Publications by authors named "Thomas Hehlgans"

47 Publications

Single-cell chromatin accessibility landscape identifies tissue repair program in human regulatory T cells.

Immunity 2021 Apr 30;54(4):702-720.e17. Epub 2021 Mar 30.

Regensburg Center for Interventional Immunology (RCI); Chair for Immunology, University Regensburg, 93053 Regensburg, Germany. Electronic address:

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 BATFCCR8 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 BATFCCR8 Treg cells from healthy tissue share features with tumor-resident Treg cells, highlighting the importance of understanding the context-specific functions of these cells.
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http://dx.doi.org/10.1016/j.immuni.2021.03.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8050210PMC
April 2021

Group 3 Innate Lymphoid Cells Program a Distinct Subset of IL-22BP-Producing Dendritic Cells Demarcating Solitary Intestinal Lymphoid Tissues.

Immunity 2020 11;53(5):1015-1032.e8

Laboratory of Innate Immunity, Department of Microbiology, Infectious Diseases and Immunology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany; Berlin Institute of Health (BIH), Anna-Louisa-Karsch Strasse 2, 10117 Berlin, Germany; Mucosal and Developmental Immunology, Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, 10117 Berlin, Germany. Electronic address:

Solitary intestinal lymphoid tissues such as cryptopatches (CPs) and isolated lymphoid follicles (ILFs) constitute steady-state activation hubs containing group 3 innate lymphoid cells (ILC3) that continuously produce interleukin (IL)-22. The outer surface of CPs and ILFs is demarcated by a poorly characterized population of CD11c cells. Using genome-wide single-cell transcriptional profiling of intestinal mononuclear phagocytes and multidimensional flow cytometry, we found that CP- and ILF-associated CD11c cells were a transcriptionally distinct subset of intestinal cDCs, which we term CIA-DCs. CIA-DCs required programming by CP- and ILF-resident CCR6 ILC3 via lymphotoxin-β receptor signaling in cDCs. CIA-DCs differentially expressed genes associated with immunoregulation and were the major cellular source of IL-22 binding protein (IL-22BP) at steady state. Mice lacking CIA-DC-derived IL-22BP exhibited diminished expression of epithelial lipid transporters, reduced lipid resorption, and changes in body fat homeostasis. Our findings provide insight into the design principles of an immunoregulatory checkpoint controlling nutrient absorption.
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http://dx.doi.org/10.1016/j.immuni.2020.10.012DOI Listing
November 2020

Lymphoma Angiogenesis Is Orchestrated by Noncanonical Signaling Pathways.

Cancer Res 2020 03 13;80(6):1316-1329. Epub 2020 Jan 13.

Translational Tumorimmunology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.

Tumor-induced remodeling of the microenvironment relies on the formation of blood vessels, which go beyond the regulation of metabolism, shaping a maladapted survival niche for tumor cells. In high-grade B-cell lymphoma, angiogenesis correlates with poor prognosis, but attempts to target established proangiogenic pathways within the vascular niche have been inefficient. Here, we analyzed -driven B-cell lymphoma-induced angiogenesis in mice. A few lymphoma cells were sufficient to activate the angiogenic switch in lymph nodes. A unique morphology of dense microvessels emerged without obvious tip cell guidance and reliance on blood endothelial cell (BEC) proliferation. The transcriptional response of BECs was inflammation independent. Conventional HIF1α or Notch signaling routes prevalent in solid tumors were not activated. Instead, a nonconventional hypersprouting morphology was orchestrated by lymphoma-provided VEGFC and lymphotoxin (LT). Interference with VEGF receptor-3 and LTβ receptor signaling pathways abrogated lymphoma angiogenesis, thus revealing targets to block lymphomagenesis. SIGNIFICANCE: In lymphoma, transcriptomes and morphogenic patterns of the vasculature are distinct from processes in inflammation and solid tumors. Instead, LTβR and VEGFR3 signaling gain leading roles and are targets for lymphomagenesis blockade. http://cancerres.aacrjournals.org/content/canres/80/6/1316/F1.large.jpg.
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http://dx.doi.org/10.1158/0008-5472.CAN-19-1493DOI Listing
March 2020

Origin and differentiation trajectories of fibroblastic reticular cells in the splenic white pulp.

Nat Commun 2019 04 15;10(1):1739. Epub 2019 Apr 15.

Institute of Immunobiology, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland.

The splenic white pulp is underpinned by poorly characterized stromal cells that demarcate distinct immune cell microenvironments. Here we establish fibroblastic reticular cell (FRC)-specific fate-mapping in mice to define their embryonic origin and differentiation trajectories. Our data show that all reticular cell subsets descend from multipotent progenitors emerging at embryonic day 19.5 from periarterial progenitors. Commitment of FRC progenitors is concluded during the first week of postnatal life through occupation of niches along developing central arterioles. Single cell transcriptomic analysis facilitated deconvolution of FRC differentiation trajectories and indicated that perivascular reticular cells function both as adult lymphoid organizer cells and mural cell progenitors. The lymphotoxin-β receptor-independent sustenance of postnatal progenitor stemness unveils that systemic immune surveillance in the splenic white pulp is governed through subset specification of reticular cells from a multipotent periarterial progenitor cell. In sum, the finding that discrete signaling events in perivascular niches determine the differentiation trajectories of reticular cell networks explains the development of distinct microenvironmental niches in secondary and tertiary lymphoid tissues that are crucial for the induction and regulation of innate and adaptive immune processes.
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http://dx.doi.org/10.1038/s41467-019-09728-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465367PMC
April 2019

Chronic Inflammation Increases the Sensitivity of Mouse Treg for TNFR2 Costimulation.

Front Immunol 2017 7;8:1471. Epub 2017 Nov 7.

Institute of Immunology, University of Regensburg, Regensburg, Germany.

