Quantitative evaluation of the therapeutic effect of fermented soybean products containing a high concentration of GABA on phthalic anhydride-induced atopic dermatitis in IL-4/Luc/CNS-1 Tg mice

Cheonggukjang (CKJ) is a fermented soybean product that exhibits diverse biological and pharmacological activities, including anti-obesity, anti-diabetic, and anti-inflammatory effects on human chronic diseases. In this study, the effects of the aqueous extract of CKJ containing a high concentration of GABA on atopic dermatitis (AD) were quantified using the luciferase reporter system in IL-4/Luc/CNS-1 transgenic (Tg) mice. Alterations of the luciferase signal and phenotypes of AD were quantified in the IL-4/Luc/CNS-1 Tg mice co-treated with phthalic anhydride (PA) and CKJ for 4 weeks using the IVIS imaging system. A strong luciferase signal was detected in the abdominal region of IL-4/Luc/CNS-1 Tg mice treated with PA alone. However, this signal was significantly reduced in IL-4/Luc/CNS-1 Tg mice co-treated with PA and CKJ. The thymus showed the greatest decrease in luciferase following CKJ treatment, but the level increased after PA treatment. Furthermore, the CKJ-treated group showed improvement of common allergic responses including decreased ear thickness, dermis thickness, auricular lymph node (ALN) weight and infiltrating mast cells. However, IgE concentration and epidermis thickness were maintained a constant level. These results indicated that the luciferase signal may successfully reflect the therapeutic effects of CKJ in IL-4/Luc/CNS-1 Tg mice. The results also suggested that CKJ may be considered an effective substance for the treatment of AD.