Hiv Tat protein causes endothelial dysfunction in porcine coronary arteries

Inflammation in HIV and Its Impact on Atherosclerotic Cardiovascular Disease

People living with HIV have a 1.5- to 2-fold increased risk of developing cardiovascular disease. Despite treatment with highly effective antiretroviral therapy, people living with HIV have chronic inflammation that makes them susceptible to multiple comorbidities. Several factors, including the HIV reservoir, coinfections, clonal hematopoiesis of indeterminate potential (CHIP), microbial translocation, and antiretroviral therapy, may contribute to the chronic state of inflammation. Within the innate immune system, macrophages harbor latent HIV and are among the prominent immune cells present in atheroma during the progression of atherosclerosis. They secrete inflammatory cytokines such as IL (interleukin)-6 and tumor necrosis-α that stimulate the expression of adhesion molecules on the endothelium. This leads to the recruitment of other immune cells, including cluster of differentiation (CD)8+ and CD4+ T cells, also present in early and late atheroma. As such, cells of the innate and adaptive immune systems contribute to both systemic inflammation and vascular inflammation. On a molecular level, HIV-1 primes the NLRP3 (NLR family pyrin domain containing 3) inflammasome, leading to an increased expression of IL-1β, which is important for cardiovascular outcomes. Moreover, activation of TLRs (toll-like receptors) by HIV, gut microbes, and substance abuse further activates the NLRP3 inflammasome pathway. Finally, HIV proteins such as Nef (negative regulatory factor) can inhibit cholesterol efflux in monocytes and macrophages through direct action on the cholesterol transporter ABCA1 (ATP-binding cassette transporter A1), which promotes the formation of foam cells and the progression of atherosclerotic plaque. Here, we summarize the stages of atherosclerosis in the context of HIV, highlighting the effects of HIV, coinfections, and antiretroviral therapy on cells of the innate and adaptive immune system and describe current and future interventions to reduce residual inflammation and improve cardiovascular outcomes among people living with HIV.

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.

Genetic Appraisal of RAAS-Associated SNPs: REN (rs16853055), AGT (rs3789678) and ACE (rs4305) in Preeclamptic Women Living with HIV Infection

PURPOSE OF REVIEW

The primary goal of this review article was to determine whether the three RAAS-associated SNPs, Renin-rs16853055, AGT-rs3789678 and ACE-rs4305 are genetically linked to the development of hypertension in preeclampsia. The secondary goal was to establish if there was a link between these SNPs and HIV infection.

RECENT FINDINGS

There is a paucity of findings related to the aforementioned SNPs and preeclampsia. There are no recent findings on the rs16853055 renin polymorphism. The rs3789678 angiotensinogen polymorphism correlated significantly with gestational hypertension. The rs4305 ACE polymorphism showed no significant association with the development of pregnancy-induced hypertension. There are conflicting findings when determining the relationship between ethnicity and the predisposition of preeclampsia and hypertension in relation to the discussed RAAS-associated SNPs. To date, the association between RAAS-associated SNPs and preeclamptic women co-morbid with HIV in South Africa has revealed that certain alleles of the AGT gene are more prominent in HIV-infected PE compared to normotensive pregnant HIV-infected women.

White and Gray Matter Changes are Associated With Neurocognitive Decline in HIV Infection

OBJECTIVE

To investigate the relationship between neurocognitive deficits and structural changes on brain magnetic resonance imaging in people living with HIV (PLWH) with good virological control on combination antiretroviral therapy, compared with socioeconomically matched control participants recruited from the same communities.

METHODS

Brain magnetic resonance imaging scans, and clinical and neuropsychological data were obtained from virologically controlled PLWH (viral load of <50 c/mL and at least 1 year of combination antiretroviral therapy) and socioeconomically matched control participants. Magnetic resonance imaging was carried out on 3 T scanner with 8-channel head coils and segmented using Classification using Derivative-based Features. Multiple regression analysis was performed to examine the association between brain volume and various clinical and neuropsychiatric parameters adjusting for age, race, and sex. To evaluate longitudinal changes in brain volumes, a random coefficient model was used to evaluate the changes over time (age) adjusting for sex and race.

RESULTS

The cross-sectional study included 164 PLWH and 51 controls, and the longitudinal study included 68 PLWH and 20 controls with 2 or more visits (mean 2.2 years, range 0.8-5.1 years). Gray matter (GM) atrophy rate was significantly higher in PLWH compared with control participants, and importantly, the GM and global atrophy was associated with the various neuropsychological domain scores. Higher volume of white matter hyperintensities were associated with increased atherosclerotic cardiovascular disease risk score, and decreased executive functioning and memory domain scores in PLWH.

INTERPRETATION

These findings suggest ongoing neurological damage even in virologically controlled participants, with significant implications for clinical management of PLWH. ANN NEUROL 2024;95:941-950.

Mechanisms and Cardiorenal Complications of Chronic Anemia in People with HIV

Chronic anemia is more prevalent in people living with HIV (PLWH) compared to the general population. The mechanisms that drive chronic anemia in HIV are multifaceted and include functional impairment of hematopoietic stem cells, dysregulation of erythropoietin production, and persistent immune activation. Chronic inflammation from HIV infection adversely affects erythropoiesis, erythrocyte lifespan, and erythropoietin response, leading to a heightened risk of co-infections such as tuberculosis, persistent severe anemia, and increased mortality. Additionally, chronic anemia exacerbates the progression of HIV-associated nephrotoxicity and contributes to cardiovascular risk through immune activation and inflammation. This review highlights the cardinal role of chronic inflammation as a link connecting persistent anemia and cardiovascular complications in PLWH, emphasizing the need for a universal understanding of these interconnected pathways for targeted interventions.

Potential Pathways and Pathophysiological Implications of Viral Infection-Driven Activation of Kallikrein-Kinin System (KKS)

Microcirculatory and coagulation disturbances commonly occur as pathological manifestations of systemic viral infections. Research exploring the role of the kallikrein-kinin system (KKS) in flavivirus infections has recently linked microvascular dysfunctions to bradykinin (BK)-induced signaling of B2R, a G protein-coupled receptor (GPCR) constitutively expressed by endothelial cells. The relevance of KKS activation as an innate response to viral infections has gained increasing attention, particularly after the reports regarding thrombogenic events during COVID-19. BK receptor (B2R and B1R) signal transduction results in vascular permeability, edema formation, angiogenesis, and pain. Recent findings unveiling the role of KKS in viral pathogenesis include evidence of increased activation of KKS with elevated levels of BK and its metabolites in both intravascular and tissue milieu, as well as reports demonstrating that virus replication stimulates BKR expression. In this review, we will discuss the mechanisms triggered by virus replication and by virus-induced inflammatory responses that may stimulate KKS. We also explore how KKS activation and BK signaling may impact virus pathogenesis and further discuss the potential therapeutic application of BKR antagonists in the treatment of hemorrhagic and respiratory diseases.

