osteoprotegerin and Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disease afflicting millions globally. Despite the development of numerous pharmacological treatments for OA, a substantial unmet need for effective therapies persists. The RANK/RANKL signaling pathway has emerged as a promising therapeutic target for OA, owing to its pivotal role in regulating osteoclast differentiation and activity. In this comprehensive review, we aim to elucidate the relevant mechanisms of OA mediated by RANK/RANKL signaling, including bone remodeling, inflammation, cartilage degradation, osteophyte formation, and pain sensitization. Furthermore, we discuss and summarize the cutting-edge strategies targeting RANK/RANKL signaling for OA therapy, encompassing approaches such as gene-based interventions and biomaterials-aided pharmacotherapy. In addition, we highlight the prevailing challenges associated with pharmacological OA treatments and explore potential future directions, approached through a clinical-translational lens.

Topics: Bone Remodeling; Cartilage, Articular; Humans; Inflammation; Osteoarthritis; Osteoprotegerin; RANK Ligand; Signal Transduction

Cartilage and the bordering subchondral bone form a functionally active regulatory interface with a prominent role in osteoarthritis pathways. The Wnt and the OPG-RANKL-RANK signaling systems, as key mediators, interact in subchondral bone remodeling. Osteoarthritic osteoblasts polarize into two distinct phenotypes: a low secretory and an activated, pro-inflammatory and anti-resorptive subclass producing high quantities of IL-6, PGE2, and osteoprotegerin, but low levels of RANKL, thus acting as putative effectors of subchondral bone sclerosis. Wnt agonists, Wnt5a, Wisp-1 initiate excessive bone remodeling, while Wnt3a and 5a simultaneously cause loss of proteoglycans and phenotype shift in chondrocytes, with decreased expression of COL2A, aggrecan, and Sox-9. Sclerostin, a Wnt antagonist possesses a protective effect for the cartilage, while DKK-1 inhibits VEGF, suspending neoangiogenesis in the subchondral bone. Experimental conditions mimicking abnormal mechanical load, the pro-inflammatory milieu, but also a decreased OPG/RANKL ratio in the cartilage, trigger chondrocyte apoptosis and loss of the matrix via degradative matrix metalloproteinases, like MMP-13 or MMP-9. Hypoxia, an important cofactor exerts a dual role, promoting matrix synthesis via HIF-1α, a Wnt silencer, but turning on HIF-2α that enhances VEGF and MMP-13, along with aberrant collagen expression and extracellular matrix deterioration in the presence of pro-inflammatory cytokines.

Topics: Animals; Bone and Bones; Cartilage, Articular; Humans; Osteoarthritis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Wnt Proteins; Wnt Signaling Pathway

Currently published data regarding the potential role of osteoprotegerin (OPG), osteocalcin (OCN) and osteopontin (OPN) for the discrimination between rheumatoid arthritis (RA) and osteoarthritis (OA) are contradictory. To derive a more precise evaluation, a meta-analysis was performed.. Published literatures comparing plasma/serum OPG, OCN and OPN levels between RA group and OA controls were searched in PubMed, Embase and the Cochrane Library. The Newcastle-Ottawa Scale was used to assess the study quality. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by random-effect model analysis. Heterogeneity test was performed by the Q statistic and quantified using I. Nine studies including 438 RA patients and 255 OA patients were finally incorporated in the meta-analysis after examining title, type, abstracts and full text. The results showed that RA patients had higher plasma/serum OPN (pooled SMD = -2.57, 95% CI = -4.72 to -0.41) levels when compared to OA patients. No significant difference in plasma/serum OPG (pooled SMD = -0.29, 95% CI = -1.07‒0.49) and OCN (pooled SMD = -0.09, 95% CI = -0.48‒0.31) levels were found between RA patients and OA patients. Subgroup analysis indicated that plasma/serum OPG levels had no significant differences between RA patients and OA patients in Europe and Asian.. Overall, there is no significant difference in circulating OPG and OCN levels between RA patients and OA patients. However, plasma/serum OPN level is significantly higher in RA patients compared with OA patients.

Topics: Arthritis, Rheumatoid; Biomarkers; Diagnosis, Differential; Humans; Osteoarthritis; Osteocalcin; Osteopontin; Osteoprotegerin; Prognosis; Publication Bias

The aim of this study was to review the cytokine profiles in the synovial fluid (SF) of patients with temporomandibular joint disorders (TMJD). Databases were searched from 1965 till September 2015 using different combinations of the following key words: "Temporomandibular joint"; "Cytokine"; "disorder"; and "synovial fluid" and "inflammation". Titles and abstracts of studies identified using the above-described protocol were screened and checked for agreement. Full-texts of articles judged by title and abstract to be relevant were read and independently evaluated. Hand-searching of the reference lists of potentially relevant original and review articles was also performed. The pattern of the present systematic review was customized to mainly summarize the relevant data. Fifteen studies were included. In 12 studies, cytokine profile of patients with TMJD was assessed using enzyme linked immunosorbent assay; and in 2 studies, histological analysis was performed to assess the cytokine profile of patients with TMJD. Patients with TMJD presented raised levels of interleukin (IL)-6 in 8 studies, IL-1beta (1β) in 5 studies and tumor necrosis factor-alpha (TNF-α) in 5 studies. Two studies showed no significant difference in TNF-α levels in patients with and without TMJD; and IL-1β levels were comparable in patients with and without TMJD in 2 studies. Raised levels of IL-6, TNF-α, IL-1β, IL-8, and IFN-γ in the SF have been associated with inflammation in patients with TMJD. Cytokines IL-10, osteoclastogenesis inhibitory factor/osteoprotegerin (OCIF/OPG), and VEGF found in the SF of TMJs could have an anti-inflammatory effect.

Topics: Cytokines; Humans; Inflammation Mediators; Interleukin-10; Osteoarthritis; Osteoprotegerin; Synovial Fluid; Temporomandibular Joint Disorders; Vascular Endothelial Growth Factor A

Osteoarthritis (OA) is the most common joint disease worldwide. A minority of cases correspond to familial presentation characterized by early-onset forms which are genetically heterogeneous. This review brings a new point of view on the molecular basis of OA by focusing on gene mutations causing early-onset OA (EO-OA). Recently, thanks to whole-exome sequencing, a gain-of-function mutation in the TNFRSF11B gene was identified in two distant family members with EO-OA, opening new therapeutic perspectives for OA. Indeed, unraveling the molecular basis of rare Mendelian OA forms will improve our understanding of molecular processes involved in OA pathogenesis and will contribute to better patient diagnosis, management, and therapy.

Topics: Age of Onset; Animals; Cartilage; Collagen; Genetic Predisposition to Disease; Humans; Mutation; Osteoarthritis; Osteoprotegerin

Topics: ADAM Proteins; ADAMTS5 Protein; Animals; Basic Helix-Loop-Helix Transcription Factors; beta Catenin; Core Binding Factor Alpha 1 Subunit; HMGB2 Protein; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Matrix Metalloproteinase 13; Mice; Molecular Targeted Therapy; NF-kappa B; Osteoarthritis; Osteoprotegerin; Sulfatases

Bone remodelling is tightly regulated by a molecular triad composed of OPG/RANK/RANKL. The receptor activator of NF-kappaB ligand (RANKL) (localized on osteoblasts) enhances osteoclastogenesis via interaction with its receptor RANK (localized on osteoclasts), whereas osteoprotegerin (OPG) (produced by osteoblasts) inhibits this osteoclastogenesis by binding to RANKL. The equilibrium between OPG and RANKL plays a crucial role in the pathophysiology of bone. Although some studies have shown the efficacy of OPG as a therapeutic agent against bone resorption, its bioavailability and mechanism of action after binding to RANKL have only recently been studied. A mechanistic investigation based on what becomes of OPG after binding to cells expressing membranous RANKL demonstrated an internalization process of OPG through the clathrin pathway prior to proteasomal and/or lysosomal degradation. Interestingly, the OPG internalization process reduced the half-life of RANKL. Recent evidence has shown that subchondral bone alterations in osteoarthritis (OA) are intimately involved in cartilage degradation, and that OPG/RANKL may be implicated. Data show that human OA subchondral bone osteoblasts have abnormal OPG and RANKL levels and consequently an altered OPG and RANKL ratio. Further data also reveal the involvement of some osteotropic factors in these altered levels and that some of these factors generally target RANKL with a differential modulation of the RANKL isoforms. Altogether, data suggest that this system could be targeted as a new strategy for the treatment of OA.

Topics: Animals; Humans; Osteoarthritis; Osteoprotegerin; Protein Binding; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Substrate Specificity

Advances in genomics and proteomics have revolutionised the drug discovery process and target validation. Identification of novel therapeutic targets for chronic skeletal diseases is an extremely challenging process based on the difficulty of obtaining high-quality human diseased versus normal tissue samples. The quality of tissue and genomic information obtained from the sample is critical to identifying disease-related genes. Using a genomics-based approach, novel genes or genes with similar homology to existing genes can be identified from cDNA libraries generated from normal versus diseased tissue. High-quality cDNA libraries are prepared from uncontaminated homogeneous cell populations harvested from tissue sections of interest. Localised gene expression analysis and confirmation are obtained through in situ hybridisation or immunohistochemical studies. Cells overexpressing the recombinant protein are subsequently designed for primary cell-based high-throughput assays that are capable of screening large compound banks for potential hits. Afterwards, secondary functional assays are used to test promising compounds. The same overexpressing cells are used in the secondary assay to test protein activity and functionality as well as screen for small-molecule agonists or antagonists. Once a hit is generated, a structure-activity relationship of the compound is optimised for better oral bioavailability and pharmacokinetics allowing the compound to progress into development. Parallel efforts from proteomics, as well as genetics/transgenics, bioinformatics and combinatorial chemistry, and improvements in high-throughput automation technologies, allow the drug discovery process to meet the demands of the medicinal market. This review discusses and illustrates how different approaches are incorporated into the discovery and validation of novel targets and, consequently, the development of potentially therapeutic agents in the areas of osteoporosis and osteoarthritis. While current treatments exist in the form of hormone replacement therapy, antiresorptive and anabolic agents for osteoporosis, there are no disease-modifying therapies for the treatment of the most common human joint disease, osteoarthritis. A massive market potential for improved options with better safety and efficacy still remains. Therefore, the application of genomics and proteomics for both diseases should provide much needed novel therapeutic approaches to treating these major world health

Topics: Animals; Bone Diseases; Carrier Proteins; Caspases; Cathepsin K; Cathepsins; Cysteine Proteinase Inhibitors; DNA-Binding Proteins; Drug Design; Drug Evaluation, Preclinical; Early Growth Response Protein 1; Genomics; Glycoproteins; Humans; Immediate-Early Proteins; Membrane Glycoproteins; Mice; Mice, Knockout; Mice, Transgenic; Molecular Structure; Osteoarthritis; Osteoporosis; Osteoprotegerin; Proteomics; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; src-Family Kinases; Transcription Factors; Two-Hybrid System Techniques

Wnt signaling, a major regulator of bone formation and homeostasis, might be involved in the bone loss of osteoporotic patients and the consequent impaired response to fracture. Therefore we analyzed Wnt-related, osteogenic, and adipogenic genes in bone tissue of elderly postmenopausal women undergoing hip replacement for either femoral fracture or osteoarthritis. Bone specimens derived from the intertrochanteric region of the femurs of 25 women with fracture (F) and 29 with osteoarthritis without fracture (OA) were analyzed. Specific miRNAs were analyzed in bone and in matched blood samples. RUNX2, BGP, and OPG showed lower expression in F than in OA samples, while OSX, OPN, BSP, and RANKL were not different. Inhibitory genes of Wnt pathway were lower in F versus OA.

Topics: Aged; Aged, 80 and over; beta Catenin; Core Binding Factor Alpha 1 Subunit; Female; Femoral Fractures; Humans; MicroRNAs; Osteoarthritis; Osteoprotegerin; Postmenopause; RANK Ligand; Wnt Signaling Pathway

Aseptic bone loss adjacent to orthopedic joint implants is a common cause of joint implant failure in humans. This study investigates the expression of key regulators of osteoclast formation, receptor activator NFkappaB (RANK), Receptor activator of NFkappaB ligand (RANKL) and osteoprotegerin (OPG), in the peri-implant tissues of patients with osteolysis compared with levels in synovial tissues from osteoarthritic and healthy subjects. Immunohistochemical studies demonstrated that significantly higher levels of RANKL protein (p<0.05) were found in the peri-implant tissues of patients with implant failure than in similar tissues from osteoarthritic and healthy subjects. In contrast, OPG protein levels were similar in all tissues. RANKL, expressed as mRNA and protein, was predominantly associated with cells containing wear particles. Dual labeling studies showed that the cells expressing RANKL protein were macrophages. In situ hybridization studies confirmed that mRNA encoding for these proteins is also expressed by cells in the peri-implant tissues. In addition, RANK mRNA was expressed in cells that contained wear particles. These findings show that abnormally high levels of RANKL are expressed in peri-implant tissues of patients with prosthetic loosening and that these abnormal levels of RANKL may significantly contribute to aseptic implant loosening.

