Background Osteoclast-mediated bone resorption drives osteoporosis, a prevalent skeletal disorder with significant clinical and socioeconomic burden, yet the upstream molecular mechanisms controlling osteoclast differentiation remain incompletely defined. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a known oncogenic regulator, but its role in bone metabolism and osteoclast biology has not been explored. Methods We used RANKL-induced mouse bone marrow macrophages (BMMs) to model osteoclast differentiation in vitro, with adenoviral-mediated gain- or loss-of-function of CIP2A. Mechanistic investigations included immunoprecipitation-mass spectrometry (IP-MS), co-immunoprecipitation (co-IP), ubiquitination assays, cycloheximide (CHX) chase analysis, RNA sequencing (RNA-seq), and chromatin immunoprecipitation sequencing (ChIP-seq). For translational assessment, in vivo, we employed an ovariectomy (OVX)-induced osteoporosis mouse model with systemic adeno-associated virus (AAV)-mediated gene manipulation as well as pharmacological inhibition using the CIP2A small-molecule inhibitor TD52. Results CIP2A expression was dynamically upregulated during RANKL-induced osteoclastogenesis. CIP2A promoted osteoclast formation, actin ring assembly, and bone resorptive activity in vitro, without affecting osteoblast differentiation. Mechanistically, CIP2A acted as a molecular scaffold that recruited the deubiquitinase OTUD4 to stabilize high mobility group A1 (HMGA1) by preventing its ubiquitination and proteasomal degradation. Stabilized HMGA1 translocated to the nucleus. Integrated multi-omics analyses (RNA-seq and HMGA1 ChIP-seq) identified c-Myc as a direct transcriptional target of HMGA1, which bound distal regulatory elements to enhance c-Myc transcription. Functional experiments further revealed that c-Myc formed a positive feedback loop with the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway, sustaining osteoclast activity. In OVX mice, c-Myc overexpression or AKT activation partially rescued the bone loss induced by CIP2A knockdown. Importantly, pharmacological inhibition of CIP2A with TD52 suppressed osteoclast differentiation and bone resorption both in vitro and in vivo, without causing major organ toxicity or affecting osteoblast function. Conclusions Our findings identify a novel CIP2A–OTUD4–HMGA1–c-Myc–PI3K/AKT regulatory axis that drives pathological osteoclastogenesis and bone loss. CIP2A represents a promising druggable target for osteoporosis and related osteolytic diseases. As a potential first-in-class CIP2A inhibitor, TD52 merits further preclinical development for the treatment of postmenopausal osteoporosis.

Spinal cord injury remains a devastating condition with no curative therapies currently available. Existing treatments are largely limited to symptomatic management and fail to address the complex pathophysiological microenvironment that hinders neural regeneration. Hydrogels with appropriate conductive properties offer potential new therapeutic avenues for treating spinal cord injury and can appropriately adjust the pathological and electrophysiological microenvironment at the injury site. Exosomes secreted by human umbilical cord mesenchymal stem cells, which can cross the blood-spinal cord barrier, have effects on repairing tissue damage and promoting cell differentiation. Here, we developed a conductive hydrogel, integrating gelatin methacrylate with polyaniline and exosomes derived from human umbilical cord mesenchymal stem cells, which exhibits excellent biocompatibility, thereby facilitating neuronal repair by activating the Wnt/β-catenin signaling pathway and improving the pathological environment at the lesion site. This hydrogel can modulate the differentiation of neural stem cells into neurons and oligodendrocytes in vitro, promoting the proliferation of neural cells. In vivo, it can improve the motor and physiological functions of rats with spinal cord injury by inhibiting scar formation and promoting nerve and myelin regeneration. The novel conductive composite hydrogel, developed in the present study and capable of loading exosomes, offers a new therapeutic strategy for spinal cord injury with promising application prospects.

