However, with HIV infection also triggering autophagy dysfunction, these abnormal mitochondria accumulate and contribute to myocardial dysfunction. Likewise, use of HAART, azidothymidine and Abacavir, have been shown to induce cardiac dysfunction and fibrosis by inducing abnormal autophagy during antiretroviral therapy. Conversely, studies have shown that increasing autophagy can reduce the accumulation of dysfunctional mitochondria and restore cardiomyocyte function. Interestingly, Rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, has also been shown to reduce HIV-induced cytotoxicity by regulating autophagy-related proteins, making it a non-antiviral agent with the potential to treat HIVAC. In this review, we synthesize these findings to provide a better understanding of the role autophagy plays in HIVAC and discuss the potential pharmacologic targets unveiled by this research.

Rapamycin and Starvation Mitigate Indomethacin-Induced Intestinal Damage through Preservation of Lysosomal Vacuolar ATPase Integrity

Nonsteroidal anti-inflammatory drugs (NSAIDs) possess anti-inflammatory, antipyretic, and analgesic properties and are among the most commonly used drugs. Although the cause of NSAID-induced gastric ulcers is well understood, the mechanism behind small intestinal ulcers remains elusive. In this study, we examined the mechanism through which indomethacin (IM), a prominent NSAID, induces small intestinal ulcers, both in vitro and in vivo. In IEC6 cells, a small intestinal epithelial cell line, IM treatment elevated levels of LC3-II and p62. These expression levels remained unaltered after treatment with chloroquine or bafilomycin, which are vacuolar ATPase (V-ATPase) inhibitors. IM treatment reduced the activity of cathepsin B, a lysosomal protein hydrolytic enzyme, and increased the lysosomal pH. There was a notable increase in subcellular colocalization of LC3 with Lamp2, a lysosome marker, post IM treatment. The increased lysosomal pH and decreased cathepsin B activity were reversed by pretreatment with rapamycin (Rapa) or glucose starvation, both of which stabilize V-ATPase assembly. To validate the in vitro findings in vivo, we established an IM-induced small intestine ulcer mouse model. In this model, we observed multiple ulcerations and heightened inflammation following IM administration. However, pretreatment with Rapa or fasting, which stabilize V-ATPase assembly, mitigated the IM-induced small intestinal ulcers in mice. Coimmunoprecipitation studies demonstrated that IM binds to V-ATPase in vitro and in vivo. These findings suggest that IM induces small intestinal injury through lysosomal dysfunction, likely due to the disassembly of lysosomal V-ATPase caused by direct binding. Moreover, Rapa or starvation can prevent this injury by stabilizing the assembly. SIGNIFICANCE STATEMENT: This study elucidates the largely unknown mechanisms behind small intestinal ulceration induced by indomethacin and reveals the involvement of lysosomal dysfunction via vacuolar ATPase disassembly. The significance lies in identifying potential preventative interventions, such as rapamycin treatment or glucose starvation, offering pivotal insights that extend beyond nonsteroidal anti-inflammatory drugs-induced ulcers to broader gastrointestinal pathologies and treatments, thereby providing a foundation for novel therapeutic strategies aimed at a wide array of gastrointestinal disorders.

HIV-Associated Cardiovascular Disease Pathogenesis: An Emerging Understanding Through Imaging and Immunology

Cardiac abnormalities were identified early in the epidemic of AIDS, predating the isolation and characterization of the etiologic agent, HIV. Several decades later, the causation and pathogenesis of cardiovascular disease (CVD) linked to HIV infection continue to be the focus of intense speculation. Before the widespread use of antiretroviral therapy, HIV-associated CVD was primarily characterized by HIV-associated cardiomyopathy linked to profound immunodeficiency. With increasing antiretroviral therapy use, viral load suppression, and establishment of immune competency, the effects of HIV on the cardiovascular system are more subtle. Yet, people living with HIV still face an increased incidence of cardiovascular pathology. Advances in cardiac imaging modalities and immunology have deepened our understanding of the pathogenesis of HIV-associated CVD. This review provides an overview of the pathogenesis of HIV-associated CVD integrating data from imaging and immunologic studies with particular relevance to the HIV population originating from high-endemic regions, such as sub-Saharan Africa. The review highlights key evidence gaps in the field and suggests future directions for research to better understand the complex HIV-CVD interactions.

Connection Between HIV and Mitochondria in Cardiovascular Disease and Implications for Treatments

HIV infection and antiretroviral therapy alter mitochondrial function, which can progressively lead to mitochondrial damage and accelerated aging. The interaction between persistent HIV reservoirs and mitochondria may provide insight into the relatively high rates of cardiovascular disease and mortality in persons living with HIV. In this review, we explore the intricate relationship between HIV and mitochondrial function, highlighting the potential for novel therapeutic strategies in the context of cardiovascular diseases. We reflect on mitochondrial dynamics, mitochondrial DNA, and mitochondrial antiviral signaling protein in the context of HIV. Furthermore, we summarize how toxicities related to early antiretroviral therapy and current highly active antiretroviral therapy can contribute to mitochondrial dysregulation, chronic inflammation, and poor clinical outcomes. There is a need to understand the mechanisms and develop new targeted therapies. We further consider current and potential future therapies for HIV and their interplay with mitochondria. We reflect on the next-generation antiretroviral therapies and HIV cure due to the direct and indirect effects of HIV persistence, associated comorbidities, coinfections, and the advancement of interdisciplinary research fields. This includes exploring novel and creative approaches to target mitochondria for therapeutic intervention.

