Analysis of synovial fluid components of hydrarthrosis in long-term hemodialysis patients

The synovial fluid components in long-term hemodialysis patients (HD; 43 knees in 43 patients) were investigated and compared with those in patients with osteoarthritis (OA; 21 knees in 21 patients) and rheumatoid arthritis (RA; 26 knees in 26 patients). The average ages in the three groups were, respectively, 60.7 years (range, 34–79 years), 63.2 years (range, 48–88 years), and 59.7 years (range, 37–76 years). The duration of hemodialysis in the HD group averaged 14.0 years (range, 4–24 years). The concentrations of hyaluronic acid, protein, and isomers of chondroitin sulfate (chondroitin 6-sulfate [C6S] and chondroitin 4-sulfate [C4S]) in the synovial fluid, and its viscosity were measured. Differences in each of the parameters were investigated according to disease clinical stage, roentgenological grade, and periods of dialysis in the HD group. The viscosity of the synovial fluid and the concentration of hyaluronic acid in HD patients were similar to those in OA patients; however, the C6S/C4S ratio in the synovial fluid of HD patients was similar to that in RA patients. The latter finding suggests that synovitis may be present in the hydrarthrosis of HD patients. The cause of this synovitis in HD patients remains to be elucidated. Received for publication Feb. 19, 1998; accepted on July 29, 1998     

Quantitation of chondroitin-sulfates, disaccharides and hyaluronan in normal, early and advanced osteoarthritic sheep temporomandibular joints

OBJECTIVE: To determine the relationship between synovial fluid, chondroitin sulfate disaccharide and hyaluronic acid to differing degrees of experimental temporomandibular joint (TMJ) osteoarthritis (OA). DESIGN: Twenty-four merino sheep were divided into three groups and had different TMJ surgical procedures to produce OA. Group I; control (six sheep), Group II; disc perforation (nine sheep) and Group III; disc perforation and articular damage (nine sheep). Synovial fluid was collected initially and at sacrifice at 3 months. Chondroitin 4-sulfate, chondroitin 6-sulfate and hyaluronic acid were measured and correlated to the OA histologic score. RESULTS: The chondroitin-sulfate levels were significantly increased (Group I to Group II P< 0.001; Group I to Group III P< 0.001), the hyaluronic acid levels decreased (Group I to Group II P< 0.01; Group I to Group III P< 0.01) with the increasing OA score. CONCLUSION: Chondroitin-sulfate and hyaluronic acid show a correlation with surgically created TMJ osteoarthritis in sheep model.     

Osteoarthritis synovial fluid activates pro-inflammatory cytokines in primary human chondrocytes

Purpose

Two of the most common joint diseases are rheumatoid arthritis (RA) and osteoarthritis (OA). Cartilage degradation and erosions are important pathogenetic mechanisms in both joint diseases and have presently gained increasing interest. The aim of the present study was to investigate the effects of the synovial fluid environment of OA patients in comparison with synovial fluids of RA patients on human chondrocytes in vitro.

Methods

Primary human chondrocytes were incubated in synovial fluids gained from patients with OA or RA. The detection of vital cell numbers was determined by histology and by using the Casy Cell Counter System. Cytokine and chemokine secretion was determined by a multiplex suspension array.

Results

Microscopic analysis showed altered cell morphology and cell shrinkage following incubation with synovial fluid of RA patients. Detection of vital cells showed a highly significant decrease of vital chondrocyte when treated with RA synovial fluids in comparison with OA synovial fluids. An active secretion of cytokines such as vascular endothelial growth factor (VEGF) of chondrocytes treated with OA synovial fluids was observed.

Conclusions

Significantly increased levels of various cytokines in synovial fluids of RA, and surprisingly of OA, patients were shown. Activation of pro-inflammatory cytokines of human chondrocytes by synovial fluids of OA patient supports a pro-inflammatory process in the pathogenesis of OA.     

