Subcellular particles for characterization of host-parasite interactions.

Parasitic diseases remain a major global health problem for humans. Parasites employ a variety of strategies to invade and survive within their hosts and to manipulate host defense mechanisms, always in the pathogen's favor. Extracellular vesicles (EVs), membrane-bound nanospheres carrying a variety of bioactive compounds, were shown to be released by the parasites during all stages of the infection, enabling growth and expansion within the host and adaptation to frequently changing environmental stressors. In this review, we discuss how the use of existing nanotechnologies and high-resolution imaging tools assisted in revealing the role of EVs during parasitic infections, enabling the quantitation, visualization, and detailed characterization of EVs. We discuss here the cases of malaria, Chagas disease and leishmaniasis as examples of parasitic neglected tropical diseases (NTDs). Unraveling the EVs' role in the NTD pathogenesis may enormously contribute to their early and reliable diagnostic, effective treatment, and prevention.

Suicide in bipolar disorder patients is associated with hippocampal microglia activation and reduction of lymphocytes-activation gene 3 (LAG3) microglial checkpoint expression.

BACKGROUND: Bipolar disorder (BD) is associated with marked functional impairments along with increased rate of suicide. Although there is ample evidence for the involvement of inflammatory processes and microglia activation in the pathophysiology of BD, the mechanisms that regulate these cells in BD patients, and particularly the role of microglia checkpoints, is still unclear. METHODS: Immunohistochemical analyses of hippocampal sections from post-mortem brains of 15 BD patients and 12 control subjects were used to assess microglia density, by staining the microglia-specific receptor P2RY12, and microglia activation, by staining the activation marker MHC II. Given recent findings on the involvement of LAG3, which interacts with MHC II and serves as a negative microglia checkpoint, in depression and electroconvulsive therapy, we assessed the levels of LAG3 expression and their correlations with microglia density and activation. RESULTS: There were no overall differences between BD patients and controls, but BD patients who committed suicide (N = 9) displayed a significant elevation in the overall microglia density and the density of MHC II-labeled microglia (but not other MHC II-labeled cells), compared with no suicide BD patients (N = 6) and controls. Furthermore, the percent of microglia expressing LAG3 was significantly reduced only in suicidal BD patients, with significant negative correlations between microglial LAG3 expression levels and the density of microglia, in general, and activated microglia, in particular. CONCLUSION: Suicidal BD patients exhibit microglia activation, which is possibly mediated by reduced LAG3 checkpoint expression, suggesting that anti-microglial therapeutics, including LAG3 modulators, may be beneficial for this subgroup of patients.

Biogenesis of extracellular vesicles in protozoan parasites: The ESCRT complex in the trafficking fast lane?

Extracellular vesicles (EVs) provide a central mechanism of cell-cell communication. While EVs are found in most organisms, their pathogenesis-promoting roles in parasites are of particular interest given the potential for medical insight and consequential therapeutic intervention. Yet, a key feature of EVs in human parasitic protozoa remains elusive: their mechanisms of biogenesis. Here, we survey the current knowledge on the biogenesis pathways of EVs secreted by the four main clades of human parasitic protozoa: apicomplexans, trypanosomatids, flagellates, and amoebae. In particular, we shine a light on findings pertaining to the Endosomal Sorting Complex Required for Transport (ESCRT) machinery, as in mammals it plays important roles in EV biogenesis. This review highlights the diversity in EV biogenesis in protozoa, as well as the related involvement of the ESCRT system in these unique organisms.

A Novel Anti-Inflammatory Formulation Comprising Celecoxib and Cannabidiol Exerts Antidepressant and Anxiolytic Effects.

