The emerging role of fatty acid binding protein 7 (FABP7) in cancers

Fatty acid binding protein 7 (FABP7) is an intracellular protein involved in the uptake, transportation, metabolism, and storage of fatty acids (FAs). FABP7 is upregulated up to 20-fold in multiple cancers, usually correlated with poor prognosis. FABP7 silencing or pharmacological inhibition suggest FABP7 promotes cell growth, migration, invasion, colony and spheroid formation/increased size, lipid uptake, and lipid droplet formation. Xenograft studies show that suppression of FABP7 inhibits tumour formation and tumour growth, and improves host survival. The molecular mechanisms involve promotion of FA uptake, lipid droplets, signalling [focal adhesion kinase (FAK), proto-oncogene tyrosine-protein kinase Src (Src), mitogen-activated protein kinase kinase/p-extracellular signal-regulated kinase (MEK/ERK), and Wnt/β-catenin], hypoxia-inducible factor 1-alpha (Hif1α), vascular endothelial growth factor A/prolyl 4-hydroxylase subunit alpha-1 (VEGFA/P4HA1), snail family zinc finger 1 (Snail1), and twist-related protein 1 (Twist1). The oncogenic capacity of FABP7 makes it a promising pharmacological target for future cancer treatments.

Origins of Cannabis sativa in Ireland and the Concept of Celtic Hemp: An Interdisciplinary Review

Introduction: Ireland's agriculture has been shaped by Celts, Romano-British Christians, Norse-Vikings, Anglo-Normans, and subsequent migrants. Who introduced hemp (Cannabis sativa) to Hibernia? We addressed this question using historical linguistics, fossil pollen studies (FPSs), archaeological data, and written records. Methods: Data gathering utilized digital resources coupled with citation tracking. Linguistic methods separated cognates (words with shared etymological origins) from loanwords (borrowed from other languages). Cannabis pollen in FPSs was identified using the "ecological proxy" method. Archaeological reports were ranked on a "robustness" scale. Results: Words for "hemp" in Celtic languages are loanwords, not cognates. The Irish word cnáib is first attested in texts written 1060 and 1127-1134 CE. Old Breton coarcholion, corrected to coarch, is attested in a text from the 9th century. Pollen consistent with cultivated Cannabis appears in the Middle Ages, ca. 700 CE, at sites in the vicinity of monasteries. Archaeological finds (hemp seeds and fiber) date to later Norse-Viking and Anglo-Norman sites. Discussion: People of the Hallstatt Culture in Central Europe have long been considered speakers of the "Proto-Celtic" language. The lack of "hemp" cognates means a Proto-Celtic word cannot be reconstructed, which implies that Hallstatt people (with robust archaeological evidence of hemp) did not speak Proto-Celtic. Cnáib is absent in Old Irish glossaries, epics, and mythologies (600-900 CE). FPS data suggest that the onset of hemp cultivation correlated-chronologically and spatially-with the founding of Romano-British monasteries. Irish cnáib was likely borrowed from Clerical Latin canapis or canabus.

Discovery and Preclinical Evaluation of a Novel Inhibitor of FABP5, ART26.12, Effective in Oxaliplatin-Induced Peripheral Neuropathy

Oxaliplatin-induced peripheral neuropathy (OIPN) is a dose-limiting toxicity characterised by mechanical allodynia and thermal hyperalgesia, without any licensed medications. ART26.12 is a fatty acid-binding protein (FABP) 5 inhibitor with antinociceptive properties, characterised here for the prevention and treatment of OIPN. ART26.12 binds selectively to FABP5 compared to FABP3, FABP4, and FABP7, with minimal off-target liabilities, high oral bioavailability, and a NOAEL of 1,000 mg/kg/day in rats and dogs. In an established preclinical OIPN model, acute oral dosing (25-100 mg/kg) showed a cannabinoid receptor type 1 (CB1)-dependent anti-allodynic effect lasting up to 8 hours (persisting longer than plasma exposure to ART26.12). Antagonists of cannabinoid receptor type 2 (CB2), peroxisome proliferator-activated receptor alpha, and transient receptor potential cation channel subfamily V member 1 (TRPV1) may have also been implicated. Twice daily oral dosing (25 mg/kg bis in die (BID) for 7 days) showed anti-allodynic effects in an established OIPN model without the development of tolerance. In a prevention paradigm, coadministration of ART26.12 (10 and 25 mg/kg BID for 15 days) with oxaliplatin prevented thermal hyperalgesia, mitigated mechanical allodynia, and attenuated OXA-induced weight loss. Multi-scale analyses revealed widespread lipid modulation, particularly among N-acyl amino acids in the spinal cord, including potential analgesic mediators. Additionally, ART26.12 administration led to upregulation of ion channels in the periaqueductal grey, and broad translational upregulation within the plasma proteome. These results show promise that ART26.12 is a safe and well-tolerated candidate for the treatment and prevention of OIPN through lipid modulation. PERSPECTIVE: Inhibition of fatty acid-binding protein 5 (FABP5) is a novel target for reducing pain associated with chemotherapy. ART26.12 is a safe and well-tolerated small molecule FABP5 inhibitor effective at preventing and reducing pain induced with oxaliplatin through lipid modulation and activation of cannabinoid receptors.

The emerging role of fatty acid binding protein 5 (FABP5) in cancers

Fatty acid binding protein 5 (FABP5, or epidermal FABP) is an intracellular chaperone of fatty acid molecules that regulates lipid metabolism and cell growth. In patient-derived tumours, FABP5 expression is increased up to tenfold, often co-expressed with other cancer-related proteins. High tumoral FABP5 expression is associated with poor prognosis. FABP5 activates transcription factors (TFs) leading to increased expression of proteins involved in tumorigenesis. Genetic and pharmacological preclinical studies show that inhibiting FABP5 reduces protumoral markers, whereas elevation of FABP5 promotes tumour growth and spread. Thus, FABP5 might be a valid target for novel therapeutics. The evidence base is currently strongest for liver, prostate, breast, and brain cancers, and squamous cell carcinoma (SCC), which could represent relevant patient populations for any drug discovery programme. Teaser: This review presents the growing evidence that upregulated fatty acid binding protein 5 (FABP5) plays a role in the progression of multiple cancer types, and may represent a novel therapeutic target.

Endocannabinoid hydrolases differentially distribute in platelets and red blood cells and are differentially released by thrombin

BACKGROUND

Plasma levels of the major endocannabinoids 2-arachidonoylgycerol (2AG) and anandamide (N-arachidonoylethanolamine, AEA) have been identified to vary independently with particular pathological conditions. The levels of these endocannabinoids are tightly regulated by two hydrolytic enzymes, monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), respectively.

OBJECTIVES

In this study, we have quantified these enzyme activities in the major blood fractions.

PATIENTS/METHODS

In blood fractions from human volunteers, radiometric assays were used to quantify monoacylglycerol lipase and fatty acid amide hydrolase. Tagging with fluorophosphonate-rhodamine allowed quantification of platelet serine hydrolase activities.

RESULTS

Fatty acid amide hydrolase activity was highest in platelets, while MAGL activity was most abundant in erythrocytes. Sampling the blood of donors on two further occasions 15 days apart showed no significant change in platelet FAAH or erythrocyte MAGL activities. Activities were not different when comparing female donors with males. Storage of these blood fractions at - 80 °C was associated with a rapid loss in enzyme activities, which could largely by avoided by storage in liquid nitrogen. Incubation of platelets and erythrocytes in the presence of thrombin lead to release of measurable FAAH, but not MAGL, activity. Tagging of serine hydrolase activities with fluorophosphonate-rhodamine allowed confirmation of MAGL activity in platelet preparations, as well as multiple other enzymes.

CONCLUSIONS

These investigations suggest a potential role for FAAH in regulation of coagulation, while the role of MAGL in blood requires further investigation.

The Pharmacological Effects of Plant-Derived versus Synthetic Cannabidiol in Human Cell Lines

Introduction

Cannabidiol (CBD) can be isolated from Cannabis sativa L. or synthetically produced. The aim of this study was to compare the in vitro effects of purified natural and synthetic CBD to establish any pharmacological differences or superiority between sources.

Methods

Six purified samples of CBD were obtained, 4 of these were natural and 2 synthetic. The anticancer effects of CBD were assessed in a human ovarian cancer cell line (SKOV-3 cells). The neuroprotective effects of CBD were assessed in human pericytes in a model of stroke (oxygen glucose deprivation [OGD]). The ability of CBD to restore inflammation-induced intestinal permeability was assessed in differentiated human Caco-2 cells (a model of enterocytes).

Results

(1) In proliferating and confluent SKOV-3 cells, all CBD samples similarly reduced resazurin metabolism as a marker of cell viability in a concentration-dependent manner (p < 0.001). (2) In pericytes exposed to OGD, all CBD samples similarly reduced cellular damage (measured by lactate dehydrogenase) at 24 h by 31-48% and reduced inflammation (measured by IL-6 secretion) by 30-53%. Attenuation of IL-6 was inhibited by 5HT_1A receptor antagonism for all CBD sources. (3) In differentiated Caco-2 cells exposed to inflammation (TNFα and IFNγ, 10 ng/mL for 24 h), each CBD sample increased the speed of recovery of epithelial permeability compared to control (p < 0.05-0.001), which was inhibited by a CB₁ receptor antagonist.

Conclusion

Our results suggest that there is no pharmacological difference in vitro in the antiproliferative, anti-inflammatory, or permeability effects of purified natural versus synthetic CBD. The purity and reliability of CBD samples, as well as the ultimate pharmaceutical preparation, should all be considered above the starting source of CBD in the development of new CBD medicines.

Current controversies in medical cannabis: Recent developments in human clinical applications and potential therapeutics

Knowledge about the therapeutic potential of medical cannabis has greatly improved over the past decade, with an ever-increasing range of developments in human clinical applications. A growing body of scientific evidence supports the use of medical cannabis products for some therapeutic indications, whilst for others, the evidence base remains disputed. For this narrative review, we incorporate areas where the current evidence base is substantial, such as intractable childhood epilepsy and multiple sclerosis, as well as areas where the evidence is still controversial, such as PTSD and anxiety. We provide a high-level summary of current developments using findings from recent major reviews, as well as real world evidence (RWE), including global database registries and other patient reported outcomes (PROs). On the one hand, our strongest empirical data supports the use of cannabis-based medicinal products (CBMPs) for conditions with relatively small patient numbers. Yet on the other hand, the conditions, where the highest patient numbers present, often have debatable clinical evidence but good RWE, incorporating PROs of 1000s of patients. The discord between PROs and the respective strength of the evidence from randomised controlled trials (RCTs) highlights the urgent need for further research. The scientific literature examining the efficacy of medical cannabis for many conditions is still developing, whilst large numbers of patients globally have been successfully using medical cannabis to treat a broad range of conditions. We conclude on the importance of systematically developing RWE databases to supplement RCTs and to bridge the current evidence gaps.

