Abstract

Streptococcus pneumoniae (S. pneumoniae) infection induces pyroptosis in human pulmonary artery epithelial cells (HPAEpiCs), which contributes to pneumonia pathogenesis. We aimed to investigate the regulatory role of N6-methyladenosine (m6A) modification mediated by methyltransferase-like (METTL) 14 in this process and elucidate the underlying molecular mechanisms. HPAEpiCs were infected with S. pneumoniae. Cell viability was assessed using the cell counting kit-8 assay, while cytokine concentrations were measured by enzyme-linked immunosorbent assay. Pyroptosis levels were analyzed through flow cytometry and Western blot for pyroptotic protein expression. Gene expression profiles, protein-RNA interactions, and m6A methylation sites were characterized by quantitative reverse transcription-polymerase chain reaction, RNA immunoprecipitation, and dual-luciferase reporter assays. In vivo experiments involved intranasal administration of S. pneumoniae in mice to evaluate pulmonary pathological changes. S. pneumoniae D39-infected HPAEpiCs exhibited enhanced pyroptosis and adhesive/invasive capabilities, accompanied by elevated m6A modification mediated by METTL14. In addition, METTL14 inhibition suppressed pyroptosis and adhesive/invasive capabilities and ameliorated S. pneumoniae D39-induced lung injury. Notably, NEK7 overexpression reversed the pyroptosis reduction caused by METTL14 knockout. Mechanistically, the METTL14/insulin-like growth factor 2 mRNA-binding proteins (IGF2BP)1 m6A regulatory axis modulated NEK7 mRNA stability through m6A-dependent post-transcriptional regulation. The METTL14/IGF2BP1 m6A regulatory axis promoted S. pneumoniae D39-induced pyroptosis by stabilizing NEK7 mRNA transcripts. Targeting this m6A regulatory pathway represents a potential therapeutic strategy for managing S. pneumoniae D39-induced pneumonia.