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The Journal of Clinical Investigation Sep 2020Although the control of bone-resorbing osteoclasts through osteocyte-derived RANKL is well defined, little is known about the regulation of osteoclasts by osteocyte...
Although the control of bone-resorbing osteoclasts through osteocyte-derived RANKL is well defined, little is known about the regulation of osteoclasts by osteocyte death. Indeed, several skeletal diseases, such as bone fracture, osteonecrosis, and inflammation are characterized by excessive osteocyte death. Herein we show that osteoclasts sense damage-associated molecular patterns (DAMPs) released by necrotic osteocytes via macrophage-inducible C-type lectin (Mincle), which induced their differentiation and triggered bone loss. Osteoclasts showed robust Mincle expression upon exposure to necrotic osteocytes in vitro and in vivo. RNA sequencing and metabolic analyses demonstrated that Mincle activation triggers osteoclastogenesis via ITAM-based calcium signaling pathways, skewing osteoclast metabolism toward oxidative phosphorylation. Deletion of Mincle in vivo effectively blocked the activation of osteoclasts after induction of osteocyte death, improved fracture repair, and attenuated inflammation-mediated bone loss. Furthermore, in patients with osteonecrosis, Mincle was highly expressed at skeletal sites of osteocyte death and correlated with strong osteoclastic activity. Taken together, these data point to what we believe is a novel DAMP-mediated process that allows osteoclast activation and bone loss in the context of osteocyte death.
Topics: Animals; Bone Resorption; Lectins, C-Type; Membrane Proteins; Mice; Mice, Knockout; Necrosis; Osteoclasts; Osteocytes; RNA-Seq
PubMed: 32773408
DOI: 10.1172/JCI134214 -
Acta Pharmacologica Sinica Feb 2016Aconiti Lateralis Radix Preparata is a traditional Chinese medicine used to treat chronic arthritis and is highly effective against rheumatoid arthritis. However, the...
AIM
Aconiti Lateralis Radix Preparata is a traditional Chinese medicine used to treat chronic arthritis and is highly effective against rheumatoid arthritis. However, the effects of aconine, a derivative of aconitum alkaloids, on osteoclasts, which can absorb bone, remain unknown. Here, we investigated the effects of aconine on osteoclast differentiation and bone resorption in vitro.
METHODS
The viability of mouse leukemic monocyte/macrophage cell line RAW264.7 was measured using CCK-8 assays. Osteoclast differentiation was induced by incubation of RAW264.7 cells in the presence of RANKL, and assessed with TRAP staining assay. Bone resorption was examined with bone resorption pits assay. The expression of relevant genes and proteins was analyzed using RT-PCR and Western blots. The activation of NF-κB and nuclear factor of activated T-cells (NFAT) was examined using stable NF-κB and NFATc1 luciferase reporter gene systems, RT-PCR and Western blot analysis.
RESULTS
Aconine (0.125, 0.25 μmol/L) did not affect the viability of RAW264.7 cells, but dose-dependently inhibited RANKL-induced osteoclast formation and bone resorptive activity. Furthermore, aconine dose-dependently inhibited the RANKL-induced activation of NF-κB and NFATc1 in RAW264.7 cells, and subsequently reduced the expression of osteoclast-specific genes (c-Src, β3-Integrin, cathepsin K and MMP-9) and the expression of dendritic cell-specific transmembrane protein (DC-STAMP), which played an important role in cell-cell fusion.
CONCLUSION
These findings suggest that aconine inhibits RANKL-induced osteoclast differentiation in RAW264.7 cells by suppressing the activation of NF-κB and NFATc1 and the expression of the cell-cell fusion molecule DC-STAMP.
Topics: Aconitine; Adjuvants, Immunologic; Animals; Bone Resorption; Cell Differentiation; Down-Regulation; Membrane Proteins; Mice; NF-kappa B; NFATC Transcription Factors; Nerve Tissue Proteins; Osteoclasts; RANK Ligand; RAW 264.7 Cells
PubMed: 26592521
DOI: 10.1038/aps.2015.85 -
Nature Apr 2019Osteoclasts are multinucleated giant cells that resorb bone, ensuring development and continuous remodelling of the skeleton and the bone marrow haematopoietic niche....
