Relaxin Modulates Collagen and MMP-1 Expression in Human PDL cells

Objectives: Relaxin is a hormone in the insulin/relaxin family of structurally related hormones. It has been shown to bind to receptors that are part of the leucine rich repeat G-protein receptor family (LGR7 and LGR8). Furthermore, relaxin influences many other physiologic processes such as collagen turnover, angiogenesis, and antifibrosis. Therefore, relaxin might influence orthodontic tooth movement through alterations of the periodontal ligament (PDL). However, very little is known the relationship between relaxin and human PDL (hPDL) cells. Therefore, our purposes of this study were to determine whether there are LGR7 and LGR8 in hPDL cells, and to evaluate the effects of relaxin on collagen type I (Col-I), Col-Ⅲ and matrix metalloproteinase 1(MMP-1) expressions in hPDL cells in vitro.

Methods: The expressions of LGR7 and LGR8 in hPDL cells were investigated by immunohistochemistry and RT-PCR. Further, to examine the effects of relaxin on hPDL cells, relaxin (1ng/ml to 1µg /ml) was added to the cell culture media for 48 hours. The gene expressions of Col-I, Col-Ⅲ and MMP-1 were determined by real-time PCR.

Results: The expressions of LGR7 and LGR8 were detected in hPDL cells by RT-PCR and immunocytochemistry. Relaxin decreased the gene expression of Col-I and increased that of MMP-1 from hPDL cells in a dose-dependent manner (p<0.05, by one-way ANOVA). The expression of Col-Ⅲ was not changed.

Conclusion: Relaxin may modulate the collagen metabolism via the expressions of Col-Ⅰ and MMP-1 in hPDL cells.

This research was supported in part by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science(C:18592252, C:19592367).