A Mouse Model for Atopic Dermatitis Using Topical Application of Vitamin D3 or of Its Analog MC903

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease with pruritus and high prevalence. Indeed, 15-30 % of children and 2-10 % of adults from industrialized countries are affected. Acute AD lesions are characterized by epidermal hyperplasia associated with a dominant Th2/Th17 immune response and dermal inflammatory infiltrates. Moreover, the expression of alarmins such as TSLP, IL-33, and IL-25 is upregulated in acute AD lesions. Topical application of vitamin D3 or of its low-calcemic analog MC903 induces changes in skin morphology and inflammation resembling immune perturbations observed in acute lesions of patients with AD. Mice treated with MC903 or vitamin D3 additionally display increased serum IgE levels, as observed in patients with extrinsic AD. Interestingly, these symptoms are not dependent on mouse gender or on genetic background. Thus, the easiness of this mouse model renders it very attractive to study immunologic abnormalities involved in AD development or maintenance. Furthermore, this model might be useful for preclinical studies aiming at unraveling new therapeutic strategies to treat AD. In this chapter, we describe the induction and major features of MC903 and vitamin D3-induced AD-like inflammation in mice.