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

Fig. 1

“Cannabinoids are a group of compounds found in the marijuana plant (Cannabis sativaL.). Marijuana has been used both for recreational and medicinal purposes for several centuries.

Cannabinoids have been shown to be effective in the treatment of nausea and vomiting associated with cancer chemotherapy, anorexia and cachexia seen in HIV/AIDS patients, as well as neuropathic pain, and spasticity in multiple sclerosis.

More recently, the anti-inflammatory properties of cannabinoids are drawing significant attention. In the last 15 years, studies with marijuana cannabinoids led to the discovery of cannabinoid receptors (CB1 and CB2) and their endogenous ligands, which make up what is known as the endocannabinoid system.

Cannabinoids are a group of compounds present in Cannabis plant (Cannabis sativa L.). They mediate their physiological and behavioral effects by activating specific cannabinoid receptors. With the recent discovery of the cannabinoid receptors (CB1 and CB2) and the endocannabinoid system, research in this field has expanded exponentially.

Cannabinoids have been shown to act as potent immunosuppressive and anti-inflammatory agents and have been shown to mediate beneficial effects in a wide range of immune-mediated diseases such as multiple sclerosis, diabetes, septic shock, rheumatoid arthritis, and allergic asthma.

Cannabinoid receptor 1 (CB1) is mainly expressed on the cells of the central nervous system as well as in the periphery. In contrast, cannabinoid receptor 2 (CB2) is predominantly expressed on immune cells. The precise mechanisms through which cannabinoids mediate immunosuppression is only now beginning to be understood…

In this review, we will focus on apoptotic mechanisms of immunosuppression mediated by cannabinoids on different immune cell populations and discuss how activation of CB2 provides a novel therapeutic modality against inflammatory and autoimmune diseases as well as malignancies of the immune system, without exerting the untoward psychotropic effects…

…cannabinoids do induce apoptosis in immune cells, alleviating inflammatory responses and protecting the host from acute and chronic inflammation.

The cumulative effect of cannabinoids on all cell populations of the immune system can be beneficial, when there is a need for immune suppression.

For example, in patients with autoimmune diseases such as multiple sclerosis, arthritis and lupus, or in those with septic shock, where the disease is caused by activated immune cells, targeting the immune cells via CB2 agonists may trigger apoptosis and act as anti-inflammatory therapy.

CB2 select agonists are not psychoactive and because CB2 is expressed primarily in immune cells, use of CB2 agonists could provide a novel therapeutic modality against autoimmune and inflammatory diseases.

In addition to the use of exogenous cannabinoids, in vivo manipulation of endocannabinoids may also offer novel treatment opportunities against cancer and autoimmune diseases.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3005548/

Direct suppression of CNS autoimmune inflammation via the cannabinoid receptor CB1 on neurons and CB2 on autoreactive T cells.

“The cannabinoid system is immunomodulatory and has been targeted as a treatment for the central nervous system (CNS) autoimmune disease multiple sclerosis.

Using an animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), we investigated the role of the CB(1) and CB(2) cannabinoid receptors in regulating CNS autoimmunity…

Together, our results demonstrate that the cannabinoid system within the CNS plays a critical role in regulating autoimmune inflammation, with the CNS directly suppressing T-cell effector function via the CB(2) receptor.”

http://www.ncbi.nlm.nih.gov/pubmed/17401376

CB2 cannabinoid receptors as an emerging target for demyelinating diseases: from neuroimmune interactions to cell replacement strategies

Figure 2

“Amongst the various demyelinating diseases that affect the central nervous system, those induced by an inflammatory response stand out because of their epidemiological relevance. The best known inflammatory-induced demyelinating disease is multiple sclerosis, but the immune response is a common pathogenic mechanism in many other less common pathologies (e.g., acute disseminated encephalomyelitis and acute necrotizing haemorrhagic encephalomyelitis).

In all such cases, modulation of the immune response seems to be a logical therapeutic approach.

Cannabinoids are well known immunomodulatory molecules that act through CB1 and CB2 receptors. While activation of CB1 receptors has a psychotropic effect, activation of CB2 receptors alone does not. Therefore, to bypass the ethical problems that could result from the treatment of inflammation with psychotropic molecules, considerable effort is being made to study the potential therapeutic value of activating CB2 receptors.

