Publications by authors named "Fred Lühder"

69 Publications

A flow cytometric approach to study glucocorticoid receptor expression in immune cell subpopulations of genetically engineered mice.

Immunol Lett 2021 Mar 19. Epub 2021 Mar 19.

University Medical Center Göttingen, Institute for Cellular and Molecular Immunology, Göttingen, Germany. Electronic address:

Glucocorticoids (GCs) constitute one of the most powerful classes of anti-inflammatory agents and are used for the treatment of a plethora of diseases related to autoimmunity, allergy, cancer, and infection. In the last two decades, multiple studies using genetically engineered mice with targeted deletions of the GC receptor (GR) in individual cell types have provided insights into the mechanisms of GCs in the control of the immune system. The characterization of GR expression in these mouse models, however, mostly relied on the analysis of mRNA expression or reporter gene activity. In contrast, approaches directly detecting the GR protein on a cellular level are scarce. Thus, we here used a flow cytometric method to analyze mice in which the GR gene locus was disrupted with the help of a Cre recombinase expressed under the control of either the lck or the lysM promoter. Measuring GR protein expression in immune cell subpopulations unveiled an efficient and highly selective depletion in both strains of knock-out mice in accordance with the expected cellular specificity of the employed promoters for T cells or myeloid cells, respectively. The flow cytometric data were well in line with those from the analysis of GR mRNA expression in magnetically sorted immune cell subpopulations but they could be obtained much more quickly. In summary, our data indicate that flow cytometry is a powerful tool with which to define GR protein content at a single cell level when studying the function of GCs in the immune system.
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http://dx.doi.org/10.1016/j.imlet.2021.03.010DOI Listing
March 2021

Primidone blocks RIPK1-driven cell death and inflammation.

Cell Death Differ 2020 Dec 3. Epub 2020 Dec 3.

Department of Nephrology and Hypertension, University Hospital Schleswig-Holstein, 24105, Kiel, Germany.

The receptor-interacting serine/threonine protein kinase 1 (RIPK1) is a key mediator of regulated cell death and inflammation. Recent studies suggest that RIPK1 inhibition would fundamentally improve the therapy of RIPK1-dependent organ damage in stroke, myocardial infarction, kidney failure, and systemic inflammatory response syndrome. Additionally, it could ameliorate or prevent multi-organ failure induced by cytokine release in the context of hyperinflammation, as seen in COVID-19 patients. Therefore, we searched for a RIPK1 inhibitor and present the aromatic antiepileptic and FDA-approved drug primidone (Liskantin®) as a potent inhibitor of RIPK1 activation in vitro and in a murine model of TNFα-induced shock, which mimics the hyperinflammatory state of cytokine release syndrome. Furthermore, we detected for the first time RIPK1 activation in the respiratory tract epithelium of hospitalized patients who tested positive for SARS-CoV-2 infection. Our data provide a strong rationale for evaluating the drug primidone in conditions of hyperinflammation in humans.
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http://dx.doi.org/10.1038/s41418-020-00690-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712602PMC
December 2020

Interleukin-1 promotes autoimmune neuroinflammation by suppressing endothelial heme oxygenase-1 at the blood-brain barrier.

Acta Neuropathol 2020 10 11;140(4):549-567. Epub 2020 Jul 11.

Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.

The proinflammatory cytokine interleukin 1 (IL-1) is crucially involved in the pathogenesis of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Herein, we studied the role of IL-1 signaling in blood-brain barrier (BBB) endothelial cells (ECs), astrocytes and microglia for EAE development, using mice with the conditional deletion of its signaling receptor IL-1R1. We found that IL-1 signaling in microglia and astrocytes is redundant for the development of EAE, whereas the IL-1R1 deletion in BBB-ECs markedly ameliorated disease severity. IL-1 signaling in BBB-ECs upregulated the expression of the adhesion molecules Vcam-1, Icam-1 and the chemokine receptor Darc, all of which have been previously shown to promote CNS-specific inflammation. In contrast, IL-1R1 signaling suppressed the expression of the stress-responsive heme catabolizing enzyme heme oxygenase-1 (HO-1) in BBB-ECs, promoting disease progression via a mechanism associated with deregulated expression of the IL-1-responsive genes Vcam1, Icam1 and Ackr1 (Darc). Mechanistically, our data emphasize a functional crosstalk of BBB-EC IL-1 signaling and HO-1, controlling the transcription of downstream proinflammatory genes promoting the pathogenesis of autoimmune neuroinflammation.
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http://dx.doi.org/10.1007/s00401-020-02187-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498485PMC
October 2020

Multiple inducers and novel roles of autoantibodies against the obligatory NMDAR subunit NR1: a translational study from chronic life stress to brain injury.

Mol Psychiatry 2020 Feb 24. Epub 2020 Feb 24.

Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany.

Circulating autoantibodies (AB) of different immunoglobulin classes (IgM, IgA, and IgG), directed against the obligatory N-methyl-D-aspartate-receptor subunit NR1 (NMDAR1-AB), belong to the mammalian autoimmune repertoire, and appear with age-dependently high seroprevalence across health and disease. Upon access to the brain, they can exert NMDAR-antagonistic/ketamine-like actions. Still unanswered key questions, addressed here, are conditions of NMDAR1-AB formation/boosting, intraindividual persistence/course in serum over time, and (patho)physiological significance of NMDAR1-AB in modulating neuropsychiatric phenotypes. We demonstrate in a translational fashion from mouse to human that (1) serum NMDAR1-AB fluctuate upon long-term observation, independent of blood-brain barrier (BBB) perturbation; (2) a standardized small brain lesion in juvenile mice leads to increased NMDAR1-AB seroprevalence (IgM + IgG), together with enhanced Ig-class diversity; (3) CTLA4 (immune-checkpoint) genotypes, previously found associated with autoimmune disease, predispose to serum NMDAR1-AB in humans; (4) finally, pursuing our prior findings of an early increase in NMDAR1-AB seroprevalence in human migrants, which implicated chronic life stress as inducer, we independently replicate these results with prospectively recruited refugee minors. Most importantly, we here provide the first experimental evidence in mice of chronic life stress promoting serum NMDAR1-AB (IgA). Strikingly, stress-induced depressive-like behavior in mice and depression/anxiety in humans are reduced in NMDAR1-AB carriers with compromised BBB where NMDAR1-AB can readily reach the brain. To conclude, NMDAR1-AB may have a role as endogenous NMDAR antagonists, formed or boosted under various circumstances, ranging from genetic predisposition to, e.g., tumors, infection, brain injury, and stress, altogether increasing over lifetime, and exerting a spectrum of possible effects, also including beneficial functions.
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http://dx.doi.org/10.1038/s41380-020-0672-1DOI Listing
February 2020

