Distinct serum and synovial fluid interleukin (IL)-33 levels in rheumatoid arthritis, psoriatic arthritis and osteoarthritis

ObjectivesRecent evidence suggests a role for interleukin (IL)-33 and its receptor ST2 in arthritis. In this study, we quantified IL-33 and soluble (s)ST2 levels in serum and synovial fluid (SF), and assessed synovial IL-33 expression levels and pattern in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), or osteoarthritis (OA).MethodsSerum and SF IL-33 and sST2 levels were assessed by ELISA. IL-33 mRNA was quantified by RT-qPCR. Synovial IL-33 protein expression pattern was examined by immunohistochemistry.ResultsSerum and SF IL-33 levels tended to be higher in RA than in OA patients. In contrast to RA, IL-33 was not detectable in PsA serum and SF. Serum sST2 levels were higher in RA than in OA. There was a wide variation of synovial tissue IL-33 mRNA expression within each disease group and IL-33 mRNA levels were not significantly different between the groups. A similar IL-33 protein expression pattern was observed in RA, PsA and OA synovium, with strong nuclear expression of IL-33 in endothelial cells and, in a subset of RA, PsA and OA patients, in cells morphologically consistent with synovial fibroblasts.Discussion/ConclusionsThis study confirms increased circulating IL-33 levels in RA. In addition, we report that IL-33 is undetectable in the serum or SF of PsA patients. Local expression of IL-33 in the synovium was observed at similar variable levels in RA, PsA and OA, suggesting that inflamed joints do not represent the primary source of elevated serum and SF levels of IL-33 in RA.     

Prevalence of calcium pyrophosphate and monosodium urate crystals in synovial fluid of patients with previously diagnosed joint diseases

ObjectiveThe main aim of this study was to investigate the frequency of monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals in synovial fluid (SF) obtained from patients with previously diagnosed joint diseases.MethodsWe reviewed the results of SF analysis of 5020 samples identifying those collected from patients with a previously definite diagnosis (2370 samples). SF analysis results, age, sex, diagnosis and disease duration were recorded from computerized records of patients’ archives.ResultsThe prevalence of CPP crystals in SF was 22.28% in osteoarthritis (OA), 8.28% in rheumatoid arthritis (RA), 3.82% in psoriatic arthritis (PsA), 2.79% in other spondyloarthropathies (SpA), 10% in septic arthritis (SeA), 0.66% in gout and 9.18% in the miscellanea of joint diseases, respectively. The prevalence of MSU crystals in SF was 0.30% in RA, 3.34% in PsA, 0.70% in other SpA, 0.80% in acute CPP crystal arthritis (CPP-CA), 0% in OA, reactive arthritis (ReA), SeA, juvenile idiopathic arthritis (JIA) and miscellanea.In OA group, we observed that age and SF inflammatory indices were higher in SF positive to CPP crystals with respect to those without crystals (P < 0.0001). In RA, we found that the group of patients with CPP crystals was significantly older (P = 0.001) and had a SF less inflammatory (P = 0.022) with respect to that without crystals but with a higher disease duration than those without crystals.ConclusionCrystals can be detected more frequently than expected in SF from joint diseases with a previous established diagnosis. This highlights the importance of SF analysis for the diagnosis of possible comorbidities linked to the presence of crystals.     

Primary inflammatory reaction in synovial fluid and tissue in rabbit immobilization osteoarthritis

The kinetics and composition of the primary cellular inflammatory process were studied in the synovial fluid (SF) and synovial tissue (ST) compartments of a rabbit knee immobilization osteoarthritis model. Immobilization induced rapid migration of neutrophils (59% +/- 26% of all cells) into SF in three days, which was accompanied by nonspecific esterase-positive monocytes (71% +/- 8% of all mononuclear cells). This finding suggests that non-specific inflammation mediated by phagocytic leukocytes predominates the cellular response in the SF compartment. In contrast, morphometric analysis of ST proper showed an inflammatory mononuclear cell response, the intensity of which diminished over time during the study period from Day 3 (416 +/- 59 cells per 0.049 mm2 ST tissue) through Day 10 (305 +/- 32 cells) to Day 35 (174 +/- 36 cells). A dotlike T-pattern alpha-naphthyl acetate esterase (ANAE) was found in the T-cell-dependent areas of secondary lymphatic tissue in the spleen, enabling immunocytologic ANAE marker studies. The ST response in situ was predominated by tissue macrophage, though infiltrates rich in T lymphocytes were present in the immediate sublining stroma. There was a significant correlation between the intensity of the SF cell response (total recovery) and the percentage of neutrophils, but there was no correlation between the intensity of the ST response and the proportion of T lymphocytes. These T-cell accumulations together with the local proliferation of fibroblastlike lining cells and stromal fibroblasts suggest that the primary inflammatory cell response is not caused by either wear and tear or mechanically by cartilage fragments.     

