Determination of interleukin-1 receptor antagonist, interleukin-10, and transforming growth factor-beta1 in synovial fluid aspirates of patients with temporomandibular disorders

Growth factors that drive aggrecan synthesis in healthy articular cartilage. Role for transforming growth factor-β?

Introduction

Articular cartilage makes smooth movement possible and destruction of this tissue leads to loss of joint function. An important biomolecule that determines this function is the large aggregating proteoglycan of cartilage, aggrecan. Aggrecan has a relatively short half-life in cartilage and therefore continuous production of this molecule is essential.

Methods

In this narrative review we discuss what is the role of growth factors in driving the synthesis of aggrecan in articular cartilage. A literature search has been done using the search items; cartilage, aggrecan, explant, Transforming Growth factor-β (TGF-β), Insulin-like Growth Factor (IGF), Bone Morphogenetic Protein (BMP) and the generic term "growth factors". Focus has been on studies using healthy cartilage and models of cartilage regeneration have been excluded.

Results

In healthy adult articular cartilage IGF is the main factor that drives aggrecan synthesis and maintains adequate levels of production. BMP's and TGF-β have a very limited role but appear to be more important during chondrogenesis and cartilage development. The major role of TGF-β is not stimulation of aggrecan synthesis but maintenance of the differentiated articular cartilage chondrocyte phenotype.

Conclusion

TGF-β is a factor that is generally considered as an important factor in stimulating aggrecan synthesis in cartilage but its role in this might be very restrained in healthy, adult articular cartilage.

Evaluation of aggrecan and adipokine levels in temporomandibular joint synovial fluid

The aim of this study was to investigate the effect various mediators in synovial fluid (SF) on the pathogenesis of temporomandibular disorders (TMD) and to evaluate the relationship between clinical and radiological features of temporomandibular joint (TMJ) diseases. Patients who had received SF sample during arthrocentesis because of TMD were included in this study. Clinical and radiological records were evaluated retrospectively. Enzyme-Linked ImmunoSorbent Assay (ELISA) method was used for analysis of aggrecan, adiponectin, resistin, apelin, Vascular Endothelial Growth Factor (VEGF) and Prostaglandin E2 (PGE2) in SFs. 59 joints of 41 patients were included in the study. Anterior disc displacement with reduction (ADDwR) was detected in 22 joints, anterior disc displacement without reduction (ADDwoR) was detected in 29 joints and osteoarthritis (OA) in 8. In OA group, PGE2 level was significantly higher than the other groups (p = 0.029). Aggrecan and PGE2 levels were statistically higher in joints with localized pain (p = 0.030, p = 0.029). The aggrecan level was statistically significant higher in patients who had degenerative changes in radiological examinations (p = 0.044). Resistin was correlated with PGE2 and aggrecan (p = 0.011), and apelin showed positive correlation with VEGF (p˂0.001). The detection of aggrecan and adipokines in SF may be a precursor of degenerative joint disease and it should be taken into account that the presence of localized pain in the joint area may be an early sign of degenerative changes.

Metalloelastase-12 is involved in the temporomandibular joint inflammatory response as well as cartilage degradation by aggrecanases in STR/Ort mice

Temporomandibular joint dysfunction (TMJD) is characterised by clinical symptoms involving both the masticatory muscles and the temporomandibular joint (TMJ). Disc internal derangement and osteoarthritis (OA) are the most common forms of TMJD. Currently, the molecular process associated with degenerative changes in the TMJ is unclear. Our previous study showed that elastin-digested peptides act on human TMJ synovial cells and lead to upregulation of interleukin-6 (IL-6) and metalloelastase-12 (MMP-12; an elastin-degrading enzyme) in vitro. However, there is limited information regarding the involvement of elastin-degradation by MMP-12 in the processes of inflammatory responses and cartilage degradation in vivo. STR/Ort mice were used as a model of TMJ OA in the present study. Significant articular cartilage degeneration was observed starting at 20 weeks of age in the STR/Ort mice and this progressed gradually until 40 weeks, compared with the age-matched CBA mice. Immunostaining analysis showed that MMP-12 and IL-6 were expressed in the chondrocytes in the superficial zones of the cartilage. Immunostaining also showed that aggrecanases [a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4 and ADAMTS-5] were expressed in the chondrocytes in the superficial zones of the cartilage. These findings suggest that an inflammatory and degradative process was initiated in the TMJ. Harmful mechanical stimuli, particularly pressure, may cause damage to the elastin fibres in the most elastin-rich superficial layer of the articular cartilage. Elastin-digested peptides are then generated as endogenous warning signals and they initiate a pro-inflammatory cascade. This leads to upregulation of pro-inflammatory mediators, such as IL-6 and MMP-12, which further trigger tissue damage resulting in elevated levels of elastin-digested peptides. IL-6 increases expression of the aggrecanases ADAMTS-4 and ADAMTS-5, following cartilage degradation. This leads to the establishment of a positive feedback loop and may result in chronic inflammation and cartilage degradation of the TMJ in vivo.

