The contribution of synovial fluid lipoproteins to the chronic synovitis of rheumatoid arthritis

AK106-001616, a Potent and Selective Inhibitor of Cytosolic Phospholipase A2: In Vivo Efficacy for Inflammation, Neuropathic Pain, and Pulmonary Fibrosis

3-[3-Amino-4-(indan-2-yloxy)-5-(1-methyl-1H-indazol-5-yl)-phenyl]-propionic acid (AK106-001616) is a novel, potent, and selective inhibitor of the cytosolic phospholipase A2 (cPLA2) enzyme. Unlike traditional nonsteroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors, AK106-001616 reduced prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) production by stimulated cells. The suppression of PGE2 and LTB4 production was also confirmed using an air pouch model in rats administered a single oral dose of AK106-001616. AK106-001616 alleviated paw swelling in a rat adjuvant-induced arthritis (AIA) model. The maximum effect of the inhibitory effect of AK106-001616 was comparable with that of naproxen on paw swelling in a rat AIA model. Meanwhile, the inhibitory effect of AK106-001616 was more effective than that of naproxen in the mouse collagen antibody-induced arthritis model with leukotrienes contributing to the pathogenesis. AK106-001616 dose dependently reversed the decrease in paw withdrawal threshold not only in rat carrageenan-induced hyperalgesia, but also in a rat neuropathic pain model induced by sciatic nerve chronic constriction injury (CCI). However, naproxen and celecoxib did not reverse the decrease in the paw withdrawal threshold in the CCI model. Furthermore, AK106-001616 reduced the disease score of bleomycin-induced lung fibrosis in rats. In addition, AK106-001616 did not enhance aspirin-induced gastric damage in fasted rats, increase blood pressure, or increase the thromboxane A2/ prostaglandin I2 ratio that is thought to be an underlying mechanism of thrombotic cardiovascular events increased by selective cyclooxygenase-2 inhibitors. Taken together, these data demonstrate that oral AK106-001616 may provide valuable effects for wide indications without attendant gastrointestinal and cardiovascular risks.

In vivo H1 MR spectroscopy using 3 Tesla to investigate the metabolic profiles of joint fluids in different types of knee diseases

In vivo proton (H1) magnetic resonance spectroscopy (MRS) has not yet been systematically used to study joint fluids in human knees. The objective of this study, therefore, was to assess the ability of proton MRS to identify the apparent heterogeneous characteristics of metabolic spectra in the joint fluid regions in human knees using a high‐field MRI system. Eighty‐four patients with effusion lesions who were referred for routine knee MR imaging underwent proton MRS with point‐resolved, single‐voxel MR spectroscopy using a clinical 3.0 Tesla MRI system. Thirty‐eight patients were confirmed to have the following: degenerative osteoarthritis, 21 patients (Group 1); traumatic diseases, 12 patients (Group 2); infectious diseases, 4 patients and an inflammatory disease, 1 patient (Group 3). Spectroscopy data were analyzed using the public jMRUI freeware software to obtain lipid metabolites. Nonparametric statistical comparisons were performed to investigate any differences in metabolites among the three disease groups. The major metabolites were vinylic CH=CH lipids around 5.1−5.5 ppm, CH2 lipids around 1.1−1.5 ppm, and CH3 lipids around 0.7−1.0 ppm. Each patient had either a CH=CH lipid peak, CH2 and CH3 lipid peaks, or all three peaks. There were no significant differences among the three groups for the CH3 (p=0.9019), CH2 (p=0.6406), and CH=CH lipids (p=0.5467) and water (p=0.2853); none of the metabolites could differentiate between any of the three types of diseases. The CH2 lipids in the 38 patients who had confirmed fluid characteristics were significantly correlated with CH3 lipids (rho=0.835, p<0.0001). The ratio of CH3 to CH2 was highest in the degenerative disease. In both the degenerative and traumatic diseases, metabolite peaks of the vinylic CH=CH lipids around 5.1−5.5 ppm and of the sum of the CH2 and CH3 lipids around 0.7−1.5 ppm were observed, but in the infectious disease, only a metabolite peak of the sum of the CH2 and CH3 lipids was detected. Although none of the metabolites could statistically significantly differentiate between the three types of diseases, the different lipid metabolite peaks and their ratios in the three disease groups may give us a hint at the different mechanisms of joint fluids in the infectious, degenerative, and traumatic diseases.

