Infection duration and inflammatory imbalance are associated with atherosclerotic risk in HIV-infected never-smokers independent of antiretroviral therapy

Associations between Various Inflammatory Markers and Carotid Findings in a Voluntary Asymptomatic Population Sample

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide, and atherosclerosis is the key factor promoting its development. Carotid intima-media thickening and the presence of carotid plaques are important indices of cardiovascular risk. In addition, inflammation is a major and complex factor in the development of atherosclerosis. The relationships between carotid atherosclerosis and certain inflammatory markers have rarely been studied in healthy individuals. Therefore, we aimed to investigate the associations between subclinical carotid atherosclerosis and various inflammatory biomarkers in a large Caucasian population free of evident CVD. In addition to recording study participants' demographic characteristics, anthropometric characteristics, and atherosclerotic risk factors, laboratory tests were performed to measure levels of hemoglobin A1c (HbA1c), high-sensitivity C-reactive protein, and inflammatory cytokines/chemokines, including interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12p70, IL-17A, IL-18, IL-23, IL-33, interferon (IFN)-α2, IFN-γ, tumor necrosis factor-α, and monocyte chemoattractant protein (MCP)-1. This study included 264 asymptomatic individuals with a median age of 61.7 years (interquartile range, 54.5-67.5 years); 45.7% of participants were male. Participants were divided into two groups according to their carotid status: the normal carotid group, comprising 120 participants; and the pathological carotid group, comprising 144 participants. Compared with the normal carotid group, hypertension and diabetes mellitus were significantly more common and serum levels of HbA1c, IL-8, and MCP-1 were significantly higher in the pathological carotid group. Multivariate regression analysis revealed significant positive associations between pathological carotid findings and serum levels of IL-8 (highest tertile, OR: 2.4, p = 0.030) and MCP-1 (highest tertile, OR: 2.4, p = 0.040). Our results suggest that IL-8 and MCP-1 may serve as early indicators of subclinical atherosclerosis, thereby helping to identify individuals at increased risk of CVD before the onset of clinical symptoms.

High-sensitivity C-reactive protein among people living with HIV on highly active antiretroviral therapy: a systemic review and meta-analysis

The pathological consequences of inflammation persist in people living with the human immunodeficiency virus (PLWH), regardless of the positive outcomes of highly active antiretroviral therapy (HAART). The current systematic review and meta-analysis aims to understand and explore the levels of high-sensitivity C-reactive protein (hs-CRP) and other cardiovascular disease (CVD)-risk factors including lipid profiles among PLWH on HAART. Major electronic databases including PubMed, Scopus, and Web of Science were searched to retrieve relevant global literature reporting on hs-CRP levels in PLWH on HAART. A total of twenty-two studies with an average participant age of 40 years were eligible for this systematic review and meta-analysis. Majority of the included studies were from Africa (n = 11), the United States (n = 6), and Europe (n = 5). Our systemic review showed that most studies reported increased levels of hs-CRP among PLWH on HAART when compared to controls (PLWH not on HAART or those without HIV), especially in studies from Africa. This was supported by a meta-analysis showing significantly elevated levels of hs-CRP in PLWH on HAART when compared to PLWH not on HAART (standardised mean difference [SMD] = 0.56; 95% CI = 0.10‑1.01, z = 2.41; p = 0.02) or those without HIV (SMD = 1.19; 95% CI = 0.76‑1.63, z = 5.35; p < 0.001). Where lipid profiles, as a major predictor for CVD risk, were also impaired in PLWH on HAART when compared to PLWH not on HAART and HIV-negative participants. In conclusion, elevated levels of hs-CRP and lipid levels are prevalent in PLWH on HAART, this may increase the risk of CVD complications, especially for those people living in Africa. However, more evidence in larger population studies is required to confirm these outcomes and unveil any possible clinical implications of HAART-induced modulation of hs-CRP levels in PLWH.

Mean Coronary Cross-Sectional Area as a Measure of Arterial Remodeling Using Noncontrast CT Imaging in Persons With HIV

Background Persons with HIV have a higher prevalence of coronary artery disease compared with their HIV-negative counterparts. Earlier identification of subclinical atherosclerosis may provide a greater opportunity for cardiovascular disease risk reduction. We investigated coronary cross-sectional area (CorCSA) by noncontrasted computed tomography imaging as a noninvasive measure of arterial remodeling among virally suppressed persons with HIV. Methods and Results We assessed 105 persons with HIV with a spectrum of cardiometabolic health. All participants underwent computed tomography imaging to assess the mean corCSA of the proximal left anterior descending artery and 28 participants underwent additional coronary computed tomography angiography. Partial Spearman rank correlations adjusted for cardiovascular disease risk factors were used to assess relationships of corCSA with anthropometric measurements, HIV-related factors, and plasma cytokines. Mean corCSA measured by noncontrast computed tomography and coronary computed tomography angiography were strongly correlated (ρ=0.91, P<0.0001). Higher mean corCSA was present in those with coronary artery calcium (P=0.005) and it correlated with participants' atherosclerotic cardiovascular disease risk score (ρ=0.35, P=0.01). After adjusting for established cardiovascular disease risk factors, we observed an inverse relationship between corCSA and CD4+ T-cell count (ρ=-0.2, P=0.047). Removal of age from the model strengthened the relationships between corCSA and antiretroviral therapy duration (from ρ=0.19, P=0.08 to ρ=0.3, P=0.01). CorCSA was also inversely correlated with plasma IL-10 (ρ=-0.25, P=0.03) but had no relationship with IL-6 (ρ=0.11, P=0.4) or IL-1β (ρ=0.08, P=0.5). Conclusions Positive coronary arterial remodeling, an imaging marker of subclinical atherosclerosis, is associated with a lower CD4 T-cell count, lower circulating IL-10, and possibly a longer antiretroviral therapy duration in persons with HIV. Registration Clinicaltrials.gov; Unique identifier: NCT04451980.

