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Pinto-Cardoso R, Bessa-Andrês C, Correia-de-Sá P, Bernardo Noronha-Matos J. Could hypoxia rehabilitate the osteochondral diseased interface? Lessons from the interplay of hypoxia and purinergic signals elsewhere. Biochem Pharmacol 2023:115646. [PMID: 37321413 DOI: 10.1016/j.bcp.2023.115646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/03/2023] [Accepted: 06/07/2023] [Indexed: 06/17/2023]
Abstract
The osteochondral unit comprises the articular cartilage (90%), subchondral bone (5%) and calcified cartilage (5%). All cells present at the osteochondral unit that is ultimately responsible for matrix production and osteochondral homeostasis, such as chondrocytes, osteoblasts, osteoclasts and osteocytes, can release adenine and/or uracil nucleotides to the local microenvironment. Nucleotides are released by these cells either constitutively or upon plasma membrane damage, mechanical stress or hypoxia conditions. Once in the extracellular space, endogenously released nucleotides can activate membrane-bound purinoceptors. Activation of these receptors is fine-tuning regulated by nucleotides' breakdown by enzymes of the ecto-nucleotidase cascade. Depending on the pathophysiological conditions, both the avascular cartilage and the subchondral bone subsist to significant changes in oxygen tension, which has a tremendous impact on tissue homeostasis. Cell stress due to hypoxic conditions directly influences the expression and activity of several purinergic signalling players, namely nucleotide release channels (e.g. Cx43), NTPDase enzymes and purinoceptors. This review gathers experimental evidence concerning the interplay between hypoxia and the purinergic signalling cascade contributing to osteochondral unit homeostasis. Reporting deviations to this relationship resulting from pathological alterations of articular joints may ultimately unravel novel therapeutic targets for osteochondral rehabilitation. At this point, one can only hypothesize how hypoxia mimetic conditions can be beneficial to the ex vivo expansion and differentiation of osteo- and chondro-progenitors for auto-transplantation and tissue regenerative purposes.
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Affiliation(s)
- Rui Pinto-Cardoso
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP)
| | - Catarina Bessa-Andrês
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP)
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP)
| | - José Bernardo Noronha-Matos
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP).
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2
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Chang CC, Lee KL, Chan TS, Chung CC, Liang YC. Histone Deacetylase Inhibitors Downregulate Calcium Pyrophosphate Crystal Formation in Human Articular Chondrocytes. Int J Mol Sci 2022; 23:ijms23052604. [PMID: 35269745 PMCID: PMC8910507 DOI: 10.3390/ijms23052604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 11/17/2022] Open
Abstract
Calcium pyrophosphate (CPP) deposition disease (CPPD) is a form of CPP crystal-induced arthritis. A high concentration of extracellular pyrophosphate (ePPi) in synovial fluid is positively correlated with the formation of CPP crystals, and ePPi can be upregulated by ankylosis human (ANKH) and ectonucleotide pyrophosphatase 1 (ENPP1) and downregulated by tissue non-specific alkaline phosphatase (TNAP). However, there is currently no drug that eliminates CPP crystals. We explored the effects of the histone deacetylase (HDAC) inhibitors (HDACis) trichostatin A (TSA) and vorinostat (SAHA) on CPP formation. Transforming growth factor (TGF)-β1-treated human primary cultured articular chondrocytes (HC-a cells) were used to increase ePPi and CPP formation, which were determined by pyrophosphate assay and CPP crystal staining assay, respectively. Artificial substrates thymidine 5′-monophosphate p-nitrophenyl ester (p-NpTMP) and p-nitrophenyl phosphate (p-NPP) were used to estimate ENPP1 and TNAP activities, respectively. The HDACis TSA and SAHA significantly reduced mRNA and protein expressions of ANKH and ENPP1 but increased TNAP expression in a dose-dependent manner in HC-a cells. Further results demonstrated that TSA and SAHA decreased ENPP1 activity, increased TNAP activity, and limited levels of ePPi and CPP. As expected, both TSA and SAHA significantly increased the acetylation of histones 3 and 4 but failed to block Smad-2 phosphorylation induced by TGF-β1. These results suggest that HDACis prevented the formation of CPP by regulating ANKH, ENPP1, and TNAP expressions and can possibly be developed as a potential drug to treat or prevent CPPD.
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Affiliation(s)
- Chi-Ching Chang
- Division of Allergy, Immunology and Rheumatology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Division of Rheumatology, Immunology and Allergy, Department of Internal Medicine, Taipei Medical University Hospital, Taipei 11031, Taiwan
| | - Kun-Lin Lee
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan; (K.-L.L.); (C.-C.C.)
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Tze-Sian Chan
- Division of Gastroenterology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Division of Gastroenterology, Department of Internal Medicine, Wan Fang Hospital, Taipei 11696, Taiwan
| | - Chia-Chen Chung
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan; (K.-L.L.); (C.-C.C.)
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
| | - Yu-Chih Liang
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan; (K.-L.L.); (C.-C.C.)
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan
- Ph.D. Program in Drug Discovery and Development Industry, College of Pharmacy, Taipei Medical University, Taipei 11031, Taiwan
- Traditional Herbal Medicine Research Center, Taipei Medical University Hospital, Taipei 11031, Taiwan
- Correspondence:
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3
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Kurisu R, Saigusa T, Aono Y, Hayashi Y, Hitomi S, Shimada M, Iwata K, Shinoda M. Pannexin 1 role in the trigeminal ganglion in infraorbital nerve injury-induced mechanical allodynia. Oral Dis 2022; 29:1770-1781. [PMID: 35029007 DOI: 10.1111/odi.14129] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 11/27/2022]
Abstract
OBJECTIVES The detailed pathological mechanism of orofacial neuropathic pain remains unknown. We aimed to examine the pannexin 1 (Panx1) signaling in the trigeminal ganglion (TG) involvement in infraorbital nerve injury (IONI)-induced orofacial neuropathic pain. MATERIALS AND METHODS Mechanical head-withdrawal threshold (MHWT) was measured in IONI-treated rats receiving intra-TG Panx1 inhibitor or metabotropic glutamate receptor 5 (mGluR5) antagonist administration and MHWTs in naive rats receiving intra-TG mGluR5 agonist administration post-IONI. Glutamate and Panx1 in the TG were measured post-IONI. Panx1, mGluR5, and glutamine synthetase expression in TG were immunohistochemically identified, and changes in the number of mGluR5-P2X3 -expressed TG neurons were examined. RESULTS MHWT was significantly decreased post-IONI, and this decrease was reversed by Panx1 inhibition or mGluR5 antagonism. mGluR5 agonism induced a decrease in the MHWT. IONI increased extracellular glutamate in TG. Panx1 was expressed in satellite glial cells and TG neurons, and intra-TG mGluR5 antagonism decreased the number of mGluR5 and P2X3 positive TG neurons post-IONI. CONCLUSIONS IONI facilitates glutamate release via Panx1 that activates mGluR5 which was expressed in the nociceptive TG neurons innervating the orofacial region. In turn, P2X3 receptor-expressed TG neurons is enhanced via mGluR5 signaling, resulting in orofacial neuropathic pain.
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Affiliation(s)
- Ryoko Kurisu
- Dental Anesthesiology and Orofacial Pain Management, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tadashi Saigusa
- Department of Pharmacology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Yuri Aono
- Department of Pharmacology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Yoshinori Hayashi
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Suzuro Hitomi
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Masahiko Shimada
- Dental Anesthesiology and Orofacial Pain Management, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Koichi Iwata
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Masamichi Shinoda
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
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4
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Fan X, Wu X, Crawford R, Xiao Y, Prasadam I. Macro, Micro, and Molecular. Changes of the Osteochondral Interface in Osteoarthritis Development. Front Cell Dev Biol 2021; 9:659654. [PMID: 34041240 PMCID: PMC8142862 DOI: 10.3389/fcell.2021.659654] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/12/2021] [Indexed: 01/05/2023] Open
Abstract
Osteoarthritis (OA) is a long-term condition that causes joint pain and reduced movement. Notably, the same pathways governing cell growth, death, and differentiation during the growth and development of the body are also common drivers of OA. The osteochondral interface is a vital structure located between hyaline cartilage and subchondral bone. It plays a critical role in maintaining the physical and biological function, conveying joint mechanical stress, maintaining chondral microenvironment, as well as crosstalk and substance exchange through the osteochondral unit. In this review, we summarized the progress in research concerning the area of osteochondral junction, including its pathophysiological changes, molecular interactions, and signaling pathways that are related to the ultrastructure change. Multiple potential treatment options were also discussed in this review. A thorough understanding of these biological changes and molecular mechanisms in the pathologic process will advance our understanding of OA progression, and inform the development of effective therapeutics targeting OA.
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Affiliation(s)
- Xiwei Fan
- Faculty of Science and Engineering, School of Mechanical, Medical and Process Engineering, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Xiaoxin Wu
- Faculty of Science and Engineering, School of Mechanical, Medical and Process Engineering, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Ross Crawford
- Faculty of Science and Engineering, School of Mechanical, Medical and Process Engineering, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,Orthopaedic Department, The Prince Charles Hospital, Brisbane, QLD, Australia
| | - Yin Xiao
- Faculty of Science and Engineering, School of Mechanical, Medical and Process Engineering, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.,Australia-China Centre for Tissue Engineering and Regenerative Medicine, Queensland University of Technology, Brisbane, QLD, Australia
| | - Indira Prasadam
- Faculty of Science and Engineering, School of Mechanical, Medical and Process Engineering, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
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5
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Orriss IR. Extracellular pyrophosphate: The body's "water softener". Bone 2020; 134:115243. [PMID: 31954851 DOI: 10.1016/j.bone.2020.115243] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/08/2020] [Accepted: 01/16/2020] [Indexed: 12/18/2022]
Abstract
Extracellular pyrophosphate (ePPi) was first identified as a key endogenous inhibitor of mineralisation in the 1960's by Fleisch and colleagues. The main source of ePPi seems to be extracellular ATP which is continually released from cells in a controlled way. ATP is rapidly broken down by enzymes including ecto-nucleotide pyrophosphatase/phosphodiesterases to produce ePPi. The major function of ePPi is to directly inhibit hydroxyapatite formation and growth meaning that this simple molecule acts as the body's own "water softener". However, studies have also shown that ePPi can influence gene expression and regulate its own production and breakdown. This review will summarise our current knowledge of ePPi metabolism and how it acts to prevent pathological soft tissue calcification and regulate physiological bone mineralisation.
