Cytokines in healthy temporomandibular joint synovial fluid

Can treatment with chondroitin and glucosamine sulphate prevent changes in the articular disc caused by temporomandibular joint osteoarthritis?

BACKGROUND

Chondroitin and glucosamine sulphates (CGS) are considered structure-modifying drugs and have been studied in the prevention, delay or reversal of structural morphological changes in joints caused by osteoarthritis.

OBJECTIVE

The aim of the present study was to investigate the action of CGS on the progression of chemically induced osteoarthritis in the temporomandibular joint (TMJ) of rabbits by evaluating the serum levels of tumour necrosis factor (TNF-α) and collagen in the articular discs.

MATERIALS AND METHODS

A sample of 36 male rabbits was divided into three groups: control (CG), osteoarthritis (OG) and treatment (TG). The disease was induced by intra-articular injection of sodium monoiodoacetate (10 mg/mL) in the OG and TG groups bilaterally. After 10 days, the TG animals received subcutaneous injection of chondroitin sulphates and glucosamine (7.5 mg/kg) and the OG and CG received saline solution (50 μL). Euthanasia times were subdivided into 40 and 100 days. Collagen quantification was performed by biochemical and histological analysis and for the quantification of serum levels of TNF-α, an enzyme immunoassay was used.

RESULTS

The TG showed an increase in the collagen area of the articular disc when compared to the CG and the OG. The increase collagen concentration in the discs did not show a statistically significant difference between the groups. Post-treatment TNF-α levels were significantly lower in TG compared to OG.

CONCLUSIONS

The results indicate that CGS treatment delayed the degeneration of the collagen in the TMJ articular disc and reduced serum TNF-α levels, indicating a preventive effect on OA progression.

Comparison of Four Treatment Protocols with Intra-Articular Medium Molecular Weight Hyaluronic Acid in Induced Temporomandibular Osteoarthritis: An Experimental Study

The aim was to compare the effect between a single intra-articular infiltration (1i) and two infiltrations (2i) of medium molecular weight hyaluronic acid (MMW-HA) of high viscosity (HV) and low viscosity (LV) on the histopathological characteristics of temporomandibular joint (TMJ) osteoarthritis (OA) induced in rabbits. An experimental study was conducted on Oryctolagus cuniculus rabbits, including 42 TMJs, distributed between (1) TMJ-C, control group; (2) TMJ-OA, group with OA; (3) TMJ-OA-wt, group with untreated OA; (4) group treated with HA-HV-1i; (5) group treated with HA-HV-2i; (6) group treated with HA-LV-1i; and (7) group treated with HA-LV-2i. The results were evaluated using the Osteoarthritis Research Society International (OARSI) scale and descriptive histology considering the mandibular condyle (MC), the articular disc (AD), and the mandibular fossa (MF). The Kruskal-Wallis test was used for the statistical analysis, considering p < 0.05 significant. All treated groups significantly decreased the severity of OA compared to the TMJ-OA-wt group. The HA-HV-2i group showed significant differences in the degree of OA from the TMJ-OA group. The degree of OA in the HA-HV-2i group was significantly lower than in the HA-LV-1i, HA-LV-2i, and HA-HV-1i groups. The protocol that showed better results in repairing the joint was HA-HV-2i. There are histological differences depending on the protocol of the preparation used: two infiltrations seem to be better than one, and when applying two doses, high viscosity shows better results.

Inflammatory and degenerative effects of induced osteoarthritis/rheumatoid arthritis models on temporomandibular joint of rats

OBJECTIVE

The present study compared three models of induction of osteoarthritis (OA) and rheumatoid arthritis (RA) in the temporomandibular joint (TMJ) of rats.

DESIGN

The induction method was by injection of complete Freund's adjuvant (CFA) + type II bovine collagen (CII). Twenty-four adult male rats were divided into four groups (n = 6): G1: Sham, 50 μL of 0.9% sodium chloride at the base of the tail and in each TMJ; G2: OA, 50 μL CFA+CII in each TMJ; G3: RA+OA, 100 μL of CFA+CII at the base of the tail and 50 μL CFA+CII in each TMJ; G4: RA, 100 μL of CFA+CII at the base of the tail. All injections were repeated 5 days later. Twenty-three days after the first injection, the animals were sacrificed and the TMJs were submitted to histomorphometric analysis and measurement of cytokines. The Kruskal-Wallis and Dunn tests were used (alpha=0.05).