Potential role of intermittent fasting on decreasing cardiovascular disease in human immunodeficiency virus patients receiving antiretroviral therapy

Cardiovascular disease (CVD) has become one of the commonest causes of comorbidity and mortality among People living with human immunodeficiency virus (HIV) (PLWH) on antiretroviral therapy (ART). Nearly 50% of PLWH are likely to have an increased risk of developing CVD, including coronary heart disease, cerebrovascular disease, peripheral artery disease and aortic atherosclerosis. Aside from the common risk factors, HIV infection itself and side effects of antiretroviral therapy contribute to the pathophysiology of this entity. Potential non-pharmacological therapies are currently being tested worldwide for this purpose, including eating patterns such as Intermittent fasting (IF). IF is a widespread practice gaining high level of interest in the scientific community due to its potential benefits such as improvement in serum lipids and lipoproteins, blood pressure (BP), platelet-derived growth factor AB, systemic inflammation, and carotid artery intima-media thickness among others cardiovascular benefits. This review will focus on exploring the potential role of intermittent fasting as a non-pharmacological and cost-effective strategy in decreasing the burden of cardiovascular diseases among HIV patients on ART due to its intrinsic properties improving the main cardiovascular risk factors and modulating inflammatory pathways related to endothelial dysfunction, lipid peroxidation and aging. Intermittent fasting regimens need to be tested in clinical trials as an important, cost-effective, and revolutionary coadjutant of ART in the fight against the increased prevalence of cardiovascular disease in PLWH.

The Effect of Rosuvastatin on Plasma/Serum Levels of High-Sensitivity C-Reactive Protein, Interleukin-6, and D-Dimer in People Living with Human Immunodeficiency Virus: A Systematic Review and Meta-Analysis

Rosuvastatin therapy might have an effect on the inflammatory and coagulation biomarkers. However, the evidence about the effect of rosuvastatin therapy on the high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), and D-dimer levels among people living with human immunodeficiency virus (PLHIV) is still unclear. Therefore, this study investigated the relational effect of rosuvastatin therapy on serum/plasma hsCRP, IL-6 and D-dimer levels in PLHIV. The literature search was done from Embase, PubMed, and Web of Science databases. The review and meta-analysis included studies written in English language up to January 4, 2020. Random effects model was used to evaluate the pooled standard mean difference with 95% confidence interval. A meta-analysis was performed using nine articles with 392 PLHIV. The result revealed that the plasma/serum levels of IL-6 were significantly reduced after the intervention. However, hsCRP and D-dimer levels showed no significant difference (p > .05) between before and after the intervention. The subgroup analysis showed that there was significant association between PLHIV ages <45 years and cohort studies with IL-6 levels. The current CD4⁺ counts ≥350 cells/mm³ correlated with hsCRP as well as IL-6. Similarly, nadir CD4⁺ counts ≥200 cells/mm³ and duration of HIV diagnosis <10 years also showed significant association with IL-6 and D-dimer levels. It was also indicated that participants who were under antiretroviral drug for <7 years were significantly associated with hsCRP levels. This study established that IL-6 levels were significantly reduced after the intervention while hsCRP and D-dimer levels showed no significant difference between before and after the intervention.

Evaluation of Platelet Activation by HIV Protease Inhibitors - The HIV-PLA II Study

Background

In the past, protease inhibitors (PIs) and the reverse transcriptase inhibitor abacavir were identified increasing the risk for thromboembolic complications and cardiovascular events (CVE) of HIV infected patients taking a combination antiretroviral therapy (cART). Results of the previous HIV-PLA I-study lead to the assumption that platelet activation could play a substantial role in increasing CVE risks.

Methods

The open label, monocentric HIV-PLA II-study investigated HIV-1-infected, therapy-naïve adults (n=45) starting with cART, consisting either of boosted PI (atazanavir, n= 6, darunavir, n=11), NNRTI (efavirenz, n=14) or integrase inhibitor (raltegravir, n=14), each plus tenofovir/emtricitabine co-medication. Main exclusion criteria were tobacco smoking, the intake of NSAIDs or abacavir or past CVE. Platelet adhesive molecule p-selectin (CD62P) and FITC anti-human Integrin α-IIb/Integrin β-3 (CD41/CD61) antibody (PAC-1) binding, monocyte CD11b/monocyte-associated CD41 expression and the endogenous thrombin potential (ETP) were assessed ex vivo-in vitro at baseline, weeks 4, 12 and 24. Therapy regimens were blinded to the investigators for laboratory and statistical analyses.

Results

CD11b and ETP showed no significant changes or differences between all study groups. In contrast, the mean + SD mean fluorescence units (MFI) of CD62P and PAC-1 increased significantly in patients taking PI, indicating an enhanced potential for thrombocyte activation and aggregation.

Conclusion

CD62P expression, detecting the ɑ-platelet degranulation of pro-inflammatory and pro-thrombotic factors and adhesive proteins, and PAC-1 expression, representing a marker for conformation changes of the GIIb/IIIa receptor, increased significantly in patients taking HIV protease inhibitors. The findings of this study revealed a yet unknown pathway of platelet activation, possibly contributing to the increased risk for CVE under HIV protease inhibitor containing cART.

Clinical Trial Registration No.

DRKS00000288.

Prevalence of Silent Atherosclerosis and Other Comorbidities in an Outpatient Cohort of Adults Living with HIV: Associations with HIV Parameters and Biomarkers

