Category Archives: Endocannabinoid System

Hybrid inhibitor of peripheral cannabinoid-1 receptors and inducible nitric oxide synthase mitigates liver fibrosis

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“Liver fibrosis, a consequence of chronic liver injury and a way station to cirrhosis and hepatocellular carcinoma, lacks effective treatment.

Endocannabinoids acting via cannabinoid-1 receptors (CB1R) induce profibrotic gene expression and promote pathologies that predispose to liver fibrosis. CB1R antagonists produce opposite effects, but their therapeutic development was halted due to neuropsychiatric side effects.

Inducible nitric oxide synthase (iNOS) also promotes liver fibrosis and its underlying pathologies, but iNOS inhibitors tested to date showed limited therapeutic efficacy in inflammatory diseases.

Here, we introduce a peripherally restricted, orally bioavailable CB1R antagonist, which accumulates in liver to release an iNOS inhibitory leaving group.

Additionally, it was able to slow fibrosis progression and to attenuate established fibrosis. Thus, dual-target peripheral CB1R/iNOS antagonists have therapeutic potential in liver fibrosis.

Regarding the pharmacodynamics of the hybrid CB1R/iNOS inhibitor, two important principles have emerged from efforts to develop effective antifibrotic therapies. First, antifibrotic treatment strategies could aim to control the primary disease, to inhibit fibrogenic gene expression and signaling, to promote molecular mechanisms involved in fibrosis regression, or a combination of these. Second, with multiple molecular mechanisms and signaling pathways involved in fibrosis, targeting more than one could increase antifibrotic efficacy, and the hybrid CB1R/iNOS inhibitor embodies optimal characteristics on both accounts.

As to the first principle, both the endocannabinoid/CB1R system and iNOS are ideal targets, as they are known to be involved directly in the fibrotic process and also in the conditions predisposing to liver fibrosis, as detailed in the Introduction. An emerging major predisposing factor to liver fibrosis is nonalcoholic fatty liver disease, and CB1R blockade has proven effective in mitigating obesity-related hepatic steatosis in both rodent models and humans. The other two major predisposing factors, alcoholic fatty liver disease and viral hepatitis, also involve increased CB1R activity. Hepatic CB1R expression is induced either by chronic ethanol intake or the hepatitis C virus, and CB1R blockade mitigates alcohol-induced steatosis and inhibits hepatitis C virus production.

The dual targeting of peripheral CB1R and iNOS demonstrated here exemplifies the therapeutic gain obtained by simultaneously hitting more than one molecule, which could then engage distinct as well as convergent cellular pathways. The advantage of such an approach is highlighted by emerging experience with recently developed antifibrotic medications, which indicates that targeting a single pathway has limited effect on fibrotic diseases.

Thus, the approach illustrated by the present study has promise as an effective antifibrotic strategy.”

http://insight.jci.org/articles/view/87336

Cannabinoids, inflammation, and fibrosis.

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“Cannabinoids apparently act on inflammation through mechanisms different from those of agents such as nonsteroidal anti-inflammatory drugs (NSAIDs).

As a class, the cannabinoids are generally free from the adverse effects associated with NSAIDs. Their clinical development thus provides a new approach to treatment of diseases characterized by acute and chronic inflammation and fibrosis.

A concise survey of the anti-inflammatory actions of the phytocannabinoids Δ9-tetrahydrocannabinol (THC), cannabidiol, cannabichromene, and cannabinol is presented.

Mention is also made of the noncannabinoid plant components and pyrolysis products, followed by a discussion of 3 synthetic preparations-Cesamet (nabilone; Meda Pharmaceuticals, Somerset, NJ, USA), Marinol (THC; AbbVie, Inc., North Chicago, IL, USA), and Sativex (Cannabis extract; GW Pharmaceuticals, Cambridge United Kingdom)-that have anti-inflammatory effects. A fourth synthetic cannabinoid, ajulemic acid (CT-3, AJA; Resunab; Corbus Pharmaceuticals, Norwood, MA, USA), is discussed in greater detail because it represents the most recent advance in this area and is currently undergoing 3 phase 2 clinical trials by Corbus Pharmaceuticals.

