Tumor necrosis factor-alpha in synovial fluid and plasma from patients with chronic connective tissue disease and its relation to temporomandibular joint pain

The Temporomandibular Joint and the Human Body: A New Perspective on Cross Talk

Background: As a unique joint that facilitates the articulation of the upper and lower jaws, the temporomandibular joint (TMJ) is concerned with several critical functions, such as speech and mastication. Pain that can become incapacitating is a result of temporomandibular disorders (TMDs), which are complex disorders affecting the masticatory muscles and the TMJ. Several anomalies and TMDs have an interdisciplinary relationship. Complementary and concurrent disorders may be caused by occlusal anomalies, psychological disorders, and changes in spine posture. Methods: This article examines the clinical characteristics of TMDs, their classification, their etiological factors, and the impact of TMJ disorders on the human body with reference to their anatomies and histological structures. Results: The clinical picture of some TMJ pathologies may be unknown, so certain biomarkers, such as cytokines, may be useful for an accurate diagnosis as they are frequently seen in TMJ disorders. Furthermore, novel therapeutic approaches that target pro-inflammatory cytokines and treat TMDs by using tissue engineering and regenerative medicine while permitting TMJ cartilage and bone regeneration may offer numerous benefits that require clinical translation. Conclusions: Implementation of recent modalities such as microvesicles and platelet-rich plasma in growth factors may provide a promising approach to enhance bone formation. In addition, we target different biological markers that give insights into the introduction of new pharmaceutical agents for therapy.

Lycopene as a Potential Anti-inflammatory Therapeutic Agent for Temporomandibular Joint Disorders: A Narrative Review

Temporomandibular joint disorder is a common condition characterized by jaw joint and muscle pain and its treatment is often multifaceted. While conventional treatment modalities exist for the same, interest has grown in exploring alternative therapies such as antioxidants for their potential analgesic properties. The prospective therapeutic use of lycopene, a naturally occurring antioxidant present in tomatoes and other fruits, as an anti-inflammatory therapeutic modality in the management of temporomandibular joint problems is examined in this narrative review.

The degeneration-pain relationship in the temporomandibular joint: Current understandings and rodent models

Temporomandibular disorders (TMD) represent a group of musculoskeletal conditions involving the temporomandibular joints (TMJ), the masticatory muscles and associated structures. Painful TMD are highly prevalent and conditions afflict 4% of US adults annually. TMD include heterogenous musculoskeletal pain conditions, such as myalgia, arthralgia, and myofascial pain. A subpopulations of TMD patients show structural changes in TMJ, including disc displacement or degenerative joint diseases (DJD). DJD is a slowly progressing, degenerative disease of the TMJ characterized by cartilage degradation and subchondral bone remodeling. Patients with DJD often develop pain (TMJ osteoarthritis; TMJ OA), but do not always have pain (TMJ osteoarthrosis). Therefore, pain symptoms are not always associated with altered TMJ structures, which suggests that a causal relationship between TMJ degeneration and pain is unclear. Multiple animal models have been developed for determining altered joint structure and pain phenotypes in response to various TMJ injuries. Rodent models of TMJOA and pain include injections to induce inflammation or cartilage destruction, sustained opening of the oral cavity, surgical resection of the articular disc, transgenic approaches to knockout or overexpress key genes, and an integrative approach with superimposed emotional stress or comorbidities. In rodents, TMJ pain and degeneration occur during partially overlapping time periods in these models, which suggests that common biological factors may mediate TMJ pain and degeneration over different time courses. While substances such as intra-articular pro-inflammatory cytokines commonly cause pain and joint degeneration, it remains unclear whether pain or nociceptive activities are causally associated with structural degeneration of TMJ and whether structural degeneration of TMJ is necessary for producing persistent pain. A thorough understanding of the determining factors of pain-structure relationships of TMJ during the onset, progression, and chronification by adopting novel approaches and models should improve the ability to simultaneously treat TMJ pain and TMJ degeneration.

ASSOCIATION OF SOME IMMUNOLOGICAL BIOMARKERS WITH RHEUMATOID ARTHRITIS PATIENTS IN THI-QAR PROVINCE

OBJECTIVE

The aim: The aim of this research is to evaluate some immunological biomarkers in cases of Rheumatoid arthritis and to verify their correlation with activity of disease among the population of Thi-Qar province.

PATIENTS AND METHODS

Matherials and methods: This study included 45 cases of rheumatoid arthritis and 45 healthy subjects. All cases underwent complete history taking, thor¬ough clinical examination, and laboratory tests including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Anti-citrulline antibody (Anti-CCP) and rheumatoid factor (RF). IL-17and TNF-α blood level was measured by Enzyme Linked Immunosorbent Assay (ELISA) method. DAS-28 (Disease activity score 28) was evaluated.

RESULTS

Results: Serum levels TNF-α was higher in Rheumatoid arthritis patients (424.3±19.46 pg/ml) than in healthy individuals (112.7±4.73 pg/ml), and IL-17 blood levels were higher in Rheumatoid arthritis patients (233.5±241.4 pg/ml) than the healthy individuals group (47.24±49.7 pg/ml). There was significant association found among IL-17, DAS-28, CRP and hemoglobin levels.

CONCLUSION

Conclusions: In conclusion, IL-17 blood levels were significantly increased in peoples with rheumatoid arthritis than in healthy individuals. Its significant relationship with DAS-28 suggested that the level of IL-17 in serum could be important immunological biomarker for activity of disease in disease of Rheumatoid arthritis.

Cytokines in temporomandibular joint synovial fluid and tissue in relation to inflammation

BACKGROUND

Synovial tissue is known to be the origin of inflammation in joint disease. Despite this, synovial fluid is the main biological specimen of choice in temporomandibular joint (TMJ) inflammation and pathology biomarker research. No comparison of TMJ protein content between synovial fluid and synovial tissue has been made.

OBJECTIVES

To investigate if cytokine concentrations in synovial fluid can be related to cytokine concentrations in synovial tissue, and to analyse correlation of clinical parameters reflecting local inflammation to cytokine concentrations.

METHODS

Synovial tissue and fluid samples were obtained during the same surgical procedure from a cohort of 101 patients with TMJ disorders. Interleukin (IL) 1β, IL-6, IL-8, IL-10, and tumor necrosis factor α (TNF-α) were analysed in the samples and an intraindividual correlation made. Various patient-specific factors relating to TMJ inflammation were associated to the cytokine concentrations in synovial fluid and tissue.

