Publications by authors named "Hans-Reimer Rodewald"

99 Publications

Transcription factor hijacking in the name of tolerance.

Cell 2022 07;185(14):2398-2400

Division of Cellular Immunology, German Cancer Research Center, D-69120 Heidelberg, Germany. Electronic address:

Thymus epithelial cells (TECs) express antigens from peripheral tissues to select against autoreactive T cells and thus prevent autoimmunity. Michelsen et al. now show that molecularly defined clusters of thymic epithelial cells express and depend on skin-, lung-, liver- or intestinal-cell transcription factors that are co-opted by the thymus to drive ectopic gene expression.
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http://dx.doi.org/10.1016/j.cell.2022.06.026DOI Listing
July 2022

Chlorine exposure and intensive exercise induces airway hyperreactivity in a 3-week murine exercise model.

Sci Total Environ 2022 Jun 30;843:157046. Epub 2022 Jun 30.

KU Leuven, Department of Public Health and Primary Care, Centre for Environment and Health, Herestraat 49 box 952, 3000 Leuven, Belgium. Electronic address:

Rationale: Exercise-induced bronchoconstriction (EIB) is defined as acute narrowing of the airways during or immediately after exercise. EIB has a high prevalence in elite swimmers probably due to the high ventilation rate and exposure to the chlorine by-products. It is still puzzling which pathophysiological mechanisms drive EIB.

Objective: In this study, we evaluated airway hyperreactivity, permeability, integrity and inflammation in a murine swimmers EIB model with and without chlorine exposure.

Methods: Mice performed a 3-week swimming protocol in a swimming pool with counter current. Three hours after the last swimming session, airway hyperreactivity to methacholine was assessed. Cytokine levels and cellular differential analysis was performed in BAL fluid. Airway permeability and tight junction expression was measured in serum and lung tissue. T-, B-, dendritic and innate lymphoid cells were determined in lung tissue via flow cytometry.

Results: A significant higher airway resistance (Rn; P < 0.0001) was observed in mice swimming in chlorinated water (mean Rn = 1.26 cmHO.s/ml) compared to mice swimming in tap water (mean Rn = 0.76 cmHO.s/ml) and both inhalation groups in the absence of cellular inflammation. No significant differences were found in lung immune cell populations or in lung tight junction mRNA expression. Experiments in SCID, Rag2γc or Cpa3 mice showed a limited involvement of the innate, adaptive immune system or the mast cells.

Conclusion: Our 3-week swimming murine model mimics intensive swimming in chlorinated water with the presence of airway hyperreactivity in mice swimming in chlorinated water in the absence of airway inflammation and airway epithelial damage.
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http://dx.doi.org/10.1016/j.scitotenv.2022.157046DOI Listing
June 2022

Toward the dissection of hematopoietic stem cell fates and their determinants.

Curr Opin Genet Dev 2022 Aug 24;75:101945. Epub 2022 Jun 24.

Division of Cellular Immunology, German Cancer Research Center, D-69120 Heidelberg, Germany. Electronic address:

Hematopoietic stem cell (HSC) functions have long been difficult to study under physiological conditions. Recently, genetic in vivo approaches have been developed for lineage tracing of differentiating progeny emerging from HSC over time (output), and for high-resolution, endogenous barcoding to uncover the lineages that HSC contribute to (fate). Such fate measurements have in principle led to the recognition of three major fate groups of HSC: multilineage, myelo-erythroid-restricted, and inactive, that is, no or no known progeny, in addition to a minor group of megakaryocyte-restricted HSC. The most recent RNA-barcoding experiments have begun to directly link fate measurements with transcriptome reading in HSC clones and single HSC, which yielded insights into transcriptional signatures associated with fate patterns. Here, we discuss these findings in light of the structure of the hematopoietic differentiation hierarchy, and we provide an outlook on strategies to dissect molecular determinants of HSC fates.
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http://dx.doi.org/10.1016/j.gde.2022.101945DOI Listing
August 2022

Eosinophils are an essential element of a type 2 immune axis that controls thymus regeneration.

Sci Immunol 2022 03 11;7(69):eabn3286. Epub 2022 Mar 11.

Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK.

Therapeutic interventions used for cancer treatment provoke thymus damage and limit the recovery of protective immunity. Here, we show that eosinophils are an essential part of an intrathymic type 2 immune network that enables thymus recovery after ablative therapy. Within hours of damage, the thymus undergoes CCR3-dependent colonization by peripheral eosinophils, which reestablishes the epithelial microenvironments that control thymopoiesis. Eosinophil regulation of thymus regeneration occurs via the concerted action of NKT cells that trigger CCL11 production via IL4 receptor signaling in thymic stroma, and ILC2 that represent an intrathymic source of IL5, a cytokine that therapeutically boosts thymus regeneration after damage. Collectively, our findings identify an intrathymic network composed of multiple innate immune cells that restores thymus function during reestablishment of the adaptive immune system.
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http://dx.doi.org/10.1126/sciimmunol.abn3286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7612579PMC
March 2022

Runner's niche: multipurpose stromal cells maintained by exercise.

