Metabolites In Synovial Fluid Research Articles

Sex-specific effects of injury and beta-adrenergic activation on metabolic and inflammatory mediators in a murine model of post-traumatic osteoarthritis

ObjectiveMetabolic processes are intricately linked to the resolution of innate inflammation and tissue repair, two critical steps for treating post-traumatic osteoarthritis (PTOA). Based on lipolytic and immunoregulatory actions of norepinephrine, we hypothesized that intra-articular β-adrenergic receptor (βAR) stimulation would suppress PTOA-associated inflammation in the infrapatellar fat pad (IFP) and synovium. DesignWe used the βAR agonist isoproterenol to perturb intra-articular metabolism 3.5 weeks after applying a non-invasive single-load compression injury to knees of 12-week-old male and female mice. We examined the acute effects of intra-articular isoproterenol treatment relative to saline on IFP histology, multiplex gene expression of synovium-IFP tissue, synovial fluid metabolomics, and mechanical allodynia. ResultsInjured knees developed PTOA pathology characterized by heterotopic ossification, articular cartilage loss, and IFP atrophy and fibrosis. Isoproterenol suppressed the upregulation of pro-fibrotic genes and downregulated the expression of adipose genes and pro-inflammatory genes (Adam17, Cd14, Icam1, Csf1r, and Casp1) in injured joints of female (but not male) mice. Analysis of published single-cell RNA-seq data identified elevated catecholamine-associated gene expression in resident-like synovial-IFP macrophages after injury. Injury substantially altered synovial fluid metabolites by increasing amino acids, peptides, sphingolipids, phospholipids, bile acids, and dicarboxylic acids, but these changes were not appreciably altered by isoproterenol. Intra-articular injection of either isoproterenol or saline increased mechanical allodynia in female mice, whereas neither substance affected male mice. ConclusionsAcute βAR activation altered synovial-IFP transcription in a sex and injury-dependent manner, suggesting that women with PTOA may be more sensitive than men to treatments targeting sympathetic neural signaling pathways.

Metabolic phenotypes reflect patient sex and injury status: A cross-sectional analysis of human synovial fluid

Osteoarthritis is a heterogeneous disease. The objective was to compare differences in underlying cellular mechanisms and endogenous repair pathways between synovial fluid (SF) from male and female participants with different injuries to improve the current understanding of the pathophysiology of downstream post-traumatic osteoarthritis (PTOA). SF from n=33 knee arthroscopy patients between 18 and 70 years with no prior knee injuries was obtained pre-procedure and injury pathology assigned post-procedure. SF was extracted and analyzed via liquid chromatography-mass spectrometry metabolomic profiling to examine differences in metabolism between injury pathologies (ligament, meniscal, and combined ligament and meniscal) and patient sex. Samples were pooled and underwent secondary fragmentation to identify metabolites. Different knee injuries uniquely altered SF metabolites and downstream pathways including amino acid, lipid, and inflammatory-associated metabolic pathways. Notably, sexual dimorphic metabolic phenotypes were examined between males and females and within injury pathology. Cervonyl carnitine and other identified metabolites differed in concentrations between sexes. These results suggest that different injuries and patient sex are associated with distinct metabolic phenotypes. Considering these phenotypic associations, a greater understanding of metabolic mechanisms associated with specific injuries, sex, and PTOA development may yield data regarding how endogenous repair pathways differ between male and female injury types. Ongoing metabolomic analysis of SF in injured male and female patients can be performed to monitor PTOA development and progression.

Synovial Fluid Metabolome Can Differentiate between Healthy Joints and Joints Affected by Osteoarthritis in Horses.