RESULTS

No correlation between cytokine concentration in synovial fluid and synovial tissue was found, except for IL-8 (ρ=.284, P=.024). Synovial tissue cytokines correlated strongly to inflammation-related factors: diagnosis (IL-1β, P=.001; TNF-α, P=.000; IL-10, P=.000), TMJ palpation pain (IL-1β, P=.024; TNF-α, P=.025), synovitis score (IL-1β, P=.015), and subjective TMJ pain (TNF-α, P=.016). Synovial fluid cytokines showed no significant relations to inflammation.

CONCLUSIONS

The investigated cytokine concentrations showed weak correlations between synovial fluid and synovial tissue, besides IL-8. Synovial tissue appeared to reflect inflammation to a higher extent than synovial fluid. Thus, suggesting that synovial tissue research should complement synovial fluid in future explorations of TMJ pathology and inflammation.

The Role of TNF-α in the Pathogenesis of Temporomandibular Disorders

Temporomandibular disorder (TMD) is an oral dentofacial disease that is related to multiple factors such as disordered dental occlusion, emotional stress, and immune responses. In the past decades, tumor necrosis factor-alpha (TNF-α), a pleiotropic cytokine, has provided valuable insight into the pathogenesis of TMD, particularly in settings associated with inflammation. It is thought that TNF-α participates in the pathogenesis of TMD by triggering immune responses, deteriorating bone and cartilage, and mediating pain in the temporomandibular joint (TMJ). Initially, TNF-α plays the role of "master regulator" in the complex immune network by increasing or decreasing the production of other inflammatory cytokines. Then, the effects of TNF-α on cells, particularly on chondrocytes and synovial fibroblasts, result in pathologic cartilage degradation in TMD. Additionally, multiple downstream cytokines induced by TNF-α and neuropeptides can regulate central sensitization and inflammatory pain in TMD. Previous studies have also found some therapies target TMD by reducing the production of TNF-α or blocking TNF-α-induced pathways. All this evidence highlights the numerous associations between TNF-α and TMD; however, they are currently not fully understood and further investigations are still required for specific mechanisms and treatments targeting specific pathways. Therefore, in this review, we explored general mechanisms of TNF-α, with a focus on molecules in TNF-α-mediated pathways and their potential roles in TMD treatment. In view of the high clinical prevalence rate of TMD and damage to patients' QOL, this review provides adequate evidence for studying links between inflammation and TMD in further research and investigation.

A comprehensive review on biomarkers associated with painful temporomandibular disorders

Pain of the orofacial region is the primary complaint for which patients seek treatment. Of all the orofacial pain conditions, one condition that possess a significant global health problem is temporomandibular disorder (TMD). Patients with TMD typically frequently complaints of pain as a symptom. TMD can occur due to complex interplay between peripheral and central sensitization, endogenous modulatory pathways, and cortical processing. For diagnosis of TMD pain a descriptive history, clinical assessment, and imaging is needed. However, due to the complex nature of pain an additional step is needed to render a definitive TMD diagnosis. In this review we explicate the role of different biomarkers involved in painful TMD. In painful TMD conditions, the role of biomarkers is still elusive. We believe that the identification of biomarkers associated with painful TMD may stimulate researchers and clinician to understand the mechanism underlying the pathogenesis of TMD and help them in developing newer methods for the diagnosis and management of TMD. Therefore, to understand the potential relationship of biomarkers, and painful TMD we categorize the biomarkers as molecular biomarkers, neuroimaging biomarkers and sensory biomarkers. In addition, we will briefly discuss pain genetics and the role of potential microRNA (miRNA) involved in TMD pain.

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.

Biomarkers in Temporomandibular Disorder and Trigeminal Neuralgia: A Conceptual Framework for Understanding Chronic Pain

In this review, we will explore the use of biomarkers in chronic pain, using the examples of two prototypical facial pain conditions: trigeminal neuralgia and temporomandibular disorder. We will discuss the main categories of biomarkers and identify various genetic/genomic, molecular, neuroradiological, and psychophysical biomarkers in both facial pain conditions, using them to compare and contrast features of neuropathic, nonneuropathic, and mixed pain. By using two distinct model facial pain conditions to explore pain biomarkers, we aim to familiarize readers with different types of biomarkers currently being studied in chronic pain and explore how these biomarkers may be used to develop new precision medicine approaches to pain diagnosis, prognosis, and management.

Effect of a functional variant of tumor necrosis factor-β gene in temporomandibular disorders: A pilot study

BACKGROUND

Temporomandibular disorders (TMD) are a group of conditions that cause chronic orofacial pain. The tumor necrosis factor β (TNF-β) is a proinflammatory cytokine that is involved in the various aspects of the inflammatory process including organization and maintenance, and in the arrangement of cells at the inflammation site. The purpose of this study was to evaluate the correlation between TNF-β +252A/G (rs909253) variant and susceptibility to TMD in a Turkish cohort.

METHODS

The study included 104 patients (26 males, 78 females) with TMD and 126 healthy controls (44 males, 82 females). The TNF-β +252A/G variant analysis was based on Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP).

RESULTS

There was no deviation from HWA for TNF-β +252A/G variant in patient and control groups. There was significant difference in genotype and allele frequencies between patient group and control group in terms of TNF-β +252A/G variant, respectively (P = 0.010, 0.015). A significant increase in the TNF-β +252 AG genotype and G allele frequencies were observed in TMD patients compared to healthy controls. The individuals with GG genotype and G allele had an increased risk of developing TMD. A statistically significant association was observed when the patients were compared with the controls according to AA genotype vs AG+GG genotypes (P = 0.002, OR: 2.23, 95% CI:1.31-3.82). TNF-β +252A/G genotype distribution was associated with chewing problems (P = 0.046).

CONCLUSIONS

In conclusion, our results provided evidence that TNF-β +252A/G variant may contribute to TMD development in a Turkish cohort. Further studies are needed to confirm this observation.

Pain threshold and temporomandibular function in systemic sclerosis: comparison with psoriatic arthritis

The aim of the study was to evaluate whether a reduced pain threshold is associated with increased temporomandibular dysfunction in systemic sclerosis (SSc) compared to psoriatic arthritis (PsA) and healthy controls. Ninety subjects participated in the study (30 SSc, 30 PsA, and 30 healthy controls). The Helkimo index was used to evaluate temporomandibular dysfunction. Digital palpation was performed at the temporomandibular joint (TMJ) surface and at the superficial masseter muscle (SMM) and pain intensity was recorded on a visual analog scale (VAS), while pain pressure threshold (PPT) was measured at the same sites through a pressure algometer. PPT scores were lower in SSc patients compared to PsA patients and controls. In addition, the average Helkimo index score, measuring the degree of TMJ dysfunction, was higher in SSc compared to PsA and controls. A significant inverse correlation was observed between every PPT score, and both Helkimo index and VAS palpation in SSc and PsA. Both the range of motion and all the other pain-related subdomains of the Helkimo index score (pain on movement, pain palpation TMJ and pain palpation muscle) were significantly worse in SSc compared to PsA, while no significant differences were observed in the TMJ function subdomain. In SSc patients, the skin score was directly associated with the range of motion subdomain of the Helkimo index. Our results confirm that TMJ function is impaired in SSc; further longitudinal studies are needed to assess the role of pain threshold in the assessment of limitations in TMJ function and to identify an objective marker of therapeutic response.