Functional relevance of the multi-drug transporter abcg2 on teriflunomide therapy in an animal model of multiple sclerosis.

J Neuroinflammation 2020 Jan 8;17(1). Epub 2020 Jan 8.

Department of Neurology, Inselspital, Bern University Hospital, Department for BioMedical Research (DBMR), University of Bern, Freiburgstrasse, 3010, Bern, Switzerland.

Background: The multi-drug resistance transporter ABCG2, a member of the ATP-binding cassette (ABC) transporter family, mediates the efflux of different immunotherapeutics used in multiple sclerosis (MS), e.g., teriflunomide (teri), cladribine, and mitoxantrone, across cell membranes and organelles. Hence, the modulation of ABCG2 activity could have potential therapeutic implications in MS. In this study, we aimed at investigating the functional impact of abcg2 modulation on teri-induced effects in vitro and in vivo.

Methods: T cells from C57BL/6 J wild-type (wt) and abcg2-knockout (KO) mice were treated with teri at different concentrations with/without specific abcg2-inhibitors (Ko143; Fumitremorgin C) and analyzed for intracellular teri concentration (HPLC; LS-MS/MS), T cell apoptosis (annexin V/PI), and proliferation (CSFE). Experimental autoimmune encephalomyelitis (EAE) was induced in C57BL/6J by active immunization with MOG/CFA. Teri (10 mg/kg body weight) was given orally once daily after individual disease onset. abcg2-mRNA expression (spinal cord, splenic T cells) was analyzed using qRT-PCR.

Results: In vitro, intracellular teri concentration in T cells was 2.5-fold higher in abcg2-KO mice than in wt mice. Teri-induced inhibition of T cell proliferation was two fold increased in abcg2-KO cells compared to wt cells. T cell apoptosis demonstrated analogous results with 3.1-fold increased apoptosis after pharmacological abcg2-inhibition in wt cells. abcg2-mRNA was differentially regulated during different phases of EAE within the central nervous system and peripheral organs. In vivo, at a dosage not efficacious in wt animals, teri treatment ameliorated clinical EAE in abcg2-KO mice which was accompanied by higher spinal cord tissue concentrations of teri.

Conclusion: Functional relevance of abcg2 modulation on teri effects in vitro and in vivo warrants further investigation as a potential determinant of interindividual treatment response in MS, with potential implications for other immunotherapies.
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http://dx.doi.org/10.1186/s12974-019-1677-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6951012PMC
January 2020

Glucocorticoid resistance of allogeneic T cells alters the gene expression profile in the inflamed small intestine of mice suffering from acute graft-versus-host disease.

J Steroid Biochem Mol Biol 2019 12 24;195:105485. Epub 2019 Sep 24.

University Medical Center Göttingen, Institute for Cellular and Molecular Immunology, Humboldtallee 34, 37073 Göttingen, Germany. Electronic address:

Glucocorticoids (GCs) play an important role in controlling acute graft-versus-host disease (aGvHD), a frequent complication of allogeneic hematopoietic stem cell transplantation. The anti-inflammatory activity of GCs is mainly ascribed to the modulation of T cells and macrophages, for which reason a genetically induced GC resistance of either of these cell types causes aggravated aGvHD. Since only a few genes are currently known that are differentially regulated under these conditions, we analyzed the expression of 54 candidate genes in the inflamed small intestine of mice suffering from aGvHD when either allogeneic T cells or host myeloid cells were GC resistant using a microfluidic dynamic array platform for high-throughput quantitative PCR. The majority of genes categorized as cytokines (e.g. Il2, Il6), chemokines (e.g. Ccl2, Cxcl1), cell surface receptors (e.g. Fasl, Ctla4) and intracellular molecules (e.g. Dusp1, Arg1) were upregulated in mice transplanted with GC resistant allogeneic T cells. Moreover, the expression of several genes linked to energy metabolism (e.g. Glut1) was altered. Surprisingly, mice harboring GC resistant myeloid cells showed almost no changes in gene expression despite their fatal disease course after aGvHD induction. To identify additional genes in the inflamed small intestine that were affected by a GC resistance of allogeneic T cells, we performed an RNAseq analysis, which uncovered more than 500 differentially expressed transcripts (e.g. Cxcr6, Glut3, Otc, Aoc1, Il1r1, Sphk1) that were enriched for biological processes associated with inflammation and tissue disassembly. The changes in gene expression could be confirmed during full-blown disease but hardly any of them in the preclinical phase using high-throughput quantitative PCR. Further analysis of some of these genes revealed a highly selective expression pattern in T cells, intestinal epithelial cells and macrophages, which correlated with their regulation during disease progression. Collectively, we identified an altered gene expression profile caused by GC resistance of transplanted allogeneic T cells, which could help to define new targets for aGvHD therapy.
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http://dx.doi.org/10.1016/j.jsbmb.2019.105485DOI Listing
December 2019

Glucocorticoid Therapy of Multiple Sclerosis Patients Induces Anti-inflammatory Polarization and Increased Chemotaxis of Monocytes.