Osteoarthritis (OA) is a common cause of lameness in sport horses with a significant economic impact. The prevention of OA is crucial since no effective treatment is available. This study aimed to apply untargeted metabolomic analysis to investigate the differences in synovial fluid (SF) composition between healthy and OA-affected joints in horses. SF collected from healthy (n.8) and OA (n.11) horses was analyzed using H-NMR analysis. Metabolomic analysis allowed 55 different metabolites to be identified and quantified in SF samples. Nineteen metabolites were found to be differently concentrated in OA compared to control horses. Synovial fluids from the OC group were found to be higher in 1,3-dihydroxyacetone but lower in tryptophan, phenylalanine, tyrosine, uridine, creatinine, creatine, glycine, choline, asparagine, glutamine, arginine, 3-hydroxybutyrate, valine, 2-hydroxyisovalerate, α-ketoisovaleric acid, 3-methyl-2-oxovalerate, 3-hydroxyisobutyrate, isoleucine, and methionine compared to the controls. A variety of SF metabolites significantly changed following joint disease, demonstrating the complex mechanism underlying osteoarthritis in horses and highlighting the value of applying the metabolomic approach in clinical research.

1H NMR metabolic profiling of synovial fluid from patients with anterior cruciate ligament tears and hemarthrosis

To compare the metabolic profiles of synovial fluid (SF) from patients with anterior cruciate ligament tears and hemarthrosis (HA) with that of normal controls, using 1H NMR spectroscopy (NMRS). Synovial fluid was collected from eleven patients undergoing arthroscopic debridement within fourteen days following an anterior cruciate ligament (ACL) tear and hemarthrosis. Ten additional SF samples were obtained from the knees of osteoarthritis-free volunteers to serve as normal controls. The relative concentrations of twenty-eight endogenous SF metabolites (hydroxybutyrate, acetate, acetoacetate, acetone, alanine, arginine, choline, citrate, creatine, creatinine, formate, glucose, glutamate, glutamine, glycerol, glycine, histidine, isoleucine, lactate, leucine, lysine, phenylalanine, proline, pyruvate, threonine, tyrosine, valine, and the mobile components of glycoproteins and lipids) were evaluated using NMRS and quantified using CHENOMX metabolomics analysis software. Mean differences between groups were evaluated with t-tests controlling for multiple comparisons at an overall error rate of 0.10. Statistically significant increases in the levels of glucose, choline, the branched-chain amino acids leucine, isoleucine, and valine, and the mobile components of N-acetyl glycoproteins and lipids were observed in ACL/HA SF as compared with normal controls; lactate levels were reduced. Marked changes occur in the metabolic profiles of human knee fluid following ACL injury and hemarthrosis, suggestive of increased demand and accompanying inflammatory response; potentially increased lipid and glucose metabolism; and possible hyaluronan degradation within the joint following trauma.

Effects of long-term exercise and a high-fat diet on synovial fluid metabolomics and joint structural phenotypes in mice: an integrated network analysis

To explore how systemic factors that modify knee osteoarthritis risk are connected to 'whole-joint' structural changes by evaluating the effects of high-fat diet and wheel running exercise on synovial fluid (SF) metabolomics. Male mice were fed a defined control or high-fat (60% kcal fat) diet from 6 to 52 weeks of age, and half the animals were housed with running wheels from 26 to 52 weeks of age (n=9-13 per group). Joint tissue structure and osteoarthritis pathology were evaluated by histology and micro-computed tomography. Systemic metabolic and inflammatory changes were evaluated by body composition, glucose tolerance testing, and serum biomarkers. SF metabolites were analyzed by high performance-liquid chromatography mass spectrometry. We built correlation-based network models to evaluate the connectivity between systemic and local metabolic biomarkers and osteoarthritis structural pathology within each experimental group. High-fat diet caused moderate osteoarthritis, including cartilage pathology, synovitis and increased subchondral bone density. In contrast, voluntary exercise had a negligible effect on these joint structure components. 1,412 SF metabolite features were detected, with high-fat sedentary mice being the most distinct. Diet and activity uniquely altered SF metabolites attributed to amino acids, lipids, and steroids. Notably, high-fat diet increased network connections to systemic biomarkers such as interleukin-1β and glucose intolerance. In contrast, exercise increased local joint-level network connections, especially among subchondral bone features and SF metabolites. Network mapping showed that obesity strengthened SF metabolite links to blood glucose and inflammation, whereas exercise strengthened SF metabolite links to subchondral bone structure.

Disturbances in Metabolic Pathways and the Identification of a Potential Biomarker Panel for Early Cartilage Degeneration in a Rabbit Anterior Cruciate Ligament Transection Model.