Trends Immunol 2021 10 31;42(10):841-843. Epub 2021 Aug 31.

Division of Cellular Immunology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany. Electronic address:

Using newly developed reporter and lineage-tracing mice, Shen et al. found perivascular stromal cells coexpressing osteolectin and leptin receptor in the bone marrow that specifically supported lymphoid progenitors, served as osteoblast progenitors, and were maintained by mechanical stimulation. Exercise may thus have joint positive influences on lymphopoiesis and bone formation.
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http://dx.doi.org/10.1016/j.it.2021.08.007DOI Listing
October 2021

Comparative analysis of the role of mast cells in murine asthma models using Kit-sufficient mast cell-deficient animals.

Allergy 2021 07 9;76(7):2030-2043. Epub 2021 Mar 9.

Institute of Molecular Health Sciences, ETH Zurich, Zurich, Switzerland.

Background: Asthma is a frequent chronic disease that can potentially severely affect the respiratory capacity and well-being of patients. Mast cells (MCs) are regarded as major players in human asthma due to their capacity to release crucial inflammatory mediators following allergen exposure. However, unambiguous characterization of their role in animal models has long been hindered by the unavailability of specific MC-deficient models lacking confounding MC-unrelated effects. This study aims to examine the role of MCs in Kit-sufficient MC-deficient Cpa3 mice.

Methods: We used a variety of models of acute and chronic asthma employing distinct routes and regimes of sensitization. These sensitizations were done via the peritoneal cavity, the skin, or the lung. Additionally, different allergens, i.e. ovalbumin and house dust mite extract, were used.

Results: Our results show that the absence of MCs had no impact on the severity of allergic airway inflammation in any of the tested mouse models, as measured by leukocyte infiltration in the airways, cytokine expression, antibody production, airway hyper-responsiveness and mucus production.

Conclusion: This indicates that MCs do not play a major role in murine allergic airway inflammation.
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http://dx.doi.org/10.1111/all.14765DOI Listing
July 2021

Mast cell-derived serotonin enhances methacholine-induced airway hyperresponsiveness in house dust mite-induced experimental asthma.

Allergy 2021 07 9;76(7):2057-2069. Epub 2021 Mar 9.

Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.

Background: Airway hyperresponsiveness (AHR) is a feature of asthma in which airways are hyperreactive to stimuli causing extensive airway narrowing. Methacholine provocations assess AHR in asthma patients mainly by direct stimulation of smooth muscle cells. Using in vivo mouse models, mast cells have been implicated in AHR, but the mechanism behind has remained unknown.

Methods: Cpa3 mice, which lack mast cells, were used to assess the role of mast cells in house dust mite (HDM)-induced experimental asthma. Effects of methacholine in presence or absence of ketanserin were assessed on lung function and in lung mast cells in vitro. Airway inflammation, mast cell accumulation and activation, smooth muscle proliferation, and HDM-induced bronchoconstriction were evaluated.

Results: Repeated intranasal HDM sensitization induced allergic airway inflammation associated with accumulation and activation of lung mast cells. Lack of mast cells, absence of activating Fc-receptors, or antagonizing serotonin (5-HT) receptors abolished HDM-induced trachea contractions. HDM-sensitized mice lacking mast cells had diminished lung-associated 5-HT levels, reduced AHR and methacholine-induced airway contraction, while blocking 5-HT receptors in wild types eliminated AHR, implying that mast cells contribute to AHR by releasing 5-HT. Primary mouse and human lung mast cells express muscarinic M3 receptors. Mouse lung mast cells store 5-HT intracellularly, and methacholine induces release of 5-HT from lung-derived mouse mast cells and Ca flux in human LAD-2 mast cells.

Conclusions: Methacholine activates mast cells to release 5-HT, which by acting on 5-HT receptors enhances bronchoconstriction and AHR. Thus, M3-directed asthma treatments like tiotropium may also act by targeting mast cells.
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http://dx.doi.org/10.1111/all.14748DOI Listing
July 2021

Local immune response to food antigens drives meal-induced abdominal pain.

Nature 2021 02 13;590(7844):151-156. Epub 2021 Jan 13.

Laboratory of Immunoregulation, VIB Center for Inflammation Research, Ghent, Belgium.

Up to 20% of people worldwide develop gastrointestinal symptoms following a meal, leading to decreased quality of life, substantial morbidity and high medical costs. Although the interest of both the scientific and lay communities in this issue has increased markedly in recent years, with the worldwide introduction of gluten-free and other diets, the underlying mechanisms of food-induced abdominal complaints remain largely unknown. Here we show that a bacterial infection and bacterial toxins can trigger an immune response that leads to the production of dietary-antigen-specific IgE antibodies in mice, which are limited to the intestine. Following subsequent oral ingestion of the respective dietary antigen, an IgE- and mast-cell-dependent mechanism induced increased visceral pain. This aberrant pain signalling resulted from histamine receptor H-mediated sensitization of visceral afferents. Moreover, injection of food antigens (gluten, wheat, soy and milk) into the rectosigmoid mucosa of patients with irritable bowel syndrome induced local oedema and mast cell activation. Our results identify and characterize a peripheral mechanism that underlies food-induced abdominal pain, thereby creating new possibilities for the treatment of irritable bowel syndrome and related abdominal pain disorders.
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http://dx.doi.org/10.1038/s41586-020-03118-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7610810PMC
February 2021

Duodenal acidification induces gastric relaxation and alters epithelial barrier function by a mast cell independent mechanism.

