地塞米松对哮喘大鼠Th2细胞分化的影响

摘要

目的 研究糖皮质激素对哮喘大鼠肺组织Th2细胞分化的影响,探讨糖皮质激素治疗哮喘的可能机制.方法 24只SPF(无特定病原体)级SD(远交群)雄性大鼠随机分为3组,用卵清蛋白(OVA)建立哮喘模型:正常对照组、哮喘组、地塞米松组.留取支气管肺泡灌洗液(BALF)进行细胞计数及分类,采取ELISA法测定BALF中自细胞介素4(IL-4)的含量;应用免疫组化及流式细胞术测定肺组织中GATA-3(GATA binding protein 3)的表达.结果 哮喘组BALF中嗜酸性粒细胞占细胞总数百分比(EOS%)、淋巴细胞占细胞总数百分比(Lym%)、IL-4水平,显著高于正常对照组及地塞米松组(P＜0.01);免疫组化及流式细胞术显示,哮喘组GATA-3表达显著高于正常组及地塞米松组(P＜0.01);地塞米松组BALF中EOS%、Lym%和IL-4水平、肺组织GATA-3阳性表达与正常组比较差异无统计学意义(P＞0.05).结论 转录因子GATA-3及细胞因子IL-4的高表达,参与哮喘的病理生理过程:地塞米松可减少肺组织炎性细胞浸润,下调哮喘大鼠GATA-3、IL-4水平,提示其可抑制ThO细胞向Th2细胞分化,使Thl/Th2比例趋于平衡.%Objective To investigate the effects of dexamethasone on differentiation of T helper Ⅱ type cells in rat asthma model, to explore the mechanism of dexamethasone in the treatment of asthma. Methods Twenty-four male SD rats were randomly divided into three groups, which were control group, asthma group and dexamethasone-treatment group. The rat asthma model was challenged by ovalbumin (OVA). The cells in broncho-alveolar lavage fluid (BALF) were counted and classified. The concentrations of IL-4 in BALF were measured by sandwich enzyme-linked immunosorbent assay. The expression of GATA-3 protein in lung tissue was detected by immunohistochemistry and flow cytometry. Results 1) The percentage of eosinophils of total cell number (EOS％), the percentage of lymphocyte of total cell number (Lym％) and the concentration of IL-4 in asthma group were significantly higher than that in control group and dexamethasone-treatment group (P ＜ 0.01); 2) The results of immunohistochemistry and flow cytometry showed that the level of GATA-3 expression in lung tissue of asthma group was significantly higher than that in control group and dexamethasone-treatment group (P ＜ 0.01); 3) There were no significant difference between percentage of eosinophils of total cell number (EOS％), the percentage of lymphocyte of total cell number (Lym％), and IL-4 concentration in BALF and the GATA-3 positive expression in lung tissue in control group and in dexamethasone-treatment group (P ＞ 0.05). Conclusion The high expression of transcription factor GATA-3 and cytokine IL-4 in rat asthma model was involved in the patthogenesis asthma. Dexamethasone can down-regulate the expression of GATA-3 and IL-4, which indicated that it can inhibit the cell differentiation from Th0 to Th2, and regain the Th1/Th2 balance.