Serum and synovial fluid histidine: a comparison in rheumatoid arthritis and osteoarthritis

Summary The serum and synovial fluid (SF) histidine, sulphydryl, and protein concentrations were compared in simultaneous samples from 84 patients with rheumatoid arthritis (RA) and a control group comprising 29 patients with osteoarthritis (OA). The SF levels of histidine were higher than the serum levels in the RA patients but significantly lower than corresponding results in patients with OA (P<0.001). The latter had levels of serum and SF histidine which were equivalent and within the normal range. Greater quantities of protein were found in the SF of the patients with RA compared with the OA group. The serum and SF sulphydryl concentrations expressed as mol/g protein were low but in equilibrium in patients with RA. However the SF sulphydryl (mol/g protein) was depressed relative to serum levels in patients with OA.     

Synovial fluid and serum hydroxyproline fractions in rheumatoid arthritis.

In rheumatoid arthritis (RA) the synovial fluid lymphocyte count closely parallels the synovial fluid dialysable hydroxyproline, a marker of collagen resorption. This observation stresses the primordial role of lymphocytes in RA joint injury. The actual and eventually potential destruction of any single joint, as expressed by synovial fluid dialysable hydroxyproline levels, seems to reflect the general picture of disease activity as evaluated by the number of active joints (joint count), ESR and rheumatoid factor titres (latex fixation). Although urinary hydroxyproline levels are generally within the normal range in RA, they can be used as index of articular tissue destruction and as a parameter of overall disease activity when groups of patients are studied longitudinally in detail. The present study sheds no further light on the significance of synovial fluid and blood non-dialysable hydroxyproline levels.     

Serum and synovial fluid adenosine deaminase activity in patients with rheumatoid arthritis, osteoarthritis, and reactive arthritis.

Adenosine deaminase activity was determined in paired samples of serum and synovial fluid taken from patients with rheumatoid arthritis (n = 12), reactive arthritis (n = 13), and osteoarthritis (n = 7), and the value of this investigation in the diagnosis of synovial swellings was assessed. Increased activity was found in the synovial fluid taken from patients with rheumatoid disease and reactive arthritis, though values were less raised in the latter. Synovial fluid taken from patients with osteoarthritis did not show significantly raised adenosine deaminase activity as compared with that of normal controls (n = 3).     

Synovial fluid beta 2 microglobulin and hydroxyproline fractions in rheumatoid arthritis and nonautoimmune arthropathies.

Fourteen patients with classical and definite seropositive rheumatoid arthritis (RA), 5 patients with microcrystalline arthritis, and 7 patients with osteoarthrosis were studied with respect to markers of newly synthesised collagen (synovial NDOH pro levels); markers of connective tissue resorption (synovial DOH pro and NBH levels); markers of lymphoid tissue activity (synovial and plasma beta 2m levels). Higher amounts of NDOH pro in RA synovial fluid are compatible with the hypothesis of a local connective tissue production as suggested by Uitto et al. on basis of a higher protocollagen proline hydroxylase activity in RA synovial tissue. DOH pro and NBH do not differ significantly in synovial fluid from RA or gouty patients, but the correlations between these forms of OH pro and, respectively, synovial lymphocytes and polymorphonuclear leucocytes are indicative of different processes of connective tissue remodelling in the 2 conditions. Synovial beta 2m levels are a direct function of total synovial lymphocyte counts independently of the type of arthropathy being explored. The ratio of synovial to plasma beta 2m is systematically above unity in RA patients only.     

