Attenuation of the ovalbumin-induced allergic airway response by cannabinoid treatment in A/J mice

Cannabinol modulates the endocannabinoid system and shows TRPV1-mediated anti-inflammatory properties in human keratinocytes

Cannabinol (CBN) is a secondary metabolite of cannabis whose beneficial activity on inflammatory diseases of human skin has attracted increasing attention. Here, we sought to investigate the possible modulation by CBN of the major elements of the endocannabinoid system (ECS), in both normal and lipopolysaccharide-inflamed human keratinocytes (HaCaT cells). CBN was found to increase the expression of cannabinoid receptor 1 (CB1) at gene level and that of vanilloid receptor 1 (TRPV1) at protein level, as well as their functional activity. In addition, CBN modulated the metabolism of anandamide (AEA) and 2-arachidonoylglicerol (2-AG), by increasing the activities of N-acyl phosphatidylethanolamines-specific phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH)-the biosynthetic and degradative enzyme of AEA-and that of monoacylglycerol lipase (MAGL), the hydrolytic enzyme of 2-AG. CBN also affected keratinocyte inflammation by reducing the release of pro-inflammatory interleukin (IL)-8, IL-12, and IL-31 and increasing the release of anti-inflammatory IL-10. Of note, the release of IL-31 was mediated by TRPV1. Finally, the mitogen-activated protein kinases (MAPK) signaling pathway was investigated in inflamed keratinocytes, demonstrating a specific modulation of glycogen synthase kinase 3β (GSK3β) upon treatment with CBN, in the presence or not of distinct ECS-directed drugs. Overall, these results demonstrate that CBN modulates distinct ECS elements and exerts anti-inflammatory effects-remarkably via TRPV1-in human keratinocytes, thus holding potential for both therapeutic and cosmetic purposes.

The Impact of the CB2 Cannabinoid Receptor in Inflammatory Diseases: An Update

The emergence of inflammatory diseases is a heavy burden on modern societies. Cannabis has been used for several millennia to treat inflammatory disorders such as rheumatism or gout. Since the characterization of cannabinoid receptors, CB1 and CB2, the potential of cannabinoid pharmacotherapy in inflammatory conditions has received great interest. Several studies have identified the importance of these receptors in immune cell migration and in the production of inflammatory mediators. As the presence of the CB2 receptor was documented to be more predominant in immune cells, several pharmacological agonists and antagonists have been designed to treat inflammation. To better define the potential of the CB2 receptor, three online databases, PubMed, Google Scholar and clinicaltrial.gov, were searched without language restriction. The full texts of articles presenting data on the endocannabinoid system, the CB2 receptor and its role in modulating inflammation in vitro, in animal models and in the context of clinical trials were reviewed. Finally, we discuss the clinical potential of the latest cannabinoid-based therapies in inflammatory diseases.

Cannabinol Regulates the Expression of Cell Cycle-Associated Genes in Motor Neuron-like NSC-34: A Transcriptomic Analysis

Cannabinoids are reported to have neuroprotective properties and play a role in neurogenesis and neuroplasticity in in vitro and in vivo models. Cannabinol (CBN) is a minor cannabinoid produced by the degradation of Δ9-tetrahydrocannabinol in Cannabis sativa L. and exhibits anti-oxidant, analgesic, anti-bacterial, and anti-inflammatory effects. In this study, we explored the biological effects of 20 µM CBN (6.20 µg/mL) on differentiated NSC-34 cells by MTT assay and next-generation sequencing analysis on the transcriptome. KEGG and Gene Ontology enrichment analyses have been performed to evaluate potential CBN-associated processes. Our results highlighted the absence of any cytotoxic effect of CBN. The comparative transcriptomic analysis pointed out the downregulation of Cdkn2a, Cdkn2c and Cdkn2d genes, which are known to suppress the cell cycle. Ccne2, Cdk2, Cdk7, Anapc11, Anapc10, Cdc23, Cdc16, Anapc4, Cdc27, Stag1, Smc3, Smc1a, Nipbl, Pds5a, Pds5b, and Wapl genes, renowned for their role as cell cycle progression activators, were instead upregulated. Our work suggests that CBN regulates the expression of many genes related to the cell cycle, which are required for axonal maturation, migration, and synaptic plasticity, while not affecting the expression of genes involved in cell death or tumorigenesis.

Functionally-selective inhibition of threshold sodium currents and excitability in dorsal root ganglion neurons by cannabinol

Cannabinol (CBN), an incompletely understood metabolite for ∆9-tetrahydrocannabinol, has been suggested as an analgesic. CBN interacts with endocannabinoid (CB) receptors, but is also reported to interact with non-CB targets, including various ion channels. We assessed CBN effects on voltage-dependent sodium (Nav) channels expressed heterologously and in native dorsal root ganglion (DRG) neurons. Our results indicate that CBN is a functionally-selective, but structurally-non-selective Nav current inhibitor. CBN's main effect is on slow inactivation. CBN slows recovery from slow-inactivated states, and hyperpolarizes steady-state inactivation, as channels enter deeper and slower inactivated states. Multielectrode array recordings indicate that CBN attenuates DRG neuron excitability. Voltage- and current-clamp analysis of freshly isolated DRG neurons via our automated patch-clamp platform confirmed these findings. The inhibitory effects of CBN on Nav currents and on DRG neuron excitability add a new dimension to its actions and suggest that this cannabinoid may be useful for neuropathic pain.

The effects of subacute exposure to a water-soluble cannabinol compound in male mice

Background

Cannabinol (CBN) is one of the many cannabinoids present in Cannabis sativa and has been explored as a potential treatment for sleeplessness. The purpose of this study was to determine the physiological and behavioral effects of subacute exposure to therapeutic and low pharmacological levels of a mechanically formed, stabilized water-soluble cannabinol nano-emulsion (CBNight™).

Methods

Sixty-two male mice were randomly assigned to one of six treatment groups given CBNight™ at dosages designed to deliver 0mg (control) to 4 mg/kg of CBN daily via oral gavage for 14 days. In-cage behavior was observed at 30 minutes and at 2, 4, 8, and 16 hours after each dose. After 14 days, the mice were sacrificed and necropsied. Organs were weighed and inspected for gross abnormalities, and blood was collected via cardiac puncture for clinical chemistry.

Results

No dosage-dependent adverse effects on behavior, body mass, or blood chemistry were observed, except that the highest doses of CBNight™ were associated with significantly lower eosinophil counts.

Conclusions

The commercially available, water-soluble CBN compound employed in this study does not appear to cause adverse effects in mice; rather, it appears to be well tolerated at pharmacological levels. The findings of eosinopenia at higher doses of CBN and lack of hepatotoxicity at any dosage employed in this study have not been reported to date.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42238-022-00153-w.

