ABSTRACT
Resident macrophages densely populate the normal arterial wall, yet their origins and the mechanisms that sustain them are poorly understood. Here we use gene-expression profiling to show that arterial macrophages constitute a distinct population among macrophages. Using multiple fate-mapping approaches, we show that arterial macrophages arise embryonically from CX3CR1(+) precursors and postnatally from bone marrow-derived monocytes that colonize the tissue immediately after birth. In adulthood, proliferation (rather than monocyte recruitment) sustains arterial macrophages in the steady state and after severe depletion following sepsis. After infection, arterial macrophages return rapidly to functional homeostasis. Finally, survival of resident arterial macrophages depends on a CX3CR1-CX3CL1 axis within the vascular niche.
Subject(s)
Cell Self Renewal , Embryonic Stem Cells/cytology , Embryonic Stem Cells/metabolism , Macrophages/cytology , Macrophages/metabolism , Monocytes/cytology , Monocytes/metabolism , Receptors, Chemokine/metabolism , Animals , CX3C Chemokine Receptor 1 , Cell Survival , Chemokine CX3CL1/metabolism , Cluster Analysis , Female , Gene Expression Profiling , Immunophenotyping , Macrophages/immunology , Macrophages/microbiology , Male , Mice , Mice, Transgenic , Phenotype , Protein Binding , Stem Cell Niche , TranscriptomeABSTRACT
Streptococcus pneumoniae is a leading cause of invasive bacterial infections, with nasal colonization an important first step in disease. While cigarette smoking is a strong risk factor for invasive pneumococcal disease, the underlying mechanisms remain unknown. This is partly due to a lack of clinically relevant animal models investigating nasal pneumococcal colonization in the context of cigarette smoke exposure. We present a model of nasal pneumococcal colonization in cigarette smoke-exposed mice and document, for the first time, that cigarette smoke predisposes to invasive pneumococcal infection and mortality in an animal model. Cigarette smoke increased the risk of bacteremia and meningitis without prior lung infection. Mechanistically, deficiency in interleukin 1α (IL-1α) or platelet-activating factor receptor (PAFR), an important host receptor thought to bind and facilitate pneumococcal invasiveness, did not rescue cigarette smoke-exposed mice from invasive pneumococcal disease. Importantly, we observed cigarette smoke to attenuate nasal inflammatory mediator expression, particularly that of neutrophil-recruiting chemokines, normally elicited by pneumococcal colonization. Smoking cessation during nasal pneumococcal colonization rescued nasal neutrophil recruitment and prevented invasive disease in mice. We propose that cigarette smoke predisposes to invasive pneumococcal disease by suppressing inflammatory processes of the upper respiratory tract. Given that smoking prevalence remains high worldwide, these findings are relevant to the continued efforts to reduce the invasive pneumococcal disease burden.
Subject(s)
Carrier State/immunology , Nasal Mucosa/microbiology , Pneumococcal Infections/immunology , Smoke/adverse effects , Smoking/adverse effects , Streptococcus pneumoniae/growth & development , Animals , Bacteremia/microbiology , Bacteremia/prevention & control , Carrier State/prevention & control , Disease Models, Animal , Disease Resistance , Meningitis, Pneumococcal/microbiology , Meningitis, Pneumococcal/prevention & control , Mice , Mice, Inbred C57BL , Mice, Knockout , Nasal Mucosa/immunology , Neutrophils/immunology , Pneumococcal Infections/prevention & control , Streptococcus pneumoniae/immunologyABSTRACT
RATIONALE: Nontypeable Haemophilus influenzae (NTHi) causes acute exacerbation of chronic obstructive pulmonary disease (AECOPD). IL-17A is central for neutrophilic inflammation and has been linked to COPD pathogenesis. OBJECTIVES: We investigated whether IL-17A is elevated in NTHi-associated AECOPD and required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke. METHODS: Experimental studies with cigarette smoke and NTHi infection were pursued in gene-targeted mice and using antibody intervention. IL-17A was measured in sputum collected from patients with COPD at baseline, during, and after AECOPD. MEASUREMENTS AND MAIN RESULTS: Exacerbated airway neutrophilia in cigarette smoke-exposed mice infected with NTHi was associated with an induction of IL-17A. In agreement, elevated IL-17A was observed in sputum collected during NTHi-associated AECOPD, compared with samples collected before or after the event. NTHi-exacerbated neutrophilia and induction of neutrophil chemoattractants over the background of cigarette smoke, as observed in wild-type mice, was absent in Il17a(-/-) mice and in mice treated with a neutralizing anti-IL-17A antibody. Further studies revealed that IL-1 receptor (R)1 signaling was required for IL-17A-dependent neutrophilia. Moreover, deficiency or therapeutic neutralization of IL-17A did not increase bacterial burden or delay bacterial clearance. CONCLUSIONS: IL-17A is induced during NTHi-associated AECOPD. Functionally, IL-1R1-dependent IL-17A is required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke. Targeting IL-17A in AECOPD may thus be beneficial to reduce neutrophil recruitment to the airways.