The endogenous cannabinoids, including the closely related lipoamino acids, are then discussed. The review concludes with a presentation of a possible mechanism for the anti-inflammatory and antifibrotic actions of these substances.

Thus, several cannabinoids may be considered candidates for development as anti-inflammatory and antifibrotic agents. Of special interest is their possible use for treatment of chronic inflammation, a major unmet medical need.”

http://www.ncbi.nlm.nih.gov/pubmed/27435265

Expression of the Endocannabinoid Receptor 1 in Human Stroke: An Autoptic Study.

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“Stroke is one of the leading causes of disability and death in the world.

The endocannabinoid (eCB) system is upregulated in several neurological diseases including stroke. A previous animal study demonstrated an increased expression of the endocannabinoid receptor 1 (CB1R) in the penumbra area surrounding the ischemic core, suggesting a crucial role in inflammation/reperfusion after stroke. Regarding the localization of CB1/CB2 receptors, animal studies showed that cortical neurons, activated microglia, and astroglia are involved. Our aim was to evaluate the cerebral expression of CB1R in the ischemic brain areas of 9 patients who died due to acute cerebral infarction in the middle cerebral artery territory.

METHODS:

The cerebral autoptic tissue was collected within 48 hours since death. Ischemic and contralateral normal-appearing areas were identified. After tissue preprocessing, 4-µm-thick cerebral sections were incubated with the primary CB1R antibodies (Cayman Chemical Company, Ann Arbor, MI). Thereafter, all cerebral sections were hematoxylin treated. In each section, the total cell number and CB1R-positive cells were counted and the CB1R-positive cell count ratio was calculated. For statistical analysis, Student’s t-test was used.

RESULTS:

In normal tissue, CB1R-positive neurons were the majority; a few non-neuronal cells expressed CB1R. In the ischemic areas, a few neurons were detectable. A significant increase in total CB1R staining was found in the ischemic regions compared to contralateral areas.

CONCLUSIONS:

We found an increase in CB1R expression in the ischemic region (neuronal and non-neuronal cell staining), suggesting the inflammatory reaction to the ischemic insult. Whether such response might mediate neuroprotective actions or excitotoxicity-related detrimental effects is still unclear.”

http://www.ncbi.nlm.nih.gov/pubmed/27425766

Endocannabinoid system as a regulator of tumor cell malignancy – biological pathways and clinical significance

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“The endocannabinoid system (ECS) comprises cannabinoid receptors (CBs), endogenous cannabinoids, and enzymes responsible for their synthesis, transport, and degradation of (endo)cannabinoids.

To date, two CBs, CB1 and CB2, have been characterized; however, orphan G-protein-coupled receptor GPR55 has been suggested to be the third putative CB.

Several different types of cancer present abnormal expression of CBs, as well as other components of ECS, and this has been shown to correlate with the clinical outcome.

Although most effects of (endo)cannabinoids are mediated through stimulation of classical CBs, they also interact with several molecules, either prosurvival or proapoptotic molecules.

It should be noted that the mode of action of exogenous cannabinoids differs significantly from that of endocannabinoid and results from the studies on their activity both in vivo and in vitro could not be easily compared.

This review highlights the main signaling pathways involved in the antitumor activity of cannabinoids and the influence of their activation on cancer cell biology.

We also discuss changes in the expression pattern of the ECS in various cancer types that have an impact on disease progression and patient survival.

A growing amount of experimental data imply possible exploitation of cannabinoids in cancer therapy.”

https://www.dovepress.com/endocannabinoid-system-as-a-regulator-of-tumor-cell-malignancy-ndash-b-peer-reviewed-article-OTT

Cannabinoid activation of PPARα; a novel neuroprotective mechanism

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“The cannabinoids are a structurally diverse family of compounds with a large number of different biological targets.