Topics: Adult; Aged; Aged, 80 and over; Carrier Proteins; Female; Foreign-Body Reaction; Glycoproteins; Humans; Male; Membrane Glycoproteins; Middle Aged; NF-kappa B; Osteoarthritis; Osteoclasts; Osteolysis; Osteonecrosis; Osteoprotegerin; Prosthesis Failure; Prosthesis-Related Infections; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor

In chronic arthropathies, there are several mechanisms of joint destruction. In recent years, studies have reported the implication of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in the process of activation and differentiation of osteoclasts, a key cell in the development of bone erosion. The RANKL/OPG ratio is increased in the serum of patients with malignant diseases and lytic bone disease, as well as rheumatoid arthritis (RA). The objective of this study was to measure and compare the concentrations of OPG and RANKL in the synovial fluid (SF) of patients with rheumatoid arthritis, spondyloarthritis (SpA) and osteoarthritis (OA).. This was an observational and cross-sectional study with 83 patients, 33 with RA, 32 with SpA and 18 with OA, followed up regularly in the outpatient clinics of the Rheumatology Department of the Clinics Hospital of the Ribeirão Preto Medical School-USP. All patients were assessed for indications for arthrocentesis by the attending physicians at the time of SF collection and were evaluated for demographic variables and medication use. Disease activity was assessed in individuals with RA and SpA. The quantification of SF OPG and RANKL levels was performed by ELISA, and the correlations of the results with clinical, laboratory and radiological parameters were assessed.. We found no statistically significant difference in the RANKL and OPG levels among the groups. Patients with RA showed a positive correlation between the SF cell count and RANKL level (r = 0.59; p < 0.05) and the RANKL/OPG ratio (r = 0.55; p < 0.05). Patients with OA showed a strong correlation between C-reactive protein (CRP) and the RANKL/OPG ratio (r = 0.82; p < 0.05). There was no correlation between the OPG and RANKL levels and markers of inflammatory activity or the disease activity index in patients with RA or SpA.. Within this patient cohort, the RANKL/OPG ratio was correlated with the SF cell count in patients with RA and with serum CRP in patients with OA, which may suggest a relationship with active inflammation and more destructive joint disease.

Topics: Arthritis, Rheumatoid; Cross-Sectional Studies; Humans; Ligands; NF-kappa B; Osteoarthritis; Osteoprotegerin; Spondylarthritis

Ganoderma mushrooms have been used to treat rheumatoid arthritis (RA) in East Asia. Whether Ganoderic acid A (GAA), the natural product extracted from Ganoderma, could be utilized to alleviate osteoarthritis (OA) is investigated in this study. Destabilization of the medial meniscus (DMM) model was constructed to reveal the in vivo effect of GAA. We found that GAA could significantly alleviate the pathology of DMM, as confirmed by the diminished maximum histologic scores. On the contrary, GAA could down-regulate the relative expression of osteoprotegerin (OPG) and up-regulate the relative expression of nuclear factor kappa-B ligand (RANKL) in DMM cartilage and human articular chondrocytes (HC-A) cells with diminished matrix metallopeptidase 13 (MMP-13) secretion in the synovial fluid. It was further demonstrated that the serum concentration of OPG was correlated with the severity of osteoarthritis. All these data reveal that GAA could improve OA by regulating the RANKL/OPG ratio to inhibit the secretion of MMP-13.

Topics: Chondrocytes; Heptanoic Acids; Humans; Lanosterol; Matrix Metalloproteinase 13; Osteoarthritis; Osteoprotegerin; RANK Ligand

OA is a complex genetic disease with different risk factors contributing to its development. One of the genes, TNFRSF11B, previously identified with gain-of-function mutation in a family with early-onset OA with chondrocalcinosis, is among the highest upregulated genes in lesioned OA cartilage (RAAK-study). Here, we determined the role of TNFRSF11B overexpression in development of OA.. Human primary articular chondrocytes (9 donors RAAK study) were transduced using lentiviral particles with or without TNFRSF11B. Cells were cultured for 1 week in a 3 D in-vitro chondrogenic model. TNFRSF11B overexpression was confirmed by RT-qPCR, immunohistochemistry and ELISA. Effects of TNFRSF11B overexpression on cartilage matrix deposition, matrix mineralization, and genes highly correlated to TNFRSF11B in RNA-sequencing dataset (r >0.75) were determined by RT-qPCR. Additionally, glycosaminoglycans and collagen deposition were visualized with Alcian blue staining and immunohistochemistry (COL1 and COL2).. Overexpression of TNFRSF11B resulted in strong upregulation of MMP13, COL2A1 and COL1A1. Likewise, mineralization and osteoblast characteristic markers RUNX2, ASPN and OGN showed a consistent increase. Among 30 genes highly correlated to TNFRSF11B, expression of only eight changed significantly, with BMP6 showing the highest increase (9-fold) while expression of RANK and RANKL remained unchanged indicating previously unknown downstream pathways of TNFRSF11B in cartilage.. Results of our 3D in vitro chondrogenesis model indicate that upregulation of TNFRSF11B in lesioned OA cartilage may act as a direct driving factor for chondrocyte to osteoblast transition observed in OA pathophysiology. This transition does not appear to act via the OPG/RANK/RANKL triad common in bone remodeling.

Topics: Aged; Cartilage; Cartilage Diseases; Cells, Cultured; Chondrocytes; Enzyme-Linked Immunosorbent Assay; Female; Humans; Osteoarthritis; Osteoprotegerin; Polymerase Chain Reaction

Metastasis Associated Lung Adenocarcinoma Transcript-1 (MALAT1) is implicated in regulating the inflammatory response and in the pathology of several chronic inflammatory diseases, including osteoarthritis (OA). The purpose of this study was to examine the relationship between OA subchondral bone expression of MALAT1 with parameters of joint health and biomarkers of joint inflammation, and to determine its functional role in human OA osteoblasts. Subchondral bone and blood were collected from hip and knee OA patients (

Topics: Aged; Bone and Bones; Calcification, Physiologic; Cytokines; Dinoprostone; Female; Gene Expression Regulation; Humans; Male; Middle Aged; Osteoarthritis; Osteoblasts; Osteoprotegerin; RNA, Long Noncoding; Severity of Illness Index; Transcriptome

Osteoarthritis (OA) is a degenerative disease characterized by injury of all joint tissues. Our previous study showed that in experimental osteoporosis, chiropractic manipulation (CM) exerts protective effects on bone. We here assessed whether CM might ameliorate OA by improving subchondral bone sclerosis, cartilage integrity and synovitis. Male New-Zealand rabbits underwent knee surgery to induce OA by anterior cruciate ligament injury. CM was performed using the chiropractic instrument ActivatorV 3 times/week for 8 weeks as follows: force 2 setting was applied to the tibial tubercle of the rabbit right hind limb (TM-OA), whereas the corresponding left hind limb received a false manipulation (FM-OA) consisting of ActivatorV firing in the air and slightly touching the tibial tubercle. After sacrifice, subchondral bone integrity was assessed in the tibiae by microCT and histology. Cartilage damage and synovitis were estimated by Mankin's and Krenn's scores, respectively, and histological techniques. Bone mineral density and content in both cortical and trabecular compartments of subchondral bone decreased in OA rabbits compared to controls, but partially reversed in the TM-OA group. Trabecular bone parameters in the latter group also showed a significant improvement compared to FM-OA group. Moreover RANKL, OPG, ALP and TRAP protein expression in subchondral bone significantly decreased in TM-OA rabbits with respect to FM-OA group. CM was associated with lower Mankin's and Krenn's scores and macrophage infiltrate together with a decreased protein expression of pro-inflammatory, fibrotic and angiogenic factors, in TM-OA rabbits with respect to FM-OA. Our results suggest that CM may mitigate OA progression by improving subchondral bone as well as cartilage and synovial membrane status.

Topics: Animals; Anterior Cruciate Ligament Injuries; Bone Density; Disease Models, Animal; Male; Manipulation, Chiropractic; Osteoarthritis; Osteoprotegerin; Rabbits; RANK Ligand; Tibia; Treatment Outcome; X-Ray Microtomography

Osteoarthritis (OA) is a chronic joint disease characterized by articular cartilage degeneration and secondary osteogenesis. It has been previously demonstrated that the CCAL1 locus is the gene encoding tumor necrosis factor receptor superfamily member 11B (TNFRSF11B). The purpose of this study was to demonstrate the role of CCAL1 in OA progression and to elucidate its molecular mechanisms. We report that CCAL1 is highly expressed in the cartilage of OA patients and its expression level is positively correlated with the severity of OA. We found that CCAL1 causes a switch to the fibrosis-prone phenotype of Human Chondrocyte-Osteoarthritis (HC-OA) cells. In addition, CCAL1 enhances cell viability and promotes the proliferation of HC-OA cells. Finally, the detection of proteins associated with the NF-κB/AMPK signaling pathway by western blot suggested that CCAL1 exerts its role on HC-OA cells by activating the NF-κB signaling pathway and inhibiting the AMPK signaling pathway, which was verified through the addition of NF-κB inhibitor caffeic acid phenethyl ester (CAPE) and AMPK activator 5-aminoimidazole-4-carboxamide riboside (AICAR). In summary, we report that CCAL1 may promote OA through the NF-κB and AMPK signaling pathways.

Topics: AMP-Activated Protein Kinases; Cells, Cultured; Humans; Middle Aged; NF-kappa B; Osteoarthritis; Osteoprotegerin; Signal Transduction

Osteoprotegerin (OPG) is one of the protective factors of bony tissue. However, the function of OPG in cartilage tissues remains elusive. The aim of this study is to explore the function of OPG in the postnatal maintenance and the occurring of osteoarthritis (OA) of temporomandibular joint (TMJ) in the rodent models. We found that OPG expressed in the hypertrophic layer of the condylar cartilage and upregulated in the hyperocclusion-induced-TMJ-trauma rat. In the absence of OPG, the cartilage degradation occurred prior to that in WT mice, and the 3-month-old OPG-Knockout (OPG-KO) condyle showed decreased chondrocyte proliferation and increased chondrocyte apoptosis, whereas the number of chondroclasts was comparable to WT condyle. The isolated chondrocytes from the OPG-KO mice also showed impaired survival and promoted chondrogenic differentiation. Furthermore, the hyperocclusion model deteriorated TMJ degradation in the OPG-KO mice. OPG plays a protective role in the condylar chondrocytes' survival, and it is required for the postnatal maintenance of TMJ.

Topics: Animals; Cartilage, Articular; Cell Differentiation; Chondrocytes; Disease Models, Animal; Mandibular Condyle; Mice, Inbred C57BL; Mice, Knockout; Osteoarthritis; Osteoprotegerin; Temporomandibular Joint

OA subchondral bone is a key target for therapy development. Osteocytes, the most abundant bone cell, critically regulate bone formation and resorption. Their progenitors, mesenchymal stem cells (MSCs), display altered behaviour in osteoarthritic subchondral bone. This study investigated the relationships between native osteocytes and native MSCs in osteoarthritic femoral heads.. To avoid culture manipulations, a bone treatment procedure was developed to simultaneously obtain pure osteocyte-enriched fragments and matched native CD45-CD271+ MSCs. Gene expression in osteocytes and MSCs was compared between healthy and OA bone and selected molecules were examined by immunohistochemistry in relation to OA tissue pathology. Cell sorting and standard trilineage differentiation assays were employed to test OA MSC functionality.. Native osteocyte enrichment was confirmed histologically and by higher-level osteocyte maturation transcripts expression, compared with purified MSCs. Compared with healthy bone, native OA osteocytes expressed 9- and 4-fold more early/embedding osteocyte molecules E11 and MMP14, and 6-fold more osteoprotegerin (P<0.01). CD271+ MSCs accumulated in the regions of bone sclerosis (9-fold, P<0.0001) in close juxtaposition to trabeculae densely populated with morphologically immature E11-positive osteocytes (medians of 76% vs 15% in non-sclerotic areas, P<0.0001), and osteoblasts. Gene expression of OA MSCs indicated their bone formation bias, with retained multipotentiality following culture-expansion.. In human late-stage OA, osteogenically-committed MSCs and adjacent immature osteocytes exhibit a marked accumulation in sclerotic areas. This hitherto unappreciated MSC-early osteocyte axis could be key to understanding bone abnormalities in OA and represents a potential target for novel therapy development in early disease.

Topics: Cell Differentiation; Cells, Cultured; Femur Head; Humans; Mesenchymal Stem Cells; Nerve Tissue Proteins; Osteoarthritis; Osteoblasts; Osteocytes; Osteogenesis; Osteoprotegerin; Receptors, Nerve Growth Factor; Sclerosis

To investigate the effect of chitosan oligosaccharides (COS) against osteoarthritis (OA) and preliminarily discuss the osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL) and RANK expression in a rat OA model.. Thirty-six 6-week-old Male SD rats were randomly divided into three groups: sham-operated group(CON), OA-induction group(OA), COS intervention group(n=12/group). At 4 weeks after the operation, COS (50 ul) intervention weekily for consecutive 5 weeks. The OA and CON groups received an injection of 50 ul physiological saline. At death, 11 weeks following surgery, cartilage was harvested and total RNA and protein were extracted. Both the morphological changes of the cartilage were observed and harvested the total RNA and protein. Meanwhile, the expression of OPG, RANKL and RANK in cartilage were determined.. The expression of OPG and RANKL were both enhanced in the cartilage of the OA model. Compared with the OA group, COS treatment improved the cartilage damage (both extent and grade). Furthermore, the COS group showed highly OPG and lower RANKL. Simultaneously, COS treatment upregulated the ratio of OPG/RANKL and downregulated the RANKL/RANK.. Chitosan oligosaccharides may be used as a unique biological agent to prevent and treat osteoarthritis, and this effect is associated with modulation of the expression of osteoprotegerin and receptor activator of NF-κB ligand.