Blood markers in remote ischaemic conditioning for acute ischaemic stroke: data from the REmote ischaemic Conditioning After Stroke Trial

BACKGROUND AND PURPOSE

Remote ischaemic per-conditioning (RIC) is neuroprotective in experimental ischaemic stroke. Several neurohumoral, vascular and inflammatory mediators are implicated. The effect of RIC on plasma biomarkers was assessed using clinical data from the REmote ischaemic Conditioning After Stroke Trial (RECAST-1).

METHODS

RECAST-1 was a pilot sham-controlled blinded trial in 26 patients with ischaemic stroke, randomized to receive four 5-min cycles of RIC within 24 h of ictus. Plasma taken pre-intervention, immediately post-intervention and on day 4 was analysed for nitric oxide (nitrate/nitrite) using chemiluminescence and all other biomarkers by multiplex analysis. Biomarkers were correlated with clinical outcome (day 90 National Institutes of Health Stroke Scale, modified Rankin Scale, Barthel index).

RESULTS

Remote ischaemic per-conditioning reduced serum amyloid protein (SAP) and tissue necrosis factor α (TNF-α) levels from pre- to post-intervention (n = 13, two-way ANOVA, p < 0.05). Overall (n = 26), increases in SAP pre- to post-intervention and pre-intervention to day 4 were moderately correlated with worse day 90 clinical outcomes. No consistent significant changes over time, or by treatment, or correlations with outcome were seen for other biomarkers.

CONCLUSIONS

Remote ischaemic per-conditioning reduced SAP and TNF-α levels from pre- to post-intervention. Increases in plasma levels of SAP were associated with worse clinical outcomes after ischaemic stroke. Larger studies assessing biomarkers and the safety and efficacy of RIC in acute ischaemic stroke are warranted to further understand these relationships.

A Multicriteria Decision Analysis Comparing Pharmacotherapy for Chronic Neuropathic Pain, Including Cannabinoids and Cannabis-Based Medical Products

Background:

Pharmacological management of chronic neuropathic pain (CNP) still represents a major clinical challenge. Collective harnessing of both the scientific evidence base and clinical experience (of clinicians and patients) can play a key role in informing treatment pathways and contribute to the debate on specific treatments (e.g., cannabinoids). A group of expert clinicians (pain specialists and psychiatrists), scientists, and patient representatives convened to assess the relative benefit–safety balance of 12 pharmacological treatments, including orally administered cannabinoids/cannabis-based medicinal products, for the treatment of CNP in adults.

Methods:

A decision conference provided the process of creating a multicriteria decision analysis (MCDA) model, in which the group collectively scored the drugs on 17 effect criteria relevant to benefits and safety and then weighted the criteria for their clinical relevance.

Findings:

Cannabis-based medicinal products consisting of tetrahydrocannabinol/cannabidiol (THC/CBD), in a 1:1 ratio, achieved the highest overall score, 79 (out of 100), followed by CBD dominant at 75, then THC dominant at 72. Duloxetine and the gabapentinoids scored in the 60s, amitriptyline, tramadol, and ibuprofen in the 50s, methadone and oxycodone in the 40s, and morphine and fentanyl in the 30s. Sensitivity analyses showed that even if the pain reduction and quality-of-life scores for THC/CBD and THC are halved, their benefit–safety balances remain better than those of the noncannabinoid drugs.

Interpretation:

The benefit–safety profiles for cannabinoids were higher than for other commonly used medications for CNP largely because they contribute more to quality of life and have a more favorable side effect profile. The results also reflect the shortcomings of alternative pharmacological treatments with respect to safety and mitigation of neuropathic pain symptoms. Further high-quality clinical trials and systematic comprehensive capture of clinical experience with cannabinoids is warranted. These results demonstrate once again the complexity and multimodal mechanisms underlying the clinical experience and impact of chronic pain.

Protective Effects of Cannabidivarin and Cannabigerol on Cells of the Blood-Brain Barrier Under Ischemic Conditions

Background and Objectives: Preclinical studies have shown cannabidiol is protective in models of ischemic stroke. Based on results from our recent systematic review, we investigated the effects of two promising neuroprotective phytocannabinoids, cannabigerol (CBG) and cannabidivarin (CBDV), on cells of the blood-brain barrier (BBB), namely human brain microvascular endothelial cells (HBMECs), pericytes, and astrocytes. Experimental Approach: Cultures were subjected to oxygen-glucose deprivation (OGD) protocol to model ischemic stroke and cell culture medium was assessed for cytokines and adhesion molecules post-OGD. Astrocyte cell lysates were also analyzed for DNA damage markers. Antagonist studies were conducted where appropriate to study receptor mechanisms. Results: In astrocytes CBG and CBDV attenuated levels of interleukin-6 (IL-6) and lactate dehydrogenase (LDH), whereas CBDV (10 nM-10 μM) also decreased vascular endothelial growth factor (VEGF) secretion. CBDV (300 nM-10 μM) attenuated levels of monocyte chemoattractant protein (MCP)-1 in HBMECs. In astrocytes, CBG decreased levels of DNA damage proteins, including p53, whereas CBDV increased levels of DNA damage markers. Antagonists for CB₁, CB₂, PPAR-γ, PPAR-α, 5-HT1_A, and TRPV1 had no effect on CBG (3 μM) or CBDV (1 μM)-mediated decreases in LDH in astrocytes. GPR55 and GPR18 were partially implicated in the effects of CBDV, but no molecular target was identified for CBG. Conclusions: We show that CBG and CBDV were protective against OG mediated injury in three different cells that constitute the BBB, modulating different hallmarks of ischemic stroke pathophysiology. These data enhance our understanding of the protective effects of CBG and CBDV and warrant further investigation into these compounds in ischemic stroke. Future studies should identify other possible neuroprotective effects of CBG and CBDV and their corresponding mechanisms of action.

Could Cannabidiol Be a Treatment for Coronavirus Disease-19-Related Anxiety Disorders?

Coronavirus disease-19 (COVID-19)-related anxiety and post-traumatic stress symptoms (PTSS) or post-traumatic stress disorder (PTSD) are likely to be a significant long-term issue emerging from the current pandemic. We hypothesize that cannabidiol (CBD), a chemical isolated from Cannabis sativa with reported anxiolytic properties, could be a therapeutic option for the treatment of COVID-19-related anxiety disorders. In the global over-the-counter CBD market, anxiety, stress, depression, and sleep disorders are consistently the top reasons people use CBD. In small randomized controlled clinical trials, CBD (300-800 mg) reduces anxiety in healthy volunteers, patients with social anxiety disorder, those at clinical high risk of psychosis, in patients with Parkinson's disease, and in individuals with heroin use disorder. Observational studies and case reports support these findings, extending to patients with anxiety and sleep disorders, Crohn's disease, depression, and in PTSD. Larger ongoing trials in this area continue to add to this evidence base with relevant patient cohorts, sample sizes, and clinical end-points. Pre-clinical studies reveal the molecular targets of CBD in these indications as the cannabinoid receptor type 1 and cannabinoid receptor type 2 (mainly in fear memory processing), serotonin 1A receptor (mainly in anxiolysis) and peroxisome proliferator-activated receptor gamma (mainly in the underpinning anti-inflammatory/antioxidant effects). Observational and pre-clinical data also support CBD's therapeutic value in improving sleep (increased sleep duration/quality and reduction in nightmares) and depression, which are often comorbid with anxiety. Together these features of CBD make it an attractive novel therapeutic option in COVID-related PTSS that merits investigation and testing through appropriately designed randomized controlled trials.

A meta-analysis of remote ischaemic conditioning in experimental stroke

Remote ischaemic conditioning (RIC) is achieved by repeated transient ischaemia of a distant organ/limb and is neuroprotective in experimental ischaemic stroke. However, the optimal time and methods of administration are unclear. Systematic review identified relevant preclinical studies; two authors independently extracted data on infarct volume, neurological deficit, RIC method (administration time, site, cycle number, length of limb occlusion (dose)), species and quality. Data were analysed using random effects models; results expressed as standardised mean difference (SMD). In 57 publications incorporating 99 experiments (1406 rats, 101 mice, 14 monkeys), RIC reduced lesion volume in transient (SMD -2.0; 95% CI -2.38, -1.61; p < 0.00001) and permanent (SMD -1.54; 95% CI -2.38, -1.61; p < 0.00001) focal models of ischaemia and improved neurological deficit (SMD -1.63; 95% CI -1.97, -1.29, p < 0.00001). In meta-regression, cycle length and number, dose and limb number did not interact with infarct volume, although country and physiological monitoring during anaesthesia did. In all studies, RIC was ineffective if the dose was <10 or ≥50 min. Median study quality was 7 (range 4-9/10); Egger's test suggested publication bias (p < 0.001). RIC is most effective in experimental stroke using a dose between 10 and 45 min. Further studies using repeated dosing in animals with co-morbidities are warranted.

A systematic review of minor phytocannabinoids with promising neuroprotective potential

Embase and PubMed were systematically searched for articles addressing the neuroprotective properties of phytocannabinoids, apart from cannabidiol and Δ9 -tetrahydrocannabinol, including Δ9 -tetrahydrocannabinolic acid, Δ9 -tetrahydrocannabivarin, cannabidiolic acid, cannabidivarin, cannabichromene, cannabichromenic acid, cannabichromevarin, cannabigerol, cannabigerolic acid, cannabigerivarin, cannabigerovarinic acid, cannabichromevarinic acid, cannabidivarinic acid, and cannabinol. Out of 2,341 studies, 31 articles met inclusion criteria. Cannabigerol (range 5 to 20 mg·kg-1 ) and cannabidivarin (range 0.2 to 400 mg·kg-1 ) displayed efficacy in models of Huntington's disease and epilepsy. Cannabichromene (10-75 mg·kg-1 ), Δ9 -tetrahydrocannabinolic acid (20 mg·kg-1 ), and tetrahydrocannabivarin (range 0.025-2.5 mg·kg-1 ) showed promise in models of seizure and hypomobility, Huntington's and Parkinson's disease. Limited mechanistic data showed cannabigerol, its derivatives VCE.003 and VCE.003.2, and Δ9 -tetrahydrocannabinolic acid mediated some of their effects through PPAR-γ, but no other receptors were probed. Further studies with these phytocannabinoids, and their combinations, are warranted across a range of neurodegenerative disorders.

