MICROARRAY ANALYSIS OF GENE EXPRESSION FOLLOWING EXPOSURE TO SKIN IRRITANTS.

Understanding of the mechanistic basis of the human skin irritation response is key to the development of relevant in vitro test systems for the predictive identification of skin irritation hazards. Recent progress in genomic technologies means that tools for the identification and investigation of important biochemical events in the processes of skin irritation are now available. This work was designed to identify genes for further mechanistic investigation which are regulated in response to skin irritation, following exposure of the EpiDerm™ skin model to the known irritant sodium lauryl sulphate (SLS). EpiDerm™ cultures were treated in triplicate with a noncytotoxic dose of SLS (0.1 mg per 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 pooled EpiDerm™ cultures and used to probe Atlas™ human arrays (Clontech) covering approximately 3600 genes. 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. ZAP7O). The gene encoding the UV excision repair protein and other DNA repair genes (e.g. DNA-directed RNA polymerase II) were up-regulated at 1-3 h along with TGFβ3 and other tumour suppressors (which play a role in cellular development and wound healing. At the later time points of 4-24 h, genes involved in protein translation (e.g. Cathepsin D receptor) and metabolism (e.g. CYP27A) were up-regulated. In addition, a number of genes were down-regulated in response to treatment with SLS, although these followed less of a time dependent pattern. These results indicate the differential regulation of a number of genes in response to treatment with SLS which may provide insights into the molecular events in the response to this irritant.

Atlas, Cutaneous irritancy, Cutaneous irritation, Cutaneous toxicity, Dermal irritancy, Dermal irritancy testing, Dermal irritation, EpiDerm, Gene expression, Genomic technologies, Human arrays, Irritants, MTT, MTT ET-50 tissue viability assay, MTT assay, Metabolism, Microarray, Pre-validation, Prevalidation, RNA, SLS, Skin irritancy, Skin irritation, Sodium lauryl sarconsinate, isolation of, Toxicology, Validation