Cannabinoid WIN‑55,212‑2 mesylate inhibits ADAMTS‑4 activity in human osteoarthritic articular chondrocytes by inhibiting expression of syndecan‑1

Perceptions and Opinions on Cannabidiol in the Orthopaedic Sports Medicine Community

Background

Cannabidiol (CBD) is a known pain modulator that is garnering increased attention in the orthopaedic world. There may be a considerable knowledge gap among orthopaedic sports medicine providers and their perception of its therapeutic value.

Purpose

To (1) examine the knowledge and beliefs of sports medicine orthopaedic providers with respect to CBD, (2) deliver an educational component, and (3) elucidate potential barriers to its widespread application.

Study Design

Cross-sectional study.

Methods

A 3-component, 25-question online survey was distributed to members of the American Orthopaedic Society for Sports Medicine and the Arthroscopy Association of North America between July and October 2022. The first 20 questions assessed baseline knowledge and opinions regarding CBD, followed by an educational component, and then 5 questions assessing whether the respondents' opinions had changed after learning more about CBD. Responses were compared according to age, practice setting, and state's cannabinoid legalization status using the chi-square test, and changes in opinions from before to after the educational component were compared using the paired t test.

Results

There were 101 survey responses, for a response rate of approximately 1%. Most respondents believed that there is a role for CBD in postoperative pain management (76%), acute pain and inflammation after an injury (62%), and chronic pain (94%). Most respondents admitted that they were not knowledgeable about the mechanism of action (89%) or their state's laws (66%) concerning CBD. A minority (25%) believed that CBD has psychoactive properties. While most respondents (76%) did not believe that they would be stigmatized if they were to suggest CBD to a patient, only 48% had ever suggested CBD. Notably, 94% of respondents had encountered patients who reported trying CBD to treat pain. After reading the fact sheet, 51% of respondents stated that their opinion on CBD had changed, and 63% felt inclined to investigate the topic further.

Conclusion

Most survey respondents believed that CBD has a role in postoperative and chronic pain management. Although there was a relative familiarity with CBD, there was a knowledge gap, suggesting that increased attention, education, and research are necessary.

HU308 Mitigates Osteoarthritis by Stimulating Sox9-Related Networks of Carbohydrate Metabolism

Osteoarthritis (OA) is characterized by progressive, irreversible erosion of articular cartilage accompanied by severe pain and immobility. This study aimed to assess the effect and mechanism of action of HU308, a selective cannabinoid receptor type 2 (CB2) agonist, in preventing OA-related joint damage. To test the assumption that HU308 could prevent OA-related joint damage, Cnr2 null mice and wild type (WT) mice were aged to reach 20 months and analyzed for joint structural features. OA was induced in WT mice via a post-traumatic procedure or aging, followed by HU308 local (intra-articular) or systemic (intraperitoneal) administration, respectively. Additional analyses of time and dose courses for HU308 were carried out in human primary chondrocytes, analyzed by RNA sequencing, RT-PCR, chromatin immunoprecipitation, and immunoblotting. Our results showed that Cnr2 null mice exhibited enhanced age-related OA severity and synovitis compared to age-matched WT mice. Systemic administration of HU308 to 16-month-old mice improved pain sensitivity and maintained joint integrity, which was consistent with the intra-articular administration of HU308 in post-traumatic OA mice. When assessing human chondrocytes treated with HU308, we uncovered a dose- and time-related increase in ACAN and COL2A1 expression, which was preceded by increased SOX9 expression due to pCREB transcriptional activity. Finally, transcriptomic analysis of patient-derived human chondrocytes identified patient subpopulations exhibiting HU308-responsive trends as judged by enhanced SOX9 expression, accompanied by enriched gene networks related to carbohydrate metabolism. Collectively, the results showed that HU308 reduced trauma and age-induced OA via CB2-pCREB dependent activation of SOX9, contributing to augmented gene networks related to carbohydrate metabolism. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Cannabis for Rheumatic Disease Pain: a Review of Current Literature

PURPOSE OF REVIEW

Changing attitudes about marijuana have led to an increase in use of medicinal marijuana, especially for painful chronic conditions. Patients ask rheumatologists for guidance on this topic. This review provides up-to-date information on the safety and efficacy of medicinal cannabis for rheumatic disease pain.