Neuropilin-1 in the pathogenesis of preeclampsia, HIV-1, and SARS-CoV-2 infection: A review

This review explores the role of transmembrane neuropilin-1 (NRP-1) in pregnancy, preeclampsia (PE), human immunodeficiency virus type 1 (HIV-1) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Since these conditions are assessed independently, this review attempts to predict their comorbid clinical manifestations. Dysregulation of NRP-1 contributes to the pathogenesis of PE by (a) impairing vascular endothelial growth factor (VEGF) signaling for adequate spiral artery remodeling and placentation, (b) inducing syncytiotrophoblast (ST) cell apoptosis and increasing ST-derived microparticle circulation and (c) by decreasing regulatory T cell activity predisposing maternal immune intolerance. Although NRP-1 is upregulated in SARS-CoV-2 placentae, its exploitation for SARS-CoV-2 internalization and increased infectivity may alter angiogenesis through the competitive inhibition of VEGF. The anti-inflammatory nature of NRP-1 may aid its upregulation in HIV-1 infection; however, the HIV-accessory protein, tat, reduces NRP-1 expression. Upregulated NRP-1 in macrophages and dendritic cells also demonstrated HIV-1 resistance/reduced infectivity. Notably, HIV-1-infected pregnant women receiving antiretroviral therapy (ART) to prevent vertical transmission may experience immune reconstitution, impaired decidualization, and elevated markers of endothelial injury. Since endothelial dysfunction and altered immune responses are central to PE, HIV-1 infection, ART usage and SARS-CoV-2 infection, it is plausible that an exacerbation of both features may prevail in the synergy of these events. Additionally, this review identifies microRNAs (miRNAs) mediating NRP-1 expression. MiR-320 and miR-141 are overexpressed in PE, while miR-206 and miR-124-3p showed increased expression in PE and HIV-1 infection. Additionally, miR-214 is overexpressed in PE, HIV-1 and SARS-CoV-2 infection, implicating treatment strategies to reduce these miRNAs to upregulate and normalize NRP-1 expression. However, inconsistencies in the data of the role and regulation of miRNAs in PE, HIV-1 and SARS-CoV-2 infections require clarification. This review provides a platform for early diagnosis and potential therapeutic intervention of PE, HIV-1, and SARS-CoV-2 infections independently and as comorbidities.

Immunosenescence in atherosclerosis: A role for chronic viral infections

Immune system is a versatile and dynamic body organ which offers survival and endurance of human beings in their hostile living environment. However, similar to other cells, immune cells are hijacked by senescence. The ageing immune cells lose their beneficial functions but continue to produce inflammatory mediators which draw other immune and non-immune cells to the senescence loop. Immunosenescence has been shown to be associated with different pathological conditions and diseases, among which atherosclerosis has recently come to light. There are common drivers of both immunosenescence and atherosclerosis; e.g. inflammation, reactive oxygen species (ROS), chronic viral infections, genomic damage, oxidized-LDL, hypertension, cigarette smoke, hyperglycaemia, and mitochondrial failure. Chronic viral infections induce inflammaging, sustained cytokine signaling, ROS generation and DNA damage which are associated with atherogenesis. Accumulating evidence shows that several DNA and RNA viruses are stimulators of immunosenescence and atherosclerosis in an interrelated network. DNA viruses such as CMV, EBV and HBV upregulate p16, p21 and p53 senescence-associated molecules; induce inflammaging, metabolic reprogramming of infected cells, replicative senescence and telomere shortening. RNA viruses such as HCV and HIV induce ROS generation, DNA damage, induction of senescence-associated secretory phenotype (SASP), metabolic reprogramming of infected cells, G1 cell cycle arrest, telomere shortening, as well as epigenetic modifications of DNA and histones. The newly emerged SARS-CoV-2 virus is also a potent inducer of cytokine storm and SASP. The spike protein of SARS-CoV-2 promotes senescence phenotype in endothelial cells by augmenting p16, p21, senescence-associated β-galactosidase (SA-β-Gal) and adhesion molecules expression. The impact of SARS-CoV-2 mega-inflammation on atherogenesis, however, remains to be investigated. In this review we focus on the common processes in immunosenescence and atherogenesis caused by chronic viral infections and discuss the current knowledge on this topic.

HIV and Schistosoma Co-Exposure Leads to Exacerbated Pulmonary Endothelial Remodeling and Dysfunction Associated with Altered Cytokine Landscape

HIV and Schistosoma infections have been individually associated with pulmonary vascular disease. Co-infection with these pathogens is very common in tropical areas, with an estimate of six million people co-infected worldwide. However, the effects of HIV and Schistosoma co-exposure on the pulmonary vasculature and its impact on the development of pulmonary vascular disease are largely unknown. Here, we have approached these questions by using a non-infectious animal model based on lung embolization of Schistosoma mansoni eggs in HIV-1 transgenic (HIV) mice. Schistosome-exposed HIV mice but not wild-type (Wt) counterparts showed augmented pulmonary arterial pressure associated with markedly suppressed endothelial-dependent vasodilation, increased endothelial remodeling and vessel obliterations, formation of plexiform-like lesions and a higher degree of perivascular fibrosis. In contrast, medial wall muscularization was similarly increased in both types of mice. Moreover, HIV mice displayed an impaired immune response to parasite eggs in the lung, as suggested by decreased pulmonary leukocyte infiltration, small-sized granulomas, and augmented residual egg burden. Notably, vascular changes in co-exposed mice were associated with increased expression of proinflammatory and profibrotic cytokines, including IFN-γ and IL-17A in CD4⁺ and γδ T cells and IL-13 in myeloid cells. Collectively, our study shows for the first time that combined pulmonary persistence of HIV proteins and Schistosoma eggs, as it may occur in co-infected people, alters the cytokine landscape and targets the vascular endothelium for aggravated pulmonary vascular pathology. Furthermore, it provides an experimental model for the understanding of pulmonary vascular disease associated with HIV and Schistosoma co-morbidity.

Viral Endothelial Dysfunction: A Unifying Mechanism for COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible virus with significant global impact, morbidity, and mortality. The SARS-CoV-2 virus may result in widespread organ manifestations including acute respiratory distress syndrome, acute renal failure, thromboembolism, and myocarditis. Virus-induced endothelial injury may cause endothelial activation, increased permeability, inflammation, and immune response and cytokine storm. Endothelial dysfunction is a systemic disorder that is a precursor of atherosclerotic vascular disease that is associated with cardiovascular risk factors and is highly prevalent in patients with atherosclerotic cardiovascular and peripheral disease. Several studies have associated various viral infections including SARS-CoV-2 infection with inflammation, endothelial dysfunction, and subsequent innate immune response and cytokine storm. Noninvasive monitoring of endothelial function and identification of high-risk patients who may require specific therapies may have the potential to improve morbidity and mortality associated with subsequent inflammation, cytokine storm, and multiorgan involvement.

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.

Role of Brain Arterial Remodeling in HIV-Associated Cerebrovascular Outcomes

As the life expectancy of people living with HIV (PLWH) on combination antiretroviral therapy (cART) increases, so does morbidity from cerebrovascular disease and neurocognitive disorders. Brain arterial remodeling stands out as a novel investigational target to understand the role of HIV in cerebrovascular and neurocognitive outcomes. We therefore conducted a review of publications in PubMed, EMBASE, Web of Science and Wiley Online Library, from inception to April 2021. We included search terms such as HIV, cART, brain, neuroimmunity, arterial remodeling, cerebrovascular disease, and neurocognitive disorders. The literature shows that, in the post-cART era, PLWH continue to experience an increased risk of stroke and neurocognitive disorders (albeit milder forms) compared to uninfected populations. PLWH who are immunosuppressed have a higher proportion of hemorrhagic strokes and strokes caused by opportunistic infection and HIV vasculopathy, while PLWH on long-term cART have higher rates of ischemic strokes, compared to HIV-seronegative controls. Brain large artery atherosclerosis in PLWH is associated with lower CD4 nadir and higher CD4 count during the stroke event. HIV vasculopathy, a form of non-atherosclerotic outward remodeling, on the other hand, is associated with protracted immunosuppression. HIV vasculopathy was also linked to a thinner media layer and increased adventitial macrophages, suggestive of non-atherosclerotic degeneration of the brain arterial wall in the setting of chronic central nervous system inflammation. Cerebrovascular architecture seems to be differentially affected by HIV infection in successfully treated versus immunosuppressed PLWH. Brain large artery atherosclerosis is prevalent even with long-term immune reconstitution post-cART. HIV-associated changes in brain arterial walls may also relate to higher rates of HIV-associated neurocognitive disorders, although milder forms are more prevalent in the post-cART era. The underlying mechanisms of HIV-associated pathological arterial remodeling remain poorly understood, but a role has been proposed for chronic HIV-associated inflammation with increased burden on the vasculature. Neuroimaging may come to play a role in assessing brain arterial remodeling and stratifying cerebrovascular risk, but the data remains inconclusive. An improved understanding of the different phenotypes of brain arterial remodeling associated with HIV may reveal opportunities to reduce rates of cerebrovascular disease in the aging population of PLWH on cART.

