Aß Chronic Exposure Promotes an Activation State of Microglia through Endocannabinoid Signalling Imbalance.

Dysfunctional phenotype of microglia, the primary brain immune cells, may aggravate Alzheimer's disease (AD) pathogenesis by releasing proinflammatory factors, such as nitric oxide (NO). The endocannabinoids N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) are bioactive lipids increasingly recognised for their essential roles in regulating microglial activity both under normal and AD-driven pathological conditions. To investigate the possible impact of chronic exposure to ß-amyloid peptides (Aß) on the microglial endocannabinoid signalling, we characterised the functional expression of the endocannabinoid system on neonatal microglia isolated from wild-type and Tg2576 mice, an AD-like model, which overexpresses Aß peptides in the developing brain. We found that Aß-exposed microglia produced 2-fold more 2-AG than normal microglia. Accordingly, the expression levels of diacylglycerol lipase-α (DAGLα) and monoacylglycerol lipase (MAGL), the main enzymes responsible for synthesising and hydrolysing 2-AG, respectively, were consistently modified in Tg2576 microglia. Furthermore, compared to wild-type cells, transgenic microglia basally showed increased expression of the cannabinoid 2 receptor, typically upregulated in an activated proinflammatory phenotype. Indeed, following inflammatory stimulus, Aß-exposed microglia displayed an enhanced production of NO, which was abolished by pharmacological inhibition of DAGLα. These findings suggested that exposure to Aß polarises microglial cells towards a pro-AD phenotype, possibly by enhancing 2-AG signalling.

Determination of endocannabinoids and their conjugated congeners in the brain by means of µSPE combined with UHPLC-MS/MS.

The present study encompasses the development of a fast and reliable analytical method to quantify the main endocannabinoids and some of their conjugated congeners, particularly N-arachidonoyl amino acids, in brain tissue. Samples were homogenized and a micro solid phase extraction (µSPE) procedure was developed for brain homogenate clean-up. Miniaturized SPE was selected as it allowed to work with reduced sample amounts, while maintaining high sensitivity; this last feature was mandatory due to the low concentration of endocannabinoids in biological matrices that makes their determination a challenging analytical task. UHPLC-MS/MS was used for the analysis as it provided a great sensitivity, especially for conjugated forms that were detected by negative ionization. Polarity switching was applied during the run; low limits of quantification were between 0.003 ng g-1 and 0.5 ng g-1. This method provided also low matrix effect (lower than 30%) and good extraction recoveries in the brain. To the best of our knowledge, this is the first time that µSPE is applied on this matrix for this class of compounds. The method was validated according to international guidelines, and then tested on real cerebellum samples from mice, which were sub-chronically treated with URB597, a well-known inhibitor of the fatty acid amide hydrolase.

Rare Phytocannabinoids Exert Anti-Inflammatory Effects on Human Keratinocytes via the Endocannabinoid System and MAPK Signaling Pathway.

Increasing evidence supports the therapeutic potential of rare cannabis-derived phytocannabinoids (pCBs) in skin disorders such as atopic dermatitis, psoriasis, pruritus, and acne. However, the molecular mechanisms of the biological action of these pCBs remain poorly investigated. In this study, an experimental model of inflamed human keratinocytes (HaCaT cells) was set up by using lipopolysaccharide (LPS) in order to investigate the anti-inflammatory effects of the rare pCBs cannabigerol (CBG), cannabichromene (CBC), Δ9-tetrahydrocannabivarin (THCV) and cannabigerolic acid (CBGA). To this aim, pro-inflammatory interleukins (IL)-1ß, IL-8, IL-12, IL-31, tumor necrosis factor (TNF-ß) and anti-inflammatory IL-10 levels were measured through ELISA quantification. In addition, IL-12 and IL-31 levels were measured after treatment of HaCaT cells with THCV and CBGA in the presence of selected modulators of endocannabinoid (eCB) signaling. In the latter cells, the activation of 17 distinct proteins along the mitogen-activated protein kinase (MAPK) pathway was also investigated via Human Phosphorylation Array. Our results demonstrate that rare pCBs significantly blocked inflammation by reducing the release of all pro-inflammatory ILs tested, except for TNF-ß. Moreover, the reduction of IL-31 expression by THCV and CBGA was significantly reverted by blocking the eCB-binding TRPV1 receptor and by inhibiting the eCB-hydrolase MAGL. Remarkably, THCV and CBGA modulated the expression of the phosphorylated forms (and hence of the activity) of the MAPK-related proteins GSK3ß, MEK1, MKK6 and CREB also by engaging eCB hydrolases MAGL and FAAH. Taken together, the ability of rare pCBs to exert an anti-inflammatory effect in human keratinocytes through modifications of eCB and MAPK signaling opens new perspectives for the treatment of inflammation-related skin pathologies.

