Category Archives: Liver Disease

Attenuation of Experimental Autoimmune Hepatitis by Exogenous and Endogenous Cannabinoids: Involvement of Regulatory T Cells

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“The endocannabinoid system plays a protective role in various inflammatory diseases, and it is considered an attractive therapeutic target.”

“The aim of the present study was to determine the immunomodulatory effect of THC in the murine model of ConA-induced hepatitis. We demonstrate that a single injection of THC significantly ameliorates ConA-induced T-cell-mediated liver injury by up-regulating Forkhead helix transcription factor p3 (Foxp3)+ regulatory T cells and down-regulating inflammatory cytokines. Using select cannabinoid receptor agonists and antagonists, we demonstrate that THC mediates immune modulation in this model by signaling through both CB1 and CB2 receptors. We also demonstrate that anandamide, an endocannabinoid can effectively attenuate the disease.”

“There is growing interest in recent years to target cannabinoid receptors for treating liver diseases. In the current study, CB1 or CB2 activation alone had no anti-inflammatory effect on hepatitis. However, cannabinoids that bind to both CB1 and CB2 receptors (THC, CP55,940, WIN55212, and anandamide) effectively attenuated hepatitis. That CB1/CB2 mixed agonists could suppress the disease but not the coadministered CB1 and CB2 agonists indicates that both the cannabinoid receptors need to be activated simultaneously to produce the observed effect and that the different pharmacokinetics of the two coadministered agonists may not allow this to happen. Signaling through both the receptors is important because blocking either CB1 or CB2 could reverse the effect of THC.”

“Taken together, our data suggest that exogenous cannabinoids such as THC upon binding to CB1 and CB2 receptors on immune cells, induce apoptosis in effector T cells, up-regulate Treg function, and suppress inflammatory cytokines there by preventing ConA-induced activated T-cell-mediated liver injury. The observation that the anandamide treatment ameliorates ConA-induced hepatitis, together with FAAH deficiency or inhibition leading to increased resistance to the disease, strongly suggests that the endocannabinoid system serves to attenuate the inflammatory response in ConA-induced acute hepatitis. These findings raise the promising potential of developing novel pharmacological treatments for T-cell-mediated liver diseases.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828293/

Endocannabinoids in liver disease and hepatic encephalopathy.

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Abstract

“Chronic liver disease results from a variety of causes such as hepatitis virus infections, autoimmune processes and alcohol consumption. Its complications include fat deposition, hemodynamic changes and fibrosis. Clinically there may be progression to portal-hypertension and porto-systemic encephalopathy. Pioneering research from the laboratory of Kunos at NIH has stressed the importance of endocannabinoids (ECs) as mediators of some of the pathological processes in chronic liver disease. The present review summarizes the literature on the association between ECs and liver disease, as well as the therapeutic potential of ECs and exogenous cannabinoids in liver disease with emphasis on hepatic encephalopathy.”

http://www.ncbi.nlm.nih.gov/pubmed/18781986

Use of cannabinoids as a novel therapeutic modality against autoimmune hepatitis.

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Abstract

“Autoimmune hepatitis is a severe immune mediated chronic liver disease with a prevalence range between 50 and 200 cases per million in Western Europe and North America and mortality rates of up to 80% in untreated patients. The induction of CB1 and CB2 cannabinoid receptors during liver injury and the potential involvement of endocannabinoids in the regulation of this process have sparked significant interest in further evaluating the role of cannabinoid systems during hepatic disease. Cannabinoids have been shown to possess significant immunosuppressive and anti-inflammatory properties. Cannabinoid abuse has been shown to exacerbate liver fibrogenesis in patients with chronic hepatitis C infection involving CB1 receptor. Nonetheless, CB2 receptor activation may play a protective role during chronic liver diseases. Thus, differential targeting of cannabinoid receptors may provide novel therapeutic modality against autoimmune hepatitis. In this review, we summarize current knowledge on the role of endocannabinoids and exocannabinoids in the regulation of autoimmune hepatitis.”

http://www.ncbi.nlm.nih.gov/pubmed/19647124

Hepatitis C Virus Induces the Cannabinoid Receptor 1

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  “Chronic Hepatitis C (CHC) is one of the most common causes of hepatic fibrosis and cirrhosis with the World Health Organization (WHO) estimating that up to 3% (180 million people) of the world’s population are affected.”

