Protective role of fatty acid oxidation against epithelial barrier dysfunction in allergic asthma

Fatty acid oxidation (FAO) is implicated in lung diseases, but its role in bronchial asthma is not fully understood. We investigated its effect on airway epithelial barrier integrity.

Using a house dust mite (HDM)-induced murine asthma model and HDM, IL-4, IL-13, or TNF-α stimulated human primary bronchial epithelial cells (BECs) and bronchial epithelial (Beas-2b) cells, we modulated FAO with L-carnitine (agonist) and Etomoxir (inhibitor). BECs and Beas-2b cells were infected with lentivirus-mediated CPT1A shRNA prior to stimulation. Barrier function, mitochondrial oxidative stress, inflammation, and metabolism were assessed.

FAO level in lungs negatively correlated with increased inflammation and tissue injury in HDM-induced asthmatic mice (all p < 0.05), while positively regulating tight junction protein expression. In BECs and Beas-2b cells, Etomoxir treatment and CPT1A knockdown exacerbated the impairment of FAO caused by various stimulants (all p < 0.05). Furthermore, FAO negatively regulated HDM/cytokine-induced epithelial barrier damage, hyperactive inflammatory response, and mitochondrial dysfunction in Beas-2b cells (all p < 0.05). In contrast, treatment with L-carnitine significantly alleviated these pathophysiological features in both in vivo and in vitro models.

FAO plays a protective role in the occurrence and development of asthma by maintaining airway epithelial cell homeostasis and barrier function.