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.”

Endocannabinoids and the regulation of their levels in health and disease.

Abstract

“PURPOSE OF REVIEW:

Endocannabinoids are defined as endogenous agonists of cannabinoid receptors, that is, of the two G-protein-coupled receptors for the Cannabis psychoactive principle Delta-tetra-hydrocannabinol. Two such endogenous mediators have been most thoroughly studied so far: anandamide and 2-arachidonoylglycerol. Here we review the mechanisms for the regulation of their levels under physiological and pathological conditions, and recent findings on their role in disease.

RECENT FINDINGS:

It is becoming increasingly clear that, although both anandamide and 2-arachidonoyl-glycerol are produced and degraded ‘on demand’, the levels of these two compounds appear to be regulated in different, and sometimes even opposing, ways, often using redundant molecular mechanisms. Alterations of endocannabinoid levels have been found in both animal models of pain, neurological and neurodegenerative states, gastrointestinal disorders and inflammatory conditions, and in blood, cerebrospinal fluid and bioptic samples from patients with various diseases.

SUMMARY:

Endocannabinoid levels appear to be transiently elevated as an adaptive reaction to re-establish normal homeostasis when this is acutely and pathologically perturbed. In some chronic conditions, however, this system also contributes to the progress or symptoms of the disorder. As a consequence, new therapeutic drugs are being designed from both stimulants and blockers of endocannabinoid action.”

http://www.ncbi.nlm.nih.gov/pubmed/17353660

From endocannabinoid profiling to ‘endocannabinoid therapeutics’.

Abstract

“The discovery of the endocannabinoid signalling system, that is, of cannabinoid receptors, their endogenous ligands, known as endocannabinoids, and of endocannabinoid anabolic and catabolic enzymes, raised several questions regarding the physiopathological role of these mediators. Several of these questions were answered by investigating alterations in the levels of the most studied endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), in tissues of animal models of disorders, and in bioptic samples and biological fluids (cerebrospinal fluid and blood) of human volunteers. Subsequently, the pharmacological effects of synthetic compounds that selectively target the cannabinoid CB(1) and CB(2) receptors, and endocannabinoid anabolic and catabolic enzymes, established cause-effect relationships between pathological alterations in endocannabinoid levels and the symptoms and progress of several disorders, including emesis, obesity, metabolic disorders, hepatic diseases, pain, inflammation and neurological and neuropsychiatric disorders. These new developments are discussed in this second review on the endocannabinoids, together with the results of pre-clinical and clinical studies on the potential therapeutic use of plant-derived cannabinoids and synthetic agents that manipulate pharmacologically the action at cannabinoid receptors or the tissue levels of AEA and 2-AG.”

http://www.ncbi.nlm.nih.gov/pubmed/19497779

Endocannabinoids Measurement in Human Saliva as Potential Biomarker of Obesity

Background

“The discovery of the endocannabinoid system and of its role in the regulation of energy balance has significantly advanced our understanding of the physiopathological mechanisms leading to obesity and type 2 diabetes. New knowledge on the role of this system in humans has been acquired by measuring blood endocannabinoids. Here we explored endocannabinoids and related N-acylethanolamines in saliva and verified their changes in relation to body weight status and in response to a meal or to body weight loss.”

“The discovery of the endocannabinoid system (ECS) and of its impact on the regulation of energy homeostasis represents a significant advance in the study of obesity and type 2 diabetes [1][4].”

“The saliva is the first digestive secretion produced in response to the ingestion of food [11]. Therefore, it is reasonable to investigate whether signals and systems involved in the regulation of food intake, such as the ECS, might be present in saliva and exert a functional role. Besides, saliva offers distinctive advantages over serum or plasma as a diagnostic tool, thanks to the non-invasiveness of the collection procedure.”

“The ECS is present in human salivary glands.”

“Changes in salivary endocannabinoids and N-acylethanolamines levels in response to body weight loss.”

“Here we demonstrate that endocannabinoids and related N-acylethanolamines can be reliably detected and quantified in human saliva. Similarly to what already reported for circulating levels in the blood [7], [9], [10], the salivary concentration of AEA and OEA were significantly increased in obese, insulin-resistant subjects as compared to normal weight controls.”

