Cannabinoid 2 receptor activation reduces leukocyte adhesion and improves capillary perfusion in the iridial microvasculature during systemic inflammation

Vasoactive and Antifibrotic Properties of Cannabinoids and Applications to Vasospastic/Vaso-Occlusive Disorders: A Systematic Review

BACKGROUND

Management of vasospastic and vaso-occlusive disorders is a complex challenge, with current treatments showing varied success. Cannabinoids have demonstrated both vasodilatory and antifibrotic properties, which present potential mechanisms for therapeutic relief. No existing review examines these effects in peripheral circulation in relation to vasospastic and vaso-occlusive disorders. This study aims to investigate vasodilatory and antifibrotic properties of cannabinoids in peripheral vasculature for application in vasospastic and vaso-occlusive disorders affecting the hand.

METHODS

A systematic search was conducted by 2 independent reviewers across PubMed, Cochrane, Ovid MEDLINE, and CINAHL to identify studies in accordance with the determined inclusion/exclusion criteria. Information regarding study design, medication, dosage, and hemodynamic or antifibrotic effects were extracted. Descriptive statistics were used to summarize study findings as appropriate.

RESULTS

A total of 584 articles were identified, and 32 were selected for inclusion. Studies were grouped by effect type: hemodynamic (n = 17, 53%) and antifibrotic (n = 15, 47%). Vasodilatory effects including reduced perfusion pressure, increased functional capillary density, inhibition of vessel contraction, and increased blood flow were reported in 82% of studies. Antifibrotic effects including reduced dermal thickening, reduced collagen synthesis, and reduced fibroblast migration were reported in 100% of studies.

CONCLUSION

Overall, cannabinoids were found to have vasodilatory and antifibrotic effects on peripheral circulation via both endothelium-dependent and independent mechanisms. Our review suggests the applicability of cannabis-based medicines for vasospastic and vaso-occlusive disorders affecting the hand (eg, Raynaud disease, Buerger disease). Future research should aim to assess the effectiveness of cannabis-based medicines for these conditions.

Involvement of cannabinoid receptors and neuroinflammation in early sepsis: Implications for posttraumatic stress disorder

Sepsis is associated with several comorbidities in survivors, such as posttraumatic stress disorder (PTSD). This study investigated whether rats that survive sepsis develop the generalization of fear memory as a model of PTSD. Responses to interventions that target the endothelin-1 (ET-1)/cannabinoid system and glial activation in the initial stages of sepsis were evaluated. As a control, we evaluated hyperalgesia before fear conditioning. Sepsis was induced by cecal ligation and puncture (CLP) in Wistar rats. CLP-induced sepsis with one or three punctures resulted in fear generalization in the survivors 13 and 20 days after the CLP procedure, a process that was not associated with hyperalgesia. Septic animals were intracerebroventricularly treated with vehicle, the endothelin receptor A (ETA) antagonist BQ123, the cannabinoid CB1 and CB2 receptor antagonists AM251 and AM630, respectively, and the glial blocker minocycline 4 h after CLP. The blockade of either CB1 or ETA receptors increased the survival rate, but only the former reversed fear memory generalization. The endothelinergic system blockade is important for improving survival but not for fear memory. Treatment with the CB2 receptor antagonist or minocycline also reversed the generalization of fear memory but did not increase the survival rate that was associated with CLP. Minocycline treatment also reduced tumor necrosis factor-α levels in the hippocampus suggesting that neuroinflammation is important for the generalization of fear memory induced by CLP. The influence of CLP on the generalization of fear memory was not related to Arc protein expression, a regulator of synaptic plasticity, in the dorsal hippocampus.

Is there a rational basis for cannabinoids research and development in ocular pain therapy? A systematic review of preclinical evidence

BACKGROUND

Purpose of the present systematic review is to investigate preclinical evidence in favor of the working hypothesis of efficacy of cannabinoids in ocular pain treatment.

METHODS

Literature search includes the most relevant repositories for medical scientific literature from inception until November, 24 2021. Data collection and selection of retrieved records adhere to PRISMA criteria.

