SKIN IMMMUNOSENESCENCE: THE CRITICAL INVOLVEMENT OF HORMONAL BALANCE AFFECTING SIGNAL TRANSDUCTION
E. Corsini, E. Buoso, E. Donetti, M. Racchi
J Aging Res Clin Practice 2012;1(1):17-22
Objectives of review: This manuscript aims to review the state of the art on skin aging with particular attention on skin immunosenescence, hormonal changes and signal transduction. Recent findings: Skin immunosenescence accounts, in the elderly, for increased susceptibility to cutaneous infections and malignancies, and decreased response to vaccination. Many factors have been proposed to contribute to immunosenescence. We recently described an aging-related decrease in receptor for activated C kinase (RACK)-1 expression, defective protein kinease Cβ II (PKC) translocation and reduced TNF-a release in rat epidermal cells. Given the observation that adrenal hormones follow a decrease during aging, our group has also demonstrated that the decreased level of RACK-1 protein expression during aging and the observed immune deficits in rats could be restored in vivo by treatment with dehydroepiandrosterone (DHEA). Similar defects were also observed in human skin as demonstrated by reduced expression of RACK-1 measured by western blot and immunofluorescence. As the DHEA/cortisol imbalance is important during aging, we found that DHEA and cortisol antagonistically act on RACK-1 transcription and translation, and, indirectly, on the LPS-induced cytokine production. Conclusion: These observations on the control of a key element in the signal transduction cascade regulating immune function highlight a link with the hormonal changes in cell environment associated with aging, and the complex process of ageing of the skin and its immune system.