Endocannabinoid Metabolism and Transport as Drug Targets.

The wide distribution of the endocannabinoid system (ECS) throughout the body and its pivotal pathophysiological role offer promising opportunities for the development of novel therapeutic drugs for treating several diseases. However, the need for strategies to circumvent the unwanted psychotropic and immunosuppressive effects associated with cannabinoid receptor agonism/antagonism has led to considerable research in the field of molecular alternatives, other than type-1 and type-2 (CB1/2) receptors, as therapeutic targets to indirectly manipulate this pro-homeostatic system. In this context, the use of selective inhibitors of proteins involved in endocannabinoid (eCB) transport and metabolism allows for an increase or decrease of the levels of N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) in the sites where these major eCBs are indeed needed. This chapter will briefly review some preclinical and clinical evidence for the therapeutic potential of ECS pharmacological manipulation.

Visualization of Endocannabinoids in the Cell.

A still unsolved, although critical, issue in endocannabinoid research is the mechanism by which the lipophilic anandamide (AEA) moves from its site of synthesis, crosses the aqueous milieu, and reaches the different intracellular membrane compartments, where its metabolic and signaling pathways take place. The difficulty of studying intracellular AEA transport and distribution results from the lack of specific probes and techniques to track and visualize this bioactive lipid within the cells. Herein, we describe the use of a biotinylated, non-hydrolyzable derivative of AEA (biotin-AEA, b-AEA) for visualizing the subcellular distribution of this endocannabinoid by means of confocal fluorescence microscopy.

Microglial Endocannabinoid Signalling in AD.

Chronic inflammation in Alzheimer's disease (AD) has been recently identified as a major contributor to disease pathogenesis. Once activated, microglial cells, which are brain-resident immune cells, exert several key actions, including phagocytosis, chemotaxis, and the release of pro- or anti-inflammatory mediators, which could have opposite effects on brain homeostasis, depending on the stage of disease and the particular phenotype of microglial cells. The endocannabinoids (eCBs) are pleiotropic bioactive lipids increasingly recognized for their essential roles in regulating microglial activity both under normal and AD-driven pathological conditions. Here, we review the current literature regarding the involvement of this signalling system in modulating microglial phenotypes and activity in the context of homeostasis and AD-related neurodegeneration.

Cryotolerance of equine spermatozoa correlates with specific fatty acid pattern: A pilot study.

Sperm cryopreservation represents a powerful tool for horse breeding. To improve the efficiency of artificial insemination in the horse using cryopreserved spermatozoa, an adequate understanding of the underlying biophysical properties that affect sperm cryosurvival needs to be reached yet. In this pilot study, we described isolation and analysis of the main fatty acids from sperms of stallions classified as good and poor freezers (7 GF and 5 PF, according to sperm motility and viability, before and after cryopreservation). Fatty acid profiles were only assessed in pre-thaw sperms. Eight main fatty acids were identified, using gas chromatography, and their contents were expressed as percentage of the total lipid content. We found that lauric, myristic and oleic acid (C12:0, C14:0 and C18:1n9c) turned out to be about 2-fold more abundant in the sperm cells of the GFs compared with PFs. Moreover, we described for the first time the presence of a very high amount of a trans geometrical isomer of linoleic acid, linolelaidic acid (C18:2n6t), in pre-thaw PF spermatozoa. Notably, we found in fresh sperms of PF stallions a ratio of unsaturated fatty acids to saturated fatty acids which was twice that of those of GF group, suggesting a positive effect of a high saturated-to-unsaturated fatty acid ratio for the "freezability" of equine spermatozoa. Finally, principal component analysis (PCA) confirmed the relationships between specific fatty acids and cryotolerance of equine spermatozoa, also providing a graphical classification and additional information about the dominant variables governing the classification process.