Intra-articular hyaluronic acid in osteoarthritis of the knee: an investigation into mechanisms of action

The objective of this study was to investigate mechanisms of action of intra-articular hyaluronic acid in osteoarthritis (OA) of the knee. Twelve patients with bilateral knee OA and synovial effusions entered a randomized, single-blind, blind observer study. Hyaluronic acid ("Hyalgan", Fidia SpA, Italy) or placebo were given by intra-articular injection weekly for 5 weeks. Assessments included clinical indices and imaging (magnetic resonance imaging (MRI) and 99m Tc bone scanning) before and after the course of injections. In addition, synovial fluid keratan sulfate (KS), chondroitin sulfate (CS) and C-propeptide of type II collagen (CPII) were measured. MRI and 99m Tc scanning showed no change in either treated or placebo knees over the 6-week study period. A fall in KS levels occurred in treated knees compared with placebo (Wilcoxon paired test, P = 0.1), although this did not reach significance perhaps due to small sample numbers). Ten out of 12 treated knees showed a fall in KS, compared with four out of 12 placebo knees. CS and CPII levels did not change significantly. Intra-articular injection of hyaluronic acid did not result in any improvement in the clinical indices compared to the placebo. In conclusion, assessment of cartilage markers may be of value when studying novel therapies in OA. MRI appearances remain remarkably stable over a 6-week period.     

骨性关节病与磷脂酶A2关系的研究

目的　探讨磷脂酶A2 (APLA2 ) ,前列腺素E2 (PGE2 ) ,PH在骨性关节病 (OA)中的作用及关节液中PLA2 与PGE2 的关系。方法　抽取 2 8例OA患者 ,14例对照者膝关节液 ,采用酶联免疫法测定PGE2 ,生物活性法测定PLA2 ,用 5 80 0 - 0 5溶液分析仪测定PH值。结果　OA组PLA2 活性高于对照组 (P <0 0 0 1) ;OA组PGE2 含量高于对照组 (P <0 0 0 1) ;OA组PH值低于对照组 (P <0 0 5 ) ;PLA2 活性与疼痛程度 ,病情评分呈正相关 (P <0 0 0 1) ;PLA2 活性与PGE2 含量呈正相关 (P <0 0 0 1)。     

1H NMR investigation of changes in the metabolic profile of synovial fluid in bilateral canine osteoarthritis with unilateral joint denervation

OBJECTIVE: High resolution 1H-nuclear magnetic resonance (NMR) techniques have been used to compare the effects of unilateral knee-joint denervation on the biochemical profiles of synovial fluid in a bilateral canine model of osteoarthritis. METHOD: Paired synovial fluid samples were obtained from seven dogs all of which had previously undergone bilateral anterior cruciate ligament transection, unilateral knee denervation and contralateral sham nerve exposure. All synovial fluid samples were then analyzed using 500 MHz 1H-CPMG spin-echo NMR Spectroscopy to assess differences in endogenous metabolite levels between the paired fluids. RESULTS: The results indicate statistically significant increases in glycerol, hydroxybutyrate, glutamine/glutamate, creatinine/creatine, acetate and N-acetyl-glycoprotein concentrations in synovial fluids from denervated with respect to control knees. Furthermore, significant trends towards elevated lactate, alanine and pyruvate levels in the denervated knee fluids are consistent with our previous findings comparing NMR spectroscopy metabolic profiles of normal and osteoarthritic canine synovial fluids. CONCLUSION: This study lends support to the principle of neurogenic acceleration of OA in that the observed differences in metabolite concentrations found in the denervated knee fluids seem to correlate with metabolic changes resulting from aggravation of the OA process caused by joint denervation.     

Hyaluronic acid in flexor tendon sheath fluid after sheath reconstructions in rabbits. A comparison between tendon sheath transplantation and conventional two stage procedures

Because the synovial environment has been suggested to be important in limiting the number of postoperative adhesions after flexor tendon surgery, and a high concentration of hyaluronic acid is a characteristic feature of synovial fluid, we have examined the hyaluronic acid concentrations in fluid collected from different kinds of reconstructed flexor tendon sheaths in rabbits. The hyaluronic acid concentration in normal rabbit flexor tendon sheaths was similar to that in normal human sheath and joint fluid. Rabbit tendon sheaths restored by autologous sheath grafts and partial pseudosheaths contained similar or somewhat lower hyaluronic acid concentrations, whereas in complete pseudosheaths the concentrations were considerably lower. The data suggest that tendon sheath reconstructions should consist at least partly of synovial membrane so that they are as similar as possible to normal synovial membrane.     

