Effects of relaxin on collagen type I released by stretched human periodontal ligament cells

Structured Abstract Authors - Takano M, Yamaguchi M, Nakajima R, Fujita S, Kojima T, Kasai K Objectives - Relapse of teeth that have moved during orthodontic treatment is a major clinical issue with respect to the goals of successful treatment. Such relapse is a physiologic response of the supporting tissues to application of force, and is mainly attributed to occlusal instability and increased mechanical tension exerted by the periodontal ligament (PDL). Relaxin, a member of the insulin/relaxin family of structurally related hormones, has an influence on many physiologic processes, such as collagen turnover, angiogenesis, and antifibrosis. Therefore, relaxin may also affect orthodontic tooth movement through alterations of the PDL, though little is known regarding the relationship between relaxin and stretched human PDL (hPDL) cells. In the present study, we investigated the effects of relaxin on the expression of collagen type I (Col-I) and matrix metalloproteinase 1 (MMP-1) in stretched hPDL cells in vitro. Materials and Methods - The release and gene expression of Col-I, as well as those of MMP-1 in stretched hPDL cells treated with relaxin were investigated using enzyme-linked immunosorbent assay and real-time PCR methods. Results - Relaxin decreased the release and gene expression of Col-I, and increased those of MMP-1 by stretched hPDL cells in a magnitude-dependent manner. Conclusion - Our results indicate that relaxin modulates collagen metabolism in stretched hPDL cells via the release and expression of Col-I and MMP-1. This hormone may be useful to prevent orthodontic relapse following orthodontic treatment.