HIV-1 Nef acts in synergy with APOL1-G1 to induce nephrocyte cell death in a new Drosophila model of HIV-related kidney diseases

Background: People carrying two APOL1 risk alleles (RA) G1 or G2 are at greater risk of developing HIV-associated nephropathy (HIVAN). Studies in transgenic mice showed that the expression of HIV-1 genes in podocytes, and nef in particular, led to HIVAN. However, it remains unclear whether APOL1-RA and HIV-1 Nef interact to induce podocyte cell death. Method: We generated transgenic (Tg) flies that express APOL1-G1 (derived from a child with HIVAN) and HIV-1 nef specifically in the nephrocytes, the fly equivalent of mammalian podocytes, and assessed their individual and combined effects on the nephrocyte filtration structure and function. Results: We found that HIV-1 Nef acts in synergy with APOL1-G1 resulting in nephrocyte structural and functional defects. Specifically, HIV-1 Nef itself can induce endoplasmic reticulum (ER) stress without affecting autophagy. Furthermore, Nef exacerbates the organelle acidification defects and autophagy reduction induced by APOL1-G1. The synergy between HIV-1 Nef and APOL1-G1 is built on their joint effects on elevating ER stress, triggering nephrocyte dysfunction and ultimately cell death. Conclusions: Using a new Drosophila model of HIV-1-related kidney diseases, we identified ER stress as the converging point for the synergy between HIV-1 Nef and APOL1-G1 in inducing nephrocyte cell death. Given the high relevance between Drosophila nephrocytes and human podocytes, this finding suggests ER stress as a new therapeutic target for HIV-1 and APOL1-associated nephropathies.

Catheter ablation approach and outcome in HIV+ patients with recurrent atrial fibrillation

INTRODUCTION

Earlier studies have shown a clear association between severity of human immunodeficiency virus (HIV) infection and incident atrial fibrillation (AF). We present the long-term outcome of catheter ablation (CA) and electrophysiological characteristics in HIV+ AF patients.

METHODS

This study evaluated 1438 consecutive AF patients [31 (2.15%) with HIV and 1407 (97.8%) without HIV diagnosis] undergoing their first CA at our center. A total of 31 HIV patients and 31 controls were generated by propensity matching, based on calculated risk factor scores, using a logistic model. During first procedure, all received isolation of pulmonary vein (PV) + posterior wall and superior vena cava. Non-PV triggers, defined as ectopic triggers originating from sites other than PVs, were identified at the redo ablation with high-dose isoproterenol challenge.

RESULTS

Clinical characteristics were not different between the groups. When compared to the control, by the end of 5 years after the first procedure, recurrence was significantly greater in HIV group [100% vs. 54%, p < .001]. Among patients that underwent redo ablation non-PV triggers were higher in HIV group [93.5% vs. 54%, p < .001], and most frequently originated from the coronary sinus [67.7% vs. 45.2%, p < .001] and left atrial appendage [41.9% vs. 25.8%, p < .001]. After focal ablation of non-PV trigger, no difference in arrhythmia recurrence between two groups [80.6% vs. 87.1%, p = .753] at 1-year follow up was found.

CONCLUSION

Our findings suggest that non-PV triggers are highly prevalent in HIV+ AF patients resulting in higher rate of the mid- and long-term arrhythmia recurrence.

Cardiac arrhythmias in viral infections

BACKGROUND

The current COVID-19 pandemic has led to many studies examining its arrhythmogenic effects. However, there are many other viruses that are capable of inducing arrhythmias that have not received as much attention. The objective of this study was to review common viruses and identify studies highlighting their arrhythmogenic effects.

METHODS AND RESULTS

In this review, we examined 15 viruses and the literature regarding their arrhythmogenic effects. The common mechanisms of action appear to be direct invasion of myocytes leading to immune mediated damage, infection of vascular endothelium, and alteration of cardiac ion channels.

CONCLUSIONS

This review highlights the growing evidence that supports the involvement of other viral infections in the development of arrhythmia. Physicians should be aware of these potentially life-threatening effects when caring for patients with these viruses, some of which are very common. Additional studies are required to better understand the complex mechanism and risk factors of cardiac arrhythmias in patients suffered from viral infections to determine whether the processes can be reversed or even prevented.

The Rab GTPase in the heart: Pivotal roles in development and disease

Rab proteins are a family of small GTPases that function as molecular switches of intracellular vesicle formation and membrane trafficking. As a key factor, Rab GTPase participates in autophagy and protein transport and acts as the central hub of membrane trafficking in eukaryotes. The role of Rab GTPase in neurodegenerative disorders, such as Alzheimer's and Parkinson's, has been extensively investigated; however, its implication in cardiovascular embryogenesis and diseases remains largely unknown. In this review, we summarize previous findings and reveal their importance in the onset and progression of cardiac diseases, as well as their emergence as potential therapeutic targets for cardiovascular disease.

Incidence and risk factors of atrial fibrillation and atrial arrhythmias in people living with HIV: a systematic review and meta-analysis

BACKGROUND

Cardiovascular diseases in people living with HIV (PLWH) are becoming increasingly relevant as HIV/AIDS has become more treatable with the advent of highly efficacious antiretroviral therapy. Previous studies suggested that HIV infection is an independent risk factor for atrial arrhythmia. This study aims to collectively analyze these studies to elucidate the incidence and risk factors of atrial arrhythmia in PLWH.