miR-204-5p inhibits inflammation of synovial fibroblasts in osteoarthritis by suppressing FOXC1

BackgroundThe paper is aimed at uncovering the mechanism of miR-204-5p in regulating inflammatory responses of human osteoarthritic synovial fibroblasts (SFs).MethodsIL-1β-induced osteoarthritic SFs were established as an osteoarthritis (OA) cell model. The osteoarthritic SFs were accordingly transfected with mimics-miR-204-5p, inhibitors-miR-204-5 or FOXC1 siRNA. MTT tested the vitality of osteoarthritic SFs by analyzing the cell optical density. The expressions of miR-204-5p, FOXC1, TNF-α, IL-6, PGE2, MMP-1, MMP-13 and COX-2 in osteoarthritic SFs were measured by qRT-PCR, Western blotting and/or ELISA. The binding of miR-204-5p to FOXC1 was verified through luciferase reporter assay. The regulatory effect of miR-204-5p on FOXC1 was also tested in normal SFs.ResultsmiR-204-5p was under-expressed and FOXC1 was over-expressed in osteoarthritic SFs. The expressions of FOXC1, TNF-α, IL-6, PGE2, MMP-1, MMP-13 and COX-2 were up-regulated in IL-1β-treated SFs. Up-regulation of miR-204-5p or down-regulation of FOXC1 suppressed the inflammatory responses of osteoarthritic SFs. miR-204-5p negatively regulated FOXC1 by being a sponge in osteoarthritic SFs as well as in normal SFs.ConclusionmiR-204-5p down-regulates FOXC1 to ameliorate inflammation of SFs in OA.     

Presence of spondyloarthritis associated to higher disease activity and HLA-B27 positivity in patients with early Crohn's disease: Clinical and MRI results from a prospective inception cohort

ObjectiveTo determine the SpA prevalence and identify its associated factors in Crohn's disease (CD) patients receiving a systematically rheumatological and imaging assessment, including magnetic resonance imaging (MRI) of the sacroiliac joints and spine.MethodsCD patients either naive to biologics or without them for three months prior enrollment were recruited in a subgroup of the German Spondyloarthritis Inception Cohort (GESPIC-Crohn). A structured assessment of SpA manifestations was performed by a rheumatologist, including MRI of sacroiliac joints and spine. Demographic and clinical parameters including disease activity in CD (Harvey Bradshaw Index-HBI) and SpA (C-reactive protein – CRP, Bath Ankylosing Spondylitis Disease Activity Index, and Ankylosing Spondylitis Disease Activity Score) were collected. Univariable and multivariable logistic regression analyses were performed to identify factors associated with the presence of SpA.ResultsA total of 103 patients with CD were included in the cohort. The mean CD disease duration was 1.3 ± 2.4 years and 95.1% were naïve to biologics. The most frequent musculoskeletal manifestation was back pain (65.0%), followed by chronic back pain (50.5%), and arthralgia (43.7%). Prevalence of SpA was 19.4% with slightly higher proportion of axial SpA than peripheral SpA, and higher proportion of radiographic axial SpA (7.4%) than non-radiographic axial SpA (2.8%). Changes in MRI compatible with axial SpA were found in 15 (14.7%) patients, of which 9 (81.1%) patients had the clinical diagnosis of axial SpA. HLA-B27 positivity (OR 9.02, CI 95% 2.29–35.55) and higher disease activity of CD as reflected by the HBI (OR 1.14, 95%CI 1.01–1.30) were significant and independently associated with the presence of SpA.ConclusionSpA was present in nearly one out of five patients with CD and it was associated with the expression of HLA-B27 and a higher clinical activity of CD. Our findings raise awareness to rheumatologists and gastroenterologists on the high concomitance between both diseases and may help to reduce the delay in SpA diagnosis.     