This study aimed to assess the association between synovial fluid (SF) metabolites and magnetic resonance imaging (MRI) measurements of cartilage biochemical composition to identify potential SF biomarkers for detecting the early onset of cartilage degeneration in a rabbit model. Both knees of 12 New Zealand White rabbits were used. The anterior cruciate ligament transection (ACLT) model was performed on right knees, and the sham surgery on left knees. MRI UTE-T2* scanning and SF sample collection were performed on ACLT knees at 4 and 8 weeks postsurgery and on sham surgery knees at 4 weeks postsurgery. Ultra-performance liquid chromatography-mass spectrometry and multivariate statistical analysis were used to distinguish samples in three groups. Pathway and receiver operating characteristic analyses were utilized to identify potential metabolite biomarkers. There were 12 knees in sham surgery models, 11 in ACLT models at 4 weeks postsurgery, and 10 in ACLT models at 8 weeks postsurgery. UTE-T2* values for the lateral tibia cartilage showed significant decreases over the study period. Levels of 103 identified metabolites in SF were markedly different among three groups. Furthermore, 24 metabolites were inversely correlated with UTE-T2* values of the lateral tibia cartilage, while hippuric acid was positively correlated with UTE-T2* values of the lateral tibia cartilage. Among 25 potential markers, N1-acetylspermidine, 2-amino-1,3,4-octadecanetriol, l-phenylalanine, 5-hydroxy-l-tryptophan, and l-tryptophan were identified as potential biomarkers with high area under the curve values and Pearson correlation coefficients. Five differential metabolites in SF were found as potential biomarkers for the early detection of cartilage degeneration in the rabbit ACLT model.

Differences in the composition of hip and knee synovial fluid in osteoarthritis: a nuclear magnetic resonance (NMR) spectroscopy study of metabolic profiles

The hip and knee joints differ biomechanically in terms of contact stresses, fluid lubrication and wear patterns. These differences may be reflected in the synovial fluid (SF) composition of the two joints, but the nature of these differences remains unknown. The objective was to identify differences in osteoarthritic hip and knee SF metabolites using metabolic profiling with Nuclear Magnetic Resonance (NMR) spectroscopy. Twenty-four SF samples (12 hip, 12 knee) were collected from patients with end-stage osteoarthritis (ESOA) undergoing hip/knee arthroplasty. Samples were matched for age, gender, ethnicity and had similar medical comorbidities. NMR spectroscopy was used to analyse the metabolites present in each sample. Principal Component Analysis and Orthogonal Partial Least Squares Discriminant Analysis were undertaken to investigate metabolic differences between the groups. Metabolites were identified using 2D NMR spectra, statistical spectroscopy and by comparison to entries in published databases. There were significant differences in the metabolic profile between the groups. Four metabolites were found in significantly greater quantities in the knee group compared to the hip group (N-acetylated molecules, glycosaminoglycans, citrate and glutamine). This is the first study to indicate differences in the metabolic profile of hip and knee SF in ESOA. The identified metabolites can broadly be grouped into those involved in collagen degradation, the tricarboxylic acid cycle and oxidative metabolism in diseased joints. These findings may represent a combination of intra and extra-articular factors.

Metabolite assignment of ultrafiltered synovial fluid extracted from knee joints of reactive arthritis patients using high resolution NMR spectroscopy.

