Bronchoconstrictive Responses to Inhaled Ultrasonically Nebulized Distilled Water and Airway Inflammation in Asthma

Twenty-two asthmatic patients with a range of airway hyperresponsiveness to methacholine underwent a bronchial challenge with ultrasonically nebulized distilled water (UNDW). The presence of positive responses to this stimulus was related to the extent of airway inflammation, as assessed by histochemical and immunohistochemical evaluation of bronchial biopsy specimens. Twelve patients had airflow obstruction during distilled water inhalation and they showed more severe disease than subjects with no response, as demonstrated by the higher degree of nonspecific bronchial hyperresponsiveness (p < 0.01), higher variability of peak expiratory flow rates (p < 0.01), symptom scores (p < 0.01), and daily use of bronchodilators (p < 0.01). Those patients also had increased numbers of mast cells and eosinophils (p < 0.01) and increased percentage of bronchial epithelial cells expressing endothelin 1 immunoreactivity (p < 0.01). Thus, positive responses to inhaled UNDW reflect the bronchial hyperresponsiveness consistent with moderate to severe asthma and may be due to the release of mediators with bronchoconstrictive properties from inflammatory cells or activated resident cells or both.