Recent Submissions

  • Nitric oxide controls proliferation of Leishmania major by inhibiting the recruitment of permissive host cells.

    Formaglio, Pauline; Alabdullah, Mohamad; Siokis, Anastasios; Handschuh, Juliane; Sauerland, Ina; Fu, Yan; Krone, Anna; Gintschel, Patricia; Stettin, Juliane; Heyde, Sandrina; et al. (Cell Press, 2021-10-15)
    Nitric oxide (NO) is an important antimicrobial effector but also prevents unnecessary tissue damage by shutting down the recruitment of monocyte-derived phagocytes. Intracellular pathogens such as Leishmania major can hijack these cells as a niche for replication. Thus, NO might exert containment by restricting the availability of the cellular niche required for efficient pathogen proliferation. However, such indirect modes of action remain to be established. By combining mathematical modeling with intravital 2-photon biosensors of pathogen viability and proliferation, we show that low L. major proliferation results not from direct NO impact on the pathogen but from reduced availability of proliferation-permissive host cells. Although inhibiting NO production increases recruitment of these cells, and thus pathogen proliferation, blocking cell recruitment uncouples the NO effect from pathogen proliferation. Therefore, NO fulfills two distinct functions for L. major containment: permitting direct killing and restricting the supply of proliferation-permissive host cells.
  • A Central Role for Atg5 in Microbiota-Dependent Foxp3 RORγt Treg Cell Preservation to Maintain Intestinal Immune Homeostasis.

    Plaza-Sirvent, Carlos; Zhao, Bei; Bronietzki, Alisha W; Pils, Marina C; Tafrishi, Neda; Schuster, Marc; Strowig, Till; Schmitz, Ingo; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers, 2021-08-26)
    Autophagy is an evolutionary conserved catabolic pathway that ensures the degradation of intracellular components. The autophagic pathway is regulated by autophagy-related (Atg) proteins that govern formation of double-membraned vesicles called autophagosomes. Autophagy deficiency in regulatory T (Treg) cells leads to increased apoptosis of these cells and to the development of autoimmune disorders, predominantly characterized by intestinal inflammation. Recently, RORγt-expressing Treg cells have been identified as key regulators of gut homeostasis, preventing intestinal immunopathology. To study the role of autophagy in RORγt+ Foxp3+ Treg cells, we generated mice lacking the essential component of the core autophagy machinery Atg5 in Foxp3+ cells. Atg5 deficiency in Treg cells led to a predominant intestinal inflammation. While Atg5-deficient Treg cells were reduced in peripheral lymphoid organs, the intestinal RORγt+ Foxp3+ subpopulation of Treg cells was most severely affected. Our data indicated that autophagy is essential to maintain the intestinal RORγt+ Foxp3+ Treg population, thereby protecting the mice from gut inflammatory disorders.
  • Mesenteric Lymph Node Transplantation in Mice to Study Immune Responses of the Gastrointestinal Tract.

    Shaikh, Haroon; Vargas, Juan Gamboa; Mokhtari, Zeinab; Jarick, Katja J; Ulbrich, Maria; Mosca, Josefina Peña; Viera, Estibaliz Arellano; Graf, Caroline; Le, Duc-Dung; Heinze, Katrin G; et al. (Frontiers, 2021-07-26)
    Mesenteric lymph nodes (mLNs) are sentinel sites of enteral immunosurveillance and immune homeostasis. Immune cells from the gastrointestinal tract (GIT) are constantly recruited to the mLNs in steady-state and under inflammatory conditions resulting in the induction of tolerance and immune cells activation, respectively. Surgical dissection and transplantation of lymph nodes (LN) is a technique that has supported seminal work to study LN function and is useful to investigate resident stromal and endothelial cell biology and their cellular interactions in experimental disease models. Here, we provide a detailed protocol of syngeneic mLN transplantation and report assays to analyze effective mLN engraftment in congenic recipients. Transplanted mLNs allow to study T cell activation and proliferation in preclinical mouse models. Donor mLNs proved viable and functional after surgical transplantation and regenerated blood and lymphatic vessels. Immune cells from the host completely colonized the transplanted mLNs within 7-8 weeks after the surgical intervention. After allogeneic hematopoietic cell transplantation (allo-HCT), adoptively transferred allogeneic CD4+ T cells from FVB/N (H-2q) mice homed to the transplanted mLNs in C57BL/6 (H-2b) recipients during the initiation phase of acute graft-versus-host disease (aGvHD). These CD4+ T cells retained full proliferative capacity and upregulated effector and gut homing molecules comparable to those in mLNs from unmanipulated wild-type recipients. Wild type mLNs transplanted into MHCII deficient syngeneic hosts sufficed to activate alloreactive T cells upon allogeneic hematopoietic cell transplantation, even in the absence of MHCII+ CD11c+ myeloid cells. These data support that orthotopically transplanted mLNs maintain physiological functions after transplantation. The technique of LN transplantation can be applied to study migratory and resident cell compartment interactions in mLNs as well as immune reactions from and to the gut under inflammatory and non-inflammatory conditions.
  • Germinal Centre Shutdown.

