Holger M Reichardt

Universitätsklinikum Freiburg, Freiburg an der Elbe, Lower Saxony, Germany

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Publications (111)710.86 Total impact

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    ABSTRACT: T-cell lymphopenia is a major risk factor for autoimmunity. Here we describe congenic Lewis (LEW) rats with a loss-of-function mutation in the Gimap5 gene, leading to a 92% reduction in peripheral T-cell numbers. Gimap5-deficient LEW rats developed eosinophilic autoimmune gastroenteritis accompanied by a 40-fold increase in IgE serum levels. This phenotype was ameliorated by antibiotic treatment, indicating a critical role of the microbial flora in the development of inflammatory bowel disease. Interestingly, Gimap5-deficient LEW rats showed strongly aggravated experimental autoimmune encephalomyelitis (EAE) after immunization with guinea pig myelin basic protein. This phenotype, however, persisted after antibiosis, confirming that the enhanced CNS autoimmune response in T-cell lymphopenic Gimap5-deficient LEW rats was unrelated to the composition of the microbial flora. Rather, it seems that it was caused by the 7-fold increase in the percentage of activated T cells producing IL-17 and IFN-γ, and the skewed T-cell receptor (TCR) repertoire, both of which were the result of T-cell lymphopenia and not affected by antibiosis. This notion was supported by the observation that adoptive T-cell transfer corrected the TCR repertoire and improved EAE. Collectively, our findings confirm a critical albeit differential role of T-cell lymphopenia in the susceptibility to organ-specific autoimmune responses.-Fischer, H. J., Witte, A.-K., Walter, L., Gröne, H.-J., van den Brandt, J., Reichardt, H. M. Distinct roles of T-cell lymphopenia and the microbial flora for gastrointestinal and CNS autoimmunity.
    Full-text · Article · Jan 2016 · The FASEB Journal
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    ABSTRACT: Mineralocorticoid receptor (MR) inactivation in mice results in early postnatal lethality. Therefore we generated mice in which MR expression can be silenced during adulthood by administration of doxycycline (Dox). Using a lentiviral approach, we obtained two lines of transgenic mice harboring a construct that allows for regulatable MR inactivation by RNAi and concomitant expression of eGFP. MR mRNA levels in heart and kidney of inducible MR knock-down mice were unaltered in the absence of Dox, confirming the tightness of the system. In contrast, two weeks after Dox administration MR expression was significantly diminished in a variety of tissues. In the kidney, this resulted in lower mRNA levels of selected target genes, which was accompanied by strongly increased serum aldosterone and plasma renin levels as well as by elevated sodium excretion. In the healthy heart, gene expression and the amount of collagen were unchanged despite MR levels being significantly reduced. After transverse aortic constriction, however, cardiac hypertrophy and progressive heart failure were attenuated by MR silencing, fibrosis was unaffected and mRNA levels of a subset of genes reduced. Taken together, we believe that this mouse model is a useful tool to investigate the role of the MR in pathophysiological processes.
    Full-text · Article · Nov 2015 · PLoS ONE
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    ABSTRACT: MS is a highly prevalent neuroinflammatory disease of presumed autoimmune origin. Clinical observations and animal studies suggest that CD8+ T cells play an important role in MS but their exact mechanisms are ill defined. When we actively induced EAE in CD8 knock-out DA rats, or adoptively transferred encephalitogenic CD4+ T cells into CD8 knock-out DA rats, the disease course was indistinguishable from controls. Since our previous findings had revealed that the absence of CD8+ T cells in Lewis rats ameliorated EAE, we compared antigen-induced T cell differentiation in both strains. Disease onset and the composition of the draining lymph nodes were similar but T cell activation in DA rats was much weaker. Moreover, oligoclonal expansion of CD8+ T cells was exclusively observed in Lewis but not in DA rats. This suggests that myelin-specific CD8+ T cells are involved in the differentiation of encephalitogenic CD4+ T cells in Lewis rats, whilst they do not impact CD4+ T cell priming in DA rats. Hence, clonal expansion of CD8+ T cells in secondary lymphoid organs appears to be linked to their ability to modulate CNS autoimmune responses.
