Anti-CD40, anti-CD3, and IL-2 stimulation induce contrasting changes in CB1 mRNA expression in mouse splenocytes

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.

Protective Application of Chinese Herbal Compounds and Formulae in Intestinal Inflammation in Humans and Animals

Intestinal inflammation is a chronic gastrointestinal disorder with uncertain pathophysiology and causation that has significantly impacted both the physical and mental health of both people and animals. An increasing body of research has demonstrated the critical role of cellular signaling pathways in initiating and managing intestinal inflammation. This review focuses on the interactions of three cellular signaling pathways (TLR4/NF-κB, PI3K-AKT, MAPKs) with immunity and gut microbiota to explain the possible pathogenesis of intestinal inflammation. Traditional medicinal drugs frequently have drawbacks and negative side effects. This paper also summarizes the pharmacological mechanism and application of Chinese herbal compounds (Berberine, Sanguinarine, Astragalus polysaccharide, Curcumin, and Cannabinoids) and formulae (Wumei Wan, Gegen-Qinlian decoction, Banxia xiexin decoction) against intestinal inflammation. We show that the herbal compounds and formulae may influence the interactions among cell signaling pathways, immune function, and gut microbiota in humans and animals, exerting their immunomodulatory capacity and anti-inflammatory and antimicrobial effects. This demonstrates their strong potential to improve gut inflammation. We aim to promote herbal medicine and apply it to multispecies animals to achieve better health.

RelB contributes to the survival, migration and lymphomagenesis of B cells with constitutively active CD40 signaling

Activation of CD40-signaling contributes to the initiation, progression and drug resistance of B cell lymphomas. We contributed to this knowledge by showing that constitutive CD40-signaling in B cells induces B cell hyperplasia and finally B cell lymphoma development in transgenic mice. CD40 activates, among others, the non-canonical NF-ĸB signaling, which is constitutively activated in several human B cell lymphomas and is therefore presumed to contribute to lymphopathogenesis. This prompted us to study the regulatory role of the non-canonical NF-ĸB transcription factor RelB in lymphomagenesis. To this end, we crossed mice expressing a constitutively active CD40 receptor in B cells with conditional RelB-KO mice. Ablation of RelB attenuated pre-malignant B cell expansion, and resulted in an impaired survival and activation of long-term CD40-stimulated B cells. Furthermore, we found that hyperactivation of non-canonical NF-кB signaling enhances the retention of B cells in the follicles of secondary lymphoid organs. RNA-Seq-analysis revealed that several genes involved in B-cell migration, survival, proliferation and cytokine signaling govern the transcriptional differences modulated by the ablation of RelB in long-term CD40-stimulated B cells. Inactivation of RelB did not abrogate lymphoma development. However, lymphomas occurred with a lower incidence and had a longer latency period. In summary, our data suggest that RelB, although it is not strictly required for malignant transformation, accelerates the lymphomagenesis of long-term CD40-stimulated B cells by regulating genes involved in migration, survival and cytokine signaling.

The Interplay between the Immune and the Endocannabinoid Systems in Cancer

The therapeutic potential of Cannabis sativa has been recognized since ancient times. Phytocannabinoids, endocannabinoids and synthetic cannabinoids activate two major G protein-coupled receptors, subtype 1 and 2 (CB1 and CB2). Cannabinoids (CBs) modulate several aspects of cancer cells, such as apoptosis, autophagy, proliferation, migration, epithelial-to-mesenchymal transition and stemness. Moreover, agonists of CB1 and CB2 receptors inhibit angiogenesis and lymphangiogenesis in vitro and in vivo. Low-grade inflammation is a hallmark of cancer in the tumor microenvironment (TME), which contains a plethora of innate and adaptive immune cells. These cells play a central role in tumor initiation and growth and the formation of metastasis. CB2 and, to a lesser extent, CB1 receptors are expressed on a variety of immune cells present in TME (e.g., T cells, macrophages, mast cells, neutrophils, NK cells, dendritic cells, monocytes, eosinophils). The activation of CB receptors modulates a variety of biological effects on cells of the adaptive and innate immune system. The expression of CB2 and CB1 on different subsets of immune cells in TME and hence in tumor development is incompletely characterized. The recent characterization of the human cannabinoid receptor CB2-G_i signaling complex will likely aid to design potent and specific CB2/CB1 ligands with therapeutic potential in cancer.

