Gene expression analysis of EpiDerm (TM) following exposure to SLS using cDNA microarrays

There is a need to investigate the mechanistic basis of the human skin irri tation response if relevant in vitro test systems for the predictive identi fication of skin irritation hazards are to be developed. Recent progress in genomics technologies mean that tools for the identification and investiga tion of important biochemical events in the processes of skin irritation ar e now available. The aim of this work was to identify genes (for further me chanistic investigation) which may be regulated in response to skin irritat ion, following exposure of the EpiDerm(TM) skin model to the known skin irr itant sodium lauryl sulphate (SLS). EpiDerm cultures were treated in tripli cate with a non-cytotoxic dose of SLS (0.1 mg/ml, as determined by the MTT assay and histological examination) for 15 min, 30 min, 1 h, 2 h, 3 h, 4 h and 24 h. Total RNA was extracted from the pooled EpiDerm cultures and used to probe Atlas(TM) human arrays (Clontech) covering approximately 3600 gen es. Preliminary data indicated an up-regulation at early time points (15-30 min) of a number of genes involved in transportation (e.g. the sodium and chloride dependent taurine transporter) and receptors (e.g. ZAP70 and proto cadherin 42 precursor). The gene encoding the UV excision repair protein an d other DNA repair genes (e.g. DNA-directed RNA polymerase II) were up-regu lated after 1-3 h, along with TGF beta3 and other tumour suppressors, which play a role in cellular development and wound healing. At the later time p oints of 4-24 h, genes involved in protein translation (e.g. Cathepsin D re ceptor) and metabolism (e.g. CYP27A) were up-regulated. In addition, a numb er of genes were down-regulated in response to treatment with SLS, although these followed less of a time dependent pattern. These results indicate th e differential regulation of a number of genes in response to treatment wit h SLS, some of which may provide additional clues to the molecular events u nderpinning the irritation response to this particular surfactant and possi bly to other chemical irritants. (C) 2001 Elsevier Science Ltd. All rights reserved.