RECENT FINDINGS

The number of publications related to rheumatic disease and cannabis has increased, but recent literature skews heavily toward reviews vs primary research. Data supporting a role for cannabinoids in rheumatic disease continue to grow. Observational and survey studies show increased use of medicinal cannabis, both by people with rheumatic disease and the general population, and suggest that patients find these treatments beneficial. Prospective studies, however, including randomized controlled clinical trials, are rare and sorely needed. As medicinal cannabis use for rheumatic diseases rises, despite lack of evidence, we review the sparse data available and provide tips for conversations about medicinal cannabis for rheumatologists.

Interleukin-34 Reprograms Glycolytic and Osteoclastic Rheumatoid Arthritis Macrophages via Syndecan 1 and Macrophage Colony-Stimulating Factor Receptor

OBJECTIVE

In rheumatoid arthritis (RA), elevated serum interleukin-34 (IL-34) levels are linked with increased disease severity. IL-34 binds to 2 receptors, macrophage colony-stimulating factor receptor (M-CSFR) and syndecan 1, which are coexpressed in RA macrophages. Expression of both IL-34 and syndecan 1 is strikingly elevated in the RA synovium, yet their mechanisms of action remain undefined. This study was undertaken to investigate the mechanism of action of IL-34 in RA.

METHODS

To characterize the significance of IL-34 in immunometabolism, its mechanism of action was elucidated in joint macrophages, fibroblasts, and T effector cells using RA and preclinical models.

RESULTS

Intriguingly, syndecan 1 activated IL-34-induced M-CSFR phosphorylation and reprogrammed RA naive cells into distinctive CD14+CD86+GLUT1+ M34 macrophages that expressed elevated levels of IL-1β, CXCL8, and CCL2. In murine M34 macrophages, the inflammatory phenotype was accompanied by potentiated glycolytic activity, exhibited by transcriptional up-regulation of GLUT1, c-Myc, and hypoxia-inducible factor 1α (HIF-1α) and amplified pyruvate and l-lactate secretion. Local expression of IL-34 provoked arthritis by expanding the glycolytic F4/80-positive, inducible nitric oxide synthase (iNOS)-positive macrophage population, which in turn attracted fibroblasts and polarized Th1/Th17 cells. The cross-talk between murine M34 macrophages and Th1/Th17 cells broadened the inflammatory and metabolic phenotypes, resulting in the expansion of IL-34 pathogenicity. Consequently, IL-34-instigated joint inflammation was alleviated in RAG-/- mice compared to wild-type mice. Syndecan 1 deficiency attenuated IL-34-induced arthritis by interfering with joint glycolytic M34 macrophage and osteoclast remodeling. Similarly, inhibition of glycolysis by 2-deoxy-d-glucose reversed the joint swelling and metabolic rewiring triggered by IL-34 via HIF-1α and c-Myc induction.

CONCLUSION

IL-34 is a novel endogenous factor that remodels hypermetabolic M34 macrophages and facilitates their cross-regulation with T effector cells to advance inflammatory bone destruction in RA.