Subject(s)
Haemophilus Infections/metabolism , Haemophilus influenzae , Interleukin-17/metabolism , Neutrophils/physiology , Pulmonary Disease, Chronic Obstructive/complications , Pulmonary Disease, Chronic Obstructive/metabolism , Aged , Animals , Disease Models, Animal , Female , Haemophilus Infections/complications , Humans , Leukocyte Count , Male , Mice , Mice, Inbred BALB C , Middle Aged , Neutrophil Infiltration , Smoking/adverse effectsABSTRACT
Extracellular RNA is becoming increasingly recognized as a signaling molecule. Virally derived double stranded (ds)RNA released into the extracellular space during virus induced cell lysis acts as a powerful inducer of classical type I interferon (IFN) responses; however, the receptor that mediates this response has not been identified. Class A scavenger receptors (SR-As) are likely candidates due to their cell surface expression and ability to bind nucleic acids. In this study, we investigated a possible role for SR-As in mediating type I IFN responses induced by extracellular dsRNA in fibroblasts, a predominant producer of IFNbeta. Fibroblasts were found to express functional SR-As, even SR-A species thought to be macrophage specific. SR-A specific competitive ligands significantly blocked extracellular dsRNA binding, entry and subsequent interferon stimulated gene (ISG) induction. Candidate SR-As were systematically investigated using RNAi and the most dramatic inhibition in responses was observed when all candidate SR-As were knocked down in unison. Partial inhibition of dsRNA induced antiviral responses was observed in vivo in SR-AI/II(-/-) mice compared with WT controls. The role of SR-As in mediating extracellular dsRNA entry and subsequent induced antiviral responses was observed in both murine and human fibroblasts. SR-As appear to function as 'carriers', facilitating dsRNA entry and delivery to the established dsRNA sensing receptors, specifically TLR3, RIGI and MDA-5. Identifying SR-As as gatekeepers of the cell, mediating innate antiviral responses, represents a novel function for this receptor family and provides insight into how cells recognize danger signals associated with lytic virus infections. Furthermore, the implications of a cell surface receptor capable of recognizing extracellular RNA may exceed beyond viral immunity to mediating other important innate immune functions.
Subject(s)
Interferon Type I/metabolism , RNA, Double-Stranded/metabolism , RNA, Viral/metabolism , Scavenger Receptors, Class A/genetics , Scavenger Receptors, Class A/metabolism , Virus Diseases/immunology , Animals , Cell Line , Extracellular Space/genetics , Fibroblasts/cytology , Gene Knockdown Techniques , Humans , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Monocytes/cytology , Scavenger Receptors, Class A/immunology , Toll-Like Receptor 3/immunologyABSTRACT
BACKGROUND: Evidence suggests that dendritic cells accumulate in the lungs of COPD patients and correlate with disease severity. We investigated the importance of IL-1R1 and its ligands IL-1α and ß to dendritic cell accumulation and maturation in response to cigarette smoke exposure. METHODS: Mice were exposed to cigarette smoke using a whole body smoke exposure system. IL-1R1-, TLR4-, and IL-1α-deficient mice, as well as anti-IL-1α and anti-IL-1ß blocking antibodies were used to study the importance of IL-1R1 and TLR4 to dendritic cell accumulation and activation. RESULTS: Acute and chronic cigarette smoke exposure led to increased frequency of lung dendritic cells. Accumulation and activation of dendritic cells was IL-1R1/IL-1α dependent, but TLR4- and IL-1ß-independent. Corroborating the cellular data, expression of CCL20, a potent dendritic cells chemoattractant, was IL-1R1/IL-1α-dependent. Studies using IL-1R1 bone marrow-chimeric mice revealed the importance of IL-1R1 signaling on lung structural cells for CCL20 expression. Consistent with the importance of dendritic cells in T cell activation, we observed decreased CD4+ and CD8+ T cell activation in cigarette smoke-exposed IL-1R1-deficient mice. CONCLUSION: Our findings convey the importance of IL-1R1/IL-1α to the recruitment and activation of dendritic cells in response to cigarette smoke exposure.