Latent HIV-Exosomes Induce Mitochondrial Hyperfusion Due to Loss of Phosphorylated Dynamin-Related Protein 1 in Brain Endothelium

Damage to the cerebral vascular endothelium is a critical initiating event in the development of HIV-1-associated neurocognitive disorders. To study the role of mitochondria in cerebral endothelial dysfunction, we investigated how exosomes, isolated from both cell lines with integrated provirus and HIV-1 infected primary cells (HIV-exosomes), accelerate the dysfunction of primary human brain microvascular endothelial cells (HBMVECs) by inducing mitochondrial hyperfusion, and reducing the expression of phosphorylated endothelial nitric oxide synthase (p-eNOS). The quantitative analysis of the extracellular vesicles (EVs) indicates that the isolated EVs were predominantly exosomes. It was further supported by the detection of exosomal markers, and the absence of large EV-related protein in the isolated EVs. The exosomes were readily taken up by primary HBMVECs. HIV-exosomes induce cellular and mitochondrial superoxide production but reduce mitochondrial membrane potential in HBMVECs. HIV-exosomes increase mitochondrial hyperfusion, possibly due to loss of phosphorylated dynamin-related protein 1 (p-DRP1). HIV-exosomes, containing the HIV-Tat protein, and viral Tat protein reduce the expression of p-DRP1 and p-eNOS, and accelerate brain endothelial dysfunction. Finally, exosomes isolated from HIV-1 infected primary human peripheral blood mononuclear cells (hPBMCs) produce more exosomes than uninfected controls and reduce both p-DRP1 and p-eNOS expressions in primary HBMVECs. Our novel findings reveal the significant role of HIV-exosomes on dysregulation of mitochondrial function, which induces adverse changes in the function of the brain microvascular endothelium.

Maternal endothelial dysfunction in HIV-associated preeclampsia comorbid with COVID-19: a review

This review assesses markers of endothelial dysfunction (ED) associated with the maternal syndrome of preeclampsia (PE). We evaluate the role of antiretroviral therapy (ART) in human immunodeficiency virus (HIV)-infected preeclamptic women. Furthermore, we briefly discuss the potential of lopinavir/ritonavir (LPV/r), dolutegravir (DTG) and remdesivir (RDV) in drug repurposing and their safety in pregnancy complicated by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In HIV infection, the trans-activator of transcription protein, which has homology with vascular endothelial growth factor, impairs angiogenesis, leading to endothelial injury and possible PE development despite neutralization of their opposing immune states. Markers of ED show strong evidence supporting the adverse role of ART in PE development and mortality compared to treatment-naïve pregnancies. Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2 infection, exploits angiotensin-converting enzyme 2 (ACE 2) to induce ED and hypertension, thereby mimicking angiotensin II-mediated PE in severe cases of infection. Upregulated ACE 2 in pregnancy is a possible risk factor for SARS-CoV-2 infection and subsequent PE development. The potential effectiveness of LPV/r against COVID-19 is inconclusive; however, defective decidualization, along with elevated markers of ED, was observed. Therefore, the safety of these drugs in HIV-positive pregnancies complicated by COVID-19 requires attention. Despite the observed endothelial protective properties of DTG, there is a lack of evidence of its effects on pregnancy and COVID-19 therapeutics. Understanding RDV-ART interactions and the inclusion of pregnant women in antiviral drug repurposing trials is essential. This review provides a platform for further research on PE in the HIV-COVID-19 syndemic.

HIV Protein Tat Induces Macrophage Dysfunction and Atherosclerosis Development in Low-Density Lipoprotein Receptor-Deficient Mice

PURPOSE

HIV infection is consistently associated with an increased risk of atherosclerotic cardiovascular disease, but the underlying mechanisms remain elusive. HIV protein Tat, a transcriptional activator of HIV, has been shown to activate NF-κB signaling and promote inflammation in vitro. However, the atherogenic effects of HIV Tat have not been investigated in vivo. Macrophages are one of the major cell types involved in the initiation and progression of atherosclerosis. We and others have previously revealed the important role of IκB kinase β (IKKβ), a central inflammatory coordinator through activating NF-κB, in the regulation of macrophage functions and atherogenesis. This study investigated the impact of HIV Tat exposure on macrophage functions and atherogenesis.

METHODS

To investigate the effects of Tat on macrophage IKKβ activation and atherosclerosis development in vivo, myeloid-specific IKKβ-deficient LDLR-deficient (IKKβ^ΔMyeLDLR^-/-) mice and their control littermates (IKKβ^F/FLDLR^-/-) were exposed to recombinant HIV protein Tat.

RESULTS

Exposure to Tat significantly increased atherosclerotic lesion size and plaque vulnerability in IKKβ^F/FLDLR^-/- but not IKKβ^ΔMyeLDLR^-/- mice. Deficiency of myeloid IKKβ attenuated Tat-elicited macrophage inflammatory responses and atherosclerotic lesional inflammation in IKKβ^ΔMyeLDLR^-/- mice. Further, RNAseq analysis demonstrated that HIV protein Tat affects the expression of many atherosclerosis-related genes in vitro in an IKKβ-dependent manner.

CONCLUSIONS

Our findings reveal atherogenic effects of HIV protein Tat in vivo and demonstrate a pivotal role of myeloid IKKβ in Tat-driven atherogenesis.

Chronic Nucleoside Reverse Transcriptase Inhibitors Disrupt Mitochondrial Homeostasis and Promote Premature Endothelial Senescence

Combination antiretroviral therapy (cART) has improved the life expectancy of HIV patients, thus increasing the number of people living with HIV (PLWH). However, cardiovascular diseases (CVD) are now one of the most prevalent causes of death among PLWH. Nucleoside reverse transcriptase inhibitors (NRTIs) are the backbone of cART, and the emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) coformulation is commonly used. In prior studies, acute NRTI treatment-induced endothelial dysfunction, increased reactive oxygen species production, and mitophagic activity, suggesting that mitochondrial dysfunction may be critical to NRTI-induced endothelial dysfunction. Mitochondrial dysfunction plays a causal role in endothelial senescence, whereas premature endothelial senescence can promote the development of CVD. We hypothesize that for chronic NRTI treatment, a disruption in mitochondrial homeostasis leads to premature endothelial senescence and predisposes PLWH to CVD. We used human aortic endothelial cells (HAEC) and HIV-1 transgenic (Tg26) mice to test the interrelationship between mitochondrial and vascular dysfunction after chronic NRTI treatment in vitro and in vivo. Mitochondrial DNA copy number was decreased in late-passage HAEC treated with NRTIs, and senescence-associated β-galactosidase accumulation was elevated. In late-passage HAEC, NRTIs decreased the activity of Parkin-mediated mitophagy. In Tg26 mice treated with FTC, plasma nitrite levels were decreased. Endothelium-dependent vasodilation in NRTI-treated Tg26 mice was also reduced. Our work suggests that long-term use of NRTI may disrupt mitochondrial homeostasis, induce premature endothelial senescence, and impair vascular function.

HIV-1-Associated Left Ventricular Cardiac Dysfunction in Humanized Mice

The molecular cause(s) for early onset heart failure in people living with HIV-1 infection (PLWH) remains poorly defined. Herein, longitudinal echocardiography was used to assess whether NOD.Cg-Prkdc^scid Il2rgt^m1Wjl/SzJ mice reconstituted with human hematopoietic stem cells (Hu-NSG mice) and infected with HIV-1_ADA can recapitulate the salient features of this progressive human disease. Four weeks post infection, Hu-NSG mice of both sexes developed left ventricular (LV) diastolic dysfunction (DD), with 25% exhibiting grade III/IV restrictive DD with mitral regurgitation. Increases in global longitudinal and circumferential strains and declines in LV ejection fraction and fractional shortening were observed eight weeks post infection. After twelve weeks of infection, 33% of Hu-NSG mice exhibited LV dyskinesia and dyssynchrony. Histopathological analyses of hearts seventeen weeks post infection revealed coronary microvascular leakage, fibrosis and immune cell infiltration into the myocardium. These data show for the first time that HIV-1_ADA-infected Hu-NSG mice can recapitulate key left ventricular cardiac deficits and pathophysiological changes reported in humans with progressive HIV-1 infection. The results also suggest that HIV-1 infected Hu-NSG mice may be a useful model to screen for pharmacological agents to blunt LV dysfunction and associated pathophysiologic causes reported in PLWH.

