Association between arthroscopic diagnosis of temporomandibular joint osteoarthritis and synovial fluid nitric oxide levels

A flexible and physically transient electrochemical sensor for real-time wireless nitric oxide monitoring

Real-time sensing of nitric oxide (NO) in physiological environments is critically important in monitoring neurotransmission, inflammatory responses, cardiovascular systems, etc. Conventional approaches for NO detection relying on indirect colorimetric measurement or built with rigid and permanent materials cannot provide continuous monitoring and/or require additional surgical retrieval of the implants, which comes with increased risks and hospital cost. Herein, we report a flexible, biologically degradable and wirelessly operated electrochemical sensor for real-time NO detection with a low detection limit (3.97 nmol), a wide sensing range (0.01-100 μM), and desirable anti-interference characteristics. The device successfully captures NO evolution in cultured cells and organs, with results comparable to those obtained from the standard Griess assay. Incorporated with a wireless circuit, the sensor platform achieves continuous sensing of NO levels in living mammals for several days. The work may provide essential diagnostic and therapeutic information for health assessment, treatment optimization and postsurgical monitoring.

Association between oxidative stress and temporomandibular joint dysfunction: A narrative review

BACKGROUND

The role of oxidative stress in temporomandibular disorders (TMDs) has been studied using synovial fluid, to evaluate oxidative stress (im)balance and its potential role in the onset and/or progression of the disease.

OBJECTIVE

This review aimed to evaluate the association between oxidative stress markers and the etiopathogenesis of TMJ dysfunction by means of synovial fluid analysis.

METHODS

Two independent reviewers searched the electronic databases from inception to March 2019: PubMed/MEDLINE, LILACS, SciELO, EMBASE, TRIPDATABASE, SCOPUS, and Google Scholar. The following key search terms were used: Temporomandibular Joint Disorders OR Temporomandibular Joint Disc OR Temporomandibular Joint Dysfunction Syndrome OR Temporomandibular Joint OR Facial Pain AND Free Radicals OR Oxidative Stress. Data were extracted from the selected articles, including study design, sample profile, TMJ disease reported, diagnostic method, reactive oxygen and nitrogen species evaluated, enzymatic and non-enzymatic antioxidants evaluated, and techniques used to measure free radicals and antioxidants.

RESULTS

After title and abstract screening of 6974 results, and full-text reading, 19 studies were included. All selected articles were cross-sectional observational studies. Enzymatic and non-enzymatic antioxidant defences appeared to be reduced in these patients, resulting in the establishment of the oxidative stress process. In addition, the studies showed a positive correlation between the severity of the intra-articular TMD and the increase in oxidative damage.

CONCLUSION

The establishment of oxidative stress, whether by an increase in reactive oxygen/nitrogen species or by a decrease in antioxidant defences, or a combination of both, may be associated with the establishment and maintenance of intra-articular damage.

Diverse Physiological Roles of Calcitonin Gene-Related Peptide in Migraine Pathology: Modulation of Neuronal-Glial-Immune Cells to Promote Peripheral and Central Sensitization

The neuropeptide calcitonin gene-related peptide (CGRP) is implicated in the underlying pathology of migraine by promoting the development of a sensitized state of primary and secondary nociceptive neurons. The ability of CGRP to initiate and maintain peripheral and central sensitization is mediated by modulation of neuronal, glial, and immune cells in the trigeminal nociceptive signaling pathway. There is accumulating evidence to support a key role of CGRP in promoting cross excitation within the trigeminal ganglion that may help to explain the high co-morbidity of migraine with rhinosinusitis and temporomandibular joint disorder. In addition, there is emerging evidence that CGRP facilitates and sustains a hyperresponsive neuronal state in migraineurs mediated by reported risk factors such as stress and anxiety. In this review, the significant role of CGRP as a modulator of the trigeminal system will be discussed to provide a better understanding of the underlying pathology associated with the migraine phenotype.

Rationale of arthroscopic surgery of the temporomandibular joint

Arthroscopic surgery has been widely used for treatment of temporomandibular joint (TMJ) internal derangements and diseases for the last 40 years. Although 626 articles have been hit by Pubmed search in terms of "TMJ arthroscopic surgery", this review article is described based on distinguished publishing works and on my experiences with TMJ arthroscopic surgery and related research with an aim to analyse the rationale of arthroscopic surgeries of the temporomandibular joint. With arthrocentesis emerging as an alternative, less invasive, treatment for internal derangement with closed lock, the primary indication of arthroscopic surgery seems to be somewhat limited. However, the value of endoscopic inspection and surgery has its position for both patient and physician with its long-term reliable results.