Osteoporosis is a systemic skeletal disorder characterized by reduced bone mass, compromised bone microstructure, and an increased risk of fractures, primarily due to excessive osteoclast-mediated bone resorption relative to osteoblast-mediated bone formation. While current anti-osteoporosis drugs, such as bisphosphonates and denosumab, predominantly focus on reducing bone resorption, osteoanabolic approaches are essential for restoring bone microarchitecture and ultimately reducing fracture risk. Traditional Chinese medicines (TCMs) and their active ingredients have long been used in China for osteoporosis prevention and treatment. This review provides a comprehensive evaluation of the effects and molecular mechanisms of 65 natural products across 24 categories on osteoblast-mediated bone formation. These compounds promote bone formation by regulating key transcription factors (RUNX2 and Osterix) and signaling pathways, including WNT/β-catenin, bone morphogenic protein (BMP), mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase/protein kinase B (PI3K/AKT), oxidative stress, autophagy, and epigenetic regulation. Notably, certain natural products [e.g., icariin (ICA)] exert their effects through multiple targets and pathways. Many of these natural products have demonstrated significant therapeutic efficacy in animal models, such as ovariectomized (OVX) mice. Our findings suggest that natural products with kidney-tonifying, anti-inflammatory, and antioxidant properties, as well as those inhibiting adipocyte differentiation, may hold promise for osteoporosis treatment. Additionally, we highlight current research gaps and propose future directions, including high-throughput screening and validation in diverse animal models, development of novel bone-targeting delivery systems, and identification of natural compounds targeting osteocytes.

Balancing mechanical strength, controllability of degradation and bioactivities, remains a significant challenge for absorbable barrier membranes in guided bone regeneration (GBR) for the treatment of bone defects. To overcome these limitations, a novel absorbable synthetic PGA-TMC/PTMC/nHA (PGTTH) barrier membrane was developed using electrospinning technology to prolong barrier duration and promote rapid bone repair. The PGTTH membrane integrates three functional components in a one-step fabrication process: a poly (glycolic acid-co-trimethylene cabonate) (PGA-TMC) copolymer matrix providing mechanical integrity, polytrimethylene carbonate (PTMC) imparting flexibility and a slow, linear degradation profile to ensure long-term structural stability, nano-hydroxyapatite (nHA) delivering bioactive ions to enhance osteogenesis and biomineralization. To systematically evaluate the performance of the PGTTH membrane, mechanical characterization and in vitro degradation tests confirmed that the membrane exhibits appropriate mechanical properties and a slow degradation profile, thereby demonstrating its ability to maintain structural space over an extended period. Furthermore, in vitro and in vivo studies demonstrated that the PGTTH membrane significantly promotes cell adhesion, proliferation, and osteogenic differentiation. In conclusion, this study not only presents a promising GBR barrier membrane material with potential for clinical application, but also offers a new design strategy and experimental basis for developing absorbable membranes that combine excellent barrier functionality with osteoinductive capacity.

ObjectiveThis study investigated molecular drivers of AD-associated peripheral immune dysregulation to identify pathogenic genes and therapeutic targets for precision diagnosis and intervention.MethodsA large-scale GWAS meta-analysis (n = 894,710) was performed, followed by two-sample Mendelian randomization (MR) using multi-tissue cis-eQTL data to identify putative causal genes. Immune response differential genes (IRDGs) were defined from AD peripheral blood transcriptomes and the MSigDB database. A three-step summary-data-based MR framework integrating blood cis-eQTLs and cis-mQTLs was applied to prioritize causal genes and epigenetic regulatory elements. Findings were validated through colocalization analysis, PBMC scRNA-seq and blood-tissue TWAS. Multi-dimensional clinical validation was performed in the ADNI cohort encompassing gene expression, CSF biomarkers, cognitive measures, immune cell profiles, survival analysis, and plasma proteomics, with cross-cohort transcriptomic replication in AddNeuroMed.ResultsTwo-sample MR identified eight putative AD pathogenic genes. The three-step SMR and colocalization analysis prioritized five candidate causal genes, whose differential expression in immunocytes was confirmed by scRNA-seq and independently replicated. In the ADNI cohort, PTK2B expression was elevated in AD (ANOVA P = 0.0023), inversely correlated with MMSE (r = −0.164, P = 0.017), and predictive of MCI-to-AD conversion (Cox HR = 1.741, P = 0.050), with independent replication in AddNeuroMed (FDR P = 3.56 × 10−4). PLEKHA1 and PTK2B expression were strongly associated with peripheral neutrophil and lymphocyte proportions (P < 10−7), and PLEKHA1 correlated with CSF total tau (partial r = 0.102, P = 0.036). The prioritized probe cg19863426 at the PLEKHA1 promoter showed progressive hypermethylation across the CN-MCI-AD continuum (F = 3.45, P = 0.032) and was inversely correlated with PLEKHA1 mRNA (r = −0.33, P = 2.68 × 10−¹²).ConclusionIntegrating GWAS, multi-omics Mendelian randomization, single-cell transcriptomics, transcriptome-wide association study, and clinical cohort validation, this study identified peripheral immune causal genes for AD whose blood transcriptomic and epigenetic signatures track with CSF pathology, cognitive decline, and disease progression, supporting their translational potential for early diagnosis and therapeutic development.

