The effects of HIV-1-proteins and antiretroviral therapy on aortic endothelial cells (AECs). A mechanistic in vitro approach

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Research Foundation Introduction Endothelial dysfunction (ED) is an early precursor of cardiovascular disease characterized by decreased nitric oxide (NO) and increased oxidative stress, creating a pro-inflammatory environment. Increased ED and cardiovascular risk have been observed in HIV-1 infection and antiretroviral therapy (ART). Purpose The United Nations AIDS update indicates that in 2015 17.0 million people worldwide were living with HIV and receiving antiretroviral therapy. Considering the extent of this global pandemic and its comorbidity with CVD, zooming in on HIV’s intersection with antiretroviral therapy and cardiovascular health is of paramount importance. Yet, many of the mechanisms involved are still poorly understood. This knowledge can ultimately assist with the careful selection of antiretroviral-agents in patients with underlying cardiovascular risk factors. Objectives Establishing a simulated model of in vitro HIV-1-infection in aortic endothelial cells and determining the effects of non/nucleoside reverse transcriptase inhibitors (NRTI/NNRTIs) and protease inhibitors (PIs) on markers of endothelial function and the expression/activation of vascular signalling proteins. Methods A simulated HIV-1-model was established by adding recombinant HIV-1 proteins to growth medium in a single cocktail containing Tat, Gp160 and Nef. ART1 (NRTI/NNRTIs) were administered as a single cocktail to growth medium, containing efavirenz (EFV), emtricitabine (FTC) and tenofovir (TDF). ART2 (PIs) were administered as a single cocktail to growth medium, containing lopinavir (LPV) and ritonavir (RTV). All the aforementioned treatments were subject to dose-response investigations and treatment lasted 24 hours. Cell viability, NO-production and oxidative stress were measured using fluorescent probes. Selected dosages from above studies were further used and important vascular signalling proteins in HIV-1 exposed AECs were investigated by western blotting. Results HIV-1 (100ng/ml, 24h) resulted in ↓NO-levels (DAF-fluorescence intensity: 100±1.25% vs. 76.00±3.67%; p<0.05) with no oxidative stress. HIV-1+PI treatment lowered NO levels (DAF-fluorescence: 100±0.72% vs. 94.47±1.91%; p<0.05). HIV-1+ NRTI/NNRTI treatment had no effects. HIV-1+PI treatment ↓IκBα expression (inhibitory signalling protein in pro-inflammatory NF-κB pathway) (1.0 ± 0.15 vs 0.37 ± 0.03; p<0.05) and ↓eNOS expression (1.0 ± 0.21 vs. 0.28 ± 0.04; p<0.05). The same was observed for PKB/Akt (1.0 ± 0.03 vs. 0.68 ± 0.02; p<0.05). No effects on cell viability and oxidative stress were observed. Conclusion Exposure of AECs to combined HIV-1-protein and PI treatment lowered NO-production, which may be linked to underlying PKB/Akt and eNOS downregulation. HIV-1+PI treatment was associated with increased pro-inflammatory NF-κB signalling. Overall, our results suggest that a dysfunctional state was induced in AECs exposed to HIV-1 proteins and PI treatment.