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Affiliation(s)
- Isabel R Orriss
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London NW1 0TU, UK.
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6
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Fluorescence Differentiation of ATP-related Multiple Enzymatic Activities in Synovial Fluid as a Marker of Calcium Pyrophosphate Deposition Disease using Kyoto Green. Molecules 2020; 25:molecules25051116. [PMID: 32131555 PMCID: PMC7179203 DOI: 10.3390/molecules25051116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 12/02/2022] Open
Abstract
Calcium pyrophosphate deposition disease (CPPD) is a crystal induced inflammation in joints, and causes severe pain in elderly people. The accumulation of pyrophosphate (PPi) in synovial fluid (SF) results from several enzymatic reactions, especially the highly activated e-NPPs, which catalyze the conversion of ATP to PPi. This study demonstrates the detection of relative catalytic activity of 3 enzymes—ecto-nucleotide pyrophosphatase/phosphodiesterases (e-NPPs), tissue nonspecific alkaline phosphatase (TNAP), and ecto-nucleoside triphosphate diphosphohydrolases (e-NTPDases)—using a single molecular sensor called Kyoto Green. Kyoto Green exhibits excellent performance in sensing the catalytic activity of the commercial representatives of the e-NPPs, TNAP, and e-NTPDases, which are ENPP1, PPase, and apyrase, respectively, in both single-enzyme and multi-enzyme assays. Analysis of SF enzymes in 19 SF samples from human and swine revealed moderate activity of e-NPPs, high activity of e-NTPDases, and low activity of TNAP. Our newly developed method for analysis of multiple enzymatic activities using Kyoto Green in biological SF will assist improvement in accuracy of the CPPD prognosis/diagnosis, which will minimize unnecessary medical procedures.
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7
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Corciulo C, Cronstein BN. Signaling of the Purinergic System in the Joint. Front Pharmacol 2020; 10:1591. [PMID: 32038258 PMCID: PMC6993121 DOI: 10.3389/fphar.2019.01591] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 12/09/2019] [Indexed: 12/15/2022] Open
Abstract
The joint is a complex anatomical structure consisting of different tissues, each with a particular feature, playing together to give mobility and stability at the body. All the joints have a similar composition including cartilage for reducing the friction of the movement and protecting the underlying bone, a synovial membrane that produces synovial fluid to lubricate the joint, ligaments to limit joint movement, and tendons for the interaction with muscles. Direct or indirect damage of one or more of the tissues forming the joint is the foundation of different pathological conditions. Many molecular mechanisms are involved in maintaining the joint homeostasis as well as in triggering disease development. The molecular pathway activated by the purinergic system is one of them.The purinergic signaling defines a group of receptors and intermembrane channels activated by adenosine, adenosine diphosphate, adenosine 5’-triphosphate, uridine triphosphate, and uridine diphosphate. It has been largely described as a modulator of many physiological and pathological conditions including rheumatic diseases. Here we will give an overview of the purinergic system in the joint describing its expression and function in the synovium, cartilage, ligament, tendon, and bone with a therapeutic perspective.
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Affiliation(s)
- Carmen Corciulo
- Division of Translational Medicine, Department of Medicine, NYU School of Medicine, New York, NY, United States.,Krefting Research Centre-Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Bruce N Cronstein
- Division of Translational Medicine, Department of Medicine, NYU School of Medicine, New York, NY, United States.,Division of Rheumatology, Department of Medicine, NYU School of Medicine, New York, NY, United States
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8
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Current Therapeutic Strategies for Stem Cell-Based Cartilage Regeneration. Stem Cells Int 2018; 2018:8490489. [PMID: 29765426 PMCID: PMC5889878 DOI: 10.1155/2018/8490489] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 12/14/2017] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
The process of cartilage destruction in the diarthrodial joint is progressive and irreversible. This destruction is extremely difficult to manage and frustrates researchers, clinicians, and patients. Patients often take medication to control their pain. Surgery is usually performed when pain becomes uncontrollable or joint function completely fails. There is an unmet clinical need for a regenerative strategy to treat cartilage defect without surgery due to the lack of a suitable regenerative strategy. Clinicians and scientists have tried to address this using stem cells, which have a regenerative potential in various tissues. Cartilage may be an ideal target for stem cell treatment because it has a notoriously poor regenerative potential. In this review, we describe past, present, and future strategies to regenerate cartilage in patients. Specifically, this review compares a surgical regenerative technique (microfracture) and cell therapy, cell therapy with and without a scaffold, and therapy with nonaggregated and aggregated cells. We also review the chondrogenic potential of cells according to their origin, including autologous chondrocytes, mesenchymal stem cells, and induced pluripotent stem cells.
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9
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Gadjanski I. Mimetic Hierarchical Approaches for Osteochondral Tissue Engineering. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1058:143-170. [PMID: 29691821 DOI: 10.1007/978-3-319-76711-6_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
UNLABELLED In order to engineer biomimetic osteochondral (OC) construct, it is necessary to address both the cartilage and bone phase of the construct, as well as the interface between them, in effect mimicking the developmental processes when generating hierarchical scaffolds that show gradual changes of physical and mechanical properties, ideally complemented with the biochemical gradients. There are several components whose characteristics need to be taken into account in such biomimetic approach, including cells, scaffolds, bioreactors as well as various developmental processes such as mesenchymal condensation and vascularization, that need to be stimulated through the use of growth factors, mechanical stimulation, purinergic signaling, low oxygen conditioning, and immunomodulation. This chapter gives overview of these biomimetic OC system components, including the OC interface, as well as various methods of fabrication utilized in OC biomimetic tissue engineering (TE) of gradient scaffolds. Special attention is given to addressing the issue of achieving clinical size, anatomically shaped constructs. Besides such neotissue engineering for potential clinical use, other applications of biomimetic OC TE including formation of the OC tissues to be used as high-fidelity disease/healing models and as in vitro models for drug toxicity/efficacy evaluation are covered. HIGHLIGHTS Biomimetic OC TE uses "smart" scaffolds able to locally regulate cell phenotypes and dual-flow bioreactors for two sets of conditions for cartilage/bone Protocols for hierarchical OC grafts engineering should entail mesenchymal condensation for cartilage and vascular component for bone Immunomodulation, low oxygen tension, purinergic signaling, time dependence of stimuli application are important aspects to consider in biomimetic OC TE.
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Affiliation(s)
- Ivana Gadjanski
- BioSense Institute, University of Novi Sad, Dr Zorana Djindjica, Novi Sad, Serbia. .,Belgrade Metropolitan University, Tadeusa Koscuska 63, Belgrade, Serbia.
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10
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Abstract
Connexons form the basis of hemichannels and gap junctions. They are composed of six tetraspan proteins called connexins. Connexons can function as individual hemichannels, releasing cytosolic factors (such as ATP) into the pericellular environment. Alternatively, two hemichannel connexons from neighbouring cells can come together to form gap junctions, membrane-spanning channels that facilitate cell-cell communication by enabling signalling molecules of approximately 1 kDa to pass from one cell to an adjacent cell. Connexins are expressed in joint tissues including bone, cartilage, skeletal muscle and the synovium. Indicative of their importance as gap junction components, connexins are also known as gap junction proteins, but individual connexin proteins are gaining recognition for their channel-independent roles, which include scaffolding and signalling functions. Considerable evidence indicates that connexons contribute to the function of bone and muscle, but less is known about the function of connexons in other joint tissues. However, the implication that connexins and gap junctional channels might be involved in joint disease, including age-related bone loss, osteoarthritis and rheumatoid arthritis, emphasizes the need for further research into these areas and highlights the therapeutic potential of connexins.
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Affiliation(s)
- Henry J Donahue
- Department of Biomedical Engineering, Virginia Commonwealth University, 601 West Main Street, Richmond, Virginia 23284, USA
| | - Roy W Qu
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
| | - Damian C Genetos
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
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11
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Steward AJ, Kelly DJ, Wagner DR. Purinergic Signaling Regulates the Transforming Growth Factor-β3-Induced Chondrogenic Response of Mesenchymal Stem Cells to Hydrostatic Pressure. Tissue Eng Part A 2017; 22:831-9. [PMID: 27137792 DOI: 10.1089/ten.tea.2015.0047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Although hydrostatic pressure (HP) is known to regulate chondrogenic differentiation of mesenchymal stromal/stem cells (MSCs), improved insight into the mechanotransduction of HP may form the basis for novel tissue engineering strategies. Previously, we demonstrated that matrix stiffness and calcium ion (Ca(++)) mobility regulate the mechanotransduction of HP; however, the mechanisms, by which these Ca(++) signaling pathways are initiated, are currently unknown. The purinergic pathway, in which adenosine triphosphate (ATP) is released and activates P-receptors to initiate Ca(++) signaling, plays a key role in the mechanotransduction of compression, but has yet to be investigated with regard to HP. Therefore, the objective of this study was to investigate the interplay between purinergic signaling, matrix stiffness, and the chondrogenic response of MSCs to HP. Porcine bone marrow-derived MSCs were seeded into soft or stiff agarose hydrogels and subjected to HP (10 MPa at 1 Hz for 4 h/d for 21 days) or kept in free swelling conditions. Stiff constructs were incubated with pharmacological inhibitors of extracellular ATP, P2 receptors, or hemichannels, or without any inhibitors as a control. As with other loading modalities, HP significantly increased ATP release in the control group; however, inhibition of hemichannels completely abrogated this response. The increase in sulfated glycosaminoglycan (sGAG) synthesis and vimentin reorganization observed in the control group in response to HP was suppressed in the presence of all three inhibitors, suggesting that purinergic signaling is involved in the mechanoresponse of MSCs to HP. Interestingly, ATP was released from both soft and stiff hydrogels in response to HP, but HP only enhanced chondrogenesis in the stiff hydrogels, indicating that matrix stiffness may act downstream of purinergic signaling to regulate the mechanoresponse of MSCs to HP. Addition of exogenous ATP did not replicate the effects of HP on chondrogenesis, suggesting that mechanisms other than purinergic signaling also regulate the response of MSCs to HP.
