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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 -
CMAJ : Canadian Medical Association... Aug 2023
Topics: Humans; Osteitis Deformans; Adenocarcinoma; Bone and Bones
PubMed: 37640400
DOI: 10.1503/cmaj.230164-f -
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 -
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 -
Medicina Clinica Sep 2023Paget's disease of bone is characterized by the alteration, in one or several bone locations, of the equilibrium between bone formation and bone resorption. This... (Review)
Review
Paget's disease of bone is characterized by the alteration, in one or several bone locations, of the equilibrium between bone formation and bone resorption. This imbalance results in a disorganized, widened bone, in many cases with increased bone density, although more fragile. A genetic predisposition for Paget's disease of bone could explain between 5% and 40% of the cases. Different environmental factors should explain the rest of the cases. Paget's disease of bone was classically considered the second most common metabolic bone disease. However, in recent decades there has been a marked decrease in both incidence and clinical severity. These changes have led to believe that the influence of some environmental factor may have diminished or even disappeared. This decrease in incidence should not be an excuse for abandoning Paget's disease of bone research, but rather it should be the reason to remain searching to try to understand better its pathogenesis.
Topics: Humans; Osteitis Deformans; Bone Resorption; Adenocarcinoma; Causality; Genetic Predisposition to Disease
PubMed: 37263846
DOI: 10.1016/j.medcli.2023.05.005 -
European Journal of Neurology Aug 2023Mutations in the gene encoding valosin-containing protein (VCP) are related to myriad medical conditions, including familial amyotrophic lateral sclerosis, inclusion...
BACKGROUND AND PURPOSE
Mutations in the gene encoding valosin-containing protein (VCP) are related to myriad medical conditions, including familial amyotrophic lateral sclerosis, inclusion body myopathy, and frontotemporal dementia. There are several reports of a link between these mutations and early onset Parkinson disease (PD).
CASE DESCRIPTION
We report a 53-year-old PD patient with VCP mutation who later developed motor complications, thus receiving subthalamic nucleus deep brain stimulation (DBS) at the age of 56 years. However, myopathy emerged 1.5 years after surgery.
CONCLUSIONS
With the phenotype variability of VCP, DBS should be carefully evaluated, considering the possible unfavorable long-term outcomes due to other symptoms of this mutation.
Topics: Humans; Valosin Containing Protein; Parkinson Disease; Deep Brain Stimulation; Mutation; Frontotemporal Dementia; Muscular Diseases; Cell Cycle Proteins; Osteitis Deformans
PubMed: 37170789
DOI: 10.1111/ene.15824 -
Bone Dec 2023Paget's disease of bone (PDB) is a degenerative disorder affecting the skull and bones. Hyperactive osteoclasts (OCs) initiate bone degradation in the early stage,...
Paget's disease of bone (PDB) is a degenerative disorder affecting the skull and bones. Hyperactive osteoclasts (OCs) initiate bone degradation in the early stage, followed by increased bone formation by osteoblasts (OBs) in trabecular bones during the advanced stage. This OB-OC uncoupling results in bone deformations and irregular trabecular bone patterns. Current mouse models poorly replicate the advanced-stage characteristics of PDB. Optineurin (Gene: OPTN in humans, Optn in mice, protein: OPTN) has been implicated in PDB by genetic analyses. We identified PDB-like cortical lesions associated with OC hyperactivation in an Optn knockout (Optn) mouse model. However, the effects of OPTN dysfunction on OBs and trabecular bone in advanced PDB remain unclear. In this study, we used the Optn mouse model to investigate trabecular bone abnormalities and OB activity in PDB. Micro-computed tomography analysis revealed severe pagetic alterations in craniofacial bones and femurs of aged Optn mice, resembling clinical manifestations of PDB. Altered OB activity was observed in aged Optn mice, implicating compensatory OB response in trabecular bone anomalies. To elucidate the role of OC-OB interactions in PDB, we conducted in vitro experiments using OC conditioned media (CM) to examine the effects on OB osteogenic potential. We found OC CM restored compromised osteogenic induction of Optn bone marrow stromal cells (BMSCs) from young mice, suggesting OCs maintain OB activity through secreted factors. Strikingly, OC CM from aged Optn mice significantly enhanced osteogenic capability of Optn BMSCs, providing evidence for increased OB activity in advanced stages of PDB. We further identified TGF-β/BMP signaling pathway in mediating the effects of OC CM on OBs. Our findings provide insights into Optn's role in trabecular bone abnormalities and OB activity in PDB. This enhances understanding of PDB pathogenesis and may contribute to potential therapeutic strategies for PDB and related skeletal disorders.
Topics: Humans; Mice; Animals; Aged; Osteitis Deformans; X-Ray Microtomography; Bone and Bones; Osteoclasts; Osteoblasts
PubMed: 37802379
DOI: 10.1016/j.bone.2023.116929 -
Seminars in Musculoskeletal Radiology Aug 2023Although the prevalence of Paget's disease has decreased over the past 20 years, incidental discovery on imaging is not unusual. The challenge is to establish the... (Review)
Review
Although the prevalence of Paget's disease has decreased over the past 20 years, incidental discovery on imaging is not unusual. The challenge is to establish the diagnosis, especially in unusual forms that may be mistaken for metastases. This review describes the typical imaging features of Paget's disease and some rare presentations that may be more difficult to recognize.
