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Chronic obstructive pulmonary disease
Original research
Mucus clears from the trachea in a helix: a new twist to understanding airway diseases
  1. David Abelson1,2,
  2. James Di Michiel1,
  3. Clayton Frater2,3,
  4. Mark Pearson3,
  5. Robert Russo3,
  6. Martin Wechselberger4,
  7. Alice Cottee1,
  8. Lucy Morgan1,5
  1. 1Department of Respiratory Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia
  2. 2School of Medicine, University of Sydney, Sydney, NSW, Australia
  3. 3Department of Nuclear Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia
  4. 4School of Mathematics & Statistics, The University of Sydney, Sydney, New South Wales, Australia
  5. 5Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
  1. Correspondence to Dr David Abelson, Respiratory Medicine, Concord Repatriation General Hospital, Concord, New South Wales, Australia; abelsond{at}gmail.com

Abstract

Background Mucociliary clearance (MCC) is critical to lung health and is impaired in many diseases. The path of MCC may have an important impact on clearance but has never been rigorously studied. The objective of this study is to assess the three-dimensional path of human tracheal MCC in disease and health.

Methods Tracheal MCC was imaged in 12 ex-smokers, 3 non-smokers (1 opportunistically imaged during acute influenza and repeated after recovery) and 5 individuals with primary ciliary dyskinesia (PCD). Radiolabelled macroaggregated albumin droplets were injected into the trachea via the cricothyroid membrane. Droplet movement was tracked via scintigraphy, the path of movement mapped and helical and axial models of tracheal MCC were compared.

Measurements and main results In 5/5 participants with PCD and 1 healthy participant with acute influenza, radiolabelled albumin coated the trachea and did not move. In all others (15/15), mucus coalesced into globules. Globule movement was negligible in 3 ex-smokers, but in all others (12/15) ascended the trachea in a helical path. Median cephalad tracheal MCC was 2.7 mm/min ex-smokers vs 8.4 mm/min non-smokers (p=0.02) and correlated strongly to helical angle (r=0.92 (p=0.00002); median 18o ex-smokers, 47o non-smokers (p=0.036)), but not to actual speed on helical path (r=0.26 (p=0.46); median 13.6 mm/min ex-smokers vs 13.9 mm/min non-smokers (p=1.0)).

Conclusion For the first time, we show that human tracheal MCC is helical, and impairment in ex-smokers is often caused by flattened helical transit, not slower movement. Our methodology provides a simple method to map tracheal MCC and speed in vivo.

  • Airway Epithelium
  • Bronchiectasis
  • COPD Pathology
  • Imaging/CT MRI etc
  • Lung Physiology
  • Primary ciliary dyskinesia

Data availability statement

Data are available on reasonable request.

https://doi.org/10.1136/thorax-2023-221052

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    Data availability statement

    Data are available on reasonable request.

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    Footnotes

    • Contributors DA: recruited subjects, imaged non-smokers and ex-smokers, wrote mathematical models and statistical analysis, authored manuscript. JDM: imaged PCD cohort, coauthored manuscript. CF: scintigraphy imaging of all patients. MP: author of CiliaC and extraction of all coordinate data. RR: scintigraphy management. MW: oversight of mathematical models. AC: project ethics and governance and imaged non-smokers and ex-smokers. LM: study plan, oversight, guarantor, coauthored manuscript.

    • Funding This investigator-initiated and led study was made possible by an unrestricted project grant from Novartis Australia.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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