In-vivo MRI Reveals Changes to Intracerebral Vasculature Caliber in HIV Infection

Objective: To characterize cerebral arterial remodeling in HIV-infected (HIV+) individuals in-vivo, and to study its clinical and immunological associations.

Methods: T2^*-weighted magnetic resonance imagining sequences was used to determine cross-sectional area (vascular caliber) of the anterior (A1 segment) and middle (M1 segment) cerebral arteries in HIV- (control) and HIV+ subjects on antiretroviral therapy. Correlations of A1 caliber with clinical, demographic parameters, and immunological markers in cerebrospinal fluid (CSF) were determined using multivariable analyses.

Results: A1 and M1 calibers from 22 HIV- control subjects (age: median 48.5 years, range 22-60 years, 55% male) and 61 HIV+ subjects (age: median 53 years, range 25–60 years, 67% male) were studied. ANCOVA, adjusting for ethnicity and sex (age was not correlated with M1 or A1 caliber in either group), revealed that HIV+ subjects had larger caliber in the A1 segment than HIV- subjects (4.95 ± 0.14 mm², and 4.47 ± 0.21 mm² respectively, p = 0.048), but caliber of the M1 segment did not differ among the groups (7.21 ± 0.14 mm² and 7.09 ± 0.23 mm² respectively, p = 0.65). In the HIV+ cohort, longer disease duration and higher current CD4 T-cell count were associated with reduced A1 caliber (r =−0.42 and −0.33 respectively, p < 0.05). In addition, increase in cardiovascular disease risk (CVD risk) was associated with a decrease in A1 caliber in the HIV group (r = −0.35, p < 0.05).

Conclusions: This cross-sectional study reveals an increase in A1 caliber in the HIV+ cohort, compared to control subjects, which is especially prominent in early phase of the disease. This increase in caliber may be associated with acute pathological processes in HIV during the initial stages of infection resulting in loss of compliance or thinning of the arterial wall. At later stages, such changes may be confounded by arteriosclerotic changes that are common in later stages of HIV infection. This study suggests there is extensive vessel remodeling in various stages of infection. Long-term longitudinal follow-up of this cohort is planned to further verify this hypothesis and to better understand this MRI marker of intracranial vascular caliber.

Targeting the HIV-infected brain to improve ischemic stroke outcome

HIV-associated cerebrovascular events remain highly prevalent even in the current era of antiretroviral therapy (ART). We hypothesize that low-level HIV replication and associated inflammation endure despite antiretroviral treatment and affect ischemic stroke severity and outcomes. Using the EcoHIV infection model and the middle cerebral artery occlusion as the ischemic stroke model in mice, we present in vivo analysis of the relationship between HIV and stroke outcome. EcoHIV infection increases infarct size and negatively impacts tissue and functional recovery. Ischemic stroke also results in an increase in EcoHIV presence in the affected regions, suggesting post-stroke reactivation that magnifies pro-inflammatory status. Importantly, ART with a high CNS penetration effectiveness (CPE) is more beneficial than low CPE treatment in limiting tissue injury and accelerating post-stroke recovery. These results provide potential insight for treatment of HIV-infected patients that are at risk of developing cerebrovascular disease, such as ischemic stroke.

Genetic variation and function of the HIV-1 Tat protein

Human immunodeficiency virus type 1 (HIV-1) encodes a transactivator of transcription (Tat) protein, which has several functions that promote viral replication, pathogenesis, and disease. Amino acid variation within Tat has been observed to alter the functional properties of Tat and, depending on the HIV-1 subtype, may produce Tat phenotypes differing from viruses' representative of each subtype and commonly used in in vivo and in vitro experimentation. The molecular properties of Tat allow for distinctive functional activities to be determined such as the subcellular localization and other intracellular and extracellular functional aspects of this important viral protein influenced by variation within the Tat sequence. Once Tat has been transported into the nucleus and becomes engaged in transactivation of the long terminal repeat (LTR), various Tat variants may differ in their capacity to activate viral transcription. Post-translational modification patterns based on these amino acid variations may alter interactions between Tat and host factors, which may positively or negatively affect this process. In addition, the ability of HIV-1 to utilize or not utilize the transactivation response (TAR) element within the LTR, based on genetic variation and cellular phenotype, adds a layer of complexity to the processes that govern Tat-mediated proviral DNA-driven transcription and replication. In contrast, cytoplasmic or extracellular localization of Tat may cause pathogenic effects in the form of altered cell activation, apoptosis, or neurotoxicity. Tat variants have been shown to differentially induce these processes, which may have implications for long-term HIV-1-infected patient care in the antiretroviral therapy era. Future studies concerning genetic variation of Tat with respect to function should focus on variants derived from HIV-1-infected individuals to efficiently guide Tat-targeted therapies and elucidate mechanisms of pathogenesis within the global patient population.

HIV transgene expression impairs K+ channel function in the pulmonary vasculature

Human immunodeficiency virus (HIV) infection is an established risk factor for pulmonary arterial hypertension (PAH); however, the pathogenesis of HIV-related PAH remains unclear. Since K⁺ channel dysfunction is a common marker in most forms of PAH, our aim was to analyze whether the expression of HIV proteins is associated with impairment of K⁺ channel function in the pulmonary vascular bed. HIV transgenic mice (Tg26) expressing seven of the nine HIV viral proteins and wild-type (WT) mice were used. Hemodynamic assessment was performed by echocardiography and catheterization. Vascular reactivity was studied in endothelium-intact pulmonary arteries. K⁺ currents were recorded in freshly isolated pulmonary artery smooth muscle cells (PASMC) using the patch-clamp technique. Gene expression was assessed using quantitative RT-PCR. PASMC from Tg26 mice had reduced K⁺ currents and were more depolarized than those from WT. Whereas voltage-gated K⁺ channel 1.5 (Kv1.5) currents were preserved, pH-sensitive noninactivating background currents ( I_KN) were nearly abolished in PASMC from Tg26 mice. Tg26 mice had reduced lung expression of Kv7.1 and Kv7.4 channels and decreased responses to the Kv7.1 channel activator L-364,373 assessed by vascular reactivity and patch-clamp experimental approaches. Although we found pulmonary vascular remodeling and endothelial dysfunction in Tg26 mice, this was not accompanied by changes in hemodynamic parameters. In conclusion, the expression of HIV proteins in vivo impairs pH-sensitive I_KN and Kv7 currents. This negative impact of HIV proteins in K⁺ channels was not sufficient to induce PAH, at least in mice, but may play a permissive or accessory role in the pathophysiology of HIV-associated PAH.

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.

Infectious and Non-infectious Etiologies of Cardiovascular Disease in Human Immunodeficiency Virus Infection

Background:

Increasing rates of HIV have been observed in women, African Americans, and Hispanics, particularly those residing in rural areas of the United States. Although cardiovascular (CV) complications in patients infected with human immunodeficiency virus (HIV) have significantly decreased following the introduction of antiretroviral therapy on a global scale, in many rural areas, residents face geographic, social, and cultural barriers that result in decreased access to care. Despite the advancements to combat the disease, many patients in these medically underserved areas are not linked to care, and fewer than half achieve viral suppression.

Methods:

Databases were systematically searched for peer-reviewed publications reporting infectious and non-infectious etiologies of cardiovascular disease in HIV-infected patients. Relevant articles cited in the retrieved publications were also reviewed for inclusion.

Results:

A variety of outcomes studies and literature reviews were included in the analysis. Relevant literature discussed the manifestations, diagnosis, treatment, and outcomes of infectious and non-infectious etiologies of cardiovascular disease in HIV-infected patients.

