Kimmel R.A.,University of Innsbruck |
Onder L.,Institute of Immunobiology |
Wilfinger A.,University of Innsbruck |
Ellertsdottir E.,University of Basel |
Meyer D.,University of Innsbruck
BMC Biology | Year: 2011
Background: Insulin-producing beta cells emerge during pancreas development in two sequential waves. Recently described later-forming beta cells in zebrafish show high similarity to second wave mammalian beta cells in developmental capacity. Loss-of-function studies in mouse and zebrafish demonstrated that the homeobox transcription factors Pdx1 and Hb9 are both critical for pancreas and beta cell development and discrete stage-specific requirements for these genes have been uncovered. Previously, exocrine and endocrine cell recovery was shown to follow loss of pdx1 in zebrafish, but the progenitor cells and molecular mechanisms responsible have not been clearly defined. In addition, interactions of pdx1 and hb9 in beta cell formation have not been addressed.Results: To learn more about endocrine progenitor specification, we examined beta cell formation following morpholino-mediated depletion of pdx1 and hb9. We find that after early beta cell reduction, recovery occurs following loss of either pdx1 or hb9 function. Unexpectedly, simultaneous knockdown of both hb9 and pdx1 leads to virtually complete and persistent beta cell deficiency. We used a NeuroD:EGFP transgenic line to examine endocrine cell behavior in vivo and developed a novel live-imaging technique to document emergence and migration of late-forming endocrine precursors in real time. Our data show that Notch-responsive progenitors for late-arising endocrine cells are predominantly post mitotic and depend on pdx1. By contrast, early-arising endocrine cells are specified and differentiate independent of pdx1.Conclusions: The nearly complete beta cell deficiency after combined loss of hb9 and pdx1 suggests functional cooperation, which we clarify as distinct roles in early and late endocrine cell formation. A novel imaging approach permitted visualization of the emergence of late endocrine cells within developing embryos for the first time. We demonstrate a pdx1-dependent progenitor population essential for the formation of duct-associated, second wave endocrine cells. We further reveal an unexpectedly low mitotic activity in these progenitor cells, indicating that they are set aside early in development. © 2011 Kimmel et al; licensee BioMed Central Ltd.
PubMed | Institute of Immunobiology, Novartis, Russian Academy of Sciences, University of Bern and Genentech
Type: Journal Article | Journal: PLoS biology | Year: 2016
Fibroblastic reticular cells (FRCs) form the cellular scaffold of lymph nodes (LNs) and establish distinct microenvironmental niches to provide key molecules that drive innate and adaptive immune responses and control immune regulatory processes. Here, we have used a graph theory-based systems biology approach to determine topological properties and robustness of the LN FRC network in mice. We found that the FRC network exhibits an imprinted small-world topology that is fully regenerated within 4 wk after complete FRC ablation. Moreover, in silico perturbation analysis and in vivo validation revealed that LNs can tolerate a loss of approximately 50% of their FRCs without substantial impairment of immune cell recruitment, intranodal T cell migration, and dendritic cell-mediated activation of antiviral CD8+ T cells. Overall, our study reveals the high topological robustness of the FRC network and the critical role of the network integrity for the activation of adaptive immune responses.
Onder L.,Institute of Immunobiology |
Narang P.,University of York |
Scandella E.,Institute of Immunobiology |
Chai Q.,Institute of Immunobiology |
And 9 more authors.
Blood | Year: 2012
Nonhematopoietic stromal cells of secondary lymphoid organs form important scaffold and fluid transport structures, such as lymph node (LN) trabeculae, lymph vessels, and conduits. Furthermore, through the production of chemokines and cytokines, these cells generate a particular microenvironment that determines lymphocyte positioning and supports lymphocyte homeostasis. IL-7 is an important stromal cell-derived cytokine that has been considered to be derived mainly from T-cell zone fibroblastic reticular cells. We show here that lymphatic endothelial cells (LECs) are a prominent source of IL-7 both in human and murine LNs. Using bacterial artificial chromosome transgenic IL-7-Cre mice, we found that fibroblastic reticular cells and LECs strongly up-regulated IL-7 expression during LN remodeling after viral infection and LN reconstruction after avascular transplantation. Furthermore, IL-7-producing stromal cells contributed to de novo formation of LyveI-positive lymphatic structures connecting reconstructed LNs with the surrounding tissue. Importantly, diphtheria toxin-mediated depletion of IL-7-producing stromal cells completely abolished LN reconstruction. Taken together, this study identifies LN LECs as a major source of IL-7 and shows that IL-7-producing stromal cells are critical for reconstruction and remodeling of the distinct LN microenvironment. © 2012 by The American Society of Hematology.
