“Celiac disease (CD) is a chronic inflammatory disease of the small bowel that occurs with the ingestion of gluten, found in several grains products. Although HLA-DQ2 variant is required for the gluten-derived peptide gliadin presentation by antigen-presenting cells to T-cells, non-HLA genetic factors account for the majority of heritable risk. Several genome-wide association studies have identified susceptibility loci for CD on chromosome 1. Cells of the immune system express the cannabinoid receptor type 2 (CB2), a plasma-membrane receptor activated by both endogenous and exogenouscannabinoids. Consistent data evidence that CB2 is linked to a variety of immune functional events and that, in the course of an inflammatory process, an increased number of receptors becomes available for activation. The cannabinoid receptor type 2 gene (CNR2; GeneID1269) maps on 1p36.11. In order to investigate the possible involvement of CB2 in CD establishment, immunohistochemistry toward CB2 receptor and CD4+ cells in small bowel biopsies from celiac children and association analysis, through TaqMan assay, of a CNR2 common missense variant, rs35761398 (CAA/CGG), resulting in the aminoacidic substitution of Glutamine at codon 63 with Arginine (Q63R), in a cohort of 327 South Italian children have been performed. We observed in this study that CB2 is up-regulated in CD small bowel biopsies and CNR2 rs35761398 is significantly associated with CD (χ(2) = 37.064; d.f. 1; p = 1.14 × 10(-9)). Our findings suggest a role of CB2 in CD. The Q63R variant, increasing more than six-fold the risk for CD susceptibility, might eventually represent a novel molecular biomarker for CD risk stratification. Indeed, we provide here further evidence that CB2 receptor plays a critical role in autoimmunity susceptibility and indicates that it represents a molecular target to pharmacologically modulate the immune components in CD.”
Author Archives: David Worrell
Overactivity of the intestinal endocannabinoid system in celiac disease and in methotrexate-treated rats.
“The endocannabinoid system is upregulated in both human inflammatory bowel diseases and experimental models of colitis. In this study, we investigated whether this upregulation is a marker also of celiac disease-induced atrophy. The levels of the cannabinoid CB(1) receptor, of the endocannabinoids, anandamide, and 2-arachidonoyl-glycerol (2-AG), and of the anti-inflammatory mediator palmitoylethanolamide (PEA) were analyzed in bioptic samples from the duodenal mucosa of celiac patients at first diagnosis assessed by the determination of antiendomysial antibodies and histological examination. Samples were analyzed during the active phase of atrophy and after remission and compared to control samples from non-celiac patients. The levels of anandamide and PEA were significantly elevated (approx. 2- and 1.8-fold, respectively) in active celiac patients and so were those of CB(1) receptors. Anandamide levels returned to normal after remission with a gluten-free diet. We also analyzed endocannabinoid and PEA levels in the jejunum of rats 2, 3, and 7 days after treatment with methotrexate, which causes inflammatory features (assessed by histopathological analyses and myeloperoxidase activity) similar to those of celiac patients. In both muscle/serosa and mucosa layers, the levels of anandamide, 2-AG, and PEA peaked 3 days after treatment and returned to basal levels at remission, 7 days after treatment. Thus, intestinal endocannabinoid levels peak with atrophy and regress with remission in both celiac patients and methotrexate-treated rats. The latter might be used as a model to study the role of the endocannabinoid system in celiac disease.”
Abnormal anandamide metabolism in celiac disease.
