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

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.

The Question of HIV Vaccine: Why Is a Solution Not Yet Available?

Ever since its discovery, human immunodeficiency virus type 1 (HIV-1) infection has remained a significant public health concern. The number of HIV-1 seropositive individuals currently stands at 40.1 million, yet definitive treatment for the virus is still unavailable on the market. Vaccination has proven to be a potent tool in combating infectious diseases, as evidenced by its success against other pathogens. However, despite ongoing efforts and research, the unique viral characteristics have prevented the development of an effective anti-HIV-1 vaccine. In this review, we aim to provide an historical overview of the various approaches attempted to create an effective anti-HIV-1 vaccine. Our objective is to explore the reasons why specific methods have failed to induce a protective immune response and to analyze the different modalities of immunogen presentation. This trial is registered with NCT05414786, NCT05471076, NCT04224701, and NCT01937455.

Intestinal Microbiota Dysbiosis Promotes Mucosal Barrier Damage and Immune Injury in HIV-Infected Patients

The intestinal microbiota is an "invisible organ" in the human body, with diverse components and complex interactions. Homeostasis of the intestinal microbiota plays a pivotal role in maintaining the normal physiological process and regulating immune homeostasis. By reviewing more than one hundred related studies concerning HIV infection and intestinal microbiota from 2011 to 2023, we found that human immunodeficiency virus (HIV) infection can induce intestinal microbiota dysbiosis, which not only worsens clinical symptoms but also promotes the occurrence of post-sequelae symptoms and comorbidities. In the early stage of HIV infection, the intestinal mucosal barrier is damaged and a persistent inflammatory response is induced. Mucosal barrier damage and immune injury play a pivotal role in promoting the post-sequelae symptoms caused by HIV infection. This review summarizes the relationship between dysbiosis of the intestinal microbiota and mucosal barrier damage during HIV infection and discusses the potential mechanisms of intestinal barrier damage induced by intestinal microbiota dysbiosis and inflammation. Exploring these molecular mechanisms might provide new ideas to improve the efficacy of HIV treatment and reduce the incidence of post-sequelae symptoms.

Neurological, Behavioral, and Pathophysiological Characterization of the Co-Occurrence of Substance Use and HIV: A Narrative Review

Combined antiretroviral therapy (cART) has greatly reduced the severity of HIV-associated neurocognitive disorders in people living with HIV (PLWH); however, PLWH are more likely than the general population to use drugs and suffer from substance use disorders (SUDs) and to exhibit risky behaviors that promote HIV transmission and other infections. Dopamine-boosting psychostimulants such as cocaine and methamphetamine are some of the most widely used substances among PLWH. Chronic use of these substances disrupts brain function, structure, and cognition. PLWH with SUD have poor health outcomes driven by complex interactions between biological, neurocognitive, and social factors. Here we review the effects of comorbid HIV and psychostimulant use disorders by discussing the distinct and common effects of HIV and chronic cocaine and methamphetamine use on behavioral and neurological impairments using evidence from rodent models of HIV-associated neurocognitive impairments (Tat or gp120 protein expression) and clinical studies. We also provide a biopsychosocial perspective by discussing behavioral impairment in differentially impacted social groups and proposing interventions at both patient and population levels.

Ectopic expression of HIV-1 Tat modifies gene expression in cultured B cells: implications for the development of B-cell lymphomas in HIV-1-infected patients

An increased frequency of B-cell lymphomas is observed in human immunodeficiency virus-1 (HIV-1)-infected patients, although HIV-1 does not infect B cells. Development of B-cell lymphomas may be potentially due to the action of the HIV-1 Tat protein, which is actively released from HIV-1-infected cells, on uninfected B cells. The exact mechanism of Tat-induced B-cell lymphomagenesis has not yet been precisely identified. Here, we ectopically expressed either Tat or its TatC22G mutant devoid of transactivation activity in the RPMI 8866 lymphoblastoid B cell line and performed a genome-wide analysis of host gene expression. Stable expression of both Tat and TatC22G led to substantial modifications of the host transcriptome, including pronounced changes in antiviral response and cell cycle pathways. We did not find any strong action of Tat on cell proliferation, but during prolonged culturing, Tat-expressing cells were displaced by non-expressing cells, indicating that Tat expression slightly inhibited cell growth. We also found an increased frequency of chromosome aberrations in cells expressing Tat. Thus, Tat can modify gene expression in cultured B cells, leading to subtle modifications in cellular growth and chromosome instability, which could promote lymphomagenesis over time.

