Cannabidiol-induced apoptosis in murine microglial cells through lipid raft

Exploring the Possible Role of Cannabinoids in Managing Post-cardiac Surgery Complications: A Narrative Review of Preclinical Evidence and a Call for Future Research Directions

ABSTRACT

Open-heart surgery with cardiopulmonary bypass often leads to complications including pain, systemic inflammation, and organ damage. Traditionally managed with opioids, these pain relief methods bring potential long-term risks, prompting the exploration of alternative treatments. The legalization of cannabis in various regions has reignited interest in cannabinoids, such as cannabidiol, known for their anti-inflammatory, analgesic, and neuroprotective properties. Historical and ongoing research acknowledges the endocannabinoid system's crucial role in managing physiological processes, suggesting that cannabinoids could offer therapeutic benefits in postsurgical recovery. Specifically, cannabidiol has shown promise in managing pain, moderating immune responses, and mitigating ischemia/reperfusion injury, underscoring its potential in postoperative care. However, the translation of these findings into clinical practice faces challenges, highlighting the need for extensive research to establish effective, safe cannabinoid-based therapies for patients undergoing open-heart surgery. This narrative review advocates for a balanced approach, considering both the therapeutic potential of cannabinoids and the complexities of their integration into clinical settings.

Immunomodulatory effects of cannabinoids against viral infections: a review of its potential use in SARS-CoV2 infection

The COVID-19 pandemic is a global health crisis affecting millions of people worldwide. Along with vaccine development, there is also a priority to discover new drugs and treatments. One approach involves modulating the immune system to manage inflammation and cytokine storms. Patients with a high severity of complications exhibit a high level of inflammatory cytokines, particularly IL-6, in the airways and other infected tissues. Several studies have reported the function of the endocannabinoid system in regulating inflammation and different immune responses. Cannabinoids are a class of natural chemicals found in the Cannabis plant. Recently, the anti-inflammatory properties of cannabinoids and their mediatory immunosuppression mechanisms through the endocannabinoid system have engrossed scientists in the health field for infectious conditions. Research suggests that the immune system can regulate cytokine activation through cannabinoid receptors, particularly with Cannabidiol (CBD), the second most prevalent compound in cannabis. While CBD has been deemed safe by the World Health Organization and shows no signs of abuse potential, excessive CBD use may lead to respiratory depression. CBD shows promise in reducing immune cell recruitment and cytokine storms in organs affected by SARS-CoV2. However, before clinical use, it's crucial to evaluate cannabinoid-based medications' active ingredient concentrations and potential interactions with other drugs, along with associated side effects. Indication-based dosing, consistent formulations, and ensuring purity and potency are essential. This review highlights cannabinoids' effects on COVID-19 management and prognosis, drawing from preclinical and clinical studies.

Informing the Cannabis Conjecture: From Life's Beginnings to Mitochondria, Membranes and the Electrome-A Review

Before the late 1980s, ideas around how the lipophilic phytocannabinoids might be working involved membranes and bioenergetics as these disciplines were "in vogue". However, as interest in genetics and pharmacology grew, interest in mitochondria (and membranes) waned. The discovery of the cognate receptor for tetrahydrocannabinol (THC) led to the classification of the endocannabinoid system (ECS) and the conjecture that phytocannabinoids might be "working" through this system. However, the how and the "why" they might be beneficial, especially for compounds like CBD, remains unclear. Given the centrality of membranes and mitochondria in complex organisms, and their evolutionary heritage from the beginnings of life, revisiting phytocannabinoid action in this light could be enlightening. For example, life can be described as a self-organising and replicating far from equilibrium dissipating system, which is defined by the movement of charge across a membrane. Hence the building evidence, at least in animals, that THC and CBD modulate mitochondrial function could be highly informative. In this paper, we offer a unique perspective to the question, why and how do compounds like CBD potentially work as medicines in so many different conditions? The answer, we suggest, is that they can modulate membrane fluidity in a number of ways and thus dissipation and engender homeostasis, particularly under stress. To understand this, we need to embrace origins of life theories, the role of mitochondria in plants and explanations of disease and ageing from an adaptive thermodynamic perspective, as well as quantum mechanics.

