ABSTRACT
BACKGROUND: Topical tacrolimus is widely used for the treatment of inflammatory skin diseases like atopic dermatitis, but there are few studies about the effect of topical tacrolimus for allergic contact dermatitis. Allergic contact dermatitis develops in two phases, the clinically silent sensitization phase, and the clinically apparent elicitation phase. OBJECTIVE: The purpose of this study is to investigate whether topical tacrolimus has an effect on both phases of murine contact hypersensitivity and dermatitis of repeated applications induced by diphenylcyclopropenone (DPCP). METHODS: Hairless mice were treated with topical tacrolimus before and after DPCP challenging. The suppressive effect of topical tacrolimus was measured by skin erythema, ear swelling, weight change and cell numbers of local lymph nodes. In addition, a biopsy was carried out and epidermal hyperplasia was investigated microscopically. TNF-alpha mRNA on the mice which were treated with topical tacrolimus to one side of the ears was measured before and after being chronically challenged with DPCP on both ears. RESULTS: Topical tacrolimus pretreatment dramatically supressed inflammatory reactions in the sensitization phase, and treatment of topical tacrolimus after sensitization dramatically supressed inflammatory reactions in the elicitation phase. Topical tacrolimus also dramatically supressed inflammatory reactions in the repeated DPCP-induced dermatitis. CONCLUSION: The data revealed topical tacrolimus could effectively suppress murine contact hypersensitivity and dermatitis of repeated applications induced by DPCP. Putting these results together, topical tacrolimus can be very effective in not only the treatment but also the prevention of allergic contact dermatitis. Larger studies are needed to determine the clinical relevance.