Background: Ample research shows that anti-inflammatory drugs, particularly celecoxib, exert antidepressant effects, especially in patients with microglia activation. However, substantial cardiovascular adverse effects limit celecoxib's usefulness. Given that cannabidiol (CBD) exerts anti-inflammatory, microglia-suppressive, and antidepressant effects, we hypothesized that it may potentiate the therapeutic effects of celecoxib. Methods: The effects of celecoxib, CBD, and their combination were examined in murine models of antidepressant- and anxiolytic-like behavioral responsiveness, including the forced swim test (FST), elevated plus maze (EPM), lipopolysaccharide (LPS)-induced neuroinflammation, and chronic social defeat stress (CSDS), as well as in microglia cell cultures. Results: Acute administration of a combination of celecoxib plus CBD, at doses that had no effects by themselves (10 and 5 mg/kg, respectively), produced significant antidepressant- and anxiolytic-like effects in the FST and EPM, in male and female mice. In the LPS model, combinations of celecoxib (10 or 20 mg/kg) plus CBD (30 mg/kg) reversed the anxiety-like behavior in the open-field test (OFT) and anhedonia in the sucrose preference test (SPT), with minimal effects of celecoxib or CBD by themselves. In the CSDS paradigm, a combination of celecoxib plus CBD (each at 30 mg/kg) reversed the deficits in the OFT, EPM, social exploration, and SPT, whereas celecoxib or CBD by themselves had partial effects. In BV2 microglia cultures stimulated with LPS or α-synuclein, CBD markedly potentiated the suppressive effects of celecoxib over TNFα (tumor necrosis factor-α) and IL (interleukin)-1ß secretion. Conclusions: Combinations of celecoxib plus CBD produce efficacious antidepressant- and anxiolytic-like effects, which may depend on their synergistic microglia-suppressive effects.

Microglia and their LAG3 checkpoint underlie the antidepressant and neurogenesis-enhancing effects of electroconvulsive stimulation.

Despite evidence implicating microglia in the etiology and pathophysiology of major depression, there is paucity of information regarding the contribution of microglia-dependent molecular pathways to antidepressant procedures. In this study, we investigated the role of microglia in a mouse model of depression (chronic unpredictable stress-CUS) and its reversal by electroconvulsive stimulation (ECS), by examining the effects of microglia depletion with the colony stimulating factor-1 antagonist PLX5622. Microglia depletion did not change basal behavioral measures or the responsiveness to CUS, but it completely abrogated the therapeutic effects of ECS on depressive-like behavior and neurogenesis impairment. Treatment with the microglia inhibitor minocycline concurrently with ECS also diminished the antidepressant and pro-neurogenesis effects of ECS. Hippocampal RNA-Seq analysis revealed that ECS significantly increased the expression of genes related to neurogenesis and dopamine signaling, while reducing the expression of several immune checkpoint genes, particularly lymphocyte-activating gene-3 (Lag3), which was the only microglial transcript significantly altered by ECS. None of these molecular changes occurred in microglia-depleted mice. Immunohistochemical analyses showed that ECS reversed the CUS-induced changes in microglial morphology and elevation in microglial LAG3 receptor expression. Consistently, either acute or chronic systemic administration of a LAG3 monoclonal antibody, which readily penetrated into the brain parenchyma and was found to serve as a direct checkpoint blocker in BV2 microglia cultures, rapidly rescued the CUS-induced microglial alterations, depressive-like symptoms, and neurogenesis impairment. These findings suggest that brain microglial LAG3 represents a promising target for novel antidepressant therapeutics.

Cannabidiol Improves Cognitive Impairment and Reverses Cortical Transcriptional Changes Induced by Ketamine, in Schizophrenia-Like Model in Rats.

Cannabidiol (CBD), a non-psychotropic cannabinoid, demonstrates antipsychotic-like and procognitive activities in humans and in animal models of schizophrenia. The mechanisms of these beneficial effects of CBD are unknown. Here, we examined behavioral effects of CBD in a pharmacological model of schizophrenia-like cognitive deficits induced by repeated ketamine (KET) administration. In parallel, we assessed transcriptional changes behind CBD activities in the prefrontal cortex (PFC), the main brain area linked to schizophrenia-like pathologies. Male Sprague-Dawley rats were injected for 10 days with KET followed by 6 days of CBD. The cognitive performance was evaluated in the novel object recognition test followed by PFC dissections for next-generation sequencing (RNA-Seq) analysis and bioinformatics. We observed that KET-induced learning deficits were rescued by CBD (7.5 mg/kg). Similarly, CBD reversed transcriptional changes induced by KET. The majority of the genes affected by KET and KET-CBD were allocated to astroglial and microglial cells and associated with immune-like processes mediating synaptogenesis and neuronal plasticity. These genes include C1qc, C1qa, C1qb, C2, and C3 complement cascade elements, Irf8 factor and Gpr84, Gpr34, Cx3cr1, P2ry12, and P2ry6 receptors. The main pathway regulators predicted to be involved included TGFß1 and IFNγ. In addition, CBD itself upregulated oxytocin mRNA in the PFC. The present data suggest that KET induces cognitive deficits and transcriptional changes in the PFC and that both effects are sensitive to a reversal by CBD treatment.

miRNA expression profiles and molecular networks in resting and LPS-activated BV-2 microglia-Effect of cannabinoids.

