HIV-Nef Protein Transfer to Endothelial Cells Requires Rac1 Activation and Leads to Endothelial Dysfunction Implications for Statin Treatment in HIV Patients

Abstract

Rationale: Even in antiretroviral therapy-treated patients, HIV continues to play a pathogenic role in cardiovascular diseases. A possible cofactor may be persistence of the early HIV response gene Nef, which we have demonstrated recently to persist in the lungs of HIV+ patients on antiretroviral therapy. Previously, we have reported that HIV strains with Nef, but not Nef-deleted HIV strains, cause endothelial proinflammatory activation and apoptosis. Objective: To characterize mechanisms through which HIV-Nef leads to the development of cardiovascular diseases using ex vivo tissue culture approaches as well as interventional experiments in transgenic murine models. Methods and Results: Extracellular vesicles derived from both peripheral blood mononuclear cells and plasma from HIV+ patient blood samples induced human coronary artery endothelial cells dysfunction. Plasma-derived extracellular vesicles from antiretroviral therapy+ patients who were HIV-Nef+ induced significantly greater endothelial apoptosis compared with HIV-Nef-plasma extracellular vesicles. Both HIV-Nef expressing T cells and HIV-Nef-induced extracellular vesicles increased transfer of cytosol and Nef protein to endothelial monolayers in a Rac1-dependent manner, consequently leading to endothelial adhesion protein upregulation and apoptosis. HIV-Nef induced Rac1 activation also led to dsDNA breaks in endothelial colony forming cells, thereby resulting in endothelial colony forming cell premature senescence and endothelial nitric oxide synthase downregulation. These Rac1-dependent activities were characterized by NOX2-mediated reactive oxygen species production. Statin treatment equally inhibited Rac1 inhibition in preventing or reversing all HIV-Nef-induction abnormalities assessed. This was likely because of the ability of statins to block Rac1 prenylation as geranylgeranyl transferase inhibitors were effective in inhibiting HIV-Nef-induced reactive oxygen species formation. Finally, transgenic expression of HIV-Nef in endothelial cells in a murine model impaired endothelium-mediated aortic ring dilation, which was then reversed by 3-week treatment with 5 mg/kg atorvastatin. Conclusions: These studies establish a mechanism by which HIV-Nef persistence despite antiretroviral therapy could contribute to ongoing HIV-related vascular dysfunction, which may then be ameliorated by statin treatment.

Oncogenic Effects of HIV-1 Proteins, Mechanisms Behind

“…It also leads to decreased tolerance of the cells to hydrogen peroxide, specifically in astrocytes which normally support neuronal function and protects them against cytotoxic substances including ROS [ 161 ]. Rac1-dependent NOX2-mediated reactive oxygen species production was shown to contribute to ongoing HIV-1-related vascular dysfunction [ 162 ].…”

“…Secreted in exosomes, Nef triggers apoptosis in bystander cells. Extracellular Nef has deleterious effects on CD4+ T cells [ 188 , 190 ]; on bystander B cells by suppressing immunoglobulin class switching [ 191 ]; and on astrocytes [ 192 ] and endothelial cells [ 162 ].…”

RAC1 Involves in the Radioresistance by Mediating Epithelial-Mesenchymal Transition in Lung Cancer

“…The RAC1 signaling pathway is required for transformation mediated by the Ras oncogene (41). The RAC1 pathway promotes transformation, protects against apoptosis, and promotes motility and invasion (42)(43)(44). It has been reported that Rac1 is the target molecule of the PI3K/AKT pathway.…”

Viral Bad News Sent by EVAIL

“…Studies have suggested EVs mediated cardiovascular dysfunction in transferring its protein and non-coding RNA cargo to vascular endothelial and smooth muscle cells [ 43 , 45 ]. Several reports have demonstrated that the HIV-encoded Nef protein organizes EV formation and uses them as vehicles for dissemination [ 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. These Nef-containing EVs are toxic to surrounding cells, including bystander CD4 positive T cells and vascular endothelial cells that absorb them and become apoptotic [ 46 , 47 , 48 , 52 ].…”