glyceryl-2-arachidonate and Dermatitis--Allergic-Contact

Cannabinoid (CB) 2 is expressed on immune and inflammatory cells. Identification of 2-arachidonyl glycerol (2-AG) and anandamide as endogenous CB2 ligands has allowed investigations of the roles of CB2 and its endogenous ligand system in inflammatory cells. However, the roles of this receptor-ligand system in inflammatory and allergic immune responses in vivo have not been fully elucidated.. Two mouse allergy models, namely ear dermatitis induced by 2,4-dinitrofluorobenzene and allergic bronchitis induced by ovalbumin, were analyzed for 2-AG amounts in allergic tissues, with reference to allergic and inflammatory symptoms. To investigate the gene expression via CB2 in inflammatory cells, human promyelocytic HL-60 cells were stimulated by the CB2 ligand 2-AG ether and analyzed using a DNA microarray.. In the ear dermatitis model, the 2-AG amount increased upon serial 2,4-dinitrofluorobenzene challenges and was correlated with ear weight gain. The increased ear thickness in this allergy model was clearly suppressed in CB2 knockout mice, suggesting that the generated endogenous CB2 ligands induce ear thickness through aberrant inflammatory responses and remodeling mediated via CB2. In the allergic bronchitis model, the 2-AG level in bronchoalveolar lavage was increased and sustained during the elevation of inflammatory cell infiltration. The DNA microarray analysis of human HL-60 cells revealed that 2-AG ether induced expressions of not only inflammatory chemokines/cytokines but also of cell growth factors.. Our data strongly suggest that endogenous CB2 ligands upregulated upon disease progression in allergic models are involved in aberrant alterations of both inflammatory responses and tissue cell growth.

Topics: Animals; Arachidonic Acids; Bronchitis; Cannabinoids; Chemokines; Cytokines; Dermatitis, Allergic Contact; Disease Models, Animal; Endocannabinoids; Female; Gene Expression; Glycerides; Growth Substances; HL-60 Cells; Humans; Hypersensitivity; Inflammation; Ligands; Mice; Mice, Inbred BALB C; Mice, Knockout; Receptor, Cannabinoid, CB2

Allergic contact dermatitis affects about 5% of men and 11% of women in industrialized countries and is one of the leading causes for occupational diseases. In an animal model for cutaneous contact hypersensitivity, we show that mice lacking both known cannabinoid receptors display exacerbated allergic inflammation. In contrast, fatty acid amide hydrolase-deficient mice, which have increased levels of the endocannabinoid anandamide, displayed reduced allergic responses in the skin. Cannabinoid receptor antagonists exacerbated allergic inflammation, whereas receptor agonists attenuated inflammation. These results demonstrate a protective role of the endocannabinoid system in contact allergy in the skin and suggest a target for therapeutic intervention.

Topics: Animals; Arachidonic Acids; Camphanes; Cannabinoid Receptor Modulators; Cannabinoids; Chemokines; Dermatitis, Allergic Contact; Dinitrofluorobenzene; Disease Models, Animal; Down-Regulation; Dronabinol; Endocannabinoids; Female; Glycerides; Mice; Mice, Inbred C57BL; Mice, Knockout; Oligonucleotide Array Sequence Analysis; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Rimonabant; Skin; Up-Regulation