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TCAIM Decreases T Cell Priming Capacity of Dendritic Cells by Inhibiting TLR-Induced Ca 2+ Influx and IL-2 Production This information is current as Simone Z. Vogel, Stephan Schlickeiser, Karsten Jürchott, of October 1, 2021. Levent Akyuez, Julia Schumann, Christine Appelt, Katrin Vogt, Martina Schröder, Martin Vaeth, Friederike Berberich-Siebelt, Manfred B. Lutz, Gerald Grütz and Birgit Sawitzki J Immunol 2015; 194:3136-3146; Prepublished online 6 March 2015; Downloaded from doi: 10.4049/jimmunol.1400713 http://www.jimmunol.org/content/194/7/3136 http://www.jimmunol.org/ Supplementary http://www.jimmunol.org/content/suppl/2015/03/06/jimmunol.140071 Material 3.DCSupplemental References This article cites 52 articles, 17 of which you can access for free at: http://www.jimmunol.org/content/194/7/3136.full#ref-list-1 Why The JI? Submit online. by guest on October 1, 2021 • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2015 by The American Association of Immunologists, Inc. All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. The Journal of Immunology TCAIM Decreases T Cell Priming Capacity of Dendritic Cells by Inhibiting TLR-Induced Ca2+ Influx and IL-2 Production Simone Z. Vogel,* Stephan Schlickeiser,* Karsten Jurchott,€ † Levent Akyuez,*,† Julia Schumann,* Christine Appelt,* Katrin Vogt,* Martina Schro¨der,‡ Martin Vaeth,x Friederike Berberich-Siebelt,x Manfred B. Lutz,{ Gerald Grutz,*€ and Birgit Sawitzki*,† We previously showed that the T cell activation inhibitor, mitochondrial (Tcaim) is highly expressed in grafts of tolerance- developing transplant recipients and that the encoded protein is localized within mitochondria. In this study, we show that CD11c+ dendritic cells (DCs), as main producers of TCAIM, downregulate Tcaim expression after LPS stimulation or in vivo alloantigen challenge. LPS-stimulated TCAIM-overexpressing bone marrow–derived DC (BMDCs) have a reduced capacity to Downloaded from induce proliferation of and cytokine expression by cocultured allogeneic T cells; this is not due to diminished upregulation of MHC or costimulatory molecules. Transcriptional profiling also revealed normal LPS-mediated upregulation of the majority of genes involved in TLR signaling. However, TCAIM BMDCs did not induce Il2 mRNA expression upon LPS stimulation in comparison with Control-BMDCs. In addition, TCAIM overexpression abolished LPS-mediated Ca2+ influx and mitochondrial reactive oxygen species formation. Addition of IL-2 to BMDC–T cell cocultures restored the priming capacity of TCAIM BMDCs for cocultured allogeneic CD8+ T cells. Furthermore, BMDCs of IL-2–deficient mice showed similarly abolished LPS-induced http://www.jimmunol.org/ T cell priming as TCAIM-overexpressing wild type BMDCs. Thus, TCAIM interferes with TLR4 signaling in BMDCs and subsequently impairs their T cell priming capacity, which supports its role for tolerance induction. The Journal of Immunology, 2015, 194: 3136–3146. cell activation inhibitor, mitochondrial (Tcaim; also expressed in CD11c+ dendritic cells (DCs) and CD4+ T cells (1). known as Toag-1) is highly expressed in graft and blood Keeren et al. (3) showed that TCAIM is exclusively localized T of tolerance-developing allogeneic kidney and heart graft within mitochondria. Increasing data identified mitochondria to be recipients. In contrast, 3–5 days prior to graft rejection Tcaim crucial for innate immune signaling. West et al. (4) demonstrated by guest on October 1, 2021 mRNA is downregulated up to 10-fold in both compartments (1, that TNF receptor associated factor (TRAF6) translocates to mi- 2). TCAIM is highly conserved among different species, but no tochondria in macrophages after TLR1/2/4 stimulation. Subse- homologies to protein families of known functions were detect- quently, TRAF6 ubiquitinates the mitochondrial protein evo- able. The protein contains a mitochondrial leader sequence and lutionarily conserved signaling intermediate in Toll pathway a J-domain within the N- and C terminus, respectively. So far little (ECSIT) and thereby induces mitochondrial reactive oxygen is known about the specific function of TCAIM. It is highly species (mROS) production (4). ECSIT is involved in complex I assembly (5), which is the main producer of ROS (6). mROS potentiate MAPK signaling by inactivating MAPK phosphatases *Institute of Medical Immunology, Charite University Medicine, Berlin 13353, Ger- (7). Consequently, protein-modification