Event Abstract Back to Event Does citrullination occur in medullary thymic epithelial cells? Robby Engelmann1*, Andra Biemelt1, Anja Johl1 and Brigitte Müller-Hilke1 1 University Medicine Rostock, Institute of Immunology, Germany Introduction The presence of antibodies against citrullinated peptide antigens (ACPA) is a hallmark of rheumatoid arthritis. However, it is unclear how these autoantibodies develop. It has been proposed, that peripheral citrullination generates neoepitopes that are favored targets of autoreactive immune cells evading central tolerance induction. We investigated the expression of peptidyl arginine deiminases (PAD) in medullary thymic epithelial cells (mTEC). Methods Thymic epithelial cells were isolated from 4-5 weeks old mice susceptible (DBA/1) or not susceptible (NMRI, C57BL/6) for collagen-induced arthritis (CIA). After TEC-enrichment by percoll density gradient centrifugation and magnetic depletion of CD45+ cells, immature mTEC (CD45-EpCAM+CD80lowLy-51-) and mature mTEC (CD45-EpCAM+CD80highLy-51-) were FACS-sorted. Cortical TEC were identified as CD45-EpCAM+CD80-Ly-51+. mRNA and protein were isolated from sorted mTEC populations for subsequent expression analysis. Results Flow cytometry analysis revealed a significantly decreased number of mTEC in thymi of CIA-susceptible DBA/1 mice in comparison to NMRI and C57BL/6 mice, whereas the number of T cells and cTEC did not show any differences. Subsequent quantitative PCR confirmed cell identity since mature mTEC showed significantly elevated expression of aire and the tissue restricted gene insulin2 compared to immature ones. Pad expression was higher in mature mTEC compared to immature mTEC and correlated well with the expression of aire. Furthermore, the expression of pad6 was significantly elevated in DBA/1 mature mTEC. Conclusion Pad genes are readily expressed at RNA level in murine mTEC. However, it remains to be determined whether PAD protein and citrullination can also be found in mTEC. This is work in progress. Keywords: citrullination, neoepitopes, collagen-induced arthritis, Central Tolerance, Thymus Gland Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Immune-mediated disease pathogenesis Citation: Engelmann R, Biemelt A, Johl A and Müller-Hilke B (2013). Does citrullination occur in medullary thymic epithelial cells?. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00674 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 12 Jun 2013; Published Online: 22 Aug 2013. * Correspondence: Dr. Robby Engelmann, University Medicine Rostock, Institute of Immunology, Rostock, Germany, robby.engelmann@med.uni-rostock.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Robby Engelmann Andra Biemelt Anja Johl Brigitte Müller-Hilke Google Robby Engelmann Andra Biemelt Anja Johl Brigitte Müller-Hilke Google Scholar Robby Engelmann Andra Biemelt Anja Johl Brigitte Müller-Hilke PubMed Robby Engelmann Andra Biemelt Anja Johl Brigitte Müller-Hilke Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.