NLRP1 as a Novel Pyroptosis Biomarker in Irreversible Pulpitis: A Laboratory Investigation and Animal Model Study

AIM: Irreversible pulpitis poses a significant clinical burden due to progressive inflammatory pulp damage. While inflammatory mechanisms are central to its pathogenesis, they remain incompletely characterised. This study aims to elucidate the role of Nod-like receptor thermal domain associated protein 1 (NLRP1) in irreversible pulpitis pathogenesis. METHODOLOGY: Transcriptomic analysis of public dataset GSE77459 identified dysregulated pyroptosis-related genes (PRGs), with machine learning prioritising hub genes for experimental validation. Key targets were experimentally verified through an integrated approach: in vitro models using lipopolysaccharide (LPS)-stimulated human dental pulp cells (hDPCs) analysed by qRT-PCR, ELISA and Western blot and specific pyroptosis assays (PI uptake, Caspase-1 cleavage); in vivo rat pulpitis models; and clinically validation with human irreversible pulpitis tissues analysed via H&E staining, immunohistochemistry (IHC) and immunofluorescence (IF). Functional roles were further assessed via NLRP1 knockdown and overexpression in hDPCs. RESULTS: Bioinformatics identified 11 differentially expressed PRGs, with machine learning highlighting six hub genes including unreported NLRP1. Specific pyroptosis assays confirmed that LPS induces membrane pore formation and Caspase-1 activation in hDPCs. Significant post-transcriptional regulation of NLRP1 was demonstrated by pronounced protein upregulation in LPS-stimulated hDPCs despite unaltered mRNA. Functional studies established NLRP1 as a positive regulator, where its knockdown attenuated the LPS-induced inflammatory-pyroptotic response, while its overexpression alone was sufficient to upregulate key mediators. Consistently, elevated NLRP1 expression was observed in rat models and human tissues, where IHC/IF localised prominent expression to inflammatory infiltrates. CONCLUSION: NLRP1 is highlighted as a novel pyroptosis biomarker for irreversible pulpitis, with its dysregulation offering diagnostic value for inflammation. These findings suggest its potential involvement in the inflammatory mechanisms of pulpitis, providing a new molecular target for future therapeutic exploration.