Up-regulation of vascular endothelial growth factor in synovial fibroblasts from human temporomandibular joint by hypoxia

INTRODUCTION: Enhanced expression of vascular endothelial growth factor (VEGF) has been described in patients with internal derangement (ID). Herein, we examined the expression of VEGF in synovial fibroblasts from temporomandibular joint (TMJ) under hypoxia and investigated the regulation of hypoxia-inducible factor-1alpha (HIF-1alpha) involved in the expression of VEGF. METHODS: Synovial fibroblasts were prepared from human TMJ. These cells were incubated under hypoxia or normoxia for the indicated time periods. VEGF levels in cultured supernatant were measured by an ELISA. VEGF mRNA isoforms and stability were assessed using RT-PCR and Northern blot analysis respectively. HIF-1alpha accumulation was evaluated by Western blotting and immunofluorescence. RESULTS: VEGF were significantly induced by hypoxia in synovial fibroblasts. In response to hypoxia, VEGF121 and VEGF165 mRNA were both remarkably increased, while there was no change in VEGF mRNA stability. The accumulation and nuclear translocation of HIF-1alpha occurred under hypoxia. CONCLUSIONS: Hypoxia may mainly induce the expression of VEGF121 and VEGF165 in synovial fibroblasts to promote inflamed angiogenesis of TMJ. HIF-1alpha, which is clearly activated in response to hypoxia, may control the expression of VEGF in synovial fibroblasts from TMJ.     

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.     

The localization of matrix metalloproteinase-3 and tenascin in synovial membrane of the temporomandibular joint with internal derangement

OBJECTIVES: The aim of this investigation was to study the immunohistochemical localization of MMP-3 and tenascin in the temporomandibular joint and to compare it with control specimens. MATERIALS AND METHODS: Localizations of matrix metalloproteinase-3 (MMP-3) and tenascin in the temporomandibular joint disc and the synovial membrane in 26 human temporomandibular joint samples (internal derangement of TMJ; n = 16, and control; n = 10) by an immunohistological method with monoclonal antibodies specific to human MMP-3 and tenascin. RESULTS: MMP-3 was not distributed in control specimens while it was observed in the internal derangement cases. MMP-3 showed two staining profiles: (1) diffuse staining was observed within the stroma of severely deformed disc with osteophyte and/or disc displacement (three of 16 specimens); and (2) the localization was specifically detected on the surface of severely hypertrophic synovial membrane (six of 16 specimens). The latter localization pattern resembled that of the tenascin on the surface of the severely hypertrophic synovial membrane. CONCLUSION: Comparative localization of MMP-3 and tenascin revealed intense staining for both in the synovial membrane presenting inflammation, proliferation and hypertrophy. These findings suggest that tissue repair and remodeling in the temporomandibular joint disc and the inflammatory hypertrophic reaction in the synovial membrane might proceed at the same time.     

Expression of vascular endothelial growth factor in human dysfunctional temporomandibular joint discs

A high density of blood vessels is found in specimens of temporomandibular joint (TMJ) disc at any stage of internal derangement of the joint, but the factors responsible for angiogenesis in the disc have not been described. The purpose here was to investigate, in human TMJ discs, the expression of vascular endothelial growth factor (VEGF), a multifunctional cytokine that contributes to angiogenesis. Specimens, free of significant morphological alterations and with varying degrees of disc tissue degeneration/regeneration, were studied by immunohistochemistry for VEGF in order to correlate immunohistochemical with histopathological findings. In normal discs and discs with minor pathological changes, fibroblast-like cells, fibrochondrocytes and chondrocyte-like cells were either not or only weakly immunostained by VEGF antibody. In disc specimens from internal derangement of the TMJ with significant tissue degeneration/regeneration, VEGF was consistently expressed. In these specimens, immunoreaction products for VEGF were observed both in the disc and in the endothelial cells of newly formed vessels. This VEGF immunolocalization is consistent with the stimulation of angiogenesis and the morphogenesis and differentiation of chondrocytes. Therefore VEGF expression by disc chondrocyte-like cells might reflect the action of the cytokine as an inducer of angiogenesis and as an autocrine signal for cells of the chondrogenic lineage.     