Although CB1 receptor activation evokes neuroprotection in response to cannabinoids, some cannabinoids have been reported to be peroxisome proliferator activated receptor (PPAR) ligands, offering an alternative protective mechanism.

We have, therefore, investigated the ability of a range of cannabinoids to activate PPARα and for N-oleoylethanolamine (OEA), an endogenous cannabinoid-like compound (ECL), to evoke neuroprotection.

These data demonstrate the potential for a range of cannabinoid compounds, of diverse structures, to activate PPARα and suggest that at least some of the neuroprotective properties of these agents could be mediated by nuclear receptor activation.

In summary, the data presented here provide strong evidence that selected cannabinoids are PPARα agonists, and suggest a novel means by which the multiple effects of cannabinoids, in both the CNS and periphery, could be brought about.

In addition to its well-recognized role in lipid metabolism, PPARα activation showed obvious beneficial effects in ischaemic brain damage, which is likely to be connected with its anti-inflammatory action through the NF–κB pathway.

These discoveries not only broaden the potential use of cannabinoids as therapeutic agents, but also support PPARα as a new target for neuroprotective treatment.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2190030/

Endocannabinoids in the Gut.

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“Cannabis has been used medicinally for centuries to treat a variety of disorders, including those associated with the gastrointestinal tract.

The discovery of our bodies’ own “cannabis-like molecules” and associated receptors and metabolic machinery – collectively called the endocannabinoid system – enabled investigations into the physiological relevance for the system, and provided the field with evidence of a critical function for this endogenous signaling pathway in health and disease.

Recent investigations yield insight into a significant participation for the endocannabinoid system in the normal physiology of gastrointestinal function, and its possible dysfunction in gastrointestinal pathology. Many gaps, however, remain in our understanding of the precise neural and molecular mechanisms across tissue departments that are under the regulatory control of the endocannabinoid system.

This review highlights research that reveals an important – and at times surprising – role for the endocannabinoid system in the control of a variety of gastrointestinal functions, including motility, gut-brain mediated fat intake and hunger signaling, inflammation and gut permeability, and dynamic interactions with gut microbiota.”

http://www.ncbi.nlm.nih.gov/pubmed/27413788

5-lipoxygenase mediates docosahexaenoyl ethanolamide and N-arachidonoyl-L-alanine-induced reactive oxygen species production and inhibition of proliferation of head and neck squamous cell carcinoma cells.

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“Endocannabinoids have recently drawn attention as promising anti-cancer agents. We previously observed that anandamide (AEA), one of the representative endocannabinoids, effectively inhibited the proliferation of head and neck squamous cell carcinoma (HNSCC) cell lines in a receptor-independent manner. In this study, using HNSCC cell lines, we examined the anti-cancer effects and the mechanisms of action of docosahexaenoyl ethanolamide (DHEA) and N-arachidonoyl-L-alanine (NALA), which are polyunsaturated fatty acid (PUFA)-based ethanolamides like AEA. From these findings, we suggest that ROS production induced by the 5-LO pathway mediates the anti-cancer effects of DHEA and NALA on HNSCC cells. Finally, our findings suggest the possibility of a new cancer-specific therapeutic strategy, which utilizes 5-LO activity rather than inhibiting it.”  http://www.ncbi.nlm.nih.gov/pubmed/27411387

https://bmccancer.biomedcentral.com/articles/10.1186/s12885-016-2499-3

Expression and function of cannabinoid receptors CB1 and CB2 and their cognate cannabinoid ligands in murine embryonic stem cells.

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“Characterization of intrinsic and extrinsic factors regulating the self-renewal/division and differentiation of stem cells is crucial in determining embryonic stem (ES) cell fate.

ES cells differentiate into multiple hematopoietic lineages during embryoid body (EB) formation in vitro, which provides an experimental platform to define the molecular mechanisms controlling germ layer fate determination and tissue formation.