Ahmad WMA, Ahmed Asif J, Khoo SP, Husein A, Ab-Ghani Z, Kassim NK. Biomarkers for Temporomandibular Disorders: Current Status and Future Directions

Numerous studies have been conducted in the previous years with an objective to determine the ideal biomarker or set of biomarkers in temporomandibular disorders (TMDs). It was recorded that tumour necrosis factor (TNF), interleukin 8 (IL-8), IL-6, and IL-1 were the most common biomarkers of TMDs. As of recently, although the research on TMDs biomarkers still aims to find more diagnostic agents, no recent study employs the biomarker as a targeting point of pharmacotherapy to suppress the inflammatory responses. This article represents an explicit review on the biomarkers of TMDs that have been discovered so far and provides possible future directions towards further research on these biomarkers. The potential implementation of the interactions of TNF with its receptor 2 (TNFR2) in the inflammatory process has been interpreted, and thus, this review presents a new hypothesis towards suppression of the inflammatory response using TNFR2-agonist. Subsequently, this hypothesis could be explored as a potential pain elimination approach in patients with TMDs.

Development of a simple osteoarthritis model useful to predict in vitro the anti-hypertrophic action of drugs

Osteoarthritis (OA) is characterized by cartilage degradation, inflammation, and hypertrophy. Therapies are mainly symptomatic and aim to manage pain. Consequently, medical community is waiting for new treatments able to reduce OA process. This study aims to develop an in vitro simple OA model useful to predict drug ability to reduce cartilage hypertrophy. Human primary OA chondrocytes were incubated with transforming growth factor beta 1 (TGF-β1). Hypertrophy was evaluated by Runx2, type X collagen, MMP13, and VEGF expression. Cartilage anabolism was investigated by Sox9, aggrecan, type II collagen, and glycosaminoglycan expression. In chondrocytes, TGF-β1 increased expression of hypertrophic genes and activated canonical WNT pathway, while it decreased dramatically cartilage anabolism, suggesting that this treatment could mimic some OA features in vitro. Additionally, EZH2 inhibition, that has been previously reported to decrease cartilage hypertrophy and reduce OA development in vivo, attenuated COL10A1 and MMP13 upregulation and SOX9 downregulation induced by TGF-β1 treatment. Similarly, pterosin B (an inhibitor of Sik3), and DMOG (a hypoxia-inducible factor prolyl hydroxylase which mimicks hypoxia), repressed the expression of hypertrophy markers in TGF-β stimulated chondrocytes. In conclusion, we established an innovative OA model in vitro. This cheap and simple model will be useful to quickly screen new drugs with potential anti-arthritic effects, in complementary to current inflammatory models, and should permit to accelerate development of efficient treatments against OA able to reduce cartilage hypertrophy.

Evaluation of transforming growth factor beta 1 in dogs with osteoarthritis

Osteoarthritis is a common problem in daily veterinary practice with insufficient knowledge about disease mechanism. Because fibrosis is a part of the alteration in the effected joints, we investigated the transforming growth factor beta 1 (TGF-β1) as an important regulation molecule of tissue fibrosis. We chose Osteoarthritis following a cruciate ligament rupture (CLR) because it is a common model of osteoarthritis. A total of 13 healthy dogs and 38 dogs suffering from CLR were included in this prospective study. The concentration of TGF-β1 was measured in synovial fluid using the “Quantikine Human TGF-β1 Immunoassay” (Fa. R & D Systems, Minneapolis, USA). There was a significant difference in the TGF-β1 concentration of the synovial fluid of healthy compared to affected patients (p < 0.001). The synovial TGF-β1 concentration also correlated significantly (p = 0.0147) with the synovial viscosity of the affected patients. No significant correlations could be observed to duration of disease, severity of lameness and degree of joint swelling, but also to joint capsule sickness, osteophyte development and degeneration of joint cartilage. The results of our study show an increased TGF-β1 concentration in knees affected with osteoarthritis as consequence of CLR. So we can conclude that TGF-β1 takes part at the osteoarthritic remodelling process, but different phases of the remodelling process cannot be distinguished by the measurement of TGF-β1.

