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.
ABSTRACT
Objective To determine the effect of bacille Calmette-Guerin-polysaccharide nucleic acid (BCG/PSN)on 2,4-dinitrochlorobenzene(DNCB)-induced atopic dermatitis-like skin lesions in Nc/Nga mice.Methods Fifteen mice were randomly and equally classified into 3 groups,i.e.,control group receiving topical acetone on foot pad and abdomen and intraperitoneal injection of physiological saline,model group receiving topical 5% DNCB solution and intraperitoneal injection of physiological saline,treatment group receiving 5% DNCB solution and intraperitoneal iniection of BCG/PSN,and all drugs were used every other day for 7 weeks.Further more,0.1% DNCB was topically applied on the ear and neck of Nc/Nga mice once a week from week 2 to week 7.The effects of BCG/PSN were evaluated by ear thickness,skin histopathology and immunological parameters.Results Repeated application of DNCB caused the development of eczematous dermatitis in mice.Mice in model group chnieally manifested skin dryness,erythema,edema and erosion with histopathological changes including dermal and epidermal thickening,hyperkeratosis,and inflammatory infiltration.The serum levels of IL-4 and IrE in model group were significantly higher than those in control group[(174.72±12.64)μg/L vs (17.32±3.56)μg/L,(91.49±6.32)ng/L vs (83.95±6.63)ng/L,both P<0.05].Increased serum IL-12 and IFN-γ and decreased serum IgE were observed in treatment group compared with the model group[(122.10±4.64)ng/L vs (20.14±6.15)ng/L(73.89±2.39)ng/L vs (51.53±3.45)ng/L, (84.27±9.35)μg/L vs (174.72±12.64)μg/L, all P<0.05].Conclusion BCG/PSN might be beneficial for the treatment of atopie dermatitis-like skin lesions in Nc/Nga mice by enhancing the secretion of IL-12 and IFN-γ and suppressing the synthesis of IgE.