Nsun2 Knockdown Alleviates Asthma Progression by Inhibiting Hnrnpk Expression Through Decreased 5-Methylcytosine.

INTRODUCTION: Asthma is a chronic inflammatory airway disease. 5-methylcytosine (m5C), an RNA modification, plays an unclear role in asthma pathogenesis. This study aimed to investigate the mechanism of m5C modification in asthma development. METHODS: Ovalbumin (OVA)-challenged BALB/c mice and PDGF-BB-stimulated airway smooth muscle cells (ASMCs) were used as in vivo and in vivo asthma models, respectively. Lung pathology was assessed through hematoxylin-eosin staining, inflammatory cell counts, and cytokine analysis in bronchoalveolar lavage fluid (BALF). Colony formation assays, ELISA, and transwell assays were conducted to evaluate cell proliferation, migration, invasion, and inflammatory responses in ASMCs. Mechanistic studies included methylated RNA immunoprecipitation (MeRIP), RNA immunoprecipitation (RIP), and dual-luciferase reporter assays. RESULTS: The asthma mouse model showed exacerbated lung injury and inflammation, accompanied by increased m5C levels and Nsun2 expression. Nsun2 knockdown suppressed PDGF-BB-induced ASMC proliferation, migration, invasion, and inflammatory responses through reduced Hnrnpk mRNA stability mediated by decreased m5C modification. Hnrnpk overexpression reversed the inhibitory effects of Nsun2 knockdown in PDGF-BB-treated ASMCs. Moreover, Nsun2 knockdown ameliorated airway inflammation and lung injury in asthmatic mice. CONCLUSION: Nsun2 knockdown alleviated asthma by downregulating Hnrnpk expression through m5C-dependent regulation, providing novel mechanistic insights and potential therapeutic targets for asthma.