Cannabinoid Type 2 Receptor Activation Downregulates Stroke-Induced Classic and Alternative Brain Macrophage/Microglial Activation Concomitant to Neuroprotection

Abstract

Background and Purpose— Ischemic stroke continues to be one of the main causes of death worldwide. Inflammation accounts for a large part of damage in this pathology. The cannabinoid type 2 receptor (CB2R) has been proposed to have neuroprotective properties in neurological diseases. Therefore, our aim was to determine the effects of the activation of CB2R on infarct outcome and on ischemia-induced brain expression of classic and alternative markers of macrophage/microglial activation. Methods— Swiss wild-type and CB2R knockout male mice were subjected to a permanent middle cerebral artery occlusion. Mice were treated with either a CB2R agonist (JWH-133), with or without a CB2R antagonist (SR144528) or vehicle. Infarct outcome was determined by measuring infarct volume and neurological outcome. An additional group of animals was used to assess mRNA and protein expression of CB2R, interleukin (IL)-1β, IL-6, tumor necrosis factor α (TNF-α), monocyte chemoattractant protein–1 (MCP-1), macrophage inflammatory peptide (MIP) –1α, RANTES, inducible nitric oxide synthase (iNOS), cyclooxygenase-2, IL-4, IL-10, transforming growth factor β (TGF-β), arginase I, and Ym1. Results— Administration of JWH-133 significantly improved infarct outcome, as shown by a reduction in brain infarction and neurological impairment. This effect was reversed by the CB2R antagonist and was absent in CB2R knockout mice. Concomitantly, administration of JWH-133 led to a lower intensity of Iba1+ microglia/macrophages and a decrease in middle cerebral artery occlusion–induced gene expression of both classic (IL-6, TNF-α, MCP-1, MIP-1α, RANTES, and iNOS) and alternative mediators/markers (IL-10, TGF-β, and Ym1) of microglial/macrophage activation after permanent middle cerebral artery occlusion. Conclusions— The inhibitory effect of CB2R on the activation of different subpopulations of microglia/macrophages may account for the protective effect of the selective CB2R agonist JWH-133 after stroke.

PET imaging of cannabinoid type 2 receptors with [11C]A-836339 did not evidence changes following neuroinflammation in rats

“…Preclinical studies have shown that the CB receptor system might exert a neuroprotective effect over a large number of neurological and neurodenerative disorders. [8][9][10][11][12][13][14][15][16][17][18] Despite this, the application of CB-based medicines into the clinical use is still a major challenge for the near future. The evaluation of promising novel ]DPA-714 uptake was quantified in vehicle (n ¼ 5) and JWH133 (n ¼ 7) at day 7 after ischemia as %ID/cc (mean AE SD) in the cerebral hemispheres, cortex and striatum (e-f).…”

Cannabinoid Receptor 2 Modulates Susceptibility to Experimental Cerebral Malaria through a CCL17-dependent Mechanism

“…These findings were unexpected, because earlier data indicated that CB2 activation inhibited alternative but also classical marker expression in brain-derived microglia/macrophages in an ischemic stroke model or even favored IL-10 production in LPS/IFN-␥ stimulated murine peritoneal macrophage and the transition to an M2 phenotype in liver macrophages (Kupffer cells) (22,54,55). These data, in comparison with our findings, may reflect cell-specific differences of CB2 functions that depend on culture conditions, the characteristics of the pathogen, or the respective CB2-expressing myeloid cell subset in vivo.…”

Cannabinoids in Neurodegenerative Disorders and Stroke/Brain Trauma: From Preclinical Models to Clinical Applications

“…In the case of TBI, damage is most commonly caused either by closed (concussion) or open head injury (stab wound). The cannabinoids having beneficial effects in these models included 1) dexanabinol (HU-211) [8][9][10][11], which is a synthetic compound having a chemical structure of a classic cannabinoid but no activity at cannabinoid receptors; 2) nonselective synthetic cannabinoid agonists such as HU-210, the active enantiomer of HU-211 [12], WIN 55,212-2 [13,14], TAK-937 [15,16], and BAY 38-7271 [17,18]; 3) phytocannabinoids such as Δ 9 -tetrahydrocannabinol (Δ 9 -THC) [19], which binds not only CB 1 R and CB 2 R, but also cannabidiol (CBD), which has no affinity at these receptors but was highly active against brain ischemia [20][21][22]; 4) endocannabinoids such as 2-arachidonoylglycerol (2-AG), in particular in TBI induced by closed head injury [23][24][25], but also in experimental ischemia [26], and also anandamide [27] and its related signaling lipids palmitoylethanolamide (PEA) [28], oleoylethanolamide [27], and N-arachidonoyl-L-serine (AraS) [29]; and 5) selective CB 2 R targeting ligands such as O-3853, O-1966, and JWH-133 [30][31][32][33][34][35]. Most of these studies were conducted with the cannabinoid administered at least after the cytotoxic insult [12-19, 21-26, 28-35].…”

“…In most cases, the benefits obtained with these cannabinoid-related compounds (e.g., improved neurological performance, reduced infarct size, edema, BBB disruption, inflammation and gliosis, and control of immunomodulatory responses) involved the activation of CB 1 R (e.g., HU-210 [12], WIN55,212-2 [13,14], TAK-937 [15,16], BAY 38-7271 [17,18], Δ 9 -THC [19], and PEA [36]) and/or CB 2 R (e.g., AraS [29], O-3853, O-1966, and JWH-133 [30][31][32][33][34][35] mice with a genetic deficiency in CB 1 R or, to a lesser extent, CB 2 R. For example, CB 1 -/-mice showed increased infarct size and neurological deficits after tMCAO, concomitant with a reduction in cerebral blood flow and NMDA excitotoxicity [37], and a similar greater vulnerability was also found in TBI models [24], then supporting the protective role of CB 1 R against both pathological conditions. In the case of CB 2 -/-mice, results were controversial, with a study reporting larger cerebral infarction and a worsened neurological function after tMCAO [30], but others describing no differences using permanent MCAO [32,33], despite the notable effects found in pharmacological experiments with compounds selectively activating the CB 2 R [30][31][32][33][34][35]. These types of agonists are particularly interesting for a possible therapeutic application in stroke and TBI because of the lack of psychoactivity of their selective agonists.…”

“…As far as the cannabinoid receptors are concerned, most studies showed an upregulated expression of both CB 1 R and, in particular, CB 2 R in stroke, with neurons (for CB 1 R) and microglial/macrophages, astrocytes, and neutrophils (for CB 2 R) being the most common cellular substrates for these responses [33,[51][52][53][54]. However, some studies described downregulatory responses of both receptors at very early times after induction of ischemia [33,55]. Upregulation of CB 2 R with no changes in CB 1 R have been found in TBI [56].…”