Selection and Investigation of a Primate Model of Spontaneous Degenerative Knee Osteoarthritis, the Cynomolgus Monkey (Macaca Fascicularis)

BACKGROUND The aim of this study was to identify a primate model of degenerative knee osteoarthritis (KOA) that may be more relevant for research studies on degenerative KOA in humans. MATERIAL AND METHODS Sixteen specific-pathogen-free (SPF) male cynomolgus monkeys (Macaca fascicularis) were divided into group A (n=8), an old group (22.0-25.3 years of age), and group B (n=8), a young group (3.0-5.2 years of age). For each primate, the behavior was observed, knee circumference was measured, knee joint X-rays were performed, and peripheral blood white blood cell (WBC) counts were measured, and the Kellgren and Lawrence (K-L) system was used for the classification of osteoarthritis. An enzyme-linked immunoassay (ELISA) was performed on knee joint fluid to measure levels of interleukin (IL)-1β, transforming growth factor (TGF)-β1, and matrix metalloproteinase (MMP)13. Changes in articular cartilage were evaluated using the Brittberg score and the Mankin histopathology grading score, respectively. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot were used to measure the expression of the NOTCH3, JAG1, and ACAN genes in knee cartilage specimens, and the findings in the two groups of primates were compared. RESULTS Seven old aged primates in group A were compared with group B, and showed significant differences in WBC count, synovial fluid IL-1β, TGF-β1, and MMP13 levels, expression levels of the NOTCH3, JAG1, and ACAN genes in knee cartilage specimens, and in the Brittberg and Mankin scores (all, P<0.05). CONCLUSIONS Cynomolgus monkeys (Macaca fascicularis) might be a model for age-related degenerative KOA.

Differential Role of Transforming Growth Factor-beta in an Osteoarthritic or a Healthy Joint

Transforming growth factor-β (TGF-β) is a cytokine that plays an important role in both normal joints and joints affected by osteoarthritis (OA), the most common joint disease. However, the role of this pleiotropic cytokine in a normal healthy joint is very different from its role in an OA joint. In a normal synovial joint, active TGF-β is only present after joint loading and only for a short period. In contrast, permanent and high levels of active TGF-β are detected in OA joints. Due to this difference in levels and exposure period of joint cells to active TGF-β, the function of TGF-β is strikingly different in normal and OA joints. The consequences of this difference in TGF-β levels on joint homeostasis and pathological changes in OA joints are discussed in this review.

Does TGF-β play a role in degenerative temporomandibular joint diseases? A systematic review

OBJECTIVES

The objective of this review was to assess the literature for evidence investigating the role of TGF-β in temporomandibular joint disease with osteoarthritis.

METHOD

An electronic and manual search was carried out on the databases, MEDLINE/PubMed, Cochrane Library, Web Of Science, and EMBASE, from 1975 to December 2015 by two independent evaluators to identify clinical and laboratory trials in English.

RESULTS

The search produced 693 records. Following a process of selection based on certain criteria, eight articles were included.

DISCUSSION

This systematic review suggests that TGF-β administration alone does not result in joint regeneration; other factors may be involved, such as TGF-β receptor expression ,and TGF-β receptor mutations that do not allow a correct transduction, resulting in TGF-β deficiency. The anabolism induced by this growth factor is also able to neutralize the catabolic processes that are elevated in osteoarthritis. Therefore, further studies are essential to determine how the concentration of TGF-β in the temporomandibular joints acts as a potential marker for the development of degenerative conditions.

Assessment of temporomandibular joint disease

The diagnosis of temporomandibular joint (TMJ) disorders consists of clinical (Reaserch Diagnostic Criteria for Temporomandibular Disorders, RDC/TMD) and additional (computer tomography, CT or magnetic resonance imaging, and MRI) examinations. Due to the growing knowledge of pathologic changes within the TMJ, the researches become more aware of the difficulty in detection the early symptoms of disorders using conventional examination. Therefore, it is now expected that the collected samples of synovial fluid, serum, or urine samples could enable easier identification of inflammatory process course, and degenerative cartilage changes state.

