Hypoxic pulmonary vasoconstriction requires connexin 40-mediated endothelial signal conduction.

Hypoxic pulmonary vasoconstriction (HPV) is a physiological mechanism by which pulmonary arteries constrict in hypoxic lung areas in order to redirect blood flow to areas with greater oxygen supply. Both oxygen sensing and the contractile response are thought to be intrinsic to pulmonary arterial smooth muscle cells. Here we speculated that the ideal site for oxygen sensing might instead be at the alveolocapillary level, with subsequent retrograde propagation to upstream arterioles via connexin 40 (Cx40) endothelial gap junctions.

TLR9- and Src-dependent expression of Krueppel-like factor 4 controls interleukin-10 expression in pneumonia.

The release of potent pro-inflammatory mediators is crucial to mounting an efficient host response during infection. 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.

Intermedin stabilized endothelial barrier function and attenuated ventilator-induced lung injury in mice.

Background: Even protective ventilation may aggravate or induce lung failure, particularly in preinjured lungs. Thus, new adjuvant pharmacologic strategies are needed to minimize ventilator-induced lung injury (VILI). Intermedin/Adrenomedullin-2 (IMD) stabilized pulmonary endothelial barrier function in vitro.

Streptococcus pneumoniae stimulates a STING- and IFN regulatory factor 3-dependent type I IFN production in macrophages, which regulates RANTES production in macrophages, cocultured alveolar epithelial cells, and mouse lungs.

Streptococcus pneumoniae is the leading cause of community-acquired pneumonia. In this study, we examine an innate immune recognition pathway that senses pneumococcal infection, triggers type I IFN production, and regulates RANTES production. We found that human and murine alveolar macrophages as well as murine bone marrow macrophages, but not alveolar epithelial cells, produced type I IFNs upon infection with S.

Sphingosine-1-phospate receptor 4 (S1P₄) deficiency profoundly affects dendritic cell function and TH17-cell differentiation in a murine model.

Although predominantly expressed on lymphocytic and hematopoietic cells, the role of sphingosine-1-phospate receptor 4 (S1P(4)) in immune homeostasis is still poorly understood. In this report, we used a S1P(4)-deficient murine model to characterize the biological role of S1P(4)-mediated S1P signaling in the immune system. S1p(4)(-/-) animals showed normal peripheral lymphocyte numbers and a regular architecture of secondary lymphoid organs.

Dissection of a type I interferon pathway in controlling bacterial intracellular infection in mice.

Defence mechanisms against intracellular bacterial pathogens are incompletely understood. Our study characterizes a type I IFN-dependent cell-autonomous defence pathway directed against Legionella pneumophila, an intracellular model organism and frequent cause of pneumonia. We show that macrophages infected with L.

The NLRP3 inflammasome is differentially activated by pneumolysin variants and contributes to host defense in pneumococcal pneumonia.

Streptococcus pneumoniae is a leading cause of pneumonia, meningitis, and sepsis. Pneumococci can be divided into >90 serotypes that show differences in the pathogenicity and invasiveness. We tested the hypotheses that the innate immune inflammasome pathway is involved in fighting pneumococcal pneumonia and that some invasive pneumococcal types are not recognized by this pathway.

The Sphingosine-1 Phosphate receptor agonist FTY720 dose dependently affected endothelial integrity in vitro and aggravated ventilator-induced lung injury in mice.

Lung barrier protection by Sphingosine-1 Phosphate (S1P) has been demonstrated experimentally, but recent evidence suggests barrier disruptive properties of high systemic S1P concentrations. The S1P analog FTY720 recently gained an FDA approval for treatment of multiple sclerosis. In case of FTY720 treated patients experiencing multiple organ dysfunction syndrome the drug may accumulate due to liver failure, and the patients may receive ventilator therapy.

Adrenomedullin attenuates ventilator-induced lung injury in mice.

Background: Mechanical ventilation (MV) is a life-saving intervention in acute respiratory failure without any alternative. However, even protective ventilation strategies applying minimal mechanical stress may evoke ventilator-induced lung injury (VILI). Adjuvant pharmacological strategies in addition to lung-protective ventilation to attenuate VILI are lacking.

Simvastatin attenuates ventilator-induced lung injury in mice.

Introduction: 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.

TLR2- and nucleotide-binding oligomerization domain 2-dependent Krüppel-like factor 2 expression downregulates NF-kappa B-related gene expression.

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.

Lipocalin2 protects against airway inflammation and hyperresponsiveness in a murine model of allergic airway disease.

Background: Allergen-induced bronchial asthma is a chronic airway disease that involves the interplay of various genes with environmental factors triggering different inflammatory pathways.

