HIV‐Associated Hypertension is TNFα‐Dependent and Involves Increased Vascular Nox1 Expression in Mice

Abstract

HIV is a major global public health issue which has claimed more than 37 million lives so far. While combination antiretroviral therapies (cART) have significantly increased life expectancy, 35% of all treated HIV patients are diagnosed with hypertension. While cART treatment suppresses viral replication and further progression of the disease to AIDS, viral proteins are still present at low concentrations leading to the present clinical question of whether hypertension is the result of these viral proteins, cART regimen, or a combination of the two. We hypothesize that HIV-associated hypertension involves inflammatory response to viral proteins as well as increases in TNFα production and vascular NADPH Oxidase (Nox) 1 expression. To test this hypothesis, we utilized a transgenic mouse model (Tg26) which ubiquitously expresses seven of the nine viral proteins under the viral long terminal repeat promoter. Using quantitative RT-PCR analysis, high viral mRNA concentrations were found in lymphoid organs including the spleen, intraperitoneal immune cells, and lymph nodes but absent in the vasculature, therefore providing a mouse model mimicking clinical human pathology. Blood Pressure measurements using radio telemetry revealed that viral infection elevated mean arterial pressure in both male (WT=112.3+/-1.3 vs. Tg26=121.9+/-4.0) and female (WT=110.6+/-3.01 vs. Tg26=120.3+/-6.0mmHg) mice. Viral infection also increased systolic and diastolic blood pressure and heart rate with conserved diurnal variation. Measurement of aortic reactivity using wire myography revealed impaired endothelial relaxation (male: p<0.05/female p<0.05) to acetylcholine but intact vascular response to sodium Nitroprusside (SNP) and conserved vascular constriction to KCl and phenylephrine. Remarkably, transplant of bone marrow (BM) from Tg26 mice into WT impaired endothelial function (p<0.05) while transplant of BM from WT to Tg26 mice restored endothelial function. A multiplex cytokine panel found elevated levels of the pro-inflammatory cytokine TNFα in the plasma (p<0.05) and RT-qPCR analysis of the aorta (p<0.05) and intraperitoneal immune cells (p<0.05) also yielded increased TNFα levels. Treatment with the sTNFα inhibitor, etanercept, lowered MAP and restored endothelial function in male mice. Quantification of aortic Noxes (1,2, and 4) revealed increases in Nox1 expression (p<0.05). remarkably, selective inhibition of Nox1 via GKT771 restored endothelial dependent relaxation in both Tg26 and Tg26àWT transplanted mice. Analysis of multiple immune cell markers in the aorta via RT-qPCR found increased mRNA levels of the T-cell marker GATA3 (p<0.05). Taken together, these results support the hypothesis that HIV associated hypertension at levels of low viremia and independent of cART involves bone-derived immune cells, is TNFα dependent and involves increased vascular Nox1 expression.