DREAMing about arthritic pain

Adhesive Capsulitis of the Ankle (Frozen Ankle): An Infrequent Syndrome

Adhesive capsulitis, characterized by progressive fibrosis, causes a gradual, painful loss of both active and passive articular motion, leading to the final contracture of the joint capsule. The condition commonly referred to as "frozen ankle" (FA), which Goldman was the first to use, relates to the ankle joint and is challenging to both diagnose and treat. Data acquired from people who suffer from this type of damage in other joints such as the shoulder, hip, and wrist also exists. Despite the fact that a well-defined model for the medical management of FA does not exist, a wide spectrum of local treatments, both surgical and non-surgical, exist. This review gives an overview of the current scientific position of the frozen ankle in terms of evolutionary factors, etiology, the different mechanisms of action involved, current treatment options, and other possible interventions based on recent discoveries of pathophysiological mechanisms. The application of extracorporeal shockwave therapy, stretching exercises, and corticosteroid injections combined with physical therapy modalities that enhance pain management, range of motion, and functional capacity is highly advisable for the treatment of adhesive capsulitis, commonly known as "frozen joints". Furthermore, the addition of interventions both impacting and analyzing chronic hypoxia, low-grade inflammation, and sedentary life is proposed.

Dynorphin participates in interaction between depression and non-erosive reflux disease

BACKGROUND

To explore the relationships between anxiety/depression and NERD, we focused on dynorphin (Dyn), an important member of visceral hypersensitivity, and its related pathways.

METHODS

Pearson's correlation analysis on patients with NERD and in vivo experiment on NERD rat model. Part 1: Pearson's correlation analysis among serum levels of Dyn, clinical symptoms and HADS scores of NERD patients were carried on. Part 2: Wistar rats were randomly divided into 2 groups: control group and model group. The data of pH value, immobility time, serum Dyn concentration, NMDAR1 and SP expression were, respectively, derived from automatic pH recorder, tail suspension test, enzyme-linked immunosorbent assay, immunohistochemistry and immunofluorescence.

RESULTS

Part 1: Pearson's correlation analysis showed that there was a linear correlation between Clinical Symptom (CS) score and HADS score (HAD-A, HAD-D), and the correlation coefficients were 0.385 and 0.273 respectively; the correlation coefficient between lg (Dyn) and lg (CS score) was r = 0.441, P = 0.002; the correlation coefficient between lg(Dyn) and lg (HAD-D score) was r = 0.447, P = 0.002. Part 2: The pH value of the lower esophagus in the model group was lower than that in the control group (P < 0.01). The tail suspension immobility time of model group was significantly longer than that of control group (P < 0.01). The serum Dyn concentration and the expression level of NMDAR1 in spinal cord and SP in lower esophageal mucosa of model group were significantly higher than those of control group (P < 0.05).

CONCLUSION

Increased serum dynorphin level may be a sign of correlation between depression and NERD.

A Comprehensive View of Frozen Shoulder: A Mystery Syndrome

Frozen shoulder is a common epidemiological affliction. Data acquired from people who suffer from this type of damage in other joints such as the hip, wrist and ankle also exist; although these syndromes are less common. Treatment for frozen shoulder is primarily physical (physiotherapy, manual therapy), secondary medical (corticosteroid injections) and finally surgical but with limited success. The difficulty in treating this type of condition successfully lies in the lack of knowledge about the risk factors involved and the pathophysiology underlying this mysterious syndrome. This review gives an overview of the current scientific position of frozen shoulder in terms of evolutionary factors, etiology, the different mechanisms of action involved, current treatment options and other possible interventions based on recent discoveries of pathophysiological mechanisms. The overall objective is to clarify several unknown aspects of a syndrome that affects up to 5% of the world's population.

A20: a master regulator of arthritis

A20, also known as TNF-α-induced protein 3 (TNFAIP3), is an anti-inflammatory protein that plays an important part in both immune responses and cell death. Impaired A20 function is associated with several human inflammatory and autoimmune diseases. Although the role of A20 in mediating inflammation has been frequently discussed, its intrinsic link to arthritis awaits further explanation. Here, we review new findings that further demonstrate the molecular mechanisms through which A20 regulates inflammatory arthritis, and we discuss the regulation of A20 by many factors. We conclude by reviewing the latest A20-associated mouse models that have been applied in related research because they reflect the characteristics of arthritis, the study of which will hopefully cast new light on anti-arthritis treatments.