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Affiliation(s)
- Andrew J Steward
- 1 Bioengineering Graduate Program, Department of Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana.,2 Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute , Trinity College Dublin, Dublin, Ireland
| | - Daniel J Kelly
- 2 Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute , Trinity College Dublin, Dublin, Ireland .,3 Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin , Dublin, Ireland .,4 Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin , Dublin, Ireland
| | - Diane R Wagner
- 5 Department of Mechanical Engineering, Indiana University-Purdue University Indianapolis , Indianapolis, Indiana.,6 Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis , Indianapolis, Indiana
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12
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Rothdiener M, Uynuk-Ool T, Südkamp N, Aurich M, Grodzinsky AJ, Kurz B, Rolauffs B. Human osteoarthritic chondrons outnumber patient- and joint-matched chondrocytes in hydrogel culture-Future application in autologous cell-based OA cartilage repair? J Tissue Eng Regen Med 2017; 12:e1206-e1220. [PMID: 28714570 DOI: 10.1002/term.2516] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 06/09/2017] [Accepted: 07/11/2017] [Indexed: 12/22/2022]
Abstract
Autologous chondrocyte implantation (ACI) is used in 34-60% for osteoarthritic (OA) cartilage defects, although ACI is neither recommended nor designed for OA. Envisioning a hydrogel-based ACI for OA that uses chondrons instead of classically used chondrocytes, we hypothesized that human OA chondrons may outperform OA chondrocytes. We compared patient- and joint surface-matched human OA chondrons with OA chondrocytes cultured for the first time in a hydrogel, using a self-assembling peptide system. We determined yield, viability, cell numbers, mRNA expression, GAPDH mRNA enzyme activity, Collagen II synthesis (CPII) and degradation (C2C), and sulfated glycosaminoglycan. Ex vivo, mRNA expression was comparable. Over time, significant differences in survival led to 3.4-fold higher OA chondron numbers in hydrogels after 2 weeks (p = .002). Significantly, more enzymatically active GAPDH protein indicated higher metabolic activity. The number of cultures that expressed mRNA for Collagen Types I and VI, COMP, aggrecan, VEGF, TGF-β1, and FGF-2 (but not Collagen Types II and X) was different, resulting in a 3.5-fold higher number of expression-positive OA chondron cultures (p < .05). Measuring CPII and C2C per hydrogel, OA chondron hydrogels synthesized more than they degraded Collagen Type II, the opposite was true for OA chondrocytes. Per cell, OA chondrons but not OA chondrocytes displayed more synthesis than degradation. Thus, OA chondrons displayed superior biosynthesis and mRNA expression of tissue engineering and phenotype-relevant genes. Moreover, human OA chondrons displayed a significant survival advantage in hydrogel culture, whose presence, drastic extent, and timescale was novel and is clinically significant. Collectively, these data highlight the high potential of human OA chondrons for OA ACI, as they would outnumber and, thus, surpass OA chondrocytes.
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Affiliation(s)
- Miriam Rothdiener
- Siegfried Weller Institute for Trauma Research, BG Trauma Clinic, Eberhard Karls University, Tuebingen, Germany
| | - Tatiana Uynuk-Ool
- Siegfried Weller Institute for Trauma Research, BG Trauma Clinic, Eberhard Karls University, Tuebingen, Germany
| | - Norbert Südkamp
- G.E.R.N. Tissue Replacement, Regeneration & Neogenesis, Department of Orthopedics and Trauma Surgery, University Medical Center Freiburg, Faculty of Medicine, Albert Ludwigs University of Freiburg, Freiburg, Germany
| | - Matthias Aurich
- Department of Orthopaedic and Trauma Surgery, Sana Kliniken Leipziger Land, Borna, Germany.,Department of Trauma, Hand and Reconstructive Surgery, Universitätsklinikum Jena, Jena, Germany.,Department of Biochemistry, Rush Medical College, Chicago, IL, USA
| | - Alan J Grodzinsky
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bodo Kurz
- Department of Anatomy, Christian Albrechts University, Kiel, Germany
| | - Bernd Rolauffs
- G.E.R.N. Tissue Replacement, Regeneration & Neogenesis, Department of Orthopedics and Trauma Surgery, University Medical Center Freiburg, Faculty of Medicine, Albert Ludwigs University of Freiburg, Freiburg, Germany.,Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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13
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Wong BW, Marsch E, Treps L, Baes M, Carmeliet P. Endothelial cell metabolism in health and disease: impact of hypoxia. EMBO J 2017. [PMID: 28637793 DOI: 10.15252/embj.201696150] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In contrast to the general belief, endothelial cell (EC) metabolism has recently been identified as a driver rather than a bystander effect of angiogenesis in health and disease. Indeed, different EC subtypes present with distinct metabolic properties, which determine their function in angiogenesis upon growth factor stimulation. One of the main stimulators of angiogenesis is hypoxia, frequently observed in disease settings such as cancer and atherosclerosis. It has long been established that hypoxic signalling and metabolism changes are highly interlinked. In this review, we will provide an overview of the literature and recent findings on hypoxia-driven EC function and metabolism in health and disease. We summarize evidence on metabolic crosstalk between different hypoxic cell types with ECs and suggest new metabolic targets.
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Affiliation(s)
- Brian W Wong
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, VIB Center for Cancer Biology, VIB, Leuven, Belgium
| | - Elke Marsch
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, VIB Center for Cancer Biology, VIB, Leuven, Belgium
| | - Lucas Treps
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, VIB Center for Cancer Biology, VIB, Leuven, Belgium
| | - Myriam Baes
- Laboratory for Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute KU Leuven, Leuven, Belgium .,Laboratory of Angiogenesis and Vascular Metabolism, VIB Center for Cancer Biology, VIB, Leuven, Belgium
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Cell culture: complications due to mechanical release of ATP and activation of purinoceptors. Cell Tissue Res 2017; 370:1-11. [PMID: 28434079 PMCID: PMC5610203 DOI: 10.1007/s00441-017-2618-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 03/21/2017] [Indexed: 12/11/2022]
Abstract
There is abundant evidence that ATP (adenosine 5′-triphosphate) is released from a variety of cultured cells in response to mechanical stimulation. The release mechanism involved appears to be a combination of vesicular exocytosis and connexin and pannexin hemichannels. Purinergic receptors on cultured cells mediate both short-term purinergic signalling of secretion and long-term (trophic) signalling such as proliferation, migration, differentiation and apoptosis. We aim in this review to bring to the attention of non-purinergic researchers using tissue culture that the release of ATP in response to mechanical stress evoked by the unavoidable movement of the cells acting on functional purinergic receptors on the culture cells is likely to complicate the interpretation of their data.
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15
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16
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Elevated synovial fluid concentration of adenosine triphosphate in dogs with osteoarthritis or sodium urate-induced synovitis of the stifle. Vet Comp Orthop Traumatol 2016; 29:344-6. [PMID: 27432274 DOI: 10.3415/vcot-15-06-0111] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 03/15/2016] [Indexed: 11/17/2022]
Abstract
Adenosine triphosphate has been shown to stimulate nociceptive nerve terminals in joints. Elevated synovial fluid adenosine triphosphate concentrations as well as a correlation between synovial fluid adenosine triphosphate concentrations and osteoarthritic knee pain has been demonstrated in humans, but not yet in dogs. This study documented elevated synovial fluid adenosine triphosphate concentrations in the stifles of dogs with secondary osteoarthritis and urate-induced synovitis, as compared to normal stifles.
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17
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Modular Tissue Assembly Strategies for Biofabrication of Engineered Cartilage. Ann Biomed Eng 2016; 45:100-114. [DOI: 10.1007/s10439-016-1609-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/02/2016] [Indexed: 12/19/2022]
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18
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Orriss IR, Arnett TR, Russell RGG. Pyrophosphate: a key inhibitor of mineralisation. Curr Opin Pharmacol 2016; 28:57-68. [PMID: 27061894 DOI: 10.1016/j.coph.2016.03.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 03/18/2016] [Accepted: 03/24/2016] [Indexed: 12/20/2022]
Abstract
Inorganic pyrophosphate has long been known as a by-product of many intracellular biosynthetic reactions, and was first identified as a key endogenous inhibitor of biomineralisation in the 1960s. The major source of pyrophosphate appears to be extracellular ATP, which is released from cells in a controlled manner. Once released, ATP can be rapidly hydrolysed by ecto-nucleotide pyrophosphatase/phosphodiesterases to produce pyrophosphate. The main action of pyrophosphate is to directly inhibit hydroxyapatite formation thereby acting as a physiological 'water-softener'. Evidence suggests pyrophosphate may also act as a signalling molecule to influence gene expression and regulate its own production and breakdown. This review will summarise our current understanding of pyrophosphate metabolism and how it regulates bone mineralisation and prevents harmful soft tissue calcification.
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Affiliation(s)
- Isabel R Orriss
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK.
| | - Timothy R Arnett
- Department of Cell and Developmental Biology, University College London, London, UK
| | - R Graham G Russell
- The Botnar Research Centre, Nuffield Orthopaedic Centre, Oxford, UK; The Mellanby Centre for Bone Research, University of Sheffield, Sheffield, UK
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19
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Weber JF, Waldman SD. Stochastic resonance is a method to improve the biosynthetic response of chondrocytes to mechanical stimulation. J Orthop Res 2016; 34:231-9. [PMID: 26234431 DOI: 10.1002/jor.23000] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/23/2015] [Indexed: 02/04/2023]
Abstract
Cellular mechanosensitivity is an important factor during the mechanical stimulation of tissue engineered cartilage. While the application of mechanical stimuli improves tissue growth and properties, chondrocytes also rapidly desensitize under prolonged loading thereby limiting its effectiveness. One potential method to mitigate load-induced desensitization is by superimposing noise on the loading waveforms ("stochastic resonance"). Thus, the purpose of this study was to investigate the effects of stochastic resonance on chondrocyte matrix metabolism. Chondrocyte-seeded agarose gels were subjected to dynamic compressive loading, with or without, superimposed vibrations of different amplitudes and frequency bandwidths. Changes in matrix biosynthesis were determined by radioisotope incorporation and subsequent effects on intracellular calcium signaling were evaluated by confocal microscopy. Although dependent on the duration of loading, superimposed vibrations improved cellular sensitivity to mechanical loading by further increasing matrix synthesis between 20-60%. Stochastic resonance also appeared to limit load-induced desensitization by maintaining sensitivity under desensitized loading conditions. While superimposed vibrations had little effect on the magnitude of intracellular calcium signaling, recovery of mechanosensitivity after stimulation was achieved at a faster rate suggesting that less time may be required between successive loading applications. Thus, stochastic resonance appears to be a valuable tool during the mechanical stimulation of cartilage constructs, even when suboptimal stimulation conditions are used.
