Search Results (1,588)

The service tree (Sorbus domestica L.) fruits are rich in polyphenols, which exhibit promising therapeutic effects on bone health. This review summarizes the potential benefits of polyphenols identified in Sorbus domestica L. fruits, such as chlorogenic acid (CGA), protocatechuic acid (PCA), rutin, epicatechin, and naringin on bone biology and on bone-related diseases, including osteoporosis and diabetes mellitus. Current evidence suggests that the aforementioned polyphenols may modulate osteoblast and osteoclast activity, enhance mineralization, mitigate oxidative stress and inflammation, thereby supporting overall bone health. Specific studies highlight the anabolic and anti-resorptive effects of CGA, the osteoprotective potential of PCA, and the ability of rutin, epicatechin, and naringin to promote osteogenic differentiation and inhibit osteoclastogenesis. Although the exact mechanisms are still unclear, it is believed that these bioactive metabolites can act through a variety of signalling pathways and epigenetic mechanisms. Despite existing preclinical evidence, there is a significant gap in clinical trials evaluating the direct impact of polyphenols mentioned above on bone health in humans. Therefore, further research is needed to confirm their effectiveness in clinical settings. The therapeutic potential of the most common polyphenols from Sorbus domestica L. fruits has been evaluated by available in vitro and in vivo studies, which highlight their promising potential as dietary interventions to prevent bone loss and improve skeletal integrity in metabolic bone diseases. Based on available information, maximum health benefits may be achieved if mature Sorbus domestica L. fruits are consumed approximately two weeks after harvest or as unripe fruit-based fermented products. Full article

Porphyromonas gingivalis (Pg), a keystone pathogen of chronic periodontitis, releases outer membrane vesicles (OMVs) that act as nanoscale vehicles to disseminate virulence factors within periodontal tissues and systemically beyond the oral cavity. Although Pg-OMVs are increasingly recognized as critical mediators of host–pathogen interactions, their effects on the differentiation and function of monocyte–macrophage/osteoclast lineage cells remain unclear. Here, we examined the impact of Pg-OMVs on the differentiation of RAW264.7 monocyte/macrophage-like cells into osteoclasts (OC) and/or macrophages (MΦ) in the presence of receptor activator of nuclear factor-κB ligand (RANKL). OMVs were isolated from Pg W83 and applied to RANKL-primed RAW264.7 cells using three distinct stimulation schedules: (1) simultaneous treatment with Pg-OMVs and RANKL at Day 0; (2) RANKL priming at Day 0 followed by Pg-OMV stimulation at Day 1; and (3) RANKL priming at Day 0 followed by Pg-OMV stimulation at Day 3. In all schedules, cells were cultured for 7 days from the initial RANKL exposure. Remarkably, simultaneous exposure to Pg-OMVs and RANKL (Schedule 1) markedly suppressed osteoclastogenesis (OC-genesis) while promoting M1 macrophage polarization. In contrast, delayed Pg-OMV stimulation of RANKL-primed cells (Schedules 2 and 3) significantly enhanced OC-genesis while reducing M1 polarization. These schedule-dependent effects were consistent with altered expression of osteoclastogenic markers, including dc-stamp, oc-stamp, nfatc1, and acp5. Importantly, a monoclonal antibody against OC-STAMP counteracted the Pg-OMV-induced upregulation of OC-genesis in Schedules 2 and 3. Furthermore, levels of Pg-OMV phagocytosis were inversely correlated with osteoclast formation. Finally, co-stimulation with RANKL and Pg-OMVs (Schedule 1) enhanced macrophage migratory capacity, whereas delayed stimulation with Pg-OMVs (Schedules 2 and 3) did not. Collectively, these findings indicate that Pg-OMVs exert stage-specific effects on the OC/MΦ lineage: stimulation at early stages of RANKL priming suppresses OC-genesis and promotes M1 polarization, whereas stimulation at later stages enhances OC-genesis without inducing M1 differentiation. Thus, Pg-OMVs may critically influence the fate of the OC/MΦ unit in periodontal lesions, contributing to disease progression and tissue destruction. Full article

