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Osteoclastic bone resorption and osteoblastic bone formation/replenishment are closely coupled in bone metabolism. Anabolic parathyroid hormone (PTH), which is commonly used for treating osteoporosis, shifts the balance from osteoclastic to osteoblastic, although it is unclear how these cells are coordinately regulated by PTH. Here, we identify a serine protease inhibitor, secretory leukocyte protease inhibitor (SLPI), as a critical mediator that is involved in the PTH-mediated shift to the osteoblastic phase. Slpi is highly upregulated in osteoblasts by PTH, while genetic ablation of Slpi severely impairs PTH-induced bone formation. Slpi induction in osteoblasts enhances its differentiation, and increases osteoblast–osteoclast contact, thereby suppressing osteoclastic function. Intravital bone imaging reveals that the PTH-mediated association between osteoblasts and osteoclasts is disrupted in the absence of SLPI. Collectively, these results demonstrate that SLPI regulates the communication between osteoblasts and osteoclasts to promote PTH-induced bone anabolism. The mechanism by which parathyroid hormone mediates the switch from bone resorption to bone formation is unclear. Here, the authors show that SLPI regulates the communication between osteoblasts and osteoclasts to promote the anabolic effect of parathyroid hormone.

Bone morphogenetic protein (BMP)-2 plays a central role in bone-tissue engineering because of its potent bone-induction ability. However, the process of BMP-induced bone formation in vivo remains poorly elucidated. Here, we aimed to establish a method for intravital imaging of the entire process of BMP-2-induced ectopic bone formation. Using multicolor intravital imaging in transgenic mice, we visualized the spatiotemporal process of bone induction, including appearance and motility of osteoblasts and osteoclasts, angiogenesis, collagen-fiber formation, and bone-mineral deposition. Furthermore, we investigated how PTH1-34 affects BMP-2-induced bone formation, which revealed that PTH1-34 administration accelerated differentiation and increased the motility of osteoblasts, whereas it decreased morphological changes in osteoclasts. This is the first report on visualization of the entire process of BMP-2-induced bone formation using intravital imaging techniques, which, we believe, will contribute to our understanding of ectopic bone formation and provide new parameters for evaluating bone-forming activity.

Bone homeostasis is regulated by communication between bone-forming mature osteoblasts (mOBs) and bone-resorptive mature osteoclasts (mOCs). However, the spatial–temporal relationship and mode of interaction in vivo remain elusive. Here we show, by using an intravital imaging technique, that mOB and mOC functions are regulated via direct cell–cell contact between these cell types. The mOBs and mOCs mainly occupy discrete territories in the steady state, although direct cell–cell contact is detected in spatiotemporally limited areas. In addition, a pH-sensing fluorescence probe reveals that mOCs secrete protons for bone resorption when they are not in contact with mOBs, whereas mOCs contacting mOBs are non-resorptive, suggesting that mOBs can inhibit bone resorption by direct contact. Intermittent administration of parathyroid hormone causes bone anabolic effects, which lead to a mixed distribution of mOBs and mOCs, and increase cell–cell contact. This study reveals spatiotemporal intercellular interactions between mOBs and mOCs affecting bone homeostasis in vivo. Communication between osteoblasts and osteoclasts is essential for bone homeostasis, but the mode of interaction is unclear. The authors use intravital two-photon microscopy in mice to show that these cells directly interact, regulating activity of osteoclasts, and that the interaction is modulated by parathyroid hormone administration.