METHODS

Full-text assessments and data extraction were performed from available literature. Atrial arrhythmia was defined as atrial fibrillation or atrial flutter. Incidence rate, risk, and potential risk factors of atrial arrhythmia in PLWH were catalogued, after which random-effects models were used to estimate pooled summary statistics. PRISMA standardized meta-analysis guidelines were followed.

RESULTS

Analysis of 94,928 PLWH had an averaged incidence rate of 6.4 cases of atrial arrhythmia per 1000 person-years. Risk of atrial arrhythmia was significantly higher in PLWH than in the general population (RR 1.35; 95% CI 1.19-1.53). Sex had no association with the risk of incidental atrial arrhythmia in PLWH (RR 1.47; 95% CI 0.95-2.28). Black race (RR 0.68; 95% CI 0.47-0.97) was associated with decreased risk, whereas lower CD4 counts (RR 1.80; 95% CI 1.18-2.77) and increased viral load (RR 1.57; 95% CI 1.19-2.09) suggested increased risk of atrial arrhythmia in PLWH.

CONCLUSIONS

HIV infection is a risk factor of atrial arrhythmia. Providers should be aware of the increased burden of atrial arrhythmia in PLWH and continue to encourage treatment of HIV infection while managing cardiovascular risk factors and screening for arrhythmias in symptomatic patients.

Complexities of JC Polyomavirus Receptor-Dependent and -Independent Mechanisms of Infection

JC polyomavirus (JCPyV) is a small non-enveloped virus that establishes lifelong, persistent infection in most of the adult population. Immune-competent patients are generally asymptomatic, but immune-compromised and immune-suppressed patients are at risk for the neurodegenerative disease progressive multifocal leukoencephalopathy (PML). Studies with purified JCPyV found it undergoes receptor-dependent infectious entry requiring both lactoseries tetrasaccharide C (LSTc) attachment and 5-hydroxytryptamine type 2 entry receptors. Subsequent work discovered the major targets of JCPyV infection in the central nervous system (oligodendrocytes and astrocytes) do not express the required attachment receptor at detectable levels, virus could not bind these cells in tissue sections, and viral quasi-species harboring recurrent mutations in the binding pocket for attachment. While several research groups found evidence JCPyV can use novel receptors for infection, it was also discovered that extracellular vesicles (EVs) can mediate receptor independent JCPyV infection. Recent work also found JCPyV associated EVs include both exosomes and secretory autophagosomes. EVs effectively present a means of immune evasion and increased tissue tropism that complicates viral studies and anti-viral therapeutics. This review focuses on JCPyV infection mechanisms and EV associated and outlines key areas of study necessary to understand the interplay between virus and extracellular vesicles.

SARS-CoV-2 infection enhances mitochondrial PTP complex activity to perturb cardiac energetics

SARS-CoV-2 is a newly identified coronavirus that causes the respiratory disease called coronavirus disease 2019 (COVID-19). With an urgent need for therapeutics, we lack a full understanding of the molecular basis of SARS-CoV-2-induced cellular damage and disease progression. Here, we conducted transcriptomic analysis of human PBMCs, identified significant changes in mitochondrial, ion channel, and protein quality-control gene products. SARS-CoV-2 proteins selectively target cellular organelle compartments, including the endoplasmic reticulum and mitochondria. M-protein, NSP6, ORF3A, ORF9C, and ORF10 bind to mitochondrial PTP complex components cyclophilin D, SPG-7, ANT, ATP synthase, and a previously undescribed CCDC58 (coiled-coil domain containing protein 58). Knockdown of CCDC58 or mPTP blocker cyclosporin A pretreatment enhances mitochondrial Ca2+ retention capacity and bioenergetics. SARS-CoV-2 infection exacerbates cardiomyocyte autophagy and promotes cell death that was suppressed by cyclosporin A treatment. Our findings reveal that SARS-CoV-2 viral proteins suppress cardiomyocyte mitochondrial function that disrupts cardiomyocyte Ca2+ cycling and cell viability.

Autophagy and Endoplasmic Reticulum Stress during Onset and Progression of Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (AC) is a heritable, potentially lethal disease without a causal therapy. AC is characterized by focal cardiomyocyte death followed by inflammation and progressive formation of connective tissue. The pathomechanisms leading to structural disease onset and progression, however, are not fully elucidated. Recent studies revealed that dysregulation of autophagy and endoplasmic/sarcoplasmic reticulum (ER/SR) stress plays an important role in cardiac pathophysiology. We therefore examined the temporal and spatial expression patterns of autophagy and ER/SR stress indicators in murine AC models by qRT-PCR, immunohistochemistry, in situ hybridization and electron microscopy. Cardiomyocytes overexpressing the autophagy markers LC3 and SQSTM1/p62 and containing prominent autophagic vacuoles were detected next to regions of inflammation and fibrosis during onset and chronic disease progression. mRNAs of the ER stress markers Chop and sXbp1 were elevated in both ventricles at disease onset. During chronic disease progression Chop mRNA was upregulated in right ventricles. In addition, reduced Ryr2 mRNA expression together with often drastically enlarged ER/SR cisternae further indicated SR dysfunction during this disease phase. Our observations support the hypothesis that locally altered autophagy and enhanced ER/SR stress play a role in AC pathogenesis both at the onset and during chronic progression.

