Inhibition Of Bone Resorption Research Articles

Zhuanggu Shubi ointment mediated the characteristic bacteria-intestinal mucosal barrier-bone metabolism axis to intervene in postmenopausal osteoporosis

BackgroundZhuanggu Shubi ointment (ZGSBG) has good efficacy in postmenopausal osteoporosis (PMO), but the mechanism of efficacy involving gut microecology has not been elucidated.ObjectiveThis study investigated the mechanism of ZGSBG in regulating gut microecology in PMO.MethodsThe bilateral ovarian denervation method was used to construct a rat model of PMO and was administered ZGSBG. Behavior, bone transformation, gut microbiota, intestinal mucosal barrier, and intestinal inflammatory-related indexes were detected.ResultsAfter ZGSBG intervention, bone R-hydroxy glutamic acid protein and procollagen type I N-terminal propeptides were significantly upregulated, while C-terminal telopeptide of type-I collagen and tartrate-resistant acid phosphatase-5b were significantly downregulated. Pathological analysis demonstrated an improvement in femoral and colonic structures. The expressions of zonula occludens-1, occludin, claudin-1, and secretory immunoglobulin A in the colonic tissues were significantly elevated, while the levels of tumor necrosis factor-α, interleukin-1β, interleukin-6, and lipopolysaccharides were reduced. Moreover, characteristic bacteria Muribaculaceae and Prevotella were significantly enriched. Furthermore, Muribaculaceae and Prevotella have a positive correlation with intestinal mucosal barrier function and a negative correlation with intestinal inflammatory responses.ConclusionZGSBG promoted bone formation, inhibited bone resorption, regulated gut microbiota, repaired intestinal mucosal barrier damage, and inhibited intestinal inflammatory responses in PMO rats. Muribaculaceae and Prevotella might play positive roles in ZGSBG treatment of intestinal mucosal barrier injury and inflammatory reactions in PMO.

Tales of Cancer-Induced Bone Disease from the Senescent Osteocyte Crypt

Cancer-induced bone disease greatly diminishes the quality of life for patients with bone metastatic breast cancer, resulting in painful skeletal-related events including bone loss and fracture. Improved understanding of the roles of osteoblasts and osteoclasts, and how tumors alter their biology, has led to blockbuster therapies that significantly reduce skeletal-related events, but the disease remains incurable. However, emerging technologies and tools for studying the role of other stromal and immune components in controlling tumor–host interactions have begun to reveal new insights that may yield tractable therapeutic targets to further mitigate the painful effects of bone metastases. In this issue of Cancer Research, Kaur and colleagues study osteocytes, which are terminally differentiated osteoblasts and entombed within the bone matrix, from established bone metastatic breast cancer and report how the disease ages them as characterized by a senescence-associated secretory phenotype. This premature development of osteocyte senescence in turn enhances bone destruction and osteoclastogenic potential. Targeting senescent cells using senolytics suppressed bone resorption and preserved bone mass. Collectively, these findings underscore osteocyte involvement in the “vicious cycle” of bone metastasis, and targeting senescent osteocytes represents a new avenue for managing cancer-induced bone disease.See related article by Kaur et al., p. 3936

Platelet Count Normalization Following Romosozumab Treatment for Osteoporosis in Patient with Immune Thrombocytopenic Purpura: A Case Report and Literature Review

Romosozumab, which is approved for the treatment of osteoporosis, has a dual-action mechanism that promotes bone formation and inhibits bone resorption. However, its association with an increased risk of major adverse cardiovascular events, as highlighted in the ARCH I study, raises concerns. The underlying pathophysiological mechanisms, possibly involving changes in platelet dynamics, are yet to be fully elucidated. Herein, we present a case of a 60-year-old Korean woman diagnosed with immune thrombocytopenic purpura and new-onset osteoporosis, who was treated with romosozumab. Subsequent to the administration of romosozumab, there was a notable elevation in her platelet count. This observation warrants further investigation into the off-target effects of romosozumab, especially its impact on hematopoietic stem cell function and platelet dynamics. This case accentuates the imperative for more comprehensive research into the systemic effects of romosozumab, particularly its involvement in hematopoiesis and cardiovascular risk, to thoroughly understand its extensive implications for patient health.