Analysis of the cytokine profiles of the synovial fluid in a normal temporomandibular joint: preliminary study

The purpose of this study was to compare the cytokine profiles of the synovial fluid from the temporomandibular joint (TMJ) spaces of normal individuals and temporomandibular disorder (TMD) patients. Thirty-four patients with planned orthognathic surgery did not present abnormalities of the TMJ on magnetic resonance images and radiographs and did not show the symptoms identified by the Research Diagnostic Criteria for TMD (RDC-TMD); as a result, they were assigned to the control group. Twenty-two patients who sought treatment for TMD during the same period were assigned to the TMD group. Synovial fluid was collected from superior TMJ spaces, and cytokine expression was analysed by an enzyme-linked immunosorbent assay (ELISA). Significant differences were tested using Fisher's exact test (p<0.05). Granulocyte Macrophage Colony stimulating Factor (GM-CSF), interferon (INF), interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10 and tumour necrosis factor (TNF)-α were detected in the TMD group, whereas no cytokines were detected in the control group. The most prevalent cytokines in the TMD group were IL-1β, IL-6 and GM-CSF. IL-4 and IL-5 were not detected in either the TMD group or in the control group. None of the cytokines that were detected in patients with TMD were found in the articular spaces of normal individuals.

Excess risk of temporomandibular disorder associated with cigarette smoking in young adults

Evidence suggests that the effect of cigarette smoking on chronic pain is stronger in younger than older adults. This case-control study investigated whether age modified an effect of smoking on temporomandibular disorder (TMD) in 299 females aged 18 to 60 years. It also investigated the extent to which this relationship was explained by psychological profile, inflammatory response, and allergy. Cases were defined using the Research Diagnostic Criteria for Temporomandibular Disorders based on clinical examination. Psychological profile was evaluated using standardized instruments. Inflammatory response was evaluated with 11 cytokines isolated in plasma. History of allergy conditions was self-reported. Odds ratios (ORs) for the effect of smoking were calculated using binary logistic regression. Stratified analyses and the likelihood ratio test examined effect modification by smoking. Compared with nonsmokers, ever smokers aged <30 years had higher odds of TMD (OR = 4.14, 95% CI: 1.57, 11.35) than older adults (OR = 1.23, 95% CI: .55, 2.78) (P (effect modification) = .038). Adjustment for psychological profile, cytokines, and history of allergy-like conditions attenuated the effect by 45% to statistical nonsignificance. The main finding was reproduced with secondary analyses of 2 nationally representative surveys of adults conducted in the US and Australia.

PERSPECTIVE

This study showed that smoking was associated with TMD risk in females, but only in young adulthood. It replicated this finding in 2 nationally representative surveys of females in the US and Australia. Findings may alert clinicians to recognize that smoking is a concern for TMD in younger female patients.

Effect of intra-articular administration of interleukin 1 receptor antagonist on cartilage repair in temporomandibular joint

Interleukin 1 (IL-1) plays a central role in cartilage deterioration in osteoarthritis (OA). Interleukin 1 receptor antagonist (IL-1Ra) is a natural receptor antagonist and blocks the effects of IL-1. In this study, partial disk perforation was performed bilaterally to induce an osteoarthritic joint in rabbit temporomandibular joint. Fifty micrograms of recombinant human IL-1Ra was injected into the right joint, and the contralateral joint received vehicle injection 4 weeks postoperatively. Animals were killed at different intervals. Histology and reverse transcription-polymerase chain reaction were performed for comparison. The vehicle-treated joint had typical OA-related cartilage degradation, whereas the lesions in cartilage of the IL-1Ra-treated joint were less severe than the control joint. At 12 weeks, a higher expression of aggrecan and collagen type II and a lower expression of aggrecanase were observed in the treated joint than in the control joint. At 24 weeks after injection, the expression of aggrecan and collagen type II was also higher in the treated joint than in the control joint. However, no difference in either aggrecanase or tumor necrosis factor α was found between 2 groups at 24 weeks. Our results suggest that intra-articular administration of IL-1Ra into the temporomandibular joint may be a good alternative for the treatment of cartilage degeneration in OA. There was also evidence confirming that supplemented IL-1Ra functions by modifying the signal transduction mechanisms specific to IL-1.

Increased levels of soluble cytokine receptors in the synovial fluid of temporomandibular joint disorders in relation to joint effusion on magnetic resonance images

PURPOSE

The purpose of this study is to clarify the significance of joint effusion (JE) on T2-weighted magnetic resonance images of the temporomandibular joint (TMJ) in comparison to various soluble cytokine receptors in the synovial fluid of patients with temporomandibular disorders (TMDs).