Emerging Role of Nef in the Development of HIV Associated Neurological Disorders

Despite adherence to treatment, individuals living with HIV have an increased risk for developing cognitive impairments, referred to as HIV-associated neurological disorders (HAND). Due to continued growth in the HIV population, particularly amongst the aging cohort, the neurobiological mechanisms of HAND are increasingly relevant. Similar to other viral proteins (e.g. Tat, Gp120, Vpr), the Negative Factor (Nef) is associated with numerous adverse effects in the CNS as well as cognitive impairments. In particular, emerging data indicate the consequences of Nef may be facilitated by the modulation of cellular autophagy as well as its inclusion into extracellular vesicles (EVs). The present review examines evidence for the molecular mechanisms by which Nef might contribute to neuronal dysfunction underlying HAND, with a specific focus on autophagy and EVs. Based on the these data, we propose an integrated model by which Nef may contribute to underlying neuronal dysfunction in HAND and highlight potentially novel therapeutic targets for HAND. Graphical abstract.

Autophagy-enhancing drugs limit mucosal HIV-1 acquisition and suppress viral replication ex vivo

Current direct-acting antiviral therapies are highly effective in suppressing HIV-1 replication. However, mucosal inflammation undermines prophylactic treatment efficacy, and HIV-1 persists in long-lived tissue-derived dendritic cells (DCs) and CD4+ T cells of treated patients. Host-directed strategies are an emerging therapeutic approach to improve therapy outcomes in infectious diseases. Autophagy functions as an innate antiviral mechanism by degrading viruses in specialized vesicles. Here, we investigated the impact of pharmaceutically enhancing autophagy on HIV-1 acquisition and viral replication. To this end, we developed a human tissue infection model permitting concurrent analysis of HIV-1 cellular targets ex vivo. Prophylactic treatment with autophagy-enhancing drugs carbamazepine and everolimus promoted HIV-1 restriction in skin-derived CD11c+ DCs and CD4+ T cells. Everolimus also decreased HIV-1 susceptibility to lab-adapted and transmitted/founder HIV-1 strains, and in vaginal Langerhans cells. Notably, we observed cell-specific effects of therapeutic treatment. Therapeutic rapamycin treatment suppressed HIV-1 replication in tissue-derived CD11c+ DCs, while all selected drugs limited viral replication in CD4+ T cells. Strikingly, both prophylactic and therapeutic treatment with everolimus or rapamycin reduced intestinal HIV-1 productive infection. Our findings highlight host autophagy pathways as an emerging target for HIV-1 therapies, and underscore the relevancy of repurposing clinically-approved autophagy drugs to suppress mucosal HIV-1 replication.

Extracellular vesicles from HTLV-1 infected cells modulate target cells and viral spread

BACKGROUND

The Human T-cell Lymphotropic Virus Type-1 (HTLV-1) is a blood-borne pathogen and etiological agent of Adult T-cell Leukemia/Lymphoma (ATLL) and HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). HTLV-1 has currently infected up to 10 million globally with highly endemic areas in Japan, Africa, the Caribbean and South America. We have previously shown that Extracellular Vesicles (EVs) enhance HTLV-1 transmission by promoting cell-cell contact.

RESULTS

Here, we separated EVs into subpopulations using differential ultracentrifugation (DUC) at speeds of 2 k (2000×g), 10 k (10,000×g), and 100 k (100,000×g) from infected cell supernatants. Proteomic analysis revealed that EVs contain the highest viral/host protein abundance in the 2 k subpopulation (2 k > 10 k > 100 k). The 2 k and 10 k populations contained viral proteins (i.e., p19 and Tax), and autophagy proteins (i.e., LC3 and p62) suggesting presence of autophagosomes as well as core histones. Interestingly, the use of 2 k EVs in an angiogenesis assay (mesenchymal stem cells + endothelial cells) caused deterioration of vascular-like-tubules. Cells commonly associated with the neurovascular unit (i.e., astrocytes, neurons, and macrophages) in the blood-brain barrier (BBB) showed that HTLV-1 EVs may induce expression of cytokines involved in migration (i.e., IL-8; 100 k > 2 k > 10 k) from astrocytes and monocyte-derived macrophages (i.e., IL-8; 2 k > 10 k). Finally, we found that EVs were able to promote cell-cell contact and viral transmission in monocytic cell-derived dendritic cell. The EVs from both 2 k and 10 k increased HTLV-1 spread in a humanized mouse model, as evidenced by an increase in proviral DNA and RNA in the Blood, Lymph Node, and Spleen.

CONCLUSIONS

Altogether, these data suggest that various EV subpopulations induce cytokine expression, tissue damage, and viral spread.