“the present findings overall indicate that salivary AEA might be a useful biomarker in human obesity, in particular considering that salivary samples are easy to collect, require a non-invasive procedure advantageous when performing studies in obese subjects in whom venipuncture may be difficult, and can be repeatedly collected at home by the patient during a therapeutic intervention. This type of tool could therefore be used to better phenotype the obese population, assess responses to treatment, or to further study the physiology of the ECS in humans, by investigating salivary endocannabinoid responses under various conditions.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3409167/

Cannabinoid receptors as therapeutic targets for obesity and metabolic diseases.

Abstract

“One of the most interesting pharmacological targets proposed in the past ten years for fighting obesity and related metabolic disorders is the endocannabinoid system. The role of the endocannabinoid system is crucial in regulating the rewarding properties of food, in controlling energy balance by acting at the hypothalamic circuitries involved in food intake, and in peripheral metabolism by influencing adipocytes, hepatocytes, myocytes and pancreatic endocrine cells. Obesity seems to be a condition associated with a pathological overactivation of the endocannabinoid system; therefore, restoring a normal endocannabinoid tone by antagonizing the cannabinoid receptor type 1 (CB(1)) could help arrest both the development and the maintenance of obesity.”

http://www.ncbi.nlm.nih.gov/pubmed/17027338

Rimonabant: an antagonist drug of the endocannabinoid system for the treatment of obesity.

Abstract

“Obesity, an ever-increasing problem in the industrialized world, has long been a target of research for a cure or, at least, control of its expansion. In the search for treatment, the recently discovered endocannabinoid system has emerged as a new target for controlling obesity and its associated conditions. The endocannabinoid system plays an important role in controlling weight and energy balance in humans. This system is activated to a greater extent in obese patients, and the specific blockage of its receptors is the aim of rimonabant, one of the most recent drugs created for the treatment of obesity. This drug acts as a blockade for endocannabinoid receptors found in the brain and peripheral organs that play an important role on carbohydrate and fat metabolism. Clinical studies have confirmed that, when used in combination with a low calorie diet, rimonabant promotes loss in body weight, loss in abdominal circumference, and improvements in dyslipidemia. Rimonabant is also being tested as a potential anti-smoking treatment since endocannabinoids are related to the pleasurable effect of nicotine. Thus, rimonabant constitutes a new therapeutic approach to obesity and cardiovascular risk factors. Studies show effectiveness in weight loss; however, side effects such as psychiatric alterations have been reported, including depression and anxiety. These side effects have led the FDA (Food and Drug Administration) to not approve this drug in the United States. For a more complete evaluation on the safety of this drug, additional studies are in progress.”

http://www.ncbi.nlm.nih.gov/pubmed/19443932

The endocannabinoid system and rimonabant: a new drug with a novel mechanism of action involving cannabinoid CB1 receptor antagonism–or inverse agonism–as potential obesity treatment and other therapeutic use.

Abstract

“There is considerable evidence that the endocannabinoid (endogenous cannabinoid) system plays a significant role in appetitive drive and associated behaviours. It is therefore reasonable to hypothesize that the attenuation of the activity of this system would have therapeutic benefit in treating disorders that might have a component of excess appetitive drive or over-activity of the endocannabinoid system, such as obesity, ethanol and other drug abuse, and a variety of central nervous system and other disorders. Towards this end, antagonists of cannabinoid receptors have been designed through rational drug discovery efforts. Devoid of the abuse concerns that confound and impede the use of cannabinoid receptor agonists for legitimate medical purposes, investigation of the use of cannabinoid receptor antagonists as possible pharmacotherapeutic agents is currently being actively investigated. The compound furthest along this pathway is rimonabant, a selective CB(1) (cannabinoid receptor subtype 1) antagonist, or inverse agonist, approved in the European Union and under regulatory review in the United States for the treatment of obesity. This article summarizes the basic science of the endocannabinoid system and the therapeutic potential of cannabinoid receptor antagonists, with emphasis on the treatment of obesity.”

http://www.ncbi.nlm.nih.gov/pubmed/17489873

Cannabinoid receptor antagonists: pharmacological opportunities, clinical experience, and translational prognosis.

