SummaryOxidative stress regulates cellular functions in multiple pathological conditions, including bone formation by osteoblastic cells. However, little is known about the cellular mechanisms responsible for the effects of oxidative stress on osteoblast functions in senescence. To clarify the inhibitory effects of oxidative stress on osteoblastic mineralization, we examined the relationship between the antioxidant system and bone formation in MC3T3-E1 cells. After a single exposure to H 2 O 2 within range of a non-toxic concentration for cells, the mineralization level was diminished half. Under the same conditions, gene expression of the transcription factor Nrf2, which regulates antioxidant enzymes, was upregulated. In addition, gene expression for the osteogenic markers Runx2, ALP, and BSP was lower than that in non-treated cells, whereas expression of the osteocalcin gene was up-regulated following H 2 O 2 exposure. These results suggest that reduced mineralization by MC3T3-E1 cells after H 2 O 2 exposure is the result of an up-regulated antioxidant system and altered osteogenic gene expression.
Periodontitis, a complex chronic inflammatory disease caused by subgingival infection, is among the most prevalent microbial diseases in humans. Although traditional microbiological research on periodontitis has focused on putative bacteria such as Porphyromonas gingivalis, the herpes virus is proposed to be involved in the pathogenesis of periodontitis because bacterial etiology alone does not adequately explain various clinical aspects. In this study, we established for the first time, more Epstein–Barr virus (EBV) DNA is found deeper in periodontal pockets of chronic periodontitis in Japanese patients. Subgingival samples were collected from 85 patients with chronic periodontitis having two periodontal sites with probing depths (PD) of ≤3 mm (shallow) or ≥5 mm (deep) and were subjected to a nested polymerase chain reaction. EBV DNA was more frequently detected in patients with deeper PD sites (66%) than in those with shallow PD sites (48%) or healthy controls (45%). Coexistence of EBV DNA and P. gingivalis was significantly higher in patients with deeper PD sites (40%) than in those with shallow PD sites (14%) or healthy controls (13%). Although no difference in clinical index for periodontitis, the odds ratio of EBV DNA in patients with deeper PD sites was 2.36, which was 2.07-fold higher than that in those with shallow PD sites. Interestingly, the odds of acquiring chronic periodontitis (PD ≥5 mm) were higher in the presence of both EBV DNA and P. gingivalis compared with either EBV DNA or P. gingivalis only. In addition, we also observed that EBV-encoded small RNA (EBER) in positive cells of human gingival tissues. These results would suggest that EBV DNA may serve as a pathogenic factor leading to chronic periodontitis among Japanese patients.
Periodontitis is a chronic inflammatory disease caused by specific bacteria and viruses. Local, systemic, and environmental factors affect the rate of disease progression. Immune responses to bacterial products, and the subsequent production of inflammatory cytokines, are crucial in the destruction of periodontal tissue. MicroRNAs (miRNAs) are a class of small RNAs that control various cell processes by negatively regulating protein-coding genes. In this study, we compared miRNA expression in inflamed and noninflamed gingival tissues from Japanese dental patients. Total RNAs were isolated from inflamed and noninflamed gingival tissues. miRNA expression profiles were examined by an miRNA microarray, and the data were analyzed by GeneSpring GX, Ingenuity Pathways Analysis, and the TargetScan databases. Observed miRNA expression levels in inflamed gingiva were confirmed by real-time PCR. The three most overexpressed (by >2.72-fold) miRNAs were hsa-miR-150, hsa-miR-223, and hsa-miR-200b, and the three most underexpressed (by <0.39-fold) miRNAs were hsa-miR-379, hsa-miR-199a-5p, and hsa-miR-214. In IPA analysis, hsa-miR-150, hsa-miR-223, and hsa-miR-200b were associated with inflammatory disease, organismal injury, abnormalities, urological disease, and cancer.
Bone sialoprotein protects cells from complement-mediated cellular lysis, activates matrix metalloproteinase 2 and has an angiogenic capacity. Therefore, regulation of the bone sialoprotein gene is potentially important in the differentiation of osteoblasts, bone matrix mineralization and tumor metastasis. This review highlights the function and transcriptional regulation of bone sialoprotein.
We investigated the efficacy, safety, and clinical significance of trafermin, a recombinant human fibroblast growth factor (rhFGF)‐2, for periodontal regeneration in intrabony defects in Phase III trials. Study A, a multicenter, randomized, double‐blind, placebo‐controlled study, was conducted at 24 centers. Patients with periodontitis with 4‐mm and 3‐mm or deeper probing pocket depth and intrabony defects, respectively, were included. A total of 328 patients were randomly assigned (2:1) to receive 0.3% rhFGF‐2 or placebo, and 323 patients received the assigned investigational drug during flap surgery. One of the co‐primary endpoints, the percentage of bone fill at 36 weeks after drug administration, was significantly greater in the rhFGF‐2 group at 37.131% (95% confidence interval [CI], 32.7502 to 41.5123; n = 208) than it was in the placebo group at 21.579% (95% CI, 16.3571 to 26.8011; n = 100; p < 0.001). The other endpoint, the clinical attachment level regained at 36 weeks, was not significantly different between groups. Study B, a multicenter, randomized, blinded (patients and evaluators of radiographs), and active‐controlled study was conducted at 15 centers to clarify the clinical significance of rhFGF‐2. Patients with 6‐mm and 4‐mm or deeper probing pocket depth and intrabony defects, respectively, were included. A total of 274 patients were randomly assigned (5:5:2) to receive rhFGF‐2, enamel matrix derivative (EMD), or flap surgery alone. A total of 267 patients received the assigned treatment during flap surgery. The primary endpoint, the linear alveolar bone growth at 36 weeks, was 1.927 mm (95% CI, 1.6615 to 2.1920; n = 108) in the rhFGF‐2 group and 1.359 mm (95% CI, 1.0683 to 1.6495; n = 109) in the EMD group, showing non‐inferiority (a prespecified margin of 0.3 mm) and superiority of rhFGF‐2 to EMD. Safety problems were not identified in either study. Therefore, trafermin is an effective and safe treatment for periodontal regeneration in intrabony defect, and its efficacy was superior in rhFGF‐2 compared to EMD treatments. © 2015 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).
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