TNF receptor type 2 (TNFR2) has gained attention as a costimulatory receptor for T cells and as critical factor for the development of regulatory T cells (Treg) and myeloid suppressor cells. Using the TNFR2-specific agonist TNCscTNF80, direct effects of TNFR2 activation on myeloid cells and T cells were investigated in mice. , TNCscTNF80 induced T cell proliferation in a costimulatory fashion, and also supported expansion of Treg cells. In addition, activation of TNFR2 retarded differentiation of bone marrow-derived immature myeloid cells in culture and reduced their suppressor function. application of TNCscTNF80-induced mild myelopoiesis in naïve mice without affecting the immune cell composition. Already a single application expanded Treg cells and improved suppression of CD4 T cells in mice with chronic inflammation. By contrast, multiple applications of the TNFR2 agonist were required to expand Treg cells in naïve mice. Improved suppression of T cell proliferation depended on expression of TNFR2 by T cells in mice repeatedly treated with TNCscTNF80, without a major contribution of TNFR2 on myeloid cells. Thus, TNFR2 activation on T cells in naïve mice can lead to immune suppression . These findings support the important role of TNFR2 for Treg cells in immune regulation.
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http://dx.doi.org/10.3389/fimmu.2017.01471DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681910PMC
November 2017

The association between acute graft-versus-host disease and antimicrobial peptide expression in the gastrointestinal tract after allogeneic stem cell transplantation.

PLoS One 2017 21;12(9):e0185265. Epub 2017 Sep 21.

Department of Hematology and Oncology, Internal Medicine III, University Medical Center, Regensburg, Germany.

Intestinal microbiota disruption is associated with acute gastrointestinal (GI) Graft-versus-Host Disease (GvHD) and poor outcome after allogeneic stem cell transplantation (ASCT). Here, in a retrospective analysis of 200 patients undergoing ASCT at the Regensburg University Medical Center, we assessed the relative expression of Paneth cell antimicrobial peptides (AMPs), Human Defensins (HD) 5 and 6 and regenerating islet-derived 3α (Reg3α), in 292 human intestinal biopsies as well as Reg3α serum levels in relation to acute GI GvHD. In the absence of GI GvHD, the relative expression of Paneth cell AMPs was significantly higher in the small intestine (duodenum to ileum) than in the stomach and large intestine (cecum to rectum) for Reg3α (p≤0.001), HD5 (p≤0.002) and HD6 (p≤0.02). Acute stage 2-4 GI GvHD was associated with reduced expression of AMPs in the small intestine (p≤0.01) in comparison to stage 0-1 disease, accompanied by a decrease in Paneth cell count in case of severe acute GI GvHD (p<0.001). The opposite held true for the large intestine as we found stage 2-4 GI GvHD correlated with significantly higher expression of HD5, HD6, and Reg3α compared to mild or no acute GI GvHD (p≤0.002). Severe GI GvHD in both the lower and the upper GI tract also correlated with higher serum concentrations of Reg3α (p = 0.002). As indirect markers of intestinal microbiome diversity low levels of urinary 3-indoxyl sulfate levels were associated with severe stages of acute GI GvHD compared to mild stage or no acute GI GvHD (p = 0.05). In conclusion, acute GI GvHD correlates with intestinal expression of HD5, HD6 and Reg3α as well as Reg3α serum levels and is associated with intestinal dysbiosis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185265PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608405PMC
October 2017

Lymphatic Endothelial Cells Control Initiation of Lymph Node Organogenesis.

Immunity 2017 07 11;47(1):80-92.e4. Epub 2017 Jul 11.

Institute of Immunobiology, Kantonsspital St. Gallen, St. Gallen, Switzerland. Electronic address:

Lymph nodes (LNs) are strategically situated throughout the body at junctures of the blood vascular and lymphatic systems to direct immune responses against antigens draining from peripheral tissues. The current paradigm describes LN development as a programmed process that is governed through the interaction between mesenchymal lymphoid tissue organizer (LTo) cells and hematopoietic lymphoid tissue inducer (LTi) cells. Using cell-type-specific ablation of key molecules involved in lymphoid organogenesis, we found that initiation of LN development is dependent on LTi-cell-mediated activation of lymphatic endothelial cells (LECs) and that engagement of mesenchymal stromal cells is a succeeding event. LEC activation was mediated mainly by signaling through receptor activator of NF-κB (RANK) and the non-canonical NF-κB pathway and was steered by sphingosine-1-phosphate-receptor-dependent retention of LTi cells in the LN anlage. Finally, the finding that pharmacologically enforced interaction between LTi cells and LECs promotes ectopic LN formation underscores the central LTo function of LECs.
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http://dx.doi.org/10.1016/j.immuni.2017.05.008DOI Listing
July 2017

Human beta-defensin-2 and -3 enhance pro-inflammatory cytokine expression induced by TLR ligands via ATP-release in a P2X7R dependent manner.

Immunobiology 2016 11 19;221(11):1259-65. Epub 2016 Jun 19.

Institute of Immunology, University of Regensburg, 93053 Regensburg, Germany. Electronic address:

Our previous results indicate that HBD2 and HBD3 are chemotactic for a broad spectrum of leukocytes in a CCR6- and CCR2-dependent manner. In this study we report that pre-stimulation of primary human macrophages or THP-1 cells with HBD2 or HBD3 results in a synergistic, enhanced expression of pro-inflammatory cytokines and chemokines induced by TLR ligand re-stimulation. Experiments using specific inhibitors of the ATP-gated channel receptor P2X7 or its functional ligand ATP, suggest that the enhanced expression of pro-inflammatory cytokines and chemokines seems to be mediated by P2X7R. Furthermore, our data provide evidence that beta-defensins do not directly interact with P2X7R but rather induce the release of intracellular ATP. Interference with ATP release abrogated the synergistic effect mediated by HBD2 and HBD3 pre-stimulation in THP-1 cells. However, extracellular ATP alone seems not to be sufficient to elicit the enhanced synergistic effect on cytokine and chemokine expression observed by pre-stimulation of primary human macrophages or THP-1 cells with HBD2 or HBD3. Collectively, our findings provide new insights into the molecular mechanisms how HBD2 and HBD3 interact with cells of myeloid origin and demonstrate their immuno-modulating functions during innate immune responses.
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http://dx.doi.org/10.1016/j.imbio.2016.06.006DOI Listing
November 2016

IL-10 from marginal zone precursor B cells controls the differentiation of Th17, Tfh and Tfr cells in transplantation tolerance.

Immunol Lett 2016 Feb 6;170:52-63. Epub 2016 Jan 6.

