Metabolically Competent Human Skin Models: Activation and Genotoxicity of Benzo[a]pyrene

Abstract

The polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (BP) is metabolized into a complex pattern of BP derivatives, among which the ultimate carcinogen (+)-anti-BP-7,8-diol-9,10-epoxide (BPDE) is formed to certain extents. Skin is frequently in contact with PAHs and data on the metabolic capacity of skin tissue toward these compounds are inconclusive. We compared BP metabolism in excised human skin, commercially available in vitro 3D skin models and primary 2D skin cell cultures, and analyzed the metabolically catalyzed occurrence of seven different BP follow-up products by means of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). All models investigated were competent to metabolize BP, and the metabolic profiles generated by ex vivo human skin and skin models were remarkably similar. Furthermore, the genotoxicity of BP and its derivatives was monitored in these models via comet assays. In a full-thickness skin, equivalent BP-mediated genotoxic stress was generated via keratinocytes. Cultured primary keratinocytes revealed a level of genotoxicity comparable with that of direct exposure to 50–100nM of BPDE. Our data demonstrate that the metabolic capacity of human skin ex vivo, as well as organotypic human 3D skin models toward BP, is sufficient to cause significant genotoxic stress and thus cutaneous bioactivation may potentially contribute to mutations that ultimately lead to skin cancer.

Extracellular signal-regulated kinases 1/2 and Akt contribute to triclosan-stimulated proliferation of JB6 Cl 41-5a cells

“…It should be noted that the present study was performed in only murine systems, and it is unknown whether these findings are relevant to humans. recently, the use of reconstructed 3D models of human skin has been increasing in drug safety evaluation and toxicology studies (Brinkmann et al 2013;canton et al 2010;gotz et al 2012a, b;Hewitt et al 2013;Netzlaff et al 2005;reus et al 2013;Torti et al 2012). Future studies will use the 3D models of human skin to determine whether triclosan has similar effects as observed in mice.…”

Non-animal models of epithelial barriers (skin, intestine and lung) in research, industrial applications and regulatory toxicology

“…Comprehensive investigations into the expression and functionality of enzymes involved in cutaneous biotransformation of xenobiotics in human skin ex vivo as well as in reconstructed tissue models are ongoing, and knowledge continues to improve (Gotz et al, 2012;Huh et al, 2010;Oesch et al, 2014). Pre-validation studies have in fact been conducted with HSEs to address genotoxicity (Brinkmann et al, 2013;Fautz et al, 2013) and skin metabolism (Schafer-Korting et al, 2006). Two in vitro genotoxicity approaches using three-dimensional skin models have been proposed: i) the human reconstructed skin micronucleus (RSMN) assay using the EpiDerm™ model, and ii) the Comet assay, which detects complementary DNA damage, including damage indicative of the occurrence of gene mutations (EpiDerm™, Phenion™).…”

A review of the current state of the art of physiologically-based tests for measuring human dermal in vitro bioavailability of polycyclic aromatic hydrocarbons (PAH) in soil

“…Langerhan cells may increase the likelihood of carcinogenesis due to the metabolisation of dermally absorbed PAH (Modi et al, 2012); similar observations of the genotoxicity of benzo[a]pyrene have also been made for metablolisation by kerotinocytes (e.g. Brinkmann et al 2013). It is because there is a potential for localised effects caused by PAH that bioavailability is defined in this review as a substance "absorbed into any part of the epidermis" rather than only the fraction subject to systemic circulation.…”