2nd International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV 13-15 September 2000, Toronto, Canada

THE EFFECTS OF A VARIETY OF PROTEASE INHIBITORS ON INSULIN BINDING, INSULIN-MEDIATED SUGAR TRANSPORT AND CELL TOXICITY IN INSULIN TARGET AND NON-TARGET CELL CULTURES

Antiviral Therapy 2000; 5(Suppl. 5):7 (abstract no. O9)

RJ Germinario^1,3, SP Colby-Germinario³, C Cammalleri² and M Wainberg^1,3
1McGill University AIDS Centre; ²Concordia University; and ³Lady Davis Institute for Medical Research, Montreal, Quebec, Canada

The protease inhibitor limb of the HAART therapeutic regimen has been associated with the development of lipodystrophy and insulin resistance in treated AIDS patients. The mechanism(s) involved in these treatment side-effects is currently unknown and is the subject of our studies. In this report, the effects of protease inhibitors (PIs) such as saquinavir, ritonavir, amprenavir and indinavir on basal and insulin (1)-mediated sugar transport, insulin binding and cell toxicity in vitro have been investigated. ³H-2 deoxy glucose (2DG) and ¹²⁵I-insulin were used as probes to monitor sugar transport and specific insulin binding in cell cultures. The effect of the PIs specified above on cell culture viability was determined. Over the range of concentrations studied (0.1-100 µM), significant toxicity was seen from 10-100 µM of drug. In Jurkat cells,only 42±2% of the cells remained viable 2 days post-exposure to 100 µM of saquinavir. In 3T3 L1 fibroblasts, 75-86±8% of the cells remained viable after 2 days exposure to 10 µM ritonavir, saquinavir or amprenavir, while 52-60±3% of cells were viable in the presence of 100 µM ritonavir, saquinavir or amprenavir. Most analyses employed 1 µM of drug as there was concern over toxicity but also this amount of drug represented the C_max of most PIs employed in treatment. Saquinavir at 1 µM increased basal 2DG transport in human fibroblasts, Jurkat cells and L6 myotubes but not in 3T3 L1 adipocytes. Jurkat cells exposed to saquinavir for up to 49 days in culture still exhibited 2DG transport increases. In human fibroblasts and L6 myotubes, the increased 2DG transport on exposure to saquinavir as well as indinavir resulted in a decreased insulin:control transport ratio. In 3T3 L1 adipocytes, no differences were seen in the insulin:control transport ratio on S exposure. Interestingly, saquinavir, indinavir and ritonavir all exhibited modulation of specific-insulin binding over the period of adipocyte induction. At full adipocyte induction (15 days exposure), the saquinavir group had 52±1% of control binding while the indinavir or ritonavir groups exhibited 47±12% and 6±3% of control binding, respectively. It is apparent that several metabolic effects are induced by the PIs. The effects on sugar transport and insulin binding suggest perturbations in the insulin response system. We feel that these data provide some indication of the site(s) that may be affected in vivo.

Supported by a grant from CANFAR and in part by Hoffmann LaRoche Canada.

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