Tandem repeated irritation in aged skin induces distinct barrier perturbation and cytokine profile in vivo

Background The barrier perturbation pattern and molecular markers of inflammation upon tandem repeated irritation in chronologically aged skin have not been previously studied. Objectives We aimed to investigate the barrier impairment kinetic and in vivo cytokine profile following sequential irritation with sodium lauryl sulfate (SLS) and undiluted toluene (Tol) in aged compared with young skin. Methods Four fields on the volar forearm of healthy aged and young volunteers (median age, respectively, 63.9 and 32.6 years) were sequentially exposed to 0.5% SLS and undiluted toluene in a controlled tandem repeated irritation test; an adjacent nontreated field served as control. The permeability barrier function was monitored by repeated measurements of transepidermal water loss (TEWL), capacitance and erythema every 24 h up to 96 h. The stratum corneum cytokines were harvested by sequential tape stripping and quantified by multiplex bead array and enzyme-linked immunosorbent assay. Results Compared with young skin, aged skin was characterized by delayed and/or less pronounced alterations in the visual irritation score, TEWL, chromametry a*-value and capacitance, assessed by the respective Delta-values for each parameter and monitoring time point. In both groups, exposure to SLS/SLS, SLS/Tol and Tol/SLS resulted in decreased interleukin (IL)-1 alpha levels, whereas the application of Tol/Tol induced an increase in IL-1 alpha. Furthermore, decreased IL-1 receptor antagonist (IL-1RA) levels and a lower IL-1RA/IL-1 alpha ratio were found following repeated exposure to the irritants. Conclusions Our results provide evidence for selective alterations in the cytokine profile and distinct barrier impairment kinetic following tandem repeated irritation with SLS and Tol in aged compared with young skin in vivo.