Proteomic signature of Temporomandibular Joint Disorders (TMD): Toward diagnostically predictive biomarkers

The temporomandibular joint (TMJ) articulates the mandible with the maxilla. Temporomandibular joint disorders (TMD) are dysfunctions of this joint, which range from acute to chronic inflammation, trauma and dislocations, developmental anomalies and neoplasia. TMD manifest as signs and symptoms that involve the surrounding muscles, ligaments, bones, synovial capsule, connective tissue, teeth and innervations proximal and distal to this joint. TMD induce proximal and distal, chronic and acute, dull or intense pain and discomfort, muscle spasm, clicking/popping sounds upon opening and closing of the mouth, and chewing or speaking difficulties. The trigeminal cranial nerve V, and its branches provide the primary sensory innervation to the TMJ. Our clinical work suggests that the auriculotemporal (AT) nerve, a branch of the mandibular nerve, the largest of the three divisions of the trigeminal nerve, plays a critical role in TMD sequelae. The AT nerve provides the somatosensory fibers that supply the joint, the middle ear, and the temporal region. By projecting fibers toward the otic ganglion, the AT nerve establishes an important bridge to the sympathetic system. As it courses posteriorly to the condylar head of the TMJ, compression, injury or irritation of the AT nerve can lead to significant neurologic and neuro-muscular disorders, including Tourette's syndrome,Torticolli, gait or balance disorders and Parkinson's disease. Here, we propose that a proteomic signature of TMD can be obtained by assessing certain biomarkers in local (e.g., synovial fluid at the joint) and distal body fluids (e.g., saliva, cerebrospinal fluid), which can aid TMD diagnosis and prognosis.     

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

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

Phenotypic alterations of neuropeptide Y and calcitonin gene-related peptide-containing neurons innervating the rat temporomandibular joint during carrageenan-induced arthritis

The aim of this study was to identify immunoreactive neuropeptide Y (NPY) and calcitonin gene-related peptide (CGRP) neurons in the autonomic and sensory ganglia, specifically neurons that innervate the rat temporomandibular joint (TMJ). A possible variation between the percentages of these neurons in acute and chronic phases of carrageenan-induced arthritis was examined. Retrograde neuronal tracing was combined with indirect immunofluorescence to identify NPY-immunoreactive (NPY-IR) and CGRP- immunoreactive (CGRP-IR) neurons that send nerve fibers to the normal and arthritic temporomandibular joint. In normal joints, NPY-IR neurons constitute 78±3%, 77±6% and 10±4% of double-labeled nucleated neuronal profile originated from the superior cervical, stellate and otic ganglia, respectively. These percentages in the sympathetic ganglia were significantly decreased in acute (58±2% for superior cervical ganglion and 58±8% for stellate ganglion) and chronic (60±2% for superior cervical ganglion and 59±15% for stellate ganglion) phases of arthritis, while in the otic ganglion these percentages were significantly increased to 19±5% and 13±3%, respectively. In the trigeminal ganglion, CGRP-IR neurons innervating the joint significantly increased from 31±3% in normal animals to 54±2% and 49±3% in the acute and chronic phases of arthritis, respectively. It can be concluded that NPY neurons that send nerve fibers to the rat temporomandibular joint are located mainly in the superior cervical, stellate and otic ganglia. Acute and chronic phases of carrageenan-induced arthritis lead to an increase in the percentage of NPY-IR parasympathetic and CGRP-IR sensory neurons and to a decrease in the percentage of NPY-IR sympathetic neurons related to TMJ innervation.Key words: trigeminal ganglion, otic ganglion, superior cervical ganglion, arthritis, temporomandibular joint.     