Departments of Surgery and Microbiology and Immunology, and Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, United States. Electronic address:

B cells are known to control CD4T cell differentiation in secondary lymphoid tissues. We hypothesized that IL-10 expression by marginal zone precursor (MZP) regulatory B cells controls the differentiation and positioning of effector and regulatory T cells during tolerization. Costimulatory blockade with donor-specific transfusion (DST) and anti-CD40L mAb in C57BL/6 mice induced tolerance to allogeneic cardiac allograft. B cell depletion or IL-10 deficiency in B cells prevented tolerance, resulting in decreased follicular regulatory CD4(+) T cells (Tfr) and increased IL-21 expression by T follicular helper (Tfh) cells in the B cell and T cell zones. IL-21 acted with IL-6 to induce CCR6(+) Th17 that caused rejection. Deficiency or blockade of IL-6, IL-21, IL-21R, or CCR6 prevented B cell depletion-induced acute cellular rejection; while agonistic mCCL20-Ig induced rejection. Adoptive transfer of IL-10(+/+) MZP in tolerogen treated CD19-Cre(+/-):IL-10(fl/fl) mice rescued the localization of Tfh and Tfr cells in the B cell follicle and prevented allograft rejection. MZP B cell IL-10 is necessary for tolerance and controls the differentiation and position of Th17, Tfh and Tfr cells in secondary lymphoid tissues. This has implications for understanding tolerance induction and how B cell depletion may prevent tolerance.
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http://dx.doi.org/10.1016/j.imlet.2016.01.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740190PMC
February 2016

Access to follicular dendritic cells is a pivotal step in murine chronic lymphocytic leukemia B-cell activation and proliferation.

Cancer Discov 2014 Dec 24;4(12):1448-65. Epub 2014 Sep 24.

Department of Tumor Genetics and Immunogenetics, Max-Delbrück-Center for Molecular Medicine, MDC, Berlin, Germany.

Unlabelled: In human chronic lymphocytic leukemia (CLL) pathogenesis, B-cell antigen receptor signaling seems important for leukemia B-cell ontogeny, whereas the microenvironment influences B-cell activation, tumor cell lodging, and provision of antigenic stimuli. Using the murine Eμ-Tcl1 CLL model, we demonstrate that CXCR5-controlled access to follicular dendritic cells confers proliferative stimuli to leukemia B cells. Intravital imaging revealed a marginal zone B cell-like leukemia cell trafficking route. Murine and human CLL cells reciprocally stimulated resident mesenchymal stromal cells through lymphotoxin-β-receptor activation, resulting in CXCL13 secretion and stromal compartment remodeling. Inhibition of lymphotoxin/lymphotoxin-β-receptor signaling or of CXCR5 signaling retards leukemia progression. Thus, CXCR5 activity links tumor cell homing, shaping a survival niche, and access to localized proliferation stimuli.

Significance: CLL and other indolent lymphoma are not curable and usually relapse after treatment, a process in which the tumor microenvironment plays a pivotal role. We dissect the consecutive steps of CXCR5-dependent tumor cell lodging and LTβR-dependent stroma-leukemia cell interaction; moreover, we provide therapeutic solutions to interfere with this reciprocal tumor-stroma cross-talk.
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http://dx.doi.org/10.1158/2159-8290.CD-14-0096DOI Listing
December 2014

Metagenomic analysis of the stool microbiome in patients receiving allogeneic stem cell transplantation: loss of diversity is associated with use of systemic antibiotics and more pronounced in gastrointestinal graft-versus-host disease.

Biol Blood Marrow Transplant 2014 May 31;20(5):640-5. Epub 2014 Jan 31.

Institute of Functional Genomics, University of Regensburg, Regensburg, Germany.

Next-generation sequencing of the hypervariable V3 region of the 16s rRNA gene isolated from serial stool specimens collected from 31 patients receiving allogeneic stem cell transplantation (SCT) was performed to elucidate variations in the composition of the intestinal microbiome in the course of allogeneic SCT. Metagenomic analysis was complemented by strain-specific enterococcal PCR and indirect assessment of bacterial load by liquid chromatography-tandem mass spectrometry of urinary indoxyl sulfate. At the time of admission, patients showed a predominance of commensal bacteria. After transplantation, a relative shift toward enterococci was observed, which was more pronounced under antibiotic prophylaxis and treatment of neutropenic infections. The shift was particularly prominent in patients that developed subsequently or suffered from active gastrointestinal (GI) graft-versus-host disease (GVHD). The mean proportion of enterococci in post-transplant stool specimens was 21% in patients who did not develop GI GVHD as compared with 46% in those that subsequently developed GI GVHD and 74% at the time of active GVHD. Enterococcal PCR confirmed predominance of Enterococcus faecium or both E. faecium and Enterococcus faecalis in these specimens. As a consequence of the loss of bacterial diversity, mean urinary indoxyl sulfate levels dropped from 42.5 ± 11 μmol/L to 11.8 ± 2.8 μmol/L in all post-transplant samples and to 3.5 ± 3 μmol/L in samples from patients with active GVHD. Our study reveals major microbiome shifts in the course of allogeneic SCT that occur in the period of antibiotic treatment but are more prominent in association with GI GVHD. Our data indicate early microbiome shifts and a loss of diversity of the intestinal microbiome that may affect intestinal inflammation in the setting of allogeneic SCT.
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http://dx.doi.org/10.1016/j.bbmt.2014.01.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4973578PMC
May 2014

LTβR expression on hematopoietic cells regulates acute inflammation and influences maturation of myeloid subpopulations.

Innate Immun 2014 Jul 12;20(5):461-70. Epub 2013 Aug 12.

Institute of Immunology, University of Regensburg, Regensburg, Germany.

Lymphotoxin beta-receptor (LTβR) is involved in the formation and maintenance of secondary lymphoid structures, as well as in the regulation of inflammatory responses. Because LTβR lymphoid structure formation continues to develop in infants, we compared two different chimera models: one using adult mice and the other using a transplantation model of neonatal mice. To elucidate the function of LTβR on lymphoid and non-lymphoid cells, we generated bone marrow chimeras on the wild type C57Bl/6 and the LTβR-deficient (LTβR(-/-)) background, and reconstituted the mice with bone marrow cells reciprocally. These chimeric mice were analyzed in the experimental model of acute dextran sulfate sodium-induced colitis. Interestingly, both models revealed not only equal reconstitution levels but also similar immunological responses: LTβR expression on stromal cells is essential for lymph node formation, whereas LTBR on hematopoietic cells is crucial for a decrease in inflammation. In addition, mice lacking LTβR on hematopoietic cells revealed (a) an increase of immature granulocytic cells in the spleen and (b) a reduced proportion of myeloid cells in peripheral blood and spleen expressing CD11b(+)Ly6C(+)Ly6G(-) (myeloid-derived suppressor cells expression profile). In conclusion, LTβR expression on hematopoietic cells seems to be involved in the down-regulation of acute inflammatory reactions paralleled by the appearance of immature myeloid cells.
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http://dx.doi.org/10.1177/1753425913497242DOI Listing
July 2014

Maturation of lymph node fibroblastic reticular cells from myofibroblastic precursors is critical for antiviral immunity.

