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Clemmons DR, Busby WH, Garmong A, Schultz DR, Howell DS, Altman RD, Karr R. Inhibition of insulin-like growth factor binding protein 5 proteolysis in articular cartilage and joint fluid results in enhanced concentrations of insulin-like growth factor 1 and is associated with improved osteoarthritis. ARTHRITIS AND RHEUMATISM 2002; 46:694-703. [PMID: 11920405 DOI: 10.1002/art.10222] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The complement component C1s is present in dog joint fluid in an activated state. Since C1s degrades insulin-like growth factor binding protein 5 (IGFBP-5), we undertook to determine whether inhibiting C1s in joint fluid would result in an increase in the amount of intact IGFBP-5 and IGF-1 in cartilage and joint fluid, and whether C1s inhibition would be associated with a reduction in cartilage destruction during the development of osteoarthritis (OA). METHODS Twenty-two dogs were randomized to 3 treatment groups. All dogs underwent anterior cruciate ligament transection and were exercised. Dogs received 1 of 3 treatments: buffer alone (controls; n = 6); PB-145, a peptide derived from the sequence of antithrombin III (n = 9); and pentosan polysulfate (PPS; n = 7). PB-145 or saline was injected into the joint space 3 times per week for 3 weeks. PPS was injected intramuscularly weekly for 3 weeks. RESULTS Joint histology showed preservation of chondrocytes and a smooth joint surface in the animals treated with PB-145 and PPS. Mankin scoring showed statistically significant reductions in joint destruction with PB-145 and PPS treatments (P < 0.01) compared with buffer control. Mean active collagenase concentrations were decreased by these two treatments. Immunoblotting of joint fluid showed that both treatments increased concentrations of intact IGFBP-5. Direct analysis of IGFBP-3 and IGFBP-5 protease activity showed that IGFBP-5 was degraded more rapidly and that PB-145 and PPS inhibited the degradation of both proteins. Total IGF-1 concentrations in joint fluid were increased 5.6-5.8-fold by these two treatments. Analysis showed that C1s was being activated in joint fluid and that its activation was inhibited by the addition of PB-145 or PPS. CONCLUSION The findings suggest that direct inhibition of the serine protease C1s results in increased concentrations of intact IGFBP-5 and that proteolysis of IGFBP-3 is also inhibited, probably by the inhibition of some other protease. This increase in concentrations of intact IGFBP-3 and IGFBP-5 leads to an increase in IGF-1 which is associated with an improvement in joint architecture during the development of OA.
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Affiliation(s)
- David R Clemmons
- Division of Endocrinology, University of North Carolina, Chapel Hill, 27599-7170, USA.
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2
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Loeser RF, Shanker G. Autocrine stimulation by insulin-like growth factor 1 and insulin-like growth factor 2 mediates chondrocyte survival in vitro. ARTHRITIS AND RHEUMATISM 2000; 43:1552-9. [PMID: 10902760 DOI: 10.1002/1529-0131(200007)43:7<1552::aid-anr20>3.0.co;2-w] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To determine the role of autocrine stimulation by insulin-like growth factor 1 (IGF-1) and IGF-2 in mediating chondrocyte survival and to determine whether chondrocytes from older individuals are more susceptible to cell death when IGF action is blocked. METHODS Survival was assessed in human and monkey chondrocytes cultured in suspension in alginate under serum-free conditions. The role of IGFs in mediating survival was determined by treating cultures with neutralizing antibodies to IGF-1 and IGF-2, an antibody that blocks the type 1 IGF receptor, and antisense oligonucleotides to inhibit IGF-1 production. Survival was measured in chondrocyte cultures from young and old adult monkeys in the presence and absence of the IGF receptor blocking antibody and ceramide to induce cell death. RESULTS Cell survival of >90% was noted when chondrocytes were cultured for as long as 107 days in alginate in a supplemented serum-free medium. Compared with controls, survival was significantly reduced by treatment with neutralizing antibodies to IGF-1 (25% cell death), neutralizing antibodies to IGF-2 (18% cell death), antibody to the IGF receptor (45% cell death), and IGF-1 antisense oligonucleotides (28% cell death). Cell death from inhibition of the type 1 IGF receptor was associated with an increase in caspase 3 activity and with positive DNA fragmentation, consistent with apoptotic cell death. Chondrocytes from old adult monkeys were more susceptible to cell death than were those from young adult monkeys when the IGF receptor was blocked and cell death was further stimulated by ceramide. CONCLUSION Autocrine production of IGFs helps to maintain chondrocyte survival in vitro and could play a similar role in vivo. With aging, chondrocytes may become more susceptible to factors that induce cell death.
