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PROTEIN AND VESICLE TRAFFICKING, CYTOSKELETON

Nucleoside reverse transcriptase inhibitors prevent HIV protease inhibitor-induced atherosclerosis by ubiquitination and degradation of protein kinase C

Departments of ¹Physiology, ²Pediatrics, ³Medicine, and ⁴Anatomy and Neurobiology, University of Kentucky, Lexington; and ⁵Lexington Veterans Affairs Medical Center, Lexington, Kentucky

Submitted 27 April 2006 ; accepted in final form 29 June 2006

HIV protease inhibitors are important pharmacological agents used in the treatment of HIV-infected patients. One of the major disadvantages of HIV protease inhibitors is that they increase several cardiovascular risk factors, including the expression of CD36 in macrophages. The expression of CD36 in macrophages promotes the accumulation of cholesterol, the development of foam cells, and ultimately atherosclerosis. Recent studies have suggested that -tocopherol can prevent HIV protease inhibitor-induced increases in macrophage CD36 levels. Because of the potential clinical utility of using -tocopherol to limit some of the side effects of HIV protease inhibitors, we tested the ability of -tocopherol to prevent ritonavir, a common HIV protease inhibitor, from inducing atherosclerosis in the LDL receptor (LDLR) null mouse model. Surprisingly, -tocopherol did not prevent ritonavir-induced atherosclerosis. However, cotreatment with the nucleoside reverse transcriptase inhibitors (NRTIs), didanosine or D4T, did prevent ritonavir-induced atherosclerosis. Using macrophages isolated from LDLR null mice, we demonstrated that the NRTIs prevented the upregulation of CD36 and cholesterol accumulation in macrophages. Treatment of LDLR null mice with NRTIs promoted the ubiquitination and downregulation of protein kinase C (PKC). Previous studies demonstrated that HIV protease inhibitor activation of PKC was necessary for the upregulation of CD36. Importantly, the in vivo inhibition of PKC with chelerythrine prevented ritonavir-induced upregulation of CD36, accumulation of cholesterol, and the formation of atherosclerotic lesions. These novel mechanistic studies suggest that NRTIs may provide protection from one of the negative side effects associated with HIV protease inhibitors, namely the increase in CD36 levels and subsequent cholesterol accumulation and atherogenesis.

CD36; macrophage; proteasome; low-density lipoprotein receptor

This article has been cited by other articles:

				M. P. Dube, S. E. Lipshultz, C. J. Fichtenbaum, R. Greenberg, A. D. Schecter, S. D. Fisher, and for Working Group 3 Effects of HIV Infection and Antiretroviral Therapy on the Heart and Vasculature Circulation, July 8, 2008; 118(2): e36 - e40. [Full Text] [PDF]