Martin Witzenrath - Academia.edu (original) (raw)

Papers by Martin Witzenrath

European Respiratory Journal, 2016

Introduction: Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortalit... more Introduction: Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortality worldwide. Streptococcus pneumoniae ( S.p. ) is the most frequent causal pathogen identified in CAP.Despite efficient antimicrobial therapy, CAP can induce pulmonary endothelial hyperpermeability resulting in life-threatening lung failure due to an exaggerated host-pathogen interaction. Angiopoietin- (Ang-)1 mediated Tie2-activation reduces and the Ang-1 antagonist Ang-2 increases inflammation and endothelial permeability in sepsis. “Vasculotide” (VT) is a PEGylated (polyethylene glycol) Tie2-agonist mimicking Ang-1. The aim of our study was to investigate experimentally whether VT could diminish pneumonia-induced lung injury. Methods: Human and murine lung endothelial cells were investigated by electrical cell-substrate impedance sensing (ECIS) and immunofluorescence staining. Pulmonary hyperpermeability was quantified in VT-pretreated isolated perfused and ventilated mouse lungs stimulated with the pneumococcal exotoxin pneumolysin (PLY). Also, S.p. infected mice were therapeutically treated with VT. Results: Pretreatment with VT protected lung endothelial cell-monolayers from PLY-induced disruption. Also, decreased PLY-induced pulmonary permeability of isolated mouse lungs was observed in the VT-treated group in comparison to the untreated group. Likewise, therapeutic treatment with VT of S.p. infected mice significantly reduced pneumonia-induced hyperpermeability. Conclusion: VT protected pulmonary endothelial integrity and reduced lung permeability in different models of pneumococcal pneumonia. Thus, VT may provide a novel perspective as adjunctive therapy in addition to antibotics. Support: DFG (SFB/TR84,C6).

American Journal of Respiratory Cell and Molecular Biology, Sep 1, 2013

Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypert... more Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypertension (PH), is modulated by nitric oxide (NO). NO synthesis can be decreased by asymmetric dimethylarginine (ADMA), which is degraded by dimethylarginine dimethylaminohydrolase-1 (DDAH1). We investigated the effects of DDAH1 overexpression (DDAH1 tg) on HPV and chronic hypoxia-induced PH. HPV was measured during acute (10 min) and sustained (3 h) hypoxia in isolated mouse lungs. Chronic PH was induced by the exposure of mice to 4 weeks of hypoxia. ADMA and cyclic 39,59-guanosine monophosphate (cGMP) were determined by ELISA, and NO generation was determined by chemiluminescence. DDAH1 overexpression exerted no effects on acute HPV. However, DDAH1 tg mice showed decreased sustained HPV compared with wild-type (WT) mice. Concomitantly, ADMA was decreased, and concentrations of NO and cGMP were significantly increased in DDAH1 tg. The administration of either N v-nitro-L-arginine or 1H-[1,2,4]oxadiazolo [4,3-a] quinoxalin-1-one potentiated sustained HPV and partly abolished the differences in sustained HPV between WT and DDAH1 tg mice. The overexpression of DDAH1 exerted no effect on the development of chronic hypoxia-induced PH. DDAH1 overexpression selectively decreased the sustained phase of HPV, partly via activation of the NO-cGMP pathway. Thus, increased ADMA concentrations modulate sustained HPV, but not acute HPV or chronic hypoxia-induced PH.

The Journal of Immunology, 2010

The Journal of Immunology, Jun 15, 2009

In the context of allergic immune responses, activation of STAT6 is pivotal for Th2-mediated IgE ... more In the context of allergic immune responses, activation of STAT6 is pivotal for Th2-mediated IgE production and development of airway inflammation and hyperreactivity. We analyzed whether gene silencing of STAT6 expression by RNA interference was able to suppress allergen-induced immune and airway responses. Knockdown effectiveness of three different STAT6 siRNA molecules was analyzed in murine and human cell cultures. The most potent siRNA was used for further testing in a murine model of allergen-induced airway inflammation and airway hyperreactivity (AHR). BALB/c mice were sensitized with OVA/alum twice i.p. (days 1 and 14), and challenged via the airways with allergen (days 28-30). Intranasal application of STAT6 siRNA before and during airway allergen challenges reduced levels of infiltrating cells, especially of eosinophils, in the bronchoalveolar lavage fluid, compared with GFP siRNA-treated sensitized and challenged controls. Allergen-induced alterations in lung tissues (goblet cell hyperplasia, peribronchial inflammation with eosinophils and CD4 T cells) were significantly reduced after STAT6 siRNA treatment. Associated with decreased inflammation was a significant inhibition of the development of allergen-induced in vivo AHR after STAT6 siRNA treatment, compared with GFP siRNAtreated sensitized and challenged controls. Importantly, mRNA and protein expression levels of IL-4 and IL-13 in lung tissues of STAT6-siRNA treated mice were significantly diminished compared with sensitized and challenged controls. These data show that targeting the key transcription factor STAT6 by siRNA effectively blocks the development of cardinal features of allergic airway disease, like allergen-induced airway inflammation and AHR. It may thus be considered as putative approach for treatment of allergic airway diseases such as asthma.

