Characterization of xenobiotic metabolizing enzymes of a reconstructed human epidermal model from adult hair follicles

Toxicol Appl Pharmacol. 2017 Aug 15;329:190-201. doi: 10.1016/j.taap.2017.05.040. Epub 2017 Jun 7.

Abstract

In this study, a comprehensive characterization of xenobiotic metabolizing enzymes (XMEs) based on gene expression and enzyme functionality was made in a reconstructed skin epidermal model derived from the outer root sheath (ORS) of hair follicles (ORS-RHE). The ORS-RHE model XME gene profile was consistent with native human skin. Cytochromes P450 (CYPs) consistently reported to be detected in native human skin were also present at the gene level in the ORS-RHE model. The highest Phase I XME gene expression levels were observed for alcohol/aldehyde dehydrogenases and (carboxyl) esterases. The model was responsive to the CYP inducers, 3-methylcholanthrene (3-MC) and β-naphthoflavone (βNF) after topical and systemic applications, evident at the gene and enzyme activity level. Phase II XME levels were generally higher than those of Phase I XMEs, the highest levels were GSTs and transferases, including NAT1. The presence of functional CYPs, UGTs and SULTs was confirmed by incubating the models with 7-ethoxycoumarin, testosterone, benzo(a)pyrene and 3-MC, all of which were rapidly metabolized within 24h after topical application. The extent of metabolism was dependent on saturable and non-saturable metabolism by the XMEs and on the residence time within the model. In conclusion, the ORS-RHE model expresses a number of Phase I and II XMEs, some of which may be induced by AhR ligands. Functional XME activities were also demonstrated using systemic or topical application routes, supporting their use in cutaneous metabolism studies. Such a reproducible model will be of interest when evaluating the cutaneous metabolism and potential toxicity of innovative dermo-cosmetic ingredients.

Keywords: Cutaneous metabolism; Functional activity; Gene expression; Hair follicle; Reconstructed human epidermis.

MeSH terms

  • Basic Helix-Loop-Helix Transcription Factors / agonists
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Cells, Cultured
  • Cytochrome P-450 Enzyme Inducers / pharmacology
  • Cytochrome P-450 Enzyme System / biosynthesis*
  • Cytochrome P-450 Enzyme System / genetics
  • Enzyme Induction
  • Glutathione Transferase / biosynthesis
  • Glutathione Transferase / genetics
  • Hair Follicle / cytology
  • Hair Follicle / drug effects
  • Hair Follicle / enzymology*
  • Humans
  • Isoenzymes
  • Keratinocytes / drug effects
  • Keratinocytes / enzymology*
  • Kinetics
  • Ligands
  • Metabolic Detoxication, Phase I
  • Metabolic Detoxication, Phase II
  • Receptors, Aryl Hydrocarbon / agonists
  • Receptors, Aryl Hydrocarbon / metabolism
  • Substrate Specificity
  • Sulfotransferases / biosynthesis
  • Sulfotransferases / genetics
  • Xenobiotics / metabolism*

Substances

  • AHR protein, human
  • Basic Helix-Loop-Helix Transcription Factors
  • Cytochrome P-450 Enzyme Inducers
  • Isoenzymes
  • Ligands
  • Receptors, Aryl Hydrocarbon
  • Xenobiotics
  • Cytochrome P-450 Enzyme System
  • Glutathione Transferase
  • Sulfotransferases