    Arulraj, Theinmozhi; Binder, Sebastian C; Robert, Philippe A; Meyer-Hermann, Michael; BRICS, Braunschweiger Zentrum für Systembiologie, Rebenring 56,38106 Braunschweig, Germany.; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers, 2021-07-07)
    Germinal Centres (GCs) are transient structures in secondary lymphoid organs, where affinity maturation of B cells takes place following an infection. While GCs are responsible for protective antibody responses, dysregulated GC reactions are associated with autoimmune disease and B cell lymphoma. Typically, 'normal' GCs persist for a limited period of time and eventually undergo shutdown. In this review, we focus on an important but unanswered question - what causes the natural termination of the GC reaction? In murine experiments, lack of antigen, absence or constitutive T cell help leads to premature termination of the GC reaction. Consequently, our present understanding is limited to the idea that GCs are terminated due to a decrease in antigen access or changes in the nature of T cell help. However, there is no direct evidence on which biological signals are primarily responsible for natural termination of GCs and a mechanistic understanding is clearly lacking. We discuss the present understanding of the GC shutdown, from factors impacting GC dynamics to changes in cellular interactions/dynamics during the GC lifetime. We also address potential missing links and remaining questions in GC biology, to facilitate further studies to promote a better understanding of GC shutdown in infection and immune dysregulation.
  • Tbx21 and foxp3 are Epigenetically Stabilized in T-Bet Tregs That Transiently Accumulate in Influenza A Virus-Infected Lungs.

    Elfaki, Yassin; Yang, Juhao; Boehme, Julia; Schultz, Kristin; Bruder, Dunja; Falk, Christine S; Huehn, Jochen; Floess, Stefan; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2021-07-14)
    During influenza A virus (IAV) infections, CD4+ T cell responses within infected lungs mainly involve T helper 1 (Th1) and regulatory T cells (Tregs). Th1-mediated responses favor the co-expression of T-box transcription factor 21 (T-bet) in Foxp3+ Tregs, enabling the efficient Treg control of Th1 responses in infected tissues. So far, the exact accumulation kinetics of T cell subsets in the lungs and lung-draining lymph nodes (dLN) of IAV-infected mice is incompletely understood, and the epigenetic signature of Tregs accumulating in infected lungs has not been investigated. Here, we report that the total T cell and the two-step Treg accumulation in IAV-infected lungs is transient, whereas the change in the ratio of CD4+ to CD8+ T cells is more durable. Within lungs, the frequency of Tregs co-expressing T-bet is steadily, yet transiently, increasing with a peak at Day 7 post-infection. Interestingly, T-bet+ Tregs accumulating in IAV-infected lungs displayed a strongly demethylated Tbx21 locus, similarly as in T-bet+ conventional T cells, and a fully demethylated Treg-specific demethylated region (TSDR) within the Foxp3 locus. In summary, our data suggest that T-bet+ but not T-bet- Tregs are epigenetically stabilized during IAV-induced infection in the lung.
  • Transcriptome analysis following neurotropic virus infection reveals faulty innate immunity and delayed antigen presentation in mice susceptible to virus-induced demyelination.