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Affiliation(s)
- Joanna F Weber
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada.,Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Stephen D Waldman
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada.,Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Chemical Engineering, Ryerson University, Toronto, Ontario, Canada
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20
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Moon PM, Penuela S, Barr K, Khan S, Pin CL, Welch I, Attur M, Abramson SB, Laird DW, Beier F. Deletion of Panx3 Prevents the Development of Surgically Induced Osteoarthritis. J Mol Med (Berl) 2015; 93:845-56. [PMID: 26138248 DOI: 10.1007/s00109-015-1311-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/24/2015] [Accepted: 06/09/2015] [Indexed: 12/22/2022]
Abstract
UNLABELLED Osteoarthritis (OA) is a highly prevalent, disabling joint disease with no existing therapies to slow or halt its progression. Cartilage degeneration hallmarks OA pathogenesis, and pannexin 3 (Panx3), a member of a novel family of channel proteins, is upregulated during this process. The function of Panx3 remains poorly understood, but we consistently observed a strong increase in Panx3 immunostaining in OA lesions in both mice and humans. Here, we developed and characterized the first global and conditional Panx3 knockout mice to investigate the role of Panx3 in OA. Interestingly, global Panx3 deletion produced no overt phenotype and had no obvious effect on early skeletal development. Mice lacking Panx3 specifically in the cartilage and global Panx3 knockout mice were markedly resistant to the development of OA following destabilization of medial meniscus surgery. These data indicate a specific catabolic role of Panx3 in articular cartilage and identify Panx3 as a potential therapeutic target for OA. Lastly, while Panx1 has been linked to over a dozen human pathologies, this is the first in vivo evidence for a role of Panx3 in disease. KEY MESSAGE Panx3 is localized to cartilage lesions in mice and humans. Global Panx3 deletion does not result in any developmental abnormalities. Mice lacking Panx3 are resistant to the development of osteoarthritis. Panx3 is a novel therapeutic target for the treatment of osteoarthritis.
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Affiliation(s)
- Paxton M Moon
- Departments of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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Abstract
Accumulating evidence now suggests that purinergic signalling exerts significant regulatory effects in the musculoskeletal system. In particular, it has emerged that extracellular nucleotides are key regulators of bone cell differentiation, survival and function. This review discusses our current understanding of the direct effects of purinergic signalling in bone, cartilage and muscle.
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Affiliation(s)
- Isabel R Orriss
- Department of Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, United Kingdom.
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22
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23
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Gonzales S, Wang C, Levene H, Cheung HS, Huang CYC. ATP promotes extracellular matrix biosynthesis of intervertebral disc cells. Cell Tissue Res 2014; 359:635-642. [PMID: 25407524 DOI: 10.1007/s00441-014-2042-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 10/16/2014] [Indexed: 01/07/2023]
Abstract
We have recently found a high accumulation of extracellular adenosine triphosphate (ATP) in the center of healthy porcine intervertebral discs (IVD). Since ATP is a powerful extracellular signaling molecule, extracellular ATP accumulation might regulate biological activities in the IVD. The objective of this study was therefore to investigate the effects of extracellular ATP on the extracellular matrix (ECM) biosynthesis of porcine IVD cells isolated from two distinct anatomical regions: the annulus fibrosus (AF) and nucleus pulposus (NP). ATP treatment significantly promotes ECM deposition and corresponding gene expression (aggrecan and type II collagen) by both cell types in three-dimensional agarose culture. A significant increase in ECM accumulation has been found in AF cells at a lower ATP treatment level (20 μM) compared with NP cells (100 μM), indicating that AF cells are more sensitive to extracellular ATP than NP cells. NP cells also exhibit higher ECM accumulation and intracellular ATP than AF cells under control and treatment conditions, suggesting that NP cells are intrinsically more metabolically active. Moreover, ATP treatment also augments the intracellular ATP level in NP and AF cells. Our findings suggest that extracellular ATP not only promotes ECM biosynthesis via a molecular pathway, but also increases energy supply to fuel that process.
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Affiliation(s)
- Silvia Gonzales
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA
| | - Chong Wang
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA
| | - Howard Levene
- Department of Neurological Surgery, University of Miami, Miami, FL, 33136, USA
| | - Herman S Cheung
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA
- Geriatric Research, Education and Clinical Center, Miami Veterans Affairs Medical Center, Miami, FL, 33125, USA
| | - Chun-Yuh Charles Huang
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA.
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24
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Govitvattana N, Osathanon T, Toemthong T, Pavasant P. IL-6 regulates stress-induced REX-1 expression via ATP-P2Y1 signalling in stem cells isolated from human exfoliated deciduous teeth. Arch Oral Biol 2014; 60:160-6. [PMID: 25455130 DOI: 10.1016/j.archoralbio.2014.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 09/26/2014] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To investigate the relationship between ATP and IL-6 in mechanical stress-induced REX-1 expression in SHEDs. METHODS Cells were stimulated with mechanical stress (0-2.5 gcm(-2)), IL-6 (0.1-5 ng/ml), or ATP (10-100 μM) for 2h in serum-free media. IL-6 and REX-1 expression was examined by qualitative and quantitative polymerase chain reaction. ATP release was measured using a bioluminescence assay. The molecular mechanisms of the signalling pathways were investigated using chemical inhibitors. RESULTS Mechanical stress induced IL-6 and REX-1 mRNA expression and ATP release. JAK inhibitor I inhibited the increase in REX-1 expression and ATP release but not IL-6 induction. Furthermore, suramin inhibited the upregulation of REX-1 mRNA expression but not ATP release. Exogenous IL-6 promoted both ATP release and REX-1 expression. The IL-6-induced REX-1 expression was attenuated by a P2Y1-specific receptor antagonist. Moreover, REX-1 expression was upregulated in a dose-dependent manner by the addition of ATP or a P2Y1 agonist. This inductive effect was abolished by the P2Y1-specific receptor antagonist. CONCLUSIONS ATP-P2Y1 signalling is involved in IL-6-regulated stress-induced REX-1 expression in SHEDs. These results imply the participation of mechanical stress, IL-6, and ATP in regulating the expression of REX-1, a pluripotent stem cell marker.
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Affiliation(s)
- Nattanan Govitvattana
- Research Unit of Mineralized Tissue, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand; Graduate Program in Oral Biology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
| | - Thanaphum Osathanon
- Research Unit of Mineralized Tissue, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand; Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
| | | | - Prasit Pavasant
- Research Unit of Mineralized Tissue, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
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25
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Rosa R, Collavino K, Lakhani A, Delve E, Weber J, Rosenthal A, Waldman S. Clodronate exerts an anabolic effect on articular chondrocytes mediated through the purinergic receptor pathway. Osteoarthritis Cartilage 2014; 22:1327-36. [PMID: 25042551 PMCID: PMC5452978 DOI: 10.1016/j.joca.2014.07.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 07/07/2014] [Accepted: 07/09/2014] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Bisphosphonates are commonly used anti-osteoporotic drugs which have controversial effects on joint diseases including osteoarthritis. Certain bisphosphonates have been shown to have anabolic effects on cartilage which could have important ramifications for their proposed effects in vivo; however, the underlying mechanisms are poorly understood. Thus, the purpose of this study was to characterize the effects of clodronate on primary articular chondrocyte metabolism and to determine the underlying signaling pathways responsible. DESIGN The effects of clodronate and pamidronate on extracellular matrix (ECM) biosynthesis, accumulation and MMP-13 activity were observed in high density, 3D cultures of bovine articular chondrocytes for up to 4 weeks were evaluated. Mechanisms were delineated by measuring intracellular Ca(2+) signaling and the effects of pharmacologic inhibition of the purinergic receptor pathway. RESULTS Clodronate (100 μM) induced an anabolic effect (increased biosynthesis by 13-14%) which resulted in an 89-90% increase in ECM accumulation after 4 weeks of culture and without an associated effect on matrix turn-over. Stimulation by clodronate resulted in a 3.3-fold increase in Ca(2+) signaling and pharmacological inhibitor experiments suggested that the anabolic effects exerted by clodronate are transduced through the purinergic receptor pathway. CONCLUSIONS These findings support the previous notion that certain bisphosphonates may be useful as adjunctive therapies to potentially ameliorate progression of cartilage degeneration and improve arthritis management.
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Affiliation(s)
- R.G. Rosa
- Human Mobility Research Centre, Kingston General Hospital, Kingston, Ontario, Canada
| | - K. Collavino
- Department of Chemical Engineering, Ryerson University, Toronto, Ontario, Canada,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - A. Lakhani
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario, Canada
| | - E. Delve
- Department of Chemical Engineering, Queen’s University, Kingston, Ontario, Canada
| | - J.F. Weber
- Department of Mechanical & Materials Engineering, Queen’s University, Kingston, Ontario, Canada
| | - A.K. Rosenthal
- Division of Rheumatology, Department of Medicine, Medical College of Wisconsin, and the Zablocki VA Medical Center, Milwaukee, WI, USA
| | - S.D. Waldman
- Department of Chemical Engineering, Ryerson University, Toronto, Ontario, Canada,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada,Address correspondence and reprint requests to: S.D. Waldman, Department of Chemical Engineering, Kerr Hall South, Room 241N, Ryerson University, Toronto, Ontario, Canada M5B 2K3. Tel: 1-416-979-5000x4200; Fax: 1-416-979-5083.
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26
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Abu-Hakmeh AE, Wan LQ. High-throughput cell aggregate culture for stem cell chondrogenesis. Methods Mol Biol 2014; 1202:11-19. [PMID: 24676785 DOI: 10.1007/7651_2014_75] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Cell aggregate culture is a widely used, reliable system for promoting chondrogenic differentiation of stem cells. A high-throughput cell pellet culture enables screening of various soluble factors for their effects on stem cell function and chondrogenesis. In this protocol, we report a platform that allows the formation of stem cell aggregates in a 96-well plate format. Specifically, stem cells are centrifuged to form high-density pellets, mimicking mesenchymal condensation. The cell aggregates can be differentiated into chondrocytes when cultured in chondrogenic medium for 4 weeks. Such a technique is compatible for high-throughput screening and can be very useful for optimizing conditions for cartilage tissue engineering.