Front Immunol 2019 29;10:1200. Epub 2019 May 29.

Institute for Neuroimmunology and Multiple Sclerosis Research, University Medical Center Goettingen, Göttingen, Germany.

Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system (CNS), characterized by the infiltration of mononuclear cells into the CNS and a subsequent inflammation of the brain. Monocytes are implicated in disease pathogenesis not only in their function as potential antigen-presenting cells involved in the local reactivation of encephalitogenic T cells but also by independent effector functions contributing to structural damage and disease progression. However, monocytes also have beneficial effects as they can exert anti-inflammatory activity and promote tissue repair. Glucocorticoids (GCs) are widely used to treat acute relapses in MS patients. They act on a variety of cell types but their exact mechanisms of action including their modulation of monocyte function are not fully understood. Here we investigated effects of the therapeutically relevant GC methylprednisolone (MP) on monocytes from healthy individuals and MS patients and . The monocyte composition in the blood was different in MS patients compared to healthy individuals, but it was only marginally affected by MP treatment. In contrast, application of MP caused a marked shift toward an anti-inflammatory monocyte phenotype and as revealed by an altered gene expression profile. Chemotaxis of monocytes toward CCL2, CCL5, and CX3CL1 was increased in MS patients compared to healthy individuals and further enhanced by MP pulse therapy. Both of these migration-promoting effects were more pronounced in MS patients with an acute relapse than in those with a progressive disease. Interestingly, the pro-migratory GC effect was independent of chemokine receptor levels as exemplified by results obtained for CCR2. Collectively, our findings suggest that GCs polarize monocytes toward an anti-inflammatory phenotype and enhance their migration into the inflamed CNS, endowing them with the capacity to suppress the pathogenic immune response.
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http://dx.doi.org/10.3389/fimmu.2019.01200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6549240PMC
July 2020

Vitamin D increases glucocorticoid efficacy via inhibition of mTORC1 in experimental models of multiple sclerosis.

Acta Neuropathol 2019 09 27;138(3):443-456. Epub 2019 Apr 27.

Department of Neurology, Inselspital Bern, University Hospital, University of Bern, Bern, Switzerland.

The limited efficacy of glucocorticoids (GCs) during therapy of acute relapses in multiple sclerosis (MS) leads to long-term disability. We investigated the potential of vitamin D (VD) to enhance GC efficacy and the mechanisms underlying this VD/GC interaction. In vitro, GC receptor (GR) expression levels were quantified by ELISA and induction of T cell apoptosis served as a functional readout to assess synergistic 1,25(OH)D (1,25D)/GC effects. Experimental autoimmune encephalomyelitis (MOG EAE) was induced in mice with T cell-specific GR or mTORc1 deficiency. 25(OH)D (25D) levels were determined in two independent cohorts of MS patients with stable disease or relapses either responsive or resistant to GC treatment (initial cohort: n = 110; validation cohort: n = 85). Gene expression of human CD8 T cells was analyzed by microarray (n = 112) and correlated with 25D serum levels. In vitro, 1,25D upregulated GR protein levels, leading to increased GC-induced T cell apoptosis. 1,25D/GC combination therapy ameliorated clinical EAE course more efficiently than respective monotherapies, which was dependent on GR expression in T cells. In MS patients from two independent cohorts, 25D deficiency was associated with GC-resistant relapses. Mechanistic studies revealed that synergistic 1,25D/GC effects on apoptosis induction were mediated by the mTOR but not JNK pathway. In line, 1,25D inhibited mTORc1 activity in murine T cells, and low 25D levels in humans were associated with a reduced expression of mTORc1 inhibiting tuberous sclerosis complex 1 in CD8 T cells. GR upregulation by 1,25D and 1,25D/GC synergism in vitro and therapeutic efficacy in vivo were abolished in animals with a T cell-specific mTORc1 deficiency. Specific inhibition of mTORc1 by everolimus increased the efficacy of GC in EAE. 1,25D augments GC-mediated effects in vitro and in vivo in a T cell-specific, GR-dependent manner via mTORc1 inhibition. These data may have implications for improvement of anti-inflammatory GC therapy.
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http://dx.doi.org/10.1007/s00401-019-02018-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6689294PMC
September 2019

During acute graft versus host disease CD28 deletion in donor CD8 , but not CD4 , T cells maintain antileukemia responses in mice.

Eur J Immunol 2018 12 14;48(12):2055-2067. Epub 2018 Nov 14.

Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany.

Donor lymphocyte infusions together with allogeneic hematopoietic stem cell transplantation are routinely used as second-line treatment for hematological malignancies. Mature T cells in the graft crucially mediate a graft versus leukemia (GvL) response, but also attack healthy tissues in the recipient leading to potentially life-threatening acute graft versus host disease. Using inducible CD28 knockout C57BL/6 mice as T-cell donors, we have now assessed whether CD28 costimulation of donor CD4 and/ or CD8 T cells is required for an efficient GvL effect after allogeneic T-cell transplantation into BALB/c recipients. Our results show that CD28 costimulation of donor CD8 cytotoxic, but not CD4 helper, T cells was dispensable for curing mice from the BCL-1 lymphoma. Therefore, donor lymphocyte infusion treated lymphoma-bearing BALB/c recipient mice showed enhanced long-term survival when receiving CD28-deficient as compared to wild-type donor CD8 T cells together with wild-type conventional and regulatory CD4 T cells. The same was observed when donor CD8 and conventional and regulatory CD4 T cells were CD28 deficient. Our data, thus, suggest that systemic CD28 blockade, for example, with the drug FR104 might also reduce acute graft versus host disease in patients after allogeneic hematopoietic stem cell transplantation, while maintaining the protective GvL response.
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http://dx.doi.org/10.1002/eji.201847669DOI Listing
December 2018

CD28 Costimulation of T Helper 1 Cells Enhances Cytokine Release .