RESULTS

In agreement with a priori established protocol the search retrieved 2471 records leaving 479 results after duplicates removal. Eleven records result from title and abstract screening to meet the inclusion criteria; only 4 results are eligible for inclusion in the qualitative synthesis impeding meta-analysis. The qualitative analysis highlights the antinociceptive and anti-inflammatory efficacy of Δ8-tetrahydrocannabinol, cannabidiol and its derivative HU-308 and of new racemic CB1 allosteric ligand GAT211 and its enantiomers GAT228 and GAT229. Moreover, CB2R agonists RO6871304 and RO6871085 and CB2R ligand HU910 provide evidence of anti-inflammatory efficacy. CB2 agonist HU308 reduces of 241% uveitis-induced leukocyte adhesion and changes lipidome profile. Methodological and design issues raise concern of risk of bias and the amount of studies is too small for generalization. Furthermore, the ocular pain model used can resemble only inflammatory but not neuropathic pain.

CONCLUSIONS

The role of the endocannabinoid system in ocular pain is underinvestigated, since only two studies assessing the effects of cannabinoid receptors modulators on pain behavior and other two on pain-related inflammatory processes are found. Preclinical studies investigating the efficacy of cannabinoids in ocular inflammatory and neuropathic pain models are needed to pave the way for clinical translation.

Cannabinoid Receptor 1 and 2 Signaling Pathways Involved in Sepsis

ABSTRACT

Sepsis is defined as a life-threatening organ dysfunction, caused by a dysregulated host response to an infection and can progress to septic shock, which represents a major challenge in critical care with a high mortality rate. Currently, there is no definitive treatment available for the dysregulated immune response in sepsis. Therefore, a better understanding of the pathophysiological mechanisms may be useful for elucidating the molecular basis of sepsis and may contribute to the development of new therapeutic strategies. The endocannabinoid system is an emerging research topic for the modulation of the host immune response under various pathological conditions. Cannabinoid receptors include the cannabinoid type 1 receptor (CB1) and the cannabinoid type 2 receptor (CB2). This review addresses the main functionality of CB1 and CB2 in sepsis, which can contribute to a better understanding about the pathophysiology of sepsis. Specifically, we discuss the role of CB1 in the cardiovascular system which is one of the biological systems that are strongly affected by sepsis and septic shock. We are also reviewing the role of CB2 in sepsis, specially CB2 activation, which exerts anti-inflammatory activities with potential benefit in sepsis.

Cannabinoid Receptor 2 Agonism is Capable of Preventing Lipopolysaccharide Induced Decreases of Cochlear Microcirculation - A Potential Approach for Inner Ear Pathologies

HYPOTHESIS

The ability of JWH-133, an agonist at the cannabinoid receptor 2, to abrogate the effects of lipopolysaccharide on cochlear microcirculation was investigated.

BACKGROUND

Cochlear inflammation and subsequent impairment of microcirculation is part of numerous pathologies affecting inner ear function, including suppurative labyrinthitis, noise trauma, and sudden sensorineural hearing loss. One way of causing cochlear inflammation is exposing the cochlea to lipopolysaccharide, a bacterial endotoxin.

METHODS

Twenty Dunkin-hartley guinea pigs were divided into four groups of five animals each. Two groups received topic treatment with JWH-133 and two received treatment with placebo. One group that had been treated with JWH-133 and one with placebo were then exposed to lipopolysaccharide or placebo, respectively. Cochlear microcirculation was quantified before, in between and after treatments by in vivo fluorescence microscopy.

RESULTS

Significantly different changes in cochlear blood flow were only seen in the group that was treated with placebo and subsequently lipopolysaccharide. Every other group showed no significant change in cochlear blood flow.

CONCLUSION

JWH-133 is capable of abrogating the effects of lipopolysaccharide on cochlear microcirculation. It may therefore be clinical interest in treating numerous inflammation associated cochlear pathologies.

