Dimethylheptyl-THC-11 oic acid: a nonpsychoactive antiinflammatory agent with a cannabinoid template structure

The Elusive Truth of Cannabinoids for Rheumatic Pain

PURPOSE OF REVIEW

Medical cannabis (MC) has entered mainstream medicine by a unique route. Regulatory acceptance as a medical product in many jurisdictions has bypassed the traditional evidence-based pathway required for therapies. Easier access to MC, especially related to recreational legalization of cannabis, has led to widespread use by patients for symptom relief of a variety of medical conditions and often without medical oversight. Musculoskeletal pain remains the most common reason for MC use. This review examines real-world issues pertaining to MC and offers some guidance for clinical care of patients with rheumatic diseases being treated with MC.

RECENT FINDINGS

Controlled clinical studies of cannabis products in patients with rheumatic diseases have been small and tested a range of compounds, routes of administration, and clinical populations, limiting our ability to generate conclusions on MC's effectiveness in this population. Observational cohort studies and surveys suggest that use of MC and related products in patients with rheumatic diseases improves pain and associated symptoms but is commonly accompanied by mild to moderate side effects. Conflicting evidence contributes to practitioner and patient uncertainty regarding the use of MC for rheumatic disease-related pain. Despite promising preclinical and observational evidence that MC and cannabis-derived compounds are useful in the management of rheumatic disease-related pain, there remains limited high-quality clinical evidence to substantiate these findings. There are a significant number of clinical trials on this topic currently planned or underway, however, suggesting the next decade may yield more clarity. Nevertheless, given that many people with rheumatic diseases are using cannabis products, healthcare professionals must remain apprised of the evidence pertaining to cannabinoids, communicate such evidence to patients in a meaningful way that is free from personal bias and stigma, and maintain strong collaborative clinical care pertaining to MC.

Cannabinoids in the Inflamed Synovium Can Be a Target for the Treatment of Rheumatic Diseases

The management of rheumatic diseases has noticeably changed in recent years with the development of targeted therapeutic agents, namely, biological disease-modifying antirheumatic drugs. Identifying essential signaling pathways and factors crucial for the development and progression of these diseases remains a significant challenge. Therapy could be used to delay the onset or reduce harm. The endocannabinoid system's presence within the synovium can be identified as a suggested target for therapeutic interventions due to its role in modulating pain, inflammation, and joint metabolism. This review brings together the most pertinent information concerning the actions of the endocannabinoid system present in inflamed synovial tissue and its interaction with phytocannabinoids and synthetic cannabinoids, which can be used from a therapeutic perspective to minimize the inflammatory and pain processes typical of osteoarthritis and rheumatoid arthritis.

Patent review of cannabinoid receptor type 2 (CB2R) modulators (2016-present)

INTRODUCTION

Cannabinoid receptor type 2 (CB2R), predominantly expressed in immune tissues, is believed to play a crucial role within the body's protective mechanisms. Its modulation holds immense therapeutic promise for addressing a wide spectrum of dysbiotic conditions, including cardiovascular, gastrointestinal, liver, kidney, neurodegenerative, psychiatric, bone, skin, and autoimmune diseases, as well as lung disorders, cancer, and pain management.

AREAS COVERED

This review is an account of patents from 2016 up to 2023 which describes novel CB2R ligands, therapeutic applications, synthesis, as well as formulations of CB2R modulators.

EXPERT OPINION

The patents cover a vast, structurally diverse chemical space. The focus of CB2R ligand development has shifted from unselective dual-cannabinoid receptor type 1 (CB1R) and 2 agonists toward agonists with high selectivity over CB1R, particularly for indications associated with inflammation and tissue injury. Currently, there are at least eight CB2R agonists and one antagonist in active clinical development. A better understanding of the endocannabinoid system (ECS) and in particular of CB2R pharmacology is required to unlock the receptor's full therapeutic potential.

Cannabinoid receptor 2 selective agonist alleviates systemic sclerosis by inhibiting Th2 differentiation through JAK/SOCS3 signaling

Systemic sclerosis (SSc) poses a significant challenge in autoimmunology, characterized by the development of debilitating fibrosis of skin and internal organs. The pivotal role of dysregulated T cells, notably the skewed polarization toward Th2 cells, has been implicated in the vascular damage and progressive fibrosis observed in SSc. In this study, we explored the underlying mechanisms by which cannabinoid receptor 2 (CB2) highly selective agonist HU-308 restores the imbalance of T cells to alleviate SSc. Using a bleomycin-induced SSc (BLM-SSc) mouse model, we demonstrated that HU-308 effectively attenuates skin and lung fibrosis by specifically activating CB2 on CD4+ T cells to inhibit the polarization of Th2 cells in BLM-SSc mice, which was validated by Cnr2-specific-deficient mice. Different from classical signaling downstream of G protein-coupled receptors (GPCRs), HU-308 facilitates the expression of SOCS3 protein and subsequently impedes the IL2/STAT5 signaling pathway during Th2 differentiation. The deficiency of SOCS3 partially mitigated the impact of HU-308. Analysis of a cohort comprising 80 SSc patients and 82 healthy controls revealed an abnormal elevation in the Th2/Th1 ratio in SSc patients. The proportion of Th2 cells showed a significant positive correlation with mRSS score and positivity of anti-Scl-70. Administration of HU-308 to PBMCs and peripheral CD4+ T cells from SSc patients led to the upregulation of SOCS3, which effectively suppressed the aberrantly activated STAT5 signaling pathway and the proportion of CD4+IL4+ T cells. In conclusion, our findings unveil a novel mechanism by which the CB2 agonist HU-308 ameliorates fibrosis in SSc by targeting and reducing Th2 responses. These insights provide a foundation for future therapeutic approaches in SSc by modulating Th2 responses.

The Effects of Nicotine and Cannabinoids on Cytokines

BACKGROUND

The usage of nicotine and cannabinoids has rapidly grown in popularity, leading to increased research into how they can affect people's health, both positively and negatively. Nicotine, Cannabidiol (CBD), and Δ9-tetrahydrocannabinol (THC) have been shown to have significant effects on cytokine function and inflammatory response.

OBJECTIVE

This study aimed to review and summarize the current literature on the effects of nicotine and cannabinoids on cytokines, including interleukins, TNF, IFN, and TGF-β.

METHODS

Literature search was conducted on Medline/PubMed electronic databases utilizing the search terms "nicotine" OR "cannabis" OR "cannabinoids" AND "cytokine" AND "inflammation" AND "stress" AND "immune" from 11/1973 to 02/2024.

RESULTS

THC and CBD usage have been associated with conflicting impacts on immune response, and observed to both exacerbate and inhibit inflammation. Nicotine has been shown to be generally proinflammatory with regards to cytokines. These responses have been reported to have significant effects on bodily response to inflammation-related diseases. Nicotine usage is associated with worsened outcomes for some conditions, like chronic pain, but improved outcomes for others, like arthritis. The impacts of cannabinoid usage tend to be more positive, exerting anti-inflammatory effects across a wide range of diseases. Given the widespread usage of these substances, it is important to understand the nature of their consequences on immune functions and the underlying mechanisms by which they act.

CONCLUSION

This review has covered how cannabinoids and nicotine affect inflammation directly and how these effects can be attributed to the treatment of inflammatory diseases. In summary, the existing research studying the effects of cannabinoids and nicotine supports the major relationship between nicotine and cannabis use and inflammatory diseases.

