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Wang Q, Ji C, Ali A, Ding I, Wang Y, McCulloch CA. TRPV4 mediates IL-1-induced Ca 2+ signaling, ERK activation and MMP expression. FASEB J 2024; 38:e23731. [PMID: 38855909 DOI: 10.1096/fj.202400031r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 04/14/2024] [Accepted: 05/24/2024] [Indexed: 06/11/2024]
Abstract
Ca2+ permeation through TRPV4 in fibroblasts is associated with pathological matrix degradation. In human gingival fibroblasts, IL-1β binding to its signaling receptor (IL-1R1) induces activation of extracellular regulated kinase (ERK) and MMP1 expression, processes that require Ca2+ flux across the plasma membrane. It is not known how IL-1R1, which does not conduct Ca2+, generates Ca2+ signals in response to IL-1. We examined whether TRPV4 mediates the Ca2+ fluxes required for ERK signaling in IL-1 stimulated gingival fibroblasts. TRPV4 was immunostained in fibroblasts of human gingival connective tissue and in focal adhesions of cultured mouse gingival fibroblasts. Human gingival fibroblasts treated with IL-1β showed no change of TRPV4 expression but there was increased MMP1 expression. In mouse, gingival fibroblasts expressing TRPV4, IL-1 strongly increased [Ca2+]i. Pre-incubation of cells with IL-1 Receptor Antagonist blocked Ca2+ entry induced by IL-1 or the TRPV4 agonist GSK101. Knockout of TRPV4 or expression of a non-Ca2+-conducting TRPV4 pore-mutant or pre-incubation with the TRPV4 inhibitor RN1734, blocked IL-1-induced Ca2+ transients and expression of the mouse interstitial collagenase, MMP13. Treatment of mouse gingival fibroblasts with GSK101 phenocopied Ca2+ and ERK responses induced by IL-1; these responses were absent in TRPV4-null cells or cells expressing a non-conducting TRPV4 pore-mutant. Immunostained IL-1R1 localized with TRPV4 in adhesions within cell extensions. While TRPV4 immunoprecipitates analyzed by mass spectrometry showed no association with IL-1R1, TRPV4 associated with Src-related proteins and Src co-immunoprecipitated with TRPV4. Src inhibition reduced IL-1-induced Ca2+ responses. The functional linkage of TRPV4 with IL-1R1 expands its repertoire of innate immune signaling processes by mediating IL-1-driven Ca2+ responses that drive matrix remodeling in fibroblasts. Thus, inhibiting TRPV4 activity may provide a new pharmacological approach for blunting matrix degradation in inflammatory diseases.
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Affiliation(s)
- Qin Wang
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Chenfan Ji
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Aiman Ali
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Isabel Ding
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
| | - Yongqiang Wang
- Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada
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Gonzalez-Nolde S, Schweiger CJ, Davis EER, Manzoni TJ, Hussein SMI, Schmidt TA, Cone SG, Jay GD, Parreno J. The Actin Cytoskeleton as a Regulator of Proteoglycan 4. Cartilage 2024:19476035231223455. [PMID: 38183234 DOI: 10.1177/19476035231223455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2024] Open
Abstract
OBJECTIVE The superficial zone (SZ) of articular cartilage is responsible for distributing shear forces for optimal cartilage loading and contributes to joint lubrication through the production of proteoglycan 4 (PRG4). PRG4 plays a critical role in joint homeostasis and is chondroprotective. Normal PRG4 production is affected by inflammation and irregular mechanical loading in post-traumatic osteoarthritis (PTOA). THe SZ chondrocyte (SZC) phenotype, including PRG4 expression, is regulated by the actin cytoskeleton in vitro. There remains a limited understanding of the regulation of PRG4 by the actin cytoskeleton in native articular chondrocytes. The filamentous (F)-actin cytoskeleton is a potential node in crosstalk between mechanical stimulation and cytokine activation and the regulation of PRG4 in SZCs, therefore developing insights in the regulation of PRG4 by actin may identify molecular targets for novel PTOA therapies. MATERIALS AND METHODS A comprehensive literature search on PRG4 and the regulation of the SZC phenotype by actin organization was performed. RESULTS PRG4 is strongly regulated by the actin cytoskeleton in isolated SZCs in vitro. Biochemical and mechanical stimuli have been characterized to regulate PRG4 and may converge upon actin cytoskeleton signaling. CONCLUSION Actin-based regulation of PRG4 in native SZCs is not fully understood and requires further elucidation. Understanding the regulation of PRG4 by actin in SZCs requires an in vivo context to further potential of leveraging actin arrangement to arthritic therapeutics.
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Yu D, Nie Q, Xue J, Luo R, Xie S, Chao S, Wang E, Xu L, Shan Y, Liu Z, Li Y, Li Z. Direct Mapping of Cytomechanical Homeostasis Destruction in Osteoarthritis Based on Silicon Nanopillar Array. Adv Healthc Mater 2023; 12:e2301126. [PMID: 37747342 DOI: 10.1002/adhm.202301126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 09/14/2023] [Indexed: 09/26/2023]
Abstract
Osteoarthritis (OA) is the most prevalent joint degenerative disease characterized by chronic joint inflammation. The pathogenesis of OA has not been fully elucidated yet. Cartilage erosion is the most significant pathological feature in OA, which is considered the result of cytomechanical homeostasis destruction. The cytomechanical homeostasis is maintained by the dynamic interaction between cells and the extracellular matrix, which can be reflected by cell traction force (CTF). It is critical to assess the CTF to provide a deeper understanding of the cytomechanical homeostasis destruction and progression in OA. In this study, a silicon nanopillar array (Si-NP) with high spatial resolution and aspect ratio is fabricated to investigate the CTF in response to OA. It is discovered that the CTF is degraded in OA, which is attributed to the F-actin reorganization induced by the activation of RhoA/ROCK signaling pathway. Si-NP also shows promising potential as a mechanopharmacological assessment platform for OA drug screening and evaluation.
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Affiliation(s)
- Dengjie Yu
- Department of Orthopedics, Xiangya hospital, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
| | - Qingbin Nie
- Department of Neurosurgery, PLA General Hospital, Beijing, 100853, China
| | - Jiangtao Xue
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
- School of Medical Technology, Beijing Institute of Technology, Beijing, 100081, China
| | - Ruizeng Luo
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
| | - Shiwang Xie
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
| | - Shengyu Chao
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
| | - Engui Wang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
| | - Linlin Xu
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety & CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, Beijing, 100190, China
| | - Yizhu Shan
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
| | - Zhuo Liu
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100191, China
| | - Yusheng Li
- Department of Orthopedics, Xiangya hospital, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Zhou Li
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, 101400, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
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Savadipour A, Nims RJ, Rashidi N, Garcia-Castorena JM, Tang R, Marushack GK, Oswald SJ, Liedtke WB, Guilak F. Membrane stretch as the mechanism of activation of PIEZO1 ion channels in chondrocytes. Proc Natl Acad Sci U S A 2023; 120:e2221958120. [PMID: 37459546 PMCID: PMC10372640 DOI: 10.1073/pnas.2221958120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 06/07/2023] [Indexed: 07/20/2023] Open
Abstract
Osteoarthritis is a chronic disease that can be initiated by altered joint loading or injury of the cartilage. The mechanically sensitive PIEZO ion channels have been shown to transduce injurious levels of biomechanical strain in articular chondrocytes and mediate cell death. However, the mechanisms of channel gating in response to high cellular deformation and the strain thresholds for activating PIEZO channels remain unclear. We coupled studies of single-cell compression using atomic force microscopy (AFM) with finite element modeling (FEM) to identify the biophysical mechanisms of PIEZO-mediated calcium (Ca2+) signaling in chondrocytes. We showed that PIEZO1 and PIEZO2 are needed for initiating Ca2+ signaling at moderately high levels of cellular deformation, but at the highest strains, PIEZO1 functions independently of PIEZO2. Biophysical factors that increase apparent chondrocyte membrane tension, including hypoosmotic prestrain, high compression magnitudes, and low deformation rates, also increased PIEZO1-driven Ca2+ signaling. Combined AFM/FEM studies showed that 50% of chondrocytes exhibit Ca2+ signaling at 80 to 85% nominal cell compression, corresponding to a threshold of apparent membrane finite principal strain of E = 1.31, which represents a membrane stretch ratio (λ) of 1.9. Both intracellular and extracellular Ca2+ are necessary for the PIEZO1-mediated Ca2+ signaling response to compression. Our results suggest that PIEZO1-induced signaling drives chondrocyte mechanical injury due to high membrane tension, and this threshold can be altered by factors that influence membrane prestress, such as cartilage hypoosmolarity, secondary to proteoglycan loss. These findings suggest that modulating PIEZO1 activation or downstream signaling may offer avenues for the prevention or treatment of osteoarthritis.
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Affiliation(s)
- Alireza Savadipour
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
| | - Robert J. Nims
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
| | - Neda Rashidi
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
| | - Jaquelin M. Garcia-Castorena
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
- Division of Biology and Biomedical Sciences, Biochemistry, Biophysics, and Structural Biology Program, Washington University in St. Louis, St. Louis, MO63110
| | - Ruhang Tang
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
| | - Gabrielle K. Marushack
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
| | - Sara J. Oswald
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
| | - Wolfgang B. Liedtke
- Department of Neurology, Duke University, Durham, NC27705
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY10010
| | - Farshid Guilak
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO63110
- Shriners Hospitals for Children – St. Louis, St. Louis, MO63110
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO63110
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO63110
- Division of Biology and Biomedical Sciences, Biochemistry, Biophysics, and Structural Biology Program, Washington University in St. Louis, St. Louis, MO63110
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO63110
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Stam LB, Clark AL. Chondrocyte primary cilia lengthening and shortening in response to mediators of osteoarthritis; a role for integrin α1β1 and focal adhesions. OSTEOARTHRITIS AND CARTILAGE OPEN 2023; 5:100357. [PMID: 37008821 PMCID: PMC10063384 DOI: 10.1016/j.ocarto.2023.100357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 03/14/2023] [Indexed: 03/29/2023] Open
Abstract
Objective Integrin α1β1 protects against osteoarthritis when it is upregulated in the early stages of disease, however, the mechanism behind this is currently unknown. Hypo-osmotic stress, interleukin-1 (IL-1) and transforming growth factor β (TGFβ) influence chondrocyte signaling and are important mediators of osteoarthritis. Evidence for primary cilia as a signaling hub for these factors and the involvement of the F-actin cytoskeleton in this response is growing. The purpose of this study was to investigate the role of integrin α1β1 in the response of primary cilia and the F-actin cytoskeleton to these osteoarthritic mediators. Design Primary cilia length and the number of F-actin peaks were measured in ex vivo wild type and itga1-null chondrocytes in response to hypo-osmotic stress, IL-1, and TGFβ alone or in combination, and with or without focal adhesion kinase inhibitor. Results We show that integrin α1β1 and focal adhesions are necessary for cilial lengthening and increases in F-actin peaks with hypo-osmotic stress and IL-1, but are not required for cilial shortening with TGFβ. Furthermore, we established that the chondrocyte primary cilium has a resting length of 2.4 μm, a minimum length of 2.1 μm corresponding to the thickness of the pericellular matrix, and a maximum length of 3.0 μm. Conclusions While integrin α1β1 is not necessary for the formation of chondrocyte primary cilia and cilial shortening in response to TGFβ, it is necessary for the mediation of cilial lengthening and the formation of F-actin peaks in response to hypo-osmotic stress and IL-1.
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A dysfunctional TRPV4-GSK3β pathway prevents osteoarthritic chondrocytes from sensing changes in extracellular matrix viscoelasticity. Nat Biomed Eng 2021; 5:1472-1484. [PMID: 33707778 PMCID: PMC8433267 DOI: 10.1038/s41551-021-00691-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 01/28/2021] [Indexed: 01/31/2023]
Abstract
Changes in the composition and viscoelasticity of the extracellular matrix in load-bearing cartilage influence the proliferation and phenotypes of chondrocytes, and are associated with osteoarthritis. However, the underlying molecular mechanism is unknown. Here we show that the viscoelasticity of alginate hydrogels regulates cellular volume in healthy human chondrocytes (with faster stress relaxation allowing cell expansion and slower stress relaxation restricting it) but not in osteoarthritic chondrocytes. Cellular volume regulation in healthy chondrocytes was associated with changes in anabolic gene expression, in the secretion of multiple pro-inflammatory cytokines, and in the modulation of intracellular calcium regulated by the ion-channel protein transient receptor potential cation channel subfamily V member 4 (TRPV4), which controls the phosphorylation of glycogen synthase kinase 3β (GSK3β), an enzyme with pleiotropic effects in osteoarthritis. A dysfunctional TRPV4-GSK3β pathway in osteoarthritic chondrocytes rendered the cells unable to respond to environmental changes in viscoelasticity. Our findings suggest strategies for restoring chondrocyte homeostasis in osteoarthritis.
