Identification of matrix metalloproteinases (MMPs) in synovial fluid from patients with temporomandibular disorder

The Contemporary Management of Temporomandibular Joint Intra-Articular Pain and Dysfunction

The understanding of the causes of temporomandibular joint pain and dysfunction has evolved over 50 years. Historically, the term internal derangement has been used to describe the abnormal relationship between the articular disc, condyle, and glenoid fossa, which was thought to correlate with patient symptoms. It is now known that the pathophysiology of intra-articular pain and dysfunction (IPD) involves synovitis, capsular impingement, symptomatic disc displacement, or a combination of these. Symptomatic disc displacement should only be considered to be a potential source of IPD after synovitis and capsular impingement have been treated. This philosophy provides the opportunity for most patients with IPD to be initially treated nonsurgically or with minimally invasive procedures such as arthrocentesis or arthroscopy.

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.

MMPs in tissues retrieved during surgery from patients with TMJ disorders relate to pain more than to radiological damage score

Orofacial pain is among the most common chronic pain conditions and can result from temporomandibular disorders (TMDs) of the temporomandibular joint (TMJ). Matrix metalloproteinases (MMPs) drive degeneration of TMJ tissues and likely mediate pain in TMJ disorders given their role in nociception. However, few studies have assessed MMPs in the TMJ innervated tissues nor in the context of pain. This study defined the extent of MMP-1, MMP-9, and MMP-2 in TMJ tissues from patients undergoing total joint replacement (TJR) or arthroplasty discectomy for painful TMJ disorders. Protein expression was probed by Western blot in TMJ disc and capsular ligaments taken during TJR (n = 6) or discectomy (n = 3) for osteoarthritis or internal derangement in an IRB-approved study. Pro- and active MMP-1, active MMP-9, and pro- and active MMP-2 are detectable. MMP-1 and MMP-9 correlate positively to each other (Kendall's τ = 0.63; p = 0.01), strengthening the hypothesis that they are mechanistically related in regulatory cascades. Active MMP-1 and active MMP-9 correlate positively with self-reported pain scores (τ ≥ 0.51; p ≤ 0.04), suggesting their involvement in peripheral nociception. Overall, neither MMPs nor pain correlate with the functional vertical opening of the jaw. MMP-1 varies with the observed stage of degeneration during surgery (p = 0.04). Neither overall MMPs nor pain correlate with the overall magnetic resonance imaging scores, corroborating the longstanding, but confounding, clinical observation that pain and radiological evidence of joint damage are not always related. Clinical significance: These findings suggest that MMPs mediate pain in innervated soft tissues and may be targets for diagnosing disease stage and treatments in painful TMJ disorders.

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.

MMP-7 and MMP-9 are overexpressed in the synovial tissue from severe temporomandibular joint dysfunction

Matrix metalloproteinases (MMPs) are tissue-enzymes that play a key role during the remodeling process, such as in inflammatory diseases. MMP-7 and MMP-9 have been shown to be implicated in extracellular matrix homeostasis and in joint disc remodeling. The objective of this study was to determine the relation of MMP-7 and MMP-9 expression with severe temporomandibular joint dysfunction, in particular with anterior disk displacement without reduction (ADDwoR), using an immunohistochemical approach. Therefore, twenty human temporomandibular synovia in the test group and ten in the control group were collected. The results showed there was a statistically significant difference (P<0.001) for morphometric and densitometric analysis of both detected MMPs in control and test groups. In conclusion, MMP-7 and MMP-9 were overexpressed in the synovial tissue of patients with ADDwoR.

Relationship between arthroscopic findings of synovitis and levels of tumour necrosis factor-alpha and matrix metalloproteinases in synovial lavage fluid from patients with unilateral high mandibular condyle fractures