Potential of dietary hemp and cannabinoids to modulate immune response to enhance health and performance in animals: opportunities and challenges

Cannabinoids are a group of bioactive compounds abundantly present in Cannabis sativa plant. The active components of cannabis with therapeutic potential are known as cannabinoids. Cannabinoids are divided into three groups: plant-derived cannabinoids (phytocannabinoids), endogenous cannabinoids (endocannabinoids), and synthetic cannabinoids. These compounds play a crucial role in the regulation various physiological processes including the immune modulation by interacting with the endocannabinoid system (A complex cell-signaling system). Cannabinoid receptor type 1 (CB1) stimulates the binding of orexigenic peptides and inhibits the attachment of anorexigenic proteins to hypothalamic neurons in mammals, increasing food intake. Digestibility is unaffected by the presence of any cannabinoids in hemp stubble. Endogenous cannabinoids are also important for the peripheral control of lipid processing in adipose tissue, in addition to their role in the hypothalamus regulation of food intake. Regardless of the kind of synaptic connection or the length of the transmission, endocannabinoids play a crucial role in inhibiting synaptic transmission through a number of mechanisms. Cannabidiol (CBD) mainly influences redox equilibrium through intrinsic mechanisms. Useful effects of cannabinoids in animals have been mentioned e.g., for disorders of the cardiovascular system, pain treatment, disorders of the respiratory system or metabolic disorders. Dietary supplementation of cannabinoids has shown positive effects on health, growth and production performance of small and large animals. Animal fed diet supplemented with hemp seeds (180 g/day) or hemp seed cake (143 g/kg DM) had achieved batter performance without any detrimental effects. But the higher level of hemp or cannabinoid supplementation suppress immune functions and reduce productive performance. With an emphasis on the poultry and ruminants, this review aims to highlight the properties of cannabinoids and their derivatives as well as their significance as a potential feed additive in their diets to improve the immune status and health performance of animals.

Goods and Bads of the Endocannabinoid System as a Therapeutic Target: Lessons Learned after 30 Years

The cannabis derivative marijuana is the most widely used recreational drug in the Western world and is consumed by an estimated 83 million individuals (∼3% of the world population). In recent years, there has been a marked transformation in society regarding the risk perception of cannabis, driven by its legalization and medical use in many states in the United States and worldwide. Compelling research evidence and the Food and Drug Administration cannabis-derived cannabidiol approval for severe childhood epilepsy have confirmed the large therapeutic potential of cannabidiol itself, Δ9-tetrahydrocannabinol and other plant-derived cannabinoids (phytocannabinoids). Of note, our body has a complex endocannabinoid system (ECS)-made of receptors, metabolic enzymes, and transporters-that is also regulated by phytocannabinoids. The first endocannabinoid to be discovered 30 years ago was anandamide (N-arachidonoyl-ethanolamine); since then, distinct elements of the ECS have been the target of drug design programs aimed at curing (or at least slowing down) a number of human diseases, both in the central nervous system and at the periphery. Here a critical review of our knowledge of the goods and bads of the ECS as a therapeutic target is presented to define the benefits of ECS-active phytocannabinoids and ECS-oriented synthetic drugs for human health. SIGNIFICANCE STATEMENT: The endocannabinoid system plays important roles virtually everywhere in our body and is either involved in mediating key processes of central and peripheral diseases or represents a therapeutic target for treatment. Therefore, understanding the structure, function, and pharmacology of the components of this complex system, and in particular of key receptors (like cannabinoid receptors 1 and 2) and metabolic enzymes (like fatty acid amide hydrolase and monoacylglycerol lipase), will advance our understanding of endocannabinoid signaling and activity at molecular, cellular, and system levels, providing new opportunities to treat patients.

Therapeutic Prospects of Cannabinoids in the Immunomodulation of Prevalent Autoimmune Diseases

Introduction: Cannabinoids such as ▵-9-THC and CBD can downregulate the immune response by modulating the endocannabinoid system. This modulation is relevant for the treatment of prevalent autoimmune diseases (ADs), such as multiple sclerosis (MS), systemic lupus erythematosus (SLE), diabetes mellitus type 1 (DMT1), and rheumatoid arthritis (RA). These conditions require new therapeutic options with fewer side effects for the control of the autoimmune response. Objective: to conduct a literature review of preclinical scientific evidence that supports further clinical investigations for the use of cannabinoids (natural or synthetic) as potential immunomodulators of the immune response in ADs. Methodology: A systematic search was carried out in different databases using different MeSH terms, such as Cannabis sativa L., cannabinoids, immunomodulation, and ADs. Initially, 677 journal articles were found. After filtering by publication date (from 2000 to 2020 for SLE, DMT1, and RA; and 2010 to 2020 for MS) and removing the duplicate items, 200 articles were selected and analyzed by title and summary associated with the use of cannabinoids as immunomodulatory treatment for those diseases. Results: Evidence of the immunomodulatory effect of cannabinoids in the diseases previously mentioned, but SLE that did not meet the search criteria, was summarized from 24 journal articles. CBD was found to be one of the main modulators of the immune response. This molecule decreased the number of Th1 and Th17 proinflammatory cells and the production of the proinflammatory cytokines, interleukin (IL)-1, IL-12, IL-17, interferon (IFN)-γ, and tumor necrosis factor alpha, in mouse models of MS and DMT1. Additionally, new synthetic cannabinoid-like molecules, with agonist or antagonist activity on CB1, CB2, TRPV1, PPAR-α, and PPAR-γ receptors, have shown anti-inflammatory properties in MS, DMT1, and RA. Conclusion: Data from experimental animal models of AD showed that natural and synthetic cannabinoids downregulate inflammatory responses mediated by immune cells responsible for AD chronicity and progression. Although synthetic cannabinoid-like molecules were evaluated in just two clinical trials, they corroborated the potential use of cannabinoids to treat some ADs. Notwithstanding, new cannabinoid-based approaches are required to provide alternative treatments to patients affected by the large group of ADs.

Cannabinoid receptor type 2 ligands: an analysis of granted patents since 2010

The G-protein-coupled cannabinoid receptor type 2 (CB2R) is a key element of the endocannabinoid (EC) system. EC/CB2R signaling has significant therapeutic potential in major pathologies affecting humans such as allergies, neurodegenerative disorders, inflammation or ocular diseases. CB2R agonism exerts anti-inflammatory and tissue protective effects in preclinical animal models of cardiovascular, gastrointestinal, liver, kidney, lung and neurodegenerative disorders. Existing ligands can be subdivided into endocannabinoids, cannabinoid-like and synthetic CB2R ligands that possess various degrees of potency on and selectivity against the cannabinoid receptor type 1. This review is an account of granted CB2R ligand patents from 2010 up to the present, which were surveyed using Derwent Innovation®.