Cannabinol: History, Syntheses, and Biological Profile of the Greatest "Minor" Cannabinoid

Cannabis (Cannabis sativa L.) is an outstanding source of bioactive natural products, with more than 150 different phytocannabinoids isolated throughout the decades; however, studies of their bioactivity have historically concentrated on the so-called "big four" [∆⁹-THC (1a), CBD (2a), CBG (3a) and CBC (4a)]. Among the remaining products, which have traditionally been referred to as "minor cannabinoids", cannabinol (CBN, 5a) stands out for its important repercussions and implications on the global scientific landscape. Throughout this review, we will describe why CBN (5a) deserves a prominent place within the so-called "cannabinome", providing an overview on its history, the syntheses developed, and its bioactivity, highlighting its promising pharmacological potential and the significant impact that the study of its chemistry had on the development of new synthetic methodologies.

Minor Phytocannabinoids: A Misleading Name but a Promising Opportunity for Biomedical Research

Despite the very large number of phytocannabinoids isolated from Cannabis (Cannabis sativa L.), bioactivity studies have long remained focused on the so called “Big Four” [Δ⁹-THC (1), CBD (2), CBG (3) and CBC (4)] because of their earlier characterization and relatively easy availability via isolation and/or synthesis. Bioactivity information on the chemical space associated with the remaining part of the cannabinome, a set of ca 150 compounds traditionally referred to as “minor phytocannabinoids”, is scarce and patchy, yet promising in terms of pharmacological potential. According to their advancement stage, we sorted the bioactivity data available on these compounds, better referred to as the “dark cannabinome”, into categories: discovery (in vitro phenotypical and biochemical assays), preclinical (animal models), and clinical. Strategies to overcome the availability issues associated with minor phytocannabinoids are discussed, as well as the still unmet challenges facing their development as mainstream drugs.

Endocannabinoid metabolism inhibition ameliorates ovalbumin-induced allergic airway inflammation and hyperreactivity in Guinea pigs

AIMS

Endocannabinoids are biologically active cannabinoid-related substances endogenously synthesized in many mammalian tissues. Mainly two enzymes carry out their degradation; Fatty Acid Amide Hydrolase (FAAH) and Monoacylglycerol Lipase (MAGL). Endocannabinoids are shown to affect the modulation of inflammatory processes and airway responsiveness. In the present study, we investigated the effects of FAAH and MAGL inhibitor treatments in experimental allergic airway inflammation in guinea pigs.

MATERIALS AND METHODS

Guinea pigs were sensitized and challenged by ovalbumin to induce an allergic asthma model. Then, the effects of FAAH inhibitor URB597, MAGL inhibitor JZL184, and dual (FAAH/MAGL) inhibitor JZL195 on airway inflammation and hyperreactivity were evaluated.

KEY FINDINGS

Ovalbumin challenge increased airway reactivity, IgE in serum, IL-4, and IL-13, and the percentage of eosinophils in bronchoalveolar lavage (BAL). In addition, inhibition of FAAH or MAGL enzymes leads to an increase in endocannabinoid levels. The selective inhibition of the FAAH enzyme prevented inflammation indicators such as cytokine production and inflammatory cell infiltration but had a negligible effect on airway hyperreactivity. However, the inhibition of the MAGL enzyme or dual inhibition of both FAAH and MAGL enzymes tent to moderate both pulmonary inflammation and airway hyperreactivity.

SIGNIFICANCE

We have previously demonstrated that modulation of endocannabinoid levels in the airways by FAAH or MAGL inhibition can be useful in preventing acute lung inflammation. The results of the present study further suggest that FAAH and MAGL inhibitor treatment can also be a promising strategy for bronchial hyperreactivity and airway inflammation in allergic asthma.

Effects of non-steroidal anti-inflammatory drugs and other eicosanoid pathway modifiers on antiviral and allergic responses: EAACI task force on eicosanoids consensus report in times of COVID-19

Non‐steroidal anti‐inflammatory drugs (NSAIDs) and other eicosanoid pathway modifiers are among the most ubiquitously used medications in the general population. Their broad anti‐inflammatory, antipyretic, and analgesic effects are applied against symptoms of respiratory infections, including SARS‐CoV‐2, as well as in other acute and chronic inflammatory diseases that often coexist with allergy and asthma. However, the current pandemic of COVID‐19 also revealed the gaps in our understanding of their mechanism of action, selectivity, and interactions not only during viral infections and inflammation, but also in asthma exacerbations, uncontrolled allergic inflammation, and NSAIDs‐exacerbated respiratory disease (NERD). In this context, the consensus report summarizes currently available knowledge, novel discoveries, and controversies regarding the use of NSAIDs in COVID‐19, and the role of NSAIDs in asthma and viral asthma exacerbations. We also describe here novel mechanisms of action of leukotriene receptor antagonists (LTRAs), outline how to predict responses to LTRA therapy and discuss a potential role of LTRA therapy in COVID‐19 treatment. Moreover, we discuss interactions of novel T2 biologicals and other eicosanoid pathway modifiers on the horizon, such as prostaglandin D2 antagonists and cannabinoids, with eicosanoid pathways, in context of viral infections and exacerbations of asthma and allergic diseases. Finally, we identify and summarize the major knowledge gaps and unmet needs in current eicosanoid research.

The cannabinoid WIN55212-2 impairs peanut allergic sensitization and promotes the generation of allergen-specific regulatory T cells

BACKGROUND

Cannabinoids are lipid-derived mediators with anti-inflammatory properties in different diseases. WIN55212-2, a non-selective synthetic cannabinoid, reduces immediate anaphylactic reactions in a mouse model of peanut allergy, but its capacity to prevent peanut allergic sensitization and the underlying mechanisms remains largely unknown.

OBJECTIVE

To investigate the capacity of WIN55212-2 to immunomodulate peanut-stimulated human dendritic cells (DCs) and peanut allergic sensitization in mice.

METHODS

Surface markers and cytokines were quantified by flow cytometry, ELISA and qPCR in human monocyte-derived DCs (hmoDCs) and T cell cocultures after stimulation with peanut alone or in the presence of WIN55212-2. Mice were epicutaneously sensitized with peanut alone or peanut/WIN55212-2. After peanut challenge, drop in body temperature, hematocrit, clinical symptoms, peanut-specific antibodies in serum and FOXP3⁺ regulatory (Treg) cells in spleen and lymph nodes were quantified. Splenocytes were stimulated in vitro with peanut to analyse allergen-specific T cell responses.

RESULTS

WIN55212-2 reduced peanut-induced hmoDC activation and promoted the generation of CD4⁺ CD127^- CD25⁺ FOXP3⁺ Treg cells, while reducing the induction of IL-5-producing T cells. In vivo, WIN55212-2 impaired the peanut-induced migration of DCs to lymph nodes and their maturation. WIN55212-2 significantly reduced the induction of peanut-specific IgE and IgG₁ antibodies in serum during epicutaneous peanut sensitization, reduced the clinical symptoms score upon peanut challenge and promoted the generation of allergen-specific FOXP3⁺ Treg cells.

CONCLUSIONS

The synthetic cannabinoid WIN55212-2 interferes with peanut sensitization and promotes tolerogenic responses, which might well pave the way for the development of novel prophylactic and therapeutic strategies for peanut allergy.

