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• W4913624 abstract "Nontypeable Haemophilus influenzae (NTHi) is an important bacterial pathogen associated with lower respiratory tract colonization and with acute exacerbations and disease progression in chronic obstructive pulmonary disease (COPD). Why the immune system fails to eliminate NTHi and the exact contribution of the organism to COPD progression are not well understood, in part because we lack an animal model that mimics all aspects of COPD. For this study, we used an established murine model that exhibits typical features of COPD. Elastase/LPS-exposed mice infected with NTHi showed persistence of bacteria up to 5 days after infection, whereas mice exposed to elastase, LPS, or PBS cleared all bacteria by 3 days. Elastase/LPS-exposed mice also showed sustained lung neutrophilic inflammation, goblet cell metaplasia, airway hyperresponsiveness, and progression of emphysema at 15 days after infection. Alveolar macrophages isolated from elastase/LPS-exposed mice showed impaired bacterial phagocytosis, reduced expression of MARCO and of mannose receptor, and absent expression of scavenger receptor-A (SR-A). Neutralization of SR-A significantly decreased phagocytosis of NTHi by normal alveolar macrophages. Our results suggest that elastase/LPS-exposed mice show impaired bacterial clearance and sustained lung inflammation. Lack of SR-A expression may, in part, be responsible for impaired phagocytosis of bacteria by alveolar macrophages of elastase/LPS-exposed mice. These data validate the suitability of elastase/LPS model for investigating NTHi pathogenesis and progression of disease in COPD. Nontypeable Haemophilus influenzae (NTHi) is an important bacterial pathogen associated with lower respiratory tract colonization and with acute exacerbations and disease progression in chronic obstructive pulmonary disease (COPD). Why the immune system fails to eliminate NTHi and the exact contribution of the organism to COPD progression are not well understood, in part because we lack an animal model that mimics all aspects of COPD. For this study, we used an established murine model that exhibits typical features of COPD. Elastase/LPS-exposed mice infected with NTHi showed persistence of bacteria up to 5 days after infection, whereas mice exposed to elastase, LPS, or PBS cleared all bacteria by 3 days. Elastase/LPS-exposed mice also showed sustained lung neutrophilic inflammation, goblet cell metaplasia, airway hyperresponsiveness, and progression of emphysema at 15 days after infection. Alveolar macrophages isolated from elastase/LPS-exposed mice showed impaired bacterial phagocytosis, reduced expression of MARCO and of mannose receptor, and absent expression of scavenger receptor-A (SR-A). Neutralization of SR-A significantly decreased phagocytosis of NTHi by normal alveolar macrophages. Our results suggest that elastase/LPS-exposed mice show impaired bacterial clearance and sustained lung inflammation. Lack of SR-A expression may, in part, be responsible for impaired phagocytosis of bacteria by alveolar macrophages of elastase/LPS-exposed mice. These data validate the suitability of elastase/LPS model for investigating NTHi pathogenesis and progression of disease in COPD. Chronic obstructive pulmonary disease (COPD) is a progressive disorder of the lung parenchyma and airways that became the third-leading cause of death in the United States in 2008.1Miniño A.M. Xu J. Kochanek K.D. Deaths: Preliminary Data for 2008.Natl Vital Stat Rep. 2010; 59: 1-52PubMed Google Scholar, 2Tuder R.M. Yoshida T. Arap W. Pasqualini R. Petrache I. State of the art Cellular and molecular mechanisms of alveolar destruction in emphysema: an evolutionary perspective.Proc Am Thorac Soc. 2006; 3: 503-510Crossref PubMed Scopus (144) Google Scholar Acute exacerbations are associated with disease progression and are also a major cause of morbidity and mortality in COPD patients.3Wedzicha J.A. Mechanisms of