“The endocannabinoid system has been extensively investigated in experimental colitis and inflammatory bowel disease, but not in celiac disease, where only a single study showed increased levels of the major endocannabinoid anandamide in the atrophic mucosa. On this basis, we aimed to investigate anandamide metabolism in celiac disease by analyzing transcript levels (through quantitative real-time reverse transcriptase-polymerase chain reaction), protein concentration (through immunoblotting) and activity (through radioassays) of enzymes responsible for anandamide synthesis (N-acylphosphatidyl-ethanolamine specific phospholipase D, NAPE-PLD) and degradation (fatty acid amide hydrolase, FAAH) in the duodenal mucosa of untreated celiac patients, celiac patients on a gluten-free diet for at least 12 months and control subjects. Also, treated celiac biopsies cultured ex vivo with peptic-tryptic digest of gliadin were investigated. Our in vivo experiments showed that mucosal NAPE-PLD expression and activity are higher in untreated celiac patients than treated celiac patients and controls, with no significant difference between the latter two groups. In keeping with the in vivo data, the ex vivo activity of NAPE-PLD was significantly enhanced by incubation of peptic-tryptic digest of gliadin with treated celiac biopsies. On the contrary, in vivo mucosal FAAH expression and activity did not change in the three groups of patients, and accordingly, mucosal FAAH activity was not influenced by treatment with peptic-tryptic digest of gliadin. In conclusion, our findings provide a possible pathophysiological explanation for the increased anandamide concentration previously shown in active celiac mucosa.”
Altered Expression of Type-1 and Type-2 Cannabinoid Receptors in Celiac Disease
“Anandamide (AEA) is the prominent member of the endocannabinoid family and its biological action is mediated through the binding to both type-1 (CB1) and type-2 (CB2) cannabinoid receptors (CBR). The presence of AEA and CBR in the gastrointestinal tract highlighted their pathophysiological role in several gut diseases, including celiac disease. Here, we aimed to investigate the expression of CBR at transcriptional and translational levels in the duodenal mucosa of untreated celiac patients, celiac patients on a gluten-free diet for at least 12 months and control subjects. Also biopsies from treated celiac patients cultured ex vivo with peptic-tryptic digest of gliadin were investigated. Our data show higher levels of both CB1 and CB2 receptors during active disease and normal CBR levels in treated celiac patients. In conclusion, we demonstrate an up-regulation of CB1 and CB2 mRNA and protein expression, that points to the therapeutic potential of targeting CBR in patients with celiac disease.
In conclusion, our findings together with those published in a previous study, suggest that an abnormal modulation of the endocannabinoid system, both at CBR and AEA levels, may be implicated in the pathogenesis of celiac disease. Further studies are needed to ascertain whether targeting these changes might have a therapeutic role, at least in those patients who are no longer responsive to gluten-free diet.”
Medical Marijuana Use in Oncology: A Review.
“Medicinal marijuana use is currently legal in 23 states and the District of Columbia. As more states approve marijuana use for medical indications, physicians will be asked by their patients for more information regarding the risks and benefits of use. This article reviews the history, adverse effects, and proposed mechanisms of action of marijuana and summarizes the available literature regarding symptom relief and therapeutic value in patients with cancer.
OBSERVATIONS:
Marijuana in oncology may have potential for use as an antiemetic, for refractory cancer pain, and as an antitumor agent. However, much of the data are based on animal data, small trials, or are outdated.
CONCLUSIONS AND RELEVANCE:
More research is needed in all areas related to the therapeutic use of marijuana in oncology.”
Stimulation of brain glucose uptake by cannabinoid CB2 receptors and its therapeutic potential in Alzheimer’s disease.
“Cannabinoid CB2 receptors (CB2Rs) are emerging as important therapeutic targets in brain disorders that typically involve neurometabolic alterations. We here addressed the possible role of CB2Rs in the regulation of glucose uptake in the mouse brain.
Together, these results reveal a novel general glucoregulatory role for CB2Rs in the brain, raising therapeutic interest in CB2R agonists as nootropic agents.”
Cannabidiol and epilepsy: rationale and therapeutic potential.
“Despite the introduction of new antiepileptic drugs (AEDs), the quality of life and therapeutic response for patients with epilepsy remains still poor. Unfortunately, besides several advantages, these new AEDs have not satisfactorily reduced the number of refractory patients. Therefore, the need for different other therapeutic options to manage epilepsy is still a current issue.
To this purpose, emphasis has been given to phytocannabinoids, which have been medicinally used since ancient time in the treatment of neurological disorders including epilepsy.
In particular, the nonpsychoactive compound cannabidiol (CBD) has shown anticonvulsant properties, both in preclinical and clinical studies, with a yet not completely clarified mechanism of action.