PACS number(s): 87.61.Ff, 33.25.+k, 87.14.Cc

A lipidomic study of phospholipid classes and species in human synovial fluid

OBJECTIVE

Membrane phospholipid species contribute to boundary lubrication that is provided by synovial fluid (SF). Altered levels of lubricants can be associated with increased friction, leading to articular cartilage damage. This study was undertaken to determine whether the composition of phospholipid species is altered in diseases of human knee joints.

METHODS

The study was performed using SF from unaffected controls and patients with early osteoarthritis (OA), late OA, or rheumatoid arthritis (RA). Lipids were extracted from cell- and vesicle-free SF from 9 control donors postmortem and from 17 patients with early OA, 13 patients with late OA, and 18 patients with RA. Phospholipid species were quantified by electrospray ionization tandem mass spectrometry.

RESULTS

We conducted lipidomic analysis to provide the first detailed overview of phospholipid species in human SF. We identified 130 lipid species belonging to 8 lipid classes (phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, plasmalogens, phosphatidylserine, phosphatidylglycerol, sphingomyelin, and ceramide). Compared to SF from controls, SF from patients with early OA and those with late OA had higher levels of most phospholipid species. Moreover, the concentrations of 64 and 27 phospholipids differed between RA and early OA SF and between RA and late OA SF, respectively. Also, the levels of 66 phospholipid species were altered in early OA versus late OA.

CONCLUSION

Our data indicate disease- and stage-dependent differences in the relative composition and levels of phospholipid species in human SF. Such alterations might affect articular joint lubrication. Because certain phospholipids scavenge reactive oxygen species (ROS) and are pro- or antiinflammatory, any altered phospholipid level might influence ROS-scavenging activity of SF and the inflammatory status of joints. Thus, phospholipids may be associated with the pathogenesis of OA.

Protective effects of ginger-turmeric rhizomes mixture on joint inflammation, atherogenesis, kidney dysfunction and other complications in a rat model of human rheumatoid arthritis

AIM

Besides joint destruction, extra-articular complications (outside the locomotor system) are frequent in rheumatoid arthritis (RA) patients, especially cardiovascular, hematological and metabolic disorders. Here, we evaluated and compared the protective activity of two different doses of mixture of ginger and turmeric rhizomes powder (1 : 1) suspended in distilled water (GTaq) in alleviating both articular and extra-articular manifestations in rat adjuvant-induced arthritis (AIA).

METHODS

Arthritis was induced by a single intra-dermal injection of 0.1 mL of Complete Freund's adjuvant (containing heat-killed Mycobacterium tuberculosis) into the palmar surface of the left hind paw after the rats were subjected to light diethyl ether anesthesia. Arthritic rats received orally and daily (for 28 consecutive days) distilled water as vehicle, indomethacin (1.0 mg/kg body weight), or GTaq (200 or 400 mg/kg body weight) from the day of arthritis induction.

RESULTS

The present study showed that GTaq (especially the high dose) was more effective (4.2-38.4% higher, P < 0.05-0.001) than indomethacin (a non-steroidal/anti-inflammatory drug) in alleviating the loss in body weight gain, the histopathological changes observed in ankle joints, blood leukocytosis and thrombocytosis, iron deficiency anemia, serum hypoalbuminemia and globulinemia, the impairment of kidney functions, and the risks for cardiovascular disease in arthritic rats. These protective effects of GTaq were mediated through increasing the food intake and decreasing the systemic inflammation that occur at the appearance of polyarthritis, oxidative stress and dyslipidemia.

CONCLUSION

Ginger-turmeric rhizomes mixture may be effective against RA severity and complications as shown in an AIA rat model.

Interleukin-6 and soluble interleukin-6 receptor suppress osteoclastic differentiation by inducing PGE(2) production in chondrocytes

