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

Stabilization Splint Therapy for Patients with Temporomandibular Disorders Improves Opening Movements and Jaw Limitation and Attenuates Pain by Influencing the Levels of IL-7, IL-8, and IL-13 in the Gingival Crevicular Fluid

Background and Objectives: In recent years, numerous studies have investigated and analyzed the levels of molecular biomarkers of temporomandibular disorders (TMD) from various tissue samples and body fluids. However, no study has investigated gingival crevicular fluid (GCF) in TMD patients. The purpose of this study was to determine the concentrations of pro-inflammatory cytokines in GCF before and after stabilization splint (SS) therapy in patients with painful TMD, to investigate whether SS administration causes changes in the concentrations of pro-inflammatory cytokines. An additional aim was to investigate the relationship of GCF cytokine levels with chronic pain intensity and clinical parameters. Materials and Methods: This prospective cohort study included 36 patients who were diagnosed with painful TMD using the Diagnostic Criteria for TMD (DC/TMD). GCF samples were collected at baseline before SS treatment (T0) and at one month (T1) and three months (T2) after the start of therapy. Customized ProcartaPlex Multiplex assays from eBioscience (Invitrogen™, Thermo Fisher Scientific, Viena, Austria) were used for the quantitative analysis of pro-inflammatory cytokines (IL-1β, IL-6, IL-7, IL-8, IL-13, and TNF-α). Patients filled out Croatian versions of questionnaires for self-assessment from Axis II DK/TMP: Graded Chronic Pain Scale (v2) (GCPSv2) and Jaw Function Limitation Scale-20 (JFLS-20). Results: The results showed that the GCF levels of IL-7 (Friedman's test, p = 0.008) and IL-13 (Friedman's test, p = 0.003) were significantly decreased at T2. The GCF level of IL-13 was in negative correlation with chronic pain grade score at T2 (Rho = -0.333), while the GCF level of IL-8 was in positive correlation with mobility limitation (Rho = 0.382) at T1. Conclusions: The results indicate that SS therapy might have a role in reducing inflammation and that the GCF could be a valuable medium for assessing molecular biomarkers.

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.

Causal relationship between psychiatric traits and temporomandibular disorders: a bidirectional two-sample Mendelian randomization study

OBJECTIVES

This study was to investigate the causal relationship between temporomandibular disorders (TMD) and psychiatric disorders by Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

A two-sample bidirectional MR analysis was adopted to systematically explore the causal relationship between TMD and eight psychiatric traits, including anxiety disorder (AD), panic disorder (PD), major depressive disorder (MDD), neuroticism, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), bipolar disorder (BIP), and schizophrenia (SCZ). Inverse variance weighted (IVW), weighted median, and MR-Egger regression were used in my study. Furthermore, we also performed three sensitivity analyses to illustrate the reliability of the analysis.

RESULTS

Two psychiatric traits have risk effects on TMD: PD (OR = 1.118, 95% CI: 1.047-1.194, P = 8.161 × 10-4, MDD (OR = 1.961, 95% CI: 1.450-2.653, P = 1.230 × 10-5). Despite not surpassing the strict Bonferroni correction applied (P > 0.00625), we could think that there was a suggestive causal effect of neuroticism and SCZ increasing the risk of TMD. On the reverse MR analysis, we found no significant evidence of causal effects of TMD on these psychiatric traits. Except for heterogeneity in the causal analysis for SCZ on TMD, no heterogeneity and horizontal pleiotropy were detected in the other analyses.

CONCLUSIONS

Our two-sample MR study has provided further evidence of PD and MDD being related to a higher risk of TMD.

CLINICAL RELEVANCE

These findings highlight the importance of closely monitoring mental traits during future TMD treatments to prevent an increased risk of TMD.

Comparative evaluation of the trabecular structure of the mandibular condyle, the levels of salivary cortisol, MMP-3, TNF-α, IL-1β in individuals with and without temporomandibular joint disorder

OBJECTIVE

Temporomandibular disorder (TMD) is still a challenge in terms of diagnosis and management. The aim of this study is to explore if the evaluation of salivary biomarkers and fractal dimension (FD) of mandibular condyle could be useful for interpreting early degenerative changes and the effectiveness of salivary cortisol in determining the stress levels of TMD patients.