Phospholipase activity in synovial fluid from patients with rheumatoid arthritis, osteoarthritis and crystal-associated arthritis

Phospholipase activity was assayed in cell-free synovial fluid (SF) from patients with rheumatoid arthritis (RA, n = 28), osteoarthritis (OA, n = 10), and crystal-associated arthritis (C, n = 7) by measuring the release of either [14C]oleic acid or [3H]arachidonic acid from radiolabeled E. coli phospholipids. Activity measured by oleic acid release was not significantly different between the three groups of patients (RA = 571 +/- 43.3, OA = 460 +/- 54.7 and C = 718 +/- 162.6 pmol/min/mg). Arachidonic acid release was significantly (p less than 0.005) less in OA (31 +/- 7.3) than RA (61 +/- 4.7) which was similar to C (58 +/- 17.6 pmol/min/mg). Arachidonic acid release correlated significantly with the SF white blood cell count (r = 0.483, p less than 0.01). This study shows the importance of the type of substrate used to measure phospholipase activity and indicates that differences in the capacity to release arachidonic acid may exist between RA and OA disease states.     

Comparison of blood and synovial fluid lymphocyte subsets in rheumatoid arthritis and osteoarthritis

Summary Immunoregulatory T-cell deficiency is thought to underlie pathogenesis of rheumatoid arthritis (RA) as a systemic autoimmunopathy. The aim of this study was a simultaneous analysis of peripheral blood and synovial lymphocyte subsets (Ly-SS) of RA patients as compared to patients with locally active osteoarthritis (OA). Peripheral blood Ly-SS and paired synovial fluid Ly-SS from 87 RA patients were analysed by two dimensional flow cytometry (Simulset Becton Dickinson) as compared to 15 OA patients. The control group consisted of 32 healthy subjects. The peripheral blood analysis from RA and OA patients revealed a significant decrease of CD8+T-cells and increase of CD4+:CD8+ ratio when compared to the control group. The blood of RA patients showed a significant increase of HLA DR+ and IL 2R+T cells as compared to OA group. The synovial fluid from RA and OA patients showed a significant increase of CD3+, CD8+, HLA DR+ T-cells and decrease of CD4+:CD8+ ratio and CD19+ cells in comparison to the peripheral blood. This study shows, that the OA T-cell system seems not to be activated in peripheral blood in opposition to RA patients. Synovial fluid Ly-SS in OA, however, showed only quantitative but not qualitative differences. OA seems to be mainly a local inflammatory response depending on T-cells, when lymphocyte T activity in blood is diminished.     

Serum and synovial fluid IgG,IgA and IgM antigammaglobulins in rheumatoid arthritis

Antigammaglobulins of IgG, IgA and IgM classes were measured in normal individuals and in patients with osteoarthritis or rheumatoid arthritis. Serum IgG and IgA and synovial fluid IgG antigammaglobulin levels were significantly higher in patients with rheumatoid arthritis than in other individuals, with highest levels occurring in patients with positive latex fixation tests. IgM antigammaglobulins were elevated only in patients with latex positive rheumatoid arthritis. Increased serum levels of IgG, IgA and IgM antigammaglobulins were each associated with clinical findings of severe rheumatoid arthritis. Increased levels of serum and synovial fluid IgG and IgM antigammaglobulins were each associated with diminished serum and synovial fluid complement levels.     

Serum and synovial fluid leptin levels and markers of inflammation in rheumatoid arthritis

This study was designed to investigate the serum and synovial fluid leptin levels, and inflammatory markers in rheumatoid arthritis (RA) patients. Serum and synovial fluid leptin levels were significantly higher (P > 0.05) in RA patients than control group; RA patients with moderate disease activity (DAS < 2.7) having significantly higher leptin levels (P > 0.05) than those with low disease activity (DAS < 2.7). Leukocytes and erythrocyte sedimentation rate (ESR) were found to be significantly higher in moderate disease activity RA group compared to low activity group (P > 0.05, P < 0.001, respectively). Serum leptin level is found to be independent of age and inflammatory markers. ESR is positively correlated with DAS activity and CRP values. Our finding of no correlation between leptin and BMI shows that regulation of leptinemia is complex, and leptin levels cannot be used to assess RA activity.     