Arthrocentesis has an effect of washing out inflammatory products that accumulate in the joint compartment of a dysfunctional temporomandibular joint (TMJ). The procedure removes inflammatory cytokines, which are pain-causing substances, for early reduction of TMJ pain and quick recovery of jaw function, thus increasing the possibility of a successful rehabilitation. The aim of this study was to investigate the relationship between arthroscopy synovitis grade in patients with unilateral high condylar fractures and concentrations of the pro-inflammatory cytokines tumour necrosis factor (TNF)-alpha as well as of matrix metalloproteinases (MMPs) in washed-out synovial fluid (SF) samples obtained from those patients. A total of 26 patients with unilateral high condylar fractures who underwent arthrocentesis for a therapeutic purpose were examined. SF samples were collected before performing arthroscopy to determine synovitis grade. The detection rates and concentrations of TNF-alpha and MMPs were determined, and their association with synovitis grade was analysed. TNF-alpha was detected in 23 and MMP-3 in 22 of the TMJs. There was a correlation between synovitis grade and concentration of TNF-alpha in the fracture group. Furthermore, the concentrations of TNF-alpha and MMP-3 were significantly higher as compared to the control group, comprised of TMJs on the non-fracture side of the same patients, while a correlation was also noted between TNF-alpha concentration and synovitis grade in the fracture group. The present findings may provide a biological/biochemical rationale for arthrocentesis as a reasonable treatment modality for high condylar fractures.

Effects of Compressive Loading on Human Synovium-derived Cells

Compressive stress may be involved in temporomandibular joint (TMJ) synovitis, but its mechanism has not been fully elucidated. We hypothesized that mechanical stress to the synovial cells of the TMJ potentially causes degenerative changes in temporomandibular joint disease. We examined the effect of cyclic compressive loading on three-dimensionally engineered constructs using human TMJ synovium-derived cells in vitro. Human TMJ synovium-derived cells were cultured onto collagen scaffolds, resulting in three-dimensional constructs. Cyclic compression loading was applied to the constructs by means of a custom-designed apparatus. DNA amount, apoptotic cells, and mRNA levels for inflammatory cytokines were analyzed. The protein expression and activity of MMPs were examined. DNA amount or apoptotic cell number was unchanged by loading. MMP-2, -3, and IL-8 mRNA expression was up-regulated by the compression, and both MMP-1 and -3 protein expression and MMP-2 activity were detected. Thus, compression of human TMJ synovium-derived cells appears to modulate inflammatory cytokines.

Replacing Shox2 with human SHOX leads to congenital disc degeneration of the temporomandibular joint in mice

The temporomandibular joint (TMJ) consists in the glenoid fossa arising from the otic capsule through intramembranous ossification, the fibrocartilaginous disc and the condyle, which is derived from the secondary cartilage by endochondral ossification. We have reported previously that cranial neural-crest-specific inactivation of the homeobox gene Shox2, which is expressed in the mesenchymal cells of the maxilla-mandibular junction and later in the progenitor cells and perichondrium of the developing chondyle, leads to dysplasia and ankylosis of the TMJ and that replacement of the mouse Shox2 with the human SHOX gene rescues the dysplastic and ankylosis phenotypes but results in a prematurely worn out articular disc. In this study, we investigate the molecular and cellular bases for the prematurely worn out articular disc in the TMJ of mice carrying the human SHOX replacement allele in the Shox2 locus (termed Shox2 (SHOX-KI/KI)). We find that the developmental process and expression of several key genes in the TMJ of Shox2 (SHOX-KI/KI) mice are similar to that of controls. However, the disc of the Shox2 (SHOX-KI/KI) TMJ exhibits a reduced level of Collagen I and Aggrecan, accompanied by increased activities of matrix metalloproteinases and a down-regulation of Ihh expression. Dramatically increased cell apoptosis in the disc was also observed. These combinatory cellular and molecular defects appear to contribute to the observed disc phenotype, suggesting that, although human SHOX can exert similar functions to mouse Shox2 in regulating early TMJ development, it apparently has a distinct function in the regulation of those molecules that are involved in tissue homeostasis.

Timing interventions in relation to temporomandibular joint closed lock duration: a systematic review of 'locking duration'

