P5340HIV-infected participants on combination ART (tenofovir, emtricitabine, efavirenz) have improved endothelial function and smaller retinal venular calibers compared to treatment naive participants

Background

Cumulative data from several studies suggest that HIV-infected populations have a 2-fold increased cardiovascular risk. Evidence is also pointing to a link between HIV and early vascular changes, including endothelial dysfunction and subclinical atherosclerosis. There is a paucity of data from sub-Saharan Africa (the epicenter of the global HIV burden and a region with a rapidly increasing cardiovascular disease [CVD] incidence); furthermore, the contribution of specific combination ART (c-ART) regimens to HIV-related CVD and early vascular changes remain unclear.

Purpose

To investigate the association between HIV-infection, c-ART (TDF+FTC+EFV), CVD risk and vascular markers of CVD in an adult cohort in South Africa.

Methods

Cross-sectional study, participants assigned to 3 groups: HIV-free (HIV−), HIV-infected ART naïve (HIV+/−) and HIV-infected on ART (HIV+/+). Data collection: demographic information, anthropometrics, CVD risk factors, and blood chemistry. Vascular endpoints assessed: brachial artery flow-mediated dilatation (FMD), carotid intima-media thickness (C-IMT) and retinal microvascular calibers.

Results

Cohort size: n=427 (HIV− n=148; HIV+/− n=69; HIV+/+ n=210), mean age: 39.4 years, 68.9% females. Analysis of cardiovascular risk showed no differences in smoking and alcohol consumption, and blood pressure was unaffected by HIV-status. The untreated HIV group had a high % participants with clinically low HDL-cholesterol levels, whereas c-ART seemed to reduce the prevalence (HIV+/−: 58% vs 31% in HIV− and 26% in HIV+/+; p<0.01). Prevalence of hyper-LDL-cholesterolemia and hypertriglyceridemia were similar. High sensitivity CRP levels were unaffected by HIV-status. Markers of end-organ damage showed renal involvement in the HIV+ groups (median regression of urine albumin-creatinine ratio in HIV+/+ and HIV+/− vs HIV−: Beta±SEM: 0.5±0.3 and 0.8±0.2 in HIV+/+ and HIV+/− respectively, p=0.02; adjusted for age, gender and ethnicity), as well as hepatic injury in the treated group (gamma-GT in HIV+/+ vs HIV−: Beta±SEM: 23.3±4.4, p<0.01, adjustment as above). Multiple regression of vascular markers showed increased FMD in HIV+/+ vs HIV+/− (Beta±SEM: 1.8±0.8, p=0.01; adjusted for age, gender, ethnicity and BMI), and decreased central retinal venular equivalent (CRVE) in HIV+/+ vs HIV+/− (Beta±SEM: −11.9±3.8, p=0.002) and vs HIV− (Beta±SEM: −7.1±3.2, p=0.03), adjustment as above. Carotid IMT was not affected by HIV or treatment status.

Conclusions

Combination ART consisting of TDF+FTC+EFV conferred vascular protection in HIV-infected participants as shown by improved endothelial function (increased FMD) and smaller CRVE compared to ART naïve counterparts. There was no evidence of subclinical atherosclerosis involvement (C-IMT). The vasculoprotective effects in the treated group were supported by a favourable HDL-cholesterol profile, despite unchanged inflammation (hs-CRP), and evidence of renal and hepatic impairment.

Acknowledgement/Funding

Dept of Science and Technology (South Africa); National Research Foundation (South Africa); Belgian Science Policy, Belgium; Austrian Grants Agency.

A histomorphometric study on the effects of antiretroviral therapy (ART) combined with a high-calorie diet (HCD) on aortic perivascular adipose tissue (PVAT)

Perivascular adipose tissue (PVAT), surrounding arteries is metabolically active. Obesity and antiretroviral therapy (ART) may cause pathophysiological conditions in the aortic wall and surrounding PVAT. The aim of the study was to determine the histological effects on the aortic wall, aortic PVAT adipocyte morphology and leptin staining intensity in obese rats treated with ART. Wistar rats (N=36) were divided into four groups; a lean control (C/ART-), ART control (C/ART+), high-calorie diet (HCD) untreated (HCD/ART-) and HCD and ART experimental (HCD/ART+). The aorta and surrounding PVAT were stained with haematoxylin and eosin (H&E) and anti-leptin antibodies for immunohistochemistry (IHC). The C/ART+ group had a thinner tunica media compared to the HCD/ART- group. The tunica adventitia was thicker in the ART groups (C/ART+ and HCD/ART+) compared to the lean control group. White adipocytes in the HCD/ART- group was larger in size compared to the other three groups. The high-calorie diet groups (HCD/ART- and HCD/ART+) had increased adipocyte sizes, for both brown and differentiating adipocytes, compared to the control groups (C/ART- and C/ART+). The unilocular and differentiating adipocytes in the C/ART+ group showed intense leptin staining. Unilocular and differentiating adipocytes in the HCD/ART- and HCD/ART+ groups showed weak to no leptin staining intensity. The present study indicated that ART and a HCD, separately and combined, altered both the tunica media and adventitia of the aortic wall, whereas the HCD alone caused adipocytes to increase in size. The leptin staining intensity suggested that ART alone may lead to increased leptin expression, whereas ART combined with a HCD may cause leptin deficiency. Changes seen with ART in a rat model suggest that aortic wall thickness and PVAT adipocyte morphology alterations should be considered by clinicians in obese individuals receiving ART.