Pathological Synovial Fluids Research Articles

Synovial Fluid Regulates the Gene Expression of a Pattern of microRNA via the NF-κB Pathway: An In Vitro Study on Human Osteoarthritic Chondrocytes.

Synovial fluid (SF) represents the primary source of nutrients of articular cartilage and is implicated in maintaining cartilage metabolism. We investigated the effects of SF, from patients with osteoarthritis (OA), rheumatoid arthritis (RA), and controls, on a pattern of microRNA (miRNA) in human OA chondrocytes. Cells were stimulated with 50% or 100% SF for 24 h and 48 h. Apoptosis and superoxide anion production were detected by cytometry; miRNA (34a, 146a, 155, 181a), cytokines, metalloproteinases (MMPs), type II collagen (Col2a1), antioxidant enzymes, B-cell lymphoma (BCL)2, and nuclear factor (NF)-κB by real-time PCR. The implication of the NF-κB pathway was assessed by the use of NF-κB inhibitor (BAY-11-7082). RA and OA SF up-regulated miR-34a, -146a, -155, -181a, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, MMP-1, MMP-13, and ADAMTs-5 gene expression, while it down-regulated Col2a1. Pathological SF also induced apoptosis, reduced viability, and decreased BCL2 mRNA, whereas it increased superoxide anions, the expression of antioxidant enzymes, p65 and p50 NF-κB. Opposite and positive results were obtained with 100% control SF. Pre-incubation with BAY-11-7082 counteracted SF effects on miRNA. We highlight the role of the SF microenvironment in regulating some miRNA involved in inflammation and cartilage degradation during OA and RA, via the NF-κB pathway.

CLINICAL AND LABORATORY EXAMINATION OF SYNOVIAL FLUID IN THE JOINT DISEASES DIAGNOSTICS. PART 2

The review presents novel insight on the cells of normal and pathological synovial fluid (SF) which detected by light microscopy, as well as the diagnostic value of some biochemical markers of SF which can help in the differential diagnosis of diseases musculoskeletal system [1]. Early diagnosis will help to start timely treatment at the primary stages of the disease. The clinical lecture notes the pathway for standardization of laboratory procedures in SF examination в for conventional practice of medical lab in Russia.

Computational study on synovial fluid flow behaviour in cartilage contact gap under osteoarthritic condition

This study numerically investigates the pathological changes of fluid flow in cartilage contact gap due to the changes in cartilage surface roughness and synovial fluid characteristics in osteoarthritic (OA) condition. First, cartilage surface topographies in both healthy and OA conditions are constructed using a numerical approach with consideration of both vertical and horizontal roughness. Then, constitutive equations for synovial fluid viscosity are obtained through calibration against previous experimental data. Finally, the roughness and synovial fluid information are input into the gap flow model to predict the gap permeability. The results show that the rougher surface of OA cartilage tends to decrease gap permeability by around 30%–60%. More importantly, with the reduction in gap size, the decrease in gap permeability becomes more significant, which could result in an early fluid ultrafiltration into the tissue. Moreover, it is demonstrated that the pathological synovial fluid has more deleterious effects on the gap permeability than the OA cartilage surface, as it could potentially increase the gap permeability by a few hundred times for pressure gradients less than 106 Pa/m, which could inhibit the fluid ultrafiltration into the tissue. The outcomes from this research indicate that the change in fluid flow behaviour in contact gap in OA condition could significantly affect the function of articular joints.

