• Gadd45 proteins in immunity.

      Schmitz, Ingo; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2013)
      The vertebrate immune system protects the host against invading pathogens such as viruses, bacteria and parasites. It consists of an innate branch and an adaptive branch that provide immediate and long-lasting protection, respectively. As the immune system is composed of different cell types and distributed throughout the whole body, immune cells need to communicate with each other. Intercellular communication in the immune system is mediated by cytokines, which bind to specific receptors on the cell surface and activate intracellular signalling networks. Growth arrest and DNA damage-inducible 45 (Gadd45) proteins are important components of these intracellular signalling networks. They are induced by a number of cytokines and by bacterial lipopolysaccharide. Within the innate immune system, Gadd45 proteins are crucial for the differentiation of myeloid cells as well as for the function of granulocytes and macrophages. Moreover, Gadd45β regulates autophagy, a catabolic pathway that also degrades intracellular pathogens. Regarding adaptive immunity, Gadd45 proteins are especially well characterized in T cells. For instance, Gadd45β and Gadd45γ regulate cytokine expression and Th1 differentiation, while Gadd45α inhibits p38 kinase activation downstream of the T cell receptor. Due to their many functions in the immune system, deficiency in Gadd45 proteins causes autoimmune diseases and less efficient tumour immunosurveillance.
    • Generation of Foxp3CD25 Regulatory T-Cell Precursors Requires c-Rel and IκB.

      Schuster, Marc; Plaza-Sirvent, Carlos; Visekruna, Alexander; Huehn, Jochen; Schmitz, Ingo; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers, 2019-01-01)
      Next to the classical developmental route, in which first CD25 and subsequently Foxp3 are induced to generate thymic regulatory T (Treg) cells, an alternative route has been described. This alternative route is characterized by reciprocal induction of Foxp3 and CD25, with CD25 induction being required to rescue developing Treg cells from Foxp3-induced apoptosis. NF-κB has been demonstrated to be crucial for the development of thymic Treg cells via the classical route. However, its impact on the alternative route is poorly characterized. Using single and double deficient mice for key regulators of the classical route, c-Rel and IκBNS, we here demonstrate that NF-κB is essential for the generation of alternative CD25-Foxp3+ precursors, as well. Thus, c-Rel and IκBNS govern both routes of thymic Treg cell development.
    • Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition).

      Cossarizza, Andrea; Chang, Hyun-Dong; Radbruch, Andreas; Acs, Andreas; Adam, Dieter; Adam-Klages, Sabine; Agace, William W; Aghaeepour, Nima; Akdis, Mübeccel; Allez, Matthieu; et al. (Wiley, 2019-10-01)
      These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.
    • Gut memories do not fade: epigenetic regulation of lasting gut homing receptor expression in CD4(+) memory T cells.

      Szilagyi, B A; Triebus, J; Kressler, C; de Almeida, M; Tierling, S; Durek, P; Mardahl, M; Szilagyi, A; Floess, S; Huehn, Jochen; et al. (2017-11)
      The concept of a "topographical memory" in lymphocytes implies a stable expression of homing receptors mediating trafficking of lymphocytes back to the tissue of initial activation. However, a significant plasticity of the gut-homing receptor α4β7 was found in CD8(+) T cells, questioning the concept. We now demonstrate that α4β7 expression in murine CD4(+) memory T cells is, in contrast, imprinted and remains stable in the absence of the inducing factor retinoic acid (RA) or other stimuli from mucosal environments. Repetitive rounds of RA treatment enhanced the stability of de novo induced α4β7. A novel enhancer element in the murine Itga4 locus was identified that showed, correlating to stability, selective DNA demethylation in mucosa-seeking memory cells and methylation-dependent transcriptional activity in a reporter gene assay. This implies that epigenetic mechanisms contribute to the stabilization of α4β7 expression. Analogous DNA methylation patterns could be observed in the human ITGA4 locus, suggesting that its epigenetic regulation is conserved between mice and men. These data prove that mucosa-specific homing mediated by α4β7 is imprinted in CD4(+) memory T cells, reinstating the validity of the concept of "topographical memory" for mucosal tissues, and imply a critical role of epigenetic mechanisms.
    • Helicobacter pylori and its secreted immunomodulator VacA protect against anaphylaxis in experimental models of food allergy.