Estrogen receptor-positive (ER⁺) breast cancer represents the most prevalent molecular subtype of breast cancer, characterized by hormone-dependent growth, relatively indolent progression, and a pronounced tendency to metastasize to bone. While endocrine therapies remain the cornerstone of treatment, a significant proportion of ER⁺ tumors eventually develop resistance, culminating in distant metastases—most frequently to the bone. Bone metastasis substantially compromises patient survival and quality of life, highlighting the critical need to elucidate its molecular underpinnings. Recent multi-omics and mechanistic studies have shed light on the complex interplay between tumor-intrinsic signaling pathways, such as dysregulated ER signaling, PI3K/AKT/mTOR, TGF-β, and Hippo pathways, and the bone microenvironment, including osteoclast activation, immune suppression, and stromal remodeling. This review systematically summarizes the current understanding of the molecular mechanisms driving bone metastasis in ER⁺ breast cancer, with a particular focus on tumor–bone microenvironment crosstalk and key regulatory pathways. Additionally, we discuss recent advances in therapeutic strategies, encompassing next-generation endocrine therapies, CDK4/6 inhibitors, bone-targeted agents, and pathway-specific inhibitors. Together, these insights pave the way for more effective and personalized interventions against ER⁺ breast cancer with bone involvement. Full article

Bone metastasis in breast cancer remains a major therapeutic challenge because current osteoclast-targeted therapies do not fully disrupt the tumor–bone vicious cycle. Osteocytes, the most abundant bone cells, are increasingly recognized as key regulators of bone–tumor crosstalk. Previous work has shown that osteocyte-specific overexpression of the Wnt co-receptor LRP5 inhibits breast cancer-induced osteolysis and generates conditioned medium (CM) with tumor-suppressive activity. Proteomic analysis identified LIM domain and actin-binding protein 1 (LIMA1) as a central mediator that interacts with Myosin Vb (MYO5B), suggesting the role of the LIMA1/MYO5B regulatory axis. This study demonstrates that CM derived from LRP5-overexpressing osteocytes suppresses EO771 breast cancer cell proliferation, migration, and invasion, and downregulates tumor-promoting proteins, including MMP9, Snail, IL-6, and TGF-β1, while upregulating the apoptosis-related protein cleaved caspase-3. These effects were largely reversed by knockdown of LIMA1 or MYO5B. In syngeneic mouse models of mammary tumors and bone metastasis, systemic administration of LRP5-overexpressing osteocyte-derived CM reduced tumor burden and osteolytic bone destruction, whereas genetic knockdown of LIMA1 in osteocytes or MYO5B in tumor cells abrogated these protective effects. Collectively, these findings indicate that LRP5 activation in osteocytes engages the LIMA1/MYO5B signaling axis that inhibits breast cancer progression and osteolysis, disrupts tumor–stromal interactions, and restores bone–tumor homeostasis, thereby providing a potential therapeutic strategy to break the vicious cycle of bone metastasis in breast cancer. Full article

Background/Objectives: Surfactin is a biosurfactant with various biological activities, including antibacterial and anti-inflammatory properties; however, its effects on bone metabolism remain poorly understood. This study aimed to investigate the effects of surfactin on osteoclast differentiation and elucidate its underlying molecular mechanisms. Methods: RAW264.7 cells were treated with receptor activator of nuclear factor-kappa B ligand (RANKL) and surfactin, and osteoclast differentiation and maturation were evaluated by tartrate-resistant acid phosphatase and F-actin staining, respectively. Gene expression of differentiation markers was assessed using real-time reverse transcription-quantitative polymerase chain reaction, while the kinetics of intracellular signaling molecules and transcription factors were analyzed using Western blot analysis. Results: Surfactin treatment significantly inhibited osteoclast differentiation and maturation, as well as the mRNA expression of Nfatc1, Acp5, and Cathepsin K. Although surfactin did not markedly affect RANKL-induced activation of the NF-κB or MAPK-mediated signaling, it significantly suppressed the expression of c-Fos at both the mRNA and protein levels. Furthermore, surfactin attenuated the phosphorylation of Elk1, a transcription factor involved in c-Fos induction. Conclusions: Surfactin inhibits RANKL-induced osteoclast differentiation by negatively regulating the Elk1-AP-1-NFATc1 axis. Surfactin may thus be a promising therapeutic candidate for the treatment of metabolic bone disorders and inflammatory bone destruction. Full article