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Affiliation(s)
- R F Loeser
- Rheumatology, Rush Medical College of Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA
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3
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Ogata N, Chikazu D, Kubota N, Terauchi Y, Tobe K, Azuma Y, Ohta T, Kadowaki T, Nakamura K, Kawaguchi H. Insulin receptor substrate-1 in osteoblast is indispensable for maintaining bone turnover. J Clin Invest 2000; 105:935-43. [PMID: 10749573 PMCID: PMC377487 DOI: 10.1172/jci9017] [Citation(s) in RCA: 218] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Insulin receptor substrates (IRS-1 and -2) are essential for intracellular signaling by insulin and IGF-I, anabolic regulators of bone metabolism. Mice lacking the IRS-1 gene IRS-1(-/-) showed severe osteopenia with low bone turnover. IRS-1 was expressed in osteoblasts, but not in osteoclasts, of wild-type (WT) mice. IRS-1(-/-) osteoblasts treated with insulin or IGF-I failed to induce tyrosine phosphorylation of cellular proteins, and they showed reduced proliferation and differentiation. Osteoclastogenesis in the coculture of hemopoietic cells and osteoblasts depended on IRS-1 expression in osteoblasts and could not be rescued by IRS-1 expression in hemopoietic cells in the presence of not only IGF-I but also 1,25(OH)(2)D(3). In addition, osteoclast differentiation factor (RANKL/ODF) was not induced by these factors in IRS-1(-/-) osteoblasts. We conclude that IRS-1 deficiency in osteoblasts impairs osteoblast proliferation, differentiation, and support of osteoclastogenesis, resulting in low-turnover osteopenia. Osteoblastic IRS-1 is essential for maintaining bone turnover, because it mediates signaling by IGF-I and insulin and, we propose, also by other factors, such as 1,25(OH)(2)D(3).
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Affiliation(s)
- N Ogata
- Department of Orthopaedic Surgery, and. Department of Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, Japan
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4
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Quinn TM, Maung AA, Grodzinsky AJ, Hunziker EB, Sandy JD. Physical and biological regulation of proteoglycan turnover around chondrocytes in cartilage explants. Implications for tissue degradation and repair. Ann N Y Acad Sci 1999; 878:420-41. [PMID: 10415746 DOI: 10.1111/j.1749-6632.1999.tb07700.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The development of clinical strategies for cartilage repair and inhibition of matrix degradation may be facilitated by a better understanding of (1) the chondrocyte phenotype in the context of a damaged extracellular matrix, and (2) the roles of biochemical and biomechanical pathways by which matrix metabolism is mediated. Using methods of quantitative autoradiography, we examined the cell-length scale patterns of proteoglycan deposition and turnover in the cell-associated matrices of chondrocytes in adult bovine and calf cartilage explants. Results highlight a rapid turnover in the pericellular matrix, which may indicate spatial organization of PG metabolic pools, and specific biomechanical roles for different matrix regions. Subsequent to injurious compression of calf explants, which resulted in grossly visible tissue cracks and caused a decrease in the number of viable chondrocytes within explants, cell-mediated matrix catabolic processes appeared to increase, resulting in apparently increased rates of proteoglycan turnover around active cells. Furthermore, the influences of cell-stimulatory factors such as IL-1 beta appeared to be delayed in their effects subsequent to injurious compression, suggesting interactions between biomechanical and biochemical pathways of PG degradation. These results may provide a useful reference point in the development of in vitro models for cartilage injury and disease, and hint at possible new approaches in the development of cartilage repair strategies.