Localization and Central Projections of Primary Afferent Neurons That Innervate the Temporomandibular Joint in Cats

Primary afferent neurons that innervate the temporomandibular joint (TMJ) in cats were labeled by injecting a 2-5% solution of wheatgerm agglutinin bound to horseradish peroxidase into the joint capsule and capsular tissues in 14 cats and processing the brain stem and trigeminal ganglia using the tetramethylbenzidine method described by Mesulam (1978). The perikarya of ganglion cells that innervate the TMJ ranged in diameter from 15 to 109 μm and were primarily located in the posterolateral portion of the trigeminal ganglion. The central processes of these neurons entered the brain stem in middle pons and were distributed to all portions of the sensory trigeminal nuclei. However, the majority of labeled fibers and greatest density of terminal labeling were observed in the dorsal part of the main sensory nucleus and the subnucleus oralis of the spinal trigeminal nucleus. Very few labeled fibers were observed in the spinal tract of the trigeminal nerve below the obex. However, evidence for axon terminals was consistently observed in laminae I, II, and III of the medullary dorsal horn. These findings concur with physiological evidence showing that information from the TMJ influences neurons in rostral (Kawamura et al, 1967) and in caudal (Broton et al, 1985) portions of the trigeminal sensory nuclei.     

Serotonergic mechanisms influence the response to glucocorticoid treatment in TMJ arthritis

The aims of this study were to investigate the influence of serotonin (5-HT) on the effects of intra-articular injections of glucocorticoid on pain of the temporomandibular joint (TMJ) in patients with inflammatory disorders of the TMJ. The pretreatment synovial fluid 5-HT was negatively, and plasma 5-HT positively, correlated to change in TMJ pain after treatment. The pretreatment plasma 5-HT was positively correlated to change in pressure-pain threshold after treatment. In conclusion, this study shows that local and systemic serotonergic mechanisms partly determine the effect of intra-articular glucocorticoid treatment on TMJ pain in patients with chronic TMJ arthritis of systemic nature, while change in pressure-pain threshold over the TMJ is influenced by systemic serotonergic mechanisms.     

Oral health status and temporomandibular disorders in multiple sclerosis patients

Multiple sclerosis (MS) is an inflammatory disease of unknown etiology involving the central nervous system. Certain clinical manifestations affect the oro-facial region. Three in particular should be of interest to the dentist: trigeminal neuralgia, sensory neuropathy of the trigeminal nerve and facial palsy. The aim of this study was to determine the oral health status, the frequency of subjective symptoms and temporomandibular disorders (TMD) subtype according to Research diagnostic criteria for temporomandibular disorders (RDC/TMD) among MS patients. Examinees in this study were 50 patients suffering from MS, who were at least once treated during their disease in the Clinic Hospital Center, Rijeka, Clinic for Neurology. All examinees had to meet the diagnostic criteria for clinically and laboratory confirmed MS, according to Poser. The results show the difference in mean DMFT (decayed, missing, filled teeth) between MS and the control group. The number of decayed and missing teeth was higher, but the number of filled teeth was significantly lower in MS group. Eighty-two per cent of the subjects with MS had a least one symptom of dysfunction compared with 24% of the subjects in the healthy control group. In the present study, pain, the pain during mouth opening, the difficulty with mouth opening and temporomandibular joint (TMJ) sounds were more commonly reported in the MS group than in the control group. This study shows a statistically significant excess of dental caries and temporomandibular disorders among MS patients compared with the control group. These results suggest that MS is a possible etiological factor in temporomandibular disorders.     

Synovium Fragment-Derived Cells Exhibit Characteristics Similar to Those of Dissociated Multipotent Cells in Synovial Fluid of the Temporomandibular Joint

Multipotent mesenchymal stem cells (MSCs) found in the synovial fluid (SFMSCs) of the tempromandibular joint (TMJ) remain poorly understood. During TMJ arthrocentesis, we discovered that synovial fluid collected from some patients with TMJ disorders contained not only SFMSCs but also synovium fragments (SFs). In this study, we attempted to characterize both the SFMSCs and SF-derived cells (SFCs) in order to further understand the role of MSCs in the synovial fluid of the TMJ. The SFs were membranous and translucent and consisted of several cell layers, indicating that their origin was only from the intima. SFCs were obtained by digestion of the SFs and subsequently expanded in vitro. SFMSCs were enriched by centrifugation of the synovial fluid and expanded in vitro. SFCs and SFMSCs displayed a similar fibroblast-like, spindle-shaped morphology, and we observed that some SFMSCs grew out of small tissue masses in culture. Flow cytometric analysis showed that both groups of cells expressed similar surface markers, including CD90, CD44, CD105, and CD73. However, both were negative for Stro-1, CD146, CD45, CD34, CD11b, CD19, and HLA-DR. Immunofluorescent staining showed that both SFs and SFMSCs expressed vascular cell adhesion molecule 1. Both SFCs and SFMSCs could be induced to differentiate down osteogenic, chondrogenic, adipogenic, and neurogenic lineages in vitro. Together, our results indicate that the intima is the most likely tissue origin of SFMSCs in the TMJ. Moreover, the SFs are composed of only intima and thus offer an improved source of synovium-derived MSCs compared to synovium specimens obtained by surgery, which contain both intima and subintima.     

