ウサギヒアルロン酸合成酵素(Hyaluronic acid synthase; HAS)遺伝子のクローニングおよびその発現様式の解析

広島大学(Hiroshima University)博士(歯学)Dentistrydoctora

Effects of Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) Laser Irradiation on Bone Metabolism During Tooth Movement

Introduction: The aim of this study is to evaluate the effects of low-level neodymium-doped yttrium aluminium garnet (Nd:YAG) laser irradiation on orthodontic tooth movement and histological examination.Methods: Eleven male Wistar rats (aged 10 weeks) were included. To produce experimental tooth movement in rats, 10 g force was applied to maxillary first molars with nickel titanium closed coil springs. Right molars were irradiated with Nd:YAG laser on days 0, 1, 2, 3, 7, 10, 14, 17, 21 and 24, while un-irradiated left molars were used as control. Distance between mesial side of second molar and distal side of first molar was measured on μCT image during tooth movement and the rats were sacrificed 4 weeks after the initiation of tooth movement.Results: The amount of tooth movement was significantly greater in the irradiation group (0.20 ± 0.06) than in the control group (0.14 ± 0.03) during the first week (P < 0.05). However, no statistically significant difference was found afterwards. There was a tendency of higher tartrate-resistant acid phosphatase (TRAP)-positive nuclei count in the pressure zones of the laser irradiation group, but it was not statistically significant. In immuno-histological examination, expressions of alkaline phosphatase (ALP) and receptor activator of nuclear factor kappa-B ligand (RANKL) were higher at the pressure site of the laser irradiation group than the control group, whereas there was no difference in osteoprotegerin (OPG) expression.Conclusion: The results suggest that low-level Nd:YAG laser may stimulate osteoclast and osteoblast activation and accelerate bone metabolism during tooth movement

Bone Regeneration in Artificial Jaw Cleft by Use of Carbonated Hydroxyapatite Particles and Mesenchymal Stem Cells Derived from Iliac Bone

Objectives of the Study. Cleft lip and palate (CLP) is a prevalent congenital anomaly in the orofacial region. Autogenous iliac bone grafting has been frequently employed for the closure of bone defects at the jaw cleft site. Since the related surgical procedures are quite invasive for patients, it is of great importance to develop a new less invasive technique. The aim of this study was to examine bone regeneration with mesenchyme stem cells (MSCs) for the treatment of bone defect in artificially created jaw cleft in dogs. Materials and Methods. A bone defect was prepared bilaterally in the upper incisor regions of beagle dogs. MSCs derived from iliac bone marrow were cultured and transplanted with carbonated hydroxyapatite (CAP) particles into the bone defect area. The bone regeneration was evaluated by standardized occlusal X-ray examination and histological observation. Results. Six months after the transplantation, perfect closure of the jaw cleft was achieved on the experimental side. The X-ray and histological examination revealed that the regenerated bone on the experimental side was almost equivalent to the original bone adjoining the jaw cleft. Conclusion. It was suggested that the application of MSCs with CAP particles can become a new treatment modality for bone regeneration for CLP patients

Study of Alveolar Bone Remodeling Using Deciduous Tooth Stem Cells and Hydroxyapatite by Vascular Endothelial Growth Factor Enhancement and Inhibition of Matrix Metalloproteinase-8 Expression in vivo

Background: Periodontitis progression is characterized by alveolar bone loss, and its prevention is a major clinical problem in periodontal disease management. Matrix metalloproteinase-8 (MMP-8) has been shown to adequately monitor the treatment of chronic periodontitis patients as gingival crevicular fluid MMP-8s were positively associated with the severity of periodontal disease. Moreover, modulating the vascular endothelial growth factor (VEGF) levels in bones could be a good way to improve bone regeneration and cure periodontitis as VEGF promotes endothelial cell proliferation, proteolytic enzyme release, chemotaxis, and migration; all of which are required for angiogenesis. Purpose: The aim of this study was to determine the effect of hydroxyapatite incorporated with stem cells from exfoliated deciduous teeth (SHED) in Wistar rats’ initial alveolar bone remodeling based on the findings of MMP-8 and VEGF expressions. Methods: A hydroxyapatite scaffold (HAS) in conjunction with SHED was transplanted into animal models with alveolar mandibular defects. A total of 10 Wistar rats (Rattus norvegicus) were divided into two groups: HAS and HAS + SHED. Immunohistochemistry staining was performed after 7 days to facilitate the examination of MMP-8 and VEGF expressions. Results: The independent t-test found significant downregulation of MMP-8 and upregulation VEGF expressions in groups transplanted with HAS in conjunction with SHED compared with the HAS group (p < 0.05). Conclusion: The combination of SHED with HAS on alveolar bone defects may contribute to initial alveolar bone remodeling as evident through the assessments of MMP-8 and VEGF expressions

The matrix vesicle cargo miR-125b accumulates in the bone matrix, inhibiting bone resorption in mice

Communication between osteoblasts and osteoclasts plays a key role in bone metabolism. We describe here an unexpected role for matrix vesicles (MVs), which bud from boneforming osteoblasts and have a well-established role in initiation of bone mineralization, in osteoclastogenesis. We show that the MV cargo miR-125b accumulates in the bone matrix, with increased accumulation in transgenic (Tg) mice overexpressing miR-125b in osteoblasts. Bone formation and osteoblasts in Tg mice are normal, but the number of bone-resorbing osteoclasts is reduced, leading to higher trabecular bone mass. miR-125b in the bone matrix targets and degrades Prdm1, a transcriptional repressor of anti-osteoclastogenic factors, in osteoclast precursors. Overexpressing miR-125b in osteoblasts abrogates bone loss in different mouse models. Our results show that the MV cargo miR-125b is a regulatory element of osteoblast-osteoclast communication, and that bone matrix provides extracellular storage of miR-125b that is functionally active in bone resorption.T.M. and Y.T. were supported in part by MEXT KAKENHI (JP16K11443, T.M.; JP26861548, Y.T.). Y.Y. was supported by MEXT KAKENHI (JP18K19647), the Raffinee International Foundation and the Ono Pharmaceutical Foundation.Supplementary information is available for this paper at https://doi.org/10.1038/s42003-020-0754-2