    Full-text · Article · Oct 2015

  • No preview · Article · Sep 2015
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    ABSTRACT: Objective: The chemokine CXCL12 and its receptor CXCR4 can affect tumor growth, recurrence, and metastasis. We tested the hypothesis that the CXCL12 and CXCR4 expression influences the prognosis of patients with inoperable head and neck cancer treated with definite radiotherapy or chemoradiotherapy. Methods: Formalin-fixed paraffin-embedded pretreatment tumor tissue from 233 patients with known HPV/p16(INK4A) status was analyzed. CXCL12 and CXCR4 expressions were correlated with pretreatment parameters and survival data by univariate and multivariate Cox regression. Results: CXCL12 was expressed in 43.3 % and CXCR4 in 66.1 % of the samples and both were correlated with HPV/p16(INK4A) positivity. A high CXCL12 expression was associated with increased overall survival (p = 0.036), while a high CXCR4 expression was associated with decreased metastasis-free survival (p = 0.034). Conclusion: A high CXCR4 expression could be regarded as a negative prognostic factor in head and neck cancer because it may foster metastatic spread. This may recommend CXCR4 as therapeutic target for combating head and neck cancer metastasis.
    No preview · Article · Sep 2015 · Strahlentherapie und Onkologie
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    ABSTRACT: Phosphate-based inorganic-organic hybrid nanoparticles (IOH-NPs) with the general composition [M]2+[Rfunction(O)PO3]2- (M = ZrO, Mg2O; R = functional organic group) show multipurpose and multifunctional properties. If [Rfunction(O)PO3]2- is a fluorescent dye anion ([RdyeOPO3]2), the IOH-NPs show blue, green, red and near-infrared fluorescence. This is shown for [ZrO]2+[PUP]2-, [ZrO]2+[MFP]2-, [ZrO]2+[RRP]2-, and [ZrO]2+[DUT]2- (PUP = phenylumbelliferon phosphate, MFP = methylfluorescein phosphate, RRP = resorufin phosphate, DUT = Dyomics-647 uridine triphosphate). With pharmaceutical agents as functional anions ([RdrugOPO3]2-) drug transport and release of anti-inflammatory ([ZrO]2+[BMP]2-) and anti-tumor agents ([ZrO]2+[FdUMP]2-) with up to 80% load of active drug is possible (BMP = betamethason phosphate, FdUMP = 5'-fluoro-2'-deoxyuridine 5'-monophosphate). A combination of fluorescent dye and drug anions is possible as well and shown for [ZrO]2+[BMP]2- 0.996[DUT]2- 0.004. Merging of functional anions, in general, results in [ZrO]2+([RdrugOPO3]1-x[RdyeOPO3]x)2- nanoparticles and is highly relevant for theranostics. Amine-based functional anions in [MgO]2+[RaminePO3]2- IOH-NPs, finally, show CO2 sorption (up to 180 mg g-1) and can be used for CO2/N2 separation (selectivity up to α = 23). This includes aminomethyl phosphonate [AMP]2-, 1-aminoethyl phosphonate [1AEP]2-, 2-aminoethyl phosphonate [2AEP]2-, aminopropyl phosphonate [APP]2-, and aminobutyl phosphonate [ABP]2-. All [M]2+[Rfunction(O)PO3]2- IOH-NPs are prepared via uncomplex synthesis in water, which facilitates practical handling and which is optimal for biomedical application. In sum, all IOH-NPs have very similar chemical compositions but can address a variety of different functions, including fluorescence, drug delivery and CO2 sorption.