exacerbations.Novartis Found Symp. 2001; 234 (discussion 93–103): 84-93Crossref PubMed Google Scholar, 4Wedzicha J.A. Role of viruses in exacerbations of chronic obstructive pulmonary disease.Proc Am Thorac Soc. 2004; 1: 115-120Crossref PubMed Scopus (191) Google Scholar Approximately two thirds of all of the infectious exacerbations are associated with bacterial infection, alone or in combination with respiratory viruses.5Sethi S. Evans N. Grant B.J. Murphy T.F. New strains of bacteria and exacerbations of chronic obstructive pulmonary disease.N Engl J Med. 2002; 347: 465-471Crossref PubMed Scopus (873) Google Scholar, 6Sapey E. Stockley R.A. COPD exacerbations. 2: aetiology.Thorax. 2006; 61: 250-258Crossref PubMed Scopus (335) Google Scholar Acute exacerbations are associated with the acquisition of new strains of nontypeable Haemophilus influenzae (NTHi), Moraxella catarrhalis, and Streptococcus pneumoniae and, in patients with severely reduced lung function, Enterobacteriaceae and Pseudomonas species.7Larsen M.V. Janner J.H. Nielsen S.D. Friis-Møller A. Ringbaek T. Lange P. Bacteriology in acute exacerbation of chronic obstructive pulmonary disease in patients admitted to hospital.Scand J Infect Dis. 2009; 41: 26-32Crossref PubMed Scopus (24) Google Scholar The lower airways of some COPD patients are also chronically colonized with bacteria readily detectable by conventional culture-dependent methods; these patients show elevated markers of inflammation, compared with individuals who do not show bacterial colonization by this methodology.8Hill A.T. Campbell E.J. Hill S.L. Bayley D.L. Stockley R.A. Association between airway bacterial load and markers of airway inflammation in patients with stable chronic bronchitis.Am J Med. 2000; 109: 288-295Abstract Full Text Full Text PDF PubMed Scopus (338) Google Scholar, 9Soler N. Ewig S. Torres A. Filella X. Gonzalez J. Zaubet A. Airway inflammation and bronchial microbial patterns in patients with stable chronic obstructive pulmonary disease.Eur Respir J. 1999; 14: 1015-1022Crossref PubMed Scopus (321) Google Scholar NTHi is the most frequently isolated bacterial pathogen from sputum of COPD patients under stable conditions.10Murphy T.F. Brauer A.L. Schiffmacher A.T. Sethi S. Persistent colonization by Haemophilus influenzae in chronic obstructive pulmonary disease.Am J Respir Crit Care Med. 2004; 170: 266-272Crossref PubMed Google Scholar Impaired innate immune defense mechanisms are thought to contribute to the bacterial infection and persistence of bacteria in these patients.Alveolar macrophages are professional phagocytes that play a critical role in the clearance of infecting bacteria while preventing excessive pulmonary inflammation. Alveolar macrophages express a variety of cell surface receptors that are crucial for recognition and phagocytosis of pathogens and stimulating the appropriate immune response to infection. Compared with alveolar macrophages from healthy nonsmokers, alveolar and monocyte-derived macrophages from COPD patients are deficient in phagocytosis of common respiratory bacterial pathogens, including NTHi and S. pneumoniae,11Berenson C.S. Garlipp M.A. Grove L.J. Maloney J. Sethi S. Impaired phagocytosis of nontypeable Haemophilus influenzae by human alveolar macrophages in chronic obstructive pulmonary disease.J Infect Dis. 2006; 194: 1375-1384Crossref PubMed Scopus (170) Google Scholar, 12Taylor A.E. Finney-Hayward T.K. Quint J.K. Thomas C.M. Tudhope S.J. Wedzicha J.A. Barnes P.J. Donnelly L.E. Defective macrophage phagocytosis of bacteria in COPD.Eur Respir J. 2010; 35: 1039-1047Crossref PubMed Scopus (254) Google Scholar and of apoptotic cells.13Hodge S. Hodge G. Scicchitano R. Reynolds P.N. Holmes M. Alveolar macrophages from subjects with chronic obstructive pulmonary disease are deficient in their ability to phagocytose apoptotic airway epithelial cells.Immunol Cell Biol. 2003; 81 ([Erratum appeared in Immunol Cell Biol 2003, 81:499]): 289-296Crossref PubMed Scopus (343) Google Scholar, 14Hodge S. Hodge G. Ahern J. Jersmann H. Holmes M. Reynolds P.N. Smoking alters alveolar macrophage recognition and phagocytic ability: implications in chronic obstructive pulmonary disease.Am J Respir Cell Mol Biol. 2007; 37: 748-755Crossref PubMed Scopus (266) Google Scholar Although the importance of bacterial clearance seems evident, impaired efferocytosis (ie, clearance of apoptotic cells) has also been linked to COPD progression.2Tuder R.M. Yoshida T. Arap W. Pasqualini R. Petrache I. State of the art Cellular and molecular mechanisms of alveolar destruction in emphysema: an evolutionary perspective.Proc Am Thorac Soc. 2006; 3: 503-510Crossref PubMed Scopus (144) Google Scholar, 15Henson P.M. Cosgrove G.P. Vandivier R.W. State of the art Apoptosis and cell homeostasis in chronic obstructive pulmonary disease.Proc Am Thorac Soc. 2006; 3: 512-516Crossref PubMed Scopus (44) Google Scholar The precise mechanisms for the observed defects in COPD are unclear. Defining the molecular basis for defects in alveolar macrophage phagocytic function could lead to novel therapies to improve morbidity and mortality in COPD, which typically progresses even after smoking cessation.One family of receptors that plays a role in the host innate defense against inhaled particles and pathogens is the class A scavenger receptors, which include macrophage receptor with collagenous structure (MARCO) and scavenger receptor A (SR-A), which is expressed as SR-A I and SR-A II in humans because of a splice variant and as a single form (SR-A I/II) in mice.16Arredouani M.S. Yang Z. Imrich A. Ning Y. Qin G. Kobzik L. The macrophage scavenger receptor SR-AI/II and lung defense against pneumococci and particles.Am J Respir Cell Mol Biol. 2006; 35: 474-478Crossref PubMed Scopus (122) Google Scholar, 17Arredouani M. Yang Z. Ning Y. Qin G. Soininen R. Tryggvason K. Kobzik L. The scavenger receptor MARCO is required for lung defense against pneumococcal pneumonia and inhaled particles.J Exp Med. 2004; 200: 267-272Crossref PubMed Scopus (262) Google Scholar, 18Dahl M. Bauer A.K. Arredouani M. Soininen R. Tryggvason K. Kleeberger S.R. Kobzik L. Protection against inhaled oxidants through scavenging of oxidized lipids by macrophage receptors MARCO and SR-AI/II.J Clin Invest. 2007; 117: 757-764Crossref PubMed Scopus (96) Google Scholar Both receptors were shown to be required for efficient clearance of pneumococci from the lungs of infected mice16Arredouani M.S. Yang Z. Imrich A. Ning Y. Qin G. Kobzik L. The macrophage scavenger receptor SR-AI/II and lung defense against pneumococci and particles.Am J Respir Cell Mol Biol. 2006; 35: 474-478Crossref PubMed Scopus (122) Google Scholar, 17Arredouani M. Yang Z. Ning Y. Qin G. Soininen R. Tryggvason K. Kobzik L. The scavenger receptor MARCO is required for lung defense against pneumococcal pneumonia and inhaled particles.J Exp Med. 2004; 200: 267-272Crossref PubMed Scopus (262) Google Scholar and also for protection against inhaled oxidants.18Dahl M. Bauer A.K. Arredouani M. Soininen R. Tryggvason K. Kleeberger S.R. Kobzik L. Protection against inhaled oxidants through scavenging of oxidized lipids by macrophage receptors MARCO and SR-AI/II.J Clin Invest. 2007; 117: 757-764Crossref PubMed Scopus (96) Google Scholar Importantly, the risk of developing COPD is increased in humans with mutations in the macrophage scavenger receptor 1 gene, MSR1, which encodes SR-A types I and II; these mutations result in expression of a receptor lacking the distal collagen-like domain, which is essential in ligand recognition.19Hersh C.P. DeMeo D.L. Raby B.A. Litonjua A.A. Sylvia J.S. Sparrow D. Reilly J.J. Silverman E.K. Genetic linkage and association analysis of COPD-related traits on chromosome 8p.COPD. 2006; 3: 189-194Crossref PubMed Scopus (27) Google Scholar, 20Ohar J.A. Hamilton Jr, R.F. Zheng S. Sadeghnejad A. Sterling D.A. Xu J. Meyers D.A. Bleecker E.R. Holian A. COPD is associated with a macrophage scavenger receptor-1 gene sequence variation.Chest. 