Sexual behaviors, cannabis, alcohol and monkeypox infection

The emergence of the monkeypox virus (MPXV) outbreak in 2022 is a worldwide health issue. The rapid increase of monkeypox cases caused the WHO to designate the escalating global monkeypox outbreak a Public Health Emergency of International Concern on July 23, 2022. The WHO has called on the group currently most affected by the virus, men who have sex with men (MSM), to limit their sexual partners. The diminution in number of sexual partners not only decreases the proportion of infected MSM but could also increases the number of days needed to reach a given infection level among the general population. Several behavioral factors could be associated with high levels of different sexual partners, such as cannabis use and alcohol consumption. Firstly, this review focuses on the association between cannabis and alcohol consumption and the number of sexual partners, and their possible impact on the current MPXV outbreak by impairing the immune responses. Secondly, this review investigated in the UK Biobank cohort the relationship between alcohol and cannabis use and the number of sexual partners. Among the 115,604 participants, 1.8% declared to be MSM, 1.9% to be WSW (women having sex with women), 43.3% men heterosexuals and 53.0% women heterosexuals. MSM and WSW showed higher lifetime sexual partners (N = 17.4 (SD:17.52) and N = 13.65 (SD: 13.21), respectively) compared to heterosexual men (N = 6.89 (SD: 9.47) and women (N = 5.19 (SD:6.56), p < 0.001. After adjustment for age, body mass index, lifetime sexual activity, educational and income levels, tobacco and cardiovascular diseases, cannabis use and alcohol consumption remained significantly associated with increase in the number of different sexual partners in all four subgroups. Thus, cannabis use and alcohol consumption may have two detrimental effects on the MPXV outbreak: by participating in the increase of the number of sexual partners which are mainly responsible for the augmentation of the number of new MPXV infected cases and by impairing the immune response to a viral infection. Health and safety policies should address the factors and practices, including chemsex, leading to an increase in risk of sexual behaviors responsible for MPXV dissemination in the worldwide population.

Minor Cannabinoids: Biosynthesis, Molecular Pharmacology and Potential Therapeutic Uses

The medicinal use of Cannabis sativa L. can be traced back thousands of years to ancient China and Egypt. While marijuana has recently shown promise in managing chronic pain and nausea, scientific investigation of cannabis has been restricted due its classification as a schedule 1 controlled substance. A major breakthrough in understanding the pharmacology of cannabis came with the isolation and characterization of the phytocannabinoids trans-Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and cannabidiol (CBD). This was followed by the cloning of the cannabinoid CB1 and CB2 receptors in the 1990s and the subsequent discovery of the endocannabinoid system. In addition to the major phytocannabinoids, Δ⁹-THC and CBD, cannabis produces over 120 other cannabinoids that are referred to as minor and/or rare cannabinoids. These cannabinoids are produced in smaller amounts in the plant and are derived along with Δ⁹-THC and CBD from the parent cannabinoid cannabigerolic acid (CBGA). While our current knowledge of minor cannabinoid pharmacology is incomplete, studies demonstrate that they act as agonists and antagonists at multiple targets including CB1 and CB2 receptors, transient receptor potential (TRP) channels, peroxisome proliferator-activated receptors (PPARs), serotonin 5-HT_1a receptors and others. The resulting activation of multiple cell signaling pathways, combined with their putative synergistic activity, provides a mechanistic basis for their therapeutic actions. Initial clinical reports suggest that these cannabinoids may have potential benefits in the treatment of neuropathic pain, neurodegenerative diseases, epilepsy, cancer and skin disorders. This review focuses on the molecular pharmacology of the minor cannabinoids and highlights some important therapeutic uses of the compounds.

Selective activation of cannabinoid receptor 2 regulates Treg/Th17 balance to ameliorate neutrophilic asthma in mice

Background

The cannabinoid receptor 2 (CNR2) plays a critical role in relieving asthma, with the mechanism still unclear. We aimed to investigate the mechanism of the CNR2 agonist (β-caryophyllene, β-Car) in regulating the balance of regulatory T cells (Treg) and T helper cell 17 (Th17) and thus its role in asthma.

Methods

The study group of 50 pathogen-free female BALB/c mice were randomly divided at 6–8 weeks old into five groups of Control, Asthma, Asthma + β-Car (10 mg/kg), Asthma + β-Car + SR144528 (specific CNR2 antagonist, 3 mg/kg), and Asthma + β-Car + CMD178 (inhibitor of Treg cell, 10 mg/kg). ELISA was conducted to evaluate the main inflammatory cytokines [interleukin (IL)-6, IL-8, and tumor necrosis factor-α], and those secreted by Treg (transforming growth factor-β and IL-10), and Th17 (IL-17A and IL-22). Markers of Treg and Th17 cells were assessed by flow cytometry. In vitro, the CD4⁺ T cells were sorted and directed to differentiate to Treg and Th17 cells. The expression levels of CNR2, STAT5 and JNK1/2 were investigated by western blot and immunofluorescence assay.

Results

β-Car relieved neutrophilic asthma severity in mice by elevating the marker genes’ expression of Treg and inhibiting those of Th17, causing an increased proportion of Treg to Th17. β-Car also promoted the directed differentiation of CD4⁺ T cells into Treg, but not Th17. Activation of the CNR2 regulated the Treg/Th17 balance and relieved neutrophilic asthma possibly through promotion of phosphorylation of STAT5 and JNK1/2.

Conclusions

The effect of the selective CNR2 agonist activating STAT5 and JNK1/2 signaling was to change the Treg/Th17 balance and reduce the inflammatory reaction, thus ameliorating neutrophilic asthma in a mouse model.

The treatment of asthma using the Chinese Materia Medica

ETHNOPHARMACOLOGICAL RELEVANCE

Asthma is a costly global health problem that negatively influences the quality of life of patients. The Chinese Materia Medica (CMM) contains remedies that have been used for the treatment of asthma for millennia. This article strives to systematically summarize the current research progress so that more comprehensive examinations of various databases related to CMM anti-asthma drugs, can be performed, so as to sequentially provide effective basic data for development and application of anti-asthma drugs based on the CMM.

MATERIALS AND METHODS

The research data published over the past 20 years for asthma treatment based on traditional CMM remedies were retrieved and collected from libraries and online databases (PubMed, ScienceDirect, Elsevier, Spring Link, Web of Science, PubChem Compound, Wan Fang, CNKI, Baidu, and Google Scholar). Information was also added from classic CMM, literature, conference papers on classic herbal formulae, and dissertations (PhD or Masters) based on traditional Chinese medicine.

RESULTS

This review systematically summarizes the experimental studies on the treatment of asthma with CMM, covering the effective chemical components, typical asthma models, important mechanisms and traditional anti-asthma CMM formulae. The therapy value of the CMM for anti-asthma is clarified, and the original data and theoretical research foundation are provided for the development of new anti-asthmatic data and research for the CMM.