Gestational poly(I:C) attenuates, not exacerbates, the behavioral, cytokine and mTOR changes caused by isolation rearing in a rat 'dual-hit' model for neurodevelopmental disorders

Many psychiatric illnesses have a multifactorial etiology involving genetic and environmental risk factors that trigger persistent neurodevelopmental impairments. Several risk factors have been individually replicated in rodents, to understand disease mechanisms and evaluate novel treatments, particularly for poorly-managed negative and cognitive symptoms. However, the complex interplay between various factors remains unclear. Rodent dual-hit neurodevelopmental models offer vital opportunities to examine this and explore new strategies for early therapeutic intervention. This study combined gestational administration of polyinosinic:polycytidylic acid (poly(I:C); PIC, to mimic viral infection during pregnancy) with post-weaning isolation of resulting offspring (to mirror adolescent social adversity). After in vitro and in vivo studies required for laboratory-specific PIC characterization and optimization, we administered 10 mg/kg i.p. PIC potassium salt to time-mated Lister hooded dams on gestational day 15. This induced transient hypothermia, sickness behavior and weight loss in the dams, and led to locomotor hyperactivity, elevated striatal cytokine levels, and increased frontal cortical JNK phosphorylation in the offspring at adulthood. Remarkably, instead of exacerbating the well-characterized isolation syndrome, gestational PIC exposure actually protected against a spectrum of isolation-induced behavioral and brain regional changes. Thus isolation reared rats exhibited locomotor hyperactivity, impaired associative memory and reversal learning, elevated hippocampal and frontal cortical cytokine levels, and increased mammalian target of rapamycin (mTOR) activation in the frontal cortex - which were not evident in isolates previously exposed to gestational PIC. Brains from adolescent littermates suggest little contribution of cytokines, mTOR or JNK to early development of the isolation syndrome, or resilience conferred by PIC. But notably hippocampal oxytocin, which can protect against stress, was higher in adolescent PIC-exposed isolates so might contribute to a more favorable outcome. These findings have implications for identifying individuals at risk for disorders like schizophrenia who may benefit from early therapeutic intervention, and justify preclinical assessment of whether adolescent oxytocin manipulations can modulate disease onset or progression.

Effect of Sodium-Glucose Cotransporter-2 Inhibitors on Endothelial Function: A Systematic Review of Preclinical Studies

INTRODUCTION

While the beneficial effects of sodium-glucose cotransporter-2 (SGLT-2) inhibitors on cardiovascular and renal outcomes are recognized, their direct effects on endothelial function remain unclear. We, therefore, undertook a systematic review to evaluate the current literature in this area.

METHODS

Electronic databases (PubMed, EMBASE, and Medline) were systematically searched using PRISMA guidelines for studies involving the in vitro, in vivo, or ex vivo administration of SGLT-2 inhibitors to animals, vascular tissue, or vascular endothelial cells.

RESULTS

Of 144 retrieved publications, 24 experimental studies met the inclusion criteria. Reporting of possible sources of bias were poor, making the overall risk of bias difficult to assess. Within the 24 studies, the SGLT-2 inhibitors canagliflozin, ipragliflozin, empagliflozin, dapagliflozin, tofogliflozin, and luseogliflozin were assessed as interventions. Animal model studies (n = 17) demonstrated that all SGLT-2 inhibitors prevented endothelial dysfunction and enhanced endothelium-dependent vasorelaxation in diabetic and non-diabetic models. In vitro studies (n = 9) using human endothelial cells indicated a direct anti-inflammatory effect of dapagliflozin (1-100 nM) and canagliflozin, (10 µM), while empagliflozin (1 and 10 µM) improved viability of hyperglycemic cells. Potential mechanisms of action of the SGLT-2 inhibitors include a reduction in oxidative stress, modulation of adhesion molecules and reductions in pro-inflammatory cytokines.

CONCLUSIONS

Preclinical studies indicate that SGLT-2 inhibitors attenuate vascular dysfunction in preclinical models via a combination of mechanisms that appear to act independently of glucose-lowering benefits.

The effects of acute and sustained cannabidiol dosing for seven days on the haemodynamics in healthy men: A randomised controlled trial

BACKGROUND

In vivo studies show that cannabidiol (CBD) acutely reduces blood pressure (BP) in men. The aim of this study was to assess the effects of repeated CBD dosing on haemodynamics.

METHODS

Twenty-six healthy males were given CBD (600 mg) or placebo orally for seven days in a randomised, placebo-controlled, double-blind, parallel study (n = 13/group). Cardiovascular parameters were assessed at rest and in response to isometric exercise after acute and repeated dosing using Finometer®, Vicorder® and Duplex ultrasound.

RESULTS

Compared to placebo, CBD significantly reduced resting mean arterial pressure (P = .04, two-way ANOVA, mean difference (MD) -2 mmHg, 95% CI -3.6 to -0.3) after acute dosing, but not after repeated dosing. In response to stress, volunteers who had taken CBD had lower systolic BP after acute (P = .001, two-way ANOVA, MD -6 mmHg, 95% CI -10 to -1) and repeated (P = .02, two-way ANOVA, MD -5.7 mmHg, 95% CI -10 to -1) dosing. Seven days of CBD increased internal carotid artery diameter (MD +0.55 mm, P = .01). Within the CBD group, repeated dosing reduced arterial stiffness by day 7 (pulse wave velocity; MD -0.44 m/s, P = .05) and improved endothelial function (flow mediation dilatation, MD +3.5%, P = .02, n = 6 per group), compared to day 1.

CONCLUSION

CBD reduces BP at rest after a single dose but the effect is lost after seven days of treatment (tolerance); however, BP reduction during stress persists. The reduction in arterial stiffness and improvements in endothelial function after repeated CBD dosing are findings that warrant further investigation in populations with vascular diseases.

An Investigation Into the Role of Osteocalcin in Human Arterial Smooth Muscle Cell Calcification

Osteocalcin (OCN) is a bone-derived protein that is detected within human calcified vascular tissue. Calcification is particularly prevalent in chronic kidney disease (CKD) patients but the role of OCN in calcification, whether active or passive, has not been elucidated. Part 1: The relationship between OCN, CKD and vascular calcification was assessed in CKD patients (n = 28) and age-matched controls (n = 19). Part 2: in vitro, we analyzed whether addition of uncarboxylated osteocalcin (ucOCN) influenced the rate or extent of vascular smooth muscle cell (VSMC) calcification. Human aortic VSMCs were cultured in control media or mineralisation inducing media (MM) containing increased phosphate with or without ucOCN (10 or 30 ng/mL) for up to 21 days. Markers of osteogenic differentiation and calcification were determined [alkaline phosphatase (ALP) activity, total intracellular OCN, Runx2 expression, α-SMA expression, alizarin red calcium staining, and calcium quantification]. Part 1 results: In our human population, calcification was present (mean age 76 years), but no differences were detected between CKD patients and controls. Plasma total OCN was increased in CKD patients compared to controls (14 vs. 9 ng/mL; p < 0.05) and correlated to estimated glomerular filtration rate (p < 0.05), however no relationship was detected between total OCN and calcification. Part 2 results: in vitro, ALP activity, α-SMA expression and calcium concentrations were significantly increased in MM treated VSMCs at day 21, but no effect of ucOCN was observed. Cells treated with control media+ucOCN for 21 days did not show increases in ALP activity nor calcification. In summary, although plasma total OCN was increased in CKD patients, this study did not find a relationship between OCN and calcification in CKD and non-CKD patients, and found no in vitro evidence of an active role of ucOCN in vascular calcification as assessed over 21 days. ucOCN appears not to be a mediator of vascular calcification, but further investigation is warranted.

Remote Ischemic Conditioning After Stroke Trial 2: A Phase IIb Randomized Controlled Trial in Hyperacute Stroke

Background Repeated episodes of limb ischemia and reperfusion (remote ischemic conditioning [RIC]) may protect the brain from ischemic reperfusion injury. Methods and Results We performed a phase IIb blinded dose-escalation sham-controlled trial in patients with hyperacute stroke, randomized 1:1 to receive RIC (four 5-minute cycles) or sham to the nonparetic upper limb, in 3 blocks of increasing dose, starting within 6 hours of ictus. The primary outcome was trial feasibility (recruitment, attrition). Secondary outcomes included adherence, tolerability, safety (serious adverse events), plasma biomarkers at days 1 and 4 (S100-ß protein, matrix metalloproteinase-9, and neuron-specific enolase), and functional outcome. Sixty participants were recruited from 2 centers (3 per month) with no loss to follow-up: time to randomization 4 hours 5 minutes (SD 72 minutes), age 72 years (12), men 60%, blood pressure 154/80 mm Hg (25/12), National Institutes of Health Stroke Scale 8.4 (6.9), and 55% thrombolyzed. RIC was well tolerated with adherence not differing between RIC and sham, falling in both groups on day 3 (P=0.001, repeated measures ANOVA) because of discharge or transfer. S100ß increased in the sham group (mean rise 111 pg/mL [302], P=0.041, repeated measures ANCOVA) but not the RIC group. There were no differences in matrix metalloproteinase-9, neuron-specific enolase, number with serious adverse events (RIC 10 versus sham 10, P=0.81), deaths (2 versus 4, P=0.36), or modified Rankin Scale score (2 [interquartile range 1-4], 2 [interquartile range, 1-3]; P=0.85). Conclusions RIC in hyperacute stroke is feasible when given twice daily for 2 days and appears safe in a small population with hyperacute stroke. A larger phase III trial is warranted. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02779712.

Endocannabinoids and endocannabinoid-like compounds modulate hypoxia-induced permeability in CaCo-2 cells via CB1, TRPV1, and PPARα

BACKGROUND AND PURPOSE

We have previously reported that endocannabinoids modulate permeability in Caco-2 cells under inflammatory conditions and hypothesised in the present study that endocannabinoids could also modulate permeability in ischemia/reperfusion.

EXPERIMENTAL APPROACH

Caco-2 cells were grown on cell culture inserts to confluence. Trans-epithelial electrical resistance (TEER) was used to measure permeability. To generate hypoxia (0% O2), a GasPak™ EZ anaerobe pouch system was used. Endocannabinoids were applied to the apical or basolateral membrane in the presence or absence of receptor antagonists.

KEY RESULTS

Complete hypoxia decreased TEER (increased permeability) by ~35% after 4 h (recoverable) and ~50% after 6 h (non-recoverable). When applied either pre- or post-hypoxia, apical application of N-arachidonoyl-dopamine (NADA, via TRPV1), oleamide (OA, via TRPV1) and oleoylethanolamine (OEA, via TRPV1) inhibited the increase in permeability. Apical administration of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) worsened the permeability effect of hypoxia (both via CB1). Basolateral application of NADA (via TRPV1), OA (via CB1 and TRPV1), noladin ether (NE, via PPARα), and palmitoylethanolamine (PEA, via PPARα) restored permeability after 4 h hypoxia, whereas OEA increased permeability (via PPARα). After 6 h hypoxia, where permeability does not recover, only basolateral application PEA sustainably decreased permeability, and NE decreased permeability.