 

“CB1 is up-regulated in CHC and is associated with increased steatosis in genotype 3. It is induced by the hepatitis C virus.”

“There has been much recent interest in the use of CB1 antagonists to treat both hepatic and metabolic disease and our findings emphasize the likely usefulness of these compounds in patients with hepatitis C. In addition to the amelioration of steatosis and fibrosis, CB1 blockade reduces portal pressure and can reverse mesenteric arterial dilatioN, making them useful in end stage liver disease as well.”

 

“Cannabis (Cannabis Sativa, marijuana) has been used for medicinal and ritual purposes for over 3 millennia, and remains the most commonly used recreational drug in the western world. The identification of the cannabinoid receptor 1 (CB1) in human brain some twenty years ago and the subsequent discovery of endogenous cannabinoids, has led to an understanding of the importance of the endocannabinoid system in health and disease.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941472/

Association between lipid accumulation and the cannabinoid system in Huh7 cells expressing HCV genes.

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Abstract

“Evidence from clinical and laboratory studies has accumulated indicating that the activation of the cannabinoid system is crucial for steatosis, especially in non-alcoholic fatty liver disease. However, the association between hepatitis C virus (HCV) infection and the cannabinoid system has not been well investigated and it is unclear whether steatosis in chronic hepatitis C develops via activation of the endocannabinoid/cannabinoid receptor signaling pathway. In this study, we examined the expression of a cannabinoid receptor (CB1) and the lipid accumulation in the hepatic Huh7 cell line, expressing HCV genes. We utilized Huh7/Rep-Feo-1b cells stably expressing HCV non-structural proteins (NS) 3, NS4, NS5A, and NS5B, as well as Tet-On Core-2 cells, in which the HCV core protein expression is inducible. Significantly higher levels of stored triglycerides were found in Huh7/Rep-Feo-1b cells compared to Huh7 cells. Also, triglyceride accumulation and CB1 receptor expression were down-regulated in Huh7/Rep-Feo-1b cells after HCV reduction by IFNα. Moreover, lipid accumulation appeared to increase after CB1 agonist treatment, while it decreased after CB1 antagonist treatment, although significant differences were not found compared to untreated cells. In Tet-On Core-2 cells, induction of HCV core protein expression did not affect CB1 expression or triglyceride accumulation. The results of this study in cultured cells suggest that HCV infection may activate the cannabinoid system and precede steatosis, but the core protein by itself may not have any effect on the cannabinoid system.”

http://www.ncbi.nlm.nih.gov/pubmed/21331443

Cannabinoids as novel anti-inflammatory drugs

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Figure 1

“Cannabinoids are a group of compounds that mediate their effects through cannabinoid receptors. The discovery of Δ9-tetrahydrocannabinol (THC) as the major psychoactive principle in marijuana, as well as the identification of cannabinoid receptors and their endogenous ligands, has led to a significant growth in research aimed at understanding the physiological functions of cannabinoids. Cannabinoid receptors include CB1, which is predominantly expressed in the brain, and CB2, which is primarily found on the cells of the immune system. The fact that both CB1 and CB2 receptors have been found on immune cells suggests that cannabinoids play an important role in the regulation of the immune system. Recent studies demonstrated that administration of THC into mice triggered marked apoptosis in T cells and dendritic cells, resulting in immunosuppression. In addition, several studies showed that cannabinoids downregulate cytokine and chemokine production and, in some models, upregulate T-regulatory cells (Tregs) as a mechanism to suppress inflammatory responses. The endocannabinoid system is also involved in immunoregulation. For example, administration of endocannabinoids or use of inhibitors of enzymes that break down the endocannabinoids, led to immunosuppression and recovery from immune-mediated injury to organs such as the liver. Manipulation of endocannabinoids and/or use of exogenous cannabinoids in vivo can constitute a potent treatment modality against inflammatory disorders. This review will focus on the potential use of cannabinoids as a new class of anti-inflammatory agents against a number of inflammatory and autoimmune diseases that are primarily triggered by activated T cells or other cellular immune components.”