Histological Analysis of the Effect of a Vector Potential Generator on the Femur of a Hindlimb-Suspended Rat

Disuse osteoporosis occurs due to rest and reduced mechanical stimulation. Under these conditions, bone resorption exceeds bone formation, leading to a decrease in bone density. Vector potential (VP) generators have been developed, and their ability to maintain cartilage thickness has been reported. However, their effects on bone tissue remain unstudied. In this study, experiments were conducted to test the effects of VP on bones that had undergone weight reduction due to hindlimb suspension as a model of disuse osteoporosis. Methods: In this study, 7-week-old male Wistar rats (N = 6 each) were classified into control (CO), hindlimb suspension (HS), and VP energization intervention groups. The tail was used to suspend the HS and VP to remove the load applied to the hindlimbs. The VP conditions were as follows: voltage, 67 mV; frequency, 20 kHz, 0.12 mA; experimental intervention, 30 min/day, 5 days/week, for 3 weeks. At the end of the experimental period, the rats were euthanized with carbon dioxide gas, and histological specimens were fixed in 4% paraformaldehyde (PFA) in the femur and analyzed by electron microscopy, bone morphometry, immunohistology, bone fracture testing, and gene expression analysis. Results: HS decreased trabecular bone density and strength. However, VP maintained a significantly higher bone mass than HS, and VP did not differ from CO in bone strength; more osteoclasts were observed on the bone surface in HS, but they were suppressed in VP, and gene expression of CTSK and MMP-9 was decreased. Conclusions: VP suppressed bone resorption by osteoclasts, suggesting that VP is useful in the treatment of disuse osteoporosis.

Atypical femur fracture following romosozumab and bisphosphonate treatment.

Romosozumab, a monoclonal antibody against sclerostin, is a newly licensed dual-acting osteoporosis treatment for patients at very high risk of fracture. Sclerostin inhibition leads to stimulation of bone formation and simultaneous inhibition of bone resorption. Only three cases of atypical femur fractures were reported out of 5,621 patients who received romosozumab in the pivotal randomised controlled trials FRAME and ARCH; however, most enrolled clinical trial patients were osteoporosis treatment-naïve or had a prolonged washout period. We report a case of an atypical femur fracture that occurred after the completion of romosozumab treatment which was followed by one dose of 5 mg intravenous zoledronic acid. The patient had previously received a 2-year course of subcutaneous teriparatide and subsequent three consecutive yearly intravenous zoledronic acid infusions, followed by a 2-year treatment break. This case highlights the risks of prolonged suppression of bone resorption, which includes romosozumab due to its dual action and the need for further research on how to minimise such deleterious medication effects. Patients who are switched from prolonged antiresorptive treatment to romosozumab, should be risk-assessed and counselled for the risk of atypical femur fracture.

Extracellular vesicles from mouse bone marrow macrophages-derived osteoclasts treated with zoledronic acid contain miR-146a-5p and miR-322-3p, which inhibit osteoclast function

Medication-related osteonecrosis of the jaw (MRONJ) is an intractable form of osteonecrosis of the jaw that rarely occurs in patients using bone resorption inhibitors such as bisphosphonates (BPs). Then, extracellular vesicles (EVs) carry various signaling molecules, such as mRNAs, microRNAs (miRNAs), and proteins, and have attracted attention as intercellular communication tools. Recently, the role of EVs in communication between osteoclasts and surrounding bone cells has been confirmed. This study aimed to elucidate the effects of EVs derived from osteoclasts treated with zoledronic acid (ZA), one of the BPs on osteoclast function. EVs were isolated by ultracentrifugation of the culture supernatant of osteoclasts treated with ZA, and miRNAs were extracted from these EVs. Tartrate-resistant acid phosphatase staining of the ZA treated osteoclasts showed reduced osteoclastogenesis. In addition, pit assay showed that ZA significantly decreased the bone resorption capacity of osteoclasts. miRNA-seq analysis identified 11 upregulated and 5 downregulated differentially expressed genes (DEGs) in the miRNA of EVs derived from ZA-treated osteoclasts compared to EVs derived from osteoclasts not treated with ZA. qRT-PCR analysis confirmed the amount of these specific miRNAs, with miR-146a-5p, and miR-322-3p being significantly upregulated by ZA. Overexpression of miR-146a-5p in osteoclasts inhibited osteoclastogenesis and decreased the mRNA expression of osteoclast markers. In addition, Traf6 was identified as a candidate target gene of miR-146a-5p in several miRNA databases. Indeed, the overexpression of miR-146a-5p decreased the expression level of Traf6 in osteoclasts. Additionally, overexpression of miR-322-3p in the pre-osteoblast, MC3T3-E1 cells, resulted in a significant increase in the mRNA expression levels of Sp7. Our data indicate that BPs attenuate osteoclastogenesis by simultaneously altering the characteristics of osteoclast-derived EVs. Overexpression of miR-146a-5p and miR-322-3p influences osteoclast differentiation, and Traf6 is a target gene of miR-146a-5p. On the other hand, Overexpression of miR-322-3p affects osteoblast differentiation. We suggest that ZA-treated osteoclast-derived EVs may play an important role in osteoclast function and bone resorption.