Mammalian microRNAs (miRNAs) play a critical role in modulating the response of immune cells to stimuli. Cannabinoids are known to exert beneficial actions such as neuroprotection and immunosuppressive activities. However, the underlying mechanisms which contribute to these effects are not fully understood. We previously reported that the psychoactive cannabinoid Δ9-tetrahydrocannabinol (THC) and the non-psychoactive cannabidiol (CBD) differ in their anti-inflammatory signaling pathways. Using lipopolysaccharide (LPS) to stimulate BV-2 microglial cells, we examined the role of cannabinoids on the expression of miRNAs. Expression was analyzed by performing deep sequencing, followed by Ingenuity Pathway Analysis to describe networks and intracellular pathways. miRNA sequencing analysis revealed that 31 miRNAs were differentially modulated by LPS and by cannabinoids treatments. In addition, we found that at the concentration tested, CBD has a greater effect than THC on the expression of most of the studied miRNAs. The results clearly link the effects of both LPS and cannabinoids to inflammatory signaling pathways. LPS upregulated the expression of pro-inflammatory miRNAs associated to Toll-like receptor (TLR) and NF-κB signaling, including miR-21, miR-146a and miR-155, whereas CBD inhibited LPS-stimulated expression of miR-146a and miR-155. In addition, CBD upregulated miR-34a, known to be involved in several pathways including Rb/E2f cell cycle and Notch-Dll1 signaling. Our results show that both CBD and THC reduced the LPS-upregulated Notch ligand Dll1 expression. MiR-155 and miR-34a are considered to be redox sensitive miRNAs, which regulate Nrf2-driven gene expression. Accordingly, we found that Nrf2-mediated expression of redox-dependent genes defines a Mox-like phenotype in CBD treated BV-2 cells. In summary, we have identified a specific repertoire of miRNAs that are regulated by cannabinoids, in resting (surveillant) and in LPS-activated microglia. The modulated miRNAs and their target genes are controlled by TLR, Nrf2 and Notch cross-talk signaling and are involved in immune response, cell cycle regulation as well as cellular stress and redox homeostasis.

Modulation of Astrocyte Activity by Cannabidiol, a Nonpsychoactive Cannabinoid.

The astrocytes have gained in recent decades an enormous interest as a potential target for neurotherapies, due to their essential and pleiotropic roles in brain physiology and pathology. Their precise regulation is still far from understood, although several candidate molecules/systems arise as promising targets for astrocyte-mediated neuroregulation and/or neuroprotection. The cannabinoid system and its ligands have been shown to interact and affect activities of astrocytes. Cannabidiol (CBD) is the main non-psychotomimetic cannabinoid derived from Cannabis. CBD is devoid of direct CB1 and CB2 receptor activity, but exerts a number of important effects in the brain. Here, we attempt to sum up the current findings on the effects of CBD on astrocyte activity, and in this way on central nervous system (CNS) functions, across various tested models and neuropathologies. The collected data shows that increased astrocyte activity is suppressed in the presence of CBD in models of ischemia, Alzheimer-like and Multiple-Sclerosis-like neurodegenerations, sciatic nerve injury, epilepsy, and schizophrenia. Moreover, CBD has been shown to decrease proinflammatory functions and signaling in astrocytes.

Pathways and gene networks mediating the regulatory effects of cannabidiol, a nonpsychoactive cannabinoid, in autoimmune T cells.