“Cannabis, commonly known as marijuana, is a product of the Cannabis sativa plant and the active compounds from this plant are collectively referred to as cannabinoids. For several centuries, marijuana has been used as an alternative medicine in many cultures and, recently, its beneficial effects have been shown in: the treatment of nausea and vomiting associated with cancer chemotherapy; anorexia and cachexia seen in HIV/AIDS patients; and in neuropathic pain and spasticity in multiple sclerosis. Cannabinoid pharmacology has made important advances in recent years after the discovery of the cannabinoid receptors (CB1 and CB2). Cannabinoid receptors and their endogenous ligands have provided an excellent platform for the investigation of the therapeutic effects of cannabinoids. It is well known that CB1 and CB2 are heterotrimeric Gi/o-protein-coupled receptors and that they are both expressed in the periphery and the CNS. However, CB1 expression is predominant in the CNS, especially on presynaptic nerves, and CB2 is primarily expressed on immune cells.”

“Cannabinoids are potent anti-inflammatory agents and they exert their effects through induction of apoptosis, inhibition of cell proliferation, suppression of cytokine production and induction of T-regulatory cells (Tregs).”

“Executive summary

  • Cannabinoids, the active components of Cannabis sativa, and endogenous cannabinoids mediate their effects through activation of specific cannabinoid receptors known as cannabinoid receptor 1 and 2 (CB1 and CB2).
  • The cannabinoid system has been shown both in vivo and in vitro to be involved in regulating the immune system through its immunomodulatory properties.
  • Cannabinoids suppress inflammatory response and subsequently attenuate disease symptoms. This property of cannabinoids is mediated through multiple pathways such as induction of apoptosis in activated immune cells, suppression of cytokines and chemokines at inflammatory sites and upregulation of FoxP3+ regulatory T cells.
  • Cannabinoids have been tested in several experimental models of autoimmune disorders such as multiple sclerosis, rheumatoid arthritis, colitis and hepatitis and have been shown to protect the host from the pathogenesis through induction of multiple anti-inflammatory pathways.
  • Cannabinoids may also be beneficial in certain types of cancers that are triggered by chronic inflammation. In such instances, cannabinoids can either directly inhibit tumor growth or suppress inflammation and tumor angiogenesis.”                      http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828614/

Targeting the endocannabinoid system with cannabinoid receptor agonists: pharmacological strategies and therapeutic possibilities.

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Philosophical Transactions of the Royal Society B: Biological Sciences: 367 (1607)

“Human tissues express cannabinoid CB(1) and CB(2) receptors that can be activated by endogenously released ‘endocannabinoids’ or exogenously administered compounds in a manner that reduces the symptoms or opposes the underlying causes of several disorders in need of effective therapy. Three medicines that activate cannabinoid CB(1)/CB(2) receptors are now in the clinic: Cesamet (nabilone), Marinol (dronabinol; Δ(9)-tetrahydrocannabinol (Δ(9)-THC)) and Sativex (Δ(9)-THC with cannabidiol). These can be prescribed for the amelioration of chemotherapy-induced nausea and vomiting (Cesamet and Marinol), stimulation of appetite (Marinol) and symptomatic relief of cancer pain and/or management of neuropathic pain and spasticity in adults with multiple sclerosis (Sativex). This review mentions several possible additional therapeutic targets for cannabinoid receptor agonists. These include other kinds of pain, epilepsy, anxiety, depression, Parkinson’s and Huntington’s diseases, amyotrophic lateral sclerosis, stroke, cancer, drug dependence, glaucoma, autoimmune uveitis, osteoporosis, sepsis, and hepatic, renal, intestinal and cardiovascular disorders. It also describes potential strategies for improving the efficacy and/or benefit-to-risk ratio of these agonists in the clinic. These are strategies that involve (i) targeting cannabinoid receptors located outside the blood-brain barrier, (ii) targeting cannabinoid receptors expressed by a particular tissue, (iii) targeting upregulated cannabinoid receptors, (iv) selectively targeting cannabinoid CB(2) receptors, and/or (v) adjunctive ‘multi-targeting’.”  https://www.ncbi.nlm.nih.gov/pubmed/23108552

“Targeting the endocannabinoid system with cannabinoid receptor agonists: pharmacological strategies and therapeutic possibilities”  http://rstb.royalsocietypublishing.org/content/367/1607/3353.long

Recent developments in the therapeutic potential of cannabinoids.