Habjan M.,Max Planck Institute of Biochemistry |
Hubel P.,Max Planck Institute of Biochemistry |
Lacerda L.,Max Planck Institute of Biochemistry |
Benda C.,Max Planck Institute of Biochemistry |
And 9 more authors.
PLoS Pathogens | Year: 2013
Viruses that generate capped RNA lacking 2′O methylation on the first ribose are severely affected by the antiviral activity of Type I interferons. We used proteome-wide affinity purification coupled to mass spectrometry to identify human and mouse proteins specifically binding to capped RNA with different methylation states. This analysis, complemented with functional validation experiments, revealed that IFIT1 is the sole interferon-induced protein displaying higher affinity for unmethylated than for methylated capped RNA. IFIT1 tethers a species-specific protein complex consisting of other IFITs to RNA. Pulsed stable isotope labelling with amino acids in cell culture coupled to mass spectrometry as well as in vitro competition assays indicate that IFIT1 sequesters 2′O-unmethylated capped RNA and thereby impairs binding of eukaryotic translation initiation factors to 2′O-unmethylated RNA template, which results in inhibition of translation. The specificity of IFIT1 for 2′O-unmethylated RNA serves as potent antiviral mechanism against viruses lacking 2′O-methyltransferase activity and at the same time allows unperturbed progression of the antiviral program in infected cells. © 2013 Habjan et al.
Carbajo-Lozoya J.,Max Von Pettenkofer Institute |
Muller M.A.,University of Bonn |
Kallies S.,University of Bonn |
Thiel V.,Institute of Immunobiology |
And 3 more authors.
Virus Research | Year: 2012
Recent research has shown that Coronavirus (CoV) replication depends on active immunophilin pathways. Here we demonstrate that the drug FK506 (Tacrolimus) inhibited strongly the growth of human coronaviruses SARS-CoV, HCoV-NL63 and HCoV-229E at low, non-cytotoxic concentrations in cell culture. As shown by plaque titration, qPCR, Luciferase- and green fluorescent protein (GFP) reporter gene expression, replication was diminished by several orders of magnitude. Knockdown of the cellular FK506-binding proteins FKBP1A and FKBP1B in CaCo2 cells prevented replication of HCoV-NL63, suggesting the requirement of these members of the immunophilin family for virus growth. © 2012 Elsevier B.V.
PubMed | Institute of Immunobiology, University of Zürich and Johannes Gutenberg University Mainz
Type: | Journal: eLife | Year: 2016
T cells contribute to first line immune defense, particularly through their ability for rapid production of proinflammatory cytokines. The cytokine profile of T cells is hard-wired already during thymic development. Yet, the molecular pathways underlying this phenomenon are incompletely understood. Here we show that signaling via the NFB-inducing kinase (NIK) is essential for the formation of a fully functional T cell compartment. In the absence of NIK, development of V5(+) dendritic epidermal T cells (DETCs) was halted in the embryonic thymus, and impaired NIK function caused a selective loss of IL-17 expression by T cells. Using a novel conditional mutant of NIK, we could show in vivo that NIK signaling in thymic epithelial cells is essential for the thymic hardwiring of T cell cytokine production.
Dubey L.,Ecole Polytechnique Federale de Lausanne |
Lebon L.,Ecole Polytechnique Federale de Lausanne |
Mosconi I.,Ecole Polytechnique Federale de Lausanne |
Yang C.-Y.,University of Lausanne |
And 4 more authors.