Comparison of serum tumor necrosis factor-α levels in rheumatoid arthritis individuals with and without chronic periodontitis: A biochemical study

Background

Tumor necrosis factor-alpha (TNF-α) is indicated to play a major function in chronic inflammatory disorders.

Objective

To assess and compare the cytokine level (TNF-α) in the serum of chronic periodontitis (CP), rheumatoid arthritis (RA), RA with CP, and healthy volunteers.

Materials and Methods

This original research was carried out on 80 participants, divided into Group-I 20 RA patients, Group-II 20 CP patients, Group III 20 RA with CP (RA + CP), and Group IV 20 healthy volunteers. Clinical periodontal and rheumatological parameters were assessed in all the four groups. Blood serum samples have been collected from all individuals and investigated for levels of TNF-α by mean of enzyme-linked immunosorbent assay.

Results

TNF-α level were remarkably elevated in the RA+CP group (30.5±2.2) followed by RA group (17.9 ± 3.6), and CP group (11.9 ± 0.96) when compared with the controls (5.5 ± 3.3). The results showed a statistical significance of P < 0.001. Correlation was not observed on comparision of clinical periodontal parameters and Rheumatological parameters with TNF-α levels.

Conclusion

The outcome of this present research revealed the presence of higher levels of TNF-α in individuals with RA with CP in our samples.

Tumor necrosis factor-Alpha stimulates cytokine expression and transient sensitization of trigeminal nociceptive neurons

OBJECTIVE

Elevated levels of tumor necrosis factor- alpha (TNF-α) in the capsule of the temporomandibular joint (TMJ) are implicated in the underlying pathology of temporomandibular disorders (TMD). TMD are a group of conditions that result in pain in the TMJ and/or muscles of mastication, and are associated with significant social and economic burdens. The goal of this study was to investigate the effect of elevated TNF-α levels in the TMJ capsule on nocifensive behavioral response to mechanical stimulation of trigeminal neurons and regulation of cytokines within the trigeminal ganglion.

DESIGN

Male Sprague-Dawley rats were injected bilaterally in the TMJ capsule with TNF-α and changes in nocifensive head withdrawal responses to mechanical stimulation of cutaneous tissue directly over the capsule was determined using von Frey filaments. Cytokine levels in trigeminal ganglia were determined by protein array analysis at several time points post injection and correlated to nocifensive behavior.

RESULTS

TNF-α caused a significant increase in the average number of nocifensive responses when compared to naive and vehicle treated animals 2h post injection, but levels returned to control levels at 24h. Based on array analysis, the levels of eight cytokines were significantly elevated above vehicle control levels at 2h following TNF-α injection, but all eight had returned to the vehicle control levels after 24h.

CONCLUSIONS

Our findings provide evidence that elevated levels of TNF-α in the joint capsule, which is reported to occur in TMD, promotes nociception in trigeminal ganglia neurons via a mechanism that temporally correlates with differential regulation of several cytokines.

Lectin from Abelmoschus esculentus reduces zymosan-induced temporomandibular joint inflammatory hypernociception in rats via heme oxygenase-1 pathway integrity and tnf-α and il-1β suppression

Temporomandibular joint (TMJ) disorders show inflammatory components, heavily impacting on quality of life. Abelmoschus esculentus is largely cultivated in Northeastern Brazil for medicinal purposes, having it shown anti-inflammatory activity. We evaluated A. esculentus lectin (AEL) efficacy in reducing zymosan-induced temporomandibular joint inflammatory hypernociception in rats along with the mechanism of action through which it exerts anti-inflammatory activity. Animals were pre-treated with AEL (0.01, 0.1 or 1mg/kg) before zymosan (Zy) injection in the TMJ to determine anti-inflammatory activity. To analyse the possible effect of the hemeoxygenase-1 (HO-1) and the nitric oxide (NO) pathways on AEL efficacy, animals were pre-treated with ZnPP-IX (3mg/kg), a specific HO-1 inhibitor, or aminoguanidine (30mg/kg), a selective iNOS inhibitor, before AEL administration. Von Frey test evaluated inflammatory hypernociception, synovial fluid collection was performed to determine leukocyte counting and myeloperoxidase (MPO) activity 6h after Zy injection, and Evans Blue extravasation determined vascular permeability. TMJ tissue was collected for histopathological analysis (H&E) and immunohistochemistry (TNF-α, IL-1β, HO-1). In addition, TMJ tissue and trigeminal ganglion collection was performed for TNF-α and IL-1β dosage (ELISA). AEL increased inflammatory nociceptive threshold, reduced leukocyte influx along with MPO activity, leukocyte influx into the synovial membrane, and Evans Blue extravasation. It promoted HO-1 overexpression whilst decreased TNF-α and IL-1β expression in the TMJ tissue. AEL reduced TNF-α and IL-1β levels in TMJ tissue and trigeminal ganglion. AEL effects, however, were not observed in the presence of ZnPP-IX. These findings suggest that AEL efficacy depends on TNF-α/IL-1β inhibition and HO-1 pathway integrity.

Perspectives on next steps in classification of oro-facial pain - part 2: role of psychosocial factors

This study was initiated by a symposium, in which the present authors contributed, organised by the International RDC/TMD Consortium Network in March 2013. The purpose of the study was to review the status of biobehavioural research - both quantitative and qualitative - related to oro-facial pain (OFP) with respect to the aetiology, pathophysiology, diagnosis and management of OFP conditions, and how this information can optimally be used for developing a structured OFP classification system for research. In particular, we address representation of psychosocial entities in classification systems, use of qualitative research to identify and understand the full scope of psychosocial entities and their interaction, and the usage of classification system for guiding treatment. We then provide recommendations for addressing these problems, including how ontological principles can inform this process.

