Ageing of human epidermis: the role of apoptosis, Fas and telomerase

Background Aged human epidermis is characterized by morphological changes including flattening of the dermal-epidermal junction and a decrease in thickness. Objectives To determine the roles of proliferation, apoptosis, Fas (CD95), Fas ligand (FasL) and telomerase in changes of human epidermis during ageing. Methods Human epidermis from aged subjects (n = 14; mean age 70.7 years) and young subjects (n = 14; mean age 23.4 years) was studied by histology, immunohistochemistry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling assay for apoptotic cells and reverse transcription-polymerase chain reaction to determine epidermal thickness, proliferation (Ki-67), apoptosis, expression of Fas and FasL, and telomerase activity. Results Aged skin was associated with thinning of the epidermis, decreased proliferation, and increased apoptosis below the granular layer. This was associated with increased epidermal expression of Fas and FasL. Telomerase activity was similar in aged and young epidermis. Conclusions Fas/FasL-mediated apoptosis, along with decreased proliferation, may have a role in changes of human epidermis during ageing. Telomerase activity did not appear to be limiting in young vs. old human epidermis.