Sci Rep 2020 10 15;10(1):17448. Epub 2020 Oct 15.

Translational Research Center for Gastrointestinal Disorders, Department of Chronic Diseases, Metabolism and Ageing, KU Leuven, Herestraat 49, Box 701, 3000, Leuven, Belgium.

Duodenal hyperpermeability and low-grade inflammation in functional dyspepsia is potentially related to duodenal acid exposure. We aimed to evaluate in healthy volunteers the involvement of mast cell activation on the duodenogastric reflex and epithelial integrity during duodenal acidification. This study consisted of 2 parts: (1) Duodenal infusion of acid or saline during thirty minutes in a randomized, double-blind cross-over manner with measurement of intragastric pressure (IGP) using high resolution manometry and collection of duodenal biopsies to measure epithelial barrier function and the expression of cell-to-cell adhesion proteins. Mast cells and eosinophils were counted and activation and degranulation status were assessed. (2) Oral treatment with placebo or mast cell stabilizer disodiumcromoglycate (DSCG) prior to duodenal perfusion with acid, followed by the procedures described above. Compared with saline, acidification resulted in lower IGP (P < 0.01), increased duodenal permeability (P < 0.01) and lower protein expression of claudin-3 (P < 0.001). Protein expression of tryptase (P < 0.001) was increased after acid perfusion. Nevertheless, an ultrastructural examination did not reveal degranulation of mast cells. DSCG did not modify the drop in IGP and barrier dysfunction induced by acid. Duodenal acidification activates an inhibitory duodenogastric motor reflex and, impairs epithelial integrity in healthy volunteers. However, these acid mediated effects occur independently from mast cell activation.
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http://dx.doi.org/10.1038/s41598-020-74491-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7562901PMC
October 2020

Resolving Fates and Single-Cell Transcriptomes of Hematopoietic Stem Cell Clones by PolyloxExpress Barcoding.

Cell Stem Cell 2020 09 11;27(3):383-395.e8. Epub 2020 Aug 11.

Division of Cellular Immunology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany. Electronic address:

Lineage tracing reveals hematopoietic stem cell (HSC) fates, while single-cell RNA sequencing identifies snapshots of HSC transcriptomes. To obtain information on fate plus transcriptome in the same cell, we developed the PolyloxExpress allele, enabling Cre-recombinase-dependent RNA barcoding in situ. Linking fates to single HSC transcriptomes provided the information required to identify transcriptional signatures of HSC fates, which were not apparent in single-HSC transcriptomes alone. We find that differentiation-inactive, multilineage, and lineage-restricted HSC clones reside in distinct regions of the transcriptional landscape of hematopoiesis. Differentiation-inactive HSC clones are closer to the origin of the transcriptional trajectory, yet they are not characterized by a quiescent gene signature. Fate-specific gene signatures imply coherence of clonal HSC fates, and HSC output toward short-lived lineage progenitors indicates stability of HSC fates over time. These combined analyses of fate and transcriptome under physiological conditions may pave the way toward identifying molecular determinants of HSC fates.
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http://dx.doi.org/10.1016/j.stem.2020.07.018DOI Listing
September 2020

ILC2-driven innate immune checkpoint mechanism antagonizes NK cell antimetastatic function in the lung.

Nat Immunol 2020 09 3;21(9):998-1009. Epub 2020 Aug 3.

CRUK Cambridge Institute, University of Cambridge, Cambridge, UK.

Metastasis constitutes the primary cause of cancer-related deaths, with the lung being a commonly affected organ. We found that activation of lung-resident group 2 innate lymphoid cells (ILC2s) orchestrated suppression of natural killer (NK) cell-mediated innate antitumor immunity, leading to increased lung metastases and mortality. Using multiple models of lung metastasis, we show that interleukin (IL)-33-dependent ILC2 activation in the lung is involved centrally in promoting tumor burden. ILC2-driven innate type 2 inflammation is accompanied by profound local suppression of interferon-γ production and cytotoxic function of lung NK cells. ILC2-dependent suppression of NK cells is elaborated via an innate regulatory mechanism, which is reliant on IL-5-induced lung eosinophilia, ultimately limiting the metabolic fitness of NK cells. Therapeutic targeting of IL-33 or IL-5 reversed NK cell suppression and alleviated cancer burden. Thus, we reveal an important function of IL-33 and ILC2s in promoting tumor metastasis via their capacity to suppress innate type 1 immunity.
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http://dx.doi.org/10.1038/s41590-020-0745-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116357PMC
September 2020

Interleukin-33 Induces the Enzyme Tryptophan Hydroxylase 1 to Promote Inflammatory Group 2 Innate Lymphoid Cell-Mediated Immunity.

Immunity 2020 04 10;52(4):606-619.e6. Epub 2020 Mar 10.