CONCLUSIONS

Substantial progress against asthma has been made through relevant experimental research based on the CMM. These advances improved the theoretical basis of anti-asthma drugs for CMM and provided a theoretical basis for the application of a asthma treatment that is unique. By compiling these data, it is expected that the CMM will now contain a clearer mechanism of action and a greater amount of practical data that can be used for future anti-asthma drug research.

Immunomodulation by cannabinoids: Current uses, mechanisms, and identification of data gaps to be addressed for additional therapeutic application

The endocannabinoid system plays a critical role in immunity and therefore its components, including cannabinoid receptors 1 and 2 (CB₁ and CB₂), are putative druggable targets for immune-mediated diseases. Whether modulating endogenous cannabinoid levels or interacting with CB₁ or CB₂ receptors directly, cannabinoids or cannabinoid-based therapeutics (CBTs) show promise as anti-inflammatory or immune suppressive agents. Herein we provide an overview of cannabinoid effects in animals and humans that provide support for the use of CBTs in immune-mediated disease such as multiple sclerosis (MS), inflammatory bowel disease (IBD), asthma, arthritis, diabetes, human immunodeficiency virus (HIV), and HIV-associated neurocognitive disorder (HAND). This is not an exhaustive review of cannabinoid effects on immune responses, but rather provides: (1) key studies in which initial and/or novel observations were made in animal studies; (2) critical human studies including meta-analyses and randomized clinical trials (RCTs) in which CBTs have been assessed; and (3) evidence for the role of CB₁ or CB₂ receptors in immune-mediated diseases through genetic analyses of single nucleotide polymorphisms (SNPs) in the CNR1 and CNR2 genes that encode CB₁ or CB₂ receptors, respectively. Perhaps most importantly, we provide our view of data gaps that exist, which if addressed, would allow for more rigorous evaluation of the efficacy and risk to benefit ratio of the use of cannabinoids and/or CBTs for immune-mediated diseases.

The effects of fatty acid amide hydrolase and monoacylglycerol lipase inhibitor treatments on lipopolysaccharide-induced airway inflammation in mice

Cannabinoids and the endocannabinoid system significantly contributes to the airway inflammation. Fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) are two main enzymes responsible for the metabolism of the endocannabinoids anandamide (AEA) and 2-arachydonoyl glycerol (2-AG), respectively. In the present study, we aimed to investigate the effects of local and systemic FAAH and MAGL inhibitor treatments in experimental airway inflammation and tracheal hyperreactivity in mice. Airway inflammation was induced by intranasal (i.n.) lipopolysaccharide (LPS) application (60 μl; 0,1 mg/ml in PBS) to mice and the control group received PBS. Systemic (intraperitoneal (i.p.)) or local (i.n.) FAAH inhibitor URB597 and MAGL inhibitor JZL184 treatments were administered 1h before LPS/PBS application. Fourty 8 h after LPS/PBS application, tracheas were removed to assess airway reactivity, and the lungs and bronchoalveolar lavage (BAL) fluids were isolated for histopathological evaluation, cytokine and endocannabinoid measurements. LPS application lead to an increase in 5-hydroxytryptamine (5-HT) contractions in isolated tracheal rings while carbachol contractions remained unchanged. The increased 5-HT contractions were prevented by both systemic and local URB597 and JZL184 treatments. Systemic treatment with URB597 and JZL184, and local treatment with JZL184 reduced peribronchial and paranchymal inflammation in the LPS group while i.n. application of URB597 worsened the inflammation in the lungs. Systemic URB597 treatment increased lung AEA level whereas it had no effect on 2-AG level. However, JZL184 treatment increased 2-AG level by either systemic or local application, and also elevated AEA level. Inflammation-induced increase in neutrophil numbers was only prevented by systemic URB597 treatment. However, both URB597 and JZL184 treatments abolished the increased TNF-α level either they are administered systemically or locally. These results indicate that FAAH and MAGL inhibition may have a protective effect in airway inflammation and airway hyperreactivity, and therefore their therapeutic potential for airway diseases should be further investigated.

Endocannabinoid System in the Airways

Cannabinoids and the mammalian endocannabinoid system is an important research area of interest and attracted many researchers because of their widespread biological effects. The significant immune-modulatory role of cannabinoids has suggested their therapeutic use in several inflammatory conditions. Airways are prone to environmental irritants and stimulants, and increased inflammation is an important process in most of the respiratory diseases. Therefore, the main strategies for treating airway diseases are suppression of inflammation and producing bronchodilation. The ability of cannabinoids to induce bronchodilation and modify inflammation indicates their importance for airway physiology and pathologies. In this review, the contribution of cannabinoids and the endocannabinoid system in the airways are discussed, and the existing data for their therapeutic use in airway diseases are presented.

The current state and future perspectives of cannabinoids in cancer biology

To date, cannabinoids have been allowed in the palliative medicine due to their analgesic and antiemetic effects, but increasing number of preclinical studies indicates their anticancer properties. Cannabinoids exhibit their action by a modulation of the signaling pathways crucial in the control of cell proliferation and survival. Many in vitro and in vivo experiments have shown that cannabinoids inhibit proliferation of cancer cells, stimulate autophagy and apoptosis, and have also a potential to inhibit angiogenesis and metastasis. In this review, we present an actual state of knowledge regarding molecular mechanisms of cannabinoids' anticancer action, but we discuss also aspects that are still not fully understood such as the role of the endocannabinoid system in a carcinogenesis, the impact of cannabinoids on the immune system in the context of cancer development, or the cases of a stimulation of cancer cells' proliferation by cannabinoids. The review includes also a summary of currently ongoing clinical trials evaluating the safety and efficacy of cannabinoids as anticancer agents.

Oral administration of cannabis with lipids leads to high levels of cannabinoids in the intestinal lymphatic system and prominent immunomodulation

Cannabidiol (CBD) and ∆⁹-tetrahydrocannabinol (THC) have well documented immunomodulatory effects in vitro, but not following oral administration in humans. Here we show that oral co-administration of cannabinoids with lipids can substantially increase their intestinal lymphatic transport in rats. CBD concentrations in the lymph were 250-fold higher than in plasma, while THC concentrations in the lymph were 100-fold higher than in plasma. Since cannabinoids are currently in clinical use for the treatment of spasticity in multiple sclerosis (MS) patients and to alleviate nausea and vomiting associated with chemotherapy in cancer patients, lymphocytes from those patients were used to assess the immunomodulatory effects of cannabinoids. The levels of cannabinoids recovered in the intestinal lymphatic system, but not in plasma, were substantially above the immunomodulatory threshold in murine and human lymphocytes. CBD showed higher immunosuppressive effects than THC. Moreover, immune cells from MS patients were more susceptible to the immunosuppressive effects of cannabinoids than those from healthy volunteers or cancer patients. Therefore, administering cannabinoids with a high-fat meal or in lipid-based formulations has the potential to be a therapeutic approach to improve the treatment of MS, or indeed other autoimmune disorders. However, intestinal lymphatic transport of cannabinoids in immunocompromised patients requires caution.