Cytoprotective and anti-inflammatory effects of melatonin in hydrogen peroxide-stimulated CHON-001 human chondrocyte cell line and rabbit model of osteoarthritis via the SIRT1 pathway

Melatonin has potent antioxidant, analgesic, and antinociceptive properties. However, the effects of melatonin against oxidative stress-induced cytotoxicity and inflammatory mediators in human chondrocytes remain poorly understood. This study examined the effects and underlying mechanism of melatonin in hydrogen peroxide (H(2) O(2) )-stimulated human chondrocytes and rabbit osteoarthritis (OA) model. Melatonin markedly inhibited hydrogen peroxide (H(2) O(2) )-stimulated cytotoxicity, iNOS, and COX-2 protein and mRNA expression, as well as the downstream products, NO and PGE(2) . Incubation of cells with melatonin decreased H(2) O(2) -induced Sirtuin 1 (SIRT1) mRNA and protein expression. SIRT1 inhibition by sirtinol or Sirt1 siRNA reversed the effects of melatonin on H(2) O(2) -mediated induction of pro-inflammatory cytokines (NO, PGE(2) , TNF-α, IL-1β, and IL-8) and the expression of iNOS, COX-2, and cartilage destruction molecules. Melatonin blocked H(2) O(2) -induced phosphorylation of PI3K/Akt, p38, ERK, JNK, and MAPK, as well as activation of NF-κB, which was reversed by sirtinol and SIRT1 siRNA. In rabbit with OA, intra-articular injection of melatonin significantly reduced cartilage degradation, which was reversed by sirtinol. Taken together, this study shows that melatonin exerts cytoprotective and anti-inflammatory effects in an oxidative stress-stimulated chondrocyte model and rabbit OA model, and that the SIRT1 pathway is strongly involved in this effect.

Cocoa-enriched diets enhance expression of phosphatases and decrease expression of inflammatory molecules in trigeminal ganglion neurons

Activation of trigeminal nerves and release of neuropeptides that promote inflammation are implicated in the underlying pathology of migraine and temporomandibular joint (TMJ) disorders. The overall response of trigeminal nerves to peripheral inflammatory stimuli involves a balance between enzymes that promote inflammation, kinases, and those that restore homeostasis, phosphatases. The goal of this study was to determine the effects of a cocoa-enriched diet on the expression of key inflammatory proteins in trigeminal ganglion neurons under basal and inflammatory conditions. Rats were fed a control diet or an isocaloric diet enriched in cocoa for 14days prior to an injection of noxious stimuli to cause acute or chronic excitation of trigeminal neurons. In animals fed a cocoa-enriched diet, basal levels of the mitogen-activated kinase (MAP) phosphatases MKP-1 and MKP-3 were elevated in neurons. Importantly, the stimulatory effects of acute or chronic peripheral inflammation on neuronal expression of the MAPK p38 and extracellular signal-regulated kinases (ERK) were significantly repressed in response to cocoa. Similarly, dietary cocoa significantly suppressed basal neuronal expression of calcitonin gene-related peptide (CGRP) as well as stimulated levels of the inducible form of nitric oxide synthase (iNOS), proteins implicated in the underlying pathology of migraine and TMJ disorders. To our knowledge, this is the first evidence that a dietary supplement can cause upregulation of MKP, and that cocoa can prevent inflammatory responses in trigeminal ganglion neurons. Furthermore, our data provide evidence that cocoa contains biologically active compounds that would be beneficial in the treatment of migraine and TMJ disorders.

Mechanical stretch enhances NF-kappaB-dependent gene expression and poly(ADP-ribose) synthesis in synovial cells

Temporomandibular joint disorders (TMD) show complex symptoms associated with inflammation, pain and degeneration of the peripheral tissues including synovium. Although it is believed that excessive mechanical stress on synovium causes development of TMD, the molecular mechanism by which mechanical stress triggers TMD has still remained unclear. In order to examine the effect of mechanical stress on synoviocytes, rabbit synovial cells were cyclically stretched in vitro. The stretch efficiently increased the gene expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and NF-kappaB responsive reporter gene constructs. The interruption of NF-kappaB activating pathway by inhibitors resulted in the abrogation of those expressions, indicating the pivotal role of NF-kappaB in the mechanical stretch-mediated COX-2 and iNOS expressions. In parallel, the stretch remarkably increased NO production and poly(ADP-ribose) (PAR) synthesis, suggesting that excessive amounts of NO causes DNA injury and in turn activates PAR synthesis by poly(ADP-ribose) polymerase (PARP). The inhibition of PAR synthesis by a PARP inhibitor or a radical scavenger enhanced the mechanical stretch-induced gene expressions in a NF-kappaB-independent manner, implying an involvement of PARP in the gene expression. Taken together, these results demonstrate that mechanical stress on synovial cells not only induces gene expressions of COX-2 and iNOS but also affects PAR synthesis.

