In rheumatoid arthritis (RA), osteoclastic bone resorption causes structural joint damage as well as periarticular and systemic bone loss. Periarticular bone loss is one of the earliest indices of ...RA, often preceding the onset of clinical symptoms via largely unknown mechanisms. Excessive osteoclastogenesis induced by receptor activator of NF-κB ligand (RANKL) expressed by synovial fibroblasts causes joint erosion, whereas the role of RANKL expressed by lymphocytes in various types of bone damage has yet to be elucidated. In the bone marrow of arthritic mice, we found an increase in the number of RANKL-expressing plasma cells, which displayed an ability to induce osteoclastogenesis in vitro. Genetic ablation of RANKL in B-lineage cells resulted in amelioration of periarticular bone loss, but not of articular erosion or systemic bone loss, in autoimmune arthritis. We also show conclusive evidence for the critical contribution of synovial fibroblast RANKL to joint erosion in collagen-induced arthritis on the arthritogenic DBA/1J background. This study highlights the importance of plasma-cell RANKL in periarticular bone loss in arthritis and provides mechanistic insight into the early manifestation of bone lesion induced by autoimmunity.
OPG Production Matters Where It Happened Tsukasaki, Masayuki; Asano, Tatsuo; Muro, Ryunosuke ...
Cell reports,
09/2020, Letnik:
32, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Osteoprotegerin (OPG) is a circulating decoy receptor for RANKL, a multifunctional cytokine essential for the differentiation of tissue-specific cells in bone and immune systems such as osteoclasts, ...medullary thymic epithelial cells (mTECs), and intestinal microfold cells (M cells). However, it is unknown whether OPG functions only at the production site or circulates to other tissues acting in an endocrine fashion. Here we explore the cellular source of OPG by generating OPG-floxed mice and show that locally produced OPG, rather than circulating OPG, is crucial for bone and immune homeostasis. Deletion of OPG in osteoblastic cells leads to severe osteopenia without affecting serum OPG. Deletion of locally produced OPG increases mTEC and M cell numbers while retaining the normal serum OPG level. This study shows that OPG limits its functions within the tissue where it was produced, illuminating the importance of local regulation of the RANKL system.
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•Locally produced OPG, but not circulating OPG, is crucial for bone and immune homeostasis•Osteoblastic cells are the primary source of OPG in bone metabolism•mTECs are the primary source of OPG in the regulation of the thymic microenvironment•M cells are the primary source of OPG in intestinal homeostasis
Osteoprotegerin (OPG), a soluble decoy receptor for RANKL, plays a central role in bone and immune systems. Tsukasaki et al. show that locally produced OPG critically contributes to bone, thymus, and gut homeostasis without being influenced by serum OPG, illustrating the importance of local regulation of the RANKL system.
Abstract
The ontogeny and fate of stem cells have been extensively investigated by lineage-tracing approaches. At distinct anatomical sites, bone tissue harbors multiple types of skeletal stem cells, ...which may independently supply osteogenic cells in a site-specific manner. Periosteal stem cells (PSCs) and growth plate resting zone stem cells (RZSCs) critically contribute to intramembranous and endochondral bone formation, respectively. However, it remains unclear whether there is functional crosstalk between these two types of skeletal stem cells. Here we show PSCs are not only required for intramembranous bone formation, but also for the growth plate maintenance and prolonged longitudinal bone growth. Mice deficient in PSCs display progressive defects in intramembranous and endochondral bone formation, the latter of which is caused by a deficiency in PSC-derived Indian hedgehog (Ihh). PSC-specific deletion of Ihh impairs the maintenance of the RZSCs, leading to a severe defect in endochondral bone formation in postnatal life. Thus, crosstalk between periosteal and growth plate stem cells is essential for post-developmental skeletal growth.
Amidst the fourth COVID-19 wave in Viet Nam, national lockdowns necessitated the closure of numerous dental schools. To assess DDS (Doctor of Dental Surgery) graduation exams, this study analyzed ...their 2021 implementation in comparison to onsite exams conducted in 2020 and 2022 at the Faculty of Odonto-Stomatology, University of Medicine and Pharmacy at Ho Chi Minh City, Viet Nam (FOS-UMPH). The final online examination comprises two main sessions: a synchronous online examination using FOS-UMPH e-Learning for theories (consisting of 200 MCQs and 3 written tests with 3 clinical situations needed be solved) and a synchronous online examination using Microsoft Teams for practicum (comprising of 12 online OSCE stations). The final grades were evaluated using the same metrics in face-to-face final examinations in 2022 and 2020. A total of 114, 112 and 95 students were recruited for the first-time exams in 2020, 2021 and 2022, respectively. In order to analyze the reliability, histogram and k-mean clustering were employed. The histograms from 2020, 2021 and 2022 showed a striking similarity. However, fewer students failed in 2021 and 2022 (13% and 12.6%, respectively) compared to 2020 (28%), with clinical problem-solving part grades (belonging to theory session) being notably higher in 2021 and 2022. Intriguingly, the MCQ Score results showed the identical patterns. The courses of orthodontics, dental public health, and pediatrics subjects (in the group of prevention and development dentistry) stood out for their exceptional accuracy across both sessions. After examining data gathered over three years, we identified three distinct clusters: the first comprised of scattered average and low scores, the second characterized by high scores but unstable and scattered and the third cluster boasting consistently high and centered scores. According to our study, online and onsite traditional graduation exam results are relatively equivalent, but additional measures are necessary to standardize the final examination and adapt to the new normal trend in dental education.