      Kyburz, Andreas; Urban, Sabine; Altobelli, Aleksandra; Floess, Stefan; Huehn, Jochen; Cover, Timothy L; Müller, Anne; Helmholtz Centre for infection research GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-08-12)
      Food allergy is an increasingly common health problem in Western populations. Epidemiological studies have suggested both positive and negative associations between food allergy and infection with the gastric bacterium Helicobacter pylori.
    • A Hypermorphic Allele Contributes to Impaired Thymic Deletion of Autoreactive Diabetogenic CD8 T Cells in NOD Mice.

      Presa, Maximiliano; Racine, Jeremy J; Dwyer, Jennifer R; Lamont, Deanna J; Ratiu, Jeremy J; Sarsani, Vishal Kumar; Chen, Yi-Guang; Geurts, Aron; Schmitz, Ingo; Stearns, Timothy; et al. (American Association of Immunologists, 2018-10-01)
      In both NOD mice and humans, the development of type 1 diabetes (T1D) is dependent in part on autoreactive CD8+ T cells recognizing pancreatic β cell peptides presented by often quite common MHC class I variants. Studies in NOD mice previously revealed that the common H2-Kd and/or H2-Db class I molecules expressed by this strain aberrantly lose the ability to mediate the thymic deletion of pathogenic CD8+ T cell responses through interactions with T1D susceptibility genes outside the MHC. A gene(s) mapping to proximal chromosome 7 was previously shown to be an important contributor to the failure of the common class I molecules expressed by NOD mice to mediate the normal thymic negative selection of diabetogenic CD8+ T cells. Using an inducible model of thymic negative selection and mRNA transcript analyses, we initially identified an elevated Nfkbid expression variant as a likely NOD-proximal chromosome 7 region gene contributing to impaired thymic deletion of diabetogenic CD8+ T cells. CRISPR/Cas9-mediated genetic attenuation of Nfkbid expression in NOD mice resulted in improved negative selection of autoreactive diabetogenic AI4 and NY8.3 CD8+ T cells. These results indicated that allelic variants of Nfkbid contribute to the efficiency of intrathymic deletion of diabetogenic CD8+ T cells. However, although enhancing thymic deletion of pathogenic CD8+ T cells, ablating Nfkbid expression surprisingly accelerated T1D onset that was associated with numeric decreases in both regulatory T and B lymphocytes in NOD mice.
    • IFN-γ Producing Th1 Cells Induce Different Transcriptional Profiles in Microglia and Astrocytes.

      Prajeeth, Chittappen K; Dittrich-Breiholz, Oliver; Talbot, Steven R; Robert, Philippe A; Huehn, Jochen; Stangel, Martin; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany.; BRICS, Braunschweiger Zentrum für Systembiologie, Rebenring 56,38106 Braunschweig, Germany. (2018-01-01)
      Autoreactive T cells that infiltrate into the central nervous system (CNS) are believed to have a significant role in mediating the pathology of neuroinflammatory diseases like multiple sclerosis. Their interaction with microglia and astrocytes in the CNS is crucial for the regulation of neuroinflammatory processes. Our previous work demonstrated that effectors secreted by Th1 and Th17 cells have different capacities to influence the phenotype and function of glial cells. We have shown that Th1-derived effectors altered the phenotype and function of both microglia and astrocytes whereas Th17-derived effectors induced direct effects only on astrocytes but not on microglia. Here we investigated if effector molecules associated with IFN-γ producing Th1 cells induced different gene expression profiles in microglia and astrocytes. We performed a microarray analysis of RNA isolated from microglia and astrocytes treated with medium and Th-derived culture supernatants and compared the gene expression data. By using the criteria of 2-fold change and a false discovery rate of 0.01 (corrected
    • Impact of CCR7 on T-Cell Response and Susceptibility to Yersinia pseudotuberculosis Infection.

      Pezoldt, Joern; Pisano, Fabio; Heine, Wiebke; Pasztoi, Maria; Rosenheinrich, Maik; Nuss, Aaron M; Pils, Marina C; Prinz, Immo; Förster, Reinhold; Huehn, Jochen; et al. (2017-09-15)
      To successfully limit pathogen dissemination, an immunological link between the entry tissue of the pathogen and the underlying secondary lymphoid organs (SLOs) needs to be established to prime adaptive immune responses. Here, the prerequisite of CCR7 to mount host immune responses within SLOs during gastrointestinal Yersinia pseudotuberculosis infection to limit pathogen spread was investigated.
    • Inhibition of the JAK/STAT Signaling Pathway in Regulatory T Cells Reveals a Very Dynamic Regulation of Foxp3 Expression.