People living with HIV (PLWH) are at risk of noninfectious comorbidities. It is important to individualize those at higher risk. In a single-center cohort of PLWH, we performed a cross-sectional analysis of comorbidities, diagnosed according to standard procedures. The primary endpoint was the prevalence of subclinical carotid/coronary atherosclerosis. Secondary endpoints were its association with selected inflammatory/immune activation biomarkers and with other comorbidities. Associations were examined by using Chi-square or Fisher's exact test for categorical variables and Student or Wilcoxon tests for quantitative variables, and a stepwise multivariate logistical model was performed for further exploration. Among 790 participants [median age: 49.8 years (interquartile range, IQR: 44.5-55.6), 77.1% males, median CD4: 536/mm³ (IQR: 390-754), 83.6% with undetectable viral load], asymptomatic atherosclerosis was found in 26% and was associated in multivariate analysis with older age, longer known duration of infection, higher sCD14, and lower adiponectin levels. Hypertension was found in 33.5% of participants, diabetes in 19.4%, renal impairment in 14.6%, elevated low-density lipoprotein-cholesterol in 13.3%, elevated triglyceride/high-density lipoprotein (HDL)-cholesterol ratio in 6.6%, and osteoporosis in 7.9%. The presence of two or more comorbidities was found in 42.1% of participants and was associated in multivariate analysis with older age and longer exposure to antiretrovirals. Comorbidities were diversely associated with biomarkers: osteoporosis with higher IL-6, renal impairment with higher sCD14, hypertension with higher D-dimer, diabetes and elevated triglyceride/HDL-cholesterol ratio both with lower adiponectin and lower 25-hydroxyvitamin D. Asymptomatic atherosclerosis and multimorbidity were frequent in a cohort of middle-aged, well-controlled, PLWH and were associated with traditional and HIV-specific factors. Associations between morbidities and inflammatory/immune activation biomarkers were diverse.

Cardiovascular Disease Burden in Rural Africa: Does HIV and Antiretroviral Treatment Play a Role?: Baseline Analysis of the Ndlovu Cohort Study

Background

HIV is associated with an increased risk of cardiovascular disease (CVD) in high‐income countries. Little is known about the CVD burden in sub‐Saharan Africa, where 70% of the world's HIV‐positive population lives. This study aims to provide insight into the burden of CVD risk in a rural setting in sub‐Saharan Africa considering HIV infection and antiretroviral therapy (ART).

Methods and Results

A cross‐sectional analysis was conducted of the baseline of the Ndlovu Cohort study including HIV‐negative and HIV‐positive participants in rural South Africa between 2014 and 2017. Information was collected on demographics, socioeconomic status, and CVD risk factors. Carotid intima‐media thickness measurement was performed. The influence of HIV and ART on the burden of CVD was determined by comparing HIV‐positive participants who were ART naive on first‐line or second‐line ART with HIV‐negative participants. In total, 1927 participants were included, of whom 887 (46%) were HIV positive and 54% women. The median age was 38 years. Overall, 690 participants (79%) were on ART, with 613 (89%) on first‐line and 77 (11%) on second‐line therapy. Participants with HIV had lower values for most of the CVD risk factors but higher C‐reactive protein levels than HIV‐negative participants. ART‐naive, HIV‐positive participants had similar carotid intima‐media thickness compared with HIV‐negative participants but carotid intima‐media thickness was increased for participants on ART aged 30 years and older compared with HIV‐negative participants.

Conclusions

HIV‐positive participants presented with a favorable CVD risk profile compared with HIV‐negative participants. However, carotid intima‐media thickness was increased in HIV‐positive participants on ART, indicating a higher burden of subclinical CVD for the HIV‐positive population.

Anti-Inflammatory Interleukin 10 Inversely Relates to Coronary Atherosclerosis in Persons With Human Immunodeficiency Virus

Interleukin 10 (IL-10) is an anti-inflammatory cytokine that may be protective against coronary atherosclerosis. In an observational study of persons with human immunodeficiency virus (PWH) and uninfected controls, IL-10 was measured in serum samples by means of enzyme-linked immunosorbent assay, and coronary atherosclerosis was assessed using computed tomographic angiography. Among PWH, a 10-fold decrease in IL-10 was associated with a 2.6-fold increase in the odds of coronary plaque (P = .01), after controlling for traditional and nontraditional cardiovascular risk factors. IL-10 was also inversely associated with total coronary plaque (ρ = -0.19; P = .02) and noncalcified coronary plaque (ρ = -0.24; P = .004). Our findings suggest a role for IL-10 in mitigating atherosclerosis in PWH. Clinical Trials Registration. NCT00455793.

Coronary Heart Disease in HIV-Infected Patients

Currently, there are methods of drug exposure to the infection caused by the human immunodeficiency viruses (HIV), that allow to suppress the active replication of the virus in the patient's body. The era of antiretroviral therapy, which has allowed HIV-infected people to live longer, has begun. This led to an increase in their cardiovascular diseases, which occur at an earlier age and are more severe than in people without HIV. Specific or “nontraditional” risk factors damaging vascular wall occur in HIV patients along with traditional risk factors. These factors include: the negative impact of HIV on endothelium, an imbalance of inflammatory mediators, pathological immune activation, a decrease in the level of CD4 cells, a change in the number and function of platelets. The question of the effect of antiretroviral therapy on the occurrence of atherosclerotic vascular lesions remains debatable. Acute coronary syndrome (ACS) is one of the most frequent and most severe cardiovascular events in HIV-infected patients. The risk of myocardial infarction is highest in patients with a viral load of HIV-1 ribonucleic acid (RNA)≥500 copies/ml and a CD4 cell count of <200/ml. The most common form of ACS in HIV patients is ACS with ST segment elevation. Treatment of ACS in HIV patients has some difficulties: a high frequency of stent thrombosis, the frequent occurrence of thrombocytopenia, drug interactions with antiretroviral therapy. The high risk of developing cardiovascular diseases in HIV patients necessitates the introduction of active measures of primary and secondary prevention, taking into account the specific interaction of all drugs taken by the patient.

Serum Tryptophan-Derived Quinolinate and Indole-3-Acetate Are Associated With Carotid Intima-Media Thickness and its Evolution in HIV-Infected Treated Adults

Background

HIV-infected individuals undergoing effective antiretroviral therapy (ART) present an increased risk of atherosclerotic cardiovascular disease. We identified serum metabolites associated with carotid intima-media thickness (c-IMT) and its evolution.

Methods

One hundred forty-three hydrophilic serum metabolites were measured by ultraperformance liquid chromatography coupled with high-resolution mass spectrometry in 49 HIV+ ART+, 48 HIV+ ART-naïve and 50 HIV-negative, age-matched, never-smoking male triads. Metabolites differentially altered between groups ("features") were defined as having a Benjamini-Hochberg-adjusted P value <.05 from a t test and >0.25 log₂ absolute mean fold change in metabolite levels. c-IMT was measured across 12 sites at inclusion in all individuals and at the carotid artery (cca) after a median of 5.1 years in 32 HIV+ ART+ individuals. The difference in c-IMT (cross-sectional analysis) and slope of cca-IMT regression/progression per year (longitudinal analysis) for each log₁₀ (area) increase in metabolite level were estimated with linear regression.