Mice with humanized immune system as novel models to study HIV-associated pulmonary hypertension

People living with HIV and who receive antiretroviral therapy have a significantly improved lifespan, compared to the early days without therapy. Unfortunately, persisting viral replication in the lungs sustains chronic inflammation, which may cause pulmonary vascular dysfunction and ultimate life-threatening Pulmonary Hypertension (PH). The mechanisms involved in the progression of HIV and PH remain unclear. The study of HIV-PH is limited due to the lack of tractable animal models that recapitulate infection and pathobiological aspects of PH. On one hand, mice with humanized immune systems (hu-mice) are highly relevant to HIV research but their suitability for HIV-PH research deserves investigation. On another hand, the Hypoxia-Sugen is a well-established model for experimental PH that combines hypoxia with the VEGF antagonist SU5416. To test the suitability of hu-mice, we combined HIV with either SU5416 or hypoxia. Using right heart catheterization, we found that combining HIV+SU5416 exacerbated PH. HIV infection increases human pro-inflammatory cytokines in the lungs, compared to uninfected mice. Histopathological examinations showed pulmonary vascular inflammation with arterial muscularization in HIV-PH. We also found an increase in endothelial-monocyte activating polypeptide II (EMAP II) when combining HIV+SU5416. Therefore, combinations of HIV with SU5416 or hypoxia recapitulate PH in hu-mice, creating well-suited models for infectious mechanistic pulmonary vascular research in small animals.

[Analysis of Tat protein characteristics in human immunodeficiency virus type 1 sub-subtype A6 (Retroviridae: Orthoretrovirinae: Lentivirus: Human immunodeficiency virus-1)]

INTRODUCTION

Tat protein is a major factor of HIV (human immunodeficiency virus) transcription regulation and has other activities. Tat is characterized by high variability, with some amino acid substitutions, including subtypespecific ones, being able to influence on its functionality. HIV type 1 (HIV-1) sub-subtype A6 is the most widespread in Russia. Previous studies of the polymorphisms in structural regions of the A6 variant have shown numerous characteristic features; however, Tat polymorphism in A6 has not been studied.Goals and tasks. The main goal of the work was to analyze the characteristics of Tat protein in HIV-1 A6 variant, that is, to identify substitutions characteristic for A6 and A1 variants, as well as to compare the frequency of mutations in functionally significant domains in sub-subtype A6 and subtype B.

MATERIAL AND METHODS

The nucleotide sequences of HIV-1 sub-subtypes A6, A1, A2, A3, A4, subtype B and the reference nucleotide sequence were obtained from the Los Alamos international database.

RESULTS AND DISCUSSION

Q54H and Q60H were identified as characteristic substitutions. Essential differences in natural polymorphisms between sub-subtypes A6 and A1 have been demonstrated. In the CPP-region, there were detected mutations (R53K, Q54H, Q54P, R57G) which were more common in sub-subtype A6 than in subtype B.

CONCLUSION

Tat protein of sub-subtype A6 have some characteristics that make it possible to reliably distinguish it from other HIV-1 variants. Mutations identified in the CPP region could potentially alter the activity of Tat. The data obtained could form the basis for the drugs and vaccines development.

HIV Tat Protein Induces Myocardial Fibrosis Through TGF-β1-CTGF Signaling Cascade: A Potential Mechanism of HIV Infection-Related Cardiac Manifestations