Relevance of Peroxisome Proliferator Activated Receptors in Multitarget Paradigm Associated with the Endocannabinoid System

Cannabinoids have shown to exert their therapeutic actions through a variety of targets. These include not only the canonical cannabinoid receptors CB1R and CB2R but also related orphan G protein-coupled receptors (GPCRs), ligand-gated ion channels, transient receptor potential (TRP) channels, metabolic enzymes, and nuclear receptors. In this review, we aim to summarize reported compounds exhibiting their therapeutic effects upon the modulation of CB1R and/or CB2R and the nuclear peroxisome proliferator-activated receptors (PPARs). Concomitant actions at CBRs and PPARα or PPARγ subtypes have shown to mediate antiobesity, analgesic, antitumoral, or neuroprotective properties of a variety of phytogenic, endogenous, and synthetic cannabinoids. The relevance of this multitargeting mechanism of action has been analyzed in the context of diverse pathologies. Synergistic effects triggered by combinatorial treatment with ligands that modulate the aforementioned targets have also been considered. This literature overview provides structural and pharmacological insights for the further development of dual cannabinoids for specific disorders.

Molecular Mechanisms for the Inflammation-Resolving Actions of Lenabasum

A first-in-class cannabinoid analog called lenabasum that is a CB2 agonist is being developed as an inflammation-resolving drug candidate. Thus far, specific therapeutic targets include scleroderma, cystic fibrosis, dermatomyositis, and lupus, all of which represent unmet medical needs. Two somewhat-independent molecular mechanisms for this type of action are here proposed. Both pathways initially involve the release of free arachidonic acid after activation of the CB2 receptor and phospholipase A2 by lenabasum. The pathways then diverge into a cyclooxygenase 2-mediated and a lipoxygenase-mediated route. The former leads to increased levels of the cyclopentenone prostaglandin 15-deoxy-Δ^12,14-prostaglandin-J₂ that can activate the NLPR3 inflammasome, which in turn releases caspase-3, leading to apoptosis and the resolution of chronic inflammation. The lipoxygenase-mediated pathway stimulates the production of lipoxin A₄ as well as other signaling molecules called specialized proresolving mediators. These also have inflammation-resolving actions. It is not well understood under which conditions each of these mechanisms operates and whether there is crosstalk between them. Thus, much remains to be learned about the mechanisms describing the actions of lenabasum. SIGNIFICANCE STATEMENT: The resolution of chronic inflammation is a major unmet medical need. The synthetic nonpsychoactive cannabinoid lenabasum could provide a safe and effective drug for this purpose. Two putative molecular mechanisms are suggested to better understand how lenabasum produces this action. In both, different metabolites of arachidonic acid act as mediators.

Resolvins: Emerging Players in Autoimmune and Inflammatory Diseases

Resolvins, belonging to the group of specialized proresolving mediators (SPMs), are metabolic products of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and are synthesized during the initial phases of acute inflammatory responses to promote the resolution of inflammation. Resolvins are produced for termination of neutrophil infiltration, stimulation of the clearance of apoptotic cells by macrophages, and promotion of tissue remodeling and homeostasis. Metabolic dysregulation due to either uncontrolled activity of pro-inflammatory responses or to inefficient resolution of inflammation results in chronic inflammation and may also lead to atherosclerosis or other chronic autoimmune diseases such as rheumatoid arthritis, psoriasis, systemic lupus erythematosus, vasculitis, inflammatory bowel diseases, and type 1 diabetes mellitus. The pathogenesis of such diseases involves a complex interplay between the immune system and, environmental factors (non-infectious or infectious), and critically depends on individual susceptibility to such factors. In the present review, resolvins and their roles in the resolution of inflammation, as well as the role of these mediators as potential therapeutic agents to counteract specific chronic autoimmune and inflammatory diseases are discussed.

A selective CB2 agonist protects against the inflammatory response and joint destruction in collagen-induced arthritis mice

Rheumatoid arthritis (RA) is a chronic, inflammatory, synovitis-dominated systemic disease with unknown etiology. RA is characterized by the involvement of multiple affected joints, symmetry, and invasive arthritis of the limbs, which can lead to joint deformity, cartilage destruction, and loss of function. Cannabinoid receptor 2 (CB₂) has potent immunomodulatory and anti-inflammatory effects and is predominantly expressed in non-neuronal tissues. In the current study, the role of CB₂ in the process of inflammatory bone erosion in RA was examined. The selective agonist or high-affinity ligand of CB₂ (4-quinolone-3-carboxamides CB2 agonist, 4Q3C CB₂ agonist, 4Q3C) significantly reduced the severity of arthritis, decreased histopathological findings, and markedly reduced bone erosion in collagen-induced arthritis (CIA) mice. In addition, 4Q3C prevented an increase in the nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) ratio and inhibited the formation of osteoclasts in CIA mice. Furthermore, the expression of tumor necrosis factor-alpha, interleukin-1β, cyclooxygenase-2, and inducible nitric oxide synthase was lower in 4Q3C-treated CIA mice than in control CIA mice. Micro-computed tomography corroborated the finding that 4Q3C reduced joint destruction. These data clearly indicate that the CB₂-selective agonist, 4Q3C, may have anti-inflammatory and anti-osteoclastogenesis effects in RA and may be considered to be a novel treatment for RA.

Ajulemic acid: potential treatment for chronic inflammation

Ajulemic acid (AJA, CT‐3, IP‐751, JBT‐101, anabasum) is a first‐in‐class, synthetic, orally active, cannabinoid‐derived drug that preferentially binds to the CB2 receptor and is nonpsychoactive. In preclinical studies, and in Phase 1 and 2 clinical trials, AJA showed a favorable safety, tolerability, and pharmacokinetic profile. It also demonstrated significant efficacy in preclinical models of inflammation and fibrosis. It suppresses tissue scarring and stimulates endogenous eicosanoids that resolve chronic inflammation and fibrosis without causing immunosuppression. AJA is currently being developed for use in 4 separate but related indications including systemic sclerosis (SSc), cystic fibrosis, dermatomyositis (DM), and systemic lupus erythematosus. Phase 2 clinical trials in the first 3 targets demonstrated that it is safe, is a potential treatment for these orphan diseases and appears to be a potent inflammation‐resolving drug with a unique mechanism of action, distinct from the nonsteroidal anti‐inflammatory drug (NSAID), and will be useful for treating a wide range of chronic inflammatory diseases. It may be considered to be a disease‐modifying drug unlike most NSAIDs that only provide symptomatic relief. AJA is currently being evaluated in 24‐month open‐label extension studies in SSc and in skin‐predominant DM. A Phase 3 multicenter trial to demonstrate safety and efficacy in SSc has recently been initiated.

Gene Expression of ABHD6, a Key Factor in the Endocannabinoid System, Can Be Modulated by Female Hormones in Human Immune Cells

One of the main risk factors for the development of an autoimmune disease is to be a woman. Much attention has been given to the involvement of female hormones in their etiology and sexual bias, although the mechanisms behind this potentially strong contribution in disease susceptibility are poorly understood. ABHD6 gene was recently identified as a risk factor for system lupus erythematosus and the risk was correlated with overexpression of the gene. ABHD6 is an enzyme that degrades the 2-arachidonoylglycerol, an endocannabinoid with immunomodulatory effects. Thus its degradation could contribute to immune dysregulation and development of autoimmune reactions. Sex hormones, such as estrogens, are believed to regulate important genes in the endocannabinoid pathway. However, no study was available regarding the effect of these hormones in human immune cells. In this study, ABHD6 expression was evaluated by quantitative PCR in leukocytes from healthy male and females and in the presence of estrogen or progesterone (PG). A statistical increase in ABHD6 expression could be detected in women. In the presence of estrogen or PG, a statistical upregulation of ABHD6 was observed, and in a sex-dependent manner, as only female cells responded to stimulation. Our results suggest that female hormones can promote the overexpression of ABHD6 in immune cells. This can potentially contribute to a pro-inflammatory scenario and partially explain the association of this gene in the development of LES, a highly female-biased disease.

