Detection of Cell-Dissociated Non-Typeable Haemophilus influenzae in the Airways of Patients with Chronic Obstructive Pulmonary Disease

Abstract

Background

Non-typeable Haemophilus influenzae (NTHi) is the most commonly found pathogen in the lower respiratory airways of patients with COPD. NTHi is predominantly regarded as an intracellular pathogen; however, like most pathogens, it can exist and co-exist in two broad forms: cell-associated (intracellularly or adhered to cells) or cell-dissociated (biofilm dispersed or planktonic). We sought to investigate if cell-dissociated NTHi can be detected from the sputum of COPD patients and assess this relationship to disease severity and airway inflammation.

Methods

DNA was extracted from the sputum plug and cell-free supernatant to quantify absolute (cell-associated and cell-dissociated NTHi) and cell-dissociated NTHi, respectively, from 87 COPD subjects attending an observational longitudinal COPD exacerbation study. NTHi was quantified using TaqMan hydrolysis probes, targeting the OMP P6 gene using qPCR.

Results

At stable state cell-dissociated NTHi was detected 56% of subjects with a median (IQR) of 9.95x10 ² gene copies (1.26x10 ² to 1.90x10 ⁴). Cell-dissociated NTHi correlated with absolute NTHi levels (r=0.34, p<0.01) but not airway inflammation or spirometry at stable state. At exacerbation, cell-dissociated NTHi correlated with lung function (FEV ₁ r=0.629, p=0.005; FEV ₁%predicted r=0.564, p=0.015; FVC r=0.476 p=0.046) and sputum neutrophilic inflammation (% neutrophils r=0.688, p=0.002; total neutrophils r=0.518, p=0.028).

Conclusion

In patients with COPD, NTHi can exist in both cell-associated and cell-dissociated forms. Cell-dissociated NTHi is associated with neutrophilic airway inflammation during exacerbations of COPD and may be a driving factor in worsening lung function during these episodes.

Journal

Journal ID (nlm-ta): Int J Chron Obstruct Pulmon Dis

Journal ID (iso-abbrev): Int J Chron Obstruct Pulmon Dis

Journal ID (publisher-id): COPD

Journal ID (pmc): copd

Title: International Journal of Chronic Obstructive Pulmonary Disease

Publisher: Dove

ISSN (Print): 1176-9106

ISSN (Electronic): 1178-2005

Publication date (Electronic): 12 June 2020

Publication date Collection: 2020

Volume: 15

Pages: 1357-1365

Affiliations

[1 ]Respiratory Medicine Unit, Nuffield Department of Medicine, University of Oxford , Oxford, UK

[2 ]Oxford NIHR Biomedical Research Centre, University of Oxford , Oxford, UK

[3 ]Target Discovery Institute, Nuffield Department of Medicine, University of Oxford , Oxford, UK

[4 ]Department of Immunity, Infection and Inflammation, University of Leicester , Leicester, UK

[5 ]Institute for Lung Health, University of Leicester , Leicester, UK

Author notes

Correspondence: Mona Bafadhel Respiratory Medicine Unit, NDM Research Building, Old Campus Road, University of Oxford , OxfordOX3 7FZ, UKTel [phone] Email [e-mail]

Article

Publisher ID: 247130

DOI: 10.2147/COPD.S247130

PMC ID: 7297347

Copyright statement: © 2020 Thulborn et al.

License:

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Page count

Figures: 3, Tables: 4, References: 36, Pages: 9

Funding

This work was funded by the Medical Research Council, the Wellcome Trust & Academy of Medical Sciences and 330 the Oxfordshire Health Services Research Committee. This paper presents independent research funded by the National Institute for Health Research and the views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

Categories

Subject: Original Research