Lubricin Protects the Temporomandibular Joint Surfaces from Degeneration

The temporomandibular joint (TMJ) is a specialized synovial joint essential for the mobility and function of the mammalian jaw. The TMJ is composed of the mandibular condyle, the glenoid fossa of the temporal bone, and a fibrocartilagenous disc interposed between these bones. A fibrous capsule, lined on the luminal surface by the synovial membrane, links these bones and retains synovial fluid within the cavity. The major component of synovial fluid is lubricin, a glycoprotein encoded by the gene proteoglycan 4 (Prg4), which is synthesized by chondrocytes at the surface of the articular cartilage and by synovial lining cells. We previously showed that in the knee joint, Prg4 is crucial for maintenance of cartilage surfaces and for regulating proliferation of the intimal cells in the synovium. Consequently, the objective of this study was to determine the role of lubricin in the maintenance of the TMJ. We found that mice lacking lubricin have a normal TMJ at birth, but develop degeneration resembling TMJ osteoarthritis by 2 months, increasing in severity over time. Disease progression in Prg4 ^−/− mice results in synovial hyperplasia, deterioration of cartilage in the condyle, disc and fossa with an increase in chondrocyte number and their redistribution in clusters with loss of superficial zone chondrocytes. All articular surfaces of the joint had a prominent layer of protein deposition. Compared to the knee joint, the osteoarthritis-like phenotype was more severe and manifested earlier in the TMJ. Taken together, the lack of lubricin in the TMJ causes osteoarthritis-like degeneration that affects the articular cartilage as well as the integrity of multiple joint tissues. Our results provide the first molecular evidence of the role of lubricin in the TMJ and suggest that Prg4 ^−/− mice might provide a valuable new animal model for the study of the early events of TMJ osteoarthritis.     

Capsaicin receptor expression in the rat temporomandibular joint

Experimentally, temporomandibular joint (TMJ) nerve units respond to capsaicin, which is used clinically to treat TMJ pain. However, the existence of capsaicin receptors in the TMJ has not previously been clearly demonstrated. Immunohistochemical analysis has revealed the presence of transient receptor potential vanilloid subtype 1 (TRPV1) expression in the nerves and synovial lining cells of the TMJ. TRPV1-immunoreactive nerves are distributed in the synovial membrane of the joint capsule and provide branches to the joint compartment. The disc periphery is supplied by TRPV1 nerves that are mostly associated with small arterioles, and occasional nerves penetrate to the synovial lining layer. Double immunofluorescence has shown that many TRPV1-immunoreactive nerves are labeled with neuropeptide calcitonin gene-related peptide, whereas few are labeled with IB4-lectin. The results provide evidence for the presence of TRPV1 in both nerves and synovial lining cells, which might thus be involved in the mechanism of nociception and inflammation in the TMJ. This study was supported by a grant-in-aid for Scientific Research (C), no. 15591938, from the Japanese Ministry of Education, Science, Sports, Culture, and Technology (to M.A.K.).     

The relation of nerves to multiple regeneration in a single newt limb.