BACKGROUND: Our previous studies showed that the non-psychoactive cannabinoid, cannabidiol (CBD), ameliorates the clinical symptoms in mouse myelin oligodendrocyte glycoprotein (MOG)35-55-induced experimental autoimmune encephalomyelitis model of multiple sclerosis (MS) as well as decreases the memory MOG35-55-specific T cell (TMOG) proliferation and cytokine secretion including IL-17, a key autoimmune factor. The mechanisms of these activities are currently poorly understood. METHODS: Herein, using microarray-based gene expression profiling, we describe gene networks and intracellular pathways involved in CBD-induced suppression of these activated memory TMOG cells. Encephalitogenic TMOG cells were stimulated with MOG35-55 in the presence of spleen-derived antigen presenting cells (APC) with or without CBD. mRNA of purified TMOG was then subjected to Illumina microarray analysis followed by ingenuity pathway analysis (IPA), weighted gene co-expression network analysis (WGCNA) and gene ontology (GO) elucidation of gene interactions. Results were validated using qPCR and ELISA assays. RESULTS: Gene profiling showed that the CBD treatment suppresses the transcription of a large number of proinflammatory genes in activated TMOG. These include cytokines (Xcl1, Il3, Il12a, Il1b), cytokine receptors (Cxcr1, Ifngr1), transcription factors (Ier3, Atf3, Nr4a3, Crem), and TNF superfamily signaling molecules (Tnfsf11, Tnfsf14, Tnfrsf9, Tnfrsf18). "IL-17 differentiation" and "IL-6 and IL-10-signaling" were identified among the top processes affected by CBD. CBD increases a number of IFN-dependent transcripts (Rgs16, Mx2, Rsad2, Irf4, Ifit2, Ephx1, Ets2) known to execute anti-proliferative activities in T cells. Interestingly, certain MOG35-55 up-regulated transcripts were maintained at high levels in the presence of CBD, including transcription factors (Egr2, Egr1, Tbx21), cytokines (Csf2, Tnf, Ifng), and chemokines (Ccl3, Ccl4, Cxcl10) suggesting that CBD may promote exhaustion of memory TMOG cells. In addition, CBD enhanced the transcription of T cell co-inhibitory molecules (Btla, Lag3, Trat1, and CD69) known to interfere with T/APC interactions. Furthermore, CBD enhanced the transcription of oxidative stress modulators with potent anti-inflammatory activity that are controlled by Nfe2l2/Nrf2 (Mt1, Mt2a, Slc30a1, Hmox1). CONCLUSIONS: Microarray-based gene expression profiling demonstrated that CBD exerts its immunoregulatory effects in activated memory TMOG cells via (a) suppressing proinflammatory Th17-related transcription, (b) by promoting T cell exhaustion/tolerance, (c) enhancing IFN-dependent anti-proliferative program, (d) hampering antigen presentation, and (d) inducing antioxidant milieu resolving inflammation. These findings put forward mechanism by which CBD exerts its anti-inflammatory effects as well as explain the beneficial role of CBD in pathological memory T cells and in autoimmune diseases.

Anti-inflammatory effects of the cannabidiol derivative dimethylheptyl-cannabidiol - studies in BV-2 microglia and encephalitogenic T cells.

BACKGROUND: Dimethylheptyl-cannabidiol (DMH-CBD), a non-psychoactive, synthetic derivative of the phytocannabinoid cannabidiol (CBD), has been reported to be anti-inflammatory in RAW macrophages. Here, we evaluated the effects of DMH-CBD at the transcriptional level in BV-2 microglial cells as well as on the proliferation of encephalitogenic T cells. METHODS: BV-2 cells were pretreated with DMH-CBD, followed by stimulation with the endotoxin lipopolysaccharide (LPS). The expression levels of selected genes involved in stress regulation and inflammation were determined by quantitative real-time PCR. In addition, MOG35-55-reactive T cells (TMOG) were cultured with antigen-presenting cells in the presence of DMH-CBD and MOG35-55 peptide, and cell proliferation was determined by measuring [3H]thymidine incorporation. RESULTS: DMH-CBD treatment downregulated in a dose-dependent manner the mRNA expression of LPS-upregulated pro-inflammatory genes (Il1b, Il6, and Tnf) in BV-2 microglial cells. The expression of these genes was also downregulated by DMH-CBD in unstimulated cells. In parallel, DMH-CBD upregulated the expression of genes related to oxidative stress and glutathione homeostasis such as Trb3, Slc7a11/xCT, Hmox1, Atf4, Chop, and p8 in both stimulated and unstimulated microglial cells. In addition, DMH-CBD dose-dependently inhibited MOG35-55-induced TMOG proliferation. CONCLUSIONS: The results show that DMH-CBD has similar anti-inflammatory properties to those of CBD. DMH-CBD downregulates the expression of inflammatory cytokines and protects the microglial cells by inducing an adaptive cellular response against inflammatory stimuli and oxidative injury. In addition, DMH-CBD decreases the proliferation of pathogenic activated TMOG cells.

