Human platelets express authentic CB₁ and CB₂ receptors

Role of omega-3 and omega-6 endocannabinoids in cardiopulmonary pharmacology

Endocannabinoids are derived from dietary omega-3 and omega-6 fatty acids and play an important role in regulation of inflammation, development, neurodegenerative diseases, cancer, and cardiovascular diseases. They elicit this effect via interactions with cannabinoid receptors 1 and 2 which are also targeted by plant derived cannabinoid from cannabis. The evidence of the involvement of the endocannabinoid system in cardiopulmonary function comes from studies that show that cannabis consumption leads to cardiovascular effect such as arrythmia and is beneficial in lung cancer patients. Moreover, omega-3 and omega-6 endocannabinoids play several important roles in cardiopulmonary system such as causing airway relaxation, suppressing atherosclerosis and hypertension. These effects are mediated via the cannabinoids receptors that are abundant in the cardiopulmonary system. Overall, this chapter reviews the known role of phytocannabinoids and endocannabinoids in the cardiopulmonary context.

Monoglyceride Lipase Deficiency Is Associated with Altered Thrombogenesis in Mice

Monoglyceride lipase (MGL) hydrolyzes monoacylglycerols (MG) to glycerol and one fatty acid. Among the various MG species, MGL also degrades 2-arachidonoylglycerol, the most abundant endocannabinoid and potent activator of the cannabinoid receptors 1 and 2. We investigated the consequences of MGL deficiency on platelet function using systemic (Mgl-/-) and platelet-specific Mgl-deficient (platMgl-/-) mice. Despite comparable platelet morphology, loss of MGL was associated with decreased platelet aggregation and reduced response to collagen activation. This was reflected by reduced thrombus formation in vitro, accompanied by a longer bleeding time and a higher blood volume loss. Occlusion time after FeCl3-induced injury was markedly reduced in Mgl-/- mice, which is consistent with contraction of large aggregates and fewer small aggregates in vitro. The absence of any functional changes in platelets from platMgl-/- mice is in accordance with lipid degradation products or other molecules in the circulation, rather than platelet-specific effects, being responsible for the observed alterations in Mgl-/- mice. We conclude that genetic deletion of MGL is associated with altered thrombogenesis.

Platelet storage: Progress so far

There is a crucial need for platelet transfusion during an emergency-surgery and treatment of platelet disorders. The unavailability of donors has furthermore increased the demand for platelet storage. Platelets have limited shelf life due to bacterial contamination and storage lesions. Temperature, materials, oxygen availability, media, platelet processing and manufacturing methods influence the platelet quality and viability during storage. The conception of various platelet additive solutions along with the advent of plastic storage during the 1980s led to enormous developments in platelet storage strategies. Cold storage of platelets gained attention despite its inability to contribute to platelet survival post-transfusion as it offers faster haemostasis. Several developments in platelet storage strategies over the years have improved the quality and shelf-life of stored platelets. Despite the progress, the efficacy of platelets during storage beyond a week has not been achieved. Antioxidants as additives have been explored in platelet storage and have proven to enhance the efficacy of platelets during prolonged storage. However, the molecular interactions of antioxidants in platelets can provide a better understanding of their mechanism of action. Optimization of dosage concentrations of antioxidants is also a critical parameter to be considered as they tend to exhibit toxicity at certain levels. This review provides comprehensive insights into the critical factors affecting platelet storage and the evolution of platelet storage. It also emphasizes the role of antioxidants as additives in platelet storage solutions and their future prospects towards better platelet banking.

The Endocannabinoid System: A Potential Therapeutic Target for Coagulopathies

Abnormal blood coagulation or coagulopathy is a common manifestation of many pathological conditions. It occurs when there is an imbalance between the activities of the coagulation system and the fibrinolytic system, leading to excessive or impaired intravascular blood clot formation, which can disturb blood flow causing ischemia or hemorrhage in the affected tissues. A growing body of evidence has demonstrated blood coagulation abnormalities in association with cannabinoid use, suggesting the involvement of the endogenous cannabinoid system (ECS) in modulating blood coagulation. However, the evidence in the literature has been controversial on whether cannabinoids promote or inhibit blood coagulation. The ECS has been extensively studied in recent years for its potential as a therapeutic target for many diseases. This review provides a brief introduction to the ECS and discusses the reported anticoagulatory and procoagulatory effects of various cannabinoids, highlighting some possible mechanisms that might underlie the observed effects. Understanding the coagulatory effects of cannabinoids and the interaction between the coagulation system and the ECS is vital for developing novel therapeutics for coagulopathies.