Chronic exercise modulates the cellular immunity and its cannabinoid receptors expression

The impact of performing exercise on the immune system presents contrasting effects on health when performed at different intensities. In addition, the consequences of performing chronic exercise have not been sufficiently studied in contrast to the effects of acute bouts of exercise. The porpoise of this work was to determine the effect that a popular exercise regimen (chronic/moderate/aerobic exercise) has on the proportion of different immune cell subsets, their function and if it affects the cannabinoid system with potentially functional implications on the immune system. A marked increase in several immune cell subsets and their expression of cannabinoid receptors was expected, as well as an enhanced proliferative and cytotoxic activity by total splenocytes in exercised animals. For this study male Wistar rats performed treadmill running 5 times a week for a period of 10 weeks, at moderate intensity. Our results showed a significant decrease in lymphocyte subpopulations (CD4+, Tγδ, and CD45 RA+ cells) and an increase in the cannabinoid receptors expression in those same cell. Although functional assays did not reveal any variation in total immunoglobulin production or NK cells cytotoxic activity, proliferative capability of total splenocytes increased in trained rats. Our results further support the notion that exercise affects the immunological system and extends the description of underlying mechanisms mediating such effects. Altogether, our results contribute to the understanding of the benefits of exercise on the practitioner´s general health.

Interaction between Cannabinoid System and Toll-Like Receptors Controls Inflammation

Since the discovery of the endocannabinoid system consisting of cannabinoid receptors, endogenous ligands, and biosynthetic and metabolizing enzymes, interest has been renewed in investigating the promise of cannabinoids as therapeutic agents. Abundant evidence indicates that cannabinoids modulate immune responses. An inflammatory response is triggered when innate immune cells receive a danger signal provided by pathogen- or damage-associated molecular patterns engaging pattern-recognition receptors. Toll-like receptor family members are prominent pattern-recognition receptors expressed on innate immune cells. Cannabinoids suppress Toll-like receptor-mediated inflammatory responses. However, the relationship between the endocannabinoid system and innate immune system may not be one-sided. Innate immune cells express cannabinoid receptors and produce endogenous cannabinoids. Hence, innate immune cells may play a role in regulating endocannabinoid homeostasis, and, in turn, the endocannabinoid system modulates local inflammatory responses. Studies designed to probe the interaction between the innate immune system and the endocannabinoid system may identify new potential molecular targets in developing therapeutic strategies for chronic inflammatory diseases. This review discusses the endocannabinoid system and Toll-like receptor family and evaluates the interaction between them.

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.

The role of cannabinoid receptors and the endocannabinoid system in mantle cell lymphoma and other non-Hodgkin lymphomas

The initiating oncogenic event in mantle cell lymphoma (MCL) is the translocation of cyclin D1, t(11;14)(q13;q32). However, other genetic aberrations are necessary for an overt lymphoma to arise. Like other B cell lymphomas, MCL at some points during the oncogenesis is dependent on interactions with other cells and factors in the microenvironment. The G protein coupled receptors cannabinoid receptors 1 and 2 (CB1 and CB2) are expressed at low levels on non-malignant lymphocytes and at higher levels in MCL and other lymphoma subtypes. In this review we give an overview of what is known on the role of the cannabinoid receptors and their ligands in lymphoma as compared to non-malignant T and B lymphocytes. In MCL cannabinoids mainly reduce cell proliferation and induce cell death. Importantly, our recent findings demonstrate that cannabinoids may induce either apoptosis or another type of programmed cell death, cytoplasmic vacuolation/paraptosis in MCL. The signalling to death has been partly characterized. Even though cannabinoid receptors seem to be expressed in many other types of B cell lymphoma, the functional role of cannabinoid receptor targeting is yet largely unknown. In non-malignant B and T lymphocytes, cannabinoid receptors are up-regulated in response to antigen receptor signalling or CD40. For T lymphocytes IL-4 has also a crucial role in transcriptional regulation of CB1. In lymphocytes, cannabinoid act in several ways - by affecting cell migration, cytokine response, at high doses inhibit cell proliferation and inducing cell death. The possible role for the endocannabinoid system in the immune microenvironment of lymphoma is discussed.

