LB989 Validation of the EpiScreen™ drug screening platform: Identification and characterization of trichostatin A as a potent epidermal differentiation enhancer

Abstract

EpiScreen™ has been designed for dermatology drug screening as well as the characterization of cosmetic ingredients to support efficacy claims. Generated from primary human keratinocytes, this multilayered microepidermis bridges the gap between non-physiological 2D cell culture and reconstructed models incompatible with high debit imaging. To demonstrate this first commercially available solution for screening in a 3D epidermis, EpiScreen™ was used to detect compounds that increase filaggrin (FLG), a strategy of interest to treat dry skin during aging, atopic dermatitis and psoriasis. Among compounds that enhanced FLG protein levels above 2-fold, trichostatin A (TSA) was selected for further analysis. Dose response and kinetic studies combined with cell viability and Ki-67 proliferation marker readouts showed that TSA treatment for 3 days increased overall cell numbers (+50%) with a decrease in the proliferation index. Computational reconstruction of multiple whole microepidermis demonstrated that TSA thickens specifically the suprabasal layers (2-fold). As measured by quantification of fluorescence from images, TSA increased protein expression levels of keratin-14, keratin-1 and aquaporin-3 (1.7, 4 and 2-fold respectively). The differentiation promoting properties of TSA were accompanied by a 2-fold increase in E-cadherin and desmoglein levels, indicating that TSA enhances strength and cohesion of the epidermis. Using the EpiScreen™ “psoriatic” model that displays abnormal morphology and expression of antibacterial proteins (S100A7, BD2), TSA showed anti-inflammatory potential and attenuated certain markers associated with the disease phenotype. Here, EpiScreen™ provides a rationale for the beneficial actions of TSA using keratinocytes as the target cell and supports renewed interest in histone deacetylase inhibitors for the treatment of skin disorders. The above data are consistent with reports from organ and mouse models and is proof of concept showing the relevance of EpiScreen™ for screening, exclusion and validation of compounds.