Real-Time Imaging of Immune Modulation by Cannabinoids Using Intravital Fluorescence Microscopy

Introduction: The endocannabinoid system (ECS) is an endogenous regulatory system involved in a wide range of physiologic and disease processes. Study of ECS regulation provides novel drug targets for disease treatment. Intravital microscopy (IVM), a microscopy-based imaging method that allows the observation of cells and cell-cell interactions within various tissues and organs in vivo, has been utilized to study tissues and cells in their physiologic microenvironment. This article reviews the current state of the IVM techniques used in ECS-related inflammation research. Methodological Aspects of IVM: IVM with focus on conventional fluorescent microscope has been introduced in investigation of microcirculatory function and the behavior of individual circulating cells in an in vivo environment. Experimental setting, tissue protection under physiologic condition, and microscopical observation are described. Application of IVM in Experimental Inflammatory Disorders: Using IVM to investigate the effects of immune modulation by cannabinoids is extensively reviewed. The inflammatory disorders include sepsis, arthritis, diabetes, interstitial cystitis, and inflammatory conditions in the central nervous system and eyes. Conclusion: IVM is a critical tool in cannabinoid and immunology research. It has been applied to investigate the role of the ECS in physiologic and disease processes. This review demonstrates that the IVM technique provides a unique means in understanding ECS regulation on immune responses in diseases under their physical conditions, which could not be achieved by other methods.

The Effect of Orally Administered Low-Dose Dronabinol on Retinal Blood Flow and Oxygen Metabolism in Healthy Subjects

Purpose: The present study was performed to investigate the effect of oral dronabinol, a synthetic tetrahydrocannabinol derivate, on retinal hemodynamics in healthy subjects in a randomized, double-masked, placebo-controlled, 2-way crossover design. Methods: Twenty-four subjects received 5 mg dronabinol on 1 study day and placebo on the other study day. Total retinal blood flow (TRBF) was measured using a custom-built Doppler Optical Coherence Tomography system. Oxygen saturation of major retinal vessels was measured with a commercially available Dynamic Vessel Analyzer. Based on these parameters, retinal oxygen extraction was calculated. Measurements were performed before and after drug administration on both study days. Results: Placebo had no effect on TRBF, retinal arterial or venous oxygen content, and retinal oxygen extraction (P > 0.1 each). In contrast, dronabinol induced a significant increase in TRBF from 38.9 ± 6.1 to 40.7 ± 6.7 μL/min (P < 0.001), which was accompanied by a significant increase in retinal venous oxygen content (from 0.129 ± 0.008 to 0.132 ± 0.009 mL O₂/mL, P = 0.02). As no change in retinal arterial oxygen content occurred (P = 0.12), retinal oxygen extraction remained stable (2.2 ± 0.4 μL vs. 2.2 ± 0.4 μL O₂/min, P = 0.29). Conclusions: These results indicate that orally administered dronabinol increases TRBF in healthy subjects without altering retinal oxygen extraction. The drug may therefore be a candidate for improving perfusion in patients with ocular vascular disease.

β-Caryophyllene, A Natural Dietary CB2 Receptor Selective Cannabinoid can be a Candidate to Target the Trinity of Infection, Immunity, and Inflammation in COVID-19

Coronavirus disease (COVID-19), caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an ongoing pandemic and presents a public health emergency. It has affected millions of people and continues to affect more, despite tremendous social preventive measures. Identifying candidate drugs for the prevention and treatment of COVID-19 is crucial. The pathogenesis and the complications with advanced infection mainly involve an immune-inflammatory cascade. Therefore, therapeutic strategy relies on suppressing infectivity and inflammation, along with immune modulation. One of the most promising therapeutic targets for the modulation of immune-inflammatory responses is the endocannabinoid system, particularly the activation of cannabinoid type 2 receptors (CB2R), a G-protein coupled receptor which mediates the anti-inflammatory properties by modulating numerous signaling pathways. To pharmacologically activate the CB2 receptors, a naturally occurring cannabinoid ligand, beta-caryophyllene (BCP), received attention due to its potent anti-inflammatory, antiviral, and immunomodulatory properties. BCP is recognized as a full selective functional agonist on CB2 receptors and produces therapeutic effects by activating CB2 and the nuclear receptors, peroxisome proliferator-activated receptors (PPARs). BCP is regarded as the first dietary cannabinoid with abundant presence across cannabis and non-cannabis plants, including spices and other edible plants. BCP showed tissue protective properties and favorably modulates numerous signaling pathways and inhibits inflammatory mediators, including cytokines, chemokines, adhesion molecules, prostanoids, and eicosanoids. Based on its pharmacological properties, molecular mechanisms, and the therapeutic potential of BCP as an immunomodulator, anti-inflammatory, organ-protective, and antiviral, we hypothesize that BCP could be a promising therapeutic and/or preventive candidate to target the triad of infection, immunity, and inflammation in COVID-19. In line with numerous studies that proposed the potential of cannabinoids in COVID-19, BCP may be a novel candidate compound for pharmaceutical and nutraceutical development due to its unique functional receptor selectivity, wide availability and accessibility, dietary bioavailability, nonpsychoactivity, and negligible toxicity along with druggable properties, including favorable pharmacokinetic and physicochemical properties. Based on reasonable pharmacological mechanisms and therapeutic properties, we speculate that BCP has potential to be investigated against COVID-19 and will inspire further preclinical and clinical studies.