Osteoarthritis (OA) is the most common form of arthritis and represents a major clinical and socioeconomic burden. Epidemiological data consistently show that OA affects women more frequently and, in several joints, more severely than men. Nevertheless, current in vitro models rarely consider sex-specific variables, limiting their ability to capture the biological mechanisms that shape the pathogenesis and progression of OA. Increasing evidence indicates that age-related hormonal fluctuations and subchondral bone remodeling strongly influence OA evolution, and that these processes differ between the sexes. For instance, the decline in estrogen levels during menopause has been associated with accelerated cartilage degeneration, increased osteoclastic activity, and a higher susceptibility to subchondral bone alterations, which may contribute to more aggressive clinical manifestations in women. These mechanisms are only partially reproduced in widely used experimental systems, including traditional biomaterial scaffolds and simplified osteochondral constructs, leaving important sex-dependent pathways unresolved. While advanced biomaterials enable precise control of stiffness, porosity, and biochemical cues, most current in vitro OA models still rely on sex-neutral design assumptions, limiting their ability to reproduce the divergent disease trajectories observed in men and women. By integrating material properties with dynamic loading and tunable hormonal conditions, next-generation in vitro systems could improve mechanistic understanding, increase the reliability of drug screening, and better support the development of sex-specific therapies through the combined efforts of bioengineering, materials science, cell biology, and translational medicine. Full article

Osteoporosis is a prevalent skeletal disorder characterized by reduced bone mass and microarchitectural deterioration, leading to increased fracture risk, particularly in aging populations. Postmenopausal osteoporosis (PMOP) remains the most common primary form and results from abrupt estrogen deficiency after menopause, which disrupts bone remodeling by accelerating the receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis, suppressing Wnt/β-catenin signaling, and promoting inflammatory cytokine production. In contrast, drug-induced osteoporosis (DIOP) encompasses a heterogeneous group of secondary bone disorders arising from pharmacologic exposures. Glucocorticoids suppress osteoblastogenesis, enhance osteoclast activity, and increase reactive oxygen species; long-term bisphosphonate therapy may oversuppress bone turnover, resulting in microdamage accumulation; denosumab withdrawal triggers a unique rebound surge in RANKL activity, often leading to rapid bone loss and multiple vertebral fractures. Medications including aromatase inhibitors, SSRIs, proton pump inhibitors, heparin, and antiepileptic drugs impair bone quality through diverse mechanisms. Standard antiresorptive agents remain first-line therapies, while anabolic agents such as teriparatide, abaloparatide, and romosozumab provide enhanced benefits in high-risk or drug-suppressed bone states. Transitional bisphosphonate therapy is essential when discontinuing denosumab, and individualized treatment plans—including drug holidays, lifestyle interventions, and monitoring vulnerable patients—are critical for optimizing outcomes. Emerging approaches such as small interfering RNA (siRNA)-based therapeutics, anti-sclerostin agents, digital monitoring technologies, and regenerative strategies show promise for future precision medicine management. Understanding the distinct and overlapping molecular mechanisms of osteoporosis is essential for improving fracture prevention and long-term skeletal health. Full article