BACKGROUND:Excessive osteoclastogenesis is a pivotal pathological process in osteoporosis. Identifying compounds that can effectively inhibit osteoclastogenesis without toxicity is of great therapeutic interest. Handelin, a guaianolide dimer from Chrysanthemum indicum and other Chrysanthemum spp., possesses known anti-inflammatory and antioxidant properties, yet its role in osteoclastogenesis remains unclear. This study aims to investigate the role and mechanism of Handelin in osteoclastogenesis. METHODS:The effects of Handelin on osteoclast differentiation and function were assessed using Cell Counting Kit-8 (CCK-8), tartrate-resistant acid phosphatase (TRAP) and F-actin ring staining, bone pit assays, real-time quantitative PCR (RT-qPCR), and western blot in vitro. An ovariectomized (OVX) mouse model was employed for in vivo validation, evaluated by Micro-CT, histological staining, and ELISA assays. RNA sequencing (RNA-seq), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) analysis, molecular docking, surface plasmon resonance (SPR), cellular thermal shift assay (CETSA), co-immunoprecipitation, immunofluorescence, and autophagy flux assays were employed for mechanistic investigation. Rescue experiments were conducted using recombinant lipocalin-2 (rLCN2) protein and sequestosome-1 (p62) overexpression. RESULTS:Handelin potently inhibited RANKL-induced osteoclast differentiation and bone resorption in vitro without cytotoxicity and alleviated OVX-induced bone loss in vivo. RNA-seq revealed Handelin downregulated LCN2 and activated autophagy while inhibiting the NF-κB pathway. Handelin directly bounded LCN2, reduced its expression at both mRNA and protein levels in cells and tissues, and restored autophagic flux, weakening the interaction between p62-TRAF6 to block NF-κB signaling. The anti-osteoclastogenic effects of Handelin were partially reversed by rLCN2 supplementation or p62 overexpression. Notably, Handelin did not impair osteogenic differentiation. CONCLUSION:This study identifies Handelin as a novel inhibitor of osteoclastogenesis that targets the LCN2-autophagy pathway and suppresses NF-κB signaling, highlighting its potential as a therapeutic agent for osteoporosis and related bone diseases.

Inflammation driven by the innate immune response plays a crucial role in osteoarthritis (OA) pathogenesis, yet the underlying mechanisms remain incompletely understood. Moreover, current antiinflammatory therapies primarily offer symptomatic relief without altering disease progression. Nucleotide-binding oligomerization domain 2 (NOD2) is an intracellular pattern recognition receptor that detects a broad range of microbial and damage-associated stimuli and has been implicated in several inflammatory conditions. In this study, we investigated the role of NOD2 in OA-associated inflammation and cartilage degradation. Elevated NOD2 expression was observed in both human and mouse osteoarthritic cartilage. Conditional KO of Nod2 in chondrocytes suppressed inflammation-induced catabolic responses in vitro and protected against cartilage degradation in mouse OA models. Mechanistically, we identified tumor necrosis factor receptor–associated factor 6 (TRAF6) as a key downstream mediator through which NOD2 promotes chondrocyte catabolism. Furthermore, we showed that pharmacological inhibition of NOD2 using 2 independent small-molecule inhibitors significantly attenuated OA progression in vivo. Collectively, these findings establish NOD2 as a critical regulator of OA-associated inflammation and cartilage degradation, and they highlight its potential as a therapeutic target for disease-modifying OA treatment.

