Endothelial Dysfunction, Arterial Stiffening, and Intima-Media Thickening in Large Arteries from HIV-1 Transgenic Mice

Abstract

HIV patients on highly active antiretroviral therapy (HAART) exhibit elevated incidence of cardiovascular disease, including a higher risk of myocardial infarction and prevalence of atherosclerotic lesions, as well as increases in markers of subclinical atherosclerosis including increased carotid artery intima-media thickness, increased arterial stiffness, and impaired flow-mediated dilation. Both HAART and HIV-infection are independent risk factors for atherosclerosis and myocardial infarction. Studies implicate the HIV proteins tat, gp120, vpu, and nef in early on-set atherosclerosis. The objective of this study was to quantify the role of expression of HIV-1 proteins on the vascular function, biomechanics, and geometry of common carotid arteries and aortas. This study employed NL4-3Δ gag/pol transgenic mice (HIV-Tg), which contain the genetic sequence for the HIV-1 proteins env, tat, nef, rev, vif, vpr, and vpu but lacks the gag and pol genes and reports that HIV-Tg mice have impaired aortic endothelial function, increased carotid intima-media thickness (c-IMT), and increased arterial stiffness. Further, HIV-Tg arteries show decreased elastin content, increased cathepsin K and cathepsin S activity, and increased mechanical residual stress. Thus, mice that express HIV proteins exhibit pre-clinical markers of atherosclerosis and these markers correlate with changes in markers of vascular remodeling. These findings are consistent with the hypothesis that HIV-proteins, independent of HAART treatment or HIV infection, could play a role in of the development of cardiovascular disease.

Azidothymidine (AZT) leads to arterial stiffening and intima-media thickening in mice

“…Male mice were used to minimize any variability due to the estrus cycle in females, and the age, strain, and dosage were chosen to match previous studies (Sutliff et al, 2002; Hansen et al, 2012). Non-invasive blood pressure monitoring was performed at 0, 17, and 35 days after initiation of treatment via a tail cuff system (Columbus Instruments).…”

“…Cylindrical biaxial biomechanical tests of the arteries were performed as previously described (Hansen et al, 2012). Excised common carotid arteries (3–5 mm long) and suprarenal aortas (4–5 mm long) were maintained in culture medium [Dulbecco’s modified Eagles medium (Invitrogen, Inc.) containing 4.5 g/L glucose and sodium pyruvate and without L-glutamine and phenol red] in an incubator at 37 °C.…”

“…Following testing or microscopy imaging (described below), ring sectors were cut from the arteries to obtain their stress free configuration following previous methods (Hansen et al, 2012). A 14% gelatin mixture was injected into the vessel and allowed to solidify, then the artery was cut into a series of segments and placed in phosphate buffered saline (PBS) (Wagenseil et al, 2005).…”

“…The vessel wall thickness was quantified by two methods (confocal microscopy and histology), following previously described methods (Hansen et al, 2012). …”

“…The Fastin assay (Biocolor) and Sirius red assay were used to quantify the elastin and collagen content of the dried arteries, following manufacturer instruction and as previously described (Hansen et al, 2012). Pairs of carotid arteries from a single mouse or a single suprarenal aorta were dried in a vacuum oven at 37 °C for 2 days.…”