Effects of environmentally-relevant levels of perfluorooctane sulfonate on clinical parameters and immunological functions in B6C3F1 mice

In the first part of a series of studies to account for perfluorooctane sulfonate (PFOS)-induced sheep red blood cell (SRBC)-specific immunoglobulin M (IgM) antibody suppression in mice, a survey of clinical and immunotoxicological endpoints was examined. Adult female B₆C₃F₁ mice were exposed orally for 28 days to a total administered dose (TAD) of 0, 0.1, 0.5, 1, or 5 mg PFOS/kg. Uterus wet weight was significantly decreased compared with control at the 5 mg/kg dose. No indications of wasting syndrome, malnutrition, alteration of thyroid homeostasis, or signs of overt toxicity were observed. Numbers of splenic CD19+/CD21⁻, CD19+/CD21+, B220+/CD40+, CD4+/CD154⁻, CD4+/CD154+, and MHC-II+ cells were not altered. Additionally, ex vivo interleukin-4 (IL-4), IL-5, and IL-6 production by in vitro anti-CD3- or phorbol myristate acetate-stimulated CD4+ T-cells was not affected. Ex vivo IL-6 production by B-cells was significantly increased by in vitro stimulation with either anti-CD40 or lipopolysaccharide. Increased IL-6 production by B-cells was the most sensitive endpoint assessed resulting in alterations at the lowest dose tested (0.1 mg/kg TAD) following anti-CD40 stimulation. Further studies are required to characterize effects on inflammatory markers such as IL-6 at environmentally relevant concentrations of PFOS and to determine the key events associated with PFOS-induced IgM suppression to address potential human health risks.

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.

CB(1) and CB(2) cannabinoid receptors mediate different aspects of delta-9-tetrahydrocannabinol (THC)-induced T helper cell shift following immune activation by Legionella pneumophila infection

Legionella pneumophila infection of mice induces proinflammatory cytokines and Th1 immunity as well as rapid increases in serum levels of IL-12 and IFNgamma and splenic IL-12Rbeta2 expression. Delta-9-tetrahydrocannabinol (THC) treatment prior to infection causes a shift from Th1 to Th2 immunity and here we demonstrate that CB(1) and CB(2) cannabinoid receptors mediate different aspects of the shift. Using cannabinoid receptor antagonists and cannabinoid receptor gene deficient mice (CB(1) (-/-) and CB(2) (-/-)), we showed that both CB(1) and CB(2) receptors were involved in the THC-induced attenuation of serum IL-12 and IFNgamma. IFNgamma production is dependent upon signaling through IL-12Rbeta2 (beta2) and THC treatment suppressed splenic beta2 message; moreover, this effect was CB(1) but not CB(2)-dependent from studies with receptor antagonists and CB1(-/-) and CB2(-/-) mice. Furthermore, observed increases in IL-4 induced by THC, were not involved in the drug effect on beta2 from studies with IL-4 deficient mice. The GATA-3 transcription factor is necessary for IL-4 production and is selectively expressed in Th2 cells. GATA-3 message levels were elevated in spleens of THC-treated and L. pneumophila-infected mice and the effect was shown to be CB(2) but not CB(1)-dependent. Furthermore, GATA-3 regulatory factors were modulated in that Notch ligand Delta4 mRNA was decreased and Jagged1 increased by THC also in a CB2-dependent manner and splenic NFkappaB p65 was increased. Together, these results indicate that CB(1) and CB(2) mediate the THC-induced shift in T helper activity in L. pneumophila-infected mice, with CB(1) involved in suppressing IL-12Rbeta2 and CB(2) involved in enhancing GATA-3.

Activation of human T cells induces upregulation of cannabinoid receptor type 1 transcription

OBJECTIVE

Effects of cannabinoids are mediated by CB1 and CB2 receptors. In addition to neuronal effects, cannabinoids are potent modulators of immune functions. In this report, we investigated whether the transcription of these receptors is regulated after activation of T lymphocytes.