Human TRIM5α: Autophagy Connects Cell-Intrinsic HIV-1 Restriction and Innate Immune Sensor Functioning

Human immunodeficiency virus-1 (HIV-1) persists as a global health concern, with an incidence rate of approximately 2 million, and estimated global prevalence of over 35 million. Combination antiretroviral treatment is highly effective, but HIV-1 patients that have been treated still suffer from chronic inflammation and residual viral replication. It is therefore paramount to identify therapeutically efficacious strategies to eradicate viral reservoirs and ultimately develop a cure for HIV-1. It has been long accepted that the restriction factor tripartite motif protein 5 isoform alpha (TRIM5α) restricts HIV-1 infection in a species-specific manner, with rhesus macaque TRIM5α strongly restricting HIV-1, and human TRIM5α having a minimal restriction capacity. However, several recent studies underscore human TRIM5α as a cell-dependent HIV-1 restriction factor. Here, we present an overview of the latest research on human TRIM5α and propose a novel conceptualization of TRIM5α as a restriction factor with a varied portfolio of antiviral functions, including mediating HIV-1 degradation through autophagy- and proteasome-mediated mechanisms, and acting as a viral sensor and effector of antiviral signaling. We have also expanded on the protective antiviral roles of autophagy and outline the therapeutic potential of autophagy modulation to intervene in chronic HIV-1 infection.

HIV Nef enhances the expression of oncogenic c-MYC and activation-induced cytidine deaminase in Burkitt lymphoma cells, promoting genomic instability

Background

Non-Hodgkin lymphoma is of high prevalence among HIV-infected people. In particular, the incidence of HIV-associated Burkitt lymphoma (BL) remains high despite the advent of Highly Active Anti-Retroviral Therapy. Recent evidence shows that serum-soluble HIV proteins can enhance oncogenesis, particularly in lymphoid tissues. This study sought to define the role of HIV protein Negative regulatory factor (Nef) in BL development by assessing its effect on key lymphoma driver genes.

Methods

A recombinant Nef protein was used to assess changes in expressions of activation-induced cytidine deaminase (AICDA/AID) and c-MYC in B lymphocytes exposed extracellularly to the protein. Additionally, changes in the promoter activities of these genes were measured using a Nef-expressing cellular model and reporter assays. Confocal microscopy was used to observe c-MYC and AID expression and localization, and genomic integrity via the recruitment of phosphorylated γ-H2AX, in Nef-exposed cells.

Results

mRNA transcription of c-MYC and AICDA were significantly enhanced in lymphoma cells, up to 2-fold for c-MYC and up to 4-fold for AICDA, when exposed to varying concentrations of Nef (0–1000 ng/ml) and for different periods of time (3, 6 and 12 h). The protein expressions of AID and c-MYC followed a similar pattern and these effects were specific to BL but not lymphoblastoid cells. While the promoter activity of c-MYC was enhanced in the presence of Nef in a dose-dependent manner, the same was not observed for AICDA. Both AID and c-MYC accumulated within the cytoplasmic and nuclear spaces of Nef-exposed lymphoma cells, with a concomitant increase in DNA double strand breaks within the genome.

Conclusions

Exposure to HIV Nef leads to significant increases in AID and c-MYC, leading to genomic instability, potentially enhancing the oncogenic potential of Burkitt lymphoma. Our findings align with that of others to show that HIV proteins can directly contribute to the development and pathogenesis of HIV-associated lymphoma and accounts for the elevated incidence of BL observed in the HIV-infected population.

Low-Level Ionizing Radiation Induces Selective Killing of HIV-1-Infected Cells with Reversal of Cytokine Induction Using mTOR Inhibitors

HIV-1 infects 39.5 million people worldwide, and cART is effective in preventing viral spread by reducing HIV-1 plasma viral loads to undetectable levels. However, viral reservoirs persist by mechanisms, including the inhibition of autophagy by HIV-1 proteins (i.e., Nef and Tat). HIV-1 reservoirs can be targeted by the "shock and kill" strategy, which utilizes latency-reversing agents (LRAs) to activate latent proviruses and immunotarget the virus-producing cells. Yet, limitations include reduced LRA permeability across anatomical barriers and immune hyper-activation. Ionizing radiation (IR) induces effective viral activation across anatomical barriers. Like other LRAs, IR may cause inflammation and modulate the secretion of extracellular vesicles (EVs). We and others have shown that cells may secrete cytokines and viral proteins in EVs and, therefore, LRAs may contribute to inflammatory EVs. In the present study, we mitigated the effects of IR-induced inflammatory EVs (i.e., TNF-α), through the use of mTOR inhibitors (mTORi; Rapamycin and INK128). Further, mTORi were found to enhance the selective killing of HIV-1-infected myeloid and T-cell reservoirs at the exclusion of uninfected cells, potentially via inhibition of viral transcription/translation and induction of autophagy. Collectively, the proposed regimen using cART, IR, and mTORi presents a novel approach allowing for the targeting of viral reservoirs, prevention of immune hyper-activation, and selectively killing latently infected HIV-1 cells.

HIV and antiretroviral therapy-related fat alterations

Early in the HIV epidemic, lipodystrophy, characterized by subcutaneous fat loss (lipoatrophy), with or without central fat accumulation (lipohypertrophy), was recognized as a frequent condition among people living with HIV (PLWH) receiving combination antiretroviral therapy. The subsequent identification of thymidine analogue nucleoside reverse transcriptase inhibitors as the cause of lipoatrophy led to the development of newer antiretroviral agents; however, studies have demonstrated continued abnormalities in fat and/or lipid storage in PLWH treated with newer drugs (including integrase inhibitor-based regimens), with fat gain due to restoration to health in antiretroviral therapy-naive PLWH, which is compounded by the rising rates of obesity. The mechanisms of fat alterations in PLWH are complex, multifactorial and not fully understood, although they are known to result in part from the direct effects of HIV proteins and antiretroviral agents on adipocyte health, genetic factors, increased microbial translocation, changes in the adaptive immune milieu after infection, increased tissue inflammation and accelerated fibrosis. Management includes classical lifestyle alterations with a role for pharmacological therapies and surgery in some patients. Continued fat alterations in PLWH will have an important effect on lifespan, healthspan and quality of life as patients age worldwide, highlighting the need to investigate the critical uncertainties regarding pathophysiology, risk factors and management.