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Ferreira A, Duarte T, Marques S, Costa P, Neves S, dos Santos T, Granja P, Porto G. Iron triggers the early stages of cartilage degeneration in vitro: The role of articular chondrocytes. OSTEOARTHRITIS AND CARTILAGE OPEN 2021; 3:100145. [DOI: 10.1016/j.ocarto.2021.100145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 02/15/2021] [Indexed: 12/13/2022] Open
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Articular Chondrocyte Phenotype Regulation through the Cytoskeleton and the Signaling Processes That Originate from or Converge on the Cytoskeleton: Towards a Novel Understanding of the Intersection between Actin Dynamics and Chondrogenic Function. Int J Mol Sci 2021; 22:ijms22063279. [PMID: 33807043 PMCID: PMC8004672 DOI: 10.3390/ijms22063279] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 02/08/2023] Open
Abstract
Numerous studies have assembled a complex picture, in which extracellular stimuli and intracellular signaling pathways modulate the chondrocyte phenotype. Because many diseases are mechanobiology-related, this review asked to what extent phenotype regulators control chondrocyte function through the cytoskeleton and cytoskeleton-regulating signaling processes. Such information would generate leverage for advanced articular cartilage repair. Serial passaging, pro-inflammatory cytokine signaling (TNF-α, IL-1α, IL-1β, IL-6, and IL-8), growth factors (TGF-α), and osteoarthritis not only induce dedifferentiation but also converge on RhoA/ROCK/Rac1/mDia1/mDia2/Cdc42 to promote actin polymerization/crosslinking for stress fiber (SF) formation. SF formation takes center stage in phenotype control, as both SF formation and SOX9 phosphorylation for COL2 expression are ROCK activity-dependent. Explaining how it is molecularly possible that dedifferentiation induces low COL2 expression but high SF formation, this review theorized that, in chondrocyte SOX9, phosphorylation by ROCK might effectively be sidelined in favor of other SF-promoting ROCK substrates, based on a differential ROCK affinity. In turn, actin depolymerization for redifferentiation would “free-up” ROCK to increase COL2 expression. Moreover, the actin cytoskeleton regulates COL1 expression, modulates COL2/aggrecan fragment generation, and mediates a fibrogenic/catabolic expression profile, highlighting that actin dynamics-regulating processes decisively control the chondrocyte phenotype. This suggests modulating the balance between actin polymerization/depolymerization for therapeutically controlling the chondrocyte phenotype.
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Inflammatory signaling sensitizes Piezo1 mechanotransduction in articular chondrocytes as a pathogenic feed-forward mechanism in osteoarthritis. Proc Natl Acad Sci U S A 2021; 118:2001611118. [PMID: 33758095 PMCID: PMC8020656 DOI: 10.1073/pnas.2001611118] [Citation(s) in RCA: 103] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Osteoarthritis is a global health problem that affects load-bearing joints, causing loss of mobility and enormous healthcare costs. However, disease-modifying approaches are lacking. Here, we report a cellular mechanism of inflammatory signaling in chondrocytes, the cellular component of cartilage. We show how osteoarthritis-relevant levels of interleukin-1α reprogram articular chondrocytes so that they become more susceptible to mechanical trauma, which chondrocytes sense via Piezo1/2-mechanosensitive ion channels. We uncover that IL-1α enhances gene expression of Piezo1 in primary articular chondrocytes underlying Piezo1 enhanced function. We elucidate signaling from membrane to nucleus, including transcription factors that enhance Piezo1 expression. We also define consequences of increased expression of Piezo1, for mechanotransduction and at rest, that implicate this reprogramming mechanism in osteoarthritis pathogenesis. Osteoarthritis (OA) is a painful and debilitating condition of synovial joints without any disease-modifying therapies [A. M. Valdes, T. D. Spector, Nat. Rev. Rheumatol. 7, 23–32 (2011)]. We previously identified mechanosensitive PIEZO channels, PIEZO1 and PIEZO2, both expressed in articular cartilage, to function in chondrocyte mechanotransduction in response to injury [W. Lee et al., Proc. Natl. Acad. Sci. U.S.A. 111, E5114–E5122 (2014); W. Lee, F. Guilak, W. Liedtke, Curr. Top. Membr. 79, 263–273 (2017)]. We therefore asked whether interleukin-1–mediated inflammatory signaling, as occurs in OA, influences Piezo gene expression and channel function, thus indicative of maladaptive reprogramming that can be rationally targeted. Primary porcine chondrocyte culture and human osteoarthritic cartilage tissue were studied. We found that interleukin-1α (IL-1α) up-regulated Piezo1 in porcine chondrocytes. Piezo1 expression was significantly increased in human osteoarthritic cartilage. Increased Piezo1 expression in chondrocytes resulted in a feed-forward pathomechanism whereby increased function of Piezo1 induced excess intracellular Ca2+ at baseline and in response to mechanical deformation. Elevated resting state Ca2+ in turn rarefied the F-actin cytoskeleton and amplified mechanically induced deformation microtrauma. As intracellular substrates of this OA-related inflammatory pathomechanism, in porcine articular chondrocytes exposed to IL-1α, we discovered that enhanced Piezo1 expression depended on p38 MAP-kinase and transcription factors HNF4 and ATF2/CREBP1. CREBP1 directly bound to the proximal PIEZO1 gene promoter. Taken together, these signaling and genetic reprogramming events represent a detrimental Ca2+-driven feed-forward mechanism that can be rationally targeted to stem the progression of OA.
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Takeda Y, Niki Y, Fukuhara Y, Fukuda Y, Udagawa K, Shimoda M, Kikuchi T, Kobayashi S, Harato K, Miyamoto T, Matsumoto M, Nakamura M. Compressive mechanical stress enhances susceptibility to interleukin-1 by increasing interleukin-1 receptor expression in 3D-cultured ATDC5 cells. BMC Musculoskelet Disord 2021; 22:238. [PMID: 33648469 PMCID: PMC7923672 DOI: 10.1186/s12891-021-04095-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 02/17/2021] [Indexed: 12/31/2022] Open
Abstract
Background Mechanical overload applied on the articular cartilage may play an important role in the pathogenesis of osteoarthritis. However, the mechanism of chondrocyte mechanotransduction is not fully understood. The purpose of this study was to assess the effects of compressive mechanical stress on interleukin-1 receptor (IL-1R) and matrix-degrading enzyme expression by three-dimensional (3D) cultured ATDC5 cells. In addition, the implications of transient receptor potential vanilloid 4 (TRPV4) channel regulation in promoting effects of compressive mechanical loading were elucidated. Methods ATDC5 cells were cultured in alginate beads with the growth medium containing insulin-transferrin-selenium and BMP-2 for 6 days. The cultured cell pellet was seeded in collagen scaffolds to produce 3D-cultured constructs. Cyclic compressive loading was applied on the 3D-cultured constructs at 0.5 Hz for 3 h. The mRNA expressions of a disintegrin and metalloproteinases with thrombospondin motifs 4 (ADAMTS4) and IL-1R were determined with or without compressive loading, and effects of TRPV4 agonist/antagonist on mRNA expressions were examined. Immunoreactivities of reactive oxygen species (ROS), TRPV4 and IL-1R were assessed in 3D-cultured ATDC5 cells. Results In 3D-cultured ATDC5 cells, ROS was induced by cyclic compressive loading stress. The mRNA expression levels of ADAMTS4 and IL-1R were increased by cyclic compressive loading, which was mostly prevented by pyrollidine dithiocarbamate. Small amounts of IL-1β upregulated ADAMTS4 and IL-1R mRNA expressions only when combined with compressive loading. TRPV4 agonist suppressed ADAMTS4 and IL-1R mRNA levels induced by the compressive loading, whereas TRPV4 antagonist enhanced these levels. Immunoreactivities to TRPV4 and IL-1R significantly increased in constructs with cyclic compressive loading. Conclusion Cyclic compressive loading induced mRNA expressions of ADAMTS4 and IL-1R through reactive oxygen species. TRPV4 regulated these mRNA expressions, but excessive compressive loading may impair TRPV4 regulation. These findings suggested that TRPV4 regulates the expression level of IL-1R and subsequent IL-1 signaling induced by cyclic compressive loading and participates in cartilage homeostasis. Supplementary Information The online version contains supplementary material available at 10.1186/s12891-021-04095-x.
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Affiliation(s)
- Yuki Takeda
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Yasuo Niki
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
| | - Yusuke Fukuhara
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Yoshitsugu Fukuda
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Kazuhiko Udagawa
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Masayuki Shimoda
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan
| | - Toshiyuki Kikuchi
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Shu Kobayashi
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Kengo Harato
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Takeshi Miyamoto
- Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Morio Matsumoto
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Masaya Nakamura
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
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McDonough RC, Gilbert RM, Gleghorn JP, Price C. Targeted Gq-GPCR activation drives ER-dependent calcium oscillations in chondrocytes. Cell Calcium 2021; 94:102363. [PMID: 33550208 DOI: 10.1016/j.ceca.2021.102363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/18/2021] [Accepted: 01/24/2021] [Indexed: 11/28/2022]
Abstract
The temporal dynamics of calcium signaling are critical regulators of chondrocyte homeostasis and chondrogenesis. Calcium oscillations regulate differentiation and anabolic processes in chondrocytes and their precursors. Attempts to control chondrocyte calcium signaling have been achieved through mechanical perturbations and synthetic ion channel modulators. However, such stimuli can lack both local and global specificity and precision when evoking calcium signals. Synthetic signaling platforms can more precisely and selectively activate calcium signaling, enabling improved dissection of the roles of intracellular calcium ([Ca2+]i) in chondrocyte behavior. One such platform is hM3Dq, a chemogenetic DREADD (Designer Receptors Exclusively Activated by Designer Drugs) that activates calcium signaling via the Gαq-PLCβ-IP3-ER pathway upon administration of clozapine N-oxide (CNO). We previously described the first-use of hM3Dq to precisely mediate targeted, synthetic calcium signals in chondrocyte-like ATDC5 cells. Here, we generated stably expressing hM3Dq-ATDC5 cells to investigate the dynamics of Gαq-GPCR calcium signaling in depth. CNO drove robust calcium responses in a temperature- and concentration-dependent (1 pM-100 μM) manner and elicited elevated levels of oscillatory calcium signaling above 10 nM. hM3Dq-mediated calcium oscillations in ATDC5 cells were reliant on ER calcium stores for both initiation and sustenance, and the downregulation and recovery dynamics of hM3Dq after CNO stimulation align with traditionally reported GPCR recycling kinetics. This study successfully generated a stable hM3Dq cell line to precisely drive Gαq-GPCR-mediated and ER-dependent oscillatory calcium signaling in ATDC5 cells and established a novel tool to elucidate the role that GPCR-mediated calcium signaling plays in chondrocyte biology, cartilage pathology, and cartilage tissue engineering.
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Affiliation(s)
- Ryan C McDonough
- Department of Biomedical Engineering, University of Delaware, United States.
| | - Rachel M Gilbert
- Department of Biomedical Engineering, University of Delaware, United States.
| | - Jason P Gleghorn
- Department of Biomedical Engineering, University of Delaware, United States.
| | - Christopher Price
- Department of Biomedical Engineering, University of Delaware, United States.