European Respiratory Journal, Sep 1, 2014

Objectives: Currently approved pneumococcal vaccines comprise only a part of the clinically relev... more Objectives: Currently approved pneumococcal vaccines comprise only a part of the clinically relevant S. pneumoniae serotypes. Moreover, high costs limit their administration, particularly in developing countries. An innovative chemical method enables the synthesis of almost any capsular polysaccharide antigen of S. pneumoniae and thereby, a cost-efficient rapid production of polyvalent vaccines according to the clinical and epidemiological necessity. In the current pilot study, the protective effect of a new glycoconjugate vaccine consisting of a synthetic capsular oligosaccharide of S. pneumoniae serotype 3 was examined. Methods: Mice were subcutaneously immunised with monovalent glycoconjugate with or without the adjuvant aluminium hydroxide (alum) and boosted twice at two week intervals prior to transnasal infection with S. pneumoniae serotype 3. Results : The synthetic glycoconjugate vaccine induced the production of specific antibodies against serotype 3 capsular oligosaccharide in mice. Pneumococcal infection was associated with hypothermia and loss of body weight in non-vaccinated controls and glycoconjugate vaccinated mice, but not in mice immunised with glycoconjugate and alum. Bacterial load of lung, bronchoalveolar lavage fluid and blood was significantly decreased in mice vaccinated in combination with the adjuvant. Immunisation with glycoconjugate and alum prior to pneumococcal infection reduced cytokine release into the bronchoalveolar space and prevented damage of the endoepithelial barrier. Conclusion: Immunisation with S. pneumoniae serotype 3 glycoconjugate protected mice from severe pneumococcal pneumonia by inducing protective antibodies. Funding: SFB/TR84 .

Pneumologie, 2009

Bei Pneumonie kann uberschiesende Entzundung zu lebensbedrohlichen Storungen der Oxygenierung fuh... more Bei Pneumonie kann uberschiesende Entzundung zu lebensbedrohlichen Storungen der Oxygenierung fuhren. Insbesondere die Pneumokokken-Pneumonie ist durch eine massive Freisetzung pro-entzundlicher Mediatoren gepragt. Gleichwohl ist wenig uber der Entzundung entgegenwirkende Faktoren bei Pneumonie bekannt. Wir pruften die Hypothese, dass der Transkriptionsfaktor KLF2 Pneumokokken-induzierter Epithelzellaktivierung entgegenwirkt. Infektion mit Pneumokokken induziert die Expression von KLF2 (Proteinexpression, Aktivierung eines KLF2-Reportergens) in kultivierten humanen Epithelzellen und in infizierten Mauslungen in vivo. Die Induktion von KLF2 erfolgt nach Aktivierung von transmembranaren TLR2 und zytosolischem NOD2. Stimulation der Zellen mit TLR2- oder Nod2-Liganden oder Pneumokokken fuhrt zur Phosphorylierung der regulatorischen PI3-Kinase Untereinheit p55. Blockade der Pi3-Kinase inhibiert die Expression von KLF2 (Proteinexpression, Reportergen). Dagegen ist die KLF2 Expression unabhangig von den Kinasen p38, ERK und JNK. Experimente mit transienter Uberexpression von KLF2 oder Depletion von KLF2 mittels siRNA demonstrieren, dass KLF2 der Expression NF-kappaB-abhangiger Gene entgegenwirkt. Zusammengefasst wurde a) die PI3-Kinase als Element des TLR2- und Nod2-Signalpfades identifiziert und konnte b) KLF2 einen wichtigen gegenregulatorischen Faktor zur Vermeidung uberschiesender Entzundungsreaktionen bei Pneumonie darstellen.

American journal of respiratory cell and molecular biology, Jan 29, 2015

The cation channel transient receptor potential vanilloid 4 (TRPV4) is expressed in endothelial a... more The cation channel transient receptor potential vanilloid 4 (TRPV4) is expressed in endothelial and immune cells; however, its role in acute lung injury (ALI) is unclear. The functional relevance of TRPV4 was assessed in vivo, in isolated murine lungs and in isolated neutrophils. Genetic deficiency of TRPV4 attenuated the functional, histological and inflammatory hallmarks of acid-induced ALI. Similar protection was obtained with prophylactic administration of the TRPV4 inhibitor GSK2193874; however, therapeutic administration of the TRPV4 inhibitor HC-067047 after ALI induction had no beneficial effect. In isolated lungs, platelet-activating factor (PAF) increased vascular permeability in lungs perfused with trpv4+/+ more than with trpv4-/- blood independent of lung genotype, suggesting a contribution of TRPV4 on blood cells to lung vascular barrier failure. In neutrophils, TRPV4 inhibition or deficiency attenuated the PAF-induced increase in intracellular calcium. PAF induced form...