Romosozumab for the treatment of osteoporosis - a systematic review.

Romosozumab, a new treatment of osteoporosis, is a monoclonal antibody that targets sclerostin and thereby exhibits a dual mechanism of action by stimulating bone formation and inhibiting bone resorption. This systematic review aims to assess the clinical efficacy and safety of romosozumab for treatment of primary and secondary osteoporosis. A comprehensive literature search was conducted in October 2023 across multiple databases including Embase, PubMed and Cochrane Library. Randomized controlled trials (RCTs) and observational studies evaluating the impact of romosozumab on BMD, bone turnover markers (BTM), fracture outcomes, and its safety profile were included. Data extraction and quality assessment were performed independently by two reviewers in accordance with PRISMA guidelines. A total of 36 articles met the inclusion criteria. Romosozumab significantly increased BMD at the lumbar spine, total hip, and femoral neck compared to placebo and active comparators in patients with primary osteoporosis. Sequential therapy with romosozumab followed by antiresorptives maintained or further increased BMD and reduced fracture risk. Romosozumab was generally well tolerated, however, an imbalance in cardiovascular adverse event was observed in one large clinical trial. Observational studies supported these findings. Specific subgroups of patients with secondary osteoporosis were assessed, demonstrating overall positive outcomes with romosozumab treatment. Romosozumab effectively increases BMD and reduces fracture risk, particularly when used as initial therapy in high fracture-risk patients. Sequential therapy with subsequent antiresorptive treatment optimizes long-term benefits. While generally well-tolerated, its cardiovascular safety profile requires further long-term studies to ensure its safety in clinical practice. Additional studies are needed to confirm efficacy and safety in patients with secondary osteoporosis.

Preparation and evaluation of injectable sustained-release Alendronate-loaded lipid liquid crystal on ovariectomy-induced osteoporosis in rats

Alendronate, a bisphosphonate compound, is used to treat osteoporosis by inhibiting bone resorption. However, oral consumption of Alendronate can cause severe gastrointestinal side effects, such as heartburn, difficulty swallowing, constipation or diarrhea, flatulence, and esophageal irritation or pain. To overcome this problem, an injectable sustained-release formulation of alendronate based on lipid liquid crystal (LLC) using phosphatidylcholine (PC), sorbitan monooleate (SMO), glycerol di-oleate (GDO), and N-methyl-2-pyrrolidone (NMP) or ethanol solvents was recommended. This compound was added as a base to one side of a coupling syringe, while alendronate powder was added to the other. After combining the two syringes, the resulting formulations were transferred into tubes containing PBS for in-vitro evaluation. In formulations containing ethanol, the cumulative percentage of drug release, water content, and degradation were higher than in those with NMP. Furthermore, LLC gel formulations with ethanol solvent had lower viscosity and a cubic structure, whereas LLC containing NMP had a hexagonal structure, indicating slower and longer release of alendronate in LLC-NMP formulations. In-vivo evaluations of subcutaneous injections of alendronate based on LLC formulation in rats with ovariectomy-induced osteoporosis showed significant advancements in osteogenesis markers, including RUNX2, OPG, VEGF, and Type 1 Collagen, according to Western blot analysis. These finding highlight alendronate's potential not only as a bone resorption inhibitor but also as a bone formation stimulator. Additionally, histopathology results revealed no osteoclast activity or osteoarthritis reactions in the LLC formulation group. Hence, an injectable LLC formulation containing PC, SMO and NMP could be a suitable option for developing a sustained-release LLC formulation of alendronate for osteoporosis treatment.

