Lipid-laden bronchoalveolar macrophages in asthma and chronic cough

Abstract

Background: The presence of lipids in alveolar macrophages (AMs) may impair their phagocytic response, and determine airway inflammation and obstruction.

Objective: To determine the factors such as severity of asthma, chronic cough, airway inflammation and obesity that may influence the presence of lipids in lung macrophages.

Methods: Bronchoalveolar lavage fluid (BALF) was obtained from 38 asthmatics (21 severe and 17 mild/moderate), 16 subjects with chronic cough and 11 healthy control subjects. The presence of lipids in macrophages was detected using an Oil-red-O stain and an index of lipid-laden macrophages (LLMI) was obtained.

Results: LLMI scores were higher in healthy subjects (median 48 [IQR 10-61]) and the severe asthma group (37 [11.5-61]) compared to mild/moderate asthmatics (7 [0.5-37]; p < 0.05 each). Subjects reporting a history of gastro-oesophageal reflux disease (GORD) had higher LLMI values (41.5 [11.3-138] versus 13 [0-39.3], p = 0.02). There was no significant correlation between LLMI and chronic cough, BAL cell differential counts, FEV1, FEV1/FVC or body mass index (BMI).

Conclusions: The reduced LLMI in mild/moderate asthma may be related to lower incidence of GORD. However, this was not related to the degree of airflow obstruction, obesity or airway inflammation.

Keywords: Asthma; Cough; Lipid-laden macrophages.