Immunity 2013 May 25;38(5):1013-24. Epub 2013 Apr 25.

Institute of Immunobiology, Kantonal Hospital St. Gallen, 9007 St. Gallen, Switzerland.

The stromal scaffold of the lymph node (LN) paracortex is built by fibroblastic reticular cells (FRCs). Conditional ablation of lymphotoxin-β receptor (LTβR) expression in LN FRCs and their mesenchymal progenitors in developing LNs revealed that LTβR-signaling in these cells was not essential for the formation of LNs. Although T cell zone reticular cells had lost podoplanin expression, they still formed a functional conduit system and showed enhanced expression of myofibroblastic markers. However, essential immune functions of FRCs, including homeostatic chemokine and interleukin-7 expression, were impaired. These changes in T cell zone reticular cell function were associated with increased susceptibility to viral infection. Thus, myofibroblasic FRC precursors are able to generate the basic T cell zone infrastructure, whereas LTβR-dependent maturation of FRCs guarantees full immunocompetence and hence optimal LN function during infection.
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http://dx.doi.org/10.1016/j.immuni.2013.03.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7111182PMC
May 2013

Endothelial cell-specific lymphotoxin-β receptor signaling is critical for lymph node and high endothelial venule formation.

J Exp Med 2013 Mar 18;210(3):465-73. Epub 2013 Feb 18.

Institute of Immunobiology, Kantonal Hospital St. Gallen, CH-9007 St. Gallen, Switzerland.

The development of lymph nodes (LNs) and formation of LN stromal cell microenvironments is dependent on lymphotoxin-β receptor (LTβR) signaling. In particular, the LTβR-dependent crosstalk between mesenchymal lymphoid tissue organizer and hematopoietic lymphoid tissue inducer cells has been regarded as critical for these processes. Here, we assessed whether endothelial cell (EC)-restricted LTβR signaling impacts on LN development and the vascular LN microenvironment. Using EC-specific ablation of LTβR in mice, we found that conditionally LTβR-deficient animals failed to develop a significant proportion of their peripheral LNs. However, remnant LNs showed impaired formation of high endothelial venules (HEVs). Venules had lost their cuboidal shape, showed reduced segment length and branching points, and reduced adhesion molecule and constitutive chemokine expression. Due to the altered EC-lymphocyte interaction, homing of lymphocytes to peripheral LNs was significantly impaired. Thus, this study identifies ECs as an important LTβR-dependent lymphoid tissue organizer cell population and indicates that continuous triggering of the LTβR on LN ECs is critical for lymphocyte homeostasis.
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http://dx.doi.org/10.1084/jem.20121462DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3600902PMC
March 2013

Beta-defensins activate macrophages and synergize in pro-inflammatory cytokine expression induced by TLR ligands.

Immunobiology 2013 Jul 29;218(7):1005-11. Epub 2012 Nov 29.

Institute of Immunology, University of Regensburg, 93053 Regensburg, Germany.

Our previous studies indicated that mouse beta defensin 14 (mBD14, Defb14), a newly identified member of the beta-defensin super family, interacts with the chemokine receptors CCR2 and CCR6. In this study we report that pre-stimulation of primary mouse macrophages with mBD14 results in a synergistic, enhanced expression of pro-inflammatory cytokines and chemokines induced by TLR ligand re-stimulation. Experiments using specific inhibitors of G(i)-protein-coupled receptor signaling provide evidence that this effect seems to be mediated by a G(i)-protein-coupled receptor expressed on bone marrow derived macrophages. However, using primary macrophages derived from CCR6- and CCR2-deficient mice clearly demonstrated that the enhanced pro-inflammatory cytokine and chemokine expression is independent of the chemokine receptors CCR6 and CCR2. Additionally, signaling pathway analysis indicated that mBD14 is capable of inducing MAPK ERK1/2 phosphorylation and the induction of CD86 and F4/80 expression in bone marrow-derived macrophages after mBD14 stimulation. Collectively, our data indicate that β-defensins activate primary macrophages and enhance pro-inflammatory responses by using G(i)PCRs in order to support inflammatory reactions induced by TLR ligands.
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http://dx.doi.org/10.1016/j.imbio.2012.11.007DOI Listing
July 2013

Lymphotoxin-beta receptor signalling regulates cytokine expression via TRIM30α in a TRAF3-dependent manner.

Mol Immunol 2013 May 3;54(1):40-7. Epub 2012 Dec 3.

Institute of Immunology, University of Regensburg, 93053 Regensburg, Germany.

Our earlier studies indicated that activation of the lymphotoxin beta receptor (LTβR) by T cell derived LTα(1)β(2) regulates inflammatory cytokine expression. While characterizing the cellular and molecular mechanisms responsible for the down regulation of the inflammatory reaction after LTβR stimulation we were able to identify the specific induction of TRIM30α expression as a result of LTβR signalling in mouse macrophages. Furthermore, we could demonstrate that LTβR activation in these cells results in the down regulation of pro-inflammatory cytokine (e.g. TNF and IL-6) and mediator expression upon TLR4 and TLR9 re-stimulation, demonstrating that LTβR activation on mouse macrophages dampens pro-inflammatory cytokine and mediator expression. Thus, LTβR signalling renders macrophages hypo-responsive to subsequent stimulation with TLR ligands. The observation of an LTβR-mediated TLR-tolerance in the human monocyte cell line THP-1 suggests that similar signalling mechanisms seem to exist in human cells. Signalling pathway analysis clearly demonstrated that LTβR-induced TRIM30α expression is mediated by an IκBα-dependent signalling pathway. Furthermore, the LTβR-induced TRIM30α expression seems to be TRAF3 dependent. Our data suggest that LTβR activation on mouse macrophages is involved in the control of pro-inflammatory cytokine and mediator expression by activation of a signalling pathway that controls exacerbating inflammatory cytokine production.
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http://dx.doi.org/10.1016/j.molimm.2012.10.036DOI Listing
May 2013

Friend or foe: A novel role of β-defensins in tumor development.