2010; 137: 1098-1107Crossref PubMed Scopus (27) Google Scholar, 21Thomsen M. Nordestgaard B.G. Tybjaerg-Hansen A. Dahl M. Scavenger receptor AI/II truncation, lung function and COPD: a large population-based study.J Intern Med. 2011; 269: 340-348Crossref PubMed Scopus (10) Google Scholar Reduced efferocytosis by alveolar macrophages from COPD patients was attributed in part to decreased expression of surface receptors, including CD31, CD91 and CD44.14Hodge S. Hodge G. Ahern J. Jersmann H. Holmes M. Reynolds P.N. Smoking alters alveolar macrophage recognition and phagocytic ability: implications in chronic obstructive pulmonary disease.Am J Respir Cell Mol Biol. 2007; 37: 748-755Crossref PubMed Scopus (266) Google Scholar However, these studies did not examine expression of SR-A, which we previously showed is essential for optimal efferocytosis by murine peritoneal macrophages and macrophage cell lines.22Todt J.C. Hu B. Curtis J.L. The scavenger receptor SR-A I/II (CD204) signals via the receptor tyrosine kinase Mertk during apoptotic cell uptake by murine macrophages.J Leukoc Biol. 2008; 84: 510-518Crossref PubMed Scopus (73) Google Scholar Collectively, these findings indicate the importance of defining the possible role of alveolar macrophage scavenger receptors in lung host defense and homeostasis.To this end, we used an established experimental model in which mice show structural and functional features typical of human COPD, including pulmonary emphysema, loss of lung elastic recoil, hyperinflation, goblet cell metaplasia, markedly increased numbers of neutrophils, T and B lymphocytes, monocytes and macrophages in the airways and alveoli, and a deficiency in clearing rhinovirus infection.23Sajjan U. Ganesan S. Comstock A.T. Shim J. Wang Q. Nagarkar D.R. Zhao Y. Goldsmith A.M. Sonstein J. Linn M.J. Curtis J.L. Hershenson M.B. Elastase- and LPS-exposed mice display altered responses to rhinovirus infection.Am J Physiol Lung Cell Mol Physiol. 2009; 297: L931-L944Crossref PubMed Scopus (76) Google Scholar, 24Ganesan S. Faris A.N. Comstock A.T. Chattoraj S.S. Chattoraj A. Burgess J.R. Curtis J.L. Martinez F.J. Zick S. Hershenson M.B. Sajjan U.S. Quercetin prevents progression of disease in elastase/LPS-exposed mice by negatively regulating MMP expression.Respir Res. 2010; 11: 131Crossref PubMed Scopus (93) Google Scholar Our results highlight the importance of alveolar macrophage class A scavenger receptors, especially SR-A, for clearance of NTHi.Materials and MethodsAnimals and TreatmentNormal 8- to 10-week-old C57BL/6 mice (Charles River Laboratories International, Wilmington, MA) maintained in a specific pathogen-free environment were exposed to elastase and LPS for four consecutive weeks, as described previously.23Sajjan U. Ganesan S. Comstock A.T. Shim J. Wang Q. Nagarkar D.R. Zhao Y. Goldsmith A.M. Sonstein J. Linn M.J. Curtis J.L. Hershenson M.B. Elastase- and LPS-exposed mice display altered responses to rhinovirus infection.Am J Physiol Lung Cell Mol Physiol. 2009; 297: L931-L944Crossref PubMed Scopus (76) Google Scholar, 24Ganesan S. Faris A.N. Comstock A.T. Chattoraj S.S. Chattoraj A. Burgess J.R. Curtis J.L. Martinez F.J. Zick S. Hershenson M.B. Sajjan U.S. Quercetin prevents progression of disease in elastase/LPS-exposed mice by negatively regulating MMP expression.Respir Res. 2010; 11: 131Crossref PubMed Scopus (93) Google Scholar At 1 week after the last exposure to LPS, mice were examined for susceptibility to bacterial infection. Mice treated with PBS instead of elastase/LPS were used as controls in all experiments. In selected experiments, mice were exposed to elastase alone or LPS alone once a week for four consecutive weeks. All experiments were approved by the Animal Care and Use Committee of the University of Michigan.Bacteria and Growth ConditionsNTHi (isolate 6P5H), isolated from a COPD patient at the time of acute exacerbation, was kindly provided by T.F. Murphy (University