Modelling atopic dermatitis during the morphogenetic process involved in reconstruction of a human epidermis E ´ . De Vuyst, A. Mound, C. Lambert de Rouvroit, Y. Poumay * URPHYM, Namur research institute for life sciences, University of Namur, 61, rue de Bruxelles, 5000 Namur, Belgium Plasma membranes of eukaryotic cells organize as phospholipid bilayers in order to define cell boundaries. Phospholipids constituting the plasma membrane are amphiphilic, allowing them to naturally create a bilayer as they orient hydrophobic tails in the centre of the bilayer where they can associate with each other and expose hydrophilic heads towards the exterior of the membrane, where they will be in contact either with the extracellular liquid in case of plasma membrane or with the cytosol. Phospholipids associate with sphingolipids and sterols to become the major lipid constituents of the plasma membrane. It was reported that plasma membranes contain particularly high concentrations of cholesterol and sphingolipids within specialized specific regions of the membrane called membrane lipid domains. Such domains exhibit elevated affinities for multiple proteins involved in precise signalling pathways, such as the epidermal growth factor receptor (EGFR) as one example [1–3]. Cholesterol being one crucial component of the specialized membrane lipid domains in animals, a widely used experimental approach of the role of cholesterol in the function and structure of these lipid domains utilizes various cholesterol-depleting agents to extract cholesterol from the plasma membrane. One of these agents is the molecule called methyl-b-cyclodextrin (MbCD), commonly used as an externally hydrophilic molecule that is able to solubilize cholesterol in aqueous environments, like body fluids or culture media. MbCD is totally unable to cross cell membranes, but contains a central hydrophobic cavity which can, due to its steric characteristics, specifically extract cholesterol from plasma membranes. Thus, using MbCD to deplete cholesterol is supposed to effectively disrupt molecular organization of every cholesterol- containing membrane domain, as well as linked signalling pathways. MbCD has become of interest in the context of atopic dermatitis (AD) when transcriptomic microarray analyses of cholesterol- depleted keratinocytes by MbCD have shown regulations of this cell type’s phenotype that were quite similar to the abnormal Current Research in Translational Medicine 64 (2016) 179–183 A R T I C L E I N F O Article history: Received 10 October 2016 Accepted 12 October 2016 Available online 17 November 2016 Keywords: Atopic dermatitis Reconstructed human epidermis Cholesterol Interleukins Epidermal barrier A B S T R A C T Most crucial role of epidermis is to maintain efficient barrier between the organism and its environment. This barrier is however perturbed in inflammatory skin conditions like atopic dermatitis (AD), one common chronic disease. This review depicts characteristics of a model intending to reproduce epidermal features of AD in vitro. Firstly, methyl-b-cyclodextrin (MbCD) during reconstruction of epidermis was used to deplete cholesterol from plasma membrane because this condition reproduces characteristics of AD at transcriptomic level in monolayer cultures. Major changes are confirmed after same treatment inside reconstructed human epidermis (RHE). However, since early treatment do not reveal impairment to reconstruct a functional epidermal barrier and given the importance of the Th2 dysregulated immune response in AD, cholesterol-depleted RHE at day 11 of reconstruction were then incubated with three Th2-related cytokines (IL-4, IL-13 and IL-25) previously reported as playing important roles in the development of AD, as well as altering overall function of epidermal barrier. When combining both treatments, essential epidermal features of AD are observed. Indeed, RHE then exhibit spongiosis, disappearing granular layer, alteration of barrier function, as well as dysregulated expression levels for genes involved in AD pathogenesis. Moreover, while trying to identify individual roles for each component used to create AD-like alterations, incubation with IL-4 following cholesterol depletion from plasma membrane was found inducing most of the reported alterations. This model suggests potential for better investigations of epidermal AD features and may be considered for eventual in vitro screening of cosmetics or therapeutic compounds. ß 2016 Elsevier Masson SAS. All rights reserved. * Corresponding author. Tel.: +3281724257; fax: +3281724261. E-mail address: yves.poumay@unamur.be (Y. Poumay). Available online at ScienceDirect www.sciencedirect.com http://dx.doi.org/10.1016/j.retram.2016.10.005 2452-3186/ß 2016 Elsevier Masson SAS. All rights reserved.