CONCLUSIONS AND IMPLICATIONS

A variety of endocannabinoids and endocannabinoid-like compounds modulate Caco-2 permeability in hypoxia/reoxygenation, which involves multiple targets, depending on whether the compounds are applied to the basolateral or apical membrane. CB1 antagonism and TRPV1 or PPARα agonism may represent novel therapeutic targets against several intestinal disorders associated with increased permeability.

Osteocalcin does not influence acute or chronic inflammation in human vascular cells

Some human observational studies have suggested an anti‐inflammatory role of osteocalcin (OCN). An inflammatory protocol using interferon‐γ and tumor necrosis factor‐α (10 ng/ml) was employed to examine the acute (24 hr) and chronic (144 hr) effects of uncarboxylated OCN (ucOCN) in commercial, primary, subcultured human aortic endothelial cells (HAEC), and human smooth muscle cells (HASMCs). The inflammatory protocol increased phosphorylation of intracellular signaling proteins (CREB, JNK, p38, ERK, AKT, STAT3, STAT5) and increased secretion of adhesion markers (vascular cell adhesion molecule‐1, intracellular adhesion molecule‐1, monocyte chemoattractant protein‐1) and proinflammatory cytokines (interleukin‐6 [IL‐6], IL‐8). After acute inflammation, there were no additive or reductive effects of ucOCN in either cell type. Following chronic inflammation, ucOCN did not affect cell responses, nor did it appear to have any pro‐ or anti‐inflammatory effects when administered acutely or chronically on its own in either cell type. Additionally, ucOCN did not affect lipopolysaccharide (LPS)‐induced acute inflammation in HAECs or HASMCs. The findings of this study do not support a causal role for OCN within the models of vascular inflammation chosen. Further confirmatory studies are warranted.

Osteokines and the vasculature: a review of the in vitro effects of osteocalcin, fibroblast growth factor-23 and lipocalin-2

Bone-derived factors that demonstrate extra-skeletal functions, also termed osteokines, are fast becoming a highly interesting and focused area of cross-disciplinary endocrine research. Osteocalcin (OCN), fibroblast growth factor-23 (FGF23) and lipocalin-2 (LCN-2), produced in bone, comprise an important endocrine system that is finely tuned with other organs to ensure homeostatic balance and health. This review aims to evaluate in vitro evidence of the direct involvement of these proteins in vascular cells and whether any causal roles in cardiovascular disease or inflammation can be supported. PubMed, Medline, Embase and Google Scholar were searched for relevant research articles investigating the exogenous addition of OCN, FGF23 or LCN-2 to vascular smooth muscle or endothelial cells. Overall, these osteokines are directly vasoactive across a range of human and animal vascular cells. Both OCN and FGF23 have anti-apoptotic properties and increase eNOS phosphorylation and nitric oxide production through Akt signalling in human endothelial cells. OCN improves intracellular insulin signalling and demonstrates protective effects against endoplasmic reticulum stress in murine and human endothelial cells. OCN may be involved in calcification but further research is warranted, while there is no evidence for a pro-calcific effect of FGF23 in vitro. FGF23 and LCN-2 increase proliferation in some cell types and increase and decrease reactive oxygen species generation, respectively. LCN-2 also has anti-apoptotic effects but may increase endoplasmic reticulum stress as well as have pro-inflammatory and pro-angiogenic properties in human vascular endothelial and smooth muscle cells. There is no strong evidence to support a pathological role of OCN or FGF23 in the vasculature based on these findings. In contrast, they may in fact support normal endothelial functioning, vascular homeostasis and vasodilation. No studies examined whether OCN or FGF23 may have a role in vascular inflammation. Limited studies with LCN-2 indicate a pro-inflammatory and possible pathological role in the vasculature but further mechanistic data is required. Overall, these osteokines pose intriguing functions which should be investigated comprehensively to assess their relevance to cardiovascular disease and health in humans.

A Novel Transwell Blood Brain Barrier Model Using Primary Human Cells

Structural alterations and breakdown of the blood brain barrier (BBB) is often a primary or secondary consequence of disease, resulting in brain oedema and the transport of unwanted substances into the brain. It is critical that effective in vitro models are developed to model the in vivo environment to aid in clinically relevant research, especially regarding drug screening and permeability studies. Our novel model uses only primary human cells and includes four of the key cells of the BBB: astrocytes, pericytes, brain microvascular endothelial cells (HBMEC) and neurons. We show that using a larger membrane pore size (3.0 μM) there is an improved connection between the endothelial cells, astrocytes and pericytes. Compared to a two and three cell model, we show that when neurons are added to HBMECs, astrocytes and pericytes, BBB integrity was more sensitive to oxygen-glucose deprivation evidenced by increased permeability and markers of cell damage. Our data also show that a four cell model responds faster to the barrier tightening effects of glucocorticoid dexamethasone, when compared to a two cell and three cell model. These data highlight the important role that neurons play in response to ischaemia, particularly how they contribute to BBB maintenance and breakdown. We consider that this model is more representative of the interactions at the neurovascular unit than other transwell models and is a useful method to study BBB physiology.

Palmitoylethanolamide and Cannabidiol Prevent Inflammation-induced Hyperpermeability of the Human Gut In Vitro and In Vivo-A Randomized, Placebo-controlled, Double-blind Controlled Trial

BACKGROUND AND AIMS

We aimed to examine, for the first time, the effect of cannabidiol (CBD) and palmitoylethanolamide (PEA) on the permeability of the human gastrointestinal tract in vitro, ex vivo, and in vivo.

METHODS

Flux measurements of fluorescein-labeled dextrans 10 (FD10) and fluorescein-labeled dextrans 4 (FD4) dextran across Caco-2 cultures treated for 24 hours with interferon gamma (IFNγ) and tumour necrosis factor alpha (TNFα) (10 ng·mL-1) were measured, with or without the presence of CBD and PEA. Mechanisms were investigated using cannabinoid receptor 1 (CB1), cannabinoid receptor 2 (CB2), transient receptor potential vanilloid 1 (TRPV1), and proliferator activated receptors (PPAR) antagonists and protein kinase A (PKA), nitric oxide synthase, phosphoinositide 3-kinases, extracellular signal-regulated kinases (MEK/ERK), adenylyl cyclase, and protein kinase C (PKC) inhibitors. Human colonic mucosal samples collected from bowel resections were treated as previously stated. The receptors TRPV1, PPARα, PPARδ, PPARγ, CB1, CB2, G-coupled protein receptor 55 (GPR55), G-coupled protein receptor 119 (GPR119), and claudins-1, -2, -3, -4, -5, -7, and -8 mRNA were measured using multiplex. Aquaporin 3 and 4 were measured using enzyme-linked immunosorbent assay (ELISA). A randomized, double-blind, controlled-trial assessed the effect of PEA or CBD on the absorption of lactulose and mannitol in humans taking 600 mg of aspirin. Urinary concentrations of these sugars were measured using liquid chromatography mass spectrometry.

RESULTS

In vitro, PEA, and CBD decreased the inflammation-induced flux of dextrans (P < 0.0001), sensitive to PPARα and CB1 antagonism, respectively. Both PEA and CBD were prevented by PKA, MEK/ERK, and adenylyl cyclase inhibition (P < 0.001). In human mucosa, inflammation decreased claudin-5 mRNA, which was prevented by CBD (P < 0.05). Palmitoylethanolamide and cannabidiol prevented an inflammation-induced fall in TRPV1 and increase in PPARα transcription (P < 0.0001). In vivo, aspirin caused an increase in the absorption of lactulose and mannitol, which were reduced by PEA or CBD (P < 0.001).

CONCLUSION

Cannabidiol and palmitoylethanolamide reduce permeability in the human colon. These findings have implications in disorders associated with increased gut permeability, such as inflammatory bowel disease.

Genetic polymorphisms of the endocannabinoid system in obesity and diabetes

The endocannabinoid system (ECS) is involved in many physiological processes including fertility, pain and energy regulation. The aim of this systematic review was to examine the contribution of single nucleotide polymorphisms (SNPs) of the ECS to adiposity and glucose metabolism. Database searches identified 734 articles, of which 65 were included; these covered 70 SNPs in genes coding for cannabinoid receptors 1 and 2 (CB₁ , CB₂ ), fatty acid amide hydrolase (FAAH) and N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD). No studies included SNPs relating to monoacylglycerol lipase or diacylglycerol lipase. The CB₁ receptor SNP rs1049353 showed 17 associations with lower body mass index (BMI) and fat mass (five studies). It also showed three associations with lower insulin levels (one study). Conversely, the CB₁ receptor SNP rs806368 was associated with increased BMI and waist circumference (two studies). The FAAH SNP rs324420 was associated with increased obesity (three studies). A haplotype of NAPE-PLD was associated with decreased BMI (one study). A total of 60 SNPs showed no association with any measured outcome. This review suggests a complex but important role of ECS SNPs in energy and glucose metabolism.

A Systematic Review on the Pharmacokinetics of Cannabidiol in Humans

Background: Cannabidiol is being pursued as a therapeutic treatment for multiple conditions, usually by oral delivery. Animal studies suggest oral bioavailability is low, but literature in humans is not sufficient. The aim of this review was to collate published data in this area.

Methods: A systematic search of PubMed and EMBASE (including MEDLINE) was conducted to retrieve all articles reporting pharmacokinetic data of CBD in humans.

Results: Of 792 articles retireved, 24 included pharmacokinetic parameters in humans. The half-life of cannabidiol was reported between 1.4 and 10.9 h after oromucosal spray, 2–5 days after chronic oral administration, 24 h after i.v., and 31 h after smoking. Bioavailability following smoking was 31% however no other studies attempted to report the absolute bioavailability of CBD following other routes in humans, despite i.v formulations being available. The area-under-the-curve and C_max increase in dose-dependent manners and are reached quicker following smoking/inhalation compared to oral/oromucosal routes. C_max is increased during fed states and in lipid formulations. T_max is reached between 0 and 4 h.

Conclusions: This review highlights the paucity in data and some discrepancy in the pharmacokinetics of cannabidiol, despite its widespread use in humans. Analysis and understanding of properties such as bioavailability and half-life is critical to future therapeutic success, and robust data from a variety of formulations is required.