Cannabinoid-based therapy as a future for joint degeneration. Focus on the role of CB2 receptor in the arthritis progression and pain: an updated review

Over the last several decades, the percentage of patients suffering from different forms of arthritis has increased due to the ageing population and the increasing risk of civilization diseases, e.g. obesity, which contributes to arthritis development. Osteoarthritis and rheumatoid arthritis are estimated to affect 50-60% of people over 65 years old and cause serious health and economic problems. Currently, therapeutic strategies are limited and focus mainly on pain attenuation and maintaining joint functionality. First-line therapies are nonsteroidal anti-inflammatory drugs; in more advanced stages, stronger analgesics, such as opioids, are required, and in the most severe cases, joint arthroplasty is the only option to ensure joint mobility. Cannabinoids, both endocannabinoids and synthetic cannabinoid receptor (CB) agonists, are novel therapeutic options for the treatment of arthritis-associated pain. CB₁ receptors are mainly located in the nervous system; thus, CB₁ agonists induce many side effects, which limit their therapeutic efficacy. On the other hand, CB₂ receptors are mainly located in the periphery on immune cells, and CB₂ modulators exert analgesic and anti-inflammatory effects in vitro and in vivo. In the current review, novel research on the cannabinoid-mediated analgesic effect on arthritis is presented, with particular emphasis on the role of the CB₂ receptor in arthritis-related pain and the suppression of inflammation.

EZH2 is associated with cartilage degeneration in osteoarthritis by promoting SDC1 expression via histone methylation of the microRNA-138 promoter

Cartilage degeneration has been reported to deteriorate osteoarthritis (OA), a prevalent joint disease caused by intrinsic and epigenetic factors. This study aimed to examine the molecular mechanism of enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2)/microRNA-138 (miR-138)/syndecan 1 (SDC1) and its epigenetic regulation in cartilage degeneration in OA. An OA cell model was induced by stimulating chondrocytes with interleukin (IL)-1β at a final concentration of 10 ng/mL, followed by alterations in EZH2 and miR-138 expression. Afterwards, cell apoptosis was analyzed using flow cytometry. The expression patterns of cartilage catabolism-related factors (MMP-13, ADAMTS-4, and ADAMTS-5) were determined using RT-qPCR and western blot analyses. The EZH2 and H3K27me3 enrichment at the miR-138 promoter region were determined using ChIP-qPCR. Finally, an OA mouse model was constructed to verify the function of EZH2 in vivo. EZH2 was expressed at high levels in OA models. EZH2 depletion ameliorated OA, as evidenced by reduced cell apoptosis in IL-1β-treated chondrocytes and decreased levels of cartilage catabolism-related factors. Moreover, EZH2 promoted histone methylation at the miR-138 promoter to suppress miR-138 expression, thereby upregulating the expression of SDC1, a target gene of miR-138. Changes in this pathway increased the expression of cartilage catabolism-related factors in vitro while promoting cartilage degeneration in vivo. Our data provided evidence that EZH2 inhibits miR-138 expression by promoting the histone methylation of its promoter, which induces cartilage degeneration in OA models by upregulating SDC1 expression, suggesting a novel mechanistic strategy for OA treatment.

Knowledge and Opinion on Cannabinoids Among Orthopaedic Traumatologists

INTRODUCTION

Cannabinoids are an increasingly popular therapy among orthopaedic patients for musculoskeletal conditions. A paucity of evidence to support their use in orthopaedics exists, likely because of the incongruence of federal and state legalization and the stigma surrounding cannabis. The purpose of this study is to elucidate sentiments and knowledge base of the orthopaedic trauma community with regard to cannabinoid-containing compounds.

METHODS

A 21-question online survey was distributed to the members of the Orthopaedic Trauma Association with a response window of 3 months.

RESULTS

We evaluated 251 responses. Most (88%) of the respondents did not believe that they were knowledgeable about the mechanism of action of cannabis/cannabidiol (CBD) but did feel that cannabis or CBD products play a role in managing postoperative pain (73%). Most respondents did not believe that they would be stigmatized if they suggested CBD (83%) or cannabis (67%) to patients. Despite this, fewer respondents have suggested CBD (38%) or cannabis (29%) to their patients.