HU-446 and HU-465, Derivatives of the Non-psychoactive Cannabinoid Cannabidiol, Decrease the Activation of Encephalitogenic T Cells.

Cannabidiol (CBD), the non-psychoactive cannabinoid, has been previously shown by us to decrease peripheral inflammation and neuroinflammation in mouse experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). Here we have studied the anti-inflammatory effects of newly synthesized derivatives of natural (-)-CBD ((-)-8,9-dihydro-7-hydroxy-CBD; HU-446) and of synthetic (+)-CBD ((+)-8,9-dihydro-7-hydroxy-CBD; HU-465) on activated myelin oligodendrocyte glycoprotein (MOG)35-55-specific mouse encephalitogenic T cells (T(MOG) ) driving EAE/MS-like pathologies. Binding assays followed by molecular modeling revealed that HU-446 has negligible affinity toward the cannabinoid CB1 and CB2 receptors while HU-465 binds to both CB1 and CB2 receptors at the high nanomolar concentrations (Ki = 76.7 ± 5.8 nm and 12.1 ± 2.3 nm, respectively). Both, HU-446 and HU-465, at 5 and 10 µm (but not at 0.1 and 1 µm), inhibited the MOG35-55-induced proliferation of autoreactive T(MOG) cells via CB1/CB2 receptor independent mechanisms. Moreover, both HU-446 and HU-465, at 5 and 10 µm, inhibited the release of IL-17, a key autoimmune cytokine, from MOG35-55-stimulated T(MOG) cells. These results suggest that HU-446 and HU-465 have anti-inflammatory potential in inflammatory and autoimmune diseases.

Cannabidiol, a non-psychoactive cannabinoid, leads to EGR2-dependent anergy in activated encephalitogenic T cells.

BACKGROUND: Cannabidiol (CBD), the main non-psychoactive cannabinoid, has been previously shown by us to ameliorate clinical symptoms and to decrease inflammation in myelin oligodendrocyte glycoprotein (MOG)35-55-induced mouse experimental autoimmune encephalomyelitis model of multiple sclerosis as well as to decrease MOG35-55-induced T cell proliferation and IL-17 secretion. However, the mechanisms of CBD anti-inflammatory activities are unclear. METHODS: Here we analyzed the effects of CBD on splenocytes (source of accessory T cells and antigen presenting cells (APC)) co-cultured with MOG35-55-specific T cells (TMOG) and stimulated with MOG35-55. Using flow cytometry, we evaluated the expression of surface activation markers and inhibitory molecules on T cells and B cells. TMOG cells were purified using CD4 positive microbead selection and submitted for quantitative PCR and microarray of mRNA transcript analyzes. Cell signaling studies in purified TMOG were carried out using immunoblotting. RESULTS: We found that CBD leads to upregulation of CD69 and lymphocyte-activation gene 3 (LAG3) regulatory molecules on CD4(+)CD25(-) accessory T cells. This subtype of CD4(+)CD25(-)CD69(+)LAG3(+) T cells has been recognized as induced regulatory phenotype promoting anergy in activated T cells. Indeed, we observed that CBD treatment results in upregulation of EGR2 (a key T cell anergy inducer) mRNA transcription in stimulated TMOG cells. This was accompanied by elevated levels of anergy promoting genes such as IL-10 (anti-inflammatory cytokine), STAT5 (regulatory factor), and LAG3 mRNAs, as well as of several enhancers of cell cycle arrest (such as Nfatc1, Casp4, Cdkn1a, and Icos). Moreover, CBD exposure leads to a decrease in STAT3 and to an increase in STAT5 phosphorylation in TMOG cells, positive and negative regulators of Th17 activity, respectively. In parallel, we observed decreased levels of major histocompatibility complex class II (MHCII), CD25, and CD69 on CD19(+) B cells following CBD treatment, showing diminished antigen presenting capabilities of B cells and reduction in their pro-inflammatory functions. CONCLUSIONS: Our data suggests that CBD exerts its immunoregulatory effects via induction of CD4(+)CD25(-)CD69(+)LAG3(+) cells in MOG35-55-activated APC/TMOG co-cultures. This is accompanied by EGR2-dependent anergy of stimulated TMOG cells as well as a switch in their intracellular STAT3/STAT5 activation balance leading to the previously observed decrease in Th17 activity.