Three amputation surfaces were formed on the lower arm of a single newt. Growth occurred on all combinations of these surfaces. The proximal surface (the only single surface to form regenerates) produced more regenerates (76% of the cases) than the two more distal surfaces. Blocking the proximal surface with whole skin greatly stimulates the production of accessory structures on the first and/or second more distal surfaces. The mean number of nerve fibers on the proximal surface is considerably higher than the nerve counts of the first more and second most distal surfaces. Limbs possessing a notch or digit(s) on the proximal surface and the absence of growth on the first more and second distal surfaces also show a decrease in nerve number on the first more and second most distal surfaces. An analysis of the mean number of nerve fibers on the blocked (proximal) surface shows a noticeable decrease in comparison with nerve fibers in an equivalent level on normal limbs. Nerve fiber counts on the first more and second most distal surfaces are markedly increased on those limbs where the proximal surface was blocked with whole skin. Threshold experiments suggest that the irregular occurrence of accessory structures on the first more distal and second most distal surfaces may be related to an insufficient number of nerve fibers on these surfaces. Similarly, a possible explanation for the regular occurrence of accessory structures on the proximal surface is that nerve number on this surface is always above threshold.     

A simple in vitro method to study the trigeminal ganglion

This report describes a simple in vitro method to harvest and study the electrophysiological properties of the trigeminal ganglion of the rat. In suction electrode recordings from the proximal nerve end, two distinct peaks are identified in the compound action potential evoked by electrical stimulation of the distal nerve. gamma-Aminobutyric acid (GABA), added to the perfusion fluid, caused a positive shift in the DC potential (depolarization) and a partially selective decrease in the amplitude of the slow-conduction peak. Reversible antagonism of the GABA effect by picrotoxin and bicuculline suggests that both responses are receptor mediated. There was no response to carbamazepine or L-baclofen, suggesting that ganglionic polarization does not play a major role in the action of these drugs in trigeminal neuralgia.     

Increased risk of temporomandibular joint closed lock: a case-control study of ANKH polymorphisms

Objectives

This study aimed to carry out a histological examination of the temporomandibular joint (TMJ) in ank mutant mice and to identify polymorphisms of the human ANKH gene in order to establish the relationship between the type of temporomandibular disorders (TMD) and ANKH polymorphisms.

Materials and Methods

Specimens from the TMJ of ank mutant and wild-type mice were inspected with a haematoxylin and eosin staining method. A sample of 55 TMD patients were selected. Each was examined with standard clinical procedures and genotyping techniques.

Results

The major histological finding in ank mutant mice was joint space narrowing. Within TMD patients, closed lock was more prevalent among ANKH-OR homozygotes (p = 0.011, OR = 7.7, 95% CI 1.6–36.5) and the elder (p = 0.005, OR = 2.4, 95% CI 1.3–4.3).

Conclusions

Fibrous ankylosis was identified in the TMJ of ank mutant mice. In the human sample, ANKH-OR polymorphism was found to be a genetic marker associated with TMJ closed lock. Future investigations correlating genetic polymorphism to TMD are indicated.     

Brain Signature of Chronic Orofacial Pain: A Systematic Review and Meta-Analysis on Neuroimaging Research of Trigeminal Neuropathic Pain and Temporomandibular Joint Disorders

Brain neuroimaging has been widely used to investigate the bran signature of chronic orofacial pain, including trigeminal neuropathic pain (TNP) and pain related to temporomandibular joint disorders (TMD). We here systematically reviewed the neuroimaging literature regarding the functional and structural changes in the brain of TNP and TMD pain patients, using a computerized search of journal articles via PubMed. Ten TNP studies and 14 TMD studies were reviewed. Study quality and risk of bias were assessed based on the criteria of patient selection, the history of medication, the use of standardized pain/psychological assessments, and the model and statistics of imaging analyses. Qualitative meta-analysis was performed by examining the brain regions which showed significant changes in either brain functions (including the blood-oxygen-level dependent signal, cerebral blood flow and the magnetic resonance spectroscopy signal) or brain structure (including gray matter and white matter anatomy). We hypothesized that the neuroimaging findings would display a common pattern as well as distinct patterns of brain signature in the disorders. This major hypothesis was supported by the following findings: (1) TNP and TMD patients showed consistent functional/structural changes in the thalamus and the primary somatosensory cortex, indicating the thalamocortical pathway as the major site of plasticity. (2) The TNP patients showed more alterations at the thalamocortical pathway, and the two disorders showed distinct patterns of thalamic and insular connectivity. Additionally, functional and structural changes were frequently reported in the prefrontal cortex and the basal ganglia, suggesting the role of cognitive modulation and reward processing in chronic orofacial pain. The findings highlight the potential for brain neuroimaging as an investigating tool for understanding chronic orofacial pain.     

