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

RATIONALE

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

OBJECTIVE

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

METHODS AND RESULTS

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

CONCLUSIONS

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

HIV Infection Is Not Associated With Aortic Stiffness. Traditional Cardiovascular Risk Factors Are the Main Determinants-Cross-sectional Results of INI-ELSA-BRASIL

INTRODUCTION

Aortic stiffness measured by carotid-femoral pulse wave velocity (cf-PWV) is a marker of subclinical atherosclerosis. We propose to assess whether HIV infection is associated with arterial stiffness and their determinants in HIV-infected subjects.

METHODS

We compared data from an HIV cohort (644 patients, HIV+) in Rio de Janeiro with 2 groups: 105 HIV-negative (HIV-) individuals and 14,873 participants of the ELSA-Brasil study. We used multivariable linear regression to investigate factors associated with cf-PWV and whether HIV was independently associated with aortic stiffness and propensity score weighting to control for imbalances between groups.

RESULTS

From 15,860 participants, cf-PWV was obtained in 15,622 (98.5%). Median age was 51 (interquartile range 45-58), 44.41 (35.73, 54.72), and 43.60 (36.01, 50.79) years (P < 0.001), and median cf-PWV (m/s; interquartile range) was 9.0 (8.10, 10.20), 8.70 (7.90, 10.20), and 8.48 (7.66, 9.40) for ELSA-Brasil, HIV- and HIV+, respectively (P < 0.001). In the final weighted multivariable models, HIV group was not associated with cf-PWV when compared either with ELSA-Brasil [β = -0.05; 95% confidence interval (CI) = -0.23; P = 0.12; P = 0.52] or with the HIV- groups (β = 0.10; 95% CI = -0.10; 0, 31; P = 0.32). Traditional risk factors were associated with higher cf-PWV levels in the HIV+ group, particularly waist-to-hip ratio (β = 0.20; 95% CI = 0.10; 0.30; P < 0.001, result per one SD change).

CONCLUSIONS

HIV infection was not associated with higher aortic stiffness according to our study. In HIV-infected subjects, the stiffness of large arteries is mainly associated with traditional risk factors and not to the HIV infection per se.

Aortic stiffness aging is influenced by past profound immunodeficiency in HIV-infected individuals: results from the EVAS-HIV (EValuation of Aortic Stiffness in HIV-infected individuals)

OBJECTIVE

We compared aortic stiffness between HIV-infected and HIV-uninfected individuals and examined the determinants of vascular aging during HIV infection.

METHODS

Aortic stiffness using carotid-femoral pulse wave velocity (cf-PWV) was evaluated cross-sectionally between HIV-infected individuals and uninfected controls frequency-matched for age and sex, and longitudinally in a subgroup of HIV-infected individuals. Determinants of elevated cf-PWV levels were assessed using logistic regression. Changes in cf-PWV levels during follow-up (mixed-effect linear regression) and risk factors for achieving cf-PWV below (Group 1) or above the median (Group 2) at last follow-up visit were evaluated only in HIV-infected individuals.

RESULTS

A total of 133 HIV-infected and 135 HIV-uninfected individuals (mean age: 47.7 ± 8.9 years, 91% men) were enrolled. Median cf-PWV at baseline was similar between HIV-infected individuals and controls [7.5 m/s (interquartile range = 6.7-8.4) vs. 7.5 m/s (interquartile range = 6.6-8.4), respectively; P = 0.64]. In multivariable analysis, only mean arterial pressure showed significant association with elevated cf-PWV in the overall population (P = 0.036). In HIV-infected individuals, elevated cf-PWV was associated with current smoking (P = 0.042), and nadir CD4 T-cell count less than 200 cells/μl (P = 0.048). Ninety-one HIV-infected individuals were followed for a mean 7.6 ± 2.0 years. cf-PWV progression was associated with age (P = 0.018), mean arterial pressure (P = 0.020), and nadir CD4 T-cell count (P = 0.005). Patients from Group 2 had higher baseline waist circumference, pulse pressure, and nadir CD4 T-cell count less than 200 cells/μl.

CONCLUSION

We observed no difference in aortic stiffness between HIV-infected and controls. Moreover, aortic stiffness aging was independently associated with past severe immunodeficiency, along with other traditional risk factors. Our results call for early antiretroviral initiation.