Results

Compared with HIV-, metabolite features of HIV+ ART+ were increased N6,N6,N6-trimethyl-L-lysine and decreased ferulate and 5-hydroxy-L-tryptophan, whereas features of HIV+ ART-naïve were increased malate, kynurenine, 2-oxoglutarate, and indole-3-acetate and decreased succinate and 5-hydroxy-L-tryptophan. In HIV+ ART+ individuals, quinolinate and/or indole-3-acetate were positively associated with c-IMT (P < .03), cca-IMT (P < .03), and cca-IMT progression (P < .008). These associations were not observed in HIV+ ART-naïve or HIV-negative individuals. In HIV+ ART+ individuals, the metabolites xanthosine and uridine, from nucleotide metabolism, and g-butyrobetaine, from lysine/dietary choline degradation, were also positively or negatively associated with c-IMT and/or cca-IMT (all P < .01), but not its evolution.

Conclusions

In these highly selected HIV-positive ART-controlled males, 2 novel metabolites derived from tryptophan catabolism, indole-3-acetate and quinolinate, were associated with c-IMT and its progression.

The effect of HIV infection, antiretroviral therapy on carotid intima-media thickness: A systematic review and meta-analysis

AIMS

We performed a systematic review and meta-analysis on the effect of HIV infection and antiretroviral therapy (ART) on carotid intima-media thickness (cIMT) to elucidate the role of HIV infection and ART. Also, an analysis on the role of ethnicity and gender on cIMT in HIV-infected populations was performed.

MAIN METHODS

We searched the PubMed, Web of Science, the WHO websites and International AIDS Society for published observational studies were conducted by two independent reviewers for studies comparing HIV-infected antiretroviral-experienced patients and/or inexperienced with healthy controls on cIMT. The primary outcome was the standardized mean difference (SMD) of cIMT.

FINDINGS

Twenty studies (five cohort, 15 cross-sectional, and two both cohort and cross-sectional studies) were identified comprising 7948 subjects (4656 HIV-infected; 3292 controls). In cohort studies, the standardized mean 1-year change in cIMT between HIV-infected patients and uninfected controls was not significantly different (0.16 mm/yr; 95% CI, -0.16, 0.49; p = 0.326). In 17 cross-sectional studies, the SMD in cIMT was significantly higher in HIV-infected than uninfected persons (0.27 mm; 95% CI, 0.04, 0.49; p = 0.027). HIV-infected patients on ART exhibited significantly higher SMD in cIMT compared to those not on ART (0.75 mm; 95% CI, 0.30, 1.19; p = 0.001). No confounding effect of gender and ethnicity could be established using meta-regression p > 0.05.

SIGNIFICANCE

HIV infection itself and ART appear to influence the progression of cIMT and hence may be risk factors for cardiovascular events. No firm conclusions could be drawn on the effect of ethnic/race and gender differences on cIMT in HIV-infected populations.

Significant chronic airway abnormalities in never-smoking HIV-infected patients

OBJECTIVES

The aim of the study was to describe chronic lung disease in HIV-infected never-smokers by looking at clinical, structural and functional abnormalities.

METHODS

This comparative cross-sectional study included 159 HIV-infected never-smoking patients [mean (± standard deviation) age 54.6 ± 9.1 years; 13.2% female; 98.1% with undetectable viral load] and 75 nonmatched never-smoking controls [mean (± standard deviation) age 52.6 ± 6.9 years; 46.7% female]. We examined calcium scoring computer tomography (CT) scans or chest CT scans, all with a lung-dedicated algorithm reconstruction, to assess emphysema and airway disease (respiratory bronchiolitis and/or bronchial wall thickening), tested pulmonary function using spirometry, lung volumes and the diffusion lung capacity of carbon monoxide (DLCO), and assessed respiratory symptoms using the Chronic Obstructive Pulmonary Disease (COPD) Assessment Test (CAT).

RESULTS

Twenty-five (17.2%) of the HIV-infected patients versus two (2.7%) of the controls had a CAT score > 10. Only 5% of the HIV-infected patients showed FEV1% < 80%, and 25% had DLCO < 75% of the predicted value. Based on the CT scans, they had increased prevalences, compared with the controls, of airway disease (37% versus 7.9%, respectively) and emphysema (18% versus 4%, respectively), with more severe and more frequent centrilobular disease. After correction for age, sex and clinical factors, HIV infection was significantly associated with CAT > 10 [odds ratio (OR) 7.7], emphysema (OR 4), airway disease (OR 4.5) and DLCO < 75% of predicted (OR 4).

CONCLUSIONS

Although comparisons were limited by the different enrolment methods used for HIV-infected patients and controls, the results suggest that never-smoking HIV-infected patients may present with chronic lung damage characterized by CT evidence of airway disease. A minority of them showed respiratory symptoms, without significant functional abnormalities.

Changes in cardiovascular risk and clinical outcomes in a HIV/AIDS cohort study over a 1-year period at a specialized clinic in Mexico

INTRODUCTION

The third report of the National Cholesterol Education Program guidelines recommends calculating the 10-year morbidity of atherosclerotic cardiovascular disease (ASCVD) using risk calculators when treating high blood cholesterol in adults. We analyzed the changes in cardiovascular risk (CVR) among Mexican patients with HIV.

PATIENTS AND METHODS

This observational, prospective cohort study compared the CVR after 1 year of antiretroviral treatment among 460 HIV patients from a Mexican clinic. Changes using the ASCVD risk estimator and changes in clinical outcomes were analyzed. The results were categorized as low or high CVR using a cutoff of 7.5%.

RESULTS

The CVR initially had a median of 2.3% (interquartile range [IQR]: 1%-4.8%), which changed to 2.4% (IQR: 1.5%-5.5%) after 1 year (P=0.001). After CVR stratification, we found that 84.3% of the patients had a low CVR, and 18% in this subgroup had metabolic syndrome (MS). Moreover, 15.7% had high CVR, and 47% in this subgroup had MS. The 4.3% of patients had an increase in CVR from the low to high subgroup, and 2.6% had a decrease in CVR from the high to low subgroup. Out of all patients, 22.3% had MS.