Deficient cytokine control modulates temporomandibular joint pain in rheumatoid arthritis

The aim was to investigate how endogenous cytokine control of tumor necrosis factor (TNF) influences temporomandibular joint (TMJ) pain in relation to the role of anti-citrullinated peptide antibodies (ACPA) in patients with rheumatoid arthritis (RA). Twenty-six consecutive patients with TMJ RA were included. Temporomandibular joint pain intensity was assessed at rest, on maximum mouth opening, on chewing, and on palpation. Mandibular movement capacity and degree of anterior open bite (a clinical sign of structural destruction of TMJ tissues) were also assessed. Systemic inflammatory activity was assessed using the Disease Activity Score in 28 joints (DAS28) for rheumatoid arthritis. Samples of TMJ synovial fluid and blood were obtained and analyzed for TNF, its soluble receptor, soluble TNF receptor II (TNFsRII), and ACPA. A high concentration of TNF in relation to the concentration of TNFsRII in TMJ synovial fluid was associated with TMJ pain on posterior palpation on maximum mouth opening. The ACPA concentration correlated significantly to the TNF concentration, but not to the TNFsRII concentration, indicating that increased inflammatory activity is mainly caused by an insufficient increase in anti-inflammatory mediators. This study indicates that TMJ pain on palpation in patients with RA is related to a deficiency in local cytokine control that contributes to increased inflammatory activity, including sensitization to mechanical stimuli over the TMJ.

Tumor necrosis factor-alpha levels in the synovial fluid of patients with temporomandibular joint internal derangement

PURPOSE

The purpose of this study was to investigate the level of tumor necrosis factor-alpha (TNF-α) in the synovial fluid (SF) of patients with temporomandibular joint (TMJ) internal derangement and to show the relationship between the level of TNF-α and the severity of the disease.

MATERIALS AND METHODS

Arthrocentesis was performed on 32 female and five male patients (aged between 17 and 45) referred to our clinic with the complaint of TMJ pain and discomfort. TNF-α levels were determined in the SF samples obtained during arthrocentesis. As a measure of pain, visual analog scale (VAS) scores were also evaluated.

RESULTS

There were statistically significant differences in VAS scores between the stages. VAS scores were found to be elevated as the stage of disease progressed. Increased levels of TNF-α were found in progressive stages of internal derangement.

CONCLUSION

In our study, both SF TNF-α levels and pain levels (VAS scores) were found to be increased in patients with internal derangement as the stage of the disease progresses. TNF-α might contribute to the pathogenesis of synovitis and the degeneration of the TMJ cartilage and bone.

3D osteoarthritic changes in TMJ condylar morphology correlates with specific systemic and local biomarkers of disease

OBJECTIVE

To assess 3D morphological variations and local and systemic biomarker profiles in subjects with a diagnosis of temporomandibular joint osteoarthritis (TMJ OA).

DESIGN

Twenty-eight patients with long-term TMJ OA (39.9 ± 16 years), 12 patients at initial diagnosis of OA (47.4 ± 16.1 years), and 12 healthy controls (41.8 ± 12.2 years) were recruited. All patients were female and had cone beam CT scans taken. TMJ arthrocentesis and venipuncture were performed on 12 OA and 12 age-matched healthy controls. Serum and synovial fluid levels of 50 biomarkers of arthritic inflammation were quantified by protein microarrays. Shape Analysis MANCOVA tested statistical correlations between biomarker levels and variations in condylar morphology.

RESULTS

Compared with healthy controls, the OA average condyle was significantly smaller in all dimensions except its anterior surface, with areas indicative of bone resorption along the articular surface, particularly in the lateral pole. Synovial fluid levels of ANG, GDF15, TIMP-1, CXCL16, MMP-3 and MMP-7 were significantly correlated with bone apposition of the condylar anterior surface. Serum levels of ENA-78, MMP-3, PAI-1, VE-Cadherin, VEGF, GM-CSF, TGFβb1, IFNγg, TNFαa, IL-1αa, and IL-6 were significantly correlated with flattening of the lateral pole. Expression levels of ANG were significantly correlated with the articular morphology in healthy controls.

CONCLUSIONS

Bone resorption at the articular surface, particularly at the lateral pole was statistically significant at initial diagnosis of TMJ OA. Synovial fluid levels of ANG, GDF15, TIMP-1, CXCL16, MMP-3 and MMP-7 were correlated with bone apposition. Serum levels of ENA-78, MMP-3, PAI-1, VE-Cadherin, VEGF, GM-CSF, TGFβ1, IFNγ, TNFα, IL-1α, and IL-6 were correlated with bone resorption.

Histomorphometry in antigen-induced arthritis of the rabbit temporomandibular joint

BACKGROUND

Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) can cause severe growth disturbances of the craniomandibular system. Antigen-induced arthritis (AIA) of the rabbit TMJ is simulating the inflammatory process of the TMJ in JIA. The aim of this study was to investigate the effect of a systemic administration of the tumor necrosis factor-alpha (TNF-α) antagonist etanercept on AIA in rabbits by means of three different histological staining methods.

METHODS

After sensitization, a bilateral arthritis of the TMJ was induced and maintained by repeated intra-articular administrations of ovalbumin in 12 New Zealand white rabbits aged 10 weeks. From the 13th week of age, 6 of the 12 rabbits received weekly subcutaneous injections of etanercept, and the other 6 animals remained without therapy. Another 6 animals served as controls, receiving no treatment or intra-articular injections at all. After euthanasia at the age of 22 weeks, all TMJs were retrieved en bloc. Sagittal sections were cut and stained with hematoxylin-eosin (H-E), Safranin-O for the evaluation of the Mankin score, and tartrate-resistant acid phosphatase (TRAP).

RESULTS

In the arthritis group, a chronic inflammation with degeneration of the articular cartilage was visible. In the etanercept group, the signs of cartilage degeneration were significantly reduced but present. In contrast, the joints in the control group were inconspicuous. A strong correlation between the Mankin score and TRAP-positive cells could be found.

CONCLUSIONS

Antigen-induced arthritis causes severe damage in the TMJ of young rabbits. An improvement seems to be achievable by a systemic administration of etanercept.

Expanding the taxonomy of the diagnostic criteria for temporomandibular disorders

There is a need to expand the current temporomandibular disorders' (TMDs) classification to include less common but clinically important disorders. The immediate aim was to develop a consensus-based classification system and associated diagnostic criteria that have clinical and research utility for less common TMDs. The long-term aim was to establish a foundation, vis-à-vis this classification system, that will stimulate data collection, validity testing and further criteria refinement. A working group [members of the International RDC/TMD Consortium Network of the International Association for Dental Research (IADR), members of the Orofacial Pain Special Interest Group (SIG) of the International Association for the Study of Pain (IASP), and members from other professional societies] reviewed disorders for inclusion based on clinical significance, the availability of plausible diagnostic criteria and the ability to operationalise and study the criteria. The disorders were derived from the literature when possible and based on expert opinion as necessary. The expanded TMDs taxonomy was presented for feedback at international meetings. Of 56 disorders considered, 37 were included in the expanded taxonomy and were placed into the following four categories: temporomandibular joint disorders, masticatory muscle disorders, headache disorders and disorders affecting associated structures. Those excluded were extremely uncommon, lacking operationalised diagnostic criteria, not clearly related to TMDs, or not sufficiently distinct from disorders already included within the taxonomy. The expanded TMDs taxonomy offers an integrated approach to clinical diagnosis and provides a framework for further research to operationalise and test the proposed taxonomy and diagnostic criteria.