Rinsing the mouth with sodium chloride (NaCl) solution is believed to promote healthy gum and improve oral ulcer healing. Scientific evidence to support this assumption is, however, lacking. This ...study aims to investigate the effect and clarify underlying mechanisms of short-term rinsing with NaCl on human gingival fibroblast (hGFs) wound healing. Isolated primary hGFs and human normal oral keratinocytes (hNOKs) were rinsed with 0-7.2% NaCl for 2 min, 3 times a day. Scratch-tests, trans-well migration assays and MTT activity were performed. mRNA expression was assessed of type-I collagen, fibronectin and FAK. Changes in FAK and F-actin were detected by immunofluorescence. KCl, NaH2PO4, KH2PO4 were used to clarify the molecules involved. Rinsing with 0.9-1.8% NaCl significantly promoted hGFs cell migration but not proliferation. However, it had no effect on hNOKs. Rinsing with 1.8% NaCl significantly up-regulated the expression of type-I collagen and fibronectin. FAK and F-actin, molecules responsible for cytoskeleton re-organization and cell migration, were also up-regulated. Cl- seemed to be essential since rinsing with KCl resulted in a similar effect as noted with NaCl. In conclusion, short-term rinsing with NaCl promoted hGFs migration, and increased the expression of extracellular matrix as well as cytoskeletal proteins. These data strongly support the long held belief in the benefits of using NaCl mouth-rinse.
Abstract Periodontal ligament cells have the potential to differentiate into bone forming osteoblasts and thus represent a good cellular candidate for bone regeneration. This study aimed to ...investigate the effect of inhibition of histone deacetylases, using the inhibitor Trichostatin A (TSA), on bone regeneration by human periodontal ligament cells (hPDLCs) in a mouse calvaria bone defect. Methods RUNX2 protein and its acetylation was analyzed by immunoprecipitation and western blotting. The effect of TSA on osteogenic differentiation of hPDLCs was investigated using in vitro 3D cultures. hPDLCs were pre-incubated with and without TSA and implanted in mouse calvaria defects with polycaprolactone/polyethylene glycol (PCL/PEG) co-polymer scaffold. Micro-CT scanning and bone histomorphometric analysis were used to quantify the amount of bone. Survival of hPDLCs as xenogenic grafts was verified by immunohistochemistry with anti-human β1-integrin. The immunological response of mice against hPDLCs xenografts was evaluated by measuring total IgG and hPDLCs-specific IgG. Results: Beside affecting histone protein, TSA also induced hyper-acetylation of RUNX2 which might be a crucial mechanism for enhancing osteogenesis by hPDLCs. TSA enhanced mineral deposition by hPDLCs in in vitro 3D cultures and had no effect on cell viability. In vivo bone regeneration of mouse calvaria defects was significantly enhanced by TSA pre-treated hPDLCs. By using anti-human ß1 integrin hPDLCs were shown to differentiate into osteocyte-like cells that were present in newly formed bone. hPDLCs, as a xenograft, slightly but not significantly induced an immunological response in recipient mice as demonstrated by the level of total IgG and hPDLCs-specific IgG. Conclusion Inhibition of histone deacetylases by TSA enhanced in vivo bone regeneration by hPDLCs. The data strongly suggest a novel approach to regenerate bone tissue.
Objectives
In this study, we aimed to investigate the effects of a mixture of advanced platelet‐rich fibrin (A‐PRF) and xenogenic bone substitute material (XBSM) on the proliferation and migration of ...human periodontal ligament stem cells (hPDLSCs) based on the in vitro release of growth factors.
Material and Methods
The concentrations of platelet‐derived growth factor‐AB (PDGF‐AB) and vascular endothelial growth factor (VEGF) released by the A‐PRF‐XBSM mixture were estimated using enzyme‐linked immunoassay for up to 7 d. The A‐PRF‐XBSM mixture exudate was incubated with hPDLSCs. At Days 1, 3, 5, and 7, cell proliferation and migration were investigated by cell counting and wound‐healing assays.
Results
PDGD‐AB and VEGF were released from the A‐PRF‐XBSM mixture exudate for up to 7 days. hPDLSCs were cultured in media with various concentrations of the A‐PRF‐XBSM mixture exudate and exhibited their proliferation and migration ability. Furthermore, the factors released from the 100% A‐PRF‐XBSM mixture exudate had a substantial effect on cell migration, whereas those released from 4% and 20% A‐PRF‐XBSM mixture exudates stimulated hPDLSC proliferation.
Conclusions
A‐PRF‐XBSM mixture continuously released growth factors over 7 days and enhanced hPDLSC proliferation and migration. Therefore, A‐PRF in combination with XBSM might provide potential advantages for periodontal tissue regeneration.
Histone acetylation is an important epigenetic mechanism that controls expression of certain genes. It includes non-sequence-based changes of chromosomal regional structure that can alter the ...expression of genes. Acetylation of histones is controlled by the activity of two groups of enzymes: the histone acetyltransferases (HATs) and histone deacetylases (HDACs). HDACs remove acetyl groups from the histone tail, which alters its charge and thus promotes compaction of DNA in the nucleosome. HDACs render the chromatin structure into a more compact form of heterochromatin, which makes the genes inaccessible for transcription. By altering the transcriptional activity of bone-associated genes, HDACs control both osteogenesis and osteoclastogenesis. This review presents an overview of the function of HDACs in the modulation of bone formation. Special attention is paid to the use of HDAC inhibitors in mineralized tissue regeneration from cells of dental origin.
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