690-T. Step-by-Step Evaluation of the Impact of Different Protease Inhibitors on Adipogenesis: Pathophysiological Insights and Relevance to the Clinic

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Session 90 Poster Session
Incidence, Prevalence, and Pathogenic Correlates of Insulin Resistance and Lipodystrophy Syndrome
Session Time: 4:30-6:30 pm
Room 4E-F

690-T.

Step-by-Step Evaluation of the Impact of Different Protease Inhibitors on Adipogenesis: Pathophysiological Insights and Relevance to the Clinic
M. Caron*, M. Auclair, M. Kornprobst, and J. Capeau
INSERM U.402, Faculté de Med., Saint-Antoine, Paris, France

Background: Protease inhibitors (PI) have been associated with the HIV-associated lipodystrophy syndrome. Using the 3T3-F442A murine adipocyte cell-line we have demonstrated their impact on cell differentiation and induction of insulin resistance. We wanted to demonstrate the differences between Pis commonly prescribed in clinical practice on each step of adipogenesis and the impact of rosiglitazone, a PPARg agonist, providing a rationale for treatment. The clinical relevance of these experiments is discussed.
Methods : Adipose cell differentiation was evaluated by adipocyte counting and by the protein expression of the transcription factors SREBP-1, PPARg, and C/EBPa. Insulin sensitivity was measured by the activation of MAP and Akt/PKB kinases. Cell survival was evaluated by flow cytometry and proteolysis of the caspase death substrate PARP. The distribution of SREBP-1 and of the nuclear protein lamin A/C was studied by confocal microscopy.
Results: The impact of chronic exposure to clinically relevant concentrations (15 µM) of indinavir (IDV), nelfinavir (NFV), and amprenavir (APV) was assessed step-by-step in the model. Initial clonal expansion was not modified, adipocyte conversion was affected by IDV (50-60% inhibition) > NFV (20-30 %), but not APV (5%). Impaired nuclear entry of SREBP-1, nuclear membrane dysorganization, nuclear budding and altered lamin A/C distribution were demonstrated in rank order for IDV>NFV, but not APV. IDV and NFV exerted proapoptotic effects increasing the number of cells with subG1 DNA content by 10.8 and 4.5 fold, respectively. IDV >NFV >> APV blunted insulin activation of MAPK with half-maximally effective concentration of 16, 25 and >100 µM, respectively, and Akt/PKB kinases.
Conclusions: It is increasingly recognized that HIV-associated lipodystrophy is multifactorial. We have compared 3 major PIs in a clinically relevant model demonstrating significant differences of impact on adipose conversion, insulin sensitivity, and apoptosis. We demonstrate the key pathophysiological role of SREBP-1. Rosiglitazone prevents some of the deleterious effects observed in vitro providing a rationale for clinical trials in the treatment of HIV-related lipodystrophic patients.