A47. DIAGNOSTIC TECHNIQUES AND MONITORING, 2012

PLOS ONE, 2015

The innate immune system employs C-type lectin receptors (CLRs) to recognize carbohydrate structu... more The innate immune system employs C-type lectin receptors (CLRs) to recognize carbohydrate structures on pathogens and self-antigens. The Macrophage-inducible C-type lectin (Mincle) is a FcRγ-coupled CLR that was shown to bind to mycobacterial cord factor as well as certain fungal species. However, since CLR functions during bacterial infections have not yet been investigated thoroughly, we aimed to examine their function in Streptococcus pneumonia infection. Binding studies using a library of recombinantly expressed CLR-Fc fusion proteins indicated a specific, Ca 2+-dependent, and serotype-specific binding of Mincle to S. pneumonia. Subsequent experiments with different Mincle-expressing cells as well as Mincle-deficient mice, however, revealed a limited role of this receptor in bacterial phagocytosis, neutrophil-mediated killing, cytokine production, and antibacterial immune response during pneumonia. Collectively, our results indicate that Mincle is able to recognize S. pneumonia but is not required for the anti-pneumococcal innate immune response.

The Journal of Immunology, 2009

Different NOD-like receptors, including NLRP1, NLRP3, and NLRC4, as well as the recently identifi... more Different NOD-like receptors, including NLRP1, NLRP3, and NLRC4, as well as the recently identified HIN-200 protein, AIM2, form multiprotein complexes called inflammasomes, which mediate caspase-1–dependent processing of pro-IL-1β. Listeria monocytogenes is an intracellular pathogen that is actively phagocytosed by monocytes/macrophages and subsequently escapes from the phagosome into the host cell cytosol, depending on its pore-forming toxin listeriolysin O (LLO). In this study, we demonstrate that human PBMCs produced mature IL-1β when infected with wild-type L. monocytogenes or when treated with purified LLO. L. monocytogenes mutants lacking LLO or expressing a noncytolytic LLO as well as the avirulent Listeria innocua induced strongly impaired IL-1β production. RNA interference and inhibitor experiments in human PBMCs as well as experiments in Nlrp3 and Rip2 knockout bone marrow-derived macrophages demonstrated that the Listeria-induced IL-1β release was dependent on ASC, caspas...

The Journal of Immunology, 2008

Legionella pneumophila causes severe pneumonia. Acetylation of histones is thought to be an impor... more Legionella pneumophila causes severe pneumonia. Acetylation of histones is thought to be an important regulator of gene transcription, but its impact on L. pneumophila-induced expression of proinflammatory cytokines is unknown. L. pneumophila strain 130b induced the expression of the important chemoattractant IL-8 and genome-wide histone modifications in human lung epithelial A549 cells. We analyzed the IL-8-promoter and found that histone H4 was acetylated and H3 was phosphorylated at Ser10 and acetylated at Lys14, followed by transcription factor NF-κB. Recruitment of RNA polymerase II to the IL-8 promoter corresponded with increases in gene transcription. Histone modification and IL-8 release were dependent on p38 kinase and NF-κB pathways. Legionella-induced IL-8 expression was decreased by histone acetylase (HAT) inhibitor anacardic acid and enhanced by histone deacetylase (HDAC) inhibitor trichostatin A. After Legionella infection, HATs p300 and CREB-binding protein were time-...

The Journal of Immunology, 2010

The release of potent proinflammatory mediators is not only central for mounting an efficient hos... more The release of potent proinflammatory mediators is not only central for mounting an efficient host response, but also bears the risk for deleterious excessive tissue-damaging inflammation. This is highlighted in severe pneumococcal pneumonia, in which the delicate balance between a robust inflammatory response to kill pneumococci and loss of organ function determines the outcome of disease. In this study, we tested the hypothesis that Krüppel-like factor (KLF)2 counterregulates pneumococci- and pattern recognition receptor-related human lung cell activation. Pneumococci induced KLF2 expression in vitro and in a murine pneumonia model. Activation of TLR2- and nucleotide-binding oligomerization domain protein 2-related signaling induced KLF2 expression in a PI3K-dependent manner. Overexpression of KLF2 downregulated pneumococci-, TLR2-, and nucleotide-binding oligomerization domain protein 2-related NF-κB–dependent gene expression and IL-8 release, whereas small interfering RNA-based ...