Subject(s)
Chemotaxis/drug effects , Dendritic Cells/drug effects , Interleukin-1alpha/metabolism , Lung/drug effects , Smoke/adverse effects , Smoking/adverse effects , Animals , Antibodies, Blocking , Bone Marrow Transplantation , CD4-Positive T-Lymphocytes/drug effects , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/drug effects , CD8-Positive T-Lymphocytes/immunology , Chemokine CCL20/metabolism , Dendritic Cells/immunology , Interleukin-1alpha/deficiency , Interleukin-1alpha/genetics , Interleukin-1beta/metabolism , Lung/immunology , Lymphocyte Activation/drug effects , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Receptors, Interleukin-1 Type I/deficiency , Receptors, Interleukin-1 Type I/genetics , Signal Transduction , Time Factors , Toll-Like Receptor 4/deficiency , Toll-Like Receptor 4/genetics , Transplantation ChimeraABSTRACT
Influenza virus infection is a leading cause of death and disability throughout the world. Influenza-infected hosts are vulnerable to secondary bacterial infection, however, and an ensuing bacterial pneumonia is actually the predominant cause of influenza-attributed deaths during pandemics. A number of mechanisms have been proposed by which influenza may predispose to superinfection with an unrelated or heterologous pathogen, but the subsequent interaction between the host, virus, and bacteria remains an understudied area. In this study, we develop and examine a novel model of heterologous pulmonary infection in which an otherwise subclinical Bordetella parapertussis infection synergizes with an influenza virus infection to yield a life-threatening secondary pneumonia. Despite a profound pulmonary inflammatory response and unaltered viral clearance, bacterial clearance was significantly impaired in heterologously infected mice. No deficits were observed in pulmonary or systemic adaptive immune responses or the viability or function of infiltrating inflammatory cells to explain this phenomenon, and we provide evidence that the onset of severe pulmonary inflammation actually precedes the increased bacterial burden, suggesting that exacerbated inflammation is independent of bacterial burden. To that end, neutralization of the ELR(+) inflammatory chemokine MIP-2 (CXCL2/GRO-beta) attenuated the inflammation, weight loss, and clinical presentation of heterologously infected mice without impacting bacterial burden. These data suggest that pulmonary inflammation, rather than pathogen burden, is the key threat during bacterial superinfection of influenza and that selective chemokine antagonists may be a novel therapeutic intervention in cases of bacterial superinfection of influenza.
Subject(s)
Bordetella Infections/immunology , Bordetella parapertussis/immunology , Chemokine CXCL2/biosynthesis , Influenza A Virus, H1N1 Subtype/immunology , Orthomyxoviridae Infections/immunology , Superinfection/immunology , Animals , Bordetella Infections/pathology , Bordetella Infections/therapy , Cell Line , Chemokine CXCL2/antagonists & inhibitors , Chemokine CXCL2/physiology , Dogs , Female , Gene Expression Regulation, Bacterial/immunology , Gene Expression Regulation, Viral/immunology , Inflammation Mediators/antagonists & inhibitors , Inflammation Mediators/metabolism , Inflammation Mediators/physiology , Mice , Mice, Inbred C57BL , Orthomyxoviridae Infections/pathology , Orthomyxoviridae Infections/therapy , Pneumonia, Bacterial/immunology , Pneumonia, Bacterial/pathology , Pneumonia, Bacterial/virology , Pneumonia, Viral/immunology , Pneumonia, Viral/microbiology , Pneumonia, Viral/pathology , Receptors, Interleukin-8B/antagonists & inhibitors , Superinfection/microbiology , Superinfection/virologyABSTRACT
RATIONALE: Cigarette smoke is the major cause of chronic obstructive pulmonary disease and lung cancer. The mechanisms by which smoking induces pulmonary dysfunction are complex, involving stress from toxic components and inflammatory responses. Although CCCAAT/enhancer-binding protein (C/EBP)-ß is known as a key intracellular regulator of inflammatory signaling, its role in pulmonary inflammation has not been established. OBJECTIVES: To characterize the role of C/EBPß in the airway epithelial response to cigarette smoke. METHODS: mRNA expression in the airway epithelium of current, former, and never-smokers, and in in vitro cigarette smoke extract-treated primary human airway epithelial cells, was analyzed by microarray and quantitative real-time polymerase chain reaction, respectively. Mice with lung epithelial-specific inactivation of C/EBPß were generated and exposed to cigarette smoke for 4 or 11 days. Lung histology, bronchoalveolar lavage cell differentials, and expression of inflammatory and innate immune mediators in the lungs were assessed. MEASUREMENTS AND MAIN RESULTS: C/EBPß was significantly down-regulated in the airway epithelium of both current and former smokers compared with never-smokers, and in cigarette smoke-treated primary human airway epithelial cells in vitro. Cigarette smoke-exposed mice with a lung epithelial-specific inactivation of C/EBPß displayed blunted respiratory neutrophil influx and compromised induction of neutrophil chemoattractants growth-regulated oncogene-α, macrophage inflammatory protein-1γ, granulocyte colony-stimulating factor, and serum amyloid A 3 and proinflammatory cytokines tumor necrosis factor-α and interleukin-1ß, compared with smoke-exposed controls. Inhibition of C/EBPß in human airway cells in vitro caused a similarly compromised response to smoke. CONCLUSION: Our data suggest a previously unknown role for C/EBPß and the airway epithelium in mediating inflammatory and innate immune responses to cigarette smoke.
