Effects Of Trichosanthin On Expression Of The MMP-1,MMP-2in Human Periodontal Ligament Cells Mediated By Interleukin-1β

Root resorption is one of the undesirable problems during orthodontic tooth movement, which challenges many orthodontists. Some researches show that orthodontic tooth movement is the process of aseptic inflammation and the aseptic inflammation process is an essential part of the root resorption process. Orthodontic root resorption is known as orthodontically induced inflammatory root resorption (OIIRR). OIIRR may almost be found on all teeth undergoing orthodontic movement. If root resorption is limited on superficial part of the root, the root can repair itself. But if the root resorption further develops, it will be irreversible and cause root shortening or even teeth loosing, which is very unfavorable for orthodontic patients. It has been shown that the1/3apical part of roots in1～5%orthodontic teeth were absorbed completely. The reasons and mechanisms of root resorption is not very clear, but the molecular biological researches about root resorption show that the root resorption process is similar to bone resorption which is known as acidification and demineralization of mineral and degradation of organic compound. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are very important during the degradation of collagen fibers and play an important role in the remodeling of collagen of the periodontal tissue. The expression of MMPs stimulated by the local inflammatory cytokine is upregulated, which may induce bone resorption.In clinic, avoiding heavy force engagement is the main way for orthodontists to prevent root resorption. During orthodontic tooth movement, periodontal tissues secrete inflammatory factors that will inevitably lead to much more expression of MMPs. Therefore, inhibition of MMPs expression induced by inflammatory cytokine may be a way to deal with the OIIRR.Periodontal ligament cells are important target cells of orthodontic force, and can secrete MMPs. The inflammatory factors are increased during OIIRR and further stimulate increased expression of MMPs which may promote collagen degradation. Trichosanthin (TCS) is used to cure various cancers. MMPs play an important role in invasion and metastasis of tumor cells. So, it is suggested that TCS may play a certain role in inhibiting the secretion of MMPs expression. It was shown that TCS can inhibit expression of MMP-1induced by tumor necrosis factor-α (TNF-α) and interleukin-6(IL-6) in human periodontal ligament cells in our previous researching work.This study was aimed to investigate the following things:①the effect of interleukin-1β (IL-1β) on the matrix metalloproteinase-1,2(MMP-1,2) expression in periodontal ligament cells. Then, the mechanism of the high expression of the factors related to root resorption may be analyzed during the root resorption process in periodontal tissue;②The effect of trichosanthin on the expression of matrix metalloproteinase-1,2in human periodontal ligament cells mediated by IL-1β. Then, it may be analyzed whether trichosanthin may inhibit the expression of factors related to root resorption and prevent root resorption.1. Research Contents and Methods(A) Study on the effect of IL-1β on the MMP-1,2expressions in human periodontal ligament cellsHuman periodontal ligament cells (hPDLCs) were incubated with IL-1β in vitro. MTT method was used to detect the hPDLCs growth state influenced by IL-1β. The MMP-1mRNA and protein expression was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The MMP-2mRNA expression was investigated by RT-PCR.(B) TCS interfered in hPDLCs mediated by IL-1β. At that situation, the hPDLCs growth and MMP-1,2expressions were investigated.The effect of the trichosanthin on the hPDLCs growth was investigated by MTT method. By RT-PCR and Western blot, the MMP-1gene and protein expression were detected. By RT-PCR and gelatinase spectrum, the MMP-2gene and protein activity were detected.2. Research results and conclusionsResults:(A) Mediated by IL-1β, the hPDLCs growth was not effected significantly (P>0.05). MMP-1mRNA and protein expression in IL-1β-mediated hPDLCs increased significantly (P<0.05). MMP-2mRNA expression is also increased significantly (P<0.05).(B) For the effect of TCS on hPDLCs mediated by IL-1β, the follows were found:(1) TCS did not effect the growth of hPDLCs statistically (P>0.05).(2) The inhibition effect of TCS was found on the high expression of MMP-1mRNA and MMP-1protein in IL-1β-mediated hPDLCs (P<0.05).(3) The inhibition effect of TCS was found on the high expression of MMP-2mRNA expression and protein activity in IL-1β-mediated hPDLCs (P <0.05).Conclusions:The MMP-1,2expression of hPDLCs could increase induced by IL-1β. Trichosauthin can inhibit the high expression of MMP-1,2of hPDLCs stimulated by IL-1β.