Osteoclasts are multinucleated giant cells that resorb bone, ensuring development and continuous remodelling of the skeleton and the bone marrow haematopoietic niche. Defective osteoclast activity leads to osteopetrosis and bone marrow failure, whereas excess activity can contribute to bone loss and osteoporosis. Osteopetrosis can be partially treated by bone marrow transplantation in humans and mice, consistent with a haematopoietic origin of osteoclasts and studies that suggest that they develop by fusion of monocytic precursors derived from haematopoietic stem cells in the presence of CSF1 and RANK ligand. However, the developmental origin and lifespan of osteoclasts, and the mechanisms that ensure maintenance of osteoclast function throughout life in vivo remain largely unexplored. Here we report that osteoclasts that colonize fetal ossification centres originate from embryonic erythro-myeloid progenitors. These erythro-myeloid progenitor-derived osteoclasts are required for normal bone development and tooth eruption. Yet, timely transfusion of haematopoietic-stem-cell-derived monocytic cells in newborn mice is sufficient to rescue bone development in early-onset autosomal recessive osteopetrosis. We also found that the postnatal maintenance of osteoclasts, bone mass and the bone marrow cavity involve iterative fusion of circulating blood monocytic cells with long-lived osteoclast syncytia. As a consequence, parabiosis or transfusion of monocytic cells results in long-term gene transfer in osteoclasts in the absence of haematopoietic-stem-cell chimerism, and can rescue an adult-onset osteopetrotic phenotype caused by cathepsin K deficiency. In sum, our results identify the developmental origin of osteoclasts and a mechanism that controls their maintenance in bones after birth. These data suggest strategies to rescue osteoclast deficiency in osteopetrosis and to modulate osteoclast activity in vivo.
Topics: Animals; Animals, Newborn; Bone Development; Female; Genes, Recessive; Hematopoietic Stem Cells; Male; Mice; Osteoclasts; Osteopetrosis; Tooth Eruption
PubMed: 30971820
DOI: 10.1038/s41586-019-1105-7 -
Stem Cell Research & Therapy Dec 2019Aspirin has been demonstrated to promote osteoblast-mediated bone formation and inhibit osteoclast (OC)-mediated bone resorption. However, it remains unclear whether...
BACKGROUND
Aspirin has been demonstrated to promote osteoblast-mediated bone formation and inhibit osteoclast (OC)-mediated bone resorption. However, it remains unclear whether aspirin influences other immune cells during bone resorption. Dendritic cells (DCs), the most potent antigen-presenting cells, can also transdifferentiate into active OCs in the presence of receptor activator of nuclear factor-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). The effects of aspirin on DC-derived OCs (DDOCs) were investigated in the current study.
METHODS
Flow cytometry and mixed lymphocyte reaction (MLR) assays were used for DC identification. The proliferative capacity of DCs was determined by BrdU assays. Apoptosis was examined by flow cytometry. The osteoclastic potential of DCs was tested using tartrate-resistant acid phosphatase (TRAP) staining, western blotting, and reverse transcription polymerase chain reaction (RT-PCR). Western blotting was also used to examine signaling pathways. A mandibular bone defect model was established to assess the effect of aspirin on bone resorption.
RESULTS
Aspirin had no influence on the surface phenotype, proliferation, or apoptosis of DCs, though aspirin significantly inhibited osteoclast differentiation in RANKL-stimulated DCs. DC osteoclast differentiation was modulated by aspirin via the nuclear factor kappa B (NF-κB)/nuclear factor of activated T cell, cytoplasmic 1 (NFATc1) signaling pathway. Aspirin treatment also had favorable therapeutic effects on bone regeneration in the bone defect model, and the number of osteoclasts was decreased.
CONCLUSIONS
Aspirin inhibited RANKL-induced OC differentiation in DCs via the NF-κB pathway, downregulating expression of NFATc1. Aspirin treatment promoted bone regeneration by inhibiting DDOC activation in the early stages of inflammation in a rat mandibular bone defect model.