In this review we examine the current knowledge and understanding of the utility of cannabinoids as therapeutic molecules for inflammatory-mediated demyelinating pathologies. Moreover, we discuss how CB2 receptor activation is related to the modulation of immunopathogenic states.

The activation of CB2receptors results in the modulation of the inflammatory response, restraining one of the agents responsible for the progress of demyelination and neuronal death, the ultimate causes of the symptoms in pathologies such as MS and EAE.

The modulation of inflammatory molecules through CB2 receptors could also enhance remyelination, stimulating the survival of oligodendrocyte precursors and neural stem/precursor cells, and their development into mature oligodendrocytes.

…this raises the possibility that CB2 agonists could have the potential to promote brain repair.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2219542/#!po=48.0769

Cannabidiol lowers incidence of diabetes in non-obese diabetic mice.

“Cannabidinoids are components of the Cannabis sativa (marijuana) plant that have been shown capable of suppressing inflammation and various aspects of cell-mediated immunity.

Cannabidiol (CBD), a non-psychoactive cannabinoid has been previously shown by us to suppress cell-mediatedautoimmune joint destruction in an animal model of rheumatoid arthritis.

We now report that CBD treatment significantly reduces the incidence of diabetes in NOD mice from an incidence of 86% in non-treated control mice to an incidence of 30% in CBD-treated mice…

Our results indicate that CBD can inhibit and delay destructive insulitis and inflammatory Th1-associated cytokine production in NOD mice resulting in a decreased incidence of diabetes possibly through an immunomodulatory mechanism shifting the immune response from Th1 to Th2 dominance.”

http://www.ncbi.nlm.nih.gov/pubmed/16698671

Cannabidiol arrests onset of autoimmune diabetes in NOD mice.

Figure 2

“Cannabidiol (CBD) is a potent anti-inflammatory agent. It is effective in supressing IFN-γ and TNF-α production and progression of autoimmune Th1-mediated rheumatoid arthritis by inhibition of T cell proliferation. This observation led us to investigate the possible effects of CBD on additional autoimmune diseases.

We have previously reported that cannabidiol (CBD) lowers the incidence of diabetes in young non-obese diabetes-prone (NOD) female mice.

In the present study we show that administration of CBD to 11-14 week old female NOD mice… ameliorates the manifestations of the disease…

CBD was extracted from Cannabis resin (hashish)…

Our data strengthen our previous assumption that CBD, known to be safe in man, can possibly be used as a therapeutic agent for treatment of type 1 diabetes.

CBD is not psychoactive and has anti-inflammatory and anti autoimmune properties.

Based on the above presented results, on the previously documented anti-inflammatory effects of CBD and on its clinical safety, it seems reasonable to consider the use of CBD for controlling type 1 diabetes at an early stage of the disease.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2270485/

Multiple sclerosis may disrupt endocannabinoid brain protection mechanism

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“Since the discovery of the endocannabinoids [eCB; anandamide and 2-arachidonoylglycerol (2-AG), various pathological conditions were shown to increase the eCB tone and to inhibit molecular mechanisms that are involved in the production, release, and diffusion of harmful mediators such as proinflammatory cytokines or excess glutamate.

In this issue of PNAS, Witting et al.  demonstrate that, unexpectedly and contrary to the effects of other brain diseases, cell damage induced by experimental autoimmune encephalomyelitis (EAE), an immune-mediated disease widely used as a laboratory model of multiple sclerosis (MS), does not lead to enhancement of eCB levels, although the cannabinoid receptors remain functional.

Nearly two decades ago, Lyman et al.  reported that Δ9-THC, the psychoactive component of marijuana, suppresses the symptoms of EAE. A few years later, Wirguin et al. reported the same effect by Δ8-THC, a more stable and less psychotropic analogue of Δ9-THC.

Thus, THC was shown to inhibit both clinical and histological signs of EAE even before the endocannabinoids were described.

THC was also shown to control spasticity and tremor in chronic relapsing EAE, a further autoimmune model of MS , and to inhibit glutamate release via activation of the CB1-cannabinoid receptor in EAE. Moreover, mice deficient in the cannabinoid receptor CB1 tolerate inflammatory and excitotoxic insults poorly and develop substantial neurodegeneration after immune attack in EAE.

