甘草酸对小鼠特应性皮炎炎症的影响及机制研究

Impact of glycyrrhizin on atopic dermatitis in mice model

目的:探讨甘草酸对实验性特应性皮炎(atopic dermatitis,AD)炎症的抑制作用及可能机制。方法:用2,4-二硝基氯苯(2,4-dinitrochlorobenzene,DNCB)在6~8周龄雌性BALB/c小鼠建立实验性特应性皮炎模型。将小鼠分为4组:对照组,甘草酸治疗组(分别50 mg/kg、20 mg/kg和10 mg/kg)每天腹腔注射。分别在第8、15天,HE染色观察皮肤病理学改变,用qRT-PCR方法测定局部皮损组织Th2型细胞因子的mRNA水平。同时,在第15天,取小鼠脾淋巴细胞体外培养,刀豆蛋白刺激24 h后,ELISA检测Th2型细胞因子的表达。结果:在第8天,与对照组相比,甘草酸各治疗组的皮肤病理学改变、局部皮损中细胞因子的mRNA水平以及脾淋巴细胞分泌的细胞因子无统计学差异。但在第15天,与对照组表皮厚度(194.00±18.43)和真皮厚度(374.70±40.01)比较,甘草酸50 mg/(kg·d)治疗组小鼠表皮厚度(141.00±7.61)(P=0.005)和真皮厚度(281.20±69.42)(P=0.012)显著降低。qRT-PCR结果显示皮损中白介素(inteleukin,IL)-4 mRNA(0.036±0.011)和IL-13 mRNA(0.051±0.022)水平分别低于对照组(0.073±0.007,0.100±0.015)(P=0.000,P=0.001)。ELISA方法检测脾淋巴细胞分泌的IL-4(42.94±9.26)和IL-13(43.34±12.59)均明显低于对照组(61.87±10.20,77.42±10.71)(P=0.002,P=0.000)。结论:甘草酸能缓解小鼠特应性皮炎皮肤炎症,可能是通过下调Th2细胞因子水平发挥作用。

Objective：To investigate the effect of glycyrrhizin on atopic dermatitis in mice model.Methods：A model of atopic dermatitis was established in 6-8-week-old female BALB/c mice by applying 2,4-dinitrochlorobenzene（DNCB）to shaved dorsal skin.During the process of establishment of model,the mice were divided into four groups：control group,three glycyrrhizin groups treated with50 mg/（kg·d）,20 mg/（kg·d）and 10 mg/（kg·d）,respectively.The treatment lasted for 14 days.On day 8 and 15,dorsal skin tissue samples were obtained from these mice and for the observation of histopathological changes by using hematoxylin and eosin（HE）staining.The mRNA levels of Th2 cytokines were evaluated by qRT-PCR.Enzyme linked immunosorbent assay（ELISA）was carried out to determine the levels of IL-4 and IL-13,secreted by spleen lymphocytes followed by stimulation of Con A.Results：Compared with the control mice,those treated with different doses of glycyrrhizin showed no difference in pathological changes of skin tissue and mRNA levels and cytokine production of IL-4 and IL-13 on day 8 after the treatment.However,on day 15,dermal and epidermal thickness of skin lesions（141.00±7.61）vs.（194.00±18.43）;（281.20±69.42）vs.（374.70±40.01）（P=0.005,P=0.012,respectively）as well as the mRNA expression of IL-4（0.036±0.011 vs.0.073±0.007,respectively）and IL-13（0.051±0.022 vs.0.100±0.015）（P=0.000,P=0.001,respectively）and the levels of IL-4（42.94±9.26 vs.61.87±10.20）and IL-13（43.34±12.59）vs.（77.42±10.71）（P=0.002,P=0.000,respectively）secreted by spleen lymphocytes from mice treated with glycyrrhizin 50 mg/（kg·d）group showed a significantly decrease compared with those of control mice.Conclusion：Glycyrrhizin can inhibit the inflammation in mice model of atopic dermatitis,possibly by down regulating the expression cytokines of type T helper2 cells.