Bernd Schmeck

Charité Universitätsmedizin Berlin, Berlín, Berlin, Germany

Are you Bernd Schmeck?

Claim your profile

Publications (72)291.08 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The release of potent pro-inflammatory mediators is crucial to mounting an efficient host response during infections. However, excessive inflammation may lead to deleterious tissue damage. This is highlighted in severe pneumococcal pneumonia, in which the delicate balance between a robust inflammatory response necessary to kill pneumococci and the loss of organ function determines the outcome of the disease. Therefore, we assessed the regulation of the potent anti-inflammatory cytokine IL-10 in pneumococcal infection via western blot, ELISA and Chromatin immunoprecipitation analysis. S. pneumoniae induced IL-10 expression in mouse lungs and human lung epithelial cells. Pneumococcal infection resulted in a strong induction of Krueppel-like factor 4 (KLF4) expression in vivo and in vitro. The induction of both, IL-10 and KLF4, is mediated by a pathway involving bacterial DNA, TLR9, MyD88, and Src kinase. KLF4 is recruited to the il10 promoter, and siRNA-mediated knockdown of KLF4 expression blocked IL-10 expression during pneumococcal infection. In conclusion, KLF4 is induced in a bacterial DNA-TLR9-Src-dependent manner and regulates IL-10 expression, linking the detection of bacterial DNA by TLR9 to the control of an inflammatory response.
    European Respiratory Journal 05/2012; · 6.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chlamydophila pneumoniae causes acute respiratory tract infections and has been associated with development of asthma and atherosclerosis. The production of IL-1β, a key mediator of acute and chronic inflammation, is regulated on a transcriptional level and additionally on a posttranslational level by inflammasomes. In the present study we show that C. pneumoniae-infected human mononuclear cells produce IL-1β protein depending on an inflammasome consisting of NLRP3, the adapter protein ASC and caspase-1. We further found that the small GTPase Rac1 is activated in C. pneumoniae-infected cells. Importantly, studies with specific inhibitors as well as siRNA show that Rac1 regulates inflammasome activation in C. pneumoniae-infected cells. In conclusion, C. pneumoniae infection of mononuclear cells stimulates IL-1β production dependent on a NLRP3 inflammasome-mediated processing of proIL-1β which is controlled by Rac1.
    PLoS ONE 01/2012; 7(1):e30379. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Severe community- and hospital-acquired pneumonia is caused by Legionella pneumophila. Lung airway and alveolar epithelial cells comprise an important sentinel system in airborne infections. Although interleukin (IL)-6 is known as a central regulator of the immune response in pneumonia, its regulation in the lung is widely unknown. Herein, we demonstrate that different L. pneumophila strains induce delayed expression of IL-6 in comparison with IL-8 by human lung epithelial cells. IL-6 expression depended, at early time points, on flagellin recognition by Toll-like receptor (TLR)5, activity of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)1 and p38 mitogen-activated protein (MAP) kinase, and, at later time points, on the type-IV secretion system. In the same manner, but more rapidly, the recently described transcription factor IκBζ was induced by Legionella infection and, binding to the nuclear factor (NF)-κB subunit p50 - recruited to the il6 promoter together with CCAAT-enhancer-binding protein β and phosphorylated activator protein-1 subunit cJun. Similarly, histone modifications and NF-κB subunit p65/RelA appeared at the iκbζ and subsequently at the il6 gene promoter, thereby initiating gene expression. Gene silencing of IκBζ reduced Legionella-related IL-6 expression by 41%. Overall, these data indicate a sequence of flagellin/TLR5- and type IV-dependent IκBζ expression, recruitment of IκBζ/p50 to the il6 promoter, chromatin remodelling and subsequent IL-6 transcription in L. pneumophila-infected lung epithelial cells.