Pressure and inflammatory stimulation induced increase of cadherin-11 is mediated by PI3K/Akt pathway in synovial fibroblasts from temporomandibular joint

OBJECTIVE

The goal of the study was to investigate the expression of cadherin-11 in synovial fibroblasts (SFs) under mechanical or inflammatory stimuli, and its potential relationship with PI3K/Akt signaling pathway.

METHODS

SFs separated from rat temporomandibular joint (TMJ) were treated with hydrostatic pressures (HP) of 30, 60, 90, and 120 kPa, as well as tumor necrosis factor-α (TNF-α) for 12, 24, 48, and 72 h. The location of cadherin-11 was observed by immunofluorescence microscopy, and its expression was detected by real-time PCR and Western blot. We also studied the activation of PI3K/Akt signaling pathway in SFs with HP or TNF-α stimulation.

RESULTS

The results showed that increased expression of cadherin-11 could be found in the cell-cell contact site of SFs in response to HP and inflammatory stimulation. The mRNA and protein expression of cadherin-11 was positively correlated with the intensity of HP and the duration time of TNF-α treatment. Increased expression of vascular endothelial growth factor-D (VEGF-D) and activation of Akt were also found. Treatment with PI3K inhibitor LY294002 attenuated the pressure or inflammatory cytokine induction increases of cadherin-11, VEGF-D, and FGF-2 both in mRNA and protein levels.

CONCLUSIONS

These findings suggest that cadherin-11 may play important roles in SFs following exposure to mechanical loading and inflammatory stimulation. In addition, PI3K/Akt pathway was associated with pressure or inflammation-induced cadherin-11 expression, which may involve in the pathogenesis of temporomandibular diseases.

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.

Limited fatty infiltration due to apoptosis in human degenerated temporomandibular joint disks: an immunohistochemical study

In this study, we hypothesized that caspase 3, which plays a central role in the execution phase of cell apoptosis, could be involved in limiting fatty degeneration of the temporomandibular joint (TMJ) disks and therefore inhibit the TMJ disk tissue from completely degenerating into fatty tissue. Therefore, caspase 3 immunohistochemical expression in human TMJ degenerated disks was studied. Fifty-nine degenerated TMJ disks were stained with Harry's hematoxylin, and they were then examined with light microscopy to detect any pathologic changes typical of fatty degeneration. Sections from the same TMJ disk were immunostained also by a polyclonal anti-caspase 3 antibody. On morphologic observations, 11 disks of 59 degenerated ones also presented a fatty infiltration. Immunostaining with caspase 3 antibody was detected on adipocytes in the cytoplasm as well as the nuclei. Our results sustain the hypothesis that fatty degeneration is limited by apoptosis, being adipocytes immunolabeled by caspase 3 antibody. Hence, apart from the several factors that can trigger degeneration changes in TMJ disk, their appearance, spread, and permanence, at least for fatty degeneration, seem to be influenced by apoptosis.

TNFα Mechanically Sensitizes Masseter Muscle Nociceptors by Increasing Prostaglandin E2 Levels

TNFα induces mechanical sensitization of rat masseter muscle nociceptors, which takes 2–3 h to manifest and is mediated through activation of P55 and P75 receptors. This study was undertaken to determine whether TNFα induces nociceptor mechanical sensitization through the release of other algogenic substances such as glutamate, prostaglandin E2 (PGE2), and/or nerve growth factor (NGF), which have been shown to induce mechanical sensitization of muscle nociceptors. Masseter muscle homogenate levels of PGE2 and NGF were measured 3 h after injection of TNFα (1 μg) or vehicle control using commercially available kits. Interstitial glutamate concentration was measured after injection of TNFα or vehicle control using a glutamate-selective biosensor probe. Diclofenac, a cycloxygenase inhibitor that blocks the synthesis of PGE2, d-2-amino-5-phophonovaleric acid (APV), a competitive N-methyl-d-aspartate (NMDA) receptor antagonist, and a tyrosine kinase A (TrkA) receptor antibody, which blocks NGF-induced masseter muscle nociceptor sensitization, were used to assess the contribution of PGE2, glutamate, and NGF to TNFα-induced nociceptor sensitization. PGE2 and glutamate concentrations were significantly elevated 3 h after TNFα injection into the masseter muscle. Injection of diclofenac partially reversed the TNFα-induced decreases in the mechanical threshold (MT) of masseter muscle nociceptors, whereas vehicle control, APV, and TrkA antibody did not significantly alter nociceptor MT. These results suggest that TNFα-induced mechanical sensitization of masseter muscle nociceptors is mediated in part by increased PGE2 levels. The findings of this study support the hypothesis that TNFα induces a delayed mechanical sensitization of masseter muscle nociceptors indirectly by the release of PGE2.

Interleukin‐1β influences the effect of infliximab on temporomandibular joint pain in rheumatoid arthritis

OBJECTIVES

The aim of this study was to investigate the influence of plasma and synovial fluid tumour necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), IL-6, soluble TNF receptor II (TNF-sRII), IL-1 receptor antagonist (IL-1ra), soluble IL-1 receptor II (IL-1sRII) and IL-10 on the effect of the TNFalpha antibody infliximab on temporomandibular joint (TMJ) pain in patients with active rheumatoid arthritis (RA).

METHODS

Fifteen patients with TMJ pain taking methotrexate were included in the study. The effect of intravenous infusions of infliximab was assessed after 14 or 22 weeks. TMJ resting and movement pain was assessed by a visual analogue scale (VAS) (0-100 mm) and samples of venous blood and TMJ synovial fluid were collected before and after treatment.

RESULTS

The effect of infliximab on TMJ pain was influenced by pretreatment plasma levels of IL-1beta, IL-1ra, and IL-10 as well as pretreatment levels of TMJ synovial fluid IL-1sRII. High pretreatment levels of these cytokines and receptors as well as the presence of rheumatoid factor (RF) were associated with no or minor reduction in TMJ pain after treatment.

CONCLUSIONS

Systemic treatment of RA with a combination of infliximab and methotrexate seems to be insufficient to alleviate TMJ pain in patients with RF or high pretreatment plasma levels of IL-1beta.