European Respiratory Journal, 2012

European Journal of Immunology, 2013

Formation of the splenic marginal zone (MZ) depends on the alternative NF-κB signaling pathway. R... more Formation of the splenic marginal zone (MZ) depends on the alternative NF-κB signaling pathway. Recently, we reported that unrestricted activation of this pathway in NF-κB2/ p100-deficient (p100 −/−) knock-in mice alters the phenotype of MZ stroma and B cells. Here, we show that lack of the p100 inhibitor resulted in an expansion of both MZ B and peritoneal B-1 cells. However, these cells failed to generate proliferating blasts in response to T-cell-independent type 2 (TI-2) Ags, correlating with dampened IgM and absent IgG3 responses. This phenotype was in part due to increased activity of the NF-κB subunit RelB. Moreover, p100 −/− →B6 BM chimeras were more susceptible to infection by encapsulated Streptococcus pneumoniae bacteria, pathogens that induce TI-2 responses. In contrast to the TI-2 defect, p100 deficiency did not impair immune responses to the TI-1 Ag LPS and p100 −/− MZ B cells showed normal Ag transportation into B-cell follicles. Furthermore, p100 −/− MZ B and B-1 cells failed to respond to TI-2 Ags in the presence of WT accessory cells. Thus, NF-κB2/p100 deficiency caused a predominant B-cell-intrinsic TI-2 defect that could largely be attributed to impaired proliferation of plasmablasts. Importantly, p100 was also necessary for efficient defense against clinically relevant TI-2 pathogens.

American Journal of Respiratory Cell and Molecular Biology, 2013

Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypert... more Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypertension (PH), is modulated by nitric oxide (NO). NO synthesis can be decreased by asymmetric dimethylarginine (ADMA), which is degraded by dimethylarginine dimethylaminohydrolase-1 (DDAH1). We investigated the effects of DDAH1 overexpression (DDAH1 tg) on HPV and chronic hypoxia-induced PH. HPV was measured during acute (10 min) and sustained (3 h) hypoxia in isolated mouse lungs. Chronic PH was induced by the exposure of mice to 4 weeks of hypoxia. ADMA and cyclic 39,59-guanosine monophosphate (cGMP) were determined by ELISA, and NO generation was determined by chemiluminescence. DDAH1 overexpression exerted no effects on acute HPV. However, DDAH1 tg mice showed decreased sustained HPV compared with wild-type (WT) mice. Concomitantly, ADMA was decreased, and concentrations of NO and cGMP were significantly increased in DDAH1 tg. The administration of either N v-nitro-L-arginine or 1H-[1,2,4]oxadiazolo [4,3-a] quinoxalin-1-one potentiated sustained HPV and partly abolished the differences in sustained HPV between WT and DDAH1 tg mice. The overexpression of DDAH1 exerted no effect on the development of chronic hypoxia-induced PH. DDAH1 overexpression selectively decreased the sustained phase of HPV, partly via activation of the NO-cGMP pathway. Thus, increased ADMA concentrations modulate sustained HPV, but not acute HPV or chronic hypoxia-induced PH.

DMW - Deutsche Medizinische Wochenschrift, 2017

Infections are the most common cause of granulomatous lung diseases. A variety of different patho... more Infections are the most common cause of granulomatous lung diseases. A variety of different pathogens can cause granuloma formation. The diagnosis requires consideration of endemic characteristics, patients' predispositions as well as specific requirements for pathogen detection. The aim of this review is to give a short overview of the most important causative pathogens and facilitate the differential diagnostic approach of granulomatous lung diseases.

Cell chemical biology, Jan 17, 2016

The identification of immunogenic glycotopes that render glycoconjugate vaccines protective is ke... more The identification of immunogenic glycotopes that render glycoconjugate vaccines protective is key to improving vaccine efficacy. Synthetic oligosaccharides are an attractive alternative to the heterogeneous preparations of purified polysaccharides that most marketed glycoconjugate vaccines are based on. To investigate the potency of semi-synthetic glycoconjugates, we chose the least-efficient serotype in the current pneumococcal conjugate vaccine Prevnar 13, Streptococcus pneumoniae serotype 3 (ST3). Glycan arrays containing synthetic ST3 repeating unit oligosaccharides were used to screen a human reference serum for antibodies and to define the recognition site of two ST3-specific protective monoclonal antibodies. The glycan array screens identified a tetrasaccharide that was selected for in-depth immunological evaluation. The tetrasaccharide-CRM197 carrier protein conjugate elicited protective immunity as evidenced by opsonophagocytosis assays and protection against pneumonia cau...