Aggrecanase analysis of synovial fluid of temporomandibular joint disorders

OBJECTIVES: To determine whether or not aggrecanase in synovial fluid can be used as a biochemical marker in the diagnosis of temporomandibular joint disorder (TMJD). MATERIALS AND METHODS: Forty-four samples of synovial fluid were obtained from 35 patients with internal derangement or osteoarthritis and 15 control samples from 10 asymptomatic volunteers. Aggrecanase in the synovial fluid was examined by immunoblotting. RESULT: The incidence of aggrecanase expression in TMJD group were significantly higher than that in the normal control group (P < 0.05). Those with severe OA and anterior disc displacement without reduction showed significantly high expression of aggrecanase compared with other disease subgroups (P < 0.05). CONCLUSION: These findings suggested that aggrecanase could be a potential biochemical marker for cartilage degeneration in the TMJD.     

Long-term evaluation of 211 patients with internal derangement of the temporomandibular joint

This report is a long-term evaluation of 211 patients (158 women, 53 men) with TMJ clicking and/or TMJ incoordination, treated at the University Hospital of Copenhagen, Denmark, in the years 1971-77. Information on present symptoms and the effect of the initial treatment was obtained from questionnaires. Standard treatment procedures had been used in 153 patients while 58 patients had had counseling only. In the actively treated group, 59% were still doing well, 30% had unchanged symptoms and 5% experienced aggravated symptoms. In the counseled group, 40% were free of symptoms, 50% had unchanged symptoms and 7% aggravated symptoms. A highly significant association was found between the absence or presence of symptoms at the end of treatment according to patient records and the evaluation of the initial effect of treatment 8-15 yr later, which indicates that reliable results can be expected from a long-term evaluation of TMJ dysfunction patients. In the sample as a whole, the frequency of TMJ sounds was unchanged compared to the time of treatment (64% vs 66%). A significantly higher frequency was, however, found in the untreated group, indicating that treatment might have a positive effect on TMJ sounds. The frequency of recurrent headache had increased considerably over the years (6% vs 34%), 32% still experienced pain/tenderness on mandibular movement, 24% suffered from impaired mandibular mobility and 82% were aware of bruxism/clenching of teeth. Furthermore, we found a significant association between headache before treatment and headache, awareness of bruxism and clenching of teeth at the time of evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and characterization of synovial cells from the human temporomandibular joint

BACKGROUND: The synovial tissues with temporomandibular disorders (TMDs) often show chronic inflammatory changes and the synovial cells participate in the pathogenic processes of TMDs. The synovial membrane is composed of a synovial lining layer and a connective sublining layer. The synovial lining layer is made up of two kinds of cells: macrophage-like type A and fibroblastic type B cells. The aim of this study was to isolate and characterize synovial cells from the human temporomandibular joint (TMJ). METHODS: Synovial cells were isolated using an explant culture method. Then, we characterized the cultured synovial cells (SGA2 cells) using immunocytochemistry. RESULTS: SGA2 cells expressed the fibroblastic markers vimentin and prolyl 4-hydroxylase; they also expressed laminin and heat shock protein 27, all of which are markers of type B cells. However, some cells expressed the macrophage marker CD68. These CD68-positive cells simultaneously expressed laminin. CONCLUSIONS: We isolated and cultured synovial type B cells from the human TMJ, and identified the presence of intermediate type synovial lining cells, having the phenotypic properties of both type A and type B cells, among the synovial lining cells.     

Immunohistochemical distribution of lymph capillaries and blood capillaries in the synovial membrane in cases of internal derangement of the temporomandibular joint

The distribution of lymph capillaries and blood capillaries in the synovial membrane was examined immunohistologically with anti–human collagen IV antibody and anti–human von Willebrand factor in 26 human temporomandibular joint (TMJ) samples comprising discs with adjoining synovial membrane from 10 control TMJs and from 16 TMJs with internal derangement. Three different distribution types were observed in the synovial membrane. In the control samples, the occurence of blood capillaries and lymph capillaries was rare. In mildly hyperplastic synovitis. lymph capillaries were observed just beneath the surface of the synovial membrane, whereas blood capillaries occurred in a little deeper layer of the synovia! membrane. In a severely hyperplastic synovitis. both lymph and Wood capillaries were observed frequently. The present results suggest that the different distribution patterns of lymph capillaries and blood capillaries reflect the degree of synovitis but can not be attributed to specific clinical symptoms.     

