Cystic fibrosis lung disease reflects a failure of innate lung defense mechanisms against chronic bacterial infection. Recently, it has become apparent that the CF airway lumen is filled with adherent mucus that is relatively hypoxic. The present proposal tests the hypothesis that the hypoxic environment of the CF airways promotes infection by obligate anaerobes as mixed infections that are pathogenic for the CF lung. Accordingly, a consortium of investigators from Northern Ireland (Stuart Elborn), the Irish Republic (Gerald McElvaney), and the U.S. (Richard Boucher) have explored this hypothesis and produced the following preliminary data: 1) anaerobes are present in the CF lung, as revealed by rigorous culture and molecular diagnostic techniques;2) the anaerobes detected in CF lung do not reflect oral contamination;and 3) the high density (equal to Pseudomonas), and changes with acute exacerbation support the notion that anaerobic bacteria are pathogenic in the CF lung. The consortium will test three hypotheses that relate to the role of anaerobes in the pathogenesis of CF lung disease: 1) Specific Aim 1 will test whether there are anaerobes in the CF but not normal lung, that anaerobes and P. aeruginosa are acquired over similar time intervals, and that anaerobes are pathogens and not innocent bystanders. 2) Specific Aim 2 will test the hypothesis that anaerobes identified in the clinical study are pathogenic, investigating the molecular mechanisms underlying anaerobe growth and pathogenesis in vitro. 3) Specific Aim 3 will test the hypothesis that a complex environment is required in the diseased mouse lung in vivo to support anaerobic growth/infection, and that anaerobes are pathogenic if growth is established in the lung. The long-term goals of this project are to test the hypothesis that anaerobes are pathogenic in the CF lung, identify when they produce this pathogenic effect, and identify the mechanisms mediating pathogenesis. The outcome of these studies will be critical in designing strategies to improve therapy of CF lung disease, focused on such key issues as: should anaerobes be treated at all, and if so, treated in young patients prior to or after Ps. aeruginosa acquisition? This study will generate a bank of clinical isolates of anaerobes from CF patients that will serve for testing antimicrobial sensitivities and selecting antibiotics for future antibiotic trials to clinically test the role of anaerobes in the pathogenesis of CF lung disease.

Public Health Relevance

This proposal is designed to test the hypothesis that obligate anaerobic bacteria are pathogens in the CF lung. If so, this observation would raise the possibility that they are pathogens in other major airways diseases, e.g., chronic bronchitis. Such observations might change the way physicians approach antibiotic therapy of patients with airways disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL092964-02
Application #
8011447
Study Section
Lung Cellular, Molecular, and Immunobiology Study Section (LCMI)
Program Officer
Banks-Schlegel, Susan P
Project Start
2010-01-01
Project End
2013-12-31
Budget Start
2011-01-01
Budget End
2011-12-31
Support Year
2
Fiscal Year
2011
Total Cost
$726,233
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Sherrard, Laura J; McGrath, Stef J; McIlreavey, Leanne et al. (2016) Production of extended-spectrum β-lactamases and the potential indirect pathogenic role of Prevotella isolates from the cystic fibrosis respiratory microbiota. Int J Antimicrob Agents 47:140-5
Mirković, Bojana; Murray, Michelle A; Lavelle, Gillian M et al. (2015) The Role of Short-Chain Fatty Acids, Produced by Anaerobic Bacteria, in the Cystic Fibrosis Airway. Am J Respir Crit Care Med 192:1314-24
Sherrard, Laura J; Schaible, Bettina; Graham, Kathryn A et al. (2014) Mechanisms of reduced susceptibility and genotypic prediction of antibiotic resistance in Prevotella isolated from cystic fibrosis (CF) and non-CF patients. J Antimicrob Chemother 69:2690-8
Schwab, Ute; Abdullah, Lubna H; Perlmutt, Olivia S et al. (2014) Localization of Burkholderia cepacia complex bacteria in cystic fibrosis lungs and interactions with Pseudomonas aeruginosa in hypoxic mucus. Infect Immun 82:4729-45
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Wijesundara, Kushal C; Iftimia, Nicusor V; Oldenburg, Amy L (2013) Design of a Swept-Source, Anatomical OCT System for Pediatric Bronchoscopy. Proc SPIE Int Soc Opt Eng 8571:
Sherrard, Laura J; Graham, Kathryn A; McGrath, Stef J et al. (2013) Antibiotic resistance in Prevotella species isolated from patients with cystic fibrosis. J Antimicrob Chemother 68:2369-74
Tunney, Michael M; Einarsson, Gisli G; Wei, Lan et al. (2013) Lung microbiota and bacterial abundance in patients with bronchiectasis when clinically stable and during exacerbation. Am J Respir Crit Care Med 187:1118-26
Fodor, Anthony A; Klem, Erich R; Gilpin, Deirdre F et al. (2012) The adult cystic fibrosis airway microbiota is stable over time and infection type, and highly resilient to antibiotic treatment of exacerbations. PLoS One 7:e45001

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