HIV Nef and Antiretroviral Therapy Have an Inhibitory Effect on Autophagy in Human Astrocytes that May Contribute to HIV-Associated Neurocognitive Disorders

A significant number of people living with HIV (PLWH) develop HIV-associated neurocognitive disorders (HAND) despite highly effective antiretroviral therapy (ART). Dysregulated macroautophagy (autophagy) is implicated in HAND pathogenesis. The viral protein Nef, expressed even with suppressive ART, and certain antiretrovirals affect autophagy in non-CNS cells. Astrocytes, vital for CNS microenvironment homeostasis and neuronal health, require autophagy for their own homeostasis. We hypothesized that extracellular Nef and/or ART impact astrocyte autophagy, thus contributing to HAND. We studied in-bulk and selective autophagic flux in primary human astrocytes treated with extracellular Nef and/or a combination of tenofovir+emtricitabine+raltegravir (ART) using Western blotting, a tandem fluorescent LC3 reporter, and transmission electron microscopy/morphometry. We show that after 24 h treatment, Nef and ART decrease autophagosomes through different mechanisms. While Nef accelerates autophagosome degradation without inducing autophagosome formation, ART inhibits autophagosome formation. Combination Nef+ART further depletes autophagosomes by inducing both abnormalities. Additionally, extracellular Nef and/or ART inhibit lysosomal degradation of p62, indicating Nef and/or ART affect in-bulk and selective autophagy differently. Dysregulation of both autophagic processes is maintained after 7 days of Nef and/or ART treatment. Persistent autophagy dysregulation due to chronic Nef and/or ART exposure may ultimately result in astrocyte and neuronal dysfunction, contributing to HAND.

SIV Infection and the HIV Proteins Tat and Nef Induce Senescence in Adipose Tissue and Human Adipose Stem Cells, Resulting in Adipocyte Dysfunction

Background: Aging is characterized by adipose tissue senescence, inflammation, and fibrosis, with trunk fat accumulation. Aging HIV-infected patients have a higher risk of trunk fat accumulation than uninfected individuals—suggesting that viral infection has a role in adipose tissue aging. We previously demonstrated that HIV/SIV infection and the Tat and Nef viral proteins were responsible for adipose tissue fibrosis and impaired adipogenesis. We hypothesized that SIV/HIV infection and viral proteins could induce adipose tissue senescence and thus lead to adipocyte dysfunctions. Methods: Features of tissue senescence were evaluated in subcutaneous and visceral adipose tissues of SIV-infected macaques and in human adipose stem cells (ASCs) exposed to Tat or Nef for up to 30 days. Results: p16 expression and p53 activation were higher in adipose tissue of SIV-infected macaques than in control macaques, indicating adipose tissue senescence. Tat and Nef induced higher senescence in ASCs, characterized by higher levels of senescence-associated beta-galactosidase activity, p16 expression, and p53 activation vs. control cells. Treatment with Tat and Nef also induced oxidative stress and mitochondrial dysfunction. Prevention of oxidative stress (using N-acetyl-cysteine) reduced senescence in ASCs. Adipocytes having differentiated from Nef-treated ASCs displayed alterations in adipogenesis with lower levels of triglyceride accumulation and adipocyte marker expression and secretion, and insulin resistance. Conclusion: HIV/SIV promotes adipose tissue senescence, which in turn may alter adipocyte function and contribute to insulin resistance.

HIV-Nef Protein Transfer to Endothelial Cells Requires Rac1 Activation and Leads to Endothelial Dysfunction Implications for Statin Treatment in HIV Patients

RATIONALE

Even in antiretroviral therapy-treated patients, HIV continues to play a pathogenic role in cardiovascular diseases. A possible cofactor may be persistence of the early HIV response gene Nef, which we have demonstrated recently to persist in the lungs of HIV+ patients on antiretroviral therapy. Previously, we have reported that HIV strains with Nef, but not Nef-deleted HIV strains, cause endothelial proinflammatory activation and apoptosis.

OBJECTIVE

To characterize mechanisms through which HIV-Nef leads to the development of cardiovascular diseases using ex vivo tissue culture approaches as well as interventional experiments in transgenic murine models.