Cannabinoids decrease the th17 inflammatory autoimmune phenotype.

Cannabinoids, the Cannabis constituents, are known to possess anti-inflammatory properties but the mechanisms involved are not understood. Here we show that the main psychoactive cannabinoid, Δ-9-tetrahydrocannabinol (THC), and the main nonpsychoactive cannabinoid, cannabidiol (CBD), markedly reduce the Th17 phenotype which is known to be increased in inflammatory autoimmune pathologies such as Multiple Sclerosis. We found that reactivation by MOG35-55 of MOG35-55-specific encephalitogenic T cells (cells that induce Experimental Autoimmune Encephalitis when injected to mice) in the presence of spleen derived antigen presenting cells led to a large increase in IL-17 production and secretion. In addition, we found that the cannabinoids CBD and THC dose-dependently (at 0.1-5 µM) suppressed the production and secretion of this cytokine. Moreover, the mRNA and protein of IL-6, a key factor in Th17 induction, were also decreased. Pretreatment with CBD also resulted in increased levels of the anti-inflammatory cytokine IL-10. Interestingly, CBD and THC did not affect the levels of TNFα and IFNγ. The downregulation of IL-17 secretion by these cannabinoids does not seem to involve the CB1, CB2, PPARγ, 5-HT1A or TRPV1 receptors. In conclusion, the results show a unique cannabinoid modulation of the autoimmune cytokine milieu combining suppression of the pathogenic IL-17 and IL-6 cytokines along with boosting the expression of the anti-inflammatory cytokine IL-10.

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 Δ(9)-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.

Differential transcriptional profiles mediated by exposure to the cannabinoids cannabidiol and Δ9-tetrahydrocannabinol in BV-2 microglial cells.

BACKGROUND AND PURPOSE: Apart from their effects on mood and reward, cannabinoids exert beneficial actions such as neuroprotection and attenuation of inflammation. The immunosuppressive activity of cannabinoids has been well established. However, the underlying mechanisms are largely unknown. We previously showed that the psychoactive cannabinoid Δ(9) -tetrahydrocannabinol (THC) and the non-psychoactive cannabidiol (CBD) differ in their anti-inflammatory signalling pathways. EXPERIMENTAL APPROACH: To characterize the transcriptional effects of CBD and THC, we treated BV-2 microglial cells with these compounds and performed comparative microarray analysis using the Illumina MouseRef-8 BeadChip platform. Ingenuity Pathway Analysis was performed to identify functional subsets of genes and networks regulated by CBD and/or THC. KEY RESULTS: Overall, CBD altered the expression of many more genes; from the 1298 transcripts found to be differentially regulated by the treatments, 680 gene probe sets were up-regulated by CBD and 58 by THC, and 524 gene products were down-regulated by CBD and only 36 by THC. CBD-specific gene expression profile showed changes associated with oxidative stress and glutathione depletion, normally occurring under nutrient limiting conditions or proteasome inhibition and involving the GCN2/eIF2α/p8/ATF4/CHOP-TRIB3 pathway. Furthermore, CBD-stimulated genes were shown to be controlled by nuclear factors known to be involved in the regulation of stress response and inflammation, mainly via the (EpRE/ARE)-Nrf2/ATF4 system and the Nrf2/Hmox1 axis. CONCLUSIONS AND IMPLICATIONS: These observations indicated that CBD, but much less than THC, induced a cellular stress response in microglial cells and suggested that this effect could underlie its anti-inflammatory activity. 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.

Cannabidiol affects the expression of genes involved in zinc homeostasis in BV-2 microglial cells.