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Affiliation(s)
- Ahmad E Abu-Hakmeh
- Department of Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
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27
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Burnstock G, Arnett TR, Orriss IR. Purinergic signalling in the musculoskeletal system. Purinergic Signal 2013; 9:541-72. [PMID: 23943493 PMCID: PMC3889393 DOI: 10.1007/s11302-013-9381-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 07/12/2013] [Indexed: 12/11/2022] Open
Abstract
It is now widely recognised that extracellular nucleotides, signalling via purinergic receptors, participate in numerous biological processes in most tissues. It has become evident that extracellular nucleotides have significant regulatory effects in the musculoskeletal system. In early development, ATP released from motor nerves along with acetylcholine acts as a cotransmitter in neuromuscular transmission; in mature animals, ATP functions as a neuromodulator. Purinergic receptors expressed by skeletal muscle and satellite cells play important pathophysiological roles in their development or repair. In many cell types, expression of purinergic receptors is often dependent on differentiation. For example, sequential expression of P2X5, P2Y1 and P2X2 receptors occurs during muscle regeneration in the mdx model of muscular dystrophy. In bone and cartilage cells, the functional effects of purinergic signalling appear to be largely negative. ATP stimulates the formation and activation of osteoclasts, the bone-destroying cells. Another role appears to be as a potent local inhibitor of mineralisation. In osteoblasts, the bone-forming cells, ATP acts via P2 receptors to limit bone mineralisation by inhibiting alkaline phosphatase expression and activity. Extracellular ATP additionally exerts significant effects on mineralisation via its hydrolysis product, pyrophosphate. Evidence now suggests that purinergic signalling is potentially important in several bone and joint disorders including osteoporosis, rheumatoid arthritis and cancers. Strategies for future musculoskeletal therapies might involve modulation of purinergic receptor function or of the ecto-nucleotidases responsible for ATP breakdown or ATP transport inhibitors.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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Rosenthal AK, Gohr CM, Mitton-Fitzgerald E, Lutz MK, Dubyak GR, Ryan LM. The progressive ankylosis gene product ANK regulates extracellular ATP levels in primary articular chondrocytes. Arthritis Res Ther 2013; 15:R154. [PMID: 24286344 PMCID: PMC3978574 DOI: 10.1186/ar4337] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 10/02/2013] [Indexed: 02/06/2023] Open
Abstract
Introduction Extracellular ATP (eATP) is released by articular chondrocytes under physiological and pathological conditions. High eATP levels cause pathologic calcification, damage cartilage, and mediate pain. We recently showed that stable over-expression of the progressive ankylosis gene product, ANK, increased chondrocyte eATP levels, but the mechanisms of this effect remained unexplored. The purpose of this work was to further investigate mechanisms of eATP efflux in primary articular chondrocytes and to better define the role of ANK in this process. Methods We measured eATP levels using a bioluminescence-based assay in adult porcine articular chondrocyte media with or without a 10 minute exposure to hypotonic stress. siRNAs for known ATP membrane transporters and pharmacologic inhibitors of ATP egress pathways were used to identify participants involved in chondrocyte eATP release. Results eATP levels increased after exposure to hypotonic media in a calcium-dependent manner in monolayer and 3-dimensional agarose gel cultures (p < 0.001). A potent transient receptor potential vanilloid 4 (TRPV4) agonist mimicked the effects of hypotonic media. ANK siRNA suppressed basal (p < 0.01) and hypotonically-stressed (p < 0.001) ATP levels. This effect was not mediated by altered extracellular pyrophosphate (ePPi) levels, and was mimicked by the ANK inhibitor, probenecid (p < 0.001). The P2X7/4 receptor inhibitor Brilliant Blue G also suppressed eATP efflux induced by hypotonic media (p < 0.001), while ivermectin, a P2X4 receptor stimulant, increased eATP levels (p < 0.001). Pharmacologic inhibitors of hemichannels, maxianion channels and other volume-sensitive eATP efflux pathways did not suppress eATP levels. Conclusions These findings implicate ANK and P2X7/4 receptors in chondrocyte eATP efflux. Understanding the mechanisms of eATP efflux may result in novel therapies for calcium crystal arthritis and osteoarthritis.
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Gadjanski I, Yodmuang S, Spiller K, Bhumiratana S, Vunjak-Novakovic G. Supplementation of exogenous adenosine 5'-triphosphate enhances mechanical properties of 3D cell-agarose constructs for cartilage tissue engineering. Tissue Eng Part A 2013; 19:2188-200. [PMID: 23651296 DOI: 10.1089/ten.tea.2012.0352] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Formation of tissue-engineered cartilage is greatly enhanced by mechanical stimulation. However, direct mechanical stimulation is not always a suitable method, and the utilization of mechanisms underlying mechanotransduction might allow for a highly effective and less aggressive alternate means of stimulation. In particular, the purinergic, adenosine 5'-triphosphate (ATP)-mediated signaling pathway is strongly implicated in mechanotransduction within the articular cartilage. We investigated the effects of transient and continuous exogenous ATP supplementation on mechanical properties of cartilaginous constructs engineered using bovine chondrocytes and human mesenchymal stem cells (hMSCs) encapsulated in an agarose hydrogel. For both cell types, we have observed significant increases in equilibrium and dynamic compressive moduli after transient ATP treatment applied in the fourth week of cultivation. Continuous ATP treatment over 4 weeks of culture only slightly improved the mechanical properties of the constructs, without major changes in the total glycosaminoglycan (GAG) and collagen content. Structure-function analyses showed that transiently ATP-treated constructs, and in particular those based on hMSCs, had the highest level of correlation between compositional and mechanical properties. Transiently treated groups showed intense staining of the territorial matrix for GAGs and collagen type II. These results indicate that transient ATP treatment can improve functional mechanical properties of cartilaginous constructs based on chondrogenic cells and agarose hydrogels, possibly by improving the structural organization of the bulk phase and territorial extracellular matrix (ECM), that is, by increasing correlation slopes between the content of the ECM components (GAG, collagen) and mechanical properties of the construct.
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Affiliation(s)
- Ivana Gadjanski
- Department of Biomedical Engineering, Columbia University, 622 West 168th Street, New York, NY 10032, USA
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30
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Farnsworth NL, Antunez LR, Bryant SJ. Dynamic compressive loading differentially regulates chondrocyte anabolic and catabolic activity with age. Biotechnol Bioeng 2013; 110:2046-57. [DOI: 10.1002/bit.24860] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 01/25/2013] [Accepted: 02/01/2013] [Indexed: 01/02/2023]
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Usprech J, Chu G, Giardini-Rosa R, Martin K, Waldman SD. The Therapeutic Potential of Exogenous Adenosine Triphosphate (ATP) for Cartilage Tissue Engineering. Cartilage 2012; 3:364-73. [PMID: 26069646 PMCID: PMC4297147 DOI: 10.1177/1947603512444723] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE While mechanical stimuli can be used to enhance the properties of engineered cartilage, a promising alternative may be to directly harness the underlying mechanotransduction pathways responsible. Our initial studies on the adenosine triphosphate (ATP)-purinergic receptor pathway demonstrated that stimulation by exogenous ATP improved tissue growth and properties but elicited matrix turnover under high doses (250 µM) potentially due to the accumulation of extracellular inorganic pyrophosphate (ePPi). Therefore, the purpose of this study was to identify the mechanism of ATP-mediated catabolism and determine a therapeutic dose to maximize the anabolic effect. DESIGN Isolated bovine articular chondrocytes were seeded in high-density, 3-dimensional culture supplemented with varying doses of ATP for 4 weeks. The effects on biosynthesis, matrix metalloproteinase 13 (MMP-13) protein activity, and PPi accumulation were determined. Separate monolayer experiments were conducted to determine the effect of ePPi on MMP-13 activity. RESULTS High doses of ATP resulted in an increase in ePPi accumulation (by 54%) and MMP-13 activity (by 39%). Monolayer experiments confirmed a link between increased ePPi accumulation and MMP-13 activity, which appeared to require calcium and was inhibited by the MEK1/2 inhibitor U0126. Cultures supplemented with 62.5 to 125 µM ATP favored an anabolic response, which represented the therapeutic dose range. CONCLUSIONS A therapeutic dose range of exogenous ATP to improve the properties of engineered cartilage has been identified, and a possible catabolic mechanism involving excess PPi was determined. Future research into PPi signal transduction and pathological crystal formation is necessary to maximize the beneficial effect of exogenous ATP on chondrocyte cultures.
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Affiliation(s)
- Jenna Usprech
- Department of Mechanical and Materials Engineering, Queen’s University, Kingston, ON, Canada,Human Mobility Research Centre, Kingston General Hospital, Kingston, ON, Canada
| | - Gavin Chu
- Department of Chemical Engineering, Queen’s University, Kingston, ON, Canada
| | | | - Kathleen Martin
- Human Mobility Research Centre, Kingston General Hospital, Kingston, ON, Canada
| | - Stephen D. Waldman
- Department of Mechanical and Materials Engineering, Queen’s University, Kingston, ON, Canada,Human Mobility Research Centre, Kingston General Hospital, Kingston, ON, Canada,Department of Chemical Engineering, Queen’s University, Kingston, ON, Canada
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Rho YH, Zhu Y, Zhang Y, Reginato AM, Choi HK. Risk factors for pseudogout in the general population. Rheumatology (Oxford) 2012; 51:2070-4. [PMID: 22886340 DOI: 10.1093/rheumatology/kes204] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Objective. To evaluate the association between the purported risk factors for chondrocalcinosis and gout and the risk of pseudogout in the general population. Methods. We conducted a case-control study nested within a UK general practice database (The Health Improvement Network) by identifying incident cases of pseudogout between 1986 and 2007 and up to 10 control subjects matched to each case, based on age, sex and follow-up time. We evaluated the purported risk factors for chondrocalcinosis (i.e. OA, RA, hyperparathyroidism and diuretics) and established risk factors for gout (as comparison exposures) using conditional logistic regression analysis. Results. We identified 795 cases of pseudogout and 7770 matched control subjects. The risk of pseudogout was associated with hyperparathyroidism [odds ratio (OR) 4.87; 95% CI 2.10, 11.3], OA (OR 2.91; 95% CI 2.48, 3.43) and loop diuretic use (OR 1.35; 95% CI 1.09, 1.67). RA, thiazide diuretic use, BMI and other gout risk factors were not associated with the risk of pseudogout, except for chronic renal failure (OR 2.29; 95% CI 1.30, 4.01). Conclusion. This general population study based on physician-recorded pseudogout suggests that most of the previously observed associations with chondrocalcinosis are replicable with the risk of pseudogout, but there are notable differences, such as thiazide diuretics, RA and chronic renal failure, highlighting the need to study the clinical outcome, pseudogout. Avoiding loop diuretics may help individuals with recurrent pseudogout.
