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ABSTRACT: Interleukin-1 receptor like 1 (ST2) is a negative regulator of Toll-like receptor (TLR) signaling. TLRs are important for host defense during respiratory tract infections by both influenza and Streptococcus (S.) pneumoniae. Enhanced susceptibility to pneumococcal pneumonia is an important complication following influenza virus infection. We here sought to determine the role of ST2 in primary influenza A infection and secondary pneumococcal pneumonia. ST2 knockout (st2 -/-) and wild-type (WT) mice were intranasally infected with influenza A virus; in some experiments mice were infected 2 weeks later with S. pneumoniae. Both mouse strains cleared the virus similarly during the first 14 days of influenza infection and had recovered their weights equally at day 14. Overall st2-/- mice tended to have a stronger pulmonary inflammatory response upon infection with influenza; especially 14 days after infection modest but statistically significant elevations were seen in lung IL-6, IL-1β, KC, IL-10, and IL-33 concentrations and myeloperoxidase levels, indicative of enhanced neutrophil activity. Interestingly, bacterial lung loads were higher in st2-/- mice during the later stages of secondary pneumococcal pneumonia, which was associated with relatively increased lung IFN-γ levels. ST2 deficiency did not impact on gross lung pathology in either influenza or secondary S. pneumoniae pneumonia. These data show that ST2 plays a limited anti-inflammatory role during both primary influenza and postinfluenza pneumococcal pneumonia.
PLoS ONE 01/2013; 8(3):e58191. · 4.09 Impact Factor
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J Daan de Boer,
Joris J T H Roelofs, Alex F de Vos,
Regina de Beer,
Marcel Schouten,
Tijmen J Hommes,
Arie J Hoogendijk,
Onno J de Boer,
Ingrid Stroo,
Jaring S van der Zee,
Cornelis van 't Veer,
Tom van der Poll
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ABSTRACT: Abstract The complex biology of asthma compels to use more relevant human allergens, such as house dust mite (HDM), to improve translation of animal models to human asthma. Lipopolysaccharide (LPS) exposure is associated with aggravation of asthma but mechanisms remain unclear. Here, we studied the effects of increasing LPS doses on HDM-evoked allergic lung inflammation. To this end mice were intranasally sensitized and challenged with HDM with or without increasing doses of LPS (0.001 - 10 µg). LPS dose-dependently inhibited HDM-induced eosinophil recruitment into the lungs and mucus production in the airways. LPS attenuated the production of Th2-cytokines (IL-4, IL-5, IL-10, IL-13) in HDM-challenged lungs, while enhancing HDM-induced release of IL-17, IL-33, IFN-γ and TNF-α. The shift towards a Th1 inflammatory response was further illustrated by a predominant neutrophilic lung inflammation after LPS administration at higher doses. LPS did not influence HDM-induced plasma IgE levels. While LPS did not significantly impact on activation of coagulation or complement in HDM-challenged lungs, it reduced HDM-initiated endothelial cell activation. This study is the first study to give insight in the effect of LPS in an allergic lung inflammation model making use of a clinically relevant allergen without systemic adjuvant, revealing that LPS dose-dependently inhibits HDM-induced pulmonary Th2 responses.
American Journal of Respiratory Cell and Molecular Biology 12/2012; · 5.13 Impact Factor
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Ahmed Achouiti,
Thomas Vogl,
Constantin F Urban,
Marc Röhm,
Tijmen J Hommes,
Marieke A D van Zoelen,
Sandrine Florquin,
Johannes Roth,
Cornelis van 't Veer, Alex F de Vos,
Tom van der Poll
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ABSTRACT: Klebsiella (K.) pneumoniae is a common cause of pneumonia-derived sepsis. Myeloid related protein 8 (MRP8, S100A8) and MRP14 (S100A9) are the most abundant cytoplasmic proteins in neutrophils. They can form MRP8/14 heterodimers that are released upon cell stress stimuli. MRP8/14 reportedly exerts antimicrobial activity, but in acute fulminant sepsis models MRP8/14 has been found to contribute to organ damage and death. We here determined the role of MRP8/14 in K. pneumoniae sepsis originating from the lungs, using an established model characterized by gradual growth of bacteria with subsequent dissemination. Infection resulted in gradually increasing MRP8/14 levels in lungs and plasma. Mrp14 deficient (mrp14(-/-)) mice, unable to form MRP8/14 heterodimers, showed enhanced bacterial dissemination accompanied by increased organ damage and a reduced survival. Mrp14(-/-) macrophages were reduced in their capacity to phagocytose Klebsiella. In addition, recombinant MRP8/14 heterodimers, but not MRP8 or MRP14 alone, prevented growth of Klebsiella in vitro through chelation of divalent cations. Neutrophil extracellular traps (NETs) prepared from wildtype but not from mrp14(-/-) neutrophils inhibited Klebsiella growth; in accordance, the capacity of human NETs to kill Klebsiella was strongly impaired by an anti-MRP14 antibody or the addition of zinc. These results identify MRP8/14 as key player in protective innate immunity during Klebsiella pneumonia.