Association between Immune Markers and Surrogate Markers of Cardiovascular Disease in HIV Positive Patients: A Systematic Review

Background

HIV infection is associated with an increased risk of cardiovascular disease (CVD). Chronic low-grade immune activation is likely one of the driving mechanisms. This systematic review provides an overview of the evidence addressing the relation between immune markers and surrogate markers of CVD (except CIMT) in HIV infection.

Methods

A systematic search was performed in PubMed, Embase and Cochrane Library identifying all articles from 1996 to April 2015. It addressed the relation between immune markers and surrogate markers of CVD (except Carotid Intima-media Thickness) in HIV-positive adults. Two authors, using predefined criteria, independently conducted the selection of articles, critical appraisal and extraction of the data. Analysis focused on immune markers that were assessed most frequently. The review was conducted according to the PRISMA guideline and performed as part of an overarching review registered with PROSPERO (CRD42014010516).

Findings

Twenty-nine articles were selected, describing 34 immune markers and nine different CVD surrogate outcomes: coronary calcium score (13 times) and flow-mediated dilation (10 times) were used most frequently. Twenty-seven studies had a cross-sectional design. CRP, IL-6 and sVCAM-1 were assessed most frequently. None of the immune markers were clearly associated with any of the surrogate CVD outcomes. No effect estimate could be calculated due to marked heterogeneity in study populations, immune markers, outcomes and statistical approaches.

Interpretation

This review could not identify a clear association between any of the immune markers and surrogate CVD outcomes. This may reflect a true lack of association, or may be explained by heterogeneity across studies and lack of follow-up data. Future research should focus on longitudinal studies measuring a select set of immune markers and surrogate CVD outcomes awaiting the primary outcome of clinical cardiovascular events.

Oxidative Stress during HIV Infection: Mechanisms and Consequences

It is generally acknowledged that reactive oxygen species (ROS) play crucial roles in a variety of natural processes in cells. If increased to levels which cannot be neutralized by the defense mechanisms, they damage biological molecules, alter their functions, and also act as signaling molecules thus generating a spectrum of pathologies. In this review, we summarize current data on oxidative stress markers associated with human immunodeficiency virus type-1 (HIV-1) infection, analyze mechanisms by which this virus triggers massive ROS production, and describe the status of various defense mechanisms of the infected host cell. In addition, we have scrutinized scarce data on the effect of ROS on HIV-1 replication. Finally, we present current state of knowledge on the redox alterations as crucial factors of HIV-1 pathogenicity, such as neurotoxicity and dementia, exhaustion of CD4+/CD8+ T-cells, predisposition to lung infections, and certain side effects of the antiretroviral therapy, and compare them to the pathologies associated with the nitrosative stress.

Early Antiretroviral Therapy at High CD4 Counts Does Not Improve Arterial Elasticity: A Substudy of the Strategic Timing of AntiRetroviral Treatment (START) Trial

Background.

Both human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) may increase cardiovascular disease (CVD) risk. Vascular function assessments can be used to study CVD pathogenesis. We compared the effect of immediate versus deferred ART initiation at CD4 counts >500 cells/mm³ on small arterial elasticity (SAE) and large artery elasticity (LAE).

Methods.

Radial artery blood pressure waveforms were recorded noninvasively. Small arterial elasticity and LAE were derived from analysis of the diastolic pulse waveform. Randomized treatment groups were compared with linear models at each visit and longitudinal mixed models.

Results.

Study visits involved 332 participants in 8 countries: mean (standard deviation [SD]) age 35 (10), 70% male, 66% nonwhite, 30% smokers, and median CD4 count 625 cells/mm³ and 10-year Framingham risk score for CVD 1.7%. Mean (SD) SAE and LAE values at baseline were 7.3 (2.9) mL/mmHg × 100 and 16.6 (4.1) mL/mmHg × 10, respectively. Median time on ART was 47 and 12 months in the immediate and deferred ART groups, respectively. The treatment groups did not demonstrate significant within-person changes in SAE or LAE during the follow-up period, and there was no difference in mean change from baseline between treatment groups. The lack of significant differences persisted after adjustment, when restricted to early or late changes, after censoring participants in deferred group who started ART, and among subgroups defined by CVD and HIV risk factors.

Conclusions.

Among a diverse global population of HIV-positive persons with high CD4 counts, these randomized data suggest that ART treatment does not have a substantial influence on vascular function among younger HIV-positive individuals with preserved immunity.