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Affiliation(s)
- Young Hee Rho
- Section of Rheumatology and the Clinical Epidemiology Unit, Boston University School of Medicine, 650 Albany Street, Suite 200, Boston, MA 02118, USA
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Cabral PD, Hong NJ, Garvin JL. ATP mediates flow-induced NO production in thick ascending limbs. Am J Physiol Renal Physiol 2012; 303:F194-200. [PMID: 22496412 DOI: 10.1152/ajprenal.00504.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical stimulation caused by increasing flow induces nucleotide release from many cells. Luminal flow and extracellular ATP stimulate production of nitric oxide (NO) in thick ascending limbs. However, the factors that mediate flow-induced NO production are unknown. We hypothesized that luminal flow stimulates thick ascending limb NO production via ATP. We measured NO in isolated, perfused rat thick ascending limbs using the fluorescent dye DAF FM. The rate of increase in dye fluorescence reflects NO accumulation. Increasing luminal flow from 0 to 20 nl/min stimulated NO production from 17 ± 16 to 130 ± 37 arbitrary units (AU)/min (P < 0.02). Increasing flow from 0 to 20 nl/min raised ATP release from 4 ± 1 to 21 ± 6 AU/min (P < 0.04). Hexokinase (10 U/ml) plus glucose, which consumes ATP, completely prevented the measured increase in ATP. Luminal flow did not increase NO production in the presence of luminal and basolateral hexokinase (10 U/ml). When flow was increased with the ATPase apyrase in both luminal and basolateral solutions (5 U/ml), NO levels did not change significantly. The P2 receptor antagonist suramin (300 μmol/l) reduced flow-induced NO production by 83 ± 25% (P < 0.03) when added to both and basolateral sides. Luminal hexokinase decreased flow-induced NO production from 205.6 ± 85.6 to 36.6 ± 118.6 AU/min (P < 0.02). Basolateral hexokinase also reduced flow-induced NO production. The P2X receptor-selective antagonist NF023 (200 μmol/l) prevented flow-induced NO production when added to the basolateral side but not the luminal side. We conclude that ATP mediates flow-induced NO production in the thick ascending limb likely via activation of P2Y receptors in the luminal and P2X receptors in the basolateral membrane.
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Affiliation(s)
- Pablo D Cabral
- Hypertension and Vascular Research Div., Dept. of Internal Medicine, Henry Ford Hospital, 2799 West Grand Blvd., Detroit, MI 48202, USA.
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Baroja-Mazo A, Barberà-Cremades M, Pelegrín P. The participation of plasma membrane hemichannels to purinergic signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:79-93. [PMID: 22266266 DOI: 10.1016/j.bbamem.2012.01.002] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/30/2011] [Accepted: 01/04/2012] [Indexed: 12/17/2022]
Abstract
The field of hemichannels is closely related to the purinergic signaling and both areas have been growing in parallel. Hemichannels open in response to a wide range of stressful conditions, such as ischemia, pressure or swelling. Hemichannels represent an important mechanism for the cellular release of adenosine 5'-triphosphate (ATP), which is an agonist of the P2Y and P2X family of purinergic receptors. Therefore, hemichannels are key molecules in the regulation of purinergic receptor activation, during physiological and pathophysiological conditions. Furthermore, purinergic receptor activation can also lead to the opening of hemichannels and the subsequent amplification of purinergic signaling via a positive signaling feedback loop, giving rise to the concept of ATP-induced ATP release. Purinergic receptor signaling is involved in regulating many physiological and pathophysiological processes. P2Y receptors activate inositol trisphosphate and transiently increase intracellular calcium. This signaling opens both connexin and pannexin channels, therefore contributing to the expansion of calcium waves across astrocytes and epithelial cells. In addition, several of the P2X receptor subtypes, including the P2X2, P2X4 and P2X7 receptors, activate select cellular permeation pathways to large molecules, including the pannexin-1 channels, which are involved in the initiation of inflammatory responses and cell death. Consequently, the interplay between purinergic receptors and hemichannels could represent a novel target with substantial therapeutic implications in areas such as chronic pain, inflammation or atherosclerosis. This article is part of a Special Issue entitled: The communicating junctions, roles and dysfunctions.
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Affiliation(s)
- Alberto Baroja-Mazo
- University Hospital Virgen de la Arrixaca, Fundación Formación Investigación Sanitaria Región Murcia, Murcia, Spain
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Wann AKT, Zuo N, Haycraft CJ, Jensen CG, Poole CA, McGlashan SR, Knight MM. Primary cilia mediate mechanotransduction through control of ATP-induced Ca2+ signaling in compressed chondrocytes. FASEB J 2012; 26:1663-71. [PMID: 22223751 DOI: 10.1096/fj.11-193649] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We investigated the role of the chondrocyte primary cilium in mechanotransduction events related to cartilage extracellular matrix synthesis. We generated conditionally immortalized wild-type (WT) and IFT88(orpk) (ORPK) mutant chondrocytes that lack primary cilia and assessed intracellular Ca(2+) signaling, extracellular matrix synthesis, and ATP release in response to physiologically relevant compressive strains in a 3-dimensional chondrocyte culture system. All conditions were compared to unloaded controls. We found that cilia were required for compression-induced Ca(2+) signaling mediated by ATP release, and an associated up-regulation of aggrecan mRNA and sulfated glycosaminosglycan secretion. However, chondrocyte cilia were not the initial mechanoreceptors, since both WT and ORPK cells showed mechanically induced ATP release. Rather, we found that primary cilia were required for downstream ATP reception, since ORPK cells did not elicit a Ca(2+) response to exogenous ATP even though WT and ORPK cells express similar levels of purine receptors. We suggest that purinergic Ca(2+) signaling may be regulated by polycystin-1, since ORPK cells only expressed the C-terminal tail. This is the first study to demonstrate that primary cilia are essential organelles for cartilage mechanotransduction, as well as identifying a novel role for primary cilia not previously reported in any other cell type, namely cilia-mediated control of ATP reception.
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Affiliation(s)
- Angus K T Wann
- School of Engineering and Materials Science, Queen Mary University of London, London, UK
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Brandao-Burch A, Key ML, Patel JJ, Arnett TR, Orriss IR. The P2X7 Receptor is an Important Regulator of Extracellular ATP Levels. Front Endocrinol (Lausanne) 2012; 3:41. [PMID: 22654865 PMCID: PMC3355863 DOI: 10.3389/fendo.2012.00041] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 02/29/2012] [Indexed: 11/17/2022] Open
Abstract
Controlled ATP release has been demonstrated from many neuronal and non-neuronal cell types. Once released, extracellular ATP acts on cells in a paracrine manner via purinergic receptors. Considerable evidence now suggests that extracellular nucleotides, signaling via P2 receptors, play important roles in bone homeostasis modulating both osteoblast and osteoclast function. In this study, we demonstrate that mouse osteoclasts and their precursors constitutively release ATP into their extracellular environment. Levels were highest at day 2 (precursor cells), possibly reflecting the high number of red blood cells and accessory cells present. Mature osteoclasts constitutively released ATP in the range 0.05-0.5 pmol/ml/cell. Both osteoclasts and osteoblasts express mRNA and protein for the P2X7 receptor. We found that in osteoclasts, expression levels are fourfold higher in mature cells relative to precursors, whilst in osteoblasts expression remains relatively constant during differentiation. Selective antagonists (0.1-100 μM AZ10606120, A438079, and KN-62) were used to determine whether this release was mediated via P2X7 receptors. AZ10606120, A438079, and KN-62, at 0.1-10 μM, decreased ATP release by mature osteoclasts by up to 70, 60, and 80%, respectively. No differences in cell viability were observed. ATP release also occurs via vesicular exocytosis; inhibitors of this process (1-100 μM NEM or brefeldin A) had no effect on ATP release from osteoclasts. P2X7 receptor antagonists (0.1-10 μM) also decreased ATP release from primary rat osteoblasts by up to 80%. These data show that ATP release via the P2X7 receptor contributes to extracellular ATP levels in osteoclast and osteoblast cultures, suggesting an important additional role for this receptor in autocrine/paracrine purinergic signaling in bone.
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Affiliation(s)
- Andrea Brandao-Burch
- Department of Cell and Developmental Biology, University College LondonLondon, UK
| | - Michelle L. Key
- Department of Cell and Developmental Biology, University College LondonLondon, UK
| | - Jessal J. Patel
- Department of Cell and Developmental Biology, University College LondonLondon, UK
| | - Timothy R. Arnett
- Department of Cell and Developmental Biology, University College LondonLondon, UK
| | - Isabel R. Orriss
- Department of Cell and Developmental Biology, University College LondonLondon, UK
- *Correspondence: Isabel R. Orriss, Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK. e-mail:
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Genetic Background Strongly Influences the Bone Phenotype of P2X7 Receptor Knockout Mice. J Osteoporos 2012; 2012:391097. [PMID: 22934234 PMCID: PMC3425798 DOI: 10.1155/2012/391097] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 06/28/2012] [Accepted: 07/02/2012] [Indexed: 11/25/2022] Open
Abstract
The purinergic P2X7 receptor is expressed by bone cells and has been shown to be important in both bone formation and bone resorption. In this study we investigated the importance of the genetic background of the mouse strains on which the P2X7 knock-out models were based by comparing bone status of a new BALB/cJ P2X7(-/-) strain with a previous one based on the C57BL/6 strain. Female four-month-old mice from both strains were DXA scanned on a PIXImus densitometer; femurs were collected for bone strength measurements and serum for bone marker analysis. Bone-related parameters that were altered only slightly in the B6 P2X7(-/-) became significantly altered in the BALB/cJ P2X7(-/-) when compared to their wild type littermates. The BALB/cJ P2X7(-/-) showed reduced levels of serum C-telopeptide fragment (s-CTX), higher bone mineral density, and increased bone strength compared to the wild type littermates. In conclusion, we have shown that the genetic background of P2X7(-/-) mice strongly influences the bone phenotype of the P2X7(-/-) mice and that P2X7 has a more significant regulatory role in bone remodeling than found in previous studies.
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Fernando H, Czamanski J, Yuan TY, Gu W, Abdi S, Huang CY. Mechanical loading affects the energy metabolism of intervertebral disc cells. J Orthop Res 2011; 29:1634-41. [PMID: 21484859 PMCID: PMC3137745 DOI: 10.1002/jor.21430] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Accepted: 03/15/2011] [Indexed: 02/04/2023]
Abstract
Research has shown that mechanical loading affects matrix biosynthesis of intervertebral disc (IVD) cells; however, the pathway(s) to this effect is currently unknown. Cellular matrix biosynthesis is an energy demanding process. The objective of this study was to investigate the effects of static and dynamic compressive loading on energy metabolism of IVD cells. Porcine annulus fibrosus (AF) and nucleus pulposus (NP) cells seeded in 2% agarose were used in this experiment. Experimental groups included 15% static compression and 0.1 and 1 Hz dynamic compression at 15% strain magnitude for 4 h. ATP, lactate, glucose, and nitric oxide (NO) contents in culture media, and ATP content in cell-agarose construct were measured using biochemical assays. While the total ATP content of AF cells was promoted by static and dynamic loading, only 1 Hz dynamic loading increased total ATP content of NP cells. Increases in lactate production and glucose consumption of AF cells suggest that ATP production via glycolysis is promoted by dynamic compression. ATP release and NO production of AF and NP cells were significantly increased by dynamic loading. Thus, this study clearly illustrates that static and dynamic compressive loading affect IVD cell energy production while cellular responses to mechanical loading were both cell type and compression type dependent.