MATERIALS AND METHODS

34 patients with TMD, and 34 healthy controls were included in this study. Saliva samples were obtained from all participants between 09:00-12:00 am. Salivary cortisol, IL-1β, TNF-α, and MMP-3 levels were evaluated with ELISA method. FD of the mandibular condyle was determined by means of box-counting method. Depression and anxiety were determined with PHQ-9 and GAD-7 questionnaires.

RESULTS

The salivary cortisol and depression/anxiety were higher in study group; however, not significant (p>0.05). FD of the study group was found significantly lower than the control group (p<0.01). Salivary TNF-α, IL-1β and MMP-3 levels were showed no significant difference between the two groups (p>0.05). There were no significant correlations between the evaluated parameters.

CONCLUSION

Salivary cortisol seems to be a non-invasive way of measuring physiological stress of TMD patients. Fractal analysis may be a useful tool in detecting early structural changes in mandibular condyle. Salivary TNF-α. IL-1β and MMP-3 have not a diagnostic value in terms of interpreting early degenerative changes.

Cannabis Bioactive Compound-Based Formulations: New Perspectives for the Management of Orofacial Pain

The management of orofacial pain to alleviate the quality of life of affected patients is becoming increasingly challenging for scientific research and healthcare professionals. From this perspective, in addition to conventional therapies, new alternatives are being sought, increasingly looking at the use of both natural and synthetic products. Cannabis sativa L. represents an interesting source of bioactive compounds, including non-psychoactive cannabinoids, flavonoids, and terpenes, many of which are effective in improving pain intensity. Here, we aim to analyze the possible mechanisms of action of the bioactive natural and synthetic hemp-derived compounds responsible for the modulatory effects on pain-related pathways. The ability of these compounds to act on multiple mechanisms through a synergistic effect, reducing both the release of inflammatory mediators and regulating the response of the endocannabinoid system, makes them interesting agents for alternative formulations to be used in orofacial pain.

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.

Proinflammatory cytokines levels in patients with temporomandibular joint disorder undergoing arthroscopy

PURPOSE

Biomarkers represent objective indicators of normal processes, pathology, or responses to therapeutic intervention. The purpose of this study is to evaluate the levels of proinflammatory cytokines in synovial fluid of the temporomandibular joint (TMJ) and to investigate whether there is a correlation between elevated levels and disease progression.

MATERIALS AND METHODS

This is a prospective study that included patients who were diagnosed with internal derangement according to magnetic resonance imaging and were classified according to Wilkes's classifications. After failing to improve with conservative treatment, they were referred for TMJ arthroscopy. During arthroscopy, synovial fluid was collected for biomarker analyses that included the investigation of levels of proinflammatory cytokines: tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and vascular endothelial growth factor (VEGF). The Mann-Whitney U test was used for differences between subgroups for TNF-α, IL-6, and VEGF.

RESULTS

During the study period, 22 patients presented with a TMJ disorder and met the criteria of the study. There was a statistically significant correlation between the levels of VEGF, TNF-a, and osteoarthritis (P < 0.05). There was also a statistically significant correlation between TNF-a levels and a higher degree of chondromalacia (P = 0.019).

CONCLUSION

An increase in inflammatory cytokines coupled with chondromalacia propose a more aggressive degenerative disease.

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.

Neuroimmune interactions in painful TMD: Mechanisms and treatment implications

The underlying mechanisms and treatment of painful temporomandibular disorders (TMDs) are important but understudied topics in craniofacial research. As a group of musculoskeletal diseases, the onset of painful TMD is proved to be a result of disturbance of multiple systems. Recently, emerging evidence has revealed the involvement of neuroimmune interactions in painful TMD. Inflammatory factors play an important role in peripheral sensitization of temporomandibular joint (TMJ), and neurogenic inflammation in turn enhances TMJs dysfunction in TMD. Furthermore, centralized neuroimmune communications contribute to neuron excitability amplification, leading to pain sensitization, and is also responsible for chronic TMD pain and other CNS symptoms. Therapeutics targeting neuroimmune interactions may shed light on new approaches for treating TMD. In this review, we will discuss the role of neuroimmune interactions in the onset of painful TMD from the peripheral and centralized perspectives, and how understanding this mechanism could provide new treatment options. Insights into the neuroimmune interactions within TMJs and painful TMD would broaden the knowledge of mechanisms and treatments of this multifactorial disease.