Front Immunol 2018 16;9:1060. Epub 2018 May 16.

Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany.

Compared to naive T cells, differentiated T cells are thought to be less dependent on CD28 costimulation for full activation. To revisit the role of CD28 costimulation in mouse T cell recall responses, we adoptively transferred generated OT-II T helper (Th) 1 cells into C57BL/6 mice (Thy1.2) and then either blocked CD28-ligand interactions with Fab fragments of the anti-CD28 monoclonal antibody (mAb) E18 or deleted CD28 expression using inducible CD28 knock-out OT-II mice as T cell donors. After injection of ovalbumin protein in adjuvant into the recipient mice we observed that systemic interferon (IFN)γ release strongly depended on CD28 costimulation of the Th1 cells, while secondary clonal expansion was not reduced in the absence of CD28 costimulation. For human memory CD4 T cell responses we also noted that cytokine release was reduced upon inhibition of CD28 costimulation. Together, our data highlight the so far underestimated role of CD28 costimulation for the reactivation of fully differentiated CD4 T cells.
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http://dx.doi.org/10.3389/fimmu.2018.01060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5964139PMC
July 2019

Uncoupling the widespread occurrence of anti-NMDAR1 autoantibodies from neuropsychiatric disease in a novel autoimmune model.

Mol Psychiatry 2019 10 9;24(10):1489-1501. Epub 2018 Feb 9.

Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany.

Autoantibodies of the IgG class against N-methyl-D-aspartate-receptor subunit-NR1 (NMDAR1-AB) were considered pathognomonic for anti-NMDAR encephalitis. This view has been challenged by the age-dependent seroprevalence (up to >20%) of functional NMDAR1-AB of all immunoglobulin classes found in >5000 individuals, healthy or affected by different diseases. These findings question a merely encephalitogenic role of NMDAR1-AB. Here, we show that NMDAR1-AB belong to the normal autoimmune repertoire of dogs, cats, rats, mice, baboons, and rhesus macaques, and are functional in the NMDAR1 internalization assay based on human IPSC-derived cortical neurons. The age dependence of seroprevalence is lost in nonhuman primates in captivity and in human migrants, raising the intriguing possibility that chronic life stress may be related to NMDAR1-AB formation, predominantly of the IgA class. Active immunization of ApoE and ApoE mice against four peptides of the extracellular NMDAR1 domain or ovalbumin (control) leads to high circulating levels of specific AB. After 4 weeks, the endogenously formed NMDAR1-AB (IgG) induce psychosis-like symptoms upon MK-801 challenge in ApoE mice, characterized by an open blood-brain barrier, but not in their ApoE littermates, which are indistinguishable from ovalbumin controls. Importantly, NMDAR1-AB do not induce any sign of inflammation in the brain. Immunohistochemical staining for microglial activation markers and T lymphocytes in the hippocampus yields comparable results in ApoE and ApoE mice, irrespective of immunization against NMDAR1 or ovalbumin. These data suggest that NMDAR1-AB of the IgG class shape behavioral phenotypes upon access to the brain but do not cause brain inflammation on their own.
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http://dx.doi.org/10.1038/s41380-017-0011-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6756099PMC
October 2019

Impaired resolution of DSS-induced colitis in mice lacking the glucocorticoid receptor in myeloid cells.

PLoS One 2018 11;13(1):e0190846. Epub 2018 Jan 11.

Institute for Cellular and Molecular Immunology, University Medical Center Goettingen, Göttingen, Germany.

Inflammatory bowel disease (IBD) is a highly prevalent intestinal disorder for which no cure exists. Currently, the standard first-line treatment of IBD consists of systemic glucocorticoid (GC) application, even though therapy can be complicated by unresponsiveness or adverse effects. In view of the importance of macrophages and neutrophils for the pathogenesis of IBD we set out to define the relevance of these cell types as targets of GC using the mouse model of DSS-induced colitis. We found that the disease did not resolve in GRlysM mice lacking the GC receptor (GR) in myeloid cells after removal of the chemical insult. While clinical symptoms and tissue damage in the colon ameliorated again in GRflox mice, the disease further aggravated in GRlysM littermates. The observed difference coincided with an increased abundance of macrophages in inflammatory infiltrates in the colon of mutant mice whereas neutrophil and T cell numbers were similar. Concomitantly, systemic IL-6 secretion and mRNA levels of pro-inflammatory cytokines in the colon were elevated in GRlysM mice and gene expression of scavenger receptors and IL-10 was diminished. Taken together, our results reveal an important role of myeloid cells as targets of GC in DSS-induced colitis and probably in IBD in humans as well.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0190846PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5764312PMC
February 2018

Deletion of the Mineralocorticoid Receptor in Myeloid Cells Attenuates Central Nervous System Autoimmunity.

Front Immunol 2017 13;8:1319. Epub 2017 Oct 13.

Institute of Neuroimmunology, University Medical Center Goettingen, Goettingen, Germany.