    European Respiratory Journal 03/2011; 37(3):648-57. · 6.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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-kappaB-dependent gene expression and IL-8 release, whereas small interfering RNA-based silencing of KLF2 provoked an enhanced inflammatory response. KLF2-dependent downregulation of NF-kappaB activity is partly reversible by overexpression of the histone acetylase p300/CREB-binding protein-associated factor. In conclusion, KLF2 may act as a counterregulatory transcription factor in pneumococci- and pattern recognition receptor-related proinflammatory activation of lung cells, thereby preventing lung hyperinflammation and subsequent organ failure.
    The Journal of Immunology 07/2010; 185(1):597-604. · 5.52 Impact Factor
  • Pneumologie 03/2010; 64.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Legionella pneumophila is an important causative agent of severe pneumonia in humans. Human alveolar epithelium and macrophages are effective barriers for inhaled microorganisms and actively participate in the initiation of innate host defense. The beta defensin-3 (hBD-3), an antimicrobial peptide is an important component of the innate immune response of the human lung. Therefore we hypothesize that hBD-3 might be important for immune defense towards L. pneumophila. We investigated the effects of L. pneumophila and different TLR agonists on pulmonary cells in regard to hBD-3 expression by ELISA. Furthermore, siRNA-mediated inhibition of TLRs as well as chemical inhibition of potential downstream signaling molecules was used for functional analysis. L. pneumophila induced release of hBD-3 in pulmonary epithelium and alveolar macrophages. A similar response was observed when epithelial cells were treated with different TLR agonists. Inhibition of TLR2, TLR5, and TLR9 expression led to a decreased hBD-3 expression. Furthermore expression of hBD-3 was mediated through a JNK dependent activation of AP-1 (c-Jun) but appeared to be independent of NF-kappaB. Additionally, we demonstrate that hBD-3 elicited a strong antimicrobial effect on L. pneumophila replication. Taken together, human pulmonary cells produce hBD-3 upon L. pneumophila infection via a TLR-JNK-AP-1-dependent pathway which may contribute to an efficient innate immune defense.
    Respiratory research 01/2010; 11:93. · 3.64 Impact Factor
  • Pneumologie 01/2010; 64(01).
  • [Show abstract] [Hide abstract]
    ABSTRACT: Community-acquired pneumonia is a very common infectious disease associated with significant morbidity and mortality. Streptococcus pneumoniae is the predominant pathogen in this disease, and pneumococcal resistance to multiple antibiotics is increasing. The recently purified bacteriophage endolysin Cpl-1 rapidly and specifically kills pneumococci on contact. The aim of this study was to determine the therapeutic potential of Cpl-1 in a mouse model of severe pneumococcal pneumonia. Controlled, in vivo laboratory study. Female C57/Bl6 mice, 8-12 weeks old. Mice were transnasally infected with pneumococci and therapeutically treated with Cpl-1 or amoxicillin by intraperitoneal injections starting 24 or 48 hours after infection. Judged from clinical appearance, decreased body weight, reduced dynamic lung compliance and Pao2/Fio2 ratio, and morphologic changes in the lungs, mice suffered from severe pneumonia at the onset of therapy. When treatment was commenced 24 hours after infection, 100% Cpl-1-treated and 86% amoxicillin-treated mice survived otherwise fatal pneumonia and showed rapid recovery. When treatment was started 48 hours after infection, mice had developed bacteremia, and three of seven (42%) Cpl-1-treated and five of seven (71%) amoxicillin-treated animals survived. Cpl-1 dramatically reduced pulmonary bacterial counts, and prevented bacteremia, systemic hypotension, and lactate increase when treatment commenced at 24 hours. In vivo, treatment with Cpl-1 or amoxicillin effectively reduced counts of penicillin-susceptible pneumococci. The inflammatory response in Cpl-1-and amoxicillin-treated mice was lower than in untreated mice, as determined by multiplex cytokine assay of lung and blood samples. In human epithelial cell cultures, lysed bacteria evoked less proinflammatory cytokine release and cell death, as compared with viable bacteria. Cpl-1 may provide a new therapeutic option in the treatment of pneumococcal pneumonia.
