340 Interface dermatitis shows a distinctive molecular signature independent from individual disease background F Lauffer, L Krause, R Franz, N Garzorz-Stark, T Biedermann, F Theis, C Schmidt-Weber, S Eyerich and K Eyerich 1 Department of Dermatology and Allergy, Technical University of Munich, Munich, Germany, 2 Center of Allergy and Environment (ZAUM), Helmholtz Center Munich and Technical University of Munich, Munich, Germany and 3 Institute of Computational Biology, Helmholtz Center Munich, Neuherberg, Germany Interface dermatitis (ID) is a unique type of skin inflammation characterized by a dense lymphocytic infiltrate at the dermo-epidermal junction and vacuolated or apoptotic basal keratinocytes. Despite its typical histological appearance ID is not restricted to a single skin disease but can be found in various chronic inflammatory skin diseases, such as lichen planus (LP), as well as in autoimmune diseases, like cutaneous lupus erythematosus (CLE). Even though the pathogenesis of ID is still not understood, its stable and distinctive nature indicates that common mechanisms might orchestrate the inflammatory pattern independently from the underlying skin disease. In a cohort of patients with either LP (n1⁄412) or CLE (n1⁄46) molecular signatures of affected skin in comparison to autologous non-lesional skin were analysed by whole genome expression analysis. Furthermore, histological phenotyping was performed establishing an objective and reliable severity score of ID. To identify ID specific genes, only genes regulated simultaneously in both, LP and CLE, were then tested for correlation to the degree of ID. Induced network modules analysis revealed a contribution of the JAK/STAT pathway, reflected by a downregulation of SOCS3 and induction of chemokines (CXCL2, CXCL13) as well as cytotoxic T cell marker (CTLA4). Thus, in this study we could identify molecular pathways which regulate the inflammatory composition of ID independently from individual disease background. 341 Accelerated growth of Malassezia species in optimized culture conditions C Leong, A Buttafuoco, P Schmid-Grendelmeier, PP Bosshard and M Glatz Dermatology, University and University Hospital Zurich, Zurich, Switzerland Malassezia is a genus of lipophilic yeasts, currently comprising 14 species. Most of these species are isolated from healthy human skin where they thrive on sebum fatty acids. Some species are attributed a pathogenic role in skin diseases such as atopic dermatitis or seborrheic eczema, but the pathogenic mechanisms are not fully understood. Cultivation is a desirable tool to investigate disease-contributing mechanisms by enabling biochemical analysis of Malassezia species or the investigation of interaction between Malassezia and human skin immune cells. However, Malassezia species are fastidious yeasts, growing slowly (over 2-4 weeks) with limited yield. Growth efficacy is different between species, due to their complex and heterogeneous lipid metabolisms. We aimed to (i) examine the lipid preferences and (ii) to optimize culture conditions of Malassezia species. 28 strains isolated from human skin were used for the analysis. The strains represented five species with a supposed pathogenic role in skin diseases: M. sympodialis, M. restricta, M. globosa, M. slooffiae and M. furfur. Species identity was confirmed by sequencing. Strains were plated on various agar media (Leeming Notman, Sabouraud Dextrose, Tween 60-Esculin, Cremofur EL, mDixon) to determine their media preferences. To assess lipid preferences, commonly used culture media components (e.g., tweens, olive oil, oleic acid) and human sebum components (e.g. squalene, cholesterol) were added in varying concentrations. The mono-unsaturated lipid, oleic acid was the single most effective lipid to improve growth of all investigated Malassezia species. Other additives provided non-essential growth enhancement. Incubation time could be shortened to 2-4 days (versus 2-4 weeks) with only slight differences between species. In summary, we optimized media formulations for the cultivation of common Malassezia species with reduced cultivation time and increased efficiency. This will improve the research methods on the pathogenic role of Malassezia in skin diseases.