Subject(s)
CCAAT-Enhancer-Binding Protein-beta/immunology , Epithelial Cells/immunology , Inflammation/immunology , Lung/immunology , Smoking/immunology , Animals , Blotting, Western , Bronchoalveolar Lavage Fluid/immunology , Cell Culture Techniques , Disease Models, Animal , Enzyme-Linked Immunosorbent Assay , Epithelial Cells/drug effects , Humans , Immunity, Innate/immunology , Lung/drug effects , Mice , Mice, Inbred C57BL , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Although a similar prevalence of smoking is evident among patients with asthma and the general population, little is known about the impact of cigarette smoke on the immune inflammatory processes elicited by common environmental allergens. We investigated the impact of exposure to cigarette smoke on house dust mite (HDM)-induced allergic airway inflammation and its consequences for tissue remodeling and lung physiology in mice. BALB/c mice received intranasal HDMs daily, 5 days per week, for 3 weeks to establish chronic airway inflammation. Subsequently, mice were concurrently exposed to HDMs plus cigarette smoke, 5 days per week, for 2 weeks (HDMs + smoke). We observed significantly attenuated eosinophilia in the bronchoalveolar lavage of mice exposed to HDMs + smoke, compared with animals exposed only to HDMs. A similar activation of CD4 T cells and expression of IL-5, IL-13, and transforming growth factor-ß was observed between HDM-treated and HDM + smoke-treated animals. Consistent with an effect on eosinophil trafficking, HDMs + smoke exposure attenuated the HDM-induced expression of eotaxin-1 and vascular cell adhesion molecule-1, whereas the survival of eosinophils and the numbers of blood eosinophils were not affected. Exposure to cigarette smoke also reduced the activation of B cells and the concentrations of serum IgE. Although the production of mucus decreased, collagen deposition significantly increased in animals exposed to HDMs + smoke, compared with animals exposed only to HDMs. Although airway resistance was unaffected, tissue resistance was significantly decreased in mice exposed to HDMs + smoke. Our findings demonstrate that cigarette smoke affects eosinophil migration without affecting airway resistance or modifying Th2 cell adaptive immunity in a murine model of HDM-induced asthma.
Subject(s)
Airway Remodeling , Allergens , Asthma/immunology , Lung/immunology , Pulmonary Eosinophilia/prevention & control , Pyroglyphidae/immunology , Smoking/immunology , Airway Resistance , Animals , Asthma/pathology , Asthma/physiopathology , B-Lymphocytes/immunology , Bronchial Hyperreactivity/immunology , Chemokine CCL11/metabolism , Dendritic Cells/immunology , Disease Models, Animal , Female , Interleukin-13/metabolism , Interleukin-5/metabolism , Lung/pathology , Lung/physiopathology , Mice , Mice, Inbred BALB C , Pulmonary Eosinophilia/immunology , Pulmonary Eosinophilia/pathology , Pulmonary Eosinophilia/physiopathology , Smoking/pathology , Smoking/physiopathology , T-Lymphocytes/immunology , Time Factors , Transforming Growth Factor beta/metabolism , Vascular Cell Adhesion Molecule-1/metabolismABSTRACT
The objective of this study was to characterize the impact of cigarette smoke exposure on lung immune and inflammatory processes. BALB/c and C57BL/6 mice were exposed to cigarette smoke for 4 days (acute) or at least 5 weeks (prolonged). Both mouse strains manifested an inflammatory response after acute smoke exposure, characterized by an influx of neutrophils and mononuclear cells. Multiplex analysis revealed a greater than twofold increase of the cytokines IL-1alpha, -5, -6, and -18, as well as the chemokines monocyte chemotactic protein-1 and -3, macrophage inflammatory protein-1alpha, -beta, and -gamma, -2, -3beta, macrophage defined chemokine, granulocyte chemotactic protein-2, and interferon-gamma-inducible protein-10. In BALB/c mice, neutrophilia persisted after prolonged exposure, whereas C57BL/6 showed evidence of attenuated neutrophilia both in the bronchoalveolar lavage and the lungs. In both mouse strains, cigarette smoke exposure was associated with an expansion of mature (CD11c(hi)/major histocompatibility complex class II(hi)) myeloid dendritic cells; we observed no changes in plasmacytoid dendritic cells. Lymphocytes in the lungs displayed an activated phenotype that persisted for CD4 T cells only after prolonged exposure. In BALB/c mice, T cells acquired T helper (Th) 1 and Th2 effector function after 5 weeks of smoke exposure, whereas, in C57BL/6 mice, neither Th1 nor Th2 cells were detected. In both mouse strains, cigarette smoke exposure led to an accumulation of FoxP3+ T regulatory cells in the lungs. Studies in RAG1 knockout mice suggest that these regulatory cells may participate in controlling smoke-induced inflammation. Acute and prolonged cigarette smoke exposure was associated with inflammation, activation of the adaptive immune system, and expansion of T regulatory cells in the lungs.