Currently, there are no reliable biomarkers available that can aid early differential diagnosis of reactive arthritis (ReA) from other inflammatory joint diseases. Metabolic profiling of synovial fluid (SF)-obtained from joints affected in ReA-holds great promise in this regard and will further aid monitoring treatment and improving our understanding about disease mechanism. As a first step in this direction, we report here the metabolite specific assignment of 1 H and 13 C resonances detected in the NMR spectra of SF samples extracted from human patients with established ReA. The metabolite characterization has been carried out on both normal and ultrafiltered (deproteinized) SF samples of eight ReA patients (n=8) using high-resolution (800MHz) 1 H and 1 H─13 C NMR spectroscopy methods such as one-dimensional 1 H CPMG and two-dimensional J-resolved1 H NMR and homonuclear 1 H─1 H TOCSY and heteronuclear1 H─13 C HSQC correlation spectra. Compared with normal SF samples, several distinctive 1 H NMR signals were identified and assigned to metabolites in the 1 H NMR spectra of ultrafiltered SF samples. Overall, we assigned 53 metabolites in normal filtered SF and 64 metabolites in filtered pooled SF sample compared with nonfiltered SF samples for which only 48 metabolites (including lipid/membrane metabolites as well) have been identified. The established NMR characterization of SF metabolites will serve to guide future metabolomics studies aiming to identify/evaluate the SF-based metabolic biomarkers of diagnostic/prognostic potential or seeking biochemical insights into disease mechanisms in a clinical perspective.

Synovial Fluid Metabolites Differentiate between Septic and Nonseptic Joint Pathologies.

Osteoarthritis (OA), osteochondrosis (OC), and synovial sepsis in horses cause loss of function and pain. Reliable biomarkers are required to achieve accurate and rapid diagnosis, with synovial fluid (SF) holding a unique source of biochemical information. Nuclear magnetic resonance (NMR) spectroscopy allows global metabolite analysis of a small volume of SF, with minimal sample preprocessing using a noninvasive and nondestructive method. Equine SF metabolic profiles from both nonseptic joints (OA and OC) and septic joints were analyzed using 1D 1H NMR spectroscopy. Univariate and multivariate statistical analyses were used to identify differential metabolite abundance between groups. Metabolites were annotated via 1H NMR using 1D NMR identification software Chenomx, with identities confirmed using 1D 1H and 2D 1H 13C NMR. Multivariate analysis identified separation between septic and nonseptic groups. Acetate, alanine, citrate, creatine phosphate, creatinine, glucose, glutamate, glutamine, glycine, phenylalanine, pyruvate, and valine were higher in the nonseptic group, while glycylproline was higher in sepsis. Multivariate separation was primarily driven by glucose; however, partial-least-squares discriminant analysis plots with glucose excluded demonstrated the remaining metabolites were still able to discriminate the groups. This study demonstrates that a panel of synovial metabolites can distinguish between septic and nonseptic equine SF, with glucose the principal discriminator.

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.

Lipid profile of human synovial fluid following intra-articular ankle fracture.

This study characterizes the metabolic profile of synovial fluid after intra-articular ankle fracture with an emphasis on changes in the lipid profile. Bilateral ankle synovial fluid from 19 patients with unilateral intra-articular ankle fracture was submitted for metabolic profiling. Contralateral ankle synovial fluid from each patient served as a matched control. Seven patients participated in a second bilateral synovial fluid collection after 6 months. Random forest classification, matched pairs t-tests (α < 0.01), repeated measures ANOVA with post-test contrasts (α < 0.01), correlation to cytokines and matrix metalloproteinases, and fracture and injury classification analyses yielded key lipid biomarkers in synovial fluid following intra-articular fracture. Free fatty acids, sphingomyelins, and lysolipids demonstrated significant elevation in fractured ankles at baseline. Fatty acids and sphingomyelins showed a significant decrease 6 months post-surgery. Random forest analysis showed predominantly fatty acids differentiating between groups. Significant correlations included fatty acids, sphingomyelins, and lysolipids with inflammatory cytokines and matrix metalloproteinases. Fracture classification showed increased fatty acids, lysolipids, and inositol metabolites as fracture severity increased. Fatty acid and sn-1 lysolipid elevation could be detrimental to the joint, as these strongly correlated with matrix metalloproteinases and TNF-α. This elevation also suggests involvement of phospholipase A2 , a potential target for therapeutic intervention. Together with elevated 2-hydroxyl fatty acids, these findings suggest elevated sn-1 lysolipids, sphingomyelins, and subsequent lipid metabolites in synovial fluid as biomarkers of ankle injury. Reversal of this signature after 6 months suggests temporary involvement of these metabolites in disease progression, although they may activate signaling pathways which drive progression to osteoarthritis. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:657-666, 2017.