CONCLUSION

More than 50% of the population had an increase in CVR after 1 year. Of these patients, 4.3% changed from the low to high CVR group. Although the guidelines proposed different time periods for performing CVR estimations, this study showed that such assessments offered valuable clinical data over a relatively short-term period.

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.

Subclinical atherosclerosis in low Framingham risk HIV patients

BACKGROUND

Pathogenesis of atherosclerosis is complex, and differences between HIV-infected patients and general population cannot be completely explained by the higher prevalence of traditional cardiovascular risk factors. We aimed to analyse the association between inflammation and subclinical atherosclerosis in HIV patients with low Framingham risk score.

MATERIALS AND METHODS

Case-control study.

SETTING

Outpatient Infectious Diseases clinic in a university hospital.

SUBJECTS

HIV-1-infected patients aged > 35 years receiving antiretroviral treatment with viral load < 50 copies/mL and Framingham risk score < 10%.

EXCLUSION CRITERIA

inflammatory diseases; dyslipidaemia requiring statins; smoking > 5 cigarettes/day; diabetes; hypertension; vascular diseases.

MAIN OUTCOME

subclinical atherosclerosis determined by ultrasonography: common carotid intima-media thickness greater than 0·8 mm or carotid plaque presence. Explanatory variables: ribosomal bacterial DNA (rDNA), sCD14, interleukin-6 (IL-6) and TNF-α.

RESULTS

Eighty-four patients were included, 75% male, mean age 42 years and mean CD4+ cells 657 ± 215/mm³ . Median Framingham risk score was 1% at 10 years (percentile 25-75: 0·5-4%). Eighteen patients (21%) had subclinical atherosclerosis; the associated factors were older age (P = 0·001), waist-hip ratio (P = 0·01), time from HIV diagnosis (P = 0·02), rDNA (P = 0·04) and IL-6 (P = 0·01). In multivariate analysis, OR for subclinical atherosclerosis was 7 (95% CI, 1.3-40, P = 0.02) and 9 (95% CI, 1.0-85, P = 0.04) for patients older than 44 years and IL-6 > 6·6 pg/mL, respectively.

CONCLUSIONS

Well-controlled HIV patients with low Framingham risk score have a high prevalence of subclinical carotid atherosclerosis, and the main risk factors are age and inflammation. These patients are not receiving primary prophylaxis for cardiovascular events according to current guidelines.

Pre-clinical carotid atherosclerosis and sCD163 among virally suppressed HIV patients in Botswana compared with uninfected controls

Objectives

Human immune deficiency virus (HIV) is associated with increased cardiovascular disease (CVD) risk, yet the relationship between HIV and carotid atherosclerosis / monocyte activation among virally suppressed HIV-infected patients in sub-Saharan Africa is not well understood.

Methods

We measured traditional CVD risk factors, bilateral distal common carotid intima media thickness (cIMT), presence of carotid plaque and plasma sCD163 levels among virally suppressed HIV-infected adults and HIV-uninfected controls, in a cross-sectional study in Gaborone, Botswana. The associations between HIV status, traditional CVD risk factors, sCD163 and outcome of cIMT were assessed in univariate and multivariate linear regression models.

Results

We enrolled 208 HIV-infected adults (55% Female, mean age 39 years) who had undetectable HIV-1 RNA on antiretroviral therapy and 224 HIV-uninfected controls (47% Female, mean age 37 years). There was no difference in cIMT between study groups, with mean cIMT 0.607mm and 0.599mm in HIV-infected and HIV-uninfected, respectively (p = 0.37). Plasma sCD163 was significantly higher in HIV-infected versus HIV-uninfected persons (1917ng/ml vs 1593ng/ml, p = 0.003), but was not associated with cIMT (p = 0.43 among all, p = 0.72 for HIV-infected only). In the final multivariate model, increased cIMT was associated with older age, being treated for hypertension, and higher non-HDL cholesterol among all (p<0.001, p = 0.03, p<0.001 respectively), and with older age and waist-hip ratio in HIV-infected participants (p = 0.02 & p = 0.02 respectively). Carotid plaque was present in a significantly higher proportion of HIV-infected adults (RR 2.15, 95% CI 1.22, 3.81).

Conclusions

HIV-infected participants aged 30–50 years who have achieved viral suppression did not have increased cIMT when compared to HIV-uninfected controls in Botswana. However, well-controlled HIV was associated with excess monocyte activation. Future work should explore the impact of subclinical atherosclerosis on CVD events among HIV-infected and -uninfected adults in Botswana.

START or SMART? Timing of Antiretroviral Therapy Initiation and Cardiovascular Risk for People With Human Immunodeficiency Virus Infection

The Initiation of Antiretroviral Therapy in Early Asymptomatic HIV Infection (START) study has reinforced the benefits of early initiation of antiretroviral therapy (ART). However, a notable secondary finding from that study was that immediate initiation of ART did not prevent cardiovascular disease (CVD) events (0.17 vs 0.20 events/1000 person-years, P = .65). This result appears to contradict a body of evidence, most notably from the Strategies for Management of Antiretroviral Therapy (SMART) study, which reported a 70% increased hazard of cardiovascular events for those deferring or interrupting treatment. Thus, an important unresolved question is whether the timing of ART impacts CVD risk. In this review, published data on relationships between timing of ART and CVD risk are reviewed. The data support a role for ART in mitigating CVD risk at lower CD4 counts, but data also suggests that, among those initiating therapy early, ART alone appears to suboptimally mitigate CVD risk. Additional interventions to address CVD risk among human immunodeficiency virus-infected populations are likely to be needed.

Thromboelastography on plasma reveals delayed clot formation and accelerated clot lyses in HIV-1 infected persons compared with healthy controls

Background

Thromboembolic events among HIV infected persons are a recognized clinical problem but the underlying mechanisms are poorly understood. To assess whether coagulation and fibrinolysis differ between long-term treated HIV infected individuals (HIV+) and healthy controls (CON), we investigated functional plasma coagulation by thrombelastography (TEG) and plasma markers of endothelial and platelet activation.