European Respiratory Journal, 2016

Introduction: Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortalit... more Introduction: Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortality worldwide. Streptococcus pneumoniae ( S.p. ) is the most frequent causal pathogen identified in CAP.Despite efficient antimicrobial therapy, CAP can induce pulmonary endothelial hyperpermeability resulting in life-threatening lung failure due to an exaggerated host-pathogen interaction. Angiopoietin- (Ang-)1 mediated Tie2-activation reduces and the Ang-1 antagonist Ang-2 increases inflammation and endothelial permeability in sepsis. “Vasculotide” (VT) is a PEGylated (polyethylene glycol) Tie2-agonist mimicking Ang-1. The aim of our study was to investigate experimentally whether VT could diminish pneumonia-induced lung injury. Methods: Human and murine lung endothelial cells were investigated by electrical cell-substrate impedance sensing (ECIS) and immunofluorescence staining. Pulmonary hyperpermeability was quantified in VT-pretreated isolated perfused and ventilated mouse lungs stimulated with the pneumococcal exotoxin pneumolysin (PLY). Also, S.p. infected mice were therapeutically treated with VT. Results: Pretreatment with VT protected lung endothelial cell-monolayers from PLY-induced disruption. Also, decreased PLY-induced pulmonary permeability of isolated mouse lungs was observed in the VT-treated group in comparison to the untreated group. Likewise, therapeutic treatment with VT of S.p. infected mice significantly reduced pneumonia-induced hyperpermeability. Conclusion: VT protected pulmonary endothelial integrity and reduced lung permeability in different models of pneumococcal pneumonia. Thus, VT may provide a novel perspective as adjunctive therapy in addition to antibotics. Support: DFG (SFB/TR84,C6).

American Journal of Respiratory Cell and Molecular Biology, Sep 1, 2013

Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypert... more Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypertension (PH), is modulated by nitric oxide (NO). NO synthesis can be decreased by asymmetric dimethylarginine (ADMA), which is degraded by dimethylarginine dimethylaminohydrolase-1 (DDAH1). We investigated the effects of DDAH1 overexpression (DDAH1 tg) on HPV and chronic hypoxia-induced PH. HPV was measured during acute (10 min) and sustained (3 h) hypoxia in isolated mouse lungs. Chronic PH was induced by the exposure of mice to 4 weeks of hypoxia. ADMA and cyclic 39,59-guanosine monophosphate (cGMP) were determined by ELISA, and NO generation was determined by chemiluminescence. DDAH1 overexpression exerted no effects on acute HPV. However, DDAH1 tg mice showed decreased sustained HPV compared with wild-type (WT) mice. Concomitantly, ADMA was decreased, and concentrations of NO and cGMP were significantly increased in DDAH1 tg. The administration of either N v-nitro-L-arginine or 1H-[1,2,4]oxadiazolo [4,3-a] quinoxalin-1-one potentiated sustained HPV and partly abolished the differences in sustained HPV between WT and DDAH1 tg mice. The overexpression of DDAH1 exerted no effect on the development of chronic hypoxia-induced PH. DDAH1 overexpression selectively decreased the sustained phase of HPV, partly via activation of the NO-cGMP pathway. Thus, increased ADMA concentrations modulate sustained HPV, but not acute HPV or chronic hypoxia-induced PH.

The Journal of Immunology, 2010

The Journal of Immunology, Jun 15, 2009

In the context of allergic immune responses, activation of STAT6 is pivotal for Th2-mediated IgE ... more In the context of allergic immune responses, activation of STAT6 is pivotal for Th2-mediated IgE production and development of airway inflammation and hyperreactivity. We analyzed whether gene silencing of STAT6 expression by RNA interference was able to suppress allergen-induced immune and airway responses. Knockdown effectiveness of three different STAT6 siRNA molecules was analyzed in murine and human cell cultures. The most potent siRNA was used for further testing in a murine model of allergen-induced airway inflammation and airway hyperreactivity (AHR). BALB/c mice were sensitized with OVA/alum twice i.p. (days 1 and 14), and challenged via the airways with allergen (days 28-30). Intranasal application of STAT6 siRNA before and during airway allergen challenges reduced levels of infiltrating cells, especially of eosinophils, in the bronchoalveolar lavage fluid, compared with GFP siRNA-treated sensitized and challenged controls. Allergen-induced alterations in lung tissues (goblet cell hyperplasia, peribronchial inflammation with eosinophils and CD4 T cells) were significantly reduced after STAT6 siRNA treatment. Associated with decreased inflammation was a significant inhibition of the development of allergen-induced in vivo AHR after STAT6 siRNA treatment, compared with GFP siRNAtreated sensitized and challenged controls. Importantly, mRNA and protein expression levels of IL-4 and IL-13 in lung tissues of STAT6-siRNA treated mice were significantly diminished compared with sensitized and challenged controls. These data show that targeting the key transcription factor STAT6 by siRNA effectively blocks the development of cardinal features of allergic airway disease, like allergen-induced airway inflammation and AHR. It may thus be considered as putative approach for treatment of allergic airway diseases such as asthma.

