Effects of HIV gp120 on endothelium-dependent relaxation and eNOS expression

Abstract

Introduction: Clinical studies indicate that HIV infection is associated with high incidence of cardiovascular disease. However, the mechanisms are unknown. The objective of this study was to investigate the effects of HIV gp120 on vasomotor function of porcine coronary arteries and eNOS expression. Methods: Coronary arteries were isolated from fresh porcine hearts and cut into rings, which were studied in 7 groups (TNF-α, gp120, TNF-α plus gp120, TNF-α plus gp120 and anti-gp120 antibody, TNF-α plus gp120 and anti-ICAM-1 antibody, or negative control). Vasomotor function was analyzed with myograph tension system in response to vasoreactive drugs (U46619, bradykinin or sodium nitroprusside). eNOS and ICAM-1 mRNA and eNOS protein levels were determined using RT-PCR and western blot or immunochemistry, respectively. Human coronary artery endothelial cells (HCAECs) were also included for eNOS and ICAM-1 expression. Results: Porcine coronary artery rings treated with TNF-α alone for 8 hrs or gp120 alone for 16 hrs did not show any changes of vasomotor function. However, the rings treated with TNF-α plus gp120 showed a 34.18% reduction of endothelium-dependent vasorelaxation in response to bradykinin as compared to controls (P < 0.05). Anti-gp120 or anti-ICAM-1 antibody blocked this effect of TNF-α and gp120 treated vessels. The vessel contractivity (U46619) or endothelium-independent vasorelaxation did not show changes in all treated vessels. Only TNF-α plus gp120 group significantly reduced eNOS/GAPDH mRNA ratios by 28.86% as compared to controls (P < 0.05). eNOS protein levels were also substantially decreased in this group. ICAM-1 immunoreactivity was increased in all TNF-α treated vessels. Furthermore, HCAECs showed consistent data with pig vessels in response these treatments. Conclusions: These data demonstrate that HIV gp120 reduces endothelium-dependent vasorelaxation and eNOS expression in both porcine coronary arteries and HCAECs pre-treated with TNF-α; and blocking of ICAM-1 or gp120 reverses these effects. This study suggests that ICAM-1 may be an important mediator of gp120 induced endothelial cell injury.