Distinct tribological endotypes of pathological human synovial fluid reveal characteristic biomarkers and variation in efficacy of viscosupplementation at reducing local strains in articular cartilage

Viscosupplementation has been used for decades to treat mild to moderate osteoarthritis, yet it is unknown if the lubricating function of different pathological synovial fluids (SF) vary, or if they respond differentially to viscosupplementation. The objectives of this study were to (i) evaluate the friction coefficients and induced shear strains in articular cartilage when lubricated with pathological SF, (ii) identify the effect of hyaluronic acid (HA) supplementation on friction coefficients and shear strains, and (iii) identify SF biomarkers that correlate with lubricating function. Human pathological SF was grouped by white blood cell count (inflammatory: >2000cells/mm3, n=6; non-inflammatory: <2000cells/mm3, n=6). Compositional analyses for lubricin and cytokines were performed. Friction coefficients and local tissue shear strain measurements were coupled using new, microscale rheological analyses by lubricating neonatal bovine cartilage explants with SF alone and in a 1:1 ratio with HA (Hymovis®). Friction coefficients were not significantly different between the inflammatory and non-inflammatory pathologies (p=0.09), and were poorly correlated with peak tissue strains at the cartilage articular surface (R2=0.34). A subset of inflammatory SF samples induced higher tissue strains, and HA supplementation was most effective at lowering friction and tissue strains in this inflammatory subset. Across all pathologies there were clear relationships between polymorphonuclear neutrophil (PMN), IL-8, and lubricin concentrations with cartilage tissue strains. These results suggest that pathological SF is characterized by distinct tribological endotypes where SF lubricating behaviors are differentially modified by viscosupplementation and are identifiable by biomarkers.

Anomalous Behavior of Hyaluronan Crosslinking Due to the Presence of Excess Phospholipids in the Articular Cartilage System of Osteoarthritis.

Lubrication of articular cartilage is a complex multiscale phenomenon in synovial joint organ systems. In these systems, synovial fluid properties result from synergistic interactions between a variety of molecular constituent. Two molecular classes in particular are of importance in understanding lubrication mechanisms: hyaluronic acid and phospholipids. The purpose of this study is to evaluate interactions between hyaluronic acid and phospholipids at various functionality levels during normal and pathological synovial fluid conditions. Molecular dynamic simulations of hyaluronic acid and phospholipids complexes were performed with the concentration of hyaluronic acid set at a constant value for two organizational forms, extended (normal) and coiled (pathologic). The results demonstrated that phospholipids affect the crosslinking mechanisms of hyaluronic acid significantly and the influence is higher during pathological conditions. During normal conditions, hyaluronic acid and phospholipid interactions seem to have no competing mechanism to that of the interaction between hyaluronic acid to hyaluronic acid. On the other hand, the structures formed under pathologic conditions were highly affected by phospholipid concentration.

Efficacy of Physical Therapy in the Treatment of Gonarthrosis in Physically Burdened Working Men

Introduction:Gonarthrosis is most frequently defined as the change involving damage of the articular cartilage of the knee joint, emergence of abnormal knee tissue, reactive changes in synovial membrane, and pathological synovial fluid. The site of initial damage most often remains unknown. Goal of the researchThe goal:The goal of this research is to demonstrate the efficacy of individual physical therapy during the medical treatment for gonarthrosis in the working population engaged in physical labour, and to compare the state of pain and mobility before and after the treatment.Subjects and research methods:The research encompassed 30 subjects diagnosed with gonarthrosis, and it was conducted in the Institute of Occupational Health and Sports Medicine of the Zenica-Doboj Canton. On the basis of the applied physical treatments, we divided the subjects into control group and treatment group. All the subjects were treated during 21 days.Results and conclusions:In the largest number of subjects in both groups gonarthrosis occurred primarily as a consequence of knee joint trauma, and then because of weight and physical strain. Of the total number of subjects covered by this research, 9 subjects in control and 8 in treatment group had gonarthrosis of their right knee. 4 subjects in the control and 5 in the treatment group had gonarthrosis of the left knee, while 2 subjects from each group had gonarthrosis on both knees. By the analysis of clinical symptoms of gonarthrosis prior to the treatment, it was found that all the subjects from both groups had pain symptom, in 13 subjects from the control and 14 subjects from the treatment group limited range of motion was established, while 8 subjects from control and 9 subjects from treatment group had swelling in the joint area. The condition of the subjects prior to the treatment was analyzed by means of pain scale, and it was found that both groups experienced moderate level of pain before the treatment. After the 21st day of treatment, the pain intensity was again measured in the subjects that underwent combined physical and medication treatments. In the subjects from the control group that also underwent electrotherapy, the average pain scale value amounted to 2,33±1,34 after treatment, whereas in the subjects that underwent magnetotherapy and combined physical and medication treatments the pain scale amounted to 0,73±0,38. The ANOVA test showed that there is a statistically significant difference in the pain scale before and after the treatment, and also that the improvement in the clinical picture and reduction of pain occurred in both groups of subjects.