Can we improve the diagnosis of spondyloarthritis in patients with uncertain diagnosis? The EchoSpA prospective multicenter French cohort

Power Doppler ultrasound (PDUS) has proved to be a highly sensitive tool for assessing enthesitis in spondyloarthritis (SpA). In patients with a suspected SpA, diagnosis could be improved by detecting enthesitis with PDUS.ObjectiveTo evaluate the performance of PDUS for the diagnosis of SpA alone or combined with other clinical, laboratory and imaging findings in patients consulting for a suspected SpA.MethodsProspective, multicenter French cohort study (Boulogne-Billancourt, Brest, Caen, Grenoble, Marseille and Nancy). Outpatients consulting for symptoms suggestive of SpA (inflammatory back pain [IBP], arthritis or inflammatory arthralgia [IA], enthesitis or dactylitis [ED], HLA-B27 positive uveitis [B27+U], familiarity for SpA [Fam]) were recruited and followed up for at least 2 years. Sample size was set to 500 patients (for estimated prevalence of SpA of 30 ± 5% after 2 years). At baseline, patients were submitted to standardized physical examination, pelvic X-ray, sacroiliac joints magnetic resonance imaging (MRI), HLA-B typing, and other tests judged useful for diagnosis. For each patient, a blinded PDUS examination of 14 enthesitic sites was performed at baseline and at years 1 and 2. Patients were planned to be followed during 5 years. The diagnosis of SpA ascertained by an experts’ committee, blind to PDUS results, after at least 2 years of follow-up, with a revaluation of doubtful patients at 5 years will be used as gold standard for evaluating the diagnostic performance of PDUS and the best diagnostic procedure by combining PDUS, clinical symptoms and other tests.ResultsBetween January 2005 and September 2007, 489 patients were included (96% of the target population). Nineteen patients (0.2%) retired their informed consensus or were lost to follow-up immediately after their inclusion. At baseline, mean age of the 470 remaining patients was 40 years, mean duration of symptoms was 6.1 years; 42% of them were HLA-B27+ and 63% were female. Primary inclusion criterion was IBP in 53%, IA in 27%, ED in 9%, B27+U in 8% and Fam in 4%. Follow-up is still ongoing.ConclusionWe have set up a unique diagnostic cohort which includes the entire spectrum of SpA manifestations. By using PDUS we expected to improve the diagnostic procedure of SpA.     

Comparative analysis of 23 synovial fluid biomarkers for hip and knee periprosthetic joint infection detection

There is interest in novel synovial fluid biomarkers for the detection of periprosthetic joint infection (PJI). Here, we assessed the diagnostic accuracy of 23 simple or sophisticated synovial fluid biomarkers for periprosthetic hip or knee infection detection. One hundred seven subjects were studied, 57 of whom had aseptic failure (AF) and 50 PJI. The following synovial fluid biomarkers were tested using spectrophotometric assays, immunoassays, lateral flow tests, or test strips: leukocyte count, monocyte percentage, lymphocyte percentage, neutrophil percentage, C-reactive protein (CRP), glucose, lactate, granulocyte-macrophage colony-stimulating factor, interferon-γ, interleukin-1β (IL-1β), IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, IL-23, tumor necrosis factor-α, α-defensin, and leukocyte esterase. The best-performing synovial fluid biomarkers to differentiate PJI from AF—that is, those with highest area under the curve compared to all other biomarkers—were leukocyte count, percent neutrophils and percent monocytes, CRP, and α-defensin (P < .0001).     

Performance of a new rapid diagnostic test the lactate/glucose ratio of synovial fluid for the diagnosis of septic arthritis

ObjectiveTo evaluate the diagnostic performance of the synovial lactate, glucose and lactate/glucose ratio assay for the diagnosis of septic arthritis.MethodsIn this monocentric cross-sectional study, synovial fluids were prospectively obtained from patients with acute joint effusion (<30 days) on native joint. Septic arthritis was defined using Newman's criteria. To evaluate diagnostic performance, Receiver Operating Characteristic (ROC) curves with Area under the curve (AUC), Sensitivities (Se), Specificities (Sp), LR+ their 95% confidence intervals were calculated. Synovial fluid cultures with gram staining, crystal analyses, synovial fluid white blood cell counts (WBC), lactate and glucose assays were performed.ResultsA total of 233 synovial fluids were included. 25 patients had septic arthritis and 208 had non-septic arthritis (104 crystal-induced arthritis, 15 RA, 8 SpA, 6 reactive arthritis, and 75 acute arthritis of undifferentiated origin). Synovial lactate/glucose ratio performed higher than the synovial lactate or glucose assay separately (AUC: 0.859 [0.772–0.945]). Best synovial lactate/glucose ratio threshold to differentiate septic arthritis from non-septic arthritis was 5 Se 52% [0.34–0.7], Sp 98.1% [0.95–0.99], LR+ 27.0[9.50–76.00]).ConclusionThe diagnostic performance of synovial lactate/glucose allows septic arthritis to be effectively and very quickly distinguished from other types of arthritis.     