Jill Roberts Institute for Research in Inflammatory Bowel Disease, Joan and Sanford I. Weill Department of Medicine, Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, New York, NY 10021, USA. Electronic address:

Group 2 innate lymphoid cells (ILC2s) regulate immunity, inflammation, and tissue homeostasis. Two distinct subsets of ILC2s have been described: steady-state natural ILC2s and inflammatory ILC2s, which are elicited following helminth infection. However, how tissue-specific cues regulate these two subsets of ILC2s and their effector functions remains elusive. Here, we report that interleukin-33 (IL-33) promotes the generation of inflammatory ILC2s (ILC2) via induction of the enzyme tryptophan hydroxylase 1 (Tph1). Tph1 expression was upregulated in ILC2s upon activation with IL-33 or following helminth infection in an IL-33-dependent manner. Conditional deletion of Tph1 in lymphocytes resulted in selective impairment of ILC2 responses and increased susceptibility to helminth infection. Further, RNA sequencing analysis revealed altered gene expression in Tph1 deficient ILC2s including inducible T cell co-stimulator (Icos). Collectively, these data reveal a previously unrecognized function for IL-33, Tph1, and ICOS in promoting inflammatory ILC2 responses and type 2 immunity at mucosal barriers.
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http://dx.doi.org/10.1016/j.immuni.2020.02.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7218677PMC
April 2020

Targeted deletion of the TSLP receptor reveals cellular mechanisms that promote type 2 airway inflammation.

Mucosal Immunol 2020 07 17;13(4):626-636. Epub 2020 Feb 17.

Jill Roberts Institute for Research in Inflammatory Bowel Disease, Friedman Center for Nutrition and Inflammation, Joan and Sanford I. Weill Department of Medicine, Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, New York, NY, 10021, USA.

Thymic stromal lymphopoietin (TSLP) is a critical upstream cytokine inducing type 2 inflammation in various diseases, including asthma and atopic dermatitis. Accumulating evidence suggests that TSLP can directly stimulate a variety of immune cells, such as dendritic cells (DCs), basophils, T cells, and group 2 innate lymphoid cells (ILC2s). However, which cell types directly respond to TSLP in vivo and how TSLP initiates type 2 inflammation has remained controversial. To define the precise role of TSLP in vivo, for the first time we generated multiple cell lineage-specific TSLP receptor-deficient mice to systematically dissect the cell-intrinsic requirements for TSLP responsiveness in type 2 inflammation in the lung. In papain-induced innate immune-mediated type 2 airway inflammation, TSLP directly stimulated ILC2s, but not basophils, leading to enhanced type 2 inflammation. On the other hand, in OVA-induced adaptive immune-mediated type 2 airway inflammation, TSLP principally acted on DCs and CD4 + T cells during the sensitization phase, but not basophils or ILC2s, and facilitated the development of Th2 cell-mediated airway inflammation. Together, these findings reveal that TSLP activates distinct immune cell cascades in the context of innate and adaptive immune-mediated type 2 inflammation.
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http://dx.doi.org/10.1038/s41385-020-0266-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311324PMC
July 2020

Human Mast Cell Proteome Reveals Unique Lineage, Putative Functions, and Structural Basis for Cell Ablation.

Immunity 2020 02 11;52(2):404-416.e5. Epub 2020 Feb 11.

Division for Cellular Immunology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany. Electronic address:

Mast cells are rare tissue-resident cells of importance to human allergies. To understand the structural basis of principle mast cell functions, we analyzed the proteome of primary human and mouse mast cells by quantitative mass spectrometry. We identified a mast-cell-specific proteome signature, indicative of a unique lineage, only distantly related to other immune cell types, including innate immune cells. Proteome comparison between human and mouse suggested evolutionary conservation of core mast cell functions. In addition to specific proteases and proteins associated with degranulation and proteoglycan biosynthesis, mast cells expressed proteins potentially involved in interactions with neurons and neurotransmitter metabolism, including cell adhesion molecules, ion channels, and G protein coupled receptors. Toward targeted cell ablation in severe allergic diseases, we used MRGPRX2 for mast cell depletion in human skin biopsies. These proteome analyses suggest a unique role of mast cells in the immune system, probably intertwined with the nervous system.
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http://dx.doi.org/10.1016/j.immuni.2020.01.012DOI Listing
February 2020

Do haematopoietic stem cells age?

Nat Rev Immunol 2020 03 18;20(3):196-202. Epub 2019 Nov 18.

Division of Cellular Immunology, German Cancer Research Center, Heidelberg, Germany.

Genetic defects that accumulate in haematopoietic stem cells (HSCs) are thought to be responsible for age-related changes in haematopoiesis that include a decline in lymphopoiesis and skewing towards the myeloid lineage. This HSC-centric view is based largely on studies showing that HSCs from aged mice exhibit these lineage biases following transplantation into irradiated young recipient mice. In this Opinion article, we make the case that the reliance on this approach has led to inaccurate conclusions regarding the effects of ageing on blood-forming stem cells; we suggest instead that changes in the environment contribute to haematopoietic system ageing. We propose that a complete understanding of how ageing affects haematopoiesis depends on the analysis of blood cell production in unperturbed mice. We describe how this can be achieved using in situ fate mapping. This approach indicates that changes in downstream progenitors, in addition to any HSC defects, may explain the reduced lymphopoiesis and sustained myelopoiesis that occur during ageing.
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http://dx.doi.org/10.1038/s41577-019-0236-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7879798PMC
March 2020

Using Cre-recombinase-driven Polylox barcoding for in vivo fate mapping in mice.