Temporomandibular joint pain and synovial fluid analysis: a review of the literature

The pathophysiology of temporomandibular joint pain is not well understood. A significant amount of research has been conducted to evaluate synovial fluid in these patients and in healthy controls. Qualitative and quantitative analyses of the synovial fluid have shown a significant difference between these groups. A multitude of inflammatory mediators and degradation products have been identified. The concentration of these products has been shown to correlate with several clinical parameters including pain, chronicity, severity of degenerative change, and response to treatment. A common inflammatory pathway would appear to be involved in most patients. At the present time, synovial fluid analysis does not have the sensitivity or specificity to allow specific diagnoses and targeted treatment. Continued research with the specific aim of establishing more appropriate therapeutic modalities based on the biochemical pathways is warranted.

CGRP stimulation of iNOS and NO release from trigeminal ganglion glial cells involves mitogen-activated protein kinase pathways

Clinical and basic science data support an integral role of calcitonin gene-related peptide (CGRP) in the pathophysiology of temporomandibular joint disorders. Recently, we have shown that CGRP can stimulate the synthesis and release of nitric oxide (NO) from trigeminal ganglion glial cells. The goal of this study was to determine the role of mitogen-activated protein kinase (MAPK) signaling pathways in CGRP regulation of iNOS expression and NO release from cultured trigeminal ganglion glial cells from Sprague-Dawley rats. CGRP treatment for 2 h significantly increased activity of the MAPK reporter genes, Elk, ATF-2, and CHOP. In addition, CGRP increased nuclear staining for the active forms of the MAPKs: extracellular signal-regulated kinase, c-Jun amino-terminal kinase, and p38. This stimulatory event was not observed in cultures pre-treated with the CGRP receptor antagonist peptide CGRP(8-37). Similarly, pre-treatment with selective MAPK inhibitors repressed increases in reporter gene activity as well as CGRP-induced increases in iNOS expression and NO release mediated by MAPKs. In addition, over-expression of MAPK kinase 1 (MEK1), MEK3, MEK6, and MEK kinase significantly increased iNOS expression and NO production in glial cells. Results from our study provide evidence that CGRP binding to its receptor can stimulate iNOS gene expression via activation of MAPK pathways in trigeminal ganglion glial cells.

Comparison of the effectiveness and tolerability of lidocaine patch 5% versus celecoxib for osteoarthritis-related knee pain: post hoc analysis of a 12 week, prospective, randomized, active-controlled, open-label, parallel-group trial in adults

BACKGROUND

Cyclooxygenase-2 (COX-2) selective inhibitors and nonselective NSAIDs are commonly used to treat osteoarthritis (OA) of the knee.

OBJECTIVE

The aim of this study was to compare the effectiveness of the lidocaine patch 5% with that of celecoxib 200 mg/d in the treatment of OA-related knee pain; however, the study was terminated prematurely by the sponsor because of tolerability concerns regarding the class of COX-2 selective inhibitors. A post hoc analysis of the available data is presented here.

METHODS

This multicenter, randomized, open-label, active-controlled, parallel-group study included patients >or=18 years of age with unilateral or bilateral moderate to severe OA of the knee. Patients were randomized to receive treatment with either the lidocaine patch 5% or celecoxib 200 mg/d. The primary efficacy end point was change from baseline to 12 weeks in the Western Ontario and McMaster Universities (WOMAC) OA Index pain subscale. Secondary end points included additional WOMAC subscales and Brief Pain Inventory (BPI) measures. Because this trial was prematurely terminated, a post hoc analysis was performed using a random pattern-mixture model of all observed cases of the intent-to-treat population.