Glucose-dependent insulinotropic polypeptide (GIP) was the first incretin hormone identified, best known for promoting glucose-stimulated insulin secretion. Increasing evidence has expanded its physiological relevance beyond glucose metabolism, revealing a significant role for GIP in the gut–bone axis. In vitro studies demonstrate that GIP inhibits osteoclast differentiation and activity while promoting osteoblastic bone formation. Findings from genetic animal models and human variant analyses further support the essential role of endogenous GIP signaling in maintaining bone mass and quality. Exogenous administration of GIP suppresses the bone-resorption marker C-terminal telopeptide of type I collagen (CTX) and increases the bone-formation marker procollagen type I N-terminal propeptide (P1NP) in healthy individuals, reflecting an acute shift toward reduced bone resorption and enhanced bone formation. Moreover, GIP confers protection against bone deterioration in multiple pathological conditions, including postmenopausal osteoporosis, inflammatory bone loss, obesity, and diabetes, etc., suggesting therapeutic potential beyond physiological contexts. Recent evidence also shows that GIP attenuates orthodontic tooth movement by limiting mechanically induced osteoclast activity, highlighting its broader skeletal actions. In this review, we summarize recent advances regarding the role of GIP in bone metabolism, integrating evidence from cellular studies, animal models and human investigations, and discuss future directions for GIP-based interventions. Full article

Periodontitis is a chronic non-communicable inflammatory disease in which oxidative stress plays an important role in tissue destruction and alveolar bone loss. Excessive production of reactive oxygen species disrupts redox homeostasis, activates inflammatory signaling pathways, and promotes regulated cell death processes such as pyroptosis and ferroptosis. The Nrf2/Keap1 pathway is a key regulator of antioxidant defense and cellular adaptation to redox imbalance. Impaired Nrf2 signaling has been associated with enhanced oxidative injury, NF-κB and NLRP3 inflammasome activation, osteoclast-driven bone resorption, and reduced regenerative capacity in periodontal tissues. Experimental studies suggest that Nrf2 activation can restore the redox balance and attenuate inflammation and bone destructive responses in a periodontal model. Moreover, therapeutic approaches involving phytochemicals, microbial-derived metabolites, and redox-responsive biomaterials have been reported to influence Nrf2-related signaling in experimental settings. However, the majority of the available evidence is derived from in vitro or animal studies, and the relevance of these findings to clinical periodontitis remains to be established. This review summarizes the current advances linking oxidative stress, redox signaling, cell death pathways, and bone remodeling with Nrf2 dysfunction in periodontitis and outlines the key mechanistic insights while highlighting the existing knowledge gaps. Full article

Recent studies support that hematopoietic stem cell (HSC)-derived myeloid dendritic cells, monocytes/macrophages (Mo/Mϕ), and osteoclast precursors (OCps) share common progenitor(s) during development. This occurs mainly through receptor activator of NF-κB ligand (RANKL) signaling via its cytoplasmic adaptor protein complex (TRAF6) to subsequent osteoclastogenesis for bone loss and/or remodeling. Presently, mounting new evidence suggests that erythro-myeloid progenitor (EMP)-derived macrophages (Mϕ) and HSC-derived monocytes (Mo) produce embryonic, fetal, and postnatal OCp pools (i.e., primitive OCp), pinpointing a complex network of multiple OCp developmental origins. However, their ontogenic developments, lineage interactions, and contributions to the alternative osteoclastogenesis—in contrast to overall bone remodeling or loss—remain elusive. Interestingly, studies have also elucidated the contributions of immature CD11c⁺ myeloid DC-like OCps to osteoclastogenesis, with or without the classical so-called Mo/Mϕ-derived OCp subsets, and described that CD11c⁺ myeloid DCs (mDCs) develop into functionally active OCs; meanwhile, the cytokine TGF-β mediates a stepwise regulation of de novo immature mDCs/OCps through distinct crosstalk(s) with IL-17, an unrecognized interaction featuring TRAF6^(−/−)CD11c⁺ mDDOCps that coexist and proficiently colocalize in the local environment to drive a bona fide route for alternative osteoclastogenesis in vivo. Collectively, new findings—critically hinged on progenitor osteoclastogenic pathways (primitive OCps, mDCs/OCps, osteomorphs, etc.) and involving classical and/or alternative routes to inflammation-induced bone loss—are discussed via the illustrated schemes. This review highlights plausible ontogenic vs. principal or alternative developmental paths and their consequential downstream effects. Full article