PLoS Pathogens 10/2012; 8(10):e1002987. · 9.13 Impact Factor
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ABSTRACT: Lipopolysaccharide (LPS) is ubiquitous in the environment. Inhalation of LPS has been implicated in the pathogenesis and/or severity of several lung diseases, including pneumonia, chronic obstructive pulmonary disease and asthma. Alveolar macrophages are the main resident leukocytes exposed to inhaled antigens. To obtain insight into which innate immune pathways become activated within human alveolar macrophages upon exposure to LPS in vivo, we conducted a study in eight healthy humans, in which we instilled sterile saline into a lung segment by bronchoscope, followed by instillation of LPS into the contralateral lung. Six hours later a bilateral bronchoalveolar lavage was performed and whole-genome transcriptional profiling was done on purified alveolar macrophages, comparing cells exposed to saline or LPS from the same individuals. LPS induced differential expression of 2932 genes in alveolar macrophages; 1520 genes were upregulated, whereas 1440 genes were downregulated. Twenty-six biological functions were overrepresented in LPS exposed macrophages, Forty-four canonical pathways affected by LPS were identified, among which the genes associated with the role of pattern recognition receptors in recognition of bacteria and viruses represented the top pathway. Other pathways included cellular immune response, signaling by tumor necrosis factor (receptor) family members, cytokine signaling and glucocorticoid receptor signaling. These results reveal for the first time a large number of functional pathways influenced by the biologically relevant challenge provided by LPS administered into the airways. These data can assist in identifying novel targets for therapeutic intervention in pulmonary diseases associated with LPS exposure, including pneumonia, asthma and chronic obstructive pulmonary disease.
Molecular Medicine 08/2012; · 3.76 Impact Factor
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ABSTRACT: Background. Pneumonia is frequently caused by gram-negative pathogens, among which Klebsiella pneumoniae prominently features. Recognition of pathogen-associated molecular patterns by Toll-like receptors (TLRs) is important for an appropriate immune response during infection. TLR signaling can proceed via 2 distinct routes that are dependent on the adaptor proteins Myeloid differentiation primary response gene (88) (MyD88) and TIR-domain-containing adaptor-inducing interferon-β (TRIF). The aim of the study was to determine the relative contribution of MyD88 and TRIF signaling in resident and hematopoietic cells to host defense during pneumonia. Methods. Bone marrow chimeras of MyD88 deficient/wild type and TRIF mutant/wild type mice were created and infected with K. pneumoniae via the airways. Results. MyD88 in both resident and hematopoietic cells contributed to survival and antibacterial defense in late-stage infection, whereas only TRIF in hematopoietic cells was protective. On the other hand, resident MyD88 and hematopoietic TRIF contributed to distant cellular injury. Resident MyD88 was pivotal for early chemokine release and neutrophil recruitment in the bronchoalveolar space. Conclusions. MyD88- and TRIF-dependent signaling has a differential contribution to host defense in different cell types that changes from early- to late-stage gram-negative pneumonia.