From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology

Apart from having been used and misused for at least four millennia for, among others, recreational and medicinal purposes, the cannabis plant and its most peculiar chemical components, the plant cannabinoids (phytocannabinoids), have the merit to have led humanity to discover one of the most intriguing and pleiotropic endogenous signaling systems, the endocannabinoid system (ECS). This review article aims to describe and critically discuss, in the most comprehensive possible manner, the multifaceted aspects of 1) the pharmacology and potential impact on mammalian physiology of all major phytocannabinoids, and not only of the most famous one Δ9-tetrahydrocannabinol, and 2) the adaptive pro-homeostatic physiological, or maladaptive pathological, roles of the ECS in mammalian cells, tissues, and organs. In doing so, we have respected the chronological order of the milestones of the millennial route from medicinal/recreational cannabis to the ECS and beyond, as it is now clear that some of the early steps in this long path, which were originally neglected, are becoming important again. The emerging picture is rather complex, but still supports the belief that more important discoveries on human physiology, and new therapies, might come in the future from new knowledge in this field.

Cannabinoid receptor 2 augments eosinophil responsiveness and aggravates allergen-induced pulmonary inflammation in mice

Background

Accumulation of activated eosinophils in tissue is a hallmark of allergic inflammation. The endocannabinoid 2‐arachidonoylglycerol (2‐AG) has been proposed to elicit eosinophil migration in a CB₂ receptor/G_i/o‐dependent manner. However, it has been claimed recently that this process may also involve other mechanisms such as cytokine priming and the metabolism of 2‐AG into eicosanoids. Here, we explored the direct contribution of specific CB₂ receptor activation to human and mouse eosinophil effector function in vitro and in vivo.

Methods

In vitro studies including CB₂ expression, adhesion and migratory responsiveness, respiratory burst, degranulation, and calcium mobilization were conducted in human peripheral blood eosinophils and mouse bone marrow‐derived eosinophils. Allergic airway inflammation was assessed in mouse models of acute OVA‐induced asthma and directed eosinophil migration.

Results

CB₂ expression was significantly higher in eosinophils from symptomatic allergic donors. The selective CB₂ receptor agonist JWH‐133 induced a moderate migratory response in eosinophils. However, short‐term exposure to JWH‐133 potently enhanced chemoattractant‐induced eosinophil shape change, chemotaxis, CD11b surface expression, and adhesion as well as production of reactive oxygen species. Receptor specificity of the observed effects was confirmed in eosinophils from CB₂ knockout mice and by using the selective CB₂ antagonist SR144528. Of note, systemic application of JWH‐133 clearly primed eosinophil‐directed migration in vivo and aggravated both AHR and eosinophil influx into the airways in a CB₂‐specific manner. This effect was completely absent in eosinophil‐deficient ∆dblGATA mice.

Conclusion

Our data indicate that CB₂ may directly contribute to the pathogenesis of eosinophil‐driven diseases. Moreover, we provide new insights into the molecular mechanisms underlying the CB₂‐mediated priming of eosinophils. Hence, antagonism of CB₂ receptors may represent a novel pharmacological approach for the treatment of allergic inflammation and other eosinophilic disorders.

The effect of cannabinoids on dinitrofluorobenzene-induced experimental asthma in mice

Cannabinoids have anti-inflammatory effects and can produce bronchodilation in the airways. We have investigated the effects of cannabinoids on tracheal hyperreactivity and airway inflammation in dinitrofluorobenzene (DNFB)-induced experimental non-atopic asthma in mice. 5-hydroxytryptamine (5-HT)-induced contraction response was enhanced while carbachol- and electrical field stimulation-induced contractions, and isoprenaline-induced relaxation responses were remained unchanged in DNFB group. The increased 5-HT-induced contractions were inhibited by incubation with either atropine or tetrodotoxin. DNFB application resulted in increased macrophage number in the bronchoalveolar lavage fluid (BALF). In vivo ACEA (CB1 agonist) treatment prevented the increase in 5-HT contractions, while JWH133 (CB2 agonist) had no effect. However, neither ACEA nor JWH133 prevented the increase in macrophage number in BALF. In vitro ACEA incubation also inhibited the increase in 5-HT contraction in DNFB group. These results show that cannabinoid CB1 receptor agonist can prevent tracheal hyperreactivity to 5-HT in DNFB-induced non-atopic asthma in mice.

Targeting Immunomodulatory Agents to the Gut-Associated Lymphoid Tissue

In addition to fluid haemostasis and lipid absorption, the lymphatic system and lymphoid tissues serve as the major host of immune cells where immune responses are evoked. Impaired function of the immune system might lead to serious diseases which are often treated by immunomodulators. This chapter briefly explores the physiology of an important part of the lymphatic system, the gut-associated lymphoid tissues (GALT). Currently used strategies for targeting GALT by immunomodulators for enhanced activity and/or decreased side effects are discussed. Strategies range from simple oral co-administration of immunomodulators with lipids to more advanced lipid-based formulations, polymer-based nanoparticle formulations and prodrugs. These targeting approaches successfully increase the concentration of immunomodulators achieved in the GALT and, more importantly, enhance immunomodulatory effects. Therefore, targeting immunomodulators to GALT represent a promising approach in the treatment of diseases where the immune system is actively involved.

Modulation of HIVGP120 Antigen-Specific Immune Responses In Vivo by Δ9-Tetrahydrocannabinol

Approximately 25 % of HIV patients use marijuana for its putative therapeutic benefit; however, it is unknown how cannabinoids affect the immune status of HIV patients. Previously, a surrogate in vitro mouse model was established, which induced CD8(+) T cell proliferation and gp120-specific IFNγ production. ∆(9)-Tetrahydrocannabinol (THC), the predominant psychoactive compound in marijuana, suppressed or enhanced the responses depending on the magnitude of cellular activation. The purpose of the current study was to investigate whether THC produced similar effects in vivo and therefore a mouse model to induce HIVgp120-specific immune responses was established. A gp120-expressing plasmid, pVRCgp120, or a vector plasmid, pVRC2000, was injected intramuscularly into mice, which were also dosed with THC orally. The gp120-specific IFNγ and IL-2 responses were detected when splenocytes were restimulated with gp120-derived peptide 81 (IIGDIRQAHCNISRA), which was identified as being immunodominant. Various cellular populations were activated in response to pVRCgp120 stimulation followed by peptide restimulation, as evidenced by increased expression levels of activation markers (e.g., CD69, CD80, and major histocompatibility complex II [MHC II]). The IFNγ response and cellular activation were enhanced by THC in C57Bl/6 wild type (WT) mice but suppressed or not affected by THC in cannabinoid receptor 1 (CB1) and 2 (CB2) knockout (CB1 (-/-)CB2 (-/-)) mice. Furthermore, CB1 (-/-)CB2 (-/-) mice exhibited augmented IFNγ production when compared to WT mice in the absence of THC. Collectively, our findings demonstrate that under certain conditions, THC enhances HIV antigen-specific immune responses, which occurs through CB1/CB2-dependent and -independent mechanisms.