Regeneration of large bone defects caused by trauma or tumor resection remains one of the biggest challenges in orthopedic surgery. Because of the limited availability of autograft material, the use of artificial bone is prevalent; however, the primary role of currently available artificial bone is restricted to acting as a bone graft extender owing to the lack of osteogenic ability. To explore whether surface modification might enhance artificial bone functionality, in this study we applied low-pressure plasma technology as next-generation surface treatment and processing strategy to chemically (amine) modify the surface of beta-tricalcium phosphate (β-TCP) artificial bone using a CH 4 /N 2 /He gas mixture. Plasma-treated β-TCP exhibited significantly enhanced hydrophilicity, facilitating the deep infiltration of cells into interconnected porous β-TCP. Additionally, cell adhesion and osteogenic differentiation on the plasma-treated artificial bone surfaces were also enhanced. Furthermore, in a rat calvarial defect model, the plasma treatment afforded high bone regeneration capacity. Together, these results suggest that amine modification of artificial bone by plasma technology can provide a high osteogenic ability and represents a promising strategy for resolving current clinical limitations regarding the use of artificial bone.

Lumbar canal stenosis (LCS) is a common degenerative lumbar spinal disease (DLSD) widely treated by decompression surgery, also known as laminectomy. Few cases have been observed where DLSD has progressed postoperatively, thus requiring reoperation. However, data on such cases are limited. We included 247 patients (148 men and 99 women; mean age = 73.3 years) with a mean follow-up of 2.3 years in this single-center retrospective study. Among them, 129 patients underwent bilateral partial laminectomy (BPL), 91 patients underwent lumbar spinous process-splitting laminectomy (LSPSL), and 27 underwent microendoscopic laminotomy (MEL). Of all the patients, 34 (13.8%) exhibited progression of lumbar spine degeneration symptoms, with nine (3.6%) requiring reoperation. Over 90% of new symptoms developed within one year of the initial surgery. Reoperation rates were significantly higher in patients with foraminal stenosis (P = <0.001). Additionally, 35 patients (14.2%) exhibited slippage progression. LSPSL resulted in significantly less slippage progression (P = 0.026). Spinal canal and foraminal stenosis were significantly associated with slippage progression (P< 0.001 and P = 0.010, respectively). LSPSL reduced the incidence of canal and foraminal stenosis. Symptomatic DLSD was more common within one year post surgery, with foraminal stenosis more frequently requiring reoperation.

Bone homeostasis is dynamically regulated by a balance between bone resorption by osteoclasts and bone formation by osteoblasts. Visualizing and evaluating the dynamics of bone cells in vivo remain difficult using conventional technologies, including histomorphometry and imaging analysis. Over the past two decades, multiphoton microscopy, which can penetrate thick specimens, has been utilized in the field of biological imaging. Using this innovative technique, the in vivo dynamic motion of bone metabolism-related cells and their interactions has been revealed. In this review, we summarize previous approaches used for bone imaging and provide an overview of current bone tissue imaging methods using multiphoton excitation microscopy.

A 78-year-old man presented with back pain. Magnetic resonance imaging revealed marrow edema within the L4 and L5 vertebral bodies and a spinal epidural abscess in the spinal canal. The patient was considered to have pyogenic spondylodiscitis at the L4/L5 level. The Gram-positive cocci isolated from blood cultures were subsequently identified as Gemella sanguinis using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Symptom improvement was achieved and the infection was eradicated with conservative treatment (treatment with ceftriaxone [CTRX] and minocycline [MINO]). We report the first case of G. sanguinis-associated pyogenic spondylodiscitis. MALDI-TOF MS was useful in identifying this uncommon bacterium.