PATIENTS AND METHODS

Magnetic resonance imaging of 55 TMJs of 55 patients with TMD was performed, and synovial fluid samples were obtained on the same day. The grade of JE was evaluated on a scale from 0 to 3, with grade 0 indicating the absence of JE and grades 1 to 3 indicating the presence of JE. Correlations were measured between JE and the concentrations of soluble tumor necrosis factor receptors I and II, interleukin (IL) 6 soluble receptor, IL-1 soluble receptor type II, and IL-1 receptor antagonist and protein in the synovial fluid samples.

RESULTS

The mean concentrations of cytokine receptors in the synovial fluid were significantly higher in the 30 joints with JE than in the 25 joints without JE. There were no correlations between the JE grade and the level of any mediators.

CONCLUSION

Increased levels of cytokine receptors are likely to influence the expression of JE and may play important roles in the pathogenesis of TMD. These results also suggest that JE may reflect synovial inflammation of the TMJ.

Temporomandibular joint pain and synovial fluid analysis: a review of the literature

The pathophysiology of temporomandibular joint pain is not well understood. A significant amount of research has been conducted to evaluate synovial fluid in these patients and in healthy controls. Qualitative and quantitative analyses of the synovial fluid have shown a significant difference between these groups. A multitude of inflammatory mediators and degradation products have been identified. The concentration of these products has been shown to correlate with several clinical parameters including pain, chronicity, severity of degenerative change, and response to treatment. A common inflammatory pathway would appear to be involved in most patients. At the present time, synovial fluid analysis does not have the sensitivity or specificity to allow specific diagnoses and targeted treatment. Continued research with the specific aim of establishing more appropriate therapeutic modalities based on the biochemical pathways is warranted.

Cytokines in temporomandibular joint arthritis

As the article in the current issue by Shinoda and colleagues shows, during the last two decades, there has been a dramatic increase in the understanding of basic biology behind chronic temporomandibular joint (TMJ) pain, inflammation and destruction. The involvement and contribution of cytokines to TMJ pain and inflammation must now be considered as established, evident and fundamental. Based on the present knowledge, it is now possible to design and investigate novel therapeutic strategies. These new and very encouraging approaches include manipulation of cytokine function, immune reactivity and the behaviour of inflammatory cells while maintaining the integrity of the affected tissue.

Cytokine profile in synovial fluid from patients with internal derangement of the temporomandibular joint: a preliminary study

OBJECTIVES

Temporomandibular joint disorders (TMD) comprise a group of chronic painful conditions of mastication in the temporomandibular joint (TMJ). Although the association between TMD and internal derangement of the TMJ is well documented, the functional relevance is still unclear. Increased concentrations of inflammatory mediators have been identified in the synovial fluid of affected patients with TMD, suggesting an underlying degenerative or inflammatory process. The aim of this study was to generate a comprehensive cytokine expression profile in TMD.

METHODS

15 samples from patients with internal derangement of TMJ were analysed using a novel cytokine array that enables the analysis of 79 different cytokines simultaneously.

RESULTS

Cytokine levels were correlated with the presence of joint effusion (JE) determined by MRI. In the majority of synovial fluid samples, angiogenin (Ang), fibroblast growth factor (FGF)-9, insulin-like growth factor-binding protein (IGFBP)-3, interleukin (IL)-1alpha, IL-1beta, IL-8, inducible protein (IP)-10, macrophage inflammatory protein (MIP)-1beta, osteoprotegerin (OPG), transforming growth factor (TGF)-beta2, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, tumour necrosis factor (TNF)-beta and vascular endothelial growth factor (VEGF) were detectable. Furthermore, the expression levels of Ang, brain-derived neurotrophic factor (BDNF), FGF-4, FGF-9, IGFBP-2, IL-8, MIP-1beta, OPG, pulmonary and activation-regulated protein (PARC), TGF-beta2, TIMP-2 and VEGF were significantly associated with the presence of JE; among these, nine cytokines (Ang, BDNF, FGF-4, FGF-9, IGFBP-2, MIP-1beta, PARC, TGF-beta2 and TIMP-2) were hitherto not described in TMD.