Topics: Animals; Cartilage, Articular; Chitosan; Disease Models, Animal; Gene Expression Regulation; Male; Oligosaccharides; Osteoarthritis; Osteoprotegerin; RANK Ligand; Rats; Rats, Sprague-Dawley

Secondary osteoporosis is a frequent complication of rheumatoid arthritis (RA) and the result of an imbalance of catabolic and anabolic mechanisms of bone metabolism. The effects of serial low-dose radon and hyperthermia (LDRnHT) exposure in a therapeutic adit (12 applications in 3 weeks) on the serum levels of the cytokines osteoprotegerin (OPG), receptor activator of NF kappa-B ligand (RANKL), tumor necrosis factor-α (TNF-α), and also on the RANKL/OPG ratio were investigated in 25 RA patients and an age-matched control of 24 patients with osteoarthritis (OA). Cytokine measurements were performed at baseline and after completion of LDRnHT. Anti-CCP antibodies (ACPA) were measured in RA patients in parallel. Medication in both groups was limited to non-steroidal anti-inflammatory drugs, and low-dose prednisolone (16 of 24 RA patients) as needed. RA and OA patients showed a significant decrease of TNF-α levels (p < 0.001). Both groups showed significantly decreased levels of RANKL (RA: p < 0.001, OA: p < 0.01). Only the RA patients presented a significant increase of OPG (p < 0.01) and decrease of the RANKL/OPG ratio (p < 0.01), and the ACPA levels (p < 0.001). LDRnHT results in a reduction of osteocatabolic and an increase of osteoanabolic cytokines, which represents the molecular basis for inhibiting osteoclastic activity in secondary osteoporosis and explains in part the effect of LDRnHT this physical therapy modality in a key inflammatory disease. Although reduced ACPA levels were observed under the therapy and although this could potentially contribute to an osteoprotective effect, in this case, it is rather uncertain as the reduction was only minor in magnitude.

Topics: Aged; Arthritis, Rheumatoid; Female; Humans; Hyperthermia, Induced; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Radon; RANK Ligand; Treatment Outcome; Tumor Necrosis Factor-alpha

Osteoarthritis (OA) was a degenerative joint disease characterized by articular cartilage degradation and extensive remodeling of the subchondral bone. Multiple lines of evidence indicated that Osteoprotegerin (OPG), a member of TNF receptor superfamily that was expressed in the chondrocytes of articular cartilage and adjacent locations in the physiological setting, was involved in maintaining integrity of articular cartilage. OPG could prevent subchondral bone from resorption, and also protect cartilage from degradation. In this study, we used Osteoprotegerin-knockout mice (Opg-KO mice) to find out the role of OPG in articular cartilage. We examined articular cartilage in the femoral head of Opg-KO mice began in early adulthood using modern molecular and imaging methods. We found cartilage changes starting from adulthood and progressively with age, reminiscent of pathological changes in OA. Deficiency of OPG caused thinned articular cartilage and extensive remodeling of the subchondral bone in femoral head in comparison with wild-type mice (WT mice). Also, the articular cartilage of femoral head expressed significantly less of Aggrecan, Col-II and Col-X, but more Col-I and Matrix Metalloproteinases-13 (Mmp-13) than WT mice both at gene and protein level. Moreover, increased chondrocyte apoptosis and decreased chondrocyte proliferation were observed in femoral head of Opg-KO mice compared to WT mice. These data suggested that OPG played an important role in maintaining the homeostasis of articular cartilage of femoral head.

Topics: Animals; Cartilage, Articular; Cell Count; Cell Survival; Chondrocytes; Disease Models, Animal; Extracellular Matrix; Femur Head; Mice; Mice, Knockout; Osteoarthritis; Osteoclasts; Osteogenesis; Osteoprotegerin; X-Ray Microtomography

To identify pathogenic mutations that reveal underlying biological mechanisms driving osteoarthritis (OA).. Exome sequencing was applied to two distant family members with dominantly inherited early onset primary OA at multiple joint sites with chondrocalcinosis (familial generalised osteoarthritis, FOA). Confirmation of mutations occurred by genotyping and linkage analyses across the extended family. The functional effect of the mutation was investigated by means of a cell-based assay. To explore generalisability, mRNA expression analysis of the relevant genes in the discovered pathway was explored in preserved and osteoarthritic articular cartilage of independent patients undergoing joint replacement surgery.. We identified a heterozygous, probably damaging, read-through mutation (c.1205A=>T; p.Stop402Leu) in TNFRSF11B encoding osteoprotegerin that is likely causal to the OA phenotype in the extended family. In a bone resorption assay, the mutant form of osteoprotegerin showed enhanced capacity to inhibit osteoclastogenesis and bone resorption. Expression analyses in preserved and affected articular cartilage of independent OA patients showed that upregulation of TNFRSF11B is a general phenomenon in the pathophysiological process.. Albeit that the role of the molecular pathway of osteoprotegerin has been studied in OA, we are the first to demonstrate that enhanced osteoprotegerin function could be a directly underlying cause. We advocate that agents counteracting the function of osteoprotegerin could comply with new therapeutic interventions of OA.

Topics: Aged; Aged, 80 and over; Bone Resorption; Cell Differentiation; Chondrocalcinosis; Exome; Female; Genotype; Heterozygote; Humans; Male; Middle Aged; Mutation; Osteoarthritis; Osteoclasts; Osteoprotegerin; Pedigree; Phenotype

Osteogenic behaviour of osteoblasts from trabecular, cortical and subchondral bone were examined to determine any bone type-selective differences in samples from both osteoarthritic (OA) and osteoporotic (OP) patients. Cell growth, differentiation; alkaline phosphatase (TNAP) mRNA and activity, Runt-related transcription factor-2 (RUNX2), SP7-transcription factor (SP7), bone sialoprotein-II (BSP-II), osteocalcin/bone gamma-carboxyglutamate (BGLAP), osteoprotegerin (OPG, TNFRSF11B), receptor activator of nuclear factor-κβ ligand (RANKL, TNFSF11) mRNA levels and proangiogenic vascular endothelial growth factor-A (VEGF-A) mRNA and protein release were assessed in osteoblasts from paired humeral head samples from age-matched, human OA/OP (n = 5/4) patients. Initial outgrowth and increase in cell number were significantly faster (p < 0.01) in subchondral and cortical than trabecular osteoblasts, in OA and OP, and this bone type-related differences were conserved despite consistently faster growth in OA. RUNX2/SP7 levels and TNAP mRNA and protein activity were, however, greater in trabecular than subchondral and cortical osteoblasts in OA and OP. BSP-II levels were significantly greater in trabecular and lowest in cortical osteoblasts in both OA and OP. In contrast, BGLAP levels showed divergent bone type-selective behaviour; highest in osteoblasts from subchondral origins in OA and trabecular origins in OP. We found virtually identical bone type-related differences, however, in TNFRSF11B:TNFSF11 in OA and OP, consistent with greater potential for paracrine effects on osteoclasts in trabecular osteoblasts. Subchondral osteoblasts (OA) exhibited highest VEGF-A mRNA levels and release. Our data indicate that human osteoblasts in trabecular, subchondral and cortical bone have inherent, programmed diversity, with specific bone type-related differences in growth, differentiation and pro-angiogenic potential in vitro.

Topics: Aged; Aged, 80 and over; Alkaline Phosphatase; Bone and Bones; Cell Differentiation; Cell Proliferation; Cells, Cultured; Core Binding Factor Alpha 1 Subunit; Female; Gene Expression Profiling; Humans; Integrin-Binding Sialoprotein; Organ Specificity; Osteoarthritis; Osteoblasts; Osteocalcin; Osteoporosis; Osteoprotegerin; Reverse Transcriptase Polymerase Chain Reaction; Sp7 Transcription Factor; Tissue Culture Techniques; Transcription Factors; Vascular Endothelial Growth Factor A

Increased subchondral bone turnover may contribute to pain in osteoarthritis (OA).. To investigate the analgesic potential of a modified version of osteoprotegerin (osteoprotegerin-Fc (OPG-Fc)) in the monosodium iodoacetate (MIA) model of OA pain.. Male Sprague Dawley rats (140-260 g) were treated with either OPG-Fc (3 mg/kg, subcutaneously) or vehicle (phosphate-buffered saline) between days 1 and 27 (pre-emptive treatment) or days 21 and 27 (therapeutic treatment) after an intra-articular injection of MIA (1 mg/50 µl) or saline. A separate cohort of rats received the bisphosphonate zoledronate (100 µg/kg, subcutaneously) between days 1 and 25 post-MIA injection. Incapacitance testing and von Frey (1-15 g) hind paw withdrawal thresholds were used to assess pain behaviour. At the end of the study, rats were killed and the knee joints and spinal cord removed for analysis. Immunohistochemical studies using Iba-1 and GFAP quantified levels of activation of spinal microglia and astrocytes, respectively. Joint sections were stained with haematoxylin and eosin or Safranin-O fast green and scored for matrix proteoglycan and overall joint morphology. The numbers of tartrate-resistant acid phosphatase-positive osteoclasts were quantified. N=10 rats/group.. Pre-emptive treatment with OPG-Fc significantly attenuated the development of MIA-induced changes in weightbearing, but not allodynia. OPG-Fc decreased osteoclast number, inhibited the formation of osteophytes and improved structural pathology within the joint similarly to the decrease seen after pretreatment with the bisphosphonate, zoledronate. Therapeutic treatment with OPG-Fc decreased pain behaviour, but did not improve pathology in rats with established joint damage.. Our data suggest that early targeting of osteoclasts may reduce pain associated with OA.

Topics: Animals; Arthralgia; Behavior, Animal; Bone Density Conservation Agents; Bone Remodeling; Diphosphonates; Disease Models, Animal; Drug Design; Enzyme Inhibitors; Imidazoles; Iodoacetic Acid; Joints; Male; Nociceptors; Osteoarthritis; Osteoclasts; Osteophyte; Osteoprotegerin; Rats; Rats, Sprague-Dawley; Spinal Cord; Zoledronic Acid

Dietary loading has been reported to have an effect on temporomandibular joint (TMJ) remodeling via periodontal-muscular reflex. We therefore examined whether reducing dietary loading decreased TMJ degradation induced by the unilateral anterior crossbite prosthesis as we recently reported.. Forty 6-week-old female C57BL/6J mice were randomly divided into two experimental and two control groups. One experimental and one control group received small-size diet and the other two groups received large-size diet. Unilateral anterior crossbite prosthesis was created in the two experimental groups. The TMJ samples were collected 3 weeks after experimental operation. Histological changes in condylar cartilage and subchondral bone were assessed by Hematoxylin & Eosin, toluidine blue, Safranin O and tartrate-resistant acid phosphatase staining. Real-time polymerase chain reaction (PCR) and/or immunohistochemistry were performed to evaluate the expression levels of Collagen II, Aggrecan, a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5) and RANKL/RANK/OPG in TMJ condylar cartilage and/or subchondral bone.. Thinner and degraded cartilage, reduced cartilage cellular density, decreased expression levels of Collagen II and Aggrecan, loss of subchondral bone and enhanced osteoclast activity were observed in TMJs of both experimental groups. However, the cartilage degradation phenotype was less severe and cartilage ADAMTS-5 mRNA was lower while OPG/RANKL ratio in cartilage and subchondral bone was higher in the small-size than large-size diet experimental group. No differences of histomorphology and the tested molecules were found between the two control groups.. The current findings suggest that a lower level of functional loading by providing small-size diet could reduce TMJ degradation induced by the biomechanical stimulation from abnormal occlusion.

Topics: ADAM Proteins; ADAMTS5 Protein; Aggrecans; Animals; Body Weight; Cartilage, Articular; Collagen Type II; Dental Prosthesis; Diet; Disease Progression; Female; Malocclusion; Mandibular Condyle; Mastication; Mice; Mice, Inbred C57BL; Osteoarthritis; Osteoclasts; Osteoprotegerin; RANK Ligand; Temporomandibular Joint Disorders

Osteoarthritis (OA) is a major health problem in the increasingly elderly population. Therefore, it is crucial to prevent and treat OA at an early stage. The present study investigated whether pamidronate disodium (PAM), a bone-loss inhibitor, can significantly prevent or reverse the progression of early anterior cruciate ligament transection (ACLT)-induced OA. Whether therapeutic intervention is associated with regulation of the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), metalloproteinase-9 (MMP-9) or Toll-like receptor-4 (TLR-4) in cartilage and/or subchondral bone was also investigated.. 60 New Zealand rabbits were randomized into four groups: Sham-operated (n = 20); ACLT (n = 20); short-term treatment with PAM (PAM-S, n = 10) and long-term treatment with PAM (PAM-L, n = 10). For cartilage and subchondral bone testing, rabbits from Sham and ACLT groups were harvested at 2, 4, 6, and 14 weeks. Rabbits were given PAM from the 4th week after ACLT operation in PAM-S and PAM-L group, and were harvested at 6 and 14 weeks, respectively. Trabecular characteristics and cartilage changes were detected using Micro-CT, safranin O and rapid green staining, respectively. Immunohistochemical staining for OPG and RANKL were also performed. OPG, RANKL, MMP-9 and TLR-4 expression was evaluated by western blot analysis.. Micro-CT and histology analyses indicated that PAM treatment for 2 or 10 weeks could completely prevent or reverse osteoarthritic subchondral bone loss and cartilage surface erosion. Immunohistochemistry and western blot analysis indicated that expression of OPG and RANKL increased, although RANKL expression increased more significantly than that of OPG. Therefore the ratio of OPG to RANKL was lower in the ACLT group. However, the ratio of OPG to RANKL in the PAM group was significantly higher than that in the ACLT group. Additionally, expression of MMP-9 and TLR-4 were upregulated in the ACLT group and downregulated in the PAM treated groups.. PAM can significantly inhibit and even reverse early osteoarthritic subchondral bone loss, thus alleviating the process of cartilaginous degeneration. The mechanisms involved may be associated with the upregulation of OPG expression, and downregulation of RANKL, MMP-9 and TLR-4 expression.