The Dual Role of Platelets in the Cardiovascular Risk of Chronic Inflammation

Patients with chronic inflammatory diseases often exhibit cardiovascular risk. This risk is associated with the systemic inflammation that persists in these patients, causing a sustained endothelial activation. Different mechanisms have been considered responsible for this systemic inflammation, among which activated platelets have been regarded as a major player. However, in recent years, the role of platelets has become controversial. Not only can this subcellular component release pro- and anti-inflammatory mediators, but it can also bind to different subsets of circulating lymphocytes, monocytes and neutrophils modulating their function in either direction. How platelets exert this dual role is not yet fully understood.

Cannabidiol (CBD) Alters the Functionality of Neutrophils (PMN). Implications in the Refractory Epilepsy Treatment

Cannabidiol (CBD), a lipophilic cannabinoid compound without psychoactive effects, has emerged as adjuvant of anti-epileptic drugs (AEDs) in the treatment of refractory epilepsy (RE), decreasing the severity and/or frequency of seizures. CBD is considered a multitarget drug that could act throughout the canonical endocannabinoid receptors (CB1-CB2) or multiple non-canonical pathways. Despite the fact that the CBD mechanism in RE is still unknown, experiments carried out in our laboratory showed that CBD has an inhibitory role on P-glycoprotein excretory function, highly related to RE. Since CB2 is expressed mainly in the immune cells, we hypothesized that CBD treatment could alter the activity of polymorphonuclear neutrophils (PMNs) in a similar way that it does with microglia/macrophages and others circulating leukocytes. In vitro, CBD induced PMN cytoplasmatic vacuolization and proapoptotic nuclear condensation, associated with a significantly decreased viability in a concentration-dependent manner, while low CBD concentration decreased PMN viability in a time-dependent manner. At a functional level, CBD reduced the chemotaxis and oxygen consumption of PMNs related with superoxide anion production, while the singlet oxygen level was increased suggesting oxidative stress damage. These results are in line with the well-known CBD anti-inflammatory effect and support a potential immunosuppressor role on PMNs that could promote an eventual defenseless state during chronic treatment with CBD in RE.

Can Echinacea be a potential candidate to target immunity, inflammation, and infection - The trinity of coronavirus disease 2019

Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an ongoing public health emergency. The pathogenesis and complications advanced with infection mainly involve immune-inflammatory cascade. Therefore, the therapeutic strategy relies on immune modulation, reducing infectivity and inflammation. Given the interplay of infection and immune-inflammatory axis, the natural products received attention for preventive and therapeutic usage in COVID-19 due to their potent antiviral and anti-immunomodulatory activities. Recently, Echinacea preparations, particularly E. purpurea, have been suggested to be an important antiviral agent to be useful in COVID-19 by modulating virus entry, internalization and replication. In principle, the immune response and the resultant inflammatory process are important for the elimination of the infection, but may have a significant impact on SARS-CoV-2 pathogenesis and may play a role in the clinical spectrum of COVID-19. Considering the pharmacological effects, therapeutic potential, and molecular mechanisms of Echinacea, we hypothesize that it could be a reasonably possible candidate for targeting infection, immunity, and inflammation in COVID-19 with recent recognition of cannabinoid-2 (CB2) receptors and peroxisome proliferator-activated receptor gamma (PPARγ) mediated mechanisms of bioactive components that make them notable immunomodulatory, anti-inflammatory and antiviral agent. The plausible reason for our hypothesis is that the presence of numerous bioactive agents in different parts of plants that may synergistically exert polypharmacological actions in regulating immune-inflammatory axis in COVID-19. Our proposition is to scientifically contemplate the therapeutic perspective and prospect of Echinacea on infection, immunity, and inflammation with a potential in COVID-19 to limit the severity and progression of the disease. Based on the clinical usage for respiratory infections, and relative safety in humans, further studies for the evidence-based approach to COVID-19 are needed. We do hope that Echinacea could be a candidate agent for immunomodulation in the prevention and treatment of COVID-19.