RESULTS

A total of 143 patients were randomized to treatment (lidocaine patch 5%, 69 patients; mean [SD] age, 60.2 [11.4] years; 65.2% female; 66.7% white; weight, 94.1 [23.3] kg) or celecoxib 200 mg/d (74 patients; age, 58.2 [12.1] years; 63.5% female; 68.9% white; weight, 94.3 [22.5] kg). Baseline pain WOMAC OA subscale scores (lidocaine patch 5%, 12.087; celecoxib 200 mg/d, 12.514) and mean rates of change over time (baseline to week 2, -1.5916 vs -1.6513 per week; weeks 2-6, -0.0168 vs -0.119 per week; weeks 6-12, -0.1818 vs -0.1579 per week) were not significantly different between the 2 groups. Improvement in additional WOMAC subscales and in several BPI measures were not significantly different between the 2 groups. Treatment-related adverse events were reported in 8 patients in each treatment group (11.6% in the lidocaine patch 5% group and 10.8% in the celecoxib 200-mg/d group) and were considered mild or moderate in severity.

CONCLUSION

Statistically significant differences in effectiveness and tolerability were not found between these 2 treatments in these patients with OA knee pain.

Nitric oxide-proton stimulation of trigeminal ganglion neurons increases mitogen-activated protein kinase and phosphatase expression in neurons and satellite glial cells

Elevated nitric oxide (NO) and proton levels in synovial fluid are implicated in joint pathology. However, signaling pathways stimulated by these molecules that mediate inflammation and pain in the temporomandibular joint (TMJ) have not been investigated. The goal of this study was to determine the effect of NO-proton stimulation of rat trigeminal neurons on the in vivo expression of mitogen-activated protein kinases (MAPKs) and phosphatases (MKPs) in trigeminal ganglion neurons and satellite glial cells. Low levels of the active MAPKs extracellular signal-regulated kinase (ERK), Jun amino-terminal kinase (JNK), and p38 were localized in the cytosol of neurons and satellite glial cells in unstimulated animals. However, increased levels of active ERK and p38, but not JNK, were detected in the cytosol and nucleus of V3 neurons and satellite glial cells 15 min and 2 h following bilateral TMJ injections of an NO donor diluted in pH 5.5 medium. While ERK levels returned to near basal levels 24 h after stimulation, p38 levels remained significantly elevated. In contrast to MKP-2 and MKP-3 levels that were barely detectable in neurons or satellite glial cells, MKP-1 staining was readily observed in satellite glial cells in ganglia from unstimulated animals. However, neuronal and satellite glial cell staining for MKP-1, MKP-2, and MKP-3 was significantly increased in response to NO-protons. Increased active ERK and p38 levels as well as elevated MKP levels were also detected in neurons and satellite glial cells located in V2 and V1 regions of the ganglion. Our data provide evidence that NO-proton stimulation of V3 neurons results in temporal and spatial changes in expression of active ERK and p38 and MKPs in all regions of the ganglion. We propose that in trigeminal ganglia these cellular events, which are involved in peripheral sensitization as well as control of inflammatory and nociceptive responses, may play a role in TMJ pathology.

iNOS expression in oral and gastrointestinal tract mucosa

It is known that the overproduction of nitric oxide (NO) by nitric oxide synthase (NOS) occurs during the progression of various inflammatory diseases in intestinal tract. NOS inhibitors or inducible nitric oxide synthase (iNOS) gene expression inhibitors should be considered as potential anti-inflammatory agents, as NO synthesized by iNOS is related to various pathophysiological processes including inflammation. In order to understand the relationship between iNOS and pathological reactions such as the inflammatory process and malign transformation clearly, the existence and amount of constitutive expression should be determined. It is crucial to comprehend the harmful and protective amounts of iNOS expressions in order to clarify the relationship between iNOS and pathological processes. Evidently, only after this inspection is it possible to utilize iNOS as a marker and treatment instrument during the diagnosis and treatment of malign transformation and the inflammatory process.

In vivo measurement of facet joint nitric oxide in patients with chronic low back pain

STUDY DESIGN

Prospective case-control study testing a new diagnostic method.

OBJECTIVE

The aim of the present study was to investigate the concentration of nitric oxide (NO) in the perifacetal region in patients with chronic low back pain and healthy controls.

SUMMARY OF BACKGROUND DATA

Facet joint arthrosis may be a pain source in chronic back pain. Increased concentrations of NO, an oxygen-free radical, have been demonstrated in temporomandibular and knee joints with osteoarthritis.

PATIENTS AND METHODS

Patients with at least 6 months' duration of chronic low back pain and signs of facet joint osteoarthrosis (n = 24) and healthy volunteers (n = 7) were included. A detailed questionnaire, including visual analogue scale, was completed before and 6 weeks after the measurements. NO was measured with a custom-designed electrochemical real-time NO sensor inserted under fluoroscopic guidance. All patients received corticosteroids and local anesthetics after NO measurements.