CONCLUSIONS

This study confirmed previous reports of elevated cytokine levels in TMD. Additionally, we identified previously undescribed cytokines that were upregulated and correlated significantly with the presence of JE. We were able to identify novel cytokines that have hitherto not been described in TMD. Strategies targeting the identified cytokines may represent a novel therapy option in TMD.

The effect of IL-1β on the expression of inflammatory cytokines and their receptors in human chondrocytes

Cytokines released at sites of inflammation and infection can alter the normal processes of cartilage turnover, resulting in pathologic destruction or formation. Interleukin (IL)-1beta plays a central role in the pathophysiology of cartilage damage and degradation in arthritis. In the present study, we examined the effect of IL-1beta on the expression of IL-1beta, IL-6, IL-8, IL-11, tumor necrosis factor-alpha (TNF-alpha), and their receptors in human chondrocytes. The cells were cultured either with or without 100 U/ml of IL-1beta for up to 28 days. The level of expression of the cytokines and their receptors was estimated by determining mRNA levels using real-time PCR or by determining protein levels using ELISA. The expression of IL-1beta, IL-8, and TNF-alpha markedly increased in the presence of IL-1beta after day 14 of culture. The expression of IL-6 and IL-11 increased greatly in the presence of IL-1beta on day 1 and after day 14 of culture. The expression of IL-1beta, IL-8, IL-11, and TNF-alpha receptors significantly decreased in the presence of IL-1beta after day 14 of culture, whereas the expression of IL-6 receptor significantly increased. The expression of these cytokines, except for IL-6, decreased with the addition of human IL-1 receptor antagonist. These results suggest that IL-1beta promotes the resolution system of cartilage matrix turnover through an increase in inflammatory cytokine production by chondrocytes and that it also may promote the autocrine action of IL-6 through an increase in IL-6 receptor expression in the cells.

Levels of soluble cytokine factors in temporomandibular joint effusions seen on magnetic resonance images

OBJECTIVE

To elucidate the correlations between joint effusion (JE) on T2-weighted magnetic resonance images (MRI) of the temporomandibular joint (TMJ) and the levels of various cytokine receptors, cytokine antagonists, and protein in the synovial fluid of patients with temporomandibular joint disorders (TMD).

STUDY DESIGN

Fifty-five TMJs of 55 patients with TMD were scanned by MRI, and synovial fluid samples were obtained on the same day. The grade of JE was evaluated on a scale of 0 to 3: Grades 0 and 1 indicated absence, and grades 2 and 3 indicated the presence of JE. Correlations were evaluated between JE and the concentrations of soluble tumor necrosis factor receptors I and II (sTNFR-I and sTNFR-II, respectively), IL-6 soluble receptor (IL-6sR), IL-1 soluble receptor type II, and IL-1 receptor antagonist and protein in the synovial fluid of patients with TMD.

RESULTS

The concentrations of sTNFR-I and protein in the group with JE (18 joints) were significantly higher than in the group without JE (37 joints). In addition, there were significant positive correlations between the grade of JE and the levels of sTNFR-I, sTNFR-II, and protein.

CONCLUSIONS

sTNFRs and protein may play important roles in the pathogenesis of TMD. These mediators seem to influence the expression of JE, which may reflect synovial inflammation of the TMJ.

Analysis of tumor necrosis factor-α, interleukin-6, interleukin-1β, soluble tumor necrosis factor receptors I and II, interleukin-6 soluble receptor, interleukin-1 soluble receptor type II, interleukin-1 receptor antagonist, and protein in the synovial fluid of patients with temporomandibular joint disorders

OBJECTIVE

To measure the levels of various cytokines, cytokine receptors, and cytokine antagonists in the synovial fluid of patients with temporomandibular disorders (TMD) and to determine the correlations among these expression levels.

STUDY DESIGN

Synovial fluid was obtained from 55 patients with TMD and from 5 asymptomatic healthy volunteers as controls. The concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-1beta, soluble tumor necrosis factor receptors I and II (sTNFR-I and sTNFR-II), IL-6 soluble receptor (IL-6sR), IL-1 soluble receptor type II, and IL-1 receptor antagonist were determined by enzyme-linked immunosorbent assay.

RESULTS

The concentrations of TNF-alpha, IL-6, IL-1beta, sTNFR-I, and sTNFR-II were significantly higher in the synovial fluid of patients than in controls (P < .05). TNF-alpha level was positively correlated with those of IL-6, sTNFR-I, and sTNFR-II. In particular, there was a highly significant positive correlation between sTNFR-I and sTNFR-II.