European Respiratory Journal, Sep 1, 2014

Objectives: Currently approved pneumococcal vaccines comprise only a part of the clinically relev... more Objectives: Currently approved pneumococcal vaccines comprise only a part of the clinically relevant S. pneumoniae serotypes. Moreover, high costs limit their administration, particularly in developing countries. An innovative chemical method enables the synthesis of almost any capsular polysaccharide antigen of S. pneumoniae and thereby, a cost-efficient rapid production of polyvalent vaccines according to the clinical and epidemiological necessity. In the current pilot study, the protective effect of a new glycoconjugate vaccine consisting of a synthetic capsular oligosaccharide of S. pneumoniae serotype 3 was examined. Methods: Mice were subcutaneously immunised with monovalent glycoconjugate with or without the adjuvant aluminium hydroxide (alum) and boosted twice at two week intervals prior to transnasal infection with S. pneumoniae serotype 3. Results : The synthetic glycoconjugate vaccine induced the production of specific antibodies against serotype 3 capsular oligosaccharide in mice. Pneumococcal infection was associated with hypothermia and loss of body weight in non-vaccinated controls and glycoconjugate vaccinated mice, but not in mice immunised with glycoconjugate and alum. Bacterial load of lung, bronchoalveolar lavage fluid and blood was significantly decreased in mice vaccinated in combination with the adjuvant. Immunisation with glycoconjugate and alum prior to pneumococcal infection reduced cytokine release into the bronchoalveolar space and prevented damage of the endoepithelial barrier. Conclusion: Immunisation with S. pneumoniae serotype 3 glycoconjugate protected mice from severe pneumococcal pneumonia by inducing protective antibodies. Funding: SFB/TR84 .

Pneumologie, 2009

Bei Pneumonie kann uberschiesende Entzundung zu lebensbedrohlichen Storungen der Oxygenierung fuh... more Bei Pneumonie kann uberschiesende Entzundung zu lebensbedrohlichen Storungen der Oxygenierung fuhren. Insbesondere die Pneumokokken-Pneumonie ist durch eine massive Freisetzung pro-entzundlicher Mediatoren gepragt. Gleichwohl ist wenig uber der Entzundung entgegenwirkende Faktoren bei Pneumonie bekannt. Wir pruften die Hypothese, dass der Transkriptionsfaktor KLF2 Pneumokokken-induzierter Epithelzellaktivierung entgegenwirkt. Infektion mit Pneumokokken induziert die Expression von KLF2 (Proteinexpression, Aktivierung eines KLF2-Reportergens) in kultivierten humanen Epithelzellen und in infizierten Mauslungen in vivo. Die Induktion von KLF2 erfolgt nach Aktivierung von transmembranaren TLR2 und zytosolischem NOD2. Stimulation der Zellen mit TLR2- oder Nod2-Liganden oder Pneumokokken fuhrt zur Phosphorylierung der regulatorischen PI3-Kinase Untereinheit p55. Blockade der Pi3-Kinase inhibiert die Expression von KLF2 (Proteinexpression, Reportergen). Dagegen ist die KLF2 Expression unabhangig von den Kinasen p38, ERK und JNK. Experimente mit transienter Uberexpression von KLF2 oder Depletion von KLF2 mittels siRNA demonstrieren, dass KLF2 der Expression NF-kappaB-abhangiger Gene entgegenwirkt. Zusammengefasst wurde a) die PI3-Kinase als Element des TLR2- und Nod2-Signalpfades identifiziert und konnte b) KLF2 einen wichtigen gegenregulatorischen Faktor zur Vermeidung uberschiesender Entzundungsreaktionen bei Pneumonie darstellen.

American journal of respiratory cell and molecular biology, Jan 29, 2015

The cation channel transient receptor potential vanilloid 4 (TRPV4) is expressed in endothelial a... more The cation channel transient receptor potential vanilloid 4 (TRPV4) is expressed in endothelial and immune cells; however, its role in acute lung injury (ALI) is unclear. The functional relevance of TRPV4 was assessed in vivo, in isolated murine lungs and in isolated neutrophils. Genetic deficiency of TRPV4 attenuated the functional, histological and inflammatory hallmarks of acid-induced ALI. Similar protection was obtained with prophylactic administration of the TRPV4 inhibitor GSK2193874; however, therapeutic administration of the TRPV4 inhibitor HC-067047 after ALI induction had no beneficial effect. In isolated lungs, platelet-activating factor (PAF) increased vascular permeability in lungs perfused with trpv4+/+ more than with trpv4-/- blood independent of lung genotype, suggesting a contribution of TRPV4 on blood cells to lung vascular barrier failure. In neutrophils, TRPV4 inhibition or deficiency attenuated the PAF-induced increase in intracellular calcium. PAF induced form...

