Dataset Information

Anti-inflammatory effects of cannabinoid CB(2) receptor activation in endotoxin-induced uveitis.

ABSTRACT:

Background and purpose

Cannabinoid CB2 receptors mediate immunomodulation. Here, we investigated the effects of CB2 receptor ligands on leukocyte-endothelial adhesion and inflammatory mediator release in experimental endotoxin-induced uveitis (EIU).

Experimental approach

EIU was induced by intraocular injection of lipopolysaccharide (LPS, 20?ng·?L(-1) ). Effects of the CB2 receptor agonist, HU308 (1.5% topical), the CB2 receptor antagonist, AM630 (2.5?mg·kg(-1) i.v.), or a combination of both compounds on leukocyte-endothelial interactions were measured hourly for 6?h in rat iridial vasculature using intravital microscopy. Anti-inflammatory actions of HU308 were compared with those of clinical treatments for uveitis - dexamethasone, prednisolone and nepafenac. Transcription factors (NF-?B, AP-1) and inflammatory mediators (cytokines, chemokines and adhesion molecules) were measured in iris and ciliary body tissue.

Key results

Leukocyte-endothelium adherence was increased in iridial microvasculature between 4-6?h after LPS. HU308 reduced this effect after LPS injection and decreased pro-inflammatory mediators: TNF-?, IL-1?, IL-6, CCL5 and CXCL2. AM630 blocked the actions of HU-308, and increased leukocyte-endothelium adhesion. HU-308 decreased levels of the transcription factors NF-?B and AP-1, while AM630 increased levels of NF-?B. Topical treatments with dexamethasone, prednisolone or nepafenac, failed to alter leukocyte adhesion or mitigate LPS-induced increases in inflammatory mediators during the 6?h of EIU.

Conclusion and implications

Activation of CB2 receptors was anti-inflammatory in a model of acute EIU and involved a reduction in NF-?B, AP-1 and inflammatory mediators. CB2 receptors may be promising drug targets for the development of novel ocular anti-inflammatory agents.

Linked articles

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

SUBMITTER: Toguri JT

PROVIDER: S-EPMC3954484 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Anti-inflammatory effects of cannabinoid CB(2) receptor activation in endotoxin-induced uveitis.

Toguri J T JT Lehmann C C Laprairie R B RB Szczesniak A M AM Zhou J J Denovan-Wright E M EM Kelly M E M ME

British journal of pharmacology 20140301 6

<h4>Background and purpose</h4>Cannabinoid CB2 receptors mediate immunomodulation. Here, we investigated the effects of CB2 receptor ligands on leukocyte-endothelial adhesion and inflammatory mediator release in experimental endotoxin-induced uveitis (EIU).<h4>Experimental approach</h4>EIU was induced by intraocular injection of lipopolysaccharide (LPS, 20 ng·μL(-1) ). Effects of the CB2 receptor agonist, HU308 (1.5% topical), the CB2 receptor antagonist, AM630 (2.5 mg·kg(-1) i.v.), or a combina ...[more]