Glia and Orofacial Pain: Progress and Future Directions

Orofacial pain is a universal predicament, afflicting millions of individuals worldwide. Research on the molecular mechanisms of orofacial pain has predominately focused on the role of neurons underlying nociception. However, aside from neural mechanisms, non-neuronal cells, such as Schwann cells and satellite ganglion cells in the peripheral nervous system, and microglia and astrocytes in the central nervous system, are important players in both peripheral and central processing of pain in the orofacial region. This review highlights recent molecular and cellular findings of the glia involvement and glia–neuron interactions in four common orofacial pain conditions such as headache, dental pulp injury, temporomandibular joint dysfunction/inflammation, and head and neck cancer. We will discuss the remaining questions and future directions on glial involvement in these four orofacial pain conditions.

Effect of simultaneous application of arthrocentesis and occlusal splint versus splint in management of non-reducing TMJ disc displacement

Background/Purpose

This study aimed to compare the effect of four approaches in the treatment of TMJ disc displacement without reduction (DDwoR).

Materials and methods

Thirty-two patients (40 joints) with mean age 28.025 ± 7.18 (23 female patients and nine male patients) were assigned randomly into four groups (10 joints in each group). Group I, patients were treated by centric splint. Group II, patients were treated by distraction splint. Group III, patients were treated by arthrocentesis and centric splint, while group IV patients were treated by arthrocentesis and distraction splint. The groups were compared in terms of joint function (mouth opening), joint pain through joint palpation, and use of visual analog scale (VAS). These records were taken preoperatively, two weeks, one month, three, and six months postoperatively. Also, the presence of disc recapture was evaluated in all patients on MRI at the end of the treatment period.

Results

Significant improvements in all parameters were recorded in all groups. At two weeks postoperatively, there was a significant improvement in all parameters in group III and group IV than group I and group II, while there was no statistical difference between group III and group IV. Regarding mouth opening and joint palpation, there was a significant improvement in group III than group I and group II. Also, there was a significant improvement in group IV than group II at the subsequent follow-up periods. Regarding VAS, at one and three months postoperatively, there was a significant improvement in group III than other groups.

Conclusion

However, both types of splints provide better results without a statistical difference; the simultaneous application of arthrocentesis and occlusal splint decreases pain and improving the function effectively and more rapidly.

Increased chemokine RANTES in synovial fluid and its role in early-stage degenerative temporomandibular joint disease

BACKGROUND

Degenerative joint disease (DJD) of the temporomandibular joints (TMJs) in adolescents and young adults is closely associated with disc displacement without reduction (DDw/oR).

OBJECTIVE

This study aimed to determine the pathogenesis of early-stage TMJ DJD induced by DDw/oR.

METHODS

31 female subjects aged 12-30 years were enrolled, comprising 12 patients with DDw/oR without DJD, 13 with DDw/oR and early-stage DJD, and 6 healthy volunteers. The synovial fluid samples of the subjects were screened for 27 inflammatory-related cytokines using multiple cytokine array. Significantly increased cytokines and a key regulator of osteoclastogenesis "receptor activator of nuclear factor-κB ligand" (RANKL) were further determined by sandwich immunoassay. These factors were also assessed for the possible pathophysiologic actions on RAW264.7 cell proliferation, migration, osteoclastogenesis and bone-resorbing activity using Cell Counting Kit-8, Transwell system, tartrate-resistant acid phosphatase staining and osteo assay plates.

RESULTS

Macrophage-derived inflammatory protein-1 beta (MIP-1β) and regulated upon activation normal T cell expressed and secreted (RANTES) were found to vary significantly in relation to the controls. In contrast to an unchanged concentration of RANKL, a strong increase in the level of RANTES was detected in subjects with DDw/oR and early-stage DJD. MIP-1β concentrations were only elevated in subjects with DDw/oR without DJD. Functionally, both MIP-1β and RANTES could enhance macrophage migration in a concentration-dependent manner, while only RANTES exhibited a promoting effect on osteoclast formation and bone-resorbing activity.

CONCLUSIONS

Chemokine RANTES was significantly upregulated and might be a key regulator of osteoclastogenesis contributing to DDw/oR-induced early-stage TMJ DJD.

