Formoterol, the Most Effective Bronchodilator, Has No Anti-Inflammatory nor Metabolic Modulatory Effects in Severe Asthma Induced by <i>Aspergillus fumigatus</i>

In an increasing number of asthma studies, modulation of pulmonary metabolic reprogramming using therapeutic agents targeting metabolic enzymes promoted bronchodilatory, anti-inflammatory, and antiremodeling effects. Although formoterol is the bronchodilator of choice for asthma management, its anti-inflammatory and metabolic modulatory effects in severe asthma have not been investigated. The present study aimed to explore formoterol's anti-inflammatory and metabolic modulatory potential in Aspergillus fumigatus (Af)-induced severe asthma model to establish additional benefits in the difficult-to-treat severe asthma subtype. Formoterol was administered via nebulization in an Af-induced severe asthma mouse model. Airway hyperresponsiveness (AHR), airway inflammation, airway remodeling, and metabolic pathways on glycolysis and oxidative phosphorylation in the lungs were assessed. An in-depth analysis of formoterol's effect on airway smooth muscle metabolism was also performed. Inhaled formoterol significantly inhibited methacholine-induced AHR in Af-induced severe asthma in a dose-dependent manner (<i>p</i> < 0.001). However, it did not reduce airway immune cell counts, inflammation score of hematoxylin and eosin-stained lung sections, airway mucus hypersecretion, lung levels of proinflammatory cytokines and chemokines, and α-smooth muscle actin-positive airway smooth muscle wall thickness. In addition, formoterol did not show any effects on lung single-cell glycolytic and oxidative phosphorylation activities or on the levels of metabolic enzymes in lung tissues and α-smooth muscle actin-positive airway smooth muscle in Af-induced severe asthma. Inhaled formoterol is an entirely potent and effective bronchodilator against Af-induced severe asthma, with no effect on airway inflammation, airway remodeling, and pulmonary metabolism.