RESULTS

The total thickness of the condylar cartilage increased in G2 in relation to the other groups, G3 and G4 reduced in relation to G1; and G2 and G4 reduced in relation to G2 and G3. The levels of IL-1β, IL-6 and TNF-α increased in the three induction models compared to G1. The level of IL-10 increased in G2 compared to the other groups and reduced in G3 and G4 compared to G1.

CONCLUSION

CFA+CII induced inflammation and degeneration compatible with RA (advanced chronic stage) when injected in the tail, and compatible with OA (acute stage or early disease) when injected only in the TMJ.

Temporomandibular Joint Ankylosis in a Girl Child: Immunochemical Evaluation of Tissue Material Obtained from Repeated Arthroplasty Surgeries

Temporomandibular joint ankylosis (TMJA) is a rare, but debilitating, condition that leads to TMJ joint hypomobility. Surgery is the mainstay for treatment, which is accompanied by rehabilitative and psychological support. Despite the advances in surgical techniques, the recurrence of TMJA post-surgery has been reported as a common complication. Therefore, it becomes essential to investigate and understand the histo-morpho-pathological processes governing these ankylotic changes. Given the lack of such studies in the literature, herein we present a case of a girl child who underwent primary surgery at the age of six years, followed by a second surgery at the age of twelve years. Ankylotic tissue samples collected during both surgeries were studied using various immunohistochemical markers for tissue remodeling, inflammation, antimicrobial activity, and transcriptional regulation. The expression of MMP-2 and -9 was downregulated in repeated surgery materials, whilst MMP-13 was rarely detected in both tissues. Strong MMP-8, TIMP-2, and TIMP-4 expressions were noted in both tissues, showing their anti-inflammatory and protective roles. Moderately strong expression of bFGF, FGFR-1, IL-1α, and TNF-α could indicate sustained tissue growth in the background of inflammation (wound healing). Interestingly, the expression of β-defensin-2 was found to be constant in both tissues, thereby indicating possible ECM remodeling and collagen breakdown. Finally, a moderate expression of RUNX-2, coupled with a low expression of WNT-1 and -3a, could indicate a slow and delayed bone regeneration process. Our results showcase the complex myriad of pathways that could be involved in the progression of TMJA and post-surgery healing processes. Immunopathological studies could aid in improving the diagnosis, treatment, and prognosis for patients affected with TMJA.

Validity of IL-6 and Arthrocentesis in the Cause and Management of Internal Derangement of TMJ

Purpose

The aim of this clinical study was to evaluate the level of Interleukine-6 (IL-6), pre and post arthrocentesis to validate it as a biomarker in the Internal Derangement (ID) of TMJ.

Material and Methods

This study included 30 patients (20 females and 10 males) of Temporo-Mandibular Dysfunction (TMD) with Disc displacement without reduction (DDwoR) Wilkes stage III, who were refractory to conservative management. Arthrocentesis was performed as a therapeutic modality. Synovial fluid aspirates were obtained prior to arthrocentesis and post arthrocentesis with 300 ml of Ringer Lactate solution into the superior joint compartment for the assessment of level of IL-6. The clinical parameters used for correlating the level of IL-6 were degree of pain (VAS I), chewing ability (VAS II), Maximal Mouth Opening (MMO) in both pre and post op phase with the follow-up period of 01 day, 01 week, 01 month, 03 month and 06 month and the results were compared. ELISA was performed to analyze the levels of IL-6 in the aspirates. The clinical parameters and the level of IL-6 were recorded and analyzed statistically.

Results

The study showed ID of TMJ (Wilkes stage III) s are more prevalent in females especially in the fourth decades of life with the mean age of 38.4 years. The post operative assessment in terms of pain, maximum mouth opening, lateral movements of the mandible and the levels of IL-6 were found to be statistically significant with a P value <0.01.

Conclusion

This study validates the role of IL-6 as a definitive biomarker for the pathogenesis of ID of TMJ Wilkes stage III and arthrocentesis proved to be a minimally invasive therapeutic modality for its management.