Myeloid cells play an important role in the pathogenesis of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Monocytes, macrophages, and microglia can adopt two distinct phenotypes, with M1-polarized cells being more related to inflammation and autoimmunity while M2-polarized cells contribute to tissue repair and anti-inflammatory processes. Here, we show that deletion of the mineralocorticoid receptor (MR) in bone marrow-derived macrophages and peritoneal macrophages caused their polarization toward the M2 phenotype with its distinct gene expression, altered phagocytic and migratory properties, and dampened NO production. After induction of EAE, mice that are selectively devoid of the MR in their myeloid cells (MR mice) showed diminished clinical symptoms and ameliorated histological hallmarks of neuroinflammation. T cells in peripheral lymphoid organs of these mice produced less pro-inflammatory cytokines while their proliferation and the abundance of regulatory T cells were unaltered. The numbers of inflammatory monocytes and reactive microglia in the central nervous system (CNS) in MR mice were significantly lower and they adopted an M2-polarized phenotype based on their gene expression profile, presumably explaining the ameliorated neuroinflammation. Our results indicate that the MR in myeloid cells plays a critical role for CNS autoimmunity, providing a rational to interfere with diseases such as MS by pharmacologically targeting this receptor.
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http://dx.doi.org/10.3389/fimmu.2017.01319DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5645513PMC
October 2017

Novel Drug Delivery Systems Tailored for Improved Administration of Glucocorticoids.

Int J Mol Sci 2017 Aug 24;18(9). Epub 2017 Aug 24.

Institute for Cellular and Molecular Immunology, University Medical Center Goettingen, 37073 Göttingen, Germany.

Glucocorticoids (GC) are one of the most popular and versatile classes of drugs available to treat chronic inflammation and cancer, but side effects and resistance constrain their use. To overcome these hurdles, which are often related to the uniform tissue distribution of free GC and their short half-life in biological fluids, new delivery vehicles have been developed including PEGylated liposomes, polymeric micelles, polymer-drug conjugates, inorganic scaffolds, and hybrid nanoparticles. While each of these nanoformulations has individual drawbacks, they are often superior to free GC in many aspects including therapeutic efficacy when tested in cell culture or animal models. Successful application of nanomedicines has been demonstrated in various models of neuroinflammatory diseases, cancer, rheumatoid arthritis, and several other disorders. Moreover, investigations using human cells and first clinical trials raise the hope that the new delivery vehicles may have the potential to make GC therapies more tolerable, specific and efficient in the future.
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http://dx.doi.org/10.3390/ijms18091836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618485PMC
August 2017

Protection of Mice from Acute Graft-versus-Host Disease Requires CD28 Co-stimulation on Donor CD4 Foxp3 Regulatory T Cells.

Front Immunol 2017 23;8:721. Epub 2017 Jun 23.

Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany.

Acute graft-versus-host disease (aGvHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell plus T cell transplantation (allo-HSCT). In this study, we investigated the requirement for CD28 co-stimulation of donor CD4 conventional (CD4CD25Foxp3, Tconv) and regulatory (CD4CD25Foxp3, Treg) T cells in aGvHD using tamoxifen-inducible CD28 knockout (iCD28KO) or wild-type (wt) littermates as donors of CD4 Tconv and Treg. In the highly inflammatory C57BL/6 into BALB/c allo-HSCT transplantation model, CD28 depletion on donor CD4 Tconv reduced clinical signs of aGvHD, but did not significantly prolong survival of the recipient mice. Selective depletion of CD28 on donor Treg did not abrogate protection of recipient mice from aGvHD until about day 20 after allo-HSCT. Later, however, the pool of CD28-depleted Treg drastically declined as compared to wt Treg. Consequently, only wt, but not CD28-deficient, Treg were able to continuously suppress aGvHD and induce long-term survival of the recipient mice. To our knowledge, this is the first study that specifically evaluates the impact of CD28 expression on donor Treg in aGvHD. Moreover, the delayed kinetics of aGvHD lethality after transplantation of iCD28KO Treg provides a novel animal model for similar disease courses found in patients after allo-HSCT.
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http://dx.doi.org/10.3389/fimmu.2017.00721DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5481316PMC
June 2017

Airway Epithelial Cells Are Crucial Targets of Glucocorticoids in a Mouse Model of Allergic Asthma.

J Immunol 2017 07 17;199(1):48-61. Epub 2017 May 17.

Institute for Cellular and Molecular Immunology, University Medical Center Göttingen, 37073 Göttingen, Germany;

Although glucocorticoids (GCs) are a mainstay in the clinical management of asthma, the target cells that mediate their therapeutic effects are unknown. Contrary to our expectation, we found that GC receptor (GR) expression in immune cells was dispensable for successful therapy of allergic airway inflammation (AAI) with dexamethasone. Instead, GC treatment was compromised in mice expressing a defective GR in the nonhematopoietic compartment or selectively lacking the GR in airway epithelial cells. Further, we found that an intact GR dimerization interface was a prerequisite for the suppression of AAI and airway hyperresponsiveness by GCs. Our observation that the ability of dexamethasone to modulate gene expression in airway epithelial cells coincided with its potency to resolve AAI supports a crucial role for transcriptional regulation by the GR in this cell type. Taken together, we identified an unknown mode of GC action in the treatment of allergic asthma that might help to develop more specific therapies in the future.
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http://dx.doi.org/10.4049/jimmunol.1601691DOI Listing
July 2017

Laquinimod enhances central nervous system barrier functions.

Neurobiol Dis 2017 Jun 22;102:60-69. Epub 2017 Feb 22.

Neuroimmunology Research Unit, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Faculté de Médecine, Université de Montréal, Montreal, Quebec H2L 4M1, Canada; Department of Neuroscience, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada. Electronic address:

Laquinimod is currently being tested as a therapeutic drug in multiple sclerosis. However, its exact mechanism of action is still under investigation. Tracking of fluorescently-tagged encephalitogenic T cells during experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis, revealed that laquinimod significantly reduces the invasion of pathogenic effector T cells into the CNS tissue. T-cell activation, differentiation and amplification within secondary lymphoid organs after immunization with myelin antigen, their migratory capacity and re-activation within the nervous tissue were either only mildly affected or remained unchanged. Instead, laquinimod directly impacted the functionality of the CNS vasculature. The expression of tight junction proteins p120 and ZO-1 in human brain endothelial cells was up-regulated upon laquinimod treatment, resulting in a significant increase in the transendothelial electrical resistance of confluent monolayers of brain endothelial cells. Similarly, expression of the adhesion molecule activated leukocyte cell adhesion molecule (ALCAM) and inflammatory chemokines CCL2 and IP-10 was suppressed, leading to a significant reduction in the migration of memory T1 and T17 lymphocytes across the blood brain barrier (BBB). Our data indicate that laquinimod exerts its therapeutic effects by tightening the BBB and limiting parenchymal invasion of effector T cells, thereby reducing CNS damage.
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http://dx.doi.org/10.1016/j.nbd.2017.02.002DOI Listing
June 2017

Glucocorticoid receptor in T cells mediates protection from autoimmunity in pregnancy.

