Percutaneously absorbed NSAIDs attenuate local production of proinflammatory cytokines and suppress the expression of c-Fos in the spinal cord of a rodent model of knee osteoarthritis

Medical Cannabis Use and Inflammatory Cytokines and Chemokines Among Adult Chronic Pain Patients

Background: Utilizing cannabis as a therapeutic option for chronic pain (CP) has increased significantly. However, data regarding the potential immunomodulatory effects of cannabis in CP patients remain scarce. We aimed at exploring the relationship between cannabis use and inflammatory cytokines and chemokines among a cohort of CP patients. Methods: Adult patients with a CP diagnosis and medical authorization of cannabis were enrolled. Patients completed validated clinical questionnaires and self-reported the effectiveness of cannabis for symptom management. Patients' blood and cannabis samples were analyzed for the presence of four major cannabinoids, two major cannabinoid metabolites, 29 different cytokines/chemokines, and cortisol. The multivariable linear regression model was used to identify cannabis and patient factors associated with immune markers. Results: Fifty-six patients (48±15 years; 64% females) were included, with dried cannabis (53%) being the most common type of cannabis consumed. Seventy percent of products were considered delta-9-tetrahydrocannabinol (Δ9-THC)-dominant. The majority of patients (96%) self-reported effective pain management, and 76% reported a significant decrease in analgesic medication usage (p≤0.001). Compared with males, female patients had higher plasma levels of cannabidiol (CBD), cannabidiolic acid, Δ9-THC, and 11-hydroxy-Δ9-tetrahydrocannabinol but lower concentrations of delta-9-tetrahydrocannabinolic acid and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). Females had significantly lower eotaxin levels (p=0.04) in comparison to male patients. The regression analysis indicated that high cannabis doses were related to increased levels of interleukin (IL)-12p40 (p=0.02) and IL-6 (p=0.01), whereas female sex was associated with decreased eotaxin (p≤0.01) concentrations. Blood CBD levels were associated with lower vascular endothelial growth factor (p=0.04) concentrations, and THC-COOH was a factor related to decreased tumor necrosis factor alpha (p=0.02) and IL-12p70 (p=0.03). Conclusion: This study provides further support for the patient-perceived effectiveness of cannabis in managing CP symptoms and reducing analgesic medication consumption. The results suggest a potential sex difference in metabolizing cannabinoids, and the varying immune marker concentrations may support a possible immunomodulatory effect associated with patient sex and cannabis product type. These preliminary findings provide grounds for further validation using larger, well-designed studies with longer follow-up periods.

Biodegradable Polymers-Based Smart Nanocrystals for Loxoprofen Delivery with Enhanced Solubility: Design, Fabrication and Physical Characterizations

Nanocrystals are carrier-free, submicron-sized, colloidal drug delivery systems with particle sizes in the mean nanometer range. Nanocrystals have high bioavailability and fast absorption because of their high dissolution velocity and enhanced adhesiveness to cell membranes. Loxoprofen, a nonsteroidal anti-inflammatory drug belonging to the Biopharmaceutical Classification System (BCS) II drug class, was selected as the model drug. The aim of this study was to formulate nanocrystals of loxoprofen. A total of 12 formulations (F1 to F12) were prepared. An antisolvent technique was used to determine the effects of various stabilizers and processing conditions on the optimization of formulations. The various stabilizers used were hydroxypropyl methylcellulose (0.5%), polyvinylpyrrolidone (0.5%), and sodium lauryl sulfate (0.1%). The various characterizations conducted for this research included stability studies at 25 °C and 4 °C, scanning electron microscopy, transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), zeta potentials, polydispersity indexes, and dissolution studies. F10 was the optimized formulation that showed stability at room temperature, as well as at a refrigerated temperature, for 30 days. A high dissolution rate (100% within the first 10 min) was shown by comparative dissolution studies of nano-suspensions with the micro-suspension and raw loxoprofen. F10 formulation had a non-porous and crystalline morphology on evaluation by TEM and XRPD, respectively, and the average particle size was 300 ± 0.3 nm as confirmed by TEM. DSC recorded a reduction in the melting point (180 °C processed and 200 °C unprocessed melting points). The dissolution rate and solubility of the formulated loxoprofen nanocrystals were significantly enhanced. It can be concluded that selecting suitable stabilizers (i.e., polymers and surfactants) can produce stable nanocrystals, and this can potentially lead to a scaling up of the process for commercialization.

Osteoarthritis Pain

Joint pain is the hallmark symptom of osteoarthritis (OA) and the main reason for patients to seek medical assistance. OA pain greatly contributes to functional limitations of joints and reduced quality of life. Although several pain-relieving medications are available for OA treatment, the current intervention strategy for OA pain cannot provide satisfactory pain relief, and the chronic use of the drugs for pain management is often associated with significant side effects and toxicities. These observations suggest that the mechanisms of OA-related pain remain undefined. The current review mainly focuses on the characteristics and mechanisms of OA pain. We evaluate pathways associated with OA pain, such as nerve growth factor (NGF)/tropomyosin receptor kinase A (TrkA), calcitonin gene-related peptide (CGRP), C–C motif chemokine ligands 2 (CCL2)/chemokine receptor 2 (CCR2) and tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), the NOD-like receptor (NLR) family, pyrin domain-containing protein 3 (NLRP3) inflammasome, and the Wnt/β-catenin signaling pathway. In addition, animal models currently used for OA pain studies and emerging preclinical studies are discussed. Understanding the multifactorial components contributing to OA pain could provide novel insights into the development of more specific and effective drugs for OA pain management.