Temporomandibular joint (TMJ) 'closed lock' (CL) is a clinical condition causing TMJ pain and limited mouth opening (painful locking) that is mostly attributed to disc displacement without reduction (DDwoR), or less commonly to anchored disc phenomenon (ADP). Both conditions are described clinically as CL that can be 'acute' or 'chronic' depending on the duration of locking. There is, however, no consensus about the duration of locking that defines the acute state and its effect on the success of interventions. This review paper, therefore, aims to provide: (i) a narrative review of the pathophysiological need for early intervention in DDwoR and the clinical implications of acute/chronic CL stages on the management pathway; (ii) a systematic review investigating the effects of locking duration on the success of interventions for CL management. Electronic and manual searches until mid-August 2013 were conducted for English-language studies of any design investigating the effects of non-surgical and surgical interventions for acute or chronic CL (DDwoR or ADP). A total of 626 records were identified, and 113 studies were included. Data extraction and quality assessment were completed for all included studies. Included studies were, however, heterogeneous and mostly of poor-quality leading to contradictory and inconsistent evidence on the effect of the duration of locking on treatment outcomes. Future high-quality trials investigating the effect of CL duration on treatment outcome are needed. At present, early intervention by 'unlock' mandibular manipulation seems to be the most practical and realistic approach that can be attempted first in every CL patient as an initial diagnostic/therapeutic approach.

Assessment of temporomandibular joint disease

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

Pathogenesis of degenerative temporomandibular joint arthritides

Over the past decade, remarkable progress has been made in the study of molecular mechanisms involved in degenerative temporomandibular joint arthritides. Based on recent findings, models of degenerative temporomandibular joint disease predict that mechanical loads trigger a cascade of molecular events leading to disease in susceptible individuals. These events involve the production or release of free radicals, cytokines, fatty acid catabolites, neuropeptides, and matrix-degrading enzymes. Under normal circumstances, these molecules may be involved in the remodeling of articular tissues in response to changing functional demands. However, if functional demands exceed the adaptive capacity of the temporomandibular joint or if the affected individual is susceptible to maladaptive responses, then a disease state will ensue. An individual's susceptibility to degenerative temporomandibular joint disease may be determined by several factors, including genetic backdrop, sex, age, and nutritional status. It is hoped that, by furthering our understanding of the molecular events that underlie degenerative temporomandibular joint diseases, improved diagnostics and effective therapies for these debilitating conditions will be developed.

ADAMs are present in fungi: identification of two novel ADAM genes in Aspergillus fumigatus

The ADAMs are a family of integral membrane proteases involved in shedding and fusion events in animal tissues. Here, we report the identification of two ADAMs, ADM-A and ADM-B, in the pathogenic fungus Aspergillus fumigatus. The domain structure of metazoan ADAMs was seen in ADM-A and -B, although with some differences. ADAMs were identified in other filamentous fungi and phylogenetic analysis indicated that the fungal ADAMs were monophyletic and most closely related to metazoan ADAM 10 and 17. Recombinant ADM-B protease specifically cleaved casein and albumin while recombinant propeptide+protease was inactive. A sheddase function is therefore proposed for fungal ADAMs.

Effects of a single arthrocentesis and a COX-2 inhibitor on disorders of temporomandibular joints

Our aim was to examine the short-term effect of combined treatment with single arthrocentesis and a COX-2 inhibitor on 26 patients with severe symptoms of temporomandibular joint (TMJ) disorders. The severity of the disorders was graded according to the degree of restriction of mouth opening and pain score on a visual analogue scale. Synovial fluid was collected from the superior joint space of the affected TMJ, and arthrocentesis was done with isotonic saline, 200ml. Subsequently, etodolac, 400mg/day, was given for 2 weeks. At 14 days, patients were re-examined and further specimens of synovial fluid were collected. Patients generally lost their symptoms and the severity of the disorders improved significantly (P<0.01). The concentrations of total protein and albumin in synovial fluid decreased with no statistical significance. However, the concentration of matrix metalloproteinase-3 and its ratios to total protein and albumin did decrease significantly (P<0.05). Our results suggest that a larger controlled study is necessary to clarify the contributory effect of arthrocentesis and etodolac for patients with severe symptoms of TMJ disorders.

Synovial matrix metalloproteinase-2 in different stages of sheep temporomandibular joint osteoarthrosis

PURPOSE

The purpose of this study was to test for the presence of matrix metalloproteinase (MMP) in synovial fluid of sheep with experimentally induced temporomandibular joint (TMJ) osteoarthrosis (OA) at various time intervals.

MATERIALS AND METHODS

Twenty-one sheep were used in this study. TMJ OA was induced bilaterally in 18 sheep and 3 sheep were used as controls. Each experimental group had 3 sheep, and the groups were killed at 2, 4, 6, 8, 12, and 24 weeks postoperatively. Synovial fluid was collected at killing, and the joints were evaluated histologically. Gelatin zymography was performed to detect the presence of MMPs in the synovial fluid.