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12
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Maeda E, Kuroyanagi K, Ando Y, Matsumoto T. Effects of Substrate Stiffness on Morphology and MMP-1 Gene Expression in Tenocytes Stimulated With Interleukin-1β. J Orthop Res 2020; 38:150-159. [PMID: 31254408 DOI: 10.1002/jor.24403] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 06/18/2019] [Indexed: 02/04/2023]
Abstract
Tendon cells, tenocytes, are constantly subjected to mechanical stress in vivo, which maintains a level of cellular tension. When a tendon is subjected to overloading, local rupture of collagen fibers are induced, which deprives tenocytes of mechanical stress, lowers their cellular tension level and upregulates their catabolism. In addition, leukocytes are attracted to the rupture sites and produce interleukin-1β (IL-1β), and this exogenous IL-1β also stimulates tenocyte catabolism. We tested a hypothesis that catabolic tenocytes with low cellular tension at the rupture sites excessively respond to the exogenous IL-1β and further upregulate matrix metalloproteinase 1 (MMP-1) gene expression. Tenocytes from rabbit Achilles tendon were cultured on the following substrates: glass or polydimethylsiloxane micropillar substrates with a height of 2, 4, or 8 µm. Following a 3-day IL-1β stimulation at a concentration of 0, 1, 10, or 100 pM, the effects of IL-1β stimulation on cell morphology and MMP-1 gene expression was analysed with fluorescent microscopy and fluorescence in situ hybridization, respectively. In addition, the effects of IL-1β stimulation on cell membrane fluidity were examined. It was demonstrated that the cells on 8-µm-height micropillars exhibited a greater response than those on rigid substrates with flat (glass) and topologically the same surface (2-µm-height micropillars) to IL-1β when supplied at the same concentration. Besides this, membrane fluidity was lower in the cells on micropillars. Therefore, it appears that cellular attachment to softer substrates lowers the cellular actin cortex tension, reducing the membrane fluidity and possibly elevating the sensitivity of IL-1 receptors to ligand binding. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:150-159, 2020.
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Affiliation(s)
- Eijiro Maeda
- Biomechanics Laboratory, Department of Mechanical Systems Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Kaname Kuroyanagi
- Biomechanics Laboratory, Department of Mechanical Systems Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Yoriko Ando
- Biomechanics Laboratory, Department of Mechanical Systems Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Takeo Matsumoto
- Biomechanics Laboratory, Department of Mechanical Systems Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan
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13
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Skiöldebrand E, Ley C, Björklund U, Lindahl A, Hansson E. Serotonin-evoked cytosolic Ca 2+ release and opioid receptor expression are upregulated in articular cartilage chondrocytes from osteoarthritic joints in horses. Vet Anim Sci 2019; 8:100078. [PMID: 32734095 PMCID: PMC7386637 DOI: 10.1016/j.vas.2019.100078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 09/11/2019] [Accepted: 09/25/2019] [Indexed: 12/16/2022] Open
Abstract
Osteoarthritis is a pain-associated progressive disease and pain mediators, such as opioid receptors, expressed in articular cartilage could represent novel therapeutic targets. Acute and chronic stages of OA indicate different metabolic abilities of the chondrocytes depending on inflammatory state. This study aimed to investigate the response of healthy and osteoarthritic chondrocytes and their expression and release of pain mediators in response to acute inflammation. Interleukin-1 beta (IL-1β) and lipopolysaccharide (LPS) were used to induce an acute inflammatory response in cultured equine chondrocytes harvested from healthy joints (HC) and osteoarthritic joints (OAC), the latter representing acute exacerbation of a chronic inflammatory state. Intracellular Ca2+ release was determined after exposure to serotonin (5-hydroxytryptamine (5-HT), glutamate or ATP. Protein expression levels of F- and G-actin, representing actin rearrangement, and opioid receptors were investigated. Glutamate concentrations in culture media were measured. Cartilage was immunohistochemically stained for µ (MOR), κ (KOR), and δ (DOR) opioid receptors. Upon exposure to acute inflammatory stimuli, OAC showed increased intracellular Ca2+ release after 5-HT stimulation and increased expression of MOR and KOR. When cells were stimulated by inflammatory mediators, glutamate release was increased in both HC and OAC. Immunostaining for MOR was strong in OA cartilage, whereas KOR was less strongly expressed. DOR was not expressed by cultured HC and OAC and immunostaining of OA cartilage equivocal. We show that chondrocytes in different inflammatory stages react differently to the neurotransmitter 5-HT with respect to intracellular Ca2+ release and expression of peripheral pain mediators. Our findings suggest that opioids and neurotransmitters are important in the progression of equine OA. The inflammatory stage of OA (acute versus chronic) should be taken into consideration when therapeutic strategies are being developed.
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Affiliation(s)
- Eva Skiöldebrand
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden
- Section of Pathology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Cecilia Ley
- Section of Pathology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Ulrika Björklund
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
| | - Anders Lindahl
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden
| | - Elisabeth Hansson
- Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
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14
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Estell EG, Silverstein AM, Stefani RM, Lee AJ, Murphy LA, Shah RP, Ateshian GA, Hung CT. Cartilage Wear Particles Induce an Inflammatory Response Similar to Cytokines in Human Fibroblast-Like Synoviocytes. J Orthop Res 2019; 37:1979-1987. [PMID: 31062877 PMCID: PMC6834361 DOI: 10.1002/jor.24340] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/17/2019] [Indexed: 02/04/2023]
Abstract
The synovium plays a key role in the development of osteoarthritis, as evidenced by pathological changes to the tissue observed in both early and late stages of the disease. One such change is the attachment of cartilage wear particles to the synovial intima. While this phenomenon has been well observed clinically, little is known of the biological effects that such particles have on resident cells in the synovium. The present work investigates the hypothesis that cartilage wear particles elicit a pro-inflammatory response in diseased and healthy human fibroblast-like synoviocytes, like that induced by key cytokines in osteoarthritis. Fibroblast-like synoviocytes from 15 osteoarthritic human donors and a subset of three non-osteoarthritic donors were exposed to cartilage wear particles, interleukin-1α or tumor necrosis factor-α for 6 days and analyzed for proliferation, matrix production, and release of pro-inflammatory mediators and degradative enzymes. Wear particles significantly increased proliferation and release of nitric oxide, interleukin-6 and -8, and matrix metalloproteinase-9, -10, and -13 in osteoarthritic synoviocytes, mirroring the effects of both cytokines, with similar trends in non-osteoarthritic cells. These results suggest that cartilage wear particles are a relevant physical factor in the osteoarthritic environment, perpetuating the pro-inflammatory and pro-degradative cascade by modulating synoviocyte behavior at early and late stages of the disease. Future work points to therapeutic strategies for slowing disease progression that target cell-particle interactions. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1979-1987, 2019.
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Affiliation(s)
- Eben G. Estell
- Columbia University, Department of Biomedical Engineering, New York, NY
| | | | - Robert M. Stefani
- Columbia University, Department of Biomedical Engineering, New York, NY
| | - Andy J. Lee
- Columbia University, Department of Biomedical Engineering, New York, NY
| | - Lance A. Murphy
- Columbia University, Department of Biomedical Engineering, New York, NY
| | - Roshan P. Shah
- Columbia University, Department of Orthopedic Surgery, New York, NY
| | | | - Clark T. Hung
- Columbia University, Department of Biomedical Engineering, New York, NY
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15
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Effect of Mechanical Stretch on the DNCB-induced Proinflammatory Cytokine Secretion in Human Keratinocytes. Sci Rep 2019; 9:5156. [PMID: 30914685 PMCID: PMC6435715 DOI: 10.1038/s41598-019-41480-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 02/27/2019] [Indexed: 01/09/2023] Open
Abstract
Skin is exposed to various physico-chemical cues. Keratinocytes, a major component of the skin epidermis, directly interact with the surrounding extracellular matrix, and thus, biochemical and biophysical stimulations from the matrix regulate the function of keratinocytes. Although it was reported that inflammatory responses of skin were altered by an applied mechanical force, understanding how the keratinocytes sense the mechanical stimuli and regulate a cytokine secretion remains unclear. Here, we designed a device that is able to apply chemo-mechanical cues to keratinocytes and assess their proinflammatory cytokine IL-6 production. We showed that when chemical stimuli were applied with mechanical stimuli simultaneously, the IL-6 production markedly increased compared to that observed with a single stimulus. Quantitative structural analysis of cellular components revealed that the applied mechanical stretch transformed the cell morphology into an elongated shape, increased the cell size, and dictated the distribution of focal adhesion complex. Our results suggest that the mechanical cue-mediated modulation of focal adhesion proteins and actin cytoskeleton translates into intracellular signaling associated with the IL-6 production particularly in skin sensitization. Our study can be applied to understand proinflammatory responses of skin under altered biophysical environments of the skin.
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16
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Lv M, Zhou Y, Polson SW, Wan LQ, Wang M, Han L, Wang L, Lu XL. Identification of Chondrocyte Genes and Signaling Pathways in Response to Acute Joint Inflammation. Sci Rep 2019; 9:93. [PMID: 30643177 PMCID: PMC6331554 DOI: 10.1038/s41598-018-36500-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/21/2018] [Indexed: 01/14/2023] Open
Abstract
Traumatic joint injuries often result in elevated proinflammatory cytokine (such as IL-1β) levels in the joint cavity, which can increase the catabolic activities of chondrocytes and damage cartilage. This study investigated the early genetic responses of healthy in situ chondrocytes under IL-1β attack with a focus on cell cycle and calcium signaling pathways. RNA sequencing analysis identified 2,232 significantly changed genes by IL-1β, with 1,259 upregulated and 973 downregulated genes. Catabolic genes related to ECM degeneration were promoted by IL-1β, consistent with our observations of matrix protein loss and mechanical property decrease during 24-day in vitro culture of cartilage explants. IL-1β altered the cell cycle (108 genes) and Rho GTPases signaling (72 genes) in chondrocytes, while chondrocyte phenotypic shift was observed with histology, cell volume measurement, and MTT assay. IL-1β inhibited the spontaneous calcium signaling in chondrocytes, a fundamental signaling event in chondrocyte metabolic activities. The expression of 24 genes from 6 calcium-signaling related pathways were changed by IL-1β exposure. This study provided a comprehensive list of differentially expressed genes of healthy in situ chondrocytes in response to IL-1β attack, which represents a useful reference to verify and guide future cartilage studies related to the acute inflammation after joint trauma.
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Affiliation(s)
- Mengxi Lv
- Department of Mechanical Engineering, University of Delaware, Newark, DE, United States
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, United States
| | - Yilu Zhou
- Department of Mechanical Engineering, University of Delaware, Newark, DE, United States
| | - Shawn W Polson
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, United States
| | - Leo Q Wan
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Meiqing Wang
- Department of Oral Anatomy and Physiology and TMD, the Fourth Military Medical University, Xi'an, Shanxi, China
| | - Lin Han
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA, United States
| | - Liyun Wang
- Department of Mechanical Engineering, University of Delaware, Newark, DE, United States
| | - X Lucas Lu
- Department of Mechanical Engineering, University of Delaware, Newark, DE, United States.
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, United States.
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17
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Jenei-Lanzl Z, Meurer A, Zaucke F. Interleukin-1β signaling in osteoarthritis - chondrocytes in focus. Cell Signal 2018; 53:212-223. [PMID: 30312659 DOI: 10.1016/j.cellsig.2018.10.005] [Citation(s) in RCA: 237] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/07/2018] [Accepted: 10/08/2018] [Indexed: 12/20/2022]
Abstract
Osteoarthritis (OA) can be regarded as a chronic, painful and degenerative disease that affects all tissues of a joint and one of the major endpoints being loss of articular cartilage. In most cases, OA is associated with a variable degree of synovial inflammation. A variety of different cell types including chondrocytes, synovial fibroblasts, adipocytes, osteoblasts and osteoclasts as well as stem and immune cells are involved in catabolic and inflammatory processes but also in attempts to counteract the cartilage loss. At the molecular level, these changes are regulated by a complex network of proteolytic enzymes, chemokines and cytokines (for review: [1]). Here, interleukin-1 signaling (IL-1) plays a central role and its effects on the different cell types involved in OA are discussed in this review with a special focus on the chondrocyte.
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Affiliation(s)
- Zsuzsa Jenei-Lanzl
- Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopaedic University Hospital Friedrichsheim, Frankfurt/Main, Germany
| | - Andrea Meurer
- Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopaedic University Hospital Friedrichsheim, Frankfurt/Main, Germany
| | - Frank Zaucke
- Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopaedic University Hospital Friedrichsheim, Frankfurt/Main, Germany.