Effects of Cannabidiol on Innate Immunity: Experimental Evidence and Clinical Relevance

Cannabidiol (CBD) is the main non-psychotropic cannabinoid derived from cannabis (Cannabis sativa L., fam. Cannabaceae). CBD has received approval by the Food and Drug Administration (FDA) and European Medicines Agency (EMA) for the treatment of seizures associated with Lennox-Gastaut syndrome or Dravet syndrome. However, CBD also has prominent anti-inflammatory and immunomodulatory effects; evidence exists that it could be beneficial in chronic inflammation, and even in acute inflammatory conditions, such as those due to SARS-CoV-2 infection. In this work, we review available evidence concerning CBD's effects on the modulation of innate immunity. Despite the lack so far of clinical studies, extensive preclinical evidence in different models, including mice, rats, guinea pigs, and even ex vivo experiments on cells from human healthy subjects, shows that CBD exerts a wide range of inhibitory effects by decreasing cytokine production and tissue infiltration, and acting on a variety of other inflammation-related functions in several innate immune cells. Clinical studies are now warranted to establish the therapeutic role of CBD in diseases with a strong inflammatory component, such as multiple sclerosis and other autoimmune diseases, cancer, asthma, and cardiovascular diseases.

Cytotoxic Effects of Cannabidiol on Neonatal Rat Cortical Neurons and Astrocytes: Potential Danger to Brain Development

The influence of cannabidiol (CBD) on brain development is inadequately understood. Since CBD is considered a non-intoxicating drug, it has attracted great interest concerning its potential medical applicability, including in pregnant women and children. Here, we elucidated the response of perinatal rat cortical neurons and astrocytes to CBD at submicromolar (0.1, 0.5, 1, 5 µM) concentrations attainable in humans. The effect of CBD was concentration- and time-dependent and cell-specific. In neurons, 0.1 µM CBD induced an early and transient change in mitochondrial membrane potential (ΔΨm), ATP depletion, and caspase-8 activation, followed by rapid ATP recovery and progressive activation of caspase-9 and caspase-3/7, resulting in early apoptotic cell death with reduction and shortening of dendrites, cell shrinkage, and chromatin condensation. The decrease in neuronal viability, ATP depletion, and caspase activation due to CBD exposure was prevented by transient receptor potential vanilloid 1 (TRPV1) antagonist. In astrocytes, 0.5 µM CBD caused an immediate short-term dysregulation of ΔΨm, followed by ATP depletion with transient activation of caspase-8 and progressive activation of caspase-9 and caspase-3/7, leading to early apoptosis and subsequent necroptosis. In astrocytes, both TRPV1 and cannabinoid receptor 1 (CB₁) antagonists protected viability and prevented apoptosis. Given that CBD is a non-intoxicating drug, our results clearly show that this is not the case during critical periods of brain development when it can significantly interfere with the endogenous cannabinoid system.

Hemp in Animal Diets—Cannabidiol

In recent years, interest in hemp use has grown owing to its chemical and medicinal properties. Several parts of this plant, such as seeds, leaves, flowers, and stems are used in medicine, industry, and environmental preservation. Although there were legal restrictions on hemp exploitation in some countries due to the trace presence of THC as a psychoactive element, many countries have legalized it in recent years. Cannabidiol or CBD is a non-psychoactive phytocannabinoid that can activate the endocannabinoid system and its receptors in the central and peripheral nervous system in bodies of different species. Cannabidiol has anti-inflammatory, antioxidative, analgesic, and anti-depressant effects. This review investigates various aspects of cannabidiol use and its potential in animals and humans.