    No preview · Article · May 2015 · Journal of the American Chemical Society
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    Full-text · Article · May 2015 · Nature
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    Full-text · Article · May 2015 · Nature
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    ABSTRACT: The putative protein tyrosine kinase (PTK) inhibitor tyrphostin AG126 has proven beneficial in various models of inflammatory disease. Yet molecular targets and cellular mechanisms remained enigmatic. We demonstrate here that AG126 treatment has beneficial effects in experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. AG126 alleviates the clinical symptoms, diminishes encephalitogenic Th17 differentiation, reduces inflammatory CNS infiltration as well as microglia activation and attenuates myelin damage. We show that AG126 directly inhibits Bruton's tyrosine kinase (BTK), a PTK associated with B cell receptor and Toll-like receptor (TLR) signaling. However, BTK inhibition cannot account for the entire activity spectrum. Effects on TLR-induced proinflammatory cytokine expression in microglia involve AG126 hydrolysis and conversion of its dinitrile side chain to malononitrile (MN). Notably, while liberated MN can subsequently mediate critical AG126 features, full protection in EAE still requires delivery of intact AG126. Its anti-inflammatory potential and especially interference with TLR signaling thus rely on a dual mechanism encompassing BTK and a novel MN-sensitive target. Both principles bear great potential for the therapeutic management of disturbed innate and adaptive immune functions.GLIA 2015. © 2015 Wiley Periodicals, Inc.
    Full-text · Article · Mar 2015 · Glia
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    ABSTRACT: Brain-derived neurotrophic factor (BDNF) promotes neuronal survival, regeneration and plasticity. Emerging evidence also indicates an essential role for BDNF outside the nervous system, for instance in immune cells. We therefore investigated the impact of BDNF on T cells using BDNF knockout (ko) mice and conditional ko mice lacking BDNF specifically in this lymphoid subset. In both settings, we observed diminished T-cell cellularity in peripheral lymphoid organs and an increase in CD4(+) CD44(+) memory T cells. Analysis of thymocyte development revealed diminished total thymocyte numbers, accompanied by a significant increase in CD4/CD8 double negative (DN) thymocytes due to a partial block in the transition from the DN3 to the DN4 stage. This was neither due to increased thymocyte apoptosis nor defects in the expression of the TCR β-chain or the pre-TCR. In contrast, pERK but not pAKT levels were diminished in DN3 BDNF-deficient thymocytes. BDNF deficiency in T cells did not result in gross deficits in peripheral acute immune responses nor in changes of the homeostatic proliferation of peripheral T cells. Taken together, our data reveal a critical autocrine and/or paracrine role of T-cell-derived BDNF in thymocyte maturation involving ERK-mediated TCR signalling pathways. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    No preview · Article · Jan 2015 · European Journal of Immunology
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    ABSTRACT: Superior treatment response and survival for patients with human papilloma virus (HPV)-positive head and neck cancer (HNSCC) are documented in clinical studies. However, the relevance of high-grade acute organ toxicity (HGAOT), which has also been correlated with improved prognosis, has attracted scant attention in HPV-positive HNSCC patients. Hence we tested the hypothesis that both parameters, HPV and HGAOT, are positive prognostic factors in patients with HNSCC treated with definite radiotherapy (RT) or radiochemotherapy (RCT). Pretreatment tumor tissue and clinical records were available from 233 patients receiving definite RT (62 patients) or RCT (171 patients). HPV infection was analysed by means of HPV DNA detection or p16(INK4A) expression; HGAOT was defined as the occurrence of acute organ toxicity >grade 2 according to the Common Toxicity Criteria. Both variables were correlated with overall survival (OS) using Cox proportional hazards regression. Positivity for HPV DNA (44 samples, 18.9 %) and p16(INK4A) expression (102 samples, 43.8 %) were significantly correlated (p < 0.01), and HGAOT occurred in 77 (33 %) patients. Overall, the 5-year OS was 23 %; stratified for p16(INK4A) expression and HGAOT, OS rates were 47 %, 42 %, 20 % and 10 % for patients with p16(INK4A) expression and HGAOT, patients with HGAOT only, patients with p16(INK4A) expression only, and patients without p16(INK4A) expression or HGAOT, respectively. After multivariate testing p16(INK4A) expression (p = 0.003) and HGAOT (p < 0.001) were significantly associated with OS. P16(INK4A) expression and HGAOT are independent prognostic factors for OS of patients with HNSCC, whereas p16(INK4A) expression is particularly important for patients without HGAOT.