The Journal of Infectious Diseases 08/2012; 206(9):1415-23. · 6.41 Impact Factor
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ABSTRACT: Pneumonia is a common cause of morbidity and mortality and the most frequent source of sepsis. Bacteria that try to invade normally sterile body sites are recognized by innate immune cells through pattern recognition receptors, among which toll-like receptors (TLRs) feature prominently. Interleukin-1 receptor (IL-1R)-associated kinase (IRAK)-M is a proximal inhibitor of TLR signaling expressed by epithelial cells and macrophages in the lung. To determine the role of IRAK-M in host defense against bacterial pneumonia, IRAK-M-deficient (IRAK-M(-/-)) and normal wild-type (WT) mice were infected intranasally with Klebsiella pneumoniae. IRAK-M mRNA was upregulated in lungs of WT mice with Klebsiella pneumonia, and the absence of IRAK-M resulted in a strongly improved host defense as reflected by reduced bacterial growth in the lungs, diminished dissemination to distant body sites, less peripheral tissue injury and better survival rates. Although IRAK-M(-/-) alveolar macrophages displayed enhanced responsiveness toward intact K. pneumoniae and Klebsiella lipopolysaccharide (LPS) in vitro, IRAK-M(-/-) mice did not show increased cytokine or chemokine levels in their lungs after infection in vivo. The extent of lung inflammation was increased in IRAK-M(-/-) mice shortly after K. pneumoniae infection, as determined by semiquantitative scoring of specific components of the inflammatory response in lung tissue slides. These data indicate that IRAK-M impairs host defense during pneumonia caused by a common gram-negative respiratory pathogen.
Molecular Medicine 06/2012; 18(1):1067-75. · 3.76 Impact Factor
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ABSTRACT: Streptococcus pneumoniae is the most common causative organism in community-acquired pneumonia. Pneumococci that try to invade the lower airways are recognized by innate immune cells through pattern recognition receptors, including Toll-like receptors 2, 4, and 9. Interleukin 1 (IL-1) receptor-associated kinase (IRAK)-M is a proximal inhibitor of Toll-like receptor signaling.
To determine the role of IRAK-M in host defense during pneumococcal pneumonia, IRAK-M- deficient and wild-type mice were intranasally infected with S. pneumoniae.
IRAK-M-deficient mice demonstrated a reduced lethality after infection with S. pneumoniae via the airways. Whereas bacterial burdens were similar in IRAK-M-deficient and wild-type mice early (3 hours) after infection, from 24 hours onward the number of pneumococci recovered from lungs and distant body sites were 10-100-fold lower in the former mouse strain. The diminished bacterial growth and dissemination in IRAK-M-deficient mice were preceded by an increased early influx of neutrophils into lung tissue and elevated pulmonary levels of IL-1β and CXCL1. IRAK-M deficiency did not influence bacterial growth after intravenous administration of S. pneumoniae.
These data suggest that IRAK-M impairs host defense during pneumococcal pneumonia at the primary site of infection at least in part by inhibiting the early immune response.
The Journal of Infectious Diseases 04/2012; 205(12):1849-57. · 6.41 Impact Factor
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ABSTRACT: In a mouse model of Escherichia coli sepsis characterized by a primary peritoneal infection with 10(4) E. coli and a gradually growing bacterial load, we here show that the early cytokine response and antibacterial defense are dominated by TLR4 via a cooperative action of MyD88 and Trif. Although MyD88(-/-) mice succumbed earlier than WT mice in this E. coli peritonitis model, Trif(-/-) mice displayed a small but significant survival advantage. Despite a large early deficit in antimicrobial defense, TLR4(-/-) mice showed an unaltered survival with normal neutrophil attraction to the peritoneal cavity and normal or even elevated late cytokine release. TLR2 compensated for the lack of TLR4 because TLR2(-/-)/TLR4(-/-) mice did show decreased neutrophil attraction and increased mortality compared with WT mice. Nearly normal early peritoneal TNFα production and lack of early counterregulating systemic levels of the chemoattractant KC were associated with normal peritoneal neutrophil attraction in TLR4(-/-) mice. Late stage increased TNF, IL-1β, IFN-β, and typical IFN-γ production in TLR4(-/-) mice prompted us to evaluate expression of the negative feedback regulator SOCS-1. Lack of early hepatic SOCS-1 expression in TLR4(-/-) mice explained the late innate production of IFN-γ by the liver in TLR4(-/-) mice in this low dose E. coli peritonitis model. In contrast, early TLR4-induced IFN-γ production is described as a hallmark in high dose E. coli peritonitis models. The present study displays how the kinetics of pro- and anti-inflammatory mechanisms are regulated by TLRs during peritonitis by a gradually growing E. coli load and how these kinetics may affect outcome.