In Vitro Studies on Therapeutic Effects of Cannabidiol in Neural Cells: Neurons, Glia, and Neural Stem Cells

(‒)-Cannabidiol (CBD) is one of the major phytocannabinoids extracted from the Cannabis genus. Its non-psychoactiveness and therapeutic potential, partly along with some anecdotal—if not scientific or clinical—evidence on the prevention and treatment of neurological diseases, have led researchers to investigate the biochemical actions of CBD on neural cells. This review summarizes the previously reported mechanistic studies of the CBD actions on primary neural cells at the in vitro cell-culture level. The neural cells are classified into neurons, microglia, astrocytes, oligodendrocytes, and neural stem cells, and the CBD effects on each cell type are described. After brief introduction on CBD and in vitro studies of CBD actions on neural cells, the neuroprotective capability of CBD on primary neurons with the suggested operating actions is discussed, followed by the reported CBD actions on glia and the CBD-induced regeneration from neural stem cells. A summary section gives a general overview of the biochemical actions of CBD on neural cells, with a future perspective. This review will provide a basic and fundamental, but crucial, insight on the mechanistic understanding of CBD actions on neural cells in the brain, at the molecular level, and the therapeutic potential of CBD in the prevention and treatment of neurological diseases, although to date, there seem to have been relatively limited research activities and reports on the cell culture-level, in vitro studies of CBD effects on primary neural cells.

The GPR18 Agonist PSB-KD-107 Exerts Endothelium-Dependent Vasorelaxant Effects

GPR18 is an orphan GPCR that is activated by the cannabinoid tetrahydrocannabinol (THC). Emerging evidence indicates its involvement in the control of cardiovascular functions, including heart rate, contractility, vascular tone, as well as blood pressure. Therefore, we investigated the effects of selective GPR18 receptor ligands, namely PSB-KD-107 (agonist) and PSB-CB-92 (antagonist), on blood pressure, electrocardiogram (ECG), and vascular dilatation in vitro and in vivo, as well as their anti-oxidative potential in in vitro ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picryl-hydrazyl-hydrate free radical (DPPH) assays. Our results clearly show that PSB-KD-107 dilates blood vessels. This effect is related to its activation of GPR18 as it can be blocked by the GPR18 antagonist PSB-CB-92. Moreover, our finding confirms the presence of GPR18 in blood vessels. The mechanism of the vasorelaxant activity of PSB-KD-107 is mainly related to endothelial nitric oxide generation; however, we cannot exclude additional nitric oxide-independent mechanisms or a direct influence on K⁺ channels. PSB-KD-107 may affect blood pressure and heart function after a single administration; however, this effect was no longer observed after repeated administrations once daily for eight days. PSB-KD-107 does not affect platelet aggregation-an important feature considering the safety of its administration. PSB-KD-107 also shows a significant anti-oxidant effect and further studies of its antioxidant activity in vivo are justified.

Neuroprotective Effect of Cannabidiol Against Hydrogen Peroxide in Hippocampal Neuron Culture

Introduction: Reports on the neurotoxic and neuroprotective effects of cannabidiol (CBD) have not been in complete accord, showing different and somewhat contradictory results depending upon the brain cell types and experimental conditions employed. This work systematically examines the neuroprotective capability of CBD against oxidative stress (i.e., hydrogen peroxide [H2O2]) as well as its toxicity profile in the in vitro culture platform of primary hippocampal neurons. Materials and Methods: The low cell-density (100 neurons per mm2) culture was used for analyzing the viability and morphology of neurons at a single-cell level with a confocal laser-scanning microscope (CLSM). Primary neurons were obtained from the hippocampal tissues of embryonic day-18 (E18) Sprague-Dawley rat pups and treated with CBD (0.1-100 μM) and/or H2O2 (0.1-50 μM) at 1 DIV (days in vitro). Results: The lethal concentration 50 (LC50) value (the concentration causing 50% cell death) of CBD was calculated to be 9.85 μM after 24 h of incubation, and that of H2O2 was 2.46 μM under the same conditions. The neuroprotection ratio of CBD against H2O2 ([H2O2]=10 μM) was 2.40 with 5 μM of CBD, increasing the cell viability to 57% from 24%. The CLSM analysis suggested that the cell-death mechanisms were different for CBD and H2O2, and CBD did not completely rescue the morphological alterations of primary hippocampal neurons caused by H2O2, such as neurite degeneration, at least in the in vitro neuron culture. Conclusion: Although CBD showed both neurotoxic and neuroprotective effects on hippocampal neurons in the in vitro setting, the use of low-concentrated (i.e., 5 μM) CBD, not causing toxic effects on the neurons, significantly rescued the neurons from the oxidative stress (H2O2), confirming its neuroprotection capability.