      Goldstein, Jérémie D; Burlion, Aude; Zaragoza, Bruno; Sendeyo, Kélhia; Polansky, Julia K; Huehn, Jochen; Piaggio, Eliane; Salomon, Benoit L; Marodon, Gilles; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016)
      The IL-2/JAK3/STAT-5 signaling pathway is involved on the initiation and maintenance of the transcription factor Foxp3 in regulatory T cells (Treg) and has been associated with demethylation of the intronic Conserved Non Coding Sequence-2 (CNS2). However, the role of the JAK/STAT pathway in controlling Foxp3 in the short term has been poorly investigated. Using two different JAK/STAT pharmacological inhibitors, we observed a detectable loss of Foxp3 after 10 min. of treatment that affected 70% of the cells after one hour. Using cycloheximide, a general inhibitor of mRNA translation, we determined that Foxp3, but not CD25, has a high turnover in IL-2 stimulated Treg. This reduction was correlated with a rapid reduction of Foxp3 mRNA. This loss of Foxp3 was associated with a loss in STAT-5 binding to the CNS2, which however remains demethylated. Consequently, Foxp3 expression returns to normal level upon restoration of basal JAK/STAT signaling in vivo. Reduced expression of several genes defining Treg identity was also observed upon treatment. Thus, our results demonstrate that Foxp3 has a rapid turn over in Treg partly controlled at the transcriptional level by the JAK/STAT pathway.
    • Intact interleukin-10 receptor signaling protects from hippocampal damage elicited by experimental neurotropic virus infection of SJL mice.

      Uhde, Ann-Kathrin; Ciurkiewicz, Malgorzata; Herder, Vanessa; Khan, Muhammad Akram; Hensel, Niko; Claus, Peter; Beckstette, Michael; Teich, René; Floess, Stefan; Baumgärtner, Wolfgang; et al. (2018-04-17)
      Theiler's murine encephalomyelitis virus (TMEV) infection represents an experimental mouse model to study hippocampal damage induced by neurotropic viruses. IL-10 is a pleiotropic cytokine with profound anti-inflammatory properties, which critically controls immune homeostasis. In order to analyze IL-10R signaling following virus-induced polioencephalitis, SJL mice were intracerebrally infected with TMEV. RNA-based next generation sequencing revealed an up-regulation of Il10, Il10rα and further genes involved in IL-10 downstream signaling, including Jak1, Socs3 and Stat3 in the brain upon infection. Subsequent antibody-mediated blockade of IL-10R signaling led to enhanced hippocampal damage with neuronal loss and increased recruitment of CD3+ T cells, CD45R+ B cells and an up-regulation of Il1α mRNA. Increased expression of Tgfβ and Foxp3 as well as accumulation of Foxp3+ regulatory T cells and arginase-1+ macrophages/microglia was detected in the hippocampus, representing a potential compensatory mechanism following disturbed IL-10R signaling. Additionally, an increased peripheral Chi3l3 expression was found in spleens of infected mice, which may embody reactive regulatory mechanisms for prevention of excessive immunopathology. The present study highlights the importance of IL-10R signaling for immune regulation and its neuroprotective properties in the context of an acute neurotropic virus infection.
    • Intracellular Staphylococcus aureus eludes selective autophagy by activating a host cell kinase.

      Neumann, Yvonne; Bruns, Svenja A; Rohde, Manfred; Prajsnar, Tomasz K; Foster, Simon J; Schmitz, Ingo; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-11)
      Autophagy, a catabolic pathway of lysosomal degradation, acts not only as an efficient recycle and survival mechanism during cellular stress, but also as an anti-infective machinery. The human pathogen Staphylococcus aureus (S. aureus) was originally considered solely as an extracellular bacterium, but is now recognized additionally to invade host cells, which might be crucial for persistence. However, the intracellular fate of S. aureus is incompletely understood. Here, we show for the first time induction of selective autophagy by S. aureus infection, its escape from autophagosomes and proliferation in the cytoplasm using live cell imaging. After invasion, S. aureus becomes ubiquitinated and recognized by receptor proteins such as SQSTM1/p62 leading to phagophore recruitment. Yet, S. aureus evades phagophores and prevents further degradation by a MAPK14/p38α MAP kinase-mediated blockade of autophagy. Our study demonstrates a novel bacterial strategy to block autophagy and secure survival inside the host cell.
    • The invasin D protein fromYersinia pseudotuberculosisselectively binds the Fab region of host antibodies and affects colonization of the intestine.