As the global population ages, there is an increasing prevalence of spinal cord injury (SCI) among elderly individuals, accompanied by significant challenges in treatment and recovery. Age-related conditions, such as osteoporosis, muscle atrophy, and impaired balance, predispose older adults to falls and traumatic injuries, leading to worse neurological outcomes compared to younger patients. SCI pathophysiology consists of two phases: the initial mechanical injury and the secondary injury that involves a cascade of pathological events, including ischemia, apoptosis, and neuronal cell death. Chronic neuroinflammation has emerged as a central factor in driving long-term damage after SCI, particularly in older people, where immune senescence and a decreased ability to resolve inflammation contribute to persistent, unresolved inflammation. This prolonged inflammatory state further impedes neural regeneration and functional recovery. Aged animal models have revealed that chronic neuroinflammation is exacerbated by sustained activation of microglia and astrocytes, the infiltration of peripheral immune cells, and the secretion of pro-inflammatory cytokines, creating a proinflammatory microenvironment that hinders repair. Furthermore, ageing-related factors such as immunosenescence, autophagy dysfunction, and mitochondrial abnormalities exacerbate inflammation, establishing a vicious injury cycle. Despite promising studies targeting inflammation in young SCI models, there is a critical need for age-specific therapeutic approaches for elderly SCI patients. This review explores the mechanisms of chronic inflammation in aged SCI, examines key cellular mediators, and discusses potential therapeutic strategies, including pharmacological treatments, gene therapy, exosome-based interventions, and rehabilitation. Focusing on age-related differences in inflammation and healing, this work aims to provide a foundation for precision medicine tailored to the ageing population with SCI, ultimately improving clinical outcomes and quality of life for elderly patients.

Spinal cord injury (SCI) is a devastating condition with limited self-repair capacity, resulting in long-term disabilities. Endogenous neural stem cells (eNSCs), which are present in the adult central nervous system (CNS), hold significant potential for repairing neural damage following SCI. These cells can proliferate, migrate to the injury site, and differentiate into various neural cell types, including neurons and glial cells. However, after SCI, eNSCs predominantly differentiate into astrocytes, with minimal neuronal differentiation, thereby hindering effective neural regeneration. This review summarizes the key mechanisms underlying the differentiation of eNSCs into neurons, focusing on the molecular signaling pathways that regulate their fate, including the Notch, Wnt/β-catenin, Sonic Hedgehog, and PI3K/Akt pathways. It also discusses the microenvironment’s role, including factors such as hypoxia, extracellular matrix components, and inflammatory cytokines, which influence eNSCs differentiation. The review also highlights potential therapeutic strategies to enhance eNSCs differentiation into neurons, including biomaterials and multimodal approaches that combine pharmacological, physical, and tissue engineering techniques. Despite progress in understanding eNSCs biology and signaling mechanisms, challenges remain in optimizing therapeutic strategies for SCI repair. Future research should focus on overcoming these limitations, emphasizing refining treatment timing, drug delivery systems, and the development of personalized therapies to promote effective neural regeneration and functional recovery after SCI.

Alzheimer's disease is a neurodegenerative disorder that predominantly affects the elderly and is characterized by complex pathogenesis. Within the unified framework of the ANT, the introduction of B (the disruption of the blood-brain barrier) facilitates communication between the brain and the periphery through the blood-brain barrier. In this context, inflammatory factors act as a bridge, and the neuroinflammation hypothesis is gaining increasing acceptance. This hypothesis involves the abnormal activation of microglia, the release of inflammatory mediators, and damage to astrocytes, which leads to blood-brain barrier impairment and subsequently triggers systemic inflammation. Bone health is associated with conditions such as osteoporosis, osteoarthritis, rheumatoid arthritis, and periodontitis. This hypothesis establishes a link between Alzheimer's disease and bone health. The present article aims to construct an inflammatory bridge between brain and bone health by summarizing the shared mechanisms between the two, specifically focusing on age-related NLRP3-induced pyroptosis, advanced glycation end products, oxidative stress, macrophage autophagy and lysosomal function, and calcium ion dysregulation. Additionally, it reviews the latest therapeutic approaches to explore potential clinical treatments related to the connection between Alzheimer's disease and bone health through these shared mechanisms.