Methods

In 67 successfully long-term treated HIV+ and 15 CON we analyzed stored plasma samples by TEG, with or without addition of tissue-type plasminogen activator (tPA), and measured levels of C-reactive protein, thrombomodulin, syndecan-1, sVE-cadherin, soluble CD40 ligand (sCD40L), adrenaline and noradrenaline.

Results

Compared to CON, HIV+ had delayed clot formation (reaction (R)-time 14.2 min. vs. 11.2 min., p = 0.0004) and reduced clot formation rapidity (angle 22.6° vs. 48.6 °, p = <0.0001). Clot lyses induced by tPA was accelerated in HIV+ displaying enhanced clot degradation after 30 and 60 min (53.9 % vs. 24.2 %, p < 0.0001 and 77.4 % vs. 59.9 %, p < 0.0001, respectively). sCD40L and TEG R-time correlated negatively in both HIV+ and CON (Rho =−0.502, p < 0.001 and rho =−0.651, p = 0.012).

Discussion

No previous studies have examined plasma coagulation by TEG in HIV, however, we have previously demonstrated that HIV+ display hypocoagulability in whole blood by TEG in accordance with the results of this study. Others have reported of HIV associated changes in the hemostatic system in a pro-coagulant direction based on measurements of isolated components of the coagulation pahways. In disease conditions, the flowing blood may change from “normal” to hyper- or hypocoagulant or to hyper- or hypofibrinolytic. A balance may exist in the flowing blood, i.e. between blood cells and the plasma phase, so that pro-coagulant blood cells are balanced by a hypocoagulable plasma phase; thus alterations that may promote thromboembolic events in the patient may at the same time appear as a hypocoagulable profile when evaluated in vitro.

Conclusion

Plasma from long-term treated HIV infected persons displays a hypocoagulable profile with reduced fibrinolytic resistance as compared to healthy controls.

Is the atherosclerotic process accentuated under conditions of HIV infection, antiretroviral therapy, and protease inhibitor exposure? Meta-analysis of the markers of arterial structure and function

OBJECTIVE

To evaluate the apparent association of human immunodeficiency virus (HIV) infection, antiretroviral therapy (ART), and protease inhibitor (PI) exposure with the functional and structural markers of vasculature.

METHODS

A meta-analysis of the relationship between HIV infection, ART, and PI exposure and the functional and structural markers of vasculature. A systematic literature search was performed electronically using specific eligibility criteria. Weighted mean difference (WMD) and corresponding 95% confidence interval (CI) were calculated and combined appropriately.

RESULTS

Fifty-seven articles were included with nine different outcomes. Compared with HIV-negative patients, HIV-positive patients demonstrated significant elevated intima-media thickness (IMT) (WMD (95% CI) = 0.042 (0.028-0.057)), increased pulse wave velocity (PWV) (0.538 (0.283-0.792)), and reduced flow-mediated vasodilation (FMD) (-2.049 (-2.806 to -1.293)). Elevated IMT was observed in HIV patients receiving ART when compared with those naïve to ART in the 20- to 40-year-old age group (0.078 (0.033-0.123)), the >40-year-old age group (0.038 (0.018-0.057)), and the group comprising >50% males (0.070 (0.041-0.099)). In addition, ART resulted in an increased PWV in HIV patients receiving ART in the group with >50% male proportion (0.628 (0.405-0.851)). HIV patients exposed to PI showed a significant trend toward elevated IMT (0.033 (0.007-0.058)) and increased PWV (0.264 (0.118-0.410)) compared with those without PI exposure.

CONCLUSIONS

The atherosclerotic process was accentuated by elevated IMT, increased PWV, and reduced FMD under condition of HIV infection. Comparison of ART-receiving with ART-naïve patients showed a significant trend toward elevated IMT and increased PWV, especially under treatment with PI-containing drugs.

Increased systemic immune activation and inflammatory profile of long-term HIV-infected ART-controlled patients is related to personal factors, but not to markers of HIV infection severity

OBJECTIVES

The objective of this study was to analyse the respective roles of personal factors and HIV infection markers on the systemic immune activation/inflammatory profile of long-term antiretroviral treatment-controlled patients.

PATIENTS AND METHODS

A panel of soluble immune activation/inflammatory biomarkers was measured in 352 HIV-infected treatment-controlled patients from the APROCO-COPILOTE cohort, all of whom were started on a PI in 1997-99 and had a final evaluation 11 years later, and in 59 healthy controls.

RESULTS

A total of 81.5% of the patients were male, with the following characteristics: median age 49 years; 620 CD4 cells/mm(3); 756 CD8 cells/mm(3); CD4/CD8 ratio 0.81; BMI 23.0 kg/m(2); waist-to-hip ratio 0.95. Markers of inflammation-high-sensitivity (hs) IL-6 (median and IQR) (1.3 pg/L, 0.7-2.6), hs C-reactive protein (CRP) (2.1 mg/L, 0.9-4.5) and D-dimer (252 ng/mL, 177-374)-were elevated compared with healthy controls (P < 0.001) and strongly related to each other, as were markers of immune activation [soluble (s) CD14 (1356 ng/mL, 1027-1818), β2-microglobulin (2.4 mg/L, 2.0-3.1) and cystatin-C (0.93 mg/L, 0.82-1.1)]. Inflammatory and immune activation markers were also associated with each other. In HIV-infected patients: age was related to D-dimer, β2-microglobulin and cystatin-C levels; being a smoker was related to increased IL-6 and cystatin-C; and BMI and waist-to-hip ratio were related to CRP. Conversely, markers of HIV infection, current CD4 or CD8 values, CD4 nadir, CD4/CD8 ratio, AIDS stage at initiation of PIs, current viral load and duration of ART were not associated with immune activation/inflammation markers.

CONCLUSIONS

In these long-term treatment-controlled HIV-infected patients, all systemic markers of inflammation and immune activation were increased compared with healthy controls. This was related to demographic and behavioural factors, but not to markers of severity of the HIV infection. Intervention to decrease low-grade inflammation must thus prioritize modifiable personal factors.

