Effects of azithromycin on bronchial remodeling in the natural model of severe neutrophilic asthma in horses.

The researchers conducted a study to assess whether adding azithromycin to inhaled corticosteroids improves lung function, inflammation, and the structure of airways in severe asthma. The results showed that while azithromycin did better control airway inflammation, it did not enhance the other beneficial effects of the corticosteroid.

Introduction

• This research was undertaken to study the effects of azithromycin, a type of macrolide, on severe neutrophilic asthma. The study was inspired by the fact that there is highest resistance to steroids in asthma which is mainly associated with neutrophilic inflammation.
• Previous studies reported that adding macrolide therapy to regular treatment can improve the quality of life in challenging asthma cases, with a higher efficiency observed in neutrophilic asthma cases. However, the exact mechanism or process for these macrolide-induced benefits is not yet fully understood.

Objectives

• The objective of the study was to determine whether the inclusion of azithromycin in therapy with inhaled corticosteroids (ICS) can lead to a more significant improvement in lung function, airway inflammation, and bronchial remodeling in severe asthma patients.

Methodology

• The research was conducted as a randomized blind trial for five months where horses with severe neutrophilic asthma were given inhaled fluticasone and azithromycin or fluticasone alone.
• The condition of the horses was gauged based on their lung function, the inflammation in their airways, and bronchial remodeling, which referred to changes in the physical structure of the airways, assessed using histomorphometry of central and peripheral airways and endobronchial ultrasound.

Results

• The results of the trial indicated that the group receiving both azithromycin and inhaled fluticasone had a more substantial reduction in airway neutrophilia, a condition related to neutrophilic asthma. This implies that azithromycin had a positive effect on controlling airway inflammation.
• However, despite the improve control on airway inflammation by azithromycin, no such improvement was observed in terms of lung function or airway smooth muscle mass in either the central or peripheral airway.
• The results suggest that azithromycin did not enhance or potentiate the clinical effects of fluticasone in any aspect other than reducing airway neutrophilia.