Chronic edible dosing of Δ9-tetrahydrocannabinol (THC) in nonhuman primates reduces systemic platelet activity and function

Cannabis usage has steadily increased as acceptance is growing for both medical and recreational reasons. Medical cannabis is administered for treatment of chronic pain based on the premise that the endocannabinoid system signals desensitize pain sensor neurons and produce anti-inflammatory effects. The major psychoactive ingredient of cannabis is Δ9-tetrahydrocannabinol (THC) that signals mainly through cannabinoid receptor-1 (CBr), which is also present on nonneuron cells including blood platelets of the circulatory system. In vitro, CBr-mediated signaling has been shown to acutely inhibit platelet activation downstream of the platelet collagen receptor glycoprotein (GP)VI. The systemic effects of chronic THC administration on platelet activity and function remain unclear. This study investigates the effects of chronic THC administration on platelet function using a nonhuman primate (NHP) model. Our results show that female and male NHPs consuming a daily THC edible had reduced platelet adhesion, aggregation, and granule secretion in response to select platelet agonists. Furthermore, a change in bioactive lipids (oxylipins) was observed in the female cohort after THC administration. These results indicate that chronic THC edible administration desensitized platelet activity and function in response to GPVI- and G-protein coupled receptor-based activation by interfering with primary and secondary feedback signaling pathways. These observations may have important clinical implications for patients who use medical marijuana and for providers caring for these patients.

Cannabinoid receptor CB1 and CB2 interacting proteins: Techniques, progress and perspectives

Cannabinoid receptors 1 and 2 (CB₁ and CB₂) are implicated in a range of physiological processes and have gained attention as promising therapeutic targets for a number of diseases. Protein-protein interactions play an integral role in modulating G protein-coupled receptor (GPCR) expression, subcellular distribution and signaling, and the identification and characterization of these will not only improve our understanding of GPCR function and biology, but may provide a novel avenue for therapeutic intervention. A variety of techniques are currently being used to investigate GPCR protein-protein interactions, including Förster/fluorescence and bioluminescence resonance energy transfer (FRET and BRET), proximity ligation assay (PLA), and bimolecular fluorescence complementation (BiFC). However, the reliable application of these methodologies is dependent on the use of appropriate controls and the consideration of the physiological context. Though not as extensively characterized as some other GPCRs, the investigation of CB₁ and CB₂ interacting proteins is a growing area of interest, and a range of interacting partners have been identified to date. This review summarizes the current state of the literature regarding the cannabinoid receptor interactome, provides commentary on the methodologies and techniques utilized, and discusses future perspectives.

Cannabinoid receptor type-1 partially mediates metabolic endotoxemia-induced inflammation and insulin resistance

Circulating levels of bacterial lipopolysaccharide (LPS) or endotoxin are chronically elevated in obesity (metabolic endotoxemia), resulting in low-grade inflammation. Metabolic endotoxemia has been identified as a triggering factor for obesity-associated metabolic complications such as insulin resistance. Furthermore, LPS has been shown to modulate endocannabinoid synthesis and notably to induce cannabinoid receptor type-1 (CB1) ligand synthesis. CB1 activation promotes inflammation, increases food intake and impairs insulin signaling. Therefore, we hypothesized that LPS acts through a CB1-dependent mechanism to aggravate inflammation and promote insulin resistance. Male Wistar rats fed a chow diet were implanted with mini-osmotic pumps delivering a low dose of LPS (n = 20; 12.5 μg/kg body weight (BW)/hr.) or saline (n = 10) continuously for six weeks. LPS-treated rats were injected daily with a CB1 antagonist (Rimonabant, SR141716A; 3 mg/kg, intraperitoneal (ip); LPS + CB1x; n = 10) or vehicle (1 mL/kg, LPS; n = 10). Control and LPS rats' food intake was matched to the LPS + CB1x group level. Despite no significant differences in body weight among groups, chronic exposure to low-level LPS altered hepatic endocannabinoid signaling, increased inflammation, and impaired insulin sensitivity and insulin clearance (P < 0.05). CB1 inhibition significantly attenuated LPS signaling (P < 0.05), which attenuated LPS-induced metabolic alterations. Therefore, we concluded that CB1 contributes to LPS-mediated inflammation and insulin resistance, suggesting that blocking CB1 signaling may have therapeutic benefits in reducing inflammation-induced metabolic abnormalities.