Anti-Inflammatory, Antioxidative, and Hepatoprotective Effects of Trans Δ9-Tetrahydrocannabinol/Sesame Oil on Adjuvant-Induced Arthritis in Rats

Rheumatoid arthritis (RA) is a painful chronic autoimmune disease affecting the joints. Its first-line therapy, Methotrexate (MTX), although effective in ameliorating the progress of the disease, induces hepatotoxicity over long-term usage. Thus, seeking natural compounds with fewer side effects could be an alternative therapeutic approach. This study aimed to investigate the anti-inflammatory, antiarthritic, and antioxidative effects of synthetic trans-Δ9-tetrahydrocannabinol (Δ9-THC) dissolved in sesame oil (Dronabinol) against MTX in adjuvant-induced arthritis (AIA) rat model. Daily oral administration of Δ9-THC/sesame oil, over a period of 21 days, was well tolerated in arthritic rats with no particular psychoactive side effects. It markedly attenuated the severity of clinical manifestations, recovered the histopathological changes in tibiotarsal joints, and repressed the splenomegaly in arthritic rats. Δ9-THC/sesame oil therapy showed similar effects to MTX in neutralizing the inflammatory process of AIA, through attenuating erythrocyte sedimentation rate (ESR) scores and proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin 1-beta (IL-1β), and interleukin-6 (IL-6) levels, to normal values. As opposed to MTX, this natural combination markedly protected the liver of arthritic rats and downregulated the induced oxidative stress by increasing the antioxidant defense system such as activities of catalase and superoxide dismutase (SOD) and levels of glutathione (GSH). These results suggest promising effects for the clinical use of Δ9-THC/sesame oil therapy in alleviating arthritic clinical signs as well as arthritis-induced liver injury.

Potent Anti-Inflammatory and Pro-Resolving Effects of Anabasum in a Human Model of Self-Resolving Acute Inflammation

Anabasum is a synthetic analog of Δ⁸‐tetrahydrocannabinol (THC)‐11‐oic acid that in preclinical models of experimental inflammation exerts potent anti‐inflammatory actions with minimal central nervous system (CNS) cannabimimetic activity. Here we used a novel model of acute inflammation driven by i.d. UV‐killed E. coli in healthy humans and found that anabasum (5 mg) exerted a potent anti‐inflammatory effect equivalent to that of prednisolone in terms of inhibiting neutrophil infiltration, the hallmark of acute inflammation. These effects arose from the inhibition of the neutrophil chemoattractant LTB₄, while the inhibition of antiphagocytic prostanoids (PGE₂, TxB₂, and PGF₂α) resulted in enhanced clearance of inflammatory stimulus from the injected site. Anabasum at the higher dose of 20 mg possessed the additional properties of triggering the biosynthesis of specialized pro‐resolving lipid mediators including LXA₄, LXB₄, RvD1, and RvD3. Collectively, we demonstrate for the first time a striking anti‐inflammatory and pro‐resolution effects of a synthetic analog of THC in healthy humans.

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.

Cannabinoid Analgesia as a Potential New Therapeutic Option in the Treatment of Chronic Pain

Objective:

To review the literature concerning the physiology of the endocannabinoid system, current drug development of cannabinoid agonists, and current clinical research on the use of cannabinoid agonists for analgesia.

Data Sources:

Articles were identified through a search of MEDLINE (1966–August 2005) using the key words cannabis, cannabinoid, cannabi*, cannabidiol, nabilone, THC, pain, and analgesia. No search limits were included. Additional references were located through review of the bibliographies of the articles identified.

Study Selection and Data Extraction:

Studies of cannabinoid agonists for treatment of pain were selected and were not limited by pain type or etiology. Studies or reviews using animal models of pain were also included. Articles that related to the physiology and pharmacology of the endocannabinoid system were evaluated.

Data Synthesis:

The discovery of cannabinoid receptors and endogenous ligands for these receptors has led to increased drug development of cannabinoid agonists. New cannabimimetic agents have been associated with fewer systemic adverse effects than delta-9-tetrahydrocannabinol, including recent development of cannabis medicinal extracts for sublingual use (approved in Canada), and have had promising results for analgesia in initial human trials. Several synthetic cannabinoids have also been studied in humans, including 2 cannabinoid agonists available on the international market.

Conclusions:

Cannabinoids provide a potential approach to pain management with a novel therapeutic target and mechanism. Chronic pain often requires a polypharmaceutical approach to management, and cannabinoids are a potential addition to the arsenal of treatment options.

Expression of Cannabinoid Receptors in Human Osteoarthritic Cartilage: Implications for Future Therapies

Introduction: Cannabinoids have shown to reduce joint damage in animal models of arthritis and reduce matrix metalloproteinase expression in primary human osteoarthritic (OA) chondrocytes. The actions of cannabinoids are mediated by a number of receptors, including cannabinoid receptors 1 and 2 (CB1 and CB2), G-protein-coupled receptors 55 and 18 (GPR55 and GPR18), transient receptor potential vanilloid-1 (TRPV1), and peroxisome proliferator-activated receptors alpha and gamma (PPARα and PPARγ). However, to date very few studies have investigated the expression and localization of these receptors in human chondrocytes, and expression during degeneration, and thus their potential in clinical applications is unknown. Methods: Human articular cartilage from patients with symptomatic OA was graded histologically and the expression and localization of cannabinoid receptors within OA cartilage and underlying bone were determined immunohistochemically. Expression levels across regions of cartilage and changes with degeneration were investigated. Results: Expression of all the cannabinoid receptors investigated was observed with no change with grade of degeneration seen in the expression of CB1, CB2, GPR55, PPARα, and PPARγ. Conversely, the number of chondrocytes within the deep zone of cartilage displaying immunopositivity for GPR18 and TRPV1 was significantly decreased in degenerate cartilage. Receptor expression was higher in chondrocytes than in osteocytes in the underlying bone. Conclusions: Chondrocytes from OA joints were shown to express a wide range of cannabinoid receptors even in degenerate tissues, demonstrating that these cells could respond to cannabinoids. Cannabinoids designed to bind to receptors inhibiting the catabolic and pain pathways within the arthritic joint, while avoiding psychoactive effects, could provide potential arthritis therapies.

Ligand-based virtual screening identifies a family of selective cannabinoid receptor 2 agonists

The cannabinoid receptor 2 (CB2R) has been linked with the regulation of inflammation, and selective receptor activation has been proposed as a target for the treatment of a range of inflammatory diseases such as atherosclerosis and arthritis. In order to identify selective CB2R agonists with appropriate physicochemical and ADME properties for future evaluation in vivo, we first performed a ligand-based virtual screen. Subsequent medicinal chemistry optimisation studies led to the identification of a new class of selective CB2R agonists. Several examples showed high levels of activity (EC50<200 nM) and binding affinity (Ki<200 nM) for the CB2R, and no detectable activity at the CB1R. The most promising example, DIAS2, also showed favourable in vitro metabolic stability and absorption properties along with a clean selectivity profile when evaluated against a panel of GPCRs and kinases.