      Sadana, Pooja; Geyer, Rebecca; Pezoldt, Joern; Helmsing, Saskia; Huehn, Jochen; Hust, Michael; Dersch, Petra; Scrima, Andrea; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-03-13)
      Yersinia pseudotuberculosis is a Gram-negative bacterium and zoonotic pathogen responsible for a wide range of diseases, ranging from mild diarrhea, enterocolitis, lymphatic adenitis to persistent local inflammation. TheY. pseudotuberculosisinvasin D (InvD) molecule belongs to the invasin (InvA)-type autotransporter proteins, but its structure and function remain unknown. In this study, we present the first crystal structure of InvD, analyzed its expression and function in a murine infection model, and identified its target molecule in the host. We found that InvD is induced at 37°C and expressed in vivo2-4 days after infection, indicating that InvD is a virulence factor. During infection, InvD was expressed in all parts of the intestinal tract, but not in deeper lymphoid tissues. The crystal structure of the C-terminal adhesion domain of InvD revealed a distinct Ig-related fold, that, apart from the canonical β-sheets, comprises various modifications of and insertions into the Ig-core structure. We identified the Fab fragment of host-derived IgG/IgA antibodies as the target of the adhesion domain. Phage display panning and flow cytometry data further revealed that InvD exhibits a preferential binding specificity toward antibodies with VH3/VK1 variable domains and that it is specifically recruited to a subset of B cells. This finding suggests that InvD modulates Ig functions in the intestine and affects direct interactions with a subset of cell surface-exposed B-cell receptors. In summary, our results provide extensive insights into the structure of InvD and its specific interaction with the target molecule in the host.
    • IRAP+ endosomes restrict TLR9 activation and signaling.

      Babdor, Joel; Descamps, Delphyne; Adiko, Aimé Cézaire; Tohmé, Mira; Maschalidi, Sophia; Evnouchidou, Irini; Vasconcellos, Luiz Ricardo; De Luca, Mariacristina; Mauvais, Francois-Xavier; Garfa-Traore, Meriem; et al. (2017-05)
      The retention of intracellular Toll-like receptors (TLRs) in the endoplasmic reticulum prevents their activation under basal conditions. TLR9 is activated by sensing ligands in specific endosomal-lysosomal compartments. Here we identified IRAP+ endosomes as major cellular compartments for the early steps of TLR9 activation in dendritic cells (DCs). Both TLR9 and its ligand, the dinucleotide CpG, were present as cargo in IRAP+ endosomes. In the absence of the aminopeptidase IRAP, the trafficking of CpG and TLR9 to lysosomes and signaling via TLR9 were enhanced in DCs and in mice following bacterial infection. IRAP stabilized CpG-containing endosomes by interacting with the actin-nucleation factor FHOD4, which slowed the trafficking of TLR9 toward lysosomes. Thus, endosomal retention of TLR9 via the interaction of IRAP with the actin cytoskeleton is a mechanism that prevents hyper-activation of TLR9 in DCs.
    • Limited role of regulatory T cells during acute Theiler virus-induced encephalitis in resistant C57BL/6 mice