Journal of Biological Chemistry 06/2011; 286(42):36603-18. · 4.77 Impact Factor
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ABSTRACT: In a mouse model of E. coli sepsis characterized by a primary peritoneal infection with 10e4 E. coli and a gradually growing
bacterial load, we here show that the early cytokine response and antibacterial defense are dominated by TLR4 via a cooperative
action of MyD88 and Trif. While MyD88-/- mice succumbed earlier than WT mice in this E. coli peritonitis model, Trif-/- mice
displayed a small but significant survival advantage. Despite a large early deficit in antimicrobial defense TLR4-/- mice
showed an unaltered survival with normal neutrophil attraction to the peritoneal cavity and normal or even elevated late cytokine
release. TLR2 compensated for the lack of TLR4 since TLR2-/-/TLR4-/- mice did show decreased neutrophil attraction and increased
mortality compared to WT mice. Near normal early peritoneal TNFα production and lack of early counter regulating systemic
levels of the chemoattractant KC associated with normal peritoneal neutrophil attraction in TLR4-/- mice. Late stage increased
TNF, IL-1β, IFN-β and typical IFN-γ production in TLR4-/- mice prompted to evaluate expression of the negative feedback regulator
SOCS-1. Lack of early hepatic SOCS-1 expression in TLR4-/- mice explained the late innate production of IFN-γ by the liver
in this low dose E. coli peritonitis model. This while early TLR4 induced IFN-γ production is described as a hallmark in high
dose E. coli peritonitis models. The present study displays how the kinetics of pro- and anti-inflammatory mechanisms are
regulated by TLRs during peritonitis by a gradually growing E. coli load and how these kinetics may affect outcome.
Journal of Biological Chemistry 06/2011; · 4.77 Impact Factor
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ABSTRACT: Streptococcus pneumoniae is the most frequently isolated pathogen responsible for community-acquired pneumonia. Osteopontin is involved in inflammation during both innate and adaptive immunity.
To determine the role of osteopontin in the host response during pneumococcal pneumonia, osteopontin knockout (KO) and normal wild-type (WT) mice were intranasally infected with viable S. pneumoniae.
Pneumonia was associated with a rapid increase in pulmonary osteopontin concentrations in WT mice from 6 h onward. Osteopontin KO mice showed a prolonged survival relative to WT mice, which was accompanied by diminished pulmonary bacterial growth and reduced dissemination to distant body sites. In addition, at 48 h after infection pulmonary inflammation was decreased in osteopontin KO mice as reflected by lower inflammation scores and reduced chemokine concentrations. In contrast to pneumococcal pneumonia, osteopontin deficiency did not influence bacterial growth in primary pneumococcal sepsis induced by direct intravenous infection, suggesting that the detrimental effect of osteopontin on antibacterial defense during pneumonia primarily is exerted in the pulmonary compartment. Moreover, recombinant osteopontin stabilized S. pneumoniae viability in vitro.
These results suggest that the pneumococcus misuses osteopontin in the airways for optimal growth and to cause invasive disease after entering the lower airways.
The Journal of Infectious Diseases 06/2011; 203(12):1850-8. · 6.41 Impact Factor
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ABSTRACT: The vitamin A metabolite retinoic acid (RA) plays a crucial role in mucosal immune responses. We demonstrate in this study that RA-producing retinaldehyde dehydrogenase (RALDH) enzymes are postnatally induced in mesenteric lymph node (MLN) dendritic cells (DCs) and MLN stromal cells. RALDH enzyme activity in lamina propria-derived CD103(+) MLN-DCs did not depend on TLR signaling. Remarkably, RA itself could directly induce RALDH2 in both DCs and stromal cells in vitro. Furthermore, upon provision of a vitamin A-deficient diet, it was found that RA-mediated signaling was strongly reduced within the small intestines, while RALDH2 mRNA and RALDH enzyme activity in lamina propria DCs and MLN-DCs, as well as RALDH2 mRNA expression in MLN stromal cells, were strongly diminished. Moreover, supply of vitamin A to vitamin A-deficient mice restored RA-mediated signaling in the intestine and RALDH activity in lamina propria-derived CD103(+) MLN-DCs. Our results show that RA-dependent signaling within the intestine is indispensable for RALDH activity in the draining MLN.