    Critical care medicine 01/2010; 37(2):642-9. · 6.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Severe pneumococcal pneumonia frequently causes respiratory failure. Both pathogen factors and an uncontrolled host response may contribute to acute lung injury by impairing microvascular barrier function. Phosphodiesterase 2 (PDE2) was examined as a potential target in pneumonia-induced lung microvascular hyperpermeability. Controlled, in vitro, ex vivo, and in vivo laboratory study. Female Balb/C and C57Bl/6 mice, 8-12 weeks old. Human umbilical vein endothelial cells and isolated mouse lungs were challenged with the pneumococcal exotoxin pneumolysin in the presence or absence of the selective PDE2 inhibitors 9-(6-phenyl-2-oxohex-3-yl)-2-(3,4-dimethoxybenzyl)-purin-6one (PDP) or hydroxy-PDP. Transcellular electrical resistance or human serum albumin leakage in bronchoalveolar lavage fluid was determined, respectively. In addition, we induced pneumococcal pneumonia in mice and treated with hydroxy-PDP via continuous subcutaneous application by osmotic pumps. Human serum albumin leakage in bronchoalveolar lavage fluid was measured 48 hours after transnasal infection, and lung specimens were analyzed by TaqMan real-time polymerase chain reaction and Western blot for PDE2 gene and protein expression. In isolated perfused mouse lungs and in human umbilical vein endothelial cell monolayers, selective inhibition of PDE2 markedly decreased pneumolysin-induced hyperpermeability. Furthermore, in murine pneumococcal pneumonia, pulmonary PDE2-mRNA and -protein expression was significantly increased, and pneumonia-induced vascular permeability was distinctively reduced by PDE2 inhibition. PDE2 inhibition diminished microvascular leakage in pneumococcal pneumonia, and pulmonary PDE2 upregulation may play a crucial role in this respect. Selective PDE2 inhibitors thus may offer a promising therapeutic approach in severe pneumococcal pneumonia.
    Critical care medicine 01/2010; 37(2):584-90. · 6.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mechanical ventilation (MV) is a life saving intervention in acute respiratory failure without alternative. However, particularly in pre-injured lungs, even protective ventilation strategies may evoke ventilator-induced lung injury (VILI), which is characterized by pulmonary inflammation and vascular leakage. Adjuvant pharmacologic strategies in addition to lung protective ventilation to attenuate VILI are lacking. Simvastatin exhibited anti-inflammatory and endothelial barrier stabilizing properties in vitro and in vivo. Mice were ventilated (12 ml/kg; six hours) and subjected to simvastatin (20 mg/kg) or sham treatment. Pulmonary microvascular leakage, oxygenation, pulmonary and systemic neutrophil and monocyte counts and cytokine release in lung and blood plasma were assessed. Further, lung tissue was analyzed by electron microscopy. Mechanical ventilation induced VILI, displayed by increased pulmonary microvascular leakage and endothelial injury, pulmonary recruitment of neutrophils and Gr-1high monocytes, and by liberation of inflammatory cytokines in the lungs. Further, VILI associated systemic inflammation characterized by blood leukocytosis and elevated plasma cytokines was observed. Simvastatin treatment limited pulmonary endothelial injury, attenuated pulmonary hyperpermeability, prevented the recruitment of leukocytes to the lung, reduced pulmonary cytokine levels and improved oxygenation in mechanically ventilated mice. High-dose simvastatin attenuated VILI in mice by reducing MV-induced pulmonary inflammation and hyperpermeability.