Regulation of transglutaminase activity in articular chondrocytes through thrombin receptor-mediated factor XIII synthesis.

Transglutaminases are a family of enzymes that catalyze the formation of epsilon-(gamma-glutamyl)lysine isopeptide bonds in proteins, an activity that has been implicated in the pathogenesis of cartilage matrix mineralization in degenerative arthritis. Type II transglutaminase and thrombin-activatable factor XIII have been identified in articular cartilage. Thrombin, a coagulation protease, is found in pathological synovial fluids, and is known to stimulate transglutaminase activity in non-articular tissues. We investigated the effects of thrombin on transglutaminase activity in porcine articular chondrocytes. Direct addition of thrombin to chondrocyte lysates resulted in increased transglutaminase activity due to proteolytic conversion of factor XIII to XIIIa. Thrombin-treated chondrocyte cultures (0.001 to 2.0 U/ml) also showed increased transglutaminase activity. Thrombin treatment of chondrocyte cultures increased transglutaminase activity as early as 15 minutes after addition, an effect that we attributed to factor XIII activation. Additional stimulatory effects of thrombin were observed in cultured chondrocytes at 4 and 24 hours. A thrombin receptor agonist peptide (TRAP) which activates the PAR1 thrombin receptor mimicked these later effects. Thrombin treatment of chondrocyte cultures increased factor XIII mRNA and protein levels, without affecting levels of type II transglutaminase. Thus, thrombin stimulates transglutaminase activity in articular cartilage by directly cleaving factor XIII and by receptor-mediated up-regulation of factor XIII synthesis. Such increases in potential transglutaminase activity may facilitate pathological matrix calcification in degenerative arthritis.

Matrix metalloproteinases are involved in C-terminal and interglobular domain processing of cartilage aggrecan in late stage cartilage degradation.

Monoclonal antibody (MAb) technology was used to examine aggrecan metabolites and the role of aggrecanases and matrix metalloproteinases (MMPs) in proteolysis of the interglobular domain (IGD) and C-terminus of aggrecan. An in vitro model of progressive cartilage degradation characterized by early proteoglycan loss and late stage collagen catabolism was evaluated in conjunction with a broad-spectrum inhibitor of MMPs. We have for the first time demonstrated that IGD cleavage by MMPs occurs during this late stage cartilage degeneration, both as a primary event in association with glycosaminoglycan (GAG) release from the tissue and secondarily in trimming of aggrecanase-generated G1 metabolites. Additionally, we have shown that MMPs were responsible for C-terminal catabolism of aggrecan and generation of chondroitin sulfate (CS) deficient aggrecan monomers and that this aggrecan truncation occurred prior to detectable IGD cleavage by MMPs. The onset of this later stage MMP activity was also evident by the generation of MMP-specific link protein catabolites in this model culture system. Recombinant MMP-1, -3 and -13 were all capable of C-terminally truncating aggrecan with at least two cleavage sites N-terminal to the CS attachment domains of aggrecan. Through analysis of aggrecan metabolites in pathological synovial fluids from human, canine and equine sources, we have demonstrated the presence of aggrecan catabolites that appear to have resulted from similar C-terminal processing of aggrecan as that induced in our in vitro culture systems. Finally, by developing a new MAb recognizing a linear epitope in the IGD of aggrecan, we have identified two novel aggrecan metabolites generated by an as yet unidentified proteolytic event. Collectively, these results suggest that C-terminal processing of aggrecan by MMPs may contribute to the depletion of cartilage GAG that leads to loss of tissue function in aging and disease. Furthermore, analysis of aggrecan metabolites resulting from both C-terminal and IGD cleavage by MMPs may prove useful in monitoring different stages in the progression of cartilage degeneration.