TNFalpha mechanically sensitizes masseter muscle afferent fibers of male rats

Behavioral evidence in rats indicates that injection of tumor necrosis factor alpha (TNFalpha) into skeletal muscle results in a prolonged mechanical sensitization without gross inflammation. To investigate whether a peripheral mechanism could underlie this effect, in the present study, TNFalpha (1 or 0.1 microg) was injected into the rat masseter muscle to assess its effect on the excitability and mechanical threshold (MT) of muscle nociceptors as well as on inflammation. Expression of TNFR1 (P55 receptors) and TNFR2 (P75 receptors) by the masseter muscle and trigeminal ganglion neurons that innervate that muscle was determined by Western blot and immunohistochemistry, respectively. The Evans blue dye technique was used at the end of the TNFalpha experiments to assess for plasma protein extravasation. In subsequent experiments to confirm the involvement of receptor activation in TNFalpha-induced effects, P55 or P75 receptor antibody was co-injected with TNFalpha. Intramuscular injection of 1 microg TNFalpha did not excite nociceptors but did significantly decrease MT compared with vehicle control. There was no evidence of gross inflammation 3 h after injection of TNFalpha. Co-injection of TNFalpha with P55 or P75 receptor antibodies attenuated TNFalpha-induced mechanical sensitization. P55 and P75 receptors were expressed by 29 and 62% of masseter nociceptors, respectively. These findings indicate that TNFalpha induces mechanical sensitization of masseter nociceptors that is mediated through activation of peripheral P55 and P75 receptors. These results support the hypothesis that a peripheral receptor mechanism could contribute to TNFalpha-induced noninflammatory mechanical sensitization of skeletal muscle previously reported in behaving rats.

[Cytokine regulation and pain. Results of experimental and clinical research]

Cytokines are soluble peptides and proteins that are predominantly produced and secreted by immune cells. In numerous animal experiments the endogenous increase or application of exogenous pro-inflammatory cytokines is associated with pain behavior. In turn, cytokine inhibitors reduce such pain behavior in inflammatory and neuropathic pain models. Several clinical studies point out that cytokines are also important in different human pain states. Several chronic pain syndromes are associated with systemic pro-inflammatory cytokine profiles. In some pain syndromes these pro-inflammatory profiles are accompanied by a lack of analgesic anti-inflammatory cytokines. Numerous case reports and open clinical studies, but also some controlled trials show successful analgesic treatment using cytokine inhibitors. The following review article summarizes the main data of animal experiments and clinical trials concerning the role of cytokines in pain and the potential importance of cytokine modulation in pain treatment.

Intra-articular vs. systemic administration of etanercept in antigen-induced arthritis in the temporomandibular joint. Part II: mandibular growth

BACKGROUND

Temporomandibular joint (TMJ) arthritis in children causes alterations in the craniomandibular growth. Resultant abnormalities include; condylar erosions, a posterior mandibular rotation pattern, micrognathia, malocclusion with an anterior open bite, altered joint and muscular function occasionally associated with pain. These alterations may be prevented by early aggressive anti-inflammatory intervention. Previously, we have shown that intra-articular (IA) corticosteroid reduces TMJ inflammation but causes additional mandibular growth inhibition in young rabbits. Local blockage of TNF-alpha may be an alternative treatment approach against TMJ involvement in juvenile idiopathic arthritis (JIA). We evaluated the anti-inflammatory effect of IA etanercept compared to subcutaneous etanercept in antigen-induced TMJ-arthritis in young rabbits in terms of mandibular growth. This article (Part II) presents the data and discussion on the effects on facial growth. In Part I the anti-inflammatory effects of systemic and IA etanercept administration are discussed.

METHODS

Arthritis was induced and maintained in the TMJs of 10-week old pre-sensitized rabbits (n = 42) by four repeated IA TMJ injections with ovalbumin, over a 12-week period. One group was treated weekly with systemic etanercept (0.8 mg/kg) (n = 14), another group (n = 14) received IA etanercept (0.1 mg/kg) bilaterally one week after induction of arthritis and one group (n = 14) served as an untreated arthritis group receiving IA TMJ saline injections. Head computerized tomographic scans were done before arthritis was induced and at the end of the study. Three small tantalum implants were inserted into the mandible, serving as stable landmarks for the super-impositions. Nineteen variables were evaluated in a mandibular growth analysis for inter-group differences. All data was evaluated blindedly. ANOVA and T-tests were applied for statistical evaluation using p < 0.05 as significance level.

RESULTS

Significant larger mandibular growth disturbances were observed in the group receiving IA saline injections compared with the systemic etanercept group. The most pronounced unfavourable posterior mandibular rotation pattern was observed in the group receiving IA saline injections.

CONCLUSION

Intervention with systemic etanercept monotherapy equivalent to the recommended human dose allows a mandibular growth towards an original morphology in experimental TMJ arthritis. Systemic administrations of etanercept are superior to IA TMJ administration of etanercept in maintaining mandibular vertical growth.

Intra-articular vs. systemic administration of etanercept in antigen-induced arthritis in the temporomandibular point. Part I: histological effects

BACKGROUND

Temporomandibular joint (TMJ) arthritis in children causes alterations in craniomandibular growth. This abnormal growth may be prevented by an early anti-inflammatory intervention. We have previously shown that intra-articular (IA) corticosteroid reduces TMJ inflammation, but causes concurrent mandibular growth inhibition in young rabbits. Blockage of TNF-alpha has already proven its efficacy in children with juvenile idiopathic arthritis not responding to standard therapy. In this paper we evaluate the effect of IA etanercept compared to subcutaneous etanercept in antigen-induced TMJ-arthritis in rabbits on histological changes using histomorphometry and stereology. This article presents the data and discussion on the anti-inflammatory effects of systemic and IA etanercept. In Part II the data on the effects of systemic and IA etanercept on facial growth are presented.

METHODS

Forty-two rabbits (10 weeks old) pre-sensitized with ovalbumin and locally induced inflammation in the temporomandibular joints were divided into three groups: a placebo group receiving IA saline injections in both joints one week after arthritis induction (n = 14), an IA etanercept group receiving 0.1 mg/kg etanercept per joint one week after arthritis induction (n = 14) and a systemic etanercept group receiving 0.8 mg/kg etanercept weekly throughout the 12-week study (n = 14). Arthritis was maintained by giving four inductions three weeks apart. Additional IA saline or etanercept injections were also given one week after the re-inductions. Histomorphometric and unbiased stereological methods (optical fractionator) were used to assess and estimate the inflammation in the joints.

RESULTS

The histomorphometry showed synovial proliferation in all groups. The plasma cell count obtained by the optical fractionator was significantly reduced when treating with systemic etanercept but not with IA etanercept. Semi-quantitative assessments of synovial proliferation and subsynovial inflammation also showed reduced inflammation in the systemic etanercept group. However, the thickness of the synovial lining and volume of the subsynovial connective tissue showed no differences between the groups.