Proc Natl Acad Sci U S A 2017 01 3;114(2):E181-E190. Epub 2017 Jan 3.

Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, 20251 Hamburg, Germany;

Pregnancy is one of the strongest inducers of immunological tolerance. Disease activity of many autoimmune diseases including multiple sclerosis (MS) is temporarily suppressed by pregnancy, but little is known about the underlying molecular mechanisms. Here, we investigated the endocrine regulation of conventional and regulatory T cells (Tregs) during reproduction. In vitro, we found the pregnancy hormone progesterone to robustly increase Treg frequencies via promiscuous binding to the glucocorticoid receptor (GR) in T cells. In vivo, T-cell-specific GR deletion in pregnant animals undergoing experimental autoimmune encephalomyelitis (EAE), the animal model of MS, resulted in a reduced Treg increase and a selective loss of pregnancy-induced protection, whereas reproductive success was unaffected. Our data imply that steroid hormones can shift the immunological balance in favor of Tregs via differential engagement of the GR in T cells. This newly defined mechanism confers protection from autoimmunity during pregnancy and represents a potential target for future therapy.
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http://dx.doi.org/10.1073/pnas.1617115114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5240705PMC
January 2017

Targeted delivery of glucocorticoids to macrophages in a mouse model of multiple sclerosis using inorganic-organic hybrid nanoparticles.

J Control Release 2017 01 3;245:157-169. Epub 2016 Dec 3.

Institute for Cellular and Molecular Immunology, University Medical Center Göttingen, 37073 Göttingen, Germany. Electronic address:

Glucocorticoids (GC) are widely used to treat acute relapses in multiple sclerosis (MS) patients, but their application is accompanied by side effects due to their broad spectrum of action. Here, we report on the therapeutic option to apply GC via inorganic-organic hybrid nanoparticles (IOH-NP) with the composition [ZrO][(BMP)(FMN)] (designated BMP-NP with BMP: betamethasone phosphate; FMN: flavinmononucleotide). We found that these BMP-NP have an increased cell type-specificity compared to free GC while retaining full therapeutic efficacy in a mouse model of MS. BMP-NP were preferentially taken up by phagocytic cells and modulated macrophages in vivo more efficiently than T cells. When GC were applied in the form of BMP-NP, treatment of neuroinflammatory disease in mice exclusively depended on the control of macrophage function whereas effects on T cells and brain endothelial cells were dispensable for therapeutic efficacy. Importantly, BMP-NP were not only active in mice but also showed strong activity towards monocytes isolated from healthy human volunteers. We conclude that application of GC via IOH-NP has the potential to improve MS therapy in the future.
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http://dx.doi.org/10.1016/j.jconrel.2016.12.003DOI Listing
January 2017

Interrupting CD28 costimulation before antigen rechallenge affects CD8(+) T-cell expansion and effector functions during secondary response in mice.

Eur J Immunol 2016 07 17;46(7):1644-55. Epub 2016 May 17.

Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany.

The role of CD28-mediated costimulation in secondary CD8(+) T-cell responses remains controversial. Here, we have used two tools - blocking mouse anti-mouse CD28-specific antibodies and inducible CD28-deleting mice - to obtain definitive answers in mice infected with ovalbumin-secreting Listeria monocytogenes. We report that both blockade and global deletion of CD28 reveal its requirement for full clonal expansion and effector functions such as degranulation and IFN-γ production during the secondary immune response. In contrast, cell-intrinsic deletion of CD28 in transferred TCR-transgenic CD8(+) T cells before primary infection leads to impaired clonal expansion but an increase in cells able to express effector functions in both primary and secondary responses. We suggest that the proliferation-impaired CD8(+) T cells respond to CD28-dependent help from their environment by enhanced functional differentiation. Finally, we report that cell-intrinsic deletion of CD28 after the peak of the primary response does not affect the establishment, maintenance, or recall of long-term memory. Thus, if given sufficient time, the progeny of primed CD8(+) T cells adapt to the absence of this costimulator.
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http://dx.doi.org/10.1002/eji.201546232DOI Listing
July 2016

Autoantibody-boosted T-cell reactivation in the target organ triggers manifestation of autoimmune CNS disease.

Proc Natl Acad Sci U S A 2016 Mar 8;113(12):3323-8. Epub 2016 Mar 8.