Background: Moderate alcohol consumption has been reported to be associated with a decreased risk of cardiometabolic diseases. Whether drinking pattern is associated with the risk of proteinuria is unknown. Methods: Study subjects were 9154 non-diabetic Japanese men aged 40-55 years, with an estimated glomerular filtration rate ≥60 mL/min/1.73 m2, no proteinuria, and no use of antihypertensive medications at entry. Data on alcohol consumption were obtained by questionnaire. We defined \"consecutive proteinuria\" as proteinuria detected twice consecutively as 1+ or higher on urine dipstick at annual examinations. Results: During the 81 147 person-years follow-up period, 385 subjects developed consecutive proteinuria. For subjects who reported drinking 4-7 days per week, alcohol consumption of 0.1-23.0 g ethanol/drinking day was significantly associated with a decreased risk of consecutive proteinuria (hazard ratio [HR] 0.54; 95% confidence interval [CI], 0.36-0.80) compared with non-drinkers. However, alcohol consumption of ≥69.1 g ethanol/drinking day was significantly associated with an increased risk of consecutive proteinuria (HR 1.78; 95% CI, 1.01-3.14). For subjects who reported drinking 1-3 days per week, alcohol consumption of 0.1-23.0 g ethanol/drinking day was associated with a decreased risk of consecutive proteinuria (HR 0.76; 95% CI, 0.51-1.12), and alcohol consumption of ≥69.1 g ethanol/drinking day was associated with an increased risk of consecutive proteinuria (HR 1.58; 95% CI, 0.72-3.46), but these associations did not reach statistical significance. Conclusions: Men with frequent alcohol consumption of 0.1-23.0 g ethanol/drinking day had the lowest risk of consecutive proteinuria, while those with frequent alcohol consumption of ≥69.1 g ethanol/drinking day had an increased risk of consecutive proteinuria.

Bone morphogenetic proteins (BMPs) have been clinically applied for induction of bone formation in musculoskeletal disorders such as critical-sized bone defects, nonunions, and spinal fusion surgeries. However, the use of supraphysiological doses of BMP caused adverse events, which were sometimes life-threatening. Therefore, safer treatment strategies for bone regeneration have been sought for decades. Systemic administration of a potent selective antagonist of retinoic acid nuclear receptor gamma (RARγ) (7C) stimulated BMP-induced ectopic bone formation. In this study, we developed 7C-loaded poly lactic nanoparticles (7C-NPs) and examined whether local application of 7C enhances BMP-induced bone regeneration. The collagen sponge discs that absorbed recombinant human (rh) BMP-2 were implanted into the dorsal fascia of young adult mice to induce ectopic bone. The combination of rhBMP-2 and 7C-NP markedly increased the total bone volume and thickness of the bone shell of the ectopic bone in a dose-dependent manner compared to those with rhBMP-2 only. 7C stimulated sulfated proteoglycan production, expression of chondrogenic marker genes, and Sox9 reporter activity in both chondrogenic cells and MSCs. The findings suggest that selective RARγ antagonist 7C or the related compounds potentiate the bone inductive ability of rhBMP-2, as well as support any future research to improve the BMP-2 based bone regeneration procedures in a safe and efficient manner.

Background:Japanese cedar (Cryptomeria japonica) pollen is a major cause of seasonal pollinosis in Japan. Protease activity in the pollen grains may trigger pro-allergic responses but no such proteases have yet been identified as pollen allergens. Objectives:We report the molecular cloning and immunochemical characterization of a novel C. japonica pollen allergen belonging to the aspartic protease family. Methods:We focused on the C. japonica pollen allergen spot No. 63 (CPA63, 47.5% IgE binding frequency) on our 2-dimensional IgE immunoblot map. The internal amino acid sequences were determined using time-of-flight mass spectrometry. Full-length cpa63 cDNA was cloned by rapid amplification of cDNA ends (RACE)-PCR. Recombinant CPA63 (r-CPA63) was expressed using the baculovirus-insect cell culture system and its IgE binding capacity was analyzed by enzyme-linked immunosorbent assay (ELISA). The proteolytic activity of r-CPA63 was also assessed using a putative mature enzyme produced upon autolysis. Results: cpa63 cDNA encoded a 472 amino acid polypeptide showing about 40% sequence identity to members of the plant atypical aspartic protease family. ELISA showed that r-CPA63 was recognized by IgE antibodies in the serum of 58% (18/31) of Japanese cedar pollinosis patients. We also demonstrated an aspartic protease-like enzyme activity of the putative mature r-CPA63. Conclusions:We have identified the first plant aspartic protease allergen from Japanese cedar pollen. The availability of the CPA63 sequence and its recombinant allergen production system are useful not only for pharmaceutical applications but also for further examination of the role of protease activity in the pathogenesis of cedar pollinosis.