Evaluation of Sustained Acoustic Medicine for Treating Musculoskeletal Injuries in Military and Sports Medicine

Background

Musculoskeletal injuries are common in collegiate, professional, and military personnel and require expedited recovery to reduce lost work time. Sustained acoustic medicine (SAM) provides continuous long-duration ultrasound at 3MHz and 132mW/cm². The treatment is frequently prescribed to treat acute and chronic soft tissue injuries and reduce pain. The objective of this study was to evaluate the efficacy of SAM treatment for musculoskeletal injuries and accelerated recovery.

Methods

An 18-question electronic survey and panel discussion were conducted on Athletic Trainers (ATs) using SAM treatment in professional, collegiate, and military sports medicine. The survey included both qualitative and quantitative questions. In addition, a panel discussion discussed SAM effectiveness with expert ATs. Power calculation of sampling and statistical evaluation of data was utilized to generalize the results.

Results

Survey respondents (n=97) and panelists (n=142) included ATs from all National Athletic Trainers Association districts. SAM was primarily used for musculoskeletal injuries (83.9%, p<0.001) with a focus on healing tendons and ligaments (87.3%, p<0.001). SAM treatment was also used on joints (44.8%), large muscle groups (43.7%), and bone (41.4%). SAM provided clinical improvement in under 2 weeks (68.9%, p<0.001) and a 50% reduction in pain medication (63%, p<0.001). In addition, patients were highly receptive to treatment (87.3%, p<0.001), and ATs had a high level of confidence for improved function and returned to work after 30-days of SAM use (81.2%, p<0.001).

Conclusion

SAM is an effective, safe, easy-to-use, noninvasive, comfortable, and versatile therapeutic for healing musculoskeletal injuries.

Examining the role of transient receptor potential canonical 5 (TRPC5) in osteoarthritis

Introduction

Osteo-arthritis (OA) involves joint degradation and usually pain; with mechanisms poorly understood and few treatment options. There is evidence that the transient receptor potential canonical 5 (TRPC5) mRNA expression is reduced in OA patients’ synovia. Here we examine the profile of TRPC5 in DRG and involvement in murine models of OA.

Design

TRPC5 KO mice were subjected to partial meniscectomy (PMNX) or injected with monoiodoacetate (MIA) and pain-related behaviours were determined. Knee joint pathological scores were analysed and gene expression changes in ipsilateral synovium and dorsal root ganglia (DRG) determined. c-Fos protein expression in the ipsilateral dorsal horn of the spinal cord was quantified.

Results

TRPC5 KO mice developed a discrete enhanced pain-related phenotype. In the MIA model, the pain-related phenotype correlated with c-Fos expression in the dorsal horn and increased expression of nerve injury markers ATF3, CSF1 and galanin in the ipsilateral DRG. There were negligible differences in the joint pathology between WT and TRPC5 KO mice, however detailed gene expression analysis determined increased expression of the mast cell marker CD117 as well as extracellular matrix remodelling proteinases MMP2, MMP13 and ADAMTS4 in MIA-treated TRPC5 KO mice. TRPC5 expression was defined to sensory subpopulations in DRG.

Conclusions

Deletion of TRPC5 receptor signalling is associated with exacerbation of pain-like behaviour in OA which correlates with increased expression of enzymes involved in extracellular remodelling, inflammatory cells in the synovium and increased neuronal activation and injury in DRG. Together, these results identify a modulating role for TRPC5 in OA-induced pain-like behaviours.

Sotrastaurin, a PKC inhibitor, attenuates RANKL-induced bone resorption and attenuates osteochondral pathologies associated with the development of OA

Osteoarthritis (OA) is a common degenerative disease that affects the musculoskeletal structure of the whole joint, which is characterized by progressive destruction of both articular cartilage and subchondral bone. Treatment of the bone pathologies, particularly osteoclast‐mediated subchondral bone loss in the early stages of OA, could prevent subsequent cartilage degeneration and progression of OA. In the present study, the PKC inhibitor, Sotrastaurin, was found to inhibit RANKL‐induced osteoclast formation in vitro in a dose‐ and time‐dependent manner. In particular, SO exerted its anti‐osteoclastic effect predominantly at the early stages of RANKL stimulation, suggesting inhibitory effects on precursor cell fusion. Using mature osteoclasts cultured on bovine bone discs, we showed that SO also exerts anti‐resorptive effects on mature osteoclasts bone resorptive function. Mechanistically, SO attenuates the early activation of the p38, ERK and JNK signalling pathways, leeding to impaired induction of crucial osteoclast transcription factors c‐Jun, c‐Fos and NFATc1. We also showed that SO treatment significantly inhibited the phosphorylation of PKCδ and MARCKS, an upstream regulator of cathepsin K secretion. Finally, in animal studies, SO significantly alleviates the osteochondral pathologies of subchondral bone destruction as well as articular cartilage degeneration following DMM‐induced OA, markedly improving OARSI scores. The reduced subchondral bone loss was associated with marked reductions in TRAP(+) osteoclasts in the subchondral bone tissue. Collectively, our data provide evidence for the protective effects of SO against OA by preventing aberrant subchondral bone and articular cartilage changes. Thus, SO demonstrates potential for further development as an alternative therapeutic option against OA.