This study examined how interleukin-6 (IL-6) and soluble IL-6 receptor (sIL-6r) influence osteoclastic differentiation through the function of chondrocytes. Chondrocytes were cultured with or without IL-6 and/or sIL-6r in the presence or absence of NS398, a specific inhibitor of cyclooxygenase (COX)-2, for up to 28 days. Chondrocytes were also cultured with or without IL-6 and sIL-6r for 28 days, and the conditioned medium from cells cultured without IL-6 and sIL-6r was used to induce differentiation of RAW264.7 cells into osteoclast precursors. Osteoclastic differentiation was assessed by tartrate-resistant acid phosphatase (TRAP) staining. Expression of osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL), COX-2, and prostaglandin E(2) (PGE(2)) increased in cells exposed to IL-6 and sIL-6r, whereas expression of macrophage colony-stimulating factor (M-CSF) and bone resorption-related enzymes decreased. NS398 blocked the stimulatory/suppressive effects of IL-6 and sIL-6r on the expression of OPG, RANKL, and M-CSF. Fewer TRAP-positive multinucleated cells were detected after treatment with conditioned medium from IL-6- and sIL-6r-treated chondrocytes than after treatment with conditioned medium from untreated chondrocytes. These results suggest that IL-6 and sIL-6r interfere with osteoclast function through the involvement of chondrocytes. Specifically, they appear to suppress the differentiation of osteoclast precursors into osteoclasts by inducing chondrocytic PGE(2) production, which, in turn, increases OPG secretion and decreases M-CSF secretion by chondrocytes.

IL-1beta stimulates the expression of prostaglandin receptor EP4 in human chondrocytes by increasing production of prostaglandin E2

Prostaglandin (PG) E(2), which exerts its actions via the PG receptors EP1-4, is produced from arachidonic acid by cyclooxygenase (COX)-1 and COX-2. The aim of this study was to investigate the mechanisms by which interleukin (IL)-1beta induces the expression of PG receptors in cultured human chondrocytes and to explore the role of PGE(2) in this process. The cells were cultured with 0, 10, or 100 U/mL IL-1beta with or without 1 muM celecoxib, a specific inhibitor of COX-2, for up to 28 days. Expression of the genes encoding COX-1, COX-2, and EP1-4 was quantified using real-time PCR, and expression of the corresponding proteins was examined using immunohistochemical staining. PGE(2) production was determined using ELISA. IL-1beta treatment caused a marked dose- and time-dependent increase in the levels of PGE(2), COX-2, and EP4 as compared with the untreated control. It did not affect the expression of COX-1, and it decreased the expression of EP1 and EP2. EP3 expression was not detected in either the absence or the presence of IL-1beta. When celecoxib was also present, IL-1beta failed to stimulate PGE(2) production and EP4 expression, but its stimulatory effect on COX-2 expression and its inhibitory effect on EP1 and EP2 expression were unchanged. IL-1beta increases the production of PGE(2), COX-2, and the PG receptor EP4 in cultured human chondrocytes. The increase in EP4 expression appears to be a result of the increased PGE(2) production.

Salubrious effect of Kalpaamruthaa, a modified indigenous preparation in adjuvant-induced arthritis in rats--a biochemical approach

BACKGROUND

Interactions between the phytochemicals and drugs and their combinations are capable of providing longer remissions and perhaps a complete cure for many diseases including rheumatoid arthritis (RA). In addition to articular manifestations in RA, extra-articular signs involving reticuloendothelial and hepatic systems are an indication of more severe disease and thus, have prognostic value.

OBJECTIVES

The present study was designed to illustrate the beneficial outcome of the drug Kalpaamruthaa (constituting Semecarpus anacardium nut milk extract, fresh dried powder of Emblica officinalis fruit and honey) in adjuvant-induced arthritic rat model with respect to the changes in extra-articular manifestation involving hematological and cellular constituents.

MATERIAL AND METHODS

Levels of hematological parameters, cellular constituents, activities of marker enzymes and the level of DNA damage were assessed in control, arthritis-induced, SA, KA and drug control treated rats.

RESULTS AND CONCLUSION

Significant decrease (p<0.005) in the levels of Hb, RBC, PCV, total protein, albumin, A/G ratio, plasma uric acid, urinary urea, uric acid, creatinine, FFA, HDL and significant increase (p<0.05) in the levels of WBC, platelet count, ESR, globulin, plasma creatinine, blood glucose, urea, AST, ALT, ALP, TC, FC, TG, PL, LDL and VLDL were observed in arthritic rats. No other significant change was observed in tissue DNA and RNA levels of control and experimental animals. On the contrary an increase in DNA damage was observed in arthritic rats when compared to control animals. The above said derangements were brought back to near normal levels upon SA and KA treatments and KA revealed a profound beneficial effect than SA. The enhanced effect of KA might be attributed to the combined effects of phytoconstituents such as flavonoids, tannins and other compounds such as vitamin C present in KA. Thus KA via this preliminary protective effect might contribute to the amelioration of the disease process.