RESULTS

NO measurements were obtained from all participants. No adverse effects were noted. The patients with chronic low back pain demonstrated higher concentrations of NO in the perifacetal region compared with healthy controls (1.66 +/- 0.28 vs. 0.46 +/- 0.14 nmol/L, P = 0.007). No association between NO concentration and pain duration or pain level was detected. Patients with a positive response to local anesthetics and corticosteroid injection (defined as a >or=20 mm reduction of visual analogue scale at the 6-week follow-up visit) had higher NO concentrations than patients without positive response.

CONCLUSIONS

The study demonstrates that it is feasible and safe to measure NO with a real time-sensor in or around the facet joints. The findings of higher concentrations of NO in the perifacetal region in chronic low back patients compared with healthy controls indicate that the degenerative process of the joints in these patients may cause increased NO production. The observation of higher NO concentrations in the perifacetal region in patients responding to corticosteroid/local anesthetic infiltration indirectly suggest a more pronounced inflammatory process in these patients.

Compressive mechanical stress promotes osteoclast formation through RANKL expression on synovial cells

OBJECTIVES

We investigated the effects of compressive mechanical stress on osteoclastogenesis of synovial cells to clarify the mechanism of osteoclast formation by those cells in temporomandibular joint (TMJ) disorders.

STUDY DESIGN

Synovial cells were isolated from rat knee joints and continuously compressed using a conventional method. The expression of receptor activator nuclear factor kappaB ligand (RANKL) mRNA and protein in synovial cells was analyzed by reverse transcriptase-polymerase chain reaction, immunoblotting, and immunofluorescence staining. Mouse bone marrow cells were cultured with synovial cells for 7 days to detect osteoclasts.

RESULTS

The expressions of RANKL mRNA and protein in synovial cells were increased with compressive force. When mouse bone marrow cells were cultured with continuously compressed synovial cells, tartrate-resistant acid phosphatase-positive multinucleated cells were formed. Osteoprotegerin completely inhibited osteoclast formation induced by culturing with compressed synovial cells.

CONCLUSION

Our results indicated that the expression of RANKL in compressed synovial cells enhanced osteoclast formation, whereas continuous compressive force may induce osteoclastic bone destruction in the TMJ.

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.

A multifaceted molecule, nitric oxide in oral and periodontal diseases

Nitric oxide (NO) is a molecule with multiple effects on different tissues. NO takes important roles in vasodilatation, bacterial challenge and cytokine stimulation, regulation of mineralized tissue function, neurotransmission, and platelet aggregation, etc. However, under pathological conditions, NO has damaging effects. NO is synthesized by NO synthases (NOS) and inducible isoform of NOS (iNOS) is closely related to the pathophysiological characteristics of inflammatory diseases such as periodontal diseases. The expression of iNOS has been investigated in salivary gland-related diseases, temporomandibular joint disorders and oral cancer as well. The beneficial and damaging effects of NO in diseases related with periodontal, dental and maxillofacial area are discussed in this review. The biological pathways involved with NO and NO inhibitors may be good drug targets to have a role in the future management of patients with diseases in orofacial region.

Molecular correlates of temporomandibular joint disease

OBJECTIVE

The relation between disease severity and the known mediators of pain, inflammation, and tissue damage-prostaglandin E 2 (PGE 2 ), leukotriene B 4 (LTB 4 ), malondialdehyde (MDA), nitric oxide (NO), and myeloperoxidase (MPO)-was examined in the synovial fluid of patients with internal derangement (ID) of the temporomandibular joint (TMJ).

STUDY DESIGN

Thirty-two patients with ID were classified according to Wilkes by clinical and radiological examinations, and TMJ synovial fluid samples were obtained by arthrocentesis. PGE 2 and LTB 4 levels were measured by ELISA kits, MDA levels were determined by a fluorometric method, myeloperoxidase activity was determined by an end-point method, and NO levels were measured by Griess reaction.

RESULTS

The earliest significant increase was observed in NO levels (stage II) and this elevation persisted in the subsequent stages. The first significant elevation in PGE 2 and LTB 4 levels and MPO activity were observed in stage III. Both PGE 2 and LTB 4 levels were increased in stage III and were correlated with each at this stage and in the subsequent stage. Significant increases in MDA levels were observed only in stage IV. At stage IV there was correlation between MDA and PGE 2 , MDA and LTB 4 , and MDA and MPO. The relation between PGE 2 and MDA was the most powerful one.

