sr-144528 and Encephalitis

In our previous studies, we found that a single ultralow dose of tetrahydrocannabinol (THC; 0.002 mg/kg, three to four orders of magnitude lower than the conventional doses) protects the brain from different insults that cause cognitive deficits. Because various insults may trigger a neuroinflammatory response that leads to secondary damage to the brain, the current study tested whether this extremely low dose of THC could protect the brain from inflammation-induced cognitive deficits. Mice received a single injection of THC (0.002 mg/kg) 48 hr before or 1-7 days after treatment with lipopolysccharide (LPS; 10 mg/kg) and were examined with the object recognition test 3 weeks later. LPS caused long-lasting cognitive deficits, whereas the application of THC before or after LPS protected the mice from this LPS-induced damage. The protective effect of THC was blocked by the cannabinoid (CB) 1 receptor antagonist SR14176A but not by the CB2 receptor antagonist SR141528 and was mimicked by the CB1 agonist ACEA but not by the CB2 agonist HU308. The protective effect of THC was also blocked by pretreatment with GW9662, indicating the involvement of peroxisome proliferator-activated receptor-γ. Biochemical examination of the brain revealed a long-term (at least 7 weeks) elevation of the prostaglandin-producing enzyme cyclooxygenase-2 in the hippocampus and in the frontal cortex following the injection of LPS. Pretreatment with the extremely low dose of THC tended to attenuate this elevation. Our results suggest that an ultralow dose of THC that lacks any psychotrophic activity protects the brain from neuroinflammation-induced cognitive damage and might be used as an effective drug for the treatment of neuroinflammatory conditions, including neurodegenerative diseases.

Topics: Anilides; Animals; Arachidonic Acids; Brain; Camphanes; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Cognition Disorders; Cyclooxygenase 2; Disease Models, Animal; Dose-Response Relationship, Drug; Dronabinol; Encephalitis; Lipopolysaccharides; Male; Mice; Mice, Inbred ICR; PPAR gamma; Pyrazoles; Recognition, Psychology

Previous studies have shown that modulation of the receptor-mediated cannabinoid system during neuroinflammation can produce potent neuroprotective and anti-inflammatory effects. However, in this context, little is known about how selective activation of the cannabinoid type-2 receptor (CB2R) affects the activated state of the brain endothelium and blood-brain barrier (BBB) function. Using human brain tissues and primary human brain microvascular endothelial cells (BMVECs), we demonstrate that the CB2R is highly upregulated during inflammatory insult. We then examined whether the CB2R agonists could attenuate inflammatory responses at the BBB using a mouse model of LPS-induced encephalitis and highly selective CB2R agonists. Visualization by intravital microscopy revealed that administration of JWH133 [(6aR,10aR)-3-(1,1-dimethylbutyl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran] or a novel resorcinol-based compound, O-1966 (1-[4-(1,1-dimethyl-heptyl)-2,6-dimethoxy-phenyl]-3-methyl-cyclohexanol), greatly attenuated leukocyte adhesion in surface pial vessels and in deep ascending cortical postcapillary venules. BBB permeability assessments with small and large fluorescent tracers showed that CB2R agonists were effective at preventing barrier leakiness after LPS administration. To determine whether the effects by CB2R agonists on barrier protection are not only due to the CB2R modulation of immune cell function, we tested the agonists in vitro with barrier-forming primary BMVECs. Remarkably, the addition of CB2R agonist increased transendothelial electrical resistance and increased the amount of tight junction protein present in membrane fractions. Furthermore, CB2R agonists decreased the induction of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 surface expression in BMVECs exposed to various proinflammatory mediators. Together, these results suggest that pharmacological CB2R ligands offer a new strategy for BBB protection during neuroinflammation.

Topics: Animals; Anisoles; Blood-Brain Barrier; Camphanes; Cannabinoids; Capillary Permeability; Cell Adhesion; Cells, Cultured; Cyclohexanols; Dextrans; Disease Models, Animal; Electric Impedance; Encephalitis; Endothelial Cells; Endothelium; Flow Cytometry; Fluorescein-5-isothiocyanate; Gene Expression Regulation; Humans; Intercellular Adhesion Molecule-1; Leukocytes; Lipopolysaccharides; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Phosphoproteins; Platelet Endothelial Cell Adhesion Molecule-1; Pyrazoles; Receptor, Cannabinoid, CB2; Statistics, Nonparametric; Tumor Necrosis Factor-alpha; Vascular Cell Adhesion Molecule-1; Zonula Occludens-1 Protein