Conclusion:

In these medically underserved areas, it is vital that clinicians are knowledgeable in the manifestations, diagnosis, and treatment of CV complications in patients with untreated HIV. This review summarizes the epidemiology and causes of CV complications associated with untreated HIV and provide recommendations for management of these complications.

Epidemiology and management of antiretroviral-associated cardiovascular disease

Risk and manifestations of cardiovascular disease (CVD) in patients infected with human immunodeficiency virus (HIV) will continue to evolve as improved treatments and life expectancy of these patients increases. Although initiation of antiretroviral (ARV) therapy has been shown to reduce this risk, some ARV medications may induce metabolic abnormalities, further compounding the risk of CVD. In this patient population, both pharmacologic and nonpharmacologic strategies should be employed to treat and reduce further risk of CVD. This review summarizes epidemiology data of the risk factors and development of CVD in HIV and provides recommendations to manage CVD in HIV-infected patients.

RYR3 gene variants in subclinical atherosclerosis among HIV-infected women in the Women's Interagency HIV Study (WIHS)

BACKGROUND

Single nucleotide polymorphisms (SNPs) in the Ryanodine receptor 3 (RYR3) gene are associated with common carotid intima media thickness (CCA cIMT) in HIV-infected men. We evaluated SNPs in the RYR3 gene among HIV-infected women participating in Women's Interagency HIV Study (WIHS).

METHODS

CCA cIMT was measured using B-mode ultrasound and the 838 SNPs in the RYR3 gene region were genotyped using the Illumina HumanOmni2.5-quad beadchip. The CCA cIMT genetic association was assessed using linear regression analyses among 1213 women and also separately among White (n=139), Black (n=720) and Hispanic (n=354) women after adjusting for confounders. A summary measure of pooled association was estimated using a meta-analytic approach by combining the effect estimates from the three races. Haploblocks were inferred using Gabriel's method and haplotype association analyses were conducted among the three races separately.

RESULTS

SNP rs62012610 was associated with CCA cIMT among the Hispanics (p=4.41×10(-5)), rs11856930 among Whites (p=5.62×10(-4)), and rs2572204 among Blacks (p=2.45×10(-3)). Meta-analysis revealed several associations of SNPs in the same direction and of similar magnitude, particularly among Blacks and Hispanics. Additionally, several haplotypes within three haploblocks containing SNPs previously related with CCA cIMT were also associated in Whites and Hispanics.

DISCUSSION

Consistent with previous research among HIV-infected men, SNPs within the RYR3 region were associated with subclinical atherosclerosis among HIV-infected women. Allelic heterogeneity observed across the three races suggests that the contribution of the RYR3 gene to CCA cIMT is complex, and warrants future studies to better understand regional SNP function.

Effect of antiretroviral therapy on inflammatory markers of endothelial dysfunction in HIV treatment-naïve infected patients

The aim of this study was to evaluate the effect of antiretroviral therapy on inflammatory markers of endothelial dysfunction in HIV treatment-naïve infected patients. This was a prospective cohort study in HIV treatment-naïve infected patients. The patients were assigned to a untreated group or a treatment group according to the therapeutic strategy received. Patients in the treatment group received efavirenz or lopinavir/ritonavir, each given with zidovudine and lamivudine. HIV RNA, CD4(+) cell count, and the levels of hsCRP, sCD40L, sICAM-1, sVCAM-1, and sE-selectin were measured before and 12 weeks after treatment. Fifty patients were enrolled: 13 in the untreated group and 37 in the treatment group; 48 (96%) completed the follow-up. The mean (± SD) age was 33 ± 9 years, and 38 (79%) were men. The median pretreatment CD4(+) cell counts were 263 cells/ml (IQR 118-341) in the treatment group and 658 cells/ml (IQR 475-887) in the untreated group. In the treatment group, the median serum sVCAM-1 and sICAM-1 levels decreased by a small but significant amount (1,400 and 228 ng/ml, respectively, P<0.05) from before to after the 12 weeks. These levels did not change in the untreated group. Antiretroviral therapy is associated with a decrease in sVCAM-1 and sICAM-1 levels after 12 weeks of treatment.

HIV, inflammation, and calcium in atherosclerosis

Atherosclerosis is consistently higher among the HIV-positive patients, with or without treatment, than among the HIV-negative population. Risk factors linked to atherosclerotic cardiovascular disease in HIV infection are both traditional and HIV specific although the underlying mechanisms are not fully delineated. Three key sequential biological processes are postulated to accelerate progression of atherosclerosis in the context of HIV: (1) inflammation, (2) transformation of monocytes to macrophages and then foam cells, and (3) apoptosis of foam cells leading to plaque development through Ca(2+)-dependent endoplasmic reticulum stress. These proatherogenic mechanisms are further affected when HIV interacts with the genes involved in various phases within this network.

Human immunodeficiency virus-1 transgene expression increases pulmonary vascular resistance and exacerbates hypoxia-induced pulmonary hypertension development

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by increased pulmonary arterial resistance and vessel remodeling. Patients living with human immunodeficiency virus-1 (HIV-1) have an increased susceptibility to develop severe pulmonary hypertension (PH) irrespective of their CD4+ lymphocyte counts. While the underlying cause of HIV-PAH remains unknown, the interaction of HIV-1 proteins with the vascular endothelium may play a critical role in HIV-PAH development. Hypoxia promotes PH in experimental models and in humans, but the impact of HIV-1 proteins on hypoxia-induced pulmonary vascular dysfunction and PAH has not been examined. Therefore, we hypothesize that the presence of HIV-1 proteins and hypoxia synergistically augment the development of pulmonary vascular dysfunction and PH. We examined the effect of HIV-1 proteins on pulmonary vascular resistance by measuring pressure-volume relationships in isolated lungs from wild-type (WT) and HIV-1 Transgenic (Tg) rats. WT and HIV-1 Tg rats were exposed to 10% O₂ for four weeks to induce experimental pulmonary hypertension to assess whether HIV-1 protein expression would impact the development of hypoxia-induced PH. Our results demonstrate that HIV-1 protein expression significantly increased pulmonary vascular resistance (PVR). HIV-1 Tg mice demonstrated exaggerated pulmonary vascular responses to hypoxia as evidenced by greater increases in right ventricular systolic pressures, right ventricular hypertrophy and vessel muscularization when compared to wild-type controls. This enhanced PH was associated with enhanced expression of HIF-1α and PCNA. In addition, in vitro studies reveal that medium from HIV-infected monocyte derived macrophages (MDM) potentiates hypoxia-induced pulmonary artery endothelial proliferation. These results indicate that the presence of HIV-1 proteins likely impact pulmonary vascular resistance and exacerbate hypoxia-induced PH.

Endothelial dysfunction, arterial stiffening, and intima-media thickening in large arteries from HIV-1 transgenic mice

HIV patients on highly active antiretroviral therapy (HAART) exhibit elevated incidence of cardiovascular disease (CVD), including a higher risk of myocardial infarction and prevalence of atherosclerotic lesions, as well as increases in markers of subclinical atherosclerosis including increased carotid artery intima-media thickness (c-IMT), increased arterial stiffness, and impaired flow-mediated dilation. Both HAART and HIV-infection are independent risk factors for atherosclerosis and myocardial infarction. Studies implicate the HIV proteins tat, gp120, vpu, and nef in early on-set atherosclerosis. The objective of this study was to quantify the role of expression of HIV-1 proteins on the vascular function, biomechanics, and geometry of common carotid arteries and aortas. This study employed NL4-3Δ gag/pol transgenic mice (HIV-Tg), which contain the genetic sequence for the HIV-1 proteins env, tat, nef, rev, vif, vpr, and vpu but lacks the gag and pol genes and reports that HIV-Tg mice have impaired aortic endothelial function, increased c-IMT, and increased arterial stiffness. Further, HIV-Tg arteries show decreased elastin content, increased cathepsin K and cathepsin S activity, and increased mechanical residual stress. Thus, mice that express HIV proteins exhibit pre-clinical markers of atherosclerosis and these markers correlate with changes in markers of vascular remodeling. These findings are consistent with the hypothesis that HIV-proteins, independent of HAART treatment or HIV infection, could play a role in of the development of CVD.