However, it should be made clear that most phytocannabinoids do not act on the endocannabinoid system as in the case of CBD.
In in vivo preclinical studies, CBD has shown significant anticonvulsant effects mainly in acute animal models of seizures, whereas restricted data exist in chronic models of epilepsy as well as in animal models of epileptogenesis.
Likewise, clinical evidence seem to indicate that CBD is able to manage epilepsy both in adults and children affected by refractory seizures, with a favourable side effect profile.
However, to date, clinical trials are both qualitatively and numerically limited, thus yet inconsistent. Therefore, further preclinical and clinical studies are undoubtedly needed to better evaluate the potential therapeutic profile of CBD in epilepsy, although the actually available data is promising.”
Does modulation of the endocannabinoid system have potential therapeutic utility in cerebellar ataxia?
“Cerebellar ataxias represent a spectrum of disorders which are, however, linked by common symptoms of motor incoordination and are typically associated with deficient in Purkinje cell firing activity and, often, degeneration. Cerebellar ataxias currently lack a curative agent.
The endocannabinoid (eCB) system includes eCB compounds and their associated metabolic enzymes, together with cannabinoid receptors, predominantly the cannabinoid CB1 receptor (CB1 R) in the cerebellum; activation of this system in the cerebellar cortex is associated with deficits in motor coordination characteristic of ataxia, effects which can be prevented by CB1 R antagonists.
Of further interest are various findings that CB1 R deficits may also induce a progressive ataxic phenotype.
Together these studies suggest that motor coordination is reliant on maintaining the correct balance in eCB system signalling.
Recent work also demonstrates deficient cannabinoid signalling in the mouse ‘ducky2J ‘ model of ataxia.
In light of these points, the potential mechanisms whereby cannabinoids may modulate the eCB system to ameliorate dysfunction associated with cerebellar ataxias are considered.”
[Role of cannabinoid receptors in renal diseases].
“Chronic kidney disease remains a major challenge for public health systems and corresponds to the replacement of renal functional tissue by extracellular matrix proteins such as collagens and fibronectin. There is no efficient treatment to date for chronic kidney disease except nephroprotective strategies.
The cannabinoid system and more specifically the cannabinoid receptors 1 (CB1) and 2 (CB2) may represent a new therapeutic target in chronic kidney disease.
Experimental data obtained in models of diabetes and obesity suggested that CB1 blockade and CB2 stimulation may slow the development of diabetic nephropathy.
In human kidneys, CB1 expression is increased in various chronic nephropathies and correlates with renal function. Moreover, endogenous CB1 and CB2 ligands are greatly increased during renal fibrogenesis. A microarray analysis performed in an experimental model of renal fibrosis found that the gene encoding for the CB1 receptor was among the most upregulated genes. We also demonstrated that renal fibrogenesis could be reduced by CB1 inhibition and CB2 stimulation in an experimental model through a direct mechanism involving CB1 on myofibroblasts, which are the major effector cells during renal fibrosis.
Therefore, CB1 blockers may represent a novel therapeutic target in chronic kidney disease and diabetes.”
Cannabinoids inhibit insulin receptor signaling in pancreatic β-cells.
“Optimal glucose homeostasis requires exquisitely precise adaptation of the number of insulin-secreting β-cells in the islets of Langerhans. Insulin itself positively regulates β-cell proliferation in an autocrine manner through the insulin receptor (IR) signaling pathway.
It is now coming to light that cannabinoid 1 receptor (CB1R) agonism/antagonism influences insulin action in insulin-sensitive tissues. However, the cells on which the CB1Rs are expressed and their function in islets have not been firmly established. We undertook the current study to investigate if intraislet endogenous cannabinoids (ECs) regulate β-cell proliferation and if they influence insulin action.
These findings provide direct evidence for a functional interaction between CB1R and IR signaling involved in the regulation of β-cell proliferation and will serve as a basis for developing new therapeutic interventions to enhance β-cell function and proliferation in diabetes.”