    Ciurkiewicz, Malgorzata; Floess, Stefan; Beckstette, Michael; Kummerfeld, Maren; Baumgärtner, Wolfgang; Huehn, Jochen; Beineke, Andreas; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Wiley & Sons Ltd., 2021-07-06)
    Viral infections of the central nervous system cause acute or delayed neuropathology and clinical consequences ranging from asymptomatic courses to chronic, debilitating diseases. The outcome of viral encephalitis is partially determined by genetically programed immune response patterns of the host. Experimental infection of mice with Theiler's murine encephalomyelitis virus (TMEV) causes diverse neurologic diseases, including TMEV-induced demyelinating disease (TMEV-IDD), depending on the used mouse strain. The aim of the present study was to compare initial transcriptomic changes occurring in the brain of TMEV-infected SJL (TMEV-IDD susceptible) and C57BL/6 (TMEV-IDD resistant) mice. Animals were infected with TMEV and sacrificed 4, 7, or 14 days post infection. RNA was isolated from brain tissue and analyzed by whole-transcriptome sequencing. Selected differences were confirmed on a protein level by immunohistochemistry. In mock-infected SJL and C57BL/6 mice, >200 differentially expressed genes (DEGs) were detected. Following TMEV-infection, the number of DEGs increased to >700. Infected C57BL/6 mice showed a higher expression of transcripts related to antigen presentation via major histocompatibility complex (MHC) I, innate antiviral immune responses and cytotoxicity, compared with infected SJL animals. Expression of many of those genes was weaker or delayed in SJL mice, associated with a failure of viral clearance in this mouse strain. SJL mice showed prolonged elevation of MHC II and chemotactic genes compared with C57BL/6 mice, which presumably facilitates the induction of chronic demyelinating disease. In addition, elevated expression of several genes associated with immunomodulatory or -suppressive functions was observed in SJL mice. The exploratory study confirms previous observations in the model and provides an extensive list of new immunologic parameters potentially contributing to different outcomes of viral encephalitis in two mouse strains.
  • Generation of Sequencing Libraries for Building Immune Cell Methylomes.

    Floess, Stefan; Huehn, Jochen; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Springer Nature, 2021-04-30)
    The comparison of methylomes from immune cells enables the identification of differentially methylated regions and thereby region-associated gene loci. Those regions can be used to discriminate one immune cell population from the other, as well as help to identify key molecules and major pathways determining the unique phenotypes of immune cell lineages. The combination of bisulfite treatment of genomic DNA and next-generation sequencing provides the basis for studying epigenetic changes in different immune cell populations. Further development of whole-genome bisulfite sequencing resulted in a protocol for sequencing libraries that accept both single- or double-stranded DNA from fixed or nonfixed cells, respectively. Therefore, researchers can include immune cell populations in their methylation studies whose isolation depends on the staining of intracellular molecules.
  • The microbiota is dispensable for the early stages of peripheral regulatory T cell induction within mesenteric lymph nodes.

    Wiechers, Carolin; Zou, Mangge; Galvez, Eric; Beckstette, Michael; Ebel, Maria; Strowig, Till; Huehn, Jochen; Pezoldt, Joern; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Springer Nature, 2021-03-24)
    Intestinal Foxp3+ regulatory T cell (Treg) subsets are crucial players in tolerance to microbiota-derived and food-borne antigens, and compelling evidence suggests that the intestinal microbiota modulates their generation, functional specialization, and maintenance. Selected bacterial species and microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), have been reported to promote Treg homeostasis in the intestinal lamina propria. Furthermore, gut-draining mesenteric lymph nodes (mLNs) are particularly efficient sites for the generation of peripherally induced Tregs (pTregs). Despite this knowledge, the direct role of the microbiota and their metabolites in the early stages of pTreg induction within mLNs is not fully elucidated. Here, using an adoptive transfer-based pTreg induction system, we demonstrate that neither transfer of a dysbiotic microbiota nor dietary SCFA supplementation modulated the pTreg induction capacity of mLNs. Even mice housed under germ-free (GF) conditions displayed equivalent pTreg induction within mLNs. Further molecular characterization of these de novo induced pTregs from mLNs by dissection of their transcriptomes and accessible chromatin regions revealed that the microbiota indeed has a limited impact and does not contribute to the initialization of the Treg-specific epigenetic landscape. Overall, our data suggest that the microbiota is dispensable for the early stages of pTreg induction within mLNs.
  • Impact of process temperature and organic loading rate on cellulolytic / hydrolytic biofilm microbiomes during biomethanation of ryegrass silage revealed by genome-centered metagenomics and metatranscriptomics.