Plaque burden in HIV-infected patients is associated with serum intestinal microbiota-generated trimethylamine

OBJECTIVE

Some intestinal microbiota-generated metabolites of phosphatidylcholine are recognized to be proatherogenic. As the HIV population is vulnerable to cardiovascular disease and can develop intestinal dysbiosis associated with systemic inflammation, we investigated the novel relationship between microbiota-derived metabolites of phosphatidylcholine and coronary atherosclerosis in HIV.

DESIGN/METHODS

One hundred and fifty-five HIV-infected and 67 non-HIV-infected individuals without known history of cardiovascular disease were previously recruited to assess coronary plaque by computed tomography angiography. In the current study, we evaluate whether serum choline, trimethylamine (TMA), or trimethylamine-N-oxide (TMAO) levels are associated with plaque features.

RESULTS

Young, asymptomatic HIV-infected patients (age 47 ± 7 years) demonstrated significantly higher prevalence of plaque (53 vs. 35%, P = 0.01) and number of total plaque segments (1.8 ± 2.5 vs. 1.2 ± 2.2, P = 0.03) when compared with well matched noninfected individuals with similar comorbidities. TMA was significantly associated with calcium score (r = 0.22, P = 0.006), number of total (r = 0.20, P = 0.02) and calcified (r = 0.18, P = 0.03) plaque segments, and calcium plaque volume (r = 0.19, P = 0.02) and mass (r = 0.22, P = 0.009) in the HIV cohort only. In multivariate modeling among HIV-infected patients, TMA remained significantly associated with calcium score (P = 0.008), number of total (P = 0.005) and calcified (P = 0.02) plaque segments, and calcium plaque volume (P = 0.01) and mass (P = 0.007), independent of Framingham risk score. In contrast, there was no association of TMAO to coronary plaque features in either cohort.

CONCLUSION

A link between TMA and atherosclerosis has not previously been established. The current study suggests that TMA may be a nontraditional risk factor related to the number of plaque segments and severity of calcified plaque burden in HIV.

Increased carotid intima-media thickness is not associated with T-cell activation nor with cytomegalovirus in HIV-infected never-smoker patients

OBJECTIVES

Increased risk of cardiovascular disease in patients infected with HIV has been attributed to immune activation, inflammation, and immunosenescence, all of which are linked to chronic immune activation by viral infections, particularly cytomegalovirus (CMV). Our aim is to evaluate the impact of these atherogenic markers in HIV-infected patients who never smoked.

DESIGN

Exposure-matched, cross-sectional study.

METHODS

In 59 HIV-infected individuals [n = 30 undergoing ≥4 years of antiretroviral therapy (ART); n = 29 never treated with ART] and 30 age-matched HIV-negative controls, we measured the level of activation and senescence, as well as the frequency of CMV-specific T cells, on peripheral blood mononuclear cells, while examining their association with carotid intima-media thickness. Partial correlations were adjusted for age, systolic blood pressure, and nadir CD4 cell count.

RESULTS

The previously described roles of T-cell activation, CMV, and immunosenescence in the atherosclerotic risk of HIV-infected patients, as assessed by carotid intima-media thickness, were not apparent in our cohort of particularly 'healthy' HIV-infected never-smokers.

CONCLUSION

In HIV-infected individuals at low cardiovascular disease risk, our data show that the increased risk of carotid atherosclerosis is not associated with immunological markers described to be associated with HIV disease progression.

Cardiovascular disease risk in an aging HIV population: not just a question of biology

PURPOSE OF REVIEW

The objective of this review is to appraise recently published literature that describes the relationship between HIV, biologic and environmental risk factors, and cardiovascular disease (CVD) risk with particular emphasis on the aging HIV population and to demonstrate that these biologic and environmental factors may interact to increase the risk of CVD in the HIV population.

RECENT FINDINGS

The mechanisms linking HIV and CVD are multifactorial and encompass biological and 'environmental' modalities including multimorbid conditions that co-occur with HIV, immunologic alterations associated with HIV, polypharmacy (which affects adherence and increases likelihood of adverse drug-drug interactions) and healthcare disparities in CVD risk reduction by HIV status.

SUMMARY

Data regarding optimal treatment strategies that balance immunological restoration and CVD risk reduction are needed.

Association of residual plasma viremia and intima-media thickness in antiretroviral-treated patients with controlled human immunodeficiency virus infection

Background

While residual plasma viremia is commonly observed in HIV-infected patients undergoing antiretroviral treatment (ART), little is known about its subclinical consequences.

Methods

This cross-sectional study included 47 male, never-smoking, non-diabetic patients with ≥4 years of ART and controlled HIV-replication (HIV-viral load, VL <20 copies/mL for ≥1 year). Residual HIV-VL was measured using an ultrasensitive assay (quantification limit: 1 copy/ml). Patients were categorized as having detectable (D; 1-20 copies/mL, n = 14) or undetectable (UD; <1 copies/mL, n = 33) HIV-VL. Linear regression was used to model the difference in total carotid intima-media thickness [c-IMT, measures averaged across common carotid artery (cca), bifurcation, and internal carotid artery] and cca-IMT alone across detection groups. Multivariable models were constructed for each endpoint in a forward-stepwise approach.

Results

No significant differences were observed between viremia groups with respect to median ART-duration (9.6 years, IQR = 6.8–10.9), nadir CD4+T-cell (208/mm³, IQR = 143–378), and CD4+T-cell count (555/mm³, IQR = 458–707). Median adjusted inflammatory markers tended to be higher in patients with D- than UD-viremia, with differences in IL-10 being significant (p = 0.03). After adjustment on age, systolic blood pressure, and insulin resistance, mean cca-IMT was significantly lower in patients with undetectable (0.668 mm±0.010) versus detectable viremia (0.727 mm±0.015, p = 0.002). Cca-IMT was also independently associated with age and insulin resistance. Mean adjusted total c-IMT was no different between viremia groups (p = 0.2), however there was large variability in bifurcation c-IMT measurements.