Zhuangyao Jianshen Wan ameliorates senile osteoporosis in SAMP6 mice through Modulation of the GCN5L1-mediated PI3K/Akt/wnt signaling pathway

BackgroundSenile osteoporosis (SOP) is a systemic bone disease characterized by increased susceptibility to fractures. However, there is currently no effective treatment for SOP. The Zhuangyao Jianshen Wan (ZYJSW) pill is traditionally believed to possess kidney-nourishing and bone-strengthening effects, demonstrating efficacy in treating fractures. Despite this, its effectiveness and mechanism in SOP remain unclear. This study aims to investigate the therapeutic potential of ZYJSW in treating SOP in senescence accelerated mouse prone 6 (SAMP6, P6) mice, and elucidate the underlying mechanisms. MethodsFour-month-old SAMP6 mice were categorized into six groups: the model group (SAMP6), low, medium, and high-dose ZYJSW treatment groups, calcitriol treatment (positive control 1) group, and metformin treatment (positive control 2) group. Gastric administration was carried out for 15 weeks, and a normal control group comprising four-month-old Senescence-Accelerated Mouse Resistant 1 (SAMR1) mice. Changes in body weight, liver and kidney function, bone protective effects, and muscle quality were evaluated using various assays, including H&E staining, Goldner staining, bone tissue morphology analysis, Micro-CT imaging, and biomechanical testing. Qualitative analysis and quality control of ZYJSW were performed via LC-MS/MS analysis. To explore mechanisms, network pharmacology and proteomics were employed, and the identified proteins were validated by Western blotting. ResultsOral administration of ZYJSW to P6 mice exerted preventive efficacy against osteopenia, impaired bone microstructure, and poor bone and muscle quality. ZYJSW attenuated the imbalance in bone metabolism by promoting bone formation, as evidenced by the upregulation of key factors such as Runt-related transcription factor 2 (RUNX2), Bone Morphogenetic Protein (BMP2), Osteoprotegerin (OPG) and Osteocalcin (OCN), while simultaneously inhibiting bone resorption through the downregulation of TNF receptor associated factor 6 (TRAF6), Tartrate resistant acid phosphatase (TRAP), Receptor activator for nuclear factor-κB ligand (RANKL) and Cathepsin K (CTSK). Additionally, ZYJSW enhanced muscle structure and function by counteracting the elevation of Ubiquitin (Ub), Muscle RING-finger protein-1 (Murf-1), F-Box Protein 32 (FBOX32), and Myogenin (Myog). Network pharmacology predictions, proteomics analysis corroborated by published literature demonstrated the role of ZYJSW involving in safeguarding mitochondrial biogenesis. This was achieved by suppressing GCN5L1 expression, contributing to the heightened expression of TFAM, PGC-1α, and nuclear respiratory factor-1 (NRF-1) proteins. ZYJSW also positively modulated Wnt signaling pathways responsible for bone formation, due to regulating expressions of key components like β-catenin, GSK-3β, and LRP5. In addition, ZYJSW causes the downregulation of the PI3K/Akt pathway by inhibiting the phosphorylation of both PI3K and Akt. ConclusionsThe study highlights the significance of ZYJSW in preserving the health of both bone and muscle in P6 mice, potentially through the regulation of the GCN5L1-mediated PI3K/Akt/Wnt signaling pathway. The translational potential of this articleOur research provides evidence and a mechanistic rationale for ZYJSW as a candidate for SOP treatment, offering insights for further exploration and strategy development.

Alendronate sodium induces G1 phase arrest and apoptosis in human umbilical vein endothelial cells by inhibiting ROS-mediated ERK1/2 signaling

Bisphosphonates are potent bone resorption inhibitors, among which alendronate sodium (ALN) is commonly prescribed for most osteoporosis patients, but long-term application of ALN can cause bisphosphonate-related osteonecrosis of jaw (BRONJ), the pathogenesis of which remains unclear. Previous studies have suggested that bisphosphonates cause jaw ischemia by affecting the biological behavior of vascular endothelial cells, leading to BRONJ. However, the impacts of ALN on vascular endothelial cells and its mechanism remain unclear. The purpose of this work is to assess the influence of ALN on human umbilical vein endothelial cells (HUVECs) and clarify the molecular pathways involved. We found that high concentration of ALN induced G1 phase arrest in HUVECs, demonstrated by downregulation of Cyclin D1 and Cyclin D3. Moreover, high concentration of ALN treatment showed pro-apoptotic effect on HUVECs, demonstrated by increased levels of the cleaved caspase-3, the cleaved PARP and Bax, along with decreased levels of anti-apoptotic protein Bcl-2. Further experiments showed that ERK1/2 phosphorylation was decreased. Additionally, ALN provoked the build-up of reactive oxygen species (ROS) in HUVECs, leading to ERK1/2 pathway suppression. N-acetyl-L-cysteine (NAC), a ROS scavenger, efficiently promoted the ERK1/2 phosphorylation and mitigated the G1 phase arrest and apoptosis triggered by ALN in HUVECs. PD0325901, an inhibitor of ERK1/2 that diminishes the ERK1/2 phosphorylation enhanced the ALN-induced G1 phase arrest and apoptosis in HUVECs. These findings show that ALN induces G1 phase arrest and apoptosis through ROS-mediated ERK1/2 pathway inhibition in HUVECs, providing novel insights into the pathogenic process, prevention and treatment of BRONJ in individuals receiving extended use of ALN.

