title: pH-regulated mechanisms account for pigment-type differences in epidermal barrier function.
abstract: To determine whether pigment type determines differences in epidermal function, we studied stratum corneum (SC) pH, permeability barrier homeostasis, and SC integrity in three geographically disparate populations with pigment type I-II versus IV-V skin (Fitzpatrick I-VI scale). Type IV-V subjects showed: (i) lower surface pH (approximately 0.5 U); (ii) enhanced SC integrity (transepidermal water loss change with sequential tape strippings); and (iii) more rapid barrier recovery than type I-II subjects. Enhanced barrier function could be ascribed to increased epidermal lipid content, increased lamellar body production, and reduced acidity, leading to enhanced lipid processing. Compromised SC integrity in type I-II subjects could be ascribed to increased serine protease activity, resulting in accelerated desmoglein-1 (DSG-1)/corneodesmosome degradation. In contrast, DSG-1-positive CDs persisted in type IV-V subjects, but due to enhanced cathepsin-D activity, SC thickness did not increase. Adjustment of pH of type I-II SC to type IV-V levels improved epidermal function. Finally, dendrites from type IV-V melanocytes were more acidic than those from type I-II subjects, and they transfer more melanosomes to the SC, suggesting that melanosome secretion could contribute to the more acidic pH of type IV-V skin. These studies show marked pigment-type differences in epidermal structure and function that are pH driven.
authors.affiliation: Department of Dermatology, Veteran Affairs Medical Center, University of California San Francisco, San Francisco, California 94121, USA. gunathilake@att.net
authors.forename: Roshan
authors.initials: R
authors.lastname: Gunathilake
authors.forename: Nanna Y
authors.initials: NY
authors.lastname: Schurer
authors.forename: Brenda A
authors.initials: BA
authors.lastname: Shoo
authors.forename: Anna
authors.initials: A
authors.lastname: Celli
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hachem
authors.forename: Debra
authors.initials: D
authors.lastname: Crumrine
authors.forename: Ganga
authors.initials: G
authors.lastname: Sirimanna
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Feingold
authors.forename: Theodora M
authors.initials: TM
authors.lastname: Mauro
authors.forename: Peter M
authors.initials: PM
authors.lastname: Elias
mesh_terms: D000143:Acids / Q000378:metabolism; D000328:Adult; D001706:Biopsy; D003600:Cytosol / Q000378:metabolism; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism*; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D050356:Lipid Metabolism / Q000502:physiology; D008297:Male; D008544:Melanocytes / Q000378:metabolism; D009924:Organ Culture Techniques; D010539:Permeability; D012697:Serine Endopeptidases / Q000378:metabolism; D012880:Skin Pigmentation / Q000502:physiology*; D014867:Water / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology*; D055815:Young Adult
chemical_list: D000143:Acids; D014867:Water; D012697:Serine Endopeptidases