METHODS AND RESULTS

Extracellular vesicles derived from both peripheral blood mononuclear cells and plasma from HIV+ patient blood samples induced human coronary artery endothelial cells dysfunction. Plasma-derived extracellular vesicles from antiretroviral therapy+ patients who were HIV-Nef+ induced significantly greater endothelial apoptosis compared with HIV-Nef-plasma extracellular vesicles. Both HIV-Nef expressing T cells and HIV-Nef-induced extracellular vesicles increased transfer of cytosol and Nef protein to endothelial monolayers in a Rac1-dependent manner, consequently leading to endothelial adhesion protein upregulation and apoptosis. HIV-Nef induced Rac1 activation also led to dsDNA breaks in endothelial colony forming cells, thereby resulting in endothelial colony forming cell premature senescence and endothelial nitric oxide synthase downregulation. These Rac1-dependent activities were characterized by NOX2-mediated reactive oxygen species production. Statin treatment equally inhibited Rac1 inhibition in preventing or reversing all HIV-Nef-induction abnormalities assessed. This was likely because of the ability of statins to block Rac1 prenylation as geranylgeranyl transferase inhibitors were effective in inhibiting HIV-Nef-induced reactive oxygen species formation. Finally, transgenic expression of HIV-Nef in endothelial cells in a murine model impaired endothelium-mediated aortic ring dilation, which was then reversed by 3-week treatment with 5 mg/kg atorvastatin.

CONCLUSIONS

These studies establish a mechanism by which HIV-Nef persistence despite antiretroviral therapy could contribute to ongoing HIV-related vascular dysfunction, which may then be ameliorated by statin treatment.

The autophagy protein ATG9A promotes HIV-1 infectivity

BACKGROUND

Nef is a multifunctional accessory protein encoded by HIV-1, HIV-2 and SIV that plays critical roles in viral pathogenesis, contributing to viral replication, assembly, budding, infectivity and immune evasion, through engagement of various host cell pathways.

RESULTS

To gain a better understanding of the role of host proteins in the functions of Nef, we carried out tandem affinity purification-mass spectrometry analysis, and identified over 70 HIV-1 Nef-interacting proteins, including the autophagy-related 9A (ATG9A) protein. ATG9A is a transmembrane component of the machinery for autophagy, a catabolic process in which cytoplasmic components are degraded in lysosomal compartments. Pulldown experiments demonstrated that ATG9A interacts with Nef from not only HIV-1 and but also SIV (cpz, smm and mac). However, expression of HIV-1 Nef had no effect on the levels and localization of ATG9A, and on autophagy, in the host cells. To investigate a possible role for ATG9A in virus replication, we knocked out ATG9A in HeLa cervical carcinoma and Jurkat T cells, and analyzed virus release and infectivity. We observed that ATG9A knockout (KO) had no effect on the release of wild-type (WT) or Nef-defective HIV-1 in these cells. However, the infectivity of WT virus produced from ATG9A-KO HeLa and Jurkat cells was reduced by ~ fourfold and eightfold, respectively, relative to virus produced from WT cells. This reduction in infectivity was independent of the interaction of Nef with ATG9A, and was not due to reduced incorporation of the viral envelope (Env) glycoprotein into the virus. The loss of HIV-1 infectivity was rescued by pseudotyping HIV-1 virions with the vesicular stomatitis virus G glycoprotein.

CONCLUSIONS

These studies indicate that ATG9A promotes HIV-1 infectivity in an Env-dependent manner. The interaction of Nef with ATG9A, however, is not required for Nef to enhance HIV-1 infectivity. We speculate that ATG9A could promote infectivity by participating in either the removal of a factor that inhibits infectivity or the incorporation of a factor that enhances infectivity of the viral particles. These studies thus identify a novel host cell factor implicated in HIV-1 infectivity, which may be amenable to pharmacologic manipulation for treatment of HIV-1 infection.

Autophagy Intertwines with Different Diseases-Recent Strategies for Therapeutic Approaches

Autophagy is a regular and substantial “clear-out process” that occurs within the cell and that gets rid of debris that accumulates in membrane-enclosed vacuoles by using enzyme-rich lysosomes, which are filled with acids that degrade the contents of the vacuoles. This machinery is well-connected with many prevalent diseases, including cancer, HIV, and Parkinson’s disease. Considering that autophagy is well-known for its significant connections with a number of well-known fatal diseases, a thorough knowledge of the current findings in the field is essential in developing therapies to control the progression rate of diseases. Thus, this review summarizes the critical events comprising autophagy in the cellular system and the significance of its key molecules in manifesting this pathway in various diseases for down- or upregulation. We collectively reviewed the role of autophagy in various diseases, mainly neurodegenerative diseases, cancer, inflammatory diseases, and renal disorders. Here, some collective reports on autophagy showed that this process might serve as a dual performer: either protector or contributor to certain diseases. The aim of this review is to help researchers to understand the role of autophagy-regulating genes encoding functional open reading frames (ORFs) and its connection with diseases, which will eventually drive better understanding of both the progression and suppression of different diseases at various stages. This review also focuses on certain novel therapeutic strategies which have been published in the recent years based on targeting autophagy key proteins and its interconnecting signaling cascades.

Atrial fibrillation and human immunodeficiency virus type-1 infection: a systematic review. Implications for anticoagulant and antiarrhythmic therapy

The prevalence and incidence of atrial fibrillation/flutter (AF/AFL) in patients with human immunodeficiency virus type-1 (HIV-1) infection have been poorly investigated. We performed a systematic review using PubMed and Cochrane Database of Systematic Reviews, and screening of references, searching for clinical studies reporting on the association between HIV-1 infection and AF/AFL. We also summarized the main interactions of antiretroviral agents with antithrombotic and antiarrhythmic drugs. We found a prevalence of AF/AFL ranging from 2.0% to 5.13% in patients with HIV-1, with an incidence rate of 3.6/1000 person-years. Low CD4+ count (<200-250 cells ml^-1 ) and high viral load were predictors of AF/AFL. Regarding drugs interactions, nucleoside reverse transcriptase inhibitors, integrase inhibitor and maraviroc have the lowest interactions with oral anticoagulants. Among anticoagulants, dabigatran presents the most favourable profile. Most of antiarrhythmic drugs interact with protease inhibitors, with beta blockers and diltiazem having fewer interactions. The few studies available suggest a non-negligible prevalence of AF/AFL in patients with HIV-1 infection. Awareness of potential interactions with anticoagulation and antiarrhythmic drugs is needed to offer optimal management in this population.