The endocannabinoid system is a promising therapeutic target in a wide variety of diseases. However, the non-desirable psychotropic effects of natural and synthetic cannabinoids have largely counteracted their clinical usefulness. These effects are mostly mediated by cannabinoid receptors of the CB(1) type, that exhibit a wide distribution in neuronal elements of the CNS. Thus, the presence of other elements of this system in the CNS, such as CB(2) receptors, may open new possibilities for the development of cannabinoid-based therapies. These receptors are almost absent from the CNS in normal conditions but are up-regulated in glial cells under chronic neuroinflammatory stimuli, as has been described in Alzheimer's disease. To understand the functional role of these receptors, we tested their role in the process of beta-amyloid removal, that is currently considered as one of the most promising experimental approaches for the treatment of this disease. Our results show that a CB(2) agonist (JWH-015) is capable of inducing the removal of native beta-amyloid removal from human frozen tissue sections as well as of synthetic pathogenic peptide by a human macrophage cell line (THP-1). Remarkably, this effect was achieved at low doses (maximum effect at 10 nM) and was specific for this type of cells, as U373MG astrocytoma cells did not respond to the treatment. The effect was CB(2)-mediated, at least partially, as the selective CB(2) antagonist SR144528 prevented the JWH-015-induced plaque removal in situ. These data corroborate the possible therapeutic interest of CB(2) cannabinoid specific chemicals in the treatment of Alzheimer's disease.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Astrocytes; Brain; Camphanes; Cannabinoids; Cell Line, Tumor; Dose-Response Relationship, Drug; Encephalitis; Gliosis; Humans; Indoles; Macrophages; Phagocytosis; Plaque, Amyloid; Pyrazoles; Receptor, Cannabinoid, CB2

This study investigated cannabinoid receptor-mediated regulation of brain and peripheral cytokines in vivo. The cannabinoid receptor agonist, HU210 attenuated lipopolysaccharide (LPS)-induced increases in IL-1beta and TNFalpha in rat brain and IL-1beta, TNFalpha, IL-6 and IFNgamma in plasma. The CB(1) receptor antagonist, SR141716A, attenuated the immunosupressive effects of HU210 on IL-1beta, but not TNFalpha. SR141716A or the CB(2) receptor antagonist, SR144528, alone attenuated LPS-induced cytokine increases. LPS and/or cannabinoids also reduced circulating lymphocyte numbers and increased corticosterone levels. These data provide evidence for modulation of pro-inflammatory cytokines in vivo by cannabinoid receptors and inform the development of cannabinoids for neuroinflammatory disorders.

Topics: Animals; Camphanes; Corticosterone; Dronabinol; Drug Interactions; Encephalitis; Hypothalamo-Hypophyseal System; Interferon-gamma; Interleukin-10; Interleukin-1beta; Interleukin-6; Lipopolysaccharides; Lymphocyte Count; Male; Neuroimmunomodulation; Neuroprotective Agents; Piperidines; Pituitary-Adrenal System; Pyrazoles; Rats; Rats, Sprague-Dawley; Rimonabant; Tumor Necrosis Factor-alpha

Activated glial cells have been implicated in the neuropathogenesis of many infectious and inflammatory diseases of the brain. A number of inflammatory mediators have been proposed to play a role in glial cell-related brain damage; e.g., free radicals such as nitric oxide (NO), cytokines, and chemokines. Our laboratory has been interested in the effect of psychoactive drugs and their derivatives on the production of these mediators. Cannabinoids have been shown to possess immunomodulatory as well as psychoactive properties. We previously have shown that interleukin (IL)-1beta-stimulated human astrocytes, but not microglia, produce NO. In this study, we investigated the effects of the synthetic cannabinoid WIN55,212-2 on the production of several key inflammatory mediators by human fetal astrocytes activated by IL-1beta. Expression of the cannabinoid receptors CB1 and CB2 was detected on human astrocytes. WIN55,212-2 (10(-5) M) potently inhibited inducible NO synthase (iNOS) and corresponding NO production by IL-1beta-stimulated astrocytes. The CB1 and CB2 receptor-specific antagonists SR141716A and SR144528, respectively, partially blocked this suppressive effect. In addition, treatment of astrocytes with WIN55,212-2 downregulated in a concentration-dependent manner IL-1beta-induced tumor necrosis factor (TNF)-alpha release. Treatment with WIN55,212-2 also inhibited production of the chemokines CXCL10, CCL2 and CCL5 by IL-1beta-activated astrocytes. These findings indicate that WIN55,212-2 inhibits the production of inflammatory mediators by IL-1beta-stimulated human astrocytes and suggest that comparable agents may have therapeutic potential for the management of brain inflammation.

Topics: Astrocytes; Benzoxazines; Camphanes; Cells, Cultured; Chemokines; Down-Regulation; Encephalitis; Gliosis; Humans; Inflammation Mediators; Interleukin-1; Morpholines; Naphthalenes; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Rimonabant; Tumor Necrosis Factor-alpha