Autophagy Regulator Rufy 4 Promotes Osteoclastic Bone Resorption by Orchestrating Cytoskeletal Organization via Its RUN Domain.

Rufy4, a protein belonging to the RUN and FYVE domain-containing protein family, participates in various cellular processes such as autophagy and intracellular trafficking. However, its role in osteoclast-mediated bone resorption remains uncertain. In this study, we investigated the expression and role of the Rufy4 gene in osteoclasts using small interfering RNA (siRNA) transfection and gene overexpression systems. Our findings revealed a significant increase in Rufy4 expression during osteoclast differentiation. Silencing Rufy4 enhanced osteoclast differentiation, intracellular cathepsin K levels, and formation of axial protrusive structures but suppressed bone resorption. Conversely, overexpressing wild-type Rufy4 in osteoclasts hindered differentiation while promoting podosome formation and bone resorption. Similarly, overexpression of a Rufy4 variant lacking the RUN domain mimics the effects of Rufy4 knockdown, significantly increasing intracellular cathepsin K levels, promoting osteoclastogenesis, and elongated axial protrusions formation, yet inhibiting bone resorption. These findings indicate that Rufy4 plays a critical role in osteoclast differentiation and bone resorption by regulating the cytoskeletal organization through its RUN domain. Our study provides new insights into the molecular mechanisms governing osteoclast activity and underscores Rufy4's potential as a novel therapeutic target for bone disorders characterized by excessive bone resorption.

Metabolomic characterization of MC3T3-E1pre-osteoblast differentiation induced by ipriflavone-loaded mesoporous nanospheres

This study reports on the metabolic changes accompanying the differentiation of MC3T3-E1 osteoprogenitor cells induced by mesoporous bioactive glass nanospheres (nMBG) loaded with ipriflavone (nMBG-IP). Ipriflavone (IP) is a synthetic isoflavone known for inhibiting bone resorption, maintaining bone density, and preventing osteoporosis. Delivering IP intracellularly is a promising strategy to modulate bone remodeling at significantly lower doses compared to free drug administration. Our results demonstrate that nMBG are efficiently internalized by pre-osteoblasts and, when loaded with IP, induce their differentiation. This differentiation process is accompanied by pronounced metabolic alterations, as monitored by NMR analysis of medium supernatants and cell extracts (exo- and endo-metabolomics, respectively). The main effects include an early-stage intensification of glycolysis and changes in several metabolic pathways, such as nucleobase metabolism, osmoregulatory and antioxidant pathways, and lipid metabolism. Notably, the metabolic impacts of nMBG-IP and free IP were very similar, whereas nMBG alone induced only mild changes in the intracellular metabolic profile without affecting the cells' consumption/secretion patterns or lipid composition. This finding indicates that the observed effects are primarily related to IP-induced differentiation and that nMBG nanospheres serve as convenient carriers with both efficient internalization and minimal metabolic impact. Furthermore, the observed link between pre-osteoblast differentiation and metabolism underscores the potential of utilizing metabolites and metabolic reprogramming as strategies to modulate the osteogenic process, for instance, in the context of osteoporosis and other bone diseases.

First-in-human study of dosimetry, safety and efficacy for [177Lu]Lu-P15-073: a novel bisphosphonate-based radioligand therapy (RLT) agent for bone metastases.