Topics: Animals; Bone Density Conservation Agents; Cartilage, Articular; Diphosphonates; Gene Expression Regulation; Osteoarthritis; Osteoprotegerin; Pamidronate; Rabbits; Random Allocation; RANK Ligand; Treatment Outcome

Osteoarthritis (OA) is the most common rheumatic pathology and is characterized primarily by articular cartilage degradation. Despite its high prevalence, there is no effective therapy to slow disease progression or regenerate the damaged tissue. Therefore, new diagnostic and monitoring tests for OA are urgently needed, which would also promote the development of alternative therapeutic strategies. In the present study, we have performed an iTRAQ-based quantitative proteomic analysis of secretomes from healthy human articular cartilage explants, comparing their protein profile to those from unwounded (early disease) and wounded (advanced disease) zones of osteoarthritic tissue. This strategy allowed us to identify a panel of 76 proteins that are distinctively released by the diseased tissue. Clustering analysis allowed the classification of proteins according to their different profile of release from cartilage. Among these proteins, the altered release of osteoprotegerin (decreased in OA) and periostin (increased in OA), both involved in bone remodelling processes, was verified in further analyses. Moreover, periostin was also increased in the synovial fluid of OA patients. Altogether, the present work provides a novel insight into the mechanisms of human cartilage degradation and a number of new cartilage-characteristic proteins with possible biomarker value for early diagnosis and prognosis of OA.

Topics: Aged; Aged, 80 and over; Biomarkers; Blotting, Western; Cartilage, Articular; Cell Adhesion Molecules; Chromatography, Liquid; Female; Humans; Male; Middle Aged; Multivariate Analysis; Osteoarthritis; Osteoprotegerin; Proteome; Proteomics; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Synovial Fluid; Tandem Mass Spectrometry; Tissue Culture Techniques

To evaluate the expression of Dickkopf-1 protein factor (DKK-1), DKK-2, and β-catenin, components of the Wnt pathway, in human osteoarthritic (OA) and osteoporotic (OP) osteoblasts and to correlate it to cell metabolic activity, proliferation, and receptor activator of nuclear factor-κB ligand/osteoprotegerin (RANKL/OPG) expression.. Primary human osteoblast cultures were obtained from healthy, OA, and OP donors. In each cell population we evaluated DKK-1, DKK-2, nonphosphorylated β-catenin and RANKL/OPG expression, osteocalcin and alkaline phosphatase (ALP) synthesis, and cell proliferation, both in basal condition and after vitamin D3 stimulation.. DKK-1 and DKK-2 showed opposite patterns of expression in OA and OP osteoblasts. The RANKL/OPG ratio was significantly higher in the OP group because of a greater expression of RANKL, whereas it was significantly lower in the OA group because of a higher expression of OPG. Treatment with vitamin D3 increased the RANKL/OPG ratio and DKK-2 expression and reduced DKK-1 expression in each cell population, but did not affect β-catenin levels. Both osteocalcin and ALP production and cell proliferation were enhanced in OA cells and reduced in the OP ones.. These data confirm that OA and OP are characterized by opposite bone changes, consisting of reduced bone remodeling processes with increased osteoblast activity in OA, and enhanced bone resorptive activity with reduction of osteoblast metabolism in OP, and suggest that the Wnt pathway is involved in the pathogenesis of both diseases.

Topics: Adult; Aged; Alkaline Phosphatase; Bone Resorption; Cell Proliferation; Cells, Cultured; Cholecalciferol; Female; Humans; Intercellular Signaling Peptides and Proteins; Male; Middle Aged; Osteoarthritis; Osteoblasts; Osteoporosis; Osteoprotegerin; RANK Ligand; Wnt Signaling Pathway

The purposes of this research were to investigate the long-term responses of mandibular condylar cartilage to experimentally induced disordered occlusion and to evaluate changes in the expression of the SDF-1/CXCR4 axis.. Experimentally induced disordered occlusions were created in 8-week-old female Sprague-Dawley rats by orthodontic methods. After 24 weeks, remodeling of the mandibular condylar cartilage was assessed by hematoxylin and eosin staining. Protein and mRNA expression of SDF-1, CXCR4, MMP9, IL6, OPG, and RANKL were investigated by means of immunohistochemical staining and real-time polymerase chain reaction.. Obvious cartilage degenerative remodeling responses were observed; they appeared as uneven distributions of cellular disposition, loss of cartilage surface integrity, and cell-free areas. Regenerative responses presenting as thickening of the whole and the calcified cartilage layers in the experimental group were also observed. Compared with the age-matched controls, the protein and mRNA levels of SDF-1, CXCR4, MMP9, IL6, and OPG, but not RANKL, were increased in the experimental group (all, P <0.05). In addition, the mRNA level of RANKL/OPG showed a decreasing trend in the experimental group compared with the age-matched controls (P = 0.052).. This study demonstrated that long-term experimentally induced disordered occlusion leads to a combined response in degeneration and regeneration of mandibular cartilage, accompanied by active interaction of the SDF-1/CXCR4 axis and local upregulation of MMP9, IL6, and OPG.

Topics: Animals; Bone Remodeling; Cartilage, Articular; Chemokine CXCL12; Female; Interleukin-6; Malocclusion; Mandibular Condyle; Matrix Metalloproteinase 9; Osteoarthritis; Osteoprotegerin; RANK Ligand; Rats; Rats, Sprague-Dawley; Receptors, CXCR4; Regeneration; Temporomandibular Joint Disorders

The pathological changes of subchondral bone during osteoarthritis (OA) development in the temporomandibular joint (TMJ) are poorly understood. In the present study, we investigated the longitudinal alterations of subchondral bone using a rat TMJ-OA model developed in our laboratory. Changes in bone mass were examined by micro-CT, and changes in osteoblast and osteoclast activities were analyzed by real-time PCR, immunohistochemistry, and TRAP staining. Subchondral bone loss was detected from 8 weeks after dental occlusion alteration and reached the maximum at 12 weeks, followed by a repair phase until 32 weeks. Although bone mass increased at late stages, poor mechanical structure and lower bone mineral density (BMD) were found in these rats. The numbers of TRAP-positive cells were increased at 12 weeks, while the numbers of osteocalcin-expressing cells were increased at both 12 and 32 weeks. Levels of mRNA expression of TRAP and cathepsin K were increased at 12 weeks, while levels of ALP and osteocalcin were increased at both 12 and 32 weeks. These findings demonstrated that there is an active bone remodeling in subchondral bone in TMJs in response to alteration in occlusion, although new bone was formed with lower BMD and poor mechanical properties.

Topics: Animals; Bone Density; Bone Remodeling; Cathepsin K; Dental Occlusion, Traumatic; Dental Stress Analysis; Disease Models, Animal; Female; Mandibular Condyle; Osteoarthritis; Osteoblasts; Osteocalcin; Osteoclasts; Osteoprotegerin; Random Allocation; RANK Ligand; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Temporomandibular Joint; Temporomandibular Joint Disorders; X-Ray Microtomography

The objective of the study was to determine whether cartilage expression of the bone regulating molecules receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) varies between the different grades of osteoarthritis (OA). Cartilage samples were obtained from 30 patients undergoing total hip/knee replacement surgery. Tissue sections were stained with Safranin O and graded. Immunohistochemical staining was then performed, and levels of RANKL and OPG expression were assessed using a semi-quantitative scoring system. In addition, levels of mRNA encoding for RANKL and OPG were determined by a relative real-time reverse transcription-polymerase chain reaction technique. We found that expression of RANKL protein, mRNA expression, and the ratio of RANKL: OPG mRNA was greater in grade 2 cartilage in comparison with grade 0 cartilage (P < 0.05). Increased RANKL staining in the grade 2 cartilage was predominantly in the peri-cellular region of the middle and deep zones as well as in the matrix of the superficial zone. OPG mRNA expression was greater in grade 3 cartilage in comparison with grade 0 cartilage (P < 0.05). Cartilage and subchondral bone are in close proximity and soluble proteins produced in the cartilage are likely to move from one compartment to the other. Our finding of increased expression of RANKL in grade 2 OA cartilage might explain the increase in bone turnover reported in the subchondral bone of OA patients. The changes seen in the different grades of tissue may also indicate that this effect occurs during the early stages of OA development.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers; Cartilage, Articular; Female; Gene Expression Regulation; Humans; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; RANK Ligand; RNA, Messenger

There is a paucity of studies investigating association between ROR2 gene variants and osteoporosis and osteoarthritis-related phenotypes. The published literature suggests that osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) are essential for bone metabolism and correlate with osteoarthritis manifestation and progression. The present study provides evidence of the significant association between ROR2 variants and the OPG/RANKL ratio in human plasma. The present results also suggest significant association between ROR2 polymorphisms and severity of radiographic hand osteoarthritis.. Despite the importance of the ROR-2 in skeletal physiology, there is a paucity of studies investigating the potential association of ROR2 gene variants with phenotypes relevant to osteoporosis and osteoarthritis. On the other hand, there is a considerable body of literature suggesting that OPG and RANKL and their ratio (OPG/RANKL) are essential for regulating bone resorption. This is also correlated with osteoarthritis manifestation and progression. The present study therefore examines whether ROR2 polymorphisms may be associated with the OPG/RANKL ratio and hand osteoarthritis (HOA).. The study was conducted in a family-based sample of 1,515 Caucasian individuals, assessed for radiographic hand osteoarthritis, using the Kellgren/Lawrence score. Of these, 865 individuals were genotyped for 19 SNPs, relatively equally covering the ROR2 locus, and their plasma levels of OPG and RANKL were assayed. The association between the selected SNPs and OPG, along with the OPG/RANKL ratio and HOA, was explored using the pedigree disequilibrium test.. Of the total of 57 tests, 16 nominally significant results (p < 0.05) were obtained, which is considerably more than the three normally expected for type I error. The significant association signals for all three phenotypes were mapped to the intron 1 region. The most significant results were detected between OPG/RANKL and rs7048756 (p < 0.0005) and between adjacent rs4744107 and Kellgren/Lawrence score (p = 0.006).. The present study provides evidence of the significant association between ROR2 variants and the OPG/RANKL ratio in human plasma and also suggests ROR2 association with HOA.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Biomarkers; Female; Genetic Association Studies; Genetic Predisposition to Disease; Genotype; Hand Joints; Humans; Linkage Disequilibrium; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Phenotype; Polymorphism, Single Nucleotide; Radiography; RANK Ligand; Receptor Tyrosine Kinase-like Orphan Receptors; Young Adult

Pro-inflammatory cytokines possess osteoclastogenic or anti-osteoclastogenic activities. They influence osteoclasts directly or via the receptor activator of nuclear factor κB (RANK), RANK ligand (RANKL) and osteoprotegerin (OPG) system. Recent evidence suggests that inflammation may play a role in osteoporosis (OP) and osteoarthritis (OA). We aimed therefore to determine whether there is a difference between both groups: first, in the expression of the osteoclastogenic and anti-osteoclastogenic cytokines, second, in correlation of these cytokines with bone mineral density (BMD) and levels of bone turnover markers (BTM) and third, in correlation between the expression of these cytokines and osteoclast specific genes and RANK/RANKL/OPG genes.. Human bone samples from 54 age and sex matched patients with OP or OA were collected during hip arthroplasty surgery. The expression of 25 genes encoding pro-inflammatory cytokines, their receptors, osteoclast specific genes and RANK/RANKL/OPG genes was measured using quantitative real-time PCR. Total hip, femoral neck and lumbar spine BMD and BTM in blood samples were measured. The comparison between OP and OA was assessed using Student's t-test or Mann-Whitney U test and correlations between gene expression, BMD and BTM were determined using nonparametric correlation.. The results demonstrated a higher expression of interleukin (IL)-6 and IL-1α in OP, and interferon (IFN)-γ in OA (p < 0.0005). Negative correlations of total hip BMD with tumor necrosis factor-α (TNF-α) in OA and with RANKL/RANK in OP were found (p < 0.05). Significant correlations with BTM were shown for IL-1α and IFN-γ in OP (rho = 0.608 and -0.634) and for TNF-α, IL-6 and transforming growth factor-β1 (TGF-β1) in OA (rho = 0.591, -0.521 and 0.636). Results showed OP specific negative correlations (IFN-γ with ITGB3, IFN-β1 with CTSK, tartrate resistant acid phosphatase (TRAP), CALCR, RANK, RANKL, IL-1α with CTSK, OPG, IL-17A with CALCR) and positive (TGF-β1 with CTSK, TRAP, RANK), and OA specific negative (IL-1α with osteoclast associated immunoglobulin-like receptor (OSCAR), TNF-α with RANK, RANKL, OPG) and positive (IL-6 with RANK, RANKL, OPG) correlations.. Our results demonstrate that the relationship between osteoclastogenic and anti-osteoclastogenic pro-inflammatory cytokines differs in human OP and OA bone and could present an important factor for characteristics of OP and OA bone phenotypes.