Use of synovial fluid markers of cartilage synthesis and turnover to study effects of repeated intra-articular administration of methylprednisolone acetate on articular cartilage in vivo.

In vivo the effects of intra-articular (IA) corticosteroids on articular cartilage remain controversial. This study was designed to examine this issue using synovial fluid (SF) markers of cartilage metabolism. Paired radiocarpal joints, without clinical or radiographic signs of joint disease, were studied in 10 adult horses. Aseptic arthrocentesis was performed weekly for 13 weeks. IA injections of methylprednisolone acetate (MPA) into the treatment joint and the vehicle into the control joint were performed at weeks 3, 5 and 7. We used radioimmunoassays on SF samples which measure a keratan sulfate epitope (KS) and the 846 epitope on cartilage aggrecan (PG) and the C-propeptide (CPII) of cartilage type II procollagen which is released following synthesis of this molecule. Gel chromatography was performed on selected SF samples to evaluate the sizes of SF PG molecules. The total joint KS and the 846 epitopes were both present on a heterogeneous population of mainly molecules which, from chromotographic analysis, appeared to be mainly fragments of the articular cartilage aggrecan. They were significantly elevated in MPA joints whereas CPII was significantly reduced compared to the control during the treatment period. These results indicate that the repeated use of IA MPA leads to a potentially harmful inhibition of procollagen II synthesis and an increased release of degradation products of the PG aggrecan from articular cartilage.     

Interleukin-16 in synovial fluids from cases of various types of arthritis

OBJECTIVES: To examine the characteristic relationship between interleukin-16 (IL-16) and clinical data in various types of arthritis. METHODS: We measured IL-16 levels of the synovial fluids (SF) of patients with various types of arthritis, which included rheumatoid arthritis, traumatic arthritis, pseudogouty arthritis, gouty arthritis, and osteoarthritis, by an enzyme immunosorbent assay, and examined their correlations with clinical parameters. RESULTS AND CONCLUSIONS: Higher levels of IL-16 in synovial fluid from patients with rheumatoid arthritis, traumatic arthritis, and pseudogouty arthritis, compared to those with osteoarthritis, and gouty arthritis were indicated. Also, synovial IL-16 levels in patients with rheumatoid arthritis correlated significantly, especially with synovial matrix metalloproteinase-3 levels. But the IL-16 levels of both synovial fluid and peripheral blood did not correlate with conventional inflammatory parameters such as C-reactive protein, erythrocyte sedimentation rate, or rheumatoid factor. Although the function of IL-16 in inflammatory arthritis has not yet been defined, these data indicated some essential features of IL-16.     

The effect of oral sodium taurocholate on endotoxemia and intestinal anastomotic wound healing in rats with obstructive jaundice

The effect of sodium taurocholate (ST) on endotoxemia and intestinal anastomotic wound healing in obstructive jaundice was evaluated in a rat model. A total of 108 Wistar rats were divided into three main groups. Thus, 36 animals were given ileal anastomosis (IA) alone (IA group), 36 were given IA with bile duct ligation (BDL) (IA+BDL group), and 36 were given IA with BDL and oral sodium taurocholate (ST) (IA+BDL+ST group). These three main groups were then divided into three equal subgroups, A, B, and C, which were killed on postoperative days (POD), 3, 5, and 9, respectively. In the IA+BDL+ST group, ST was administrated perioperatively and ceased from POD 5 onwards. The anastomotic hydroxyproline level and bursting pressure were significantly lower in the IA+BDL animals compared with the others on POD 3, 5, and 9 (P<0.008). Endotoxemia was prominent in the IA+BDL group from POD 3 (P=0.011). After ST was stopped, 42% of the AI+BDL+ST animals developed endotoxemia by POD 9 (P=0.008). Anastomotic wound healing was better in the IA+BDL+ST group (P<0.01). These findings suggest that endotoxemia and its adverse effects on wound healing in obstructive jaundice can be prevented by the oral administration of ST.     