Cannabidiol (CBD) has been shown to exhibit anti-inflammatory, antioxidant and neuroprotective properties. Unlike Δ(9)-tetrahydrocannabinol (THC), CBD is devoid of psychotropic effects and has very low affinity for both cannabinoid receptors, CB(1) and CB(2). We have previously reported that CBD and THC have different effects on anti-inflammatory pathways in lipopolysaccharide-stimulated BV-2 microglial cells, in a CB(1)/CB(2) independent manner. Moreover, CBD treatment of BV-2 cells, was found to induce a robust change in the expression of genes related to oxidative stress, glutathione deprivation and inflammation. Many of these genes were shown to be controlled by Nrf2 and ATF4 transcription factors. Using the Illumina MouseRef-8 BeadChip platform, DAVID Bioinformatics and Ingenuity Pathway Analysis, we identified functional sets of genes and networks affected by CBD. A subset of genes was found to be regulated by the metal responsive element (MRE)-binding transcription factor-1 (MTF-1) and is shown to be related to zinc homeostasis. We found that CBD upregulates the expression of the mRNAs for metallothionein 2 (Mt2), N-myc-downstream regulated gene 1 and matrix metalloproteinase 23 as well as of the zinc transporters ZnT1/Slc30a1 and Zip4/Slc39a4 but downregulates the expression of the mRNA for the zinc transporter Zip10/Slc39a10 as well as for the zinc finger protein 472. Among these genes, ZnT1, Mt2 and the zinc transporters ZIPs are known to function together to control the intracellular zinc concentration. These results show that CBD, but much less so THC, affects the expression of genes involved in zinc homeostasis and suggest that the regulation of zinc levels could have an important role through which CBD may exert its antioxidant and anti-inflammatory effects.

Compartmentalization of endocannabinoids into lipid rafts in a microglial cell line devoid of caveolin-1.

BACKGROUND AND PURPOSE: N-acyl ethanolamines (NAEs) and 2-arachidonoyl glycerol (2-AG) are endogenous cannabinoids and along with related lipids are synthesized on demand from membrane phospholipids. Here, we have studied the compartmentalization of NAEs and 2-AG into lipid raft fractions isolated from the caveolin-1-lacking microglial cell line BV-2, following vehicle or cannabidiol (CBD) treatment. Results were compared with those from the caveolin-1-positive F-11 cell line. EXPERIMENTAL APPROACH: BV-2 cells were incubated with CBD or vehicle. Cells were fractionated using a detergent-free continuous OptiPrep density gradient. Lipids in fractions were quantified using HPLC/MS/MS. Proteins were measured using Western blot. KEY RESULTS: BV-2 cells were devoid of caveolin-1. Lipid rafts were isolated from BV-2 cells as confirmed by co-localization with flotillin-1 and sphingomyelin. Small amounts of cannabinoid CB(1) receptors were found in lipid raft fractions. After incubation with CBD, levels and distribution in lipid rafts of 2-AG, N-arachidonoyl ethanolamine (AEA), and N-oleoyl ethanolamine (OEA) were not changed. Conversely, the levels of the saturated N-stearoyl ethanolamine (SEA) and N-palmitoyl ethanolamine (PEA) were elevated in lipid raft fractions. In whole cells with growth medium, CBD treatment increased AEA and OEA time-dependently, while levels of 2-AG, PEA and SEA did not change. CONCLUSIONS AND IMPLICATIONS: Whereas levels of 2-AG were not affected by CBD treatment, the distribution and levels of NAEs showed significant changes. Among the NAEs, the degree of acyl chain saturation predicted the compartmentalization after CBD treatment suggesting a shift in cell signalling activity. 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.

The non-psychoactive plant cannabinoid, cannabidiol affects cholesterol metabolism-related genes in microglial cells.

Cannabidiol (CBD) is a non-psychoactive plant cannabinoid that is clinically used in a 1:1 mixture with the psychoactive cannabinoid Δ(9)-tetrahydrocannabinol (THC) for the treatment of neuropathic pain and spasticity in multiple sclerosis. Our group previously reported that CBD exerts anti-inflammatory effects on microglial cells. In addition, we found that CBD treatment increases the accumulation of the endocannabinoid N-arachidonoyl ethanolamine (AEA), thus enhancing endocannabinoid signaling. Here we proceeded to investigate the effects of CBD on the modulation of lipid-related genes in microglial cells. Cell viability was tested using FACS analysis, AEA levels were measured using LC/MS/MS, gene array analysis was validated with real-time qPCR, and cytokine release was measured using ELISA. We report that CBD significantly upregulated the mRNAs of the enzymes sterol-O-acyl transferase (Soat2), which synthesizes cholesteryl esters, and of sterol 27-hydroxylase (Cyp27a1). In addition, CBD increased the mRNA of the lipid droplet-associated protein, perilipin2 (Plin2). Moreover, we found that pretreatment of the cells with the cholesterol chelating agent, methyl-ß-cyclodextrin (MBCD), reversed the CBD-induced increase in Soat2 mRNA but not in Plin2 mRNA. Incubation with AEA increased the level of Plin2, but not of Soat2 mRNA. Furthermore, MBCD treatment did not affect the reduction by CBD of the LPS-induced release of the proinflammatory cytokine IL-1ß. CBD treatment modulates cholesterol homeostasis in microglial cells, and pretreatment with MBCD reverses this effect without interfering with CBD's anti-inflammatory effects. The effects of the CBD-induced increase in AEA accumulation on lipid-gene expression are discussed.