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Affiliation(s)
- T M Quinn
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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5
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Flannery CR, Little CB, Hughes CE, Caterson B. Expression and activity of articular cartilage hyaluronidases. Biochem Biophys Res Commun 1998; 251:824-9. [PMID: 9790994 DOI: 10.1006/bbrc.1998.9561] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The glycosaminoglycan hyaluronan is an important component of the extracellular matrix of articular cartilage, contributing to both the structural and functional integrity of this highly specialized tissue. Hyaluronan is known to be synthesized and turned over by the resident chondrocytes, although the mechanisms involved in hyaluronan degradation are not precisely defined. Recently, the cDNA sequences of extracellular hyaluronidases present on spermatazoa and in human serum have been reported, and we have utilized these data to investigate the expression and activity of these and/or related enzymes by articular cartilage chondrocytes. By using "gene-homology" RT-PCR techniques, three hyaluronidase isozymes were found to be expressed by chondrocytes, and hyaluronidase activity was detected in cell membrane extracts and conditioned media from chondrocyte monolayer cultures following acidification to pH 4.5 or pH 3.7. In addition, the levels of mRNA for two of the chondrocyte hyaluronidases were upregulated by IL-1 and TNF stimulation, thereby implicating cartilage-derived hyaluronidase activity as a factor contributing to cytokine-induced extracellular matrix degradation during synovial joint disease.
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Affiliation(s)
- C R Flannery
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, PreClinical Buildings, Cardiff, Wales, CF1 3US, United Kingdom.
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6
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Abstract
Several lines of evidence suggest that the insulinlike growth factors play a role in fracture healing. They promote cell proliferation and matrix synthesis by chondrocytes and osteoblasts, the two cell types largely responsible for the formation of fracture callus. Circulating levels of insulinlike growth factor I and bone mineral density decrease with increasing age, and administration of insulinlike growth factor I increases bone turnover in patients with low bone mineral density. Insulinlike growth factor I may accelerate the normal healing of intramembranous bone defects, inducing the healing of defects that otherwise would not heal. An important role of insulinlike growth factor I is to mediate many of the actions of growth hormone on the skeleton. Considerable effort has been devoted to testing the effect of growth hormone and, thereby, indirectly that of insulinlike growth factor I on fracture healing. These studies have yielded such disparate results that no general conclusions regarding the effect of growth hormone (or of growth hormone dependent insulinlike growth factor I) on fracture healing currently can be drawn. Additional studies are needed to clarify the role of the insulinlike growth factors in the fracture healing process and to determine how their anabolic actions can be enlisted in the clinical enhancement of fracture healing.
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Affiliation(s)
- S B Trippel
- Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA
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7
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Bonassar LJ, Trippel SB. Interaction of epidermal growth factor and insulin-like growth factor-I in the regulation of growth plate chondrocytes. Exp Cell Res 1997; 234:1-6. [PMID: 9223364 DOI: 10.1006/excr.1997.3574] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The action of growth factors on the cells of the epiphyseal growth plate is an important mechanism in the regulation of skeletal growth. Insulin-like growth factor-I (IGF-I) is known to play a central role in the regulation of bone growth. In contrast, the role, if any, of epidermal growth factor (EGF) is not yet clear. In these studies, we tested the hypothesis that EGF interacts with IGF-I in the regulation of growth plate chondrocyte mitotic and metabolic activities. Chondrocytes isolated from bovine radioulnar growth plates and incubated in suspension culture were analyzed for their responsiveness to EGF with respect to synthesis of DNA, proteins, and proteoglycans, responsiveness to IGF-I, and ability to specifically bind [125I]IGF-I. Treatment of growth plate chondrocytes with maximally effective concentrations (10-100 ng/ml) of EGF produced a 16-27% increase in specific binding of [125I]IGF-I. Scatchard analysis indicated that this increase in specific binding was due to an increase in the number of receptors/cell with no change in receptor affinity. EGF stimulated protein synthesis by 30-35%. Pretreatment with EGF increased the responsiveness of chondrocytes to IGF-I, resulting in 90 and 60% augmentation of IGF-I-stimulated mitotic activity and proteoglycan synthesis, respectively. Given the prominent role of IGF-I in skeletal development and the presence of EGF in the growth plate, this study suggests an important role for interactions between these growth factors in the regulation of skeletal growth.