Oncoimmunology 2012 Oct;1(7):1159-1160

Department of Immunology; University of Regensburg; Regensburg, Germany.

For many years, β-defensins were best known for their antimicrobial activity. However, β-defensins also exert immunomodulatory functions, such as the chemotactic recruitment of immune cells via chemokine receptors. We demonstrated that mouse β-defensin 14 recruits CCR6(+) B cells into fibrosarcomas, resulting in enhanced angiogenesis and tumor development.
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http://dx.doi.org/10.4161/onci.20825DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494629PMC
October 2012

E3-14.7K is recruited to TNF-receptor 1 and blocks TNF cytolysis independent from interaction with optineurin.

PLoS One 2012 4;7(6):e38348. Epub 2012 Jun 4.

Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany.

Escape from the host immune system is essential for intracellular pathogens. The adenoviral protein E3-14.7K (14.7K) is known as a general inhibitor of tumor necrosis factor (TNF)-induced apoptosis. It efficiently blocks TNF-receptor 1 (TNFR1) internalization but the underlying molecular mechanism still remains elusive. Direct interaction of 14.7K and/or associated proteins with the TNFR1 complex has been discussed although to date not proven. In our study, we provide for the first time evidence for recruitment of 14.7K and the 14.7K interacting protein optineurin to TNFR1. Various functions have been implicated for optineurin such as regulation of receptor endocytosis, vesicle trafficking, regulation of the nuclear factor κB (NF-κB) pathway and antiviral signaling. We therefore hypothesized that binding of optineurin to 14.7K and recruitment of both proteins to the TNFR1 complex is essential for protection against TNF-induced cytotoxic effects. To precisely dissect the individual role of 14.7K and optineurin, we generated and characterized a 14.7K mutant that does not confer TNF-resistance but is still able to interact with optineurin. In H1299 and KB cells expressing 14.7K wild-type protein, neither decrease in cell viability nor cleavage of caspases was observed upon stimulation with TNF. In sharp contrast, cells expressing the non-protective mutant of 14.7K displayed reduced viability and cleavage of initiator and effector caspases upon TNF treatment, indicating ongoing apoptotic cell death. Knockdown of optineurin in 14.7K expressing cells did not alter the protective effect as measured by cell viability and caspase activation. Taken together, we conclude that optineurin despite its substantial role in vesicular trafficking, endocytosis of cell surface receptors and recruitment to the TNFR1 complex is dispensable for the 14.7K-mediated protection against TNF-induced apoptosis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0038348PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3366936PMC
October 2012

Mouse β-defensin 14 (Defb14) promotes tumor growth by inducing angiogenesis in a CCR6-dependent manner.

J Immunol 2012 May 13;188(10):4931-9. Epub 2012 Apr 13.

Department of Immunology, University of Regensburg, 93053 Regensburg, Germany.

β-Defensins are known for their antimicrobial activity and belong to the molecular barrier of the innate immune system against invading pathogens. In addition, it has been shown that some members of the β-defensin superfamily have the capacity to promote local innate inflammatory and systemic adaptive immune responses, mediated in part by the interaction with CCR6. We found that mouse β-defensin 14 (mBD14, Defb14), a newly identified member of the mouse β-defensin superfamily, is expressed in mouse fibrosarcoma tumor tissue. Tumor cells overexpressing mBD14 demonstrated enhanced solid tumor growth in syngeneic C57BL/6 mice concomitant with increased vascularization of these tumors. Furthermore, mBD14-overexpressing tumors demonstrated increased expression of proangiogenic MIP-2 (CXCL2) ex vivo. In contrast, vascular endothelial growth factor expression was not affected. Cellular analysis of tumor-infiltrating leukocytes revealed a significant increase of CCR6(+) B220(+) lymphocytes in solid tumors derived from mBD14-overexpressing tumor cells. Enhanced tumor growth of mBD14-overexpressing fibrosarcomas was abolished in CCR6-deficient mice, which was paralleled by decreased infiltration of CCR6(+) B220(+) lymphocytes, indicating the requirement of CCR6 expression on host cells. Previously, the interaction of activated, LTαβ(+), lymphocytes with lymphotoxin β-receptor-expressing fibrosarcoma tumor cells has been identified as a new CXCL2-dependent proangiogenic pathway. Coexpression of a soluble lymphotoxin β-receptor:Ig fusion protein, an inhibitor of CXCL2-dependent angiogenesis, in mBD14-overexpressing fibrosarcoma tumor cells abolished enhanced solid tumor growth. Thus, we conclude that mBD14 expression by tumor-infiltrating host cells results in the chemoattraction of CCR6(+) B220(+) lymphocytes, which in turn initiates a proangiogenic pathway leading to enhanced angiogenesis and organized tumor tissue development.
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http://dx.doi.org/10.4049/jimmunol.1102442DOI Listing
May 2012

Mechanisms of immune complex-mediated experimental glomerulonephritis: possible role of the balance between endogenous TNF and soluble TNF receptor type 2.

Eur Cytokine Netw 2012 Mar;23(1):15-20

Department of Immunology, University of Regensburg, Regensburg, Germany.

In an experimental model of immune-complex-mediated glomerulonephritis, mice excreted increased levels of urinary protein starting three days after the induction. Mice lacking the TNF receptor type 2 (TNFR2) were protected from early proteinuria and enhanced mortality. Analysis of the molecular basis of the mechanisms of glomerulonephritis revealed that naïve mice continuously excrete soluble TNF-neutralizing TNFR2 in urine. Mice kept in a specific pathogen-free environment did not go on to develop early proteinuria or enhanced mortality, following induction of glomerulonephritis. TNFR2-deficient mice were protected from early proteinuria and enhanced mortality only when housed conventionally. Mice producing human TNFR2 that can be activated by mouse TNF, in addition to mouse TNFR2, did not demonstrate enhanced susceptibility to the lethal effects of glomerulonephritis, indicating that pro-inflammatory signalling via TNFR2 does not account for a sensitizing effect. Finally, we suggest that the protective effect seen in mice lacking TNFR2 results rather from environment-induced attenuation by low dose bacterial endotoxins than from missing pro-inflammatory signalling via the TNFR2.
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http://dx.doi.org/10.1684/ecn.2012.0299DOI Listing
March 2012

Lymphotoxin-beta receptor activation on macrophages ameliorates acute DSS-induced intestinal inflammation in a TRIM30α-dependent manner.