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18
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Annexin A6 regulates catabolic events in articular chondrocytes via the modulation of NF-κB and Wnt/ß-catenin signaling. PLoS One 2018; 13:e0197690. [PMID: 29771996 PMCID: PMC5957413 DOI: 10.1371/journal.pone.0197690] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 05/07/2018] [Indexed: 12/22/2022] Open
Abstract
Annexin A6 (AnxA6) is expressed in articular chondrocytes at levels higher than in other mesenchymal cell types. However, the role of AnxA6 in articular chondrocytes is not known. Here we show that complete lack of AnxA6 functions resulted in increased ß-catenin activation in Wnt3a-treated murine articular chondrocytes, whereas AnxA6 expressing articular chondrocytes showed decreased ß-catenin activation. High expression of AnxA6 in human articular chondrocytes showed the highest inhibition of Wnt/ß-catenin signaling. Inhibition of Wnt/ß-catenin signaling activity by AnxA6 together with cytosolic Ca2+ was achieved by interfering with the plasma membrane association of the Wnt signaling complex. AnxA6 also affected the cross-talk between Wnt/ß-catenin signaling and NF-κB signaling by decreasing ß-catenin activity and increasing NF-κB activity in Wnt3a-, interleukin-1beta (IL-1ß)-, and combined Wnt3a/IL-1ß-treated cells. Wnt3a treatment increased the mRNA levels of catabolic markers (cyclooxygenase-2, interleukin-6, inducible nitric oxide synthase) to a much lesser degree than IL-1ß treatment in human articular chondrocytes, and decreased the mRNA levels of matrix metalloproteinase-13 (MMP-13) and articular cartilage markers (aggrecan, type II collagen). Furthermore, Wnt3a decreased the mRNA levels of catabolic markers and MMP-13 in IL-1ß-treated human articular chondrocytes. High expression of AnxA6 resulted in decreased mRNA levels of catabolic markers, and increased MMP-13 and articular cartilage marker mRNA levels in Wnt3a-treated human articular chondrocytes, whereas leading to increased mRNA levels of catabolic markers and MMP-13 in human articular chondrocytes treated with IL-1ß, or combined Wnt3a and IL-1ß. Our findings define a novel role for AnxA6 in articular chondrocytes via its modulation of Wnt/ß-catenin and NF-κB signaling activities and the cross-talk between these two signaling pathways.
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19
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Mobasheri A, Matta C, Uzielienè I, Budd E, Martín-Vasallo P, Bernotiene E. The chondrocyte channelome: A narrative review. Joint Bone Spine 2018; 86:29-35. [PMID: 29452304 DOI: 10.1016/j.jbspin.2018.01.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 01/31/2018] [Indexed: 12/24/2022]
Abstract
Chondrocytes are the main cells in the extracellular matrix (ECM) of articular cartilage and possess a highly differentiated phenotype that is the hallmark of the unique physiological functions of this specialised load-bearing connective tissue. The plasma membrane of articular chondrocytes contains a rich and diverse complement of membrane proteins, known as the membranome, which defines the cell surface phenotype of the cells. The membranome is a key target of pharmacological agents and is important for chondrocyte function. It includes channels, transporters, enzymes, receptors, and anchors for intracellular, cytoskeletal and ECM proteins and other macromolecular complexes. The chondrocyte channelome is a sub-compartment of the membranome and includes a complete set of ion channels and porins expressed in these cells. Many of these are multi-functional proteins with "moonlighting" roles, serving as channels, receptors and signalling components of larger molecular assemblies. The aim of this review is to summarise our current knowledge of the fundamental aspects of the chondrocyte channelome, discuss its relevance to cartilage biology and highlight its possible role in the pathogenesis of osteoarthritis (OA). Excessive and inappropriate mechanical loads, an inflammatory micro-environment, alternative splicing of channel components or accumulation of basic calcium phosphate crystals can result in an altered chondrocyte channelome impairing its function. Alterations in Ca2+ signalling may lead to defective synthesis of ECM macromolecules and aggravated catabolic responses in chondrocytes, which is an important and relatively unexplored aspect of the complex and poorly understood mechanism of OA development.
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Affiliation(s)
- Ali Mobasheri
- Department of Veterinary Pre-Clinical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, United Kingdom; Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Queen's Medical Centre, Nottingham, United Kingdom; Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania.
| | - Csaba Matta
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Ilona Uzielienè
- Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania
| | - Emma Budd
- Department of Veterinary Pre-Clinical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - Pablo Martín-Vasallo
- Department of Biochemistry and Molecular Biology, University of La Laguna, Tenerife, Spain
| | - Eiva Bernotiene
- Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania
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20
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Nguyen QT, Jacobsen TD, Chahine NO. Effects of Inflammation on Multiscale Biomechanical Properties of Cartilaginous Cells and Tissues. ACS Biomater Sci Eng 2017; 3:2644-2656. [PMID: 29152560 PMCID: PMC5686563 DOI: 10.1021/acsbiomaterials.6b00671] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/24/2017] [Indexed: 12/20/2022]
Abstract
![]()
Cells
within cartilaginous tissues are mechanosensitive and thus
require mechanical loading for regulation of tissue homeostasis and
metabolism. Mechanical loading plays critical roles in cell differentiation,
proliferation, biosynthesis, and homeostasis. Inflammation is an important
event occurring during multiple processes, such as aging, injury,
and disease. Inflammation has significant effects on biological processes
as well as mechanical function of cells and tissues. These effects
are highly dependent on cell/tissue type, timing, and magnitude. In
this review, we summarize key findings pertaining to effects of inflammation
on multiscale mechanical properties at subcellular, cellular, and
tissue level in cartilaginous tissues, including alterations in mechanotransduction
and mechanosensitivity. The emphasis is on articular cartilage and
the intervertebral disc, which are impacted by inflammatory insults
during degenerative conditions such as osteoarthritis, joint pain,
and back pain. To recapitulate the pro-inflammatory cascades that
occur in vivo, different inflammatory stimuli have been used for in
vitro and in situ studies, including tumor necrosis factor (TNF),
various interleukins (IL), and lipopolysaccharide (LPS). Therefore,
this review will focus on the effects of these stimuli because they
are the best studied pro-inflammatory cytokines in cartilaginous tissues.
Understanding the current state of the field of inflammation and cell/tissue
biomechanics may potentially identify future directions for novel
and translational therapeutics with multiscale biomechanical considerations.
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Affiliation(s)
- Q T Nguyen
- Bioengineering-Biomechanics Laboratory The Feinstein Institute for Medical Research, Northwell Health System, Manhasset, New York 11030, United States
| | - T D Jacobsen
- Bioengineering-Biomechanics Laboratory The Feinstein Institute for Medical Research, Northwell Health System, Manhasset, New York 11030, United States.,Hofstra Northwell School of Medicine, Hempstead, New York 11549, United States
| | - N O Chahine
- Bioengineering-Biomechanics Laboratory The Feinstein Institute for Medical Research, Northwell Health System, Manhasset, New York 11030, United States.,Hofstra Northwell School of Medicine, Hempstead, New York 11549, United States
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21
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Xia Y, Momot KI, Chen Z, Chen CT, Kahn D, Badar F. Introduction to Cartilage. BIOPHYSICS AND BIOCHEMISTRY OF CARTILAGE BY NMR AND MRI 2016. [DOI: 10.1039/9781782623663-00001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cartilage is a supporting connective tissue that, together with the bone, forms the framework supporting the body as a whole. There are many distinct types of cartilage, which exhibit numerous similarities as well as differences. Among them, articular cartilage is the best known and the most studied type. Articular cartilage is the thin layer of connective tissue that covers the articulating ends of bones in synovial (diarthrodial) joints. It provides a smooth surface for joint movement and acts as a load-bearing medium that protects the bone and distributes stress. The intense interest in articular cartilage is motivated by the critical role its degradation plays in arthritis and related joint diseases, which are the number one cause of disability in humans. This chapter discusses the physical, chemical and cellular properties of cartilage that give the tissue its extraordinary load-bearing characteristics.
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Affiliation(s)
- Yang Xia
- Department of Physics and Center for Biomedical Research, Oakland University Rochester MI 48309 USA
| | - Konstantin I. Momot
- School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT) Brisbane Qld 4001 Australia
| | - Zhe Chen
- Department of Physics and Center for Biomedical Research, Oakland University Rochester MI 48309 USA
- Department of Radiology, Ruijin Hospital, Shanghai JiaoTong University School of Medicine Shanghai 200025 China
| | - Christopher T. Chen
- Center for Mineral Metabolism and Clinical Research / Department of Orthopedic Surgery, University of Texas Southwestern Medical Center Dallas TX 75390 USA
| | - David Kahn
- Department of Physics and Center for Biomedical Research, Oakland University Rochester MI 48309 USA
| | - Farid Badar
- Department of Physics and Center for Biomedical Research, Oakland University Rochester MI 48309 USA
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22
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Berridge MJ. The Inositol Trisphosphate/Calcium Signaling Pathway in Health and Disease. Physiol Rev 2016; 96:1261-96. [DOI: 10.1152/physrev.00006.2016] [Citation(s) in RCA: 377] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Many cellular functions are regulated by calcium (Ca2+) signals that are generated by different signaling pathways. One of these is the inositol 1,4,5-trisphosphate/calcium (InsP3/Ca2+) signaling pathway that operates through either primary or modulatory mechanisms. In its primary role, it generates the Ca2+ that acts directly to control processes such as metabolism, secretion, fertilization, proliferation, and smooth muscle contraction. Its modulatory role occurs in excitable cells where it modulates the primary Ca2+ signal generated by the entry of Ca2+ through voltage-operated channels that releases Ca2+ from ryanodine receptors (RYRs) on the internal stores. In carrying out this modulatory role, the InsP3/Ca2+ signaling pathway induces subtle changes in the generation and function of the voltage-dependent primary Ca2+ signal. Changes in the nature of both the primary and modulatory roles of InsP3/Ca2+ signaling are a contributory factor responsible for the onset of a large number human diseases.
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Affiliation(s)
- Michael J. Berridge
- Laboratory of Molecular Signalling, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, United Kingdom
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23
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Miller SL, Coughlin DG, Waldorff EI, Ryaby JT, Lotz JC. Pulsed electromagnetic field (PEMF) treatment reduces expression of genes associated with disc degeneration in human intervertebral disc cells. Spine J 2016; 16:770-6. [PMID: 26780754 DOI: 10.1016/j.spinee.2016.01.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 11/17/2015] [Accepted: 01/01/2016] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Pulsed electromagnetic field (PEMF) therapies have been applied to stimulate bone healing and to reduce the symptoms of arthritis, but the effects of PEMF on intervertebral disc (IVD) biology is unknown. PURPOSE The purpose of this study was to determine how PEMF affects gene expression of IVD cells in normal and inflammatory environments. STUDY DESIGN/SETTING This was an in vitro human cell culture and microarray gene expression study. METHODS Human annulus fibrosus (AF) and nucleus pulposus (NP) cells were separately encapsulated in alginate beads and exposed to interleukin 1α (IL-1α) (10 ng/mL) to stimulate the inflammatory environment associated with IVD degeneration and/or stimulated by PEMF for 4 hours daily for up to 7 days. RNA was isolated from each treatment group and analyzed via microarray to assess IL-1α- and PEMF-induced changes in gene expression. RESULTS Although PEMF treatment did not completely inhibit the effects of IL-1α, PEMF treatment lessened the IL-1α-induced upregulation of genes expressed in degenerated IVDs. Consistent with our previous results, after 4 days, PEMF tended to reduce IL-1α-associated gene expression of IL-6 (25%, p=.07) in NP cells and MMP13 (26%, p=.10) in AF cells. Additionally, PEMF treatment significantly diminished IL-1α-induced gene expression of IL-17A (33%, p=.01) and MMP2 (24%, p=.006) in NP cells and NFκB (11%, p=.04) in AF cells. CONCLUSIONS These results demonstrate that IVD cells are responsive to PEMF and motivate future studies to determine whether PEMF may be helpful for patients with IVD degeneration.
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Affiliation(s)
- Stephanie L Miller
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Ave, S-1161, Box 0514, San Francisco, CA, 94143, USA
| | - Dezba G Coughlin
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Ave, S-1161, Box 0514, San Francisco, CA, 94143, USA
| | - Erik I Waldorff
- Orthofix, Inc., 3451 Plano Parkway, Lewisville, TX 75056, USA
| | - James T Ryaby
- Orthofix, Inc., 3451 Plano Parkway, Lewisville, TX 75056, USA
| | - Jeffrey C Lotz
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Ave, S-1161, Box 0514, San Francisco, CA, 94143, USA.