Bone remodeling is maintained through the coordinated actions of osteoblasts, osteoclasts, and osteocytes, among which osteocytes serve as major regulators of osteoclast-mediated bone resorption through the receptor activator of the nuclear factor-κB ligand (RANKL)–osteoprotegerin (OPG) signaling axis. While molecular signals regulating osteocytic RANKL-OPG expression are fairly understood, how post-transcriptional mechanisms impact osteocyte function remains poorly defined. HuR (human antigen R) encoded by Elavl1 (embryonic lethal abnormal vision-like 1), a ubiquitously expressed RNA-binding protein, is known for stabilizing AU-rich element-containing transcripts involved in inflammatory and stress responses; however, its role in osteocyte-derived bone resorption is unknown. In this study, we examined the effect of HuR loss on osteocyte–osteoclastogenesis. Short hairpin RNA (shRNA)-mediated HuR knockdown in MLO-Y4 osteocyte-like cells resulted in a significant increase in OPG mRNA and its protein expression, whereas RANKL levels remained unchanged, leading to a significantly reduced RANKL/OPG ratio. Both co-culture and conditioned-medium assays demonstrated that HuR-deficient osteocytes produced a markedly diminished osteoclastogenic environment. Actinomycin D chase experiments showed no alteration in OPG mRNA decay kinetics, and RNA immunoprecipitation (RIP)-PCR failed to detect HuR–OPG interactions, indicating that HuR regulates OPG expression through indirect mechanisms rather than mRNA binding. These findings identify HuR as an indirect regulator of osteocyte-derived OPG expression that impacts osteoclast differentiation and reveal a previously unrecognized mechanism by which HuR contributes to bone remodeling. Full article

Introduction: Non-invasive methods to modulate orthodontic tooth movement have gained interest, particularly those targeting inflammatory mediators such as IL-1β and TNF-α, which regulate osteoclast and osteoblast activity. High-frequency vibrations (HFV), including those delivered by sonic toothbrushes, have been proposed to influence these biological responses. The aim of the study is to assess whether sonic vibrations affect IL-1β and TNF levels in patients undergoing clear aligner therapy. Materials and Methods: Twenty Invisalign^® patients were evaluated. For each patient, one tooth received HFV via a 285 Hz sonic toothbrush (experimental), while the contralateral served as a control. Gingival crevicular fluid was sampled at baseline (T0), after one week without HFV (T1), and after one week with HFV (T2). Cytokines were measured by ELISA. Because data were non-normally distributed, non-parametric tests were applied. Results: No significant differences across T0–T2 were found within the HFV group. At T2, IL-1β levels were significantly lower in the HFV group (mean: 23.04; SD: ± 20.18) than in controls (mean: 44.44; SD: ± 47.14), which showed an IL-1β increase with orthodontic force alone. TNF-α levels remained near the ELISA detection limit. Conclusions: Sonic vibrations combined with clear aligners appear to reduce IL-1β secretion and local inflammation without adverse effects. Sonic toothbrushes provide a simple HFV delivery method, though larger studies are needed to confirm these findings. Full article