Anandamide Induces Platelet Nitric Oxide Synthase through AMP-Activated Protein Kinase

The objective of this study was to determine whether adenosine 5' monophosphate (AMP)-activated protein kinase (AMPK) is activated by anandamide (AEA) and is involved in endothelial nitric oxide synthase (eNOS) activation. We found that AEA stimulates and activates AMPKα through a Ca²⁺ -dependent/Calmodulin (CaM)-dependent pathway as the specific inhibitor of the Ca²⁺ /Calmodulin kinase kinase β (CaMKKβ) STO-609 abolishes the AMPK phosphorylation/activation. The same inhibiting effect is shown in platelets pretreated with LY294002, an inhibitor of phosphatidylinositol 3 kinase (PI3K), or with MK2206, an inhibitor of protein kinase B (AKT), suggesting that AMPK is downstream of the PI3K/AKT pathway. Moreover, the AEA-induced eNOS activation and the consequent nitric oxide (NO) and guanosine 3'-5' cyclic monophosphate (cGMP) increase are mediated by the CaMKKβ/AMPKα pathway as STO-609 significantly inhibits these parameters. In contrast, liver kinase B1 (LKB1) seems to be very poorly involved. One crucial effect of NO and cGMP elevation is the activation of protein kinase G that can phosphorylate the vasodilator-stimulated phosphoprotein (VASP). We have demonstrated that AEA stimulates VASP phosphorylation on both thr278 and ser239 that is strongly inhibited by STO-609, LY294002, and MK2206. Finally, AMPK phosphorylation/activation and VASP phosphorylation are significantly reduced by SR141716, the specific inhibitor of type 1 cannabinoid receptor (CB1). SR144528, an antagonist of type 2 cannabinoid receptor (CB2), has a less-potent effect, suggesting that the CB1 receptor is overall involved in the AEA effect. In conclusion, we show that the CaMKKβ/AMPKα pathway, downstream of the PI3K/AKT pathway, is activated by AEA in human platelets and leads to increase NO levels producing beneficial effects during ischemic conditions and contributing to extend platelet survival.

Activation of CaMKKβ/AMPKα pathway by 2-AG in human platelets

The objective of this study was to determine whether AMPK is activated by 2-arachidonoylglycerol (2-AG) and participates to the cytoskeleton control in human platelets. We found that 2-AG stimulates the AMPKα activation through a Ca²⁺ /Calmodulin-dependent pathway as the specific inhibition of the CaMKKβ by STO-609 inhibits the AMPKα phosphorylation/activation. Moreover, the CaMKKβ/AMPKα pathway activated by 2-AG is involved in the phosphorylation of cofilin, vasodilator stimulated phosphoprotein (VASP), and myosin light chain (MLCs). These proteins participate to actin cytoskeletal remodelling during aggregation. We found that the phosphorylation/activation inhibition of these proteins is associated with a significant reduction in actin polymerization, aggregation, ATP, and α-granule secretion. Finally, AMPKα activation, Cofilin, VASP, and MLCs phosphorylation are significantly reduced by SR141716, the specific inhibitor of type 1 cannabinoid (CB1) receptor, suggesting that the CB1 receptor is involved in the 2-AG effect. In conclusion, we have shown that the CaMKKβ/AMPKα pathway is activated by 2-AG in human platelets and controls the phosphorylation of key proteins involved in actin polymerization and aggregation.