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Affiliation(s)
- L J Bonassar
- Orthopaedic Research Laboratories, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA
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Verschure PJ, Van Marle J, Van Noorden CJ, Van den Berg WB. The contribution of quantitative confocal laser scanning microscopy in cartilage research: chondrocyte insulin-like growth factor-1 receptors in health and pathology. Microsc Res Tech 1997; 37:285-98. [PMID: 9185151 DOI: 10.1002/(sici)1097-0029(19970515)37:4<285::aid-jemt4>3.0.co;2-k] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The use of immunohistochemical detection techniques and fluorescent molecular probes in light and fluorescence microscopy allows accurate and specific analysis of a great variety of cell and tissue components. However, when staining yields only low intensity levels, serious problems may arise with discrimination of specific signals against background staining. This problem is often inherent with articular cartilage research. Application of confocal laser scanning microscopy (CLSM) can circumvent these problems. The CLSM collects images that are almost free of out-of-focus signals, which results in improved spatial resolution and discrimination as compared with conventional microscopy. Moreover, CLSM allows optical sectioning of specimens and three-dimensional reconstruction of the microscopical object. Quantitative evaluation of microscopical images is hampered by out-of-focus signals because they interfere with specific signals in the image. Interference of these nonspecific signals can be diminished by application of CLSM; in CLSM only one single point in microscopical objects is illuminated at any time and this point is then imaged into the pinhole at the entrance of the photo-detector and subsequently digitized. The present review is a discussion of the present state of the art in digital imaging with the use of CLSM in cartilage research. This discussion includes aspects such as sensitivity, specificity, spatial resolution and accuracy of quantitative analysis in microscopical immunofluorescent objects.
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Affiliation(s)
- P J Verschure
- Department of Rheumatology, University Hospital Nijmegen, The Netherlands
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9
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Verschure PJ, Van Noorden CJ, Van Marle J, Van den Berg WB. Articular cartilage destruction in experimental inflammatory arthritis: insulin-like growth factor-1 regulation of proteoglycan metabolism in chondrocytes. THE HISTOCHEMICAL JOURNAL 1996; 28:835-57. [PMID: 9015706 DOI: 10.1007/bf02331388] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Rheumatoid arthritis, a disease of unknown aetiology, is characterized by joint inflammation and, in its later stages, cartilage destruction. Inflammatory mediators may exert not only suppression of matrix synthesis but also cartilage degradation, which eventually leads to severe cartilage depletion. Systemically and locally produced growth factors and hormones regulate cartilage metabolism. Alterations in levels of these factors or in their activity can influence the pathogenesis of articular cartilage destruction in arthritic joints. The main topic of the present review is the role of the anabolic factor insulin-like growth factor-1 in the regulation of chondrocyte metabolic functions in normal and in diseased cartilage. This is the most important growth factor that balances chondrocytes proteoglycan synthesis and catabolism to maintain a functional cartilage matrix. A brief overview of how chondrocytes keep the cartilage matrix intact, and how catabolic and anabolic factors are thought to be involved in pathological cartilage destruction precedes the review of the role of this growth factor in proteoglycan metabolism in cartilage.
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Affiliation(s)
- P J Verschure
- Department of Rheumatology, University Hospital Nijmegen, The Netherlands
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10
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Verschure PJ, Van Marle J, Joosten LA, Van Den Berg WB. Histochemical analysis of insulin-like growth factor-1 binding sites in mouse normal and experimentally induced arthritic articular cartilage. THE HISTOCHEMICAL JOURNAL 1996; 28:13-23. [PMID: 8866644 DOI: 10.1007/bf02331423] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Insulin-like growth factor-1 (IGF-1) plays a key role in regulation of chondrocyte metabolism. We examined the localization of IGF-1 binding sites on chondrocytes in cartilage from normal and experimentally induced arthritic mouse knee joints. Cryostat sections from patellar cartilage were incubated either with IGF-1 receptor antibody or biotinylated IGF-1. Subsequently confocal laser scanning microscopy was applied to compare the two staining procedures qualitatively and quantitatively. This approach allowed detailed analysis of membrane-associated and intracellular staining. Using IGF-1 receptor antibody, IGF-1 receptors were found on the cell membrane of chondrocytes in the middle and deeper cartilage zones, whereas intracellular staining was highest in chondrocytes of superficial zones. After incubation with biotinylated IGF-1, distinct membrane staining was not present and fluorescence was localized homogeneously in the middle and deeper zones but not in superficial zones. In cartilage from inflamed knee joints staining with the use of IGF-1 receptor antibody did not change significantly, whereas a pronounced increase in staining was noted with biotinylated IGF-1 in chondrocytes of the middle and deeper zones of cartilage. It is concluded that the staining patterns obtained with the use of IGF-1 receptor antibody and biotinylated IGF-1 are remarkably different, suggesting that the latter also detects IGF-binding proteins. The results suggest that joint inflammation has no consistent effect on IGF-1 receptor expression but may induce a significant upregulation of IGF-binding proteins in chondrocytes of the middle and deeper zones of cartilage.
