Cannabinoids as Therapeutic Agents for Ablating Neuroinflammatory Disease

“Cannabinoids have been reported to alter the activities of immune cells in vitro and in vivo. These compounds may serve as ideal agents for adjunct treatment of pathological processes that have a neuroinflammatory component. As highly lipophilic molecules, they readily access the brain. Furthermore, they have relatively low toxicity and can be engineered to selectively target cannabinoid receptors. To date, two cannabinoid receptors have been identified, characterized and designated CB1 and CB2. CB1 appears to be constitutively expressed within the CNS while CB2 apparently is induced during inflammation. The inducible nature of CB2 extends to microglia, the resident macrophages of the brain that play a critical role during early stages of inflammation in that compartment. Thus, the cannabinoid-cannabinoid receptor system may prove therapeutically manageable in ablating neuropathogenic disorders such as Alzheimer’s disease, multiple sclerosis, amyotrophic.”

“The marijuana plant, Cannabis sativa, has been consumed therapeutically and recreationally for centuries because of its medicinal and psychotropic attributes. Cannabis contains a complex array of substances, including a group of terpenoid-like, highly lipophilic compounds referred to as cannabinoids. To date, over 60 cannabinoids have been identified from the marijuana plant. Cannabinoids account for the majority of the effects attributed to marijuana that users experience, including euphoria, impaired perception and memory, and mild sedation. While cannabinoids have been used to abolish loss of appetite and to ablate nausea and pain in patients suffering from severe medical disorders, these compounds also possess immune modulatory properties that may prove detrimental to human health. However, accumulating evidence suggests that cannabinoids also may serve as therapeutic agents in neuropathogenic diseases, pathologically hallmarked by elicitation of pro-inflammatory factors by cells of the central nervous system (CNS) and infiltrated peripheral immunocytes. Cannabinoids have the potential to be ideal therapeutic candidates in abolishing inflammatory neuropathies in that they can readily penetrate the blood brain barrier (BBB) to access the brain, have low levels of toxicity, and can specifically exert their effects through cannabinoid receptors. The major cannabinoid receptor type that appears to be targeted in neuroinflammation is cannabinoid receptor 2 (CB2). This receptor has been identified in select cells of the CNS, can be induced on demand during early inflammatory events, and has been shown to attenuate pro-inflammatory cytokine production by microglia, the resident macrophages of the brain that play a central role in many neuropathological processes.”

“In the present review the immune modulatory properties of cannabinoids, including their relation to interaction with cannabinoid receptors as linked to inflammatory neuropathies will be discussed. Included in this review will be an overview of the signal transduction cascades associated with cannabinoid receptors, and the effects of cannabinoid receptor signaling on immune cell function and immunity, and more importantly in the CNS. These discussions will lay the groundwork for the critical element of this review, in which we explore the potential of cannabinoid receptors to serve as therapeutic targets to attenuate the elicitation of pro-inflammatory mediators during neuropathogenic diseases and disorders such as Alzheimer’s disease (AD), Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS), HIV Encephalitis (HIVE), Closed Head Injury (CHI) and Granulomatous Amebic Encephalitis (GAE).”

“It is apparent that therapeutic intervention at an early stage of neuroinflammation is critical. The recognition that microglia express CB2 and that its activation results in ablation of untoward immune responses indicates that this receptor may serve as an ideal therapeutic target. Cannabinoids, as highly lipophilic compounds, can readily penetrate the BBB and access the brain. Furthermore, these compounds can be designed to have low toxicity, minimal psychotropic properties, and to selectively target cells that express the CB2, particularly microglia that serve as endogenous immune cells of the CNS and that play a prominent role in neuroinflammatory processes.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2750822/

The endocannabinoid system in peripheral lymphocytes as a mirror of neuroinflammatory diseases.

Abstract

“During immuno-mediated attack of the brain, activation of endocannabinoids represents a protective mechanism, aimed at reducing both neurodegenerative and inflammatory damage through various and partially converging mechanisms that involve neuronal and immune cells. Here, we review the main alterations of the endocannabinoid system (ECS) within the central nervous system and in peripheral blood mononuclear cells, in order to discuss the intriguing observation that elements of the peripheral ECS mirror central dysfunctions of endocannabinoid signaling. As a consequence, elements of blood ECS might serve as novel, non-invasive diagnostic tools of several neurological disorders, and targeting the ECS might be useful for therapeutic purposes. In addition, we discuss the appealing working hypothesis that the presence of type-1 cannabinoid receptors on the luminal side, and that of type-2 cannabinoid receptors on the abluminal side of the blood-brain barrier, could drive a unidirectional transport of AEA in the luminal –> abluminal direction (i.e., from blood to brain), thus implying that blood may be a reservoir of AEA for the brain. On this basis, it can be expected that an unbalance of the endogenous tone of AEA in the blood may sustain a similar unbalance of its level within the brain, as demonstrated in Huntington’s disease, Parkinson’s disease, multiple sclerosis, attention-deficit/hyperactivity disorder, schizophrenia, depression and headache.”

http://www.ncbi.nlm.nih.gov/pubmed/18781987