An Analysis of Endocannabinoid Concentrations and Mood Following Singing and Exercise in Healthy Volunteers

The euphoric feeling described after running is, at least in part, due to increased circulating endocannabinoids (eCBs). eCBs are lipid signaling molecules involved in reward, appetite, mood, memory and neuroprotection. The aim of this study was to investigate whether activities other than running can increase circulating eCBs. Nine healthy female volunteers (mean 61 years) were recruited from a local choir. Circulating eCBs, haemodynamics, mood and hunger ratings were measured before and immediately after 30 min of dance, reading, singing or cycling in a fasted state. Singing increased plasma levels of anandamide (AEA) by 42% (P < 0.05), palmitoylethanolamine (PEA) by 53% (P < 0.01) and oleoylethanolamine (OEA) by 34% (P < 0.05) and improved positive mood and emotions (P < 0.01), without affecting hunger scores. Dancing did not affect eCB levels or hunger ratings, but decreased negative mood and emotions (P < 0.01). Cycling increased OEA levels by 26% (P < 0.05) and tended to decrease how hungry volunteers felt, without affecting mood. Reading increased OEA levels by 28% (P < 0.01) and increased the desire to eat. Plasma AEA levels were positively correlated with how full participants felt (P < 0.05). Plasma OEA levels were positively correlated with positive mood and emotions (P < 0.01). All three ethanolamines were positively correlated with heart rate (HR; P < 0.0001). These data suggest that activities other than running can increase plasma eCBs associated with changes in mood or appetite. Increases in eCBs may underlie the rewarding and pleasurable effects of singing and exercise and ultimately some of the long-term beneficial effects on mental health, cognition and memory.

The Use of Cannabinoids in Colitis: A Systematic Review and Meta-Analysis

BACKGROUND

Clinical trials investigating the use of cannabinoid drugs for the treatment of intestinal inflammation are anticipated secondary to preclinical literature demonstrating efficacy in reducing inflammation.

METHODS

We systematically reviewed publications on the benefit of drugs targeting the endo-cannabinoid system in intestinal inflammation. We collated studies examining outcomes for meta-analysis from EMBASE, MEDLINE and Pubmed until March 2017. Quality was assessed according to mSTAIR and SRYCLE score.

RESULTS

From 2008 papers, 51 publications examining the effect of cannabinoid compounds on murine colitis and 2 clinical studies were identified. Twenty-four compounds were assessed across 71 endpoints. Cannabidiol, a phytocannabinoid, was the most investigated drug. Macroscopic colitis severity (disease activity index [DAI]) and myeloperoxidase activity (MPO) were assessed throughout publications and were meta-analyzed using random effects models. Cannabinoids reduced DAI in comparison with the vehicle (standard mean difference [SMD] -1.36; 95% CI, -1.62 to-1.09; I2 = 61%). FAAH inhibitor URB597 had the largest effect size (SMD -4.43; 95% CI, -6.32 to -2.55), followed by the synthetic drug AM1241 (SMD -3.11; 95% CI, -5.01 to -1.22) and the endocannabinoid anandamide (SMD -3.03; 95% CI, -4.89 to -1.17; I2 not assessed). Cannabinoids reduced MPO in rodents compared to the vehicle; SMD -1.26; 95% CI, -1.54 to -0.97; I2 = 48.1%. Cannabigerol had the largest effect size (SMD -6.20; 95% CI, -9.90 to -2.50), followed by the synthetic CB1 agonist ACEA (SMD -3.15; 95% CI, -4.75 to -1.55) and synthetic CB1/2 agonist WIN55,212-2 (SMD -1.74; 95% CI, -2.81 to -0.67; I2 = 57%). We found no evidence of reporting bias. No significant difference was found between the prophylactic and therapeutic use of cannabinoid drugs.

CONCLUSIONS

There is abundant preclinical literature demonstrating the anti-inflammatory effects of cannabinoid drugs in inflammation of the gut. Larger randomised controlled-trials are warranted.

A single dose of cannabidiol reduces blood pressure in healthy volunteers in a randomized crossover study

BACKGROUND

Cannabidiol (CBD) is a nonpsychoactive phytocannabinoid used in multiple sclerosis and intractable epilepsies. Preclinical studies show CBD has numerous cardiovascular benefits, including a reduced blood pressure (BP) response to stress. The aim of this study was to investigate if CBD reduces BP in humans.

METHODS

Nine healthy male volunteers were given 600 mg of CBD or placebo in a randomized, placebo-controlled, double-blind, crossover study. Cardiovascular parameters were monitored using a finometer and laser Doppler.

RESULTS

CBD reduced resting systolic BP (-6 mmHg; P < 0.05) and stroke volume (-8 ml; P < 0.05), with increased heart rate (HR) and maintained cardiac output. Subjects who had taken CBD had lower BP (-5 mmHg; P < 0.05, especially before and after stress), increased HR (+10 bpm; P < 0.01), decreased stroke volume (-13 ml; P < 0.01), and a blunted forearm skin blood flow response to isometric exercise. In response to cold stress, subjects who had taken CBD had blunted BP (-6 mmHg; P < 0.01) and increased HR (+7 bpm; P < 0.05), with lower total peripheral resistance.

CONCLUSIONS

This data shows that acute administration of CBD reduces resting BP and the BP increase to stress in humans, associated with increased HR. These hemodynamic changes should be considered for people taking CBD. Further research is required to establish whether CBD has a role in the treatment of cardiovascular disorders.

In Vivo Cannabidiol Treatment Improves Endothelium-Dependent Vasorelaxation in Mesenteric Arteries of Zucker Diabetic Fatty Rats

Background and purpose: We have shown that in vitro treatment with cannabidiol (CBD, 2 h) enhances endothelial function in arteries from Zucker diabetic fatty (ZDF) rats, partly due to a cyclooxygenase (COX)-mediated mechanism. The aim of the present study was to determine whether treatment with CBD in vivo would also enhance endothelial function.

Experimental approach: Male ZDF rats, or ZDF Lean rats, were treated for 7 days (daily i.p. injection) with either 10mg/kg CBD or vehicle (n = 6 per group). Sections of mesenteric resistance arteries, femoral arteries and thoracic aortae were mounted on a wire myograph, and cumulative concentration-response curves to endothelium-dependent (acetylcholine, ACh, 1 nM–100 μM) or endothelium-independent (sodium nitroprusside, SNP, 1 nM–100 μM) agents were constructed. Multiplex analysis was used to measure serum metabolic and cardiovascular biomarkers.

Key results: Vasorelaxation to ACh was significantly enhanced in mesenteric arteries from CBD-treated ZDF rats, but not ZDF Lean rats. The enhanced vasorelaxation in ZDF mesenteric arteries was no longer observed after COX inhibition using indomethacin or nitric oxide (NO) inhibition using L-NAME. Increased levels of serum c-peptide, insulin and intracellular adhesion molecule-1 observed in the ZDF compared to ZDF Lean rats were no longer significant after 7 days CBD treatment.

Conclusion and implications: Short-term in vivo treatment with CBD improves ex vivo endothelium-dependent vasorelaxation in mesenteric arteries from ZDF rats due to COX- or NO-mediated mechanisms, and leads to improvements in serum biomarkers.

The role of CB1 in intestinal permeability and inflammation

The endocannabinoid system has previously been shown to play a role in the permeability and inflammatory response of the human gut. The goal of our study was to determine the effects of endogenous anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) on the permeability and inflammatory response of intestinal epithelium under normal, inflammatory, and hypoxic conditions. Human intestinal mucosa was modeled using Caco-2 cells. Human tissue was collected from planned colorectal resections. Accumulation of AEA and 2-AG was achieved by inhibiting their metabolizing enzymes URB597 (a fatty acid amide hydrolase inhibitor) and JZL184 (a monoacylglycerol lipase inhibitor). Inflammation and ischemia were simulated with TNF-α and IFN-γ and oxygen deprivation. Permeability changes were measured by transepithelial electrical resistance. The role of the CB₁ receptor was explored using CB₁-knockdown (CB₁Kd) intestinal epithelial cells. Endocannabinoid levels were measured using liquid chromatography-mass spectrometry. Cytokine secretion was measured using multiplex and ELISA. URB597 and JZL184 caused a concentration-dependent increase in permeability via CB₁ (P < 0.0001) and decreased cytokine production. Basolateral application of JZL184 decreased permeability via CB₁ (P < 0.0001). URB597 and JZL184 increased the enhanced (worsened) permeability caused by inflammation and hypoxia (P < 0.0001 and P < 0.05). CB₁Kd cells showed reduced permeability response to inflammation (P < 0.01) but not hypoxia. 2-AG levels were increased in response to inflammation and hypoxia in Caco-2 cells. In human mucosal tissue, inflammation increased the secretion of granulocyte macrophage-colony stimulating factor, IL-12, -13, and -15, which was prevented with ex vivo treatment with URB597 and JZL184, and was inhibited by a CB₁ antagonist. The results of this study show that endogenous AEA and 2-AG production and CB₁ activation play a key modulatory roles in normal intestinal mucosa permeability and in inflammatory and hypoxic conditions.-Karwad, M. A., Couch, D. G., Theophilidou, E., Sarmad, S., Barrett, D. A., Larvin, M., Wright, K. L., Lund, J. N., O'Sullivan, S. E. The role of CB₁ in intestinal permeability and inflammation.

A Systematic Review and Meta-Analysis of the Haemodynamic Effects of Cannabidiol

Despite cannabidiol (CBD) having numerous cardiovascular effects in vitro, its haemodynamic effects in vivo are unclear. Nonetheless, the clinical use of CBD (Epidiolex) is becoming more widespread. The aim of this systematic review was to establish whether CBD is associated with changes in haemodynamics in vivo. Twenty-five studies that assessed the haemodynamic effects of CBD (from PubMed, Medline and EMBASE) were systematically reviewed and meta-analyzed. Data on blood pressure (BP), heart rate (HR), and blood flow (BF) were extracted and analyzed using random effects models. Twenty-two publications assessed BP and HR among 6 species (BP n = 344 and HR n = 395), and 5 publications assessed BF in 3 species (n = 56) after acute dosing of CBD. Chronic dosing was assessed in 4 publications in 3 species (total subjects BP, n = 6; HR, n = 27; BF, n = 3). Acute CBD dosing had no effect on BP or HR under control conditions. Similarly, chronic dosing with CBD had no effect on HR. In models of stress, acute CBD administration significantly reduced the increase in BP and HR induced by stress (BP, mean difference (MD) −3.54, 95% CI −5.19, −1.9, p < 0.0001; HR, MD −16.23, 95% CI −26.44, −6.02, p = 0.002). In mouse models of stroke, CBD significantly increased cerebral blood flow (CBF, standardized mean difference (SMD) 1.62, 95% CI 0.41, 2.83, p = 0.009). Heterogeneity among the studies was present, there was no publication bias except in HR of control and stressful conditions after acute CBD dosing, and median study quality was 5 out of 9 (ranging from 1 to 8). From the limited data available, we conclude that acute and chronic administration of CBD had no effect on BP or HR under control conditions, but reduces BP and HR in stressful conditions, and increases cerebral blood flow (CBF) in mouse models of stroke. Further studies are required to fully understand the potential haemodynamic effects of CBD in humans under normal and pathological conditions.