Immune Responses Regulated by Cannabidiol

Introduction: Cannabidiol (CBD) as Epidiolex^® (GW Pharmaceuticals) was recently approved by the U.S. Food and Drug Administration (FDA) to treat rare forms of epilepsy in patients 2 years of age and older. Together with the increased societal acceptance of recreational cannabis and CBD oil for putative medical use in many states, the exposure to CBD is increasing, even though all of its biological effects are not understood. Once such example is the ability of CBD to be anti-inflammatory and immune suppressive, so the purpose of this review is to summarize effects and mechanisms of CBD in the immune system. It includes a consideration of reports identifying receptors through which CBD acts, since the “CBD receptor,” if a single one exists, has not been definitively identified for the myriad immune system effects. The review then provides a summary of in vivo and in vitro effects in the immune system, in autoimmune models, with a focus on experimental autoimmune encephalomyelitis, and ends with identification of knowledge gaps.

Conclusion: Overall, the data overwhelmingly support the notion that CBD is immune suppressive and that the mechanisms involve direct suppression of activation of various immune cell types, induction of apoptosis, and promotion of regulatory cells, which, in turn, control other immune cell targets.

Antioxidative and Anti-Inflammatory Properties of Cannabidiol

Cannabidiol (CBD) is one of the main pharmacologically active phytocannabinoids of Cannabis sativa L. CBD is non-psychoactive but exerts a number of beneficial pharmacological effects, including anti-inflammatory and antioxidant properties. The chemistry and pharmacology of CBD, as well as various molecular targets, including cannabinoid receptors and other components of the endocannabinoid system with which it interacts, have been extensively studied. In addition, preclinical and clinical studies have contributed to our understanding of the therapeutic potential of CBD for many diseases, including diseases associated with oxidative stress. Here, we review the main biological effects of CBD, and its synthetic derivatives, focusing on the cellular, antioxidant, and anti-inflammatory properties of CBD.

Cannabidiol differentially regulates basal and LPS-induced inflammatory responses in macrophages, lung epithelial cells, and fibroblasts

INTRODUCTION

Cannabidiol (CBD) containing products are available in a plethora of flavors in oral, sublingual, and inhalable forms. Immunotoxicological effects of CBD containing liquids were assessed by hypothesizing that CBD regulates oxidative stress and lipopolysaccharide (LPS) induced inflammatory responses in macrophages, epithelial cells, and fibroblasts.

METHODS

Epithelial cells (BEAS-2B and NHBE), macrophages (U937), and lung fibroblast cells (HFL-1) were treated with varying CBD concentrations or exposed to CBD aerosols. Generated reactive oxygen species (ROS) and inflammatory mediators were measured. Furthermore, monocytes and epithelial cells were stimulated with LPS in combination with CBD or dexamethasone to understand the anti-inflammatory effects of CBD.

RESULTS

CBD showed differential effects on IL-8 and MCP-1, and acellular and cellular ROS levels. CBD significantly attenuated LPS-induced NF-κB activity, IL-8, and MCP-1 release from macrophages. Cytokine array data depicted a differential cytokine response due to CBD. Inflammatory mediators, IL-8, serpin E1, CXCL1, IL-6, MIF, IFN-γ, MCP-1, RANTES, and TNF-α were induced, whereas MCP-1/CCL2, CCL5, eotaxin, and IL-2 were reduced. CBD and dexamethasone treatments reduced the IL-8 level induced by LPS when the cells were treated individually, but showed antagonistic effects when used in combination via MCPIP (monocytic chemotactic protein-induced protein).

