NIK inhibitor impairs chronic periodontitis via suppressing non-canonical NF-κB and osteoclastogenesis.

Periodontitis is an inflammatory disease that causes damages to periodontium and alveolar bone. Overactivation and formation of osteoclasts can cause bone destruction, which contributes to periodontitis development. Receptor activator of nuclear factor κB ligand (RANKL)-mediated NF-κB signaling plays an essential role in osteoclasts differentiation. We aimed to study the effects of NIK-SMI1, an NF-κB-inducing kinase (NIK) inhibitor, on the osteoclastogenesis in vitro and periodontitis progression in vivo. A ligature-induced mice model of periodontitis was incorporated to test the potential therapeutic effect of NIK-SMI1 on periodontitis. The target protein and mRNA expression levels were determined by Western blot assay and real-time PCR assay, respectively. We found that the administration of NIK-SMI1 strongly inhibited the RANKL-stimulated non-canonical NF-κB signaling as demonstrated by decreased nuclear p52 expression and activity. Blocking NIK activity also resulted in reduced osteoclasts specific genes expression and enhanced IFN-β expression. NIK-SMI1 treatment resulted in attenuated periodontitis progression and pro-inflammatory cytokines expression in vivo. Our study suggested that NIK-SMI1 exerts beneficial effects on the mitigation of osteoclastogenesis in vitro and periodontitis progression in vivo. Application of NIK-SMI1 may serve as a potential therapeutic approach for periodontitis.