This work has not been addressed previously and yields new information on the function of cannabinoid receptors, CB1 and CB2, as components of a novel pathway regulating murine ES cell differentiation.

This study provides insights into cannabinoid system involvement in ES cell survival and hematopoietic differentiation.

Thus, these observations together with our results strongly suggest that both CB1 and CB2 activation are involved in the maintenance of mES cells and that the endocannabinoid system is essential in stem cell survival and stem cell hematopoietic differentiation.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1919431/

 

Regulation of hematopoietic stem cell trafficking and mobilization by the endocannabinoid system.

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“The cannabinoid receptors CB(1) and CB(2) are seven-transmembrane Gαi protein-coupled receptors and are expressed in certain mature hematopoietic cells.

We recently showed that these receptors are expressed in murine and human hematopoietic stem cells (HSCs) and that CB(2) agonists induced chemotaxis, enhanced colony formation of marrow cells, as well as caused in vivo mobilization of murine HSCs with short- and long-term repopulating abilities. Based on these observations, we have further explored the role of CB(2) and its agonist AM1241 on hematopoietic recovery following sublethal irradiation in mice.

Cannabinoid receptor 2 knockout mice (Cnr2(-/-) deficient mice) exhibited impaired recovery following sublethal irradiation as compared with irradiated wild-type (WT) mice, as determined by low colony-forming units and low peripheral blood counts. WT mice treated with CB(2) agonist AM1241 following sublethal irradiation demonstrated accelerated marrow recovery and increased total marrow cells (approximately twofold) and total lineage- c-kit(+) cells (approximately sevenfold) as well as enhanced HSC survival as compared with vehicle control-treated mice.

When the CB(2) agonist AM1241 was administered to WT mice 12 days before their sublethal irradiation, analysis of hematopoiesis in these mice showed decreased apoptosis of HSCs, enhanced survival of HSCs, as well as increase in total marrow cells and c-kit+ cells in the marrow.

Thus, CB(2) agonist AM1241 promoted recovery after sublethal irradiation by inhibiting apoptosis of HSCs and promoting survival, as well as enhancing the number of HSCs entering the cell cycle.”

http://www.ncbi.nlm.nih.gov/pubmed/22074629

Cannabinoids for Symptom Management and Cancer Therapy: The Evidence.

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“Cannabinoids bind not only to classical receptors (CB1 and CB2) but also to certain orphan receptors (GPR55 and GPR119), ion channels (transient receptor potential vanilloid), and peroxisome proliferator-activated receptors. Cannabinoids are known to modulate a multitude of monoamine receptors. Structurally, there are 3 groups of cannabinoids.

Multiple studies, most of which are of moderate to low quality, demonstrate that tetrahydrocannabinol (THC) and oromucosal cannabinoid combinations of THC and cannabidiol (CBD) modestly reduce cancer pain.

Dronabinol and nabilone are better antiemetics for chemotherapy-induced nausea and vomiting (CINV) than certain neuroleptics, but are not better than serotonin receptor antagonists in reducing delayed emesis, and cannabinoids have largely been superseded by neurokinin-1 receptor antagonists and olanzapine; both cannabinoids have been recommended for breakthrough nausea and vomiting among other antiemetics. Dronabinol is ineffective in ameliorating cancer anorexia but does improve associated cancer-related dysgeusia.

Multiple cancers express cannabinoid receptors directly related to the degree of anaplasia and grade of tumor.

Preclinical in vitro and in vivo studies suggest that cannabinoids may have anticancer activity.

Paradoxically, cannabinoid receptor antagonists also have antitumor activity.

There are few randomized smoked or vaporized cannabis trials in cancer on which to judge the benefits of these forms of cannabinoids on symptoms and the clinical course of cancer. Smoked cannabis has been found to contain Aspergillosis. Immunosuppressed patients should be advised of the risks of using “medical marijuana” in this regard.”

http://www.ncbi.nlm.nih.gov/pubmed/27407130