Energy Metabolism Disorder as a Contributing Factor of Rheumatoid Arthritis: A Comparative Proteomic and Metabolomic Study.

ObjectivesTo explore the pathogenesis of rheumatoid arthritis (RA), the different metabolites were screened in synovial fluid by metabolomics.MethodsSynovial fluid from 25 RA patients and 10 normal subjects were analyzed by GC/TOF MS analysis so as to give a broad overview of synovial fluid metabolites. The metabolic profiles of RA patients and normal subjects were compared using multivariate statistical analysis. Different proteins were verified by qPCR and western blot. Different metabolites were verified by colorimetric assay kit in 25 inactive RA patients, 25 active RA patients and 20 normal subjects. The influence of hypoxia-inducible factor (HIF)-1α pathway on catabolism was detected by HIF-1α knockdown.ResultsA subset of 58 metabolites was identified, in which the concentrations of 7 metabolites related to energy metabolism were significantly different as shown by importance in the projection (VIP) (VIP≥1) and Student’s t-test (p<0.05). In the 7 metabolites, the concentration of glucose was decreased, and the concentration of lactic acid was increased in the synovial fluid of RA patients than normal subjects verified by colorimetric assay Kit. Receiver operator characteristic (ROC) analysis shows that the concentration of glucose and lactic acid in synovial fluid could be used as dependable biomarkers for the diagnosis of active RA, provided an AUC of 0.906 and 0.922. Sensitivity and specificity, which were determined by cut-off points, reached 84% and 96% in sensitivity and 95% and 85% in specificity, respectively. The verification of different proteins identified in our previous proteomic study shows that the enzymes of anaerobic catabolism were up-regulated (PFKP and LDHA), and the enzymes of aerobic oxidation and fatty acid oxidation were down-regulated (CS, DLST, PGD, ACSL4, ACADVL and HADHA) in RA patients. The expression of HIF-1α and the enzymes of aerobic oxidation and fatty acid oxidation were decreased and the enzymes of anaerobic catabolism were increased in FLS cells after HIF-1α knockdown.ConclusionIt was found that enhanced anaerobic catabolism and reduced aerobic oxidation regulated by HIF pathway are newly recognized factors contributing to the progression of RA, and low glucose and high lactic acid concentration in synovial fluid may be the potential biomarker of RA.

Nitric oxide metabolites in synovial fluid of patients with temporomandibular joint internal derangement: correlation with clinical and radiographic signs

Nitric oxide is thought to be involved in the pathogenesis of temporomandibular joint internal derangement. The published papers in this field led us to develop this study which aim was to evaluate nitric oxide metabolites (nitrite and nitrate) in synovial fluid of patients with temporomandibular joint internal derangement, and correlate them with the main clinical and radiographic parameters of the disease. The indication of arthrocenthesis was the main criteria for the selection of patients. At the time of arthrocenthesis, synovial fluid was collected to evaluate nitrite and nitrate.

The Effect of Methotrexate and Leflunomide on the Cytokine Profile and Nitric Oxide Metabolism in Rheumatoid Arthritis Patients

Objective: To reveal the role of individual cytokines and nitric oxide in pharmacological effects of methotrexate and leflunomide in rheumatoid arthritis (RA) patients. Materials and methods: Ninety four patients with confirmed seropositive RA aged 20-60 yrs were examined. The patients were separated into groups of early and late RA and of “erosive” and “non-erosive” RA. 63 patients received methotrexate, and 31, leflunomide. The levels of IL-1β, IL-6, IL-10, and TNF-α were determined in blood serum and synovial fluid using solid-phase enzyme immunoassay. The levels of NO2 and NO3 were determined in blood serum, synovial fluid, and urine by spectrophotometry. All analyses were performed both before and 6 months post therapy. Therapy effectiveness was estimated in the same period. Results: The levels of NO metabolites and cytokines except for IL-6 were increased in synovial fluid and urine of all patients compared to the control. The methotrexate therapy resulted in an increase in IL-1, TNF, and NO metabolites in the peripheral blood. As distinct from methotrexate, leflunomide strongly suppressed IL-6 production in blood serum. The therapy using either drug resulted in a manifold decrease in the levels of IL-1, TNF, and NO metabolites in synovial fluid. Conclusions: There were opposite changes of levels of cytokines and NO metabolites in RA patient’s blood and synovial fluid receiving methotrexate and leflunomide respectively.