Subject(s)
Immunity, Innate/immunology , Pneumonia/immunology , Smoking/adverse effects , Adaptive Immunity/genetics , Adaptive Immunity/immunology , Animals , Bronchoalveolar Lavage , CD11c Antigen/genetics , CD11c Antigen/immunology , Cytokines/genetics , Cytokines/immunology , Dendritic Cells/immunology , Dendritic Cells/physiology , Female , Homeodomain Proteins/genetics , Homeodomain Proteins/immunology , Humans , Immunity, Innate/genetics , Lung/immunology , Lung/pathology , Mice , Mice, Inbred BALB C , Mice, Knockout , Myeloid Cells/immunology , Myeloid Cells/pathology , Neutrophil Infiltration/genetics , Neutrophil Infiltration/immunology , Neutrophils/immunology , Neutrophils/pathology , Pneumonia/etiology , Pneumonia/genetics , Pneumonia/pathology , Smoking/immunology , T-Lymphocytes, Regulatory/immunology , T-Lymphocytes, Regulatory/pathology , Th1 Cells/immunology , Th1 Cells/pathology , Th2 Cells/immunology , Th2 Cells/pathology , Time FactorsABSTRACT
The impact of cigarette smoke on allergic asthma remains controversial both clinically and experimentally. The objective of this study was to investigate, in a murine model, how cigarette smoke affects immune inflammatory processes elicited by a surrogate allergen. In our experimental design, mice were concurrently exposed to cigarette smoke and ovalbumin (OVA), an innocuous antigen that, unless introduced in the context of an adjuvant, induces inhalation tolerance. We show that cigarette smoke exposure has adjuvant properties, allowing for allergic mucosal sensitization to OVA. Specifically, concurrent exposure to cigarette smoke and OVA for 2 weeks led to airway eosinophilia and goblet cell hyperplasia. In vivo OVA recall challenge 1 month after the last smoke exposure showed that concurrent exposure to OVA and cigarette smoke induced antigen-specific memory. Robust eosinophilia and OVA-specific IgG1 and IgE characterized the ensuing inflammatory response. Mechanistically, allergic sensitization was, in part, granulocyte macrophage colony-stimulating factor (GM-CSF) dependent, as a significant reduction in BAL eosinophilia was observed in mice treated with an anti-GM-CSF antibody. Of note, continuous smoke exposure attenuated the OVA recall response; decreased airway eosinophilia was observed in mice continuously exposed to cigarette smoke compared with mice that ceased the smoke exposure protocol. In conclusion, we demonstrate experimentally that while cigarette smoke acts as an adjuvant allowing for allergic sensitization, it also attenuates the ensuing eosinophilic inflammatory response.
Subject(s)
Adjuvants, Immunologic , Allergens/immunology , Asthma/immunology , Bronchial Hyperreactivity/immunology , Inflammation/immunology , Nicotiana , Smoke , Animals , Antigens, CD/immunology , Bronchoalveolar Lavage Fluid/cytology , Bronchoalveolar Lavage Fluid/immunology , Dendritic Cells/immunology , Disease Models, Animal , Female , Humans , Immune Tolerance/physiology , Immunologic Memory , Mice , Mice, Inbred BALB C , Ovalbumin/immunology , T-Lymphocytes/immunologySubject(s)
Asthma/etiology , Disease Models, Animal , Pyroglyphidae/immunology , Animals , Humans , Male , Mice , Mice, Inbred BALB CABSTRACT
Mechanisms that govern transcriptional regulation of inflammation in atherosclerosis remain largely unknown. Here, we identify the nuclear transcription factor c-Myb as an important mediator of atherosclerotic disease in mice. Atherosclerosis-prone animals fed a diet high in cholesterol exhibit increased levels of c-Myb in the bone marrow. Use of mice that either harbor a c-Myb hypomorphic allele or where c-Myb has been preferentially deleted in B cell lineages revealed that c-Myb potentiates atherosclerosis directly through its effects on B lymphocytes. Reduced c-Myb activity prevents the expansion of atherogenic B2 cells yet associates with increased numbers of IgM-producing antibody-secreting cells (IgM-ASCs) and elevated levels of atheroprotective oxidized low-density lipoprotein (OxLDL)-specific IgM antibodies. Transcriptional profiling revealed that c-Myb has a limited effect on B cell function but is integral in maintaining B cell progenitor populations in the bone marrow. Thus, targeted disruption of c-Myb beneficially modulates the complex biology of B cells in cardiovascular disease.