      Prajeeth, Chittappen K; Beineke, Andreas; Iskandar, Cut D; Gudi, Viktoria; Herder, Vanessa; Gerhauser, Ingo; Haist, Verena; Teich, René; Huehn, Jochen; Baumgärtner, Wolfgang; et al. (2014-11-13)
      Abstract Background Theiler’s murine encephalomyelitis virus (TMEV) infection represents a commonly used infectious animal model to study various aspects of the pathogenesis of multiple sclerosis (MS). In susceptible SJL mice, dominant activity of Foxp3+ CD4+ regulatory T cells (Tregs) in the CNS partly contributes to viral persistence and progressive demyelination. On the other hand, resistant C57BL/6 mice rapidly clear the virus by mounting a strong antiviral immune response. However, very little is known about the role of Tregs in regulating antiviral responses during acute encephalitis in resistant mouse strains. Methods In this study, we used DEREG mice that express the diphtheria toxin (DT) receptor under control of the foxp3 locus to selectively deplete Foxp3+ Tregs by injection of DT prior to infection and studied the effect of Treg depletion on the course of acute Theiler’s murine encephalomyelitis (TME). Results As expected, DEREG mice that are on a C57BL/6 background were resistant to TMEV infection and cleared the virus within days of infection, regardless of the presence or absence of Tregs. Nevertheless, in the absence of Tregs we observed priming of stronger effector T cell responses in the periphery, which subsequently resulted in a transient increase in the frequency of IFNγ-producing T cells in the brain at an early stage of infection. Histological and flow cytometric analysis revealed that this transiently increased frequency of brain-infiltrating IFNγ-producing T cells in Treg-depleted mice neither led to an augmented antiviral response nor enhanced inflammation-mediated tissue damage. Intriguingly, Treg depletion did not change the expression of IL-10 in the infected brain, which might play a role for dampening the inflammatory damage caused by the increased number of effector T cells. Conclusion We therefore propose that unlike susceptible mice strains, interfering with the Treg compartment of resistant mice only has negligible effects on virus-induced pathologies in the CNS. Furthermore, in the absence of Tregs, local anti-inflammatory mechanisms might limit the extent of damage caused by strong anti-viral response in the CNS.
    • Limited role of regulatory T cells during acute Theiler virus-induced encephalitis in resistant C57BL/6 mice.

      Prajeeth, Chittappen K; Beineke, Andreas; Iskandar, Cut Dahlia; Gudi, Viktoria; Herder, Vanessa; Gerhauser, Ingo; Haist, Verena; Teich, René; Huehn, Jochen; Baumgärtner, Wolfgang; et al. (2014)
      Theiler's murine encephalomyelitis virus (TMEV) infection represents a commonly used infectious animal model to study various aspects of the pathogenesis of multiple sclerosis (MS). In susceptible SJL mice, dominant activity of Foxp3(+) CD4(+) regulatory T cells (Tregs) in the CNS partly contributes to viral persistence and progressive demyelination. On the other hand, resistant C57BL/6 mice rapidly clear the virus by mounting a strong antiviral immune response. However, very little is known about the role of Tregs in regulating antiviral responses during acute encephalitis in resistant mouse strains.
    • Longitudinal proliferation mapping in vivo reveals NADPH oxidase-mediated dampening of Staphylococcus aureus growth rates within neutrophils.

      Seiß, Elena A; Krone, Anna; Formaglio, Pauline; Goldmann, Oliver; Engelmann, Susanne; Schraven, Burkhart; Medina, Eva; Müller, Andreas J; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Nature publishing group, 2019-04-05)
      Upon the onset of inflammatory responses, bacterial pathogens are confronted with altered tissue microenvironments which can critically impact on their metabolic activity and growth. Changes in these parameters have however remained difficult to analyze over time, which would be critical to dissect the interplay between the host immune response and pathogen physiology. Here, we established an in vivo biosensor for measuring the growth rates of Staphylococcus aureus (S. aureus) on a single cell-level over days in an ongoing cutaneous infection. Using intravital 2-photon imaging and quantitative fluorescence microscopy, we show that upon neutrophil recruitment to the infection site and bacterial uptake, non-lethal dampening of S. aureus proliferation occurred. This inhibition was supported by NADPH oxidase activity. Therefore, reactive oxygen production contributes to pathogen containment within neutrophils not only by killing S. aureus, but also by restricting the growth rate of the bacterium.
    • A mathematical model of the impact of insulin secretion dynamics on selective hepatic insulin resistance.

      Zhao, Gang; Wirth, Dagmar; Schmitz, Ingo; Meyer-Hermann, Michael; Braunschweiger Zentrum für Systembiologie, Rebenring 56, 38106, Germany. (2017-11-08)
      Physiological insulin secretion exhibits various temporal patterns, the dysregulation of which is involved in diabetes development. We analyzed the impact of first-phase and pulsatile insulin release on glucose and lipid control with various hepatic insulin signaling networks. The mathematical model suggests that atypical protein kinase C (aPKC) undergoes a bistable switch-on and switch-off, under the control of insulin receptor substrate 2 (IRS2). The activation of IRS1 and IRS2 is temporally separated due to the inhibition of IRS1 by aPKC. The model further shows that the timing of aPKC switch-off is delayed by reduced first-phase insulin and reduced amplitude of insulin pulses. Based on these findings, we propose a sequential model of postprandial hepatic control of glucose and lipid by insulin, according to which delayed aPKC switch-off contributes to selective hepatic insulin resistance, which is a long-standing paradox in the field.
    • Memantine potentiates cytarabine-induced cell death of acute leukemia correlating with inhibition of K1.3 potassium channels, AKT and ERK1/2 signaling.