The Journal of Immunology 02/2011; 186(4):1934-42. · 5.79 Impact Factor
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ABSTRACT: Streptococcus pneumoniae is the most prevalent pathogen causing community-acquired pneumonia. CD44 is a transmembrane adhesion molecule, expressed by a wide variety of cell types, that has several functions in innate and adaptive immune responses. In this study, we tested the hypothesis that CD44 is involved in the host response during pneumococcal pneumonia. On intranasal infection with a lethal dose of S. pneumoniae CD44-knockout (KO) mice showed a prolonged survival when compared with wild-type mice, which was accompanied by a diminished pulmonary bacterial growth and reduced dissemination to distant body sites. Whereas, proinflammatory cytokine responses and lung pathology were not affected, CD44 deficiency resulted in increased early neutrophil influx into the lung. In separate experiments, we confirmed a detrimental role of CD44 in host defense against pneumococci during sublethal pneumonia, as demonstrated by an improved capacity of CD44 KO mice to clear a low infectious dose. In addition, CD44 appeared important for the resolution of lung inflammation during sublethal pneumonia, as shown by histopathology of lung tissue slides. In conclusion, we show here that CD44 facilitates bacterial outgrowth and dissemination during pneumococcal pneumonia, which in lethal infection results in a prolonged survival of CD44 KO mice. Moreover, during sublethal pneumonia CD44 contributes to the resolution of the inflammatory response.
Laboratory Investigation 01/2011; 91(4):588-97. · 3.64 Impact Factor
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ABSTRACT: In addition to its complement-regulating activity, CD55 is a ligand of the adhesion class G protein-coupled receptor CD97; however, the relevance of this interaction has remained elusive. We previously showed that mice lacking a functional CD97 gene have increased numbers of granulocytes.
Here, we demonstrate that CD55-deficient mice display a comparable phenotype with about two-fold more circulating granulocytes in the blood stream, the marginated pool, and the spleen. This granulocytosis was independent of increased complement activity. Augmented numbers of Gr-1-positive cells in cell cycle in the bone marrow indicated a higher granulopoietic activity in mice lacking either CD55 or CD97. Concomitant with the increase in blood granulocyte numbers, Cd55⁻/⁻ mice challenged with the respiratory pathogen Streptococcus pneumoniae developed less bacteremia and died later after infection.
Collectively, these data suggest that complement-independent interaction of CD55 with CD97 is functionally relevant and involved in granulocyte homeostasis and host defense.
PLoS ONE 01/2011; 6(10):e24431. · 4.09 Impact Factor
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David J van Westerloo,
Goda Choi,
Ester C Löwenberg,
Jasper Truijen, Alex F de Vos,
Erik Endert,
Joost C M Meijers,
Lu Zhou,
Manuel P F L Pereira,
Karla C S Queiroz,
Sander H Diks,
Marcel Levi,
Maikel P Peppelenbosch,
Tom van der Poll
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ABSTRACT: Although a relation between diminished human immunity and stress is well recognized both within the general public and the scientific literature, the molecular mechanisms by which stress alters immunity remain poorly understood. We explored a novel model for acute human stress involving volunteers performing a first-time bungee jump from an altitude of 60 m and exploited this model to characterize the effects of acute stress in the peripheral blood compartment. Twenty volunteers were included in the study; half of this group was pretreated for 3 d with the β-receptor blocking agent propranolol. Blood was drawn 2 h before, right before, immediately after and 2 h after the jump. Plasma catecholamine and cortisol levels increased significantly during jumping, which was accompanied by significantly reduced ex vivo inducibility of proinflammatory cytokines as well as activation of coagulation and vascular endothelium. Kinome profiles obtained from the peripheral blood leukocyte fraction contained a strong noncanonical glucocorticoid receptor signal transduction signature after jumping. In apparent agreement, jumping down-regulated Lck/Fyn and cellular innate immune effector function (phagocytosis). Pretreatment of volunteers with propranolol abolished the effects of jumping on coagulation and endothelial activation but left the inhibitory effects on innate immune function intact. Taken together, these results indicate that bungee jumping leads to a catecholamine-independent immune suppressive phenotype and implicate noncanonical glucocorticoid receptor signal transduction as a major pathway linking human stress to impaired functioning of the human innate immune system.
