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

Direct suppression of autoreactive lymphocytes in the central nervous system via the CB2 receptor.

The cannabinoid system is evolutionally conserved and is present in invertebrates and vertebrates. One of the best-studied cannabinoids is Δ9-tetrahydrocannabinol (THC), the predominant active component of Cannabis sativa or marijuana.

The marijuana plant has been exploited by humans since their early history and was used for centuries in Asian medicine to reduce the severity of pain, inflammation and asthma. However, only recently have the mechanisms of the medicinal properties of THC begun to be understood. This understanding is largely due to the identification and cloning of two cannabinoid receptors.

The cannabinoid system is now recognized as a regulator of both the nervous and immune systems.

Although marijuana has been used for centuries for the treatment of a variety of disorders, its therapeutic mechanisms are only now being understood.

The best-studied plant cannabinoid, delta9-tetrahydrocannabinol (THC), produced by Cannabis sativa and found in marijuana, has shown evidence of being immunosuppressive in both in vivo and in vitro.

These studies are theoretically in agreement with the suggestions of others that cannabinoid receptor agonists would be beneficial for the treatment of MS in humans.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2219523/

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/

A biosynthetic pathway for anandamide

“The endocannabinoid arachidonoyl ethanolamine (anandamide) is a lipid transmitter synthesized and released “on demand” by neurons in the brain. Anandamide is also generated by macrophages where its endotoxin (LPS)-induced synthesis has been implicated in the hypotension of septic shock and advanced liver cirrhosis. Anandamide can be generated from its membrane precursor, N-arachidonoyl phosphatidylethanolamine (NAPE) through cleavage by a phospholipase D (NAPE-PLD).

Here we document a biosynthetic pathway for anandamide in mouse brain…

Both PTPN22 and endocannabinoids have been implicated in autoimmune diseases, suggesting that the PLC/phosphatase pathway of anandamide synthesis may be a pharmacotherapeutic target.

The observed exclusive role of the PLC/phosphatase pathway in LPS-induced AEA synthesis may offer therapeutic targets for the treatment of these conditions.

Furthermore, cannabinoids have immunosuppressive effects in autoimmune models of multiple sclerosis and diabetes, and mice deficient in CB1 receptors show increased susceptibility to neuronal damage found in autoimmune encephalitis…”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1557387/#!po=23.3333

Multiple sclerosis may disrupt endocannabinoid brain protection mechanism

An external file that holds a picture, illustration, etc.
Object name is zpq0180620550001.jpg

“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/

Experimental autoimmune encephalomyelitis disrupts endocannabinoid-mediated neuroprotection

An external file that holds a picture, illustration, etc.<br />
Object name is zpq0130617490001.jpg

“Focal cerebral ischemia and traumatic brain injury induce an escalating amount of cell death because of harmful mediators diffusing from the original lesion site.

Evidence suggests that healthy cells surrounding these lesions attempt to protect themselves by producing endocannabinoids (eCBs) and activating cannabinoid receptors, the molecular target for marijuana-derived compounds.

Indeed, activation of cannabinoid receptors reduces the production and diffusion of harmful mediators.

Here, we provide evidence that an exception to this pattern is found in experimental autoimmuneencephalomyelitis (EAE), a mouse model of multiple sclerosis…

Our data suggest that the high level of CNS IFN-gamma associated with EAE disrupts eCB-mediated neuroprotection while maintaining functional cannabinoid receptors, thus providing additional support for the use of cannabinoid-based medicine to treat multiple sclerosis.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1458883/

Anandamide Attenuates Th-17 Cell-Mediated Delayed-Type Hypersensitivity Response by Triggering IL-10 Production and Consequent microRNA Induction

thumbnail

“Endogenous cannabinoids [endocannabinoids] are lipid signaling molecules that have been shown to modulate immune functions..

Cannabinoids are compounds derived from the Cannabis sativa plant and exert many effects on the immune system. Cannabinoids have potential as therapeutic agents in several different disease conditions, including experimental autoimmune hepatitis, Multiple Sclerosis, and Graft vs. Host Disease…

This report suggested a role of the endogenous cannabinoid system in regulation of allergic inflammation.

These studies also suggest that endogenous cannabinoid system is one of the homeostatic mechanisms that the body employs to down-regulate immune response to foreign antigens as well as combat autoimmunity.

Targeting of this system could yield valuable therapeutics in the future.”

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0093954