    No preview · Article · Jan 2015 · Strahlentherapie und Onkologie
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    ABSTRACT: Glucocorticoids (GCs) are released from the adrenal gland during inflammation and help to keep immune responses at bay. Owing to their potent anti-inflammatory activity GCs also play a key role in controlling acute graft-versus-host disease (aGvHD). Here we demonstrate that mice lacking the glucocorticoid receptor (GR) in T cells develop fulminant disease after allogeneic bone marrow transplantation. In a fully MHC-mismatched model, transfer of GR-deficient T cells resulted in severe aGvHD symptoms and strongly decreased survival times. Histopathological features were aggravated and infiltration of CD8+ T cells into the jejunum was increased when the GR was not expressed. Furthermore, serum levels of IL-2, IFNγ and IL-17 were elevated and the cytotoxicity of CD8+ T cells enhanced after transfer of GR-deficient T cells. Short-term treatment with dexamethasone reduced cytokine secretion but neither impacted disease severity nor the CTLs’ cytolytic capacity. Importantly, in an aGvHD model in which disease development exclusively depends on the presence of CD8+ T cells in the transplant, transfer of GR-deficient T cells aggravated clinical symptoms and reduced survival times as well. Taken together, our findings highlight that suppression of CD8+ T cell function is a crucial mechanism in the control of aGvHD by endogenous GCs.
    Full-text · Article · Oct 2014 · The Journal of Pathology

  • No preview · Article · Oct 2014

  • No preview · Article · Oct 2014 · Journal of Neuroimmunology
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    ABSTRACT: Introduction: The role of erythropoietin (Epo) in myocardial repair after infarction remains inconclusive. We observed high Epo receptor (EPOR) expression in cardiac progenitor cells (CPCs). Therefore, we aimed to characterize these cells and elucidate their contribution to myocardial regeneration upon Epo stimulation.Results: High EPOR expression was detected during murine embryonic heart development followed by a marked decrease until adulthood. EPOR positive cells in the adult heart were identified in a CPC-enriched cell population and showed co-expression of stem, mesenchymal, endothelial and cardiomyogenic cell markers. We focused on the population co-expressing early (TBX5, NKX2.5) and definitive (myosin heavy chain (MHC), cardiac Troponin T (cTNT)) cardiomyocyte markers. Epo increased their proliferation and thus were designated as Epo-responsive MHC expressing cells (EMCs). In vitro, EMCs proliferated and partially differentiated towards cardiomyocyte-like cells. Repetitive Epo administration in mice with myocardial infarction (cumulative dose 4 IU/g) resulted in an increase of cardiac EMCs and cTNT positive cells in the infarcted area. This was further accompanied by a significant preservation of cardiac function as compared to control mice.Conclusion: Our study characterized an EPO-responsive MHC-expressing cell population in the adult heart. Repetitive, moderate-dose Epo treatment enhanced the proliferation of EMCs resulting in preservation of post-ischemic cardiac function. Stem Cells 2014
    Full-text · Article · Sep 2014 · Stem Cells
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    ABSTRACT: Background Graft-versus-host disease (GvHD) is a major challenge after hematopoietic stem cell transplantation but treatment options for patients are still limited. In many cases first-line treatment with glucocorticoids is not successful. Among second-line therapies the extracorporeal photopheresis (ECP) is frequently performed, due to induction of selective tolerance instead of general immunosuppression. However, for some patients with severe acute GvHD the leukapheresis step of the ECP procedure is physically exhausting and limits the number of ECP cycles. Methods We hypothesized that leukocytes from healthy cell donors could be used as a replacement for ECP leukocytes gained from the GvHD patient. For this purpose we used a well established mouse model of acute GvHD. The ECP therapy was based on cells with the genetic background of the initial donor of the stem cell transplantation. As a precondition we developed a protocol representing conventional ECP in mice equivalent to clinical used ECP setup. Results We could demonstrate that conventional, clinically derived ECP setup is able to alleviate acute GvHD. By using leukocytes obtained from healthy mice with the bone marrow donor’s genetic background we could not observe a statistically significant therapeutic effect. Conclusions Conventional human ECP setup is effective in the mouse model of severe acute GvHD. In addition we could not prove that ECP cells from healthy mice with bone marrow donor’s genetic background are as effective as ECP cells derived from GvHD mice. Based on our findings, new questions arise for further studies, in which the cellular characteristics for ECP mediated immune tolerance are a matter of investigation.
