title: Defective barrier function in melasma skin.
abstract: BACKGROUND
  Melasma is characterized by increased pigmentation and photodamaged features, which include solar elastosis. Recently, we detected the downregulation of the genes most associated with lipid metabolism using microarray analysis in melasma. These findings suggested that lesional skin may have different biophysical characteristics, and, in particular, an altered skin barrier function.
  
  
  OBJECTIVE
  To determine the cutaneous biophysical characteristics of melasma.
  
  
  METHODS
  The melanin index, erythema index, stratum corneum hydration, sebum content and transepidermal water loss (TEWL) were measured for lesional and perilesional normal skin of 16 melasma patients and then compared. In addition, a skin biopsy was performed on 11 of the 16 study subjects to measure stratum corneum thickness and to study the protein expressions of PPAR-α and ALOX15B.
  
  
  RESULTS
  Melanin index, erythema index and stratum corneum hydration were significantly higher in lesional skin than in perilesional normal skin. No significant difference was found between lesional and normal skin in terms of basal TEWL level or sebum content. However, the rate of TEWL after barrier perturbation was significantly higher for lesional skin, and the barrier recovery rate was significantly delayed. Furthermore, a trend towards thinned stratum corneum was observed for lesional skin, and this was correlated with barrier recovery rate. The expressions of PPAR-α and ALOX15B were variable in the samples.
  
  
  CONCLUSIONS
  Melasma skin is characterized by impaired stratum corneum integrity and a delayed barrier recovery rate.
authors.affiliation: Department of Dermatology, Ajou University School of Medicine, Suwon, Korea.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Ha
authors.forename: K-C
authors.initials: KC
authors.lastname: Park
authors.forename: J-P
authors.initials: JP
authors.lastname: Ortonne
authors.forename: H Y
authors.initials: HY
authors.lastname: Kang
mesh_terms: D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism; D001703:Biophysics; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008543:Melanins / Q000378:metabolism; D008548:Melanosis / Q000378:metabolism / Q000503:physiopathology*; D047495:PPAR gamma / Q000378:metabolism; D010539:Permeability; D056910:Republic of Korea; D012629:Sebum / Q000378:metabolism
chemical_list: D008543:Melanins; D047495:PPAR gamma; C458528:ALOX15B protein, human; D001093:Arachidonate 15-Lipoxygenase