Levels of chondroitin sulfate isomers in synovial fluid of patients with hip osteoarthritis

We determined the levels of chondroitin sulfate (CS) isomers in the synovial fluid of patients with hip osteoarthritis (OA) to investigate their significance as markers reflecting extracellular matrix metabolism in joint tissues. A cross-sectional study of synovial fluid aspirated from 50 hip joints of 50 patients with OA was performed. Concentrations of chondroitin-4-sulfate (C4S) and chondroitin-6-sulfate (C6S) were determined by high-performance liquid chromatography. Levels of each marker molecule were investigated in relation to age and radiological stage of the disease. In all disease stages, the dominant CS isomer in synovial fluid was C6S. There was a significant negative correlation between levels of C6S and age. A significant inverse correlation was also observed between the ratio of C6S to C4S and age. Results of analysis of covariance in which age was covariate showed that the ratio of C6S to C4S in advanced and terminal stage OA was lower than that in early stage OA. The present results indicate that the ratio of CS isomers in synovial fluid in hip OA varies with the severity of disease. These molecules in synovial fluid may serve as a useful marker reflecting extracellular matrix metabolism in OA. Received for publication on May 13, 1998; accepted on Dec. 17, 1998     

The role of protein and hyaluronic acid in the synovial fluid in animal joint lubrication

The purpose of this investigation was to study the role of protein and hyaluronic acid of synovial fluid in the animal joint lubrication. The D-fraction (0.2 micron up to 0.8 micron) from the bovine synovial fluid showed the lowest friction coefficient and contained about 20% protein and 70% hyaluronic acid of the synovial fluid. Protein but not hyaluronic acid of this fraction had lubricating ability, and the protein but not hyaluronic acid could support the lubricating film thickness. By electron microscopic observation hyaluronic acid was 2,000A-5,000A formless mass and the protein complex that had lubricating ability was 200A-300A spherical particle. Through these results I presume that hyaluronic acid enclose the spherical protein particles in its network like a cage of the roller-bearing and the particles can rotate freely like rolling elements of the roller-bearing. It was suggested that the roller-bearing mechanism was performed along with elastohydrodynamic lubrication in animal joint.     

Synovial fluid features and their relations to osteoarthritis severity: new findings from sequential studies

OBJECTIVE: Many factors are involved in the osteoarthritic process. It is not yet known which are initiators, promoters or simply results. Thus, we have evaluated some of those potentially important factors in osteoarthritis (OA) as observed sequentially for the first time in synovial fluids. DESIGN: Synovial fluids (SF) obtained between 1992-2002 were all routinely evaluated for gross appearance, leukocyte counts and microscopic examination of wet drop preparations. We used regular and polarized light and alizarin red s stains. We separated out all OA patients, then we looked for patients who had more than two synovial fluid analyses to get sequential information. Time between first and final aspiration ranged from 2 to 7 (3.6+/-1.6) years and number of analyses per patients from 3 to 6 (3.3+/-0.7). We related synovial fluid crystals, fibrils and white blood cell count (WBC) to age, sex, disease duration and radiographic assessment according to the Kellgren-Lawrence radiographic rating system. RESULTS: Of 4523 synovial fluid examinations, we found 855 in patients with knee OA; 330 patients with adequate clinical details for comparison were included in our study. Twenty-six patients (one woman and 25 men) had sequentially examined SF. We found that 52% of those OA patients with effusions studied had crystals identified in their synovial fluid. Twenty-one percent of all the patients had CPPD crystals, 47% had hydroxyapatite, also called basic calcium phosphate (BCP) crystals and 16% had both types of crystals. Microscopically identifiable fibrils were found in 60% of SF.In sequentially examined patients, CPPD crystals and apatite (BCP) were found in 19% and 23%, respectively, at the first aspiration and, in 34% and 58% at the final aspiration. Fibrils were seen in 54% at first examination and 85% later. Apatite and fibrils showed more significant correlation with time (r=0.51,r =0.92) than did CPPD (r=0.32). SF WBC correlated only with CPPD crystals and did not increase with OA duration or severity. CPPD, apatite and fibrils all correlated with higher radiographic grades of OA. CONCLUSIONS: As noted before CPPD and apatite crystals were more common in patients with more severe OA. New findings are that our sequential cases showed that there were some patients with no crystals at onset but that crystals appeared with progression of the disease. Fibril presence in SF also correlated with progression of the disease.     