RESULTS

TMJ OA gradually progressed over time. ProMMP-2 was detected in all experimental groups. However, the activated form of MMP-2 was only detected at 2 and 4 weeks postoperatively.

CONCLUSION

Activated MMP-2 activity correlates with initial articular cartilage destruction rather than with the progression of OA in the sheep TMJ.

Matrix metalloproteinase-2 in synovial lavage fluid of patients with disorders of the temporomandibular joint

We examined the matrix metalloproteinase-2 (MMP-2) activity in synovial lavage fluid of patients with disorders of the temporomandibular joint (TMJ) and explored the possible correlationship between MMP-2 activity and radiological changes. We studied 86 patients and 10 healthy volunteers. An arthrogram and a double contrast arthrotomogram were taken to evaluate intra-articular morphological changes. The patients were divided into three groups: no abnormality (n = 36), internal derangement (n = 39), and osteoarthritis (n = 11). Samples of synovial fluid were studied by gelatin zymography, and we sought a correlation between the band detected and radiological findings. ProMMP-2 was detected in all samples and active MMP-2 was detected in 9/36 with no abnormality, 14/39 with internal derangement and 5/11 with osteoarthritis. No active form of MMP-2 was detected in the control group. The incidence of active MMP-2 was high in the internal derangement group and highest in the osteoarthritis group, which suggests that active MMP-2 plays an important part in the development of conditions of the TMJ.

Activities of plasminogen activator, plasmin and kallikrein in synovial fluid from patients with temporomandibular joint disorders

To measure the activities of plasminogen activator (PA), plasmin and kallikrein, multiple synovial fluid samples were taken from 32 patients with internal derangement (ID) and osteoarthrosis (OA), and nine asymptomatic volunteers. The enzyme activity in synovial fluid from the temporomandibular joint (TMJ) was quantitated by a fluorogenic substrate assay using an enzyme substrate. In fluid samples from the patient group, PA was detected in 24 (31.5%), plasmin in 20 (26.3%) and kallikrein in 53 (96.4%), while none of these enzymes were found in the synovial fluid samples from the control group. There were positive correlations found among PA, plasmin and kallikrein. These results clearly demonstrated increased levels of PA, plasmin and kallikrein activities in the synovial fluid of patients with ID and OA, and suggest that these enzymes may be involved in the pathogenesis of synovitis, as well as the resorption of cartilage and bone in TMJ.

Matrix metalloproteinases in mild and severe temporomandibular joint internal derangement synovial fluid

OBJECTIVES

The first objective of this study was to verify the presence of and identify the molecular forms of matrix metalloproteinases (MMPs), including collagenases (MMP-1, MMP-8, and MMP-13) and gelatinases (MMP-2 and MMP-9), in the synovial fluid (SF) of mild and severe temporomandibular joint internal derangement (TMJ-ID). Another objective was to evaluate whether the SF MMPs are potential diagnostic markers that reflect the stage of intra-articular inflammation in the TMJ.

STUDY DESIGN

The subjects were 44 patients with mild (n = 16) or severe (n = 28) TMJ-ID; they were classified on the basis of subjective symptoms, clinical and radiographic findings, and surgical observations. The patients were surgically treated, and SF samples were collected immediately before the operation. The collagenase activity of SF samples was analyzed by means of a type I collagen degradation assay. The levels and molecular forms of the SF MMPs as well as the tissue inhibitors of MMPs (TIMP-1 and TIMP-2) were analyzed with Western immunoblotting and gelatin zymography.

RESULTS

The SF of both the mild and the severe TMJ-ID patients exhibited free collagenase activity and activity capable of further degrading the (3/4)(alphaA) fragments. Ninety-two-kilodalton proMMP-9 and its 121-kD complex form, as well as 72-kD proMMP-2 were significantly increased in the mild TMJ-ID group (P <.05 in all cases). Both 70- to 80-kD neutrophil type and 45- to 55-kD mesenchymal cell-type MMP-8 (corresponding to the latent and active forms) were observed in mild and severe TMJ-ID SF, but they predominated in mild TMJ-ID. Both MMP-1 and MMP-13 were observed in both groups, and in mild TMJ-ID SF the low-molecular weight forms of MMP-1 indicated activation of the enzyme.