METHODS

CB1- and CB2-specific mRNA of primary human peripheral blood T cells and cells of the human T cell line Jurkat was measured by quantitative real-time RT-PCR in response to CD3/28. Using the decoy oligonucleotide approach, transcription factors involved in the regulation were determined. A promoter analysis was performed using transient transfection of chloramphenicol acetyl transferase reporter gene constructs in Jurkat cells.

RESULTS

Activation of human T cells caused an induction of CB1 mRNA expression in primary human T cells (8-fold) and Jurkat cells (29-fold). In contrast, CB2 transcription was not regulated. The CD3/28-mediated upregulation of CB1 involves the transcription factors AP-1, NF kappaB and NFAT. Furthermore, 2,490 bp of the CB1 promoter mediated inducibility in response to CD3/28.

CONCLUSIONS

The upregulation of CB1 in activated T cells, together with the constitutive expression of CB2, enables cellular responses to cannabinoids mediated by both receptor subtypes. It may thus contribute to the understanding of the various modulatory effects of cannabinoids on activated T cells.

Cannabinoid receptors in atherosclerosis

PURPOSE OF REVIEW

Recent findings suggesting that cannabinoid receptors are potential targets for the treatment of atherosclerosis are reviewed.

RECENT FINDINGS

Cannabinoids, such as Delta9-tetrahydrocannabinol, the major psychoactive compound of marijuana, their synthetic analogs and endogenous cannabinoid ligands, produce their biological effects by interacting with specific receptors. In the apolipoprotein E knockout mouse model of atherosclerosis, Delta9-tetrahydrocannabinol was shown to inhibit disease progression through pleiotropic effects on inflammatory cells. Blocking of cannabinoid receptor CB2, the main cannabinoid receptor expressed on immune cells, abolished the observed effects. The development of novel cannabinoid receptor ligands that selectively target CB2 receptors or pharmacological modulation of the endocannabinoid system might offer novel therapeutic strategies in the treatment of atherosclerosis. Several reports demonstrating an implication of the endocannabinoid system in different inflammatory conditions support this hypothesis.

SUMMARY

The immunomodulatory capacity of cannabinoids is now well established and suggests a broad therapeutic potential of cannabinoids for a variety of conditions, including atherosclerosis. New strategies based on nonpsychotropic cannabinoid receptor ligands or compounds modulating endocannabinoid synthesis or stability might solve the problem of the unwanted side effects associated with cannabinoid administration.

Functional expression of the P2Y14 receptor in murine T-lymphocytes

Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) analysis has previously shown that the P2Y(14) receptor is expressed in peripheral immune cells including lymphocytes. Although in transfected cells the P2Y(14) receptor couples to pertussis toxin-sensitive G(i/o) protein, the functional coupling of endogenously expressed P2Y(14) receptors to the inhibition of adenylyl cyclase activity has not been reported. Therefore, the primary aim of this study was to determine whether the P2Y(14) receptor is functionally expressed in murine spleen-derived T- and B-lymphocyte-enriched populations. RT-PCR analysis detected the expression of P2Y(14) receptor mRNA in whole spleen and isolated T- and B-lymphocytes. In T cells, UDP-glucose (EC(50) = 335 nM) induced a small but significant inhibition (circa 20%) of forskolin-stimulated cAMP accumulation, suggesting functional coupling of endogenously expressed P2Y(14) receptors to the inhibition of adenylyl cyclase activity. In contrast, the other putative P2Y(14) receptor agonists UDP-galactose, UDP-glucuronic acid and UDP-N-acetylglucosamine had no significant effect alone but behaved as partial agonists by blocking UDP-glucose responses. In B cells, UDP-glucose (100 microM) had no significant effect on forskolin-stimulated cAMP accumulation. Treatment of T cells with pertussis toxin (G(i/o) blocker) abolished the inhibitory effects of UDP-glucose on forskolin-stimulated cAMP accumulation. T-cell proliferation in response to anti-CD3 monoclonal antibody (1 microg ml(-1)) was significantly inhibited by UDP-glucose (59% inhibition; p[IC(50)] = 5.9 +/- 0.3), UDP-N-acetylglucosamine (37%; 6.1 +/- 0.3), UDP-galactose (56%; 8.2 +/- 0.2) and UDP-glucuronic acid (49%; 6.3 +/- 0.2). Interleukin-2- (5 ng ml(-1)) induced T-cell proliferation was also significantly inhibited by all four agonists. In summary, we have shown that the P2Y(14) receptor appears to be functionally expressed in murine spleen-derived T-lymphocytes. These observations suggest that UDP-glucose and related sugar nucleotides presumably via the P2Y(14) receptor may play an important role in modulating immune function.

