MiR-491-5p Targets B4GalT5 to Alleviate Airway Inflammation and Remodeling in Asthma by Regulating Pulmonary Oxidative Stress.

Background: MicroRNA-491-5p (miR-491-5p) is a key regulator of cell proliferation and inflammation, but its role in asthma pathogenesis remains unclear. This study aimed to investigate the mechanistic involvement of miR-491-5p in airway remodeling and inflammation, focusing on its downstream target, B4GalT5, and oxidative stress pathways. Methods: MicroRNA sequencing of airway smooth muscle (ASM) tissues from asthma patients revealed significant downregulation of miR-491-5p, and bioinformatic prediction combined with dual-luciferase reporter assays identified B4GalT5 as a direct downstream target. Clinical correlation analyses assessed the relationship between B4GalT5 expression, Ki-67 (a marker of cell proliferation), and percentage of airway wall area to total tracheal area (WA%). To explore the functional role of miR-491-5p, an ovalbumin (OVA)-induced asthma model was established in C57BL/6 mice, followed by intratracheal instillation of AAV-miR-491-5p to restore its expression in vivo. Airway inflammation and remodeling were evaluated using ELISA, and histological staining (HE, Masson and PAS staining). Oxidative stress markers, including reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and adenosine triphosphate (ATP), were also quantified. In vitro, airway smooth muscle cells (ASMCs) were stimulated with TNF-α to mimic the inflammatory microenvironment and then transfected with a miR-491-5p mimic to assess effects on cell proliferation, cytokine secretion, mitochondrial morphology, ROS production, and Ca Results: MiR-491-5p was significantly downregulated in ASM tissues from asthma patients. B4GalT5 was identified and validated as a direct target of miR-491-5p. Clinically, B4GalT5 expression was positively correlated with Ki-67 and WA%, suggesting a role in airway remodeling. In the OVA-induced asthma model, miR-491-5p overexpression markedly alleviated airway inflammation, mucus hypersecretion, collagen deposition, and structure remodeling, accompanied by reduced oxidative stress (decreased ROS and MDA, increased SOD activity and ATP levels). In TNF-α-stimulated ASMCs, miR-491-5p mimic suppressed excessive proliferation, cytokine release, mitochondrial dysfunction, ROS elevation and intracellular Ca²⁺ homeostasis. Mechanistic studies confirmed that miR-491-5p directly binds to the 3'-UTR of B4GalT5, inhibiting its expression and downstream oxidative stress pathways. Conclusion: These findings demonstrate that miR-491-5p attenuates asthma-related airway remodeling and inflammation by targeting B4GalT5 and modulating oxidative stress, providing a novel target for therapeutic intervention.