Autologous synovial fluid enhances migration of mesenchymal stem cells from synovium of osteoarthritis patients in tissue culture system

Synovial fluid from osteoarthritic knee contains mesenchymal stem cells (MSCs). One of the possible reservoirs of MSCs in synovial fluid is synovial tissue, and synovial fluid may induce mobilization of MSCs into synovial fluid in osteoarthritis patients. Here, we investigated whether synovial fluid expanded synovial MSCs in a tissue culture system. Human synovium and synovial fluid were obtained from osteoarthritis patients during total knee arthroplasties. In the tissue culture system, autologous synovial fluid expanded synovial cells statistically higher than αMEM + FBS, and the addition of TGFβ3 to αMEM + FBS increased expansion to a similar level in all 11 donors. The addition of decorin or anti‐TGFβ neutralizing antibody to synovial fluid partially inhibited synovial cell expansion. In cell culture assay, synovial fluid proliferated synovial cells fewer than αMEM + FBS. The expanded synovial cells in synovial fluid retained multipotentiality and showed surface markers similar to those of MSCs. We demonstrated that autologous synovial fluid enhanced expansion of MSCs in tissue culture of synovium from osteoarthritis patients by promoting cell migration. This effect was partially affected by TGFβ. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1413–1418, 2008     

Dual transduction of insulin-like growth factor-I and interleukin-1 receptor antagonist protein controls cartilage degradation in an osteoarthritic culture model.

This study evaluated the potential of gene induced synoviocyte expression of a combination of insulin-like growth factor-I (AdIGF-I) and interleukin-1 receptor antagonist protein (AdIL-1Ra) to control articular cartilage degradation in vitro. Cartilage explants and synovial membrane were harvested from young mature horses. Synovial monolayers were established and either (1) maintained as untransduced controls; (2) transduced with AdIGF-I at 200 MOI in 500 microl serum-free medium; (3) transduced with AdIL-1Ra at 100 MOI; or (4) transduced with a combination of AdIGF-I (200 MOI) and AdIL-1Ra (100 MOI). Following transduction, cartilage explants were exposed to the synovial monolayer medium using co-culture inserts. Cultures were maintained for 6 days in either serum-free medium or medium containing 10 ng/ml recombinant human interleukin-1beta. At termination, synovial cell RNA was isolated for real-time PCR analysis, and cartilage explants were collected for H&E and toluidine blue staining, immunohistochemistry for type II collagen and IGF-I, in situ localization of IGF-I and type II collagen gene expression, and biochemical assays. Synovial monolayers were readily transduced with both AdIGF-I and AdIL-1Ra. IGF-I and IL-1Ra protein were secreted at beneficial levels throughout the experiment, having peak concentrations of 94.6 ng/ml and 33.0 ng/ml, respectively. Transduction with IGF-I promoted cartilage production of proteoglycan and type II collagen, suggesting a beneficial role for healing injured cartilage. Transduction with IL-1Ra decreased the synovial expression of IL-1alpha and IL-1beta and matrix metalloproteinases, indicating a mechanism for prevention of matrix degradation. The beneficial effects of the combination of anabolic growth factors and catabolic blockers were evident in improved preservation of proteoglycan content of cartilage explants exposed to the depleting effects of IL-1. These results show that gene therapy combining anabolic growth factors to stimulate matrix synthesis and catabolic blockers to prevent matrix degradation by IL-1, protects and causes partial restoration of cartilage matrix, and suggest a potential benefit of combination gene therapy for cartilage healing.     

Cytokine-Induced and Stretch-Induced Sphingosine 1-Phosphate Production by Enthesis Cells Could Favor Abnormal Ossification in Spondyloarthritis

Spondyloarthritis (SpA) is a common rheumatic disease characterized by enthesis inflammation (enthesitis) and ectopic ossification (enthesophytes). The current pathogenesis model suggests that inflammation and mechanical stress are both strongly involved in SpA pathophysiology. We have previously observed that the levels of sphingosine 1-phosphate (S1P), a bone anabolic molecule, were particularly high in SpA patients' serum compared to healthy donors. Therefore, we wondered how this deregulation was related to SpA molecular mechanisms. Mouse primary osteoblasts, chondrocytes, and tenocytes were used as cell culture models. The sphingosine kinase 1 (Sphk1) gene expression and S1P secretion were significantly enhanced by cyclic stretch in osteoblasts and chondrocytes. Further, TNF-α and IL-17, cytokines implicated in enthesitis, increased Sphk1 mRNA in chondrocytes in an additive manner when combined to stretch. The immunochemistry on mouse ankles showed that sphingosine kinase 1 (SK1) was localized in some chondrocytes; the addition of a pro-inflammatory cocktail augmented Sphk1 expression in cultured ankles. Subsequently, fingolimod was used to block S1P metabolism in cell cultures. It inhibited S1P receptors (S1PRs) signaling and SK1 and SK2 activity in both osteoblasts and chondrocytes. Fingolimod also reduced S1PR-induced activation by SpA patients' synovial fluid (SF), demonstrating that the stimulation of chondrocytes by SFs from SpA patients involves S1P. In addition, when the osteogenic culture medium was supplemented with fingolimod, alkaline phosphatase activity, matrix mineralization, and bone formation markers were significantly reduced in osteoblasts and hypertrophic chondrocytes. Osteogenic differentiation was accompanied by an increase in S1prs mRNA, especially S1P_1/3, but their contribution to S1P-impact on mineralization seemed limited. Our results suggest that S1P might be overproduced in SpA enthesis in response to cytokines and mechanical stress, most likely by chondrocytes. Moreover, S1P could locally favor the abnormal ossification of the enthesis; therefore, blocking the S1P metabolic pathway could be a potential therapeutic approach for the treatment of SpA. © 2019 American Society for Bone and Mineral Research.     