    Maus, Irena; Klocke, Michael; Derenkó, Jaqueline; Stolze, Yvonne; Beckstette, Michael; Jost, Carsten; Wibberg, Daniel; Blom, Jochen; Henke, Christian; Willenbücher, Katharina; et al. (BMC, 2020-03-02)
    Background: Anaerobic digestion (AD) of protein-rich grass silage was performed in experimental two-stage two-phase biogas reactor systems at low vs. increased organic loading rates (OLRs) under mesophilic (37 °C) and thermophilic (55 °C) temperatures. To follow the adaptive response of the biomass-attached cellulolytic/hydrolytic biofilms at increasing ammonium/ammonia contents, genome-centered metagenomics and transcriptional profiling based on metagenome assembled genomes (MAGs) were conducted. Results: In total, 78 bacterial and archaeal MAGs representing the most abundant members of the communities, and featuring defined quality criteria were selected and characterized in detail. Determination of MAG abundances under the tested conditions by mapping of the obtained metagenome sequence reads to the MAGs revealed that MAG abundance profiles were mainly shaped by the temperature but also by the OLR. However, the OLR effect was more pronounced for the mesophilic systems as compared to the thermophilic ones. In contrast, metatranscriptome mapping to MAGs subsequently normalized to MAG abundances showed that under thermophilic conditions, MAGs respond to increased OLRs by shifting their transcriptional activities mainly without adjusting their proliferation rates. This is a clear difference compared to the behavior of the microbiome under mesophilic conditions. Here, the response to increased OLRs involved adjusting of proliferation rates and corresponding transcriptional activities. The analysis led to the identification of MAGs positively responding to increased OLRs. The most outstanding MAGs in this regard, obviously well adapted to higher OLRs and/or associated conditions, were assigned to the order Clostridiales (Acetivibrio sp.) for the mesophilic biofilm and the orders Bacteroidales (Prevotella sp. and an unknown species), Lachnospirales (Herbinix sp. and Kineothrix sp.) and Clostridiales (Clostridium sp.) for the thermophilic biofilm. Genome-based metabolic reconstruction and transcriptional profiling revealed that positively responding MAGs mainly are involved in hydrolysis of grass silage, acidogenesis and / or acetogenesis. Conclusions: An integrated -omics approach enabled the identification of new AD biofilm keystone species featuring outstanding performance under stress conditions such as increased OLRs. Genome-based knowledge on the metabolic potential and transcriptional activity of responsive microbiome members will contribute to the development of improved microbiological AD management strategies for biomethanation of renewable biomass.
  • Single-cell chromatin accessibility landscape identifies tissue repair program in human regulatory T cells.

    Delacher, Michael; Simon, Malte; Sanderink, Lieke; Hotz-Wagenblatt, Agnes; Wuttke, Marina; Schambeck, Kathrin; Schmidleithner, Lisa; Bittner, Sebastian; Pant, Asmita; Ritter, Uwe; et al. (Cell Press, 2021-03-30)
    Murine regulatory T (Treg) cells in tissues promote tissue homeostasis and regeneration. We sought to identify features that characterize human Treg cells with these functions in healthy tissues. Single-cell chromatin accessibility profiles of murine and human tissue Treg cells defined a conserved, microbiota-independent tissue-repair Treg signature with a prevailing footprint of the transcription factor BATF. This signature, combined with gene expression profiling and TCR fate mapping, identified a population of tissue-like Treg cells in human peripheral blood that expressed BATF, chemokine receptor CCR8 and HLA-DR. Human BATF+CCR8+ Treg cells from normal skin and adipose tissue shared features with nonlymphoid T follicular helper-like (Tfh-like) cells, and induction of a Tfh-like differentiation program in naive human Treg cells partially recapitulated tissue Treg regenerative characteristics, including wound healing potential. Human BATF+CCR8+ Treg cells from healthy tissue share features with tumor-resident Treg cells, highlighting the importance of understanding the context-specific functions of these cells.
  • Influenza A virus-induced thymus atrophy differentially affects dynamics of conventional and regulatory T-cell development in mice.