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.

High pretreatment systemic immune-inflammation index values are associated with diminished short-term success after temporomandibular joint arthrocentesis procedure

Background

The systemic immune-inflammation index (SII) has been demonstrated to be a valid biomarker of a patient's immunological and inflammatory state, with the ability to accurately predict outcomes in a variety of disease conditions. In the absence of comparable studies, we intended to examine the relevance of pretreatment SII in predicting the success rates of temporomandibular joint arthrocentesis (TMJA) at 1-week, 1-month, and 6-month periods, defined as maximum mouth opening (MMO) > 35 mm and VAS ≤ 3.

Methods

A sum of 136 patients with disc displacement without reduction (DDwo-red) who underwent TMJA was included. For each patient, pre-TMJA SII was calculated as; SII = Platelets × neutrophils/lymphocytes. Additionally, baseline MMO and VAS measurements were recorded for each patient. The success criteria of TMJA included MMO > 35 mm and VAS ≤ 3. The optimal pre-TMJA SII cutoff that predicts TMJA success was determined using receiver operating characteristic (ROC) curve analysis. The primary endpoint was the link between the pre-treatment SII and TMJA success (simultaneous achievement of MMO > 35 mm and VAS ≤ 3).

Results

The median pre-TMJA jaw locking duration, maximum mouth opening (MMO), and visual analog score (VAS) were 7 days, 24 mm, and 8, respectively. The overall TMJA success rates were determined as 80.1%, 91.9%, and 69.1% at 1-week, 1-month, and 6-months, respectively. The results of ROC curve analysis exhibited the optimal SII cutoff at 526 (AUC: 67.4%; sensitivity: 66.7%; specificity: 64.2%) that grouped the patients into two subgroups: Group 1: SII ≤ 526 (N = 81) and SII > 526 (N = 55), respectively. Spearman correlation analysis revealed a strong inverse relationship between the pretreatment SII values and the success of TMJA 1-week (r_s: − 0.83; P = 0.008) and 1-month, (r_s: − 0.89; P = 0.03). Comparative analyses displayed that TMJA success rates at 1-week (87.7% vs. 69.1%; P = 0.008) and 1-month (96.2% vs. 80%; P = 0.03) were significantly higher in the SII ≤ 526 than SII > 526 group, respectively, while the 6-month results favored the SII ≤ 526 group with a trend approaching significance (P = 0.084).

Conclusion

The current study's findings suggested the SII as a unique independent prognostic biomarker that accurately predicts treatment outcomes for up to 6 months.

Trial registration The results of this research were retrospectively registered.

Effect of glucosamine sulphate on the temporomandibular joint of ovariectomised rats

Glycosamine is an amino-monosaccharide present in connective and cartilage tissues that contribute to the maintenance, resistance, flexibility, and elasticity of these tissues. This study aimed to determine the in vivo effects of glucosamine sulphate (GS) on the temporomandibular joint (TMJ) of ovariectomised rats (OVX).Thirty-two rats were distributed into four groups as follows: G1, sham-OVX+saline solution; G2, sham-OVX+glucosamine sulphate (80mg/kg) - oral administration; G3, OVX+saline solution; G4, OVX+glucosamine sulphate (80mg/kg) - oral administration. Animals were treated for seven days. The TMJ was removed and stained with toluidine blue. The thickness of the cartilage layers and cytokines IL-1β, IL-6, and TNF-α levels were determined by histomorphometry and immunoassay, respectively. The administration of GS to OVX females did not change the thickness of condylar cartilage when compared with the other groups (p>0.05). There was an increase in the total cartilage thickness in sham-OVX females. IL-1β and TNF-α levels were significantly lower in sham-OVX females than in OVX females, indicating that ovariectomy acts as potent cytokine inducer. IL-6 levels were significantly higher in sham-OVX females. GS did not affect cytokine production in OVX females (p>0.05). In conclusion, the administration of GS did not affect cytokine levels, but did induce an increase in the total thickness of the TMJ condylar cartilage in sham-OVX rats.