Topics: Humans; Osteitis Deformans; Incidental Findings
PubMed: 37748472
DOI: 10.1055/s-0043-1771036 -
Frontiers in Endocrinology 2023Disordered and hypomineralized woven bone formation by dysfunctional mesenchymal stromal cells (MSCs) characterize delayed fracture healing and endocrine -metabolic bone...
BACKGROUND
Disordered and hypomineralized woven bone formation by dysfunctional mesenchymal stromal cells (MSCs) characterize delayed fracture healing and endocrine -metabolic bone disorders like fibrous dysplasia and Paget disease of bone. To shed light on molecular players in osteoblast differentiation, woven bone formation, and mineralization by MSCs we looked at the intermediate filament desmin (DES) during the skeletogenic commitment of rat bone marrow MSCs (rBMSCs), where its bone-related action remains elusive.
RESULTS
Monolayer cultures of immunophenotypically- and morphologically - characterized, adult male rBMSCs showed co-localization of desmin (DES) with vimentin, F-actin, and runx2 in all cell morphotypes, each contributing to sparse and dense colonies. Proteomic analysis of these cells revealed a topologically-relevant interactome, focused on cytoskeletal and related enzymes//chaperone/signalling molecules linking DES to runx2 and alkaline phosphatase (ALP). Osteogenic differentiation led to mineralized woven bone nodules confined to dense colonies, significantly smaller and more circular with respect to controls. It significantly increased also colony-forming efficiency and the number of DES-immunoreactive dense colonies, and immunostaining of co-localized DES/runx-2 and DES/ALP. These data confirmed pre-osteoblastic and osteoblastic differentiation, woven bone formation, and mineralization, supporting DES as a player in the molecular pathway leading to the osteogenic fate of rBMSCs.
CONCLUSION
Immunocytochemical and morphometric studies coupled with proteomic and bioinformatic analysis support the concept that DES may act as an upstream signal for the skeletogenic commitment of rBMSCs. Thus, we suggest that altered metabolism of osteoblasts, woven bone, and mineralization by dysfunctional BMSCs might early be revealed by changes in DES expression//levels. Non-union fractures and endocrine - metabolic bone disorders like fibrous dysplasia and Paget disease of bone might take advantage of this molecular evidence for their early diagnosis and follow-up.
Topics: Male; Animals; Rats; Osteogenesis; Intermediate Filaments; Osteitis Deformans; Core Binding Factor Alpha 1 Subunit; Desmin; Proteomics; Calcinosis; Mesenchymal Stem Cells; Adenocarcinoma; Alkaline Phosphatase; Bone Diseases, Metabolic
PubMed: 37732119
DOI: 10.3389/fendo.2023.1234569 -
Journal of Endocrinological... Jun 2024Paget's disease of bone is a focal skeletal disorder causing bone deformities and impairing bone quality. Despite the prevalence of asymptomatic cases is increasing, the... (Review)
Review
INTRODUCTION
Paget's disease of bone is a focal skeletal disorder causing bone deformities and impairing bone quality. Despite the prevalence of asymptomatic cases is increasing, the progression of the disease can lead to invalidating complications that compromise the quality of life. Doubts on clinical and therapeutic management aspects exist, although beneficial effects of antiresorptive drugs, particularly bisphosphonates are known. However, limited information is available from randomized controlled trials on the prevention of disease complications so that somewhat contrasting positions about treatment indications between expert panels from the main scientific societies of metabolic bone diseases exist. This task force, composed by expert representatives appointed by the Italian Society of Osteoporosis, Mineral Metabolism and Skeletal Diseases and members of the Italian Association of Paget's disease of bone, felt the necessity for more specific and up to date indications for an early diagnosis and clinical management.
METHODS
Through selected key questions, we propose evidence-based recommendations for the diagnosis and treatment of the disease. In the lack of good evidence to support clear recommendations, available information from the literature together with expert opinion of the panel was used to provide suggestions for the clinical practice.
RESULTS AND CONCLUSION
Description of the evidence quality and support of the strength of the statements was provided on each of the selected key questions. The diagnosis of PDB should be mainly based on symptoms and the typical biochemical and radiological features. While treatment is mandatory to all the symptomatic cases at diagnosis, less evidence is available on treatment indications in asymptomatic as well as in previously treated patients in the presence of biochemical recurrence. However, given the safety and long-term efficacy of potent intravenous bisphosphonates such as zoledronate, a suggestion to treat most if not all cases at the time of diagnosis was released.
Topics: Humans; Osteitis Deformans; Italy; Bone Density Conservation Agents; Societies, Medical; Diphosphonates
PubMed: 38488978
DOI: 10.1007/s40618-024-02318-1