    Elfaki, Yassin; Robert, Philippe A; Binz, Christoph; Falk, Christine S; Bruder, Dunja; Prinz, Immo; Floess, Stefan; Meyer-Hermann, Michael; Huehn, Jochen; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.; BRICS, Braunschweiger Zentrum für Systembiologie, Rebenring 56,38106 Braunschweig, Germany. (Wiley-VCH, 2021-02-26)
    Foxp3+ Treg cells, which are crucial for maintenance of self-tolerance, mainly develop within the thymus, where they arise from CD25+ Foxp3- or CD25- Foxp3+ Treg cell precursors. Although it is known that infections can cause transient thymic involution, the impact of infection-induced thymus atrophy on thymic Treg (tTreg) cell development is unknown. Here, we infected mice with influenza A virus (IAV) and studied thymocyte population dynamics post infection. IAV infection caused a massive, but transient thymic involution, dominated by a loss of CD4+ CD8+ double-positive (DP) thymocytes, which was accompanied by a significant increase in the frequency of CD25+ Foxp3+ tTreg cells. Differential apoptosis susceptibility could be experimentally excluded as a reason for the relative tTreg cell increase, and mathematical modeling suggested that enhanced tTreg cell generation cannot explain the increased frequency of tTreg cells. Yet, an increased death of DP thymocytes and augmented exit of single-positive (SP) thymocytes was suggested to be causative. Interestingly, IAV-induced thymus atrophy resulted in a significantly reduced T-cell receptor (TCR) repertoire diversity of newly produced tTreg cells. Taken together, IAV-induced thymus atrophy is substantially altering the dynamics of major thymocyte populations, finally resulting in a relative increase of tTreg cells with an altered TCR repertoire.
  • Lymph node stromal cell subsets-Emerging specialists for tailored tissue-specific immune responses.

    Zou, Mangge; Wiechers, Carolin; Huehn, Jochen; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Elsevier, 2021-02-25)
    The effective priming of adaptive immune responses depends on the precise dispatching of lymphocytes and antigens into and within lymph nodes (LNs), which are strategically dispersed throughout the body. Over the past decade, a growing body of evidence has advanced our understanding of lymph node stromal cells (LNSCs) from viewing them as mere accessory cells to seeing them as critical cellular players for the modulation of adaptive immune responses. In this review, we summarize current advances on the pivotal roles that LNSCs play in orchestrating adaptive immune responses during homeostasis and infection, and highlight the imprinting of location-specific information by micro-environmental cues into LNSCs, thereby tailoring tissue-specific immune responses.
  • Efficient IL-2R signaling differentially affects the stability, function, and composition of the regulatory T-cell pool.

    Permanyer, Marc; Bošnjak, Berislav; Glage, Silke; Friedrichsen, Michaela; Floess, Stefan; Huehn, Jochen; Patzer, Gwendolyn E; Odak, Ivan; Eckert, Nadine; Zargari, Razieh; et al. (Springer Nature, 2021-01-06)
    Signaling via interleukin-2 receptor (IL-2R) is a requisite for regulatory T (Treg) cell identity and function. However, it is not completely understood to what degree IL-2R signaling is required for Treg cell homeostasis, lineage stability and function in both resting and inflammatory conditions. Here, we characterized a spontaneous mutant mouse strain endowed with a hypomorphic Tyr129His variant of CD25, the α-chain of IL-2R, which resulted in diminished receptor expression and reduced IL-2R signaling. Under noninflammatory conditions, Cd25Y129H mice harbored substantially lower numbers of peripheral Treg cells with stable Foxp3 expression that prevented the development of spontaneous autoimmune disease. In contrast, Cd25Y129H Treg cells failed to efficiently induce immune suppression and lost lineage commitment in a T-cell transfer colitis model, indicating that unimpaired IL-2R signaling is critical for Treg cell function in inflammatory environments. Moreover, single-cell RNA sequencing of Treg cells revealed that impaired IL-2R signaling profoundly affected the balance of central and effector Treg cell subsets. Thus, partial loss of IL-2R signaling differentially interferes with the maintenance, heterogeneity, and suppressive function of the Treg cell pool.
  • Autophagy-A Story of Bacteria Interfering with the Host Cell Degradation Machinery.

