Resistive breathing aggravates cigarette smoke-induced pulmonary inflammation

Abstract

Introduction: Resistive breathing (RB) is the hallmark of diseases of airway obstruction, such as chronic obstructive pulmonary disease (COPD), especially during exacerbations. RB results in increased mechanical stress and inflammation in the lung of previously healthy mice. Cigarette smoke (CS) exposure, the main cause of COPD, also induces pulmonary inflammation. Aim: To investigate the potential synergistic effect of the combination of RB with CS exposure model. Methods: Mice were exposed to CS of 5 reference cigarettes, 4 times daily, 5 days per week for one month. Control mice were exposed to room air. By the end of the month mice were subjected to RB for 24 hours by tracheal banding or were sham operated. Tracheal banding was induced by placing the mice under a surgical microscope, the trachea was exposed and a nylon band was placed around the trachea and firmly sutured to provide a surface area 50% of the initial. Following 24 hours, respiratory system mechanics were assessed by the forced oscillation technique. Bronchoalveolar lavage (BAL) was performed and total and differential cell count and total protein level were measured in BAL fluid. Results: CS exposure was associated with increased BAL cellularity (10-fold to ctr, p Conclusions: Combining resistive breathing with cigarette smoke exposure results into augmented inflammatory responses.