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Autophagy Sep 2023The skeletal system is the basis of the vertebral body composition, which affords stabilization sites for muscle attachment, protects vital organs, stores mineral ions,...
The skeletal system is the basis of the vertebral body composition, which affords stabilization sites for muscle attachment, protects vital organs, stores mineral ions, supplies places to the hematopoietic system, and participates in complex endocrine and immune system. Not surprisingly, bones are constantly reabsorbed, formed, and remodeled under physiological conditions. Once bone metabolic homeostasis is interrupted (including inflammation, tumors, fractures, and bone metabolic diseases), the body rapidly initiates bone regeneration to maintain bone tissue structure and quality. Macroautophagy/autophagy is an essential metabolic process in eukaryotic cells, which maintains metabolic energy homeostasis and plays a vital role in bone regeneration by controlling molecular degradation and organelle renewal. One relatively new observation is that mesenchymal cells, osteoblasts, osteoclasts, osteocytes, chondrocytes, and vascularization process exhibit autophagy, and the molecular mechanisms and targets involved are being explored and updated. The role of autophagy is also emerging in degenerative diseases (intervertebral disc degeneration [IVDD], osteoarthritis [OA], etc.) and bone metabolic diseases (osteoporosis [OP], osteitis deformans, osteosclerosis). The use of autophagy regulators to modulate autophagy has benefited bone regeneration, including MTOR (mechanistic target of rapamycin kinase) inhibitors, AMPK activators, and emerging phytochemicals. The application of biomaterials (especially nanomaterials) to trigger autophagy is also an attractive research direction, which can exert superior therapeutic properties from the material-loaded molecules/drugs or the material's properties such as shape, roughness, surface chemistry, etc. All of these have essential clinical significance with the discovery of autophagy associated signals, pathways, mechanisms, and treatments in bone diseases in the future. Δψm: mitochondrial transmembrane potential AMPK: AMP-activated protein kinase ARO: autosomal recessive osteosclerosis ATF4: activating transcription factor 4 ATG: autophagy-related β-ECD: β-ecdysone BMSC: bone marrow mesenchymal stem cell ER: endoplasmic reticulum FOXO: forkhead box O GC: glucocorticoid HIF1A/HIF-1α: hypoxia inducible factor 1 subunit alpha HSC: hematopoietic stem cell HSP: heat shock protein IGF1: insulin like growth factor 1 IL1B/IL-1β: interleukin 1 beta IVDD: intervertebral disc degradation LPS: lipopolysaccharide MAPK: mitogen-activated protein kinase MSC: mesenchymal stem cell MTOR: mechanistic target of rapamycin kinase NP: nucleus pulposus NPWT: negative pressure wound therapy OA: osteoarthritis OP: osteoporosis PTH: parathyroid hormone ROS: reactive oxygen species SIRT1: sirtuin 1 SIRT3: sirtuin 3 SQSTM1/p62: sequestosome 1 TNFRSF11B/OPG: TNF receptor superfamily member 11b TNFRSF11A/RANK: tumor necrosis factor receptor superfamily, member 11a TNFSF11/RANKL: tumor necrosis factor (ligand) superfamily, member 11 TSC1: tuberous sclerosis complex 1 ULK1: unc-51 like autophagy activating kinase 1.
Topics: Humans; Autophagy; Signal Transduction; AMP-Activated Protein Kinases; Clinical Relevance; Osteoarthritis; TOR Serine-Threonine Kinases; Osteoporosis; Metabolic Diseases
PubMed: 36858962
DOI: 10.1080/15548627.2023.2186112 -
British Journal of Pharmacology Jan 2022Osteosarcoma is one of the most common primary tumours of the bone, with a 5-year survival rate of less than 20% after the development of metastases. Osteosarcoma is... (Review)
Review
Osteosarcoma is one of the most common primary tumours of the bone, with a 5-year survival rate of less than 20% after the development of metastases. Osteosarcoma is highly predisposed in Paget's disease of the bone, and both have common characteristic skeletal features due to rapid bone remodelling. Osteosarcoma prognosis is location dependent, which further emphasizes the likely contribution of the bone microenvironment in its pathogenesis. Mechanobiology describes the processes involved when mechanical cues from the changing physical microenvironment of the bone are transduced to biological pathways through mechanosensitive cellular components. Mechanobiology-driven therapies have been used to curb tumour progression by direct alteration of the physical microenvironment or inhibition of metastasis-associated mechanosensitive proteins. This review emphasizes the contribution of mechanobiology to the progression of osteosarcoma and sheds light on current mechanobiology-based therapies and potential new targets for improving disease management. Additionally, the many different 3D models currently used to study osteosarcoma mechanobiology are summarized.