Immunohistochemical panel of degenerated articular discs from patients with temporomandibular joint osteoarthritis

BACKGROUND

Temporomandibular joint osteoarthritis (TMJOA) is a progressive degenerative disease caused by imbalance between anabolic and catabolic stimuli.

OBJECTIVE

The aim of this study was to evaluate histopathological changes, collagen degeneration and the expression of eleven TMJOA biomarkers in articular discs.

METHODS

Specimens were obtained from eight female patients submitted to discectomy. Discs were divided into anterior band (AB), intermediate zone (IZ) and posterior band (PB) for computerised histomorphometric analyses. Each was assigned a histopathological degeneration score (HDS). Collagen degeneration was assessed with Picrosirius-polarisation method. Biomarkers were evaluated through immunohistochemistry, including IGF-1, OPG, VEGF, TNF-α, FGF-23, IHH, MMP-3, MMP-9, TGF-β₁ , BMP-2 and WNT-3. Image processing software was used to calculate average immature collagen ratios and immunostained areas. Spearman rank tests were applied to verify correlations, with significance level of 0.05.

RESULTS

The HDS showed negative correlation with expression of VEGF in IZ and PB (P < .05) and positive with TNF-α in AB (P < .01). Collagen degeneration correlated with TGF-β₁ (P < .05), BMP-2 (P < .01) and IHH (P < .05) immunostained areas in the IZ; TGF-β_1, BMP-2 and IHH expression correlated among each other in AB and IZ (P < .05).

CONCLUSION

Angiogenesis and tissue fragmentation may result from aberrant physiologic responses mediated by VEGF and TNF-α, compromising TMJ discs during OA progression. The expression of TGF-β_1, BMP-2 and IHH could be related to collagen degeneration in displaced discs and may participate in TMJOA pathogenesis.

Correlation of molecular biomarker concentrations between synovial fluid and saliva of the patients with temporomandibular disorders

OBJECTIVES

The synovial membrane and fluid are involved in the pathogenesis of temporomandibular joint (TMJ) disorders. This study aims to assess the relationship between matrix metalloproteinase-2 (MMP-2), chemerin and prostaglandin (PGE₂) levels in the synovial fluid (SF) and saliva of patients with TMJ disorder regarding their role in inflammation and the value of being a candidate for predictive biomarkers in the disease. Also, it is aimed to find out whether chemerin's main function triggers the formation inflammatory cytokine markers in the associated area.

MATERIALS AND METHODS

Thirty-two samples of SF and saliva were obtained from patients with disc displacement without reduction with limited opening (DDWORwLO). Mann-Whitney-U test was used for the comparisons of the biomarker levels in SF and saliva. The correlation between chemerin and BMI (Body Mass Index) is analyzed by non-parametric Spearman's rho correlation coefficient.

RESULTS

For all of the three biomarkers, statistically significant differences were found between SF and saliva. An unexpectedly high level expression of chemerin was observed in SF. A statistically significant, positive correlation was observed between PGE₂ -MMP-2, and chemerin-PGE₂ in saliva, chemerin and MMP-2 in SF, respectively (p = 0.031, r = 0.382 / p = 0.039, r = 0.366 / p = 0.032, r = 0.379). A positive correlation was determined between saliva and SF levels of PGE₂ (p = 0.016, r = 0.421).

CONCLUSIONS

Chemerin, MMP-2, and PGE₂ can play a role as an inflammatory factor for the development of TMJ disorder.

CLINICAL RELEVANCE

The search for molecular markers in TMJ and the inhibition of the associated molecular signaling mechanism is important to reduce joint inflammation and cartilage degradation.

Immunohistochemical expression of TLR-4 in temporomandibular joint dysfunction

Objective Toll-like receptor 4 (TLR-4) is a transmembrane protein involved in the innate immune system and has been implicated in the pathogenesis of temporomandibular joint dysfunction (TMD). The purpose of this study was to histologically examine the level of expression of TLR-4 relative to severity of TMD. Methods Thirty-one human TMJ disc samples were immunostained for TLR-4 and evaluated for intensity of stain. Among the samples, 8 were control samples, 16 were from patients with anterior disc displacement with reduction (ADDwR), and 7 were from patients with anterior disc displacement without reduction (ADDwoR). Results There was no statistically significant difference in intensity of stain between groupings (p = 0.673). Conclusions The results indicate a negative correlation between TMD and the expression of TLR-4.