CONCLUSIONS

Sentiment toward cannabinoids among orthopaedic traumatologists is remarkably favorable; however, in-depth understanding is admittedly poor and routine use is uncommon. More clinical research for cannabinoids is needed to help orthopaedic traumatologists provide guidance for patients seeking advice for this recently popular therapeutic.

In Vitro Effects of Low Doses of β-Caryophyllene, Ascorbic Acid and d-Glucosamine on Human Chondrocyte Viability and Inflammation

β-caryophyllene (BCP), a plant-derived sesquiterpene, has been reported to have anti-inflammatory and antioxidant effects. The purpose of this study is to evaluate the effects of BCP in combination with ascorbic acid (AA) and d-glucosamine (GlcN) against macrophage-mediated inflammation on in vitro primary human chondrocytes. Changes in cell viability, intracellular ROS generation, gene expression of pro-inflammatory mediators, metalloproteinases (MMPs), collagen type II and aggrecan were analyzed in primary human chondrocytes exposed to the conditioned medium (CM) of activated U937 monocytes and subsequently treated with BCP alone or in combination with AA and GlcN. The CM-induced chondrocyte cytotoxicity was reduced by the presence of low doses of BCP alone or in combination with AA and GlcN. The exposure of cells to CM significantly increased IL-1β, NF-κB1 and MMP-13 expression, but when BCP was added to the inflamed cells, alone or in combination with AA and GlcN, gene transcription for all these molecules was restored to near baseline values. Moreover, chondrocytes increased the expression of collagen type II and aggrecan when stimulated with AA and GlcN alone or in combination with BCP. This study showed the synergistic anti-inflammatory and antioxidative effects of BCP, AA and GlcN at low doses on human chondrocyte cultures treated with the CM of activated U937 cells. Moreover, the combination of the three molecules was able to promote the expression of collagen type II and aggrecan. All together, these data could suggest that BCP, AA and GlcN exert a chondro-protective action.

Matrix Metalloproteinase-3 induces proteoglycan degradation in gouty arthritis model

BACKGROUND

Gout is an inflammatory arthritis resulting from precipitation of monosodium urate (MSU) crystals in joints and surrounding tissues. However, the mechanism underlying high levels of uric acid inducing gouty arthritis has not been clarified.

OBJECTIVE

The purpose was to investigate the role of Matrix Metalloproteinase-3 (MMP-3) in the development of gouty arthritis from hyperuricemia.

METHOD

MSU crystal-induced gouty arthritis model and chondrocytes were used to evaluate changes of MMP-3 levels. Western blot, qPCR and ELISA were performed to detect MMP-3, Tissue Inhibitors of Metalloproteinase-1 (TIMP-1) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs-4 (ADAMTS-4) expressions in rabbit chondrocytes. Expression of proteoglycan was determined through toluidine blue staining. Concentrations of glycosaminoglycan, Interleukin-6 (IL-6), Interleukin-1β (IL-1β) and Tumor Necrosis Factor-α (TNF-α) in chondrocytes were assessed via ELISA kits. Concentration of uric acid in supernate was tested by Automatic Analyzer.

RESULTS

MMP-3 was significantly increased in rat serum, synovial fluid, cartilages and chondrocytes treated with high-level uric acid. Increased concentration of glycosaminoglycancould be observed in chondrocytes incubated with MMP-3, as well as the remarkable downregulation of proteoglycan expression. Furthermore, high-level uric acid contributed to the degradation of proteoglycan via the activation of MMP-3. IL-6, IL-1β and TNF-α concentrations were increased significantly in 35 °C compared to 37 °C with MMP-3 and high-level uric acid.

CONCLUSION

Our study showed that MMP-3 was enhanced by high levels of uric acid, which promoted proteoglycan degradation, and induced MSU crystallization in turn. A low temperature environment is an important factor in the development of gout.