Effects on the immune system

Marijuana and other exogenous cannabinoids alter immune function and decrease host resistance to microbial infections in experimental animal models and in vitro. Two modes of action by which delta9-tetrahydrocannabinol (THC) and other cannabinoids affect immune responses have been proposed. First, cannabinoids may signal through the cannabinoid receptors CB1 and CB2. Second, at sites of direct exposure to high concentrations of cannabinoids, such as the lung, membrane perturbation may be involved. In addition, endogenous cannabinoids or endocannabinoids have been identified and have been proposed as native modulators of immune functions through cannabinoid receptors. Exogenously introduced cannabinoids may disturb this homoeostatic immune balance. A mode by which cannabinoids may affect immune responses and host resistance maybe by perturbing the balance of T helper (Th)1 pro-inflammatory versus Th2 anti-inflammatory cytokines. While marijuana and various cannabinoids have been documented to alter immune functions in vitro and in experimental animals, no controlled longitudinal epidemiological studies have yet definitively correlated immunosuppressive effects with increased incidence of infections or immune disorders in humans. However, cannabinoids by virtue of their immunomodulatory properties have the potential to serve as therapeutic agents for ablation of untoward immune responses.

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.

Cannabinoid-based drugs as anti-inflammatory therapeutics

In the nineteenth century, marijuana was prescribed by physicians for maladies ranging from eating disorders to rabies. However, as newer, more effective drugs were discovered and as the potential for abuse of marijuana was recognized, its use as a therapeutic became restricted, and only recently has its therapeutic potential been re-evaluated. Recent studies in animal models and in humans have produced promising results for the treatment of various disorders - such as obesity, cancer, and spasticity and tremor due to neuropathology - with drugs based on marijuana-derived cannabinoids. Moreover, as I discuss here, a wealth of information also indicates that these drugs have immunosuppressive and anti-inflammatory properties; therefore, on the basis of this mode of action, the therapeutic usefulness of these drugs in chronic inflammatory diseases is now being reassessed.

Cannabinoid signaling in glial cells

The cannabinoid signaling system is composed of cannabinoid (CB) receptors, their endogenous ligands, the endocannabinoids, and the enzymes that produce and inactivate them. It is well known that neurons communicate between each other through this signaling system. Delta 9-tetrahydrocannabinol, the main psychoactive compound of marijuana, interacts with CB receptors, impinging on this communication and inducing profound behavioral effects such as memory impairment and analgesia. Recent evidence suggests that glial cells also express components of the cannabinoid signaling system and marijuana-derived compounds act at CB receptors expressed by glial cells, affecting their functions. This review summarizes this evidence, discusses how glial cells might use the cannabinoid signaling system to communicate with neighboring cells, and argues that nonpsychotropic cannabinoids, both marijuana-derived and synthetic, likely constitute lead compounds for therapy aimed at reducing acute and chronic neuroinflammation, such as occurs in multiple sclerosis.