Topics: Aged; Arthroplasty; Bone Density; Cytokines; Female; Gene Expression Regulation; Humans; Inflammation; Male; Osteoarthritis; Osteoclasts; Osteoporosis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytokine

Subchondral bone modifications occur early in the development of osteoarthritis (OA). The level of bone resorption might impact cartilage remodeling. We therefore assessed the in vivo and in vitro effects of targeting bone resorption in OA and cartilage metabolism.. OA was induced by meniscectomy (MNX) in ovariectomized osteopenic mice (OP) treated with estradiol (E2), pamidronate (PAM), or phosphate buffered saline (PBS) for 6 weeks. We assessed the subchondral bone and cartilage structure and the expression of cartilage matrix proteases. To assess the involvement of bone soluble factors in cartilage metabolism, supernatant of human bone explants pre-treated with E2 or PAM were transferred to cartilage explants to assess proteoglycan release and aggrecan cleavage. OPG/RANKL mRNA expression was assessed in bone explants by real-time quantitative PCR. The role of osteoprotegerin (OPG) in the bone-cartilage crosstalk was tested using an OPG neutralizing antibody.. Bone mineral density of OP mice and osteoclast number were restored by E2 and PAM (p<0.05). In OP mice, E2 and PAM decreased ADAMTS-4 and -5 expression, while only PAM markedly reduced OA compared to PBS (2.0±0.63 vs 5.2±0.95; p<0.05). OPG/RANKL mRNA was increased in human bone explants treated with both drugs (2.2-3.7-fold). Moreover, supernatants from bone explants cultured with E2 or PAM reduced aggrecan cleavage and cartilage proteoglycan release (73±8.0% and 80±22% of control, respectively, p<0.05). This effect was reversed with osteoprotegerin blockade.. The inhibition of bone resorption by pamidronate in osteopenic mice alleviates the histological OA score with a reduction in the expression of aggrecanases. Bone soluble factors, such as osteoprotegerin, impact the cartilage response to catabolic factors. This study further highlights the importance of subchondral bone in the regulation of joint cartilage damage in OA.

Topics: ADAM Proteins; ADAMTS5 Protein; Animals; Bone and Bones; Bone Diseases, Metabolic; Bone Resorption; Cartilage; Diphosphonates; Estradiol; Female; Humans; Menisci, Tibial; Mice; Mice, Inbred C57BL; Osteoarthritis; Osteoprotegerin; Pamidronate; Protective Agents

Bone destruction is a common feature of inflammatory arthritis and is mediated by osteoclasts, the only specialized cells to carry out bone resorption. Aberrant expression of receptor activator of nuclear factor kappa β ligand (RANKL), an inducer of osteoclast differentiation has been linked with bone pathology and the synovial fibroblast in rheumatoid arthritis (RA). In this manuscript, we challenge the current concept that an increase in RANKL expression governs osteoclastogenesis and bone destruction in autoimmune arthritis. We isolated human fibroblasts from RA, pyrophosphate arthropathy (PPA) and osteoarthritis (OA) patients and analyzed their RANKL/OPG expression profile and the capacity of their secreted factors to induce osteoclastogenesis. We determined a 10-fold increase of RANKL mRNA and protein in fibroblasts isolated from RA relative to PPA and OA patients. Peripheral blood mononuclear cells (PBMC) from healthy volunteers were cultured in the presence of RA, PPA and OA synovial fibroblast conditioned medium. Osteoclast differentiation was assessed by expression of tartrate-resistant acid phosphatase (TRAP), vitronectin receptor (VNR), F-actin ring formation and bone resorption assays. The formation of TRAP(+), VNR(+) multinucleated cells, capable of F-actin ring formation and lacunar resorption in synovial fibroblast conditioned medium cultures occured in the presence of osteoprotegerin (OPG) a RANKL antagonist. Osteoclasts did not form in these cultures in the absence of macrophage colony stimulating factor (M-CSF). Our data suggest that the conditioned medium of pure synovial fibroblast cultures contain inflammatory mediators that can induce osteoclast formation in human PBMC independently of RANKL. Moreover inhibition of the TNF or IL-6 pathway was not sufficient to abolish osteoclastogenic signals derived from arthritic synovial fibroblasts. Collectively, our data clearly show that alternate osteoclastogenic pathways exist in inflammatory arthritis and place the synovial fibroblast as a key regulatory cell in bone and joint destruction, which is a hallmark of autoimmune arthritis.

Topics: Acid Phosphatase; Actins; Arthritis, Rheumatoid; Bone Resorption; Cell Differentiation; Cells, Cultured; Chondrocalcinosis; Culture Media, Conditioned; Fibroblasts; Gene Expression Regulation; Humans; Integrin alphaVbeta3; Interleukin-6; Isoenzymes; Leukocytes, Mononuclear; Osteoarthritis; Osteoclasts; Osteoprotegerin; RANK Ligand; Signal Transduction; Synovial Fluid; Tartrate-Resistant Acid Phosphatase; Tumor Necrosis Factor-alpha

The osteoprotegerin/RANKL system modulates bone remodelling. Alendronate and raloxifene are anti-resorptive drugs effective in osteoporotic disease. They reduce fracture risk, the activity of bone remodelling and increase bone mineral density. It is not known if they can exert a direct effect in osteoblasts via the osteoprotegerin/RANKL system. Our objective was to assess the effects of alendronate and raloxifene among osteoprotegerin production (ELISA), as well as osteoprotegerin and RANKL expression (RT-PCR), in primary cultures of human osteoblasts (hOB). We compared 17 osteoporotic patients with 16 patients affected by osteoarthritis in basal conditions and after incubation with alendronate (10(-6) M), raloxifene (10(-7) M) or 17-β estradiol (10(-7) M) for 24 h. The statistical analysis was determined by ANOVA. Osteoprotegerin protein secretion in hOB cultures was higher in patients with osteoporosis than osteoarthritis. Osteoprotegerin secretion levels remained unchanged after each treatment. The osteoporotic group was more sensitive to treatment. Both raloxifene (34%) and estradiol (37%) increased osteoprotegerin mRNA expression, and alendronate (118%) and raloxifene (61%) increased the mRNA expression of RANKL. The RANKL/osteoprotegerin mRNA ratio was higher in osteoporotic than osteoarthritic patients. In the osteoporotic group, the RANKL/osteoprotegerin mRNA ratio was significantly increased after treatment with alendronate (112%) and after treatment with raloxifene (60%). These results indicate a direct action of alendronate and raloxifene on hOB cultures from osteoporotic patients, and the cited drugs are able to modulate the osteoprotegerin/RANKL system.

Topics: Aged; Aged, 80 and over; Alendronate; Bone Density Conservation Agents; Bone Remodeling; Cells, Cultured; Estradiol; Female; Humans; Male; Middle Aged; Osteoarthritis; Osteoblasts; Osteoporosis, Postmenopausal; Osteoprotegerin; Raloxifene Hydrochloride; RANK Ligand; RNA, Messenger

This study evaluates cytokines production in bone and bone marrow of patients with an osteoporotic fracture or with osteoarthritis by real time PCR, Western blot and immunohistochemistry. We demonstrate that the cytokine pattern is shifted towards osteoclast activation and osteoblast inhibition in patients with osteoporotic fractures.. Fragility fractures are the resultant of low bone mass and poor bone architecture typical of osteoporosis. Cytokines involved in the control of bone cell maturation and function are produced by both bone itself and bone marrow cells, but the roles of these two sources in its control and the amounts they produce are not clear. This study compares their production in patients with an osteoporotic fracture and those with osteoarthritis.. We evaluated 52 femoral heads from women subjected to hip-joint replacement surgery for femoral neck fractures due to low-energy trauma (37), or for osteoarthritis (15). Total RNA was extracted from both bone and bone marrow, and quantitative PCR was used to identify the receptor activator of nuclear factor kB Ligand (RANKL), osteoprotegerin (OPG), macrophage colony stimulating factor (M-CSF), transforming growth factor β (TGFβ), Dickoppf-1 (DKK-1) and sclerostin (SOST) expression. Immunohistochemistry and Western blot were performed in order to quantify and localize in bone and bone marrow the cytokines.. We found an increase of RANKL/OPG ratio, M-CSF, SOST and DKK-1 in fractured patients, whereas TGFβ was increased in osteoarthritic bone. Bone marrow produced greater amounts of RANKL, M-CSF and TGFβ compared to bone, whereas the production of DKK-1 and SOST was higher in bone.. We show that bone marrow cells produced the greater amount of pro-osteoclastogenic cytokines, whereas bone cells produced higher amount of osteoblast inhibitors in patients with fragility fracture, thus the cytokine pattern is shifted towards osteoclast activation and osteoblast inhibition in these patients.

Topics: Adaptor Proteins, Signal Transducing; Aged; Aged, 80 and over; Blotting, Western; Bone Marrow; Bone Morphogenetic Proteins; Cytokines; Female; Femur Head; Genetic Markers; Humans; Intercellular Signaling Peptides and Proteins; Macrophage Colony-Stimulating Factor; Middle Aged; Osteoarthritis; Osteoblasts; Osteoclasts; Osteoporotic Fractures; Osteoprotegerin; RANK Ligand; Real-Time Polymerase Chain Reaction; Transforming Growth Factor beta

Results of studies in mice suggest a protective role for TRAIL in arthritis. The aim of this study was to investigate the role of TRAIL in patients with rheumatoid arthritis (RA).. In the present study, we compared RA fibroblast-like synoviocytes (FLS) that were resistant or sensitive to TRAIL-induced apoptosis and the expression of TRAIL receptors in these cells, and also investigated the clinical features of the patients from whom the FLS were derived. Furthermore, we evaluated the levels of TRAIL and its soluble decoy receptor osteoprotegerin (OPG) in patients with RA, patients with osteoarthritis (OA), and patients with spondylarthritis (SpA).. Sensitivity to TRAIL-induced apoptosis varied in FLS from different patients, and the severity of disease in patients with RA was inversely correlated with the susceptibility of their FLS to TRAIL-induced apoptosis. TRAIL-sensitive cells expressed significantly lower levels of TRAILR-1, and silencing of TRAILR-1 increased TRAIL-induced apoptosis in RA FLS. TRAIL levels were elevated in the arthritic joints of patients with established RA, and TRAIL levels in the synovial fluid of these patients were elevated compared with levels in the synovial fluid of patients with OA or SpA. At baseline, a low OPG-to-TRAIL ratio in the sera of patients with early RA was associated with a better evolution of disease activity, but high serum levels of TRAIL at followup were associated with joint damage.. These findings suggest that TRAIL has a dual role in RA, and that the resistance of RA FLS to TRAIL-induced apoptosis is associated with a disease-promoting activity of TRAIL in RA.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Apoptosis; Arthritis, Rheumatoid; Female; Fibroblasts; Humans; Interleukin-6; Interleukin-8; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Severity of Illness Index; Spondylarthritis; Synovial Membrane; TNF-Related Apoptosis-Inducing Ligand; Young Adult

Temporomandibular joint osteoarthritis (TMJ OA) is a degenerative disease that affects both cartilage and subchondral bone. We used microarray to identify changes in gene expression levels in the TMJ during early stages of the disease, using an established TMJ OA genetic mouse model deficient in 2 extracellular matrix proteins, biglycan and fibromodulin (bgn(-/0)fmod(-/-)). Differential gene expression analysis was performed with RNA extracted from 3-week-old WT and bgn(-/0)fmod(-/-) TMJs with an intact cartilage/subchondral bone interface. In total, 22 genes were differentially expressed in bgn(-/0)fmod(-/-) TMJs, including 5 genes involved in osteoclast activity/differentiation. The number of TRAP-positive cells were three-fold higher in bgn(-/0)fmod(-/-) TMJs than in WT. Quantitative RT-PCR showed up-regulation of RANKL and OPG, with a 128% increase in RANKL/OPG ratio in bgn(-/0)fmod(-/-) TMJs. Histology and immunohistochemistry revealed tissue disorganization and reduced type I collagen in bgn(-/0)fmod(-/-) TMJ subchondral bone. Early changes in gene expression and tissue defects in young bgn(-/0)fmod(-/-) TMJ subchondral bone are likely attributed to increased osteoclast activity. Analysis of these data shows that biglycan and fibromodulin are critical for TMJ subchondral bone integrity and reveal a potential role for TMJ subchondral bone turnover during the initial early stages of TMJ OA disease in this model.