Human immunodeficiency virus (HIV) infection is a risk factor of cardiovascular diseases (CVDs). HIV-infected patients exhibit cardiac dysfunction coupled with cardiac fibrosis. However, the reason why HIV could induce cardiac fibrosis remains largely unexplored. HIV-1 trans-activator of transcription (Tat) protein is a regulatory protein, which plays a critical role in the pathogenesis of various HIV-related complications. In the present study, recombinant Tat was administered to mouse myocardium or neonatal mouse cardiac fibroblasts in different doses. Hematoxylin-eosin and Masson's trichrome staining were performed to observe the histological changes of mice myocardial tissues. EdU staining and MTS assay were used to evaluate the proliferation and viability of neonatal mouse cardiac fibroblasts, respectively. Real-time PCR and western blot analysis were used to detect CTGF, TGF-β1, and collagen I mRNA and protein expression levels, respectively. The results showed that Tat promoted the occurrence of myocardial fibrosis in mice. Also, we found that Tat increased the proliferative ability and the viability of neonatal mouse cardiac fibroblasts. The protein and mRNA expression levels of TGF-β1 and CTGF were significantly upregulated both in Tat-treated mouse myocardium and neonatal mouse cardiac fibroblasts. However, co-administration of TGF-β inhibitor abrogated the enhanced expression of collagen I induced by Tat in neonatal mouse cardiac fibroblasts. In conclusion, Tat contributes to HIV-related cardiac fibrosis through enhanced TGF-β1-CTGF signaling cascade.

Prevalence of Dyslipidemia in HIV-Positive Women with HPV Coinfection: A Preliminary Study

OBJECTIVE

The present study aimed to evaluate the lipid profile and atherogenic indexes in HIV-positive women with and without coinfection with human papillomavirus.

METHODS

Preliminary study was conducted with HIV-positive women. Laboratory tests (lipid profile, glycid profile, and atherogenic indexes) and detection of human papillomavirus (nested PCR technique using PGMY 09 and 11 primers, GP+5, and GP+6) were performed. For the analysis of the results, the data were categorized into two groups: with coinfection (HIV+/HPV+) and without coinfection (HIV+/HPV-).

RESULTS

Eighty-two HIV-positive women, aged between 35 and 49 years, participated in this study among whom 50% had HPV coinfection (HIV+/HPV+). Regarding comorbidities, there was a predominance of dyslipidemia (46.3%). The analysis of laboratory determinations and atherogenic indexes showed statistical relevance in the serum concentrations of total cholesterol (p=0.04), LDL cholesterol (p=0.03), and non-HDL cholesterol (p=0.04), as well as for the Castelli I index, Castelli II index, and atherogenic coefficient (p=0.04, 0.04, and 0.03, respectively).

CONCLUSION

The present study demonstrated a correlation between the lipid profile and atherogenic indexes with HIV/HPV coinfection, demonstrating a possible synergy between these viruses. However, further studies in this area must be carried out.

Chronic Exposure to HIV-Derived Protein Tat Impairs Endothelial Function via Indirect Alteration in Fat Mass and Nox1-Mediated Mechanisms in Mice

People living with human immunodeficiency virus (HIV) (PLWH) have increased risk for atherosclerosis-related cardiovascular disease (CVD), the main cause of death in this population. Notwithstanding, the mechanisms of HIV-associated vascular pathogenesis are not fully elucidated. Therefore, we sought to determine whether HIV-regulatory protein Tat mediates HIV-induced endothelial dysfunction via NADPH oxidase 1 (Nox1)-dependent mechanisms. Body weight, fat mass, leptin levels, expression of reactive oxygen species (ROS)-producing enzymes and vascular function were assessed in C57BL/6 male mice treated with Tat for 3 days and 4 weeks. Aortic rings and human endothelial cells were also treated with Tat for 2–24 h in ex vivo and in vitro settings. Chronic (4 weeks) but not acute (3 days and 2–24 h) treatment with Tat decreased body weight, fat mass, and leptin levels and increased the expression of Nox1 and its coactivator NADPH oxidase Activator 1 (NoxA1). This was associated with impaired endothelium-dependent vasorelaxation. Importantly, specific inhibition of Nox1 with GKT771 and chronic leptin infusion restored endothelial function in Tat-treated mice. These data rule out direct effects of HIV-Tat on endothelial function and imply the contribution of reductions in adipose mass and leptin production which likely explain upregulated expression of Nox1 and NoxA1. The Nox1 and leptin system may provide potential targets to improve vascular function in HIV infection-associated CVD.