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Affiliation(s)
- H.N. Fernando
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - J. Czamanski
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - T.-Y. Yuan
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA, Tissue Biomechanics Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - W.Y. Gu
- Tissue Biomechanics Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - S. Abdi
- Department of Anesthesiology, Critical Care and Pain Medicine, BIDMC, Harvard Medical School, Boston, MA
| | - C.-Y.C. Huang
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
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Abhishek A, Doherty S, Maciewicz RA, Muir KR, Zhang W, Doherty M. Self-reported knee malalignment in early adult life as an independent risk for knee chondrocalcinosis. Arthritis Care Res (Hoboken) 2011; 63:1550-7. [DOI: 10.1002/acr.20593] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Xing Y, Gu Y, Gomes RR, You J. P2Y(2) receptors and GRK2 are involved in oscillatory fluid flow induced ERK1/2 responses in chondrocytes. J Orthop Res 2011; 29:828-33. [PMID: 21520257 PMCID: PMC3126889 DOI: 10.1002/jor.21319] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 10/28/2010] [Indexed: 02/04/2023]
Abstract
Mechanical loading is an important factor regulating cartilage metabolism maintained by chondrocytes. However, some of its underlying mechanisms remain poorly understood. In this study, we employed a chondrogenic cell line ATDC5 to investigate roles of P2Y(2) and GRK2 in chondrocyte mechanotransduction. We first confirmed the expression of chondrocyte markers in differentiated ATDC5 cells. We then exposed both differentiated and undifferentiated ATDC5 cells to oscillatory fluid flow, and found that differentiated ATDC5 cells responded to oscillatory fluid flow by increasing COX-2 and aggrecan expressions. More importantly, fluid flow induced ERK1/2 response in differentiated cells was increased more than 10 times compared to those in undifferentiated cells. Furthermore, we found that P2Y(2) mRNA and protein levels in differentiated ATDC5 cells were significantly higher than those in undifferentiated cells. In contrast, GRK2 protein levels in differentiated cells were significantly lower than those in undifferentiated cells. Finally, overexpressions of P2Y(2) and GRK2 in differentiated ATDC5 cells result in a 34% increase and a 21% decrease of the ERK1/2 phosphorylation, respectively, in response to oscillatory fluid flow, suggesting important roles of P2Y(2) and GRK2 in chondrocyte mechanotransduction.
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Affiliation(s)
| | | | | | - Jun You
- Corresponding Author: Jun You, Ph.D., Department of Orthopaedics, 500 University Drive, Hershey, PA 17033, U.S.A., , Tel: (01)-717-531-4819, Fax: (01)-717-531-7583
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Kumahashi N, Naitou K, Nishi H, Oae K, Watanabe Y, Kuwata S, Ochi M, Ikeda M, Uchio Y. Correlation of changes in pain intensity with synovial fluid adenosine triphosphate levels after treatment of patients with osteoarthritis of the knee with high-molecular-weight hyaluronic acid. Knee 2011; 18:160-4. [PMID: 20627733 DOI: 10.1016/j.knee.2010.04.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 04/01/2010] [Accepted: 04/29/2010] [Indexed: 02/02/2023]
Abstract
We sought to determine whether a clinical association exists between osteoarthritis (OA)-associated knee pain and adenosine triphosphate (ATP) levels in synovial fluid (SF). A total of 28 patients with 28 primary OA knees were included. They routinely received intra-articular injection of high-molecular-weight hyaluronic acid (HA) once weekly for 5 weeks (treated group). Eight patients without knee pain who had undergone an operation for anterior or posterior cruciate ligament reconstruction 2 years ago were also examined (control group). SF and blood ATP concentrations, total amount of ATP, total SF volume, and Visual Analogue Scale (VAS) scores in all patients were measured and we compared pre-treatment values with those 1 week after the final treatment. We evaluated the correlation of change in total ATP (ΔATP) and change in VAS score (ΔVAS), ΔVAS and change in SF volume (ΔSF), and ATP concentration in SF and blood. In the treated group, SF ATP concentration, total amount of ATP, SF volume, and VAS score were all significantly lower post-treatment than pre-treatment (p = 0.0005, 0.0003, 0.0022, and < 0.0001, respectively). In treated group, ΔVAS was significantly associated with ΔATP (r = 0.56, p = 0.0032), ΔSF was significantly associated with ΔVAS (r = 0.78, p < 0.0001), and total amount of SF ATP and SF volume at pre-treatment were significantly higher than the control group (p < 0.0001, p < 0.0001) We demonstrated an association between SF ATP level changes and OA knee pain, which should facilitate a further understanding of OA pain mechanisms.
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Affiliation(s)
- Nobuyuki Kumahashi
- Department of Orthopaedics, Ohda Municipal Hospital, 1428-3 Yoshinaga Ohda-shi, Shimane 694-0063, Japan
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Luckprom P, Kanjanamekanant K, Pavasant P. Role of connexin43 hemichannels in mechanical stress-induced ATP release in human periodontal ligament cells. J Periodontal Res 2011; 46:607-15. [PMID: 21615411 DOI: 10.1111/j.1600-0765.2011.01379.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND OBJECTIVE Our previous studies showed that mechanical stress could induce ATP release in human periodontal ligament (HPDL) cells. By signaling through P2 purinergic receptors, ATP increased the expression and the synthesis of osteopontin and RANKL. In this study, the mechanism of stress-induced ATP release was investigated. MATERIAL AND METHODS Continuous compressive forces were applied on cultured HPDL cells. The ATP released was measured using luciferin-luciferase bioluminescence. The expression of gap-junction proteins was examined using RT-PCR and western blot analysis. The opening of hemichannels was demonstrated by cellular uptake of a fluorescent dye, 5(6)-carboxyfluorescein, which is known to penetrate hemichannels. Intracellular signal transduction was investigated using inhibitors and antagonists. RESULTS Mechanical stress induced the release of ATP into the culture medium, which was attenuated by carbenoxolone, a nonspecific gap-junction inhibitor. Addition of meclofenamic acid sodium salt, a connexin43 inhibitor, inhibited ATP release by mechanical stress. Knockdown of connexin43 expression by small interfering RNA reduced the amount of ATP released by mechanical stress, suggesting the role of connexin43 hemichannels. In addition, intracellular Ca(2+) blockers could also inhibit mechanical stress-induced ATP release and the opening of the gap junction. CONCLUSION Our study demonstrated the involvement of gap-junction hemichannels, especially connexin43, in the stress-induced ATP-release mechanism. Furthermore, this mechanism may be regulated by the intracellular Ca(2+) signaling pathway. These results suggest an important role of gap-junction hemichannels in the function and behavior of HPDL cells.
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Affiliation(s)
- P Luckprom
- Department of Anatomy and Graduate School of Oral Biology, Faculty of Dentistry, Chulalongkorn University, Pathumwan, Bangkok, Thailand
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Tanaka S, Kudo H, Asari T, Ono A, Motomura S, Toh S, Furukawa KI. P2Y1 transient overexpression induced mineralization in spinal ligament cells derived from patients with ossification of the posterior longitudinal ligament of the cervical spine. Calcif Tissue Int 2011; 88:263-71. [PMID: 21210088 DOI: 10.1007/s00223-010-9456-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 12/12/2010] [Indexed: 12/01/2022]
Abstract
Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic bone formation in the spinal ligaments. We previously reported that P2 purinoceptor Y1 (P2Y1) expression is elevated in the spinal ligament cells of OPLL patients, but the role of P2Y1 in the spinal ligament calcification process is unknown. To verify the hypothesis that P2Y1 expression causes ossification of the spinal ligaments, we forced expression of P2Y1 in spinal ligament cells obtained from OPLL and non-OPLL patients using a cytomegaloviral vector. The expression of mRNA and protein was investigated by quantitative real-time polymerase chain reaction and immunofluorescence staining, respectively. After transfection, bone morphogenetic protein-2 (BMP-2) and Sox9 mRNA expression was significantly increased in spinal ligament cells derived from OPLL patients (4.36- and 6.44-fold, respectively) compared with cells from non-OPLL patients (0.57- and 3.64-fold, respectively) 2 days after P2Y1 transient transfection. Furthermore, a statistically significant correlation was observed between BMP-2 and P2Y1 mRNA expression levels in cells obtained from OPLL patients but not from non-OPLL patients. Immunofluorescence analysis showed that BMP-2 and P2Y1 expression was increased in OPLL patients only, while Sox9 expression was increased in OPLL and non-OPLL patients. MRS2279, a selective P2Y1 antagonist, blocked the upregulation of Sox9 and BMP-2 after forced expression of P2Y1. Furthermore, 4 days after transient transfection of P2Y1, mineralization was observed only in spinal ligament cells from OPLL patients. These results suggest that P2Y1 expression plays an important role in ectopic bone formation in the spinal ligaments of OPLL patients.