Vascular endothelial growth factor in human periodontal disease

Vascular endothelial growth factor (VEGF) is a multifunctional angiogenic cytokine of importance in inflammation and wound healing but its presence in chronic inflammatory periodontal disease has never been reported. The aims of this study were to investigate the presence of VEGF in human periodontal tissue and gingival crevicular fluid (GCF) in periodontal health and disease. VEGF in tissue was localized by immunohistochemistry. GCF and unstimulated saliva were collected from patients and clinically healthy subjects and VEGF was assessed by using an ELISA. VEGF was detected within vascular endothelial cells, neutrophils, plasma cells and junctional, pocket and gingival epithelium. In periodontitis patients, the volume of GCF and total amount of VEGF collected from diseased sites were both greater than from clinically healthy sites (Wilcoxon test p <0.01). However, the concentration of VEGF per unit volume of GCF was higher at healthy sites compared with diseased sites (Wilcoxon test p<0.05). Higher concentrations of VEGF were detected in healthy sites in patients compared with similar sites in clinically healthy subjects (Mann-Whitney U-test p <0.05). A logistic regression approach indicated that there was variation in VEGF between subjects (p<0.01), and that age (p<0.05), plaque (p < 0.05) and pocket depth (p < 0.07) were explanatory variables. VEGF was also detected in all saliva samples and was significantly higher in patients than in healthy controls (p<0.05). This study suggests that VEGF could be relevant to angiogenic processes in healthy as well as diseased periodontal tissue and that the periodontal status influences the salivary level of VEGF.     

Cytokines in healthy temporomandibular joint synovial fluid

Analysis of temporomandibular joint (TMJ) synovial fluid may elucidate the aetiology of temporomandibular disorders and arthritic conditions, as well as the inflammatory mechanisms involved. Knowledge about healthy synovial fluid is necessary to understand TMJ pathologies. We aimed to quantify the proinflammatory cytokines interleukin (IL)‐1β, IL‐2, IL‐6 and tumour necrosis factor (TNF), and the anti‐inflammatory cytokines IL‐10 and interferon (IFN)‐γ in healthy TMJ synovial fluid to serve as reference values for future studies on TMJ pathologies. Twenty healthy, young adult volunteers without temporomandibular dysfunction were included. Bilateral synovial fluid samples were obtained using the push‐pull technique with hydroxocobalamin described by Alstergren in 1999. Cytokines were quantified with Luminex multiplex assays and compared using nonparametric statistical analysis. No serious adverse effects were reported. Of 40 possible samples, 14 fulfilled the strict sampling criteria and were included in the analysis. Cytokine values (reported as medians with interquartile ranges) were as follows: TNF, 23 (13–37) pg mL^?1; IL‐2, 1·8 (0–22) pg mL^?1; and INF‐γ, 10 (0–47) pg mL^?1. IL‐1β, IL‐6 and IL‐10 were almost undetectable. In addition, TNF and INF‐γ cytokine levels correlated. We demonstrated that TNF was consistently detected and IFN‐γ and IL‐2 sporadically detected in the TMJ synovial fluid of healthy individuals using the hydroxocobalamin method and a multiplex assay. The cytokines IL‐10, IL‐1β and IL‐6 were barely detectable in this sample of healthy TMJs.     

Levels of fibroblast growth factor 2 in synovial fluids in human patients with internal derangement of the temporomandibular joint

OBJECTIVE: We sought to elucidate the levels of fibroblast growth factor 2 (FGF-2) in synovial fluid taken from internally deranged human temporomandibular joints (TMJs) and to discuss the role of FGF-2 in the pathogenesis of internal derangement. STUDY DESIGN: Through the use of a pumping procedure, diluted synovial fluid was collected from the upper joint compartment of 22 TMJs with evidence of internal derangement (21 patients) and 8 TMJs with no such evidence (5 control subjects). Two of the control subjects were patients who had habitual dislocation, and three were healthy volunteers. The level of FGF-2 in the synovial fluid was assessed by means of an enzyme-linked immunosorbent assay. RESULTS: FGF-2 levels were at detectable levels in 15 of the 22 TMJs (68%) with internal derangement. The mean concentration of FGF-2 was 24 pg/mL. In the control group, FGF-2 levels were detectable in only 1 of 8 joints (13%), for a concentration of 3 pg/mL. The mean concentration of FGF-2 in the synovial fluid was significantly higher in the internal derangement group than in the control group (P =.02). CONCLUSIONS: FGF-2 levels are elevated in the human synovial fluid of TMJs with internal derangement.     

