Hormetic action of mild heat stress decreases the inducibility of protein oxidation and glycoxidation in human fibroblasts.

Repeated mild heat shock (RMHS) has anti-aging effects on growth and various other cellular and biochemical characteristics of human skin fibroblasts undergoing aging in vitro. In this study, we have tested whether RMHS can reduce the accumulation of heavily damaged proteins, such as oxidized and glycoxidized proteins involved in the development of many pathological consequences of aging. Cultured human skin fibroblasts were subjected to RMHS and were subsequently incubated either with glyoxal (0.1-1 mM) generating Nepsilon-carboxymethyl-lysine (CML), or with tert-butyl-hydroperoxide (t-BHP 10-700 microM) producing oxidized proteins. About 50% more carbonylated-proteins were produced in control cells treated with t-BHP than in cells previously exposed to RMHS. More dramatically, a treatment with 0.1 mM glyoxal for 48 h generated CML only in control cells. Such modulation of the level of damaged proteins is most likely related to the beneficial effects of hormesis resulting from exposure to mild stress.