Ritonavir increases CD36, ABCA1 and CYP27 expression in THP-1 macrophages.
Ritonavir, a protease inhibitor used in combination antiretroviral therapy for HIV-1 infection, is associated with an increased risk of premature atherosclerosis. The aim of the present study was to assess the effects of ritonavir, in the absence of added lipoproteins, on the expression of genes that control cholesterol trafficking in human monocytes/macrophages.


METHODS
THP-1 cells were used to study the effects of ritonavir on the expression of CD36, ATP binding cassette transporters A1 (ABCA1) and G1 (ABCG1), scavenger receptor B class I (SR-BI), caveolin-1 and sterol 27-hydroxylase (CYP27). Exposure to ritonavir (2.5 mug/ml) increased CD36 protein (28%, P < 0.05) and mRNA (38%, P < 0.05) in differentiated THP-1 macrophages, but not in undifferentiated monocytes. This effect was not related to the increase in PPARgamma expression (51%, P < 0.05) caused by ritonavir. Ritonavir also reduced SR-BI protein levels (46%, P < 0.05) and increased CYP27 (43%, P < 0.05) and ABCA1 (49%, P < 0.05) mRNA expression. Liver X receptor alpha (LXRalpha) mRNA, protein and binding activity were also increased by ritonavir treatment.


CONCLUSIONS
We propose that ritonavir induces ABCA1 expression in THP-1 macrophages through LXRalpha. The increase in ABCA1 and other cholesterol efflux mediators, such as CYP27, may compensate CD36 induction. Therefore, we suggest that the net effect of ritonavir on macrophages in the absence of lipoproteins is not clearly proatherogenic.
Pharmacology Department, Faculty of Pharmacy and Biomedicine Institute (IBUB), University of Barcelona, and Ciber Diabetes y Enfermedades Metabólicas asociadas (CIBERDEM), Instituto de Salud Carlos III, Spain.
Jordi
J
Pou
Alba
A
Rebollo
Núria
N
Roglans
Rosa M
RM
Sánchez
Manuel
M
Vázquez-Carrera
Juan C
JC
Laguna
Juan
J
Pedro-Botet
Marta
M
Alegret
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D018955:CD36 Antigens / Q000378:metabolism*; D002460:Cell Line; D053493:Cholestanetriol 26-Monooxygenase / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D006801:Humans; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D019438:Ritonavir / Q000494:pharmacology*
C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D018955:CD36 Antigens; D017320:HIV Protease Inhibitors; D012333:RNA, Messenger; C506831:CYP27A1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; D019438:Ritonavir