Transient hypercapnia reveals an underlying cerebrovascular pathology in a murine model for HIV-1 associated neuroinflammation: role of NO-cGMP signaling and normalization by inhibition of cyclic nucleotide phosphodiesterase-5

BACKGROUND

Cerebral blood flow (CBF) is known to be dysregulated in persons with human immunodeficiency virus 1 (HIV-1), for uncertain reasons. This is an important issue because impaired vasoreactivity has been associated with increased risk of ischemic stroke, elevated overall cardiovascular risk and cognitive impairment.

METHODS

To test whether dysregulation of CBF might be due to virally-induced neuroinflammation, we used a well-defined animal model (GFAP-driven, doxycycline-inducible HIV-1 Tat transgenic (Tat-tg) mice). We then exposed the mice to a brief hypercapnic stimulus, and assessed cerebrovascular reactivity by measuring 1) changes in cerebral blood flow, using laser Doppler flowmetry and 2) changes in vascular dilation, using in vivo two-photon imaging.

RESULTS

Exposure to brief hypercapnia revealed an underlying cerebrovascular pathology in Tat-tg mice. In control animals, brief hypercapnia induced a brisk increase in cortical flow (20.8% above baseline) and vascular dilation, as measured by laser Doppler flowmetry and in vivo two-photon microscopy. These responses were significantly attenuated in Tat-tg mice (11.6% above baseline), but cortical microvascular morphology and capillary density were unaltered, suggesting that the functional pathology was not secondary to vascular remodeling. To examine the mechanistic basis for the diminished cerebrovascular response to brief hypercapnia, Tat-tg mice were treated with 1) gisadenafil, a phosphodiesterase 5 (PDE5) inhibitor and 2) tetrahydrobiopterin (BH4). Gisadenafil largely restored the normal increase in cortical flow following hypercapnia in Tat-tg mice (17.5% above baseline), whereas BH4 had little effect. Gisadenafil also restored the dilation of small (<25 μm) arterioles following hypercapnia (19.1% versus 20.6% diameter increase in control and Tat-tg plus gisadenafil, respectively), although it failed to restore full dilation of larger (>25 μm) vessels.

CONCLUSIONS

Taken together, these data show that HIV-associated neuroinflammation can cause cerebrovascular pathology through effects on cyclic guanosine monophosphate (cGMP) metabolism and possibly on PDE5 metabolism.

The biology of atherosclerosis: general paradigms and distinct pathogenic mechanisms among HIV-infected patients

Complications of atherosclerosis, including myocardial infarction and stroke, are the leading cause of death and disability worldwide. Recent data strongly implicate cardiovascular death as a contributor to mortality among patients with human immunodeficiency virus (HIV) infection, with evidence suggesting increased incidence of atherosclerosis among these patients. Therefore, greater understanding of atherosclerotic mechanisms and how these responses may be similar or distinct in HIV-infected patients is needed. Key concepts in atherosclerosis are reviewed, including the evidence that inflammation and abnormal metabolism are major drivers of atherosclerosis, and connected to the current literature regarding atherosclerosis in the context of HIV.

Vascular stiffness and aging in HIV

Large artery stiffening is a biological index of vascular aging. Vascular aging and atherosclerosis are two closely linked processes that develop in parallel and in synergy, sharing common aetiological determinants. Vascular stiffening increases left ventricular work and can lead to diminished coronary perfusion, and may therefore contribute to the development of cardiovascular disease. There is emerging evidence that large artery stiffness and vascular aging are accelerated in HIV infection because of the high prevalence of cardiovascular risk factors among HIV-infected patients. Moreover, the biological effects of HIV and the metabolic perturbations associated with antiretroviral therapies appear to accelerate vascular stiffening in HIV-infected patients. Further studies evaluating the effects of general and targeted therapies and various combinations of antiretroviral therapies on measures of large artery stiffness are urgently needed.

The Relationship Between HIV Infection and Cardiovascular Disease

Over 30 million people are currently living with human immunodeficiency virus (HIV) infection, and over 2 million new infections occur per year. HIV has been found to directly affect vascular biology resulting in an increased risk of cardiovascular disease compared to uninfected persons. Although HIV infection can now be treated effectively with combination antiretroviral medications, significant toxicities such as hyperlipidemia, diabetes, and excess cardiovascular co-morbidity; as well as the potential for significant drug-drug interactions between HIV and cardiovascular medications, present new challenges for the management of persons infected with HIV. We first review basic principles of HIV pathogenesis and treatment and then discuss relevant clinical management strategies that will be useful for cardiologists who might be involved in the care of HIV infected patients.

A genome-wide association study of carotid atherosclerosis in HIV-infected men

BACKGROUND

The role of host genetics in the development of subclinical atherosclerosis in the context of HIV-infected persons who are being treated with highly active antiretroviral therapy (HAART) is not well understood.

METHODS

The present genome-wide association study (GWAS) is based on 177 HIV-positive Caucasian males receiving HAART who participated in the Fat Redistribution and Metabolic Change in HIV Infection (FRAM) Study. Common and internal carotid intima-media thicknesses (cIMT) measured by B-mode ultrasound were used as a subclinical measure of atherosclerosis. Single nucleotide polymorphisms (SNPs) were assayed using the Illumina HumanCNV370-quad beadchip. Copy Number Variants (CNV) were inferred using a hidden Markov Model (PennCNV). Regression analyses were used to assess the association of common and internal cIMT with individual SNPs and CNVs, adjusting for age, duration of antiretroviral treatment, and principal components to account for potential population stratification.

RESULTS

Two SNPs in tight linkage disequilibrium, rs2229116 (a missense, nonsynonymous polymorphism (IIe to Val)) and rs7177922, located in the ryanodine receptor (RYR3) gene on chromosome 15 were significantly associated with common cIMT (P-value < 1.61 x 10). The RYR gene family has been known to play a role in the etiology of cardiovascular disease and has been shown to be regulated by HIV TAT protein.

CONCLUSION

These results suggest that in the context of HIV infection and HAART, a functional SNP in a biologically plausible candidate gene, RYR3, is associated with increased common carotid IMT, which is a surrogate for atherosclerosis.

HIV gp120 induces endothelial dysfunction in tumour necrosis factor-alpha-activated porcine and human endothelial cells

AIMS

The aim of this study was to determine direct effects and potential molecular mechanisms of HIV gp120, a viral envelope glycoprotein, on endothelial function.

METHODS AND RESULTS

Fresh porcine coronary artery rings and human coronary artery endothelial cells (HCAECs) were treated with recombinant HIV gp120 for 16 h with or without pretreatment with tumour necrosis factor-alpha (TNF-alpha) (8 h). With a myograph tension analysis, HIV gp120 with TNF-alpha pretreatment significantly decreased endothelium-dependent vasorelaxation in response to bradykinin in porcine coronary artery rings compared with untreated control vessels. In addition, HIV gp120 with TNF-alpha pretreatment significantly reduced endothelial nitric oxide synthase (eNOS) expression-both mRNA and protein levels-in porcine coronary artery rings and HCAECs compared with untreated controls. Furthermore, TNF-alpha pretreatment substantially increased intercellular adhesion molecule-1 (ICAM-1) expression in artery rings and HCAECs. Anti-gp120 or anti-ICAM-1 antibody significantly blocked these effects of HIV gp120. Silencing of ICAM-1 by siRNA oligonucleotides significantly blocked the effect of gp120 on eNOS downregulation in TNF-alpha-pretreated HCAECs.

CONCLUSION

HIV gp120 and TNF-alpha synergistically reduce eNOS expression and cause endothelial dysfunction in both porcine coronary arteries and HCAECs. ICAM-1 induced by TNF-alpha pretreatment may mediate HIV gp120-induced endothelial dysfunction, which suggests a novel molecular mechanism of HIV gp120-ICAM-1 interaction inducing endothelial dysfunction.