A decrease in the molecular weight of hyaluronic acid in synovial fluid from patients with temporomandibular disorders

BACKGROUND: The molecular weight (MW) of hyaluronic acid (HA) in joints generally declines in inflammatory arthritis. As inflammation exists in certain temporomandibular disorders (TMD), we measured the MW of HA in synovial fluid (SF) recovered from patients with TMD and compared it with that from normal controls. METHODS: Synovial fluid was obtained from patients with TMD (21 TMJs) and normal controls (5 TMJs). The MW of HA was measured using high-performance liquid chromatography (HPLC). RESULTS: In the controls, the MW of HA in SF exceeded the detection limit, 3000 kDa. In contrast, 19 (90.5%) of 21 SF samples from patients showed a decreased MW of HA. The median MW of HA (1570 kDa) in TMD was significantly lower than that in the controls (P < 0.01). CONCLUSION: The MW of HA in SF from patients with TMD is decreased.     

The expression of vascular endothelial growth factor in synovial tissues in patients with internal derangement of the temporomandibular joint

OBJECTIVE: The aim of this study was to elucidate the expression and localization of vascular endothelial growth factor (VEGF) in synovial tissue taken from the temporomandibular joint (TMJ) with internal derangement (ID) and discuss the role of VEGF in the pathogenesis of ID. STUDY DESIGN: Through the use of an immunohistochemical technique, 39 TMJs in 37 patients were examined. As controls, synovial tissue specimens from 6 joints in 6 patients with habitual dislocation were also examined. RESULTS: In the synovial tissue from 35 of the patients with ID, expression of VEGF was observed in the synovial lining cells, in the endothelial cells of the blood vessels, and in the fibroblasts. In contrast, expression of VEGF was found in the TMJ tissue from only 2 of the controls. The percentage of VEGF-positive cells in the ID specimens was significantly higher than that in the habitual dislocation specimens (P < .02), and the expression of VEGF significantly correlated with the arthroscopic synovitis score (P = .004). CONCLUSION: These results suggest that the expression of VEGF is upregulated and involved in the development of inflammatory changes in synovial tissues in TMJs with ID.     

A case of synovial chondromatosis of the temporomandibular joint secondary to preauricular trauma

Synovial chondromatosis is a rare benign arthropathy characterized by chondrometaplasia of the synovial membrane, particularly in the temporomandibular joint (TMJ). The purpose of this article is to describe an uncommon case of synovial chondromatosis arising from the inferior joint space of the TMJ with an enlarged condyle secondary to preauricular trauma in a 44-year-old healthy male. The possible role of a traumatic event in the etiology, the usefulness of the combined performance of CT and MRI examinations for preoperative diagnosis and current treatment are discussed.     

Lubricin immunohistochemical expression in human temporomandibular joint disc with internal derangement

J Oral Pathol Med (2011) 40 : 587–592 Lubricin is a chondroprotective, mucinous glycoprotein which contribute to joint lubrication, especially to boundary lubrication and maintains joint integrity. The present investigation aimed to study the immunolocalization of lubricin in TMJ discs from patients affected by anterior disc displacement with reduction (ADDwR) ADDwoR. Eighteen TMJ displaced disc affected by ADDwoR were processed immunohistochemically, with a polyclonal anti‐lubricin antibody, used at 1:50 working dilution. The percentage of lubricin immunopositive cells (extent score = ES) and the extent of lubricin staining of the disc extracellular matrix (ECM), were evaluated. Each sample was scored for histopathological changes. Percentage of immunostained surface disc cells was the same (ES = 4) in both control and ADDwOR cells, being this data not statistically significant (P < 0.05). In pathological specimens the percentages of lubricin‐stained cells was very high with an ES of 4 respect to control specimen, and this difference was statistically significant different (P > 0.05). The extracellular matrix (ECM) of discs at the disc surfaces of both pathological and normal specimens was very heavily stained (++++). Both the ES and ECM staining were not statistically correlated to the TMJ degeneration score according to the Spearman’s rank correlation coefficient. According to our findings, a longstanding TMJ disc injury, affects lubricin expression in the TMJ disc tissue and not its surfaces, moreover, lubricin immunostaining is not correlated to TMJ disc histopathological changes.     