Subject(s)
Antibody-Producing Cells/immunology , Atherosclerosis/genetics , Atherosclerosis/immunology , Immunoglobulin M/metabolism , Proto-Oncogene Proteins c-myb/genetics , Proto-Oncogene Proteins c-myb/immunology , Animals , Antibody-Producing Cells/metabolism , Atherosclerosis/pathology , Bone Marrow Cells/immunology , Bone Marrow Cells/pathology , Genes, myb , Male , MiceABSTRACT
Alveolar macrophages (aMs) play a central role in respiratory host defense by sensing microbial antigens and initiating immune-inflammatory responses early in the course of an infection. The purpose of this study was to investigate the effect of cigarette smoke exposure on aMs after stimulation of innate pattern recognition receptors (PRRs) in a murine model. To accomplish this, C57BL/6 mice were exposed for 8 weeks using two models of cigarette smoke exposure, nose-only or whole-body exposure, and aMs isolated from the bronchoalveolar lavage. After stimulation of aMs with pI:C, a mimic of viral replication, and bacterial cell-wall constituent LPS, aMs from cigarette smoke-exposed mice produced significantly attenuated levels of the inflammatory cytokines TNF-alpha and IL-6, and the chemokine RANTES. This attenuation was specific to the aM compartment, and not related to changes in aM viability or expression of Toll-like receptor (TLR)3 or TLR4 between groups. Furthermore, aMs from smoke-exposed mice had decreased cytokine RNA as compared with aMs from sham-exposed mice. Mechanistically, this was associated with decreased nuclear translocation of the proinflammatory transcription factor NF-kappaB, and increased activator protein-1 nuclear translocation, in aMs from smoke-exposed mice. Attenuated cytokine production was reversible after smoking cessation. Cigarette smoke exposure also attenuated TNF-alpha production after stimulation with nucleotide-oligomerization domain-like receptor agonists, showing that the effect applies more broadly to other PRR pathways. Our data demonstrate that cigarette smoke exposure attenuates aM responses after innate stimulation, including pathways typically associated with bacterial and viral infections.
Subject(s)
Cytokines/biosynthesis , Macrophages, Alveolar/metabolism , Nicotiana , Smoke/adverse effects , Animals , Carboxyhemoglobin/metabolism , Cytokines/metabolism , Enzyme-Linked Immunosorbent Assay , Female , Fluorescent Antibody Technique , Macrophages, Peritoneal/metabolism , Mice , Mice, Inbred C57BL , Nitric Oxide/metabolism , Pulmonary Disease, Chronic Obstructive/etiology , Reverse Transcriptase Polymerase Chain Reaction , Toll-Like Receptors/metabolismABSTRACT
The objective of this study was to investigate the impact of cigarette smoke on innate antiviral defense mechanisms; specifically, we examined the effects of cigarette smoke on the induction of type I interferon (IFN). We observed a dose-dependent decrease in the ability of human lung fibroblast and epithelial cells to elicit an antiviral response against a viral double-strand RNA (dsRNA) mimic, polyI:C, in the presence of cigarette smoke-conditioned medium (SCM). Mechanistically, SCM decreases the expression of IFN-stimulated gene 15 (ISG15) and IFN regulatory factor-7 (IRF-7) transcripts and suppresses the nuclear translocation of key transcription factors, nuclear factor-kappaB (NF-kappaB) and IRF-3, after polyI:C stimulation. Furthermore, we provide evidence that the intercellular defense strategy against viral infection is also impaired. We observed a decrease in the ability of fibroblasts to elicit an antiviral state in response to IFN-beta stimulation. This was associated with decreased nuclear translocation of phosphorylated Stat1 in response to IFN-beta treatment. The effects elicited by SCM are reversible and are almost entirely abrogated in the presence of an antioxidant, such as glutathione. Our findings suggest that cigarette smoke affects the immediate-early, inductive, and amplification phases of the type I IFN response.
Subject(s)
Epithelial Cells/immunology , Fibroblasts/immunology , Interferon Type I/immunology , Smoke/adverse effects , Antiviral Agents/immunology , Antiviral Agents/metabolism , Cell Line , Cell Nucleus/metabolism , Culture Media, Conditioned , Cytokines/metabolism , Epithelial Cells/metabolism , Fibroblasts/metabolism , Glutathione/pharmacology , Humans , Immunity, Innate , Interferon Inducers/pharmacology , Interferon Regulatory Factor-3/immunology , Interferon Regulatory Factor-3/metabolism , Interferon Regulatory Factor-7/metabolism , Interferon Type I/metabolism , Lung/immunology , Lung/metabolism , Poly I-C/pharmacology , Protein Serine-Threonine Kinases/metabolism , STAT1 Transcription Factor/metabolism , Nicotiana , Ubiquitins/metabolism , NF-kappaB-Inducing KinaseABSTRACT
Modeling acute exacerbations of chronic obstructive pulmonary disease (AECOPD) in animals has proven challenging due to the clinical and pathological complexity of the underlying disease. This has hindered the progress in understanding the cellular and molecular mechanisms that lie beneath AECOPD. In this chapter, we will address modeling possibilities of AECOPD that may be drawn from the current knowledge of factors that cause exacerbations. Importantly, since it is widely accepted that the most common causes of AECOPD are viral and bacterial infections, animal models of AECOPD should incorporate both the causative agents of exacerbation: viruses and bacteria. However, other factors that are also believed to determine both progression of COPD, as well as the frequency and severity of AECOPD, such as proteolytic enzymes, cigarette smoke or other noxious stimuli must also be considered. Such animal models will provide mechanistic insight into the etiology of AECOPD and will prove invaluable in furthering our understanding of key events in disease pathogenesis.