CONCLUSION

Results of this cross-sectional study point out the relation between disease severity and levels of some molecular mediators in synovial fluid of TMJ. Longitudinal studies are needed to explore the role of these molecular mediators in the progression of ID.

Topical lidocaine patch 5% may target a novel underlying pain mechanism in osteoarthritis

Recent literature and animal research has provided insight to potentially new analgesic targets for managing osteoarthritis (OA) pain. Primary afferent neurons located in affected joints express excessive amounts of abnormally functioning sodium (Na) channels on their surface in response to the inflammatory process. These Na channels may play an integral role in production of pain and hyperalgesia. Hence, the authors set out to conduct a 2-week, open-label, multicenter proof-of-concept study to evaluate the effectiveness and safety of lidocaine patch 5% monotherapy in adults with OA pain of the knee (n = 20). Patients with OA of one or both knees who were experiencing inadequate pain relief (defined as an average daily pain intensity of > 4 on a 0 to 10 pain scale) with their current analgesic regimen (i.e. APAP, NSAIDs, COX-2 inhibitors, tramadol) were enrolled and had all analgesic medications discontinued. Treatment with the lidocaine patch 5% resulted in significant improvements in the Western Ontario and McMaster Universities OA Index (WOMAC) pain, stiffness, physical function subscales and composite index (48.4, 41.1, 47.0, and 46.8% improvements respectively, p < 0.01). In addition, significant improvement was noted for pain intensity, pain relief, and pain interference with quality of life as measured by the Brief Pain Inventory (p < 0.05). The lidocaine patch 5% was generally well tolerated and no patients discontinued due to treatment-related adverse events. Given the open-label design, lack of a control group, and small sample size, the findings from our pilot study need to be confirmed by larger randomized controlled trials. Topical lidocaine patch 5% may provide clinicians with a novel, non-systemic therapy for OA pain with a unique mechanism of action.

Lidocaine patch 5% and its positive impact on pain qualities in osteoarthritis: results of a pilot 2-week, open-label study using the Neuropathic Pain Scale

OBJECTIVE

To determine the impact of the lidocaine patch 5% on distinct pain qualities associated with osteoarthritis (OA) through use of the Neuropathic Pain Scale (NPS), an assessment tool designed to assess intensity of various pain qualities (i.e.sharp, dull).

PATIENTS AND METHODS

Patients were enrolled in a prospective, open-label, non-randomized, parallel-group, 2-week study involving 8 clinical trial sites in the United States. Eligible patients had radiographic evidence of OA involving one or both knees and reported moderate-to-severe pain (despite prn or stable doses of analgesics) on the NPS at study enrollment. Patients on prn analgesics were discontinued from all analgesic regimens prior to study entry and received lidocaine patch 5% as monotherapy. Those on stable doses of analgesics were continued on their other analgesic regimens with no additions or dose alterations allowed other than the lidocaine patch 5% as add-on therapy. The lidocaine patch 5% was applied to the area of maximal pain, using no more than a total of 4 patches changed every 24 h. Effectiveness was measured by change from baseline to Week 2 in 4 composite measures of the NPS: NPS-10, NPS-4, NPS-8, and NPS-nonallodynia. Safety was assessed by adverse events (AEs), dermal assessment of application site(s), and skin sensory testing.

RESULTS

In the combined patient population (n = 100), 2 weeks of treatment with lidocaine patch 5% significantly improved all 4 NPS composite measures (p < 0.001). Separate analyses by subgroups revealed significant improvements in all 4 composite measures for both the monotherapy group (n = 12; p < 0.01) and add-on therapy group (n = 88; p < 0.001). No treatment-related AEs were reported for the monotherapy group. In the add-on therapy group, 5 patients experienced mild-to-moderate treatment-related AEs.

CONCLUSIONS

In patients with moderate-to-severe OA of the knee, 2 weeks of treatment with the lidocaine patch 5% significantly reduces the intensity of pain qualities as measured by all 4 NPS composite measures. Our results coincide with previously reported improvements in pain and physical function in the same patient population, as measured by the Western Ontario and McMaster Universities OA Index. Measuring the various qualities of pain appears to be a valid approach for assessing clinical outcomes in the treatment of OA pain. Pain measures such as the NPS can capture the multi-dimensional properties of a patient's pain experience and may offer clinicians the possibility to identify differential effects of analgesic treatments on various pain qualities associated with OA.