Regulation of inflammation by cannabinoids, the endocannabinoids 2-arachidonoyl-glycerol and arachidonoyl-ethanolamide, and their metabolites

2-Arachidonoyl-glycerol (2-AG) and arachidonyl-ethanolamide (AEA) are endocannabinoids that have been implicated in many physiologic disorders, including obesity, metabolic syndromes, hepatic diseases, pain, neurologic disorders, and inflammation. Their immunomodulatory effects are numerous and are not always mediated by cannabinoid receptors, reflecting the presence of an arachidonic acid (AA) molecule in their structure, the latter being the precursor of numerous bioactive lipids that are pro- or anti-inflammatory. 2-AG and AEA can thus serve as a source of AA but can also be metabolized by most eicosanoid biosynthetic enzymes, yielding additional lipids. In this regard, enhancing endocannabinoid levels by using endocannabinoid hydrolysis inhibitors is likely to augment the levels of these lipids that could regulate inflammatory cell functions. This review summarizes the metabolic pathways involved in the biosynthesis and metabolism of AEA and 2-AG, as well as the biologic effects of the 2-AG and AEA lipidomes in the regulation of inflammation.

The effects of cannabidiol on the antigen-induced contraction of airways smooth muscle in the guinea-pig

(-)-Δ(9)-Tetrahydrocannabinol has been demonstrated to have beneficial effects in the airways, but its psychoactive effects preclude its therapeutic use for the treatment of airways diseases. In the present study we have investigated the effects of (-)-cannabidiol, a non-psychoactive component of cannabis for its actions on bronchial smooth muscle in vitro and in vivo. Guinea-pig bronchial smooth muscle contractions induced by exogenously applied spasmogens were measured isometrically. In addition, contractile responses of bronchial smooth muscle from ovalbumin-sensitized guinea-pigs were investigated in the absence or presence of (-)-cannabidiol. Furthermore, the effect of (-)-cannabidiol against ovalbumin-induced airway obstruction was investigated in vivo in ovalbumin-sensitized guinea-pigs. (-)-Cannabidiol did not influence the bronchial smooth muscle contraction induced by carbachol, histamine or neurokinin A. In contrast, (-)-cannabidiol inhibited anandamide- and virodhamine-induced responses of isolated bronchi. A fatty acid amide hydrolase inhibitor, phenylmethanesulfonyl fluoride reversed the inhibitory effect of (-)-cannabidiol on anandamide-induced contractions. In addition, (-)-cannabidiol inhibited the contractile response of bronchi obtained from allergic guinea-pigs induced by ovalbumin. In vivo, (-)-cannabidiol reduced ovalbumin-induced airway obstruction. In conclusion, our results suggest that cannabidiol can influence antigen-induced airway smooth muscle tone suggesting that this molecule may have beneficial effects in the treatment of obstructive airway disorders.

Cannabinoid 2 (CB2) receptor involvement in the down-regulation but not up-regulation of serum IgE levels in immunized mice

Marijuana cannabinoids such as Δ(9)-tetrahydrocannabinol (THC) have been shown in experimental systems to bias T helper immunity towards Th2 and away from Th1. This effect if broadly applicable to humans could have important implications in Th2-mediated diseases such as allergy. In the current study, we examined the effect of cannabinoids on serum immunoglobulin IgE levels in immunized mice and also examined the role of cannabinoid receptors in the response. The method involved pre-injecting mice with cannabinoid receptor agonists and antagonists followed 18-24 h later with an immunizing injection with two different antigen/adjuvant combinations. This treatment was followed 2-3 weeks later with a booster injection of antigen and the subsequent bleeding of mice 1-2 weeks later for serum immunoglobulin analysis by ELISA. Our results showed that THC injection enhanced total IgE serum levels in response to antigen immunization even under conditions of deficient cannabinoid receptor 2 (CB2) and cannabinoid receptor 1 (CB1) activity and furthermore the increase in IgE was accompanied by a decrease in serum IgG2a. In addition, we observed that l-α-lysophosphatidyliniositol (LPI) increased serum IgE levels and that IgE levels were higher in CB2 deficient mice and suppressed by the CB2 agonist, Gp1a. These results suggest that in this IgE induction model in mice, non-selective cannabinoids such as THC increase IgE through receptors other than CB1 and CB2 but that CB2 receptors do play a suppressive role in the control of serum IgE levels.

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.

Is lipid signaling through cannabinoid 2 receptors part of a protective system?

The mammalian body has a highly developed immune system which guards against continuous invading protein attacks and aims at preventing, attenuating or repairing the inflicted damage. It is conceivable that through evolution analogous biological protective systems have been evolved against non-protein attacks. There is emerging evidence that lipid endocannabinoid signaling through cannabinoid 2 (CB₂) receptors may represent an example/part of such a protective system/armamentarium. Inflammation/tissue injury triggers rapid elevations in local endocannabinoid levels, which in turn regulate signaling responses in immune and other cells modulating their critical functions. Changes in endocannabinoid levels and/or CB₂ receptor expressions have been reported in almost all diseases affecting humans, ranging from cardiovascular, gastrointestinal, liver, kidney, neurodegenerative, psychiatric, bone, skin, autoimmune, lung disorders to pain and cancer, and modulating CB₂ receptor activity holds tremendous therapeutic potential in these pathologies. While CB₂ receptor activation in general mediates immunosuppressive effects, which limit inflammation and associated tissue injury in large number of pathological conditions, in some disease states activation of the CB₂ receptor may enhance or even trigger tissue damage, which will also be discussed alongside the protective actions of the CB₂ receptor stimulation with endocannabinoids or synthetic agonists, and the possible biological mechanisms involved in these effects.

Cannabinoids and the immune system: an overview

Cannabinoids can influence the immune network. Data on the impact of exogenous cannabinoid ligands on immune function serve not only to understand how the endocannabinoid system modulates immune phenomena associated with infection or inflammation, but also to identify therapeutic targets for immune diseases. Cannabinoids can modulate immune reactions in the periphery but also in the brain, influence T cell subset balance and cytokine expression and play a role in the balance between neuroinflammation and neurodegeneration. Immune cells can synthesize endocannabinoids and also be influenced by cannabinoid analogues. Cannabinoid receptors show different expression on immune cells depending on activation status and stimuli. The complexity of relation between cannabinoid ligands of various classes and cannabinoid receptors brought the need to refine the simple conceptual frame of agonist-antagonists and offered potential implications for understanding interactions in pathological conditions. The immune influence of cannabinoid ligands is not fully elucidated. However, aspects of their immunomodulatory effects provide the basis for a context-dependent targeted therapeutic approach, thus leading to the possibility for the use of cannabinoids in the treatment of inflammatory disease.