The CB2 receptor and its role as a regulator of inflammation

The CB2 receptor is the peripheral receptor for cannabinoids. It is mainly expressed in immune tissues, highlighting the possibility that the endocannabinoid system has an immunomodulatory role. In this respect, the CB2 receptor was shown to modulate immune cell functions, both in cellulo and in animal models of inflammatory diseases. In this regard, numerous studies have reported that mice lacking the CB2 receptor have an exacerbated inflammatory phenotype. This suggests that therapeutic strategies aiming at modulating CB2 signaling could be promising for the treatment of various inflammatory conditions. Herein, we review the pharmacology of the CB2 receptor, its expression pattern, and the signaling pathways induced by its activation. We next examine the regulation of immune cell functions by the CB2 receptor and the evidence obtained from primary human cells, immortalized cell lines, and animal models of inflammation. Finally, we discuss the possible therapies targeting the CB2 receptor and the questions that remain to be addressed to determine whether this receptor could be a potential target to treat inflammatory disease.

Endocannabinoids and the Cardiovascular System in Health and Disease

The endocannabinoid system is widely distributed throughout the cardiovascular system. Endocannabinoids play a minimal role in the regulation of cardiovascular function in normal conditions, but are altered in most cardiovascular disorders. In shock, endocannabinoids released within blood mediate the associated hypotension through CB(1) activation. In hypertension, there is evidence for changes in the expression of CB(1), and CB(1) antagonism reduces blood pressure in obese hypertensive and diabetic patients. The endocannabinoid system is also upregulated in cardiac pathologies. This is likely to be cardioprotective, via CB(2) and CB(1) (lesser extent). In the vasculature, endocannabinoids cause vasorelaxation through activation of multiple target sites, inhibition of calcium channels, activation of potassium channels, NO production and the release of vasoactive substances. Changes in the expression or function of any of these pathways alter the vascular effect of endocannabinoids. Endocannabinoids have positive (CB(2)) and negative effects (CB(1)) on the progression of atherosclerosis. However, any negative effects of CB(1) may not be consequential, as chronic CB(1) antagonism in large scale human trials was not associated with significant reductions in atheroma. In neurovascular disorders such as stroke, endocannabinoids are upregulated and protective, involving activation of CB(1), CB(2), TRPV1 and PPARα. Although most of this evidence is from preclinical studies, it seems likely that cannabinoid-based therapies could be beneficial in a range of cardiovascular disorders.

Coronary thrombosis and marijuana smoking: a case report and narrative review of the literature

We encountered evidence of myocardial infarction due to coronary thrombosis in an autopsy of an occasional marijuana smoker. These findings prompted us to perform a narrative review of the literature to determine when post-mortem toxicological tests may support a temporal relationship between marijuana smoking and cardiovascular disease. Toxicological examination showed the presence of Δ-9-tetrahydrocannabinol, its main metabolite and cannabinol in blood and urine. Quali-quantitative analysis revealed that Δ-9-tetrahydrocannabinol was taken within 2 h of the onset of cardiovascular symptoms, according to circumstantial data. Post-mortem toxicological results must take into account the degradation and post-mortem redistribution of analytes. However, for any inference about the specific cardiovascular triggering effect of Δ-9-tetrahydrocannabinol intake, we maintain that cannabinoid analysis in blood samples must be considered an essential requirement to estimate the time of last intake and avoid incomplete documentation. The literature, combined with the present case report, highlights an association between marijuana use and negative cardiovascular events, although few authors have supported their conclusions with toxicological results. Thus, additional research is needed.