Effects of nonsteroidal anti-inflammatory drugs on serum proinflammatory cytokines in the treatment of ankylosing spondylitis

Objective: This study was conducted to investigate the correlation between serum levels of proinflammatory cytokines and the clinical efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) in patients with ankylosing spondylitis (AS). Methods: A total of 148 patients with AS were selected and received NSAID treatment. ELISA was used to assess cytokine levels, and patients were assigned into the following groups: positively effective; effective; moderately effective; and ineffective. Spearman and Pearson correlation analyses were used for correlation analysis. Results: The erythrocyte sedimentation rates (ESR), C-reactive protein (CRP) levels, and immunoglobulin A (IgA) levels of the case group after NSAID treatment were markedly lower than those before NSAID treatment. After treatment, the levels of interleukin (IL)-6, IL-17, and tumor necrosis factor (TNF)-α were markedly reduced, while IL-10 levels increased in the positively effective, effective, and moderately effective groups, and IL-12 levels decreased in the positively effective and effective groups. In addition, the levels of IL-6 and TNF-α were correlated with a greater number in the efficacy indexes and clinical parameters, followed by IL-10 levels, while the levels of IL-17 and IL-12 had relatively weaker correlations with these indexes and parameters. Conclusion: NSAIDs could promote the clinical efficacy of treatment for ankylosing spondylitis by regulating serum levels of proinflammatory cytokines.

Assessment of pain-related behavior and pro-inflammatory cytokine levels in the rat rotator cuff tear model

The cause of pain following rotator cuff tear has not been fully elucidated. The purpose of this study was to evaluate behavior and inflammatory cytokines in a rat unstabilized rotator cuff defect (UCD) model. Forty-five Sprague-Dawley rats were divided into three groups: sham; UCD; and stabilized rotator cuff defect (SCD). Gait analysis was examined using CatWalk. Tumor necrosis factor (TNF)-α, interleukin(IL)-1β, and IL-6 were measured within the subacromial bursa and the glenohumeral joint synovium at 21 and 56 days after surgery using an enzyme-linked immunosorbent assay (ELISA). Stride length, print area and contact intensity in the UCD group was significantly lower than in the sham group after surgery. Stride length, print area and contact intensity in the SCD group was significantly higher than in the UCD group. In contrast, TNF-α, IL-1β, and IL-6 in the UCD group was significantly higher than in the sham group at days 21 and 56. However, TNF-α, IL-1β, and IL-6 in the SCD group was significantly lower than in the UCD group at days 21 and 56. The present results suggest that SCD is effective not only in improving shoulder function but also in reducing inflammatory cytokines, which may serve as one source of pain due to rotator cuff tear.

Osteoarthritis pain mechanisms: basic studies in animal models

OBJECTIVE

Osteoarthritis (OA) is a complex and painful disease of the whole joint. At present there are no satisfying agents for treating OA. To promote OA research and improved treatment, this review summarizes current preclinical evidence on the development of OA.

METHODS

Preclinical OA research was searched and key findings are summarized and commented.

RESULTS

Mechanisms of OA-associated pain have been studied in rodent knee OA models produced by intra-knee injection of the chondrocyte glycolytic inhibitor mono-iodoacetate (MIA), surgery, or spontaneous development in some species. These models are clinically relevant in terms of histological damage and functional changes, and are used to study mechanisms underlying mechanical, thermal, ambulatory, body weight supporting-evoked, and ongoing OA pain. Recent peripheral, spinal, and supraspinal biochemical and electrophysiological studies in these models suggest that peripheral pro-inflammatory mediators and neuropeptides sensitize knee nociceptors. Spinal cytokines and neuropeptides promote OA pain, and peripheral and spinal cannabinoids inhibit OA pain respectively through cannabinoid-1 (CB1) and CB1/CB2 receptors. TRPV1 and metalloproteinases contribute and supraspinal descending facilitation of 5-hydroxytryptamine (5-HT)/5-HT 3 receptors may also contribute to OA pain. Conditioned place preference tests demonstrate that OA pain induces aversive behaviors, suggesting the involvement of brain. During OA, brain functional connectivity is enhanced, but at present it is unclear how this change is related to OA pain.

CONCLUSION

Animal studies demonstrate that peripheral and central sensitization contributes to OA pain, involving inflammatory cytokines, neuropeptides, and a variety of chemical mediators. Interestingly, brainstem descending facilitation of 5-HT/5-HT3 receptors plays a role OA pain.