of Buffalo) and was maintained as glycerol stock at −80°C. Bacteria were subcultured and grown on chocolate agar, as described previously.25Sajjan U. Wang Q. Zhao Y. Gruenert D.C. Hershenson M.B. Rhinovirus disrupts the barrier function of polarized airway epithelial cells.Am J Respir Crit Care Med. 2008; 178: 1271-1281Crossref PubMed Scopus (237) Google Scholar In some experiments, bacteria were labeled with either fluorescein isothiocyanate (FITC) (Pierce; Thermo Fisher Scientific, Rockford, IL) or Alexa Fluor 555 (Invitrogen, Carlsbad, CA), as described previously.26Chattoraj S.S. Murthy R. Ganesan S. Goldberg J.B. Zhao Y. Hershenson M.B. Sajjan U.S. Pseudomonas aeruginosa alginate promotes Burkholderia cenocepacia persistence in cystic fibrosis transmembrane conductance regulator knockout mice.Infect Immun. 2010; 78: 984-993Crossref PubMed Scopus (20) Google ScholarInfection of MiceAfter the 4 weeks of exposure to elastase/LPS, elastase, LPS, or PBS, mice were anesthetized by intraperitoneal injection of xylazine (1 mg/kg body weight) and ketamine (50 mg/kg body weight) and infected with 50 μL of NTHi (5 × 107 CFU) or with the same volume of PBS (sham infection) by the intratracheal route. Mice were euthanized humanely at 1, 3, 5, or 15 days after infection for use in a variety of assays; not all mice were used in each assay.Lung Function MeasurementsMice were anesthetized and a steel cannula was inserted into the trachea and connected to a miniature computerized FlexiVent ventilator (Scireq, Montreal, QC, Canada). To determine elastic recoil, lungs were gradually inflated to 30 cm H2O; pressure and lung volume were then measured continuously during inflation and deflation of the lungs. Airway responsiveness to methacholine was measured as described previously.23Sajjan U. Ganesan S. Comstock A.T. Shim J. Wang Q. Nagarkar D.R. Zhao Y. Goldsmith A.M. Sonstein J. Linn M.J. Curtis J.L. Hershenson M.B. Elastase- and LPS-exposed mice display altered responses to rhinovirus infection.Am J Physiol Lung Cell Mol Physiol. 2009; 297: L931-L944Crossref PubMed Scopus (76) Google ScholarLung HistologyLungs were inflation-fixed with 10% buffer formalin and embedded in paraffin. Sagittal sections, 5 μm thick, were stained with H&E or PAS reagent.Bacterial Persistence and Measurement of CytokinesLungs were harvested from mice under aseptic conditions and homogenized in 2 mL of PBS. Lung homogenates were serially diluted and plated on chocolate agar plates to determine the bacterial load. Homogenate supernatants were used to determine protein levels of proinflammatory cytokines by enzyme-linked immunosorbent assay (R&D Systems, Minneapolis, MN).Measurement of Muc5AC and Muc5B ExpressionAfter RNA extraction, Muc5AC and Muc5B mRNA levels were measured by quantitative real-time PCR using specific primers and probes.Bronchoalveolar LavageMice were euthanized and lungs were lavaged with PBS containing 20 mmol/L EDTA; cells were collected by centrifugation. Total and differential cell counts in bronchoalveolar lavage fluid (BALF) were determined as described previously.23Sajjan U. Ganesan S. Comstock A.T. Shim J. Wang Q. Nagarkar D.R. Zhao Y. Goldsmith A.M. Sonstein J. Linn M.J. Curtis J.L. Hershenson M.B. Elastase- and LPS-exposed mice display altered responses to rhinovirus infection.Am J Physiol Lung Cell Mol Physiol. 2009; 297: L931-L944Crossref PubMed Scopus (76) Google Scholar The cells were immunolabeled with antibodies against CD45, CD11c, CD11b (eBiosciences, San Diego, CA), SR-A, MARCO, mannose receptor, CD80, and CD36 (AbD Serotec, Raleigh, NC) and analyzed on an LSR II flow cytometer (BD Bioscience, San Jose, CA) equipped with 488-nm blue, 405-nm violet, and 633-nm red lasers, as described previously.23Sajjan U. Ganesan S. Comstock A.T. Shim J. Wang Q. Nagarkar D.R. Zhao Y. Goldsmith A.M. Sonstein J. Linn M.J. Curtis J.L. Hershenson M.B. Elastase- and LPS-exposed mice display altered responses to rhinovirus infection.Am J Physiol Lung Cell Mol Physiol. 