Complement C3-α and C3-β Levels in Synovial Fluid But Not in Blood Correlate With the Severity of Osteoarthritis Research Society International Histopathological Grades in Primary Knee Osteoarthritis

BackgroundPrimary osteoarthritis (OA) is the most common cause of knee arthritis worldwide. The knee synovial fluid complement C3-β chain levels have been shown to correlate with clinical symptoms of knee OA. It is not known whether the complement C3 in the synovial fluid is derived from the circulation or is produced locally in the knee.MethodsFifty primary OA patients undergoing a total knee arthroplasty procedure were evaluated for biochemical analyses of C3-α and C3-β chains in the synovial fluid and blood plasma. These levels were corelated with the severity of corresponding knee OA based on the Osteoarthritis Research Society International (OARSI) grade.ResultsBoth synovial C3-α and C3-β levels correlated significantly with the severity of OA. Neither plasma C3-α levels nor C3-β levels significantly correlated with OARSI grading. Neither synovial C3-α levels nor C3-β correlated significantly with plasma C3-α or C3-β levels, respectively. Synovial C3-α chain and C3-β chain levels were significantly higher in the grade >6 group. In plasma, neither C3-α chain levels nor C3-β chain levels were significantly different between the groups. Neither synovial C3-α nor C3-β levels significantly correlated with plasma erythrocyte sedimentation rate or C-reactive protein levels.ConclusionIn knee primary OA, C3 seems to be produced and released locally into the synovial fluid instead of being derived from blood in the circulation. Synovial C3 levels, but not blood plasma C3, correlate with the histopathological severity of primary OA in the knee. Synovial C3 may be an important factor in the pathogenesis of primary OA clinical symptoms and a potential target for therapeutic intervention.     

Amniotic Suspension Allograft Modulates Inflammation in a Rat Pain Model of Osteoarthritis

Osteoarthritis (OA) affects over 301 million adults worldwide. Inflammation is a recognized component of the OA process; two potent pro-inflammatory cytokines involved in OA are interleukin-1β and tumor necrosis factor-α. Placental-derived tissues and fluids are known to contain anti-inflammatory and immunomodulatory cytokines and growth factors. The objective of this study was to evaluate the anti-inflammatory effects of amniotic suspension allograft (ASA) in an in vivo model of OA; we evaluated pain, function, and cytokine levels following ASA treatment in the rat monosodium iodoacetate (MIA) OA pain model. Rats were injected with 2 mg of MIA, which causes pain, cartilage degeneration, and inflammation, followed by treatment with saline, triamcinolone (positive control), or ASA 7 days following disease induction with MIA. Behavioral assays, including gait analysis, mechanical pain threshold, incapacitance, and swelling were evaluated, along with histology and serum and synovial fluid biomarkers. Treatment with ASA resulted in significant improvements in pain threshold, while weight bearing aversion and swelling were significantly decreased. There were no differences between groups in total joint score after histological grading. Serum biomarkers did not show differences, indicating a lack of systemic response; however, synovial fluid levels of IL-10 were significantly increased in animals treated with ASA. ASA treatment significantly reduced pain, weight-bearing aversion and swelling. This study provides mechanistic data regarding potential therapeutic effects of ASA in OA and preliminary evidence of the anti-inflammatory nature of ASA. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1141-1149, 2020     

Comparison of differential biomarkers of osteoarthritis with and without posttraumatic injury in the Hartley guinea pig model

The objective was to compare biomarkers of articular cartilage metabolism in synovial fluid from Hartley guinea pig knees, with and without anterior cruciate ligament transection (ACLT), to establish whether detectable differences in biomarker levels exist between primary and secondary osteoarthritis (OA). Synovial fluid lavages and knees were obtained from 3‐month (control group) and 12‐month (primary OA group) animals. Another group of animals (posttraumatic OA group) underwent unilateral ACLT at 3 months, and samples were obtained 9 months postsurgery. Synovial fluid concentrations of stromal cell‐derived‐factor (SDF‐1), collagen fragments (C2C), proteoglycan (GAG), lubricin, matrix metalloproteinase‐13 (MMP‐13), and Interleukin‐1 (IL‐1β) were evaluated. Cartilage damage was assessed via histology. The highest concentrations of C2C and SDF‐1 in synovial fluid were found in the posttraumatic OA group, moderate concentrations were found in the primary OA group, and low concentrations in the control group. GAG release in synovial fluid was similar to C2C and SDF‐1. The lubricin concentrations were significantly lower in ACLT joints than either the control or 12‐month primary OA groups, but not between the control and primary OA groups. Higher levels of MMP‐13 and IL‐1β were detected in the joints of the posttraumatic OA group as compared to the control or primary OA groups. Histology revealed greatest OA damage in the posttraumatic OA group, followed by moderate and minimal damage in primary OA and control groups, respectively. This study indicates that the biomarkers and progression of OA may differ in the Hartley guinea pig models with and without posttraumatic OA. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:900–906, 2010     

