Relaxin Modulates Collagen Type I and Matrix Metalloproteinase-1 Expression by Human Periodontal Ligament Cells

Relaxin, a member of the insulin/relaxin family of structurally related hormones, binds to receptors that are part of the leucine-rich repeat G-protein receptor family (LGR7 and LGR8). Furthermore, it influences many other physiologic processes, such as collagen turnover, angiogenesis, and antifibrosis; therefore, relaxin may also affect orthodontic tooth movement through alterations of the periodontal ligament (PDL), although little is known regarding the relationship between relaxin and human PDL (hPDL) cells. In the present study, we investigated whether hPDL cells contain LGR7 and LGR8, in order to evaluate the effects of relaxin on the expression of collagen typeI (Col-I) and typeIII (Col-III), as well as matrix metalloproteinase 1 (MMP-1) in hPDL cells in vitro. The expressions of LGR7 and LGR8 in hPDL cells were detected using immunocytochemistry and RT-PCR methods. Further, hPDL cells treated with relaxin decreased the release and gene expression of Col-I and increased that of MMP-1 in a dose-dependent manner (p<0.05, one-way ANOVA), whereas the expression of Col-III was not changed. Our results indicated that relaxin modulates collagen metabolism in hPDL cells via the expression of Col-I and MMP-1.