两种分形维数在颞下颌关节音分析中的应用

颞下颌关节（TMJ）是人体最复杂的关节之一,有着复杂的生理功能,颞下颌关节音（颚开合时TMJ产生的声音）含有丰富的有关TMJ状态的信息。利用非线性动力学的混沌与分形理论对健康人和颞下颌关节内紊乱（TMD）患者的TMJ音信号进行了分析。分别计算其波形维和相关维。结果表明,健康人TMJ音信号的两种分形维数值都明显高于TMD患者。提示,以TMJ音信号的分形维数值作为TMJ损伤及病变的一个指标是有意义的。     

Adrenergic signalling in osteoarthritis

Adrenoceptors (ARs) mediate the effects of the sympathetic neurotransmitters norepinephrine (NE) and epinephrine (E) in the human body and play a central role in physiologic and pathologic processes. Therefore, ARs have long been recognized as targets for therapeutic agents, especially in the field of cardiovascular medicine. During the past decades, the contribution of the sympathetic nervous system (SNS) and particularly of its major peripheral catecholamine NE to the pathogenesis of osteoarthritis (OA) attracted growing interest. OA is the most common degenerative joint disorder worldwide and a disease of the whole joint. It is characterized by progressive degradation of articular cartilage, synovial inflammation, osteophyte formation, and subchondral bone sclerosis mostly resulting in chronic pain. The subchondral bone marrow, the periosteum, the synovium, the vascular meniscus and numerous tendons and ligaments are innervated by tyrosine hydroxylase-positive (TH+) sympathetic nerve fibers that release NE into the synovial fluid and cells of all abovementioned joint tissues express at least one out of nine AR subtypes. During the past decades, several in vitro studies explored the AR-mediated effects of NE on different cell types in the joint. So far, only a few studies used animal OA models to investigate the contribution of distinct AR subtypes to OA pathogenesis in vivo. This narrative review shortly summarizes the current background knowledge about ARs and their signalling pathways at first. In the second part, we focus on recent findings in the field of NE-induced AR-mediated signalling in different joint tissues during OA pathogenesis and at the end, we will delineate the potential of targeting the adrenergic signalling for OA prevention or treatment. We used the PubMed bibliographic database to search for keywords such as ‘joint’ or ‘cartilage’ or ‘synovium’ or ‘bone’ and ‘osteoarthritis’ and/or ‘trauma’ and ‘sympathetic nerve fibers’ and/or ‘norepinephrine’ and ‘adrenergic receptors / adrenoceptors’ as well as ‘adrenergic therapy’.     

Influence of depression and somatization on acute and chronic orofacial pain in patients with single or multiple TMD diagnoses

To examine whether psychological variables such as depression and non-specific physical symptoms (somatization) influence pain entity among acute and chronic TMD patients with one or more TMD diagnoses (muscle disorders, MD; disc displacements, DD; and arthralgia, arthritis, arthrosis, AAA). One hundred and fifty-four patients (37 male and 117 female; mean age, 39.0 +/- 14.5 years) with Research Diagnostic Criteria for Temporomandibular Disorders (RDC/ TMD) protocol were selected. Differences in mean depression and somatization scores between acute and chronic TMD patients, as well as TMD patients with one or multiple TMD diagnoses were compared by using the parametric T-test for independent samples. The majority of patients were acute TMD patients (81.8%), while the remaining 28 patients (18.2%) were chronic TMD patients. 62% of patients had only one TMD diagnosis (MD or DD or AAA), 31% of patients had two diagnoses (MD+DD, MD+AAA, DD+AAA) and, finally, 7% of patients had three diagnoses (MD+DD+AAA) according to the RDC/TMD protocol. According to the SCL-90 psychometric evaluation, 19.5% of patients presented a severe depression score (> 1.105), 27.3% of participants presented a severe somatization score with pain items included (> 1.000). The results of the t-test for independent samples showed statistically significant differences between acute and chronic TMD patients (p < 0.001), as well as between patients who were assigned one diagnosis (p = 0.019) and patients who had two or more diagnoses (p < 0.001); for mean levels of depression and somatization scores. Chronic TMD patients and patients with multiple TMD diagnoses had higher rates of depression and somatization in this study. These results could be used in a tailored strategy of TMD treatment.     