2009; 297: L931-L944Crossref PubMed Scopus (76) Google ScholarPhagocytosis AssayBALF cells from PBS or elastase/LPS-exposed mice were centrifuged, suspended in RPMI 1640 medium containing 10% fetal bovine serum, seeded in two-chamber coverslipped glass slides (Invitrogen, Carlsbad, CA), and incubated for 2 hours. The chamber slides were rinsed briefly with medium to remove unattached cells and infected with Alexa Fluor 555-labeled NTHi. Phagocytosis of bacteria in real time was recorded for 30 minutes using a DeltaVision RT-live cell imaging system (Applied Precision, Issaquah, WA).In some experiments, resident alveolar macrophages plated in chamber slides were infected with FITC-labeled NTHi and extracellular fluorescence was quenched with Trypan Blue, as described previously.26Chattoraj S.S. Murthy R. Ganesan S. Goldberg J.B. Zhao Y. Hershenson M.B. Sajjan U.S. Pseudomonas aeruginosa alginate promotes Burkholderia cenocepacia persistence in cystic fibrosis transmembrane conductance regulator knockout mice.Infect Immun. 2010; 78: 984-993Crossref PubMed Scopus (20) Google Scholar The number of cells positive for intracellular FITC-labeled bacteria was counted under a fluorescence microscope equipped with phase contrast to determine phagocytosis index.The capacity of immortalized MH-S murine alveolar macrophages (CRL-2019; ATCC, Manassas, VA) to phagocytose NTHi was quantified by flow cytometry, as described previously.26Chattoraj S.S. Murthy R. Ganesan S. Goldberg J.B. Zhao Y. Hershenson M.B. Sajjan U.S. Pseudomonas aeruginosa alginate promotes Burkholderia cenocepacia persistence in cystic fibrosis transmembrane conductance regulator knockout mice.Infect Immun. 2010; 78: 984-993Crossref PubMed Scopus (20) Google Scholar Briefly, macrophages were seeded in six-well plates and incubated with FITC-labeled NTHi at 10 MOI (multiplicity of infection) for 1 hour. Cells were washed, extracellular fluorescence was quenched with Trypan Blue, and then cells were analyzed by flow cytometry. In some experiments, macrophages were pretreated with neutralizing antibody to SR-A (Cell Sciences, Canton, MA) or isotype control for 1 hour at 37°C, infected with FITC-labeled NTHi, and analyzed by flow cytometry as above.Statistical AnalysisResults are presented as means ± SEM. Data were analyzed using SigmaStat statistical software (Systat Software, San Jose, CA). One-way analysis of variance with Tukey-Kramer post hoc analysis was performed to compare more than two groups. To compare two groups, an unpaired t-test with Welch's correction was used. A P value <0.05 was considered significant.ResultsElastase/LPS-Exposed Mice Show Persistent Pulmonary Bacterial Load and Lung InflammationMice exposed to PBS or to elastase/LPS were infected intratracheally with NTHi and euthanized at 1, 3, and 5 days after infection. Lung bacterial load was determined. Although both PBS-exposed and elastase/LPS-exposed mice showed bacteria in the lungs 24 hours after infection, only elastase/LPS-exposed mice showed persistence of bacteria up to 5 days after infection (Figure 1A).Bronchoalveolar lavage was performed to determine the total and differential cell counts (Figure 1, B and C). Both PBS-exposed and elastase/LPS-exposed mice showed a 1-log increase in total cell counts 1 day after NTHi infection, compared with their respective sham-infected controls, and neutrophils accounted for 85% to 87% of the cells in both groups. At 3 days after infection, total cells decreased slightly in both groups of mice. Neutrophilic inflammation persisted in both groups, but was significantly higher in the elastase/LPS-exposed group. By 5 days after infection, total and neutrophil cell counts returned to baseline in the PBS group and were similar to those of sham-infected controls. The elastase/LPS-exposed mice, however, showed slightly increased total cell counts and sustained neutrophilic inflammation. Total and differential cell counts in sham-infected animals on days 3 and 5 