Regulation of cAMP Intracellular Levels in Human Platelets Stimulated by 2-Arachidonoylglycerol

We demonstrated that in human platelets the endocannabinoid 2-arachidonoylglycerol (2-AG) decreased dose- and time-dependently cAMP intracellular levels. No effect on cAMP decrease induced by 2-AG was observed in the presence of the adenylate cyclase inhibitor SQ22536 as well in platelets pretreated with the thromboxane A2 receptor antagonist, SQ29548 or with aspirin, inhibitor of arachidonic acid metabolism through the cyclooxygenase pathway. An almost complete recovering of cAMP level was measured in platelets pretreated with the specific inhibitor of phosphodiesterase (PDE) 3A, milrinone. In platelets pretreated with LY294002 or MK2206, inhibitors of PI3K/AKT pathway, and with U73122, inhibitor of phospholipase C pathway, only a partial prevention was shown. cAMP intracellular level depends on synthesis by adenylate cyclase and hydrolysis by PDEs. In 2-AG-stimulated platelets adenylate cyclase activity seems to be unchanged. In contrast PDEs appear to be involved. In particular PDE3A was specifically activated, as milrinone reversed cAMP reduction by 2-AG. 2-AG enhanced PDE3A activity through its phosphorylation. The PI3K/AKT pathway and PKC participate to this PDE3A phosphorylation/activation mechanism as it was greatly inhibited by platelet pretreatment with LY294002, MK2206, U73122, or the PKC specific inhibitor GF109203X. Taken together these data suggest that 2-AG potentiates its power of platelet agonist reducing cAMP intracellular level.

2-Arachidonoylglycerol enhances platelet formation from human megakaryoblasts

Platelets modulate vascular system integrity, and their loss is critical in haematological pathologies and after chemotherapy. Therefore, identification of molecules enhancing platelet production would be useful to counteract thrombocytopenia. We have previously shown that 2-arachidonoylglycerol (2-AG) acts as a true agonist of platelets, as well as it commits erythroid precursors toward the megakaryocytic lineage. Against this background, we sought to further interrogate the role of 2-AG in megakaryocyte/platelet physiology by investigating terminal differentiation, and subsequent thrombopoiesis. To this end, we used MEG-01 cells, a human megakaryoblastic cell line able to produce in vitro platelet-like particles. 2-AG increased the number of cells showing ruffled surface and enhanced surface expression of specific megakaryocyte/platelet surface antigens, typical hallmarks of terminal megakaryocytic differentiation and platelet production. Changes in cytoskeleton modeling also occurred in differentiated megakaryocytes and blebbing platelets. 2-AG acted by binding to CB1 and CB2 receptors, because specific antagonists reverted its effect. Platelets were split off from megakaryocytes and were functional: they contained the platelet-specific surface markers CD61 and CD49, whose levels increased following stimulation with a natural agonist like collagen. Given the importance of 2-AG for driving megakaryopoiesis and thrombopoiesis, not surprisingly we found that its hydrolytic enzymes were tightly controlled by classical inducers of megakaryocyte differentiation. In conclusion 2-AG, by triggering megakaryocyte maturation and platelet release, may have clinical efficacy to counteract thrombocytopenia-related diseases.

Downstream effects of endocannabinoid on blood cells: implications for health and disease

Endocannabinoids (eCBs), among which N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) are the most biologically active members, are polyunsaturated lipids able to bind cannabinoid, vanilloid and peroxisome proliferator-activated receptors. Depending on the target engaged, these bioactive mediators can regulate different signalling pathways, at both central and peripheral levels. The biological action of eCBs is tightly controlled by a plethora of metabolic enzymes which, together with the molecular targets of these substances, form the so-called "endocannabinoid system". The ability of eCBs to control manifold peripheral functions has received a great deal of attention, especially in the light of their widespread distribution in the body. In particular, eCBs are important regulators in blood, where they modulate haematopoiesis, platelet aggregation and apoptosis, as well as chemokine release and migration of immunocompetent cells. Here, we shall review the current knowledge on the pathophysiological roles of eCBs in blood. We shall also discuss the involvement of eCBs in those disorders affecting the haematological system, including cancer and inflammation. Knowledge gained to date underlines a fundamental role of the eCB system in blood, thus suggesting that it may represent a therapeutic promise for a broad range of diseases involving impaired hematopoietic cell functions.

