Background:   Lopinavir (LPV), amprenavir (APV, active moiety of FosAmprenavir), and atazanavir (ATV) are protease inhibitors (PI) currently used in HIV-1 ART alone or through pharmaco-enhancement by ritonavir (RTV). LPV and RTV are known to negatively influence lipid profile in patients and healthy subjects. We previously described our method of assessment of adipose functions using the 3T3-F442A cell line and its relevance to the clinic. We now compare the effects of LPV, APV, or ATV on adipose cell functions using multiple endpoints.

Methods:  The murine adipose cell line 3T3-F442A was cultured and differentiated with fetal calf serum and insulin. The drugs were tested at therapeutic concentrations (near C_max value:  LPV, APV: 10 µM, ATV : 4 µM) in the presence or absence of RTV (2 µM). Cells were treated all along the differentiation program from day 6 before to day 7 after induction of differentiation. Adipocyte differentiation was evaluated at day 7 by protein expression of the transcription factors SREBP-1, PPAR-γ and C/EBP-α. Cell response to insulin was evaluated by tyrosine phosphorylation of the insulin receptor (IR) ß-subunit, and insulin activation of ERK1/2 and Akt/PKB. Lipid metabolism was evaluated by assessment of lipid accumulation and insulin-induced lipogenesis. Drug toxicity was tested by MTT lysis and apoptosis by flow cytometry.

Results:  APV, LPV, or ATV did not alter adipocyte differentiation based on the protein expression of adipogenic markers SREBP-1, PPAR-γ and C/EBP-α. These adipogenic markers were normally expressed when the APV-, ATV-, or LPV-treated adipocytes were co-treated with RTV. APV, ATV, and LPV, used alone or together with RTV, did not alter insulin action on IR ß-subunit phosphorylation, ERK1/2 and Akt/PKB, and did not decrease MTT lysis or induce apoptosis. APV (10 µM), ATV (4 µM), and RTV (2 µM) had no effect on lipid accumulation and insulin-induced lipogenesis. LPV used alone or in association with RTV partly decreased these functions (25 and 40%, respectively). In association with RTV, ATV decreased lipid accumulation (35%). APV had no effect on lipid metabolism whether or not associated with RTV.

Conclusions:  Therapeutic concentration of ATV or of APV ± RTV did not alter adipose cell differentiation, survival, and response to insulin. LPV alone or associated with RTV, and ATV associated with RTV partly decreased lipid accumulation.

Keywords: lipodystrophy; HIV protease inhibitor; adipocytes