Nat Protoc 2019 06 20;14(6):1820-1840. Epub 2019 May 20.

Division of Cellular Immunology, German Cancer Research Center, Heidelberg, Germany.

Fate mapping is a powerful genetic tool for linking stem or progenitor cells with their progeny, and hence for defining cell lineages in vivo. The resolution of fate mapping depends on the numbers of distinct markers that are introduced in the beginning into stem or progenitor cells; ideally, numbers should be sufficiently large to allow the tracing of output from individual cells. Highly diverse genetic barcodes can serve this purpose. We recently developed an endogenous genetic barcoding system, termed Polylox. In Polylox, random DNA recombination can be induced by transient activity of Cre recombinase in a 2.1-kb-long artificial recombination substrate that has been introduced into a defined locus in mice (Rosa26 reporter mice). Here, we provide a step-by-step protocol for the use of Polylox, including barcode induction and estimation of induction efficiency, barcode retrieval with single-molecule real-time (SMRT) DNA sequencing followed by computational barcode identification, and the calculation of barcode-generation probabilities, which is key for estimations of single-cell labeling for a given number of stem cells. Thus, Polylox barcoding enables high-resolution fate mapping in essentially all tissues in mice for which inducible Cre driver lines are available. Alternative methods include ex vivo cell barcoding, inducible transposon insertion and CRISPR-Cas9-based barcoding; Polylox currently allows combining non-invasive and cell-type-specific labeling with high label diversity. The execution time of this protocol is ~2-3 weeks for experimental data generation and typically <2 d for computational Polylox decoding and downstream analysis.
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http://dx.doi.org/10.1038/s41596-019-0163-5DOI Listing
June 2019

Unimpaired Responses to Vaccination With Protein Antigen Plus Adjuvant in Mice With Kit-Independent Mast Cell Deficiency.

Front Immunol 2018 28;9:1870. Epub 2018 Aug 28.

Medical Faculty Carl Gustav Carus, Institute for Immunology, University of Technology Dresden, Dresden, Germany.

Innate inflammatory responses are crucial for induction and regulation of T cell and antibody responses. Mast cell (MC)-deficient mutant mice showed impaired adaptive immunity, suggesting that MCs provide essential adjuvant activities, and pharmacological MC activation was proposed as a new adjuvant principle. However, the mutations result in complex alterations of the immune system in addition to MC deficiency. We revisited the role of MCs in vaccination responses using and mice that lack connective tissue MCs or all MCs, respectively, but feature an otherwise normal immune system. These animals showed no impairment of T and B cell responses to intradermal vaccination with protein antigen plus complete Freund's adjuvant. Moreover, we demonstrate that the adjuvant effects of the MC secretagogue c48/80 in intradermal or mucosal immunization are independent of the presence of MCs. We hence find no evidence for a regulation by MCs of adaptive immune responses to protein antigens. The finding that immunological MC functions differ from those suggested by experiments in mutants, emphasizes the importance of rigorous tests in Kit-independent MC-deficiency models.
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http://dx.doi.org/10.3389/fimmu.2018.01870DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123530PMC
September 2019

Differentiation-based model of hematopoietic stem cell functions and lineage pathways.

Blood 2018 09 24;132(11):1106-1113. Epub 2018 Jul 24.

Division of Cellular Immunology, German Cancer Research Center, Heidelberg, Germany.

Advances in genetic labeling and barcoding of hematopoietic stem cells (HSCs) in situ now allow direct measurements of physiological HSC output, both quantitatively and qualitatively. Turning on a heritable label in HSCs and measuring the kinetics of label emergence in downstream compartments reveal rates of differentiation and self-renewal of HSCs and progenitor cells, whereas endogenous HSC barcoding probes physiological precursor-product relationships. Labels have been inserted at different stages of the hematopoietic differentiation hierarchy. Recent genetic and functional evidence suggests a phenotype ( ) for tip HSCs. Fate mapping shows that many tip HSCs regularly feed into downstream stages, with individual cells contributing infrequently. Stem and progenitor cells downstream of tip HSCs serve as a major, nearly self-renewing source of day-to-day hematopoiesis, rendering the blood and immune system HSC-independent for extended periods of time. HSCs realize multilineage output, yet, fates restricted to several lineages or even a single lineage have also been observed. Single HSCs within a clone in the bone marrow that develop from a fetal HSC precursor have been observed to express clone-specific fates. Thus, the new tools probing HSC differentiation in situ are progressing beyond assays for HSC activity based on proliferation measurements and fates of transplanted stem cells, and the data challenge lineage interpretations of single-cell gene expression snapshots. Linking in vivo fate analyses to gene expression and other molecular determinants of cell fate will aid in unraveling the mechanisms of lineage commitment and the architecture of physiological hematopoiesis.
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http://dx.doi.org/10.1182/blood-2018-03-791517DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6307983PMC
September 2018

Tissue-Restricted Adaptive Type 2 Immunity Is Orchestrated by Expression of the Costimulatory Molecule OX40L on Group 2 Innate Lymphoid Cells.