白细胞介素1β、肿瘤坏死因子α在膝关节原发性骨关节病发病中的作用

目的探讨白细胞介素１β（ＩＬ－１β）、肿瘤坏死因子α（ＴＮＦ－α）在膝关节原发性骨关节病（ＯＡ）发病中的作用。方法提取１６例ＯＡ患者（ＯＡ组）、５例对照者（非ＯＡ组）的关节液,采用酶联免疫吸附法（ＥＬＩＳＡ法）测定ＩＬ－１β,生物活性法（ＭＴＴ法）检测ＴＮＦ－α的水平。结果在ＯＡ组关节滑液中,ＩＬ－１β的水平均显著高于对照组（Ｐ＜０００１）;对照组的ＴＮＦ－α未能测出,而ＯＡ组ＴＮＦ－α的检出阳性率为２５％。其次,为进一步探讨滑液中上述细胞因子的产生来源,传代培养膝关节滑膜细胞并用脂多糖（ＬＰＳ）刺激,ＯＡ组（２０例）关节滑膜细胞自发分泌ＩＬ－１β的水平显著高于对照组（５例）,Ｐ＜００５;ＬＰＳ刺激的条件下,ＯＡ组和对照组分泌ＩＬ－１β均显著升高,尤以ＯＡ组为著（Ｐ＜０００１）;ＴＮＦ－α在ＯＡ组中仅有两例呈阳性,对照组中均为阴性。结论ＩＬ－１β和ＴＮＦ－α在骨关节病的发病中起重要作用。ＯＡ患者滑膜细胞高水平自发性分泌ＩＬ－１β可能与其炎症发生与发展密切相关,可能是关节滑液中ＩＬ－１β的主要来源,而滑膜细胞分泌ＴＮＦ－ａ可能不是关节滑液中的主要来源。     

Matrix metalloproteinase protein expression profiles cannot distinguish between normal and early osteoarthritic synovial fluid

ABSTRACT: BACKGROUND: Osteoarthritis (OA) and Rheumatoid arthritis (RA) are diseases which result in the degeneration of the joint surface articular cartilage. Matrix Metalloproteinases (MMPs) are enzymes that aid in the natural remodelling of tissues throughout the body including cartilage. However, some MMPs have been implicated in the progression of OA and RA as their expression levels and activation states can change dramatically with the onset of disease. Yet, it remains unknown if normal and arthritic joints demonstrate unique MMPs expression profiles, and if so, can the MMP expression profile be used to identify patients with early OA. In this study, the synovial fluid protein expression levels for MMPs 1, 2, 3, 7, 8, 9, 12 & 13, as well as those for the Tissue Inhibitors of MMPs (TIMPs) 1, 2, 3, & 4 were examined in highly characterized normal knee joints, and knee joints with clinically diagnosed OA (early and advanced) or RA. The purpose of this study was to determine if normal, OA, and RA patients exhibit unique expression profiles for a sub-set of MMPs, and if early OA patients have a unique MMP expression profile that could be used as an early diagnostic marker. METHODS: Synovial fluid was aspirated from stringently characterized normal knee joints, and in joints diagnosed with either OA (early and advanced) or RA. Multiplexing technology was employed to quantify protein expression levels for 8 MMPs and 4 TIMPs in the synovial fluid of 12 patients with early OA, 17 patients diagnosed with advanced OA, 15 with RA and 25 normal knee joints. Principle component analysis (PCA) was used to reveal which MMPs were most influential in the distinction between treatment groups. K - means clustering was used to verify the visual grouping of subjects via PCA. RESULTS: Significant differences in the expression levels of MMPs and TIMPs were observed between normal and arthritic synovial fluids (with the exception of MMP 12). PCA demonstrated that MMPs 2, 8 & 9 can be used to effectively separate individuals diagnosed with advanced arthritis from early osteoarthritic and normal individuals, however, these MMP profiles do not separate early OA from normal synovial fluid. An apparent separation between advanced OA and RA subjects was also revealed through PCA. K-means clustering verified the presence of 3 clusters: normal joints clustered with early OA, and separate clusters of advanced OA or RA. CONCLUSIONS: This study demonstrates that unique MMP and TIMP expression profiles are present within normal, advanced OA and RA synovial fluid. These MMP profiles can be used to distinguish advanced OA & RA synovial fluid from early OA & normal synovial fluid, and even between synovial fluid samples from OA and RA joints. Although this methodology cannot be used for the diagnosis of early OA, high throughput multiplex technology of MMPs and TIMPs in synovial fluid may prove useful in determining the severity of the disease state, and/or quantifying the response of individuals to disease interventions.     

