Morphometry and Epidermal Fas Expression of Unexposed Aged Versus Young Skin

BACKGROUND: Identifying the molecular mechanisms of intrinsic aging is critical in developing modalities for reversal of cutaneous aging. OBJECTIVE: The objective was to evaluate the expression of epidermal Fas, epidermal thickness, collagen, and elastic fibers degeneration in unexposed skin of aged individuals compared with young ones. MATERIALS AND METHODS: Skin biopsies were taken from normal skin of the back of 22 old subjects (age range: 48-75 years) and 15 young subjects (age range: 18-28 years). Skin sections were stained with hematoxylin and eosin, Masson trichrome, orcein. Epidermal thickness was measured with image analyzer and scoring was done for collagen and elastic fiber degeneration. Fas immunostaining was done. Quantitative and qualitative data were compared statistically between the old and young subjects. RESULTS: A statistically significant decreased epidermal thickness was found in old compared with young skin (P<0.05). A statistically significant number of patients showed decreased epidermal thickness, density, and fragmentation of both collagen and elastic fibers in old compared with young skin (P<0.001). Epidermal Fas expression was detected in 19 of 22 old subjects (86.4%) compared with 2 of 15 young subjects (13.3%) (P<0.001). There was no statistically significant correlation between age of old subjects and each of epidermal thickness, collagen, and elastic fiber degeneration. CONCLUSION: The decreased epidermal thickness and morphological alteration of collagen and elastic fibers are not correlated with aging and Fas-mediated apoptosis could be involved in thinning of the epidermis in unexposed aged skin.