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Asthma
Increased myoepithelial cells of bronchial submucosal glands in fatal asthma
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  1. F H Y Green1,
  2. D J Williams1,
  3. A James2,3,
  4. L J McPhee1,
  5. I Mitchell1,
  6. T Mauad4
  1. 1
    Respiratory Research Group, Faculty of Medicine, University of Calgary, Alberta, Canada
  2. 2
    Department of Pulmonary Physiology, West Australian Sleep Disorders Research Institute, Queen Elizabeth II Medical Centre, Perth, Western Australia, Australia
  3. 3
    School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia, Australia
  4. 4
    Laboratory of Air Pollution, Department of Pathology, Sao Paulo University Medical School, Sao Paulo, SP, Brazil
  1. Correspondence to Dr F H Y Green, Pathology and Laboratory Medicine, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada; fgreen{at}ucalgary.ca

Abstract

Background: Fatal asthma is characterised by enlargement of bronchial mucous glands and tenacious plugs of mucus in the airway lumen. Myoepithelial cells, located within the mucous glands, contain contractile proteins which provide structural support to mucous cells and actively facilitate glandular secretion.

Objectives: To determine if myoepithelial cells are increased in the bronchial submucosal glands of patients with fatal asthma.

Methods: Autopsied lungs from 12 patients with fatal asthma (FA), 12 patients with asthma dying of non-respiratory causes (NFA) and 12 non-asthma control cases (NAC) were obtained through the Prairie Provinces Asthma Study. Transverse sections of segmental bronchi from three lobes were stained for mucus and smooth muscle actin and the area fractions of mucous plugs, mucous glands and myoepithelial cells determined by point counting. The fine structure of the myoepithelial cells was examined by electron microscopy.

Results: FA was characterised by significant increases in mucous gland (p = 0.003), mucous plug (p = 0.004) and myoepithelial cell areas (p = 0.017) compared with NAC. When the ratio of myoepithelial cell area to total gland area was examined, there was a disproportionate and significant increase in FA compared with NAC (p = 0.014). Electron microscopy of FA cases revealed hypertrophy of the myoepithelial cells with increased intracellular myofilaments. The NFA group showed changes in these features that were intermediate between the FA and NAC groups but the differences were not significant.

Conclusions: Bronchial mucous glands and mucous gland myoepithelial cell smooth muscle actin are increased in fatal asthma and may contribute to asphyxia due to mucous plugging.

https://doi.org/10.1136/thx.2008.111435

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    Footnotes

    • ▸ Additional data are published online only at http://thorax.bmj.com/content/vol65/issue1

    • Funding Supported by Health and Welfare Canada, Herron Foundation of Alberta, Alberta Lung Association and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil. AJ is supported by the National Health and Medical Research Council of Australia.

    • Competing interests None.

    • Ethics approval Ethics approval was obtained from the institutional review boards at the Universities of Calgary, Alberta, Saskatchewan and Manitoba, Canada.

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