Increased prevalence of subclinical coronary atherosclerosis detected by coronary computed tomography angiography in HIV-infected men

OBJECTIVE

The degree of subclinical coronary atherosclerosis in HIV-infected patients is unknown. We investigated the degree of subclinical atherosclerosis and the relationship of traditional and nontraditional risk factors to early atherosclerotic disease using coronary computed tomography angiography.

DESIGN AND METHODS

Seventy-eight HIV-infected men (age 46.5 +/- 6.5 years and duration of HIV 13.5 +/- 6.1 years, CD4 T lymphocytes 523 +/- 282; 81% undetectable viral load), and 32 HIV-negative men (age 45.4 +/- 7.2 years) with similar demographic and coronary artery disease (CAD) risk factors, without history or symptoms of CAD, were prospectively recruited. 64-slice multidetector row computed tomography coronary angiography was performed to determine prevalence of coronary atherosclerosis, coronary stenosis, and quantitative plaque burden. RESULTS HIV-infected men demonstrated higher prevalence of coronary atherosclerosis than non-HIV-infected men (59 vs. 34%; P = 0.02), higher coronary plaque volume [55.9 (0-207.7); median (IQR) vs. 0 (0-80.5) microl; P = 0.02], greater number of coronary segments with plaque [1 (0-3) vs. 0 (0-1) segments; P = 0.03], and higher prevalence of Agatston calcium score more than 0 (46 vs. 25%, P = 0.04), despite similar Framingham 10-year risk for myocardial infarction, family history of CAD, and smoking status. Among HIV-infected patients, Framingham score, total cholesterol, low-density lipoprotein, CD4/CD8 ratio, and monocyte chemoattractant protein 1 were significantly associated with plaque burden. Duration of HIV infection was significantly associated with plaque volume (P = 0.002) and segments with plaque (P = 0.0009) and these relationships remained significant after adjustment for age, traditional risk factors, or duration of antiretroviral therapy. A total of 6.5% (95% confidence interval 2-15%) of our study population demonstrated angiographic evidence of obstructive CAD (>70% luminal narrowing) as compared with 0% in controls.

CONCLUSION

Young, asymptomatic, HIV-infected men with long-standing HIV disease demonstrate an increased prevalence and degree of coronary atherosclerosis compared with non-HIV-infected patients. Both traditional and nontraditional risk factors contribute to atherosclerotic disease in HIV-infected patients.

Cardiovascular disease in HIV-infected patients: does HIV infection in and of itself increase cardiovascular risk?

PURPOSE OF REVIEW

Cardiovascular disease is increasingly recognized to be a significant cause of morbidity and mortality among patients with chronic HIV infection in the current era of effective antiretroviral therapy. HIV-infected patients treated with antiretroviral therapy have increased traditional cardiovascular risk factors, but whether HIV infection in and of itself confers a significant increase in cardiovascular risk is largely unknown. This review summarizes recent data investigating cardiovascular risk in HIV patients and the evidence for an effect of HIV per se. The potential physiological mechanisms by which HIV might contribute to coronary artery disease are reviewed.

RECENT FINDINGS

Several interesting studies in the last year have evaluated cardiovascular endpoints and surrogate measures such as carotid intima-media thickness and endothelial function in HIV-infected patients compared with uninfected control groups. Several studies to date using surrogate measurements such as carotid intima-media thickness and endothelial dysfunction suggest a possible independent HIV effect on cardiovascular risk, but some studies have yielded conflicting results. Numerous potential mechanisms by which HIV might contribute to coronary artery disease exist. These mechanisms include effects of HIV proteins to attract monocytes to the intimal wall, and impair cholesterol efflux, and effects of activated monocytes to induce an inflammatory response.

SUMMARY

More definitive prospective studies are needed to fully answer whether HIV infection per se promotes cardiovascular disease, but ample evidence suggests that HIV and related inflammatory responses could contribute to increased cardiovascular disease.

Roles and mechanisms of human immunodeficiency virus protease inhibitor ritonavir and other anti-human immunodeficiency virus drugs in endothelial dysfunction of porcine pulmonary arteries and human pulmonary artery endothelial cells

The objective of this study was to determine the effects of highly active antiretroviral therapy (HAART) drugs on pulmonary endothelial function. Porcine pulmonary arteries or human pulmonary arterial endothelial cells (HPAECs) were incubated with eight HAART drugs [ritonavir, indinavir, lopinavir, zidovudine (AZT), abacavir, stavudine, didanosine (ddI), and lamivudine] individually or in combination [three HAART drugs (3-plex; indinavir, stavudine, and ddI)] at their clinical plasma concentrations for 24 hours. Endothelium-dependent vasorelaxation in response to bradykinin was reduced significantly by the ritonavir in a concentration-dependent manner. Five other HAART drugs (indinavir, lamivudine, abacavir, AZT, and ddI) and the 3-plex significantly also impaired endothelium-dependent vasorelaxation in response to bradykinin. Five HAART drugs (ritonavir, indinavir, lamivudine, abacavir, and AZT) significantly decreased endothelial nitric oxide synthase (eNOS) expression and increased superoxide anion levels in both vessels and HPAECs. Furthermore, both ritonavir and AZT substantially activated ERK2 in HPAECs. Additionally, the antioxidants ginsenoside Rb1 and ginkgolide A effectively reversed HAART drug-induced vasomotor dysfunction and eNOS down-regulation. Inhibition of ERK1/2 also partially blocked ritonavir- and AZT-induced down-regulation of eNOS and vasomotor dysfunction. Thus, HAART drugs significantly impair endothelial functions of porcine pulmonary arteries and HPAECs, which may be mediated by eNOS down-regulation, oxidative stress, and ERK1/2 activation. These findings suggest that HAART drugs may contribute to the high incidence of pulmonary artery hypertension in human immunodeficiency virus-infected patients.

Growth hormone-releasing peptide ghrelin inhibits homocysteine-induced endothelial dysfunction in porcine coronary arteries and human endothelial cells

OBJECTIVE

Ghrelin, a novel growth hormone-releasing peptide, is implicated to play a protective role in cardiovascular tissues. However, it is not clear whether ghrelin protects vascular tissues from injury secondary to risk factors such as homocysteine (Hcy). This study investigated the effect and potential mechanisms of ghrelin on Hcy-induced endothelial dysfunction.

METHODS

Porcine coronary artery rings were incubated for 24 hours with ghrelin (100 ng/mL), Hcy (50 microM), or ghrelin plus Hcy. Endothelial vasomotor function was evaluated using the myograph tension model. The response to the thromboxane A(2)analog U46619, bradykinin, and sodium nitroprusside was analyzed. Endothelial nitric oxide synthase (eNOS) expression was determined using real-time polymerase chain reaction and immunohistochemistry staining, and superoxide anion production was documented lucigenin-enhanced chemiluminescence analysis. Human coronary artery endothelial cells (HCAECs) were treated with different concentrations of Hcy, ghrelin, or antighrelin receptor antibody for 24 hours, and eNOS protein levels were determined by Western blot analysis.

RESULTS

Maximal contraction with U46619 and endothelium-independent vasorelaxation with sodium nitroprusside were not different among the four groups. However, endothelium-dependent vasorelaxation with bradykinin (10(-6) M) was significantly reduced by 34% with Hcy compared with controls (P < .05). The addition of ghrelin to Hcy had a protective effect, with 61.6% relaxation, which was similar to controls (64.7%). Homocysteine significantly reduced eNOS expression, whereas ghrelin cotreatment effectively restored eNOS expression to the control levels. Superoxide anion levels, which were increased by 100% with Hcy, returned to control levels with ghrelin cotreatment. Ghrelin also effectively blocked the Hcy-induced decrease of eNOS protein levels in HCAECs in a concentration-dependent manner. Antighrelin receptor antibody effectively inhibited the effect of ghrelin.