CONCLUSIONS

The degradation of type I collagen in the TMJ is evidently due to the collective action of many collagenolytic MMPs present in the SF of patients with mild and severe TMJ-ID. The elevated levels of MMP-2, MMP-9, and MMP-8 in the SF of patients with mild TMJ-ID eventually reflect the active phase of TMJ destruction. These observations may have considerable diagnostic and therapeutic significance in the management of TMJ disorders.

Role of interleukin-1 in induction of matrix metalloproteinases synthesized by rat temporomandibular joint chondrocytes and disc cells

To identify cartilage-degrading enzymes and cell types that can be specifically induced by interleukin-1 (IL-1)alpha, we studied matrix metalloproteinase (MMP) activities of cultured rat temporomandibular joint (TMJ) chondrocytes and disc cells. The cells were isolated from TMJs pre-injected with normal physiological saline (CR) or recombinant human IL-1alpha (AR). MMP activities in the conditioned media were assayed by gelatin enzymography, and they were identified by Western blot analyses. MMP mRNAs in these cells were also detected by RT-PCR. IL-1alpha significantly induced an increase of active MMP9 as well as pro- and active MMP3, but had no effect on the MMP2 activity in both types of cells. MMP3 and MMP9 mRNAs were also inducible in these cells by IL-1alpha stimulation. Furthermore, disc cells were more susceptible to IL-1alpha than chondrocytes. AR cells spontaneously produced the same MMPs in vitro as the CR cells synthesized under IL-1alpha stimulation. The results indicate that MMP9 and MMP3 were predominantly produced by disc cells, and these may be considered to play a pivotal role in ECM degradation during pathological conditions of the TMJ, such as IL-1-induced TMJ arthritis.

Medical hypnosis for temporomandibular disorders: treatment efficacy and medical utilization outcome

AIM

The aim of this study was to examine the effectiveness of a particular behavioral medicine treatment modality, medical hypnosis, on reducing the pain symptoms of temporomandibular disorders (TMD).

METHODS

Twenty-eight patients who were recalcitrant to conservative treatment for TMD participated in a medical hypnosis treatment program and completed measures of their pain symptoms on 4 separate occasions: during wait list, before treatment, after treatment, and at a 6-month follow-up. In addition, pretreatment and posttreatment medical use were examined.

RESULTS

Statistical analysis of this open trial suggests that medical hypnosis is a potentially valuable treatment modality for TMD. Patients reported a significant decrease in pain frequency (F [3, 87] = 14.79, P<.001), pain duration (F [3, 87] = 9.56, P<.001), and pain intensity (F [3, 87] = 15.08, P<. 001), and an increase in daily functioning. Analysis suggests that their symptoms did not simply spontaneously improve, and that their treatment gains were maintained for 6 months after hypnosis treatment. Further, after hypnosis treatment, patients exhibited a significant reduction in medical use.

CONCLUSION

Medical hypnosis appears to be an effective treatment modality for TMD, in terms of reducing both symptoms and medical use.

Alteration in expression of MMP-1 and MMP-2 but not TIMP-1 and TIMP-2 in hereditary gingival fibromatosis is mediated by TGF-beta 1 autocrine stimulation

Hereditary gingival fibromatosis (HGF) is characterized by an excess accumulation of extracellular matrix (ECM) resulting in a generalized and fibrotic enlargement of the gingiva. To investigate some of the regulatory features of this condition, gingival fibroblasts from normal gingiva (NG) and HGF were examined for the expression and production of matrix metalloproteinases (MMPs) and their inhibitors, tissue matrix metalloproteinases inhibitor (TIMPs). Our results, obtained from 2 different assays, semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and enzymography, clearly demonstrated that the expression and production of MMP-1 and MMP-2 was significantly lower in fibroblasts from HGF than from NG. Interestingly, TIMP-1 and TIMP-2 expression from NG cells was shown to be slightly higher to those from HGF. Addition of antibodies against transforming growth factor-beta 1 (TGF-beta 1), which is produced in greater amounts by HGF fibroblasts, resulted in a slight increase in MMP-1 and a decrease in MMP-2 expression, whereas TIMP-1 and TIMP-2 expressions were unaffected. These patterns of expression and production suggest that enhanced TGF-beta 1 production reduce the proteolytic activities of HGF fibroblasts, which favor the accumulation of ECM.