Topics: Biophysics; Bone Neoplasms; Humans; Osteitis Deformans; Osteosarcoma; Tumor Microenvironment
PubMed: 34679192
DOI: 10.1111/bph.15713 -
Endocrinology and Metabolism (Seoul,... Oct 2022Paget's disease of the bone is a prevalent bone disease characterized by disorganized bone remodeling; however, it is comparatively uncommon in East Asian countries,...
Paget's disease of the bone is a prevalent bone disease characterized by disorganized bone remodeling; however, it is comparatively uncommon in East Asian countries, including China, Japan, and Korea. The exact cause still remains unknown. In genetically susceptible individuals, environmental triggers such as paramyxoviral infections are likely to cause the disease. Increased osteoclast activity results in increased bone resorption, which attracts osteoblasts and generates new bone matrix. Fast bone resorption and formation lead to the development of disorganized bone tissue. Increasing serum alkaline phosphatase or unique radiographic lesions may serve as the diagnostic indicators. Common symptoms include bone pain, bowing of the long bones, an enlarged skull, and hearing loss. The diagnosis is frequently confirmed by radiographic and nuclear scintigraphy of the bone. Further, bisphosphonates such as zoledronic acid and pamidronate are effective for its treatment. Moreover, biochemical monitoring is superior to the symptoms as a recurrence indicator. This article discusses the updates of Paget's disease of bone with a clinical case.
Topics: Humans; Osteitis Deformans; Diphosphonates; Pamidronate; Bone and Bones; Bone Resorption
PubMed: 36327984
DOI: 10.3803/EnM.2022.1575 -
CMAJ : Canadian Medical Association... Aug 2023
Topics: Humans; Osteitis Deformans; Adenocarcinoma; Bone and Bones
PubMed: 37640400
DOI: 10.1503/cmaj.230164-f -
Best Practice & Research. Clinical... Sep 2022Bone science has over the last decades unraveled many important pathways in bone and mineral metabolism and the interplay between genetic factors and the environment.... (Review)
Review
Bone science has over the last decades unraveled many important pathways in bone and mineral metabolism and the interplay between genetic factors and the environment. Some of these discoveries have led to the development of pharmacological treatments of osteoporosis and rare bone diseases. Other scientific avenues have uncovered a role for the gut microbiome in regulating bone mass, which have led to investigations on the possible therapeutic role of probiotics in the prevention of osteoporosis. Huge advances have been made in identifying the genes that cause rare bone diseases, which in some cases have led to therapeutic interventions. Advances have also been made in understanding the genetic basis of the more common polygenic bone diseases, including osteoporosis and Paget's disease of bone (PDB). Polygenic profiles are used for establishing genetic risk scores aiming at early diagnosis and intervention, but also in Mendelian randomization (MR) studies to investigate both desired and undesired effects of targets for drug design.
Topics: Humans; Osteitis Deformans; Bone and Bones; Bone Density; Bone Diseases; Osteoporosis
PubMed: 36336607
DOI: 10.1016/j.berh.2022.101791 -
Current Osteoporosis Reports Apr 2024To describe the contributions of osteocytes to the lesions in Paget's disease, which are characterized by locally overactive bone resorption and formation. (Review)
Review
PURPOSE OF REVIEW
To describe the contributions of osteocytes to the lesions in Paget's disease, which are characterized by locally overactive bone resorption and formation.
RECENT FINDINGS
Osteocytes, the most abundant cells in bone, are altered in Paget's disease lesions, displaying increased size, decreased canalicular length, incomplete differentiation, and less sclerostin expression compared to controls in both patients and mouse models. Pagetic lesions show increased senescent osteocytes that express RANK ligand, which drives osteoclastic bone resorption. Abnormal osteoclasts in Paget's disease secrete abundant IGF1, which enhances osteocyte senescence, contributing to lesion formation. Recent data suggest that osteocytes contribute to lesion formation in Paget's disease by responding to high local IGF1 released from abnormal osteoclasts. Here we describe the characteristics of osteocytes in Paget's disease and their role in bone lesion formation based on recent results with mouse models and supported by patient data.
Topics: Osteitis Deformans; Osteocytes; Humans; Animals; Osteoclasts; RANK Ligand; Bone Resorption; Mice; Insulin-Like Growth Factor I; Disease Models, Animal; Cellular Senescence
PubMed: 38457001
DOI: 10.1007/s11914-024-00863-5 -
Current Osteoporosis Reports Jun 2021To provide an overview of the role of genes and loci that predispose to Paget's disease of bone and related disorders. (Review)
Review
PURPOSE OF REVIEW
To provide an overview of the role of genes and loci that predispose to Paget's disease of bone and related disorders.
