Acidification of Stratum Corneum Prevents the Progression from Atopic Dermatitis to Respiratory Allergy

The presence of congenitally impaired skin barrier followed by atopicdermatitis (AD) is an initial step in the atopicmarch. The maintenance of acidic pH in the stratum corneum(SC) has been suggested as a therapeutic or preventive strategy for barrier impairment caused by skin inflammation. To determine whether an ADmurine model, flaky tail mice, with inherited filaggrindeficiency could develop airway inflammation by repeated topical application followed by nasal inhalation of house dust mite(HDM) antigen (defined as a novel " atopicmarch animal model"), and whether maintenance of an acidic SC environment by continuous application of acidic creamcould interrupt the following atopicmarch. During the course of HDM treatment, acidic cream(pH2.8) or neutral cream(pH7.4) was applied to flaky tail mice twice daily. Repeated applications and inhalations of HDM to flaky tail mice induced AD skin lesions followed by respiratory allergies. Maintenance of SC acidity inhibited the occurrence of respiratory allergic inflammationas well as AD-like skin lesions. Collectively, a novel atopicmarch model could be developed by repeated epicutaneous and nasal applications of HDM to flaky tail mice, and that the acidification of SC could prevent the atopicmarch from AD to respiratory allergy.