Activation of cannabinoid receptor 2 attenuates synovitis and joint distruction in collagen-induced arthritis

OBJECTIVES

Recent studies have suggested immunomodulatory and anti-inflammatory effects of cannabinoid receptor 2 (CB2R) activation, which is devoid of psychoactivity. We have demonstrated the expression of CB2R in synovial tissue from patients with rheumatoid arthritis (RA), and its specific activation shows inhibitory effects on fibroblast-like synoviocytes. However, it is still unclear whether selective activation of CB2R inhibits joint inflammation or protects joint damage in RA.

METHODS

A murine model of collagen-induced arthritis (CIA) was used to evaluate the therapeutic efficacy of HU-308, a selective CB2R agonist. The disease severity was evaluated by semi-quantitative scoring of joint swelling, histological assessment of joint inflammation and structure, and radiographic assessment of joint destruction by using digital plain radiographs and micro-CT scans. The concentrations of various isotypes of anti-collagen II antibodies in sera and the levels of cytokines in culture supernatants were determined by ELISA.

RESULTS

Compared with vehicle treatment, protective treatment with intraperitoneal injection of HU-308 (0.3-1.0 mg/kg) failed to decrease the incidence of the development of CIA, but it effectively suppressed the severity of the disease. In CIA mice, treatment with HU-308 significantly decreased joint swelling, synovial inflammation, and joint destruction, as well as serum levels of anti-collagen II antibodies. In vitro, HU-308 (1-10 μM) significantly suppressed the production of proinflammatory cytokines IL-6 and TNF-α from lipopolysaccharide-stimulated murine peritoneal macrophages with intact CB2R in dose-dependent manners. HU-308 failed to elicit any inhibitory effect of on lipopolysaccharide-stimulated macrophages from CB2R-knockout mice.

CONCLUSIONS

Activation of CB2R by HU-308 has therapeutic potential for RA to suppress synovitis and alleviate joint destruction by inhibiting the production of autoantibodies and proinflammatory cytokines.

Involvement of the endocannabinoid system in osteoarthritis pain

Osteoarthritis is a degenerative joint disease associated with articular cartilage degradation. The major clinical outcome of osteoarthritis is a complex pain state that includes both nociceptive and neuropathic mechanisms. Currently, the therapeutic approaches for osteoarthritis are limited as no drugs are available to control the disease progression and the analgesic treatment has restricted efficacy. Increasing evidence from preclinical studies supports the interest of the endocannabinoid system as an emerging therapeutic target for osteoarthritis pain. Indeed, pharmacological studies have shown the anti-nociceptive effects of cannabinoids in different rodent models of osteoarthritis, and compelling evidence suggests an active participation of the endocannabinoid system in the pathophysiology of this disease. The ubiquitous distribution of cannabinoid receptors, together with the physiological role of the endocannabinoid system in the regulation of pain, inflammation and even joint function further support the therapeutic interest of cannabinoids for osteoarthritis. However, limited clinical evidence has been provided to support this therapeutic use of cannabinoids, despite the promising preclinical data. This review summarizes the promising results that have been recently obtained in support of the therapeutic value of cannabinoids for osteoarthritis management.

The cannabinoid acids, analogs and endogenous counterparts

The cannabinoid acids are a structurally heterogeneous group of compounds some of which are endogenous molecules and others that are metabolites of phytocannabinoids. The prototypic endogenous substance is N-arachidonoyl glycine (NAgly) that is closely related in structure to the cannabinoid agonist anandamide. The most studied phytocannabinoid is Δ(9)-THC-11-oic acid, the principal metabolite of Δ(9)-THC. Both types of acids have in common several biological actions such as low affinity for CB1 anti-inflammatory activity and analgesic properties. This suggests that there may be similarities in their mechanism of action, a point that is discussed in this review. Also presented are reports on analogs of the acids that provide opportunities for the development of novel therapeutic agents, such as ajulemic acid.

Ultrapure ajulemic acid has improved CB2 selectivity with reduced CB1 activity

Ajulemic acid, a side-chain analog of Δ(8)-THC-11-oic acid, was designed as a potent therapeutic agent free of the psychotropic adverse effects typical of most cannabinoids. Subsequent studies of ajulemic acid have yielded widely divergent findings on the occurrence of these adverse effects. To help resolve these discrepancies, we have prepared highly purified ajulemic acid using a different synthetic method than previously reported in the literature and compared its cannabinoid receptor binding constants with those obtained using several other preparations from different sources. Whereas CB2 binding did not vary greatly among all of the samples, the CB1 binding showed a wide range of affinities. The highly purified product (JBT-101) reported here had the weakest affinity for CB1 while the original preparation (HU-239) showed the strongest affinity for CB1. The CB1/CB2 ratio of affinities was 12.3 for JBT-101 whereas that for HU-239 was 0.19, a 65-fold difference. Functional responses such as catalepsy and hypothermia using JBT-101 versus HU-239 displayed reduced CB1 activity in keeping with the receptor binding data. Thus, earlier conclusions on the limited therapeutic index for ajulemic acid need to be reconsidered in the light of the data now obtained using JBT-101.

Cannabinoid WIN-55,212-2 mesylate inhibits interleukin-1β induced matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase expression in human chondrocytes

OBJECTIVE

Interleukin-1β (IL-1β) is involved in the up-regulation of matrix metalloproteinases (MMPs) leading to cartilage degradation. Cannabinoids are anti-inflammatory and reduce joint damage in animal models of arthritis. This study aimed to determine a mechanism whereby the synthetic cannabinoid WIN-55,212-2 mesylate (WIN-55) may inhibit cartilage degradation.

METHODS

Effects of WIN-55 were studied on IL-1β stimulated production of MMP-3 and -13 and their inhibitors TIMP-1 and -2 in human chondrocytes. Chondrocytes were obtained from articular cartilage of patients undergoing total knee replacement. Chondrocytes were grown in monolayer and 3D alginate bead cultures. Real-time polymerase chain reaction (PCR) was used to determine the gene expression of MMP-3, -13, TIMP-1 and -2 and Enzyme Linked Immunosorbent Assay (ELISA) to measure the amount of MMP-3 and MMP-13 protein released into media. Immunocytochemistry was used to investigate the expression of cannabinoid receptors in chondrocyte cultures.

RESULTS

Treatment with WIN-55 alone or in combination with IL-1β, decreased or abolished MMP-3, -13, TIMP-1 and -2 gene expression in human chondrocyte monolayer and alginate bead cultures in both a concentration and time dependent manner. WIN-55 treatment alone, and in combination with IL-1β, reduced MMP-3 and -13 protein production by chondrocytes cultured in alginate beads. Immunocytochemistry demonstrated the expression of cannabinoid receptors in chondrocyte cultures.

CONCLUSION

Cannabinoid WIN-55 can reduce both basal and IL-1β stimulated gene and protein expression of MMP-3 and -13. However WIN-55 also decreased basal levels of TIMP-1 and -2 mRNA. These actions of WIN-55 suggest a mechanism by which cannabinoids may act to prevent cartilage breakdown in arthritis.