CONCLUSION

TNF and sTNFRs in the synovial fluid of patients with TMD may be important in the pathogenesis of these disorders.

Effects of TGF-beta on hyaluronan anabolism in fibroblasts derived from the synovial membrane of the rabbit temporomandibular joint

Hyaluronan (HA) synthesis in the synovial membrane is affected by various chemical mediators. It is hypothesized that transforming growth factor-beta 1 (TGF-beta 1) would be a mediator to modulate HA synthesis in cultured synovial membrane fibroblasts of the temporomandibular joint (TMJ). Fibroblasts were extracted from the TMJ synovial membrane of four-week-old Japanese white rabbits. The amount of HA and expression levels of HA synthase (HAS) mRNAs induced by TGF-beta 1 treatment were analyzed by means of high-performance liquid chromatography and real-time polymerase chain-reaction, respectively. Both medium and large amounts of HA were enhanced by the stimulation of TGF-beta 1. HAS2 mRNA expression was enhanced 13-fold after six-hour stimulation with TGF-beta 1 (10 ng/mL), whereas HAS3 mRNA expression was not changed significantly. These results suggest that TGF-beta 1 enhances the expression of HAS2 mRNA in the TMJ synovial membrane fibroblasts and may contribute to the production of high-molecular-weight HA in the joint fluid.

Facial arthralgia and myalgia: can they be differentiated by trigeminal sensory assessment?

Heat and electrical detection thresholds were assessed in 72 patients suffering from painful temporomandibular disorder. Employing widely accepted criteria, 44 patients were classified as suffering from temporomandibular joint (TMJ) arthralgia (i.e. pain originating from the TMJ) and 28 from myalgia (i.e. pain originating from the muscles of mastication). Electrical stimulation was employed to assess thresholds in large myelinated nerve fibers (Abeta) and heat application to assess thresholds in unmyelinated nerve fibers (C). The sensory tests were performed bilaterally in three trigeminal nerve sites: the auriculotemporal nerve territory (AUT), buccal nerve territory (BUC) and the mental nerve territory (MNT). In addition, 22 healthy asymptomatic controls were examined. A subset of ten arthralgia patients underwent arthrocentesis and electrical detection thresholds were additionally assessed following the procedure. Electrical detection threshold ratios were calculated by dividing the affected side by the control side, thus reduced ratios indicate hypersensitivity of the affected side. In control patients, ratios obtained at all sites did not vary significantly from the expected value of 'one' (mean with 95% confidence intervals; AUT, 1:0.95-1.06; BUC, 1.01:0.93-1.11; MNT, 0.97:0.88-1.05, all areas one sample analysis P>0.05). In arthralgia patients mean ratios (+/-SEM) obtained for the AUT territory (0.63+/-0.03) were significantly lower compared to ratios for the MNT (1.02+/-0.03) and BUC (0.96+/-0.04) territories (repeated measures analysis of variance (RANOVA), P<0.0001) and compared to the AUT ratios in myalgia (1.27+/-0.09) and control subjects (1+/-0.06, ANOVA, P<0.0001). In the myalgia group the electrical detection threshold ratios in the AUT territory were significantly elevated compared to the AUT ratios in control subjects (Dunnett test, P<0.05), but only approached statistical significance compared to the MNT (1.07+/-0.04) and BUC (1.11+/-0.06) territories (RANOVA, F(2,27)=3.12, P=0.052). There were no significant differences between and within the groups for electrical detection threshold ratios in the BUC and MNT nerve territories, and for the heat detection thresholds in all tested sites. Following arthrocentesis, mean electrical detection threshold ratios in the AUT territory were significantly elevated from 0.64+/-0.06 to 0.99+/-0.04 indicating resolution of the hypersensitivity (paired t-test, P=0.001). In conclusion, large myelinated fiber hypersensitivity is found in the skin overlying TMJs with clinical pain and pathology but is not found in controls. In patients with muscle-related facial pain there was significant elevation of the electrical detection threshold in the AUT region.

Up-regulated expression of cartilage intermediate-layer protein and ANK in articular hyaline cartilage from patients with calcium pyrophosphate dihydrate crystal deposition disease

OBJECTIVE

Excess accumulation of extracellular inorganic pyrophosphate (ePPi) in aged human cartilage is crucial in calcium pyrophosphate dihydrate (CPPD) crystal formation in cartilage matrix. Two sources of ePPi are ePPi-generating ectoenzymes (NTPPPH) and extracellular transport of intracellular PPi by ANK. This study was undertaken to evaluate the role of NTPPPH and ANK in ePPi elaboration, by investigating expression of NTPPPH enzymes (cartilage intermediate-layer protein [CILP] and plasma cell membrane glycoprotein 1 [PC-1]) and ANK in human chondrocytes from osteoarthritic (OA) articular cartilage containing CPPD crystals and without crystals.

