FGF-2 stimulates periodontal regeneration: results of a multi-center randomized clinical trial.

The efficacy of the local application of recombinant human fibroblast growth factor-2 (FGF-2) in periodontal regeneration has been investigated. In this study, a randomized, double-blind, placebo-controlled clinical trial was conducted in 253 adult patients with periodontitis. Modified Widman periodontal surgery was performed, during which 200 µL of the investigational formulation containing 0% (vehicle alone), 0.2%, 0.3%, or 0.4% FGF-2 was administered to 2- or 3-walled vertical bone defects. Each dose of FGF-2 showed significant superiority over vehicle alone (p < 0.01) for the percentage of bone fill at 36 wks after administration, and the percentage peaked in the 0.3% FGF-2 group. No significant differences among groups were observed in clinical attachment regained, scoring approximately 2 mm. No clinical safety problems, including an abnormal increase in alveolar bone or ankylosis, were identified. These results strongly suggest that topical application of FGF-2 can be efficacious in the regeneration of human periodontal tissue that has been destroyed by periodontitis.

Oxidative stress causes alveolar bone loss in metabolic syndrome model mice with type 2 diabetes.

BACKGROUND AND OBJECTIVE: Alveolar bone loss is caused by a host response to periodontal pathogens, and its progression is often enhanced by systemic conditions such as insulin resistance. Alveolar bone dehiscence has been observed in KK-A(y) mice, which are metabolic syndrome model mice with type 2 diabetes. The aim of this study was to investigate inducements responsible for alveolar bone dehiscence in the KK-A(y) mice. MATERIAL AND METHODS: The expression of endothelial nitric oxide synthase in the mandibles of mice was detected using immunohistochemical staining and the reverse transcription-polymerase chain reaction. After administration of N-acetylcysteine, an antioxidant, to KK-A(y) mice, alveolar bone loss and the expression of endothelial nitric oxide synthase protein in gingival keratinocytes and of hydrogen peroxide concentrations in plasma, were analyzed. The effect of hydrogen peroxide on endothelial nitric oxide synthase expression in keratinocytes was examined using cultured keratinocytes. RESULTS: The expression of endothelial nitric oxide synthase was decreased in gingival keratinocytes from KK-A(y) mice compared with gingival keratinocytes from control mice. Administration of N-acetylcysteine to the mice restored endothelial nitric oxide synthase expression in the gingival keratinocytes, suppressed the alveolar bone loss and decreased the hydrogen peroxide concentrations in plasma without the improvement of obesity or diabetes. In vitro, stimulation with hydrogen peroxide decreased the expression level of endothelial nitric oxide synthase in cultured keratinocytes, which was restored by the addition of N-acetylcysteine. CONCLUSION: Reactive oxygen species, such as hydrogen peroxide, are responsible for the alveolar bone loss accompanied by decreased endothelial nitric oxide synthase expression in KK-A(y) mice. Therefore, we propose a working hypothesis that the generation of oxidative stress is an underlying systemic condition that enhances alveolar bone loss in periodontitis occurring as a complication of diabetes.

Hydrogen sulfide inhibits cell proliferation and induces cell cycle arrest via an elevated p21 Cip1 level in Ca9-22 cells.

BACKGROUND AND OBJECTIVE: Volatile sulfur compounds such as hydrogen sulfide (H(2)S) and methyl mercaptan (CH(3)SH) are the main causes of oral mal odor. However, the physiological functions of H(2)S have not been investigated in oral tissues. The aim of this study was to evaluate the effect of H(2)S on cell proliferation and the cell cycle in oral epithelial-like cells. MATERIAL AND METHODS: Ca9-22 cells were used in this study. Cells were cultured in 5% CO(2)/95% air with (5 or 10 ng/mL) or without H(2)S. DNA synthesis was measured using a 5-bromo-2-deoxyuridine enzyme-linked immunosorbent assay. The cell cycle was analyzed using a flow cytometer. The expressions of phosphorylated retinoblastoma protein (Rb), p21(Cip1) and p27(Kip1) were evaluated by western blotting. RESULTS: Exposure to 5 and 10 ng/mL of H(2)S significantly decreased DNA synthesis (p < 0.05). Cell cycle analysis also showed that exposure to both concentrations of H(2)S significantly increased the proportion of cells in G(1) phase (p < 0.001) and significantly decreased the proportion of cells in S phase (p < 0.01). Western blotting showed that Rb phosphorylation was reduced and p21(Cip1) was enhanced by exposure to H(2)S. CONCLUSION: The results indicated that H(2)S inhibits cell proliferation and induces cell cycle arrest via the expression of p21(Cip1) in Ca9-22 cells.

Arginine-specific gingipains from Porphyromonas gingivalis deprive protective functions of secretory leucocyte protease inhibitor in periodontal tissue.

Chronic periodontitis is correlated with Porphyromonas gingivalis infection. In this study, we found that the expression of secretory leucocyte protease inhibitor (SLPI), an endogenous inhibitor for neutrophil-derived proteases, was reduced in gingival tissues with chronic periodontitis associated with P. gingivalis infection. The addition of vesicles of P. gingivalis decreased the amount of SLPI in the media of primary human gingival keratinocytes compared to untreated cultures. We therefore investigated how arginine-specific gingipains (Rgps) affect the functions of SLPI, because Rgps are the major virulence factors in the vesicles and cleave a wide range of in-host proteins. We found that Rgps digest SLPI in vitro, suppressing the release of SLPI. Rgps proteolysis of SLPI disrupted SLPI functions, which normally suppresses neutrophil elastase and neutralizes pro-inflammatory effects of bacterial cell wall compounds in cultured human gingival fibroblasts. The protease inhibitory action of SLPI was not exerted towards Rgps. These results suggest that Rgps reduce the protective effects of SLPI on neutrophil proteases and bacterial proinflammatory compounds, by which disease in gingival tissue may be accelerated at the sites with P. gingivalis infection.

The effects of methyl mercaptan on epithelial cell growth and proliferation.

AIM: Previous studies have demonstrated that methyl mercaptan (CH3SH), one of the main causes of oral malodour, might contribute to the initiation and progression of periodontal disease. These studies suggested that CH3SH may affect the epithelial cells of the gingival crevice, which form a barrier to the penetration of microbial substances. In this study, the effects of CH3SH on the epithelial cells and gingival fibroblasts were investigated. METHOD: Human oral epithelial carcinoma cell line (KB), human oral squamous cell carcinoma cell line (HSC-2), and human gingival fibroblasts (HGF) derived from healthy gingiva were used in this study. These cells were cultured in conditions of 5% CO2/95% air with or without CH3SH (10 ng/ml or 50 ng/ml) for 5 days. Cell numbers, proliferation and cytotoxicity were evaluated. RESULTS: CH3SH inhibited epithelial cell growth and proliferation at the concentration of 50 ng/ml, and a cytotoxic effect of CH3SH was also noted. On the other hand, HGF cells were not affected by 50 ng/ml CH3SH. CONCLUSION: High concentrations of CH3SH such as 50 ng/ml have an inhibitory effect on the growth and proliferation of epithelial cells, but not on those of fibroblasts.