Synovial tissue cytokine profile in disc displacement of the temporomandibular joint

BACKGROUND

Symptomatic disc displacement (DD) of the temporomandibular joint (TMJ) may cause pain and limited mouth opening. The aetiopathogenesis is obscure and probably complex, which makes the diagnostic classification crude and mainly based on clinical criteria rather than disease mechanisms, and tissue characteristics.

OBJECTIVES

The study aim was to characterise and quantify synovial tissue in DD, where specific cytokine patterns might serve as potential biomarkers.

METHODS

An observational cohort study was performed harvesting synovial tissue from 63 patients: 44 with DD without reduction (DDwoR) and 19 with DD with reduction (DDwR). DDwoR was subdivided depending on type of onset (sudden, n = 17; delayed, n = 27), and DDwR served as the control group. Proteins were extracted from tissue samples and investigated in a multi-analytic profiling system.

RESULTS

DDwoR patients had significantly higher concentrations in 12 out of 28 analysed cytokines compared to DDwR. In the same statistical model, significantly lower concentrations of interferon gamma-induced protein (IP) 10, osteoprotegerin (OPG) and RANTES were detected in DDwoR patients. Women showed significantly higher concentrations of epidermal growth factor and interleukin (IL) 1ra compared to men. DDwoR with sudden onset had significant higher concentrations of bone morphogenetic protein 4, eotaxin and IL-8 compared to DDwoR with delayed onset.

CONCLUSIONS

Characterising the biomarker panel for TMJ conditions may serve as suggestible targets for disease classification and novel treatment options. The significantly lower concentrations of IP-10, OPG and RANTES could be proposed as putative markers for the separation of the studied conditions to other TMJ diseases.

Synovial fluid levels of VEGF and FGF-2 before and after intra-articular injection of hyaluronic acid in patients with temporomandibular disorders: a short-term study

Our purpose was to measure the temporomandibular joint (TMJ) synovial fluid (SF) levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) before and after intra-articular injection of hyaluronic acid (HA) and to investigate the possible mechanism involved in the therapeutic value of HA. We analysed the synovial fluid of 30 patients with unilateral internal derangement (ID) or osteoarthritis (OA) of the TMJ (confirmed by magnetic resonance imaging and cone-beam computed tomography) and recorded clinical signs and symptoms including maximal mouth opening, subjective joint pain, and joint noise at the patient's each visit. All clinical signs significantly improved after injection of HA, and there was no significant difference between ID and OA groups. In synovial fluid parameters, the concentration of VEGF was significantly higher before treatment with HA than after treatment, but there was no significant difference in the concentration of FGF-2 between before and after treatment. The study findings suggest intra-articular injection of HA may reduce the synovitis and improve the internal state of the TMJ in a short period.

Xanthan gum protects temporomandibular chondrocytes from IL‑1β through Pin1/NF‑κB signaling pathway

Temporomandibular disorder (TMD) is a complicated and multi-factorial disease related to inflammation and cartilage destruction. Intra-articular injection of xanthan gum (XG) has been demonstrated to protect the joint cartilage and reduce osteoarthritis progression. However, the role and mechanism of XG in TMD is still unclear. In the present study, chondrocytes were isolated from rats and identified by immunofluorescence. Cells were stimulated by XG or interleukin (IL)-1β. Cell viability was analyzed by MTT assay. Tumor necrosis factor α (TNF-α) and IL-6 levels were determined by ELISA. The expression of monocyte chemoattractive protein-1 (MCP-1), inducible nitric oxide synthase (iNOS), collagens, matrix metalloproteinases (MMPs), peptidyl-prolyl isomerase 1 (Pin1) and phosphorylated nuclear factor κB (NF-κB) p65 (p-p65) was analyzed by quantitative PCR or western blotting. MMP activity was assessed by gelatin zymography. Compared with the control, XG treatment partially reversed the IL-1β-reduced cell viability. In addition, IL-1β stimulation increased inflammatory cytokine expression, including TNF-α, IL-6 secretion, MCP-1 and iNOS expression, whereas XG treatment reduced the expression of these inflammatory cytokines compared with that of the IL-1β-stimulated cells. Additionally, XG increased the expression of collagen, but reduced MMP expression and activity as compared with that in the IL-1β group. In addition, XG treatment prevented the IL-1β-increased Pin1 and p-p65 expression. These data suggested that XG reduced the expression of inflammatory cytokines and may maintain the balance between collagens and MMPs partially through the Pin1/NF-κB signaling pathway in IL-1β-stimulated temporomandibular chondrocytes. Therefore, XG may be useful in the treatment of TMD.