Efavirenz and ritonavir-boosted lopinavir use exhibited elevated markers of atherosclerosis across age groups in people living with HIV in Ethiopia

BACKGROUND

HIV patients on highly-active antiretroviral therapy (HAART) have shown elevated incidence of dyslipidemia, lipodystrophy, and markers of cardiovascular disease. Evidence is beginning to emerge that implicates efavirenz (EFV) as a potential mediator of early on-set cardiovascular disease.

METHODS

Pediatric and adult HIV-infected HAART-naïve, EFV-treated, nevirapine (NVP)-treated, and ritonavir-boosted lopinavir (LPV/r)-treated subjects were recruited from Black Lion Hospital in Addis Ababa, Ethiopia. Pulse wave velocity (PWV), carotid intima-media thickness (cIMT), carotid arterial stiffness, brachial artery flow-mediated dilation (FMD), body mass index, waist-to-hip circumference ratio, and skinfold thickness were measured. CD4+ cell count, fasting glucose, lipoprotein profiles and triglycerides were also determined. Results were segmented into pediatric (6-17 years of age), young adults (25-39 years old) and older adults (40-60 years old).

RESULTS

PWV was generally elevated in EFV- and LPV/r-treated subjects compared to NVP-treated subjects across age groups. cIMT was elevated in EFV- and LPV/r-treated compared to NVP-treated older adults and in EFV-treated compared to HAART-naïve older adults. FMD was impaired in EFV- and LPV/r-treated compared to HAART-naïve younger adults, in EFV-treated compared to NVP-treated young and older adults, and in LPV/r-treated compared to NVP-treated older adults. Differences in lipoprotein profiles and skinfold thickness with HAART regimen were observed in pediatric and young adults, but less so in older adults.

CONCLUSIONS

Whereas LPV/r and other protease inhibitors have long been recognized as mediators of HIV/HAART-associated atherosclerosis, this report supports the emerging evidence that EFV may also mediate cardiovascular disease in people living with HIV on HAART.

Assessment of arterial elasticity among HIV-positive participants with high CD4 cell counts: a substudy of the INSIGHT Strategic Timing of AntiRetroviral Treatment (START) trial

OBJECTIVES

Both HIV infection and antiretroviral therapy (ART) may increase cardiovascular disease (CVD) risk. Assessments of vascular function and structure can be used to study the pathogenesis and progression of CVD, including the effects of ART and other interventions. The objective of this report is to understand methods to assess vascular (dys)function and report our experience in the Arterial Elasticity Substudy in the Strategic Timing of AntiRetroviral Treatment (START) trial.

METHODS

We review literature and analyze baseline data from the Arterial Elasticity Substudy, which estimated vascular (dys)function through analysis of the diastolic blood pressure (BP) waveform. Linear regression was used to study cross-sectional associations between baseline clinical factors and small or large arterial elasticity.

RESULTS

Arterial elasticity measurement was chosen for its improved measurement reproducibility over other methodologies and the potential of small arterial elasticity to predict clinical risk. Analysis of baseline data demonstrates that small artery elasticity is impaired (lower) with older age and differs by race and between geographical regions. No HIV-specific factors studied remained significantly associated with arterial elasticity in multivariate models.

CONCLUSIONS

Longitudinal analyses in this substudy will provide essential randomized data with which to study the effects of early ART initiation on the progression of vascular disease among a diverse global population. When combined with future biomarker analyses and clinical outcomes in START, these findings will expand our understanding of the pathogenesis of HIV-related CVD.

Efavirenz treatment causes arterial stiffening in apolipoprotein E-null mice

The development of highly active antiretroviral therapy (HAART) has transformed HIV-1 infection from a terminal diagnosis to a chronic, yet manageable disease. However, people living with HIV-1 exhibit a host of non-AIDS-related co-morbidities including cardiovascular disease (CVD). Several HAART drugs have been implicated in the development of CVD; however, the role of efavirenz (EFV), a highly prescribed HAART drug, in early-onset CVD is poorly understood. We treated apolipoprotein E-null (ApoE(-/-)) mice with EFV (75 mg/kg/day) or vehicle, via oral gavage, for 35 days and quantified commonly measured preclinical markers of CVD (intima-media thickening, arterial stiffening) and plaque area. Suprarenal abdominal aortas were subjected to cylindrical biaxial biomechanical testing and standard histology. Aortas from EFV-treated mice demonstrated decreased compliance (i.e., increased arterial stiffness) and decreased axial force and a trend toward decreased in vivo axial stretch, but EFV treatment had no effect on intima-media thickness of the aortic wall or plaque coverage in thoracic aortas and aortic arches. Taken together, these data suggest that EFV leads to arterial stiffening but, for the dose and duration tested, did not lead to elevated plaque progression in ApoE(-/-) mice.

