Inflammation Affects the Osteogenic Differentiation of Aged Periodontal Ligament Cells via NF-κB/FOXO3a/c-JUN Signalling

AIM: This study aims to investigate the effect of inflammation on the senescence phenotype and osteogenic capacity of aged periodontal ligament cells (PDLCs), and to explore the regulatory role of the NF-κB signalling pathway in the osteogenesis of aged PDLCs. METHODS: Human PDLCs were isolated, and two ageing models were used: replicative senescence and etoposide treatment. The proliferation and migration of PDLCs were tested with the cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine staining, and scratch test. Proinflammatory cytokine levels were tested using enzyme-linked immunosorbent assay and real time-quantitative polymerase chain reaction. Osteogenic differentiation was evaluated through alkaline phosphatase activity, Alizarin Red S staining, and calcium quantification. Expression levels of nuclear factor kappa-B (NF-κB) and c-JUN pathway-related proteins were analyzed through Western blotting. RESULTS: Inflammatory stimulation enhanced the senescence phenotype in both young and aged PDLCs and inhibited osteogenic differentiation in aged PDLCs. During cellular ageing, NF-κB signalling downregulated the osteogenic differentiation of PDLCs by suppressing forkhead box O3a (FOXO3a) and c-JUN. Conversely, under exogenous inflammatory stimulation, NF-κB signalling inhibited osteogenesis by promoting FOXO3a phosphorylation and increasing c-JUN expression, with p21 exerting a synergistic inhibitory effect on osteogenic differentiation in aged PDLCs. CONCLUSION: Inflammation aggravates cellular senescence and suppresses osteogenic differentiation in aged PDLCs through the NF-κB/FOXO3a/c-JUN signalling pathway.