title: Sustained serine proteases activity by prolonged increase in pH leads to degradation of lipid processing enzymes and profound alterations of barrier function and stratum corneum integrity.
abstract: We showed recently that short-term increases in stratum corneum (SC) pH are accompanied by minor alterations in permeability barrier homeostasis and SC integrity/cohesion. Since prolonged SC neutralization more closely mirrors clinical situations (i.e., neonatal skin, occupational dermatitis conditions), we assessed here whether sustained elevations of SC pH by long-term application of 1,1,3,3-tetramethylguanidine superbase provoke profound alterations in SC function. Sustained SC neutralization altered not only barrier recovery kinetics but also basal permeability barrier function. These abnormalities were attributable to a decrease in beta-glucocerebrosidase (beta-GlcCer'ase) and acidic sphingomyelinase (aSMase) catalytic activity and enzyme degradation consequent to a pH-induced sustained serine protease (SP) activity. The role of SP in this process was shown by the normalization of enzyme activities/content by co-applied SP inhibitors (SPI). To address whether lipid-processing enzymes are potential substrates for the stratum corneum chymotryptic enzyme (SCCE), protein extracts from human SC were treated for 2 h at 37 degrees C with recombinant active SCCE at pH 7.2. Recombinant SCCE induced a significant decrease in the immunoblotting of both beta-GlcCer'ase or aSMase compared with control experiments performed in the absence of the active SCCE. Finally, with sustained SC neutralization, SC integrity/cohesion deteriorated, attributable to SP-mediated degradation of corneodesmosomes (CD) as well as CD constituent proteins, desmoglein 1. These abnormalities were again reversed by co-applied SPI. In conclusion, prolonged SC neutralization provokes profound abnormalities in SC function, due to pH-induced high SP activity that, in turn, degrades lipid processing enzymes and CD proteins.
authors.affiliation: Dermatology, VA Medical Center, University of California, San Francisco, 94121, USA.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hachem
authors.forename: Mao-Quiang
authors.initials: MQ
authors.lastname: Man
authors.forename: Debra
authors.initials: D
authors.lastname: Crumrine
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Uchida
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Brown
authors.forename: Vera
authors.initials: V
authors.lastname: Rogiers
authors.forename: Diane
authors.initials: D
authors.lastname: Roseeuw
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Feingold
authors.forename: Peter M
authors.initials: PM
authors.lastname: Elias
mesh_terms: D000818:Animals; D002384:Catalysis; D004817:Epidermis / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005962:Glucosylceramidase / Q000378:metabolism*; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007610:Kallikreins / Q000187:drug effects / Q000378:metabolism*; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D011994:Recombinant Proteins; D012697:Serine Endopeptidases / Q000187:drug effects / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*
chemical_list: D006146:Guanidines; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; D013108:Sphingomyelin Phosphodiesterase; D005962:Glucosylceramidase; D007610:Kallikreins; C495974:Klk7 protein, mouse; D012697:Serine Endopeptidases; C477069:1,1,3,3-tetramethylguanidine