Effects of nicotine on periodontal ligament fibroblasts apoptosis in vitro

Objectives: The aim of this study was to investigate the effects and the induction of apoptosis of nicotine on periodontal ligament fibroblasts (PDLF) and analyze the expression of Fas-antigen of nicotine on periodontal ligament fibroblasts, so as to further study the pathogenicity of nicotine in periodontal disease. Methods: Human primary periodontal ligament fibroblasts(PDLFs)were cultured in vitro, and the sixth passage cells were used in the experiments. PDLFs were cultured in the presence of nicotine at various concentrations. The growth of cell was measured by MTT method. The apoptosis and the cycle of the cells were examined by flow cytometry. The expression of apoptosis-related protein Fas was analyzed by immunohistochemistry. Results: Proliferation of cell was studied by means of MTT colorimetric method, and nicotine can significantly inhibit periodontal ligament fibroblasts proliferation in a dose- and time- dependent manner. Cell cycle and apoptosis rate assay with flow cytometry showed that nicotine can promote the apoptosis of periodontal ligament fibroblasts. The expression of Fas/Apo-1 (CD95) antigen was positive in PDLFs cultured in the presence of nicotine with immunohistochemical method. Conclusions: 1. Nicotine has toxic effect on PDLFs, and may aggravate the destruction of periodontal ligament during periodontal disease. 2. Nicotine can promote development of periodontal disease by enhancing the apoptosis of the PDLFs. 3. Fas/Apo-1 (CD95) may play a major role in nicotine inducing apoptosis of the periodontal cells.