Increased density of fluorescent adrenergic fibers around the middle cerebral arteries of stroke-prone spontaneously hypertensive rats

The distribution of fluorescent adrenergic nerve fibers in the proximal portion (horizontal segment, Hs) and the three distal portions (major branches) of the middle cerebral arteries (MCA) was examined in stroke-prone spontaneously hypertensive rats (SHRSP) aged 10, 30, 60, 90, and 180 days, by the glyoxylic acid method. The results were compared with those in agematched normotensive Wistar Kyoto (WKY) rats. While the distribution pattern of fluorescent nerve fibers in the proximal portion of WKY rats changed from a straight linear arrangement at 10 and 30 days of age to a network-like arrangement after 60 days, those from SHRSP showed a constant meshwork pattern throughout the entire examination period. In the distal portions of the MCA of both SHRSP and WKY rats at all ages examined, fluorescent nerve fibers formed a coarse network. The distribution densities of adrenergic nerve fibers in the proximal and distal portions of the MCA of SHRSP were significantly higher (P<0.01 and 0.05) than those of WKY rats at all ages examined, except in the proximal portion at 90 and 180 days of age. The difference in nerve fiber density between SHRSP and WKY rats reached a peak at 30 days of age in both proximal and distal portions, and then gradually decreased with age. The present study suggests that sympathetic hyperinnervation is an important factor in the development of hypertension, and is involved in its maintenance in SHRSP.     

Nerve fiber planimetry in acute and chronic nerve lesions and in nerve lesions in continuity

The level of resection of damaged nerve tissue in acute and chronic nerve lesions was determined on the basis of the vascular structure, the consistency of the nerve during palpation, the amount of interfascicular connective tissue, and the mushroom formation of the fascicles. Intraoperative electrophysiologic recordings were performed on the cut nerve ends to determine the function of the axons. Postoperative planimetric analyses of cross sections made through the resected nerve stumps were performed to measure axonal and endoneural tube diameters and to correlate these results with the clinical criteria used through the operating microscope. Axons in the proximal nerve ends of acute and chronic nerve lesions displayed a similar mean diameter. Endoneural tubes in chronic nerve lesions shrunk significantly as nerve repair was delayed. In several nerve lesions in continuity, axons remained present across the injured site despite absence of electrical conduction. When comparing the results of axonal or endoneural tube diameters of chronic nerve lesions to the results of other studies or acute nerve lesions, we demonstrated that careful examination through the operating microscope provided valid information about the proper management and resection level of chronic nerve lesions. Electrophysiologic evaluation aided the surgical management but was not useful for the resection of the distal damaged nerve segment. The presence of an evoked potential in the proximal nerve ends guaranteed a nearly normal nerve fiber diameter distribution, while the absence of such a potential in the distal nerve ends indicated an abnormal, absent, or disturbed endoneural tube diameter histogram.     

The specific expression of tenascin in the synovial membrane of the temporomandibular joint with internal derangement: An immunohistochemical study

 The expression of tenascin (TN) in the temporomandibular joint (TMJ) disc and synovial membrane was examined in 18 human TMJ samples from patients with internal derangement of the TMJ and ten control specimens by an immunohistological technique using paraffin-embedded tissue and specific anti-human TN monoclonal antibody (RCB-1). The expression of TN was observed in all 28 samples, but it was limited to the walls of blood vessels, the perineurium, and the surface of the TMJ disc. The expression of TN was diffuse in the stroma of mildly hypertrophic synovial membranes and focal in the surface of severely hypertrophic synovial membranes. The clinical symptoms of internal derangement of the TMJ are thought to be related to the degree of synovitis. The present study demonstrates that TN is expressed specifically in the portion of the TMJ synovial membrane affected with internal derangement. Accepted: 17 December 1996