Activity and potential role of licofelone in the management of osteoarthritis

Osteoarthritis is the most common form of arthritis. It is a progressive joint disease associated with aging. It may be found in the knees, hips, or other joints. It is estimated that costs associated with osteoarthritis exceed 2% of the gross national product in developed countries. Nonsteroidal anti-inflammatory drugs (NSAIDs) are a mainstay in the treatment of inflammatory disease and are among the most widely used drugs worldwide. The main limitation in using NSAIDs consists in their side-effects, including gastrointestinal ulcerogenic activity and bronchospasm. The mechanism of action of these drugs is attributed to the inhibition of cyclooxygenase (COX), and, consequently, the conversion of arachidonic acid into prostaglandins. It is hypothesized that the undesirable side-effects of NSAIDs are due to the inhibition of COX-1 (constitutive isoform), whereas the beneficial effects are related to the inhibition of COX-2 (inducible isoform). Arachidonic acid can also be converted to leukotrienes (LTs) by the action of 5-lipoxygenase (5-LOX). Licofelone, a LOX/COX competitive inhibitor, decreases the production of proinflammatory leukotrienes and prostaglandins (which are involved in the pathophysiology of osteoarthritis and in gastrointestinal (GI) damage induced by NSAIDs) and has the potential to combine good analgesic and anti-inflammatory effects with excellent GI tolerability. Preliminary data with this drug seem promising, but further well-designed clinical trials of this agent in the elderly will be necessary before a final evaluation is possible.

The protective effect of licofelone on experimental osteoarthritis is correlated with the downregulation of gene expression and protein synthesis of several major cartilage catabolic factors: MMP-13, cathepsin K and aggrecanases

This study sought to evaluate the levels of mRNA expression and protein synthesis of MMP-13, cathepsin K, aggrecanase-1 (ADAMTS-4), aggrecanase-2 (ADAMTS-5) and 5-lipoxygenase (5-LOX) in cartilage in the experimental anterior cruciate ligament (ACL) dog model of osteoarthritis (OA), and to examine the effects of treatment with licofelone, a 5-lipoxygenase (LOX)/cyclooxygenase (COX) inhibitor, on the levels of these catabolic factors. Sectioning of the ACL of the right knee was performed in three experimental groups: group 1 received no active treatment (placebo group); and groups 2 and 3 received therapeutic concentrations of licofelone (2.5 or 5.0 mg/kg/day orally, respectively) for 8 weeks, beginning the day following surgery. A fourth group consisted of untreated dogs that were used as normal controls. Specimens of cartilage were selected from lesional areas of OA femoral condyles and tibial plateaus, and were processed for real-time quantitative PCR and immunohistochemical analyses. The levels of MMP-13, cathepsin K, ADAMTS-4, ADAMTS-5 and 5-LOX were found to be significantly increased in OA cartilage. Licofelone treatment decreased the levels of both mRNA expression and protein synthesis of the factors studied. Of note was the marked reduction in the level of 5-LOX gene expression. The effects of the drug were about the same at both tested dosages. In vivo treatment with therapeutic dosages of licofelone has been found to reduce the degradation of OA cartilage in experimental OA. This, coupled with the results of the present study, indicates that the effects of licofelone are mediated by the inhibition of the major cartilage catabolic pathways involved in the destruction of cartilage matrix macromolecules. Moreover, our findings also indicate the possible auto-regulation of 5-LOX gene expression by licofelone in OA cartilage.

Altered pattern of lipids in plasma and erythrocyte membranes of rheumatoid arthritis patients

The present study has investigated the levels of lipids, lipoprotein cholesterol (HDL and LDL cholesterol), thiobarbituric acid reactive substances (TBARS) and vitamin E in plasma and erythrocyte membranes of twenty two clinically diagnosed adult rheumatoid arthritis patients and an equal number of age matched healthy subjects. The levels of lipids and lipoprotein cholesterol were markedly reduced in patients with rheumatoid arthritis as compared to healthy subjects. The altered lipid pattern may be related to decreased lipoprotein cholesterol, fatty acids and impairment in antioxidant defence mechanism.

Divergent roles of nitrergic and prostanoid pathways in chronic joint inflammation

BACKGROUND

Nitrergic and prostanoid pathways have both been implicated in inflammatory processes.

OBJECTIVE

To investigate their respective contributions in a rat model of chronic arthritis.