    Riebisch, Anna K; Mühlen, Sabrina; Beer, Yan Yan; Schmitz, Ingo; HZI, Helmholtz Zentrum für Infektionsforschung, GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (MDPI, 2021-01-22)
    Autophagy is a highly conserved and fundamental cellular process to maintain cellular homeostasis through recycling of defective organelles or proteins. In a response to intracellular pathogens, autophagy further acts as an innate immune response mechanism to eliminate pathogens. This review will discuss recent findings on autophagy as a reaction to intracellular pathogens, such as Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Staphylococcus aureus, and pathogenic Escherichia coli. Interestingly, while some of these bacteria have developed methods to use autophagy for their own benefit within the cell, others have developed fascinating mechanisms to evade recognition, to subvert the autophagic pathway, or to escape from autophagy.
  • The Cytomegalovirus Tegument Protein UL35 Antagonizes Pattern Recognition Receptor-Mediated Type I IFN Transcription.

    Fabits, Markus; Gonçalves Magalhães, Vladimir; Chan, Baca; Girault, Virginie; Elbasani, Endrit; Rossetti, Elisa; Saeland, Eirikur; Messerle, Martin; Pichlmair, Andreas; Lisnić, Vanda Juranić; et al. (MDPI, 2020-05-26)
    The rapid activation of pattern recognition receptor (PRR)-mediated type I interferon (IFN) signaling is crucial for the host response to infection. In turn, human cytomegalovirus (HCMV) must evade this potent response to establish life-long infection. Here, we reveal that the HCMV tegument protein UL35 antagonizes the activation of type I IFN transcription downstream of the DNA and RNA sensors cGAS and RIG-I, respectively. We show that ectopic expression of UL35 diminishes the type I IFN response, while infection with a recombinant HCMV lacking UL35 induces an elevated type I IFN response compared to wildtype HCMV. With a series of luciferase reporter assays and the analysis of signaling kinetics upon HCMV infection, we observed that UL35 downmodulates PRR signaling at the level of the key signaling factor TANK-binding kinase 1 (TBK1). Finally, we demonstrate that UL35 and TBK1 co-immunoprecipitate when co-expressed in HEK293T cells. In addition, we show that a previously reported cellular binding partner of UL35, O-GlcNAc transferase (OGT), post-translationally GlcNAcylates UL35, but that this modification is not required for the antagonizing effect of UL35 on PRR signaling. In summary, we have identified UL35 as the first HCMV protein to antagonize the type I IFN response at the level of TBK1, thereby enriching our understanding of how this important herpesvirus escapes host immune responses.
  • YB-1 Mediates TNF-Induced Pro-Survival Signaling by Regulating NF-κB Activation.

    Shah, Aneri; Plaza-Sirvent, Carlos; Weinert, Sönke; Buchbinder, Jörn H; Lavrik, Inna N; Mertens, Peter R; Schmitz, Ingo; Lindquist, Jonathan A; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (MDPI, 2020-08-05)
    Cell fate decisions regulating survival and death are essential for maintaining tissue homeostasis; dysregulation thereof can lead to tumor development. In some cases, survival and death are triggered by the same receptor, e.g., tumor necrosis factor (TNF)-receptor 1 (TNFR1). We identified a prominent role for the cold shock Y-box binding protein-1 (YB-1) in the TNF-induced activation and nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65. In the absence of YB-1, the expression of TNF receptor-associated factor 2 (TRAF2), a central component of the TNF receptor signaling complex required for NF-κB activation, is significantly reduced. Therefore, we hypothesized that the loss of YB-1 results in a destabilization of TRAF2. Consistent with this hypothesis, we observed that YB-1-deficient cells were more prone to TNF-induced apoptotic cell death. We observed enhanced effector caspase-3 activation and could successfully rescue the cells using the pan-caspase inhibitor zVAD-fmk, but not necrostatin-1. Taken together, our results indicate that YB-1 plays a central role in promoting cell survival through NF-κB activation and identifies a novel mechanism by which enhanced YB-1 expression may contribute to tumor development.
  • Acute neonatal Listeria monocytogenes infection causes long-term, organ-specific changes in immune cell subset composition.