Role of cannabinoid receptors in inhibiting macrophage costimulatory activity

Delta(9)-tetrahydrocannabinol (THC) inhibits several immunologic functions of macrophages. THC's impact on peritoneal macrophages to deliver costimulatory signals to a helper T cell hybridoma was investigated by T cell interleukin-2 production stimulated with immobilized anti-CD3 antibody. The drug's inhibition of costimulatory activity depended on the macrophages. THC decreased costimulation provided by peritoneal cells elicited with polystyrene beads and thioglycollate, but the drug had no influence with macrophages elicited with thioglycollate alone. Bead administration induced CB2 mRNA expression in macrophages, while CB1 mRNA was not detected. Although inhibition was associated with functional heat-stable antigen, a costimulatory molecule, on macrophages, THC exposure did not alter cell surface heat-stable antigen expression. Inhibition by THC and anti-heat-stable antigen antibody was not additive suggesting the inhibitory mechanisms may overlap. Cannabinoid suppression was stereoselective; low affinity synthetic isomer CP56,667 did not diminish the T cell response. CB1-selective antagonist SR141716A completely reversed, and CB2-selective antagonist SR144528 partially blocked THC's inhibition. Both antagonists appeared to behave as inverse agonists in a receptor-selective manner. Although T cells expressed a low level of CB2 mRNA, neither THC nor SR141716A affected T cell activation in a system independent of macrophages, while SR144528 was inhibitory. High affinity synthetic agonist CP55,940, but not partial agonist THC, impaired costimulation by macrophages from mice lacking CB2 receptor. Although CB1 mRNA was not detected in CB2 null macrophages, CP55,940 reversed the inverse agonist activity of SR141716A. Hence, CB2 and possibly another receptor subtype may be involved in mediating cannabinoid suppression of macrophage costimulation.

The cannabinoid system and immune modulation

Studies on the effects of marijuana smoking have evolved into the discovery and description of the endocannabinoid system. To date, this system is composed of two receptors, CB1 and CB2, and endogenous ligands including anandamide, 2-arachidonoyl glycerol, and others. CB1 receptors and ligands are found in the brain as well as immune and other peripheral tissues. Conversely, CB2 receptors and ligands are found primarily in the periphery, especially in immune cells. Cannabinoid receptors are G protein-coupled receptors, and they have been linked to signaling pathways and gene activities in common with this receptor family. In addition, cannabinoids have been shown to modulate a variety of immune cell functions in humans and animals and more recently, have been shown to modulate T helper cell development, chemotaxis, and tumor development. Many of these drug effects occur through cannabinoid receptor signaling mechanisms and the modulation of cytokines and other gene products. It appears the immunocannabinoid system is involved in regulating the brain-immune axis and might be exploited in future therapies for chronic diseases and immune deficiency.

High level of cannabinoid receptor 1, absence of regulator of G protein signalling 13 and differential expression of Cyclin D1 in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a moderately aggressive B-cell lymphoma that responds poorly to currently used therapeutic protocols. In order to identify tumour characteristics that improve the understanding of biology of MCL, analysis of oligonucleotide microarrays were used to define specific gene expression profiles. Biopsy samples of MCL cases were compared to reactive lymphoid tissue. Among genes differentially expressed in MCL were genes that are involved in the regulation of proliferation, cell signalling, adhesion and homing. Furthermore, some genes with previously unknown function, such as C11orf32, C2orf10, TBC1D9 and ABCA6 were found to be differentially expressed in MCL compared to reactive lymphoid tissue. Of special interest was the high expression of the cannabinoid receptor 1 (CB1) gene in all MCL cases analysed. These results were further confirmed at the cellular and protein level by immunocytochemical staining and immunoblotting of MCL cells. Furthermore, there was a reduced expression of a regulator of G protein signalling, RGS13 in all MCLs, with a complete absence in the majority of cases while present in control lymphoid tissue. These results were further confirmed by PCR. Sequencing of the RGS13 gene revealed changes suggesting polymorphisms, indicating that downregulation of the expression of RGS13 is not related to mutations, but may serve as a new specific marker for MCL. Moreover, comparison between individual cases of MCL, revealed that the CCND1 gene appears to be differently expressed in MCL cases with high vs low proliferative activity.