Bisphosphonates are pivotal in managing bone tumors by inhibiting bone resorption. This study investigates the therapeutic potential of [177Lu]Lu-P15-073, a novel bisphosphonate, for radioligand therapy (RLT) in bone metastases. Ten patients (age 35 to 75) with confirmed bone metastases underwent therapy with a single dose of [177Lu]Lu-P15-073 (1,225 ± 84 MBq, or 33 ± 2 mCi). Prior to treatment, bone metastases were verified via [99mTc]Tc-MDP bone scans. Serial planar whole-body scans monitored biodistribution over a 14-day period. Dosimetry was assessed for major organs and tumor lesions, while safety was evaluated through blood biomarkers and pain scores. Serial planar whole-body scans demonstrated rapid and substantial accumulation of [177Lu]Lu-P15-073 in bone metastases, with minimal uptake in blood and other organs. The absorbed dose in the critical organ, red marrow, was measured at (0.034 ± 0.010 mSv/MBq), with a notably low normalized effective dose (0.013 ± 0.005 mSv/MBq) compared to other 177Lu-labeled bisphosphonates. Persistent high uptake in bone metastases was observed, resulting in elevated tumor doses (median 3.12Gy/GBq). Patients exhibited favorable tolerance to [177Lu]Lu-P15-073 therapy, with no new instances of side effects. Additionally, 87.5% (7/8) of patients experienced a significant reduction in pain scale (numerical rating scale, NRS, from 5.1 ± 2.3 to 3.0 ± 1.8). The tumor-background ratio (TBRmean) of [99mTc]Tc-MDP correlated significantly with [177Lu]Lu-P15-073 uptake (P < 0.01), indicating its potential for prediction of absorbed dose. This study demonstrates the safety, dosimetry, and efficacy of a single therapeutic dose of [177Lu]Lu-P15-073 in bone metastases. The treatment was well-tolerated with no severe adverse events. These findings suggest that [177Lu]Lu-P15-073 holds promise as a novel RLT agent for bone metastases.

Mapping RANKL- and OPG-expressing cells in bone tissue: the bone surface cells as activators of osteoclastogenesis and promoters of the denosumab rebound effect.

Denosumab is a monoclonal anti-RANKL antibody that inhibits bone resorption, increases bone mass, and reduces fracture risk. Denosumab discontinuation causes an extensive wave of rebound resorption, but the cellular mechanisms remain poorly characterized. We utilized in situ hybridization (ISH) as a direct approach to identify the cells that activate osteoclastogenesis through the RANKL/OPG pathway. ISH was performed across species, skeletal sites, and following recombinant OPG (OPG:Fc) and parathyroid hormone 1-34 (PTH) treatment of mice. OPG:Fc treatment in mice induced an increased expression of RANKL mRNA mainly in trabecular, but not endocortical bone surface cells. Additionally, a decreased expression of OPG mRNA was detected in bone surface cells and osteocytes of both compartments. A similar but more pronounced effect on RANKL and OPG expression was seen one hour after PTH treatment. These findings suggest that bone surface cells and osteocytes conjointly regulate the activation of osteoclastogenesis, and that OPG:Fc treatment induces a local accumulation of osteoclastogenic activation sites, ready to recruit and activate osteoclasts upon treatment discontinuation. Analysis of publicly available single-cell RNA sequencing (scRNAseq) data from murine bone marrow stromal cells revealed that Tnfsf11+ cells expressed high levels of Mmp13, Limch1, and Wif1, confirming their osteoprogenitor status. ISH confirmed co-expression of Mmp13 and Tnfsf11 in bone surface cells of both vehicle- and OPG:Fc-treated mice. Under physiological conditions of human/mouse bone, RANKL is expressed mainly by osteoprogenitors proximate to the osteoclasts, while OPG is expressed mainly by osteocytes and bone-forming osteoblasts.

Exploring the Impact of Catechins on Bone Metabolism: A Comprehensive Review of Current Research and Future Directions.

Background/Objectives: Degenerative musculoskeletal diseases represent a global health problem due to the progressive deterioration of affected individuals. As a bioactive compound, catechins have shown osteoprotective properties by stimulating osteoblastic cells and inhibiting bone resorption. Thus, this review aimed to address the mechanism of action of catechins on bone tissue. Methods: The search was applied to PubMed without limitations in date, language, or article type. Fifteen articles matched the topic and objective of this review. Results: EGCG (epigallocatechin gallate) and epicatechin demonstrated action on the osteogenic markers RANKL, TRAP, and NF-κβ and expression of BMPs and ALP, thus improving the bone microarchitecture. Studies on animals showed the action of EGCG in increasing calcium and osteoprotegerin levels, in addition to regulating the transcription factor NF-ATc1 associated with osteoclastogenesis. However, it did not show any effect on osteocalcin and RANK. Regarding human studies, EGCG reduced the risk of fracture in a dose-dependent manner. In periodontal tissue, EGCG reduced IL-6, TNF, and RANKL in vitro and in vivo. Human studies showed a reduction in periodontal pockets, gingival index, and clinical attachment level. The action of EGCG on membranes and hydrogels showed biocompatible and osteoinductive properties on the microenvironment of bone tissue by stimulating the expression of osteogenic growth factors and increasing osteocalcin and alkaline phosphate levels, thus promoting new bone formation. Conclusions: EGCG stimulates cytokines related to osteogenes, increasing bone mineral density, reducing osteoclastogenesis factors, and showing great potential as a therapeutic strategy for reducing the risk of bone fractures.