Regulation of inflammation by cannabinoids, the endocannabinoids 2-arachidonoyl-glycerol and arachidonoyl-ethanolamide, and their metabolites

2-Arachidonoyl-glycerol (2-AG) and arachidonyl-ethanolamide (AEA) are endocannabinoids that have been implicated in many physiologic disorders, including obesity, metabolic syndromes, hepatic diseases, pain, neurologic disorders, and inflammation. Their immunomodulatory effects are numerous and are not always mediated by cannabinoid receptors, reflecting the presence of an arachidonic acid (AA) molecule in their structure, the latter being the precursor of numerous bioactive lipids that are pro- or anti-inflammatory. 2-AG and AEA can thus serve as a source of AA but can also be metabolized by most eicosanoid biosynthetic enzymes, yielding additional lipids. In this regard, enhancing endocannabinoid levels by using endocannabinoid hydrolysis inhibitors is likely to augment the levels of these lipids that could regulate inflammatory cell functions. This review summarizes the metabolic pathways involved in the biosynthesis and metabolism of AEA and 2-AG, as well as the biologic effects of the 2-AG and AEA lipidomes in the regulation of inflammation.

Regulation of inflammation and proliferation of human bladder carcinoma cells by type-1 and type-2 cannabinoid receptors

AIMS

Pro-inflammatory cytokines, growth and angiogenic factors released by leukocytes are involved in carcinogenesis and cancer progression, but they are also crucial for fighting tumour growth and spreading. We have previously demonstrated that endocannabinoids modulate cell-to-cell crosstalk during inflammation. Here, we investigated the inflammatory and tumourigenic properties of endocannabinoids in a human urinary bladder carcinoma cell line.

MAIN METHODS

Endocannabinoid-treated ECV304 cells were checked for tumour necrosis factor (TNF)-α secretion (by ELISA assay) and surface exposure of selectins (by in situ ELISA and FACS analysis). ECV304/Jurkat T cell interaction was assessed by adhesion and live imaging experiments. Proliferation rate, cell death and cell cycle were determined by FACS analysis.

KEY FINDINGS

By binding to type-1 (CB1) and type-2 (CB2) cannabinoid receptors, the endocannabinoid 2-arachidonoylglycerol (2-AG) exacerbates the pro-inflammatory status surrounding bladder carcinoma ECV304 cells, by: (i) enhancing TNF-α release, (ii) increasing surface exposure of P- and E-selectins, and (iii) allowing Jurkat T lymphocytes to adhere to treated cancer cells. We also found that the CB1 inverse agonist AM281, unlike 2-AG, decreases cancer proliferation by delaying cell cycle progression.

SIGNIFICANCE

Our data suggest that 2-AG modulates the inflammatory milieu of cancer cells in vitro, while AM281 plays a more specific role in proliferation. Collectively, these findings suggest that CB receptors may play distinct roles in cancer biology, depending on the specific ligand employed.

CONCLUSIONS

The in vivo assessment of the role of CB receptors in inflammation and cancer might be instrumental in broadening the understanding about bladder cancer biology.

Endocannabinoids control platelet activation and limit aggregate formation under flow

Background

The endocannabinoid system has previously been implicated in the regulation of neurons and inflammatory cells. Additionally, it has been reported that endocannabinoid receptors are present on circulating platelets, but there has been conflicting evidence on their contribution to platelet function.

Objectives

Our aim was to examine the role of endocannabinoids in platelet function in vitro and in vivo.

Methods and Results

We studied the effects of the well-characterized endogenous endocannabinoid anandamide on platelet aggregation in suspension, α-granule release, calcium mobilization, Syk phosphorylation, as well as platelet spreading and aggregate formation under flow. Anandamide inhibits platelet aggregation and α-granule release by collagen, collagen-derived peptide CRP-XL, ADP, arachidonic acid and thromboxane A2 analogue U46619. However, activation via thrombin receptor PAR-1 stays largely unaffected. Calcium mobilization is significantly impaired when platelets are stimulated with collagen or CRP-XL, but remains normal in the presence of the other agonists. In line with this finding, we found that anandamide prevents collagen-induced Syk phosphorylation. Furthermore, anandamide-treated platelets exhibit reduced spreading on immobilized fibrinogen, have a decreased capacity for binding fibrinogen in solution and show perturbed platelet aggregate formation under flow over collagen. Finally, we investigated the influence of Cannabis sativa consumption by human volunteers on platelet activation. Similar to our in vitro findings with anandamide, ex vivo collagen-induced platelet aggregation and aggregate formation on immobilized collagen under flow were impaired in whole blood of donors that had consumed Cannabis sativa.