Ischemic stroke (IS) has a high mortality rate. Multiplexed detection of IS core biomarkers is of great significance to early diagnosis and personalized treatment of IS patients. Whether pericytes, a key component of the neurovascular unit and blood-brain barrier located on the capillary wall, could serve as a promising biomarker for IS is to be explored. Herein, we observed a significant upregulation of inflammatory and apoptotic factors, such as MMP9, in pericytes subjected to in vitro ischemia. By transfecting pericytes with ASK1-shRNA to inhibit ASK1 expression, we noted reduced levels of inflammatory and apoptotic markers, including MMP9, as well as enhanced pericyte contraction and migration, thereby preserving the integrity of the blood-brain barrier. Additionally, ELISA assays conducted using plasma samples from patients with varying NIHSS scores revealed statistically significant concentrations of PDGFRβ and MMP9. Furthermore, we developed a highly sensitive and specific quantitative detection method for PDGFRβ and MMP9 based on fluorescence sensor technology. This novel detector exhibits high sensitivity, repeatability, and stability, enabling precise dual detection. Thus, the results suggest the great potential of the detection of PDGFRβ and MMP9 for early diagnosis of IS and prognosis prediction of the disease.

BACKGROUND:Spinal cord injury (SCI) is a destructive neuropathological condition. Cinnamaldehyde (CA), a major bioactive component in Cinnamon essential oil, is known for its neuroprotective effects by inhibiting neuroinflammation, oxidative stress, and apoptosis. However, CA specific role in SCI remains unclear. The purpose of this study was to examine the impact of CA on SCI. METHODS:We established a rat model of SCI and assessed nerve damage in rats using the Basso-Beattie-Bresnahan (BBB) locomotion scale, inclined plane test and Tarlov Scale. Neuronal loss was evaluated with Nissl and NeuN staining. Apoptotic damage was assessed using TUNEL staining and caspase3 analysis. The level of M1-type microglia activation was explored using Iba1. Additionally, TNF-α and IL-Iβ concentrations were measured to examine inflammation. Poly (ADP-ribose) polymerase (PARP) and proliferating cell nuclear antigen (PCNA) were used to assess DNA damage. RESULTS:The results demonstrated that CA effectively improves behavioral scores measured by the BBB assay, inclined plane test, and Tarlov trial after SCI. NeuN and Nissl staining showed that CA significantly increases the number of NeuN-stained neurons and Nissl bodies. Apoptosis detection revealed that CA markedly reduces caspase3 production and the number of TUNEL-positive cells. Moreover, CA not only reduced Iba1 levels but also significantly decreased the production of TNF-α and IL-Iβ. Additionally, CA notably decreased PARP levels and promoted PCNA expression. CONCLUSIONS:CA regulates pathways involved in anti-neuroinflammation, anti-apoptosis, and DNA repair to improve neurological deficits and pathological conditions after SCI. CA therapeutic effect of CA may depend on the dosage.

