Regulatory Effects of Bone Morphogenetic Protein‐4 on Tumour Necrosis Factor‐Alpha‐Induced IL‐6 and M‐CSF Expression in Cementoblasts

OBJECTIVE: Orthodontically induced root resorption involves the destruction of cementum, and in severe cases, dentine. Cementoblasts are cells responsible for depositing and mineralizing cementum, and they can also communicate with osteoclasts to indirectly regulate cementum destruction. This study aimed to elucidate the impact of TNF-α on IL-6 and M-CSF, two potent osteoclast-activating cytokines secreted by cementoblasts. Additionally, the study explored the combined effects of BMP-2, BMP-4, BMP-6, BMP-7 and TNF-α. MATERIALS AND METHODS: We utilized the immortalized mouse cementoblast cell line OCCM-30. Cells were incubated with TNF-α, followed by RT-qPCR and ELISA to assess IL-6 and M-CSF expression. Prior to TNF-α stimulation, cells were pre-incubated with inhibitors targeting p38 MAPK, Erk1/2, JNK, PI3K-Akt, or NF-κB pathways, and IL-6 and M-CSF levels were analysed by RT-qPCR. Cells were also treated with combinations of BMP-2, BMP-4, BMP-6, BMP-7 and TNF-α, and their synergistic effects on IL-6 and M-CSF were evaluated by RT-qPCR and ELISA. RESULTS: TNF-α significantly increased both IL-6 and M-CSF mRNA levels, as well as their secreted levels. Blocking the NF-κB pathway partially reversed TNF-α-induced upregulation of IL-6 and M-CSF. BMP-4 and BMP-2 further potentiated TNF-α-induced upregulation of IL-6 and M-CSF, while BMP-6 and BMP-7 had no effect. CONCLUSION: TNF-α increased IL-6 and M-CSF expression in cementoblasts via the NF-κB pathway. BMP-4 and BMP-2 exacerbated the TNF-α-induced effect on IL-6 and M-CSF.