New insights into pathogenesis point to HIV-1 Tat as a key vaccine target

Despite over 30 years of enormous effort and progress in the field, no preventative and/or therapeutic vaccines against human immunodeficiency virus (HIV) are available. Here, we briefly summarize the vaccine strategies and vaccine candidates that in recent years advanced to efficacy trials with mostly unsatisfactory results. Next, we discuss a novel and somewhat contrarian approach based on biological and epidemiological evidence, which led us to choose the HIV protein Tat for the development of preventive and therapeutic HIV vaccines. Toward this goal, we review here the role of Tat in the virus life cycle as well as experimental and epidemiological evidence supporting its key role in the natural history of HIV infection and comorbidities. We then discuss the preclinical and clinical development of a Tat therapeutic vaccine, which, by improving the functionality and homeostasis of the immune system and by reducing the viral reservoir in virologically suppressed vaccinees, helps to establish key determinants for intensification of combination antiretroviral therapy (cART) and a functional cure. Future developments and potential applications of the Tat therapeutic vaccine are also discussed, as well as the rationale for its use in preventative strategies. We hope this contribution will lead to a reconsideration of the current paradigms for the development of HIV/AIDS vaccines, with a focus on targeting of viral proteins with key roles in HIV pathogenesis.

Platelets in HIV: A Guardian of Host Defence or Transient Reservoir of the Virus?

The immune and inflammatory responses of platelets to human immunodeficiency virus 1 (HIV-1) and its envelope proteins are of great significance to both the treatment of the infection, and to the comorbidities related to systemic inflammation. Platelets can interact with the HIV-1 virus itself, or with viral membrane proteins, or with dysregulated inflammatory molecules in circulation, ensuing from HIV-1 infection. Platelets can facilitate the inhibition of HIV-1 infection via endogenously-produced inhibitors of HIV-1 replication, or the virus can temporarily hide from the immune system inside platelets, whereby platelets act as HIV-1 reservoirs. Platelets are therefore both guardians of the host defence system, and transient reservoirs of the virus. Such reservoirs may be of particular significance during combination antiretroviral therapy (cART) interruption, as it may drive viral persistence, and result in significant implications for treatment. Both HIV-1 envelope proteins and circulating inflammatory molecules can also initiate platelet complex formation with immune cells and erythrocytes. Complex formation cause platelet hypercoagulation and may lead to an increased thrombotic risk. Ultimately, HIV-1 infection can initiate platelet depletion and thrombocytopenia. Because of their relatively short lifespan, platelets are important signalling entities, and could be targeted more directly during HIV-1 infection and cART.

In vitro Anti-HIV-1 Activity of the Recombinant HIV-1 TAT Protein Along With Tenofovir Drug

BACKGROUND

HIV-1 TAT protein is essential for the regulation of viral genome transcription. The first exon of TAT protein has a fundamental role in the stimulation of the extrinsic and intrinsic apoptosis pathways, but its anti-HIV activity is not clear yet.

METHODS

In the current study, we firstly cloned the first exon of the TAT coding sequence in the pET-24a expression vector and then protein expression was done in the Rosetta expression host. Next, the expressed TAT protein was purified by Ni-NTA column under native conditions. After that, the protein yield was determined by Bradford kit and NanoDrop spectrophotometry. Finally, the cytotoxicity effect and anti-Scr-HIV-1 activity of the recombinant TAT protein alone and along with Tenofovir drug were assessed by MTT and ELISA, respectively.

RESULTS

The recombinant TAT protein was successfully generated in E. coli, as confirmed by 13.5% SDS-PAGE and western blotting. The protein yield was ~150-200 μg/ml. In addition, the recombinant TAT protein at a certain dose with low toxicity could suppress Scr-HIV replication in the infected HeLa cells (~30%) that was comparable with a low toxic dose of Tenofovir drug (~40%). It was interesting that the recombinant TAT protein could enhance anti-HIV potency of Tenofovir drug up to 66%.

CONCLUSION

Generally, a combination of TAT protein and Tenofovir drug could significantly inhibit HIV-1 replication. It will be required to determine their mechanism of action in the next studies.

The role of soluble E-selectin in HIV associated preeclampsia

OBJECTIVE

To determine the serum concentration of soluble E-selectin (sE-selectin) in HIV associated preeclampsia.