Mol Immunol 2012 Jun 20;51(2):128-35. Epub 2012 Mar 20.

Institute of Immunology, University of Regensburg, 93053 Regensburg, Germany.

Our previous studies indicated that LTβR activation mainly by T cell derived LTα₁β₂ is crucial for the control and down-regulation of intestinal inflammation. In order to dissect the cellular and molecular role of LTβR activation in the experimental model of DSS-induced intestinal inflammation, we have generated cell type-specific LTβR-deficient mice with specific ablation of LTβR expression on macrophages/neutrophils (LTβR((flox/flox))×LysM-Cre). These mice develop an exacerbated intestinal inflammation in our experimental model indicating that LTβR expression on macrophages/neutrophils is responsible for the control and down-regulation of the inflammatory reaction. These results were verified by adoptive transfer experiments of BMDM from wild-type and LTβR-deficient mice. Furthermore, transfer of activated CD4+ T cells derived from wild-type mice, but not from LTβR ligand-deficient mice attenuated the signs of intestinal inflammation. Finally, we demonstrate that LTβR activation on BMDM results in induction of TRIM30α, a negative regulator of NFκB activation. Concordantly, ablation of LTβR signaling results in the inability to induce TRIM30α expression concomitant with an increased expression of pro-inflammatory cytokines in our experimental model. Taken together, our data demonstrate that LTβR activation on macrophages by CD4+ T cell derived LTαβ controls the pro-inflammatory response by activation of a TRIM30α-dependent signaling pathway, crucial for the down-regulation of the inflammatory response in this experimental model.
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http://dx.doi.org/10.1016/j.molimm.2012.02.118DOI Listing
June 2012

Lymphotoxin β receptor activation on macrophages induces cross-tolerance to TLR4 and TLR9 ligands.

J Immunol 2012 Apr 22;188(7):3426-33. Epub 2012 Feb 22.

Institute of Immunology, University of Regensburg, 93053 Regensburg, Germany.

Our previous studies indicated that lymphotoxin β receptor (LTβR) activation controls and downregulates inflammatory reactions. In this study, we report that LTβR activation on primary mouse macrophages results in induction of tripartite motif containing (TRIM) 30α, which negatively regulates NF-κB activation induced by TLR signaling. LTβR activation results in a downregulation of proinflammatory cytokine and mediator expression upon TLR restimulation, demonstrating that LTβR signaling is involved in the induction of TLR cross-tolerance. Specific knockdown experiments using TRIM30α-specific small interfering RNA abolished the LTβR-dependent induction of TRIM30α and LTβR-mediated TLR cross-tolerance. Concordantly, LTβR activation on bone marrow-derived macrophages induced cross-tolerance to TLR4 and TLR9 ligands in vitro. Furthermore, we have generated cell type-specific LTβR-deficient mice with ablation of LTβR expression on macrophages/neutrophils (LTβR(flox/flox) × LysM-Cre). In bone marrow-derived macrophages derived from these mice LTβR-induced cross-tolerance to TLR4 and TLR9 ligands was impaired. Additionally, mice with a conditional ablation of LTβR expression on macrophages (LTβR(flox/flox) × LysM-Cre) are resistant to LTβR-induced TLR4 tolerance in vivo. Collectively, our data indicate that LTβR activation on macrophages by T cell-derived lymphotoxin α(1)β(2) controls proinflammatory responses by activation of a TRIM30α-controlled, counterregulatory signaling pathway to protect against exacerbating inflammatory reactions.
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http://dx.doi.org/10.4049/jimmunol.1103324DOI Listing
April 2012

RelA and RelB transcription factors in distinct thymocyte populations control lymphotoxin-dependent interleukin-17 production in γδ T cells.

Immunity 2011 Mar;34(3):364-74

Immunology Group, Leibniz-Institute for Age Research-Fritz-Lipmann-Institute, Beutenbergstrasse 11, 07745 Jena, Germany.

The NF-κB transcription factor regulates numerous immune responses but its contribution to interleukin-17 (IL-17) production by T cells is largely unknown. Here, we report that IL-17, but not interferon-γ (IFN-γ), production by γδ T cells required the NF-κB family members RelA and RelB as well as the lymphotoxin-β-receptor (LTβR). In contrast, LTβR-NF-κB signaling was not involved in the differentiation of conventional αβ Th17 cells. Impaired IL-17 production in RelA- or RelB-deficient T cells resulted in a diminished innate immune response to Escherichia coli infection. RelA controlled the expression of LT ligands in accessory thymocytes whereas RelB, acting downstream of LTβR, was required for the expression of RORγt and RORα4 transcription factors and the differentiation of thymic precursors into γδT17 cells. Thus, RelA and RelB within different thymocyte subpopulations cooperate in the regulation of IL-17 production by γδ T cells and contribute to the host's ability to fight bacterial infections.
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http://dx.doi.org/10.1016/j.immuni.2011.02.019DOI Listing
March 2011

Human beta-defensin 2 and 3 and their mouse orthologs induce chemotaxis through interaction with CCR2.

J Immunol 2010 Jun 17;184(12):6688-94. Epub 2010 May 17.

Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Division of Basic Science, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.