Institute of Neuroimmunology and Institute for Multiple Sclerosis Research, University Medical Centre Göttingen, D-37073 Göttingen, Germany; Max-Planck-Institute for Experimental Medicine Göttingen, D-37075 Göttingen, Germany

Multiple sclerosis (MS) is caused by T cells that are reactive for brain antigens. In experimental autoimmune encephalomyelitis, the animal model for MS, myelin-reactive T cells initiate the autoimmune process when entering the nervous tissue and become reactivated upon local encounter of their cognate CNS antigen. Thereby, the strength of the T-cellular reactivation process within the CNS tissue is crucial for the manifestation and the severity of the clinical disease. Recently, B cells were found to participate in the pathogenesis of CNS autoimmunity, with several diverse underlying mechanisms being under discussion. We here report that B cells play an important role in promoting the initiation process of CNS autoimmunity. Myelin-specific antibodies produced by autoreactive B cells after activation in the periphery diffused into the CNS together with the first invading pathogenic T cells. The antibodies accumulated in resident antigen-presenting phagocytes and significantly enhanced the activation of the incoming effector T cells. The ensuing strong blood-brain barrier disruption and immune cell recruitment resulted in rapid manifestation of clinical disease. Therefore, myelin oligodendrocyte glycoprotein (MOG)-specific autoantibodies can initiate disease bouts by cooperating with the autoreactive T cells in helping them to recognize their autoantigen and become efficiently reactivated within the immune-deprived nervous tissue.
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http://dx.doi.org/10.1073/pnas.1519608113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4812745PMC
March 2016

Evaluation of the Therapeutic Potential of Anti-TLR4-Antibody MTS510 in Experimental Stroke and Significance of Different Routes of Application.

PLoS One 2016 5;11(2):e0148428. Epub 2016 Feb 5.

Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.

Toll-like receptors (TLRs) are central sensors for the inflammatory response in ischemia-reperfusion injury. We therefore investigated whether TLR4 inhibition could be used to treat stroke in a standard model of focal cerebral ischemia. Anti-TLR4/MD2-antibody (mAb clone MTS510) blocked TLR4-induced cell activation in vitro, as reported previously. Here, different routes of MTS510 application in vivo were used to study the effects on stroke outcome up to 2d after occlusion of the middle cerebral artery (MCAO) for 45 min in adult male C57Bl/6 wild-type mice. Improved neurological performance, reduced infarct volumes, and reduced brain swelling showed that intravascular application of MTS510 had a protective effect in the model of 45 min MCAO. Evaluation of potential long-term adverse effects of anti-TLR4-mAb-treament revealed no significant deleterious effect on infarct volumes nor neurological deficit after 14d of reperfusion in a mild model of stroke (15 min MCAO). Interestingly, inhibition of TLR4 resulted in an altered adaptive immune response at 48 hours after reperfusion. We conclude that blocking TLR4 by the use of specific mAb is a promising strategy for stroke therapy. However, long-term studies with increased functional sensitivity, larger sampling sizes and use of other species are required before a clinical use could be envisaged.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0148428PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4746129PMC
July 2016

Knockout of silent information regulator 2 (SIRT2) preserves neurological function after experimental stroke in mice.

J Cereb Blood Flow Metab 2015 Dec 29;35(12):2080-8. Epub 2015 Jul 29.

Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.

Sirtuin-2 (Sirt2) is a member of the NAD(+)-dependent protein deacetylase family. Various members of the sirtuin class have been found to be involved in processes related to longevity, regulation of inflammation, and neuroprotection. Induction of Sirt2 mRNA was found in the whole hemisphere after experimental stroke in a recent screening approach. Moreover, Sirt2 protein is highly expressed in myelin-rich brain regions after stroke. To examine the effects of Sirt2 on ischemic stroke, we induced transient focal cerebral ischemia in adult male Sirt2-knockout and wild-type mice. Two stroke models with different occlusion times were applied: a severe ischemia (45 minutes of middle cerebral artery occlusion (MCAO)) and a mild one (15 minutes of MCAO), which was used to focus on subcortical infarcts. Neurological deficit was determined at 48 hours after 45 minutes of MCAO, and up to 7 days after induction of 15 minutes of cerebral ischemia. In contrast to recent data on Sirt1, Sirt2(-/-) mice showed less neurological deficits in both models of experimental stroke, with the strongest manifestation after 48 hours of reperfusion. However, we did not observe a significant difference of stroke volumes or inflammatory cell count between Sirt2-deficient and wild-type mice. Thus we postulate that Sirt2 mediates myelin-dependent neuronal dysfunction during the early phase after ischemic stroke.
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http://dx.doi.org/10.1038/jcbfm.2015.178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4671131PMC
December 2015

Neurotoxocarosis alters myelin protein gene transcription and expression.

Parasitol Res 2015 Jun 17;114(6):2175-86. Epub 2015 Mar 17.

Institute for Parasitology, University of Veterinary Medicine Hannover, Buenteweg 17, 30559, Hannover, Germany.

Neurotoxocarosis is an infection of the central nervous system caused by migrating larvae of the common dog and cat roundworms (Toxocara canis and Toxocara cati), which are zoonotic agents. As these parasites are prevalent worldwide and neuropathological and molecular investigations on neurotoxocarosis are scare, this study aims to characterise nerve fibre demyelination associated with neurotoxocarosis on a molecular level. Transcription of eight myelin-associated genes (Cnp, Mag, Mbp, Mog, Mrf-1, Nogo-A, Plp1, Olig2) was determined in the mouse model during six time points of the chronic phase of infection using qRT-PCR. Expression of selected proteins was analysed by Western blotting or immunohistochemistry. Additionally, demyelination and neuronal damage were investigated histologically. Significant differences (p ≤ 0.05) between transcription rates of T. canis-infected and uninfected control mice were detected for all analysed genes while T. cati affected five of eight investigated genes. Interestingly, 2', 3 ´-cyclic nucleotide 3'-phosphodiesterase (Cnp) and myelin oligodendrocyte glycoprotein (Mog) were upregulated in both T. canis- and T. cati-infected mice preceding demyelination. Later, CNPase expression was additionally enhanced. As expected, myelin basic protein (Mbp) was downregulated in cerebra and cerebella of T. canis-infected mice when severe demyelination was present 120 days post infectionem (dpi). The transcriptional pattern observed in the present study appears to reflect direct traumatic and hypoxic effects of larval migration as well as secondary processes including host immune reactions, demyelination and attempts to remyelinate damaged areas.
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http://dx.doi.org/10.1007/s00436-015-4407-1DOI Listing
June 2015

Tyrphostin AG126 exerts neuroprotection in CNS inflammation by a dual mechanism.