Rheumatoid arthritis and osteoarthritis synovial fluid effects on primary human endothelial cell cultures

Since vascular proliferation may be important in the pathogenesis of rheumatoid arthritis (RA) and/or osteoarthritis (OA), this study examined the induction of angiogenesis by these synovial fluids (SF). Four of 11 (36%) RA and 2 of 6 (33%) OA SF caused early morphological changes in human endothelial cell cultures. SF from 7 of 11 (63%) RA and 4 of 8 (50%) OA patients resulted in the late formation of tabular networks morphologically resembling capillaries observed in vivo. Early morphological changes in cultures were associated with a significantly (p less than 0.05) longer duration of disease in patients with RA. Factors present in the SF of RA and OA patients may play a role in the excessive vascularization which often occurs in these arthropathies.     

Detection of stromelysin in synovial fluid and serum from patients with rheumatoid arthritis and osteoarthritis

Summary Stromelysin levels were measured using a one-step sandwich immunoassay in synovial fluid (SF) obtained from 31 patients with rheumatoid arthritis (RA) (31 samples) and 13 patients with osteoarthritis (OA) (13 samples) and in serum from 81 patients with RA (106 samples), 12 with OA (14 samples), 12 with gouty arthritis (gout) (14 samples), and 8 with osteoporosis (OP) (14 samples) to identify differences in the levels in these diseases as well as correlations with clinical parameters in RA. SF stromelysin levels were significantly higher in RA than in OA, and rose with increasing joint destruction in the former. No significant correlations were found between the SF stromelysin level in RA and various clinical parameters, except for the volume of SF which showed a correlation. Serum levels of stromelysin were highest in RA, gout, OA, and osteoporosis in decreasing order, and in RA were correlated with the Steinbrocker Stage. A significant correlation was also found between the serum stromelysin level and number of swollen joints, and correlations with the Lansbury index, ESR, CRP, WBC and Plt. The stromelysin level in SF was thought to be a useful parameter of local joint involvement and that in serum of the severity of systemic joint inflammation.     

Levels of lectin pathway proteins in plasma and synovial fluid of rheumatoid arthritis and osteoarthritis

The innate immune system contributes to the development of rheumatoid arthritis (RA). A potent contributor to such processes is the complement system. The complement system is known to be activated in the inflammatory phases of osteoarthritis (OA). The lectin pathway of the complement system is activated through the recognition of pathogens or altered self-structures by mannan-binding lectin (MBL) or one of the three ficolins in collaboration with MBL-associated serine proteases (MASPs). We assessed the lectin pathway in plasma and synovial fluid (SF) of 27 RA patients and 30 OA patients by measuring MBL, MASP-2, MASP-3, M-ficolin, and H-ficolin. The concentration for all 5 proteins was significantly higher in plasma than in SF (P < 0.001) and the concentration in paired plasma and SF samples correlated in both RA and OA (significance levels between <0.001 and 0.02). The ratio of SF/plasma concentration was for all proteins significantly elevated in RA compared with OA patients (all P < 0.001). The M-ficolin concentration correlated with the neutrophils in both plasma (P = 0.01) and SF (P < 0.001) of RA, and in plasma of 78 controls (P = 0.03). To our knowledge, this is the first report on these proteins in SF, except for MBL where our results are in contrast to the one previous publication. The results support an important physiological role of the neutrophils in determining the M-ficolin levels in both RA and healthy adults. We suggest that quantifications of white blood cells should be included in future clinical investigations of M-ficolin.     

Immunohistologic demonstration of type II collagen in synovial fluid phagocytes of osteoarthritis and rheumatoid arthritis patients

We were able to demonstrate type II collagen in synovial phagocytes of osteoarthritis (OA) and rheumatoid arthritis (RA) patients, using a monoclonal antibody to human type II collagen and immunoperoxidase staining. In addition, using immunoelectron microscopy, we demonstrated labeled fragments in synovial phagocytes of both RA and OA patients. This immunohistochemical assay may prove to be a sensitive indicator of cartilage erosion in patients with OA and RA.     

Characteristics of the protease activity in synovial fluid from patients with rheumatoid arthritis and osteoarthritis.