Muscle-Bone Crosstalk in the Masticatory System: From Biomechanical to Molecular Interactions

The masticatory system is a complex and highly organized group of structures, including craniofacial bones (maxillae and mandible), muscles, teeth, joints, and neurovascular elements. While the musculoskeletal structures of the head and neck are known to have a different embryonic origin, morphology, biomechanical demands, and biochemical characteristics than the trunk and limbs, their particular molecular basis and cell biology have been much less explored. In the last decade, the concept of muscle-bone crosstalk has emerged, comprising both the loads generated during muscle contraction and a biochemical component through soluble molecules. Bone cells embedded in the mineralized tissue respond to the biomechanical input by releasing molecular factors that impact the homeostasis of the attaching skeletal muscle. In the same way, muscle-derived factors act as soluble signals that modulate the remodeling process of the underlying bones. This concept of muscle-bone crosstalk at a molecular level is particularly interesting in the mandible, due to its tight anatomical relationship with one of the biggest and strongest masticatory muscles, the masseter. However, despite the close physical and physiological interaction of both tissues for proper functioning, this topic has been poorly addressed. Here we present one of the most detailed reviews of the literature to date regarding the biomechanical and biochemical interaction between muscles and bones of the masticatory system, both during development and in physiological or pathological remodeling processes. Evidence related to how masticatory function shapes the craniofacial bones is discussed, and a proposal presented that the masticatory muscles and craniofacial bones serve as secretory tissues. We furthermore discuss our current findings of myokines-release from masseter muscle in physiological conditions, during functional adaptation or pathology, and their putative role as bone-modulators in the craniofacial system. Finally, we address the physiological implications of the crosstalk between muscles and bones in the masticatory system, analyzing pathologies or clinical procedures in which the alteration of one of them affects the homeostasis of the other. Unveiling the mechanisms of muscle-bone crosstalk in the masticatory system opens broad possibilities for understanding and treating temporomandibular disorders, which severely impair the quality of life, with a high cost for diagnosis and management.

Correlation of magnetic resonance imaging grades with cytokine levels of synovial fluid of patients with temporomandibular joint disorders: a cross-sectional study

OBJECTIVES

Magnetic resonance imaging (MRI) is a standardized method for assisting joint diagnosis. To validate the reliability of different imaging-based grading systems, this study examined (1) the associations between grading systems for osseous change, joint effusion, and the Wilkes classification of temporomandibular joint (TMJ) disorders and (2) the correlation between cytokines in synovial fluid and imaging-based joint scores.

MATERIALS AND METHODS

Twenty-seven patients, who routinely received numeric rating scale (NRS) and MRI assessment before TMJ arthrocentesis, were enrolled. Each joint was evaluated through the grading criteria for severity of osseous change and joint effusion by blinded observers using MRI. ImageJ was employed for classifying joint effusion. Joint synovial fluid, collected through arthrocentesis, was examined for cytokine expression by using a Luminex multiplex assay. All data were analyzed using the Pearson correlation analysis.

RESULTS

The Wilkes classification was strongly correlated with osseous change scores, but not with joint effusion scores. Joint effusion scores significantly correlated with NRS scores, but not with the Wilkes classification and osseous change scores. Compared with osseous change scores, joint effusion scores had a higher correlation with the levels of inflammatory cytokines (interleukin (IL)-8 and soluble IL-6 receptor (sIL-6R)) and with anti-inflammatory cytokines (soluble tumor necrosis factor receptors I and II (sTNF-RI/II)).

CONCLUSIONS

In patients with TMJ disorders, MRI grades are strongly correlated with NRS scores and levels of cytokines (IL-8, sIL-6R, and sTNF-RI/II) in the synovial fluid.

CLINICAL RELEVANCE

Joint effusion scoring can be a reliable and valid indicator for pathological assessment of TMJ disorders.