STUDY DESIGN

The study population (n = 72) consisted of normotensive pregnant (n = 36) and preeclamptic (n = 36) women stratified by HIV status (negative vs. positive). Serum concentrations of sE-selectin were quantified using the MilliPlex multiplex immunoassay method. Statistical analyses were conducted using GraphPad Prism software.

RESULTS

When stratified by pregnancy type and HIV status, serum sE-selectin levels were elevated in the preeclamptic HIV-negative group compared to the normotensive HIV-negative group (p = 0.0070**). Gestational age, systolic blood pressure, diastolic blood pressure and baby weight were statistically different across the study groups (p < 0.0001).

CONCLUSION

This study demonstrates an elevation of sE-selectin in preeclamptic HIV-negative compared to the normotensive HIV-negative group. However, when stratified by HIV status, there was no significant difference observed in preeclamptic HIV-positive and normotensive HIV-positive groups. The findings of this small-scale study suggest that sE-selectin may be used as a biomarker or an early identifier of preeclampsia. Studies with large numbers should be considered to confirm our findings.

HIV-1 Tat: Role in Bystander Toxicity

HIV Tat protein is a critical protein that plays multiple roles in HIV pathogenesis. While its role as the transactivator of HIV transcription is well-established, other non-viral replication-associated functions have been described in several HIV-comorbidities even in the current antiretroviral therapy (ART) era. HIV Tat protein is produced and released into the extracellular space from cells with active HIV replication or from latently HIV-infected cells into neighboring uninfected cells even in the absence of active HIV replication and viral production due to effective ART. Neighboring uninfected and HIV-infected cells can take up the released Tat resulting in the upregulation of inflammatory genes and activation of pathways that leads to cytotoxicity observed in several comorbidities such as HIV associated neurocognitive disorder (HAND), HIV associated cardiovascular impairment, and accelerated aging. Thus, understanding how Tat modulates host and viral response is important in designing novel therapeutic approaches to target the chronic inflammatory effects of soluble viral proteins in HIV infection.

Early Insights into COVID-19 in Persons Living with HIV and Cardiovascular Manifestations

Persons living with HIV-1 (PLHIV) are at increased risk of cardiovascular complications in part due to the persistent inflammatory state despite viral suppression. SARS-CoV-2, the virus causing COVID-19, was declared a pandemic virus in March 2020, and caused over 30 million cases and 900,000 deaths worldwide to date. Individuals with COVID-19 are manifesting acute cardiovascular complications because of the inflammatory response associated with SARS-CoV-2 infection. It is not yet known whether having COVID-19 in the context of ongoing HIV-1 infection results in worse cardiovascular complications than in PLHIV who have not had COVID-19 infection. In this review, the potential for exacerbated cardiovascular manifestations in persons coinfected with HIV-1 and COVID-19 is considered.

Abnormal Dispersion of Ventricular Repolarization as a Risk Factor in Patients with Human Immunodeficiency Virus: Tp-e Interval, Tp-e/QTc Ratio

OBJECTIVE

In recent years, there has been worldwide recognition of the problems associated with Human Immunodeficiency Virus (HIV) infection and Acquired Immune Deficiency Syndrome (AIDS). The prevalence of cardiovascular disease in the HIV-infected population is increasing. Repolarization abnormalities, the significant contributor to life-threatening arrhythmias and mortality, are the most frequent electrocardiographic changes in this population. This study aimed to evaluate the changes in Tp-e interval, Tp-e/QT and Tp-e/corrected QT (QTc) ratios, and traditional electrocardiographic features of electrical dispersion in adults infected with HIV.

SUBJECTS AND METHODS

A total of 235 participants were selected in the current study. The HIV group consisted of 85 subjects (median age 36 years [25-48], and the control group included 150 individuals (median age 39 years [27-51]). Tp-e interval, Tp-e/QT and Tp-e/QTc ratios were measured by the 12-lead electrocardiogram.