CONCLUSION

Ghrelin has a protective effect in the porcine coronary artery by blocking Hcy-induced endothelial dysfunction, improving eNOS expression, and reducing oxidative stress. Ghrelin also shows a protective effect on HCACEs from the Hcy-induced decrease in eNOS protein levels. The effect of ghrelin is receptor-dependent. Thus, ghrelin administration may have beneficial effects in the treatment of vascular disease in patients with hyperhomocysteinemia.

The roles of HIV-1 proteins and antiretroviral drug therapy in HIV-1-associated endothelial dysfunction

Since the emergence of highly active antiretroviral therapy (HAART), human immunodeficiency virus-1 (HIV-1)-infected patients have demonstrated dramatic decreases in viral burden and opportunistic infections, and an overall increase in life expectancy. Despite these positive HAART-associated outcomes, it has become increasingly clear that HIV-1 patients have an enhanced risk of developing cardiovascular disease over time. Clinical studies are instrumental in our understanding of vascular dysfunction in the context of HIV-1 infection. However, most clinical studies often do not distinguish whether HIV-1 proteins, HAART, or a combination of these 2 factors cause cardiovascular complications. This review seeks to address the roles of both HIV-1 proteins and antiretroviral drugs in the development of endothelial dysfunction because endothelial dysfunction is the hallmark initial step of many cardiovascular diseases. We analyze recent in vitro and in vivo studies examining endothelial toxicity in response to HIV-1 proteins or in response to the various classes of antiretroviral drugs. Furthermore, we discuss the multiple mechanisms by which HIV-1 proteins and HAART injure the vascular endothelium in HIV-1 patients. By understanding the molecular mechanisms of HIV-1 protein- and antiretroviral-induced cardiovascular disease, we may ultimately improve the quality of life of HIV-1 patients through better drug design and the discovery of new pharmacological targets.

Vascular oxidative stress and nitric oxide depletion in HIV-1 transgenic rats are reversed by glutathione restoration

Human immunodeficiency virus (HIV)-infected patients have a higher incidence of oxidative stress, endothelial dysfunction, and cardiovascular disease than uninfected individuals. Recent reports have demonstrated that viral proteins upregulate reactive oxygen species, which may contribute to elevated cardiovascular risk in HIV-1 patients. In this study we employed an HIV-1 transgenic rat model to investigate the physiological effects of viral protein expression on the vasculature. Markers of oxidative stress in wild-type and HIV-1 transgenic rats were measured using electron spin resonance, fluorescence microscopy, and various molecular techniques. Relaxation studies were completed on isolated aortic rings, and mRNA and protein were collected to measure changes in expression of nitric oxide (NO) and superoxide sources. HIV-1 transgenic rats displayed significantly less NO-hemoglobin, serum nitrite, serum S-nitrosothiols, aortic tissue NO, and impaired endothelium-dependent vasorelaxation than wild-type rats. NO reduction was not attributed to differences in endothelial NO synthase (eNOS) protein expression, eNOS-Ser1177 phosphorylation, or tetrahydrobiopterin availability. Aortas from HIV-1 transgenic rats had higher levels of superoxide and 3-nitrotyrosine but did not differ in expression of superoxide-generating sources NADPH oxidase or xanthine oxidase. However, transgenic aortas displayed decreased superoxide dismutase and glutathione. Administering the glutathione precursor procysteine decreased superoxide, restored aortic NO levels and NO-hemoglobin, and improved endothelium-dependent relaxation in HIV-1 transgenic rats. These results show that HIV-1 protein expression decreases NO and causes endothelial dysfunction. Diminished antioxidant capacity increases vascular superoxide levels, which reduce NO bioavailability and promote peroxynitrite generation. Restoring glutathione levels reverses HIV-1 protein-mediated effects on superoxide, NO, and vasorelaxation.

Insulin resistance predicts endothelial dysfunction and cardiovascular risk in HIV-infected persons on long-term highly active antiretroviral therapy

OBJECTIVE

Cardiovascular disease risk among persons with HIV is likely multifactorial, thus testing a variety of available noninvasive vascular ultrasound and other surrogate tests may yield differing results. To address this issue, we assessed multiple metabolic and clinical predictors of endothelial function and carotid intima-media thickness in HIV-infected subjects and compared results with HIV-negative controls.

DESIGN

Prospective, cross-sectional study of 50 HIV-infected, healthy adults on stable highly active antiretroviral therapy matched to 50 HIV-negative controls by age, sex, race, and body mass index.

METHODS

Flow-mediated vasodilation of the brachial artery, carotid intima-media thickness, dual energy X-ray absorptiometry (HIV-infected subjects), and fasting insulin, lipids, and oral glucose tolerance tests were performed. Results were compared between HIV-infected and control groups.

RESULTS

Fifty percent of subjects were African-American with 34% women. Among HIV-infected, mean CD4 cell count was 547 cells/microl; 90% had HIV RNA less than 50 copies/ml. There were no significant differences between HIV-infected and control subjects with regard to brachial artery flow-mediated vasodilation or carotid intima-media thickness. In multivariate analyses of the HIV cohort, independent predictors of endothelial dysfunction (lower flow-mediated vasodilation) were increasing insulin resistance, greater alcohol consumption, and higher baseline brachial artery diameter (P < 0.05); predictors of increased carotid intima-media thickness were hypertension, higher trunk/limb fat ratio, and insulin resistance (P < 0.05).

CONCLUSION

In this HIV cohort on modern highly active antiretroviral therapy with well controlled HIV, there were no significant differences with regard to preclinical markers of cardiovascular disease. Insulin resistance was a strong predictor of impaired brachial artery flow-mediated vasodilation and increased carotid intima-media thickness, and may be an important cardiovascular disease risk factor in the HIV population.

Neutrophil antimicrobial peptide alpha-defensin causes endothelial dysfunction in porcine coronary arteries

BACKGROUND

Defensins are cysteine-rich cationic polypeptides released from neutrophils that exhibit powerful antimicrobial activities. Because inflammation, including neutrophil infiltration and release of defensins, may play an important role in atherosclerosis and other vascular diseases, we determined whether alpha-defensin could cause endothelial dysfunction, a major initial event of atherosclerosis, in porcine coronary arteries.

METHODS

Porcine coronary arteries were sliced into 5-mm rings and treated with different concentrations of human recombinant alpha-defensin for 24 hours. Vasomotor reactivity was studied by using a myograph system. Levels of superoxide anion were detected by the lucigenin-enhanced chemiluminescence method. Endothelial nitric oxide synthase (eNOS) messenger RNA (mRNA) and protein levels were determined by real-time polymerase chain reaction and immunohistochemistry analysis, respectively.

RESULTS

Endothelium-dependent relaxation in response to bradykinin was significantly reduced by 40% for the rings treated with 1500 nM of alpha-defensin compared with controls (P< .05). Vessel contractility in response to the thromboxane A2 analogue U46619 and endothelium-independent relaxation in response to sodium nitroprusside were not affected with defensin treatment. In addition, the superoxide anion level at the endothelial layer of porcine coronary artery rings was significantly increased by 80% in the defensin-treated (1500 nM) vessels compared with controls (P< .05). Furthermore, the eNOS mRNA levels in endothelial cells isolated from the cultured rings treated with defensin (1500 nM) were significantly decreased by 27% compared with controls (P< .05). Immunoreactivity of eNOS in the defensin-treated vessel rings was also substantially reduced.

CONCLUSIONS

Defensin reduces the endothelium-dependent vasorelaxation. This effect is associated with increased superoxide radical production and decreased eNOS expression in porcine coronary arteries.

CLINICAL RELEVANCE

Inflammation is an important mechanism of atherosclerosis and other vascular diseases. The roles and interactions of biomediators released from inflammatory cells are not fully understood, however. This study provides new information about effects and potential molecular mechanisms of a major neutrophil releasing factor, alpha-defensin, on endothelial dysfunction of porcine coronary arteries. Thus, targeting alpha-defensin and its associated molecular mechanisms may become a new strategy to prevent vascular diseases.