Cannabis and Cannabinoids in the Treatment of Rheumatic Diseases

Chronic pain is a common complaint among patients, and rheumatic diseases are a common cause for chronic pain. Current pharmacological interventions for chronic pain are not always useful or safe enough for long-term use. Cannabis and cannabinoids are currently being studied due to their potential as analgesics. In this review we will discuss current literature regarding cannabinoids and cannabis as treatment for rheumatic diseases. Fibromyalgia is a prevalent rheumatic disease that causes diffuse pain, fatigue, and sleep disturbances. Treatment of this syndrome is symptomatic, and it has been suggested that cannabis and cannabinoids could potentially alleviate some of the symptoms associated with fibromyalgia. In this review we cite some of the evidence that supports this claim. However, data on long-term efficacy and safety of cannabinoid and cannabis use are still lacking. Cannabinoids and cannabis are commonly investigated as analgesic agents, but in recent years more evidence has accumulated on their potential immune-modulatory effect, supported by results in animal models of certain rheumatic diseases. While results that demonstrate the same effect in humans are still lacking, cannabinoids and cannabis remain potential drugs to alleviate the pain associated with rheumatic diseases, as they were shown to be safe and to cause limited adverse effects.

Dose-Dependent Cannabidiol-Induced Elevation of Intracellular Calcium and Apoptosis in Human Articular Chondrocytes

Cannabidiol (CBD) is the most abundant non-psychoactive compound of Cannabis sativa extracts. Cannabinoids have been shown to exhibit anti-inflammatory, analgesic, antioxidant, neuroprotective, and anti-tumorigenic effects. In the present study, we investigated the effects of CBD on human articular chondrocytes. Cell viability was determined by Resazurin assays. Apoptosis was analyzed by annexin-V/7-actinomycin D (7-AAD) staining followed by flow cytometry. Caspase 3/7 activity was measured with caspase assays. Intracellular Ca²⁺ ([Ca²⁺ ]_i ) was monitored by time-lapse fluorescence imaging. The perforated whole-cell patch-clamp technique was used for measuring the cell membrane potential. Erk1/2 phosphorylation was assessed by western blot analysis. The chondrocyte cell line C28/I2 and primary chondrocytes showed a reduced viability after treatment with concentrations of CBD greater than 4 µM. This apoptotic effect was accompanied by an increase of caspase 3/7 activity and an increase in the early apoptotic cell population. CBD elevated [Ca²⁺ ]_i , which was accompanied by depolarization of the cell membrane potential. The increase of [Ca²⁺ ]_i was abrogated, when Ca²⁺ was omitted from the bath solution, indicating an influx of extracellular Ca²⁺ . The cannabinoid receptor 1 (CB1) antagonist AM251 inhibited the Ca²⁺ influx triggered by CBD. Preincubation with AM251 reduced the toxic effects of CBD. By looking for mediators of the apoptotic CBD effect downstream of the CB1 receptor, enhanced Erk1/2 phosphorylation could be detected after CBD treatment. However, this Erk1/2 activation proved to be unaffected by CB1 receptor blockage. The present study demonstrates that CBD promotes apoptosis and [Ca²⁺ ]_i elevation in human articular chondrocytes via a CB1-receptor-mediated mechanism. © 2019 The Authors. Journal of Orthopaedic Research^® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society J Orthop Res 37:2540-2549, 2019.

Protective effects of specific cannabinoid receptor 2 agonist GW405833 on concanavalin A-induced acute liver injury in mice