RECENT FINDINGS
Studies over the past ten years have seen major advances in knowledge on the role of genetic factors in Paget's disease of bone (PDB). Genome wide association studies have identified six loci that predispose to the disease whereas family based studies have identified a further eight genes that cause PDB. This brings the total number of genes and loci implicated in PDB to fourteen. Emerging evidence has shown that a number of these genes also predispose to multisystem proteinopathy syndromes where PDB is accompanied by neurodegeneration and myopathy due to the accumulation of abnormal protein aggregates, emphasising the importance of defects in autophagy in the pathogenesis of PDB. Genetic factors play a key role in the pathogenesis of PDB and the studies in this area have identified several genes previously not suspected to play a role in bone metabolism. Genetic testing coupled to targeted therapeutic intervention is being explored as a way of halting disease progression and improving outcome before irreversible skeletal damage has occurred.
Topics: Genetic Predisposition to Disease; Genetic Testing; Genome-Wide Association Study; Humans; Osteitis Deformans
PubMed: 33988819
DOI: 10.1007/s11914-021-00676-w -
JCI Insight Jul 2023We previously reported that measles virus nucleocapsid protein (MVNP) expression in osteoclasts (OCLs) of patients with Paget disease (PD) or targeted to the OCL lineage...
We previously reported that measles virus nucleocapsid protein (MVNP) expression in osteoclasts (OCLs) of patients with Paget disease (PD) or targeted to the OCL lineage in MVNP-transgenic mice (MVNP mice) increases IGF1 production in osteoclasts (OCL-IGF1) and leads to development of PD OCLs and pagetic bone lesions (PDLs). Conditional deletion of Igf1 in OCLs of MVNP mice fully blocked development of PDLs. In this study, we examined whether osteocytes (OCys), key regulators of normal bone remodeling, contribute to PD. OCys in PDLs of patients and of MVNP mice expressed less sclerostin, and had increased RANKL expression compared with OCys in bones from WT mice or normal patients. To test whether increased OCL-IGF1 is sufficient to induce PDLs and PD phenotypes, we generated TRAP-Igf1 (T-Igf1) transgenic mice to determine whether increased IGF1 expression in the absence of MVNP in OCLs is sufficient to induce PDLs and pagetic OCLs. We found that T-Igf1 mice at 16 months of age developed PD OCLs, PDLs, and OCys, with decreased sclerostin and increased RANKL, similar to MVNP mice. Thus, pagetic phenotypes could be induced by OCLs expressing increased IGF1. OCL-IGF1 in turn increased RANKL production in OCys to induce PD OCLs and PDLs.
Topics: Animals; Mice; Bone and Bones; Gene Expression; Mice, Transgenic; Osteitis Deformans; Osteoclasts; Osteocytes
PubMed: 37338990
DOI: 10.1172/jci.insight.159838 -
The Journal of International Advanced... Apr 2020Air-bone gaps (ABGs) are commonly found in patients with conductive or mixed hearing loss generally due to outer- and/or middle-ear diseases such as otitis externa,... (Review)
Review
Air-bone gaps (ABGs) are commonly found in patients with conductive or mixed hearing loss generally due to outer- and/or middle-ear diseases such as otitis externa, tympanic membrane perforation, interruption or fixation of the ossicular chain, and chronic suppurative otitis media. ABGs can also be found in correlation with inner-ear disorders, such as endolymphatic hydrops, enlarged vestibular aqueduct syndrome, semicircular canal dehiscence, gusher syndrome, cochlear dehiscence, and Paget disease's as well cerebral vascular anomalies including dural arteriovenous fistula. The typical clinical presentation of inner-ear conditions or cerebral vascular anomalies causing ABGs includes audiological and vestibular symptoms like vertigo, oscillopsia, dizziness, imbalance, spinning sensation, pulsatile or continuous tinnitus, hyperacusis, autophony, auricular fullness, Tullio's phenomenon, and Hennebert's sign. Establishing a definitive diagnosis of the underlying condition in patients presenting with an ABG is often challenging to do and, in many patients, the condition may remain undefined. Results from an accurate clinical, audiological, and vestibular evaluation can be suggestive for the underlying condition; however, radiological assessment by computed tomography and/or magnetic resonance imaging is mandatory to confirm any diagnostic suspicion. In this review, we describe and discuss the most recent updates available regarding the clinical presentation and diagnostic workup of inner-ear conditions that may present together with ABGs.
Topics: Air; Bone Conduction; Bone and Bones; Central Nervous System Vascular Malformations; Child; Cochlea; Ear Ossicles; Endolymphatic Hydrops; Female; Hearing Loss; Hearing Loss, Conductive; Hearing Loss, Mixed Conductive-Sensorineural; Hearing Loss, Sensorineural; Humans; Labyrinth Diseases; Magnetic Resonance Imaging; Male; Meniere Disease; Middle Aged; Osteitis Deformans; Semicircular Canal Dehiscence; Tomography, X-Ray Computed; Vestibular Aqueduct
PubMed: 32401207
DOI: 10.5152/iao.2020.7764 -
CMAJ : Canadian Medical Association... Jun 2023
Topics: Humans; Osteitis Deformans; Adenocarcinoma; Bone and Bones
PubMed: 37308214
DOI: 10.1503/cmaj.230164