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MESH Headings
- Animals
- Antibody Specificity
- Arthritis, Experimental/metabolism
- Arthritis, Experimental/physiopathology
- Binding Sites
- Cartilage, Articular/cytology
- Cartilage, Articular/metabolism
- Cartilage, Articular/pathology
- Cartilage, Articular/ultrastructure
- Female
- Frozen Sections
- Immunohistochemistry
- Insulin-Like Growth Factor I/metabolism
- Mice
- Mice, Inbred C57BL
- Microscopy, Confocal
- Microscopy, Fluorescence
- Receptor, IGF Type 1/immunology
- Receptor, IGF Type 1/metabolism
- Up-Regulation
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Affiliation(s)
- P J Verschure
- Department of Rheumatology, University Hospital Nijmegen, Netherlands
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11
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Sah RL, Trippel SB, Grodzinsky AJ. Differential effects of serum, insulin-like growth factor-I, and fibroblast growth factor-2 on the maintenance of cartilage physical properties during long-term culture. J Orthop Res 1996; 14:44-52. [PMID: 8618165 DOI: 10.1002/jor.1100140109] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effects of fetal bovine serum, insulin-like growth factor-I, and fibroblast growth factor-2 on the regulation of the functional physical properties of adult bovine cartilage explants during an incubation period of 18-20 days was determined, and the relationship between the measured functional properties of the cartilage and the tissue composition was assessed. Cartilage disks were tested in the uniaxial radially confined configuration by the application of low amplitude oscillatory displacement and measurement of the resultant load and streaming potential. For the control cartilage terminated just after explant, the modulus was 0.39 +/- 0.28 MPa, the open circuit hydraulic permeability was 2.0 +/- 1.0 x 10(-15) m2/(Pa.sec), and the electrokinetic (streaming potential) coefficient was -2.3 +/- 0.6 mV/MPa. Incubation of cartilage in medium supplemented with serum or insulin-like growth factor-I resulted in maintenance of the modulus and electrokinetic coefficient, whereas incubation in basal medium or medium supplemented with fibroblast growth factor-2 led to a marked decrease from control values in the modulus and the amplitude of the electrokinetic coefficient. All of the culture conditions examined resulted in an increase in permeability that was not statistically significant. The variation in the electromechanical properties of all the cartilage samples tested was related to the density of tissue proteoglycan and collagen (hydroxyproline). The modulus was correlated with both the density of tissue proteoglycan (+0.014 MPa/[mg/ml]) and the density of tissue hydroxyproline (+0.008 MPa/[mg/ml]). The electrokinetic coefficient was also correlated with the density of proteoglycan (-0.080 [mV/MPa]/[mg/ml]) and the density of hydroxyproline (+0.064 [mV/MPa]/[mg/ml]). These data indicate that the regulation of chondrocyte matrix metabolism by growth factors can significantly affect the physical properties and function of cartilage.