Conclusions

Higher cca-IMT was observed in patients with detectable, compared to undetectable, HIV-VL in never-smoking ART-controlled patients, suggesting that residual HIV viremia may be linked to atherosclerosis.

HIV-1 protein Nef inhibits activity of ATP-binding cassette transporter A1 by targeting endoplasmic reticulum chaperone calnexin

HIV-infected patients are at increased risk of developing atherosclerosis, in part due to an altered high density lipoprotein profile exacerbated by down-modulation and impairment of ATP-binding cassette transporter A1 (ABCA1) activity by the HIV-1 protein Nef. However, the mechanisms of this Nef effect remain unknown. Here, we show that Nef interacts with an endoplasmic reticulum chaperone calnexin, which regulates folding and maturation of glycosylated proteins. Nef disrupted interaction between calnexin and ABCA1 but increased affinity and enhanced interaction of calnexin with HIV-1 gp160. The Nef mutant that did not bind to calnexin did not affect the calnexin-ABCA1 interaction. Interaction with calnexin was essential for functionality of ABCA1, as knockdown of calnexin blocked the ABCA1 exit from the endoplasmic reticulum, reduced ABCA1 abundance, and inhibited cholesterol efflux; the same effects were observed after Nef overexpression. However, the effects of calnexin knockdown and Nef on cholesterol efflux were not additive; in fact, the combined effect of these two factors together did not differ significantly from the effect of calnexin knockdown alone. Interestingly, gp160 and ABCA1 interacted with calnexin differently; although gp160 binding to calnexin was dependent on glycosylation, glycosylation was of little importance for the interaction between ABCA1 and calnexin. Thus, Nef regulates the activity of calnexin to stimulate its interaction with gp160 at the expense of ABCA1. This study identifies a mechanism for Nef-dependent inactivation of ABCA1 and dysregulation of cholesterol metabolism.

Increased coronary vessel wall thickness in HIV-infected young adults

BACKGROUND

Individuals with long-term human immunodeficiency virus (HIV) infection are at risk for premature vasculopathy and cardiovascular disease (CVD). We evaluated coronary vessel wall thickening, coronary plaque, and epicardial fat in patients infected with HIV early in life compared with healthy controls.

METHODS

This is a prospective cross-sectional study of 35 young adults who acquired HIV in early life and 11 healthy controls, free of CVD. Time resolved phase-sensitive dual inversion recovery black-blood vessel wall magnetic resonance imaging (TRAPD) was used to measure proximal right coronary artery (RCA) wall thickness, and multidetector computed tomography (CT) angiography was used to quantify coronary plaque and epicardial fat.

RESULTS

RCA vessel wall thickness was significantly increased in HIV-infected patients compared with sex- and race-matched controls (1.32 ± 0.21 mm vs 1.09 ± 0.14 mm, P = .002). No subject had discrete plaque on CT sufficient to cause luminal narrowing, and plaque was not related to RCA wall thickness. In multivariate regression analyses, smoking pack-years (P = .004) and HIV infection (P = .007) were independently associated with thicker RCA vessel walls. Epicardial fat did not differ between groups. Among the HIV-infected group, duration of antiretroviral therapy (ART) (P = .02), duration of stavudine exposure (P < .01), low-density lipoprotein cholesterol (P = .04), and smoking pack-years (P < .01) were positively correlated with RCA wall thickness.

CONCLUSIONS

This investigation provides evidence of subclinical coronary vascular disease among individuals infected with HIV in early life. Increased duration of ART, hyperlipidemia, and smoking contributed to proximal RCA thickening, independent of atherosclerotic plaque quantified by CT. These modifiable risk factors appear to influence early atherogenesis as measured by coronary wall thickness and may be important targets for CVD risk reduction.

Infectious burden and atherosclerosis: A clinical issue

Atherosclerotic cardiovascular diseases, chronic inflammatory diseases of multifactorial etiology, are the leading cause of death worldwide. In the last decade, more infectious agents, labeled as “infectious burden”, rather than any single pathogen, have been showed to contribute to the development of atherosclerosis through different mechanisms. Some microorganisms, such as Chlamydia pneumoniae (C. pneumoniae), human cytomegalovirus, etc. may act directly on the arterial wall contributing to endothelial dysfunction, foam cell formation, smooth muscle cell proliferation, platelet aggregation as well as cytokine, reactive oxygen specie, growth factor, and cellular adhesion molecule production. Others, such as Helicobacter pylori (H. pylori), influenza virus, etc. may induce a systemic inflammation which in turn may damage the vascular wall (e.g., by cytokines and proteases). Moreover, another indirect mechanism by which some infectious agents (such as H. pylori, C. pneumoniae, periodontal pathogens, etc.) may play a role in the pathogenesis of atherosclerosis is molecular mimicry. Given the complexity of the mechanisms by which each microorganism may contribute to atherosclerosis, defining the interplay of more infectious agents is far more difficult because the pro-atherogenic effect of each pathogen might be amplified. Clearly, continued research and a greater awareness will be helpful to improve our knowledge on the complex interaction between the infectious burden and atherosclerosis.

Making sense of how HIV kills infected CD4 T cells: implications for HIV cure

Defining how HIV does, and does not, kill the host CD4 T cell that it infects is of paramount importance in an era when research is approaching a cure for infection. Three mutually exclusive pathways can lead to the death of HIV-infected cells during the HIV life cycle, before, coincident and after HIV integration and consequently may affect viral replication. We discuss the molecular mechanism underlying these pathways, the evidence supporting their roles in vivo, and contemplate how understanding these pathways might inform novel approaches to promote viral cure of HIV.

Making sense of how HIV kills infected CD4 T cells: implications for HIV cure

Defining how HIV does, and does not, kill the host CD4 T cell that it infects is of paramount importance in an era when research is approaching a cure for infection. Three mutually exclusive pathways can lead to the death of HIV-infected cells during the HIV life cycle, before, coincident and after HIV integration and consequently may affect viral replication. We discuss the molecular mechanism underlying these pathways, the evidence supporting their roles in vivo, and contemplate how understanding these pathways might inform novel approaches to promote viral cure of HIV.