TDAG8 deficiency reduces satellite glial number and pro-inflammatory macrophage number to relieve rheumatoid arthritis disease severity and chronic pain

Background

The autoimmune disease rheumatoid arthritis (RA) affects approximately 1% of the global population. RA is characterized with chronic joint inflammation and often associated with chronic pain. The imbalance of pro-inflammatory and anti-inflammatory macrophages is a feature of RA progression. Glial cells affecting neuronal sensitivity at both peripheral and central levels may also be important for RA progression and associated pain. Genetic variants in the T cell death-associated gene 8 (TDAG8) locus are found to associate with spondyloarthritis. TDAG8 was also found involved in RA disease progression and associated hyperalgesia in the RA mouse model. However, its modulation in RA remains unclear.

Methods

To address this question, we intra-articularly injected complete Freund’s adjuvant (CFA) into TDAG8^+/+, TDAG8^−/− or wild-type mice, followed by pain behavioral tests. Joints and dorsal root ganglia were taken, sectioned, and stained with antibodies to observe the number of immune cells, macrophages, and satellite glial cells (SGCs). For compound treatments, compounds were intraperitoneally or orally administered weekly for 9 consecutive weeks after CFA injection.

Results

We demonstrated that TDAG8 deletion slightly reduced RA pain in the early phase but dramatically attenuated RA progression and pain in the chronic phase (> 7 weeks). TDAG8 deletion inhibited an increase in SGC number and inhibition of SGC function attenuated chronic phase of RA pain, so TDAG8 could regulate SGC number to control chronic pain. TDAG8 deletion also reduced M1 pro-inflammatory macrophage number at 12 weeks, contributing to the attenuation of chronic RA pain. Such results were further confirmed by using salicylanilide derivatives, CCL-2d or LCC-09, to suppress TDAG8 expression and function.

Conclusions

This study demonstrates that TDAG8 deletion reduced SGC and M1 macrophage number to relieve RA disease severity and associated chronic pain. M1 macrophages are critical for the development and maintenance of RA disease and pain, but glial activation is also required for the chronic phase of RA pain.

A Review on Chronic Pain in Rheumatoid Arthritis: A Focus on Activation of NR2B Subunit of N-Methyl-D-Aspartate Receptors

Chronic pain is a debilitating condition that occurs after tissue damage, which substantially affects the patient's emotional state and physical activity. The chronic pain in rheumatoid arthritis (RA) is the result of various autoimmune-induced inflammatory reactions in the joints. Both types of peripheral and central pain processing can lead to sensitisation. Non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs (DMARDs) can result in potent anti-inflammatory effect. However, these drugs are not able to suppress the pain from RA for a prolonged period. For years, researchers have examined the role of the N-methyl-D-aspartic acid receptor 2B (NR2B) subunit of N-methyl-D-aspartate receptors (NMDAR) in chronic and neuropathic pain models. This NMDAR subtype can be found in at the peripheral and central nervous system and it represents an effective therapy for RA pain management. This review focuses on the NR2B subunit of NMDAR and the different pathways leading to its activation. Furthermore, specific attention is given to the possible involvement of NR2B subunit in the peripheral and central pathogenesis of RA.

Association between pain phenotype and disease activity in rheumatoid arthritis patients: a non-interventional, longitudinal cohort study

BACKGROUND

In well-controlled rheumatoid arthritis (RA) without significant joint damage, a substantial proportion of patients complain of persistent pain. Previous studies have identified different pain phenotypes in RA, in which non-nociceptive pain phenotypes are associated with higher concurrent disease activity scores. In this longitudinal study, we explored associations between pain phenotypes and long-term disease activity outcome in RA patients. Secondly, we explored whether pain phenotype is associated with comorbid conditions.

METHODS

One hundred eighty established RA patients were classified with a nociceptive (61%) or a non-nociceptive (39%) pain phenotype, based on their responses to the painDETECT-questionnaire. Two years of clinical follow-up data on disease activity outcomes were collected. Information on comorbid diseases was derived from electronic patient files.