METHODS

Male Wistar rats (n = 4-6/group) received either an intra-articular injection of 2% carrageenan/4% kaolin (C/K) or intra- and periarticular injections of Freund's complete adjuvant (FCA; 10 mg/ml M tuberculosis). Joint diameter, urinary nitric oxide metabolites (NO(x)), and prostaglandin E(2) (PGE(2)) levels were measured as indices of the inflammatory process. A prophylactic and therapeutic (day 5) dose ranging study of an inducible nitric oxide synthase inhibitor, L-N-(1-iminoethyl)-lysine (L-NIL), and a cyclo-oxygenase-2 (COX-2) inhibitor, SC-236, was performed with the drugs given subcutaneously. Submaximal doses were identified and used for combination studies. Appropriate vehicle controls were included.

RESULTS

L-NIL and SC-236 dose dependently inhibited C/K induced acute joint swelling, the magnitude being greatest when they were given in combination. Both prophylactic and therapeutic administration of SC-236 in the FCA induced model of chronic arthritis produced a dose dependent reduction in all the measures assessed. However, although L-NIL demonstrated similar dose dependent inhibition of urinary NO(x) and PGE(2) levels, joint swelling was significantly exacerbated in this model. Co-administration of the inhibitors nullified the benefits of SC-236.

CONCLUSION

Whereas COX-2 derived prostaglandins are proinflammatory in both acute and chronic joint inflammation, NO seems to have divergent roles, being anti-inflammatory in chronic and proinflammatory in acute joint inflammation.

Lectin-like oxidized low-density lipoprotein receptor 1 mediates matrix metalloproteinase 3 synthesis enhanced by oxidized low-density lipoprotein in rheumatoid arthritis cartilage

OBJECTIVE

To investigate for the presence of oxidized low-density lipoprotein (ox-LDL) and lectin-like oxidized LDL receptor 1 (LOX-1) in cartilage specimens from rheumatoid arthritis (RA) joints and to determine whether the interaction of ox-LDL with LOX-1 can induce matrix metalloproteinase 3 (MMP-3) in articular cartilage explant culture.

METHODS

Human articular cartilage specimens obtained from patients with RA, osteoarthritis (OA), and femoral neck fractures were examined for LOX-1 and ox-LDL by confocal fluorescence microscopy. The association between ox-LDL and LOX-1 was evaluated by immunofluorescence analysis. Articular cartilage specimens from patients with femoral neck fractures were incubated with ox-LDL, with or without preincubation with neutralizing anti-LOX-1 antibody. MMP-3 synthesis by chondrocytes in explant cartilage was evaluated by immunofluorescence, and protein secretion into conditioned medium was monitored by immunoblotting and enzyme-linked immunosorbent assay.

RESULTS

The majority of the RA chondrocytes stained positively with both anti-LOX-1 and anti-ox-LDL antibodies; however, no positive cells were found in OA and normal cartilage specimens. Anti-LOX-1 antibody suppressed the binding of DiI-labeled ox-LDL to chondrocytes in explant culture, suggesting that the interaction was mediated by LOX-1. In contrast to native LDL, ox-LDL induced MMP-3 synthesis by articular chondrocytes in association with the induction of LOX-1, which resulted in enhanced secretion of MMP-3 into the culture medium. Anti-LOX-1 antibody reversed ox-LDL-stimulated MMP-3 synthesis to control levels.

CONCLUSION

Ox-LDL, principally mediated by LOX-1, enhanced MMP-3 production in articular chondrocytes. Increased accumulation of ox-LDL with elevated expression of LOX-1 in RA cartilage indicates a specific role of the receptor-ligand interaction in cartilage pathology in RA.

Plasma apolipoprotein(a) co-deposits with fibrin in inflammatory arthritic joints

Extravascular coagulation and diminished fibrinolysis are processes that contribute to the pathology of both inflammatory arthritis and atherosclerosis. We hypothesized that, given its homology with plasminogen, apolipoprotein (apo) (a), the distinctive glycoprotein of the atherogenic lipoprotein (Lp) (a), may be equally implicated in inflammatory arthritis. We detected the presence of apo(a) as part of Lp(a) in human arthritic synovial fluid. The abundance of apo(a) in synovial fluid rose in proportion to plasma apo(a) levels and was higher in inflammatory arthritides than in osteoarthritis. In addition, apo(a) immunoreactive material, but not apo(a) transcripts, was detected in inflammatory arthritic synovial tissues. These data indicated that synovial fluid apo(a) originates from circulating Lp(a) and that diffusion of Lp(a) through synovial tissue is facilitated in inflammatory types of arthritis. In synovial tissues, apo(a) co-localized with fibrin. These observations could be reproduced in a model of antigen-induced arthritis, using transgenic mice expressing human Lp(a). Although in this mouse model the presence of apo(a) did not change the severity of arthritis, the co-localization of apo(a) with fibrin in synovial tissue suggests that, in humans, apo(a) may modulate locally the fibrinolytic activity and may thus contribute to the persistence of intra-articular fibrin in inflammatory arthritis.