Conclusions

Endocannabinoid receptor agonists reduce platelet activation and aggregate formation both in vitro and ex vivo after Cannabis sativa consumption. Further elucidation of this novel regulatory mechanism for platelet function may prove beneficial in the search for new antithrombotic therapies.

Association between a genetic variant of type-1 cannabinoid receptor and inflammatory neurodegeneration in multiple sclerosis

Genetic ablation of type-1 cannabinoid receptors (CB1Rs) exacerbates the neurodegenerative damage of experimental autoimmune encephalomyelitis, the rodent model of multiple sclerosis (MS). To address the role on CB1Rs in the pathophysiology of human MS, we first investigated the impact of AAT trinucleotide short tandem repeat polymorphism of CNR1 gene on CB1R cell expression, and secondly on the inflammatory neurodegeneration process responsible for irreversible disability in MS patients. We found that MS patients with long AAT repeats within the CNR1 gene (≥12 in both alleles) had more pronounced neuronal degeneration in response to inflammatory white matter damage both in the optic nerve and in the cortex. Optical Coherence Tomography (OCT), in fact, showed more severe alterations of the retinal nerve fiber layer (RNFL) thickness and of the macular volume (MV) after an episode of optic neuritis in MS patients carrying the long AAT genotype of CNR1. MS patients with long AAT repeats also had magnetic resonance imaging (MRI) evidence of increased gray matter damage in response to inflammatory lesions of the white matter, especially in areas with a major role in cognition. In parallel, visual abilities evaluated at the low contrast acuity test, and cognitive performances were negatively influenced by the long AAT CNR1 genotype in our sample of MS patients. Our results demonstrate the biological relevance of the (AAT)n CNR1 repeats in the inflammatory neurodegenerative damage of MS.

Selected topics of the 4th International Cooperative Study Group meeting on immune thrombocytopenia revisited

The Intercontinental Cooperative immune thrombocytopenia (ITP) Study Group (ICIS) held its 4th Expert Meeting in September 2012 in Montreux, Switzerland. The program reunited researchers and clinicians from all over the globe and was organized with lectures and seminars for real-time exchange of latest information. Platelets target victims of autoimmune disease on their own, participating under physiological conditions in the immune network; these small cells are more immunologically savvy than previously thought. Currently, researchers focus their attention on regulatory T and regulatory B cells, ie, cells that might have a decisive impact on how ITP spontaneously resolves or evolves into chronic disease. Diagnostic criteria and prognosis are increasingly benefiting from molecular biological tests, and therapy has evolved with the availability of biosimilar agents and recombinant hormones or blockers of their receptors.

The anandamide effect on NO/cGMP pathway in human platelets

In this study the effect of the endocannabinoid anandamide on platelet nitric oxide (NO)/cGMP pathway was investigated. Data report that anandamide in a dose-and time-dependent manner increased NO and cGMP levels and stimulated endothelial nitric oxide synthase (eNOS) activity. These parameters were significantly reduced by LY294002, selective inhibitor of PI3K and by MK2206, specific inhibitor of AKT. Moreover anandamide stimulated both eNOSser1177 and AKTser473 phosphorylation. Finally the anandamide effect on NO and cGMP levels, eNOS and AKT phosphorylation/activation were inhibited by SR141716, specific cannabinoid receptor 1 antagonist, supporting the involvement of anandamide binding to this receptor. Overall data of this report indicate that low concentrations of anandamide, through PI3K/AKT pathway activation, stimulates eNOS activity and increases NO levels in human platelets. In such way anandamide contributes to extend platelet survival.