Analysis of synovial fluid visfatin level in temporomandibular joint disorders

Background: Biochemical analysis of synovial fluid (SF) is an important means of understanding the pathogenesis of temporomandibular disorder (TMD) and confirming diagnoses made using traditional methods. Objective: The aim of this study was to determine whether or not SF visfatin levels can serve as a biochemical marker in the diagnosis of TMD. Method: Sixty samples of SF were obtained from 60 patients with internal derangement (ID) or osteoarthritis (OA). Visfatin in the SF was examined by enzyme-linked immunosorbent assay (ELISA). Result: Visfatin levels showed positive correlations with TMD pain and ID stage and a negative correlation with maximum mouth opening. In addition, Visfatin levels in joints with OA changes in the condyle were significantly higher in comparison to joints with no OA changes. Conclusion: Within the limitations of this study, it can be concluded that visfatin may play a role in the pathogenesis of TMD.

Expression of chemerin in the synovial fluid of patients with temporomandibular joint disorders

The synovial membrane and fluid are significantly involved in the pathogenesis of temporomandibular joint (TMJ) disorders. This study aimed to investigate the relation between levels of chemerin in the synovial fluid (SF) of patients with TMJ disorder and their relationship. Sixty samples of SF were obtained from patients with an internal derangement (ID) or osteoarthritis (OA). Chemerin in the SF was examined by enzyme-linked immunosorbent assay (ELISA). The results showed greater levels of chemerin in the SF of patients with OA than ID. While chemerin levels were positively correlated with pain scores, they were inversely correlated with MMO. Chemerin levels increased progressively as the disorder stage became more severe. The findings of this study suggest that chemerin in SF may play role as a predisposing factor and may represent a novel potential prognostic biochemical marker in the pathogenesis of TMJ disorders.

Mesenchymal Stem Cell-Derived Exosomes: Immunomodulatory Evaluation in an Antigen-Induced Synovitis Porcine Model

Synovitis is an inflammatory process associated with pain, disability, and discomfort, which is usually treated with anti-inflammatory drugs or biological agents. Mesenchymal stem cells (MSCs) have been also successfully used in the treatment of inflammatory-related diseases such as synovitis or arthritis. In the last years, the exosomes derived from MSCs have become a promising tool for the treatment of inflammatory-related diseases and their therapeutic effect is thought to be mediated (at least in part) by their immunomodulatory potential. In this work, we aimed to evaluate the anti-inflammatory effect of these exosomes in an antigen-induced synovitis animal model. To our knowledge, this is the first report where exosomes derived from MSCs have been evaluated in an animal model of synovitis. Our results demonstrated a decrease of synovial lymphocytes together with a downregulation of TNF-α transcripts in those exosome-treated joints. These results support the immunomodulatory effect of these exosomes and point out that they may represent a promising therapeutic option for the treatment of synovitis.

Lubricin in synovial fluid of mild and severe temporomandibular joint internal derangements

BACKGROUND

To understand the molecular basis of temporomandibular joint (TMJ) pathologies, we aimed to investigate the lubricin levels in the TMJ synovial fluid (SF) of patients with mild to severe internal derangements (IDs).

MATERIAL AND METHODS

A total, 34 joints were the study group. Only patients, with a Wilkes stage of III, IV and V were included, in this sample. Control group consisted of SF from eight joints, from patients undergoing to orthognatic surgery. Concentrations of lubricin in the SF from both samples were measured using ELISA system.

RESULTS

The mean lubricin concentration was 7.029 ± 0.21 µg/mL in stage III patients; 5.64 ± 0.10 µg/mL in stage IV patients, and 4.78 ± 0.11 µg/mL in stage V patients. The lubricin levels from stage IV and stage V patients differed significantly (P ≤ 0.001) from those of control subjects. Lubricin levels were inversely correlated with age and to VAS score.

CONCLUSIONS

The results of this cross-sectional study highlight the relationship between disease severity and the levels of lubricin in TMJ SF. Our findings suggest that novel biotherapeutic approaches, including the administration of recombinant lubricin in the joint cavity, for the treatment of TMJ diseases can be developed.