    Zou, Mangge; Yang, Juhao; Wiechers, Carolin; Huehn, Jochen; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Akadémiai Kiadó, 2020-06-19)
    Listeria monocytogenes (Lm) is a food-borne pathogen with a high chance of infecting neonates, pregnant women, elderly and immunocompromised individuals. Lm infection in neonates can cause neonatal meningitis and sepsis with a high risk of severe neurological and developmental sequelae and high mortality rates. However, whether an acute neonatal Lm infection causes long-term effects on the immune system persisting until adulthood has not been fully elucidated. Here, we established a neonatal Lm infection model and monitored the composition of major immune cell subsets at defined time points post infection (p.i.) in secondary lymphoid organs and the intestine. Twelve weeks p.i., the CD8+ T cell population was decreased in colon and mesenteric lymph nodes (mLNs) with an opposing increase in the spleen. In the colon, we observed an accumulation of CD4+ and CD8+ effector/memory T cells with an increase of T-bet+ T helper 1 (Th1) cells. In addition, 12 weeks p.i. an altered composition of innate lymphoid cell (ILC) and dendritic cell (DC) subsets was still observed in colon and mLNs, respectively. Together, these findings highlight organ-specific long-term consequences of an acute neonatal Lm infection on both the adaptive and innate immune system.
  • Staphylococcus aureus Alpha-Toxin Limits Type 1 While Fostering Type 3 Immune Responses.

    Bonifacius, Agnes; Goldmann, Oliver; Floess, Stefan; Holtfreter, Silva; Robert, Philippe A; Nordengrün, Maria; Kruse, Friederike; Lochner, Matthias; Falk, Christine S; Schmitz, Ingo; et al. (Frontiers, 2020-08-07)
    Staphylococcus aureus can cause life-threatening diseases, and hospital- as well as community-associated antibiotic-resistant strains are an emerging global public health problem. Therefore, prophylactic vaccines or immune-based therapies are considered as alternative treatment opportunities. To develop such novel treatment approaches, a better understanding of the bacterial virulence and immune evasion mechanisms and their potential effects on immune-based therapies is essential. One important staphylococcal virulence factor is alpha-toxin, which is able to disrupt the epithelial barrier in order to establish infection. In addition, alpha-toxin has been reported to modulate other cell types including immune cells. Since CD4+ T cell-mediated immunity is required for protection against S. aureus infection, we were interested in the ability of alpha-toxin to directly modulate CD4+ T cells. To address this, murine naïve CD4+ T cells were differentiated in vitro into effector T cell subsets in the presence of alpha-toxin. Interestingly, alpha-toxin induced death of Th1-polarized cells, while cells polarized under Th17 conditions showed a high resistance toward increasing concentrations of this toxin. These effects could neither be explained by differential expression of the cellular alpha-toxin receptor ADAM10 nor by differential activation of caspases, but might result from an increased susceptibility of Th1 cells toward Ca2+-mediated activation-induced cell death. In accordance with the in vitro findings, an alpha-toxin-dependent decrease of Th1 and concomitant increase of Th17 cells was observed in vivo during S. aureus bacteremia. Interestingly, corresponding subsets of innate lymphoid cells and γδ T cells were similarly affected, suggesting a more general effect of alpha-toxin on the modulation of type 1 and type 3 immune responses. In conclusion, we have identified a novel alpha-toxin-dependent immunomodulatory strategy of S. aureus, which can directly act on CD4+ T cells and might be exploited for the development of novel immune-based therapeutic approaches to treat infections with antibiotic-resistant S. aureus strains.
  • Salt generates anti-inflammatory Th17 cells but amplifies their pathogenicity in pro-inflammatory cytokine microenvironments.