Beta-defensins play a dual role during immune response. Their direct antimicrobial properties contribute to the local innate immune response by combating microbial invasions. Furthermore, previous studies revealed the capacity of certain beta-defensin family members to chemoattract immature dendritic cells and CD45RO+ CD4+ T cells through chemokine receptor CCR6. However, because beta-defensins also chemoattract macrophages and monocytes, which do not express CCR6, efforts have been made to identify other receptors for these polypeptides. In this study, we demonstrate the capacity of human beta-defensin (hBD)2 and 3 and their mouse orthologs, beta-defensin 4 and 14, to interact with CCR2, a chemokine receptor expressed on monocytes, macrophages, and neutrophils. These beta-defensins, fused to the Fc region of human IgG1, showed binding to CCR2-transfected HEK293 cells, as revealed by flow cytometry. The beta-defensin fusion proteins also induced CCR2-specific chemotaxis of transfected HEK293 cells, human peripheral blood monocytes, and mouse peritoneal exudate cells in a dose-dependent manner. Preincubation of human monocytes with CCL2/MCP-1, the chemokine ligand for CCR2, abolished migration induced by beta-defensins. Conversely, preincubation with hBD2:Ig or hBD3:Ig inhibited MCP-1 induced migration. Peritoneal exudate cells from CCR2-deficient mice failed to migrate toward these fusion proteins. In conclusion, the beta-defensins used in this study contribute to the innate and adaptive immune response in their role as chemoattractants. Our data indicate that hBD2 and hBD3, together with their mouse orthologs (beta-defensin 4 and 14), are chemotactic for a broad spectrum of leukocytes in a CCR6- and CCR2-dependent manner.
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http://dx.doi.org/10.4049/jimmunol.0903984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6309988PMC
June 2010

Lymphotoxin-β receptor activation by lymphotoxin-α(1)β(2) and LIGHT promotes tumor growth in an NFκB-dependent manner.

Int J Cancer 2011 Mar;128(6):1363-70

Institute of Immunology, University of Regensburg, Regensburg, Germany.

Lymphotoxin beta receptor (LTβR) activation on mouse fibrosarcoma cells (BFS-1) results in enhanced solid tumor growth paralleled by increased angiogenesis induced by the expression of pro-angiogenic CXCL2. In our study, we demonstrate that both functional ligands of the LTβR, namely LTα(1) β(2) and LIGHT, are involved in the activation of LTβR in solid fibrosarcomas. To identify whether the lymphocyte population is involved in the activation of LTβR in these fibrosarcoma tumors, we used conditional LTβ-deficient mice that specifically lack LTβ expression either on T cells (T-LTβ(-/-)) or on B cells (B-LTβ(-/-)). Solid tumor growth was reduced in both mouse strains when compared to tumor growth in wild-type mice, indicating the participation of both T and B host lymphocytes in the activation of LTβR in these tumors. Tumor growth was also reduced in LIGHT-deficient mice, suggesting a contribution of this ligand to the activation of LTβR in BFS-1 fibrosarcomas. LTβR signaling can involve IκBα and/or NFκB-inducing kinase (NIK) for subsequent NFκB activation in different types of cells. Expression of a dominant negative form of IκBα or of a dominant negative mutant of NIK resulted in decreased activation of NFκB signaling and reduced expression of pro-angiogenic CXCL2 in vitro. Moreover, expression of dominant negative form of NIK or an IκBα repressor in these fibrosarcoma cells resulted in reduced solid tumor growth in vivo, suggesting that both IκBα and NIK are involved in pro-angiogenic signaling after LTβR activation. Our data support the idea that the ablation of LTβR signaling should be considered for cancer treatment.
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http://dx.doi.org/10.1002/ijc.25456DOI Listing
March 2011

Mouse aorta smooth muscle cells differentiate into lymphoid tissue organizer-like cells on combined tumor necrosis factor receptor-1/lymphotoxin beta-receptor NF-kappaB signaling.

Arterioscler Thromb Vasc Biol 2010 Mar 5;30(3):395-402. Epub 2010 Feb 5.

Institute for Vascular Medicine, Friedrich Schiller University of Jena, Bachstrasse 18, 07743 Jena, Germany.

Objective: Mouse aorta smooth muscle cells (SMC) express tumor necrosis factor receptor superfamily member 1A (TNFR-1) and lymphotoxin beta-receptor (LTbetaR). Circumstantial evidence has linked the SMC LTbetaR to tertiary lymphoid organogenesis in hyperlipidemic mice. Here, we explored TNFR-1 and LTbetaR signaling in cultured SMC.

Methods And Results: TNFR-1 signaling activated the classical RelA NF-kappaB pathway, whereas LTbetaR signaling activated the classical RelA and alternative RelB NF-kappaB pathways, and both signaling pathways synergized to enhance p100 inhibitor processing to the p52 subunit of NF-kappaB. Microarrays showed that simultaneous TNFR-1/LTbetaR activation resulted in elevated mRNA encoding leukocyte homeostatic chemokines CCL2, CCL5, CXCL1, and CX3CL1. Importantly, SMC acquired features of lymphoid tissue organizers, which control tertiary lymphoid organogenesis in autoimmune diseases through hyperinduction of CCL7, CCL9, CXCL13, CCL19, CXCL16, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1. TNFR-1/LTbetaR cross-talk resulted in augmented secretion of lymphorganogenic chemokine proteins. Supernatants of TNFR-1/LTbetaR-activated SMC markedly supported migration of splenic T cells, B cells, and macrophages/dendritic cells. Experiments with ltbr(-/-) SMC indicated that LTbetaR-RelB activation was obligatory to generate the lymphoid tissue organizer phenotype.

Conclusions: SMC may participate in the formation of tertiary lymphoid tissue in atherosclerosis by upregulation of lymphorganogenic chemokines involved in T-lymphocyte, B-lymphocyte, and macrophage/dendritic cell attraction.
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http://dx.doi.org/10.1161/ATVBAHA.109.191395DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874749PMC
March 2010

Specific binding and chemotactic activity of mBD4 and its functional orthologue hBD2 to CCR6-expressing cells.

J Biol Chem 2010 Mar 12;285(10):7028-34. Epub 2010 Jan 12.

Institute of Immunology, University of Regensburg, Regensburg D-93042, Germany.

