EFFECTS OF GALACTOMYCES FERMENT FILTRATE ON EPIDERMAL BARRIER MARKER CASPASE-14 IN HUMAN SKIN CELLS.

BACKGROUND: The stratum corneum of human epidermis is composed of terminally differentiated keratinocytes serving as an essential barrier to environmental stresses, such as UV induced photodamage, and water loss. The regulatory and proteolytic events that coordinate barrier formation are tightly controlled. Caspase-14 belongs to a conserved family of aspartate-specific proteases. Its epidermal expression is restricted almost exclusively to the suprabasal layers, implicating this protease in keratinocyte terminal differentiation and cornification. Thus, caspase-14 is a useful biomarker to monitor formation and homeostasis of the stratum corneum barrier1). Galactomyces Ferment Filtrate (GFF) is used as a moisturizing agent in cosmetics. In vitro GFF has several beneficial effects, such as antioxidant effects through activation of ARE-related genes in human skin cells2) and induction of hyaluronan production in epidermal cells3). In the current work we focused on caspase-14 in order to elucidate further the effects of GFF. METHODS: In vitro human skin models, including skin keratinocytes and skin equivalents (SE) with partially (EPI-201) or completely formed (EPI- 200) stratified, cornified epidermis were treated topically with GFF or Dexamethasone (Dex). The SE models were cultured in EPI-100MM medium without hydrocortisone. GFF was diluted with distilled water and added to stratum corneum surface of the skin cultures. Dex and RU-486 (a glucocorticoid receptor antagonist) were added to culture medium of the models. For western blot and caspase-14 (cas-14) analysis, protein was extracted from SE models in PBS by sonication. The data were compared using the Tukey’s test. Differences were considered significant at p < 0.05. CONCLUSIONS: These results indicate that GFF increases caspase-14 expression by epidermal cells, specifically during late stage differentiation. The positive effect of GFF on late differentiation biomarkers supports previous in vivo observations that GFF-containing moisturizers help protect the skin against damage 6-7), such as due to dryness or environmental stress. These results provide a compelling reason to further understand the nature of GFF and its potential benefits for skin.

Antioxidant, Aspartate-specific proteases, Caspase-14, EPI-200, EPI-201, Homeostasis of the stratum corneum barrier, Keratinocyte terminal differentiation, Moisturizing agent, Peptidylarginine deiminase 1, Peptidylarginine deiminase 3, Profilaggrin, Transglutaminase

Dexamethasone, Galactomyces Ferment Filtrate (GFF), RU-486; a glucorticoid receptor antagonist