Berna, N., A. Coquette, A. Vandenbosch, and Y. Poumay. Use of Reconstructed Epidermis to Assess Keratinocyte Activation by Skin Irritant and Sensitizing Compounds. J. Invest. Dermatol. 1998. 110(4): 657. Abstract #1108. [Repinted with permission of Blackwell Science, Inc.].

benzalkonium chloride - 08001-54-5; Triton X-100 - 09002-93-1; Tween 80 - 09005-65-6; dinitrochlorobenzene - 25567-67-3

A model of reconstructed epidermis (Rep) obtained from Skinethic was used as an in vitro skin model to discriminate the effect of known primary contact irritant and sensitizing compounds. The Reps were topically exposed for 20 hr (0.125-4 mg/ml) to three irritating (benzalkonium chloride (BZK), Triton X100 and Tween 80) and one sensitizing (dinitrochlorobenzene (DNCB)) compounds. These molecules produced different dose-dependent decreases in cell viability, corresponding with their in vivo irritative potency: BZK > DCNB > Triton > Tween. Using morphological observations, Triton X100 and DNCB at 2 mg/ml were found to damage the Rep, leading to a disaggregated cornified layer. The release of interleukin-1 alpha (IL-1a ), interleukin-8 (IL-8), and tumour necrosis factor alpha (TNF-a ) in the extracellular medium was measured by ELISA. The release of Il-1a was clearly dose-dependent and correlated with the potency of the irritant compounds. In identical conditions, no significant increase in IL-8 and TNF-a was observed. On the opposite, DNCB did not induce any significant increase in IL-1a release, but induced the release of IL-8 and TNF-a . RT-PCR analysis of the expression of these cytokines showed an increase of their corresponding mRNA at mild concentrations, but then revealed a decrease at the highest concentrations tested in the assay. These results could be explained by the loss of tissue viability at the highest concentrations after the 20^th treatment. Our results demonstrate that this in vitro skin model is a powerful tool for in vitro skin toxicological investigations and suggest that the production of cytokines could be related to the type of applied compound, whether irritant or sensitizing.