Immunity 2018 06 12;48(6):1195-1207.e6. Epub 2018 Jun 12.

MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK. Electronic address:

The local regulation of type 2 immunity relies on dialog between the epithelium and the innate and adaptive immune cells. Here we found that alarmin-induced expression of the co-stimulatory molecule OX40L on group 2 innate lymphoid cells (ILC2s) provided tissue-restricted T cell co-stimulation that was indispensable for Th2 and regulatory T (Treg) cell responses in the lung and adipose tissue. Interleukin (IL)-33 administration resulted in organ-specific surface expression of OX40L on ILC2s and the concomitant expansion of Th2 and Treg cells, which was abolished upon deletion of OX40L on ILC2s (Il7raTnfsf4 mice). Moreover, Il7raTnfsf4 mice failed to mount effective Th2 and Treg cell responses and corresponding adaptive type 2 pulmonary inflammation arising from Nippostrongylus brasiliensis infection or allergen exposure. Thus, the increased expression of OX40L in response to IL-33 acts as a licensing signal in the orchestration of tissue-specific adaptive type 2 immunity, without which this response fails to establish.
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http://dx.doi.org/10.1016/j.immuni.2018.05.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6015114PMC
June 2018

β-adrenergic receptor-mediated negative regulation of group 2 innate lymphoid cell responses.

Science 2018 03;359(6379):1056-1061

Jill Roberts Institute for Research in Inflammatory Bowel Disease, Joan and Sanford I. Weill Department of Medicine, Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, New York, NY 10021, USA.

The type 2 inflammatory response is induced by various environmental and infectious stimuli. Although recent studies identified group 2 innate lymphoid cells (ILC2s) as potent sources of type 2 cytokines, the molecular pathways controlling ILC2 responses are incompletely defined. Here we demonstrate that murine ILC2s express the β-adrenergic receptor (βAR) and colocalize with adrenergic neurons in the intestine. βAR deficiency resulted in exaggerated ILC2 responses and type 2 inflammation in intestinal and lung tissues. Conversely, βAR agonist treatment was associated with impaired ILC2 responses and reduced inflammation in vivo. Mechanistically, we demonstrate that the βAR pathway is a cell-intrinsic negative regulator of ILC2 responses through inhibition of cell proliferation and effector function. Collectively, these data provide the first evidence of a neuronal-derived regulatory circuit that limits ILC2-dependent type 2 inflammation.
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http://dx.doi.org/10.1126/science.aan4829DOI Listing
March 2018

Polylox barcoding reveals haematopoietic stem cell fates realized in vivo.

Nature 2017 08 16;548(7668):456-460. Epub 2017 Aug 16.

Division of Cellular Immunology, German Cancer Research Center, D-69120 Heidelberg, Germany.

Developmental deconvolution of complex organs and tissues at the level of individual cells remains challenging. Non-invasive genetic fate mapping has been widely used, but the low number of distinct fluorescent marker proteins limits its resolution. Much higher numbers of cell markers have been generated using viral integration sites, viral barcodes, and strategies based on transposons and CRISPR-Cas9 genome editing; however, temporal and tissue-specific induction of barcodes in situ has not been achieved. Here we report the development of an artificial DNA recombination locus (termed Polylox) that enables broadly applicable endogenous barcoding based on the Cre-loxP recombination system. Polylox recombination in situ reaches a practical diversity of several hundred thousand barcodes, allowing tagging of single cells. We have used this experimental system, combined with fate mapping, to assess haematopoietic stem cell (HSC) fates in vivo. Classical models of haematopoietic lineage specification assume a tree with few major branches. More recently, driven in part by the development of more efficient single-cell assays and improved transplantation efficiencies, different models have been proposed, in which unilineage priming may occur in mice and humans at the level of HSCs. We have introduced barcodes into HSC progenitors in embryonic mice, and found that the adult HSC compartment is a mosaic of embryo-derived HSC clones, some of which are unexpectedly large. Most HSC clones gave rise to multilineage or oligolineage fates, arguing against unilineage priming, and suggesting coherent usage of the potential of cells in a clone. The spreading of barcodes, both after induction in embryos and in adult mice, revealed a basic split between common myeloid-erythroid development and common lymphocyte development, supporting the long-held but contested view of a tree-like haematopoietic structure.
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http://dx.doi.org/10.1038/nature23653DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5905670PMC
August 2017

ILC2s regulate adaptive Th2 cell functions via PD-L1 checkpoint control.

J Exp Med 2017 Sep 26;214(9):2507-2521. Epub 2017 Jul 26.