    Full-text · Article · Aug 2014 · PLoS ONE
  • Holger M Reichardt · Henrike J Fischer
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    ABSTRACT: Transgenesis is a valuable tool with which to study different aspects of gene function in the context of the intact organism. During the last two decades a tremendous number of transgenic animals have been generated, and the continuous improvement of technology and the development of new systems have fostered their widespread application in biomedical research. Generally, transgenic animals are generated by introducing foreign DNA into fertilized oocytes, which can be achieved either by injecting recombinant DNA into the pronucleus or by transferring lentiviral particles into the perivitelline space. While mice remain the favored species in many laboratories, there are a number of applications where the use of rats is advantageous. One such research area is multiple sclerosis. Here, several experimental models are available that are closely mimicking the human disease, and it is possible to induce neuroinflammation by transferring pathogenic T cells which can then be studied by flow cytometry and 2-photon live imaging. Unlike for mice, the development of transgenic rats has encountered some hurdles in the past, e.g., due to a complicated reproductive biology and the frailty of the fertilized oocytes in vitro. In this chapter we provide a protocol describing how we manipulate single cell embryos in our lab in order to efficiently generate transgenic rats in a variety of different strains using lentiviral gene transfer.
    No preview · Article · Jul 2014 · Methods in Molecular Biology
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    ABSTRACT: Glucocorticoids (GCs) constitute a highly pleiotropic class of drugs predominantly employed in the treatment of inflammatory diseases. In our search for new mechanisms of action we identified a hitherto unknown effect of GCs in the gastrointestinal tract. We found that oral administration of dexamethasone (Dex) to mice caused an enlargement of the stomach due to the induction of gastroparesis, and that this effect was abolished in GR(dim) mice carrying the A458T mutation in the GC receptor (GR). Gastroparesis was unrelated to the enhanced gastric acid secretion observed after Dex treatment although both effects were mediated by the same molecular mechanism of the GR. Using conditional GR knock-out mice we could further rule out that GC effects on enterocytes or myeloid cells were involved in the induction of gastroparesis. In contrast, we found that Dex up-regulated arginase 2 (Arg2) in the stomach both at the mRNA and protein level. This suggests that GC treatment leads to a depletion of L-arginine thereby impeding the production of nitric oxide (NO) which is required for gastric motility. We tested this hypothesis by supplementing the drinking water of the mice with exogenous L-arginine to compensate for the presumed shortage of this major substrate of NO synthases. Importantly, this measure completely prevented both the enlargement of the stomach and the induction of gastroparesis after Dex treatment. Our findings raise considerations of combining orally applied GCs with L-arginine to improve tolerability of GC treatment and provide a possible explanation for the anti-emetic effects of GCs widely exploited in chemotherapy.