PMID: 24308861

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Project description:(1) Background: The cannabinoid 2 receptor (CB2R) is a promising anti-inflammatory drug target and development of selective CB2R ligands may be useful for treating sight-threatening ocular inflammation. (2) Methods: This study examined the pharmacology of three novel chemically-diverse selective CB2R ligands: CB2R agonists, RO6871304, and RO6871085, as well as a CB2R inverse agonist, RO6851228. In silico molecular modelling and in vitro cell-based receptor assays were used to verify CB2R interactions, binding, cell signaling (ß-arrestin and cAMP) and early absorption, distribution, metabolism, excretion, and toxicology (ADMET) profiling of these receptor ligands. All ligands were evaluated for their efficacy to modulate leukocyte-neutrophil activity, in comparison to the reported CB2R ligand, HU910, using an in vivo mouse model of endotoxin-induced uveitis (EIU) in wild-type (WT) and CB2R-/- mice. The actions of RO6871304 on neutrophil migration and adhesion were examined in vitro using isolated neutrophils from WT and CB2R-/- mice, and in vivo in WT mice with EIU using adoptive transfer of WT and CB2R-/- neutrophils, respectively. (3) Results: Molecular docking studies indicated that RO6871304 and RO6871085 bind to the orthosteric site of CB2R. Binding studies and cell signaling assays for RO6871304 and RO6871085 confirmed high-affinity binding to CB2R and selectivity for CB2R > CB1R, with both ligands acting as full agonists in cAMP and ß-arrestin assays (EC50s in low nM range). When tested in EIU, topical application of RO6871304 and RO6871085 decreased leukocyte-endothelial adhesion and this effect was antagonized by the inverse agonist, RO6851228. The CB2R agonist, RO6871304, decreased in vitro neutrophil migration of WT neutrophils but not neutrophils from CB2R-/-, and attenuated adhesion of adoptively-transferred leukocytes in EIU. (4) Conclusions: These unique ligands are potent and selective for CB2R and have good immunomodulating actions in the eye. RO6871304 and RO6871085, as well as HU910, decreased leukocyte adhesion in EIU through inhibition of resident ocular immune cells. The data generated with these three structurally-diverse and highly-selective CB2R agonists support selective targeting of CB2R for treating ocular inflammatory diseases.

Project description:Neuroinflammation plays a major role in postoperative cognitive dysfunction (POCD). Accumulated evidence indicates that cannabinoid receptor type 2 (CB2R) can mediate anti-inflammatory and immunomodulatory effects in part by controlling microglial activity. However, the impact of CB2R on postoperative cognition has not been investigated. We hypothesized that CB2R is involved in surgery-induced cognitive impairment in adult mice.Adult C57BL/6 mice were subjected to intramedullary fixation surgery for tibial fracture under isoflurane anesthesia and CB2R agonist (JWH133) or CB2R antagonist (AM630) treatment. The mice were trained 24 h prior to surgery using a fear conditioning protocol and assessed in a novel context on postoperative days 1, 3, and 7 to evaluate cognitive function. Open-field testing was performed to evaluate the locomotor activity of the mice. The expression levels of IL-1β, TNF-α, MCP-1, and CB2R in the hippocampus and prefrontal cortex were assessed by Western blotting; the expression of microglial marker CD11b in the CA1 area of the hippocampus and medial prefrontal cortex was assessed by immunostaining.The mice displayed no changes in locomotor activity after surgery and drug treatments. The mice exhibited impaired hippocampal-dependent memory accompanied by an increased expression of proinflammatory factors in the hippocampus and prefrontal cortex 1, 3, and 7 days after surgery, while hippocampal-independent memory remained unaffected at the same time points. JWH133 treatment attenuated surgery-induced memory loss, while AM630 treatment aggravated surgery-induced memory loss, paralleled by a decreased or increased expression of proinflammatory factors in the hippocampus and prefrontal cortex. The expression of CB2R in the hippocampus and prefrontal cortex was upregulated following surgery; however, it was downregulated by postoperative treatment with JWH133. Similarly, the expression of CD11b in the CA1 area of the hippocampus and medial prefrontal cortex was upregulated following surgery and downregulated by postoperative treatment with JWH133.These findings indicate that CB2R may modulate the neuroinflammatory and cognitive impairment in a mouse model of orthopedic surgery, and the activation of CB2R may effectively ameliorate the hippocampal-dependent memory loss of mice in the early postoperative stage.

Dataset Information

Anti-inflammatory effects of cannabinoid CB(2) receptor activation in endotoxin-induced uveitis.

Background and purpose

Experimental approach

Key results

Conclusion and implications

Linked articles

Publications

Anti-inflammatory effects of cannabinoid CB(2) receptor activation in endotoxin-induced uveitis.

Similar Datasets

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