Topics: Animals; Arthritis, Experimental; Biglycan; Bone and Bones; Bone Remodeling; Cartilage, Articular; Disease Models, Animal; Extracellular Matrix Proteins; Fibromodulin; Gene Expression Profiling; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oligonucleotide Array Sequence Analysis; Osteoarthritis; Osteoclasts; Osteoprotegerin; Proteoglycans; RANK Ligand; Reverse Transcriptase Polymerase Chain Reaction; Temporomandibular Joint Disorders

To demonstrate that posttranslational modification of type II collagen (CII) by reactive oxygen species (ROS), which are known to be present in inflamed arthritic joints, can give rise to epitopes specific to damaged cartilage in rheumatoid arthritis (RA) and osteoarthritis (OA) and to establish a proof of concept that antibodies specific to ROS-modified CII can be used to target therapeutics specifically to inflamed arthritic joints.. We used a semisynthetic phage display human antibody library to raise single-chain variable fragments (scFv) specific to ROS-modified CII. The specificity of anti-ROS-modified CII scFv to damaged arthritic cartilage was assessed in vitro by immunostaining articular cartilage from RA and OA patients and from normal controls. The in vivo targeting potential was tested using mice with antigen-induced arthritis, in which localization of anti-ROS-modified CII scFv in the joints was determined. The therapeutic effect of anti-ROS-modified CII scFv fused to soluble murine tumor necrosis factor receptor II-Fc fusion protein (mTNFRII-Fc) was also investigated.. The anti-ROS-modified CII scFv bound to damaged arthritic cartilage from patients with RA and OA but not to normal preserved cartilage. When systemically administered to arthritic mice, the anti-ROS-modified CII accumulated selectively at the inflamed joints. Importantly, when fused to mTNFRII-Fc, it significantly reduced inflammation in arthritic mice, as compared with the effects of mTNFRII-Fc alone or of mTNFRII-Fc fused to an irrelevant scFv.. Our findings indicate that biologic therapeutics can be targeted specifically to arthritic joints and suggest a new approach for the development of novel treatments of arthritis.

Topics: Animals; Arthritis, Rheumatoid; Cartilage; Cartilage, Articular; Cattle; Disease Models, Animal; Epitopes; Humans; Immunoglobulin Fc Fragments; Immunohistochemistry; Mice; Mice, Inbred C57BL; Osteoarthritis; Osteoprotegerin; Reactive Oxygen Species; Single-Chain Antibodies

New bone formation of the spine is a typical feature of ankylosing spondylitis (AS). It is unknown whether new bone formation is part of a physiological repair process or a unique pathological entity of the disease.. We analyzed zygapophyseal joints from patients with AS and osteoarthritis (OA) undergoing spinal surgery for rigid hyperkyphosis (AS) or radiculopathy caused by severe OA. In 17 patients with AS, 11 with OA, and 5 controls we performed immunohistochemical analysis of osteoprotegerin (OPG), nuclear factor-kappaB ligand (RANKL), and osteocalcin (OC) expression in osteoblasts and determined the trabecular thickness in AS and OA patients and controls. Osteoclasts were detected by tartrate-resistant alkaline phosphatase (TRAP) staining.. Trabecular thickness was significantly lower in patients with AS compared to OA (p = 0.01). The absolute number of CD56+ osteoblasts (p < 0.001) and OC+ (p = 0.002), OPG+ (p = 0.003), and RANKL+ osteoblasts (p = 0.03) in AS patients was also significantly lower than in OA patients. The percentages of OC+, OPG+, and RANKL+ osteoblasts did not differ between AS and OA (p > 0.05 in all cases). In controls, the percentages of OPG+ (p = 0.013) and OC+ (p = 0.034) but not RANKL+ (p > 0.05) osteoblasts were significantly lower compared to AS patients. The frequency of TRAP+ osteoclasts in AS patients was significantly lower compared to OA (p < 0.001), but higher compared to controls.. Immunohistochemical analysis of zygapophyseal joints suggested that osteoblast activity is similar in AS and OA, indicating that new bone formation is possibly a physiological function of repair in both diseases.

Topics: Adult; Alkaline Phosphatase; Female; Humans; Immunohistochemistry; Male; Middle Aged; Osteoarthritis; Osteoblasts; Osteocalcin; Osteoclasts; Osteoprotegerin; RANK Ligand; Spondylitis, Ankylosing; Statistics, Nonparametric; Zygapophyseal Joint

This study aims to explore the potential role of circulating Dickkopf-1 (Dkk-1) and osteoprotegerin (OPG) in evaluating erosive arthritis in systemic lupus erythematosus (SLE).. Serum Dkk-1 and OPG levels were examined in 130 SLE patients including eight with erosive arthritis, 100 rheumatoid arthritis (RA) patients and 50 healthy individuals by ELISA. Comparison of serum Dkk-1 levels with presence of anti-cyclic citrullinated peptides (CCP) antibodies in evaluating erosive arthritis in SLE was carried out. Associations of Dkk-1 and OPG levels with results of clinical examination were also noted.. Dkk-1 levels were significantly increased in eight SLE patients with erosive arthritis, compared to 58 SLE patients with non-erosive arthritis, 64 SLE patients without arthritis, and healthy controls, while similar with RA. In contrast, no significant changes of OPG levels were found except for higher levels in RA. No differences were found in Dkk-1 levels of SLE patients with erosive arthritis subdivided according to presence or absence of anti-CCP antibodies. Moreover, higher levels of Dkk-1 were identified in anti-CCP positive SLE patients with erosive arthritis compared to those with non-erosive arthritis or without arthritis. However, no significant correlations between Dkk-1 and OPG levels or between Dkk-1 levels and other laboratory and clinical manifestations were observed.. High levels of circulating Dkk-1 were associated with bone erosion in patients with SLE, even when anti-CCP antibodies were absent.

Topics: Adolescent; Adult; Aged; Antibodies, Antinuclear; Biomarkers; Bone Resorption; Disease Progression; Female; Humans; Intercellular Signaling Peptides and Proteins; Lupus Erythematosus, Systemic; Male; Middle Aged; Osteoarthritis; Osteoprotegerin

The aim of the study was to evaluate the association between prevalence and severity of radiographic hand osteoarthritis (OA) and serum levels of systemic inflammatory markers in a community-based population sample.. A cross-sectional observational study was conducted on a population comprised 1452 Chuvashians (763 males, aged 49.23 ± 17.43; and 689 females, aged 50.37 ± 17.47 years). OA was evaluated in 14 joints of each hand using Kellgren and Lawrence (K-L), joint space narrowing (JSN) and osteophyte (OS) scores. Serum levels of systemic inflammatory and osteoclastogenic cytokines were measured by an enzyme-linked immunosorbent assay (ELISA). Statistical analyses included descriptive statistics, correlation analysis and multiple linear regressions.. Monocyte chemotactic protein-1 (MCP-1) and osteoprotegerin (OPG) levels were associated with OA traits, but the statistically significant correlations were weak and/or moderate. In particular, the MCP-1 inflammation marker showed a statistically significant association with JSN (β=0.077, P=0.022) and OS (β=0.067, P=0.024) scores, but not with the number of affected joints (K-L ≥ 2). OPG was significantly correlated with the scores as to the number of affected joints (β=0.063, P=0.035) and OS (β=0.077, P=0.028). No significant associations were found between levels of other inflammatory [interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-17] and osteoclastogenic [receptor activator for nuclear factor κ B ligand (RANKL), macrophage colony-stimulating factor (M-CSF)] cytokines and OA characteristics.. This study strengthens the premise that OPG might be a valid biomarker of hand OA. Confirmation of these results in larger cohorts of patients will reinforce our theory that the RANKL/OPG pathway is a suitable target for developing novel agents against OA.

Topics: Biomarkers; Chemokine CCL2; Cross-Sectional Studies; Cytokines; Female; Hand Joints; Humans; Inflammation; Interleukin-6; Linear Models; Macrophage Colony-Stimulating Factor; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Radiography; Receptor Activator of Nuclear Factor-kappa B; Tumor Necrosis Factor-alpha

In chronic arthritis cartilage and bone destruction occur as a consequence of synovial inflammation. It is mainly mediated by matrix metalloproteinases and RANKL-OPG pathways. Data on synovial fluid levels of these mediators in enthesitis related arthritis subtype (ERA) of JIA are not available. MMP-1, MMP-3, TIMP, sRANKL and OPG levels were measured in synovial fluid from patients with ERA and compared with other arthritides, polyarticular (Poly) JIA, RA and osteoarthritis (OA). sRANKL was detectable in 25/41 of ERA patients, 4/16 of Poly JIA patients. Median SF sRANKL level in patients with ERA was higher as compared to OA (p < 0.001) and poly JIA (p < 0.05) but were comparable to RA. The median OPG level in ERA was lower as compared to OA (p < 0.001), comparable to RA but was higher than poly JIA (p < 0.001). sRANKL/OPG ratio was significantly higher in ERA and Poly JIA compared to OA (p < 0.0001, p < 0.0001 respectively). The median MMP3 levels in ERA (74 microg/ml) was lower as compared to poly JIA (410 microg/ml; p < 0.0001) and RA (340 ug/ml; p < 0.0001) but was comparable to OA (107 microg/ml). The median level of ProMMP1 in ERA (0.70 microg/ml) was lower as compared to RA (2.9 microg/ml; p < 0.0001) and poly JIA but was elevated as compared to OA patients (0.1 microg/ml; p < 0.0001). TIMP1 levels in ERA were higher than poly JIA and RA patients. MMP3/TIMP1 ratio was lower in ERA compared to polyarticular JIA patients (p < 0.05). Ours is the first study reporting elevated sRANKL and reduced OPG levels and elevated sRANKL/OPG ratio in SF of children with JIA resulting in a mileu associated with bone loss. In addition, ERA patients had lower MMP level as well as MMP/TIMP ratio as compared to poly JIA which may partly explain lesser degree of joint damage seen in ERA as compared to poly JIA.

Topics: Adolescent; Adult; Aged; Arthritis, Juvenile; Arthritis, Rheumatoid; Child; Child, Preschool; Female; Humans; Male; Matrix Metalloproteinases; Middle Aged; Osteoarthritis; Osteoprotegerin; RANK Ligand; Synovial Fluid; Tissue Inhibitor of Metalloproteinase-1

The OPG/RANKL/RANK system is important in the balance between bone formation and resorption. We used primary human osteoblasts (hOBs) cells to examine the impact of 17-beta-estradiol (E2) or/and 1,25-dihydroxyvitamin D (1,25D) in OPG/RANKL system in 28 post-menopausal (PM) women; (a) with hip fracture (OP) or (b) with osteoarthritis (OA). The hOB from OP patients proliferated slower during the first stage, than the OA women (31.5+/-2.6 and 21.4+/-1.3 days, respectively, p<0.05). The OP group secreted significantly higher OPG protein levels than the OA women (10.1+/-2.6 and 4.4+/-0.8pmol/L, respectively, p<0.05). The 1,25D and 1,25D+E2 induce an increase in RANKL and RANKL/OPG mRNA expression in OP patients above 200% (p<0.05). HOBs from the osteoporotic hip initially proliferate slower but after reaching the first cellular confluence, the proliferation rate is equal in both groups. Furthermore, hOBs from hips with OP present a higher protein secretion of OPG, and higher RANKL and RANKL/OPG expression ratio in response to 1,25D and 1,25D+E2, than hOBs from OA women. All this could suggest that the greater bone loss that characterizes OP patients can be mediated due to differences in the secretion and expression of the RANKL/OPG system in response to different stimuli.

Topics: Aged; Aged, 80 and over; Cells, Cultured; Estradiol; Female; Gene Expression Regulation; Hip Fractures; Humans; Osteoarthritis; Osteoblasts; Osteoporosis; Osteoprotegerin; Postmenopause; RANK Ligand; RNA, Messenger; Vitamin D

To determine if the receptor activator of nuclear factor-kappaB-receptor activator of nuclear factor-kappaB ligand-osteoprotegerin (RANK-RANKL-OPG) system is active in bone remodeling in dogs and, if so, whether differences in expression of these mediators occur in healthy and arthritic joints.. Experimental study.. Fragmented processus coronoidei (n=20) were surgically removed from dogs with elbow arthritis and 5 corresponding healthy samples from dogs euthanatized for reasons other than elbow joint disease.. Bright-field immunohistochemistry and high-resolution fluorescence microscopy were used to investigate the distribution of RANK, RANKL, and OPG in healthy and arthritic joints.. All 3 molecules were identified by immunostaining of canine bone tissue. In elbow dysplasia, the number of RANK-positive osteoclasts was increased. In their vicinity, cells expressing RANKL, a mediator of osteoclast activation, were abundant whereas the number of osteoblasts having the potential to limit osteoclastogenesis and bone resorption via OPG was few.. The RANK-RANKL-OPG system is active in bone remodeling in dogs. In elbow dysplasia, a surplus of molecules promoting osteoclastogenesis was evident and is indicative of an imbalance between the mediators regulating bone resorption and bone formation. Both OPG and neutralizing antibodies against RANKL have the potential to counterbalance bone resorption.. Therapeutic use of neutralizing antibodies against RANKL to inhibit osteoclast activation warrants further investigation.

Topics: Animals; Bone and Bones; Bone Remodeling; Dog Diseases; Dogs; Forelimb; Microscopy, Fluorescence; Osteoarthritis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B

The mechanisms of osteoclast maturation and the role of rheumatoid arthritis (RA) synovial fibroblasts in the control of osteoclastogenesis remain unclear. The purpose of this study was to determine the humoral factors that influence osteoclast differentiation resulting from mutual interactions between osteoclast progenitor cells and synovial fibroblasts.. The cloned mouse macrophage cell line RAW 264.7 or isolated human CD14+ monocytes were cocultured with RA or osteoarthritis (OA) synovial fibroblasts in the presence of RANKL. Osteoclasts were visualized by staining for tartrate-resistant acid phosphatase (TRAP), and their functions were evaluated by bone resorption assay. Transforming growth factor beta (TGFbeta) and osteoprotegerin (OPG) levels were measured by enzyme-linked immunosorbent assay. Expression of pSmad2 and Smad7 was analyzed by Western blotting.. RANKL-mediated osteoclast formation was observed in cocultures of RAW cells with RA synovial cells, but not with OA synovial cells. This formation was inhibited by TGFbeta receptor kinase inhibitor or neutralizing TGFbeta antibody. Human CD14+ monocytes showed the same results with RAW 264.7, and bone resorption activity was consistent with osteoclast formation. RA synovial fibroblasts produced TGFbeta in response to cell-cell contact with RAW cells in a RANKL-dependent manner. TGFbeta reduced OPG production by RA synovial fibroblasts, but dose-dependently increased OPG secretion in OA synovial fibroblasts. TGFbeta decreased the expression of pSmad2 and increased the expression of Smad7 in RA synovial fibroblasts, but not OA synovial fibroblasts.. Suppression of OPG production by down-regulation of TGFbeta/Smad2 signaling may contribute to RANKL-mediated osteoclastogenesis from RA synovial fibroblasts.