Update on the role of cannabinoid receptors after ischemic stroke

Cannabinoids are considered as key mediators in the pathophysiology of inflammatory diseases, including atherosclerosis. In particular, they have been shown to reduce the ischemic injury after acute cardiovascular events, such as acute myocardial infarction and ischemic stroke. These protective and anti-inflammatory properties on peripheral tissues and circulating inflammatory have been demonstrated to involve their binding with both selective cannabinoid type 1 (CB₁) and type 2 (CB₂) transmembrane receptors. On the other hands, the recent discoveries of novel different classes of cannabinoids and receptors have increased the complexity of this system in atherosclerosis. Although only preliminary data have been reported on the activities of novel cannabinoid receptors, several studies have already investigated the role of CB₁ and CB₂ receptors in ischemic stroke. While CB₁ receptor activation has been shown to directly reduce atherosclerotic plaque inflammation, controversial data have been shown on neurotransmission and neuroprotection after stroke. Given its potent anti-inflammatory activities on circulating leukocytes, the CB₂ activation has been proven to produce protective effects against acute poststroke inflammation. In this paper, we will update evidence on different cannabinoid-triggered avenues to reduce inflammation and neuronal injury in acute ischemic stroke.

Cannabinoids: novel therapies for arthritis?

A key feature of osteoarthritis and rheumatoid arthritis is the loss of articular cartilage. Cartilage breakdown is mediated by complex interactions of proinflammatory cytokines, such as IL-1, inflammatory mediators, including nitric oxide and prostaglandin E2, and proteases, including matrix metalloproteinases and aggrecanases, such as ADAMTS-4 and -5. Cannabinoids have been shown to reduce joint damage in animal models of arthritis. They have also been shown to prevent IL-1-induced matrix breakdown of collagen and proteoglycan, indicating that cannabinoids may mediate chondroprotective effects. Cannabinoids produce their effects via several cannabinoid receptors and it is important to identify the key cannabinoids and their receptors that are involved in chondroprotection. This review aims to outline the current and future prospects of cannabinoids as anti-arthritic therapeutics, in terms of their ability to prevent cartilage breakdown.

Regulatory effect of cannabinoid receptor agonist on chemokine-induced lymphocyte chemotaxis

Cannabinoids elicit biological responses through two types of specific receptors, CB1 and CB2. Immune cells including naïve B-lymphocytes are known to selectively express peripheral cannabinoid receptors, CB2. Although the immunosuppressive effects of cannabinoids have become widely known, the mechanisms underlying their effects are not well understood. In this study, we demonstrated that splenic lymphocytes migrated toward a synthetic cannabinoid receptor agonist, WIN55,212-2. There is an optimal concentration range for induction of lymphocyte migration and a high dose fails to induce cell migration. Furthermore, a high dose of WIN55,212-2 significantly inhibited CXCL12-induced chemotaxis of lymphocytes. The inhibitory effect was transient and reversible. The inhibition was also observed when purified B-lymphocytes were used for CXCL12-induced chemotaxis. These results provide novel information regarding the cellular mechanisms underlying the effects of cannabinoids on the immune system.

Cannabinoids: a new group of agonists of PPARs

Cannabinoids have been used medicinally and recreationally for thousands of years and their effects were proposed to occur mainly via activation of the G-protein-coupled receptor CB1/CB2 (cannabinoid receptor 1/2). Discovery of potent synthetic analogs of the natural cannabinoids as clinically useful drugs is the sustained aim of cannabinoid research. This demands that these new compounds be free of the psychotropic effects that connected with the recreational use of cannabinoids. In preclinical studies cannabinoids displayed many of the characteristics of nonsteroidal anti-inflammatory drugs (NSAIDs) and it seems to be free of unwanted side effects. An increasing number of therapeutic actions of cannabinoid are being reported that do not appear to be mediated by either CB1 or CB2, and recently nuclear receptor superfamily PPARs (peroxisome-proliferator-activated receptors) have been suggested as the target of certain cannabinoids. This review summarizes the evidence for cannabinoid activation on PPARs and possible associated remedial potentials.

Cannabinoids as novel anti-inflammatory drugs

Cannabinoids are a group of compounds that mediate their effects through cannabinoid receptors. The discovery of Δ9-tetrahydrocannabinol (THC) as the major psychoactive principle in marijuana, as well as the identification of cannabinoid receptors and their endogenous ligands, has led to a significant growth in research aimed at understanding the physiological functions of cannabinoids. Cannabinoid receptors include CB1, which is predominantly expressed in the brain, and CB2, which is primarily found on the cells of the immune system. The fact that both CB1 and CB2 receptors have been found on immune cells suggests that cannabinoids play an important role in the regulation of the immune system. Recent studies demonstrated that administration of THC into mice triggered marked apoptosis in T cells and dendritic cells, resulting in immunosuppression. In addition, several studies showed that cannabinoids downregulate cytokine and chemokine production and, in some models, upregulate T-regulatory cells (Tregs) as a mechanism to suppress inflammatory responses. The endocannabinoid system is also involved in immunoregulation. For example, administration of endocannabinoids or use of inhibitors of enzymes that break down the endocannabinoids, led to immunosuppression and recovery from immune-mediated injury to organs such as the liver. Manipulation of endocannabinoids and/or use of exogenous cannabinoids in vivo can constitute a potent treatment modality against inflammatory disorders. This review will focus on the potential use of cannabinoids as a new class of anti-inflammatory agents against a number of inflammatory and autoimmune diseases that are primarily triggered by activated T cells or other cellular immune components.

Latest advances in cannabinoid receptor agonists

BACKGROUND

Since the discovery of cannabinoid receptors and their endogenous ligands in early 1990s, the endocannabinoid system has been shown to play a vital role in several pathophysiological processes. It has been targeted for the treatment of several diseases including neurodegenerative diseases (Parkinson's disease, Alzheimer's disease, Huntington's disease and MS), cancer, obesity, inflammatory bowel disease, neuropathic and inflammatory pain. The last decade has witnessed remarkable advances in the development of cannabinergic ligands displaying high selectivity and potency towards two subtypes of cannabinoid receptors, namely CB1 and CB2.

OBJECTIVE

In this review, we highlight the latest advances made in the development of cannabinoid agonists and summarize recently disclosed, novel chemical scaffolds as CB-selective agonists in patents that appeared during January 2008 - June 2009.

METHODS

Data presented here are obtained through the search of PubMed for research articles and reviews, and the website of European patents (http://ep.espacenet.com), SciFinder Scholar and US patents (www.uspto.gov).

CONCLUSIONS

Our analysis reveals prolific patenting activity mainly in the CB2 selective agonist area. Limiting the BBB penetrability, thereby, leading to peripherally restricted CB1/CB2 agonists and enhancing CB2-selectivity emerge as likely prerequisites for avoidance of adverse central CB1 mediated side effects.

Cannabinoid-induced apoptosis in immune cells as a pathway to immunosuppression

Cannabinoids are a group of compounds present in Cannabis plant (Cannabis sativa L.). They mediate their physiological and behavioral effects by activating specific cannabinoid receptors. With the recent discovery of the cannabinoid receptors (CB1 and CB2) and the endocannabinoid system, research in this field has expanded exponentially. Cannabinoids have been shown to act as potent immunosuppressive and anti-inflammatory agents and have been shown to mediate beneficial effects in a wide range of immune-mediated diseases such as multiple sclerosis, diabetes, septic shock, rheumatoid arthritis, and allergic asthma. Cannabinoid receptor 1 (CB1) is mainly expressed on the cells of the central nervous system as well as in the periphery. In contrast, cannabinoid receptor 2 (CB2) is predominantly expressed on immune cells. The precise mechanisms through which cannabinoids mediate immunosuppression is only now beginning to be understood and can be broadly categorized into four pathways: apoptosis, inhibition of proliferation, suppression of cytokine and chemokine production and induction of T regulatory cells (T regs). Studies from our laboratory have focused on mechanisms of apoptosis induction by natural and synthetic cannabinoids through activation of CB2 receptors. In this review, we will focus on apoptotic mechanisms of immunosuppression mediated by cannabinoids on different immune cell populations and discuss how activation of CB2 provides a novel therapeutic modality against inflammatory and autoimmune diseases as well as malignancies of the immune system, without exerting the untoward psychotropic effects.