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Lozoya OA, Gilchrist CL, Guilak F. Universally Conserved Relationships between Nuclear Shape and Cytoplasmic Mechanical Properties in Human Stem Cells. Sci Rep 2016; 6:23047. [PMID: 26976044 PMCID: PMC4792134 DOI: 10.1038/srep23047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 02/25/2016] [Indexed: 12/22/2022] Open
Abstract
The ability of cells to proliferate, differentiate, transduce extracellular signals and assemble tissues involves structural connections between nucleus and cytoskeleton. Yet, how the mechanics of these connections vary inside stem cells is not fully understood. To address those questions, we combined two-dimensional particle-tracking microrheology and morphological measures using variable reduction techniques to measure whether cytoplasmic mechanics allow for discrimination between different human adherent stem cell types and across different culture conditions. Here we show that nuclear shape is a quantifiable discriminant of mechanical properties in the perinuclear cytoskeleton (pnCSK) of various stem cell types. Also, we find the pnCSK is a region with different mechanical properties than elsewhere in the cytoskeleton, with heterogeneously distributed locations exhibiting subdiffusive features, and which obeys physical relations conserved among various stem cell types. Finally, we offer a prospective basis to discriminate between stem cell types by coupling perinuclear mechanical properties to nuclear shape.
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Affiliation(s)
- Oswaldo A Lozoya
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | | | - Farshid Guilak
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.,Departments of Orthopaedic Surgery, Biomedical Engineering, and Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA.,Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA
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Changes in Ultrastructure and Cytoskeletal Aspects of Human Normal and Osteoarthritic Chondrocytes Exposed to Interleukin-1β and Cyclical Hydrostatic Pressure. Int J Mol Sci 2015; 16:26019-34. [PMID: 26528971 PMCID: PMC4661795 DOI: 10.3390/ijms161125936] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/03/2015] [Accepted: 10/21/2015] [Indexed: 12/23/2022] Open
Abstract
The aim of this study was to examine the ultrastructure and cytoskeletal organization in human normal and Osteoarhritic (OA) chondrocytes, exposed to interleukin-1β (IL-1β) and cyclic hydrostatic pressure (HP). Morphological examination by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed differences between normal and OA chondrocytes at the nuclear and cytoplasmic level. IL-1β (5 ng/mL) induced a decrease of the number of mitochondria and Golgi bodies and a significant increase on the percentage of cells rich in vacuolization and in marginated chromatin. Cyclical HP (1–5 MPa, 0.25 Hz, for 3 h) did not change the morphology of normal chondrocytes, but had a beneficial effect on OA chondrocytes increasing the number of organelles. Normal and OA cells subjected to IL-1β and HP recovered cytoplasmic ultrastructure. Immunofluorescence (IF) examination of normal chondrocytes showed an actin signal polarized on the apical sides of the cytoplasm, tubulin and vimentin uniformly distributed throughout cytoplasm and vinculin revealed a punctuated pattern under the plasma membrane. In OA chondrocytes, these proteins partially lost their organization. Stimulation with IL-1β caused, in both type of cells, modification in the cytoskeletal organization; HP counteracted the negative effects of IL-1β. Our results showed structural differences at nuclear, cytoplasmic and cytoskeletal level between normal and OA chondrocytes. IL-1β induced ultrastructural and cytoskeletal modifications, counteracted by a cyclical low HP.
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26
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YANG FAN, HU ANFENG, ZHAO DEWEI, GUO LIN, YANG LEI, WANG BENJIE, TIAN FENGDE, LIU BAOYI, HUANG SHIBO, XIE HUI. An insertion/deletion polymorphism at the microRNA-122 binding site in the interleukin-1α 3′-untranslated region is associated with a risk for osteoarthritis. Mol Med Rep 2015; 12:6199-206. [DOI: 10.3892/mmr.2015.4121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 05/13/2015] [Indexed: 11/06/2022] Open
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27
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Kaur D, Gomez E, Doe C, Berair R, Woodman L, Saunders R, Hollins F, Rose F, Amrani Y, May R, Kearley J, Humbles A, Cohen E, Brightling C. IL-33 drives airway hyper-responsiveness through IL-13-mediated mast cell: airway smooth muscle crosstalk. Allergy 2015; 70:556-67. [PMID: 25683166 PMCID: PMC4418379 DOI: 10.1111/all.12593] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2015] [Indexed: 12/13/2022]
Abstract
Background Mast cell localization within the airway smooth muscle (ASM)-bundle plays an important role in the development of airway hyper-responsiveness (AHR). Genomewide association studies implicate the ‘alarmin’ IL-33 in asthma, but its role in mast cell–ASM interactions is unknown. Objectives We examined the expression and functional role of IL-33 in bronchial biopsies of patients with and without asthma, ex vivo ASM, mast cells, cocultured cells and in a mouse model system. Methods IL-33 protein expression was assessed in human bronchial tissue from 9 healthy controls, and 18 mild-to-moderate and 12 severe asthmatic patients by immunohistochemistry. IL-33 and ST2 mRNA and protein expression in human-derived ASM, epithelial and mast cells were assessed by qPCR, immunofluorescence and/or flow cytometry and ELISA. Functional assays were used to assess calcium signalling, wound repair, proliferation, apoptosis and contraction. AHR and inflammation were assessed in a mouse model. Results Bronchial epithelium and ASM expressed IL-33 with the latter in asthma correlating with AHR. ASM and mast cells expressed intracellular IL-33 and ST2. IL-33 stimulated mast cell IL-13 and histamine secretion independent of FcεR1 cross-linking and directly promoted ASM wound repair. Coculture of mast cells with ASM activated by IL-33 increased agonist-induced ASM contraction, and in vivo IL-33 induced AHR in a mouse cytokine installation model; both effects were IL-13 dependent. Conclusion IL-33 directly promotes mast cell activation and ASM wound repair but indirectly promotes ASM contraction via upregulation of mast cell-derived IL-13. This suggests that IL-33 may present an important target to modulate mast cell–ASM crosstalk in asthma.
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Affiliation(s)
- D. Kaur
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - E. Gomez
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - C. Doe
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - R. Berair
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - L. Woodman
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - R. Saunders
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - F. Hollins
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - F.R. Rose
- Division of Drug Delivery and Tissue Engineering, Centre for Biomolecular Sciences, School of Pharmacy; University of Nottingham UK
| | - Y. Amrani
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
| | - R. May
- MedImmune Ltd; Cambridge UK
| | | | | | | | - C.E. Brightling
- Institute for Lung Health; Department of Infection, Immunity and Inflammation; University of Leicester; Leicester UK
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Zhou Y, Park M, Cheung E, Wang L, Lu XL. The effect of chemically defined medium on spontaneous calcium signaling of in situ chondrocytes during long-term culture. J Biomech 2015; 48:990-6. [PMID: 25700610 DOI: 10.1016/j.jbiomech.2015.02.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 01/29/2015] [Accepted: 02/02/2015] [Indexed: 01/06/2023]
Abstract
Chemically defined serum-free medium has been shown to better maintain the mechanical integrity of articular cartilage explants than serum-supplemented medium during long-term in vitro culture, but little is known about its effect on cellular mechanisms. We hypothesized that the chemically defined culture medium could regulate the spontaneous calcium signaling of in situ chondrocytes, which may modulate the cellular metabolic activities. Bovine cartilage explants were cultured in chemically defined serum-free or serum-supplemented medium for four weeks. The spontaneous intracellular calcium ([Ca(2+)]i) signaling of in situ chondrocytes was longitudinally measured together along with the biomechanical properties of the explants. The spontaneous [Ca(2+)]i oscillations in chondrocytes were enhanced at the initial exposure of serum-supplemented medium, but were significantly dampened afterwards. In contrast, cartilage explants in chemically defined medium preserved the level of calcium signaling, and showed more responsive cells with higher and more frequent [Ca(2+)]i peaks throughout the four week culture in comparison to those in serum medium. Regardless of the culture medium that the explants were exposed, a positive correlation was detected between the [Ca(2+)]i responsive rate and the stiffness of cartilage (Spearman's rank correlation coefficient=0.762). A stable pattern of [Ca(2+)]i peaks was revealed for each chondrocyte, i.e., the spatiotemporal features of [Ca(2+)]i peaks from a cell were highly consistent during the observation period (15 min). This study showed that the beneficial effect of chemically defined culture of cartilage explants is associated with the spontaneous [Ca(2+)]i signaling of chondrocytes in cartilage.
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Affiliation(s)
- Yilu Zhou
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716 USA
| | - Miri Park
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716 USA
| | - Enoch Cheung
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716 USA
| | - Liyun Wang
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716 USA
| | - X Lucas Lu
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716 USA.
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Chen C, Xie J, Rajappa R, Deng L, Fredberg J, Yang L. Interleukin-1β and tumor necrosis factor-α increase stiffness and impair contractile function of articular chondrocytes. Acta Biochim Biophys Sin (Shanghai) 2015; 47:121-9. [PMID: 25520178 DOI: 10.1093/abbs/gmu116] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) are major proinflammatory cytokines involved in osteoarthritis (OA). These cytokines disturb chondrocyte metabolism by suppressing the synthesis of extracellular matrix proteins and stimulating the release of catabolic proteases, but little is known about their role in chondrocyte mechanics. Thus, the aim of this study was to measure the effects of IL-1β and TNF-α on the mechanical properties of the chondrocytes. Chondrocytes from goat knee joints were cultured in 96-well plates. The cellular stiffness and contractile function were probed using optical magnetic twisting cytometry, the cytoskeleton and the expression of extracellular matrix proteins were visualized using immunofluorescent staining, and chondrocyte phenotypical expression was measured by western blot analysis. Results showed that chondrocyte stiffness was dramatically decreased by disruption of F-actin but was unaffected by disruption of the intermediate filament vimentin. Treatment with 10 ng/ml IL-1β or 40 ng/ml TNF-α for 24 h substantially increased the expression level of F-actin and cellular stiffness, and impaired cell stiffening in response to the contractile agonist histamine, but these effects were blocked by the Rho-associated protein kinase inhibitor Y27632. In conclusion, IL-1β and TNF-α substantially change the mechanical properties of the chondrocytes in vitro. While changes of chondrocyte mechanics in vivo during OA progression remain unclear, this finding reveals a prominent role of these cytokines in cellular mechanics and provides insight for anti-cytokine therapies of OA.
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Affiliation(s)
- Cheng Chen
- Center for Joint Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, China Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
| | - Jing Xie
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu 610064, China
| | - Ravikumar Rajappa
- Tissue Engineering Laboratories, Veterans Affairs Boston Healthcare System, Boston, MA 02115, USA Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Linhong Deng
- Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou 213164, China
| | - Jeffrey Fredberg
- Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
| | - Liu Yang
- Center for Joint Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
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Sánchez JC, López-Zapata DF. Effects of Adipokines and Insulin on Intracellular pH, Calcium Concentration, and Responses to Hypo-Osmolarity in Human Articular Chondrocytes from Healthy and Osteoarthritic Cartilage. Cartilage 2015; 6:45-54. [PMID: 26069708 PMCID: PMC4462245 DOI: 10.1177/1947603514553095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE To evaluate the effects of adipokines and insulin on intracellular calcium concentration ([Ca(2+)]i) and pH (pHi) in human articular chondrocytes from healthy (CHC) and osteoarthritic cartilage (COC). DESIGN pHi and [Ca(2+)]i were measured using BCECF and Fura-2 fluorometric probes in CHC and COC under control conditions and following a hypotonic shock. The effects of interleukin-1β (IL1β), tumor necrosis factor-α (TNFα), insulin, leptin, resistin, and adiponectin were assessed. RESULTS pHi was lower in COC than in CHC. Only IL1β β decreased pHi in both cell types; all the agents enhanced pHi recovery following an ammonium prepulse in CHC, effect that was attenuated by Na(+)-H(+) exchanger inhibitors, but they had no effect in COC. Hypotonic shock (HTS) caused a pHi increase, which was significantly smaller in COC. All the hormones attenuated this response and the effect of IL1β was greater. The basal [Ca(2+)]i was similar in COC and CHC; IL1β, TNFα, and insulin increased the [Ca(2+)]i, but leptin, resistin, and adiponectin did not. These effects were greater in COC. This [Ca(2+)]i increase was dependent on extracellular Ca(2+) and attenuated by Na(+)-Ca(2+) exchanger inhibitors. HTS caused a [Ca(2+)]i increase, which was inhibited by transient receptor potential vanilloid blockers and attenuated by all the hormones tested with the exception of adiponectin. CONCLUSIONS These findings may help explain the association between obesity and osteoarthritis, in which these hormones are altered. The responses of CHC and COC are different, which suggests that a modification of pH and Ca(2+) homeostasis is part of the osteoarthritis pathophysiology.