Synovial fluid nitric oxide levels in patients with knee osteoarthritis

Nitric oxide (NO) has an important role in the inflammatory arthropathies. This study investigated NO levels in the synovial fluid and plasma of patients with primary osteoarthritis (OA) of the knee. Twenty-seven cases with primary knee OA and 13 controls were recruited for the study. Nitrate/nitrite levels of synovial fluid and plasma were measured by Griess reaction, and interleukin-1 beta (IL-1 beta) levels were measured quantitatively by a sandwich immunoassay technique. We found a significant increase in the synovial fluid nitrate/nitrite levels in cases with primary OA of the knee compared to controls (50.26+/-23.63 microg/l vs 32.49+/-10.05 microg/l, p=0.002) as well as increased plasma nitrate/nitrite levels (57.06+/-23.32 microg/l vs 39.98+/-16.36 microg/l, p=0.012). There was no difference in plasma and synovial fluid IL-1 beta concentrations between the study and control groups. These results may be considered as supporting evidence that NO might be one of the factors responsible for cartilage destruction in primary osteoarthritis of the knee.

Magnetic resonance evaluation of the disk before and after arthroscopic surgery for temporomandibular joint disorders

OBJECTIVE

The purposes of this study were (1) to assess functional and pain outcomes after arthroscopic surgery on patients with temporomandibular joint disorders (TMD); (2) to evaluate postsurgical changes in disk position, mobility, and morphology on magnetic resonance imaging (MRI); and (3) to measure the association between changes in disk position, mobility, and morphology on MRI and clinical outcomes.

STUDY DESIGN

A retrospective analysis was conducted of temporomandibular joints with internal derangement and osteoarthritis that were refractory to nonsurgical treatments and underwent arthroscopic surgery and on which MRI was performed within 1 month after the initial visit and 1 year after arthroscopic surgery. Clinical findings were assessed on the basis of mandibular range of motion and joint pain level on a visual analog scale at the initial visit and 1 year after arthroscopic surgery. The disk position, mobility, and morphology on MRI were compared with clinical findings and were statistically analyzed before and after arthroscopic surgery. The treatment outcome was judged according to our success criteria. The associations between changes in disk position, mobility, and morphology and clinical outcomes after arthroscopic surgery were statistically analyzed.

RESULTS

Forty-three joints of 43 patients who underwent arthroscopic surgery were assessed in this study. After arthroscopic surgery, mandibular range of motion and visual analog scale results improved statistically. According to the criteria for clinical resolution, 32 surgeries were successful and 11 were unsuccessful. Preoperative and postoperative MRI showed that most joints had anterior disk displacement (ADD) without reduction. Postoperative MRI revealed that, statistically, the number of mobile disks had increased and deformity of the disks had progressed. In the successful group, postoperative MRI revealed that all joints had mobile disks. In both groups, most joints had ADD without reduction before and after arthroscopic surgery, and, statistically, deformity of the disks progressed after arthroscopic surgery.

CONCLUSIONS

Arthroscopic surgery was an effective treatment for TMD refractory to nonsurgical treatments. This study provides important information of clinical significance. Disk position remained ADD without reduction, disk mobility increased, and deformity of the disks progressed after arthroscopic surgery.

Inducible nitric oxide synthase and apoptosis-related factors in the synovial tissues of temporomandibular joints with internal derangement and osteoarthritis

PURPOSE

In this study, we investigated the relationship between oxidative stress and apoptosis in synovial tissues in temporomandibular joint diseases (TMDs), including internal derangement (ID) and osteoarthritis (OA), comparing immunohistochemical, arthroscopic, and histologic findings.

MATERIALS AND METHODS

Synovial specimens obtained from patients with ID (31 patients), osteoarthritis (11 patients), and condylar fractures of the mandible (5 patients) during arthroscopy were examined immunohistochemically using antibodies against CD68, inducible nitric oxide synthase (iNOS), Fas, and single-stranded DNA (ssDNA).

RESULTS

CD68 and iNOS immunoreactivity were detected mainly in synovial lining cells and subintimal macrophages, and tended to increase with synovial hyperplasia. Fas and ssDNA immunoreactivity was detected mainly in synovial lining cells, and Fas-positive regions exhibited a number of ssDNA-positive cells. Fas expression was significantly greater in fractures than in OA, and ssDNA expression was significantly greater in OA than in ID. Fas expression was significantly greater in iNOS-positive versus iNOS-negative TMJs, and ssDNA expression tended to increase with iNOS expression.

CONCLUSION

These immunohistochemical findings suggest that oxidative stress and apoptosis in synovial tissues are involved in the onset and progression of TMDs.

