LB964 Inhibition of TSLP, inflammatory cytokines, and tissue damage in a reconstructed human epidermis model mimicking atopic dermatitis

Abstract

Thymic stromal lymphopoietin (TSLP) is highly expressed by keratinocytes in atopic dermatitis (AD) in which TSLP drives immune dysregulation, barrier alternations, and triggers itch sensation. Several reports demonstrated that keratinocyte and reconstructed human epidermis (RHE) when treated with an inflammatory cocktail, comprised of a TLR3 agonist, Th2 cytokines and TNF-a, exhibited key aspects of AD-related phenotype including increased release of TSLP, cytokines, spongiosis, and disrupted skin barrier. The objective of this study was to develop this AD model and evaluate its utility for assessing topical actives in suppressing inflammation responses triggered by the AD inflammatory cocktail. Hydrocortisone was utilized for the initial evaluation of this AD model. Treatment of inflammatory cocktails comprised of different concentrations of poly I:C, IL-4, IL-13 and TNF-a resulted in a dose and time-dependent increased expression and release of inflammatory mediators (e.g., TSLP, COX-2, LTB4, and various cytokines) in RHE. The inflammatory cocktails also led to differing extents of tissue damage including spongiosis, reduced keratinocyte proliferation, differentiation, and tissue integrity. Topical treatment with hydrocortisone inhibited the inflammatory cocktail-induced TSLP, and cytokines. Histology analyses demonstrated that topical hydrocortisone alleviated the cocktail-induced tissue damage, and altered cell proliferation. Topical treatment with hydrocortisone, when applied prior to, simultaneously, or post-inflammatory cocktail treatment, resulted in differing degrees of protection against the inflammatory cocktail-induced TSLP, cytokines, and tissue damage, with the highest level of inhibition associated with application before cocktail treatment. In conclusion, this report suggests that the AD RHE model system could be a useful in vitro tool for the screening of therapeutic agents which target TSLP expression, as demonstrated by the results with hydrocortisone.