Subject(s)
Disease Models, Animal , Pulmonary Disease, Chronic Obstructive/etiology , Animals , Humans , Pulmonary Disease, Chronic Obstructive/immunology , Pulmonary Disease, Chronic Obstructive/microbiology , Pulmonary Disease, Chronic Obstructive/virologyABSTRACT
BACKGROUND: In allergen-induced asthma, activated mast cells start the lung inflammatory process with degranulation, cytokine synthesis, and mediator release. Bruton's tyrosine kinase (Btk) activity is required for the mast cell activation during IgE-mediated secretion. METHODS: This study characterized a novel inhaled Btk inhibitor RN983 in vitro and in ovalbumin allergic mouse models of the early (EAR) and late (LAR) asthmatic response. RESULTS: RN983 potently, selectively, and reversibly inhibited the Btk enzyme. RN983 displayed functional activities in human cell-based assays in multiple cell types, inhibiting IgG production in B-cells with an IC50 of 2.5 ± 0.7 nM and PGD2 production from mast cells with an IC50 of 8.3 ± 1.1 nM. RN983 displayed similar functional activities in the allergic mouse model of asthma when delivered as a dry powder aerosol by nose-only inhalation. RN983 was less potent at inhibiting bronchoconstriction (IC50(RN983) = 59 µg/kg) than the ß-agonist salbutamol (IC50(salbutamol) = 15 µg/kg) in the mouse model of the EAR. RN983 was more potent at inhibiting the antigen induced increase in pulmonary inflammation (IC50(RN983) = <3 µg/kg) than the inhaled corticosteroid budesonide (IC50(budesonide) = 27 µg/kg) in the mouse model of the LAR. CONCLUSIONS: Inhalation of aerosolized RN983 may be effective as a stand-alone asthma therapy or used in combination with inhaled steroids and ß-agonists in severe asthmatics due to its potent inhibition of mast cell activation.
Subject(s)
Anti-Asthmatic Agents/administration & dosage , Anti-Inflammatory Agents/administration & dosage , Asthma/drug therapy , Bronchial Hyperreactivity/prevention & control , Bronchoconstriction/drug effects , Bronchodilator Agents/administration & dosage , Dry Powder Inhalers , Lung/drug effects , Ovalbumin , Phthalazines/administration & dosage , Pneumonia/prevention & control , Protein Kinase Inhibitors/administration & dosage , Protein-Tyrosine Kinases/antagonists & inhibitors , Pyridazines/administration & dosage , Administration, Inhalation , Adrenergic beta-2 Receptor Agonists/administration & dosage , Agammaglobulinaemia Tyrosine Kinase , Albuterol/administration & dosage , Animals , Anti-Asthmatic Agents/pharmacokinetics , Anti-Inflammatory Agents/pharmacokinetics , Asthma/enzymology , Asthma/immunology , Asthma/physiopathology , B-Lymphocytes/drug effects , B-Lymphocytes/enzymology , B-Lymphocytes/immunology , Bronchial Hyperreactivity/enzymology , Bronchial Hyperreactivity/immunology , Bronchial Hyperreactivity/physiopathology , Bronchodilator Agents/pharmacokinetics , Budesonide/administration & dosage , Cell Degranulation/drug effects , Cells, Cultured , Cytokines/immunology , Cytokines/metabolism , Disease Models, Animal , Dose-Response Relationship, Drug , Glucocorticoids/administration & dosage , Humans , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Lung/enzymology , Lung/immunology , Lung/physiopathology , Male , Mast Cells/drug effects , Mast Cells/enzymology , Mast Cells/immunology , Mice, Inbred BALB C , Phthalazines/pharmacokinetics , Pneumonia/enzymology , Pneumonia/immunology , Pneumonia/physiopathology , Prostaglandin D2/immunology , Prostaglandin D2/metabolism , Protein Kinase Inhibitors/pharmacokinetics , Protein-Tyrosine Kinases/metabolism , Pyridazines/pharmacokineticsABSTRACT
COPD is a complex syndrome that poses a serious health threat to >1.1 billion smokers worldwide. The stable disease is punctuated by episodes of acute exacerbation, which are predominantly the result of viral and bacterial infections. Despite their devastating health impact, mechanisms underlying disease exacerbations remain poorly understood. Mounting evidence suggests that cigarette smoke profoundly affects the immune system, compromising the host's ability to mount appropriate immune and inflammatory responses against microbial agents. This review highlights recent advances in our understanding of the impact of cigarette smoke on type 1 interferon and IL-1 signaling cascades. The immune defects caused by cigarette smoke on these two key pathways contribute to the seemingly contradictory nature of cigarette smoke as both a damaging and a proinflammatory factor as well as an immunosuppressive factor. Understanding the impact of cigarette smoke on the immune system may unravel novel targets for therapies that could affect acute exacerbations and COPD pathogenesis.