CONCLUSION

An anti-inflammatory effect of systemic etanercept on the synovial tissues in the temporomandibular joint was shown. However, IA etanercept at the given dose had no significant effect on the severity of chronic inflammation on the parameters here tested in ovalbumin antigen-induced arthritis.

Effect of calcium hydroxide on proinflammatory cytokines and neuropeptides

Calcium hydroxide, a widely used intracanal medicament, is known to exert an antimicrobial effect and to degrade bacterial-derived lipopolysaccharides. However, little is known about the effect of Ca(OH)(2) on endogenous inflammatory mediators such as interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha (TNF-alpha), and calcitonin gene-related peptide (CGRP). This is an important gap in knowledge because these inflammatory mediators play an important role in mediating the pathogenesis of periradicular periodontitis. We tested the hypothesis that Ca(OH)(2) denatures IL-1 alpha, TNF-alpha, and CGRP. Human IL-1 alpha (0.125 ng/mL), TNF-alpha (0.2 ng/mL), and CGRP (0.25 ng/mL) were incubated with Ca(OH)(2) (0.035 mg/mL) for 1-7 days. At the end of the incubation period, the pH of the samples was neutralized, and the concentrations of the mediators were measured by immunoassays. Data were analyzed with one-way analysis of variance and Bonferroni multiple comparison tests. The results indicate that Ca(OH)(2) denatures IL-1 alpha, TNF-alpha, and CGRP by 50%-100% during the testing periods (P < .001). We concluded that denaturation of these proinflammatory mediators is a potential mechanism by which Ca(OH)(2) contributes to the resolution of periradicular periodontitis.

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.

Successful treatment with multiple intra-articular injections of infliximab in a patient with psoriatic arthritis

This case report presents the clinical and radiographic course of temporomandibular joint (TMJ) involvement in a patient with severe TMJ symptoms from psoriatic arthritis (PsA) resistant to both systemic infliximab and intra-articular glucocorticoid and who therefore received multiple intra-articular infliximab injections for 36 weeks. TMJ symptoms improved after the first bilateral intra-articular infliximab injections but even more so after the second injections. The considerable improvement remained for the 36 weeks studied. Bilateral computerized tomography showed no progression in radiographic changes during the treatment. No adverse reaction was observed from the intra-articular injections.

Characterization of a model of chronic orofacial hyperalgesia in the rat: contribution of NA(V) 1.8

The purpose of this study was to develop and characterize a model of orofacial inflammatory hyperalgesia. Injection of complete Freund's adjuvant (CFA) into the upper lip/whisker pad of the rat produced significant and long-lasting thermal (> or =14 days) and mechanical (> or =28 days) hyperalgesia in the area of CFA injection. Both indomethacin and morphine, given systemically, significantly attenuated thermal hyperalgesia; the effect of morphine was shown to be opioid receptor-mediated. We also examined the contribution of the tetrodotoxin-resistant voltage-gated sodium channel Na(v)1.8 in CFA-produced orofacial mechanical hypersensitivity. Na(v)1.8 mRNA was increased > or =2.5-fold in trigeminal ganglion neurons 1 and 2 weeks after CFA treatment, and Na(v)1.8 protein was increased in the infraorbital nerve over a similar time course. The changes observed were time-dependent and had returned to baseline when examined 2 months after inflammation; there were no changes in Na(v)1.9 mRNA in trigeminal ganglion neurons after CFA treatment. In support of this, Na(v)1.8 antisense oligodeoxynucleotide treatment significantly attenuated CFA-produced mechanical hypersensitivity. These results document development of a model of inflammatory orofacial hyperalgesia, which, consistent with other reports, indicate a contribution of tetrodotoxin-resistant, voltage-gated sodium channel Na(v)1.8.

PERSPECTIVE

Orofacial hypersensitivity develops postoperatively as a routine course of orofacial surgery, and mechanical allodynia is characteristic of temporomandibular joint disorder. The results described in this report are novel with respect to the duration of orofacial hypersensitivity produced and suggest that pharmacological targeting of the voltage-gated sodium channel Na(v)1.8 may be useful in managing hypersensitivity.

Indirect mechanism of histamine-induced nociception in temporomandibular joint of rats

A considerable amount of evidence suggests that temporomandibular joint (TMJ) pain associated with temporomandibular disorder results, at least in part, from an inflammatory episode. Although histamine can cause pain, it is not clear whether this mediator induces nociception in the TMJ. In this study, we investigated the contribution of endogenous histamine to formalin-induced nociception in the TMJ of rats. We also investigated whether the administration of histamine induces nociception in the TMJ and, if so, whether this effect is mediated by an indirect action on primary afferent nociceptors. Local administration of the H1-receptor antagonist pyrilamine prevented formalin-induced nociception in the TMJ in a dose-dependent manner. Local administration of histamine (250 microg) in the TMJ induced nociceptive behavior that was inhibited by co-administration of the lidocaine N-ethyl bromide quaternary salt QX-314 (2%) or the selective H1-receptor antagonist pyrilamine (400 microg). Nociception induced by histamine was also inhibited by pre-treatment with sodium cromoglycate (800 microg) and by co-administration of the 5-HT(3) receptor antagonist tropisetron (400 mug), while pyrilamine (400 mug) did not inhibit nociception induced by 5-hydroxytryptamine (5-HT, 250 microg) in the TMJ. Furthermore, histamine, in a dose that did not induce nociception by itself, strongly enhanced 5-HT-induced nociception. Finally, the administration of a sub-threshold dose of 5-HT (100 microg), but not of histamine (100 microg), elicited nociception in the TMJ previously challenged with the inflammatory agent carrageenan (100 microg). In conclusion, these data suggest that histamine induces TMJ nociception by an indirect mechanism involving endogenous release of 5-HT and activation of 5-HT(3) receptors on sensory afferents. It is proposed that histamine activates the H1 receptor to induce the release of 5-HT which depolarizes the nociceptor by activating 5-HT(3) receptor.

Tumor necrosis factor-alpha in temporomandibular joint synovial fluid predicts treatment effects on pain by intra-articular glucocorticoid treatment

The aim of this study was to investigate the influence of tumor necrosis factor-alpha (TNF-alpha) in temporomandibular joint (TMJ) synovial fluid and blood on the treatment effect on TMJ pain by intra-articular injection of glucocorticoid in patients with chronic inflammatory TMJ disorders. High pretreatment level of TNF-alpha in the synovial fluid was associated with a decrease of TNF-alpha and elimination of pain upon maximal mouth opening. Elimination of this TMJ pain was accordingly associated with decrease in synovial fluid level of TNF-alpha. There was also a significant decrease of C-reactive protein and TMJ resting pain after treatment. In conclusion, this study indicates that presence of TNF-alpha in the synovial fluid predicts a treatment effect of intra-articular injection of glucocorticoid on TMJ movement pain in patients with chronic TMJ inflammatory disorders.