Trinity Biomedical Sciences Institute, School of Medicine, Trinity College Dublin, Dublin, Ireland

Group 2 innate lymphoid cells (ILC2s) are important effector cells driving the initiation of type 2 immune responses leading to adaptive T helper 2 (Th2) immunity. Here we show that ILC2s dynamically express the checkpoint inhibitor molecule PD-L1 during type 2 pulmonary responses. Surprisingly, PD-L1:PD-1 interaction between ILC2s and CD4 T cells did not inhibit the T cell response, but PD-L1-expressing ILC2s stimulated increased expression of GATA3 and production of IL-13 by Th2 cells both in vitro and in vivo. Conditional deletion of PD-L1 on ILC2s impaired early Th2 polarization and cytokine production, leading to delayed worm expulsion during infection with the gastrointestinal helminth Our results identify a novel PD-L1-controlled mechanism for type 2 polarization, with ILC2s mediating an innate checkpoint to control adaptive T helper responses, which has important implications for the treatment of type 2 inflammation.
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http://dx.doi.org/10.1084/jem.20170051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5584124PMC
September 2017

Type-2 innate lymphoid cells control the development of atherosclerosis in mice.

Nat Commun 2017 06 7;8:15781. Epub 2017 Jun 7.

Department of Medicine, Division of Cardiovascular Medicine, University of Cambridge, Cambridge CB2 0SZ, UK.

Type-2 innate lymphoid cells (ILC2) are a prominent source of type II cytokines and are found constitutively at mucosal surfaces and in visceral adipose tissue. Despite their role in limiting obesity, how ILC2s respond to high fat feeding is poorly understood, and their direct influence on the development of atherosclerosis has not been explored. Here, we show that ILC2 are present in para-aortic adipose tissue and lymph nodes and display an inflammatory-like phenotype atypical of adipose resident ILC2. High fat feeding alters both the number of ILC2 and their type II cytokine production. Selective genetic ablation of ILC2 in Ldlr mice accelerates the development of atherosclerosis, which is prevented by reconstitution with wild type but not Il5 or Il13 ILC2. We conclude that ILC2 represent a major innate cell source of IL-5 and IL-13 required for mounting atheroprotective immunity, which can be altered by high fat diet.
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http://dx.doi.org/10.1038/ncomms15781DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5467269PMC
June 2017

The E-Id Protein Axis Specifies Adaptive Lymphoid Cell Identity and Suppresses Thymic Innate Lymphoid Cell Development.

Immunity 2017 05;46(5):818-834.e4

Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA. Electronic address:

Innate and adaptive lymphoid development is orchestrated by the activities of E proteins and their antagonist Id proteins, but how these factors regulate early T cell progenitor (ETP) and innate lymphoid cell (ILC) development remains unclear. Using multiple genetic strategies, we demonstrated that E proteins E2A and HEB acted in synergy in the thymus to establish T cell identity and to suppress the aberrant development of ILCs, including ILC2s and lymphoid-tissue-inducer-like cells. E2A and HEB orchestrated T cell fate and suppressed the ILC transcription signature by activating the expression of genes associated with Notch receptors, T cell receptor (TCR) assembly, and TCR-mediated signaling. E2A and HEB acted in ETPs to establish and maintain a T-cell-lineage-specific enhancer repertoire, including regulatory elements associated with the Notch1, Rag1, and Rag2 loci. On the basis of these and previous observations, we propose that the E-Id protein axis specifies innate and adaptive lymphoid cell fate.
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http://dx.doi.org/10.1016/j.immuni.2017.04.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5512722PMC
May 2017

Defective bone repair in mast cell-deficient Cpa3Cre/+ mice.

PLoS One 2017 28;12(3):e0174396. Epub 2017 Mar 28.

Bone Engineering Labs, Research Institute-McGill University Health Centre. Montreal General Hospital C10.160, Cedar Ave., Montreal, QC, Canada.

In the adult skeleton, cells of the immune system interact with those of the skeleton during all phases of bone repair to influence the outcome. Mast cells are immune cells best known for their pathologic role in allergy, and may be involved in chronic inflammatory and fibrotic disorders. Potential roles for mast cells in tissue homeostasis, vascularization and repair remain enigmatic. Previous studies in combined mast cell- and Kit-deficient KitW-sh/W-sh mice (KitW-sh) implicated mast cells in bone repair but KitW-sh mice suffer from additional Kit-dependent hematopoietic and non- hematopoietic deficiencies that could have confounded the outcome. The goal of the current study was to compare bone repair in normal wild type (WT) and Cpa3Cre/+ mice, which lack mast cells in the absence of any other hematopoietic or non- hematopoietic deficiencies. Repair of a femoral window defect was characterized using micro CT imaging and histological analyses from the early inflammatory phase, through soft and hard callus formation, and finally the remodeling phase. The data indicate 1) mast cells appear in healing bone of WT mice but not Cpa3Cre/+ mice, beginning 14 days after surgery; 2) re-vascularization of repair tissue and deposition of mineralized bone was delayed and dis-organised in Cpa3Cre/+ mice compared with WT mice; 3) the defects in Cpa3Cre/+ mice were associated with little change in anabolic activity and biphasic alterations in osteoclast and macrophage activity. The outcome at 56 days postoperative was complete bridging of the defect in most WT mice and fibrous mal-union in most Cpa3Cre/+ mice. The results indicate that mast cells promote bone healing, possibly by recruiting vascular endothelial cells during the inflammatory phase and coordinating anabolic and catabolic activity during tissue remodeling. Taken together the data indicate that mast cells have a positive impact on bone repair.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0174396PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5369761PMC
September 2017

GATA4-dependent organ-specific endothelial differentiation controls liver development and embryonic hematopoiesis.