OBJECTIVE: To clarify which proteases are specifically activated in the lesions of rheumatoid arthritis (RA) and osteoarthritis (OA). METHODS: The activity levels of the serine proteases of the coagulation and fibrinolytic systems, and of elastase and collagenase as controls, in synovial fluid from 27 RA patients and 28 OA patients were measured using fluorogenic synthetic substrates which had methylcoumarylamide (MCA) at their COOH-termini. The thrombin-antithrombin III complex (TAT) content was also measured by ELISA. RESULTS: Among the proteases, thrombin-like activity was the highest in both RA and OA. The profiles of protease activity were similar in RA and OA, but their activities were in general significantly higher in RA than in OA (p < 0.01). The levels of both thrombin-like activity and TAT were about 7.5-fold higher in RA than in OA, while the levels of CRP and fibrinogen were only about 2-fold higher. Biochemical characterization of the thrombin-like activity in the synovial fluid of RA patients showed that this activity was due to thrombin. Thrombin-like activity positively correlated with the TAT concentration in RA (r = 0.750, p < 0.0001), but not in OA. CONCLUSION: Activation of the coagulation system was more marked in RA than in OA, strongly suggesting that in RA there is an imbalance between thrombin and its inhibitors, and that thrombin is more closely linked to the pathogenesis of RA than to that of OA. Our results also show that analysis of the synovial fluid may be useful to estimate the activation of the coagulation system in RA, but not that of the fibrinolytic system.     

Serum and synovial fluid inhibitors of antibody-mediated lymphocytotoxicity in rheumatoid arthritis and systemic lupus erythematosus

Many sera from patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) inhibit lymphocyte-dependent antibody cytotoxicity (LDAC). RA synovial fluids also inhibit LDAC. RA serum inhibition was present in high molecular weight and 5S serum fractions, whereas in SLE it was confined to 7S fractions. A correlation between rheumatoid factor activity and LDAC inhibition was noted, and there was some evidence for inhibition of SLE serum acting on effector cells. Inhibition in RA synovial fluid was found in both high molecular weight and very low molecular weight fractions (<4S).     

Hydroxypyridinium collagen crosslinks in serum,urine, synovial fluid and synovial tissue in patients with rheumatoid arthritis compared with osteoarthritis

OBJECTIVE: To investigate the relationship between inflammation markers and content of pyridinium crosslinks in hydrolysates of synovial tissue and to specify the significance of urinary excreted pyridinoline, released primarily from collagen I and II of bone and cartilage, and deoxypyridinoline released especially from collagen I of bone and dentin, dependent on disease activity in rheumatoid arthritis (RA). METHODS: Synovial tissue and fluid from knee endoprosthesis surgery, as well as simultaneously obtained serum and urine, were collected from 12 patients with inactive RA or RA with low disease activity [iRA: C-reactive protein (CRP) <28 mg/l], 10 with active RA (aRA: CRP > or =28 mg/l) and 21 with OA. After preparation of the synovial tissue, including hydrolysis, completely released synovial pyridinoline and deoxypyridinoline crosslinks as well as those from synovial fluid, serum and urine were investigated using a gradient ion-paired reversed-phase HPLC method. Crosslink levels in synovial tissue are expressed as mol/mol collagen, assuming 300 residues of hydroxyproline per collagen molecule, also measured by HPLC. RESULTS: In the synovial tissue of aRA patients we found significantly elevated total pyridinoline concentrations and pyridinoline/deoxypyridinoline (Pyr/Dpyr) quotients compared with the iRA and OA controls, indicating an elevated crosslinking density of mature synovial tissue collagen with increased activity of RA. Pyridinoline levels and the Pyr/Dpyr ratio were correlated with those of urine and with acute-phase reactants in RA patients. Compared with serum crosslink levels, which were unrelated to disease activity, the urinary concentration of pyridinoline was increased by a factor of 2 and showed a simultaneous increase with increasing synovitis. CONCLUSION: Both crosslinking density and degradation of mature collagen from synovial tissue depend on the disease activity in RA. Urinary excretion of associated crosslinks, expressed as the Pyr/Dpyr ratio, correlates with those in synovial tissue and may be confirmed as a marker of synovial tissue collagen degradation. We suggest that increased crosslinking of mature collagen in the synovial tissue of RA is related to an inflammation-dependent regulation of collagen synthesis in activated synovial fibroblasts, in which lysyl oxidase represents the final enzymatic step for crosslinking.     

