RESUMEN
OBJECTIVE: We tested the hypothesis that lycopene supplementation reduces the expression of oxidant-responsive heme oxygenase-1 (HO-1) in basal conditions and in response to an oxidant challenge and determined whether this is temporally associated with increased cell viability. METHODS: We determined basal and stimulated ex vivo expression of HO-1 and cell viability in lymphocytes from volunteers after lycopene supplementation. Twenty-four healthy young men on a low lycopene diet consumed 1) 170 g of passata sauce with butter or 2) butter alone for 3 wk in a randomized crossover design. RESULTS: Plasma lycopene concentrations at the end of the tomato and control trials were 0.54 +/- 0.20 versus 0.20 +/- 0.15 micromol/L, respectively (P < 0.05). There was a significant increase in the proportion of live cells (91 +/- 5% versus 87 +/- 9%) and a corresponding reduction in apoptosis (6 +/- 4% versus 11 +/- 9%) in untreated lymphocytes after supplementation (P < 0.05), with no effect on cell viability in response to hydrogen peroxide treatment. HO-1 protein expression in basal conditions and induction of HO-1 after hydrogen peroxide treatment was not different between trials. CONCLUSION: Lycopene supplementation did not affect basal oxidative stress or susceptibility to oxidant-induced stress as indicated by the expression of the oxidant-responsive protein HO-1 and cell viability in response to hydrogen peroxide treatment. However, lycopene supplementation significantly reduced apoptosis in freshly harvested untreated lymphocytes. We conclude that this was not through an oxidant-mediated mechanism because of the lack of an effect on oxidant-responsive HO-1.