Topics: Animals; Arthritis, Rheumatoid; Bone Resorption; Cell Differentiation; Cell Line; Cloning, Organism; Down-Regulation; Fibroblasts; Humans; Mice; Monocytes; Osteoarthritis; Osteoclasts; Osteoprotegerin; RANK Ligand; Receptors, Transforming Growth Factor beta; Signal Transduction; Smad7 Protein; Synovial Membrane; Transforming Growth Factor beta

The relationship of circulating levels of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) with the expression of these molecules in bone has not been established. The objective of this study was to measure, in humans, the serum levels of RANKL and OPG, and the corresponding levels in bone of mRNA encoding these proteins.. Fasting blood samples were obtained on the day of surgery from patients presenting for hip replacement surgery for primary osteoarthritis (OA). Intraoperatively, samples of intertrochanteric trabecular bone were collected for analysis of OPG and RANKL mRNA, using real time RT-PCR. Samples were obtained from 40 patients (15 men with age range 50 to 79 years, and 25 women with age range 47 to 87 years). Serum total RANKL and free OPG levels were measured using ELISA.. Serum OPG levels increased over the age range of this cohort. In the men RANKL mRNA levels were positively related to age, whereas serum RANKL levels were negatively related to age. Again, in the men serum RANKL levels were inversely related (r = -0.70, P = 0.007) to RANKL mRNA levels. Also in the male group, RANKL mRNA levels were associated with a number of indices of bone structure (bone volume fraction relative to bone tissue volume, specific surface of bone relative to bone tissue volume, and trabecular thickness), bone remodelling (eroded surface and osteoid surface), and biochemical markers of bone turnover (serum alkaline phosphatase and osteocalcin, and urinary deoxypyridinoline).. This is the first report to show a relationship between serum RANKL and the expression of RANKL mRNA in bone.

Topics: Aged; Aged, 80 and over; Bone and Bones; Bone Remodeling; Female; Femur; Humans; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; RANK Ligand; RNA, Messenger; Sex Factors

Cathepsin K and MMP-9 are considered to be the most abundant proteases in osteoclasts. TRAP is a marker for osteoclasts, and there is increasing evidence of its proteolytic role in bone resorption. RANKL is a recently discovered regulator of osteoclast maturation and activity and induces expression of many genes. This study compared cathepsin K, MMP-9, TRAP, RANKL, OPG, and osteocalcin gene expression in the proximal femur of patients with osteoarthritis with that of patients with femoral neck fracture. Fifty-six patients undergoing arthroplasty because of osteoarthritis or femoral neck fracture were included in the study. Total mRNA was extracted from the bone samples obtained from the intertrochanteric region of the proximal femur. Real-time RT-PCR was used to quantify CTSK (cathepsin K), MMP-9 (matrix metalloproteinase 9), ACP5 (TRAP), TNFSF11 (RANKL), TNFRSF11B (OPG), and BGLAP (osteocalcin) mRNAs. The levels of mRNAs coding for MMP-9 and osteocalcin indicated higher expression in the osteoarthritic group (P = 0.011, P = 0.001, respectively), whereas RANKL expression and the ratio RANKL/OPG were both significantly lower in the osteoarthritic group than in the fracture group. Expression of cathepsin K, MMP-9, and TRAP relative to RANKL was significantly higher in the osteoarthritic group. Ratios of all three proteolytic enzymes relative to formation marker osteocalcin were higher in the fracture group. Gene expression of cathepsin K, MMP-9, TRAP, RANKL, OPG, and osteocalcin and the association between their mRNA levels pointed to higher bone resorption and bone formation in osteoarthritis, differences in balance between them, and differences in regulation of bone resorption in osteoarthritic and osteoporotic bone.

Topics: Acid Phosphatase; Aged; Aged, 80 and over; Bone Resorption; Cathepsin K; Cathepsins; Female; Gene Expression Regulation; Humans; Isoenzymes; Male; Matrix Metalloproteinase 9; Osteoarthritis; Osteocalcin; Osteoporosis; Osteoprotegerin; RANK Ligand; Tartrate-Resistant Acid Phosphatase

Protein expression of osteopontin (OPN), osteoprotegerin (OPG), bone sialoprotein (BSP), osteocalcin (OC), RANKL and PTHrP was determined by use of immunohistochemical analysis on tissue arrays (48 cases of PVNS, 20 cases of active (a-RA), non-active rheumatoid arthritis (na-RA), and osteoarthritis (OA)). Additionally, gene expression was analysed using complimentary DNA (cDNA) microarrays. All PVNS cases showed a higher level of both protein and gene expression of RANKL, OPN and BSP in comparison with OA cases. Expression of OPG was not significantly different in PVNS compared to OA. The RANKL/OPG expression ratio was significantly higher in PVNS than in OA. High expressions level of proteins involved in bone degradation in PVNS may promote an intra-osseous propagation of the lesion. This evidence suggests that PVNS might respond to treatment using specific inhibitors of RANKL, OPN and BSP.

Topics: Adult; Aged; Biomarkers; Female; Humans; Immunohistochemistry; Integrin-Binding Sialoprotein; Male; Middle Aged; Osteoarthritis; Osteolysis; Osteopontin; Osteoprotegerin; RANK Ligand; RNA; Sialoglycoproteins; Synovitis, Pigmented Villonodular; Tissue Array Analysis

Early in the pathological process of osteoarthritis (OA), subchondral bone remodelling, which is related to altered osteoblast metabolism, takes place. In the present study, we explored in human OA subchondral bone whether chondroitin sulfate (CS), glucosamine sulfate (GS), or both together affect the major bone biomarkers, osteoprotegerin (OPG), receptor activator of nuclear factor-kappa B ligand (RANKL), and the pro-resorptive activity of OA osteoblasts. The effect of CS (200 mug/mL), GS (50 and 200 mug/mL), or both together on human OA subchondral bone osteoblasts, in the presence or absence of 1,25(OH)2D3 (vitamin D3) (50 nM), was determined on the bone biomarkers alkaline phosphatase and osteocalcin, on the expression (mRNA) and production (enzyme-linked immunosorbent assay) of bone remodelling factors OPG and RANKL, and on the pro-resorptive activity of these cells. For the latter experiments, human OA osteoblasts were incubated with differentiated peripheral blood mononuclear cells on a sub-micron synthetic calcium phosphate thin film. Data showed that CS and GS affected neither basal nor vitamin D3-induced alkaline phosphatase or osteocalcin release. Interestingly, OPG expression and production under basal conditions or vitamin D3 treatment were upregulated by CS and by both CS and GS incubated together. Under basal conditions, RANKL expression was significantly reduced by CS and by both drugs incubated together. Under vitamin D3, these drugs also showed a decrease in RANKL level, which, however, did not reach statistical significance. Importantly, under basal conditions, CS and both compounds combined significantly upregulated the expression ratio of OPG/RANKL. Vitamin D3 decreased this ratio, and GS further decreased it. Both drugs reduced the resorption activity, and statistical significance was reached for GS and when CS and GS were incubated together. Our data indicate that CS and GS do not overly affect cell integrity or bone biomarkers. Yet CS and both compounds together increase the expression ratio of OPG/RANKL, suggesting a positive effect on OA subchondral bone structural changes. This was confirmed by the decreased resorptive activity for the combination of CS and GS. These data are of major significance and may help to explain how these two drugs exert a positive effect on OA pathophysiology.

Topics: Aged; Alkaline Phosphatase; Base Sequence; Biomarkers; Bone Resorption; Calcitriol; Cells, Cultured; Chondroitin Sulfates; DNA Primers; Drug Synergism; Glucosamine; Humans; Middle Aged; Osteoarthritis; Osteoblasts; Osteocalcin; Osteoprotegerin; RANK Ligand; RNA, Messenger

Although a recent study suggested the involvement of RANKL and osteoprotegerin (OPG) in the pathogenesis of bone-destructive disease, no study has focused on the RANKL:OPG ratio in the synovial fluid of patients with temporomandibular joint (TMJ) disorder. This communication reports on the concentrations of RANKL and OPG in synovial fluid from TMJ patients and healthy control individuals. In contrast to an unchanged concentration of RANKL, a strong decrease in the concentration of OPG was detected in the synovial fluid from patients with TMJ internal derangement. Treatment with the synovial fluid of osteoarthritis (OA) patients resulted in the high production of osteoclast-like cells from blood mononuclear cells in vitro, as well as in pit formation in dentin slices. The addition of anti-RANKL IgG or OPG attenuated OA-synovial fluid-induced osteoclast formation, suggesting that the increase in the RANKL:OPG ratio in the microenvironment of the joint has the potential to induce osteoclastogenesis in TMJ osteoarthritis.

Topics: Adult; Analysis of Variance; Case-Control Studies; Cell Differentiation; Cells, Cultured; Female; Humans; Immunoglobulin G; Joint Dislocations; Macrophage Colony-Stimulating Factor; Male; Monocytes; Osteoarthritis; Osteoclasts; Osteoprotegerin; RANK Ligand; Synovial Fluid; Temporomandibular Joint Disorders

We examined OPG and soluble RANKL in the serum (sOPG, sRANKL) and synovial fluid (synOPG, synRANKL) in patients with rheumatoid arthritis (RA) and osteoarthritis (OA). OPG and RANKL were measured in 85 patients (44 with RA, 41 patients with OA) in serum and synovial fluid as well. For measuring of OPG and RANKL ELISA tests were used. The results of OPG and RANKL were compared with clinical and radiological scores. We found a negative correlation for OPG and RANKL in synovial fluids: not only for the whole group of patients (P < 0.003, r = -0.32), but also for the subgroups (RA: P < 0.04, r = -0.28, OA: P < 0.002, r = -0.54). SRANKL and synRANKL were positively correlated in the whole group (P < 0.01, r = 0.25) and in the OA group (P < 0.02, r = 0.35); the RA group was showing a trend (P < 0.063, r = 0.24), however. Serum OPG was lower in RA, synOPG higher in OA. The difference between the two patient groups was only significant for synOPG (P < 0.03, r = 0.056), but not for sOPG (P < 0.09, r = 0.19), sRANKL (P < 0.43, r = 0.85) or synRANKL (P < 0.11, r = 0.22). The synOPG:synRANKL ratio was significantly correlated with the Larsen score (P < 0.004, r = 0.38). Synovial OPG is significantly decreased in rheumatoid joints, whereby synovial RANKL is increased. Lower synOPG could reflect a lower protective effect on bone, thus leading to an earlier and more pronounced bone destruction in RA. However, the effect of different mediators for joint destruction in RA and OA seems not to be important to the pathophysiological changes in the joints. The upregulation of serum OPG might be the result of the inflammation; in contrast, an upregulation of RANKL could not be found in the serum of patients with RA and OA.

Topics: Aged; Aged, 80 and over; Arthritis, Rheumatoid; Carrier Proteins; Enzyme-Linked Immunosorbent Assay; Female; Glycoproteins; Humans; Male; Membrane Glycoproteins; Middle Aged; Osteoarthritis; Osteoprotegerin; Radiography; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Severity of Illness Index; Synovial Fluid

Recently, novel members of the TNF/TNF receptor superfamily, receptor activator of nuclear factor- kappa B ligand (RANKL), its receptor RANK, and the decoy receptor osteoprotegerin (OPG), have been identified as paracrine mediators of both the immune system and bone functions. The balance of RANK/RANK-L and OPG is critical for osteoclastogenesis modulation and physiological bone remodeling. In order to evaluate whether RANKL/OPG balance is modified by ageing, we analyzed, by imunoassay, systemic levels of OPG and sRANKL in healthy elderly subjects (age range from 70 to over 90 years) and in patients affected by two age-related diseases, osteoarthritis (OA) and polymyalgia rheumatica (PMR), characterized by bone metabolism alteration and involvement of the immune system. We demonstrated that (a) plasma concentrations of OPG increased significantly with age; (b) conversely, sRANKL significantly declined in the group of subjects aged between 81 and 90 years, being similar to the young controls in the other age groups; (c) in OA and PMR, circulating OPG did not differ from plasma levels found in age-matched control groups, while sRANKL concentration was significantly increased compared to controls. Hence, in ageing, the sRANKL/OPG system appears to be modified, with prominent changes in circulating OPG levels; in OA and PMR, the sRANKL/OPG balance alteration was shown to be mainly due to the increase of plasma sRANKL concentration.