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Affiliation(s)
- Julio C. Sánchez
- Faculty of Health Sciences, Universidad Tecnológica de Pereira, Pereira, Colombia
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31
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TRPV4 channels activity in bovine articular chondrocytes: Regulation by obesity-associated mediators. Cell Calcium 2014; 56:493-503. [DOI: 10.1016/j.ceca.2014.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 10/14/2014] [Accepted: 10/16/2014] [Indexed: 01/22/2023]
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Interleukin-1β promotes the LC3-mediated secretory function of osteoclast precursors by stimulating the Ca2+-dependent activation of ERK. Int J Biochem Cell Biol 2014; 54:198-207. [DOI: 10.1016/j.biocel.2014.07.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 07/02/2014] [Accepted: 07/25/2014] [Indexed: 11/24/2022]
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Han W, Heo SJ, Driscoll T, Boggs M, Duncan R, Mauck R, Elliott D. Impact of cellular microenvironment and mechanical perturbation on calcium signalling in meniscus fibrochondrocytes. Eur Cell Mater 2014; 27:321-31. [PMID: 24908425 PMCID: PMC4382367 DOI: 10.22203/ecm.v027a23] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Mechanical signals regulate a multitude of cell functions and ultimately govern fibrous tissue growth, maintenance and repair. Such mechanotransduction processes often involve modulation of intracellular calcium concentration ([Ca2+]i). However, most studies interrogate these responses in cells in simplified culture systems, thereby removing potentially important inputs from the native extracellular microenvironment. The objective of this study was to test the hypothesis that the intracellular calcium response of meniscus fibrochondrocytes (MFCs) is dependent on both the microenvironmental context in which this perturbation is applied and on the tensile deformation. Using a custom micro-mechanical tester mounted on a confocal microscope, intracellular calcium activity in MFCs in response to incremental tissue strains (0, 3, 6 and 9 %) was monitored in situ (i.e., in the native tissues) on MFC-seeded aligned scaffolds and MFC-seeded silicone membranes. The [Ca2+]i regulation by MFCs within the native meniscus tissue microenvironment was considerably different from [Ca2+]i regulation by MFCs on either aligned nanofibrous scaffolds or flat silicone membranes. Additionally, increasing levels of tensile deformation resulted in a greater number of responding cells, both in situ and in vitro, while having no effects on temporal characteristics of [Ca2+]i signalling. Collectively, these findings have significant implications for mechanobiology of load-bearing fibrous tissues and their responses to injury and degeneration. In addition, from a tissue engineering perspective, the findings establish cellular benchmarks for maturing engineered constructs, where native tissue-like calcium mechano-regulation may be an important outcome parameter to achieve mechanical functionality comparable to native tissue.
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Affiliation(s)
- W.M. Han
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - S-J. Heo
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA,Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - T.P. Driscoll
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA,Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M.E. Boggs
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - R.L. Duncan
- Department of Biological Sciences, University of Delaware, Newark, DE, USA,Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - R.L. Mauck
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA,Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - D.M. Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA,Address for correspondence: Dawn M. Elliott, Biomedical Engineering, University of Delaware, 125 E. Delaware Ave., Newark, DE 19716, USA, Telephone Number: 1-302-831-1295,
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Parekh R, Lorenzo MK, Shin SY, Pozzi A, Clark AL. Integrin α1β1 differentially regulates cytokine-mediated responses in chondrocytes. Osteoarthritis Cartilage 2014; 22:499-508. [PMID: 24418674 PMCID: PMC4028170 DOI: 10.1016/j.joca.2013.12.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/07/2013] [Accepted: 12/25/2013] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To elucidate the role of integrin α1β1 in chondrocyte responses to inflammatory interleukin-1α (IL-1) and anabolic transforming growth factor-β1 (TGF-β1) in the knee. METHODS Intracellular calcium transient responses to IL-1 and TGF-β1 were measured in wild type and integrin α1-null chondrocytes using real time ex vivo confocal microscopy, and immunohistochemistry was performed to analyze TGF-β1-mediated activation of Smad2/3 in tibial and femoral chondrocytes. RESULTS Loss of integrin α1β1 reduces intracellular calcium transient response to IL-1, while it enhances chondrocyte responses to TGF-β1 as measured by intracellular calcium transients and activation of downstream Smad2/3. CONCLUSIONS Integrin α1β1 plays a vital role in mediating chondrocyte responses to two contrasting factors that are critical players in the onset and progression of osteoarthritis - inflammatory IL-1 and anabolic TGF-β. Further investigation into the molecular mechanisms by which integrin α1β1 mediates these responses will be an important next step in understanding the influence of increased expression of integrin α1β1 during the early stages of osteoarthritis on disease progression.
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Affiliation(s)
- R Parekh
- Faculty of Science, The University of Calgary, Calgary, AB, Canada
| | - MK Lorenzo
- Faculty of Science, The University of Calgary, Calgary, AB, Canada
| | - SY Shin
- Faculty of Kinesiology, The University of Calgary, Calgary, AB, Canada
| | - A Pozzi
- Department of Medicine, Vanderbilt University, Nashville, TN, USA,Department of Medicine, Veterans Affairs Hospital, Nashville, TN, USA
| | - AL Clark
- Faculty of Kinesiology, The University of Calgary, Calgary, AB, Canada,Department of Surgery, Faculty of Medicine, The University of Calgary, Calgary, AB, Canada
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McNulty AL, Rothfusz NE, Leddy HA, Guilak F. Synovial fluid concentrations and relative potency of interleukin-1 alpha and beta in cartilage and meniscus degradation. J Orthop Res 2013; 31:1039-45. [PMID: 23483596 PMCID: PMC4037157 DOI: 10.1002/jor.22334] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 02/05/2013] [Indexed: 02/04/2023]
Abstract
Cartilage degeneration with osteoarthritis (OA) is believed to involve the activities of interleukin-1 (IL-1), which exists as alpha and beta isoforms. The goal of this study was to measure the concentrations of both isoforms of IL-1 in the synovial fluid of normal and spontaneously osteoarthritic porcine knees, and to test the hypothesis that physiologic concentrations of IL-1α and IL-1β exhibit different potencies in activating calcium signaling, the production of matrix metalloproteinases and nitric oxide, and the loss of proteoglycans and tissue mechanical properties in cartilage and meniscus. Median concentrations of IL-1α were 0.043 ng/ml with mild OA and 0.288 ng/ml with moderate OA, whereas IL-1β concentrations were 0.109 ng/ml with mild OA and 0.122 ng/ml with moderate OA. Both isoforms induced calcium signaling in chondrocytes and meniscal cells at all concentrations. Overall, cartilage and meniscus catabolism was significantly more sensitive to IL-1α than IL-1β at concentrations of 1 ng/ml or less, while few differences were observed between the two forms at 10 ng/ml. These data provide a range of physiologic IL-1 concentrations that can serve as a framework for the comparison of various in vitro studies, as well as providing further insight for the development of anti-cytokine therapies for OA.
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Affiliation(s)
- Amy L. McNulty
- Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA
| | - Nicole E. Rothfusz
- Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA
| | - Holly A. Leddy
- Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA
| | - Farshid Guilak
- Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA,Department of Biomedical Engineering, Duke University, Durham, NC, USA,Corresponding author: Farshid Guilak, Ph.D., Duke University Medical Center, Box 3093, Durham, NC 27710, Phone (919) 684-2521, Fax (919) 681-8490,
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Ma B, Landman EBM, Miclea RL, Wit JM, Robanus-Maandag EC, Post JN, Karperien M. WNT signaling and cartilage: of mice and men. Calcif Tissue Int 2013; 92:399-411. [PMID: 23212543 DOI: 10.1007/s00223-012-9675-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 11/03/2012] [Indexed: 01/08/2023]
Abstract
In adult articular cartilage, the extracellular matrix is maintained by a balance between the degradation and the synthesis of matrix components. Chondrocytes that sparsely reside in the matrix and rarely proliferate are the key cellular mediators for cartilage homeostasis. There are indications for the involvement of the WNT signaling pathway in maintaining articular cartilage. Various WNTs are involved in the subsequent stages of chondrocyte differentiation during development, and deregulation of WNT signaling was observed in cartilage degeneration. Even though gene expression and protein synthesis can be activated upon injury, articular cartilage has a limited ability of self-repair and efforts to regenerate articular cartilage have so far not been successful. Because WNT signaling was found to be involved in the development and maintenance of cartilage as well as in the degeneration of cartilage, interfering with this pathway might contribute to improving cartilage regeneration. However, most of the studies on elucidating the role of WNT signaling in these processes were conducted using in vitro or in vivo animal models. Discrepancies have been found in the role of WNT signaling between chondrocytes of mouse and human origin, and extrapolation of results from mouse models to the human situation remains a challenge. Elucidation of detailed WNT signaling functions will provide knowledge to improve cartilage regeneration.
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Affiliation(s)
- Bin Ma
- Department of Developmental BioEngineering, University of Twente, Drienerlolaan 5, 7522NB, Enschede, The Netherlands
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Chaudhry SI, Hooper S, Nye E, Williamson P, Harrington K, Sahai E. Autocrine IL-1β-TRAF6 signalling promotes squamous cell carcinoma invasion through paracrine TNFα signalling to carcinoma-associated fibroblasts. Oncogene 2013; 32:747-58. [PMID: 22450746 PMCID: PMC3446864 DOI: 10.1038/onc.2012.91] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 01/25/2012] [Accepted: 02/12/2012] [Indexed: 12/13/2022]
Abstract
The invasion of squamous cell carcinoma (SCC) is a significant cause of morbidity and mortality. Here, we identify an E3 ligase, Traf6 and a de-ubiquitinating enzyme, Cezanne/ZA20D1, as important regulators of this process in organotypic models. Traf6 can promote the formation of Cdc42-dependent F-actin microspikes. Furthermore, Traf6 has a key role in autocrine interleukin-1β signalling in SCC cells, which in turn is required to drive the expression of tumour necrosis factor α (TNFα). TNFα acts in a paracrine manner to increase the invasion-promoting potential of carcinoma-associated fibroblasts (CAFs). Exogenous TNFα signalling can restore invasion in cells depleted of Traf6. In conclusion, Traf6 has two important roles in SCC invasion: it promotes cell intrinsic Cdc42-dependent regulation of the actin cytoskeleton and enables production of the paracrine signal, TNFα, that enhances the activity of CAFs.
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Affiliation(s)
- S I Chaudhry
- Tumour Cell Biology Laboratory, Cancer Research UK London Research Institute, London, UK
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38
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van der Kraan PM. Relevance of zebrafish as an OA research model. Osteoarthritis Cartilage 2013; 21:261-2. [PMID: 23287582 DOI: 10.1016/j.joca.2012.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 12/20/2012] [Indexed: 02/02/2023]
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Varshavsky A. Augmented generation of protein fragments during wakefulness as the molecular cause of sleep: a hypothesis. Protein Sci 2012; 21:1634-61. [PMID: 22930402 PMCID: PMC3527701 DOI: 10.1002/pro.2148] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 08/21/2012] [Indexed: 02/05/2023]
Abstract
Despite extensive understanding of sleep regulation, the molecular-level cause and function of sleep are unknown. I suggest that they originate in individual neurons and stem from increased production of protein fragments during wakefulness. These fragments are transient parts of protein complexes in which the fragments were generated. Neuronal Ca²⁺ fluxes are higher during wakefulness than during sleep. Subunits of transmembrane channels and other proteins are cleaved by Ca²⁺-activated calpains and by other nonprocessive proteases, including caspases and secretases. In the proposed concept, termed the fragment generation (FG) hypothesis, sleep is a state during which the production of fragments is decreased (owing to lower Ca²⁺ transients) while fragment-destroying pathways are upregulated. These changes facilitate the elimination of fragments and the remodeling of protein complexes in which the fragments resided. The FG hypothesis posits that a proteolytic cleavage, which produces two fragments, can have both deleterious effects and fitness-increasing functions. This (previously not considered) dichotomy can explain both the conservation of cleavage sites in proteins and the evolutionary persistence of sleep, because sleep would counteract deleterious aspects of protein fragments. The FG hypothesis leads to new explanations of sleep phenomena, including a longer sleep after sleep deprivation. Studies in the 1970s showed that ethanol-induced sleep in mice can be strikingly prolonged by intracerebroventricular injections of either Ca²⁺ alone or Ca²⁺ and its ionophore (Erickson et al., Science 1978;199:1219-1221; Harris, Pharmacol Biochem Behav 1979;10:527-534; Erickson et al., Pharmacol Biochem Behav 1980;12:651-656). These results, which were never interpreted in connection to protein fragments or the function of sleep, may be accounted for by the FG hypothesis about molecular causation of sleep.