Targeting the endocannabinoid system: a predictive, preventive, and personalized medicine-directed approach to the management of brain pathologies

Cannabis-inspired medical products are garnering increasing attention from the scientific community, general public, and health policy makers. A plethora of scientific literature demonstrates intricate engagement of the endocannabinoid system with human immunology, psychology, developmental processes, neuronal plasticity, signal transduction, and metabolic regulation. Despite the therapeutic potential, the adverse psychoactive effects and historical stigma, cannabinoids have limited widespread clinical application. Therefore, it is plausible to weigh carefully the beneficial effects of cannabinoids against the potential adverse impacts for every individual. This is where the concept of "personalized medicine" as a promising approach for disease prediction and prevention may take into the account. The goal of this review is to provide an outline of the endocannabinoid system, including endocannabinoid metabolizing pathways, and will progress to a more in-depth discussion of the therapeutic interventions by endocannabinoids in various neurological disorders.

Potential for endocannabinoid system modulation in ocular pain and inflammation: filling the gaps in current pharmacological options

Challenges in the management of ocular pain are an underappreciated topic. Currently available therapeutics lack both efficacy and clear guidelines for their use, with many also possessing unacceptable side effects. Promising novel agents would offer analgesic, anti-inflammatory, and possibly neuroprotective actions; have favorable ocular safety profiles; and show potential in managing neuropathic pain. Growing evidence supports a link between the endocannabinoid system (ECS) and a range of physiological and disease processes, notably those involving inflammation and pain. Both preclinical and clinical data suggest analgesic and anti-inflammatory actions of cannabinoids and ECS-modifying drugs in chronic pain conditions, including those of neuropathic origin. This review will examine existing evidence for the anatomical and physiological basis of ocular pain, specifically, ocular surface disease and the development of chronic ocular pain. The mechanism of action, efficacy, and limitations of currently available treatments will be discussed, and current knowledge related to ECS-modulation of ocular pain and inflammatory disease will be summarized. A perspective will be provided on the future directions of ECS research in terms of developing cannabinoid therapeutics for ocular pain.

Revisiting cannabinoid receptor 2 expression and function in murine retina

The cannabinoid receptor CB2 plays a significant role in the regulation of immune function whereas neuronal expression remains a subject of contention. Multiple studies have described CB2 in retina and a recent study showed that CB2 deletion altered retinal visual processing. We revisited CB2 expression using immunohistochemistry and a recently developed CB2-eGFP reporter mouse. We examined the consequence of acute vs. prolonged CB2 deactivation on the electroretinogram (ERG) responses. We also examined lipidomics in CB2 knockout mice and potential changes in microglia using Scholl analysis. Consistent with a published report, in CB2 receptor knockout mice see an increased ERG scotopic a-wave, as well as stronger responses in dark adapted cone-driven ON bipolar cells and, to a lesser extent cone-driven ON bipolar cells early in light adaptation. Significantly, however, acute block with CB2 antagonist, AM630, did not mimic the results observed in the CB2 knockout mice whereas chronic (7 days) block did. Immunohistochemical studies show no CB2 in retina under non-pathological conditions, even with published antibodies. Retinal CB2-eGFP reporter signal is minimal under baseline conditions but upregulated by intraocular injection of either LPS or carrageenan. CB2 knockout mice see modest declines in a broad spectrum of cannabinoid-related lipids. The numbers and morphology of microglia were unaltered. In summary minimal CB2 expression is seen in healthy retina. CB2 appears to be upregulated under pathological conditions. Previously reported functional consequences of CB2 deletion are an adaptive response to prolonged blockade of these receptors. CB2 therefore impacts retinal signaling but perhaps in an indirect, potentially extra-ocular fashion.

The Cannabinoids Δ8THC, CBD, and HU-308 Act via Distinct Receptors to Reduce Corneal Pain and Inflammation

Background and Purpose: Corneal injury can result in dysfunction of corneal nociceptive signaling and corneal sensitization. Activation of the endocannabinoid system has been reported to be analgesic and anti-inflammatory. The purpose of this research was to investigate the antinociceptive and anti-inflammatory effects of cannabinoids with reported actions at cannabinoid 1 (CB₁R) and cannabinoid 2 (CB₂R) receptors and/or noncannabinoid receptors in an experimental model of corneal hyperalgesia.