Topics: Adult; Aged; Aged, 80 and over; Aging; Carrier Proteins; Female; Glycoproteins; Humans; Immunoassay; Male; Membrane Glycoproteins; Osteoarthritis; Osteoprotegerin; Polymyalgia Rheumatica; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Sex Factors; Statistics as Topic

To evaluate the therapeutic potential of interferon-a (IFN-a) in osteoarthritis (OA) and rheumatoid arthritis (RA) by examining regulation of cytokine antagonist expression.. Expression of interleukin 1 receptor antagonist (IL-1Ra) and soluble tumor necrosis factor receptor (sTNFR) was examined by ELISA in cells from freshly isolated synovial fluids (SF) and synovial tissues (ST) from patients with OA or RA, either left untreated or treated with IFN-a. Single (7) and paired (5) SF and ST cells from OA and RA patients were examined. As well, the ability of IFN-a to regulate gene expression levels for osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL) was examined in freshly isolated SF cells from patients with RA, by reverse transcriptase polymerase chain reaction.. IL-1Ra and sTNFR were found to be constitutively expressed in OA and RA SF and ST cells. IFN-a treatment resulted in an increase in both IL 1Ra and sTNFR production. Freshly isolated RA SF cells exhibited constitutive OPGL gene expression in both the non-T and T cell fractions of the SF. In contrast, OPG gene expression levels were undetectable or low. IFN-a treatment of RA SF cells resulted in upregulation of OPG gene expression in the T cell fraction of the RA SF cells, whereas OPGL gene expression remained unaffected.. These in vitro data suggest a therapeutic role for IFN-a in the treatment of arthritis through upregulation of critical cytokine antagonists.

Topics: Adult; Arthritis, Rheumatoid; Carrier Proteins; Etanercept; Gene Expression; Glycoproteins; Humans; Immunoglobulin G; Immunologic Factors; In Vitro Techniques; Interferon-alpha; Interleukin 1 Receptor Antagonist Protein; Membrane Glycoproteins; Osteoarthritis; Osteoprotegerin; Pilot Projects; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Sialoglycoproteins; Synovial Fluid; Synovial Membrane; Up-Regulation

The aim of this study was to investigate the correlations among the expression of osteoprotegerin (OPG) in synovial tissue and the degree of synovitis, the degeneration of articular cartilage, and the adhesions in patients with internal derangement and osteoarthritis of the temporomandibular joint (TMJ). Study design The expression of OPG, which was detected immunohistochemically, and the degree of arthroscopy of 31 patients with internal derangement and osteoarthritis of the TMJ were assessed and the correlations between them were analyzed statistically.. OPG was expressed in the cytoplasm of the endothelial cells, synovial lining cells, and fibroblast cells. TMJs with osteoarthritis had a higher degree of articular cartilage degeneration than did TMJs with internal derangement. There was a correlation between the expression of OPG in the endothelial cells and the degree of the articular cartilage degeneration (P <.01).. The expression of OPG might be associated with the development of degenerative changes of articular cartilage.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Arthroscopy; Cartilage, Articular; Cytoplasm; Endothelium, Vascular; Female; Fibroblasts; Glycoproteins; Humans; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Statistics, Nonparametric; Synovial Membrane; Synovitis; Temporomandibular Joint Disorders; Tissue Adhesions

The goal of this study was to measure the activities of osteoclastogenesis inhibitory factor/osteoprotegerin (OCIF/OPG), interleukin-1beta (IL-1beta), and tumour necrosis factor-alpha (TNF-alpha) in synovial fluid from 24 patients with internal derangement and 26 with osteoarthritis of the temporomandibular joint (TMJ). Five asymptomatic healthy volunteers were studied as control. Concentrations of OCIF/OPG, IL-1beta, and TNF-alpha were determined by enzyme-linked immunosorbent assay. The mean OCIF/OPG concentration in the patients with osteoarthritis (71 pg/ml) was significantly lower than those in the patients with internal derangement (160 pg/ml, P< 0.05) and the healthy volunteers (196 pg/ml, P< 0.01). In contrast, the IL-1beta and TNF-alpha concentrations were similar in all three groups. These results suggest that OCIF/OPG is associated with the pathogenesis of osteoarthritis of the TMJ. Perhaps, decreased OCIF/OPG concentrations promote osteoclastic activity and induce osteoarthritis of the TMJ.

Topics: Adolescent; Adult; Aged; Child; Female; Glycoproteins; Humans; Interleukin-1; Joint Dislocations; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Synovial Fluid; Temporomandibular Joint Disorders; Tumor Necrosis Factor-alpha

To compare receptor activator of NF-kappaB ligand (RANKL) production in the synovial tissue from patients with active rheumatoid arthritis (RA), inactive RA, spondyloarthropathies (SpA), osteoarthritis, and from normal subjects. In addition, to establish the cell lineages expressing RANKL in these tissues.. Immunohistological analysis of frozen synovial tissue biopsy specimens was performed using a monoclonal antibody (mAb) to detect RANKL. Sections were evaluated by computer assisted image analysis and semiquantitative analysis to compare RANKL expression between groups. Dual and sequential labelling with mAb RANKL and cell lineage specific monoclonal antibodies were used to determine the types of cells expressing RANKL.. Higher levels of RANKL were expressed in tissues from patients with active RA and SpA than in tissues from patients with inactive RA, osteoarthritis, and from normal subjects. RANKL protein was associated with CD3 antigen-positive lymphocytes and some macrophages. RANKL was predominantly associated with activated, memory T cells (CD45Ro positive cells) in patients with active RA and spondyloarthropathy (SpA).. The highest levels of RANKL were detected in patients with RA with active synovitis and in some patients with SpA. An increase in RANKL in the inflamed joint of patients with RA, produced by infiltrating activated T cells and macrophages, is likely to be an important cause of joint erosions in RA.

Topics: Adult; Aged; Arthritis, Rheumatoid; CD3 Complex; Female; Glycoproteins; Humans; Immunoenzyme Techniques; Leukocytes, Mononuclear; Lymphocytes; Macrophages; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Spondylarthropathies; Synovial Fluid

To elucidate the direct role of human T cells in the induction of osteoclastogenesis in rheumatoid arthritis (RA), by studying human monocytes and the pathogenetic roles of receptor activator of nuclear factor kappaB ligand (RANKL), RANK, and osteoprotegerin (OPG).. Synovial tissue obtained at total knee replacement was stained immunohistologically using anti-RANKL, CD3, and CD4 antibodies. Synovial fluid was obtained from patients with RA, osteoarthritis (OA), gout, or trauma. Concentrations of the soluble form of RANKL (sRANKL) and OPG in the synovial fluid were measured by enzyme-linked immunosorbent assay. Activated T cells from peripheral blood mononuclear cells (PBMC) of healthy volunteers were cultured with human monocytes from PBMC.. Immunostaining of the synovial tissue of RA patients demonstrated that RANKL-positive cells were detected in a subset of fibroblast-like synoviocytes and infiltrating mononuclear cells. Double immunostaining revealed that RANKL-positive cells were detected in a subset of CD3+ cells and CD4+ cells. An increased concentration of sRANKL and a decreased concentration of OPG were detected in synovial fluid from RA patients. The ratio of the concentration of sRANKL to that of OPG was significantly higher in synovial fluid of RA patients than in synovial fluid of patients with OA or gout. The activated T cells expressing RANKL induced osteoclastogenesis from autologous peripheral monocytes. The role of RANKL in this osteoclastogenetic process was confirmed by dose-dependent inhibition by OPG.. The present study is the first to demonstrate osteoclastogenesis using human-derived T cells and monocytes. In addition, the present findings suggest that excess production of RANKL by activated T cells increases the level of sRANKL in synovial fluid and may contribute to osteoclastic bone resorption in RA patients.

Topics: Antibodies; Arthritis, Rheumatoid; Carrier Proteins; CD3 Complex; CD4 Antigens; CD4-Positive T-Lymphocytes; Coculture Techniques; Enzyme-Linked Immunosorbent Assay; Female; Gene Expression; Glycoproteins; Gout; Humans; In Situ Hybridization; Lymphocyte Activation; Male; Membrane Glycoproteins; Monocytes; Osteoarthritis; Osteoclasts; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; RNA, Messenger; Synovial Fluid

The determinants of cancellous bone turnover and trabecular structure are not understood in normal bone or skeletal disease. Bone remodeling is initiated by osteoclastic resorption followed by osteoblastic formation of new bone. Receptor activator of nuclear factor kappaB ligand (RANKL) is a newly described regulator of osteoclast formation and function, the activity of which appears to be a balance between interaction with its receptor RANK and with an antagonist binding protein osteoprotegerin (OPG). Therefore, we have examined the relationship between the expression of RANKL, RANK, and OPG and indices of bone structure and turnover in human cancellous bone from the proximal femur. Bone samples were obtained from individuals with osteoarthritis (OA) at joint replacement surgery and from autopsy controls. Histomorphometric analysis of these samples showed that eroded surface (ES/BS) and osteoid surface (OS/BS) were positively associated in both control (p < 0.001) and OA (p < 0.02), indicating that the processes of bone resorption and bone formation remain coupled in OA, as they are in controls. RANKL, OPG, and RANK messenger RNA (mRNA) were abundant in human cancellous bone, with significant differences between control and OA individuals. In coplotting the molecular and histomorphometric data, strong associations were found between the ratio of RANKL/OPG mRNA and the indices of bone turnover (RANKL/OPG vs. ES/BS: r = 0.93, p < 0.001; RANKL/OPG vs. OS/BS: r = 0.80, p < 0.001). These relationships were not evident in trabecular bone from severe OA, suggesting that bone turnover may be regulated differently in this disease. We propose that the effective concentration of RANKL is related causally to bone turnover.

Topics: Adult; Age Factors; Aged; Aged, 80 and over; Bone Remodeling; Carrier Proteins; Case-Control Studies; Female; Femur; Gene Expression; Glycoproteins; Humans; Male; Membrane Glycoproteins; Middle Aged; Osteoarthritis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Reference Values; RNA, Messenger

Rheumatic diseases are often associated with changes in bone metabolism. Excessive production and release of cytokines and other growth factors due to inflammation, e.g. tumor necrosis factor-alpha (TNF-alpha), receptor activator of NF-kappaB ligand (RANKL), interleukins such as IL-1 and IL-6, may cause alterations in bone homeostasis leading to bone degradation. Other components such as osteoprotegerin (OPG) and possibly the ligand-receptor pair hepatocyte growth factor (HGF) and c-met may counteract this destruction, we have measured the levels of OPG, and HGF c-met, in serum, synovial fluid (SF), and cartilage from patients with rheumatoid arthritis (RA) and other arthritides. We found a) elevated levels of both OPG and HGF in SF from RA patients relative to arthritides of other causes, b) increased levels of both OPG and HGF in SF from seropositive RA patients (RA+) compared to seronegative RA patients (RA-), c) elevated levels or both OPG and HGF in serum from RA patients compared to healthy controls, d) no correlation between severity of inflammation and levels of OPG or HGF, and e) presence of HGF c-met in both cartilage and synovial tissue. The most significant elevations of OPG and HGF were found in patients with RA, the rheumatic disease most frequently associated with the development of secondary osteoporosis.

Topics: Adult; Arthritis, Rheumatoid; Cartilage, Articular; Enzyme-Linked Immunosorbent Assay; Female; Fluorescent Antibody Technique, Indirect; Glycoproteins; Hepatocyte Growth Factor; Humans; Male; Middle Aged; Osteoarthritis; Osteoprotegerin; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Spondylitis, Ankylosing; Synovial Fluid

The receptor activator of nuclear factor kappaB (RANK) is a member of the tumor necrosis factor receptor family. It is activated by the secreted or cell surface-bound RANK ligand (RANKL). Osteoprotegerin (OPG) is a soluble nonsignaling receptor for RANKL and interferes with RANK activation. This receptor-ligand system regulates the differentiation of osteoclasts and dendritic cells. The present study examined human articular cartilage for the expression of these molecules and the role of RANKL in the regulation of chondrocyte function.. Normal and osteoarthritic (OA) human articular cartilage was used for explant tissue culture or for isolation of chondrocytes and cell culture. Expression of RANK, RANKL, and OPG was analyzed by immunohistochemistry, Western blotting, or reverse transcription-polymerase chain reaction. Recombinant RANKL was added to cartilage or chondrocyte cultures, and gene expression, collagenase and nitric oxide production, and NF-kappaB activation were determined.. RANK, RANKL, and OPG messenger RNA (mRNA) were expressed in normal cartilage. By immunohistochemistry, RANK, RANKL, and OPG were detected in the superficial zone of normal cartilage. OA cartilage contained increased levels of OPG mRNA, and expression of the 3 proteins extended into the midzone of OA cartilage. OPG was detected by Western blotting, and was increased in response to interleukin-1beta stimulation. OPG, RANK, and RANKL protein were also detected in cultured chondrocytes. Addition of exogenous RANKL did not activate NF-kappaB, induce expression of genes encoding proinflammatory mediators in chondrocytes, or stimulate the production of collagenase and nitric oxide.. These results demonstrate the expression of OPG, RANK, and RANKL in cartilage. However, RANKL does not activate human articular chondrocytes.

Topics: Carrier Proteins; Cartilage, Articular; Cells, Cultured; Chemokine CCL5; Chondrocytes; Collagenases; Cyclooxygenase 2; Gene Expression; Glycoproteins; Humans; Interleukin-1; Interleukin-6; Isoenzymes; Membrane Glycoproteins; Membrane Proteins; NF-kappa B; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Osteoarthritis; Osteoprotegerin; Prostaglandin-Endoperoxide Synthases; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; RNA, Messenger; Signal Transduction; Tumor Necrosis Factor-alpha