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Affiliation(s)
- R L Sah
- Department of Bioengineering, University of California at San Diego, La Jolla, California 92093-1412, USA
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12
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Verschure PJ, van Marle J, Joosten LA, van den Berg WB. Chondrocyte IGF-1 receptor expression and responsiveness to IGF-1 stimulation in mouse articular cartilage during various phases of experimentally induced arthritis. Ann Rheum Dis 1995; 54:645-53. [PMID: 7677441 PMCID: PMC1009962 DOI: 10.1136/ard.54.8.645] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To examine the distribution of insulin like growth factor-1 (IGF-1) receptors and the biological response to IGF-1 stimulation in articular cartilage of normal mouse knee joints and arthritic joints taken at various stages of experimentally induced arthritis. METHODS In situ IGF-1 receptor expression and responsiveness to IGF-1 stimulation were examined in murine articular cartilage at different phases in two models of experimentally induced arthritis. IGF-1 receptor expression was visualised in joint sections with the use of anti-IGF-1 receptor antibodies and quantified by confocal laser scanning microscopy. Chondrocyte proteoglycan (PG) synthesis was measured by incorporation of 35S-sulphate. RESULTS In control cartilage, the majority of IGF-1 receptors were found on chondrocytes localised in the middle and deeper zones of the cartilage, whereas receptor expression in surface zone chondrocytes was very low. During culture of normal articular cartilage, IGF-1 was able to maintain chondrocyte PG synthesis at the in vivo level. Concurrently with the development of arthritis, cartilage lost its capacity to react to IGF-1, but IGF-1 stimulation recovered when the inflammatory response waned. Shortly after induction of arthritis, IGF-1 receptor expression initially declined, but it had returned to normal levels by day 1 and remained increased thereafter. CONCLUSION The distribution of IGF-1 receptor expression in the different zones of normal articular cartilage reflects IGF-1 stimulation and metabolic activity of chondrocytes in these layers. This correlation is disturbed in arthritic cartilage, suggesting inadequate or overruled signalling.
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Affiliation(s)
- P J Verschure
- Department of Rheumatology, University Hospital Nijmegen, The Netherlands
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13
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Doré S, Pelletier JP, DiBattista JA, Tardif G, Brazeau P, Martel-Pelletier J. Human osteoarthritic chondrocytes possess an increased number of insulin-like growth factor 1 binding sites but are unresponsive to its stimulation. Possible role of IGF-1-binding proteins. ARTHRITIS AND RHEUMATISM 1994; 37:253-63. [PMID: 7510486 DOI: 10.1002/art.1780370215] [Citation(s) in RCA: 155] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To characterize the insulin-like growth factor 1 (IGF-1) receptor in human osteoarthritic (OA) and normal adult chondrocytes. The biologic response of chondrocytes to IGF-1 stimulation was examined, as was the presence and synthesis of IGF binding proteins (IGFBP) in these cells. METHODS Binding studies, Northern blot, immunohistochemical analysis, and affinity cross-linking experiments were performed for characterization of the IGF receptor, and the latter method was also used for IGFBP determination. The biologic response was estimated via the incorporation of radiolabeled proline into a newly synthesized protein. RESULTS Binding experiments revealed a single class of binding sites. The mean +/- SEM affinity (Kd) of normal chondrocytes was 1.4 +/- 0.4 nM, with 26.8 +/- 5.5 x 10(3) binding sites/cell. OA chondrocytes had a lower affinity (Kd 15.4 +/- 4.7 nM) and a higher density (1,178.3 +/- 299.5 x 10(3) binding sites/cell) compared with normal cells (P < 0.004 and P < 0.001, respectively). Immunohistochemical studies with a monoclonal antibody (MAb) against the type 1 IGF receptor (alpha IR3) showed increased staining in OA cartilage compared with normal tissue. Biologic responses of chondrocytes after IGF-1 stimulation revealed that OA chondrocytes were unresponsive, whereas a 2.5-fold increase in new protein synthesis was observed in normal cells. Competition studies in normal chondrocytes revealed that both IGF-1 and IGF-2 displaced radiolabeled IGF-1 in a comparable manner; however, insulin at high concentration weakly competes. Moreover, MAb alpha IR3 effectively blocked specific binding in normal chondrocytes (77%), but not in OA chondrocytes (26%). Northern blot and covalent cross-linking analyses revealed the specific band characteristic of type 1 receptor. With the latter technique, other bands corresponding to the IGFBPs were also detected. Comparison between normal and OA chondrocytes showed increased intensity of the IGFBP bands, particularly those corresponding to the IGFBP-3 doublet. CONCLUSION It is shown that type 1 IGF receptor is expressed in human articular cartilage and that the level of binding sites is significantly increased in OA chondrocytes. Interestingly, despite the higher level of binding sites in OA cells, no response to IGF-1 stimulation was found in these cells. Our data suggest that this increase in specific binding may involve not only the type 1 IGF receptor but also IGFBP on the cell surface. The latter, by binding the IGF-1, will diminish the bioavailability of IGF-1 and thus prevent its anabolic action.
