Abstract: Guo Yanan*, Wang Lili, Wen Haiquan, Ren Yong, Li Song. *Shandong Provincial Hospital, Shandong University, Jinan 250021, China Corresponding author: Li Song, Email: 123250349@qq.com 【Abstract】 Objective To evaluate the protective effect of polysaccharide nucleic acid fraction of bacillus Calmette-Guerin （BCG-PSN） against atopic dermatitis （AD） in Nc/Nga mice, and to explore its possible mechanism. Methods Sixteen Nc/Nga mice were classified into normal control group （n = 4）, low-concentration BCG-PSN group （n=5） and high-concentration BCG-PSN group （n = 7） to be subcutaneously injected with sodium chloride physiological solution, BCG-PSN of 0.1 mg/kg and 0.5 mg/kg respectively, at 1, 8, 15 and 22 days of age. Dinitrochlorobenzene （DNCB） was repeatedly and topically applied to these Nc/Nga mice to induce AD-like lesions at 49 days of age. The preventive effect of BCG-PSN against AD was evaluated by dermatitis scores, scratching frequency, histopathological manifestations and immunological parameters （including IgE, interleukin （IL）-4 and -12, and interferon （IFN）-γ）. Results Repeated injection of BCG-PSN within 4 weeks after birth significantly decreased the severity of DNCB-induced AD-like lesions, dermatitis scores and scratching behavior in Nc/Nga mice. There was no statistical difference in scratching frequency between the high- and low-concentration BCG-PSN groups. BCG-PSN treatment reduced the plasma level of IgE in Nc/Nga mice in a dose-dependent manner. BCG-PSN at 0.5 mg/kg increased the number of cells secreting IFN-γ in skin lesions of mice. Both doses of BCG-PSN down-regulated IL-4 level, but up-regulated IL-12 level in the culture supernatant of spleen mononuclear cells from mice. Conclusion Early injection of BCG-PSN could protect Nc/Nga mice against dermatitis by promoting the proliferation of IFN-γ-secreting cells, increasing the synthesis of IL-12, and reducing the levels of IL-4 and IgE.

Key words: Dermatitis, atopic, Mice, Nc/Nga, Dendritic cells, BCG0-PSN