Localization of hyaluronan in pseudocapsule from total hip arthroplasty.

Hyaluronan is a large glycosaminoglycan present in normal synovial fluid imparting important viscoelastic properties for joint lubrication. In normal and noninflammatory conditions, hyaluronan has been localized to the lining layer of the synovial membrane, specifically synovial fibroblasts. Prosthetic joint fluid contains large amounts of hyaluronan, the source of which has not been determined. Pseudocapsules from patients who had total hip arthroplasty and were having revision surgery for nonloosened and nonseptic conditions were fixed in 10% acid formalin with 70% alcohol and stained for hyaluronic acid with biotinylated hyaluronic acid binding protein as a probe. Hyaluronan was localized strongly to the lining layer of the pseudocapsule, as in normal and osteoarthritic synovial membranes. The fibroblasts in the pseudocapsule of total hip arthroplasty may be responsible for the persistent production of hyaluronan in prosthetic joint fluid.     

CCL25‐Supplemented Hyaluronic Acid Attenuates Cartilage Degeneration in a Guinea Pig Model of Knee Osteoarthritis

There is evidence that the application of mesenchymal stromal cells (MSCs) counteracts osteoarthritis (OA) progression. However, the prospect of extracting and expanding these cells might be limited. The aim of this study was to investigate whether hyaluronic acid (HA) supplemented with MSC‐recruiting chemokine C‐C motif ligand 25 (CCL25) can influence the natural course of spontaneous OA in the guinea pig. CCL25 concentration in synovial fluid (SF) was quantified with enzyme‐linked immunosorbent assay. Boyden chamber cell migration assay was used to test CCL25‐mediated migration of guinea pig MSC. Forty‐nine 11‐month‐old male guinea pigs were divided into seven groups. The main treatments consisted of five intra‐articular injections of HA in pure form and in combination with three doses of CCL25 (63, 693, and 6,993 pg) given at a weekly interval. The severity of cartilage damage was assessed by using a modified Mankin score. The measured average physiological concentration of CCL25 in SF of animals is 85 ± 39 pg/ml. MSC showed a 3.2‐fold increase in cell migration at 1,000 nM CCL25 in vitro demonstrating the biological migratory activity of CCL25 on these cells. In vivo, treatment with HA alone did not reduce OA progression. Similarly, OA scores were not found significantly reduced after treatment with 63 pg CCL25 + HA. However, when compared to pure HA, treatment with 693 pg CCL25 + HA and 6,993 pg CCL25 + HA significantly reduced the OA score from 10.1 to 7.4 (?28%) and 8.4 (?20%), respectively. These data suggest that intra‐articular injections of HA supplemented with CCL25 attenuates OA. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1723–1729, 2019     

Global and targeted metabolomics of synovial fluid discovers special osteoarthritis metabolites