Efficacy and Safety of Cannabidiol and Tetrahydrocannabivarin on Glycemic and Lipid Parameters in Patients With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled, Parallel Group Pilot Study

OBJECTIVE

Cannabidiol (CBD) and Δ(9)-tetrahydrocannabivarin (THCV) are nonpsychoactive phytocannabinoids affecting lipid and glucose metabolism in animal models. This study set out to examine the effects of these compounds in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this randomized, double-blind, placebo-controlled study, 62 subjects with noninsulin-treated type 2 diabetes were randomized to five treatment arms: CBD (100 mg twice daily), THCV (5 mg twice daily), 1:1 ratio of CBD and THCV (5 mg/5 mg, twice daily), 20:1 ratio of CBD and THCV (100 mg/5 mg, twice daily), or matched placebo for 13 weeks. The primary end point was a change in HDL-cholesterol concentrations from baseline. Secondary/tertiary end points included changes in glycemic control, lipid profile, insulin sensitivity, body weight, liver triglyceride content, adipose tissue distribution, appetite, markers of inflammation, markers of vascular function, gut hormones, circulating endocannabinoids, and adipokine concentrations. Safety and tolerability end points were also evaluated.

RESULTS

Compared with placebo, THCV significantly decreased fasting plasma glucose (estimated treatment difference [ETD] = -1.2 mmol/L; P < 0.05) and improved pancreatic β-cell function (HOMA2 β-cell function [ETD = -44.51 points; P < 0.01]), adiponectin (ETD = -5.9 × 10(6) pg/mL; P < 0.01), and apolipoprotein A (ETD = -6.02 μmol/L; P < 0.05), although plasma HDL was unaffected. Compared with baseline (but not placebo), CBD decreased resistin (-898 pg/ml; P < 0.05) and increased glucose-dependent insulinotropic peptide (21.9 pg/ml; P < 0.05). None of the combination treatments had a significant impact on end points. CBD and THCV were well tolerated.

CONCLUSIONS

THCV could represent a new therapeutic agent in glycemic control in subjects with type 2 diabetes.

Oleoylethanolamine and palmitoylethanolamine modulate intestinal permeability in vitro via TRPV1 and PPARα

Cannabinoids modulate intestinal permeability through cannabinoid receptor 1 (CB₁). The endocannabinoid-like compounds oleoylethanolamine (OEA) and palmitoylethanolamine (PEA) play an important role in digestive regulation, and we hypothesized they would also modulate intestinal permeability. Transepithelial electrical resistance (TEER) was measured in human Caco-2 cells to assess permeability after application of OEA and PEA and relevant antagonists. Cells treated with OEA and PEA were stained for cytoskeletal F-actin changes and lysed for immunoassay. OEA and PEA were measured by liquid chromatography-tandem mass spectrometry. OEA (applied apically, logEC₅₀ -5.4) and PEA (basolaterally, logEC₅₀ -4.9; apically logEC₅₀ -5.3) increased Caco-2 resistance by 20-30% via transient receptor potential vanilloid (TRPV)-1 and peroxisome proliferator-activated receptor (PPAR)-α. Preventing their degradation (by inhibiting fatty acid amide hydrolase) enhanced the effects of OEA and PEA. OEA and PEA induced cytoskeletal changes and activated focal adhesion kinase and ERKs 1/2, and decreased Src kinases and aquaporins 3 and 4. In Caco-2 cells treated with IFNγ and TNFα, OEA (via TRPV1) and PEA (via PPARα) prevented or reversed the cytokine-induced increased permeability compared to vehicle (0.1% ethanol). PEA (basolateral) also reversed increased permeability when added 48 or 72 h after cytokines (P < 0.001, via PPARα). Cellular and secreted levels of OEA and PEA (P < 0.001-0.001) were increased in response to inflammatory mediators. OEA and PEA have endogenous roles and potential therapeutic applications in conditions of intestinal hyperpermeability and inflammation.-Karwad, M. A., Macpherson, T., Wang, B., Theophilidou, E., Sarmad, S., Barrett, D. A., Larvin, M., Wright, K. L., Lund, J. N., O'Sullivan, S. E. Oleoylethanolamine and palmitoylethanolamine modulate intestinal permeability in vitro via TRPV1 and PPARα.

The endocannabinoid anandamide causes endothelium-dependent vasorelaxation in human mesenteric arteries

The endocannabinoid anandamide (AEA) causes vasorelaxation in animal studies. Although circulating AEA levels are increased in many pathologies, little is known about its vascular effects in humans. The aim of this work was to characterise the effects of AEA in human arteries. Ethical approval was granted to obtain mesenteric arteries from patients (n = 31) undergoing bowel resection. Wire myography was used to probe the effects and mechanisms of action of AEA. RT‐PCR was used to confirm the presence of receptor mRNA in human aortic endothelial cells (HAECs) and intracellular signalling proteins were measured using multiplex technology. AEA caused vasorelaxation of precontracted human mesenteric arteries with an R_max of ∼30%. A synthetic CB₁ agonist (CP55940) caused greater vasorelaxation (R_max ∼60%) while a CB₂ receptor agonist (HU308) had no effect on vascular tone. AEA-induced vasorelaxation was inhibited by removing the endothelium, inhibition of nitric oxide (NO) synthase, antagonising the CB₁ receptor and antagonising the proposed novel endothelial cannabinoid receptor (CB_e). AEA‐induced vasorelaxation was not affected by CB₂ antagonism, by depleting sensory neurotransmitters, or inhibiting cyclooxygenase activity. RT‐PCR showed CB₁ but not CB₂ receptors were present in HAECs, and AEA and CP55940 had similar profiles in HAECs (increased phosphorylation of JNK, NFκB, ERK, Akt, p70s6K, STAT3 and STAT5). Post hoc analysis of the data set showed that overweight patients and those taking paracetamol had reduced vasorelaxant responses to AEA. These data show that AEA causes moderate endothelium-dependent, NO-dependent vasorelaxation in human mesenteric arteries via activation of CB₁ receptors.

Cannabidiol protects an in vitro model of the blood-brain barrier from oxygen-glucose deprivation via PPARγ and 5-HT1A receptors

BACKGROUND AND PURPOSE

In vivo and in vitro studies have demonstrated a protective effect of cannabidiol (CBD) in reducing infarct size in stroke models and against epithelial barrier damage in numerous disease models. We aimed to investigate whether CBD also affects blood-brain barrier (BBB) permeability following ischaemia.

EXPERIMENTAL APPROACH

Human brain microvascular endothelial cell (HBMEC) and human astrocyte co-cultures modelled the BBB. Ischaemia was modelled by oxygen-glucose deprivation (OGD) and permeability was measured by transepithelial electrical resistance.

KEY RESULTS

CBD (10 μM) prevented the increase in permeability caused by 4 h OGD. CBD was most effective when administered before the OGD, but protective effects were observed up to 2 h into reperfusion. This protective effect was inhibited by a PPARγ antagonist and partly reduced by a 5-HT1A receptor antagonist, but was unaffected by antagonists of cannabinoid CB1 or CB2 receptors, TRPV1 channels or adenosine A2A receptors. CBD also reduced cell damage, as measured by LDH release and by markers of cellular adhesion, such as the adhesion molecule VCAM-1. In HBMEC monocultures, CBD decreased VCAM-1 and increased VEGF levels, effects which were inhibited by PPARγ antagonism.

CONCLUSIONS AND IMPLICATIONS

These data suggest that preventing permeability changes at the BBB could represent an as yet unrecognized mechanism of CBD-induced neuroprotection in ischaemic stroke, a mechanism mediated by activation of PPARγ and 5-HT1A receptors.

The endogenous cannabinoid anandamide increases human airway epithelial cell permeability through an arachidonic acid metabolite

Injury to the bronchial epithelium in respiratory diseases such as asthma and COPD results in the loss of barrier function and an elevated sensitivity to environmental insults. An increased release of the endogenous cannabinoid, anandamide in response to inhalation of allergen in asthmatic patients has been reported. The aim of this study was, therefore, to determine the effects of endocannabinoids on bronchial epithelial cell permeability and to investigate the mechanisms involved. Calu-3 human bronchial epithelial cells were cultured at air-liquid interface to allow development of tight junctions. Changes in Transepithelial Electrical Resistance (TEER), a reflection of epithelial permeability, were measured at various time points post-treatment, and expression of the tight junction proteins, occludin and ZO-1, were determined using Western immunoblotting. Anandamide produced a significant reduction in TEER, which was unaffected by cannabinoid receptor antagonists, but attenuated by URB597, an inhibitor of fatty acid amide hydrolase, and by a combination of cyclooxygenase (COX) and lipoxygenase (LOX) blockade. The anandamide metabolite, arachidonic acid, showed similar TEER decrease that was also prevented in the presence of COX and LOX inhibitor. Expression of occludin and ZO-1 were also reduced by anandamide. These findings indicate a pro-inflammatory-like effect of anandamide on bronchial epithelial permeability, mediated by cyclooxygenase and lipoxygenase metabolites, and suggest that inhibition of anandamide degradation might provide a novel approach to treat airway inflammation.

Remote effects of acute kidney injury in a porcine model

Acute kidney injury (AKI) is a common and serious condition with no specific treatment. An episode of AKI may affect organs distant from the kidney, further increasing the morbidity associated with AKI. The mechanism of organ cross talk after AKI is unclear. The renal and immune systems of pigs and humans are alike. Using a preclinical animal (porcine) model, we tested the hypothesis that early effects of AKI on distant organs is by immune cell infiltration, leading to inflammatory cytokine production, extravasation, and edema. In 29 pigs exposed to either sham surgery or renal ischemia-reperfusion (control, n = 12; AKI, n = 17), we assessed remote organ (liver, lung, brain) effects in the short (from 2- to 48-h reperfusion) and longer term (5 wk later) using immunofluorescence (for leukocyte infiltration, apoptosis), a cytokine array, tissue elemental analysis (e.g., electrolytes), blood hematology and chemistry (e.g., liver enzymes), and PCR (for inflammatory markers). AKI elicited significant, short-term (∼24 h) increments in enzymes indicative of acute liver damage (e.g. , AST: ALT ratio; P = 0.02) and influenced tissue biochemistry in some remote organs (e.g., lung tissue [Ca(2+)] increased; P = 0.04). These effects largely resolved after 48 h, and no further histopathology, edema, apoptosis, or immune cell infiltration was noted in the liver, lung, or hippocampus in the short and longer term. AKI has subtle biochemical effects on remote organs in the short term, including a transient increment in markers of acute liver damage. These effects resolved by 48 h, and no further remote organ histopathology, apoptosis, edema, or immune cell infiltration was noted.

Cannabidiol causes endothelium-dependent vasorelaxation of human mesenteric arteries via CB1 activation

Aims

The protective effects of cannabidiol (CBD) have been widely shown in preclinical models and have translated into medicines for the treatment of multiple sclerosis and epilepsy. However, the direct vascular effects of CBD in humans are unknown.