were similar to those observed at 1 day after infection (data not shown). Myeloperoxidase activity significantly increased in both groups at 1 day after infection, compared with the respective sham-infected animals (Figure 1D). Although myeloperoxidase levels returned to normal levels in the PBS group, the elastase/LPS group showed persistently increased myeloperoxidase levels, consistent with the observed increase in BALF neutrophils.H&E-stained lung sections from sham-infected animals were histologically similar to those from the respective uninfected mice. At 1 day after infection with NTHi, both PBS-exposed and elastase/LPS-treated mice showed an inflammatory infiltrate, with neutrophils predominating (Figure 2, A, B, and D–F). However, compared with the PBS group, elastase/LPS-exposed mice showed more inflammation (Figure 2, D–G). Whereas PBS-exposed mice showed localized accumulation of inflammatory cells in the peribronchiolar and perivascular areas, elastase/LPS-exposed mice showed widespread neutrophilic inflammation, including in the airway lumina and alveoli (Figure 2, E and F). At 5 days after infection, the inflammation in PBS-exposed mice resolved completely (Figure 2C). In contrast, elastase/LPS-exposed mice showed persistent inflammation up to 5 days after infection (Figure 2G). Consistent with this observation, we observed sustained increases in the proinflammatory cytokines TNF-α, IL-1β, IL-6, KC, MIP-2, and CCL2 up to 5 days after NTHi challenge in elastase/LPS-exposed but not PBS-exposed mice (see Supplemental Figure S1 at http://ajp.amjpathol.org).Figure 2Histology of mice infected with NTHi. Paraffin-embedded lung sections from PBS-or elastase/LPS-exposed mice infected with NTHi were stained with H&E. A: PBS-exposed mouse, 1 day after infection. B: Inflammatory cells seen at higher magnification; the image corresponds to the area outlined in panel A. C: PBS-treated mouse, 5 days after infection. D–F: Elastase/LPS-exposed mice at 1 day after infection. E: Neutrophils in the airway lumen seen at higher magnification; the image corresponds to the area outlined in panel D. F: Neutrophils in the alveolar space. G: Elastase/LPS-exposed mice exhibit moderate lung inflammation, 5 days after infection. Arrows indicate neutrophils; arrowheads indicate macrophages. Images are representative of 3 mice from each group. Scale bars: 50 μm (B, E, and F); 200 μm (A, C, D, and G).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Elastase/LPS-exposed mice with sham infection showed more PAS-positive material than the PBS-exposed mice in both large and small airways, as observed previously (Figure 3, A and B).23Sajjan U. Ganesan S. Comstock A.T. Shim J. Wang Q. Nagarkar D.R. Zhao Y. Goldsmith A.M. Sonstein J. Linn M.J. Curtis J.L. Hershenson M.B. Elastase- and LPS-exposed mice display altered responses to rhinovirus infection.Am J Physiol Lung Cell Mol Physiol. 2009; 297: L931-L944Crossref PubMed Scopus (76) Google Scholar, 24Ganesan S. Faris A.N. Comstock A.T. Chattoraj S.S. Chattoraj A. Burgess J.R. Curtis J.L. Martinez F.J. Zick S. Hershenson M.B. Sajjan U.S. Quercetin prevents progression of disease in elastase/LPS-exposed mice by negatively regulating MMP expression.Respir Res. 2010; 11: 131Crossref PubMed Scopus (93) Google Scholar PAS-positive cells further increased after bacterial infection in elastase/LPS-exposed mice (Figure 3, C and D), but not in similarly infected PBS-exposed mice (Figure 3, E and F). RT-PCR analysis indicated a significant increase in Muc5AC expression at 1, 3, and 5 days after infection in elastase/LPS-exposed mice, but only 1 day after infection in PBS-exposed mice (Figure 3G). There were no changes in Muc5B expression in either group of mice.Figure 3Mucin expression in NTHi-infected mice. Paraffin-embedded lung sections from PBS-exposed or elastase/LPS-exposed mice infected with NTHi were stained with PAS. A and B: Lung sections from sham-infected elastase/LPS-exposed mice show PAS-positive cells