Current Efavirenz (EFV) or ritonavir-boosted lopinavir (LPV/r) use correlates with elevate markers of atherosclerosis in HIV-infected subjects in Addis Ababa, Ethiopia

BACKGROUND

HIV patients on antiretroviral therapy have shown elevated incidence of dyslipidemia, lipodystrophy, and cardiovascular disease (CVD). Most studies, however, focus on cohorts from developed countries, with less data available for these co-morbidities in Ethiopia and sub-Saharan Africa.

METHODS

Adult HIV-negative (n = 36), treatment naïve (n = 51), efavirenz (EFV)-treated (n = 91), nevirapine (NVP)-treated (n = 95), or ritonavir-boosted lopinavir (LPV/r)-treated (n=44) subjects were recruited from Black Lion Hospital in Addis Ababa, Ethiopia. Aortic pressure, augmentation pressure, and pulse wave velocity (PWV) were measured via applanation tonometry and carotid intima-media thickness (cIMT) and carotid arterial stiffness, and brachial artery flow-mediated dilation (FMD) were measured via non-invasive ultrasound. Body mass index, waist-to-hip circumference ratio (WHR), skinfold thickness, and self-reported fat redistribution were used to quantify lipodystrophy. CD4+ cell count, plasma HIV RNA levels, fasting glucose, total-, HDL-, and LDL-cholesterol, triglycerides, hsCRP, sVCAM-1, sICAM-1, leptin and complete blood count were measured.

RESULTS

PWV and normalized cIMT were elevate and FMD impaired in EFV- and LPV/r-treated subjects compared to NVP-treated subjects; normalized cIMT was also elevated and FMD impaired in the EFV- and LPV/r-treated subjects compared to treatment-naïve subjects. cIMT was not statistically different across groups. Treated subjects exhibited elevated markers of dyslipidemia, inflammation, and lipodystrophy. PWV was associated with age, current EFV and LPV/r used, heart rate, blood pressure, triglycerides, LDL, and hsCRP, FMD with age, HIV duration, WHR, and glucose, and cIMT with age, current EFV use, skinfold thickness, and blood pressure.

CONCLUSIONS

Current EFV- or LPV/r-treatment, but not NVP-treatment, correlated with elevated markers of atherosclerosis, which may involve mechanisms distinct from traditional risk factors.

Increased arterial stiffness in HIV-infected children: risk factors and antiretroviral therapy

BACKGROUND

Recent evidence suggests that both the HIV virus and antiretroviral therapy (ART) are associated with premature atherosclerosis in adults. Increased arterial stiffness as assessed by pulse wave velocity (PWV) has been associated with adverse cardiovascular outcome in adults. The relationship between HIV infection and treatment and arterial stiffness has not been evaluated in children.

METHODS

We studied 83 HIV-infected children with a mean +/-sd age of 11.0 +/-3.1 years and 59 controls aged 12.2 +/-2.8 years. Among the HIV-infected children, 48 were receiving ART (23 including a protease inhibitor). Arterial stiffness was assessed non-invasively by carotid-radial PWV. Disease severity was defined according to the CDC classification.

RESULTS

PWV was significantly increased in HIV-infected children compared with controls (P<0.05). A significant association between age and PWV was noted in HIV-infected children but not in controls. HIV-infected children receiving ART had significantly increased total cholesterol levels and PWV compared with non-treated children (P<0.001 and P<0.05, respectively). CDC stage was greater in ART-treated compared with non-treated HIV-infected children (P<0.001). No differences in other cardiovascular risk factors were noted in the two groups. After multivariable analysis, ART, systolic blood pressure, disease severity and total cholesterol remained independent predictors of PWV.

CONCLUSIONS

HIV-infected children have increased arterial stiffness compared with healthy children. These changes were more pronounced with increasing age in HIV-infected children particularly in those who were receiving ART.