Adipokines and vascular health in treated HIV infection: an obesity paradox?

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.

HIV Protease Inhibitor Ritonavir Impairs Endothelial Function Via Reduction in Adipose Mass and Endothelial Leptin Receptor-Dependent Increases in NADPH Oxidase 1 (Nox1), C-C Chemokine Receptor Type 5 (CCR5), and Inflammation

Background Cardiovascular disease is currently the leading cause of death in patients with human immunodeficiency virus on combination antiretroviral therapy. Although the use of the protease inhibitor ritonavir has been associated with increased prevalence of cardiovascular disease, the underlying mechanisms remain ill-defined. Herein, we tested the hypothesis that ritonavir-mediated lipoatrophy causes endothelial dysfunction via reducing endothelial leptin signaling. Methods and Results Long-term (4 weeks) but not short-term (3 days) treatment with ritonavir reduced body weight, fat mass, and leptin levels and induced endothelial dysfunction in mice. Moreover, ritonavir increased vascular NADPH oxidase 1, aortic H₂O₂ levels as well as interleukin-1β, GATA3 (GATA binding protein 3), the macrophage marker (F4/80), and C-C chemokine receptor type 5 (CCR5) expression. Reactive oxygen species scavenging with tempol restored endothelial function, and both NADPH oxidase 1 and CCR5 deletion in mice protected from ritonavir-mediated endothelial dysfunction and vascular inflammation. Remarkably, leptin infusion markedly improved endothelial function and significantly reduced vascular NADPH oxidase 1, interleukin-1β, GATA3, F4/80, and CCR5 levels in ritonavir-treated animals. Selective deficiency in endothelial leptin receptor abolished the protective effects of leptin infusion on endothelial function. Conversely, selective increases in endothelial leptin signaling with protein tyrosine phosphatase deletion blunted ritonavir-induced endothelial dysfunction. Conclusions All together, these data indicate that ritonavir-associated endothelial dysfunction is a direct consequence of a reduction in adiposity and leptin secretion, which decreases endothelial leptin signaling and leads to a NADPH oxidase 1-induced, CCR5-mediated reduction in NO bioavailability. These latter data also introduce leptin deficiency as an additional contributor to cardiovascular disease and leptin as a negative regulator of CCR5 expression, which may provide beneficial avenues for limiting human immunodeficiency virus infection.

Stroke incidence is highest in women and non-Hispanic blacks living with HIV in the AIDS Clinical Trials Group Longitudinal Linked Randomized Trials cohort

OBJECTIVE

To investigate the incidence of first-ever stroke/transient ischemic attack (TIA) and associated risk factors in a cohort of persons living with HIV infection (PLWH).

DESIGN

Observational cohort study

METHODS

We determined incidence rates of first-ever stroke/TIA in PLWH after ART initiation from the AIDS Clinical Trials Group ALLRT cohort and its parent trials. Poisson regression models evaluated baseline and time-varying covariates as risk factors for stroke/TIA.

RESULTS

The incidence rate of stroke/TIA was 1.69 per 1000 person-years. Incidence rates were highest in women (2.88 stroke/TIAs per 1000 person-years compared with 1.40 per 1000 person-years in men) and non-Hispanic Blacks (2.51 stroke/TIAs per 1000 person-years compared with 0.77 per 1000 person-years in Hispanic/other race/ethnicities and 1.56 per 1000 person-years in whites). In a multivariable model, we found a significant age-by-sex interaction (P = 0.01). The higher risk of stroke/TIA in women was more pronounced at younger ages, whereas older age conferred a greater increase in stroke/TIA risk in men than women. Other risk factors for stroke/TIA included hypertension, higher LDL, and HIV RNA greater than 200 copies/ml. Overweight/obese BMI and higher CD4+:CD8+ ratio protected against stroke/TIA.

CONCLUSION

Women and non-Hispanic Blacks living with HIV had the highest incidence rates of stroke/TIA. A concerted effort must be made to include PLWH from these at-risk groups in observational and interventional studies aimed at understanding stroke mechanisms and reducing stroke risk in HIV infection. Strategies to modify stroke risk in PLWH should employ a multipronged approach targeting vascular risk factors and engaging and retaining patients in HIV care.

Leptin, Adiponectin and Cognition in Middle-aged HIV-infected and Uninfected Women. The Brooklyn Women's Interagency HIV Study

CONTEXT

Case-control study of women with and without HIV infection.

OBJECTIVE

To explore the association of cognition and the adipokines, leptin and adiponectin (total; high molecular weight, HMW), in women with (HIV+) and without HIV (HIV-) infection.

DESIGN

Cross-sectional analyses of adipokines and cognition using linear regression models of log-transformed adipokines, and Trails A, Trails B, Stroop interference time, Stroop word recall, Stroop color naming and reading, and Symbol Digit Modalities Test (SDMT) with consideration for age, HIV infection status, education, CD4 count, diabetes, body mass index (BMI), waist circumference (WC) and race/ethnicity.

SETTING

Brooklyn, NY.

PARTICIPANTS

354 participants (247 HIV+, 107 HIV-), in the Brooklyn Women's Interagency HIV Study (WIHS), average age 38.9 years, with measured levels of leptin and adiponectin (total and high molecular weight, HMW).

MAIN OUTCOME MEASURE

Cognition.

RESULTS

Higher levels of leptin were positively associated with worse cognition on the basis of Trails A completion time and SDMT score. Among at risk HIV- women, leptin was associated with worse performance on Trails B. No associations were observed for total or HMW adiponectin.

CONCLUSION

Blood adipokine levels were measured to provide mechanistic insights regarding the association of adipose with cognitive function. These data suggest that higher levels of leptin, consistent with more adipose tissue, are associated with worse cognitive function in middle age. Monitoring leptin over time and with increasing age in relation to cognition and dementia, may lend insights to the role of adipose tissue in successful body and brain aging among women with HIV infection.