Resistin in rheumatoid arthritis synovial tissue, synovial fluid and serum

BACKGROUND: Resistin is a newly identified adipocytokine which has demonstrated links between obesity and insulin resistance in rodents. In humans, proinflammatory properties of resistin are superior to its insulin resistance-inducing effects. OBJECTIVES: To assess resistin expression in synovial tissues, serum and synovial fluid from patients with rheumatoid arthritis, osteoarthritis and spondylarthropathies (SpA), and to study its relationship with inflammatory status and rheumatoid arthritis disease activity. METHODS: Resistin expression and localisation in synovial tissue was determined by immunohistochemistry and confocal microscopy. Serum and synovial fluid resistin, leptin, interleukin (IL)1beta, IL6, IL8, tumour necrosis factor alpha, and monocyte chemoattractant protein-1 levels were measured. The clinical activity of patients with rheumatoid arthritis was assessed according to the 28 joint count Disease Activity Score (DAS28). RESULTS: Resistin was detected in the synovium in both rheumatoid arthritis and osteoarthritis. Staining in the sublining layer was more intensive in patients with rheumatoid arthritis compared with those with osteoarthritis. In rheumatoid arthritis, macrophages (CD68), B lymphocytes (CD20) and plasma cells (CD138) but not T lymphocytes (CD3) showed colocalisation with resistin. Synovial fluid resistin was higher in patients with rheumatoid arthritis than in those with SpA or osteoarthritis (both p<0.001). In patients with rheumatoid arthritis and SpA, serum resistin levels were higher than those with osteoarthritis (p<0.01). Increased serum resistin in patients with rheumatoid arthritis correlated with both CRP (r=0.53, p<0.02), and DAS28 (r=0.44, p<0.05), but not with selected (adipo) cytokines. CONCLUSION: The upregulated resistin at local sites of inflammation and the link between serum resistin, inflammation and disease activity suggest a role for resistin in the pathogenesis of rheumatoid arthritis.     

Serum and synovial cartilage oligomeric matrix protein (COMP) in patients with rheumatoid arthritis and osteoarthritis

ObjectiveTo measure serum and synovial COMP levels in rheumatoid arthritis (RA) and osteoarthritis (OA) patients and to assess their correlation with clinical, laboratory and ultrasonographic parameters.MethodsTwo groups of patients were included in this study consisting of 32 patients with RA and 10 patients with knee OA. Ultrasonography of knee joints was performed and serum and synovial Cartilage oligomeric matrix protein (COMP) levels were measured using an inhibition ELISA.ResultsThe mean synovial COMP level was significantly higher in RA compared to OA patients (14.3 ± 5.19μg/mL and 9.26 ±2.42 μg/mL respectively, P< 0.01). Amongst RA patients, it was higher in those with erosions. COMP levels were higher in synovial fluid compared to serum levels in both groups (P <0.01). Amongst RA patients, synovial COMP levels showed a significant positive correlation with synovial membrane thickness on ultrasonography (P <0.001), and significant negative correlation with the cartilage thickness (P <0.001). In OA group, synovial and serum COMP level showed significant positive correlation with WOMAC index for the lower limbs (r= 0.64, P < 0.05, and r=0.92, P <0.001 respectively) and a significant negative correlation with cartilage thickness (P <0.001).ConclusionThe synovial COMP and ultrasonographic joint evaluation may be considered as markers of disease activity and cartilage destruction in both RA and OA patients.