METHODS

Chondrocytes were harvested from knee cartilage at the time of arthroplasty (OA with CPPD crystals [CPPD], n = 8; OA without crystals [OA], n = 10). Normal adult human chondrocytes (n = 1) were used as a control. Chondrocytes were cultured with transforming growth factor beta1 (TGFbeta1), which stimulates ePPi elaboration, and/or insulin-like growth factor 1 (IGF-1), which inhibits ePPi elaboration. NTPPPH and ePPi were measured in the media at 48 hours. Media CILP, PC-1, and ANK were determined by dot-immunoblot analysis. Chondrocyte messenger RNA (mRNA) was extracted for reverse transcriptase-polymerase chain reaction to study expression of mRNA for CILP, PC-1, and ANK. NTPPPH and ANK mRNA and protein were also studied in fresh frozen cartilage.

RESULTS

Basal ePPi elaboration and NTPPPH activity in conditioned media from CPPD chondrocytes were elevated compared with normal chondrocytes, and tended to be higher compared with OA chondrocytes. Basal expression of mRNA for CILP (chondrocytes) and ANK (cartilage) was higher in both CPPD chondrocytes and CPPD cartilage extract than in OA or normal samples. PC-1 mRNA was less abundant in CPPD chondrocytes and cartilage extract than in OA chondrocytes and extract, although the difference was not significant. CILP, PC-1, and ANK protein levels were similar in CPPD, OA, and normal chondrocytes or cartilage extracts. Both CILP and ANK mRNA expression and ePPi elaboration were stimulated by TGFbeta1 and inhibited by IGF-1 in chondrocytes from all sources.

CONCLUSION

CILP and ANK mRNA expression correlates with chondrocyte ePPi accumulation around CPPD and OA chondrocytes, and all respond similarly to growth factor stimulation. These findings suggest that up-regulated CILP and ANK expression contributes to higher ePPi accumulation from CPPD crystal-forming cartilage.

Biochemical and immunohistochemical studies of the protein expression and localization of decorin and biglycan in the temporomandibular joint disc of growing rats

To analyze the growth-related changes in extracellular matrix components, biochemical/immunohistochemical techniques were used to examine the protein expression and localization of two small leucine-rich proteoglycans, biglycan and decorin, in the temporomandibular joint discs of growing rats. Western blotting showed that the protein expression of decorin increased with age, but that of biglycan gradually decreased. An immunohistochemical study showed that staining for decorin was weak and homogeneously distributed in the discs from birth to 2 weeks. Regional differences in staining for decorin became prominent at 4, 8 and 16 weeks; decorin was more abundant in the peripheral area (the periphery of the band and the attachment) than in the central area (the intermediate zone and central area of the posterior band). In contrast, staining for biglycan was evenly distributed throughout the disc until 4 weeks, and after that became rather intense in the anterior and posterior bands. These results demonstrate that there are growth-related changes and regional differences in the expression of biglycan and decorin in the temporomandibular joint discs of growing rats, which probably reflect changes in the biomechanical environment caused by the development of orofacial functions.

Proinflammatory cytokines and arthroscopic findings of patients with internal derangement and osteoarthritis of the temporomandibular joint

This study investigated the correlations between the concentrations of proinflammatory cytokines in synovial fluid and the degree of synovitis on the one hand, and the degree of degeneration of articular cartilage on the other hand, in patients with internal derangement and osteoarthritis of the temporomandibular joint. We measured the concentrations of interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha), IL-6 and IL-8 in synovial fluid and the degree of arthroscopic synovitis and degeneration of articular cartilage in 37 joints with internal derangement and osteoarthritis. The correlations between the concentration of each cytokine and the score of each arthroscopic feature were analysed statistically. The detection rates of IL-1beta,TNF-alpha, IL-6 and IL-8 were 57%, 78%, 89% and 70%, respectively. There was a positive correlation between the IL-6 concentration and the synovitis score (P = 0.02). Measurement of IL-6 in synovial fluid might be useful as an indicator of the extent of synovitis.