Molecular mechanism of NF-κB-mediated transcriptional activation of MMP12 in lipopolysaccharide-stimulated human dental pulp stem cells

Objectives: To investigate the molecular mechanisms through which matrix metalloprotein (MMP)12 exacerbates inflammation in pulpitis and to explore a potential regulatory axis between lipopolysaccharide (LPS)-induced MMP12 expression and activation of the nuclear factor-κB (NF-κB) signaling pathway.

Methods: An inflammatory pulpitis model was established using LPS-stimulated human dental pulp stem cells (hDPSCs). Transcriptomic profiling was conducted to identify differentially expressed genes between physiological and inflammatory states via RNA Sequencing, with validation performed using quantitative Real-Time PCR (qPCR). The regulatory influence of the NF-κB pathway on MMP12 and cytokine expression was examined through western blotting and qPCR. In addition, dual-luciferase reporter assays were employed to confirm NF-κB binding motifs within the MMP12 promoter region.

Results: Treatment with LPS (1 μg/mL) triggered inflammatory activation in hDPSCs. Six pulpitis-associated genes, MMP12, IL6, IL8, IL10, IL1β, and TNF-α, were significantly upregulated (P < 0.05). Inhibition of NF-κB markedly reduced MMP12 expression. Moreover, NF-κB was found to transcriptionally activate the MMP12 promoter through binding motifs located at positions -1590/-1600 bp upstream, thereby establishing an NF-κB/MMP12 signaling axis.

Conclusion: The NF-κB/MMP12 axis functions as a critical amplifier of inflammation in pulpitis. The data shows that MMP12 is a major mediator of pulp tissue destruction and represents a potential therapeutic target, highlighting a coordinated mechanism underlying disease progression.

Dental pulp stem cells; Matrix metalloproteinase-12; Nuclear factor-κB; Pulpitis.