J Clin Invest 2017 Mar 20;127(3):1099-1114. Epub 2017 Feb 20.

Microvascular endothelial cells (ECs) are increasingly recognized as organ-specific gatekeepers of their microenvironment. Microvascular ECs instruct neighboring cells in their organ-specific vascular niches through angiocrine factors, which include secreted growth factors (angiokines), extracellular matrix molecules, and transmembrane proteins. However, the molecular regulators that drive organ-specific microvascular transcriptional programs and thereby regulate angiodiversity are largely elusive. In contrast to other ECs, which form a continuous cell layer, liver sinusoidal ECs (LSECs) constitute discontinuous, permeable microvessels. Here, we have shown that the transcription factor GATA4 controls murine LSEC specification and function. LSEC-restricted deletion of Gata4 caused transformation of discontinuous liver sinusoids into continuous capillaries. Capillarization was characterized by ectopic basement membrane deposition, formation of a continuous EC layer, and increased expression of VE-cadherin. Correspondingly, ectopic expression of GATA4 in cultured continuous ECs mediated the downregulation of continuous EC-associated transcripts and upregulation of LSEC-associated genes. The switch from discontinuous LSECs to continuous ECs during embryogenesis caused liver hypoplasia, fibrosis, and impaired colonization by hematopoietic progenitor cells, resulting in anemia and embryonic lethality. Thus, GATA4 acts as master regulator of hepatic microvascular specification and acquisition of organ-specific vascular competence, which are indispensable for liver development. The data also establish an essential role of the hepatic microvasculature in embryonic hematopoiesis.
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http://dx.doi.org/10.1172/JCI90086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5330741PMC
March 2017

Hematopoietic Stem Cell Niches Produce Lineage-Instructive Signals to Control Multipotent Progenitor Differentiation.

Immunity 2016 12 29;45(6):1219-1231. Epub 2016 Nov 29.

Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA. Electronic address:

Hematopoietic stem cells (HSCs) self-renew in bone marrow niches formed by mesenchymal progenitors and endothelial cells expressing the chemokine CXCL12, but whether a separate niche instructs multipotent progenitor (MPP) differentiation remains unclear. We show that MPPs resided in HSC niches, where they encountered lineage-instructive differentiation signals. Conditional deletion of the chemokine receptor CXCR4 in MPPs reduced differentiation into common lymphoid progenitors (CLPs), which decreased lymphopoiesis. CXCR4 was required for CLP positioning near Interleukin-7 (IL-7) cells and for optimal IL-7 receptor signaling. IL-7 cells expressed CXCL12 and the cytokine SCF, were mesenchymal progenitors capable of differentiation into osteoblasts and adipocytes, and comprised a minor subset of sinusoidal endothelial cells. Conditional Il7 deletion in mesenchymal progenitors reduced B-lineage committed CLPs, while conditional Cxcl12 or Scf deletion from IL-7 cells reduced HSC and MPP numbers. Thus, HSC maintenance and multilineage differentiation are distinct cell lineage decisions that are both controlled by HSC niches.
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http://dx.doi.org/10.1016/j.immuni.2016.11.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5538583PMC
December 2016

Output without input: the lifelong productivity of hematopoietic stem cells.

Curr Opin Cell Biol 2016 12 10;43:69-77. Epub 2016 Sep 10.

Division of Cellular Immunology, German Cancer Research Center, D-69120 Heidelberg, Germany. Electronic address:

The hematopoietic stem cell (HSC) compartment must be maintained life-long, while being replenishable only from within. HSC proliferation can compensate for cell loss by differentiation, by cell death, or by mobilization from the bone marrow niches, but the relative use of proliferation to compensate for these distinct depletion sources is unclear. Classifications of HSC states (e.g., as active, dormant, quiescent or parsimonious) have mostly been based on HSC proliferation rather than on actual differentiation arising from HSC. New in vivo fate mapping experiments have shed light on HSC output. The kinetics of label emergence from HSC to progenitor stages uncovered steady, infrequent and low output from large numbers of HSC during normal adult hematopoiesis. Here, we discuss the relative contribution of proliferation to differentiation and self-renewal in hematopoietic stem and progenitor compartments, and propose that kinetic data on HSC output also yield insights into the structure of the hematopoietic hierarchy.
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http://dx.doi.org/10.1016/j.ceb.2016.08.003DOI Listing
December 2016

Of Mouse Models of Mast Cell Deficiency and Metabolic Syndrome.

Cell Metab 2016 07;24(1):1-2

Division of Cellular Immunology, German Cancer Research Center, D-69120 Heidelberg, Germany. Electronic address:

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http://dx.doi.org/10.1016/j.cmet.2016.06.019DOI Listing
July 2016
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