The Leaves of Broussonetia kazinoki Siebold Inhibit Atopic Dermatitis-Like Response on Mite Allergen-Treated Nc/Nga Mice

Broussonetia kazinoki Siebold. (B. kazinoki) has long been used in the manufacture of paper in Asian countries. Although B. kazinoki leaves (BK) have been employed in dermatological therapy, use of BK has not been tested in patients with atopic dermatitis (AD). Using Nc/Nga mice, which are genetically predisposed to develop AD-like skin lesions, we confirmed the efficacy of BK in AD treatment. BK extract was applied topically to Dermatophagoides farinae-induced AD-like lesions in Nc/Nga mice, and the effects were assessed both clinically and by measuring skin thickness on the back and ears. We measured the effects of BK extract on plasma levels of IgE and IL-4. We also measured the ability of BK extract to inhibit the secretion of hTARC in HaCaT cells after stimulation by TNF-${\alpha}$ and IFN-${\gamma}$. We found that BK extract significantly reduced ear and dorsal skin thickness and the clinical signs of AD, as well as significantly down-regulating the plasma levels of IgE and IL-4 (p<0.01 for each comparison). Moreover, $500{\mu}g/mL$ of BK extract inhibited hTARC secretion in HaCaT cells by activated TNF-${\alpha}$/IFN-${\gamma}$ by about 87%. These findings suggest that topical application of BK extract has excellent potential in the treatment of AD.