Abstract

“The endogenous cannabinoid (CB) (endocannabinoid) signaling system is involved in a variety of (patho)physiological processes, primarily by virtue of natural, arachidonic acid-derived lipids (endocannabinoids) that activate G protein-coupled CB1 and CB2 receptors. A hyperactive endocannabinoid system appears to contribute to the etiology of several disease states that constitute significant global threats to human health. Consequently, mounting interest surrounds the design and profiling of receptor-targeted CB antagonists as pharmacotherapeutics that attenuate endocannabinoid transmission for salutary gain. Experimental and clinical evidence supports the therapeutic potential of CB1 receptor antagonists to treat overweight/obesity, obesity-related cardiometabolic disorders, and substance abuse. Laboratory data suggest that CB2 receptor antagonists might be effective immunomodulatory and, perhaps, anti-inflammatory drugs. One CB1 receptor antagonist/inverse agonist, rimonabant, has emerged as the first-in-class drug approved outside the United States for weight control. Select follow-on agents (taranabant, otenabant, surinabant, rosonabant, SLV-319, AVE1625, V24343) have also been studied in the clinic. However, rimonabant’s market withdrawal in the European Union and suspension of rimonabant’s, taranabant’s, and otenabant’s ongoing development programs have highlighted some adverse clinical side effects (especially nausea and psychiatric disturbances) of CB1 receptor antagonists/inverse agonists. Novel CB1 receptor ligands that are peripherally directed and/or exhibit neutral antagonism (the latter not affecting constitutive CB1 receptor signaling) may optimize the benefits of CB1 receptor antagonists while minimizing any risk. Indeed, CB1 receptor-neutral antagonists appear from preclinical data to offer efficacy comparable to or better than that of prototype CB1 receptor antagonists/inverse agonists, with less propensity to induce nausea. Continued pharmacological profiling, as the prelude to first-in-man testing of CB1 receptor antagonists with unique modes of targeting/pharmacological action, represents an exciting translational frontier in the critical path to CB receptor blockers as medicines.”

http://www.ncbi.nlm.nih.gov/pubmed/19249987

Cannabinoid-1 receptor (CB1R) blockers as medicines: beyond obesity and cardiometabolic disorders to substance abuse/drug addiction with CB1R neutral antagonists.

Abstract

“INTRODUCTION:

Addiction to chemical substances with abuse potential presents medical needs largely unsolved by extant therapeutic strategies. Signal transmission through the cannabinoid-1 receptor (CB1R) in the central nervous system (CNS) modulates neurotransmitters/neuronal pathways contributing to the rewarding properties and hedonic effects of certain nondrug stimuli (e.g., food) and many prototypical addictive drugs, promoting excessive intake and its pathological consequences. Typical CB1R antagonists/inverse agonists reduce the rewarding effects and normalize behavioral phenotypes associated with food and abused drugs, but carry an unacceptable adverse-event profile that may reflect, at least partly, their intrinsic ability to alter basal homeostatic CB1R signaling in the CNS and elicit a negative efficacy response. Alternatively, peripherally biased CB1R inverse agonists with limited CNS permeability and putative CB1R neutral antagonists expressing modest (if any) inverse-agonist efficacy are garnering attention for treating obesity and related cardiometabolic complications with a potentially enhanced benefit-to-risk profile.

AREAS COVERED:

This mini-review calls attention to the proposition that CB1R neutral antagonists offer attractive opportunities for pharmacotherapeutic exploitation in the substance abuse/drug addiction space, whereas the restricted CNS accessibility of peripherally biased CB1R inverse agonists circumscribes their therapeutic utility for this indication.

EXPERT OPINION:

The unique preclinical pharmacology, efficacy profiles, and reduced adverse-event risk of CB1R neutral antagonists make them worthy of translational study for their potential therapeutic application beyond obesity/cardiometabolic disease to include substance-abuse/drug-addiction disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/22335400

Peripheral CB1 cannabinoid receptor blockade improves cardiometabolic risk in mouse models of obesity

Abstract

“Obesity and its metabolic consequences are a major public health concern worldwide. Obesity is associated with overactivity of the endocannabinoid system, which is involved in the regulation of appetite, lipogenesis, and insulin resistance. Cannabinoid-1 receptor (CB1R) antagonists reduce body weight and improve cardiometabolic abnormalities in experimental and human obesity, but their therapeutic potential is limited by neuropsychiatric side effects. Here we have demonstrated that a CB1R neutral antagonist largely restricted to the periphery does not affect behavioral responses mediated by CB1R in the brains of mice with genetic or diet-induced obesity, but it does cause weight-independent improvements in glucose homeostasis, fatty liver, and plasma lipid profile. These effects were due to blockade of CB1R in peripheral tissues, including the liver, as verified through the use of CB1R-deficient mice with or without transgenic expression of CB1R in the liver. These results suggest that targeting peripheral CB1R has therapeutic potential for alleviating cardiometabolic risk in obese patients.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2912197/