RESULTS

Patients with a non-nociceptive pain phenotype showed higher mean disease activity scores (DAS28, 2.57; 95% CI, 2.37-2.77 vs. 2.11; 95% CI, 1.94-2.27; p < 0.001) and a twofold lower chance of achieving sustained DAS28 remission (OR = 0.49; 95% CI, 0.26-0.92; p = 0.020). Only the tender joint count and patient global health significantly differed between the pain phenotype groups. Patients with a non-nociceptive pain phenotype had more often been diagnosed with concurrent fibromyalgia (9.9% vs. 0.9%; p = 0.007) and other pain-associated comorbid diseases (52.1% vs. 35.8%; p = 0.030) compared with patients with a nociceptive pain phenotype.

CONCLUSION

This longitudinal study showed consistently worse long-term disease activity outcomes in RA patients with a non-nociceptive pain phenotype which appeared to be mainly due to differences in the subjective components of the disease activity score.

TRIAL REGISTRATION

The DREAM cohort study is registered in the Netherlands Trial Register: NTR578.

Biopharmaceutical Process of Diclofenac Multi-particulate Systems for Chronotherapy of Rheumatoid Arthritis

Objectives

Diclofenac exhibits limited solubility, low bioabsorption and gastric toxicity. The objective of the study was to address the above limitations and to design a multi-particulate formulation for the chronotherapy of RA.

Materials and Methods

Solid dispersions of DC with SSG and GG were prepared. Uniform-sized (∼400 µm) non-pareil seeds were coated with solid dispersions to produce immediate-release pellets (DMP-1 and DMP-2) and controlled-release pellets (DMP-3 and DMP-4). The resultant controlled-release pellets were further layered with methacrylate polymers to obtain pulsatile-release pellets (DMPP). Solubility, FTIR, DSC, micrometrics, SEM, drug content, drug release, pharmacokinetics, and stability studies were performed for DMPP.

Results

The solubility of DC was improved by 164-folds due to the presence of hydrophilic carriers in the solid dispersions. No chemical and physical interactions were noticed in FTIR spectra and also in thermograms. A fluidized bed processor facilitated the production of high-quality, circular, and regular pellets with an angle of repose less than 19.5 degrees and DC content between 95.18% and 98.87%. The maximum drug was released from DMPP at the end of 12 hours. DMP-1 and DMP-2 pellets had 2 hr of drug release and pulsatile, controlled-release pellets had a 6 hr lag phase followed by 12 hr controlled release. Both DMP-1 and DMP-2-immediate showed first-order release followed by Hixson-Crowell kinetics, whereas DMPP pellets followed zero-order release with Higuchi's kinetics. The maximum concentration of DC in plasma was 400.8 ng/mL at 5 hr for DMP-2 and 381.1 ng/mL at 14 hr for DMPP-5. The solubility of DC was increased with the application of solid dispersion and in turn increased the pharmacokinetics. The pellets were plausibly stable over a period of 90 days.

Conclusion

Thus, multi-particulate pulsatile systems of DC were as effective as chronotherapeutics in the treatment of circadian rhythm-based ailments such as RA.

A store-operated calcium channel inhibitor attenuates collagen-induced arthritis

BACKGROUND AND PURPOSE

Store-operated calcium (SOC) channels are thought to play a critical role in immune responses, inflammatory diseases and chronic pain. The aim of this study was to explore the potential role and mechanisms of SOC channels in collagen-induced arthritis (CIA).

EXPERIMENTAL APPROACH

The CIA mouse model was used to examine the effects of the SOC channel inhibitor YM-58483 on CIA and arthritic pain. Hargreaves' and von Frey hair tests were conducted to measure thermal and mechanical sensitivities of hind paws. elisa was performed to measure cytokine production, and haematoxylin and eosin staining was used to assess knee histological changes. Western blot analysis was performed to examine protein levels.

KEY RESULTS

Pretreatment with 5 or 10 mg · kg(-1) of YM-58483 reduced the incidence of CIA, prevented the development of inflammation and pain hypersensitivity and other signs and features of arthritis disease. Similarly, treatment with YM-58483 after the onset of CIA: (i) reversed the clinical scores; (ii) reduced paw oedema; (iii) attenuated mechanical and thermal hypersensitivity; (iv) improved spontaneous motor activity; (v) decreased periphery production of IL-1β, IL-6 and TNF-α; and (vi) reduced spinal activation of ERK and calmodulin-dependent PKII (CaMKIIα).