Thus, the brain loses some of its endogenous neuroprotective capacity, but it may still respond to exogenous treatment with 2-AG or other CB1 agonists. Assuming that the biochemical changes taking place in the EAE model of MS are similar to those in MS itself, these results represent a biochemical-based support to the positive outcome noted with cannabinoid therapy in MS.

These data suggest that the high level of IFN-γ in the CNS, noted in mice with EAE, disrupts eCB-mediated neuroprotection, while maintaining functional cannabinoid receptors, thus providing additional support for the use of cannabinoid-based medicine to treat MS.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1458835/

Cannabinoid receptors in acute and chronic complications of atherosclerosis

“Atherosclerosis is a chronic inflammatory disease that is the primary cause of myocardial infarction and stroke, which occur after sudden thrombotic occlusion of an artery.

A growing body of evidence suggests that cannabinoid signalling plays a fundamental role in atherosclerosis development and its clinical manifestations. Thus, CB2 receptors are protective in myocardial ischaemia/reperfusion and implicated in the modulation of chemotaxis, which is crucial for the recruitment of leukocytes during inflammation.

Delta-9-Tetrahydrocannabinol (THC)-mediated activation has been shown to inhibit atherosclerotic plaque progression in a CB2 dependent manner.

It is tempting to suggest that pharmacological modulation of the endocannabinoid system is a potential novel therapeutic strategy in the treatment of atherosclerosis.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2219535/

Low dose oral cannabinoid therapy reduces progression of atherosclerosis in mice

Figure 1 : The cannabinoid receptor CB2 is expressed in human and mouse atherosclerotic plaques. Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, or to obtain a text description, please contact npg@nature.com

“Atherosclerosis is a chronic inflammatory disease… Derivatives of cannabinoids such as delta-9-tetrahydrocannabinol (THC) modulate immune functions and therefore have potential for the treatment of inflammatory diseases.

We investigated the effects of THC in a murine model of established atherosclerosis.

Oral administration of THC resulted in significant inhibition of disease progression.

Our data demonstrate that oral treatment with a low dose of THC inhibits atherosclerosis progression in the apolipoprotein E knockout mouse model, through pleiotropic immunomodulatory effects on lymphoid and myeloid cells.

Thus, THC or cannabinoids with activity at the CB2 receptor may be valuable targets for treating atherosclerosis.”

http://www.nature.com/nature/journal/v434/n7034/full/nature03389.html

http://www.ncbi.nlm.nih.gov/pubmed/15815632

 

The Effect of Cannabidiol on Ischemia/Reperfusion-Induced Ventricular Arrhythmias: The Role of Adenosine A1 Receptors.

“Cannabidiol (CBD) is a nonpsychoactive phytocannabinoid with anti-inflammatory activity mediated by enhancing adenosine signaling.

As the adenosine A1 receptor activation confers protection against ischemia/reperfusion (I/R)-induced ventricular arrhythmias, we hypothesized that CBD may have antiarrhythmic effect through the activation of adenosine A1 receptor.

Cannabidiol has recently been shown to suppress ischemia-induced ventricular arrhythmias…

The present results demonstrated that CBD has an antiarrhythmic effect against I/R-induced arrhythmias, and the antiarrhythmic effect of CBD may be mediated through the activation of adenosine A1 receptor.”

http://www.ncbi.nlm.nih.gov/pubmed/24853683

Δ8-Tetrahydrocannabivarin prevents hepatic ischaemia/reperfusion injury by decreasing oxidative stress and inflammatory responses through cannabinoid CB2 receptors.

“Activation of cannabinoid CB(2) receptors protects against various forms of ischaemia-reperfusion (I/R) injury.

Δ(8) -Tetrahydrocannabivarin (Δ(8) -THCV) is a synthetic analogue of the plant cannabinoid Δ(9) -tetrahydrocannabivarin, which exhibits anti-inflammatory effects in rodents involving activation of CB(2) receptors. Here, we assessed effects of Δ(8) -THCV and its metabolite 11-OH-Δ(8) -THCV on CB(2) receptors and against hepatic I/R injury.

CONCLUSIONS AND IMPLICATIONS:

Δ(8) -THCV activated CB(2) receptors in vitro, and decreased tissue injury and inflammation in vivo, associated with I/R partly via CB(2) receptor activation.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3423240/