Molecular Medicine 12/2010; 17(3-4):180-8. · 3.76 Impact Factor
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ABSTRACT: Klebsiella pneumoniae is a frequently isolated causative pathogen in respiratory tract infections. CD44 is a transmembrane adhesion molecule that has been implicated in several immunological processes. To determine the role of CD44 during Klebsiella pneumonia, we intranasally infected wild-type and CD44 knockout (KO) mice with 10(2) to 10(4) colony-forming units of K. pneumoniae or administered Klebsiella lipopolysaccharide. During lethal infection, CD44 deficiency was associated with reduced bacterial growth and dissemination accompanied by enhanced pulmonary inflammation. After infection with lower Klebsiella doses, CD44 KO mice but not wild-type mice demonstrated mortality. After infection with even lower bacterial doses, which were cleared by most mice of both strains, CD44 KO mice displayed enhanced lung inflammation 4 and 10 days postinfection, indicating that CD44 is important for the resolution of pulmonary inflammation after nonlethal pneumonia. In accordance, CD44 KO mice showed a diminished resolution of lung inflammation 4 days after intrapulmonary delivery of lipopolysaccharide. CD44 deficiency was associated with the accumulation of hyaluronan together with reduced gene expression levels of the negative regulators of Toll-like receptor signaling, interleukin-1R-associated kinase M, A20, and suppressor of cytokine signaling 3. In conclusion, the absence of CD44 affects various components and phases of the host response during Klebsiella pneumonia, reducing bacterial outgrowth and dissemination and enhancing pulmonary pathology during lethal infection, and diminishing the resolution of lung inflammation during sublethal infection.
American Journal Of Pathology 11/2010; 177(5):2483-94. · 4.89 Impact Factor
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ABSTRACT: After surviving the initial hyperinflammatory phase, patients with sepsis display features consistent with immunosuppression, which renders the host susceptible to nosocomial infections, in particular bacterial pneumonia. Suppression of tumorigenicity 2 (ST2) is a negative regulator of Toll-like receptor signaling implicated in endotoxin tolerance.
The present study sought to determine the role of ST2 in modulating host defense in the lung during sepsis, using a murine model of cecal ligation and puncture (CLP)-induced sepsis followed by a secondary infection with Pseudomonas aeruginosa via the airways.
CLP or sham surgery was performed on BALB/c wild-type (WT) and ST2 knockout (KO) mice, and 24 hours later animals were challenged with 10(8) live P. aeruginosa.
CLP mice demonstrated impaired clearance of Pseudomonas from their lungs and reduced pulmonary levels of tumor necrosis factor-α and IL-6 compared with sham mice. After CLP, ST2KO mice with secondary pneumonia displayed a strongly improved survival and a better bacterial clearance compared with WT mice, which was accompanied by enhanced lung inflammation. CLP did not influence the responsiveness of alveolar macrophages toward P. aeruginosa ex vivo irrespective of the st2 genotype. In contrast, CLP resulted in a reduced capacity of WT CD4(+) and CD8(+) T cells to produce IFN-γ and tumor necrosis factor-α, an immune suppressive effect that was not seen in ST2KO mice.
These findings indicate that gene products of ST2 contribute to the immune-compromised state during sepsis and the ensuing disturbed homeostasis of lung host defense.
American Journal of Respiratory and Critical Care Medicine 10/2010; 183(7):932-40. · 11.08 Impact Factor
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ABSTRACT: : This article is one of ten reviews selected from the Yearbook of Intensive Care and Emergency Medicine 2010 (Springer Verlag) and co-published as a series in Critical Care. Other articles in the series can be found online at http://ccforum.com/series/yearbook. Further information about the Yearbook of Intensive Care and Emergency Medicine is available from http://www.springer.com/series/2855.
Critical care (London, England) 03/2010; 14(2):209. · 4.61 Impact Factor
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ABSTRACT: Infections with multidrug-resistant enterococci are a growing problem worldwide. Little is known about the host defense against enterococcal diseases. In vitro studies have demonstrated an important role played by complement proteins in neutrophil-mediated phagocytosis. In this study, we investigated the importance of complement in an in vivo model of Enterococcus faecium peritonitis.
Peripheral neutrophils and peritoneal macrophages were incubated with E. faecium that had been preincubated with decomplemented or normal plasma, and phagocytosis and killing were examined. E. faecium peritonitis was induced in C57BL/6 mice rendered complement deficient by intraperitoneal injection with cobra venom factor (CVF) and in complement 3 (C3) knockout mice. The course of the infection was compared with that in saline control and wild-type mice, respectively, at several time points up to 48 h after infection.
