METHODS: Five-week-old female NC/Nga mice were topically treated with 100 mg of HDM on dorsal skin twice a week and were also exposed to airborne HCHO in a chamber for 4 hours a day for 6 days. These mice were divided into 4 groups: (1) negative control group, (2) house dust mite (HDM) group in which HDM was topically applied on the skin, (3) HDM plus 2 ppm HCHO-exposed group and (4) HDM plus 5 ppm HCHO-exposed group. After the exposure, the dorsal skin of mice was collected to estimate the clinical severity, histology and expression of cytokines and structural proteins.
RESULTS: Topical application of HDM increased epidermal thickness, the number of degranulated mast cells in dermis, and the severity of skin lesions. In HDM plus HCHO-exposed group, epidermal thickness, the severity scores and mast cell degranulation was significantly increased than in HDM group. The exposure to airborne HCHO at 2 ppm caused abnormal processing of profilaggrin to filaggrin, and also reduced the expression level of sodium hydrogen exchanger 1 (NHE1), a regulator of pH in the skin.
CONCLUSIONS: Our results suggest that airborne HCHO exposure to the skin in AD might aggravate skin barrier dysfunction by activating mast cells and altering the expression of filaggrin and NHE1.
Funding support: This study was funded by Environmental Health Research Center Project by the Ministry of Environment (MOE), Republic of Korea.