Objectives: Side effects of antiretroviral treatment such as lipoatrophy have been mainly attributed to mitochondrial toxicity of nucleoside reverse transcriptase inhibitors (NRTIs). We assessed whether uridine can abrogate the adverse effects of NRTIs on adipocyte functions.
Methods: 3T3-F442A preadipocytes were exposed to stavudine (d4T; 10 microM), zidovudine (ZDV; 1 microM), zalcitabine (ddC; 0.2 microM) or didanosine (ddl; 10 microM) in the absence or presence of uridine 21 days prior to and 7 days after induction of differentiation. Then, lipid accumulation (oil red staining), apoptosis (flow cytometry, PARP-cleavage), mitochondrial mass (Mitotracker) and DNA (mtDNA), cytochrome c oxidase (COX) subunits and mitochondrial membrane potential (JC-1) were quantified.
Results: Whereas ddl had no effects, d4T, ZDV and ddC significantly decreased cellular lipid accumulation (by 32%, 46% and 24%, respectively), increased apoptosis and induced mitochondrial depolarization. d4T, ZDV and ddC decreased adipocyte mtDNA (by 64%, 53% and 46%, respectively) and reduced the mtDNA encoded COX II subunit. Uridine (200 microM) had no intrinsic effect, but prevented all adverse effects of d4T, ZDV and ddC on adipocyte morphology, lipid staining, apoptosis, mtDNA depletion (partial prevention with ZDV), mitochondrial mass and membrane potential. The effects of uridine were concentration-dependent. Uridine also fully reverted established d4T toxicities despite continued d4T exposure.
Conclusions: Uridine supplementation protects adipocytes from the adverse effects of d4T, ZDV and ddC on lipid accumulation, cell survival and mitochondrial functions, suggesting that the toxic effects could be linked to intracellular depletion of uridine or its metabolites. Uridine is an interesting candidate in the prevention of NRTI-induced lipoatrophy in vivo.