Current status and challenges of cytokine pharmacology

The major concern of pharmacology about cytokines has originated from plentiful data showing association between gross changes in their production and pathophysiological processes. Despite the enigmatic role of cytokines in diseases, a number of them have become a subject of cytokine and anti-cytokine immunotherapies. Production of cytokines can be influenced by many endogenous and exogenous stimuli including drugs. Cells of the immune system, such as macrophages and lymphocytes, are richly endowed with receptors for the mediators of physiological functions, such as biogenic amines, adenosine, prostanoids, steroids, etc. Drugs, agonists or antagonists of these receptors can directly or indirectly up- and down-regulate secretion of cytokines and expression of cytokine receptors. Vice versa, cytokines interfere with drug pharmacokinetics and pharmacodynamics through the interactions with cytochrome P450 and multiple drug resistance proteins. The aim of the review is to encourage more intensive studies in these fields of cytokine pharmacology. It also outlines major areas of searching promising candidates for immunotherapeutic interventions.

Silibinin attenuates antigen-specific IgE production through the modulation of Th1/Th2 balance in ovalbumin-sensitized BALB/c mice

The effect of silibinin on antigen-specific antibody production and T-cell cytokine expression was investigated. BALB/c mice were either left untreated or administered daily with vehicle (VH; saline) and/or silibinin (200 or 400 mg/kg) by gavage for 3 consecutive days prior to sensitization with ovalbumin (OVA). The antibody production in the serum and T-cell-derived cytokine expression by splenocytes were determined 7 days post OVA sensitization. Our results demonstrated that the production of OVA-specific serum IgE and total IgE was significantly attenuated by silibinin treatment, whereas OVA-specific IgG(2a) was markedly enhanced. In parallel with the differential modulation of the production of IgG(2a) and IgE, treatment of OVA-sensitized mice with silibinin markedly increased and decreased the production of IFN-gamma and IL-4, respectively, by splenocytes cultured in the presence of OVA. Together, these results suggest that silibinin treatment polarizes the Th1/Th2 immune balance toward the Th1-dominant direction, which may be beneficial against IgE-mediated allergy.

Suppression of T cell costimulator ICOS by Delta9-tetrahydrocannabinol

Inducible costimulator (ICOS), a prototypic T cell costimulator, is induced on activated T cells. ICOS regulates T cell activation and Th cell differentiation and is principally involved in humoral immune responses. Previous work showed that T cell accessory function is modulated by the plant-derived cannabinoid, delta-9-tetrahydrocannabinol (Delta(9)-THC). In light of an emerging role by ICOS in T cell-mediated immunity, the objective of this study was to investigate the effect of Delta(9)-THC on ICOS in activated mouse T cells. Induction of ICOS mRNA levels by phorbol ester (PMA) plus ionomycin (Io) activation in mouse splenocytes was attenuated by Delta(9)-THC in a concentration-related manner. Similar results were obtained in the mouse T cell line, EL4.IL-2. Anti-CD3/CD28 induced ICOS expression on CD4(+) splenic T cells, which was suppressed by Delta(9)-THC in a time- and concentration-related manner. The PMA/Io-induced icos promoter luciferase reporter activity was also down-regulated by Delta(9)-THC, suggesting that the suppression of ICOS expression by Delta(9)-THC occurs at the transcriptional level. Moreover, transcriptional activation of the NFAT was also down-regulated by Delta(9)-THC as shown by a NFAT luciferase reporter assay, which is consistent with a putative role of NFAT in regulating ICOS expression. Collectively, Delta(9)-THC suppresses ICOS expression in activated T cells, and this suppression may be related, in part, to its modulation of NFAT signaling. The emerging role of ICOS in a wide range of immune-related diseases also suggests that it may represent a potential therapeutic target, which could be modulated by cannabinoid compounds.

Effects of targeted deletion of cannabinoid receptors CB1 and CB2 on immune competence and sensitivity to immune modulation by Delta9-tetrahydrocannabinol

The role of cannabinoid receptors, CB1 and CB2, in immune competence and modulation by Delta9-tetrahydrocannabinol (Delta9-THC) was investigated in CB1(-/-)/CB2(-/-) mice. Immunofluorescence analysis of splenic leukocytes showed no significant differences in the percentage of T cell subsets, B cells, or macrophages between wild-type and CB1(-/-)/CB2(-/-) mice. Lymphoproliferative control responses to PHA, phorbol ester plus ionomycin, or LPS and sensitivity to suppression by Delta9-THC showed no profound differences between the two genotypes, although some differences were observed in control baseline responses. Likewise, similar control responses and sensitivity to Delta9-THC were observed in mixed lymphocyte responses (MLR) and in IL-2 and IFN-gamma production in both genotypes. Conversely, humoral immune responses showed a markedly different profile of activity. Delta9-THC suppressed the in vivo T cell-dependent, anti-sheep RBC (anti-sRBC) IgM antibody-forming cell (AFC) response in wild-type but not in CB1(-/-)/CB2(-/-) mice, and the in vitro anti-sRBC IgM response in CB1(-/-)/CB2(-/-) splenocytes was too low to rigorously assess CB1/CB2 involvement in modulation by Delta9-THC. Conversely, comparable in vitro IgM AFC control responses to LPS and CD40 ligand (CD40L) activation were observed in the two genotypes. Interestingly, LPS-induced IgM responses were refractory to suppression by Delta9-THC, regardless of genotype, and CD40L-induced IgM responses were only suppressed by Delta9-THC in wild-type but not in CB1(-/-)/CB2(-/-) B cells. Collectively, we demonstrate differential involvement of CB1 and/or CB2 in immune modulation by Delta9-THC and in some control responses. Moreover, CB1/CB2 involvement was observed in humoral responses requiring CD40-initiated signaling for suppression by Delta9-THC.

Activation of cannabinoid receptors prevents antigen-induced asthma-like reaction in guinea pigs

In this study we evaluated the effects of the CB₁/CB₂ cannabinoid receptor agonist CP55, 940 (CP) on antigen-induced asthma-like reaction in sensitized guinea pigs and we tested the ability of the specific CB2 receptor antagonist SR144528 (SR) and CB1 receptor antagonist AM251 (AM) to interfere with the effects of CP. Ovalbumin-sensitized guinea pigs placed in a respiratory chamber were challenged with the antigen given by aerosol. CP (0.4 mg/kg b.wt.) was given i.p. 3 hrs before ovalbumin challenge. Sixty minutes before CP administration, some animals were treated i.p. with either AM, or SR, or both (0.1 mg/kg b.wt.). Respiratory parameters were recorded and quantified. Lung tissue specimens were then taken for histopathological and morphometric analyses and for eosinophilic major basic protein immunohistochemistry. Moreover, myeloperoxidase activity, 8-hydroxy-2-deoxyguanosine, cyclic adenosine monophosphate (cAMP) and guanosine monophosphate (cGMP) levels, and CB₁ and CB₂ receptor protein expression by Western blotting were evaluated in lung tissue extracts. In the bronchoalveolar lavage fluid, the levels of prostaglandin D₂ and tumour necrosis factor-α TNF-α were measured. Ovalbumin challenge caused marked abnormalities in the respiratory, morphological and biochemical parameters assayed. Treatment with CP significantly reduced these abnormalities. Pre-treatment with SR, AM or both reverted the protective effects of CP, indicating that both CB₁ and CB₂ receptors are involved in lung protection. The noted treatments did not change the expression of cannabinoid receptor proteins, as shown by Western blotting. These findings suggest that targeting cannabinoid receptors could be a novel preventative therapeutic strategy in asthmatic patients.