To identify special metabolites in synovial fluid of osteoarthritis (OA) via a metabolomics approach. Synovial fluid of 35 participants (25 OA patients and 10 controls) was detected by GC‐TOF/MS and multivariate data analysis was applied to analyze correlation among the observations. Different metabolites were screened by VIP value (VIP > 1), student t‐test (p < 0.05), and fold change (fold >1.5), and verified with the standard metabolites in the synovial fluid of 24 OA patients and 11 controls by LC/MS. The classification performance of different metabolites was analyzed by receiver operating characteristic (ROC) analysis. The results showed that six different metabolites (glutamine, 1,5‐anhydroglucitol, gluconic lactone, tyramine, threonine, and 8‐aminocaprylic acid) were strongly associated with OA in global metabolomics. Verified results of the first three metabolites were the same as the identified results using targeted metabolomics. ROC curve analysis demonstrated that their concentrations in synovial fluid were strongly correlated to OA. In addition, the concentrations of gluconic lactone were significantly different between OA and RA. Metabolites with altered levels may be contributors to OA pathogenesis and can be used as potential diagnosis criteria for OA. Gluconic lactone may prove to be a novel criterion for differential diagnosis of OA from RA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1973–1981, 2017.

     

Changes in gait after bilateral meniscectomy in sheep: effect of two hyaluronan preparations

Background  This study examined the effect of bilateral meniscectomy on ground reaction forces (GRFs) in sheep, and the therapeutic effect of two hyaluronan (HA) preparations. Methods  Eighteen sheep were subjected to bilateral lateral meniscectomy and were treated from 16 to 20 weeks postoperatively with intraarticular Hyalgan (Fidia Farmaceutici), HYADD4-G (a novel amide derivative; Fidia Farmaceutici), or saline placebo (n = 6 per group). GRFs were assessed at baseline and 6, 12, 16, 22, and 26 weeks postoperatively. Rheological parameters and HA content of synovial fluid samples were assessed using micro-Fourier rheometry. Results  Meniscectomy significantly reduced GRF and abolished the normal two-peak vector. GRF deficits were partially ameliorated by both HA preparations: Hyalgan increased peak vertical forces at 6 weeks post-treatment (week 22), while HYADD4-G increased vertical impulse post-treatment. Both HA treatments, but not saline placebo, restored a twopeak composite force vector at 6 weeks post-treatment. Neither HA preparation significantly modulated osteoarthritis (OA) severity, or synovial fluid parameters. Conclusions  This study showed that GRF responses to bilateral meniscectomy in sheep mimic available data for human meniscectomy and OA patients. However, this time course suggests that gait deficits are temporally unrelated to observed cartilage or synovial fluid changes. The bilateral ovine meniscectomy model demonstrates modest but quantifiable changes in GRF that mimic human OA and are amenable to modification by known OA therapies such as HA.     

Prevalence and consequences of musculoskeletal symptoms in symphony orchestra musicians vary by gender: a cross-sectional study

Background

Tenascin-C (TN-C) is an extracellular matrix glycoprotein that is involved in tissue injury and repair processes. We analyzed TN-C expression in normal and osteoarthritic (OA) human cartilage, and evaluated its capacity to induce inflammatory and catabolic mediators in chondrocytes in vitro. The effect of TN-C on proteoglycan loss from articular cartilage in culture was also assessed.

Methods

TN-C in culture media, cartilage extracts, and synovial fluid of human and animal joints was quantified using a sandwich ELISA and/or analyzed by Western immunoblotting. mRNA expression of TN-C and aggrecanases were analyzed by Taqman assays. Human and bovine primary chondrocytes and/or explant culture systems were utilized to study TN-C induced inflammatory or catabolic mediators and proteoglycan loss. Total proteoglycan and aggrecanase -generated ARG-aggrecan fragments were quantified in human and rat synovial fluids by ELISA.

Results

TN-C protein and mRNA expression were significantly upregulated in OA cartilage with a concomitant elevation of TN-C levels in the synovial fluid of OA patients. IL-1 enhanced TN-C expression in articular cartilage. Addition of TN-C induced IL-6, PGE₂, and nitrate release and upregulated ADAMTS4 mRNA in cultured primary human and bovine chondrocytes. TN-C treatment resulted in an increased loss of proteoglycan from cartilage explants in culture. A correlation was observed between TN-C and aggrecanase generated ARG-aggrecan fragment levels in the synovial fluid of human OA joints and in the lavage of rat joints that underwent surgical induction of OA.

Conclusions

TN-C expression in the knee cartilage and TN-C levels measured in the synovial fluid are significantly enhanced in OA patients. Our findings suggest that the elevated levels of TN-C could induce inflammatory mediators and promote matrix degradation in OA joints.