    No preview · Article · Jul 2014 · Endocrinology
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    ABSTRACT: Basal cell carcinoma (BCC) belongs to the group of non-melanoma skin tumors and is the most common tumor in the western world. BCC arises due to mutations in the tumor suppressor gene Patched1 (Ptch). Analysis of the conditional Ptch knockout mouse model for BCC reveals that macrophages and dendritic cells (DC) of the skin play an important role in BCC growth restraining processes. This is based on the observation that a clodronate-liposome mediated depletion of these cells in the tumor-bearing skin results in significant BCC enlargement. The depletion of these cells does not modulate Ki67 or K10 expression, but is accompanied by a decrease in collagen-producing cells in the tumor stroma. Together, the data suggest that cutaneous macrophages and DC in the tumor microenvironment exert an antitumor effect on BCC.
    Full-text · Article · Apr 2014 · PLoS ONE
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    ABSTRACT: Glucocorticoids (GCs) are the standard therapy for treating multiple sclerosis (MS) patients suffering from an acute relapse. One of the main mechanisms of GC action is held to be the induction of T cell apoptosis leading to reduced lymphocyte infiltration into the CNS, yet our analysis of experimental autoimmune encephalomyelitis (EAE) in three different strains of genetically manipulated mice has revealed that the induction of T cell apoptosis is not essential for the therapeutic efficacy of GCs. Instead, we identified the redirection of T cell migration in response to chemokines as a new therapeutic principle of GC action. GCs inhibited the migration of T cells towards CCL19 while they enhanced their responsiveness towards CXCL12. Importantly, blocking CXCR4 signaling in vivo by applying Plerixafor(®) strongly impaired the capacity of GCs to interfere with EAE, as revealed by an aggravated disease course, more pronounced CNS infiltration and a more dispersed distribution of the infiltrating T cells throughout the parenchyma. Our observation that T cells lacking the GC receptor were refractory to CXCL12 further underscores the importance of this pathway for the treatment of EAE by GCs. Importantly, methylprednisolone pulse therapy strongly increased the capacity of peripheral blood T cells from MS patients of different subtypes to migrate towards CXCL12. This indicates that modulation of T cell migration is an important mechanistic principle responsible for the efficacy of high-dose GC therapy not only of EAE but also of MS.
    Full-text · Article · Feb 2014 · Acta Neuropathologica

Publication Stats

6k Citations
710.86 Total Impact Points

Institutions

  • 2014-2015
    • Universitätsklinikum Freiburg
      • Institute of Human Genetics
      Freiburg an der Elbe, Lower Saxony, Germany
  • 2008-2015
    • Universitätsmedizin Göttingen
      • Department of Cellular and Molecular Immunology
      Göttingen, Lower Saxony, Germany
  • 2007-2015
    • Georg-August-Universität Göttingen
      • • Institute for Cellular and Molecular Immunology
      • • Göttingen Center for Molecular Biosciences (GZMB)
      • • Institute of Inorganic Chemistry
      Göttingen, Lower Saxony, Germany
  • 2004-2013
    • University of Wuerzburg
      • Institute for Virology and Immune Biology
      Würzburg, Bavaria, Germany
  • 2011
    • University of Cologne
      • Institute for Medical Microbiology, Immunology and Hygiene
      Köln, North Rhine-Westphalia, Germany
    • Leibniz Institute for Age Research - Fritz Lipmann Institute
      Jena, Thuringia, Germany
  • 2010
    • University of Greifswald
      • Department of Laboratory Animal Science
      Greifswald, Mecklenburg-Vorpommern, Germany
    • Technische Universität Hamburg-Harburg
      Hamburg, Hamburg, Germany
  • 2009
    • Benaroya Research Institute
      Seattle, Washington, United States
  • 2004-2007
    • Collège de France
      Lutetia Parisorum, Île-de-France, France
  • 1999-2002
    • Institute of Molecular Biology
      Mayence, Rheinland-Pfalz, Germany
  • 1998-2002
    • Howard Hughes Medical Institute
      Ашбърн, Virginia, United States
  • 1996-2002
    • German Cancer Research Center
      • Division of Molecular Biology of the Cell II
      Heidelburg, Baden-Württemberg, Germany