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目的研究哮喘大鼠支气管信息传递与转录活化因子6(STAT6)的表达和地塞米松(DXM)对其表达的影响。方法30只体重120～180g的二级幼年雄性SD大鼠,随机分为3组:正常对照组(A组)、哮喘组(B组)、地塞米松组(DXM组)。对支气管肺泡灌洗液(BALF)进行细胞总数、嗜酸性粒细胞(EOS)计数和分类计数;应用双抗体夹心酶联免疫吸附试验法测定BALF和血清中白细胞介素4(IL4)浓度;采用免疫组化法和原位杂交法分别检测支气管STAT6蛋白和STAT6mRNA的表达。结果(1)B组支气管STAT6蛋白和STAT6mRNA表达[(0.171±0.025),(0.180±0.013)]均高于A组[(0.082±0.022),(0.091±0.012)]和DXM组[(0.114±0.013),(0.114±0.010)](均为P<0.01),其主要表达细胞是上皮细胞;(2)支气管STAT6蛋白、STAT6mRNA分别与BALF中的IL4浓度呈显著正相关(r=0.664、0.785,P<0.01),STAT6蛋白、STAT6mRNA分别与BALF中的EOS绝对值呈显著正相关(r=0.869、0.884,P<0.01)。结论哮喘大鼠支气管有STAT6的较强表达,上皮细胞是其主要表达细胞;地塞米松可以下调STAT6的表达,可能为其抑制哮喘气道炎症形成的重要作用机制。
Objective To investigate the expression of signal transducer and activator of transcription 6 (STAT6) and the effect of DXM on the expression of asthma in asthmatic rats. Methods Thirty young male Sprague-Dawley rats weighing 120 ~ 180g were randomly divided into three groups: normal control group (group A), asthma group (group B) and dexamethasone group (DXM group). The total number of cells, eosinophils (EOS) count and classification of bronchoalveolar lavage fluid (BALF) were counted. The concentrations of interleukin 4 (IL4) in BALF and serum were determined by double antibody sandwich enzyme-linked immunosorbent assay The expression of STAT6 protein and STAT6 mRNA in bronchus were detected by immunohistochemistry and in situ hybridization. Results (1) The expression of STAT6 protein and STAT6 mRNA in bronchus in group B were significantly higher than those in group A [(0.171 ± 0.025) and (0.180 ± 0.013)], respectively (0.082 ± 0.022 and 0.091 ± 0.012) 0.013), (0.114 ± 0.010)] (all P <0.01), and the main expressed cells were epithelial cells. (2) The expressions of STAT6 and STAT6 mRNA in bronchial epithelial cells were positively correlated with the concentration of IL4 in bronchoalveolar lavage fluid (r = 0.664, , P <0.01). There was a significant positive correlation between STAT6 protein and STAT6 mRNA and the absolute value of EOS in BALF (r = 0.869,0.884, P <0.01). Conclusions The expression of STAT6 in bronchus of asthmatic rats is stronger than that in epithelial cells. Dexamethasone down-regulates the expression of STAT6, which may be an important mechanism of its inhibition of airway inflammation in asthma.