title: Ageing of human epidermis: the role of apoptosis, Fas and telomerase.
abstract: BACKGROUND
  Aged human epidermis is characterized by morphological changes including flattening of the dermal-epidermal junction and a decrease in thickness.
  
  
  OBJECTIVE
  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.
authors.affiliation: Skin Research Laboratory, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel. gilhar@tx.technion.ac.il
authors.forename: A
authors.initials: A
authors.lastname: Gilhar
authors.forename: Y
authors.initials: Y
authors.lastname: Ullmann
authors.forename: R
authors.initials: R
authors.lastname: Karry
authors.forename: R
authors.initials: R
authors.lastname: Shalaginov
authors.forename: B
authors.initials: B
authors.lastname: Assy
authors.forename: S
authors.initials: S
authors.lastname: Serafimovich
authors.forename: R S
authors.initials: RS
authors.lastname: Kalish
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D004817:Epidermis / Q000378:metabolism / Q000503:physiopathology*; D053222:Fas Ligand Protein; D015870:Gene Expression; D006801:Humans; D020287:In Situ Nick-End Labeling; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015595:Skin Aging / Q000502:physiology*; D019098:Telomerase / Q000502:physiology*; D019014:fas Receptor / Q000235:genetics / Q000502:physiology*
chemical_list: C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D019014:fas Receptor; D019098:Telomerase