Methods: Corneal hyperalgesia (increased pain response) was generated using chemical cauterization of the corneal epithelium in wild-type (WT) and CB₂R knockout (CB₂R^−/−) mice. Cauterized eyes were treated topically with the phytocannabinoids Δ⁸-tetrahydrocannabinol (Δ⁸THC) or cannabidiol (CBD), or the CBD derivative HU-308, in the presence or absence of the CB₁R antagonist AM251 (2.0 mg/kg i.p.), or the 5-HT_1A receptor antagonist WAY100635 (1 mg/kg i.p.). Behavioral pain responses to a topical capsaicin challenge at 6 h postinjury were quantified from video recordings. Mice were euthanized at 6 and 12 h postcorneal injury for immunohistochemical analysis to quantify corneal neutrophil infiltration.

Results: Corneal cauterization resulted in hyperalgesia to capsaicin at 6 h postinjury compared to sham control eyes. Neutrophil infiltration, indicative of inflammation, was apparent at 6 and 12 h postinjury in WT mice. Application of Δ⁸THC, CBD, and HU-308 reduced the pain score and neutrophil infiltration in WT mice. The antinociceptive and anti-inflammatory actions of Δ⁸THC, but not CBD, were blocked by the CB₁R antagonist AM251, but were still apparent, for both cannabinoids, in CB₂R^−/− mice. However, the antinociceptive and anti-inflammatory actions of HU-308 were absent in the CB₂R^−/− mice. The antinociceptive and anti-inflammatory effects of CBD were blocked by the 5-HT_1A antagonist WAY100635.

Conclusion: Topical cannabinoids reduce corneal hyperalgesia and inflammation. The antinociceptive and anti-inflammatory effects of Δ⁸THC are mediated primarily via CB₁R, whereas that of the cannabinoids CBD and HU-308, involve activation of 5-HT_1A receptors and CB₂Rs, respectively. Cannabinoids could be a novel clinical therapy for corneal pain and inflammation resulting from ocular surface injury.

Neuroprotection by (endo)Cannabinoids in Glaucoma and Retinal Neurodegenerative Diseases

BACKGROUND

Emerging neuroprotective strategies are being explored to preserve the retina from degeneration, that occurs in eye pathologies like glaucoma, diabetic retinopathy, age-related macular degeneration, and retinitis pigmentosa. Incidentally, neuroprotection of retina is a defending mechanism designed to prevent or delay neuronal cell death, and to maintain neural function following an initial insult, thus avoiding loss of vision.

METHODS

Numerous studies have investigated potential neuroprotective properties of plant-derived phytocannabinoids, as well as of their endogenous counterparts collectively termed endocannabinoids (eCBs), in several degenerative diseases of the retina. eCBs are a group of neuromodulators that, mainly by activating G protein-coupled type-1 and type-2 cannabinoid (CB1 and CB2) receptors, trigger multiple signal transduction cascades that modulate central and peripheral cell functions. A fine balance between biosynthetic and degrading enzymes that control the right concentration of eCBs has been shown to provide neuroprotection in traumatic, ischemic, inflammatory and neurotoxic damage of the brain.

RESULTS

Since the existence of eCBs and their binding receptors was documented in the retina of numerous species (from fishes to primates), their involvement in the visual processing has been demonstrated, more recently with a focus on retinal neurodegeneration and neuroprotection.

CONCLUSION

The aim of this review is to present a modern view of the endocannabinoid system, in order to discuss in a better perspective available data from preclinical studies on the use of eCBs as new neuroprotective agents, potentially useful to prevent glaucoma and retinal neurodegenerative diseases.