    Critical care (London, England) 01/2010; 14(4):R143. · 4.72 Impact Factor
  • Pneumologie 01/2010; 64.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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-1beta. 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-1beta 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-1beta 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-1beta release was dependent on ASC, caspase-1, and NLRP3, whereas NOD2, Rip2, NLRP1, NLRP6, NLRP12, NLRC4, and AIM2 appeared to be dispensable. We found that L. monocytogenes-induced IL-1beta production was largely dependent on phagosomal acidification and cathepsin B release, whereas purified LLO activated an IL-1beta production independently of these mechanisms. Our results indicate that L. monocytogenes-infected human PBMCs produced IL-1beta, largely depending on an LLO-mediated phagosomal rupture and cathepsin B release, which is sensed by Nlrp3. In addition, an LLO-dependent but cathepsin B-independent NLRP3 activation might contribute to some extent to the IL-1beta production in L. monocytogenes-infected cells.
    The Journal of Immunology 12/2009; 184(2):922-30. · 5.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Legionella pneumophila is an important causative agent of severe pneumonia in humans. The human alveolar epithelium is an effective barrier for inhaled microorganisms and actively participates in the initiation of innate host defense. Although secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) is essential for the elimination of invading Legionella spp., mechanisms of Legionella pneumophila-induced release of this cytokine are widely unknown. In this study, we have demonstrated a toll-like receptor (TLR)2- and TLR5-dependent release of GM-CSF in L. pneumophila-infected human alveolar epithelial cells. GM-CSF secretion was not dependent on the bacteria type II or type IV secretion system. Furthermore, an increase in protein kinase C (PKC) activity, particularly PKC(alpha) and PKC(epsilon), was noted. Blocking of PKC(alpha) and PKC(epsilon) activity or expression, but not of PKC(beta), PKC(delta), PKC(eta), PKC(theta), and PKC(zeta), significantly reduced the synthesis of GM-CSF in infected cells. While PKC(alpha) was critical for the initiation of a nuclear factor-kappaB-mediated GM-CSF expression, PKC(epsilon) regulated GM-CSF production via activator protein 1. Thus, differential regulation of GM-CSF, production by PKC isoforms, contributes to the host response in Legionnaires' disease.
    European Respiratory Journal 04/2009; 34(5):1171-9. · 6.36 Impact Factor
  • Pneumologie 03/2009; 63(02).
  • [Show abstract] [Hide abstract]
    ABSTRACT: Activation of the endothelium by oxidized low-density lipoprotein (oxLDL) has been implicated in the development of atherosclerosis. Histone modifications impact on the transcriptional activity state of genes. We tested the hypothesis that oxLDL-induced inflammatory gene expression is regulated by histone modifications and experienced the effect of statins on these alterations. OxLDL-related interleukin-8 (IL-8) and monocyte-chemoattractant protein-1 (MCP-1) secretion in endothelial cells was reduced by statins but enhanced by histone deacetylase inhibitors. OxLDL induced lectin-like oxidized LDL receptor-1 (LOX-1) and extracellular regulated kinases (ERK1/2)-dependent acetylation of histone H3 and H4 as well as phosphorylation of histone H3, both globally and on the promoters of il8 and mcp1. Pretreatment of oxLDL-exposed cells with statins reduced the above mentioned histone modification, as well as recruitment of CREB binding protein (CBP) 300, NF-kappaB, and of RNA polymerase II but prevented loss of binding of histone deacetylase (HDAC)-1 and -2 at the il8 and mcp1 gene promoters. OxLDL reduced HDAC1 and 2 expression, and statins partly restored global HDAC-activity. Statin-related effects were reverted with mevalonate. In situ experiments indicated decreased expression of HDAC2 in endothelial cells in atherosclerotic plaques of human coronary arteries. Histone modifications seem to play an important role in atherosclerosis.
    Arteriosclerosis Thrombosis and Vascular Biology 02/2009; 29(3):380-6. · 6.34 Impact Factor
  • Pneumologie 01/2009; 63.
