Protease-resistant fraction of smoked, dried bonito alleviates atopic dermatitis-like skin lesions in NC/Nga mice.

The effect of smoke-dried bonito undigested fraction remaining after microbial protease treatment (SDBR) on a spontaneously occurring mouse model of atopic dermatitis was studied in male 5-wk-old, NC/Nga mice. Smoke-dried bonito, Katsuobushi, is a traditional Japanese food. SDBR contains 2 major components: bonito oil and protease-undigested proteins. Mice were fed a casein diet containing corn oil (C diet) or a diet containing SDBR (SDBR diet) for 18 wk. In comparison with the C diet, the SDBR diet alleviated the increase in skin severity score and plasma IgE concentration in a time-dependent manner, and lowered leucotriene B(4) (LTB(4))-releasing ability upon calcium ionophore A23187 stimulation. The SDBR diet did not affect scratching time. These results demonstrate that SDBR diet alleviates atopic dermatitis-like skin lesions in NC/Nga mice.