T-helper 17 cells mediate the osteo/odontoclastogenesis induced by excessive orthodontic forces

Department of Orthodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Oral Diseases (Impact Factor: 2.4). 12/2011; 18(4):375-88. DOI: 10.1111/j.1601-0825.2011.01886.x
Source: PubMed

ABSTRACT The aim of this study was to investigate how T-helper 17 cells (Th17 cells), interleukin (IL)-17, and interleukin-6 contribute to root resorption during orthodontic tooth movement.
Fifteen male 6-week-old Wistar rats were subjected to orthodontic force of 10 or 50 g to induce a mesially tipping movement of the upper first molars for 7 days. The expression levels of TRAP, IL-17, the IL-17 receptor (IL-17R), and IL-6 proteins were determined in periodontal ligament (PDL) by immunohistochemical analysis. Moreover, the fluorescent localization immunoassay was performed to detect Th17 cells. Furthermore, the effects of IL-17 on IL-6 release were investigated using human PDL cells in vitro. The effect of IL-17 on osteoclastogenesis was evaluated by TRAP staining, actin ring staining, and the pit formation assay.
The immunoreactivity for Th17, IL-17, IL-17R, and IL-6 was detected in PDL tissue subjected to the orthodontic force on day 7. IL-17 increased the release of IL-6 from human periodontal ligament cells in a time-dependent manner. Moreover, IL-17 stimulated osteoclastogenesis from human osteoclast precursor cells, and these effects were partially suppressed by an anti-IL-6 antibody.
These results suggest that Th17 cells may aggravate the process of orthodontically induced inflammatory root resorption.

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