CONCLUSION

CBD differentially regulated basal pro-inflammatory response and attenuated both LPS-induced cytokine release and NF-κB activity in monocytes, similar to dexamethasone. Thus, CBD has a differential inflammatory response and acts as an anti-inflammatory agent in pro-inflammatory conditions but acts as an antagonist with steroids, overriding the anti-inflammatory potential of steroids when used in combination.

DMH-CBD, a cannabidiol analog with reduced cytotoxicity, inhibits TNF production by targeting NF-kB activity dependent on A2A receptor

Cannabidiol (CBD) is a natural compound with psychoactive therapeutic properties well described. Conversely, the immunological effects of CBD are still poorly explored. In this study, the potential anti-inflammatory effects and underlying mechanisms of CBD and its analog Dimethyl-Heptyl-Cannabidiol (DMH-CBD) were investigated using RAW 264.7 macrophages. CBD and DMH-CBD suppressed LPS-induced TNF production and NF-kB activity in a concentration-dependent manner. Both compounds reduced the NF-kB activity in a μM concentration range: CBD (IC₅₀ = 15 μM) and DMH-CBD (IC₅₀ = 38 μM). However, the concentrations of CBD that mediated NF-kB inhibition were similar to those that cause cytotoxicity (LC₅₀ = 58 μM). Differently, DMH-CBD inhibited the NF-kB activation without cytotoxic effects at the same concentrations, although it provokes cytotoxicity at long-term exposure. The inhibitory action of the DMH-CBD on NF-kB activity was not related to the reduction in IkBα degradation or either p65 (NF-kB) translocation to the nucleus, although it decreased p38 MAP kinase phosphorylation. Additionally, 8-(3-Chlorostyryl) caffeine (CSC), an A_2A antagonist, reversed the effect of DMH-CBD on NF-kB activity in a concentration-dependent manner. Collectively, our results demonstrated that CBD reduces NF-kB activity at concentrations intimately associated with those that cause cell death, whereas DMH-CBD decreases NF-kB activity at non-toxic concentrations in an A_2A receptor dependent-manner.

Cannabidiol induced apoptosis in human monocytes through mitochondrial permeability transition pore-mediated ROS production

Cannabidiol (CBD) has been reported to induce apoptosis in immune cells through oxidative stress-related mechanisms. The objective of the present study was to investigate the cellular mechanisms for CBD-induced apoptosis and oxidative stress in human monocytes. Exposure of freshly isolated human monocytes to CBD induced apoptosis in a time- and concentration-dependent manner. Time-course analyses revealed the induction of intracellular reactive oxygen species (ROS) at 1-2 h post CBD (16 μM) exposure. By comparison, the CBD treatment rapidly elicited the depolarization of mitochondrial membrane potential (MMP) within 5 min, and the oxidation of cardiolipin, a major lipid component of the mitochondrial inner membrane, within 15 min. Moreover, CBD induced the release of cytochrome c (Cyt c) from mitochondria. Mechanistic studies revealed that CBD-induced ROS production and apoptosis were not associated with the alteration of mitochondrial superoxide dismutase activity, the electron leakage through mitochondrial respiratory chain, and Fe²⁺- and Ca²⁺-mediated mechanisms. In contrast, CBD-induced apoptosis and MMP depolarization were markedly attenuated by the mitochondrial permeability transition pore (MPTP) inhibitor cyclosporin A (CsA), but not the calcineurin inhibitor FK506. Furthermore, CsA prevented cardiolipin oxidation and the MPTP opening induced by CBD. The present study suggests that CBD acts on the mitochondria to elicit ROS generation and apoptosis through MPTP opening and provides critical insights into the cellular mechanisms for CBD-induced oxidative stress in apoptotic monocytes.

