Specific barrier response profiles after experimentally induced skin irritation in vivo

Background: Recently, natural moisturizing factors (NMFs) and corneocyte surface topography were suggested as biomarkers for irritant dermatitis. Objectives: To investigate how exposure to different irritants influences corneocyte surface topography, NMF levels and the barrier function of human skin in vivo. Methods: Eight healthy adult volunteers were exposed to aqueous solutions of 60% n-propanol, 0.5% sodium lauryl sulfate (SLS), 0.15% sodium hydroxide, and 2.0% acetic acid, and distilled water, in a repeated irritation test over a period of 96 hours. Erythema, transepidermal water loss (TEWL), skin hydration, the dermal texture index (DTI) and NMF levels were measured at baseline, and after 24 and 96 hours. Results: SLS and sodium hydroxide had the most pronounced effects on erythema and TEWL. Although n-propanol caused only slight changes in TEWL and erythema, it showed pronounced effects on skin hydration, NMF levels, and the DTI. NMF was the only parameter that was significantly altered by all investigated irritants. The changes in the DTI were inversely associated with NMF levels and skin hydration. Conclusion: Skin barrier impairment and the inflammatory response are irritant-specific, emphasizing the need for a multiparametric approach to the study of skin irritation. NMF levels seem to be the most sensitive parameter in detecting irritant-induced skin barrier alterations.