Glia 2015 Jun 2;63(6):1083-99. Epub 2015 Mar 2.

Institute of Neuropathology, University of Göttingen, Germany.

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.
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http://dx.doi.org/10.1002/glia.22803DOI Listing
June 2015

Thymocyte-derived BDNF influences T-cell maturation at the DN3/DN4 transition stage.

Eur J Immunol 2015 May 19;45(5):1326-38. Epub 2015 Feb 19.

Department of Neuroimmunology, Institute for Multiple Sclerosis Research, The Hertie Foundation and MPI for Experimental Medicine, University of Göttingen Medical School, Göttingen, Germany.

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 signaling pathways.
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http://dx.doi.org/10.1002/eji.201444985DOI Listing
May 2015

NMDA-receptor antagonists block B-cell function but foster IL-10 production in BCR/CD40-activated B cells.

Cell Commun Signal 2014 Dec 5;12:75. Epub 2014 Dec 5.

Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Germany.

Background: B cells are important effectors and regulators of adaptive and innate immune responses, inflammation and autoimmunity, for instance in anti-NMDA-receptor (NMDAR) encephalitis. Thus, pharmacological modulation of B-cell function could be an effective regimen in therapeutic strategies. Since the non-competitive NMDAR antagonist memantine is clinically applied to treat advanced Alzheimer`s disease and ketamine is supposed to improve the course of resistant depression, it is important to know how these drugs affect B-cell function.

Results: Non-competitive NMDAR antagonists impaired B-cell receptor (BCR)- and lipopolysaccharide (LPS)-induced B-cell proliferation, reduced B-cell migration towards the chemokines SDF-1α and CCL21 and downregulated IgM and IgG secretion. Mechanistically, these effects were mediated through a blockade of Kv1.3 and KCa3.1 potassium channels and resulted in an attenuated Ca(2+)-flux and activation of Erk1/2, Akt and NFATc1. Interestingly, NMDAR antagonist treatment increased the frequency of IL-10 producing B cells after BCR/CD40 stimulation.

Conclusions: Non-competitive NMDAR antagonists attenuate BCR and Toll-like receptor 4 (TLR4) B-cell signaling and effector function and can foster IL-10 production. Consequently, NMDAR antagonists may be useful to target B cells in autoimmune diseases or pathological systemic inflammation. The drugs' additional side effects on B cells should be considered in treatments of neuronal disorders with NMDAR antagonists.
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http://dx.doi.org/10.1186/s12964-014-0075-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4269920PMC
December 2014

Glucocorticoids attenuate acute graft-versus-host disease by suppressing the cytotoxic capacity of CD8(+) T cells.

J Pathol 2015 Mar 7;235(4):646-55. Epub 2015 Jan 7.

Institute for Cellular and Molecular Immunology, University of Göttingen Medical School, Göttingen, Germany.

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 was 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.
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http://dx.doi.org/10.1002/path.4475DOI Listing
March 2015

Glucocorticoids induce gastroparesis in mice through depletion of l-arginine.

Endocrinology 2014 Oct 24;155(10):3899-908. Epub 2014 Jul 24.

Institute for Cellular and Molecular Immunology (S.D.R., T.W., M.O., J.v.d.B., H.M.R.) and Department of Neuroimmunology (F.L.), Institute for Multiple Sclerosis Research, The Hertie Foundation and MPI for Experimental Medicine, University of Göttingen Medical School, 37073 Göttingen, Germany; Institute of Physiology (A.R., M.F., F.L.), University of Tübingen, 72076 Tübingen, Germany; and Institute of General Zoology and Endocrinology (J.P.T.), University of Ulm, 89081 Ulm, Germany.

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-knockout 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 upregulated 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 antiemetic effects of GCs widely exploited in chemotherapy.
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http://dx.doi.org/10.1210/en.2014-1246DOI Listing
October 2014

DMBA/TPA treatment is necessary for BCC formation from patched deficient epidermal cells in Ptch(flox/flox)CD4Cre(+/-) mice.

J Invest Dermatol 2014 Oct 24;134(10):2620-2629. Epub 2014 Mar 24.

Institute of Human Genetics, University of Göttingen, Göttingen, Germany.

The development of basal cell carcinoma (BCC), the most frequently diagnosed tumor among persons with European ancestry, is closely linked to mutations in the Hedgehog (Hh) receptor and tumor suppressor Patched1 (Ptch). Using Ptch(flox/flox)CD4Cre(+/-) mice, in which Ptch was ablated in CD4Cre-expressing cells, we demonstrate that the targeted cells can give rise to BCC after treatment with DMBA (7,12-dimethylbenz(a)anthracene)/TPA (12-O-tetradecanoylphorbol-13-acetate), but not after wounding of the skin. In addition, in this model, BCC are not caused by malfunctioning of Ptch-deficient T cells, as BCC did not develop when bone marrow (BM) of Ptch(flox/flox)CD4Cre(+/-) mice was transplanted into Ptch wild-type mice. Instead, lineage-tracing experiments and flow cytometric analyses suggest that the tumors are initiated from rare Ptch-deficient stem cell-like cells of the epidermis that express CD4. As DMBA/TPA is a prerequisite for BCC development in this model, the initiated cells need a second stimulus for expansion and tumor formation. However, in contrast to papilloma, this stimulus seems to be unrelated to alterations in the Ras signaling cascade. Together, these data suggest that biallelic loss of Ptch in CD4(+) cells does not suffice for BCC formation and that BCC formation requires a second so far unknown event, at least in the Ptch(flox/flox)CD4Cre(+/-) BCC mouse model.
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http://dx.doi.org/10.1038/jid.2014.157DOI Listing
October 2014