Tau protein is enriched in neuronal axons, it functions as a stabilizer of axonal transportation. Hyperphosphorylation of Tau in the brain results in early-onset Alzheimer's disease (AD), causes remarkable bone loss. Notably, pathological Tau leads to the loss of specific physiological Tau that exaggerates Tau toxicity. However, little was known about the physiological role of Tau in bone homeostasis although it's rarely expressed in peripheral tissues. Here, we provided evidence for brain Tau's role in promoting bone formation. Tau knockout (Tau-/-) mice showed smaller body size and exhibited osteoporotic-like deficit, including reduced trabecular and cortical bone mass, especially in young male Tau-/- mice. Such a deficit is likely due to a decrease in osteoblast (OB)-mediated bone formation, as little change in bone resorption in Tau-/- mice. Further mechanistic studies showed increased PPARγ signaling in the brain of Tau-/- mice, which contributed to chemerin release and CMKLR1upregulation in Tau-/- mice brain. Chemerin neutralization remarkably restored osteogenesis potential. Furthermore, reduced repressive H3K9me2 in Tau-/- mice brain led to decreased enrichment of H3K9me2 at PPARγ promoter and thus increased chemerin production. Moreover, PPARγ inhibitor GW9662 significantly reversed the osteoporotic phenotype of Tau-/- mice. Our results implicated brain Tau acting as a dominant positive regulator in bone mass, and unveiled a potential clinical value of PPARγ inhibition in treatment of AD-associated osteoporotic deficits.

Total Flavonoids of Rhizoma Drynariae (TFRD) possess the ability to enhance bone regeneration by promoting angiogenesis-osteogenesis coupling, but the underlying mechanisms remain poorly understood. This study aimed to investigate the influence of TFRD on the coordination of osteogenic and pro-angiogenic properties of bone marrow mesenchymal stem cells (BMSCs) during long bone regeneration and further elucidate the underlying mechanism. We initially assessed pharmacological effects of TFRD in mouse monocortical tibial defect (MTD) model by utilizing micro-CT, histopathology and immunofluorescence imaging. Subsequently, we extracted BMSCs from TFRD-treated mice and characterized the regulatory effects of TFRD on the behavior of BMSCs. We observed that TFRD treatment increased skeletal parameters, osteoblast number, vessel volume and perivascular osteoprogenitor population within the callus. In vitro analyses revealed that TFRD promoted the proliferation and osteogenic differentiation of BMSCs. Additionally, BMSC-conditioned medium from TFRD-treated mice enhanced the migration, proliferation and tube formation of endothelial cells (ECs) under hypoxia. TFRD increased the expression level of HIF-1α and its target genes in callus and hypoxia-cultured ECs. The results of YAP1/TAZ interference in ECs by using siRNA indicated that the enhancement of HIf-1α was through YAP1/TAZ inhibition. Our findings suggest that YAP1/TAZ/ HIf-1α pathways involved in indirect regulation of TFRD on angiogenesis through BMSCs paracrine pathways.

To analyze dynamic patterns of arterial carbon dioxide partial pressure (PaCO₂) using latent class growth analysis in acute brain injury patients and investigate their associations with 28-day ICU mortality and 60-day in-hospital mortality. This retrospective study utilized the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. We applied latent class growth analysis to analyze PaCO₂ dynamic patterns during the first 72 h after ICU admission in adult patients with acute brain injury. Associations between trajectories and outcomes were evaluated using Cox proportional hazards models. Among the included acute brain injury patients (n = 1,145), three distinct PaCO₂ trajectories were identified: persistent hypocapnia pattern (23.7%), normal-mild regulation pattern (65.9%), and hypercapnia improvement pattern (10.5%). Cox proportional hazards regression analysis revealed that, compared with the normal-mild regulation pattern, the persistent hypocapnia pattern was significantly associated with higher risk of 28-day ICU mortality (HR = 1.28, 95% CI: 1.02-1.60) and 60-day in-hospital mortality (HR = 1.28, 95% CI: 1.03-1.59) after adjusting for confounding factors. The hypercapnia improvement pattern demonstrated a potentially protective association. This study identified distinct patterns of PaCO₂ dynamic changes in acute brain injury patients. Our analysis demonstrated that persistent hypocapnia was associated with higher risk of 28-day ICU and 60-day in-hospital mortality, while the hypercapnia improvement pattern showed potentially protective association. These results suggest the complexity of PaCO₂ management and the need for more individualized respiratory management strategies.