Cannabidiol inhibits pathogenic T cells, decreases spinal microglial activation and ameliorates multiple sclerosis-like disease in C57BL/6 mice.

BACKGROUND AND PURPOSE: Cannabis extracts and several cannabinoids have been shown to exert broad anti-inflammatory activities in experimental models of inflammatory CNS degenerative diseases. Clinical use of many cannabinoids is limited by their psychotropic effects. However, phytocannabinoids like cannabidiol (CBD), devoid of psychoactive activity, are, potentially, safe and effective alternatives for alleviating neuroinflammation and neurodegeneration. EXPERIMENTAL APPROACH: We used experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein (MOG) in C57BL/6 mice, as a model of multiple sclerosis. Using immunocytochemistry and cell proliferation assays we evaluated the effects of CBD on microglial activation in MOG-immunized animals and on MOG-specific T-cell proliferation. KEY RESULTS: Treatment with CBD during disease onset ameliorated the severity of the clinical signs of EAE. This effect of CBD was accompanied by diminished axonal damage and inflammation as well as microglial activation and T-cell recruitment in the spinal cord of MOG-injected mice. Moreover, CBD inhibited MOG-induced T-cell proliferation in vitro at both low and high concentrations of the myelin antigen. This effect was not mediated via the known cannabinoid CB(1) and CB(2) receptors. CONCLUSIONS AND IMPLICATIONS: CBD, a non-psychoactive cannabinoid, ameliorates clinical signs of EAE in mice, immunized against MOG. Suppression of microglial activity and T-cell proliferation by CBD appeared to contribute to these beneficial effects.

Cannabinoids Delta(9)-tetrahydrocannabinol and cannabidiol differentially inhibit the lipopolysaccharide-activated NF-kappaB and interferon-beta/STAT proinflammatory pathways in BV-2 microglial cells.

Cannabinoids have been shown to exert anti-inflammatory activities in various in vivo and in vitro experimental models as well as ameliorate various inflammatory degenerative diseases. However, the mechanisms of these effects are not completely understood. Using the BV-2 mouse microglial cell line and lipopolysaccharide (LPS) to induce an inflammatory response, we studied the signaling pathways engaged in the anti-inflammatory effects of cannabinoids as well as their influence on the expression of several genes known to be involved in inflammation. We found that the two major cannabinoids present in marijuana, Delta(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD), decrease the production and release of proinflammatory cytokines, including interleukin-1beta, interleukin-6, and interferon (IFN)beta, from LPS-activated microglial cells. The cannabinoid anti-inflammatory action does not seem to involve the CB1 and CB2 cannabinoid receptors or the abn-CBD-sensitive receptors. In addition, we found that THC and CBD act through different, although partially overlapping, mechanisms. CBD, but not THC, reduces the activity of the NF-kappaB pathway, a primary pathway regulating the expression of proinflammatory genes. Moreover, CBD, but not THC, up-regulates the activation of the STAT3 transcription factor, an element of homeostatic mechanism(s) inducing anti-inflammatory events. Following CBD treatment, but less so with THC, we observed a decreased level of mRNA for the Socs3 gene, a main negative regulator of STATs and particularly of STAT3. However, both CBD and THC decreased the activation of the LPS-induced STAT1 transcription factor, a key player in IFNbeta-dependent proinflammatory processes. In summary, our observations show that CBD and THC vary in their effects on the anti-inflammatory pathways, including the NF-kappaB and IFNbeta-dependent pathways.