in large (A) and small (B) airways. C and D: Lung sections from elastase/LPS-exposed mice at 5 days after infection show increased PAS-positive cells and PAS-positive material in large (C) and small (D) airways. E and F: Lung sections from PBS-exposed mice at 5 days after infection show few PAS-positive cells in the large airway (E), but not in the small airway (F). Arrows indicate PAS-positive cells and arrowheads indicate PAS-positive material in airway lumen. Images are representative of three animals per group. G: Total RNA was extracted from sham-infected or NTHi-infected mice at 1, 3, or 5 days after infection. Muc5AC and Muc5B gene expression determined by real-time PCR was normalized to expression of β-actin and expressed as fold increase relative to sham-infected PBS-exposed mice. Data are presented as means ± SEM (n = 5 mice/per group). *P ≤ 0.05 versus PBS-treated mice, analysis of variance; †P ≤ 0.05 versus sham-infected mice, analysis of variance. Scale bars: 50 μm.View Large Image Figure ViewerDownload Hi-res image Download (PPT)NTHi Infection Affects Lung Function in Elastase/LPS-Exposed MiceTo examine whether overt inflammation caused by bacterial infection was associated with altered lung function, we examined pressure-volume relationships and airway cholinergic responsiveness in mice 1 and 5 days after infection. Pressure-volume loops did not change significantly in infected animals and were similar to those of uninfected mice (data not shown). We also measured airway responsiveness to increasing doses of nebulized methacholine. NTHi-infected, PBS-exposed mice showed no significant increase in airway" @default.
• W4913624 created "2016-06-24" @default.
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• W4913624 date "2012-01-01" @default.
• W4913624 modified "2023-10-18" @default.
• W4913624 title "Elastase/LPS-Exposed Mice Exhibit Impaired Innate Immune Responses to Bacterial Challenge" @default.
• W4913624 cites W119247573 @default.
• W4913624 cites W1498223456 @default.
• W4913624 cites W1596007839 @default.
• W4913624 cites W1614546692 @default.
• W4913624 cites W1929857088 @default.
• W4913624 cites W1966312417 @default.
• W4913624 cites W1966388070 @default.
• W4913624 cites W1970883748 @default.
• W4913624 cites W1980191732 @default.
• W4913624 cites W1980213997 @default.
• W4913624 cites W1984173055 @default.
• W4913624 cites W1985829398 @default.
• W4913624 cites W1986142113 @default.
• W4913624 cites W1999098361 @default.
• W4913624 cites W2004556227 @default.
• W4913624 cites W2006291490 @default.
• W4913624 cites W2010701664 @default.
• W4913624 cites W2029335692 @default.
• W4913624 cites W2035643252 @default.
• W4913624 cites W2037317202 @default.
• W4913624 cites W2040469767 @default.
• W4913624 cites W2040884453 @default.
• W4913624 cites W2042722520 @default.
• W4913624 cites W2044927291 @default.
• W4913624 cites W2047090489 @default.
• W4913624 cites W2050733122 @default.
• W4913624 cites W2054316293 @default.
• W4913624 cites W2058975819 @default.
• W4913624 cites W2059873587 @default.
• W4913624 cites W2085021685 @default.
• W4913624 cites W2087073499 @default.
• W4913624 cites W2090110893 @default.
• W4913624 cites W2093117593 @default.
• W4913624 cites W2097240008 @default.
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• W4913624 cites W2115449634 @default.
• W4913624 cites W2115693059 @default.
• W4913624 cites W2116064154 @default.
• W4913624 cites W2120493819 @default.
• W4913624 cites W2127676550 @default.
• W4913624 cites W2131829840 @default.
• W4913624 cites W2136394058 @default.
• W4913624 cites W2139348724 @default.
• W4913624 cites W2145621175 @default.
• W4913624 cites W2145710202 @default.
• W4913624 cites W2145964444 @default.
• W4913624 cites W2151555881 @default.
• W4913624 cites W2152702795 @default.
• W4913624 cites W2153971243 @default.
• W4913624 cites W2160442039 @default.
• W4913624 cites W2165681911 @default.
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