Repeated intraarticular injections of triamcinolone acetonide alter cartilage matrix metabolism measured by biomarkers in synovial fluid.

Although intraarticular (IA) corticosteroids are frequently used to treat joint disease, the effects of their repeated use on articular cartilage remains controversial. The aim of our study was to determine the effects of a clinically recommended dose of IA triamcinolone acetonide (TA), on synovial fluid (SF) biomarkers of cartilage metabolism. Ten adult horses, free of osteoarthritis (OA) in their radiocarpal joints, were studied. One radiocarpal joint of each horse was randomly chosen for treatment and the contralateral anatomically paired joint acted as the control. Aseptic arthrocentesis was performed weekly on both joints for 13 weeks. The initial results from the first 3 weeks of the experimental period established baseline untreated control marker levels for each joint, each being its own control. On weeks 3, 5, and 7, a sterile suspension of 12 mg of TA was injected into the treated joint and an equivalent volume of sterile saline solution (0.9%) was injected into the control joint. SF was immunoassayed for biomarkers of aggrecan turnover (CS 846 & KS), types I and II collagen cleavage (C1,2C) and type II collagen synthesis (CPII). In treated joints, there was a significant increase in CS 846, KS, C1,2C and CPII epitope concentrations following IA TA injections when compared to baseline levels. There was also a significant increase in C1,2C and CPII epitope concentrations in the contralateral control joints following IA TA injections in the treated joint. Significant differences were observed between treated and control joints for all markers except CPII. These findings indicate that TA alters articular cartilage and collagen metabolism in treated and, interestingly, also in control joints, suggesting a systemic effect of the drug. Though intuitively the observed findings would favor the hypothesis that long-term IA TA treatment changes joint metabolism and this may have detrimental effects; further studies would be necessary to confirm this.     

Anti-interleukin-1 effects of diacerein and rhein in human osteoarthritic synovial tissue and cartilage cultures.

OBJECTIVE: The etiology of osteoarthritis (OA) is still a matter of debate. Several factors are known to be involved in the destruction of the articular cartilage. Interleukin-1 (IL-1) plays an important role in the pathogenesis of osteoarthritis (OA) either directly or through the stimulation of catabolic factors, such as nitric oxide (NO). The objective of this study was to evaluate the effect of diacerein, a new anti-OA agent and its active metabolite, rhein, on the production and function of IL-1beta, nitric oxide (NO) and receptor agonist (IL-1ra) in human OA cartilage and synovial tissue cultures. DESIGN: Synovial tissue and cartilage derived from OA patients were kept in culture for 48-72 hours in the presence of 1 microg/ml of lipopolysaccharide (LPS) with or without diacerein (10(-7)-10(-5) M), rhein (10(-7)-10(-5) M) and hydrocortisone (5 microg/ml). IL-1beta, IL-1ra, NO productions and 35S uptake were measured in culture media. In some experiments the resulting supernatants from synovial tissue cultures were added to cartilage. RESULTS: Diacerein and rhein, as well as hydrocortisone, significantly inhibited LPS-induced IL-1beta production by synovial tissue and cartilage. They also significantly reversed the inhibitory effect of LPS on cartilage 35S uptake. Culture media from synovial tissue containing LPS+diacerein (10(-6) M) or +rhein (10(-6) M) had a significantly less inhibitory effect on cartilage synthesis than culture media containing LPS only. Diacerein and rhein decreased NO release in synovial tissue and cartilage media and increased IL-1ra levels in cartilage culture media. CONCLUSION: An inhibitory effect of diacerein and rhein at therapeutic concentrations on both IL-1beta secretion and function in human synovial tissue and cartilage is suggested. Diacerein and rhein effects on NO production by LPS-stimulated OA synovial tissue and cartilage may both contribute and elucidate their anti-OA properties.     