Specific expression of inducible nitric oxide synthase in the synovium of the diseased temporomandibular joint

OBJECTIVE

The expression of inducible nitric oxide synthase (iNOS) in temporomandibular joint (TMJ) specimens obtained arthroscopically from diseased TMJs was investigated by using immunohistochemistry and compared with clinical, arthroscopic, and histologic findings.

STUDY DESIGN

Synovial biopsies were obtained arthroscopically from 18 TMJs in 15 patients with symptomatic internal derangement (ID) or osteoarthritis (OA). We also obtained arthroscopic biopsies from 8 control TMJs (3 with habitual luxation of the mandible, one with ID with clicking, and 4 with mandibular condyle fractures). The expression of iNOS was examined by immunohistochemistry and was compared with clinical, arthroscopic, and histologic findings.

RESULTS

Definite or intense iNOS immunoreactivity was observed in both the synovial lining cells and the endothelial cells of TMJs with symptomatic ID or OA. Weaker immunoreactivity was present in synovial fibroblasts. In contrast, in TMJs without synovitis (eg, those with habitual luxation of the mandible) the expression of iNOS was weak or marginal. The expression of iNOS correlated significantly with arthroscopic evidence of synovitis (r = 0.406, P <.05) but not with cartilaginous degeneration (P >.05). The expression of iNOS also correlated with the histologic grade of the synovial lining cell layers (r = 0.530, P <.05). However, in patients with ID or OA of the TMJ, there was no statistically significant correlation between the intensity of iNOS immunoreactivity and clinical, arthroscopic, or histologic findings (P >.05).

CONCLUSION

These data clearly suggest that nitric oxide is locally produced in the synovial lining of the TMJ in ID and OA.

Changes in the reducing power of synovial fluid from temporomandibular joints with "anchored disc phenomenon"

PURPOSE

In this study, we examined the hypothesis that uncontrolled oxidative stress causes collapse of the lubrication system, which is considered a major initiator of temporomandibular joint (TMJ) dysfunction. The oxidative stress was evaluated by measuring the overall antioxidant capacity of the low-molecular-weight antioxidants in the TMJ, using cyclic voltammetry (CV), in synovial fluid from normal and anchored disc phenomenon (ADP) TMJs.

MATERIALS AND METHODS

Synovial fluids samples were taken from 13 normally functioning and 33 ADP TMJs. The samples were frozen initially on collection and analyzed in CV to measure their overall reducing power.

RESULTS

CV measurements of the fluids collected from 90% of the healthy joints showed an anodic waves at peak potential [Ep(a)1/2] of 290 +/- 30 mV. Of the samples 56% showed another wave at 650 +/- 100 mV. These waves were generally absent in the fluid collected from ADP TMJs, but 2 new waves at 465 +/- 90 mV and greater than 750 mV were detected in 68% and 87% of the patients, respectively.

CONCLUSIONS

The results show more anodic waves, most of which of higher potentials (greater than 750 mV) in ADP TMJs, indicating that the capacity to cope with oxidative stress is lower in these joints. It is not clear whether this is due to absence of low-molecular-weight antioxidants or their consumption by uncontrolled production of reactive oxygen species, which might be the initial step in the collapse of the lubrication system.

The role of nitric oxide in nociception

Pharmacologic, electrophysiologic, and immunohistochemical studies have suggested a role of nitric oxide (NO) in nociception processing. Recent studies have indicated that NO may modulate spinal and sensory neuron excitability through multiple mechanisms that may underlie its distinctive roles in different pain states. Differential regulation of a family of NO-producing enzymes, NO synthases, contributes mainly to the complexity underlying the role of NO in nociception. This review summarizes the latest advances in our understanding of the contribution of NO to pain transduction. Possible cellular mechanisms regarding the connection between NO production and the abnormal sensation derived from different stimuli and pathologic conditions are discussed.

Immunohistochemical localization of inducible nitric oxide synthase in synovial tissue of human temporomandibular joints with internal derangement

The expression and distribution of inducible nitric oxide synthase (iNOS) was examined in 12 samples of human temporomandibular joint (TMJ) with internal derangement (ID) and four control specimens. In the diseased joints, strong or definite iNOS reactivity was expressed in synovial lining and endothelial cells; weaker activity was present in synovial fibroblasts. In contrast, although there was weak expression of iNOS in synovial fibroblasts and endothelial cells in the two control specimens, there was no iNOS staining in the synovial lining cell layers. This original report that iNOS is expressed in the synovial tissue of the temporomandibular joint indicates that nitric oxide is produced locally at least in the synovial lining in these joints when affected by internal derangement.