目的观察黄芪(Radix Astragali,RA)对支气管哮喘大鼠支气管信号转导子和转录激活子6(STAT6)及其mRNA表达的影响。方法用卵清白蛋白建立哮喘模型,SD大鼠随机分成4组:正常对照组、模型组、低剂量RA组和高剂量RA组。留取支气管肺泡灌洗液(BALF)进行嗜酸性粒细胞(EOS)和分类计数;采用免疫组化法和原位杂交法分别检测STAT6蛋白和STAT6 mRNA的表达。结果①模型组BALF中EOS绝对值和EOS占细胞总数的百分比(EOS％)均显著高于正常对照组(P<0.01), 黄芪组上述指标均显著低于模型组(P<0.01);②免疫组化和原位杂交显示,模型组支气管STAT6蛋白和STAT6 mRNA表达均显著高于正常对照组,黄芪组较模型组均明显减弱(均为P<0.01),其主要表达细胞是上皮细胞;③支气管STAT6蛋白、STAT6 mRNA分别与BALF中的EOS绝对值呈显著正相关。结论黄芪有抑制哮喘气道EOS性炎症的作用,其机制可能与其下调 STAT6及其mRNA的表达有关。

OBJECTIVE To study the effect of Radix Astragali (RA) on the expression of signal transducer and activator of transcription6 (STAT6) and its mRNA in the bronchus of a rat asthma model.METHODS Forty male SD rats were randomly divided into four groups: the control group,asthma group, AM group treated with high dose,and low dose, respectively. In the experiment, the rat asthma model was established by the ovalbumin(OVA) challenge methods. The lung tissue was gained from the left lung, bronchoalveolar lavage fluid (BALF) was gained from the right lung. The Eosinophils(EOS) numbers and differentiated cell numbers in BALF were counted; the protein expressions of STAT6 were detected by immunohistochemistry techniques; the mRNA expressions of STAT6 were detected by hybridization in situ. RESULTS The total cell numbers in BALF, the absolute numbers of EOS, the ratios of eosinophils to the total cell numbers (EOS%) of asthma group were all significantly higher than those of the control group(P<0.01); The total cell numbers in BALF, the absolute numbers of EOS and EOS% of RA groups were all significantly lower than those of asthma group (P<0.01) . Immunohistochemistry showed that the protein content of STAT6 around the bronchus of asthma group was significantly higher than that of the control group (P<0.01) , while that of RA groups were significantly lower than that of asthma group, the epithelial cells were the chief expression cells; hybridization in situ showed that the mRNA expression of STAT6 around the bronchus of asthma group was significantly higher than that of the control group (P<0.01), while that of RA groups was significantly lower than that of asthma group, the epithelial cells were the chief expression cells. There was a significant correlation between the absolute numbers of EOS in BALF, the content of STAT6 and STAT6mRNA respectively in the epithelial cells of bronchus(P<0.01) .CONCLUSION RA had an inhibitory effect on airway inflammation cells infiltration such as EOS, it significantly depressed STAT6 and its mRNA expression may be key in the modulating mechanism of asthma.