Cannabinoid receptor 2 (CB2R) is highly expressed in immune cells and plays an important role in regulating immune responses. In the current study, we investigated the effects of GW405833 (GW), a specific CB2R agonist, on acute liver injury induced by concanavalin A (Con A). In animal experiments, acute liver injury was induced in mice by injection of Con A (20 mg/kg, i.v.). The mice were treated with GW (20 mg/kg, i.p., 30 min after Con A injection) or GW plus the selective CB2R antagonist AM630 (2 mg/kg, i.p., 15 min after Con A injection). We found that Con A caused severe acute liver injury evidenced by significantly increased serum aminotransferase levels, massive hepatocyte apoptosis, and necrosis, as well as lymphocyte infiltration in liver tissues. Treatment with GW significantly ameliorated Con A-induced pathological injury in liver tissue, decreased serum aminotransferase levels, and decreased hepatocyte apoptosis. The therapeutic effects of GW were prevented by AM630. In cell experiments, we showed that CB2Rs were highly expressed in Jurkat T cells, but little expression in L02 liver cells. Treatment with GW (10-40 μg/mL) dose-dependently decreased the viability of Jurkat T cells and induced cell apoptosis, which was reversed by AM630. In the coculture of Jurkat T cells with L02 liver cells, GW dose-dependently protected L02 cells from apoptosis induced by Con A (5 μg/mL). The protective effect of GW was reversed by AM630 (1 μg/mL). Our results suggest that GW protects against Con A-induced acute liver injury in mice by inhibiting Jurkat T-cell proliferation through the CB2Rs.

Cannabinoids for the treatment of rheumatic diseases - where do we stand?

As medical use of cannabis is increasingly legalized worldwide, a better understanding of the medical and hazardous effects of this drug is imperative. The pain associated with rheumatic diseases is considered a prevalent indication for medicinal cannabis in various countries. Thus far, preliminary clinical trials have explored the effects of cannabis on rheumatoid arthritis, osteoarthritis and fibromyalgia; preliminary evidence has also found an association between the cannabinoid system and other rheumatic conditions, including systemic sclerosis and juvenile idiopathic arthritis. The potential medicinal effects of cannabis could be attributable to its influence on the immune system, as it exerts an immunomodulatory effect on various immune cells, including T cells, B cells and macrophages. However, the available evidence is not yet sufficient to support the recommendation of cannabinoid treatment for rheumatic diseases.

Role of cannabinoid receptor 1 and the peroxisome proliferator-activated receptor α in mediating anti-nociceptive effects of synthetic cannabinoids and a cannabinoid-like compound

Osteoarthritis (OA) is characterized by cartilage degeneration, subchondral sclerosis, and pain. Cannabinoids have well-established anti-nociceptive properties in animal models of chronic pain. The aim of this study is to evaluate the anti-nociceptive effects of synthetic cannabinoids (WIN-55,212 and HU210) and the cannabinoid-like compound palmitoylethanolamide (PEA) in rat models of OA and to assess the role of cannabinoid receptor 1 (CB1) and the peroxisome proliferator-activated receptor α (PPARα) in mediating these effects. Intra-articular injection of monosodium iodoacetate (MIA) in the knee joint was used as a model of osteoarthritis. The von Frey filament test and weight-bearing difference were used to assess the anti-nociceptive effects of WIN-55,212, HU210, and PEA on MIA-induced OA in rats. Open-field locomotor activity system was used confirm the analgesic effects of those compounds. HU210, WIN55, 212, and PEA in a dose-dependent manner restored the paw withdrawal threshold (PWT) and the weight-bearing difference induced by MIA injection. SR141716A (a CB1 antagonist) significantly reversed the anti-nociceptive effects of all the administered drugs in terms of PWT. However, in terms of weight-bearing difference, SR141716A significantly reduced the anti-nociceptive effect of HU210 but not PEA or WIN55, 212. GW6471 (a PPARα antagonist) significantly reversed the anti-nociceptive effects of PEA but not those of HU210 or WIN55, 212. HU210, WIN55, 212 and PEA significantly restored the MIA-induced reduction in locomotor activity. In conclusions, both CB1 and PPARα receptors are involved in mediating pain in osteoarthritis. Therefore, targeting these receptors may be of great clinical value.