Identification of Pathologic Synovial Fluid Crystals on Gram Stains

Identification of Pathologic Synovial Fluid Crystals on Gram Stains

Elevated factor J levels in synovial fluid from patients with inflammatory arthropathies

Factor J (FJ) is a complement inhibitor that is able to regulate in vitro both the classical and alternative human complement pathways. In the search of its biological significance, we have analyzed FJ levels in synovial fluid from patients with different arthropathies, in which IL-6 levels had been previously measured. The pathologies included in this study were: rheumatoid arthritis (RA) (n = 21), crystal deposition diseases (CDD) (n = 6), osteoarthritis (OA) (n = 23), spondyloarthritis (SpA) (n = 3) and other inflammatory arthropathies (OIA) (n = 4). We found a good correlation between IL-6 and FJ levels (r = 0.33, p = 0.0132) in the 57 processed samples. Synovial fluids had high levels of IL-6 (median: 3000 pg/ml). Besides, we found that FJ levels were elevated (241 ± 429 μg/ml) when compared with NHS (5.32 ± 2.82 μg/ml). Considering OA patients as control group for non-inflammatory situation, we found that FJ levels were significantly elevated in inflammatory patients only if RA patients were excluded. Furthermore, there were also significant differences with CDD patients. In addition, we have examined the presence of this inhibitor in synovial fluid by Western blot after running gels at acid pH and electrophoretical transference at the same pH. In these experiments, we evidenced the presence of a cationic protein immunoreactive with polyclonal and monoclonal anti-FJ antibodies. In conclusion, FJ levels are elevated in pathological synovial fluids. FJ could be an acute phase reactant as other molecules present in the synovial fluid, or could be shed from extracellular matrix as a consequence of the high enzymatic activity present in the articular fluid or as a response to the inflammatory stimulus.

Characterization of Monoclonal Antibodies Recognizing Different Fragments of Cartilage Oligomeric Matrix Protein in Human Body Fluids

Cartilage oligomeric matrix protein (COMP) is a high-molecular-weight glycoprotein found at a high concentration in articular cartilage. Recent studies have shown that the joint fluid and serum levels of antigenic COMP, measured by an enzyme-linked immunosorbent assay (ELISA) which uses a polyclonal antiserum raised against bovine COMP, provide important information about metabolic changes occurring in the cartilage matrix in joint disease. In this report, we describe the specificity of three monoclonal antibodies (mAbs) to human COMP and their usefulness in quantifying antigenic COMP fragments in body fluids. Two of the mAbs (16-F12 and 18-G3) recognized both oligomeric and monomeric forms of COMP, but the third (17-C10) reacted positively only with the former. Immunoblots of human COMP, predigested with trypsin for up to 6 h, showed that the three mAbs are directed against different epitopes identified on small tryptic fragments of 30 kDa (16-F12), 25 kDa (17-C10), and 40 kDa as well as 30 kDa (18-G3), respectively. The antibodies also recognized a different pattern of fragments in human pathological synovial fluids. This was particularly striking in the case of the medium size fragments (16-F12: 90 and 110 kDa; 17-C10: 70 and 90 kDa; 18-G3: up to five bands from 70 to 130 kDa). Competitive indirect inhibition ELISAs developed with mAbs 16-F12 and 17-C10 revealed further differences in the specificities of these antibodies. Thus, while mAb 16-F12 can be used only to quantify antigenic COMP in human synovial fluid and serum, mAb 17-C10 is useful in addition when analyzing canine and horse synovial fluid as well as canine serum. The results of analyses of synovial fluid samples from patients with osteoarthritis and rheumatoid arthritis provided preliminary evidence in support of the contention that measurement of the different COMP epitopes recognized by these mAbs in body fluids could prove useful in the clinical assessment of patients with joint disease.