Superoxide dismutase activity in synovial fluids in patients with temporomandibular joint internal derangement.

PURPOSE: To measure the activity of superoxide dismutase (SOD) in the synovial fluid of patients with temporomandibular joint internal derangement and to show the relationship between the activity of SOD and the severity of the disease. MATERIALS AND METHODS: Twenty patients with internal derangement were classified according to Wilkes by clinical radiological examinations. SOD activity was measured by the method based on nitrobluetetrazolium reduction rate. RESULTS: The activity of SOD seemed to be progressively decreased as the stage of the disease increased. CONCLUSION: The reduction of SOD activity observed may result from insufficient scavenging capacity of free radicals. Further investigation and longitudinal studies are required to determine the role of antioxidants that scavenge the free radicals in temporomandibular joint disorders.     

Synovial fluid dynamics with small disc perforation in temporomandibular joint

Summary The articular disc plays an important role as a stress absorber in joint movement, resulting in stress reduction and redistribution in the temporomandibular joint (TMJ). The flow of synovial fluid in the TMJ may follow a regular pattern during movement of the jaw. We hypothesised that the regular pattern is disrupted when the TMJ disc is perforated. By computed tomography arthrography, we studied the upper TMJ compartment in patients with small disc perforation during jaw opening–closing at positions from 0 to 3 cm. Finite element fluid dynamic modelling was accomplished to analyse the pattern of fluid flow and pressure distribution during the movements. The results showed that the fluid flow in the upper compartment generally formed an anticlockwise circulation but with local vortexes with the jaw opening up to 2 cm. However, when the jaw opening–closing reached 3 cm, an abnormal flow field and the fluid pressure change associated with the perforation may increase the risk of perforation expansion or rupture and is unfavourable for self‐repair of the perforated disc.     

The role of molecular pain biomarkers in temporomandibular joint internal derangement

There is evidence that low‐grade inflammation may be responsible for pain and development of degenerative changes in temporomandibular joint internal derangement. This article reviews the current knowledge of the molecular mechanisms behind TMJ internal derangements. A non‐systematic search was carried out in PubMed, Embase and the Cochrane library for studies regarding pathophysiological mechanisms behind internal derangements focusing on pain‐mediating inflammatory and cartilage‐degrading molecules. Recent data suggest that release of cytokines may be the key event for pain and cartilage destruction in TMJ internal derangements. Cytokines promote the release of matrix metalloproteinases (MMPs), and due to hypoxia, vascular endothelial growth factor (VEGF) is released. This activates chondrocytes to produce MMPs and reduce their tissue inhibitors (TIMPs) as well as the recruitment of osteoclasts, ultimately leading to cartilage and bone resorption. Also, proteoglycans have an important role in this process. Several cytokines, MMPs, TIMPs and VEGF have been identified in higher concentrations in the TMJ synovial fluid of patients with painful internal derangements and shown to be associated with the degree of degeneration. Other molecules that show elevated levels include hyaluronic acid synthase, disintegrin and metalloproteinase with thrombospondin motifs (ADAMTs), aggrecan, fibromodulin, biglycan and lumican. Taken together, more or less pronounced inflammation of TMJ structures with release of cytokines, MMPs and other molecular markers that interact in a complex manner may be responsible for tissue degeneration in internal derangements. As internal derangements may be symptom‐free, the degree of inflammation, but also other mechanisms, may be important for pain development.     

Cytokines in temporomandibular joint arthritis

As the article in the current issue by Shinoda and colleagues shows, during the last two decades, there has been a dramatic increase in the understanding of basic biology behind chronic temporomandibular joint (TMJ) pain, inflammation and destruction. The involvement and contribution of cytokines to TMJ pain and inflammation must now be considered as established, evident and fundamental. Based on the present knowledge, it is now possible to design and investigate novel therapeutic strategies. These new and very encouraging approaches include manipulation of cytokine function, immune reactivity and the behaviour of inflammatory cells while maintaining the integrity of the affected tissue.