Topics: Animals; Apoptosis; Aspirin; Bone Diseases; Bone Regeneration; CD11c Antigen; Cell Differentiation; Dendritic Cells; Disease Models, Animal; Male; Mice; Mice, Inbred C57BL; NF-kappa B; NFATC Transcription Factors; Osteoclasts; RANK Ligand; Rats; Signal Transduction
PubMed: 31805984
DOI: 10.1186/s13287-019-1500-x -
International Journal of Molecular... Sep 2020Age related changes to the skeleton, such as osteoporosis, increase the risk of fracture and morbidity in the elderly population. In osteoporosis, bone remodeling... (Review)
Review
Age related changes to the skeleton, such as osteoporosis, increase the risk of fracture and morbidity in the elderly population. In osteoporosis, bone remodeling becomes unbalanced with an increase in bone resorption and a decrease in bone formation. Osteoclasts are large multinucleated cells that secrete acid and proteases to degrade and resorb bone. Understanding the molecular mechanisms that regulate osteoclast differentiation and activity will provide insight as to how hyper-active osteoclasts lead to pathological bone loss, contributing to diseases such as osteoporosis. Reversible modifications to the DNA such as histone acetylation, methylation, phosphorylation and ubiquitylation alters the access of transcriptional machinery to DNA and regulates gene expression and osteoclast differentiation and activity. It is critical for the management of bone related diseases to understand the role of these chromatin modifying proteins during osteoclast differentiation, as potential therapies targeting these proteins are currently under development.
Topics: Animals; Cell Differentiation; Epigenesis, Genetic; Histone Code; Humans; Osteoclasts; Osteoporosis; Protein Processing, Post-Translational
PubMed: 32992908
DOI: 10.3390/ijms21197080 -
Nihon Rinsho Men'eki Gakkai Kaishi =... 2017Osteoclasts are differentiated from precursors of the monocyte/macrophage lineage originated from bone marrow hematopoietic stem cells and are the sole... (Review)
Review
Osteoclasts are differentiated from precursors of the monocyte/macrophage lineage originated from bone marrow hematopoietic stem cells and are the sole bone-resorbing cells in the body. Osteoclast differentiation is thought to require M-CSF (macrophage colony-stimulating factor) and RANKL (receptor activator of nuclear factor kappa-B ligand) signaling. However, it has recently been proposed that under chronic inflammatory conditions, such as systemic autoimmune diseases (e.g., rheumatoid arthritis), an increase in inflammatory cytokine levels within joints induces pathological osteoclast differentiation, causing excessive bone resorption. In addition, the authors have reported that stimulating mouse bone marrow monocytes and human CD14 monocytes with combination of TNFα and IL-6 can induce differentiation of osteoclast-like cells, which are cells with bone resorption activity. In the present article, we discuss the mechanism of osteoclast differentiation of RANKL-independent bone-resorbing cells, using both data from the aforementioned report as well as the latest findings. Understanding the mechanisms underlying RANKL-independent, cytokine-mediated osteoclast differentiation could facilitate the development of novel therapies for inflammatory joint diseases.
Topics: Animals; Arthritis, Rheumatoid; Bone Resorption; Cell Differentiation; Cytokines; Drug Discovery; Humans; Inflammation; Inflammation Mediators; Interleukin-6; Macrophage Colony-Stimulating Factor; Mice; Molecular Targeted Therapy; Osteoclasts; RANK Ligand; Signal Transduction; Tumor Necrosis Factor-alpha
PubMed: 29238019
DOI: 10.2177/jsci.40.367 -
International Journal of Molecular... Aug 2020Multinucleation is a hallmark of osteoclast maturation. The unique and dynamic multinucleation process not only increases cell size but causes functional alterations... (Review)
Review
Multinucleation is a hallmark of osteoclast maturation. The unique and dynamic multinucleation process not only increases cell size but causes functional alterations through reconstruction of the cytoskeleton, creating the actin ring and ruffled border that enable bone resorption. Our understanding of the molecular mechanisms underlying osteoclast multinucleation has advanced considerably in this century, especially since the identification of DC-STAMP and OC-STAMP as "master fusogens". Regarding the molecules and pathways surrounding these STAMPs, however, only limited progress has been made due to the absence of their ligands. Various molecules and mechanisms other than the STAMPs are involved in osteoclast multinucleation. In addition, several preclinical studies have explored chemicals that may be able to target osteoclast multinucleation, which could enable us to control pathogenic bone metabolism more precisely. In this review, we will focus on recent discoveries regarding the STAMPs and other molecules involved in osteoclast multinucleation.
