Effects Of P38MAPK Signaling Pathway On Cyclic Stretch-induced Fibroblast Proliferation

Objective:Periodontal disease is one of the two major diseases of mouth, as well as one of the most ancient diseases of humanities, which still possesses a very high incidence over the current world. In China, the incidence of periodontal disease and the extent of harm caused by it are much higher than those of dental caries. It is generally recognized that the number of tooth extraction attributed to periodontitis occupy30percent to40percent of the total tooth extraction number. The cause of periodontitis is an ancient and complicated research area, whose essential mechanism is still obscure, although the scholars around the world have done large amounts of profound research over last century. According to the studies, trauma from occlusion can contribute to the occurrence and development of periodontitis, and make direct impact to the recreating of periodontal tissue. Proper occlusal force can make the major susceptibility and effective cells of periodontal ligament, periodontal ligament fibroblast proliferation, differentiation and apoptosis which have actually participated the recreating of periodontal tissue. With regard to the foundation of human periodontal ligament fibroblasts in vitro-on the basis of the mechanical stimulus model and the detecting technic of CCK-8and RT-PCR, this experience attempts to illustrate the function of P38mapk signal pathway in the process, clarify the relations among cyclic stretch, cell proliferation and p38MAPK, providing new thoughts for further illustration of function of trauma from occlusion in the process of periodontitis, and supplying theoretical evidence for exploring clinical intervention of trauma from occlusion.Methods:In vitro cultured fibroblast for experimental object. Experiment was divided into loading group (Oh,1h,6h,12h and24h) and loading+SB203580group (Oh,12h). The Flexcell Strain Unit FX-4000T was used to expose to fibroblasts equiaxial cyclic stretch of10%magnitude and a frequency of0.1Hz, each cycle including the5-s stretch/5-s relaxation. Cells of proliferation was analyzed by Cell Counting kit-8, RT-PCR detection of the expression of PCNA. This time makes the fibroblast prior to impose cell-specific inhibitor SB203580, and then imposed on the same tensile stress, and then we detected the changes of cell proliferation. The experimental data were analyzed used SPSS17.0Statistical PackageResults:Flow cytometry, RT-PCR results show that the test imposed by10%, cyclical tensile stress can induce proliferation of fibroblasts, and with the extension of time, the proliferation of fibroblast cells also increased, to12hours to reach the peak, and then begin to decline but still higher than the group without tensile stress.(P<0.05) Cells imposed on SB203580before imposing cyclical tensile stress, showed that the expression of PCNA is lower than the same time in the loading group without it.(p<0.05))Conclusions:Fibroblasts by certain force value of mechanical stimulation (the value of the deformation force and frequency) could occur proliferation, and the extent of proliferation s and stimulation of the role of time in a certain range of positive correlation. p38MAPK signaling pathway may be involved in the proliferation process.