Predictors of arthrocentesis outcome on joint effusion in patients with disk displacement without reduction

OBJECTIVES

The aim of this study was to investigate the preoperative variables in patients with articular disk displacement without reduction that may influence the results of arthrocentesis on joint effusion (JE).

STUDY DESIGN

The records of 203 patients with clinical signs and symptoms of unilateral painful disk displacement without reduction and JE, confirmed by magnetic resonance imaging (MRI), and treated with arthrocentesis were selected. The following preoperative data were recorded: sex; age; joint side; pain duration; pain intensity, measurement with the visual analogue scale; and maximum interincisal distance (MID). All patients underwent a second MRI examination 3 to 4 months postoperatively to assess JE. The sample was then divided into 2 groups: group 1 (n = 160) comprised patients with no signs of JE; and group 2 (n = 43) comprised patients still showing signs of JE. Univariate and multivariate analyses were used to compare the groups.

RESULTS

Among the studied variables, pain duration (P = .0175), pain intensity (P < .0001), and MID (P = .0085) were shown to affect arthrocentesis outcomes. The longer the pain duration (odds ratio [OR] = 0.930), the more intense was the pain (OR = 0.346), and the smaller the MID (OR = 0.562), the less were the chances of arthrocentesis completely eliminating JE.

CONCLUSIONS

Pain duration, pain intensity, and MID can be used as predictors for the effect of arthrocentesis on JE outcomes and considered during treatment planning.

Immunohistochemical analysis of IL-1 Receptor 1 in the discs of patients with temporomandibular joint dysfunction

Objective Temporomandibular joint dysfunction (TMD) may affect a patient's quality of life, and one of the etiologies can be anterior disc displacement with reduction (ADDwR) and anterior disc displacement without reduction (ADDWoR). Interleukin 1 Receptor 1 (IL-1R1) is a membrane receptor that plays an important role on initiating immune and inflammatory response by binding the agonists ligands of IL-1 alpha and IL-1 beta. Therefore, the aim of this study was to evaluate, through immunohistochemical analysis, the association of IL-1R1 with TMD. Methods Thirty-nine human disc samples were collected and composed three different groups: ADDwR (n = 19), ADDwoR (n = 12), and control group (n = 8). The samples were immunostained with IL-1R1 antibody and evaluated on both quantity and intensity of staining. Results There was a statistically significant difference (p < 0.05) between the control and test groups for both quantity and intensity of staining. Conclusion IL1-R1 was associated with ADDwR and ADDwoR in TMD discs of humans.

Differential regulation by IFN‑γ on TNF‑α‑induced chemokine expression in synovial fibroblasts from temporomandibular joint

Tumor necrosis factor (TNF)‑α and interferon (IFN)‑γ, are inflammatory cytokines in the synovial fluid of patients with temporomandibular joint disorder (TMD). However, it remains unknown whether they participate in the regulation of various chemokine expression levels associated with TMD. The effects of TNF‑α and IFN‑γ on the expression of several different inflammatory chemokines, including interleukin (IL)‑8, C‑X‑C motif chemokine ligand (CXCL)1, C‑C motif chemokine ligand (CCL)20, CXCL9, CXCL10, and CXCL11 in synovial fibroblasts obtained from the temporomandibular joint (TMJ) were examined. The results demonstrated that TNF‑α increased the mRNA levels of all examined chemokines in synovial fibroblasts obtained from the TMJ. IFN‑γ treatment alone increased the mRNA expression levels of CXCR3 chemokines, including CXCL10, while they were significantly enhanced when administered in combination with TNF‑α compared with either treatment alone. However, the combination of IFN‑γ and TNF‑α resulted in lower mRNA expression levels of IL‑8 and CXCL1 as compared with those induced by TNF‑α alone. The nuclear factor‑κB inhibitor, Bay 11‑7082, decreased the TNF‑α‑mediated expression of IL‑8 and CXCL10 in the absence, and presence of IFN‑γ. In addition, the JAK2 inhibitor, AG490, decreased CXCL10 expression when administered with TNF‑α and IFN‑γ. Finally, the decrease in TNF‑α‑induced IL‑8 caused by IFN‑γ was recovered by AG490. The results of the present study suggest that TNF‑α and IFN‑γ function in a cooperative manner to regulate inflammatory chemokine expression in synovial fibroblasts, which may contribute to the pathological condition of the TMJ.