Opsonization by complement enhanced phagocytosis by neutrophils and macrophages. CVF-treated and C3 knockout mice were severely hampered in clearing E. faecium from all organs and tissues under study (peritoneal fluid, blood, lungs, and liver). Higher peritoneal cytokine and chemokine levels were measured in decomplemented mice, whereas no differences in systemic or peritoneal cell kinetics were detected.
Complement deficiency severely hampers the clearance of E. faecium peritonitis and subsequent systemic infection.
The Journal of Infectious Diseases 02/2010; 201(4):544-52. · 6.41 Impact Factor
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W Joost Wiersinga,
Liesbeth M Kager,
Joppe W R Hovius,
Gerritje J W van der Windt, Alex F de Vos,
Joost C M Meijers,
Joris J Roelofs,
Arjen Dondorp,
Marcel Levi,
Nicholas P Day,
Sharon J Peacock,
Tom van der Poll
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ABSTRACT: Urokinase receptor (urokinase-type plasminogen activator receptor [uPAR], CD87), a GPI-anchored protein, is considered to play an important role in inflammation and fibrinolysis. The Gram-negative bacterium Burkholderia pseudomallei is able to survive and replicate within leukocytes and causes melioidosis, an important cause of pneumonia-derived community-acquired sepsis in Southeast Asia. In this study, we investigated the expression and function of uPAR both in patients with septic melioidosis and in a murine model of experimental melioidosis. uPAR mRNA and surface expression was increased in patients with septic melioidosis in/on both peripheral blood monocytes and granulocytes as well as in the pulmonary compartment during experimental pneumonia-derived melioidosis in mice. uPAR-deficient mice intranasally infected with B. pseudomallei showed an enhanced growth and dissemination of B. pseudomallei when compared with wild-type mice, corresponding with increased pulmonary and hepatic inflammation. uPAR knockout mice demonstrated significantly reduced neutrophil migration toward the pulmonary compartment after inoculation with B. pseudomallei. Further in vitro experiments showed that uPAR-deficient macrophages and granulocytes display a markedly impaired phagocytosis of B. pseudomallei. Additional studies showed that uPAR deficiency did not influence hemostatic and fibrinolytic responses during severe melioidosis. These data suggest that uPAR is crucially involved in the host defense against sepsis caused by B. pseudomallei by facilitating the migration of neutrophils toward the primary site of infection and subsequently facilitating the phagocytosis of B. pseudomallei.
The Journal of Immunology 02/2010; 184(6):3079-86. · 5.79 Impact Factor
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ABSTRACT: Recognition of lipopolysaccharide (LPS) is required for effective defense against invading gram-negative bacteria. Recently, in vitro studies revealed that CD14 is required for activation of the myeloid differentiation factor (MyD)88-dependent Toll-like receptor (TLR)4 signaling pathway by smooth (S)-LPS, but not by rough (R)-LPS. The present study investigated the role of CD14 in induction of lung inflammation in mice by these different LPS chemotypes.
Neutrophil accumulation and tumor necrosis factor (TNF) release in bronchoalveolar lavage fluid were determined 6 hours after intranasal treatment of wild type (WT) and CD14 knock-out (KO) mice with different doses S-LPS or R-LPS. The contribution of CD14 to lung inflammation induced by S-LPS or R-LPS depended on the LPS dose. At low doses, S-LPS and R-LPS induced neutrophil influx in a CD14-dependent manner. Low dose S-LPS-induced cytokine release also depended on CD14. Strikingly, neutrophil influx and TNF release induced by high dose S-LPS or R-LPS was diminished in the presence of CD14. Intranasal administration of sCD14 to CD14 KO mice treated with S-LPS partially reversed the inflammatory response to the response observed in WT mice.
In conclusion, CD14 modulates effects of both S-LPS and R-LPS within the lung in a similar way. Except for R-LPS-induced TNF release, S-LPS and R-LPS at low dose induced acute lung inflammation in a CD14-dependent manner, while the inflammatory response triggered by high dose S-LPS or R-LPS was diminished by CD14.
PLoS ONE 01/2010; 5(4):e10183. · 4.09 Impact Factor