A47. DIAGNOSTIC TECHNIQUES AND MONITORING, 2012

PLOS ONE, 2015

The innate immune system employs C-type lectin receptors (CLRs) to recognize carbohydrate structu... more The innate immune system employs C-type lectin receptors (CLRs) to recognize carbohydrate structures on pathogens and self-antigens. The Macrophage-inducible C-type lectin (Mincle) is a FcRγ-coupled CLR that was shown to bind to mycobacterial cord factor as well as certain fungal species. However, since CLR functions during bacterial infections have not yet been investigated thoroughly, we aimed to examine their function in Streptococcus pneumonia infection. Binding studies using a library of recombinantly expressed CLR-Fc fusion proteins indicated a specific, Ca 2+-dependent, and serotype-specific binding of Mincle to S. pneumonia. Subsequent experiments with different Mincle-expressing cells as well as Mincle-deficient mice, however, revealed a limited role of this receptor in bacterial phagocytosis, neutrophil-mediated killing, cytokine production, and antibacterial immune response during pneumonia. Collectively, our results indicate that Mincle is able to recognize S. pneumonia but is not required for the anti-pneumococcal innate immune response.

The Journal of Immunology, 2009

Different NOD-like receptors, including NLRP1, NLRP3, and NLRC4, as well as the recently identifi... more Different NOD-like receptors, including NLRP1, NLRP3, and NLRC4, as well as the recently identified HIN-200 protein, AIM2, form multiprotein complexes called inflammasomes, which mediate caspase-1–dependent processing of pro-IL-1β. Listeria monocytogenes is an intracellular pathogen that is actively phagocytosed by monocytes/macrophages and subsequently escapes from the phagosome into the host cell cytosol, depending on its pore-forming toxin listeriolysin O (LLO). In this study, we demonstrate that human PBMCs produced mature IL-1β when infected with wild-type L. monocytogenes or when treated with purified LLO. L. monocytogenes mutants lacking LLO or expressing a noncytolytic LLO as well as the avirulent Listeria innocua induced strongly impaired IL-1β production. RNA interference and inhibitor experiments in human PBMCs as well as experiments in Nlrp3 and Rip2 knockout bone marrow-derived macrophages demonstrated that the Listeria-induced IL-1β release was dependent on ASC, caspas...

The Journal of Immunology, 2008

Legionella pneumophila causes severe pneumonia. Acetylation of histones is thought to be an impor... more Legionella pneumophila causes severe pneumonia. Acetylation of histones is thought to be an important regulator of gene transcription, but its impact on L. pneumophila-induced expression of proinflammatory cytokines is unknown. L. pneumophila strain 130b induced the expression of the important chemoattractant IL-8 and genome-wide histone modifications in human lung epithelial A549 cells. We analyzed the IL-8-promoter and found that histone H4 was acetylated and H3 was phosphorylated at Ser10 and acetylated at Lys14, followed by transcription factor NF-κB. Recruitment of RNA polymerase II to the IL-8 promoter corresponded with increases in gene transcription. Histone modification and IL-8 release were dependent on p38 kinase and NF-κB pathways. Legionella-induced IL-8 expression was decreased by histone acetylase (HAT) inhibitor anacardic acid and enhanced by histone deacetylase (HDAC) inhibitor trichostatin A. After Legionella infection, HATs p300 and CREB-binding protein were time-...

The Journal of Immunology, 2010

The release of potent proinflammatory mediators is not only central for mounting an efficient hos... more The release of potent proinflammatory mediators is not only central for mounting an efficient host response, but also bears the risk for deleterious excessive tissue-damaging inflammation. This is highlighted in severe pneumococcal pneumonia, in which the delicate balance between a robust inflammatory response to kill pneumococci and loss of organ function determines the outcome of disease. In this study, we tested the hypothesis that Krüppel-like factor (KLF)2 counterregulates pneumococci- and pattern recognition receptor-related human lung cell activation. Pneumococci induced KLF2 expression in vitro and in a murine pneumonia model. Activation of TLR2- and nucleotide-binding oligomerization domain protein 2-related signaling induced KLF2 expression in a PI3K-dependent manner. Overexpression of KLF2 downregulated pneumococci-, TLR2-, and nucleotide-binding oligomerization domain protein 2-related NF-κB–dependent gene expression and IL-8 release, whereas small interfering RNA-based ...