Synovial fluid metabolites in osteonecrosis

Osteonecrosis of the femoral head results from interruption of the vascular supply and eventual death of the cellular portion of bone. Effective methods of monitoring response to treatment are needed. Our aim was to evaluate synovial fluid metabolites, glucose and lactate, as biomarkers in a canine model of osteonecrosis. Osteonecrosis was cryosurgically induced in the right femoral head while the left hip served as control (n = 31). Animals either underwent no further intervention (n = 10), vascular endothelial growth factor (VEGF) injections (n = 4), placement of a vascularized bone graft (n = 6), a combination of VEGF microinjection and vascularized graft placement (n = 5), or treatment with daily oral alendronate (n = 6). After 12 weeks, synovial fluid from each hip joint was obtained for glucose and lactate concentrations. Joints with surgically induced osteonecrosis demonstrated decreased synovial fluid concentrations of glucose (P < 0.05) and elevated concentrations of lactate (P < 0.05) relative to contralateral control hips. When animals were treated with VEGF, the vascularized graft placement, or vascularized graft and VEGF, there were no differences in the synovial fluid concentrations of these metabolites between cryoablated and control hips. In contrast, alendronate did not normalize the concentration of these synovial fluid metabolites in the cryoablated hips. Osteonecrosis of the femoral head is associated with alterations in synovial fluid glucose and lactate, reflecting anaerobic metabolism. These metabolites may serve as useful tools for monitoring response to revascularization therapies.

Synovial fluid interleukin 6, tumor necrosis factor, and nitric oxide values in dogs with osteoarthritis secondary to cranial cruciate ligament rupture

Abstract Objective To measure and compare values of interleukin 6 (IL-6), tumor necrosis factor (TNF), and nitric oxide (NO) metabolites in synovial fluid from canine joints with osteoarthritis (OA) secondary to naturally acquired cranial cruciate ligament (CCL) rupture and experimental CCL transection. Animals 57 dogs (clinical group) with OA secondary to CCL rupture; 5 dogs (experimental group) with OA secondary to CCL transection; 19 control dogs with normal joints. Procedure Joints were radiographed and graded for severity of OA. Synovial fluid was collected from dogs: at surgery from the clinical group, at 90 days after surgery from the experimental group, and at necropsy from the control group. Activities of IL-6 and TNF, as well as concentration of the NO metabolites (NO2−/NO3−) were measured, and results were reported as mean ± SEM. Results IL-6 activity in dogs of the clinical (290 ± 40 U/ml) and experimental (494 ± 165 U/ml) groups was greater than that in control dogs (6 ± 1.6 U/ml; P &lt; 0.05). The TNF values in dogs of the clinical (3.0 ± 0.5 pg/ml) and experimental (2.0 ± 0.9 pg/ml) groups were lower than those in control dogs (8.6 ± 2.3 pg/ml; P &lt; 0.05). The IL-6 values were negatively associated with radiographic score of OA and were positively associated with age (R2 = 26.5%, P &lt; 0.05). Conclusion Dogs with OA secondary to naturally acquired CCL rupture and experimental CCL transection had significantly different alterations in synovial fluid IL-6 and TNF values. The decrease in IL-6 activity with advancing OA was independent of the increase in IL-6 activity with aging. Clinical Relevance IL-6 and TNF may be involved in pathogenesis of OA secondary to naturally acquired and experimentally induced CCL rupture. (Am J Vet Res 1997;58:1027–1032)

Positive correlation between levels of IL-1 or IL-2 and 1,25(OH) 2D/25-OH-D ratio in synovial fluid of patients with rheumatoid arthritis