Symposium on the musculoskeletal aspects of Marfan syndrome: meeting report and state of the science

The National Marfan Foundation sponsored a symposium in August 2005 to review recent progress in the area of Marfan-related musculoskeletal research. Orthopaedic surgeons, molecular geneticists, medical geneticists, and pain specialists met to review a variety of topics. This report reviews and summarizes the proceedings of the symposium, with emphasis on future directions for study that were identified in the course of the meeting. Areas covered include clinical detection, diagnosis, growth, spine deformity, molecular mechanisms, dural ectasia, protrusio acetabuli, and pain in Marfan syndrome.

Induction of osteoclast-like cells derived from the synovial lavage fluids of patients with temporomandibular joint disorders

OBJECTIVE

Although biochemical studies have examined the synovial fluid (SF) of patients with temporomandibular joint (TMJ) disorders (TMDs), the details of the molecular mechanism of bone destruction and remodeling remain unknown. In this study, we induced and characterized osteoclast-like cells from the SF of patients with TMD and investigated the participation of these cells in the pathogenesis of TMD.

METHODS

We collected SF cells from patients with TMD after a pumping procedure, cultured osteoclast-like cells, and examined their characteristics, including osteoclast markers and bone resorption activities. In addition, we obtained fibroblastic cells from the SF of TMD patients by continuous sub-culturing. Using these fibroblastic cells, we examined fibroblast markers using immunocytochemical staining and analyzed the receptor activator of nuclear-factor-kappaB ligand (RANKL) mRNA levels. Detection of soluble form of RANKL (sRANKL) in the SF was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Osteoclast-like cells were induced from the SF cells of patients with TMD by adding recombinant human (rh) macrophage colony stimulating factor (M-CSF) and either 1,25-dihydroxy vitamin D3 [1,25(OH)2D3] or prostaglandin E2 (PGE2). These multinucleated giant cells were positive for tartrate-resistant acid phosphatase (TRAP) and had the ability to absorb bone. The fibroblastic cells from the SF of TMD patients were positive for fibroblast markers and RANKL mRNA was up-regulated. Detection of sRANKL in SF of patient group was significantly higher than control group.

CONCLUSION

The results suggest that the joint-infiltrating SF cells from TMD patients play important roles in the pathogenesis of these disorders, which is characterized by progressive bone destruction or remodeling.

Hypernociceptive role of cytokines and chemokines: targets for analgesic drug development?

Pain is one of the classical signs of the inflammatory process in which sensitization of the nociceptors is the common denominator. This sensitization causes hyperalgesia or allodynia in humans, phenomena that involve pain perception (emotional component+nociceptive sensation). As this review focuses mainly on animal models, which don't allow discrimination of the emotional component, the terms nociception and hypernociception are used to describe overt behavior induced by mechanical stimulation and increase of nociceptor sensitivity, respectively. Pro- and anti-inflammatory cytokines and chemokines are endogenous small protein mediators released by local or migrating cells whose balance modulates the intensity of inflammatory response. The inflammatory stimuli or tissue injuries stimulate the release of characteristic cytokine cascades, which ultimately trigger the release of final mediators responsible for inflammatory pain. These final mediators, such as prostanoids or sympathetic amines, act directly on the nociceptors to cause hypernociception, which results from the lowering of threshold due to modulation of specific voltage-dependent sodium channels. Furthermore, a direct effect of cytokines on nociceptors is also described. On the other hand, there are also anti-inflammatory cytokines, such as interleukin (IL)-10, IL-4 and IL-13, and IL-1 receptor antagonists (IL-1ra), which inhibit the production of hypernociceptive cytokines and/or the final hypernociceptive mediators, preventing the installation of or the increase in the hypernociception. This review highlights the importance of the direct and indirect actions of cytokines and chemokines in inflammatory and neuropathic hypernociception, emphasizing the evidence suggesting these molecules are potential targets to develop novel drugs and therapies for the treatment of pain.

Reduction of temporomandibular joint pain after treatment with a combination of methotrexate and infliximab is associated with changes in synovial fluid and plasma cytokines in rheumatoid arthritis

The aims were to investigate the effect of intravenous infusions of the tumor necrosis factor-alpha (TNF-alpha) antibody infliximab on symptoms and signs of temporomandibular joint (TMJ) involvement in relation to effects on synovial fluid and plasma proinflammatory TNF-alpha, interleukin-1beta (IL-1beta) and interleukin-6 as well as antiinflam matory soluble TNF receptor II (TNF-sRII), interleukin-1 receptor antagonist (IL-1ra), soluble IL-1 receptor II (IL-1sRII) and interleukin-10 (IL-10) in patients with active rheumatoid arthritis (RA). Nineteen patients with TMJ involvement taking methotrexate were included in the study. TMJ and general joint pain intensity as well as pain on mandibular movements, tenderness to digital palpation, pressure pain threshold and maximum mouth-opening capacity were assessed in a clinical examination. The effect of infliximab was assessed after 2 and 14 or 22 weeks. TMJ synovial fluid and venous blood were collected for cytokine analysis at all occasions while determination of erythrocyte sedimentation rate and C-reactive protein were performed at baseline and at long-term follow-up only. Reduction of TMJ pain was associated with raised levels of synovial fluid TNF-sRII and IL-1sRII as well as raised plasma levels of IL-1ra and IL-10. Decreased erythrocyte sedimentation rate was associated with decreased tenderness to digital palpation. Reduced general joint pain intensity was associated with reduced plasma levels of IL-6 and C-reactive protein. In conclusion, systemic treatment with a combination of infliximab and methotrexate reduces TMJ pain in RA in association with an increase in anti-inflammatory cytokines and receptors in synovial fluid and plasma.

Electrophoretically separation of the synovial fluid proteins in rabbit temporomandibular arthritis induced by mechanical loading

BACKGROUND

The concentration of protein in synovial fluid (SF) of temporomandibular joints (TMJs) with disorders tends to be increased. We investigated the protein composition of SF of rabbits in which arthritis of the TMJ was induced.

METHOD

Arthritis was induced in six TMJs in six rabbits by exertion of a load for 4 weeks. Six non-loaded TMJs in six rabbits served as controls. The protein concentration and content in TMJ SF of the two groups were compared.

RESULTS

The mean protein concentration was higher in the SF of the loaded group than in that of the non-loaded group (1824 microg/ml vs. 398 microg/ml, P = 0.002). Proteins with molecular weights of more than 95 kDa were abundant in the loaded group (P < 0.05).

CONCLUSION

Temporomandibular arthritis induced by mechanical loading in rabbit is accompanied by an increase in the abundance of relatively high molecular weight proteins in SF.