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Affiliation(s)
- Alexander Varshavsky
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
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Nguyen C, Lieberherr M, Bordat C, Velard F, Côme D, Lioté F, Ea HK. Intracellular calcium oscillations in articular chondrocytes induced by basic calcium phosphate crystals lead to cartilage degradation. Osteoarthritis Cartilage 2012; 20:1399-408. [PMID: 22885567 DOI: 10.1016/j.joca.2012.07.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 07/18/2012] [Accepted: 07/25/2012] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Basic calcium phosphate (BCP) crystals, including octacalcium phosphate (OCP), carbonated-apatite (CA) and hydroxyapatite (HA) crystals are associated with destructive forms of osteoarthritis. Mechanisms of BCP-induced cartilage breakdown remain incompletely understood. We assessed the ability of BCP to induce changes in intracellular calcium (iCa(2+)) content and oscillations and the role of iCa(2+) in BCP-induced cartilage degradation. METHODS Bovine articular chondrocytes (BACs) and bovine cartilage explants (BCEs) were stimulated with BCP or monosodium urate (MSU) crystals. iCa(2+) levels were determined by spectrofluorimetry and oscillations by confocal microscopy. mRNA expression of matrix metalloproteinase 3 (MMP-3), a disintegrin and metalloprotease with thrombospondin-like motifs 4 (ADAMTS-4) and ADAMTS-5 was assessed by quantitative real-time PCR. Glycosaminoglycan (GAG) release was measured in the supernatants of BCE cultures. RESULTS All three BCP crystals significantly increased iCa(2+) content. OCP also induced iCa(2+) oscillations. Rate of BACs displaying iCa(2+) oscillations increased over time, with a peak after 20 min of stimulation. OCP-induced iCa(2+) oscillations involved both extracellular Ca(2+) (eCa(2+)) influx and iCa(2+) stores. Indeed, OCP-induced iCa(2+) oscillations decreased rapidly in Ca(2+)-free medium. Both voltage- and non-voltage-dependent Ca(2+) channels were involved in eCa(2+) influx. BCP crystal-induced variation in iCa(2+) content was associated with BCP crystal-induced cartilage matrix degradation. However, iCa²(+) was not associated with OCP crystal-induced mRNA expression of MMP-3, ADAMTS-4 or ADAMTS-5. CONCLUSION BCP crystals can induce variation in iCa(2+) content and oscillations in articular chondrocytes. Furthermore, BCP crystal-induced changes in iCa(2+) content play a pivotal role in BCP catabolic effects on articular cartilage.
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Affiliation(s)
- C Nguyen
- Univ Paris Diderot, Sorbonne Paris Cité, INSERM, UMR-S 606, F-75205 Paris, France
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Wann AKT, Knight MM. Primary cilia elongation in response to interleukin-1 mediates the inflammatory response. Cell Mol Life Sci 2012; 69:2967-77. [PMID: 22481441 PMCID: PMC3417094 DOI: 10.1007/s00018-012-0980-y] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 03/20/2012] [Accepted: 03/22/2012] [Indexed: 01/12/2023]
Abstract
Primary cilia are singular, cytoskeletal organelles present in the majority of mammalian cell types where they function as coordinating centres for mechanotransduction, Wnt and hedgehog signalling. The length of the primary cilium is proposed to modulate cilia function, governed in part by the activity of intraflagellar transport (IFT). In articular cartilage, primary cilia length is increased and hedgehog signaling activated in osteoarthritis (OA). Here, we examine primary cilia length with exposure to the quintessential inflammatory cytokine interleukin-1 (IL-1), which is up-regulated in OA. We then test the hypothesis that the cilium is involved in mediating the downstream inflammatory response. Primary chondrocytes treated with IL-1 exhibited a 50 % increase in cilia length after 3 h exposure. IL-1-induced cilia elongation was also observed in human fibroblasts. In chondrocytes, this elongation occurred via a protein kinase A (PKA)-dependent mechanism. G-protein coupled adenylate cyclase also regulated the length of chondrocyte primary cilia but not downstream of IL-1. Chondrocytes treated with IL-1 exhibit a characteristic increase in the release of the inflammatory chemokines, nitric oxide and prostaglandin E2. However, in cells with a mutation in IFT88 whereby the cilia structure is lost, this response to IL-1 was significantly attenuated and, in the case of nitric oxide, completely abolished. Inhibition of IL-1-induced cilia elongation by PKA inhibition also attenuated the chemokine response. These results suggest that cilia assembly regulates the response to inflammatory cytokines. Therefore, the cilia proteome may provide a novel therapeutic target for the treatment of inflammatory pathologies, including OA.
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Affiliation(s)
- A K T Wann
- Biomedical Engineering, 2nd Floor Cell and Tissue Laboratories, School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK.
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Riera KM, Rothfusz NE, Wilusz RE, Weinberg JB, Guilak F, McNulty AL. Interleukin-1, tumor necrosis factor-alpha, and transforming growth factor-beta 1 and integrative meniscal repair: influences on meniscal cell proliferation and migration. Arthritis Res Ther 2011; 13:R187. [PMID: 22087734 PMCID: PMC3334636 DOI: 10.1186/ar3515] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/08/2011] [Accepted: 11/16/2011] [Indexed: 12/29/2022] Open
Abstract
Introduction Interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α) are up-regulated in injured and osteoarthritic knee joints. IL-1 and TNF-α inhibit integrative meniscal repair; however, the mechanisms by which this inhibition occurs are not fully understood. Transforming growth factor-β1 (TGF-β1) increases meniscal cell proliferation and accumulation, and enhances integrative meniscal repair. An improved understanding of the mechanisms modulating meniscal cell proliferation and migration will help to improve approaches for enhancing intrinsic or tissue-engineered repair of the meniscus. The goal of this study was to examine the hypothesis that IL-1 and TNF-α suppress, while TGF-β1 enhances, cellular proliferation and migration in cell and tissue models of meniscal repair. Methods A micro-wound assay was used to assess meniscal cell migration and proliferation in response to the following treatments for 0, 24, or 48 hours: 0 to 10 ng/mL IL-1, TNF-α, or TGF-β1, in the presence or absence of 10% serum. Proliferated and total cells were fluorescently labeled and imaged using confocal laser scanning microscopy and the number of proliferated, migrated, and total cells was determined in the micro-wound and edges of each image. Meniscal cell proliferation was also assessed throughout meniscal repair model explants treated with 0 or 10 ng/mL IL-1, TNF-α, or TGF-β1 for 14 days. At the end of the culture period, biomechanical testing and histological analyses were also performed. Statistical differences were assessed using an ANOVA and Newman-Keuls post hoc test. Results IL-1 and TNF-α decreased cell proliferation in both cell and tissue models of meniscal repair. In the presence of serum, TGF-β1 increased outer zone cell proliferation in the micro-wound and in the cross section of meniscal repair model explants. Both IL-1 and TNF-α decreased the integrative shear strength of repair and extracellular matrix deposition in the meniscal repair model system, while TGF-β1 had no effect on either measure. Conclusions Meniscal cell proliferation in vivo may be diminished following joint injury due to the up-regulation of inflammatory cytokines, thereby limiting native cellular repair of meniscal lesions. Therefore, therapies that can promote meniscal cell proliferation have promise to enhance meniscal repair and improve tissue engineering strategies.
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Affiliation(s)
- Katherine M Riera
- Department of Orthopaedic Surgery, Duke University Medical Center, DUMC Box 3093, Durham, NC 27710, USA
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Nalesso G, Sherwood J, Bertrand J, Pap T, Ramachandran M, De Bari C, Pitzalis C, Dell'accio F. WNT-3A modulates articular chondrocyte phenotype by activating both canonical and noncanonical pathways. ACTA ACUST UNITED AC 2011; 193:551-64. [PMID: 21536751 PMCID: PMC3087013 DOI: 10.1083/jcb.201011051] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A single Wnt can simultaneously activate different pathways with distinct and independent outcomes and reciprocal regulation in human articular chondrocytes. Activation and disruption of Wnt/β-catenin signaling both result in cartilage breakdown via unknown mechanisms. Here we show that both WNT-3A and the Wnt inhibitor DKK1 induced de-differentiation of human articular chondrocytes through simultaneous activation of β-catenin–dependent and independent responses. WNT-3A activates both the β-catenin–dependent canonical pathway and the Ca2+/CaMKII noncanonical pathways, with distinct transcriptional targets. WNT-3A promotes cell proliferation and loss of expression of the chondrocyte markers COL2A1, Aggrecan, and SOX9; however, proliferation and AXIN2 up-regulation are downstream of the canonical pathway and are rescued by DKK1, whereas the loss of differentiation markers is CaMKII dependent. Finally, we showed that in chondrocytes, the Ca2+/CaMKII-dependent and β-catenin–dependent pathways are reciprocally inhibitory, thereby explaining why DKK1 can induce loss of differentiation through de-repression of the CaMKII pathway. We propose a novel model in which a single WNT can simultaneously activate different pathways with distinct and independent outcomes and with reciprocal regulation. This offers an opportunity for selective pharmacological targeting.
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Affiliation(s)
- Giovanna Nalesso
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London EC1M6BQ, England, UK
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Santos A, Bakker AD, de Blieck-Hogervorst JMA, Klein-Nulend J. WNT5A induces osteogenic differentiation of human adipose stem cells via rho-associated kinase ROCK. Cytotherapy 2011; 12:924-32. [PMID: 20429785 DOI: 10.3109/14653241003774011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND AIMS Human (h) adipose tissue-derived mesenchymal stromal cells (ASC) constitute an interesting cellular source for bone tissue engineering applications. Wnts, for example Wnt5a, are probably important regulators of osteogenic differentiation of stem cells, but the role of Wnt5a in hASC lineage commitment and the mechanisms activated upon Wnt5a binding are unknown. We examined whether Wnt5a induces osteogenic and/or adipogenic differentiation of hASC. METHODS hASC were incubated for 7 days with or without Wnt5a, rho-associated kinase (ROCK)-activity inhibitor Y27632 or Wnt3a. Cells were lysed for total RNA isolation, DNA content and alkaline phosphatase (ALP) activity. Mineralized nodule formation and gene expression of osteogenic markers osteocalcin and runt-related protein-2 (RUNX2), and adipogenic markers peroxisome proliferator activator receptor-γ (PPARγ) and transcription factor apetala-2 (aP2), were analyzed. hASC were incubated with Wnt5a or Wnt3a to determine activation of canonical and/or non-canonical Wnt signaling pathways, and protein kinase C activity (PKC), total ß-catenin content and gene expression of connexin 43 and cyclin D1 were quantified. RESULTS Wnt5a increased ALP activity and RUNX2 and osteocalcin gene expression, and down-regulated adipogenic markers through ROCK activity. Wnt5a also induced mineralized nodule formation. Wnt3a only enhanced RUNX2 and osteocalcin gene expression, and did not induce osteogenic differentiation. Wnt5a activated the non-canonical Wnt signaling pathway by increasing PKC activity, while Wnt3a mildly activated the Wnt canonical pathway by increasing total ß-catenin content and connexin 43 and cyclin D1 gene expression. CONCLUSIONS Our data illustrate the importance of Wnt5a as a stimulator of hASC osteogenic differentiation, and show that changes in actin cytoskeleton controlled by ROCK are determinants for Wnt5a-induced osteogenic differentiation of hASC.
