Allergic contact dermatitis (ACD) is caused by reaction to something that directly contacts with the skin. It can be caused by many different substances called allergens.
Usually these substances cause no trouble for most people, and may not even be noticed the first time the person is exposed. But once the skin becomes sensitive or allergic to the substance, any exposure will produce a rash. The rash usually doesn't start until a day or two later, but can start a soon as hours or as late as a week.
In earlier work, Prof. Raphael Mechoulam's research group at the Hebrew University isolated two naturally occurring cannabinoid (cannabis-like) components - one from the brain, named anandamide, and another from the intestines named 2-AG. These two cannabinoids, plus their receptors and various enzymes that are involved in the cannnabinoids' syntheses and degradations, comprise the endocannabinoid system.
These materials have similar effects to those of the active components in hashish and marijuana, produced from the cannabis plant.
As part of this study, a team of researchers including Dr Andreas Zimmer and Prof. Mechoulam tested the endocannabinoid system as a major regulator of cutaneous (skin) contact hypersensitivity (CHS) in a mouse model.
The researchers found that mice lacking cannabinoid receptors displayed intensified inflammatory skin responses to an allergen.
In order to better understand the molecular mechanism that might contribute to the increased CHS in cannabinoid-receptor deficient mice, the researchers performed a series of experiments which showed that mouse skin cells produce a specific chemical (a chemokine) which is involved in the annoying disease reaction. Activation of the endocannabinoid system in the skin upon exposure to a contact allergen lowers the allergic responses through modulating the production of this chemokine.
The results thus clearly showed a protective role for the endocannabinoid system in contact allergy in the skin and suggested that development of cannabinoid compounds based on elements produced from the cannabis plant could enhance therapeutic treatment for humans.
The findings of the study were published in the journal Science.