by ROS can result in many; †Berlin Brandenburg Center for Regenerative Therapies, Charite University Medicine, Berlin 13353, Germany; ‡Institute of Immunology, Department of Biology, a variety of functional changes, such as activation, inactivation, or Maynooth University, National University of Ireland Maynooth, County Kildare, multimerization of proteins (8). Ireland; xDepartment of Molecular Pathology, Institute of Pathology, Julius Maxi- milians University of Wurzburg,€ Wurzburg€ 97080, Germany; and {Institute of Viro- As professional Ag-presenting cells, DCs communicate between logy and Immunobiology, Julius Maximilians University of Wurzburg,€ Wurzburg€ innate and adaptive immunity. Upon activation within the tissue, 97078, Germany they migrate to draining lymph nodes. Within the lymph nodes, Received for publication March 18, 2014. Accepted for publication January 29, 2015. DCs activate Ag-specific T cells because of their high expression This work was supported by the Deutsche Forschungsgemeinschaft (Transregio levels of costimulatory proteins (e.g., CD86, CD80), MHC class II TR52). (MHC-II) molecules and increased secretion of proinflammatory Address correspondence and reprint requests to Prof. Birgit Sawitzki, Charite Uni- cytokines (9). It has also been reported that DCs are able to versity Medicine, Augustenburger Platz 1, Berlin 13353, Germany. E-mail address: [email protected] produce IL-2 early upon TLR-mediated activation (10, 11). This The online version of this article contains supplemental material. might explain the high T cell priming capacity of DCs, because they are supposed to be the only IL-2–producing cells in the Abbreviations used in this article: AP1, activating protein-1; BMDC, bone marrow– derived DC; CPD, cell proliferation dye; CRAC, calcium release activated channel; myeloid compartment (12, 13). Il2 expression is initiated upon DC, dendritic cell; ER, endoplasmic reticulum; ESCIT, evolutionarily conserved activation of NFAT, which in turn is controlled via dephosphor- signaling intermediate in Toll pathway; MHC-II, MHC class II; mHprt, mouse hy- poxanthine phosphoribosyltransferase; moDC, monocyte-derived DC; mROS, mito- ylation by calcineurin. In DCs, calcineurin is activated by an in- + chondrial reactive oxygen species; QRT-PCR, quantitative real-time PCR; rmIL-2, creased intracellular Ca2 concentration, initiated by CD14 recombinant mouse IL-2; TCAIM, T cell activation inhibitor, mitochondrial; TMRM, signaling or Dectin-1 ligand binding (14–16). tetramethylrhodamine-methyl ester. We studied the effect of Tcaim overexpression on the priming Copyright Ó 2015 by The American Association of Immunologists, Inc. 0022-1767/15/$25.00 capacity of LPS-matured murine bone marrow–derived DCs www.jimmunol.org/cgi/doi/10.4049/jimmunol.1400713 The Journal of Immunology 3137 (TCAIM-BMDCs) as compared with control transduced BMDCs 30 min at 4˚C. Samples were measured on an LSR II (BD Biosciences) and (Control-BMDCs). We showed that LPS- but not polyinosinic- analyzed using the FlowJo software (Tree Star). polycytidylic acid (poly-IC)–stimulated TCAIM-BMDCs have Coculture: surface staining and proliferation determination. Onday5of a reduced priming capacity for both CD4+ and CD8+ T cells. coculture CPD450-labeled lymph node cells were harvested carefully. They were stained for live dead and then for surface expression of Interestingly, this was not due to reduced LPS-mediated up- CD3e, CD4, CD8a, and CD44 as described above (CD3e-FITC, CD4- regulation of MHC-II and CD86 expression or IL-6 production. Alexa Fluor 700, CD8a-allophycocyanin-Cy7, and CD44-PeCy7; all In contrast, TCAIM abolished LPS-mediated Ca2+ influx, mROS from BioLegend). Responder cell proliferation was measured by the formation and diminished Il2 expression. LPS-mediated Il2 ex- dilution of CPD450 intensity. Surface expression and proliferation was measured on an LSR Fortessa (BD Biosciences) and analyzed using pression was instrumental for the priming capacity of BMDCs. FlowJo software. Addition of IL-2 restored the LPS-induced T cell priming capacity of TCAIM-BMDCs for CD8+ T cells. Thus, TCAIM interferes Surface expression with crucial LPS-signaling steps at the mitochondria and may Splenocytes and lymph node cells collected from naive C57BL/6 mice thereby inhibit inflammation. or transplant recipient mice for sorting of DC subsets were stained for sur- face expression of a lineage mixture (CD3/CD19/CD49b/F4-80-PB),