RESULTS

Tp-e interval, cTp-e interval, and Tp-e/QT and Tp-e/QTc ratios were significantly higher in HIV patients compared to the control group (p = 0.006, p = 0.004, p = 0.003, and p = 0.002, respectively). In correlation analysis, there was inverse correlation between the mean cTp-e interval and CD4 count and Tp-e/QTc ratios and CD4 count (r = - 0.407, p < 0.001, r = - 0.416, p < 0.001, respectively). Besides, there was correlation between the mean cTp-e interval and high-sensitivity C-reactive protein (hsCRP) and Tp-e/QTc ratios and hsCRP (r = 0.403, p = 0.001, r = 0.406, p = 0.001, respectively).

CONCLUSION

Our study revealed that the cTp-e interval, Tp-e/QT and cTp-e/QT ratios were prolonged and correlated to the severity of the disease in HIV-infected patients. Our findings may shed light on the cTp-e interval and Tp-e/QTc ratio and lead to further studies showing a relationship with ventricular arrhythmias and mortality in HIV-infected individuals.

Repression of Nrf2/ARE regulated antioxidant genes and dysregulation of the cellular redox environment by the HIV Transactivator of Transcription

Chronic HIV infection in the era of anti-retroviral therapy is associated with dramatically increased risk of developing severe cardio pulmonary disease. Common to these diseases is increased oxidative burden and chronic inflammation despite low viremia and restoration of CD4⁺ T-cell levels. Soluble viral factors are heavily implicated in these disease processes, including the HIV Transactivator of Transcription (Tat). Tat is produced in high levels during infection and secreted from infected cells into circulation where it is internalized by bystander cells and is known to regulate inflammatory pathways and elicit a pro-oxidant environment. We have examined the effects of Tat on the anti-oxidant regulatory network driven by the transcription factor Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in primary human pulmonary arterial endothelial cells, which are heavily involved in pathogenesis of HIV associated lung diseases including pulmonary arterial hypertension and COPD. Co-expression of Tat and a luciferase reporter construct driven by the Nrf2 activated anti-oxidant response element (ARE) demonstrated markedly reduced Nrf2/ARE activity, even when stimulated by the potent Nrf2 activating compound PB125. Additionally, Heme-oxygenase-1 (HO-1) transcription was potently repressed by Tat in a cell line as well as primary endothelial cells, and treatment with PB125 failed to restore transcriptional activity. Other anti-oxidant Nrf2 genes examined included NADPH Dehydrogenase Quinone 1 (NQO1) and Sulfiredoxin-1 (SRXN1). NQO1 was repressed basally by Tat, while SRXN1 transcription was refractory to activation by PB125 in the presence of Tat. Lastly, we demonstrated that Tat expressing cells have increased indicators of oxidative stress including elevated production of reactive oxygen species, measured by electron paramagnetic resonance spectroscopy, and increased levels of nitrotyrosine content. These observations suggest a novel mechanism by which HIV Tat increases oxidative burden by dysregulation of the Nrf2/ARE pathway.

Mechanisms of Arrhythmia and Sudden Cardiac Death in Patients With HIV Infection

Long-term survival of HIV-infected patients has significantly improved with the use of antiretroviral therapy (ART). As a consequence, cardiovascular diseases are now emerging as an important clinical problem in this population. Sudden cardiac death is the third leading cause of mortality in HIV patients. Twenty percent of patients with HIV who died of sudden cardiac death had previous cardiac arrhythmias including ventricular tachycardia, atrial fibrillation, and other unspecified rhythm disorders. This review presents a summary of HIV-related arrhythmias, associated risk factors specific to the HIV population, and underlying mechanisms. Compared with the general population, patients with HIV have several cardiac conditions and electrophysiological abnormalities. As a result, they have an increased risk of developing severe arrhythmias, that can lead to sudden cardiac death. Possible explanations may be related to non-ART polypharmacy, electrolyte imbalances, and use of substances observed in HIV-infected patients; many of these conditions are associated with alterations in cardiac electrical activity, increasing the risk of arrhythmia and sudden cardiac death. However, clinical and experimental evidence has also revealed that cardiac arrhythmias occur in HIV-infected patients, even in the absence of drugs. This indicates that HIV itself can change the electrophysiological properties of the heart profoundly and cause cardiac arrhythmias and related sudden cardiac death. The current knowledge of the underlying mechanisms, as well as the emerging role of inflammation in these arrhythmias, are discussed here.