Polymorphisms in HIV-1 nef are associated with plasma concentration of biomarkers of endothelial activation

Abstract

Infection with HIV is associated with an increased risk of cardiovascular disease (CVD), which may be mediated by the effect of the viral proteins, Nef and Tat, on inflammation and endothelial activation. The viral genes coding for Nef and Tat contain numerous polymorphisms, which we hypothesised may be differentially associated with endothelial activation. Therefore, our aim was to assess the association of these polymorphisms with endothelial activation and inflammation in subjects infected with HIV-1. The HIV-1 nef and tat genes were sequenced from clinical isolates from 31 and 34 patients, respectively. Plasma concentration of biomarkers of endothelial activation (intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), endothelial leukocyte adhesion molecule-1 (E-selectin), monocyte chemoattractant protein-1 (MCP-1) and von Willebrand factor (vWF)), and biomarkers of inflammation (tumor necrosis factor- (TNF-), interleukin-6 (IL-6) and interleukin-8 (IL-8)), were measured. Analysis of HIV-1 nef gene sequences identified five polymorphisms (V16I, H40Y, T50A,H, S169N and H188Q,S) that were each significantly (p<0.05) associated with ICAM-1 plasma concentration. An additive effect of these variants on plasma ICAM-1 concentration (p=0.004 for trend), was observed. No significant associations were seen between Tat amino acid residues and plasma concentration of markers of endothelial activation and inflammation. These are the first human in vivo data that support the hypothesis that nef gene polymorphisms impact endothelial function. ImportanceCardiovascular disease (CVD) is a leading cause of mortality in adults living with HIV, which may in part be due to endothelial activation and inflammation caused by the viral proteins, Nef and Tat. However, there is no data from humans supporting the CVD-associated Nef and Tat hypothesis, and assays for accurately measuring Nef and Tat plasma concentrations are not currently available. Therefore, we hypothesized that polymorphisms in the nef and tat genes of clinical viral isolates may be associated with host plasma markers of endothelial activation and inflammation. Our results show that this was the case, with five nef polymorphisms showing both individual and additive association with plasma concentration of ICAM-1. The HIV-1 Tat gene, however, showed no significant association with plasma concentrations of markers of endothelial activation and inflammation. This is the first human study to directly link Nef to endothelial activation and to provide a possible screening tool i.e., nef genotyping, for identifying individuals at high risk of endothelial-based diseases.