METTL14/IGF2BP1 m6A axis promotes pyroptosis in Streptococcus pneumoniae-induced pneumonia by regulating NEK7 mRNA stability.

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.