Objective: The aim of this study was to identify possible mediators of airway inflammation (AI) in a model of allergic AI via microarray comparisons and to analyse one of these mediators, Lipocalin2 (Lcn2), for its role in a murine model of allergic airway disease.

Methods: Gene microarrays were used to identify genes with at least a twofold increase in gene expression in the lungs of two separate mouse strains with high and low allergic susceptibility, respectively.

RNAi-mediated suppression of constitutive pulmonary gene expression by small interfering RNA in mice.

The ability of synthetic small interfering RNA (siRNA) to silence gene expression makes it a useful tool in biomedical research. However, effective and non-toxic functional siRNA delivery to mouse lungs in vivo is still a key challenge, and regulation of constitutively expressed genes is poorly characterized. Following in vitro validation of siRNA molecules, naked, stabilized siRNA (AtuRNAi) was applied intranasally (i.

Listeria monocytogenes-infected human peripheral blood mononuclear cells produce IL-1beta, depending on listeriolysin O and NLRP3.

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.

Glutathione peroxidase-2 protects from allergen-induced airway inflammation in mice.

The aim of the present study was to identify and validate the biological significance of new genes/proteins involved in the development of allergic airway disease in a murine asthma model. Gene microarrays were used to identify genes with at least a two-fold increase in gene expression in lungs of two separate mouse strains with high and low allergic susceptibility. Validation of mRNA data was obtained by western blotting and immunohistochemistry, followed by functional analysis of one of the identified genes in mice with targeted disruption of specific gene expression.

Role of sphingosine kinase 1 in allergen-induced pulmonary vascular remodeling and hyperresponsiveness.

Background: Immunologic processes might contribute to the pathogenesis of pulmonary arterial hypertension (PAH), a fatal condition characterized by progressive pulmonary arterial remodeling, increased pulmonary vascular resistance, and right ventricular failure. Experimental allergen-driven lung inflammation evoked morphologic and functional vascular changes that resembled those observed in patients with PAH. Sphingosine kinase 1 (SphK1) is the main pulmonary contributor to sphingosine-1-phosphate (S1P) synthesis, a modulator of immune and vascular functions.

cIAP-1 controls innate immunity to C. pneumoniae pulmonary infection.

The resistance of epithelial cells infected with Chlamydophila pneumoniae for apoptosis has been attributed to the induced expression and increased stability of anti-apoptotic proteins called inhibitor of apoptosis proteins (IAPs). The significance of cellular inhibitor of apoptosis protein-1 (cIAP-1) in C. pneumoniae pulmonary infection and innate immune response was investigated in cIAP-1 knockout (KO) mice using a novel non-invasive intra-tracheal infection method.

Small interfering RNA against transcription factor STAT6 inhibits allergic airway inflammation and hyperreactivity in mice.

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.

Phosphodiesterase 2 inhibition diminished acute lung injury in murine pneumococcal pneumonia.

Objective: 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.

Systemic use of the endolysin Cpl-1 rescues mice with fatal pneumococcal pneumonia.

Objectives: 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.

Immunostimulation with macrophage-activating lipopeptide-2 increased survival in murine pneumonia.

Community-acquired pneumonia (CAP) is associated with high morbidity and mortality, and Streptococcus pneumoniae is the most prevalent causal pathogen identified in CAP. Impaired pulmonary host defense increases susceptibility to pneumococcal pneumonia. S.

Histone acetylation and flagellin are essential for Legionella pneumophila-induced cytokine expression.

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.

Rho-kinase and contractile apparatus proteins in murine airway hyperresponsiveness.

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.

Simvastatin reduces Chlamydophila pneumoniae-mediated histone modifications and gene expression in cultured human endothelial cells.

Inflammatory activation of the endothelium by Chlamydophila pneumoniae infection has been implicated in the development of chronic vascular lesions and coronary heart disease by seroepidemiological and animal studies. We tested the hypothesis that C. pneumoniae induced inflammatory gene expression is regulated by Rho-GTPase-related histone modifications.

Cell-specific interleukin-15 and interleukin-15 receptor subunit expression and regulation in pneumococcal pneumonia--comparison to chlamydial lung infection.

Interleukin (IL)-15 has critical impact on the homeostasis and activation of natural killer cells, natural killer T cells, gammadeltaT cells, and CD8(+)T cells, and contributes to antimicrobial defenses particularly at mucosal sites. The respiratory tract comprises a large mucosal surface and harbors significant amounts of lymphocytes, however the expression pattern of IL-15 in the lung and its role in local immune responses are largely unknown. We therefore analyzed the differential expression of IL-15 and the IL-15 receptor (IL-15R) complex in the lungs of mice and demonstrated substantial constitutive expression in bronchial and alveolar epithelial cells, alveolar macrophages, and vascular smooth muscle cells, implicating contribution to pulmonary immune cell homeostasis already under normal conditions.