Background: Periodontitis and orthodontic treatment can lead to inflammatory root resorption (IRR) through an unclear mechanism. Chemerin, a novel chemoattractant protein, is closely associated with inflammation, affects osteoblast and osteoclast differentiation, and may play a role in IRR. We aimed to explore possible roles of the chemerin/ChemR23 interaction in cementoblast function and IRR and reveal a new IRR therapeutic target.
Methods: Cementoblast function-related gene and protein expression in the immortalized murine cementoblast cell line OCCM-30 after treatment with chemerin and siChemR23 was examined by qRT-PCR and Western blotting. The roles of the MAPK and PI3K-Akt signaling pathways were studied using specific inhibitors. Cementoblast cytokine production under different treatment conditions was measured by enzyme-linked immunosorbent assay and qRT-PCR. Additionally, we modeled IRR in wild-type and chemerin-overexpressing mice and injected transgenic mice with anti-ChemR23 antibody to block ChemR23. We then calculated the root resorption volume and examined periodontal tissue cathepsin K, Runx2, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) expression.
Result: Chemerin suppressed cementoblast differentiation and mineralization and exerted a proinflammatory effect on cementoblasts. These effects were partially reversed by siChemR23 and reversed to different extents by p38, Erk1/2 and PI3K-Akt pathway inhibition, suggesting p38, Erk1/2 and PI3K-Akt pathways as signaling pathways downstream of chemerin/ChemR23. In vivo, chemerin overexpression worsened IRR. Moreover, chemerin expression was positively correlated with TNF-α, IL-6, and cathepsin K expression and negatively correlated with Runx2 expression. ChemR23 downregulation reversed these effects.
Conclusion: Chemerin/ChemR23 induced TNF-α and IL-6 expression dependent on Erk1/2, p38 MAPK, and PI3K-Akt signaling pathway activation, thereby regulating cementoblast function and affecting IRR.
Keywords: cementum; cytokine(s); gene regulation; inflammation and innate immunity.
© 2020 American Academy of Periodontology.