Evidence for the Covalent Binding of SHAP, Heavy Chains of Inter-α-Trypsin Inhibitor, to Hyaluronan

We previously showed that serum-derived 85-kDa proteins (SHAPs, serum-derived hyaluronan associated proteins) are firmly bound to hyaluronan (HA) synthesized by cultured fibroblasts. SHAPs were then identified to be the heavy chains of inter-alpha-trypsin inhibitor (ITI) (Huang, L., Yoneda, M., and Kimata, K. (1993) J. Biol. Chem. 268, 26725-26730). In this study, the SHAP.HA complex was isolated from pathological synovial fluid from human arthritis patients. The SHAP.HA complex was digested with thermolysin, followed by CsCl gradient centrifugation. The HA-containing fragments thus obtained were further digested with chondroitinase AC II and subjected to TSK gel high performance liquid chromatography (HPLC). Peptide-HA disaccharide-containing fractions (the SHAP.HA binding regions) were further purified by reverse phase HPLC. Major peaks were analyzed by protein sequencing and mass spectrometry (electrospray ionization mass spectrometry and collision induced dissociation-MS/MS). By comparison with the reported C-terminal sequences of the human ITI family, the peptides were found to correspond to tetrapeptides derived from the C termini of heavy chains 1 of and 2 of inter-alpha-trypsin inhibitor (HC1 and HC2), and heavy chain 3 of pre-alpha-trypsin inhibitor (HC3), respectively, and a heptapeptide from HC1. Mass spectrometric analyses suggested that the C-terminal Asp of each heavy chain was esterified to the C6-hydroxyl group of an internal N-acetylglucosamine of HA chain. This report is the first demonstration to give evidence for the covalent binding of proteins to HA.

Viscoelastic evaluation of different knee osteoarthritis therapies

This study deals with the viscoelastic evaluation of the efficacy of two ordinary knee osteoarthritis therapies: injections of exogenous high molecular weight hyaluronic acid and arthrocentesis. The results were also compared with “placebo” treatment. Synovial fluids were extracted from osteoarthritic knee joints of 60 patients before and after the different treatments and were analysed in a rheometer with coaxial cylinders arrangement at 37°C. Frequency sweep experiments provided the values of shear storage modulus G′ and shear loss modulus G″ as function of oscillation frequency. The quantified viscoelasticity gave information about the mechanical performance of synovial fluids and hence the long-term efficacy of osteoarthritis therapies. Moreover, the results were interpreted in terms of macromolecular structure and hyaluronic acid concentration and molecular weight in pathological synovial fluids.

The detection, quantification and partial characterisation of cathepsin B-like activity in human pathological synovial fluids.

In this study, the levels of the cysteine proteinase--cathepsin B were measured in diseased synovial fluids using a steady state fluorometric assay. Cathepsin B-like activity was shown to be present in all the samples analysed, with the rheumatoid arthritic synovial fluids possessing significantly higher concentrations (mean value ca. 416 mg/l) than the osteoarthritic fluids (mean value ca. 142.4 mg/l). In addition, upon treatment with pepsin, all of the rheumatoid arthritis samples were shown to possess additional cathepsin B-like activity, suggesting the presence of a reservoir of latent precursor molecules. By utilising a recently developed biotinylated affinity label for cathepsin B-like proteinases and sheep anti-(human cathepsin B) antibodies, used in combination with SDS-PAGE and Western blotting, the rheumatoid arthritic synovial cathepsin B was shown to exist in two forms with apparent molecular masses of M(r) 29,000 and 42,000. We propose that the former is a functionally active proteinase, whereas the latter is a pepsin activatable proform which, when cleaved by this aspartyl proteinase, is converted into a catalytically competent species of M(r) 20,000.

Asperity lubrication in human joints.

