甲壳质抗特应性皮炎的实验研究

Role of chitin in controlling atopic dermatitis(AD)——study on a murine AD model

目的：探讨甲壳质对卵清蛋白（OVA）诱导的小鼠特应性皮炎（AD）的作用。方法：28只BALB/c小鼠随机分成3组：对照组（N组）（8只）、模型组（M组）（10只）、甲壳质组（E组）（10只）。通过小鼠腹腔注射及背部皮肤外敷OVA建立AD动物模型（模型组）,甲壳质组在建模过程中同时给予3 mg/d甲壳质灌胃4周。建模成功后处死小鼠,取背部皮肤,进行石蜡切片HE和甲苯胺蓝染色,显微镜下观察表皮和真皮厚度的变化以及细胞浸润情况;ELISA法检测血清中总Ig E、总Ig G2a和OVA-specific Ig E的水平;取脾细胞进行体外培养,ELISA法测定培养液中细胞因子的含量。结果：与模型组小鼠比较,甲壳质组小鼠皮肤激发处炎症症状较轻,皮肤表皮层与真皮层增厚程度降低,真皮内炎症细胞浸润总量（P〈0.05）、嗜酸性粒细胞数量及肥大细胞数量（P〈0.01）明显减少。甲壳质组小鼠血清中总Ig E和OVA-specific Ig E的水平都明显降低（P〈0.05~0.001）,Ig G2a水平显著升高（P〈0.001）。甲壳质组小鼠脾细胞体外培养产生的IL-12及IFN-γ水平明显高于模型组,而IL-4水平明显低于模型组（P〈0.05）。结论：甲壳质能有效减轻OVA诱导的小鼠AD症状,降低小鼠血清中Ig E水平,甲壳质的抗过敏作用可能与其诱导AD小鼠脾细胞产生Th1型细胞因子（IL-12、IFN-γ）有关。

Objective：To investigate the effects of chitin on atopic dermatitis in an OVA induced AD murine model. Methods： Twenty-eight BALB/c mice were randomly divided into three groups：the normal control group （N） （8）, the chitin group （E） （10） and the AD model group （M） （10）. The murine model of atopic dermatitis was established through intraperitoneal injection of OVA followed by repeated epicutaneous application of OVA on mice back skin（ AD model group）. During the set up of AD murine model, mice of the chitin group were given intragastric gavage of 3 mg/d for 4 weeks. At the end of the experiment, the mice were sacrificed and skin lesions were biopsied for histological study. HE and O-toluidine stained paraffin sections were observed under microscope. The spleen ceils were cultured and challenged with OVA and chitin, respectively, the supernatant was obtained for cytokine determination. Serum levels of total and OVA-specific IgE and total IgG2a were determined with ELISA. Results： Chitin significantly inhibited skin inflammation induced by OVA. Compared with the AD model group, the thickness of the epidermis and dermis in the chitin group were obviously decreased. The numbers of dermal infiltrated inflammatory cells, eosinophils and mast cells were significantly decreased in the chitin group compared with the AD model group （ P 〈 O. 05 - O. 001 ）. The serum level of total IgE and OVA-specific IgE were significantly lower in the chitin group than in the AD model group（ P〈0. 05-0. 001 ） ,while the serum level of IgG2a in the chitin group was significantly higher than that of the AD model group（P〈0. 001 ）. The cultured spleen cells of the chitin group produced significantly higher levels of IL-12 and IFN-y, but lower level of IL-4 compared with those of the AD model group after OVA challenge （P〈0.05）. Conclusion：Chitin can inhibit the inflammation and decease the scum level of IgE in the murine AD model. The antiallergic effect of chitin might be associated with the induced production of Thl type cytokines by mice spleen cells.