Cannabidiol effects on behaviour and immune gene expression in zebrafish (Danio rerio)

Various preparations and extracts of the plant Cannabis sativa (family cannabaceae) are used as herbal medicinal drugs against a series of disorders but the plant contains a wide series of pharmacologically active components which may confound evaluation of drug effects. In order to differentiate specific effects of the individual constituents on specific functions in the organism we advocate for controlled studies on specified constituents and their impact on the vertebrate organism. One of the dominating Cannabis constituents, delta(9)-tetrahydrocannabinol (THC), has previously been studied in depth whereas information on another main ingredient cannabidiol (CBD) is limited. We have performed a controlled study on CBD and its effect using an experimental zebrafish model. CDB treatment of zebrafish for 30 min affected mobility of the fish by decreasing swimming speed and swimming distance. In addition, out of 23 immune related genes studied it was shown that expression of two genes il1b and il17a/f2 were up-regulated and four genes, tgfba, ighm, cd4-1, and s100a10b were significantly down-regulated following CBD treatment. The study indicated that CBD affects motility and immunity of the vertebrate host.

Cannabinoids as Modulators of Cell Death: Clinical Applications and Future Directions

Endocannabinoids are bioactive lipids that modulate various physiological processes through G-protein-coupled receptors (CB1 and CB2) and other putative targets. By sharing the activation of the same receptors, some phytocannabinoids and a multitude of synthetic cannabinoids mimic the effects of endocannabinoids. In recent years, a growing interest has been dedicated to the study of cannabinoids properties for their analgesic, antioxidant, anti-inflammatory and neuroprotective effects. In addition to these well-recognized effects, various studies suggest that cannabinoids may affect cell survival, cell proliferation or cell death. These observations indicate that cannabinoids may play an important role in the regulation of cellular homeostasis and, thus, may contribute to tissue remodelling and cancer treatment. For a long time, the study of cannabinoid receptor signalling has been focused on the classical adenylyl cyclase/cyclic AMP/protein kinase A (PKA) pathway. However, this pathway does not totally explain the wide array of biological responses to cannabinoids. In addition, the diversity of receptors and signalling pathways that endocannabinoids modulate offers an interesting opportunity for the development of specific molecules to disturb selectively the endogenous system. Moreover, emerging evidences suggest that cannabinoids ability to limit cell proliferation and to induce tumour-selective cell death may offer a novel strategy in cancer treatment. This review describes the main properties of cannabinoids in cell death and attempts to clarify the different pathways triggered by these compounds that may help to understand the complexity of respective molecular mechanisms and explore the potential clinical benefit of cannabinoids use in cancer therapies.

Alternatively activated microglia and macrophages in the central nervous system

Macrophages are important players in the fight against viral, bacterial, fungal and parasitic infections. From a resting state they may undertake two activation pathways, the classical known as M1, or the alternative known as M2. M1 markers are mostly mediators of pro-inflammatory responses whereas M2 markers emerge for resolution and cleanup. Microglia exerts in the central nervous system (CNS) a function similar to that of macrophages in the periphery. Microglia activation and proliferation occurs in almost any single pathology affecting the CNS. Often microglia activation has been considered detrimental and drugs able to stop microglia activation were considered for the treatment of a variety of diseases. Cumulative evidence shows that microglia may undergo the alternative activation pathway, express M2-type markers and contribute to neuroprotection. This review focuses on details about the role of M2 microglia and in the approaches available for its identification. Approaches to drive the M2 phenotype and data on its potential in CNS diseases are also reviewed.

Marijuana use and brain immune mechanisms

The recreational smoking of marijuana, or Cannabis sativa, has become widespread, including among adolescents. Marijuana contains a class of compounds known as phytocannabinoids that include cannabidiol (CBD) and Δ(9)-tetrahydrocannabinol (THC). THC is the major psychoactive component in marijuana, but also exhibits immunosuppressive activity. CBD, while not psychotropic, also modulates immune function, but its mechanism of action appears to differ from that of THC. Since both compounds are highly lipophilic, they readily passage the blood-brain barrier and access the central nervous system. Since CBD is not psychotropic, it has been considered as a candidate therapeutic compound for ablating neuropathological processes characterized by hyperinflammation. However, an unresolved question centers around the impact of these compounds on immune-competent cells within the CNS in relation to susceptibility to infection. There are accumulating data indicating that THC inhibits the migratory capability of macrophage-like cells resident in the CNS, such as microglia, toward nodes of microbial invasion. Furthermore, phytocannabinoids have been reported to exert developmental and long-term effects on the immune system suggesting that exposure to these substances during an early stage in life has the potential to alter the fundamental neuroimmune response to select microbial agents in the adult.

