Cell death plays a pivotal role in the body to maintain homeostasis during aging. Studies have shown that damaged cells, which must be removed from the body, accumulate during aging. Decay of the capacity and/or control of cell death during aging is widely considered to be involved in some age-dependent diseases. We investigated the accumulation of
protein carbonyls and the role of cell death induced by
hydrogen peroxide in human fibroblasts from individuals of various ages (17-80 years). The results showed that levels of oxidatively modified
proteins increased with age, not only in whole-cell lysates but also in mitochondrial fractions, and this change correlates with a decline in the intracellular
ATP level. Exposure of fibroblasts to
hydrogen peroxide led to cell death by apoptosis and
necrosis. Younger (<60 years old) cells were more resistant to
necrosis induced by
hydrogen peroxide than were older cells (>60 years old), which contained lower levels of free
ATP than did younger cells. Treatment of cells of all ages with inhibitors of
ATP synthesis (
oligomycin,
2,4-dinitrophenol, or
2-deoxyglucose) made them more susceptible to cell death but also led to a switch in the death mode from apoptosis to
necrosis. Furthermore,
hydrogen peroxide treatment led to a greater accumulation of several inflammatory
cytokines (IL-6, IL-7, IL-16, and IL-17) and increased
necrosis in older cells. These results suggest that age-related decline in the
ATP level reduces the capacity to induce apoptosis and promotes necrotic
inflammation. This switch may trigger a number of age-dependent disorders.