Cannabinoids, endocannabinoids, and related analogs in inflammation

This review covers reports published in the last 5 years on the anti-inflammatory activities of all classes of cannabinoids, including phytocannabinoids such as tetrahydrocannabinol and cannabidiol, synthetic analogs such as ajulemic acid and nabilone, the endogenous cannabinoids anandamide and related compounds, namely, the elmiric acids, and finally, noncannabinoid components of Cannabis that show anti-inflammatory action. It is intended to be an update on the topic of the involvement of cannabinoids in the process of inflammation. A possible mechanism for these actions is suggested involving increased production of eicosanoids that promote the resolution of inflammation. This differentiates these cannabinoids from cyclooxygenase-2 inhibitors that suppress the synthesis of eicosanoids that promote the induction of the inflammatory process.

Ajulemic acid, a synthetic cannabinoid, increases formation of the endogenous proresolving and anti-inflammatory eicosanoid, lipoxin A4

Ajulemic acid (AjA), a synthetic nonpsychoactive cannabinoid, and lipoxin A(4) (LXA(4)), an eicosanoid formed from sequential actions of 5- and 15-lipoxygenases (LOX), facilitate resolution of inflammation. The purpose of this study was to determine whether the ability of AjA to limit the progress of inflammation might relate to an increase in LXA(4), a known anti-inflammatory and proresolving mediator. Addition of AjA (0-30 microM) in vitro to human blood and synovial cells increased production of LXA(4) (ELISA) 2- to 5-fold. Administration of AjA to mice with peritonitis resulted in a 25-75% reduction of cells invading the peritoneum, and a 7-fold increase in LXA(4) identified by mass spectrometry. Blockade of 12/15 LOX, which leads to LXA(4) synthesis via 15-HETE production, reduced (>90%) the ability of AjA to enhance production of LXA(4) in vitro. These results suggest that AjA and other agents that increase endogenous compounds that facilitate resolution of inflammation may be useful for conditions characterized by inflammation and tissue injury.

Ajulemic acid, a synthetic cannabinoid acid, induces an antiinflammatory profile of eicosanoids in human synovial cells

AIMS

To better understand mechanisms whereby Ajulemic acid (AjA), a synthetic antiinflammatory cannabinoid, promotes resolution of acute and chronic inflammation in animal models, we investigated its influence on cyclooxygenase 2 (COX2) expression and eicosanoid production in human fibroblast-like synovial cells (FLS).

MAIN METHODS

FLS isolated from tissue obtained at joint replacement surgery or cultured from synovial fluid were treated for 60 min with AjA (10-30 microM), then stimulated with tumor necrosis factor alpha (TNFalpha). COX2 mRNA was measured by hybridization/colorimetric assay of whole cell lysates collected 4 h after stimulation. To determine effects on arachidonic acid release, FLS were incubated with (14)C-arachidonic acid for 20 h then treated with AjA (8-32 microM). Arachidonic acid release was measured by scintillation counting. Prostaglandins (PG) were measured by enzyme linked immunosorbent assay (ELISA) in cell supernatants collected 4 and 24 h after stimulation.

KEY FINDINGS

AjA increased the steady state levels of COX2 mRNA in and arachidonic acid release from FLS. Treatment of FLS with AjA increased 15-deoxy-delta(12,14)-PGJ(2) (15d-PGJ(2)) production in a concentration dependent manner, but did not affect PGE(2) production significantly.

SIGNIFICANCE

The capacity of AjA to increase selectively and markedly 15d-PGJ(2), an eicosanoid which facilitates resolution of inflammation, suggests that AjA may have value as a therapeutic agent for the treatment of rheumatoid arthritis (RA) and other diseases characterized by acute and chronic inflammation.

Suppression of human macrophage interleukin-6 by a nonpsychoactive cannabinoid acid

Interleukin-6 (IL-6) is a multifunctional cytokine which contributes to inflammation and tissue injury in several diseases. Thus, inhibition of IL-6 production may be a useful strategy for treatment of patients with diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). A synthetic nonpsychoactive cannabinoid, ajulemic acid (AjA), prevents joint damage in experimental arthritis. Results of experiments presented here indicate that addition of AjA (3-30 microM) to human monocyte derived macrophages in vitro reduces steady state levels of IL-6 mRNA and the subsequent secretion of IL-6 from LPS stimulated cells. Although AjA binds to and activates PPARgamma, its anti IL-6 effects are PPARgamma independent. These studies provide evidence to support the view that AjA may prove to be an effective, safe antiinflammatory agent.

On the pharmacological properties of Delta9-tetrahydrocannabinol (THC)

Cannabis is one of the first plants used as medicine, and the notion that it has potentially valuable therapeutic properties is a matter of current debate. The isolation of its main constituent, Delta9-tetrahydrocannabinol (THC), and the discovery of the endocannabinoid system (cannabinoid receptors CB1 and CB2 and their endogenous ligands) made possible studies concerning the pharmacological activity of cannabinoids. This paper reviews some of the most-important findings in the field of THC pharmacology. Clinical trials, anecdotal reports, and experiments employing animal models strongly support the idea that THC and its derivatives exhibit a wide variety of therapeutic applications. However, the psychotropic effects observed in laboratory animals and the adverse reactions reported during human trials, as well as the risk of tolerance development and potential dependence, limit the application of THC in therapy. Nowadays, researchers focus on other therapeutic strategies by which the endocannabinoid system might be modulated to clinical advantage (inhibitor or activator of endocannabinoid biosynthesis, cellular uptake, or metabolism). However, emerging evidence highlights the beneficial effects of the whole cannabis extract over those observed with single components, indicating cannabis-based medicines as new perspective to revisit the pharmacology of this plant.

Effects of IP-751, Ajulemic Acid, on Bladder Overactivity Induced by Bladder Irritation in Rats

OBJECTIVES

Ajulemic acid (IP-751) is a synthetic analog of tetrahydrocannabinol, which is a major ingredient of the plant Cannabis. IP-751 reportedly shows potent anti-inflammatory activity and is a powerful analgesic agent. Thus, we examined whether IP-751 can suppress urinary frequency induced by nociceptive stimuli in the bladder.

METHODS

Continuous cystometry (infusion rate 0.04 mL/min) under urethane anesthesia was performed to evaluate the effect of intravenous injection of IP-751 with or without a cannabinoid-1 receptor antagonist (AM251) or a cannabinoid-2 receptor antagonist (AM630) on bladder function in normal rats and rats with urinary frequency induced by intravesical infusion with 0.25% acetic acid or cyclophosphamide (CYP) (150 mg/kg intraperitoneally, 48 hours before cystometrography).