Beta-defensins are small antimicrobial polypeptides that are mainly expressed by epithelial cells and play an important role in the antimicrobial innate immune response. In addition to the direct microbicidal effects of these polypeptides, members of the beta-defensin super family have the capacity to promote local innate inflammatory and systemic adaptive immune responses, which are in part mediated by the CC-chemokine receptor CCR6. Here we report the expression of recombinant mBD4 and its human orthologue hBD2 fused to the constant domain of human IgG(1) to obtain correct folding and to increase stability and solubility using the Drosophila S2 expression system. Purified recombinant mBD4:Ig and hBD2:Ig fusion proteins retained potent antimicrobial activity against Gram-negative and Gram-positive bacteria. Furthermore, these beta-defensin fusion proteins showed specific binding to CCR6-expressing cells as revealed by flow cytometry. Interestingly, although hBD2:Ig bound to both human and mouse CCR6-expressing cells, mBD4:Ig did only bind to mCCR6-expressing cells but not to hCCR6-expressing cells. Both beta-defensin fusion proteins demonstrated chemotactic activity for cells expressing the mouse CC-chemokine receptor CCR6. The chemokine ligand CCL20 competed with the beta-defensin fusion proteins for specific binding to CCR6 as analyzed by fluorescence-activated cell sorter analysis. Both beta-defensin fusion proteins demonstrated chemotactic activity for cells expressing the mouse CCR6 receptor, but mBD4:Ig did not induce chemotactic activity of cells expressing human CCR6. This result supports our finding that mBD4 does not interact with human CCR6-expressing cells. Further evidence for specific interaction of the beta-defensin fusion proteins with CCR6-expressing cells is demonstrated by the observation that CCL20 and beta-defensin fusion proteins desensitize each other in inducing chemotactic activity. In addition both mBD4:Ig and hBD2:Ig demonstrated CCR6-independent chemotaxis of freshly isolated mouse resident peritoneal cells and human peripheral blood mononuclear cells, indicating the interaction with another chemotaxis-inducing receptor. Thus, the beta-defensin fusion proteins used in this study retained their biological activity and are a feasible tool to identify and analyze specific beta-defensin receptor interactions.
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http://dx.doi.org/10.1074/jbc.M109.091090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2844152PMC
March 2010

Neutralization of LIGHT ameliorates acute dextran sodium sulphate-induced intestinal inflammation.

Immunology 2009 Nov;128(3):451-8

Institute of Immunology, University of Regensburg, Regensburg, Germany.

Emerging data indicate that alterations in the expression of tumour necrosis factor (TNF) superfamily members play a crucial role in the pathogenesis of intestinal inflammation. Recent results demonstrated that sustained transgenic expression of lymphotoxin-like inducible protein that competes with glycoprotein D for binding herpesvirus entry mediator on T cells (LIGHT; TNFSF14) induced severe intestinal inflammation, suggesting a specific role of LIGHT-mediated signalling to the intestinal compartment. In order to dissect the role of LIGHT in intestinal inflammation, we used LIGHT-deficient mice in the mouse model of acute dextran sodium sulphate-induced colitis. Interestingly, LIGHT-deficient mice were characterized by strongly reduced signs of intestinal inflammation compared with wild-type mice in this experimental model. Determination of mouse LIGHT mRNA expression in colon tissues of wild-type mice revealed a strong induction of mouse LIGHT mRNA expression during acute DSS-induced colitis. We therefore generated anti-mouse LIGHT monoclonal antibodies in LIGHT-deficient mice which bind specifically to LIGHT and are capable of neutralizing the activity of LIGHT in vitro and in vivo. With these antibodies, we demonstrated that neutralization of LIGHT during acute DSS-induced colitis resulted in reduced signs of intestinal inflammation. These data suggest that LIGHT is an important mediator in intestinal inflammation and may serve as a new target for therapeutic intervention.
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http://dx.doi.org/10.1111/j.1365-2567.2009.03131.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2770692PMC
November 2009

Lymphotoxin beta receptor signaling promotes tertiary lymphoid organogenesis in the aorta adventitia of aged ApoE-/- mice.

J Exp Med 2009 Jan 12;206(1):233-48. Epub 2009 Jan 12.

Institute for Vascular Medicine, Friedrich Schiller University of Jena, 07743 Jena, Germany.

Atherosclerosis involves a macrophage-rich inflammation in the aortic intima. It is increasingly recognized that this intimal inflammation is paralleled over time by a distinct inflammatory reaction in adjacent adventitia. Though cross talk between the coordinated inflammatory foci in the intima and the adventitia seems implicit, the mechanism(s) underlying their communication is unclear. Here, using detailed imaging analysis, microarray analyses, laser-capture microdissection, adoptive lymphocyte transfers, and functional blocking studies, we undertook to identify this mechanism. We show that in aged apoE(-/-) mice, medial smooth muscle cells (SMCs) beneath intimal plaques in abdominal aortae become activated through lymphotoxin beta receptor (LTbetaR) to express the lymphorganogenic chemokines CXCL13 and CCL21. These signals in turn trigger the development of elaborate bona fide adventitial aortic tertiary lymphoid organs (ATLOs) containing functional conduit meshworks, germinal centers within B cell follicles, clusters of plasma cells, high endothelial venules (HEVs) in T cell areas, and a high proportion of T regulatory cells. Treatment of apoE(-/-) mice with LTbetaR-Ig to interrupt LTbetaR signaling in SMCs strongly reduced HEV abundance, CXCL13, and CCL21 expression, and disrupted the structure and maintenance of ATLOs. Thus, the LTbetaR pathway has a major role in shaping the immunological characteristics and overall integrity of the arterial wall.
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http://dx.doi.org/10.1084/jem.20080752DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2626665PMC
January 2009

Enhanced susceptibility to Con A-induced liver injury in mice transgenic for the intracellular isoform of human TNF receptor type 2.

J Leukoc Biol 2008 Jul 24;84(1):162-9. Epub 2008 Apr 24.

Department of Immunology, University of Regensburg, F.-J.-Strauss-Allee, D-93042 Regensburg, Germany.

TNF is a pleiotropic cytokine involved in a variety of inflammatory processes and immune responses. TNF effects are mediated via two distinct membrane receptors: TNFR1 and TNFR2. Investigations concerning regulation and function of TNFR2 revealed a novel TNFR2 isoform in human and mouse cells, termed icp75TNFR, with mainly intracellular localization. As human icp75TNFR is capable of functional interaction with mouse TNF, mouse lines transgenic for the human icp75TNFR were generated and characterized. Transgenic expression was identified in several organs, and soluble human (sh)TNFR2 was detected in serum. shTNFR2 released from transfected cells or peritoneal macrophages of transgenic mice protected from TNF-induced cytotoxicity. Although in vivo, no change in inflammatory reactions was observed in models of septic peritonitis, of colitis, or after stimulation with bacterial LPS, liver injury was strongly enhanced in transgenic mice after Con A challenge. Thus, the functional properties of human icp75TNFR seem to be similar to that of TNFR2, resulting in exacerbation of inflammatory tissue damage, thus revealing the functional importance of TNFR2 in pathophysiological processes.
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http://dx.doi.org/10.1189/jlb.1007713DOI Listing
July 2008