The asperity lubrication in human joints is examined in the present paper, with particular reference to the tertiary undulation with wavelengths of around 20-45 microns. It was found that, under dynamic physiological loading conditions, the secondary waviness of the cartilaginous surface (typically 0.5 mm wavelength) could be effectively flattened to sustain a fluid film of 0.1-0.3 micron thick, while the tertiary waviness could be squashed to sustain a much thinner fluid film of 0.01 micron (10 nm) thick with normal synovial fluid as the lubricant. The calculated film thickness for the tertiary undulation was less than 5 nm when the ankle joint was lubricated by Ringer's solution or pathological synovial fluids, or when only quasi-static loading conditions were considered, while a sufficiently thick fluid film could still be formed when the secondary undulations were considered alone. It was thus suggested that the fluid film lubrication mechanism was operative for human joints with normal synovial fluid as the lubricant under physiological dynamic loading conditions and the mixed lubrication mechanism could take over when static loading conditions prevailed or when watery lubricants (eta approximately 0.001 Pa s) were used.

ヒト顎関節液の分析と顎関節症の臨床診断について 顎関節液中のタンパク質成分と症状の関係について

Biochemical studies on synovial fluid in the temporomandibular joint are rather rare when compared with those in the orthopedic field. In the orthopedic, several biochemical studies on synovial fluid have been reported such as the study of the proteins, sugars, enzymes, etc. So the author attempted to analyze synovial fluid in the temporomandibular joint and the data were compared with the clinical symptoms.Objects were 10 normal and 60 pathologic samples of temporomandibular joints synovial fluid.Synovial fluid was collected from upper joint cavity by pumping 3 times with 2 ml of 2 Xylocaine. Click or pain in the temporomandibular joint area and changes in the maxium interincisal distance before and after cavity pumping were checked and Orbito-ramus, Schuller projection and arthrogram were taken. Collected synovial fluid was centrifuged at 3, 000 rpm for 10 min, and the supernatant was obtained for analysis. Total protein amount, immunoelectrophoresis, SDS-electrophoresis, and calculation of the albumin/globulin (A/G) ratio from the SDS-electrophoretograms were performed. In addition, gel filtration and ion exchange chromatography, amino acid analysis, immunoblotting method were performed for biochemical study. Correlation coefficient between the biochemical results and clinical data was calculated using a statistic analysis program.The results were as follows; Average of total protein amounts was 1, 259μg/ml in the pathologic synovial fluid, in contrast to 205μg/ml in the normal. Albumin appeared in normal fluid, but albumin, transferrin and IgG were found in the pathologic fluid by the immunoelectrophoresis. A/G ratio of pathologic synovial fluid was 2. 26 which was close to that of serum (1.2-2.1). A protein of 78 k in molecular weight, which was not found in normal synovial fluid or serum, appeared in pathologic synovial fluid in the SDS-electrophoresis. This 78k protein had a tendency to appear when there were pathologic changes in upper joint cavity.(84%). But in the some cases (16%), this protein did not appear in spite of pathologic changes in upper joint. From the results of clinical examination, those cases without 78k protein had a tendency to have chronic or fixed symptoms. By statistic analysis, correlation coefficient between the appearance of 78 k protein and incidence of disk deformity was 0.58. This result indicated that disk deformity may have some relation to 78 k protein appearance.

Fibrin Dissolution in Synovial Fluid

Fibrinogen, fibrinogen-fibrin breakdown products (b.d.p.), fibrin stabilizing factor (FSF), plasminogen, alpha-2 macroglobulin and alpha-1 antitrypsin concentrations were estimated immunologically in normal and in pathological synovial fluids from patients with RA, gout, monoarthritis, rheumatic fever, osteoarthritis and traumatic arthritis. The fibrinolytic activity was determined by the fibrinplate method. Normal synovial fluid contained no fibrinogen, b.d.p., FSF or alpha-2 macroglobulin, but traces of plasminogen and alpha-1 antitrypsin. By increasing inflammatory reactions increasing amounts of the various factors were demonstrable. No distinct, specific, patterns were found. Spontaneous fibrinolytic activity was demonstrable in the most exsudative cases, and in these high concentrations of fibrin breakdown products were present. These were also demonstrable in most pathological synovial fluids proving a recent proteolytic activity. It is suggested, that the fibrin breakdown products in pathological synovial fluids are partly resistent to proteolytic activity.