RESULTS

When 10 mg/kg of IP-751 was injected in normal rats, the intercontraction interval (ICI) and pressure threshold increased. A 0.25% acetic acid infusion induced urinary frequency, as evidenced by a reduction in ICIs, which were suppressed by injection of IP-751 (10 mg/kg). Urinary frequency, indicated by significant ICI reductions, was also observed in the CYP-treated rats. Administration of IP-751 (10 mg/kg) significantly suppressed CYP-induced urinary frequency, as evidenced by the increase in the ICI. When AM251, but not AM630, was administered before IP-751, the IP-751-induced increases in the ICI and pressure threshold were prevented in all three groups. In addition, administration of AM251 alone decreased the ICIs in CYP-treated rats.

CONCLUSIONS

IP-751 can suppress normal bladder activity and urinary frequency induced by bladder nociceptive stimuli, probably by suppression of bladder afferent activity. These inhibitory effects of IP-751 are at least in part mediated by the cannabinoid-1 receptor.

Therapeutic Potential of Cannabinoid-Based Drugs

Cannabinoid-based drugs modeled on cannabinoids originally isolated from marijuana are now known to significantly impact the functioning of the endocannabinoid system of mammals. This system operates not only in the brain but also in organs and tissues in the periphery including the immune system. Natural and synthetic cannabinoids are tricyclic terpenes, whereas the endogenous physiological ligands are eicosanoids. Several receptors for these compounds have been extensively described, CB1 and CB2, and are G protein-coupled receptors; however, cannabinoid-based drugs are also demonstrated to function independently of these receptors. Cannabinoids regulate many physiological functions and their impact on immunity is generally antiinflammatory as powerful modulators of the cytokine cascade. This anti-inflammatory potency has led to the testing of these drugs in chronic inflammatory laboratory paradigms and even in some human diseases. Psychoactive and nonpsychoactive cannabinoid-based drugs such as Delta9-tetrahydrocannabinol, cannabidiol, HU-211, and ajulemic acid have been tested and found moderately effective in clinical trials of multiple sclerosis, traumatic brain injury, arthritis, and neuropathic pain. Furthermore, although clinical trials are not yet reported, preclinical data with cannabinoid-based drugs suggest efficacy in other inflammatory diseases such as inflammatory bowel disease, Alzheimer's disease, atherosclerosis, and osteoporosis.

Ajulemic acid, a nonpsychoactive cannabinoid acid, suppresses osteoclastogenesis in mononuclear precursor cells and induces apoptosis in mature osteoclast-like cells

Oral administration of ajulemic acid (AjA), a cannabinoid acid devoid of psychoactivity, prevents joint tissue injury in rats with adjuvant induced arthritis. Because activation of osteoclasts is central to the pathogenesis of bone erosion in patients with rheumatoid arthritis (RA), we investigated the influence of AjA on osteoclast differentiation and survival. Osteoclast cultures were established by stimulation of RAW264.7 cells and primary mouse bone marrow cultures with receptor activator of NF-kappaB ligand (RANKL). Simultaneous addition of AjA (15 and 30 microM) and RANKL to both culture systems significantly suppressed development of multinucleated osteoclasts (osteoclastogenesis) in a dose dependent manner, as determined by quantification of multinuclear, tartrate-resistant acid phosphatase (TRAP)-positive cells. AjA impaired growth of RAW264.7 monocytes and prevented further osteoclast formation in cultures in which osteoclastogenesis had already begun. Reduction by AjA of both monocyte growth and osteoclast formation was associated with apoptosis, assayed by annexin V and propidium iodide staining, and caspase activity. The anti-osteoclastogenic effects of AjA did not require the continuous presence of AjA in the cell cultures. Based on these findings, we propose that AjA or other nonpsychoactive synthetic analogs of Cannabis constituents may be useful therapy for diseases such as RA and osteoporosis in which bone resorption is a central feature.

Suppression of fibroblast metalloproteinases by ajulemic acid, a nonpsychoactive cannabinoid acid

Production of matrix metalloproteinases (MMP) in joint tissue of patients with inflammatory arthritis facilitates cartilage degradation and bone erosion, and leads to joint deformities and crippling. Thus, MMPs are important targets for agents designed to treat inflammatory arthritis. Oral administration of ajulemic acid (AjA), a synthetic, nonpsychoactive cannabinoid acid, prevents joint tissue injury in rats with adjuvant arthritis. AjA binds to and activates PPARgamma directly. Therefore, we investigated the influence of AjA on MMP production in human fibroblast-like synovial cells (FLS), and examined the role of PPARgamma in the mechanism of action of AjA. FLS, treated or not with a PPARgamma antagonist, were treated with AjA then stimulated with TNFalpha or IL-1alpha. Release of MMPs-1, 3, and 9 was measured by ELISA. The influence of AjA on MMP-3 release from stimulated PPARgamma positive (PPAR+/-) and PPARgamma null (PPAR-/-) mouse embryonic fibroblasts (MEF) was also examined. Addition of AjA to FLS suppressed production of MMPs whether or not PPARgamma activation was blocked. Secretion of MMP-3 was also suppressed by AjA in both TNFalpha- and IL-1alpha-stimulated PPARgamma+/- and PPARgamma-/- MEF. Suppression of MMP secretion from FLS by AjA appears to be PPARgamma independent. Prevention by AjA of joint tissue injury and crippling in the rat adjuvant arthritis model may be explained in large part by inhibition of MMPs. These results suggest that AjA may be useful for treatment of patients with rheumatoid arthritis and osteoarthritis.

Cannabimimetic Properties of Ajulemic Acid

Side effects of marijuana-based drugs and synthetic analogs of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), including sedation and dysphoria, have limited their therapeutic application. Ajulemic acid (AJA), a side-chain synthetic analog of Delta(8)-THC-11-oic acid, has been reported to have anti-inflammatory properties without producing undesired psychoactive effects. Moreover, it has been suggested that AJA does not interact with cannabinoid receptors to produce its pharmacological effects. The aim of the present study was to conduct a thorough evaluation of the pharmacological effects of AJA then to determine whether actions at cannabinoid receptor (CB)(1) mediated these effects. This study evaluated the psychoactive and analgesic effects of AJA by examining its cannabimimetic properties in ICR mice (i.e., antinociception, catalepsy, hypothermia, and hypomobility), its discriminative stimulus effects in Long Evans rats trained in a two-lever Delta(9)-THC (3.0 mg/kg) versus vehicle drug discrimination procedure, and its antihyperalgesia effects in a rat model of inflammatory pain [complete Freund's adjuvant (CFA)-induced mechanical hyperalgesia]. Lastly, antagonism tests with SR 141716A [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboximide hydrochloride], CB(1) receptor antagonist, were conducted. These studies demonstrated that AJA shares a number of CB(1)-mediated pharmacological properties with Delta(9)-THC, including cannabimimetic, discriminative stimulus, and antihyperalgesic effects. Furthermore, a separation between doses that produced antinociception and those that produced the other pharmacological effects in mice was not observed. Moreover, AJA showed nearly equipotency for therapeutic efficacy in the CFA model and for substitution in Delta(9)-THC discrimination. In summary, this study shows that AJA, like Delta(9)-THC, exhibits psychoactive and therapeutic effects at nearly equal doses in preclinical models, suggesting similar limitations in their putative therapeutic profiles.