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Affiliation(s)
- Ana Santos
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Research Institute MOVE, Amsterdam, the Netherlands
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Fluoride inhibits the response of bone cells to mechanical loading. Odontology 2011; 99:112-8. [DOI: 10.1007/s10266-011-0013-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 12/03/2010] [Indexed: 12/22/2022]
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Ong SB, Shah D, Qusous A, Jarvis SM, Kerrigan MJ. Stimulation of regulatory volume increase (RVI) in avian articular chondrocytes by gadolinium chloride. Biochem Cell Biol 2010; 88:505-12. [DOI: 10.1139/o09-179] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chondrocytes, the resident cell-type of articular cartilage, are responsible for the regulation of the extracellular matrix (ECM) in response to their physico-chemical environment. Due to the nature of cartilage loading, chondrocytes are exposed to constant changes in extracellular osmolality with a gradual increase throughout the day. As an increase in osmolality attenuates matrix synthesis, we have studied cell volume regulation (regulatory volume increase (RVI)) after hypertonic challenge and the regulation of RVI by the actin cytoskeleton. Using freshly isolated avian articular chondrocytes, changes in actin organisation were studied by confocal laser scanning microscopy following a 43% increase in extracellular osmolality. Using calcein-loading chondrocytes, the capacity for RVI was determined and the rate of volume recovery (t1/2) mathematically extrapolated. Following an increase in extracellular osmolality there was a significant increase (p < 0.05) in cortical actin, inhibited by the removal of extracellular calcium EGTA or by the addition of 100 µmol·L–1 gadolinium chloride. Most cells exhibited slow RVI (t1/2 = 55.5 ± 5.5 min), whereby inhibition of actin polymerisation by gadolinium chloride or the removal of extracellular calcium significantly increased the rate of volume recovery via a bumetanide-sensitive pathway (t1/2 of 29.6 ± 6.5 min and 13.8 ± 3.1 min, respectively). These data suggest the Na+–K+–2Cl– (NKCC) co-transporter regulated by the actin cytoskeleton is involved in avian chondrocyte RVI.
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Affiliation(s)
- Sang-Bing Ong
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Dinesh Shah
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Ala Qusous
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Simon M. Jarvis
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
| | - Mark J.P. Kerrigan
- Department of Human & Health Sciences, School of Life Sciences, University of Westminster, 115 New Cavendish St., London W1W 6UW, UK
- The Hatter Cardiovascular Institute, University College London Hospital & Medical School, 67 Chenies Mews, London WC1E 6HX, UK
- University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK
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White R, Gibson JS. The effect of oxygen tension on calcium homeostasis in bovine articular chondrocytes. J Orthop Surg Res 2010; 5:27. [PMID: 20420658 PMCID: PMC2873548 DOI: 10.1186/1749-799x-5-27] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 04/26/2010] [Indexed: 01/11/2023] Open
Abstract
Background Articular chondrocytes normally experience a lower O2 tension compared to that seen by many other tissues. This level may fall further in joint disease. Ionic homeostasis is essential for chondrocyte function but, at least in the case of H+ ions, it is sensitive to changes in O2 levels. Ca2+ homeostasis is also critical but the effect of changes in O2 tension has not been investigated on this parameter. Here we define the effect of hypoxia on Ca2+ homeostasis in bovine articular chondrocytes. Methods Chondrocytes from articular cartilage slices were isolated enzymatically using collagenase. Cytoplasmic Ca2+ levels ([Ca2+]i) were followed fluorimetrically using Fura-2 to determine the effect of changes in O2 tension. The effects of ion substitution (replacing extracellular Na+ with NMDG+ and chelating Ca2+ with EGTA) were tested. Levels of reactive oxygen species (ROS) and the mitochondrial membrane potential were measured and correlated with [Ca2+]i. Results A reduction in O2 tension from 20% to 1% for 16-18 h caused [Ca2+]i to approximately double, reaching 105 ± 23 nM (p < 0.001). Ion substitutions indicated that Na+/Ca2+ exchange activity was not inhibited at low O2 levels. At 1% O2, ROS levels fell and mitochondria depolarised. Restoring ROS levels (with an oxidant H2O2, a non-specific ROS generator Co2+ or the mitochondrial complex II inhibitor antimycin A) concomitantly reduced [Ca2+]i. Conclusions O2 tension exerts a significant effect on [Ca2+]i. The proposed mechanism involves ROS from mitochondria. Findings emphasise the importance of using realistic O2 tensions when studying the physiology and pathology of articular cartilage and the potential interactions between O2, ROS and Ca2+.
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Affiliation(s)
- Rachel White
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 OES, UK.
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Bakker AD, Silva VCD, Krishnan R, Bacabac RG, Blaauboer ME, Lin YC, Marcantonio RAC, Cirelli JA, Klein-Nulend J. Tumor necrosis factor alpha and interleukin-1beta modulate calcium and nitric oxide signaling in mechanically stimulated osteocytes. ACTA ACUST UNITED AC 2010; 60:3336-45. [PMID: 19877030 DOI: 10.1002/art.24920] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Inflammatory diseases often coincide with reduced bone mass. Mechanoresponsive osteocytes regulate bone mass by maintaining the balance between bone formation and resorption. Despite its biologic significance, the effect of inflammation on osteocyte mechanoresponsiveness is not understood. To fill this gap, we investigated whether the inflammatory cytokines tumor necrosis factor alpha (TNFalpha) and interleukin-1beta (IL-1beta) modulate the osteocyte response to mechanical loading. METHODS MLO-Y4 osteocytes were incubated with TNFalpha (0.5-30 ng/ml) or IL-1beta (0.1-10 ng/ml) for 30 minutes or 24 hours, or with calcium inhibitors for 30 minutes. Cells were subjected to mechanical loading by pulsatile fluid flow (mean +/- amplitude 0.7 +/- 0.3 Pa, 5 Hz), and the response was quantified by measuring nitric oxide (NO) production using Griess reagent and by measuring intracellular calcium concentration ([Ca(2+)](i)) using Fluo-4/AM. Focal adhesions and filamentous actin (F-actin) were visualized by immunostaining, and apoptosis was quantified by measuring caspase 3/7 activity. Cell-generated tractions were quantified using traction force microscopy, and cytoskeletal stiffness was quantified using optical magnetic twisting cytometry. RESULTS Pulsatile fluid flow increased [Ca(2+)](i) within seconds (in 13% of cells) and NO production within 5 minutes (4.7-fold). TNFalpha and IL-1beta inhibited these responses. Calcium inhibitors decreased pulsatile fluid flow-induced NO production. TNFalpha and IL-1beta affected cytoskeletal stiffness, likely because 24 hours of incubation with TNFalpha and IL-1beta decreased the amount of F-actin. Incubation with IL-1beta for 24 hours stimulated osteocyte apoptosis. CONCLUSION Our results suggest that TNFalpha and IL-1beta inhibit mechanical loading-induced NO production by osteocytes via abrogation of pulsatile fluid flow-stimulated [Ca(2+)](i), and that IL-1beta stimulates osteocyte apoptosis. Since both NO and osteocyte apoptosis affect osteoclasts, these findings provide a mechanism by which inflammatory cytokines might contribute to bone loss and consequently affect bone mass in rheumatoid arthritis.
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Affiliation(s)
- A D Bakker
- ACTA-Universiteit van Amsterdam and Vrije Universiteit, Research Institute MOVE, Amsterdam, The Netherlands
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Phan MN, Leddy HA, Votta BJ, Kumar S, Levy DS, Lipshutz DB, Lee SH, Liedtke W, Guilak F. Functional characterization of TRPV4 as an osmotically sensitive ion channel in porcine articular chondrocytes. ACTA ACUST UNITED AC 2009; 60:3028-37. [PMID: 19790068 DOI: 10.1002/art.24799] [Citation(s) in RCA: 221] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Transient receptor potential vanilloid 4 (TRPV4) is a Ca(2+)-permeable channel that can be gated by tonicity (osmolarity) and mechanical stimuli. Chondrocytes, the cells in cartilage, respond to their osmotic and mechanical environments; however, the molecular basis of this signal transduction is not fully understood. This study was undertaken to demonstrate the presence and functionality of TRPV4 in chondrocytes. METHODS TRPV4 protein expression was measured by immunolabeling and Western blotting. In response to TRPV4 agonist/antagonists, osmotic stress, and interleukin-1 (IL-1), changes in Ca(2+) signaling, cell volume, and prostaglandin E(2) (PGE(2)) production were measured in porcine chondrocytes using fluorescence microscopy, light microscopy, or immunoassay, respectively. RESULTS TRPV4 was expressed abundantly at the RNA and protein levels. Exposure to 4alpha-phorbol 12,13-didecanoate (4alphaPDD), a TRPV4 activator, caused Ca(2+) signaling in chondrocytes, which was blocked by the selective TRPV4 antagonist, GSK205. Blocking TRPV4 diminished the chondrocytes' response to hypo-osmotic stress, reducing the fraction of Ca(2+) responsive cells, the regulatory volume decrease, and PGE(2) production. Ca(2+) signaling was inhibited by removal of extracellular Ca(2+) or depletion of intracellular stores. Specific activation of TRPV4 restored the defective regulatory volume decrease caused by IL-1. Chemical disruption of the primary cilium eliminated Ca(2+) signaling in response to either 4alphaPDD or hypo-osmotic stress. CONCLUSION Our findings indicate that TRPV4 is present in articular chondrocytes, and chondrocyte response to hypo-osmotic stress is mediated by this channel, which involves both an extracellular Ca(2+) and intracellular Ca(2+) release. TRPV4 may also be involved in modulating the production or influence of proinflammatory molecules in response to osmotic stress.
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Affiliation(s)
- Mimi N Phan
- Duke University Medical Center, Durham, North Carolina 27710, USA
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Grässel S, Opolka A, Anders S, Straub RH, Grifka J, Luger TA, Böhm M. The melanocortin system in articular chondrocytes: melanocortin receptors, pro-opiomelanocortin, precursor proteases, and a regulatory effect of alpha-melanocyte-stimulating hormone on proinflammatory cytokines and extracellular matrix components. ACTA ACUST UNITED AC 2009; 60:3017-27. [PMID: 19790046 DOI: 10.1002/art.24846] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The pro-opiomelanocortin (POMC)-derived neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) mediates its effects via melanocortin (MC) receptors. This study was carried out to investigate the expression patterns of the MC system and the effects of alpha-MSH in human articular chondrocytes. METHODS Articular chondrocytes established from human osteoarthritic joint cartilage were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting for the expression of MC receptors, POMC, and prohormone convertases (PCs). MC-1 receptor (MC-1R) expression in articular cartilage was further studied by immunohistochemistry. Ca(2+) and cAMP assays were used to monitor alpha-MSH signaling, while studies of alpha-MSH function were performed in cultures with chondrocyte micromass pellets stimulated with alpha-MSH. Expression of cytokines and extracellular matrix (ECM) components was determined by real-time RT-PCR, Western immunoblotting, and enzyme-linked immunosorbent assays. RESULTS MC-1R expression was detected in articular chondrocytes in vitro and in articular cartilage in situ. In addition, expression of transcripts for MC-2R, MC-5R, POMC, and PCs was detected in articular chondrocytes. Stimulation with alpha-MSH increased the levels of intracellular cAMP, but not Ca(2+), in chondrocytes. Both messenger RNA and protein expression of various proinflammatory cytokines, collagens, matrix metalloproteinases (MMPs), and SOX9 was modulated by alpha-MSH. CONCLUSION Human articular chondrocytes are target cells for alpha-MSH. The effects of alpha-MSH on expression of cytokines and MMPs suggest that this neuropeptide plays a role in inflammatory and degenerative processes in cartilage. It is conceivable that inflammatory reactions can be mitigated by the induction of endogenous MCs or administration of alpha-MSH to the affected joints. The induction pattern of regulatory and structural ECM components such as collagens as well as SOX9 and anabolic and catabolic cytokines points to a function of alpha-MSH as a trophic factor in skeletal development during endochondral ossification rather than as a factor in homeostasis of permanent cartilage.
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Affiliation(s)
- Susanne Grässel
- Department of Orthopaedic Surgery and Centre for Medical Biotechnology, University of Regensburg, Regensburg, Germany.
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