Direct modulation of the outer mitochondrial membrane channel, voltage-dependent anion channel 1 (VDAC1) by cannabidiol: a novel mechanism for cannabinoid-induced cell death

Cannabidiol (CBD) is a non-psychoactive plant cannabinoid that inhibits cell proliferation and induces cell death of cancer cells and activated immune cells. It is not an agonist of the classical CB1/CB2 cannabinoid receptors and the mechanism by which it functions is unknown. Here, we studied the effects of CBD on various mitochondrial functions in BV-2 microglial cells. Our findings indicate that CBD treatment leads to a biphasic increase in intracellular calcium levels and to changes in mitochondrial function and morphology leading to cell death. Density gradient fractionation analysis by mass spectrometry and western blotting showed colocalization of CBD with protein markers of mitochondria. Single-channel recordings of the outer-mitochondrial membrane protein, the voltage-dependent anion channel 1 (VDAC1) functioning in cell energy, metabolic homeostasis and apoptosis revealed that CBD markedly decreases channel conductance. Finally, using microscale thermophoresis, we showed a direct interaction between purified fluorescently labeled VDAC1 and CBD. Thus, VDAC1 seems to serve as a novel mitochondrial target for CBD. The inhibition of VDAC1 by CBD may be responsible for the immunosuppressive and anticancer effects of CBD.

Microarray and pathway analysis reveal distinct mechanisms underlying cannabinoid-mediated modulation of LPS-induced activation of BV-2 microglial cells

Cannabinoids are known to exert immunosuppressive activities. However, the mechanisms which contribute to these effects are unknown. Using lipopolysaccharide (LPS) to activate BV-2 microglial cells, we examined how Δ⁹-tetrahydrocannabinol (THC), the major psychoactive component of marijuana, and cannabidiol (CBD) the non-psychoactive component, modulate the inflammatory response. Microarray analysis of genome-wide mRNA levels was performed using Illumina platform and the resulting expression patterns analyzed using the Ingenuity Pathway Analysis to identify functional subsets of genes, and the Ingenuity System Database to denote the gene networks regulated by CBD and THC. From the 5338 transcripts that were differentially expressed across treatments, 400 transcripts were found to be upregulated by LPS, 502 by CBD+LPS and 424 by THC+LPS, while 145 were downregulated by LPS, 297 by CBD+LPS and 149 by THC+LPS, by 2-fold or more (p≤0.005). Results clearly link the effects of CBD and THC to inflammatory signaling pathways and identify new cannabinoid targets in the MAPK pathway (Dusp1, Dusp8, Dusp2), cell cycle related (Cdkn2b, Gadd45a) as well as JAK/STAT regulatory molecules (Socs3, Cish, Stat1). The impact of CBD on LPS-stimulated gene expression was greater than that of THC. We attribute this difference to the fact that CBD highly upregulated several genes encoding negative regulators of both NFκB and AP-1 transcriptional activities, such as Trib3 and Dusp1 known to be modulated through Nrf2 activation. The CBD-specific expression profile reflected changes associated with oxidative stress and glutathione depletion via Trib3 and expression of ATF4 target genes. Furthermore, the CBD affected genes were shown to be controlled by nuclear factors usually involved in regulation of stress response and inflammation, mainly via Nrf2/Hmox1 axis and the Nrf2/ATF4-Trib3 pathway. These observations indicate that CBD, and less so THC, induce a cellular stress response and that this response underlies their high immunosuppressant activities.