Cannabinoid receptor double knockout mice (Cnr1 -/- /Cnr2 -/-) in CHS model

We evaluated cutaneous contact hypersensitivity (CHS) in Cnr1-/-/Cnr2-/- animals using the obligate contact allergen 2,4-dinitrofluorobenzene (DNFB), which generates a specific cutaneous T-cell mediated allergic response upon repeated allergen contact. 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 whereas receptor agonists attenuated allergic inflammation. These results demonstrate a protective role of the endocannabinoid system in contact allergy in the skin, and suggest a novel target for therapeutic intervention. Keywords: Strain (Wt versus Ko) and disease state (DNFB treated versus control). Three wildtype mice (Wt) and three Cnr1-/-/Cnr2-/- (Ko) mice were used. Contact hypersensitivity was determined always at the right ears, which therefore were treated with DNFB (Tr). Left ears of mice were kept untreated and served as control ears (C). A total of 12 hybridizations were performed (2 strains x 2 treatments X 3 biological replicates) in this experiment.