Bioinspired Glycopeptide Hydrogel Reestablishing Bone Homeostasis through Mediating Osteoclasts and Osteogenesis in Periodontitis Treatment.

Irreversible alveolar bone resorption is one of the important clinical manifestations of periodontitis, which is initiated by a plaque biofilm and exacerbated by the imbalance of osteoclast activity and osteogenesis, affecting a patient's masticatory function and resulting in a high recurrence rate of periodontitis. Herein, to reestablish bone homeostasis in periodontitis, a minocycline hydrochloride (MH)-loaded glycopeptide hydrogel (MH/GRWgel) is fabricated to mediate alveolar bone absorption through sequential antibacterial and RANKL-blocking activities. GRWgel shows an ECM-like fibrous and porous microstructure serving as a scaffold for cell proliferation and differentiation and holds the merits including injectability, self-healing properties, and good biocompatibility. After injection in situ, MH is released rapidly from the hydrogel in the early stage, demonstrating a potent antimicrobial effect to combat the biofilm in the deep periodontal pocket. Moreover, MH/GRWgel exhibits a high specific binding efficiency with RANKL to suppress osteoclast maturation by shielding the RANKL/RANK interaction and enhancing osteogenic differentiation, thereby synergistically regulating bone homeostasis. In the rat periodontitis model, MH/GRWgel significantly curtails periodontitis progression through antimicrobial activity, inhibition of alveolar bone resorption, and promotion of bone regeneration, which is superior to the treatment of a commercial gel. These findings suggest that MH/GRWgel with superiority in regulating bone homeostasis provides a promising therapeutic strategy for periodontitis.

Maltobionic acid protects against ovariectomy‐induced osteoporosis by suppressing bone resorption

AbstractBackgroundOsteoporosis is a debilitating disease characterized by decreased bone density. In this study, we evaluated the anti‐osteoporotic effect of maltobionic acid (MB), one of the components of honey, and calcium maltobionate (MBCa) on bone density and metabolism using a mouse model of osteoporosis. The underlying mechanisms of MB and MBCa action were also investigated.ResultsOvariectomized (OVX) mice were fed diet containing MB or MBCa for 80 days, and femoral bone mineral content and mineral density (BMD) were evaluated. As expected, OVX reduced BMD; however, the administration of MB and MBCa significantly prevented this decrease. Furthermore, MB and MBCa treatment significantly reduced the serum levels of tartrate‐resistant acid phosphatase 5b (TRACP‐5b), a bone resorption marker, and significantly increased the levels of serum calcitonin, compared to those in the OVX control group. In vitro, the relatively high‐dose levels of MB and MBCa inhibited osteoclast differentiation by decreasing the protein expression of nuclear factor of activated T‐cell cytoplasmic 1 (NFATc1), the master transcription factor of osteoclastogenesis.ConclusionOur results showed that osteoporotic mice treated with MB and MBCa had improved bone density and bone metabolism compared to the OVX controls. Moreover, it was hypothesized herein that the suppressive effect on osteoclast differentiation slightly contributed to these results concomitantly. These findings suggest that the intake of MB or MBCa may contribute to the maintenance of bone health, including the prevention of primary osteoporosis.

Progression of vertebral fractures in metastatic melanoma and non-small cell lung cancer patients given immune checkpoint inhibitors

IntroductionThe immune system mediates important effects on bone metabolism, but little has been done to understand immunotherapy’s role in this interaction. This study aims to describe and identify risk factors for the occurrence and/or exacerbation of vertebral fractures (vertebral fracture progression) during immune checkpoint inhibitors (ICIs). MethodsWe conducted an observational, retrospective, monocentric study. We collected data on melanoma and NSCLC patients, treated with first-line ICIs at the Medical Oncology Department ASST Spedali Civili of Brescia, between January 2015 and November 2021, and with a median follow-up of 20.1 (6–36) months. We collected data on patients, diseases, immune-related adverse events, and cortico-steroid therapy initiated on concomitant ICIs. ResultsWe identified 135 patients, 65 (48.2 %) with locally advanced/metastatic melanoma and 70 (51.8 %) with locally advanced/metastatic non-small cell lung cancer (NSCLC). Twenty-one (15.6 %) patients already had an asymptomatic vertebral fracture at baseline before starting ICIs in monotherapy. A total of ten patients, or 7.4 %, had a vertebra fracture progression defined as a new vertebral fracture or a worsening of a previous fracture. There was a strong relation between the steroid therapy and irAEs with vertebra fracture progression [OR (95 % CI) 8.1 (3.7–17.8) p-value < 0.001] in univariable analysis. However, only steroid therapy resulted to be an independent risk factor [8.260 (95 % CI 0.909–75.095); p-value 0.061] at the multivariable analysis. ConclusionConcurrent steroid therapy in patients receiving immunotherapy exposes them to a high risk of fractures due to skeletal fragility. The use of bone resorption inhibitors should be considered in these patients to prevent these adverse events.