Evidence for cannabinoid receptor-dependent and -independent mechanisms of action in leukocytes

Cannabinoids exhibit immunosuppressive actions that include inhibition of interleukin-2 production in response to a variety of T cell activation stimuli. Traditionally, the effects of these compounds have been attributed to cannabinoid receptors CB1 and CB2, both of which are expressed in mouse splenocytes. Therefore, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorphenyl)-4-methyl-H-pyrazole-3 carboxyamidehydrochloride (SR141716A), a CB1 antagonist, and N-[(1S)-endo-1,3,3,-trimethyl-bicyclo[2,2,1]heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528), a CB2 antagonist, were used to investigate the role of cannabinoid receptors in the cannabinoid-induced inhibition of phorbol ester plus calcium ionophore (PMA/Io)-stimulated interleukin-2 production by mouse splenocytes. PMA/Io-stimulated interleukin-2 production was inhibited by cannabinol, cannabidiol, and both WIN 55212-2 stereoisomers with a rank order potency of R-(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-napthanlenyl) methanone mesylate (WIN 55212-2) approximately cannabidiol > S-(-)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-napthanlenyl) methanone mesylate (WIN 55212-3) approximately cannabinol. Cannabinoid-induced inhibition of PMA/Io-stimulated interleukin-2 was not attenuated by the presence of both SR144528 and SR141716A. Using pertussis toxin to address the role of G protein-coupled receptors in this response, it was determined that pertussis toxin treatment did not attenuate cannabinol-induced inhibition of PMA/Io-stimulated interleukin-2. With the demonstration that cannabinoid-induced inhibition of PMA/Io-stimulated interleukin-2 was not mediated via CB1 or CB2, alternative targets of cannabinoids in T cells were examined. Specifically, it was demonstrated that cannabinoids elevated intracellular calcium concentration in resting splenocytes and that the cannabinol-induced elevation in intracellular calcium concentration was attenuated by treatment with both SR144528 and SR141716A. Interestingly, pretreatment of splenocytes with agents that elevate intracellular calcium concentration inhibited PMA/Io-stimulated interleukin-2 production, suggesting that an elevation in intracellular calcium concentration might be involved in the mechanism of interleukin-2 inhibition. These studies suggest that immune modulation produced by cannabinoids involves multiple mechanisms, which might be both cannabinoid receptor-dependent and -independent.

Immunoregulation of a viral model of multiple sclerosis using the synthetic cannabinoid R+WIN55,212

Theiler murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD) is a mouse model of chronic-progressive multiple sclerosis (MS) characterized by Th1-mediated CNS demyelination and spastic hindlimb paralysis. Existing MS therapies reduce relapse rates in 30% of relapsing-remitting MS patients, but are ineffective in chronic-progressive disease, and their effects on disability progression are unclear. Experimental studies demonstrate cannabinoids are useful for symptomatic treatment of spasticity and tremor in chronic-relapsing experimental autoimmune encephalomyelitis. Cannabinoids, however, have reported immunosuppressive properties. We show that the cannabinoid receptor agonist, R+WIN55,212, ameliorates progression of clinical disease symptoms in mice with preexisting TMEV-IDD. Amelioration of clinical disease is associated with downregulation of both virus and myelin epitope-specific Th1 effector functions (delayed-type hypersensitivity and IFN-gamma production) and the inhibition of CNS mRNA expression coding for the proinflammatory cytokines, TNF-alpha, IL1-beta, and IL-6. Clinical trials investigating the therapeutic potential of cannabinoids for the symptomatic treatment of MS are ongoing, and this study demonstrates that they may also have potent immunoregulatory properties.

Altered cannabinoid receptor mRNA expression in peripheral blood mononuclear cells from marijuana smokers

We studied, using RT-PCR, the relative expression of cannabinoid receptor (CBR) mRNA in peripheral blood mononuclear cells (PBMC) from different donor groups. Cells from normal donors expressed a CB2 mRNA level threefold higher than CB1 across all age, gender or ethnicity groups, and amplicons were of the same size in all donors. However, cells from marijuana users expressed higher levels of CBR mRNA, but with a preserved CB1/CB2 ratio of 1:3. CBR gene products were also studied following short-term mitogen activation in vitro. CB1 expression decreased following mitogen stimulation when compared to the time-matched medium only cells while the expression of CB2 mRNA remained unchanged. These studies suggest that marijuana smoking and immune activation can alter the basal levels of CB1 and CB2 in PBMCs.