In vivo dual inhibition of cyclooxygenase and lipoxygenase by ML-3000 reduces the progression of experimental osteoarthritis: suppression of collagenase 1 and interleukin-1beta synthesis

OBJECTIVE

To study the therapeutic effectiveness of ML-3000, a new antiinflammatory drug that has balanced dual inhibitory activity against 5-lipoxygenase and cyclooxygenase, on the development of lesions in the experimental osteoarthritis (OA) dog model, and to determine the action of ML-3000 on the synthesis of collagenase 1 in cartilage and interleukin-1beta (IL-1beta) in synovial membrane.

METHODS

The anterior cruciate ligament of the right stifle joint of 21 mongrel dogs was sectioned with a stab wound. Dogs were divided into 3 groups: group 1 (n = 7) received placebo; groups 2 (n = 7) and 3 (n = 7) were treated with therapeutic dosages of oral ML-3000 at 2.5 mg/kg/day and 5 mg/kg/day, respectively. The dogs began receiving medication the day after surgery and were killed 8 weeks later. The size and grade of cartilage erosions on both the condyles and plateaus were evaluated, and the severity of the cartilage lesions and synovial inflammation was examined histologically. Levels of collagenase 1 in cartilage and IL-1beta in the synovial membrane were measured by immunohistochemistry. In addition, levels of prostaglandin E2 (PGE2) in the synovial fluid and leukotriene B4 (LTB4) in cultured synovial membrane explants were determined using specific enzyme immunoassays.

RESULTS

Serum levels of ML-3000 in treated dogs were within the therapeutic range. ML-3000 significantly decreased the size and grade of the cartilage lesions in tibials and plateaus, compared with placebo. At the histologic level, the severity of cartilage lesions was also decreased in the ML-3000-treated dogs versus the placebo-treated dogs in both the condyles and the plateaus. All 3 OA groups exhibited a notable and similar level of synovial inflammation. ML-3000 significantly decreased the level of PGE2 in synovial fluid and LTB4 production by synovium. It also markedly reduced the levels of collagenase 1 in cartilage and IL-1beta in synovial membrane.

CONCLUSION

ML-3000 significantly reduced the development of lesions in experimental dog OA. The drug acts by reducing the synthesis of the inflammation mediators PGE2 and LTB4 and catabolic factors such as collagenase 1 and IL-1beta, which are known to play an important role in the pathophysiology of OA lesions. The effect of the drug on catabolic factors could possibly be related to its inhibitory action on LTB4 synthesis.

Prostaglandin E2 in temporomandibular joint synovial fluid and its relation to pain and inflammatory disorders

PURPOSE

The aim of this study was to investigate temporomandibular joint (TMJ) synovial fluid (SF) levels of prostaglandin E2 and its relation to general inflammatory activity and its influence on specific TMJ pain in patients with inflammatory TMJ disorders.

PATIENTS AND METHODS

The study comprised 24 patients (30 joints) with inflammatory TMJ disorders and 4 healthy persons (6 joints). TMJ pain at rest, tenderness to palpation of the TMJ, and TMJ pressure pain threshold, as well as pain during joint movements (PM), were assessed. PGE2 levels were analyzed in synovial fluid samples (SF-PGE2) and blood plasma (P-PGE2). The erythrocyte sedimentation rate (B-ESR) as well as the serum levels of C-reactive protein (S-CRP) and antinuclear antibodies were determined.

RESULTS

PGE2 was undetectable in the plasma and in the TMJ SF of the healthy persons. In the patients, PGE2 was detectable in 20 of the 30 (67%) SF samples. SF-PGE2 was significantly and positively correlated to PM in the patients. There were significant correlations between P-PGE2 and B-ESR as well as the S-CRP.

CONCLUSIONS

This study shows that the synovial fluid in patients with TMJ inflammatory disorders frequently has a detectable level of PGE2 that is related to TMJ allodynia. The plasma levels of PGE2 seem to be related to the general inflammatory activity in these patients.