CONCLUSIONS AND IMPLICATIONS

This study provides the first evidence that inhibition of SOC entry prevents and relieves rheumatoid arthritis (RA) and arthritic pain. These effects are probably mediated by a reduction in cytokine levels in the periphery and activation of ERK and CaMKIIα in the spinal cord. These results suggest that SOC channels are potential drug targets for the treatment of RA.

Neuronal calcium signaling in chronic pain

Acute physiological pain, the unpleasant sensory response to a noxious stimulus, is essential for animals and humans to avoid potential injury. Pathological pain that persists after the original insult or injury has subsided, however, not only results in individual suffering but also imposes a significant cost on society. Improving treatments for long-lasting pathological pain requires a comprehensive understanding of the biological mechanisms underlying pain perception and the development of pain chronicity. In this review, we aim to highlight some of the major findings related to the involvement of neuronal calcium signaling in the processes that mediate chronic pain.

Pain treatment in arthritis-related pain: beyond NSAIDs

Managing pain from chronic conditions, such as, but not limited to, osteoarthritis and rheumatoid arthritis, requires the clinician to balance the need for effective analgesia against safety risks associated with analgesic agents. Osteoarthritis and rheumatoid arthritis pain is incompletely understood but involves both nociceptive and non-nociceptive mechanisms, including neuropathic mechanisms. Prevailing guidelines for arthritis-related pain do not differentiate between nociceptive and non-nociceptive pain, sometimes leading to recommendations that do not fully address the nature of pain. NSAIDs are effective in treating the nociceptive arthritis-related pain. However, safety concerns of NSAIDs may cause clinicians to undertreat arthritis-related pain. In this context, combination therapy may be more appropriate to manage the different pain mechanisms involved. A panel convened in November 2010 found that among the currently recommended analgesic products for arthritis-related pain, fixed-low-dose combination products hold promise for pain control because such products allow lower doses of individual agents resulting in decreased toxicity and acceptable efficacy due to synergy between the individual drugs. Better evidence and recommendations are required to improve treatment of chronic arthritis-related pain.

DREAM is reduced in synovial fibroblasts of patients with chronic arthritic pain: is it a suitable target for peripheral pain management?

Introduction

The endogenous pain-relieving system depends in part on the regulation of nociceptive signals through binding of opioids to the corresponding opioid receptor. Interfering with the trans-repression effect of downstream regulatory element antagonist modulator (DREAM) on the transcription of the opioid dynorphin-encoding prodynorphin (pdyn) gene might enhance pain relief in the periphery.

Methods

Expression levels were measured in osteoarthritis (OA) synovial fibroblast-like cells (SFLCs) (n = 8) and in peripheral blood mononuclear cells (PBMCs) from OA patients (n = 53) and healthy controls (n = 26) by real-time polymerase chain reaction. Lysed OA SFLCs were analyzed by immunoprecipitation. Translation of DREAM mRNA was inhibited by small interfering RNAs (siRNAs). Expressions of DREAM, pdyn, and c-fos mRNAs were measured at 24, 48, and 72 hours after transfection.

Results

The expression of DREAM mRNA was shown in both healthy and OA SFLCs as well as PBMCs. Inhibiting transcription using siRNAs led to a marked reduction in DREAM expression after 24, 48, and 72 hours. However, no significant changes in c-fos and pdyn expression occurred. In addition, DREAM mRNA expression was significantly reduced in OA patients with chronic pain (pain intensity as measured by a visual analog scale scale of greater than 40), but no pdyn expression was detectable.

Conclusion

To our knowledge, this is the first report showing the expression of DREAM in SFLCs and PBMCs on the mRNA level. However, DREAM protein was not detectable. Since repression of pdyn transcription persists after inhibiting DREAM translation, DREAM appears to play no functional role in the kappa opioid receptor system in OA SFLCs. Therefore, our data suggest that DREAM appears not to qualify as a target in peripheral pain management.