Human immunodeficiency virus impairs reverse cholesterol transport from macrophages

Area of Science:

• Immunology
• Virology
• Cardiovascular Science

Background:

• HIV-1 replication relies on cholesterol.
• HIV infection alters lipid metabolism, increasing coronary artery disease risk.
• Cellular cholesterol metabolism effects in HIV remain unclear.

Purpose of the Study:

• Investigate HIV-1's impact on cellular cholesterol metabolism in macrophages.
• Determine the role of HIV-1 Nef protein in cholesterol dysregulation.
• Elucidate mechanisms linking HIV infection, cholesterol metabolism, and atherosclerosis.

Main Methods:

• Assessed ATP-binding cassette transporter A1 (ABCA1)-dependent cholesterol efflux in HIV-1-infected human macrophages.
• Utilized Nef-transfected murine macrophages to study Nef's direct effects.
• Analyzed ABCA1 expression, localization, and apolipoprotein A-I interaction.
• Examined lipid accumulation in macrophages and presence of HIV-positive foam cells in patient plaques.

Main Results:

• HIV-1 infection and Nef protein significantly impaired ABCA1-dependent cholesterol efflux.
• Nef mediated ABCA1 down-regulation and altered its plasma membrane localization.
• HIV-infected and Nef-transfected macrophages accumulated lipids, resembling atherogenic foam cells.
• Reduced cholesterol efflux decreased HIV infectivity and virion cholesterol content.

Conclusions:

• HIV-1 infection dysregulates macrophage cholesterol metabolism via the Nef protein.
• Impaired cholesterol efflux contributes to HIV infectivity and atherogenesis in HIV patients.
• Nef and ABCA1 are critical in HIV-associated lipid metabolism disturbances and atherosclerosis risk.