Propolis effects inflammatory cytokine expression in pulp cells and osteoclasts

To effectively inhibit bone resorption and prevent failure of endodontically treated teeth, an ideal intracanal medicament would decrease inflammation along with osteoclast-mediated bone resorption. Bacterial components such as lipopolysaccharides (LPS) are implicated in the development of pulpal and periapical inflammation as well as induce osteoclastogenesis. Propolis is a natural, non-toxic substance collected from bee's wax that has been used for many years in folk medicine. Propolis has been demonstrated to have antibacterial properities along with anti-inflammatory affects on macrophages. In addition, our previous studies have shown that propolis inhibits osteoclast maturation. However, the effect of propolis on the inflammatory response of pulp cells and osteoclasts function has yet to be explored. Objectives: The purpose of this study was to evaluate whether propolis alters the inflammatory response of four endodontically-relevant cell lines: mouse odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD-21), macrophages (RAW264.7), and osteoclasts. Methods: Cells were cultured in Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal bovine serum, penicillin/streptomycin. Osteoclasts were treated with 100 ng/ml RANKL. Cells were exposed to 0-20 ug/ml LPS, to induce an inflammatory response, in the presence of propolis or vehicle control. Culture supernatants were collected and used to quantify expression of multiple soluble mediators using Luminex® technology. Results: Propolis had no effect on the baseline expression of most inflammatory cytokines measured. However, propolis was effective in reducing the secretion of LPS induced inflammatory cytokines in pulp cells and osteoclasts. Conclusion: Our results suggest that propolis suppresses the inflammatory response of key cells within the canal allowing it to be used as an anti-inflammatory intracanal medicament in endodontics.