Cannabinoid Receptor 2 Modulates Neutrophil Recruitment in a Murine Model of Endotoxemia

The endocannabinoid system consists of endogenous lipid mediators and cannabinoid receptors (CB) 1 and 2. It has previously been demonstrated that activation of the leukocyte-expressed CB₂ has anti-inflammatory effects in vivo. Here, we report its role under baseline conditions and in a model of low-dose endotoxemia by comparing CB₂ knockout to littermate control mice. CB₂-deficient mice displayed significantly more neutrophils and fewer monocytes in the bone marrow under steady state. In initial validation experiments, administration of 1 mg/kg LPS to male C57BL/6J mice was shown to transiently upregulate systemic proinflammatory mediators (peaked at 2 hours) and mobilise bone marrow neutrophils and monocytes into circulation. In CB₂ knockout mice, the level of the metalloproteinase MMP-9 was significantly elevated by 2 hours and we also observed augmented recruitment of neutrophils to the spleen in addition to increased levels of Ccl2, Ccl3, Cxcl10, and Il6. Collectively, our data show that the absence of CB₂ receptor increases the levels of innate immune cell populations in the bone marrow under steady state. Furthermore, during an acute systemic inflammatory insult, we observe a highly reproducible and site-specific increase in neutrophil recruitment and proinflammatory chemokine expression in the spleen of CB₂ knockout mice.

Cannabinoids in the Cardiovascular System

Cannabinoids are known to modulate cardiovascular functions including heart rate, vascular tone, and blood pressure in humans and animal models. Essential components of the endocannabinoid system, namely, the production, degradation, and signaling pathways of endocannabinoids have been described not only in the central and peripheral nervous system but also in myocardium, vasculature, platelets, and immune cells. The mechanisms of cardiovascular responses to endocannabinoids are often complex and may involve cannabinoid CB₁ and CB₂ receptors or non-CB_1/2 receptor targets. Preclinical and some clinical studies have suggested that targeting the endocannabinoid system can improve cardiovascular functions in a number of pathophysiological conditions, including hypertension, metabolic syndrome, sepsis, and atherosclerosis. In this chapter, we summarize the local and systemic cardiovascular effects of cannabinoids and highlight our current knowledge regarding the therapeutic potential of endocannabinoid signaling and modulation.

Turning Down the Thermostat: Modulating the Endocannabinoid System in Ocular Inflammation and Pain

The endocannabinoid system (ECS) has emerged as an important regulator of both physiological and pathological processes. Notably, this endogenous system plays a key role in the modulation of pain and inflammation in a number of tissues. The components of the ECS, including endocannabinoids, their cognate enzymes and cannabinoid receptors, are localized in the eye, and evidence indicates that ECS modulation plays a role in ocular disease states. Of these diseases, ocular inflammation presents a significant medical problem, given that current clinical treatments can be ineffective or are associated with intolerable side-effects. Furthermore, a prominent comorbidity of ocular inflammation is pain, including neuropathic pain, for which therapeutic options remain limited. Recent evidence supports the use of drugs targeting the ECS for the treatment of ocular inflammation and pain in animal models; however, the potential for therapeutic use of cannabinoid drugs in the eye has not been thoroughly investigated at this time. This review will highlight evidence from experimental studies identifying components of the ocular ECS and discuss the functional role of the ECS during different ocular inflammatory disease states, including uveitis and corneal keratitis. Candidate ECS targeted therapies will be discussed, drawing on experimental results obtained from both ocular and non-ocular tissue(s), together with their potential application for the treatment of ocular inflammation and pain.

RCP induces Slug expression and cancer cell invasion by stabilizing β1 integrin

Rab coupling protein (RCP)-induced tumor cell migration has been implicated in tumor pathophysiology and patient outcomes. In the present study, we demonstrate that RCP stabilizes β1 integrin leading to increased β1 integrin levels and activation of a signaling cascade culminating in Slug induction, epithelial-to-mesenchymal transition and increased invasion. Ectopic expression of RCP induced Slug expression. Silencing β1 integrin efficiently inhibited RCP-induced Slug expression and subsequent cancer cell invasion. Conversely, ectopic expression of β1 integrin was sufficient to induce Slug expression. Pharmacological inhibition of integrin linked kinase (ILK), EGFR and NF-κB, as well as transfection of a dominant-negative mutant of Ras (RasN17), significantly inhibited RCP-induced Slug expression and cancer cell invasion. Strikingly, ectopic expression of RCP was sufficient to enhance metastasis of ovarian cancer cells to the lung. Collectively, we demonstrate a mechanism by which RCP promotes cancer cell aggressiveness through sequential β1 integrin stabilization, activation of an ILK/EGFR/Ras/NF-κB signaling cascade and subsequent Slug expression.