The present study determined the levels in synovial fluid (SF) of vitamin D metabolites (1,25-dihydroxyvitamin D (1,25(OH) 2D), 24,25-dihydroxyvitamin D (24,25(OH) 2D) and 25-hydroxyvitamin D (25-OH-D)), and of the cytokines. We evaluated SF from 21 patients with rheumatoid arthritis (RA) and 6 patients with osteoarthritis (OA). The levels of vitamin D metabolites in SF, as determined by two different extraction methods, were significantly correlated (p < 0.05, n = 7). The levels of 3 vitamin D metabolites were significantly higher in the RA SF than in OA SF (p < 0.05). The ratio of 1,25(OH) 2D/25-OH-D in RA SF, which is presumed to reflect the activity of 25-OH-D-1-hydroxylase (1-OH-ase), was positively correlated with the levels of interleukin-1α (IL-1α), IL-1β, and IL-2 in such SF, and was significantly higher than that in sera from RA patients. This suggests an important role for these cytokines in the activation of 1-OH-ase in RA synovium. The ratio of 24,25(OH) 2D/25-OH-D, which is presumed to reflect 25-OH-D-24-hydroxylase (24-OH-ase) activity, was significantly correlated with 1,25(OH) 2D levels only in RA SF, but not in sera from RA patients, suggesting a local regulation of vitamin D metabolism that 1,25-(OH) 2D induces 24-OH-ase as in other target cells. Our observations suggested that 1,25(OH) 2D and 24,25(OH) 2D are produced locally from 25-OH-D in RA synovium, and that the syntheses of 1,25(OH) 2D and 24,25(OH) 2D may be affected by IL-1 IL-2 and 1,25(OH) 2D in RA SF, respectively.

Synovial fluid interleukin-8 and neutrophil function in rheumatoid arthritis and seronegative polyarthritis.

The relationships between synovial fluid (SF) interleukin-8 (IL-8) and neutrophil turnover as measured by cytidine deaminase (CD), and SF metabolites were studied in 28 patients, 16 with rheumatoid arthritis (RA; median age and disease duration 62 and 14 yr, respectively) and 12 with seronegative polyarthritis (SNP; median age and disease duration 32 and 5 yr, respectively). Knee SF samples were aspirated using indwelling cannulae following a period of rest for 1 h. SF IL-8 levels (measured by an ELISA) were significantly elevated in RA compared to SNP (median 2.35 vs 0.22 ng/ml, P < 0.001), as were median levels of CD (55.8 vs 8.11 U/ml, P < 0.01), lactic acid (29.6 vs 16.6 mg/dl, P < 0.001), glucose (57.9 vs 84.5 mg/dl, P < 0.05) and the lactate to glucose ratio (0.85 vs 0.19, P < 0.001). Measures of disease activity, C-reactive protein, plasma viscosity and articular index were also elevated in RA compared to SNP (P < 0.05). SF IL-8 levels correlated strongly with CD, lactate, glucose and the lactate to glucose ratio when both disease groups were considered together (P < 0.001). These parameters also showed some association with the measures of disease activity (P < 0.05). All these associations were less marked when the individual disease groups were analysed separately. These results suggest that factors responsible for neutrophil accumulation and priming (probably IL-8) are present in SF, and these coincide with products of their activation (CD). The degree of neutrophil turnover is linked to the anaerobic metabolism of the synovial cavity.

顎関節症に対するヒアルロン酸ナトリウムの顎関節腔内注入療法の効果について 特にアラキドン酸代謝産物の消長からみて

We investigated arachidonic acid (AA) metabolites in synovial fluid of 18 patients with temporomandibular joint (TMJ) arthrosis. AA metabolites were separated and quantified by high performance liquid chromatography (HPLC).Among 18 patients, 15 were treated by injections of sodium hyaluronate (SH) into the superior joint compartment of the TMJ. We assessed the effect of treatment clinical symptoms and the generation of AA metabolites.In addition, we measured the leukotrienes (LTs) produced by polymorphonuclear leukocytes (PMNs) obtained from peripheral blood and studied the effect of SH.The following results were obtained:1. Clinical symptoms of TMJ arthrosis improved after intra-articular injections of SH.2. As clinical symptoms improved, AA metabolites decreased.3. SH tended to inhibit the generation of LTs produced by stimulated PMNs.4. This study suggests that TMJ arthrosis is associated with inflammation.