Objective To study the effects of different concentration of interleukin(IL)-17 on the expression of receptor activator of nuclear factor-κB ligand (RANKL) and osteoprogeterin (OPG) in human periodontal ligament fibroblasts (HPDLF) and explore the relationship between IL-17 and orthodontic root resorption.Methods HPDLF cell line was established through the tissue pieces culture method in vitro.HPDLF were stimulated by IL-17 with five different concentrations(0,5,10,20,40 ng/mL) for 24 h.The expression level of mRNA and protein of RANKL and OPG in HPDLF were detected by RT-PCR and ELISA,respectively.Results HPDLF expressed RANKL and OPG in 0 ng/mL group.The expression amount of mRNA and protein of RANKL in HPDLF was positive correlation with the concentration of IL-17 in 0 to 20 ng/mL group.The expression amount of mRNA and protein of OPG was negative correlation with the concentration of IL-17 in 5 to 20 ng/mL group.The ralative RANKL/OPG ratio of mRNA and protein were positive correlation with the concentration of IL-17 in 0 to 20 ng/mL group.Conclusion HPDLF expresses RANKL and OPG in the absence of IL-17.IL-17 enhances the expression of RANKL and inhibits the expression of OPG in HPDLF.

BACKGROUND: p38 MAPK pathway has been shown to play an important role in the synthesis of inflammatory factors, but the relationship between p38 MAPK signaling pathway and interleukin 17, interleukin 6 and other inflammatory factors in periodontal ligament fibroblasts during orthodontic tooth movement is little reported. OBJECTIVE: To investigate the relationship of the expression of inflammatory cytokines interleukin 17 and interleukin 6 with p38 MAPK in human periodontal ligament fibroblasts under continuous static pressure, and to explore the effect of p38 MAPK signaling pathway on the expression of interleukin 17 and interleukin 6. METHODS: The periodontal tissues of fresh first and second premolars were obtained from the removed teeth of the orthodontic patients aged 11-15 years (informed consent had been obtained). Periodontal ligament fibroblasts were cultured in vitro, and the cell model loaded with gravity was established. Cell culture plates were loaded with 0, 1, 2 and 4 g/cm2 pressure for 5, 15, 30 and 60 minutes, respectively. The expression of p38 MAPK protein was detected. The passage 4 cells were seeded, and then randomized into six groups: blank, dimethyl sulfoxide, inhibitor (p38 MAPK blocker, SB203580), loading, loading plus dimethyl sulfoxide, and loading plus inhibitor groups. The intervention lasted for 60 minutes. The interleukin 17 and interleukin 6 protein and mRNA levels in periodontal ligament fibroblasts after loaded with 4 g/cm2 force were detected by RT-PCR and ELISA. RESULTS and CONCLUSION: (1) The expression level of p38 MAPK protein in the 2 and 4 g/cm2 groups was increased with time prolonged, peaked at 30 minutes, and began to decrease at 60 minutes. (2) Compared with the groups without loading, the loading groups showed an increase in the expression levels of interleukin 17 and interleukin 6. The expression level of interleukin 6 in the inhibitor group was down-regulated, and the expression level of interleukin 17 showed no significant difference. (3) To conclude, static pressure can promote human periodontal ligament fibroblasts to secrete interleukin 17 and interleukin 6. Interleukin 6 secretion may be related to p38 MAPK signaling pathway. However, there is insufficient evidence to demonstrate that p38 MAPK signaling pathway is involved in periodontal ligament fibroblasts inducing interleukin 17 expression under static pressure.