Attenuation of Allergic Contact Dermatitis Through the Endocannabinoid System

Abstract

Karsak M, Gaffal E, Date R, et al. Science. 2007;316(5830):1494–1497 PURPOSE OF THE STUDY. To assess the role of cannabinoid receptors in allergic contact dermatitis. STUDY POPULATION AND METHODS. The study was conducted in an animal model for cutaneous contact hypersensitivity using wild-type mice and also those lacking cannabinoid receptors (CB1 and CB2). RESULTS. 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. CONCLUSIONS. These results demonstrate a protective role of the endocannabinoid system for contact allergy in the skin and suggest a target for therapeutic intervention. REVIEWER COMMENTS. This very clever study was based on an observation that mice lacking cannabinoid receptors tended to develop an itchy dermatitis at the site of nickel-containing ear tags. From this simple observation, the authors conducted a series of well-designed experiments that demonstrated that the cannabinoid receptors help to regulate cell recruitment to sites of inflammation in the context of contact dermatitis. These results have led to new insights to the pathogenesis of this disorder and may lead to a new treatment for contact dermatitis. I wonder if cannabinoid receptors are involved in other forms of skin allergy.