Methods and results

Using wire myography, the vascular effects of CBD were assessed in human mesenteric arteries, and the mechanisms of action probed pharmacologically. CBD-induced intracellular signalling was characterized using human aortic endothelial cells (HAECs). CBD caused acute, non-recoverable vasorelaxation of human mesenteric arteries with an R_max of ∼40%. This was inhibited by cannabinoid receptor 1 (CB₁) receptor antagonists, desensitization of transient receptor potential channels using capsaicin, removal of the endothelium, and inhibition of potassium efflux. There was no role for cannabinoid receptor-2 (CB₂) receptor, peroxisome proliferator activated receptor (PPAR)γ, the novel endothelial cannabinoid receptor (CB_e), or cyclooxygenase. CBD-induced vasorelaxation was blunted in males, and in patients with type 2 diabetes or hypercholesterolemia. In HAECs, CBD significantly reduced phosphorylated JNK, NFκB, p70s6 K and STAT5, and significantly increased phosphorylated CREB, ERK1/2, and Akt levels. CBD also increased phosphorylated eNOS (ser1177), which was correlated with increased levels of ERK1/2 and Akt levels. CB₁ receptor antagonism prevented the increase in eNOS phosphorylation.

Conclusion

This study shows, for the first time, that CBD causes vasorelaxation of human mesenteric arteries via activation of CB₁ and TRP channels, and is endothelium- and nitric oxide-dependent.

Endocannabinoids modulate human blood-brain barrier permeability in vitro

Background and Purpose

Endocannabinoids alter permeability at various epithelial barriers, and cannabinoid receptors and endocannabinoid levels are elevated by stroke, with potential neuroprotective effects. We therefore explored the role of endocannabinoids in modulating blood–brain barrier (BBB) permeability in normal conditions and in an ischaemia/reperfusion model.

Experimental Approach

Human brain microvascular endothelial cell and astrocyte co-cultures modelled the BBB. Ischaemia was modelled by oxygen-glucose deprivation (OGD) and permeability was measured by transepithelial electrical resistance. Endocannabinoids or endocannabinoid-like compounds were assessed for their ability to modulate baseline permeability or OGD-induced hyperpermeability. Target sites of action were investigated using receptor antagonists and subsequently identified with real-time PCR.

Key Results

Anandamide (10 μM) and oleoylethanolamide (OEA, 10 μM) decreased BBB permeability (i.e. increased resistance). This was mediated by cannabinoid CB₂ receptors, transient receptor potential vanilloid 1 (TRPV1) channels, calcitonin gene-regulated peptide (CGRP) receptor (anandamide only) and PPARα (OEA only). Application of OEA, palmitoylethanolamide (both PPARα mediated) or virodhamine (all 10 μM) decreased the OGD-induced increase in permeability during reperfusion. 2-Arachidonoyl glycerol, noladin ether and oleamide did not affect BBB permeability in normal or OGD conditions. N-arachidonoyl-dopamine increased permeability through a cytotoxic mechanism. PPARα and γ, CB₁ receptors, TRPV1 channels and CGRP receptors were expressed in both cell types, but mRNA for CB₂ receptors was only present in astrocytes.

Conclusion and Implication

The endocannabinoids may play an important modulatory role in normal BBB physiology, and also afford protection to the BBB during ischaemic stroke, through a number of target sites.

Changes in plasma levels of N-arachidonoyl ethanolamine and N-palmitoylethanolamine following bariatric surgery in morbidly obese females with impaired glucose homeostasis

AIM

We examined endocannabinoids (ECs) in relation to bariatric surgery and the association between plasma ECs and markers of insulin resistance.

METHODS

A study of 20 participants undergoing bariatric surgery. Fasting and 2-hour plasma glucose, lipids, insulin, and C-peptide were recorded preoperatively and 6 months postoperatively with plasma ECs (AEA, 2-AG) and endocannabinoid-related lipids (PEA, OEA).

RESULTS

Gender-specific analysis showed differences in AEA, OEA, and PEA preoperatively with reductions in AEA and PEA in females postoperatively. Preoperatively, AEA was correlated with 2-hour glucose (r = 0.55, P = 0.01), HOMA-IR (r = 0.61, P = 0.009), and HOMA %S (r = -0.71, P = 0.002). OEA was correlated with weight (r = 0.49, P = 0.03), waist circumference (r = 0.52, P = 0.02), fasting insulin (r = 0.49, P = 0.04), and HOMA-IR (r = 0.48, P = 0.05). PEA was correlated with fasting insulin (r = 0.49, P = 0.04). 2-AG had a negative correlation with fasting glucose (r = -0.59, P = 0.04).

CONCLUSION

Gender differences exist in circulating ECs in obese subjects. Females show changes in AEA and PEA after bariatric surgery. Specific correlations exist between different ECs and markers of obesity and insulin and glucose homeostasis.

Defining uremic arterial functional abnormalities in patients recently started on haemodialysis: combined in vivo and ex vivo assessment

Endothelial dysfunction is a key initiating event in vascular disease in chronic kidney disease (CKD) patients and haemodialysis (HD) patients exhibit significant vascular abnormalities. To understand this further, we examined how ex vivo intrinsic function in isolated arteries correlates with in vivo assessments of cardiovascular status in HD patients. Abdominal fat biopsies were obtained from 11 HD patients and 26 non-uremic controls. Subcutaneous arteries were dissected and mounted on a wire myograph, and cumulative concentration-response curves to noradrenalin, endothelin-1, a thromboxane A₂ agonist (U46619), angiotensin II, vasopressin, bradykinin (BK), acetylcholine (ACh) and sodium nitroprusside (SNP) were constructed. Pulse wave velocity and blood pressure were measured in HD patients. Enhanced (P<0.05−0.0001) maximal contractile responses (R_max) to all spasmogens (particularly vasopressin) were observed in arteries from HD patients compared to controls, and this effect was more pronounced in arteries with an internal diameter>600 µm. The potency (pEC₅₀) of U46619 (P<0.01) and vasopressin (P<0.001) was also increased in arteries>600 µm of HD patients. The maximal relaxant response to the endothelium-dependent dilators ACh and BK were lower in HD patients (P<0.01-P<0.0001) (worse for ACh than BK); however the endothelium-independent dilator SNP was similar in both groups. PWV was significantly correlated with the vasoconstrictor response to vasopressin (P = 0.042) in HD patients. HD patients are primed for hypertension and end organ demand ischaemia by a highly sensitised pressor response. The failure of arterial relaxation is mediated by endothelial dysfunction. Intrinsic vascular abnormalities may be important in sensitising HD patients to recurrent cumulative ischaemic end organ injury.

Vascular targets for cannabinoids: animal and human studies

Application of cannabinoids and endocannabinoids to perfused vascular beds or individual isolated arteries results in changes in vascular resistance. In most cases, the result is vasorelaxation, although vasoconstrictor responses are also observed. Cannabinoids also modulate the actions of vasoactive compounds including acetylcholine, methoxamine, angiotensin II and U46619 (thromboxane mimetic). Numerous mechanisms of action have been proposed including receptor activation, potassium channel activation, calcium channel inhibition and the production of vasoactive mediators such as calcitonin gene-related peptide, prostanoids, NO, endothelial-derived hyperpolarizing factor and hydrogen peroxide. The purpose of this review is to examine the evidence for the range of receptors now known to be activated by cannabinoids. Direct activation by cannabinoids of CB1 , CBe , TRPV1 (and potentially other TRP channels) and PPARs in the vasculature has been observed. A potential role for CB2, GPR55 and 5-HT1 A has also been identified in some studies. Indirectly, activation of prostanoid receptors (TP, IP, EP1 and EP4 ) and the CGRP receptor is involved in the vascular responses to cannabinoids. The majority of this evidence has been obtained through animal research, but recent work has confirmed some of these targets in human arteries. Vascular responses to cannabinoids are enhanced in hypertension and cirrhosis, but are reduced in obesity and diabetes, both due to changes in the target sites of action. Much further work is required to establish the extent of vascular actions of cannabinoids and the application of this research in physiological and pathophysiological situations.

LINKED ARTICLES

This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.

The effects of obesity, diabetes and metabolic syndrome on the hydrolytic enzymes of the endocannabinoid system in animal and human adipocytes

Background

Circulating endocannabinoid levels are increased in obesity and diabetes. We have shown that fatty acid amide hydrolase (FAAH, an endocannabinoid hydrolysing enzyme) in subcutaneous adipose tissue positively correlates with BMI in healthy volunteers. The aim of the present study was to investigate whether the hydrolytic enzymes of the endocannabinoid system are affected by diabetes or metabolic syndrome in obesity.

Methods

Using radiolabelled substrates, FAAH and monoacylglycerol lipase (MGL) activities were assessed in adipocytes from various adipose depots in Zucker rats (n = 22, subcutaneous abdominal, visceral and epididymal) and bariatric patients (n = 28, subcutaneous abdominal and omental).

Results

FAAH activity was significantly increased in adipocytes of obese (Zucker Fatty) compared to Zucker lean rats (P < 0.05) but was not raised in the Zucker Diabetic Fatty rats (ZDF). MGL activity was raised in both Zucker Fatty (P < 0.001-0.01) and ZDF rats (P < 0.05) and was positively correlated with body weight and plasma glucose levels (P < 0.01). In bariatric patients (BMI range 37–58 kg.m²), there was a trend for MGL activity to correlate positively with BMI, reaching significance when type 2 diabetic patients were removed. FAAH and MGL activities in obese humans were not correlated with blood pressure, skinfold thicknesses, fasting glucose, insulin, HbA1c, triglycerides or cholesterol levels.

Conclusions

FAAH in adipocytes is differentially altered in animal models of obesity and diabetes, while MGL activity is increased by both. However, in obese humans, FAAH or MGL activity in adipocytes is not affected by diabetes, dyslipidaemia or other markers of metabolic dysfunction. This suggests increased circulating levels of endocannabinoids are not a result of altered degradation in adipose tissue.

Is the cardiovascular system a therapeutic target for cannabidiol?