Subject(s)
Disease Progression , Pneumonia, Viral/immunology , Pulmonary Disease, Chronic Obstructive/immunology , Smoking/immunology , Humans , Interferon Type I/immunology , Interleukin-1/immunology , Pneumonia, Viral/complications , Pulmonary Disease, Chronic Obstructive/complications , Pulmonary Disease, Chronic Obstructive/virology , Signal Transduction , Tobacco ProductsABSTRACT
Airway inflammation is considered a central component of asthma and, therefore, international guidelines recommend antiinflammatory medications. We describe the clinical history of a 34-year-old woman with airway hyperresponsiveness and asthma who had a reduced ability to mount an inflammatory response due to two unrelated and rare genetic conditions: Fanconi anemia and incontinentia pigmenti. Absence of eosinophils in blood and sputum led to a successful reduction in the dose of corticosteroids without loss of asthma control demonstrating the clinical utility of monitoring treatment using biomarkers and the importance of recognizing the components of airway diseases that contribute to symptoms.
Subject(s)
Asthma/epidemiology , Fanconi Anemia/epidemiology , Incontinentia Pigmenti/epidemiology , Adult , Comorbidity , Eosinophils/metabolism , Female , Humans , Incontinentia Pigmenti/genetics , Sputum/cytology , Sputum/metabolismABSTRACT
The preclinical model of bleomycin-induced lung fibrosis, used to investigate mechanisms related to idiopathic pulmonary fibrosis (IPF), has incorrectly predicted efficacy for several candidate compounds suggesting that it may be of limited value. As an attempt to improve the predictive nature of this model, integrative bioinformatic approaches were used to compare molecular alterations in the lungs of bleomycin-treated mice and patients with IPF. Using gene set enrichment analysis we show for the first time that genes differentially expressed during the fibrotic phase of the single challenge bleomycin model were significantly enriched in the expression profiles of IPF patients. The genes that contributed most to the enrichment were largely involved in mitosis, growth factor, and matrix signaling. Interestingly, these same mitotic processes were increased in the expression profiles of fibroblasts isolated from rapidly progressing, but not slowly progressing, IPF patients relative to control subjects. The data also indicated that TGFß was not the sole mediator responsible for the changes observed in this model since the ALK-5 inhibitor SB525334 effectively attenuated some but not all of the fibrosis associated with this model. Although some would suggest that repetitive bleomycin injuries may more effectively model IPF-like changes, our data do not support this conclusion. Together, these data highlight that a single bleomycin instillation effectively replicates several of the specific pathogenic molecular changes associated with IPF, and may be best used as a model for patients with active disease.
Subject(s)
Antibiotics, Antineoplastic/adverse effects , Bleomycin/adverse effects , Idiopathic Pulmonary Fibrosis/chemically induced , Idiopathic Pulmonary Fibrosis/genetics , Airway Remodeling/drug effects , Animals , Antibiotics, Antineoplastic/administration & dosage , Bleomycin/administration & dosage , Cluster Analysis , Disease Models, Animal , Fibroblasts/drug effects , Fibroblasts/metabolism , Gene Expression Profiling , Gene Expression Regulation/drug effects , Humans , Idiopathic Pulmonary Fibrosis/metabolism , Idiopathic Pulmonary Fibrosis/pathology , Imidazoles/pharmacology , Inflammation/chemically induced , Lung/drug effects , Lung/pathology , Lung/physiopathology , Male , Mice , Mitosis/genetics , Protein Serine-Threonine Kinases/antagonists & inhibitors , Quinoxalines/pharmacology , Receptor, Transforming Growth Factor-beta Type I , Receptors, Transforming Growth Factor beta/antagonists & inhibitors , Signal Transduction/drug effectsABSTRACT
BACKGROUND: Cigarette smoking is the main risk factor for the development of chronic obstructive pulmonary disease (COPD), a major cause of morbidity and mortality worldwide. Despite this, the cellular and molecular mechanisms that contribute to COPD pathogenesis are still poorly understood. METHODOLOGY AND PRINCIPAL FINDINGS: The objective of this study was to assess IL-1 α and ß expression in COPD patients and to investigate their respective roles in perpetuating cigarette smoke-induced inflammation. Functional studies were pursued in smoke-exposed mice using gene-deficient animals, as well as blocking antibodies for IL-1α and ß. Here, we demonstrate an underappreciated role for IL-1α expression in COPD. While a strong correlation existed between IL-1α and ß levels in patients during stable disease and periods of exacerbation, neutrophilic inflammation was shown to be IL-1α-dependent, and IL-1ß- and caspase-1-independent in a murine model of cigarette smoke exposure. As IL-1α was predominantly expressed by hematopoietic cells in COPD patients and in mice exposed to cigarette smoke, studies pursued in bone marrow chimeric mice demonstrated that the crosstalk between IL-1α+ hematopoietic cells and the IL-1R1+ epithelial cells regulates smoke-induced inflammation. IL-1α/IL-1R1-dependent activation of the airway epithelium also led to exacerbated inflammatory responses in H1N1 influenza virus infected smoke-exposed mice, a previously reported model of COPD exacerbation. CONCLUSIONS AND SIGNIFICANCE: This study provides compelling evidence that IL-1α is central to the initiation of smoke-induced neutrophilic inflammation and suggests that IL-1α/IL-1R1 targeted therapies may be relevant for limiting inflammation and exacerbations in COPD.