Concentration and molecular weight of sodium hyaluronate in synovial fluid from patients with rheumatoid arthritis and other arthropathies.

The molecular weight distribution of hyaluronate (HA) in synovial fluid (SF) from 10 patients with rheumatoid arthritis (RA), from six patients with other joint disorders, and from five recently deceased persons without joint affections was investigated by a gel chromatographic procedure. A new and highly specific radioassay was used for determination of the HA concentration in the effluent from the chromatographic column, and this allowed analyses on 0.5 ml or less of untreated synovial fluid. The results confirmed the findings by others that the weight-average molecular weight (Mw) of HA in SF from patients with RA (4.8 X 10(6)) was similar to that in other joint diseases (5.0 X 10(6)) and moderately but significantly (p less than 0.001) lower than that of normal SF (7.0 X 10(6)). Furthermore, the molecular weight distribution of HA in the pathological SF was generally broad and varied considerably between individuals. The HA concentration in the pathological SF varied between 0.17 and 1.32 g/l, which is in accordance with previous reports and considerably lower than that of normal SF. Neither the nature of the arthropathy and the extent of the inflammatory process nor the pharmacological treatment had a tendency to influence the HA concentration in the SF, the mean molecular weight of HA, or its molecular weight distribution. Although the concentration of HA in SF drops in joint disease, the total amount of the polysaccharide is greatly enhanced. Also the amount of high molecular weight polysaccharide (Mw greater than 6 X 10(6)) is in excess in joint disease. The pathological state is therefore characterised not by lack of high molecular weight hyaluronate but by a dilution of it.

Characterization of synovial fluid fibronectin from patients with rheumatic inflammatory diseases and healthy subjects.

Synovial fluid fibronectin from normal subjects and from patients who have rheumatic inflammatory diseases has been studied and compared with plasma fibronectin. The average fibronectin concentration in synovial fluids from normal subjects was 172 +/- 69 micrograms/ml; it was 721 +/- 315 and 556 +/- 349 micrograms/ml in synovial fluids from patients with rheumatoid arthritis and osteoarthritis, respectively. This is the first report on fibronectin concentrations in normal synovial fluids. Synovial fluid fibronectin from healthy subjects and patients with rheumatoid arthritis or osteoarthritis showed a molecular weight identical to that of plasma fibronectin. All normal and pathologic synovial fluid fibronectins showed a remarkably lower electrophoretic mobility compared with that of plasma fibronectin, when separated according to net molecular charge on agarose gel. Peptides from thermolysin digests of fibronectin from plasma and synovial fluid, when compared on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed distinct differences. These data demonstrate that synovial fluid fibronectin represents a molecular form which is structurally different from that of plasma fibronectin. This suggests that synovial fluid fibronectin is locally synthesized, possibly by a cell type which differs from that responsible for the production of the plasmatic fibronectin pool.

Synovial fluids facilitate small solute diffusivity.

The diffusivity of water, fucose, proline, lysine, glutamic acid, glucose and sucrose was determined in a variety of inflammatory human synovial fluids. In view of the constituents of pathological synovial fluids one would predict impedence to solute movement. In several fluid diffusivity was enhanced relative to translational diffusion in water. In most fluids diffusivity was enhanced relative to diffusion in diluted serum. Diffusivity of the solutes was dependent on size and charge of the solute but independent of fluid characteristics, including glucose, protein, and complement concentrations and cellular constituents. This paper reports aberrant small solute behaviour in synovial fluids. Enhanced diffusivity relative to water was demonstrated in hyaluronate dissolved in diluted serum as well. Hyaluronate domains in the synovial fluids interact with these solutes, facilitating movement. This phenomenon affords a homoestatic mechanism as regards chondrocyte viability in spite of inflammation or a low glucose concentration.