Cannabidiol (CBD) has beneficial effects in disorders as wide ranging as diabetes, Huntington's disease, cancer and colitis. Accumulating evidence now also suggests that CBD is beneficial in the cardiovascular system. CBD has direct actions on isolated arteries, causing both acute and time-dependent vasorelaxation. In vitro incubation with CBD enhances the vasorelaxant responses in animal models of impaired endothelium-dependent vasorelaxation. CBD protects against the vascular damage caused by a high glucose environment, inflammation or the induction of type 2 diabetes in animal models and reduces the vascular hyperpermeability associated with such environments. A common theme throughout these studies is the anti-inflammatory and anti-oxidant effect of CBD. In the heart, in vivo CBD treatment protects against ischaemia-reperfusion damage and against cardiomyopathy associated with diabetes. Similarly, in a different model of ischaemia-reperfusion, CBD has been shown to reduce infarct size and increase blood flow in animal models of stroke, sensitive to 5HT(1A) receptor antagonism. Although acute or chronic CBD treatment seems to have little effect on haemodynamics, CBD reduces the cardiovascular response to models of stress, applied either systemically or intracranially, inhibited by a 5HT(1A) receptor antagonist. In blood, CBD influences the survival and death of white blood cells, white blood cell migration and platelet aggregation. Taken together, these preclinical data appear to support a positive role for CBD treatment in the heart, and in peripheral and cerebral vasculature. However, further work is required to strengthen this hypothesis, establish mechanisms of action and whether similar responses to CBD would be observed in humans.

Cannabinoids mediate opposing effects on inflammation-induced intestinal permeability

BACKGROUND AND PURPOSE

Activation of cannabinoid receptors decreases emesis, inflammation, gastric acid secretion and intestinal motility. The ability to modulate intestinal permeability in inflammation may be important in therapy aimed at maintaining epithelial barrier integrity. The aim of the present study was to determine whether cannabinoids modulate the increased permeability associated with inflammation in vitro.

EXPERIMENTAL APPROACH

Confluent Caco-2 cell monolayers were treated for 24 h with IFNγ and TNFα (10 ng·mL(-1) ). Monolayer permeability was measured using transepithelial electrical resistance and flux measurements. Cannabinoids were applied either apically or basolaterally after inflammation was established. Potential mechanisms of action were investigated using antagonists for CB(1) , CB(2) , TRPV1, PPARγ and PPARα. A role for the endocannabinoid system was established using inhibitors of the synthesis and degradation of endocannabinoids.

KEY RESULTS

Δ(9) -Tetrahydrocannabinol (THC) and cannabidiol accelerated the recovery from cytokine-induced increased permeability; an effect sensitive to CB(1) receptor antagonism. Anandamide and 2-arachidonylglycerol further increased permeability in the presence of cytokines; this effect was also sensitive to CB(1) antagonism. No role for the CB(2) receptor was identified in these studies. Co-application of THC, cannabidiol or a CB(1) antagonist with the cytokines ameliorated their effect on permeability. Inhibiting the breakdown of endocannabinoids worsened, whereas inhibiting the synthesis of endocannabinoids attenuated, the increased permeability associated with inflammation.

CONCLUSIONS AND IMPLICATIONS

These findings suggest that locally produced endocannabinoids, acting via CB(1) receptors play a role in mediating changes in permeability with inflammation, and that phytocannabinoids have therapeutic potential for reversing the disordered intestinal permeability associated with inflammation.

LINKED ARTICLES

This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7.

Endocannabinoids and the cardiovascular response to stress

Stress activates the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS), resulting in cardiovascular responses. The endocannabinoid system (ECS), a ubiquitously expressed lipid signalling system, modulates both HPA and SNS activity. The purpose of this review is to explore the possible involvement/role of the ECS in the cardiovascular response to stress. The ECS has numerous cardiovascular effects including modulation of blood pressure, heart rate, the baroreflex, and direct vascular actions. It is also involved in a protective manner in response to stressors in cardiac preconditioning, and various stressors (for example, pain, orthostasis and social stress) increase plasma levels of endocannabinoids. Given the multitude of vascular effects of endocannabinoids, this is bound to have consequences. Beneficial effects of ECS upregulation could include cardioprotection, vasodilatation, CB(2)-mediated anti-inflammatory effects and activation of peroxisome proliferator-activated receptors. Negative effects of endocannabinoids could include mediation of the effects of glucocorticoids, CB(1)-mediated metabolic changes, and metabolism to vasoconstrictor products. It is also likely that there is a central role for the ECS in modulating cardiovascular activity via the HPA and SNS. However, much more work is required to fully integrate the role of the ECS in mediating many of the physiological responses to stress, including cardiovascular responses.

The activity of the endocannabinoid metabolising enzyme fatty acid amide hydrolase in subcutaneous adipocytes correlates with BMI in metabolically healthy humans

Background

The endocannabinoid system (ECS) is a ubiquitously expressed signalling system, with involvement in lipid metabolism and obesity. There are reported changes in obesity of blood concentrations of the endocannabinoids anandamide (AEA) and 2-arachidonoylglcyerol (2-AG), and of adipose tissue expression levels of the two key catabolic enzymes of the ECS, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL). Surprisingly, however, the activities of these enzymes have not been assayed in conditions of increasing adiposity. The aim of the current study was to investigate whether FAAH and MGL activities in human subcutaneous adipocytes are affected by body mass index (BMI), or other markers of adiposity and metabolism.

Methods

Subcutaneous abdominal mature adipocytes, fasting blood samples and anthropometric measurements were obtained from 28 metabolically healthy subjects representing a range of BMIs. FAAH and MGL activities were assayed in mature adipocytes using radiolabelled substrates. Serum glucose, insulin and adipokines were determined using ELISAs.

Results

MGL activity showed no relationship with BMI or other adiposity indices, metabolic markers (fasting serum insulin or glucose) or serum adipokine levels (adiponectin, leptin or resistin). In contrast, FAAH activity in subcutaneous adipocytes correlated positively with BMI and waist circumference, but not with skinfold thickness, metabolic markers or serum adipokine levels.

Conclusions

In this study, novel evidence is provided that FAAH activity in subcutaneous mature adipocytes increases with BMI, whereas MGL activity does not. These findings support the hypothesis that some components of the ECS are upregulated with increasing adiposity in humans, and that AEA and 2-AG may be regulated differently.

Pharmacological effects of cannabinoids on the Caco-2 cell culture model of intestinal permeability

Activation of cannabinoid receptors decreases emesis, inflammation, gastric acid secretion, and intestinal motility. However, the effects of cannabinoids on intestinal permeability have not yet been established. The aim of the present study is to examine the effects of cannabinoids on intestinal permeability in an in vitro model. Caco-2 cells were grown until fully confluent on inserts in 12-well plates. Transepithelial electrical resistance (TEER) measurements were made as a measure of permeability. EDTA (50 μM) was applied to reversibly increase permeability (reduce TEER). The effects of cannabinoids on permeability in combination with EDTA, or alone, were assessed. Potential target sites of action were investigated using antagonists of the cannabinoid (CB)(1) receptor, CB(2) receptor, transient receptor potential vanilloid subtype 1 (TRPV1), peroxisome proliferator-activated receptor (PPAR)γ, PPARα, and a proposed cannabinoid receptor. When applied to the apical or basolateral membrane of Caco-2 cells, Δ(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD) enhanced the speed of recovery of EDTA-induced increased permeability. This effect was sensitive to cannabinoid CB(1) receptor antagonism only. Apical application of endocannabinoids caused increased permeability, sensitive to cannabinoid CB(1) receptor antagonism. By contrast, when endocannabinoids were applied basolaterally, they enhanced the recovery of EDTA-induced increased permeability, and this involved additional activation of TRPV1. All cannabinoids tested increased the mRNA of the tight junction protein zona occludens-1, but only endocannabinoids also decreased the mRNA of claudin-1. These findings suggest that endocannabinoids may play a role in modulating intestinal permeability and that plant-derived cannabinoids, such as THC and CBD, may have therapeutic potential in conditions associated with abnormally permeable intestinal epithelium.

Cannabinoid activation of peroxisome proliferator-activated receptors: potential for modulation of inflammatory disease

Cannabinoids act via cell surface G protein-coupled receptors (CB(1) and CB(2)) and the ion channel receptor TRPV1. Evidence has now emerged suggesting that an additional target is the peroxisome proliferator-activated receptor (PPAR) family of nuclear receptors. There are three PPAR subtypes alpha, delta (also known as beta) and gamma, which regulate cell differentiation, metabolism and immune function. The major endocannabinoids, anandamide and 2-arachidonoylglycerol, and ajulemic acid, a structural analogue of the phytocannabinoid Delta(9)-tetrahydrocannabinol (THC), have anti-inflammatory properties mediated by PPARgamma. Other cannabinoids which activate PPARgamma include N-arachidonoyl-dopamine, THC, cannabidiol, HU210, WIN55212-2 and CP55940. The endogenous acylethanolamines, oleoylethanolamide and palmitoylethanolamide regulate feeding and body weight, stimulate fat utilization and have neuroprotective effects mediated through PPARalpha. Other endocannabinoids that activate PPARalpha include anandamide, virodhamine and noladin ether. There is, as yet, little direct evidence for interactions of cannabinoids with PPARdelta. There is a convergence of effects of cannabinoids, acting via cell surface and nuclear receptors, on immune cell function which provides promise for the targeted therapy of a variety of immune, particularly neuroinflammatory, diseases.

Cannabinoids go nuclear: evidence for activation of peroxisome proliferator-activated receptors

Cannabinoids act at two classical cannabinoid receptors (CB1 and CB2), a 7TM orphan receptor and the transmitter-gated channel transient receptor potential vanilloid type-1 receptor. Recent evidence also points to cannabinoids acting at members of the nuclear receptor family, peroxisome proliferator-activated receptors (PPARs, with three subtypes alpha, beta (delta) and gamma), which regulate cell differentiation and lipid metabolism. Much evidence now suggests that endocannabinoids are natural activators of PPAR alpha. Oleoylethanolamide regulates feeding and body weight, stimulates fat utilization and has neuroprotective effects mediated through activation of PPAR alpha. Similarly, palmitoylethanolamide regulates feeding and lipid metabolism and has anti-inflammatory properties mediated by PPAR alpha. Other endocannabinoids that activate PPAR alpha include anandamide, virodhamine and noladin. Some (but not all) endocannabinoids also activate PPAR gamma; anandamide and 2-arachidonoylglycerol have anti-inflammatory properties mediated by PPAR gamma. Similarly, ajulemic acid, a structural analogue of a metabolite of Delta(9)-tetrahydrocannabinol (THC), causes anti-inflammatory effects in vivo through PPAR gamma. THC also activates PPAR gamma, leading to a time-dependent vasorelaxation in isolated arteries. Other cannabinoids which activate PPAR gamma include N-arachidonoyl-dopamine, HU210, WIN55212-2 and CP55940. In contrast, little research has been carried out on the effects of cannabinoids at PPAR delta. In this newly emerging area, a number of research questions remain unanswered; for example, why do cannabinoids activate some isoforms and not others? How much of the chronic effects of cannabinoids are through activation of nuclear receptors? And importantly, do cannabinoids confer the same neuro- and cardioprotective benefits as other PPAR alpha and PPAR gamma agonists? This review will summarize the published literature implicating cannabinoid-mediated PPAR effects and discuss the implications thereof.