BackgroundThe molecular basis of lipodystrophy, a syndrome associated with HIV antiretroviral (ARV) therapy, remains unknown.ObjectivesTo examine whether ARV therapy might inhibit the expression of CD36, which is known to play an important role in fatty acid and glucose metabolism, and if this might contribute to the metabolic alterations associated with lipodystrophy.DesignThe effects of ARV therapy on CD36 levels was examinedin vivoin a prospective cohort of individuals treated with ARV therapy andin vitroin assays of human cell lines exposed to ARV drugs.MethodsMonocyte CD36 levels were assessed by flow cytometry at baseline and after 7 days of therapy in five healthy volunteers and 10 treatment-naive HIV-1-infected individuals. ARV therapy included protease inhibitors (ritonavir, nelfinavir or lopinavir/ritonavir). In addition, human cell lines (THP-1 and C32) were assessed for CD36 levels pre and post-ritonavir treatment.ResultsThree of four healthy controls (one withdrew because of adverse effects) and 6 of 10 HIV-1-infected individuals had a 50 to > 90% decrease in monocyte CD36 levels after 7 days of therapy. One of ten HIV-infected subjects had a 30% decrease, and the remaining individuals had no change or an increase in CD36 levels. CD36 levels decreased significantly in human cell lines treated with ritonavir but not in those treated with zidovudine.ConclusionsARV therapy resulted in a marked decrease in CD36 in approximately 70% of our participants. Sustained ARV therapy-induced CD36 deficiency may contribute to insulin resistance and other metabolic complications of lipodystrophy.