title: Variation in the activities of late stage filaggrin processing enzymes, calpain-1 and bleomycin hydrolase, together with pyrrolidone carboxylic acid levels, corneocyte phenotypes and plasmin activities in non-sun-exposed and sun-exposed facial stratum corneum of different ethnicities.
abstract: BACKGROUND
  Knowledge of the ethnic differences and effects of photodamage on the relative amounts of natural moisturizing factor (NMF) together with filaggrin processing enzymes in facial stratum corneum is limited. Our aim was to characterize the activities of calpain-1 (C-1), bleomycin hydrolase (BH) and the levels of pyrrolidone carboxylic acid (PCA) as a marker for total NMF levels and to relate them to plasmin activities and corneocyte maturation.
  
  
  METHODS
  Enzyme activities, PCA levels and corneocyte maturation were determined from facial tape strippings of photoexposed cheek and photoprotected post-auricular areas (PA) of healthy Caucasian (C), Black African (BA) and albino African (AA) female subjects living in South Africa.
  
  
  RESULTS
  PCA concentration levels were of the order AA > BA > C subjects, and the highest activities of BH were present in the AA subjects. BH activities were greater on the photoexposed sites for the BA and C subjects, but they were only numerically elevated in the AA subjects. Photoprotected sites had an increase in C-1 activity in pigmented groups (C and BA), whereas in the AA subjects, the opposite was measured. Plasmin activities were greater on the cheek compared with the PA site for the AA and C subjects, but the activity was low in the BA subjects. In both test sites, the AA, but not the BA and C subjects, had smaller, parakeratotic and less mature corneocytes.
  
  
  CONCLUSIONS
  Variation in PCA levels has been found for different ethnic groups in this study (AA > BA > C subjects). The values in the AA subjects are surprising as one might expect that the lack of pigmentation, and thereby increased photodamage, might lead to lower levels. Increased BH, but not C-1 activity, was observed in the AA subjects indicating that BH is associated with PCA production to a greater extent. Surprisingly, corneocyte maturation is still impaired with elevated PCA levels in AA subjects. The higher levels of plasmin and BH activities on the cheeks, especially for AA and C subjects, suggest that they can be used as markers for epidermal photodamage.
authors.affiliation: UCL School of Pharmacy, London, U.K.
authors.forename: N
authors.initials: N
authors.lastname: Raj
authors.affiliation: DSM Nutritional Products Ltd., Kaiseraugst, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Voegeli
authors.affiliation: UCL School of Pharmacy, London, U.K.
authors.forename: A V
authors.initials: AV
authors.lastname: Rawlings
authors.affiliation: Photobiology Laboratory, Sefako Makgatho Health Sciences University, Medunsa, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Summers
authors.affiliation: UCL School of Pharmacy, London, U.K.
authors.forename: M R
authors.initials: MR
authors.lastname: Munday
authors.affiliation: UCL School of Pharmacy, London, U.K.
authors.forename: M E
authors.initials: ME
authors.lastname: Lane
mesh_terms: D000328:Adult; D002154:Calpain / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D005006:Ethnicity; D005145:Face; D005260:Female; D000091344:Filaggrin Proteins; D006801:Humans; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D008297:Male; D011761:Pyrrolidonecarboxylic Acid / Q000378:metabolism*; D012867:Skin / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects*
chemical_list: C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D002154:Calpain; D003546:Cysteine Endopeptidases; C031262:bleomycin hydrolase; D011761:Pyrrolidonecarboxylic Acid
keywords: biomarkers; ethnic differences; face; natural moisturizing factor; photodamage