Idiopathic condylar resorptions: 3-dimensional condylar bony deformation, signs and symptoms

INTRODUCTION

Our aim was to describe 3-dimensional condylar deformation of the temporomandibular joint (TMJ) and symptoms and signs of temporomandibular dysfunction (TMD) in patients with idiopathic condylar resorption (ICR).

METHODS

We included 25 patients with ICR and 25 controls. We performed cone-beam computed tomographic scans and analyzed condylar width, length, and height as well as the condylar axial angle and the condylar neck angle. TMJ cross sections were evaluated for degenerative characteristics and location of bony deformations. Furthermore, symptoms and signs of TMD were described in the ICR group.

RESULTS

In the ICR group, we found statistically significantly reduced condylar width (mean difference, 2.0 mm), height (mean difference, 4.9 mm), and condylar axial angle (mean difference, 10.6°); 84% of the TMJs had a posterior condylar neck angle (control group, 22%). The most common degenerative changes were noncongruent shape of the condyle-fossa relationship (72%), condylar resorption (56%), and nonintact cortex (40%). More than 70% of the joints with bony deformations showed changes along the entire condylar head. Most patients with ICR showed symptoms and signs of TMD; nevertheless, 12% had no signs or symptoms of TMD.

CONCLUSIONS

ICR in the TMJ changes the shape and reduces the size of the condyle. Deformity locations are unspecified, and the entire condyle is often affected. Most patients with ICR have signs or symptoms of TMD; however, a small group was asymptomatic and without clinical signs.

Expression of Interleukin-1 and temporomandibular disorder: Contemporary review of the literature

OBJECTIVE

Temporomandibular disorders (TMD) are a group of conditions affecting the temporomandibular joint (TMJ), leading to jaw dysfunction, joint and muscle pain, and a decrease in quality of life. A communication network of pro- and anti-inflammatory mediators called cytokines maintains the homeostasis of the TMJ. This review will focus on the Interleukin (IL) family of cytokines, which have been quantified in TMJ synovial fluids in a variety of studies. IL-1α and IL-1β have pro-inflammatory effects, while the endogenous receptor antagonist (IL-1RA) inhibits the pro-inflammatory effects of IL-1.

METHODS

A literature search (2006-2016) to identify eligible studies was completed using the PubMed database. Studies identified used saline irrigation to quantify cytokine profiles in synovial fluid of healthy and/or dysfunctional joints.

RESULTS

The initial search yielded 111 articles, 5 of which met the inclusion criteria after inter-reviewer discussion.

CONCLUSIONS

Articles that compared IL-1 concentrations in TMD vs. control groups found significant differences.

IL-1β impedes the chondrogenic differentiation of synovial fluid mesenchymal stem cells in the human temporomandibular joint

Mesenchymal stem cell-based therapy has great therapeutic potential for temporomandibular joint (TMJ) cartilage repair. However, the behavior of mesenchymal stem cells in the inflammatory milieu following their delivery remains poorly understood. Synovial fluid-derived mesenchymal stem cells (SFMSCs) are a promising resource for TMJ cartilage repair, as they are easily obtained from patients with TMJ disorders (TMD). In this study, we obtained SFMSCs from patients with TMD and expanded them in vitro; we then stimulated the cells with interleukin (IL)‑8, IL-1β, IL-6, IL-10, tumor necrosis factor (TNF)-α and IL-12p. The cells expressed CD90, CD44, CD105 and CD73, and were negative for CD45, CD34, CD11b, CD19 and HLA-DR. They could be induced to differentiate into osteogenic, chondrogenic, adipogenic and neurogenic lineages in vitro. Only the levels of IL-6 and IL-8 were upregulated significantly following stimulation with IL-8, IL-1β, IL-6, IL-10, TNF-α and IL-12p. Furthermore, IL-6 and IL-8 expression was driven mainly by IL-1β-dependent nuclear factor-κB (NF-κB) pathway activation, and was independent of IL-8, IL-6, IL-10, TNF-α and IL-12p. IL-6 and IL-8 expression was inhibited completely by treatment with the NF-κB inhibitor, BAY11-7082. SRY-box 9 (SOX9) was downregulated and matrix metalloproteinase (MMP)13 was upregulated upon chondrogenic differentiation induced in the cells also exposed to IL-1β. Sulfated glycosaminoglycan production was also reduced upon chondrogenic differentiation in the presence of IL-6, but not IL-8. Thus, IL-1β in the inflammatory milieu is crucial in regulating SFMSCs. In doing so, IL-1β impedes the chondrogenic differentiation of SFMSCs. The upregulation of IL-6 and NF-κB pathway activation also contribute to this biological behavior. The findings of our study indicate the potential adverse effects of IL-1β on the chondrogenic differentiation of SFMSCs, and may thus provide new insight into the pathogenesis of TMD.