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Abstract

“OBJECTIVE:

To examine the recent evidence that marijuana and other cannabinoids have therapeutic potential.

METHODS:

Literature published since 1997 was searched using the following terms: cannabinoid, marijuana, THC, analgesia, cachexia, glaucoma, movement, multiple sclerosis, neurological, pain, Parkinson, trial, vomiting. Qualifying clinical studies were randomized, double-blind, and placebo-controlled. Selected open-label studies and surveys are also discussed.

RESULTS:

A total of 15 independent, qualifying clinical trials were identified, of which only three had more than 100 patients each. Two large trials found that cannabinoids were significantly better than placebo in managing spasticity in multiple sclerosis. Patients self-reported greater sense of motor improvement in multiple sclerosis than could be confirmed objectively. In smaller qualifying trials, cannabinoids produced significant objective improvement of tics in Tourette’s disease, and neuropathic pain. A new, non-psychotropic cannabinoid also has analgesic activity in neuropathic pain. No significant improvement was found in levodopa-induced dyskinesia in Parkinson’s Disease or post-operative pain. No difference from active placebo was found for management of cachexia in a large trial. Some immune system parameters changed in HIV-1 and multiple sclerosis patients treated with cannabinoids, but the clinical significance is unknown. Quality of life assessments were made in only three of 15 qualifying clinical trials.

CONCLUSION:

Cannabinoids may be useful for conditions that currently lack effective treatment, such as spasticity, tics and neuropathic pain. New delivery systems for cannabinoids and cannabis-based medicinal extracts, as well as new cannabinoid derivatives expand the options for cannabinoid therapy. More well-controlled, large clinical tests are needed, especially with active placebo.”

http://www.ncbi.nlm.nih.gov/pubmed/15895873

Non-psychotropic plant cannabinoids: new therapeutic opportunities from an ancient herb.

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“Delta(9)-tetrahydrocannabinol binds cannabinoid (CB(1) and CB(2)) receptors, which are activated by endogenous compounds (endocannabinoids) and are involved in a wide range of physiopathological processes (e.g. modulation of neurotransmitter release, regulation of pain perception, and of cardiovascular, gastrointestinal and liver functions).

The well-known psychotropic effects of Delta(9)-tetrahydrocannabinol, which are mediated by activation of brain CB(1) receptors, have greatly limited its clinical use. However, the plant Cannabis contains many cannabinoids with weak or no psychoactivity that, therapeutically, might be more promising than Delta(9)-tetrahydrocannabinol.

Here, we provide an overview of the recent pharmacological advances, novel mechanisms of action, and potential therapeutic applications of such non-psychotropic plant-derived cannabinoids. Special emphasis is given to cannabidiol,

the possible applications of which have recently emerged in inflammation, diabetes, cancer, affective and neurodegenerative diseases, and to Delta(9)-tetrahydrocannabivarin, a novel CB(1) antagonist which exerts potentially useful actions in the treatment of epilepsy and obesity.”

http://www.ncbi.nlm.nih.gov/pubmed/19729208

The therapeutic potential of novel cannabinoid receptors.

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Cover image

“Cannabinoids produce a plethora of biological effects, including the modulation of neuronal activity through the activation of CB(1) receptors and of immune responses through the activation of CB(2) receptors. The selective targeting of either of these two receptor subtypes has clear therapeutic value. Recent evidence indicates that some of the cannabinomimetic effects previously thought to be produced through CB(1) and/or CB(2) receptors, be they on neuronal activity, on the vasculature tone or immune responses, still persist despite the pharmacological blockade or genetic ablation of CB(1) and/or CB(2) receptors. This suggests that additional cannabinoid and cannabinoid-like receptors exist. Here we will review this evidence in the context of their therapeutic value and discuss their true belonging to the endocannabinoid signaling system.”  http://www.ncbi.nlm.nih.gov/pubmed/19248809

“The therapeutic potential of novel cannabinoid receptors”  http://www.sciencedirect.com/science/article/pii/S0163725809000266