title: Xenobiotic metabolism capacities of human skin in comparison with a 3D-epidermis model and keratinocyte-based cell culture as in vitro alternatives for chemical testing: phase II enzymes.
abstract: The 7th Amendment to the EU Cosmetics Directive prohibits the use of animals in cosmetic testing for certain endpoints, such as genotoxicity. Therefore, skin in vitro models have to replace chemical testing in vivo. However, the metabolic competence neither of human skin nor of alternative in vitro models has so far been fully characterized, although skin is the first-pass organ for accidentally or purposely (cosmetics and pharmaceuticals) applied chemicals. Thus, there is an urgent need to understand the xenobiotic-metabolizing capacities of human skin and to compare these activities to models developed to replace animal testing. We have measured the activity of the phase II enzymes glutathione S-transferase, UDP-glucuronosyltransferase and N-acetyltransferase in ex vivo human skin, the 3D epidermal model EpiDerm 200 (EPI-200), immortalized keratinocyte-based cell lines (HaCaT and NCTC 2544) and primary normal human epidermal keratinocytes. We show that all three phase II enzymes are present and highly active in skin as compared to phase I. Human skin, therefore, represents a more detoxifying than activating organ. This work systematically compares the activities of three important phase II enzymes in four different in vitro models directly to human skin. We conclude from our studies that 3D epidermal models, like the EPI-200 employed here, are superior over monolayer cultures in mimicking human skin xenobiotic metabolism and thus better suited for dermatotoxicity testing.
authors.affiliation: Leibniz-Institut für Umweltmedizinische Forschung (IUF), Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Götz
authors.forename: Roland
authors.initials: R
authors.lastname: Pfeiffer
authors.forename: Julia
authors.initials: J
authors.lastname: Tigges
authors.forename: Karsten
authors.initials: K
authors.lastname: Ruwiedel
authors.forename: Ulrike
authors.initials: U
authors.lastname: Hübenthal
authors.forename: Hans F
authors.initials: HF
authors.lastname: Merk
authors.forename: Jean
authors.initials: J
authors.lastname: Krutmann
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Edwards
authors.forename: Josef
authors.initials: J
authors.lastname: Abel
authors.forename: Camilla
authors.initials: C
authors.lastname: Pease
authors.forename: Carsten
authors.initials: C
authors.lastname: Goebel
authors.forename: Nicola
authors.initials: N
authors.lastname: Hewitt
authors.forename: Ellen
authors.initials: E
authors.lastname: Fritsche
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism*; D000826:Animal Testing Alternatives; D002460:Cell Line; D002478:Cells, Cultured; D003358:Cosmetics; D003885:Dermotoxins; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D008954:Models, Biological; D012867:Skin / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014116:Toxicology; D015262:Xenobiotics / Q000378:metabolism*
chemical_list: D003358:Cosmetics; D003885:Dermotoxins; D015262:Xenobiotics; D000123:Acetyltransferases; D014453:Glucuronosyltransferase; D005982:Glutathione Transferase