The promotional effect of IL-22 on mineralization activity of periodontal ligament cells

ObjectivesInterleukin (IL)-22 acts on non-immune cells to induce anti-microbial responses, protection from tissue damage, and enhance cell regeneration. However, little is known about the involvement of IL-22 in periodontal biology. This study investigated the biological effects of IL-22 on periodontal ligament (PDL) cells as part of studies to assess the involvement of IL-22 in periodontal disease.Materials and methodsGene expression levels of IL-22 and its receptors in PDL cells and gingival tissue samples were evaluated by real-time PCR. Proliferative responses and mineralized-matrix forming activities of PDL cells were examined in the presence and absence of IL-22.ResultsIn contrast to the expression of IL-22 receptors detected in PDL tissues and their cell lines, gingival tissues showed modest or no gene expressions of IL-22. The production of several cytokines including IL-11, IL-8 and CCL2 was upregulated by IL-22 treatment of PDL cells in a dose-dependent manner. IL-22 treatment had no effect on the proliferative response in PDL cells. Meanwhile, IL-22 precipitated mineralized nodule formation and induced gene expressions of RUNX2, MSX2 and osteocalcin in PDL cells, suggesting that IL-22 enhances the mineralized matrix-forming activities of PDL cells.ConclusionIL-22 has the potential to promote mineralizing activity in PDL cells and to develop appropriate regenerative therapy.

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► Periodontal ligament (PDL) cells express IL-22 receptors.
► IL-22 induces IL-11, IL-8 and CCL2 gene expression in PDL cells.
► IL-22 enhances mineralized matrix-forming activity in PDL cells.
► IL-22 gene expression is very low in periodontal lesions.
► IL-22 may be an important potential player in regenerative periodontal therapy.