キサンチンオキシダーゼ阻害薬febuxostatはNrf2を活性化し脂肪細胞分化を抑制する

Xanthine oxidoreductase (XOR) is a rate-limiting enzyme in purine catabolism that acts as a novel regulator of adipogenesis. In pathological states, xanthine oxidoreductase activity increases to produce excess reactive oxygen species (ROS). The nuclear factor erythroid 2-related factor 2 (Nrf2) is a critical inducer of antioxidants, which is bound and repressed by a kelch-like ECH-associated protein 1 (Keap1) in the cytoplasm. The Keap1-Nrf2 axis appears to be a major mechanism for robust inducible antioxidant defenses. Here, we demonstrate that febuxostat, a xanthine oxidase inhibitor, alleviates the increase in adipose tissue mass in obese mouse models with a high-fat diet or ovariectomy. Febuxostat disrupts in vitro adipocytic differentiation in adipogenic media. Adipocytes appeared at day 7 in absence or presence of febuxostat were 160.8 ± 21.2 vs. 52.5 ± 12.7 (p < 0.01) in 3T3–L1 cells, and 126.0 ± 18.7 vs. 55.3 ± 13.4 (p < 0.01) in 10T1/2 cells, respectively. Adipocyte differentiation was further enhanced by the addition of hydrogen peroxide, which was also suppressed by febuxostat. Interestingly, febuxostat, but not allopurinol (another xanthine oxidase inhibitor), rapidly induced the nuclear translocation of Nrf2 and facilitated the degradation of Keap1, similar to the electrophilic Nrf2 activator omaveloxolone. These results suggest that febuxostat alleviates adipogenesis under oxidative conditions, at least in part by suppressing ROS production and Nrf2 activation. Regulation of adipocytic differentiation by febuxostat is expected to inhibit obesity due to menopause or overeating

RANKLが誘導する破骨細胞分化におけるROSの役割と、Febuxostatによる破骨細胞分化抑制効果

Receptor activator of NF-κB ligand (RANKL), a critical mediator of osteoclastogenesis, is upregulated in multiple myeloma (MM). The xanthine oxidase inhibitor febuxostat, clinically used for prevention of tumor lysis syndrome, has been demonstrated to effectively inhibit not only the generation of uric acid but also the formation of reactive oxygen species (ROS). ROS has been demonstrated to mediate RANKL-mediated osteoclastogenesis. In the present study, we therefore explored the role of cancer-treatment-induced ROS in RANKL-mediated osteoclastogenesis and the suppressive effects of febuxostat on ROS generation and osteoclastogenesis. RANKL dose-dependently induced ROS production in RAW264.7 preosteoclastic cells; however, febuxostat inhibited the RANKL-induced ROS production and osteoclast (OC) formation. Interestingly, doxorubicin (Dox) further enhanced RANKL-induced osteoclastogenesis through upregulation of ROS production, which was mostly abolished by addition of febuxostat. Febuxostat also inhibited osteoclastogenesis enhanced in cocultures of bone marrow cells with MM cells. Importantly, febuxostat rather suppressed MM cell viability and did not compromise Dox’s anti-MM activity. In addition, febuxostat was able to alleviate pathological osteoclastic activity and bone loss in ovariectomized mice. Collectively, these results suggest that excessive ROS production by aberrant RANKL overexpression and/or anticancer treatment disadvantageously impacts bone, and that febuxostat can prevent the ROS-mediated osteoclastic bone damage

LL-Z1640-2 for rheumatoid arthritis

Objectives: Aberrant NLRP3 inflammasome activation has been demonstrated in rheumatoid arthritis (RA), which may contribute to debilitating inflammation and bone destruction. Here, we explored the efficacy of the potent TGF-β-activated kinase-1 (TAK1) inhibitor LL-Z1640-2 (LLZ) on joint inflammation and bone destruction in collagen-induced arthritis (CIA). Methods: LL-Z1640-2 was administered every other day in CIA mice. Clinical and histological evaluation was performed. Priming and activation of NLRP3 inflammasome and osteoclastogenic activity were assessed. Results: NLRP3 inflammasome formation was observed in synovial macrophages and osteoclasts (OCs) in CIA mice. TACE and RANKL were also overexpressed in synovial macrophages and fibroblasts, respectively, in the CIA joints. Treatment with LLZ mitigated all the above changes. As a result, LLZ markedly suppressed synovial hypertrophy and pannus formation to alleviate pain and inflammation in CIA mice. LLZ could block the priming and activation of NLRP3 inflammasome in RAW264.7 macrophage cell line, primary bone marrow macrophages and OCs upon treatment with LPS followed by ATP, thereby suppressing their IL-1β production. LLZ also suppressed LPS-induced production of TACE and TNF-α in bone marrow macrophages and abolished IL-1β-induced production of MMP-3, IL-6 and RANKL in synovial fibroblasts. In addition, LLZ directly inhibits RANKL-mediated OC formation and activation. Conclusion: TAK1 inhibition with LLZ may become a novel treatment strategy to effectively alleviate inflammasome-mediated inflammation and RANKL-induced osteoclastic bone destruction in joints alongside its potent suppression of TNF-α and IL-6 production and proteinase-mediated pathological processes in RA