Coal tar soap is one of the oldest remedies for atopic dermatitis,a.k.a. eczema, but it is unclear exactly why this treatment is effective.
In the Journal of Clinical Investigation, Ellen van den Bogaard and colleagues at Radboud University in Nijmegen, the Netherlands, identified the aryl hydrocarbon receptor (AHR) as the molecular target of coal tar.
Using a skin model of atopic dermatitis, van den Bogaard and colleagues demonstrated that coal tar activates AHR to diminish cell death, expression of inflammatory proteins, and skin cell swelling (spongiosis), and restored barrier proteins that maintain skin integrity.
In a companion commentary, Irwin McClean and Alan Irvine of the University of Dundee, detail the history of coal tar as a therapeutic and discuss how these findings could be used to identify new therapies for atopic dermatitis.
TITLE:Coal tar induces AHR-dependent skin barrier repair in atopic dermatitis
ACCOMPANYING COMMENTARY:Old King Coal – molecular mechanisms underlying an ancient treatment for atopic eczema