Protective effect of polysaccharide nucleic acid fraction of bacillus Calmette-Guerin against atopic dermatitis in Nc/Nga mice / 中华皮肤科杂志

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,i nterleukin (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.