  • Pneumologie 01/2009; 63.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The nucleotide-binding domain and leucine-rich repeat containing protein NOD2 serves as a cytoplasmic pattern recognition molecule sensing bacterial muramyl dipeptide (MDP), whereas TLR2 mediates cell surface recognition of bacterial lipopeptides. In this study, we show that NOD2 stimulation activated Rac1 in human THP-1 cells and primary human monocytes. Rac1 inhibition or knock-down, or actin cytoskeleton disruption increased MDP-stimulated IL-8 secretion and NF-kappaB activation, whereas TLR2-dependent cell activation was suppressed by Rac1 inhibition. p21-activated kinase [Pak]-interacting exchange factor (beta-PIX) plays a role in this negative regulation, because knock-down of beta-PIX also led to increased NOD2-mediated but not TLR2-mediated IL-8 secretion, and coimmunoprecipitation experiments demonstrated that NOD2 interacted with beta-PIX as well as Rac1 upon MDP stimulation. Moreover, knock-down of beta-PIX or Rac1 abrogated membrane recruitment of NOD2, and interaction of NOD2 with its negative regulator Erbin. Overall, our data indicate that beta-PIX and Rac1 mediate trafficking and negative regulation of NOD2-dependent signaling which is different from Rac1's positive regulatory role in TLR2 signaling.
    The Journal of Immunology 09/2008; 181(4):2664-71. · 5.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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 Ser(10) and acetylated at Lys(14), followed by transcription factor NF-kappaB. 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-kappaB 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-dependently recruited to the IL-8 promoter, whereas HDAC1 and HDAC5 first decreased and later reappeared at the promoter. Legionella specifically induced expression of HDAC5 but not of other HDACs in lung epithelial cells, but knockdown of HDAC1 or 5 did not alter IL-8 release. Furthermore, Legionella-induced cytokine release, promoter-specific histone modifications, and RNA polymerase II recruitment were reduced in infection with flagellin-deletion mutants. Legionella-induced histone modification as well as HAT-/HDAC-dependent IL-8 release could also be shown in primary lung epithelial cells. In summary, histone acetylation seems to be important for the regulation of proinflammatory gene expression in L. pneumophila infected lung epithelial cells. These pathways may contribute to the host response in Legionnaires' disease.
    The Journal of Immunology 08/2008; 181(2):940-7. · 5.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Airway hyperresponsiveness (AHR) is a hallmark of bronchial asthma. Increased expression of smooth muscle contractile proteins or increased responsiveness of the contractile apparatus due to RhoA/Rho-kinase activation may contribute to AHR. BALB/c mice developed AHR following systemic sensitization by intraperitoneal injections of 20 microg ovalbumin (OVA) in presence of 2mg Al(OH)(3) on days 1 and 14, and airway challenge by 1% OVA-inhalation for 20 min each on days 28, 29 and 30. As assessed by Western blot, protein expression of RhoA, MLC (myosin light chain) and smMLCK (smooth muscle myosin light chain kinase) was increased in lungs of OVA/OVA-animals with AHR, as well as in lungs of OVA-sensitized and sham-challenged animals (OVA/PBS) without AHR, compared with lungs of PBS/PBS-animals. Pretreatment with the specific Rho-kinase inhibitor Y-27632 reduced MLC-phosphorylation and AHR. Contribution of Rho-kinase to bronchoconstriction was increased in lungs of OVA/OVA-animals compared with OVA/PBS- and PBS/PBS-animals, respectively. Furthermore, bronchoconstriction following MCh stimulation was significantly reduced after Y-27632 application. In conclusion, systemic allergen-sensitization increased pulmonary expression of proteins involved in smooth muscle contraction, which may contribute to development of AHR. However, this observation was independent from local allergen challenge, suggesting that additional cofactors may be required for the activation of Rho-kinase and thereby the induction of AHR. Rho-kinase may play an important role in murine AHR, and the bronchodilating action of Rho-kinase inhibition may offer a new therapeutic perspective in obstructive airway disease.
    Experimental and Toxicologic Pathology 07/2008; 60(1):9-15. · 2.62 Impact Factor