Modelling interaction between HIV-1 Nef and calnexin

BACKGROUND

HIV-associated atherosclerosis is a major comorbidity due, in part, to systemic effects of the virus on cholesterol metabolism. HIV protein Nef plays an important role in this pathology by impairing maturation of the main cellular cholesterol transporter ATP-Binding Cassette (ABCA) 1. ABCA1 maturation critically depends on calnexin, an integral endoplasmic reticulum membrane chaperone, and Nef binds to the cytoplasmic domain of calnexin and impairs interaction of calnexin with ABCA1. Overarching goal of the present study was to model Nef-calnexin interaction interface, and identify small molecule compounds potentially inhibiting this interaction.

METHODS

Molecular dynamics was utilized to build structure model of calnexin cytoplasmic domain, followed by global docking combined with application of QASDOM software developed by us for efficient analysis of receptor-ligand complexes. Structure-based virtual screening was performed for all sites identified by docking. A soluble analogue of a compound from the screening results list was tested for ability to down-regulate ABCA1.

RESULTS

We identified major interaction sites in calnexin and reciprocal sites in Nef. Virtual screening yielded a number of small-molecule compounds potentially blocking a calnexin site. Interestingly, one of the compounds, NSC13987, was previously identified by us as an inhibitor targeting a Nef site. An analogue of NSC13987, AMS-55, potently reversed the negative effect of Nef on ABCA1 abundance.

CONCLUSIONS

We have modelled Nef-calnexin interaction, predicted small molecule compounds that can potentially inhibit this interaction, and experimentally tested one of these compounds, confirming its effectiveness. These findings provide a platform for searching for new therapeutic agents to treat HIV-associated comorbidities.

The role of HIV Tat protein in HIV-related cardiovascular diseases

The human immunodeficiency virus (HIV) is a major global public health issue. HIV-related cardiovascular disease remains a leading cause of morbidity and mortality in HIV positive patients. HIV Tat is a regulatory protein encoded by tat gene of HIV-1, which not only promotes the transcription of HIV, but it is also involved in the pathogenesis of HIV-related complications. This review is aimed at summarizing the current understanding of Tat in HIV-related cardiovascular diseases.

miR-224 suppresses HBV replication posttranscriptionally through inhibiting SIRT1-mediated autophagy

Hepatitis B virus (HBV) enters the host and successfully completes replication by using several mechanisms, including autophagy. However, previous studies revealed that microRNAs (miRNAs) widely participate in regulation of various cellular processes, such as autophagy and viral replication. Hence, the purpose of this study was to investigate the role of miR-224 in HBV infection and to determine whether its role depended on the miR-224/SIRT1/autophagy axis. Our results show that secretions of HBeAg and HBsAg, and HBV replication significantly declined in Huh7-1.3 cells, established by transfecting recombinant pcDNA 3.0-1.3 mer containing the 1.3 mer fragment of HBV genomic DNA,with miR-224 mimic transfection as compared to the Huh7-1.3 group. Moreover, it was discovered that HBV could induce autophagy, while miR-224 inhibited autophagy caused by HBV. Additionally, miR-224 could suppress SIRT1, LC3 expression, and facilitate p62 expression. SIRT1 was identified as the target gene of miR-224 and down-regulation of SIRT1 via miR-224 or si-SIRT1 transfected treatment in Huh7-1.3 cells repressed LC3 expression and enhanced p62 expression. In conclusion, these results suggest that miR-224 might hinder HBV replication through attenuating SIRT1-mediated autophagy, thereby these findings open a new avenue for the treatment of HBV infection.

Brain-specific HIV Nef identified in multiple patients with neurological disease

HIV-1 Nef is a flexible, multifunctional protein with several cellular targets that is required for pathogenicity of the virus. This protein maintains a high degree of genetic variation among intra- and inter-host isolates. HIV Nef is relevant to HIV-associated neurological diseases (HAND) in patients treated with combined antiretroviral therapy because of the protein's role in promoting survival and migration of infected brain macrophages. In this study, we analyzed 2020 HIV Nef sequences derived from 22 different tissues and 31 subjects using a novel computational approach. This approach combines statistical regression and evolved neural networks (ENNs) to classify brain sequences based on the physical and chemical characteristics of functional Nef domains. Based on training, testing, and validation data, the method successfully classified brain Nef sequences at 84.5% and provided informative features for further examination. These included physicochemical features associated with the Src-homology-3 binding domain, the Nef loop (including the AP-2 Binding region), and a cytokine-binding domain. Non-brain sequences from patients with HIV-associated neurological disease were frequently classified as brain, suggesting that the approach could indicate neurological risk using blood-derived virus or for the development of biomarkers for use in assay systems aimed at drug efficacy studies for the treatment of HIV-associated neurological diseases.