EFFECTS OF USING HYDROXIAPATITE-GELATIN GEL AND ROSELLA EXTRACT TO PREVENT RELAPSE IN ORTHODONTIC TREATMENT

To correct malocclusion and malposition in dentistry using orthodontic treatment. Teeth that have moved through the bone with orthodontic devices tend to return to their original position or what is usually called relapse. Relapse is when the teeth return to their original position before orthodontic treatment was carried out. Relapse prevention can be achieved using mechanical devices but there are still some limitations. The use of scaffolds can be a solution in preventing tooth relapse because scaffolds can support cells to grow and develop into new bone in the damaged area. The scaffold components are hydroxyapatite, gelatin, and rosella flower extract which contains flavonoids to inhibit bone resorption. To find out whether these components are toxic or not before they are applied to the human body, a cytotoxicity test is carried out, which is a laboratory study. This research was carried out by incubating the hydroxyapatite scaffold, gelatin and rosella flower extract with osteoblast cells for 24 hours to see whether the rosella extract was toxic to osteoblast cells. Conclusion: This toxicity test shows that rosella flower extract as an ingredient in making scaffolds is not toxic to osteoblast cells.

The senolytic agent ABT263 ameliorates osteoporosis caused by active vitamin D insufficiency through selective clearance of senescent skeletal cells

Background/ObjectiveActive vitamin D insufficiency accelerates the development of osteoporosis, with senescent bone cells and the senescence-associated secretory phenotype (SASP) playing crucial roles. This study aimed to investigate whether the senolytic agent ABT263 could correct osteoporosis caused by active vitamin D insufficiency by selectively clearing senescent cells. MethodsBone marrow mesenchymal stem cells (BM-MSCs) from young and aged mice were treated with ABT263 in vitro, and 1,25(OH)2D-insufficient (Cyp27b1+/−) mice were administered ABT263 in vivo. Cellular, molecular, imaging, and histopathological analyses were performed to compare treated cells and mice with control groups. ResultsABT263 induced apoptosis in senescent BM-MSCs by downregulating Bcl2 and upregulating Bax expression. It also induced apoptosis in senescent BM-MSCs from 1,25(OH)2D-insufficient mice. ABT263 administration corrected bone loss caused by 1,25(OH)2D insufficiency by increasing bone density, bone volume, trabecular number, trabecular thickness, and collagen synthesis. It also enhanced osteoblastic bone formation and reduced osteoclastic bone resorption in vivo. ABT263 treatment corrected the impaired osteogenic action of BM-MSCs by promoting their proliferation and osteogenic differentiation. Furthermore, it corrected oxidative stress and DNA damage caused by 1,25(OH)2D insufficiency by increasing SOD-2 and decreasing γ-H2A.X expression. Finally, ABT263 corrected bone cell senescence and SASP caused by 1,25(OH)2D insufficiency by reducing the expression of senescence and SASP-related genes and proteins. ConclusionABT263 can correct osteoporosis caused by active vitamin D insufficiency by selectively clearing senescent skeletal cells, reducing oxidative stress, DNA damage, and SASP, and promoting bone formation while inhibiting bone resorption. These findings provide new insights into the potential therapeutic application of senolytic agents in the treatment of osteoporosis associated with active vitamin D insufficiency. The translational potential of this articleThis study highlights the therapeutic potential of ABT263, a senolytic compound, in treating osteoporosis caused by active vitamin D insufficiency. By selectively eliminating senescent bone cells and their associated SASP, ABT263 intervention demonstrates the ability to restore bone homeostasis, prevent further bone loss, and promote bone formation. These findings contribute to the growing body of research supporting the use of senolytic therapies for the prevention and treatment of age-related bone disorders. The translational potential of this study lies in the development of novel therapeutic strategies targeting cellular senescence to combat osteoporosis, particularly in cases where vitamin D insufficiency is a contributing factor. Further clinical studies are warranted to validate the efficacy and safety of ABT263 and other senolytic agents in the treatment of osteoporosis in humans.