      Lowinus, Theresa; Heidel, Florian H; Bose, Tanima; Nimmagadda, Subbaiah Chary; Schnöder, Tina; Cammann, Clemens; Schmitz, Ingo; Seifert, Ulrike; Fischer, Thomas; Schraven, Burkhart; et al. (BMC, 2019-01-16)
      Treatment of acute leukemia is challenging and long-lasting remissions are difficult to induce. Innovative therapy approaches aim to complement standard chemotherapy to improve drug efficacy and decrease toxicity. Promising new therapeutic targets in cancer therapy include voltage-gated K We analyzed acute lymphoid (Jurkat, CEM) and myeloid (HL-60, Molm-13, OCI-AML-3) leukemia cell lines and patients' acute leukemic blasts after treatment with either drug alone or the combination of cytarabine and memantine. Patch-clamp analysis was performed to evaluate inhibition of K Our study demonstrates that memantine inhibits K Our study underlines inhibition of K
    • Mesenteric lymph node stromal cell-derived extracellular vesicles contribute to peripheral de novo induction of Foxp3(+) regulatory T cells.

      Pasztoi, Maria; Pezoldt, Joern; Beckstette, Michael; Lipps, Christoph; Wirth, Dagmar; Rohde, M; Paloczi, Krisztina; Buzas, Edit Iren; Huehn, Jochen; Helmholtz Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-08-18)
      Intestinal regulatory T cells (Tregs) are fundamental in peripheral tolerance toward commensals and food-borne antigens. Accordingly, gut-draining mesenteric lymph nodes (mLNs) represent a site of efficient peripheral de novo Treg induction when compared to skin-draining peripheral LNs (pLNs), and we had recently shown that LN stromal cells substantially contribute to this process. Here, we aimed to unravel the underlying molecular mechanisms and generated immortalized fibroblastic reticular cell lines (iFRCs) from mLNs and pLNs, allowing unlimited investigation of this rare stromal cell subset. In line with our previous findings, mLN-iFRCs showed a higher Treg-inducing capacity when compared to pLN-iFRCs. RNA-seq analysis focusing on secreted molecules revealed a more tolerogenic phenotype of mLN- as compared to pLN-iFRCs. Remarkably, mLN-iFRCs produced substantial numbers of microvesicles (MVs) that carried elevated levels of TGF-β when compared to pLN-iFRC-derived MVs, and these novel players of intercellular communication were shown to be responsible for the tolerogenic properties of mLN-iFRCs. Thus, stromal cells originating from mLNs contribute to peripheral tolerance by fostering de novo Treg induction using TGF-β-carrying MVs. This finding provides novel insights into the subcellular/molecular mechanisms of de novo Treg induction and might serve as promising tool for future therapeutic applications to treat inflammatory disorders.
    • Microbiome Dependent Regulation of Tregs and Th17 Cells in Mucosa.

      Pandiyan, Pushpa; Bhaskaran, Natarajan; Zou, Mangge; Schneider, Elizabeth; Jayaraman, Sangeetha; Huehn, Jochen; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers, 2019-01-01)
      Mammals co-exist with resident microbial ecosystem that is composed of an incredible number and diversity of bacteria, viruses and fungi. Owing to direct contact between resident microbes and mucosal surfaces, both parties are in continuous and complex interactions resulting in important functional consequences. These interactions govern immune homeostasis, host response to infection, vaccination and cancer, as well as predisposition to metabolic, inflammatory and neurological disorders. Here, we discuss recent studies on direct and indirect effects of resident microbiota on regulatory T cells (Tregs) and Th17 cells at the cellular and molecular level. We review mechanisms by which commensal microbes influence mucosa in the context of bioactive molecules derived from resident bacteria, immune senescence, chronic inflammation and cancer. Lastly, we discuss potential therapeutic applications of microbiota alterations and microbial derivatives, for improving resilience of mucosal immunity and combating immunopathology.