Value of synovial analysis for prognosis of matrix synthesis of transplanted chondrocytes

Successful transplantation of autologous chondrocytes for repair of articular cartilage defects requires an undisturbed matrix-synthesis of the transplanted cells. This, in turn, is dependent on the composition of the synovial fluid (SF) of the respective joint. We addressed the question whether analysis of a patient's SF can predict the rate of matrix-synthesis of articular cartilage exposed to this SF in vitro. SF was obtained from 115 patients with disorders of the knee, including gonarthrosis (n = 44), meniscal tears (n = 10), rheumatoid arthritis (n = 53), and reactive arthritides (n = 8). In the SF, the following parameters were determined: Interleukin-1 beta, IL-6, IL-8, IL-1-RA, TNF alpha, Insulin-like growth-factor I (IGF-I), IGF-II, IGF-binding protein-2 (IGFBP-2), IGFBP-3 as well as total proteinase activity and total collagenase activity. To assess the effect of SF on the matrix synthesis of articular chondrocytes, bovine cartilage was incubated in the presence of SF, and the rate of proteoglycan synthesis subsequently determined. In some cases, a monoclonal antibody directed against IGF-I was added. SF from patients with OA or trauma, respectively, stimulated PG-synthesis of bovine cartilage more markedly than did SF from patients with rheumatic arthritides. On the average, 60 percent of the SF-induced increase of cartilage matrix synthesis could be titrated out by an anti-IGF-I-AB. The best predictor for the SF-effects on PG-synthesis of exposed cartilage was the proportion of free IGF-I (r = 0.573, p < 0.001, Spearman rank correlation) followed by the SF-concentrations of IGF-I (with a positive sign), IGFBP-3, IL-1 beta, and TNF alpha (all with a negative sign). According to our data, IGF-I is the most important anabolic factor in human SF with respect to cartilage PG-synthesis. The proportion of free IGF-I seems to be of special importance in this regard. Low SF-levels of free IGF-I could be identified as a possible risk-factor for a sub-optimal protoeglycan synthesis of chondrocytes exposed to this synovial milieu.     

Interleukin-7 levels in synovial fluid increase with age and MMP-1 levels decrease with progression of osteoarthritis

Background and purpose

Little is known about biochemical mediators that correlate with the initiation and progression of knee osteoarthritis (OA). We therefore valuated the roles of cytokines and metalloenzymes in knee OA in relation to OA grading, age, and BMI.

Patients and methods

A multiplex ELISA-based immunoassay (Luminex technology) was used to measure biochemical mediators in the synovial fluid (SF) of 82 patients undergoing knee surgery. All patients were classified according to age, BMI, and OA grade. 24 patients had no signs of OA (knee reconstruction surgeries). The mediators that were tested for included interleukins (IL-1Ra, IL-6, IL-7, and IL-18), chemokines (CCL2 (MCP-1), CCL3 (MIP-1a), and CXCL8 (IL-8)), growth factors (HGF and VEGF), and matrix metalloproteinases (MMP-1, MMP-2, MMP-9, and MMP-13).

Results

There was a correlation between IL-7 levels in SF and age (p < 0.01). The 11 highest IL-7 levels were seen in patients who were aged between 59 and 72 but had different OA grades. In contrast, all patients who had severe OA in all 3 knee compartments (pan-OA) had only low or medium IL-7 levels. There was a negative correlation between MMP-1 levels in synovial fluid and grade of OA (p < 0.001). Correlation studies between pairs of mediators revealed two groups of mediators that are important in OA progression, dominated by MCP-1 and IL-1Ra.

Interpretation

IL-7 levels in SF are elevated in elderly people suffering from OA of different grades, but they are depressed in patients with severe 3-compartment OA, possibly due to widely impaired chondrocytes embedded in the affected cartilage tissue. The observed decrease in MMP-1 levels in SF, which is dependent on the severity of OA, may be caused by deterioration of superficial cartilage layers during progression of OA.