    Matthias, Julia; Heink, Sylvia; Picard, Felix Sr; Zeiträg, Julia; Kolz, Anna; Chao, Ying-Yin; Soll, Dominik; de Almeida, Gustavo P; Glasmacher, Elke; Jacobsen, Ilse D; et al. (American Society for Clinical Investigation, 2020-06-02)
    T helper cells integrate signals from their microenvironment to acquire distinct specialization programs for efficient clearance of diverse pathogens or for immunotolerance. Ionic signals have recently been demonstrated to affect T cell polarization and function. Sodium chloride (NaCl) was proposed to accumulate in peripheral tissues upon dietary intake and to promote autoimmunity via the Th17 cell axis. Here we demonstrate that high NaCl conditions induced a stable, pathogen-specific, anti-inflammatory Th17 cell fate in human T cells in vitro. The p38/MAPK pathway, involving NFAT5 and SGK1, regulated FoxP3 and interleukin (IL)-17A-expression in high-NaCl conditions. The NaCl-induced acquisition of an anti-inflammatory Th17 cell fate was confirmed in vivo in an experimental autoimmune encephalomyelitis (EAE) mouse model, which demonstrated strongly reduced disease symptoms upon transfer of T cells polarized in high NaCl conditions. However, NaCl was coopted to promote murine and human Th17 cell pathogenicity, if T cell stimulation occurred in a pro-inflammatory and TGF-β-low cytokine microenvironment. Taken together, our findings reveal a context-dependent, dichotomous role for NaCl in shaping Th17 cell pathogenicity. NaCl might therefore prove beneficial for the treatment of chronic inflammatory diseases in combination with cytokine-blocking drugs.
  • Transmaternal Helicobacter pylori exposure reduces allergic airway inflammation in offspring through regulatory T cells.

    Kyburz, Andreas; Fallegger, Angela; Zhang, Xiaozhou; Altobelli, Aleksandra; Artola-Boran, Mariela; Borbet, Timothy; Urban, Sabine; Paul, Petra; Münz, Christian; Floess, Stefan; et al. (Elsevier, 2018-09-19)
    Background: Transmaternal exposure to tobacco, microbes, nutrients, and other environmental factors shapes the fetal immune system through epigenetic processes. The gastric microbe Helicobacter pylori represents an ancestral constituent of the human microbiota that causes gastric disorders on the one hand and is inversely associated with allergies and chronic inflammatory conditions on the other. Objective: Here we investigate the consequences of transmaternal exposure to H pylori in utero and/or during lactation for susceptibility to viral and bacterial infection, predisposition to allergic airway inflammation, and development of immune cell populations in the lungs and lymphoid organs. Methods: We use experimental models of house dust mite- or ovalbumin-induced airway inflammation and influenza A virus or Citrobacter rodentium infection along with metagenomics analyses, multicolor flow cytometry, and bisulfite pyrosequencing, to study the effects of H pylori on allergy severity and immunologic and microbiome correlates thereof. Results: Perinatal exposure to H pylori extract or its immunomodulator vacuolating cytotoxin confers robust protective effects against allergic airway inflammation not only in first- but also second-generation offspring but does not increase susceptibility to viral or bacterial infection. Immune correlates of allergy protection include skewing of regulatory over effector T cells, expansion of regulatory T-cell subsets expressing CXCR3 or retinoic acid-related orphan receptor γt, and demethylation of the forkhead box P3 (FOXP3) locus. The composition and diversity of the gastrointestinal microbiota is measurably affected by perinatal H pylori exposure. Conclusion: We conclude that exposure to H pylori has consequences not only for the carrier but also for subsequent generations that can be exploited for interventional purposes. Keywords: Allergic airway inflammation; epigenetic regulation of allergy and asthma; immune regulation; immune tolerance; metagenomics; microbial interventions during pregnancy.

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