Ischemic stroke is one of the leading causes of death and severe disability. The overproduction of reactive oxygen species (ROS) after ischemic injury causes a series of inflammatory reactions, which is considered to be the key factor in aggravating brain injury. However, the current clinical drug treatment effect is not satisfactory. Therefore, ROS scavengers that can remove excess ROS production have great therapeutic potential. Nanoenzymes with potent antioxidant stress and anti-inflammatory properties have the potential to treat ischemic stroke. Herein, we used a Prussian blue nanoenzyme (PBzyme) to study the treatment of ischemic stroke. The comprehensive effects of PBzyme on ROS in vivo and in vitro were investigated. Pbzyme inhibited the activation of macrophages and the release of inflammatory factors in the brain, promoted the polarization of microglia to M2, inhibited neuronal apoptosis, and promoted the recovery of neurological function after ischemic stroke. This research may provide a promising application for nanoenzymes to treat brain diseases.

Fatty amide hydrolase (FAAH) is a key degradation enzyme of the endocannabinoid system, mainly responsible for the hydrolysis of arachidonic acid ethanolamine (AEA). Previous investigations have shown that FAAH is involved in a series of biological processes, such as inflammation, immune regulation, and transmembrane signal transduction of neurons. Endogenous cannabinoids and cannabinoid receptors have been reported to participate in the regulation of bone homeostasis by regulating the differentiation of osteoblasts and osteoclasts. We hypothesized that FAAH may play an important role in osteoclastogenesis based on the above evidence. The present study found that the FAAH expression was increased at both mRNA and protein levels during RANKL-induced osteoclastogenesis. Pharmacological and genetic inhibition of FAAH in bone marrow-derived macrophages (BMMs) inhibited osteoclastogenesis, F-actin ring formation, bone resorption, and osteoclast-specific gene expression in vitro. Moreover, intragastric administration of the FAAH inhibitor PF-04457845(PF) ameliorated ovariectomy (OVX)-induced bone loss in mice. Further investigation revealed that nuclear factor kappa B (NF-kappa B) and mitogen-activated protein kinase (MAPK) pathways were inhibited by PF treatment and FAAH knockdown. RNAseq indicated that the IL17 pathway was blocked by PF, and administration of recombinant murine IL17 protein could partially restore osteoclastogenesis and activate NF-kappa B and MAPK pathways. To sum up, our findings demonstrate that targeting FAAH could be a promising candidate strategy for treating osteoclast-related diseases, especially osteoporosis.

Osteosarcoma (OS) is one of the most common primary bone malignancy. Combining chemotherapy and surgical treatment significantly improved clinical outcomes for osteosarcoma patients. Osteosarcoma stem cells (OSCs) are often more malignant than differentiated cancer cells and are a key determinant of responses to chemotherapy and radiation therapy, therefore, the removal of OSCs could be an effective therapeutic strategy. Myxoprotein 1 (MUC1) is aberrantly overexpressed in many human cancers and it promotes cancer stemness through activation of pluripotency networks. In this study, we observed elevated MUC1 in osteosarcoma and a depressed prognosis in patients with high MUC1 expression profiles. Our observations also revealed that MUC1 promoted OS stemness and tumor metastasis both in vivo and in vitro. These data led us to hypothesize that MUC1 may be a therapeutic target for patients with OS.

Osteoporosis, characterized by over-production and activation of osteoclasts, has become a major health problem especially in elderly women. In our study, we first tested the effect of Caudatin (Cau) in osteoclastogenesis, which is separated from Cynanchum auriculatum as a species of C-21 steroidal glyosides. The results indicated that Cau suppressed osteoclastogenesis in a time- and dose-dependent manner in vitro. Mechanistically, Cau was identified to inhibit NF-κB signaling pathway via modulation of KIF11-mediated mTORC1 activity. In vivo, by establishing an ovariectomized (OVX) mouse model to mimic osteoporosis, we confirmed that Cau treatment prevented OVX-induced bone loss in mice. In conclusion, we demonstrated that Cau inhibited NF-κB signaling pathway via modulation of KIF11-mediated mTORC1 activity to suppress osteoclast differentiation in vitro as well as OVX-induced bone loss in vivo. This provides the possibility of a novel prospective drug for osteoporosis remedies.