List of abbreviations

BMI

body mass index

CCL

chemokine (C-C motif) ligand

CXCL

chemokine (C-X-C motif) ligand

HGF

hepatocyte growth factor

ICRS

International Cartilage Repair Society

IL

interleukin

IL-1Ra

IL-1 receptor antagonist

MCP

monocyte chemoattractant protein

MIP

macrophage inflammatory protein

MMP

matrix metalloproteinase

OA

osteoarthritis

SF

synovial fluid

VEGF

vascular endothelial growth factor

Progression of knee OA is often driven by biomechanical forces (Englund 2010), whereas the etiology of OA in other joints is less affected by mechanical stress. Biochemical mediators such as cytokines, growth factors, and matrix metalloproteinases—acting individually or in networks—profoundly influence cellular responses in joint tissues, modifying both catabolic and anabolic activities involved in the pathogenesis of OA (Goldring and Goldring 2007). Ageing is the most prominent risk factor for OA, and chondrocyte senescence and aging-related changes in the matrix, such as articular surface fibrillation and proteoglycan changes, are most likely to contribute to joint ageing (Martin and Buckwalter 2002, Shane Anderson and Loeser 2010). However, despite intensive research efforts, little is known about biochemical factors whose levels may correlate with the severity of knee OA (Belo et al. 2007). Also, age-related changes in cytokine production in body fluids have not been investigated completely (Gardner and Murasko 2002).Biochemical mediators found in synovial fluid (SF) that affect the cellular functions of tissues of the knee joint include interleukins (ILs), chemokines, growth factors, and matrix metalloproteinases (MMPs). Interleukins, both pro- and anti-inflammatory, have a pivotal role in arthritic diseases and are potential targets of OA therapy. Chemokines, which are small, chemoattractant cytokines, have key roles in the accumulation of inflammatory cells at the site of inflammation. Growth factors produced by chondrocytes and subchondral bone regulate the growth of blood vessels in the joint. Some recent studies have supported the notion that inhibition of abnormal angiogenesis will provide effective therapeutic strategies for treatment of OA (Ashraf and Walsh 2008). MMPs and pro-inflammatory cytokines are involved in a collagen II-dependent feed-forward mechanism of matrix degradation in human articular cartilage (Klatt et al. 2009).To improve our understanding of the molecular and cellular processes involved in joint ageing and in the initiation and progression of OA, we wanted to determine the levels of biochemical mediators that correlate with the severity of knee OA or patient age.     

Direct anti-proliferative effect of adipose-derived mesenchymal stem cells of ankylosing spondylitis patients on allogenic CD4+ cells

ObjectivesT-cell-mediated adaptive immunity contributes to the development and persistence of ankylosing spondylitis (AS). Mesenchymal stromal/stem cells (MSCs) have immunomodulatory potential and are able to inhibit T-cell proliferation, but their functionality in AS patients is relatively unknown. The aim of the study was to assess the direct anti-proliferative effects of MSCs isolated from subcutaneous abdominal adipose tissue of AS patients (AS/ASCs) on allogeneic T lymphocytes, using commercially available ASC lines from healthy donors (HD/ASCs) as a control.Material and methodsCD3+CD4+ T-cells were isolated from peripheral blood of healthy blood donors, activated with anti-CD3/CD28 beads, and co-cultured for 5 days with untreated and TNF+IFN-γ pre-stimulated HD/ASCs (5 cell lines) and AS/ASCs, obtained from 11 patients (6F/5M). The proliferative response of T-cells was analysed by flow cytometry, while the concentrations of kynurenines, prostaglandin E2 (PGE-2), interleukin 10 (IL-10), and interleukin 1 receptor antagonist (IL-1Ra) were measured spectrophotometrically or using a specific enzyme-linked immunosorbent assay (ELISA).ResultsHD/ASCs and AS/ASCs similarly reduced the T-cell proliferation response, i.e. the percentage of proliferating cells, the proliferation, and replication indices, and these effects were dependent mostly on soluble factors. In the co-cultures of activated CD4+ T-cells with HD/ASCs and AS/ASCs significant increases of kynurenines, PGE-2, and IL-1Ra, but not IL-10, production were observed. The release of these factors was dependent either on cell-to-cell contact (IL-10, IL-1Ra) or soluble factors (kynurenines, PGE-2). There was a moderate to strong negative correlation between T-cell proliferative response, and the concentrations of kynurenines, PGE-2, and IL-10, but not IL-1Ra. This association was more evident in the case of TI-treated AS/ASCs than HD/ASCs.ConclusionsAS/ASCs, similar to HD/ASCs, exert a direct effective anti-proliferative impact on CD4+ T cells, acting via soluble factors that are released in cell contact-dependent (IL-10) and independent (kynurenines, PGE-2) pathways. Thus, our results suggest that AS/ASCs are potentially useful for therapeutic application.