Cell Reports | Year: 2016
Secondary lymphoid tissues provide specialized niches for the initiation of adaptive immune responses and undergo a remarkable expansion in response to inflammatory stimuli. Although the formation of B cell follicles was previously thought to be restricted to the postnatal period, we observed that the draining mesenteric lymph nodes (mLN) of helminth-infected mice form an extensive number of new, centrally located, B cell follicles in response to IL-4Rα-dependent inflammation. IL-4Rα signaling promoted LTα1β2 (lymphotoxin) expression by B cells, which then interacted with CCL19 positive stromal cells to promote lymphoid enlargement and the formation of germinal center containing B cell follicles. Importantly, de novo follicle formation functioned to promote both total and parasite-specific antibody production. These data reveal a role for type 2 inflammation in promoting stromal cell remodeling and de novo follicle formation by promoting B cell-stromal cell crosstalk. Intestinal helminth infection drives type 2 immune responses in the draining mLN. Dubey et al. demonstrate in mice that type 2 inflammation drives lymphoid remodeling resulting from lymphotoxin-dependent crosstalk between B cells and FRCs. Such crosstalk promotes de novo follicle formation and supports the production of parasite-specific antibodies. © 2016 The Authors.
Perez-Shibayama C.,Institute of Immunobiology |
Gil-Cruz C.,Institute of Immunobiology |
Ludewig B.,Institute of Immunobiology
Immunology Letters | Year: 2015
Vaccines against acute infections execute their protective effects almost exclusively via the induction of antibodies. Development of protective vaccines against persisting pathogens lags behind probably because standard immunogens and application regimen do not sufficiently stimulate those circuits in B cell activation that mediate protection. In general, B cell responses against pathogen derived-antigens are generated through complex cellular interactions requiring the coordination of innate and adaptive immune mechanisms. In this review, we summarize recent findings from prototypic infection models to exemplify how generation of protective antibodies against persisting pathogens is imprinted by particular pathogen-derived factors and how distinct CD4+ T cell populations determine the quality of these antibodies. Clearly, it is the high plasticity of these processes that is instrumental to drive tailored B cell responses that protect the host. In sum, application of novel knowledge on B cell plasticity and complexity can guide the development of rationally designed vaccines that elicit protective antibodies against persisting pathogens. © 2014 Elsevier B.V.
Firner S.,Institute of Immunobiology |
Onder L.,Institute of Immunobiology |
Nindl V.,Institute of Immunobiology |
Ludewig B.,Institute of Immunobiology
Frontiers in Immunology | Year: 2012
Vascular endothelial cells (ECs) form the inner layer of blood vessels and exert crucial functions during immune reactions including coagulation, inflammation, and regulation of innate immunity. Importantly, ECs can interact with T cells in an antigen-specific, i.e., T cell receptor-dependent manner. In this review, we will discuss EC actions and reactions during acute inflammation and focus on the interaction of T cells with ECs at two vascular sites: the high endothelial venule (HEV) of lymph nodes, and the vascular lesion during transplant vasculopathy (TV). HEVs are characterized by a highly active endothelium that produces chemoattracting factors and expresses adhesion molecules to facilitate transit of lymphocytes into the lymph node (LN) parenchyma .Yet, T cell-EC interaction at this anatomical location results neither inT cell activation nor tolerization. In contrast, the endothelium at sites of chronic inflammation, such as solid organ transplants, can promote T cell activation by upregulation of major histocompatibility complex (MHC) and costimulatory molecules. Importantly, a major function of ECs in inflamed tissues must be the maintenance of vascular integrity including the efficient attenuation of effectorT cells that may damage the vascular bed.Thus, antigen-specificT cell-EC interaction is characterized by a tightly controlled balance between immunological ignorance, immune activation, and tolerization. © 2012 Firner, Onder, Nindl and Ludewig.
PubMed | Institute of Immunobiology
Type: | Journal: Methods in molecular biology (Clifton, N.J.) | Year: 2016
Vaccination with a recombinant LCMV based vector expressing tumor-associated or viral antigens is a safe and versatile method to induce an immune response against tumors or viral infections. Here, we describe the generation of recombinant LCMV vectors in which the gene encoding the viral LCMV-GP was substituted with a gene of interest (vaccine antigen). This renders the vaccine vector propagation-incompetent while it preserves the property of eliciting a strong cytotoxic T cell response.