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Affiliation(s)
- S Doré
- Department of Medicine, University of Montreal, Notre Dame Hospital Research Center, Quebec, Canada
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15
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Trippel SB, Whelan MC, Klagsbrun M, Doctrow SR. Interaction of basic fibroblast growth factor with bovine growth plate chondrocytes. J Orthop Res 1992; 10:638-46. [PMID: 1323648 DOI: 10.1002/jor.1100100506] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The basic fibroblast growth factor (bFGF) family of peptides influences a wide range of cellular actions. To better understand the possible role of bFGF in the growth plate, we have characterized the interaction of this growth factor with isolated bovine growth plate chondrocytes. Basic FGF interacts with two classes of binding sites on these cells. One is consistent with high-affinity bFGF receptors and the other with low-affinity heparin-like binding sites on the chondrocyte surface. Radiolabeled bFGF binding studies revealed approximately 4 x 10(6) binding sites per cell, with a Kd of approximately 42 nM. Graded concentrations of heparin or NaCl competed with [125I]-labeled bFGF in a dose-dependent fashion, reducing [125I]-labeled bFGF binding by 75 and 97%, respectively. The data suggest the presence of a high-capacity, low-affinity class of binding sites with the properties of a heparin-like moiety. Affinity cross-linking of [125I]-labeled bFGF to chondrocytes labeled two principal species with apparent molecular masses of 135 and 160 kDa. Labeled bFGF was specifically displaced from both species by subnanomolar concentrations of unlabeled bFGF. These high-affinity, low-capacity binding sites are characteristic of classical bFGF receptors. Binding of [125I]-labeled bFGF to these sites was also influenced by heparin, consistent with coregulation of binding to the two classes of binding sites. The data suggest that bFGF participates in the regulation of skeletal growth at the growth plate and that this regulation may involve bFGF interaction with at least two distinct classes of binding sites.
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Affiliation(s)
- S B Trippel
- Department of Orthopaedics, Massachusetts General Hospital, Boston 02115
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16
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Farnum CE, Wilsman NJ. Condensation of hypertrophic chondrocytes at the chondro-osseous junction of growth plate cartilage in Yucatan swine: relationship to long bone growth. THE AMERICAN JOURNAL OF ANATOMY 1989; 186:346-58. [PMID: 2589219 DOI: 10.1002/aja.1001860404] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chondrocytes of the cartilaginous growth plate are found in a spatial gradient of cellular differentiation beginning with cellular proliferation and ending with cellular hypertrophy. Although it is recognized that both proliferation and hypertrophy contribute significantly to overall bone growth, mechanisms acting on the chondrocyte to control the timing, the rate, and the extent of hypertrophy are poorly understood. Similarly, mechanisms acting on the terminal chondrocyte to cause its death at the chondro-osseous junction have not been investigated. In this study we examine the condensation of terminal hypertrophic chondrocytes in proximal and distal radial growth plates of Yucatan swine at 4 weeks of age. The animals were raised in a controlled environment where activity and feeding patterns were synchronized to a given time in the light/dark cycle. We analyzed cellular condensation both as a function of circadian rhythms in a 24-hr time period, and as a function of overall rate of growth. The data suggest that the magnitude of circadian influences on long bone growth is significantly damped at the level of the hypertrophic chondrocyte compared to that seen by previous investigators studying circadian influences on chondrocytic proliferation. Secondly, the condensation of hypertrophic chondrocytes at the chondro-osseous junction varies inversely with rate of growth in length of the bone. At any time period, a higher percentage of terminal chondrocytes in the condensed form was found in the slower-growing of the two growth plates. We relate these findings to current hypotheses concerning controls of chondrocytic hypertrophy and possible controls over the timing of hypertrophic cell death.
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Affiliation(s)
- C E Farnum
- College of Veterinary Medicine, Cornell University, Ithaca, New York 14853
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