Selective CB2 inverse agonist JTE907 drives T cell differentiation towards a Treg cell phenotype and ameliorates inflammation in a mouse model of inflammatory bowel disease

Cannabinoids are known to possess anti-inflammatory and immunomodulatory properties, but the mechanisms involved are not fully understood. CB2 is the cannabinoid receptor that is expressed primarily on hematopoietic cells and mediates the immunoregulatory functions of cannabinoids. In order to study the effect of JTE907, a selective/inverse agonist of CB2 with anti-inflammatory properties, on the differentiation of T cell subtypes, we used an in vitro system of Th lineage-specific differentiation of naïve CD4⁺ T lymphocytes isolated from the mouse spleen. The results indicate that JTE907 was able to induce the differentiation of Th0 cells into the Treg cell phenotype, which was characterized by the expression of FoxP3, TGF-β and IL-10. P38 phosphorylation and STAT5A activation were found to mediate the signaling pathway triggered by JTE907 via the CB2 receptor in Th0 lymphocytes. In mice with DNBS-induced colitis, JTE907 treatment was able to induce an increase in the number of CD4⁺CD25⁺FoxP3⁺ cells in the lamina propria after 24 h of disease onset and reduce disease severity after 48 h. Further, longer JTE907 treatment resulted in less severe colitis even when administered orally, resulting in less body weight loss, reduction of the disease score, prevention of NF-κB activation, and reduction of the expression of adhesion molecules. Collectively, the results of this study indicate that specific signals delivered through the CB2 receptor can drive the immune response towards the Treg cell phenotype. Thus, ligands such as JTE907 may have use as potential therapeutic agents in autoimmune and inflammatory diseases.

TGF-β1 suppresses syndecan-2 expression through the ERK signaling pathway in nucleus pulposus cells

Intervertebral disc degeneration (IVDD) is the main cause of low back pain and has become a worldwide problem causing enormous economic loss. Thus, mechanisms and treatment of IVDD are attracting great attention from surgeons and physicians. The syndecan (SDC) family has been reported to play important roles in various physiopathologic processes. In this study, we found that SDC2 expression levels were positively correlated with IVDD grades in human samples. Moreover, we demonstrated that transforming growth factor-β1 inhibited SDC2 expression through ERK1/2 signaling pathway activation in nucleus pulposus cells. Knocking down SDC2 in disc cells significantly suppressed aggrecanase-1 and aggrecanase-2 expression. The results of our study indicate that SDC2 may be a therapeutic target through which extracellular matrix degradation of IVDD can be controlled.

The Endogenous Cannabinoid System: A Budding Source of Targets for Treating Inflammatory and Neuropathic Pain

A great need exists for the development of new medications to treat pain resulting from various disease states and types of injury. Given that the endogenous cannabinoid (that is, endocannabinoid) system modulates neuronal and immune cell function, both of which play key roles in pain, therapeutics targeting this system hold promise as novel analgesics. Potential therapeutic targets include the cannabinoid receptors, type 1 and 2, as well as biosynthetic and catabolic enzymes of the endocannabinoids N-arachidonoylethanolamine and 2-arachidonoylglycerol. Notably, cannabinoid receptor agonists as well as inhibitors of endocannabinoid-regulating enzymes fatty acid amide hydrolase and monoacylglycerol lipase produce reliable antinociceptive effects, and offer opioid-sparing antinociceptive effects in myriad preclinical inflammatory and neuropathic pain models. Emerging clinical studies show that 'medicinal' cannabis or cannabinoid-based medications relieve pain in human diseases such as cancer, multiple sclerosis, and fibromyalgia. However, clinical data have yet to demonstrate the analgesic efficacy of inhibitors of endocannabinoid-regulating enzymes. Likewise, the question of whether pharmacotherapies aimed at the endocannabinoid system promote opioid-sparing effects in the treatment of pain reflects an important area of research. Here we examine the preclinical and clinical evidence of various endocannabinoid system targets as potential therapeutic strategies for inflammatory and neuropathic pain conditions.