IL-1β-regulating angiogenic factors expression in perforated temporomandibular disk cells via NF-κB pathway

BACKGROUND

A high density of blood vessels is observed in the perforated disks of temporomandibular joint (TMJ), but the underlying mechanism is unknown. This study aimed to explore the regulation of disk angiogenesis in the perforated disks.

METHODS

Expressions of vascular endothelial growth factor (VEGF), angiogenin-1 (Ang-1), chondromodulin-1 (ChM-1), and thrombospondins-1 (TSP-1) were compared between healthy and perforated TMJ disk cells with or without interleukin-1β (IL-1β) incubation. The tube formation, cell migration, and expressions of matrix-metalloproteinases (MMPs) in human umbilical vein endothelial cell line (HUV-EC-C) were investigated in conditional media of disk cells. Western blot was performed to determine protein level of VEGF, Ang-1, ChM-1 and TSP-1 in IL-1β-induced disk cells cultured by NF-κB- or P38-specific pathway inhibitors, respectively.

RESULTS

Conditional media from perforated disk cells induced more tube formation, cell migration, and MMPs' expression in HUV-EC-C. Expressions of VEGF and Ang-1 were significantly higher, and ChM-1 and TSP-1 were lower in perforated disks compared to healthy disks. The VEGFA concentration was 291.1 ± 36.09 pg/ml in perforated disk cell conditioned media, markedly larger than that in NDCCM (144.9 ± 33.69 pg/ml). IL-1β induced VEGF through NF-κB signaling pathway and Ang-1 through p38 MAPK pathway, while repressed expression of ChM-1 and TSP-1 was through NF-κB pathway. Blockade of each pathway markedly restrained inducing effect of cultural media on HUV-EC-C tube formation and migration.

CONCLUSIONS

Perforated disk cells secreted more angiogenic factors which might induced via NF-κB pathway.

Signs and symptoms after temporomandibular joint washing and cannula placement assessed by cone beam computerized tomography

OBJECTIVE

Analyses of temporomandibular joint synovial fluid using the hydroxocobalamin push-pull technique are increasingly used. However, objective complications and subjective experiences from this procedure have not been described. Firstly, this study aimed to describe discomfort and potential side-effects of this method with special emphasis on symptoms related to the arthrocentesis to be used for future patient information and Ethical Committee applications. Secondly, this study aimed to evaluate the use of cone beam computed tomography (CBCT) as control of intra-capsular cannula placement.

METHODS

Twenty healthy, young adult volunteers were included. Extensive objective and subjective questionnaires were completed before and 14 days after the synovial fluid sampling. With the cannula inside the joints a CBCT was done to investigate if this procedure can be used to verify intra-capsular cannula position.

RESULTS

The subjective findings: Most subjects did experience mild pain or discomfort post-operatively. In 12 of 20 subjects symptoms had resolved after 2 days and no subjects had symptoms for more than a week. The longer lasting symptoms were mainly transient joint sounds on mandibular movement. Objective findings: 14 days after the sampling mandibular protrusion had improved 1 mm, but all other objective measures were equal compared to baseline. CBCT showed a large variation in cannula position and no conclusions could be drawn from this.

CONCLUSION

The hydroxocobalamin push-pull synovial fluid sampling may cause minor, transient symptoms. CBCT does not seem to provide any clinical benefits concerning the correct cannula position in relation to the upper joint compartment and disc.

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.