European Respiratory Journal, 2012

European Journal of Immunology, 2013

Formation of the splenic marginal zone (MZ) depends on the alternative NF-κB signaling pathway. R... more Formation of the splenic marginal zone (MZ) depends on the alternative NF-κB signaling pathway. Recently, we reported that unrestricted activation of this pathway in NF-κB2/ p100-deficient (p100 −/−) knock-in mice alters the phenotype of MZ stroma and B cells. Here, we show that lack of the p100 inhibitor resulted in an expansion of both MZ B and peritoneal B-1 cells. However, these cells failed to generate proliferating blasts in response to T-cell-independent type 2 (TI-2) Ags, correlating with dampened IgM and absent IgG3 responses. This phenotype was in part due to increased activity of the NF-κB subunit RelB. Moreover, p100 −/− →B6 BM chimeras were more susceptible to infection by encapsulated Streptococcus pneumoniae bacteria, pathogens that induce TI-2 responses. In contrast to the TI-2 defect, p100 deficiency did not impair immune responses to the TI-1 Ag LPS and p100 −/− MZ B cells showed normal Ag transportation into B-cell follicles. Furthermore, p100 −/− MZ B and B-1 cells failed to respond to TI-2 Ags in the presence of WT accessory cells. Thus, NF-κB2/p100 deficiency caused a predominant B-cell-intrinsic TI-2 defect that could largely be attributed to impaired proliferation of plasmablasts. Importantly, p100 was also necessary for efficient defense against clinically relevant TI-2 pathogens.

American Journal of Respiratory Cell and Molecular Biology, 2013

Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypert... more Acute and sustained hypoxic pulmonary vasoconstriction (HPV), as well as chronic pulmonary hypertension (PH), is modulated by nitric oxide (NO). NO synthesis can be decreased by asymmetric dimethylarginine (ADMA), which is degraded by dimethylarginine dimethylaminohydrolase-1 (DDAH1). We investigated the effects of DDAH1 overexpression (DDAH1 tg) on HPV and chronic hypoxia-induced PH. HPV was measured during acute (10 min) and sustained (3 h) hypoxia in isolated mouse lungs. Chronic PH was induced by the exposure of mice to 4 weeks of hypoxia. ADMA and cyclic 39,59-guanosine monophosphate (cGMP) were determined by ELISA, and NO generation was determined by chemiluminescence. DDAH1 overexpression exerted no effects on acute HPV. However, DDAH1 tg mice showed decreased sustained HPV compared with wild-type (WT) mice. Concomitantly, ADMA was decreased, and concentrations of NO and cGMP were significantly increased in DDAH1 tg. The administration of either N v-nitro-L-arginine or 1H-[1,2,4]oxadiazolo [4,3-a] quinoxalin-1-one potentiated sustained HPV and partly abolished the differences in sustained HPV between WT and DDAH1 tg mice. The overexpression of DDAH1 exerted no effect on the development of chronic hypoxia-induced PH. DDAH1 overexpression selectively decreased the sustained phase of HPV, partly via activation of the NO-cGMP pathway. Thus, increased ADMA concentrations modulate sustained HPV, but not acute HPV or chronic hypoxia-induced PH.

DMW - Deutsche Medizinische Wochenschrift, 2017

Infections are the most common cause of granulomatous lung diseases. A variety of different patho... more Infections are the most common cause of granulomatous lung diseases. A variety of different pathogens can cause granuloma formation. The diagnosis requires consideration of endemic characteristics, patients' predispositions as well as specific requirements for pathogen detection. The aim of this review is to give a short overview of the most important causative pathogens and facilitate the differential diagnostic approach of granulomatous lung diseases.

Cell chemical biology, Jan 17, 2016

The identification of immunogenic glycotopes that render glycoconjugate vaccines protective is ke... more The identification of immunogenic glycotopes that render glycoconjugate vaccines protective is key to improving vaccine efficacy. Synthetic oligosaccharides are an attractive alternative to the heterogeneous preparations of purified polysaccharides that most marketed glycoconjugate vaccines are based on. To investigate the potency of semi-synthetic glycoconjugates, we chose the least-efficient serotype in the current pneumococcal conjugate vaccine Prevnar 13, Streptococcus pneumoniae serotype 3 (ST3). Glycan arrays containing synthetic ST3 repeating unit oligosaccharides were used to screen a human reference serum for antibodies and to define the recognition site of two ST3-specific protective monoclonal antibodies. The glycan array screens identified a tetrasaccharide that was selected for in-depth immunological evaluation. The tetrasaccharide-CRM197 carrier protein conjugate elicited protective immunity as evidenced by opsonophagocytosis assays and protection against pneumonia cau...