Topics: Animals; Cell Nucleus; Humans; Models, Biological; Osteoclasts; Receptors, Cell Surface; Signal Transduction
PubMed: 32784443
DOI: 10.3390/ijms21165685 -
Disease Models & Mechanisms May 2021Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation. Clinical manifestations... (Review)
Review
Autosomal recessive osteopetrosis (ARO) is a severe inherited bone disease characterized by defective osteoclast resorption or differentiation. Clinical manifestations include dense and brittle bones, anemia and progressive nerve compression, which hamper the quality of patients' lives and cause death in the first 10 years of age. This Review describes the pathogenesis of ARO and highlights the strengths and weaknesses of the current standard of care, namely hematopoietic stem cell transplantation (HSCT). Despite an improvement in the overall survival and outcomes of HSCT, transplant-related morbidity and the pre-existence of neurological symptoms significantly limit the success of HSCT, while the availability of human leukocyte antigen (HLA)-matched donors still remains an open issue. Novel therapeutic approaches are needed for ARO patients, especially for those that cannot benefit from HSCT. Here, we review preclinical and proof-of-concept studies, such as gene therapy, systematic administration of deficient protein, in utero HSCT and gene editing.
Topics: Consensus; Gene Expression Regulation; Genes, Recessive; Humans; Osteoclasts; Osteopetrosis; Practice Guidelines as Topic
PubMed: 33970241
DOI: 10.1242/dmm.048940 -
Molecules (Basel, Switzerland) Apr 2021Although the anti-tumor and anti-infective properties of β-glucans have been well-discussed, their role in bone metabolism has not been reviewed so far. This review... (Review)
Review
Although the anti-tumor and anti-infective properties of β-glucans have been well-discussed, their role in bone metabolism has not been reviewed so far. This review discusses the biological effects of β-glucans on bone metabolisms, especially on bone-resorbing osteoclasts, which are differentiated from hematopoietic precursors. Multiple immunoreceptors that can recognize β-glucans were reported to be expressed in osteoclast precursors. Coordinated co-stimulatory signals mediated by these immunoreceptors are important for the regulation of osteoclastogenesis and bone remodeling. Curdlan from the bacterium negatively regulates osteoclast differentiation in vitro by affecting both the osteoclast precursors and osteoclast-supporting cells. We also showed that laminarin, lichenan, and glucan from baker's yeast, as well as β-1,3-glucan from inhibit the osteoclast formation in bone marrow cells. Consistent with these findings, systemic and local administration of β-glucan derived from and suppressed bone resorption in vivo. However, zymosan derived from stimulated the bone resorption activity and is widely used to induce arthritis in animal models. Additional research concerning the relationship between the molecular structure of β-glucan and its effect on osteoclastic bone resorption will be beneficial for the development of novel treatment strategies for bone-related diseases.
Topics: Animals; Bone Regeneration; Bone Resorption; Bone and Bones; Cartilage; Cell Differentiation; Glucans; Humans; Immunomodulation; Osteoclasts; Osteogenesis; Receptors, Immunologic
PubMed: 33915775
DOI: 10.3390/molecules26071982 -
Biomedicine & Pharmacotherapy =... Oct 2023Bone loss is a major issue for patients with osteoporosis, arthritis, periodontitis, and bone metastasis; however, anti-resorption drugs used to treat bone loss have...
Bone loss is a major issue for patients with osteoporosis, arthritis, periodontitis, and bone metastasis; however, anti-resorption drugs used to treat bone loss have been linked to a variety of adverse effects. Helminthostachys zeylanica (L.) Hook, belonging to the family Ophioglossaceae, is commonly used in traditional Chinese medicine to treat inflammation and liver problems. In the current study, ugonin L extracted from H. zeylanica was shown to reduce the receptor activator of nuclear factor kappa beta ligand (RANKL)-induced osteoclastogenesis in RAW264.7 cells in a concentration-dependent manner. Ugonin L treatment also inhibited the mRNA expression of osteoclast markers. Ugonin L was also shown to promote cell apoptosis in mature osteoclasts and suppress RANKL-induced ERK, p38, JNK, and NF-κB activation. Taken together, ugonin L appears to be a promising candidate for the development of novel anti-resorption therapies.
Topics: Humans; Apoptosis; Bone Diseases, Metabolic; NF-kappa B; Osteoclasts; Osteogenesis; Signal Transduction; Drugs, Chinese Herbal; RANK Ligand
PubMed: 37651802
DOI: 10.1016/j.biopha.2023.115392