Despite metals currently being widely used in orthopedic surgery, their mechanical properties significantly differ from the surrounding tissues and organs, causing low biocompatibility. Biodegradable, non-toxic, and non-immunogenic materials seem to be more convenient for clinical implementation. Our research was aimed at the construction of a polylactide screw covered with collagen, nanohydroxyapatite, and polylactide, with a variant including silver nanowires for antibacterial properties, as well as the analysis of their physico-chemical and biological properties. Adherent human osteosarcoma cells (2T line) were shown to grow on the porous surface layers. A cytotoxicity assay using WST1 revealed the non-toxic nature of the coatings and showed an increase in cell adhesion and proliferation. Safety and efficacy were also evaluated in vivo with the coated screws implanted into the metatarsal bones of minipigs. Histological analysis at 29 and 58 days post-screw-implantation revealed that the coated samples accelerated bone tissue regeneration compared to uncoated controls. This was evidenced by a higher bone-to-granulation tissue ratio, reduced inflammatory cell counts, and increased osteoblast/osteoclast activity at the early stage during the initial days after implantation. The results confirm that the developed bioactive coatings enhance biocompatibility and osteointegration. Full article

The incretin hormone glucose-dependent insulinotropic polypeptide (GIP) promotes insulin secretion, lowers blood glucose levels, and is increasingly linked to bone remodeling. Native GIP is quickly inactivated by the enzyme dipeptidyl peptidase-4 (DPP-4), whereas (D-Ala²)GIP is a novel GIP analog engineered to resist DPP-4 degradation. Tumor necrosis factor-alpha (TNF-α), a key proinflammatory cytokine, promotes osteoclastogenesis and is notably upregulated during orthodontic tooth movement (OTM). This study aimed to evaluate the effects of (D-Ala²)GIP on TNF-α-induced osteoclast formation and bone resorption in vivo, as well as on OTM and related root resorption. Mice received daily supracalvarial injections of TNF-α with or without (D-Ala²)GIP for 5 days. The (D-Ala²)GIP-treated group showed significantly reduced osteoclast formation, bone resorption, and expression of osteoclastic markers TRAP and cathepsin K, compared to the group that received TNF-α alone. OTM was induced in mice by applying a nickel-titanium closed-coil spring, and mice were treated with either phosphate-buffered saline (PBS) or (D-Ala²)GIP every 2 days. After 12 days, the (D-Ala²)GIP-treated group showed significantly reduced tooth movement and fewer osteoclasts and odontoclasts on the compression side compared to the PBS control. These findings suggest that (D-Ala²)GIP inhibits OTM, potentially by suppressing TNF-α-driven osteoclastogenesis and bone resorption. Full article

The next frontier in postmenopausal osteoporosis management lies not in novel pharmacological agents, but in the systematic integration of mechanism-guided drug selection, fall prevention, and long-term adherence strategies into a unified patient-centered care model. This review is intended for clinicians and clinical researchers involved in the diagnosis, treatment, and long-term management of postmenopausal osteoporosis. We provide a mechanism-to-practice framework that explicitly maps each therapeutic class to the specific molecular pathway it targets: bisphosphonates inhibit osteoclast function downstream of RANKL activation; denosumab blocks RANKL directly at the cytokine level; romosozumab inhibits sclerostin to restore Wnt-mediated bone formation. This mechanistic foundation supports a risk-stratified treatment paradigm in which antiresorptives address accelerated remodeling in moderate-risk patients, while patients at very high fracture risk—characterized by severe bone deficit or recent fragility fractures—benefit from an anabolic-first approach followed by consolidation. Beyond drug selection, we examine the persistent treatment gap in which fewer than 20% of post-fracture patients receive therapy, arguing that fall prevention—responsible for >90% of hip fractures—and medication adherence deserve equal priority in clinical practice. We further analyze key controversies, including T-score- versus FRAX-based intervention thresholds, limitations of the trabecular bone score, cost-effectiveness constraints on anabolic-first sequencing, and evidence gaps in post-denosumab transition strategies. By synthesizing mechanistic insights, guideline recommendations, and critical appraisal of current limitations, this review offers not only an overview of existing knowledge but a coherent decision-support model aimed at improving fracture prevention through comprehensive, individualized care. Full article