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Affiliation(s)
- Sunao Tanaka
- Department of Pharmacology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan
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Costello JC, Rosenthal AK, Kurup IV, Masuda I, Medhora M, Ryan LM. Parallel regulation of extracellular ATP and inorganic pyrophosphate: roles of growth factors, transduction modulators, and ANK. Connect Tissue Res 2011; 52:139-46. [PMID: 20604715 DOI: 10.3109/03008207.2010.491928] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Extracellular inorganic pyrophosphate (ePPi) is a key regulator of pathologic mineralization in articular cartilage. Articular chondrocytes generate ePPi by the transportation of intracellular PPi (iPPi) through transport mechanisms such as ANK or by the degradation of extracellular adenosine triphosphate (eATP) by ectoenzymes. Although numerous modulators of ePPi have been characterized, little is known about eATP elaboration in cartilage. We sought to determine (1) whether eATP is coordinately regulated with ePPi and (2) whether ANK transports ATP. METHODS Primary articular chondrocytes were treated with factors known to modulate ePPi levels including growth factors (TGFβ1 and IGF-1), anion channel inhibitors, and chemicals that alter adenylyl cyclase and protein kinase C activities. Additional chondrocyte monolayers were infected with adenovirus containing functional (Ad-ANK) or mutated (Ad-ANK mutant) ANK sequences. eATP levels were measured with a bioluminescent assay. RESULTS TGFβ1 enhanced eATP accumulation by 33%, whereas IGF-1 decreased eATP accumulation by 63% and attenuated TGFβ1-induced eATP release by 72%. Forskolin and probenecid diminished eATP accumulation by 55% and 89%. Phorbol-12-myristate-13-acetate increased eATP by 29%. Transfection of chondrocytes with Ad-ANK caused a 10-fold increase in eATP compared with control values. CONCLUSION Modulation of eATP by various factors paralleled their effects on ePPi production, suggesting a shared pathway of ePPi and eATP production and implicating ANK in eATP transport. As eATP directly contributes to pathologic mineralization in articular cartilage, understanding eATP regulation may lead to effective therapies for crystal-associated arthritis.
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Affiliation(s)
- Jill C Costello
- Division of Rheumatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin 53295-1000, USA
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Abstract
Communication between osteoblasts, osteoclasts, and osteocytes is integral to their ability to build and maintain the skeletal system and respond to physical signals. Various physiological mechanisms, including nerve communication, hormones, and cytokines, play an important role in this process. More recently, the important role of direct, cell-cell communication via gap junctions has been established. In this review, we demonstrate the integral role of gap junctional intercellular communication (GJIC) in skeletal physiology and bone cell mechanosensing.
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Qi J, Chi L, Bynum D, Banes AJ. Gap junctions in IL-1β-mediated cell survival response to strain. J Appl Physiol (1985) 2011; 110:1425-31. [PMID: 21212244 DOI: 10.1152/japplphysiol.00477.2010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mechanical stimuli play important roles in proliferation and differentiation of connective tissue cells, and development and homeostatic maintenance of tissues. However, excessive mechanical loading to a tissue can injure cells and disrupt the matrix, as occurs in tendinopathy. Tendinopathy is a common clinical problem in athletes and in many occupational settings due to overuse of the tendon. Moreover, interleukin (IL)-1β is generally considered to be a "bad" cytokine, activating NF-κb and cell death and inducing matrix metalloproteinase (MMPs 1, 2, 3) expression and matrix destruction. However, activated NF-κB can also drive a cell survival pathway. We have reported that cyclic strain induced tenocyte death in three-dimensional (3D) cultures, and IL-1β could promote cell survival under strain. Therefore, it was hypothesized that 1) cyclic strain could induce cell death in tenocytes as observed in pathologic tendons in vivo; 2) a gene expression profile indicative of tendinopathy could be identified; and 3) low-dose IL-1β could protect cells from strain-induced, tendinopathy-like changes. Human tenocytes were cultured in 3D type I collagen hydrogels and subjected to 3.5% elongation at 1 Hz for 1 h/day for up to 5 days with or without IL-1β. Real-time RT-PCR data showed that cyclic strain regulated the expression of tendinopathy marker genes in a manner similar to that found in pathological tendons from patients and that addition of IL-1β reversed the gene expression changes to control levels. Results of further studies showed that IL-1β may modulate cell survival through upregulating the expression of connexin 43, which is involved in the modulation of cell death/survival in a variety of cells and tissues. The elucidation of the mechanisms underlying strain-induced cell death and recovery from strain injury will facilitate our understanding of the pathogenesis of tendinopathy and may lead to the discovery of new molecular targets for early diagnosis and treatment of tendinopathy.
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Affiliation(s)
- Jie Qi
- Flexcell International, Hillsborough, NC 27278, USA
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Abhishek A, Doherty M. Pathophysiology of articular chondrocalcinosis--role of ANKH. Nat Rev Rheumatol 2010; 7:96-104. [PMID: 21102543 DOI: 10.1038/nrrheum.2010.182] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Calcium pyrophosphate (CPP) crystal deposition (CPPD) is associated with ageing and osteoarthritis, and with uncommon disorders such as hyperparathyroidism, hypomagnesemia, hemochromatosis and hypophosphatasia. Elevated levels of synovial fluid pyrophosphate promote CPP crystal formation. This extracellular pyrophosphate originates either from the breakdown of nucleotide triphosphates by plasma-cell membrane glycoprotein 1 (PC-1) or from pyrophosphate transport by the transmembrane protein progressive ankylosis protein homolog (ANK). Although the etiology of apparent sporadic CPPD is not well-established, mutations in the ANK human gene (ANKH) have been shown to cause familial CPPD. In this Review, the key regulators of pyrophosphate metabolism and factors that lead to high extracellular pyrophosphate levels are described. Particular emphasis is placed on the mechanisms by which mutations in ANKH cause CPPD and the clinical phenotype of these mutations is discussed. Cartilage factors predisposing to CPPD and CPP-crystal-induced inflammation and current treatment options for the management of CPPD are also described.
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Affiliation(s)
- Abhishek Abhishek
- Division of Academic Rheumatology, Clinical Sciences Building, City Hospital Nottingham, Hucknall Road, Nottingham NG51PB, UK.
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Rosenthal AK, Hempel D, Kurup IV, Masuda I, Ryan LM. Purine receptors modulate chondrocyte extracellular inorganic pyrophosphate production. Osteoarthritis Cartilage 2010; 18:1496-501. [PMID: 20709180 PMCID: PMC2975862 DOI: 10.1016/j.joca.2010.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 08/05/2010] [Accepted: 08/10/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Extracellular inorganic pyrophosphate (ePPi) plays a key role in the regulation of normal and pathologic mineralization. The purpose of this work was to evaluate the role of P1 and P2 purine receptors in modulating ePPi production by articular chondrocytes. METHODS Porcine cartilage explants and chondrocyte monolayers were cultured in the presence of P1 agonists, or a P2 agonist or antagonist and inhibitors of P2 signaling. Ambient media ePPi concentrations were measured after 48-96h. RESULTS The P1 agonists NECA and CGS 21680 significantly decreased ePPi concentrations surrounding chondrocytes and cartilage explants. The P2 agonist, ADP, increased ePPi levels, and the P2 antagonist, suramin, decreased ePPi concentrations. Thapsigargin and 1,2 bis-(2-aminophenoxy)ethane-N,N,N'N'-tetra acetic acid (BAPTA), which dampen Ca(2+)-related P2 signaling, suppressed the response to ADP. CONCLUSIONS Purine receptors are important regulators of ePPi production by chondrocytes. P1 receptor stimulation diminishes and P2 receptor stimulation enhances ePPi production. Alterations in receptor signaling or aberrations of extracellular purine nucleotide metabolism resulting in abnormal quantities or proportions of P1 and P2 receptor ligands could foster changes in ePPi production that in turn affect mineralization. We propose a homeostatic role for extracellular purine nucleotides and purine receptors in stabilizing ePPi concentrations.
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Waldman SD, Usprech J, Flynn LE, Khan AA. Harnessing the purinergic receptor pathway to develop functional engineered cartilage constructs. Osteoarthritis Cartilage 2010; 18:864-72. [PMID: 20346406 DOI: 10.1016/j.joca.2010.03.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 02/15/2010] [Accepted: 03/04/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Mechanical stimulation is a widely used method to enhance the formation and properties of tissue-engineered cartilage. While this approach can be highly successful, it may be more efficient and effective to harness the known underlying mechanotransduction pathways responsible. With this aim, the purpose of this study was to assess the effect of directly stimulating the purinergic receptor pathway through exogenous adenosine 5'-triphosphate (ATP) in absence of externally applied forces. METHODS Isolated bovine articular chondrocytes were seeded in high density, 3D culture and supplemented with varying doses of ATP for up to 4 weeks. The effects on biosynthesis, extracellular matrix accumulation and mechanical properties were then evaluated. Experiments were also conducted to assess whether exogenous ATP elicited any undesirable effects, such as: inflammatory mediator release, matrix turn-over and mineralization. RESULTS Supplementation with ATP had a profound effect on the growth and maturation of the developed tissue. Exogenous ATP (62.5-250 microM) increased biosynthesis by 80-120%, and when stimulated for a period of 4 weeks resulted in increased matrix accumulation (80% increase in collagen and 60% increase in proteoglycans) and improved mechanical properties (6.5-fold increase in indentation modulus). While exogenous ATP did not stimulate the release of inflammatory mediators or induce mineralization, high doses of ATP (250 microM) elicited a 2-fold increase in matrix metalloproteinase-13 expression suggesting the emergence of a catabolic response. CONCLUSIONS Harnessing the ATP-purinergic receptor pathway is a highly effective approach to improve tissue formation and impart functional mechanical properties. However, the dose of ATP needs to be controlled as not to elicit a catabolic response.
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Affiliation(s)
- S D Waldman
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada.
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Garcia M, Knight MM. Cyclic loading opens hemichannels to release ATP as part of a chondrocyte mechanotransduction pathway. J Orthop Res 2010; 28:510-5. [PMID: 19890993 DOI: 10.1002/jor.21025] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The process of chondrocyte mechanotransduction is poorly understood. However, recent studies suggest the involvement of a purinergic calcium signaling pathway although the mechanism of ATP release has not been identified. The present study tests the hypothesis that cyclic compression opens hemichannels thereby triggering the release of ATP into the extracellular milieu activating P2 receptors. The well-established chondrocyte-agarose model was utilized enabling chondrocytes to be subjected to a 40-min period of cyclic compression at 0-15% strain and 1 Hz. The opening of hemichannels was determined using Lucifer yellow (LY) incorporation and fluorescence microscopy, whereas the release of ATP into the surrounding media was quantified using the luciferin-luciferase assay. Results indicated that cyclic compression activated hemichannels such that the percentage of cells showing LY incorporation increased from 50 to 70%. This was associated with a sevenfold increase in the release of ATP. Both LY incorporation and ATP release in response to mechanical loading were blocked by the hemichannel inhibitor, flufenamic acid. Treatment with apyrase or P2 receptor antagonists, suramin or oxidated-ATP, did not prevent the mechanically induced response. In conclusion, mechanical loading triggers release of ATP via hemichannels. Hence, this study provides the first evidence of hemichannel involvement in chondrocyte mechanobiology.
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Affiliation(s)
- Mariana Garcia
- Queen Mary University of London, School of Engineering and Materials Science, Mile End Road, London E1 4NS, United Kingdom
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