Filaggrin deficiency leads to impaired lipid profile and altered acidification pathways in a 3D skin construct.
Mutations in the filaggrin (FLG) gene are strongly associated with common dermatological disorders such as atopic dermatitis. However, the exact underlying pathomechanism is still ambiguous. Here, we investigated the impact of FLG on skin lipid composition, organization, and skin acidification using a FLG knockdown (FLG-) skin construct. Initially, sodium/hydrogen antiporter (NHE-1) activity was sufficient to maintain the acidic pH (5.5) of the reconstructed skin. At day 7, the FLG degradation products urocanic (UCA) and pyrrolidone-5-carboxylic acid (PCA) were significantly decreased in FLG- constructs, but the skin surface pH was still physiological owing to an upregulation of NHE-1. At day 14, secretory phospholipase A2 (sPLA2) IIA, which converts phospholipids to fatty acids, was significantly more activated in FLG- than in FLG+. Although NHE-1 and sPLA2 were able to compensate the FLG deficiency, maintain the skin surface pH, and ensured ceramide processing (no differences detected), an accumulation of free fatty acids (2-fold increase) led to less ordered intercellular lipid lamellae and higher permeability of the FLG- constructs. The interplay of the UCA/PCA and the sPLA2/NHE-1 acidification pathways of the skin and the impact of FLG insufficiency on skin lipid composition and organization in reconstructed skin are described.
Faculty of Pharmacy, Charles University in Prague, Hradec Kralove, Czech Republic.
Kateřina
K
Vávrová
Institute for Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, Germany.
Dominika
D
Henkes
Department of Pharmacy, Ludwig-Maximilians University Munich, Munich, Germany.
Kay
K
Strüver
Faculty of Pharmacy, Charles University in Prague, Hradec Kralove, Czech Republic.
Michaela
M
Sochorová
Faculty of Pharmacy, Charles University in Prague, Hradec Kralove, Czech Republic.
Barbora
B
Školová
Department of Pharmacy, Ludwig-Maximilians University Munich, Munich, Germany.
Madeleine Y
MY
Witting
Department of Pharmacy, Ludwig-Maximilians University Munich, Munich, Germany.
Wolfgang
W
Friess
Department of Dermatology, University Medical Center Regensburg, Regensburg, Germany.
Stephan
S
Schreml
Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Regensburg, Germany.
Robert J
RJ
Meier
Institute for Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, Germany.
Monika
M
Schäfer-Korting
Department of Dermatology, Charité University Clinic, Berlin, Germany.
Joachim W
JW
Fluhr
Institute for Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, Germany. Electronic address: sarah.kuechler@fu-berlin.de.
Sarah
S
Küchler
D000143:Acids / Q000378:metabolism*; D003876:Dermatitis, Atopic / Q000378:metabolism* / Q000473:pathology; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D000091344:Filaggrin Proteins; D055785:Gene Knockdown Techniques; D054501:Group II Phospholipases A2 / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007381:Intermediate Filament Proteins / Q000172:deficiency* / Q000235:genetics*; D050356:Lipid Metabolism / Q000502:physiology*; D010539:Permeability; D011761:Pyrrolidonecarboxylic Acid / Q000378:metabolism; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D014560:Urocanic Acid / Q000378:metabolism
D000143:Acids; C000717249:FLG protein, human; D005230:Fatty Acids, Nonesterified; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D017923:Sodium-Hydrogen Exchangers; C069139:growth factor-activatable Na-H exchanger NHE-1; D054501:Group II Phospholipases A2; D014560:Urocanic Acid; D011761:Pyrrolidonecarboxylic Acid