Virodhamine and CP55,940 modulate cAMP production and IL-8 release in human bronchial epithelial cells

BACKGROUND AND PURPOSE

We investigated expression of cannabinoid receptors and the effects of the endogenous cannabinoid virodhamine and the synthetic agonist CP55,940 on cAMP accumulation and interleukin-8 (IL-8) release in human bronchial epithelial cells.

EXPERIMENTAL APPROACH

Human bronchial epithelial (16HBE14o(-)) cells were used. Total mRNA was isolated and cannabinoid receptor mRNAs were detected by RT-PCR. Expression of CB(1) and CB(2) receptor proteins was detected with Western blotting using receptor-specific antibodies. cAMP accumulation was measured by competitive radioligand binding assay. IL-8 release was measured by ELISA.

KEY RESULTS

CB(1) and CB(2) receptor mRNAs and proteins were found. Both agonists concentration-dependently decreased forskolin-induced cAMP accumulation. This effect was inhibited by the CB(2) receptor antagonist SR144528, and was sensitive to Pertussis toxin (PTX), suggesting the involvement of CB(2) receptors and G(i/o)-proteins. Cell pretreatment with PTX unmasked a stimulatory component, which was blocked by the CB(1) receptor antagonist SR141716A. CB(2) receptor-mediated inhibition of cAMP production by virodhamine and CP55,940 was paralleled by inhibition of tumor necrosis factor-alpha (TNF-alpha) induced IL-8 release. This inhibition was insensitive to SR141716A. In the absence of agonist, SR144528 by itself reduced TNF-alpha induced IL-8 release.

CONCLUSIONS AND IMPLICATIONS

Our results show for the first time that 16HBE14o(-) cells respond to virodhamine and CP55,940. CB(1) and CB(2) receptor subtypes mediated activation and inhibition of adenylyl cyclase, respectively. Stimulation of the dominant CB(2) receptor signalling pathway diminished cAMP accumulation and TNF-alpha-induced IL-8 release. These observations may imply that cannabinoids exert anti-inflammatory properties in airways by modulating cytokine release.

Involvement of the cannabinoid CB2 receptor and its endogenous ligand 2-arachidonoylglycerol in oxazolone-induced contact dermatitis in mice

The possible involvement of 2-arachidonoylglycerol (2-AG), an endogenous ligand for the cannabinoid receptors (CB1 and CB2), in contact dermatitis in mouse ear was investigated. We found that the level of 2-AG was markedly elevated in the ear following a challenge with oxazolone in sensitized mice. Of note, the swelling following the challenge was suppressed by either the administration of SR144528, a CB2 receptor antagonist, immediately after sensitization, or the administration of SR144528 upon the challenge. The effect of AM251, a CB1 receptor antagonist, was marginal in either case. It seems apparent, therefore, that the CB2 receptor and its endogenous ligand 2-AG are closely involved in both the sensitization phase and the elicitation phase of oxazolone-induced contact dermatitis. In line with this, we found that Langerhans cells (MHC class II(+)) contain a substantial amount of CB2 receptor mRNA, whereas keratinocytes (MHC class II(-)) do not. We also obtained evidence that the expression of mRNAs for proinflammatory cytokines following a challenge with oxazolone was markedly suppressed by treatment with SR144528. We next examined whether the CB2 receptor and 2-AG participate in chronic contact dermatitis accompanied by the infiltration of tissues by eosinophils. The amount of 2-AG in mouse ear dramatically increased following repeated challenge with oxazolone. Importantly, treatment with SR144528 attenuated both the recruitment of eosinophils and ear swelling in chronic contact dermatitis induced by repeated challenge with oxazolone. These results strongly suggest that the CB2 receptor and 2-AG play important stimulative roles in the sensitization, elicitation, and exacerbation of allergic inflammation.

The endocannabinoid system as an emerging target of pharmacotherapy

The recent identification of cannabinoid receptors and their endogenous lipid ligands has triggered an exponential growth of studies exploring the endocannabinoid system and its regulatory functions in health and disease. Such studies have been greatly facilitated by the introduction of selective cannabinoid receptor antagonists and inhibitors of endocannabinoid metabolism and transport, as well as mice deficient in cannabinoid receptors or the endocannabinoid-degrading enzyme fatty acid amidohydrolase. In the past decade, the endocannabinoid system has been implicated in a growing number of physiological functions, both in the central and peripheral nervous systems and in peripheral organs. More importantly, modulating the activity of the endocannabinoid system turned out to hold therapeutic promise in a wide range of disparate diseases and pathological conditions, ranging from mood and anxiety disorders, movement disorders such as Parkinson's and Huntington's disease, neuropathic pain, multiple sclerosis and spinal cord injury, to cancer, atherosclerosis, myocardial infarction, stroke, hypertension, glaucoma, obesity/metabolic syndrome, and osteoporosis, to name just a few. An impediment to the development of cannabinoid medications has been the socially unacceptable psychoactive properties of plant-derived or synthetic agonists, mediated by CB(1) receptors. However, this problem does not arise when the therapeutic aim is achieved by treatment with a CB(1) receptor antagonist, such as in obesity, and may also be absent when the action of endocannabinoids is enhanced indirectly through blocking their metabolism or transport. The use of selective CB(2) receptor agonists, which lack psychoactive properties, could represent another promising avenue for certain conditions. The abuse potential of plant-derived cannabinoids may also be limited through the use of preparations with controlled composition and the careful selection of dose and route of administration. The growing number of preclinical studies and clinical trials with compounds that modulate the endocannabinoid system will probably result in novel therapeutic approaches in a number of diseases for which current treatments do not fully address the patients' need. Here, we provide a comprehensive overview on the current state of knowledge of the endocannabinoid system as a target of pharmacotherapy.

Cannabinoids and the immune system: potential for the treatment of inflammatory diseases?

Since the discovery of the cannabinoid receptors and their endogenous ligands, significant advances have been made in studying the physiological function of the endocannabinoid system. The presence of cannabinoid receptors on cells of the immune system and anecdotal and historical evidence suggesting that cannabis use has potent immuno-modulatory effects, has led to research directed at understanding the function and role of these receptors within the context of immunological cellular function. Studies from chronic cannabis smokers have provided much of the evidence for immunomodulatory effects of cannabis in humans, and animal and in vitro studies of immune cells such as T cells and macrophages have also provided important evidence. Cannabinoids can modulate both the function and secretion of cytokines from immune cells. Therefore, cannabinoids may be considered for treatment of inflammatory disease. This review article will highlight recent research on cannabinoids and how they interact with the immune system and also their potential use as therapeutic agents for a number of inflammatory disorders.