卡介苗多糖核酸对年幼期哮喘大鼠细支气管STAT6及其mRNA表达的影响

Effects of BCG-PSN on the expression of signal transducer and activator of transcription 6 and its mRNA in the bronchioles in a young rat model of allergic asthma

目的:研究卡介苗多糖核酸(BCG-PSN)对哮喘大鼠细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:30只SPF级幼年雄性SD大鼠随机分为对照组、哮喘组和BCG-PSN治疗组。将支气管肺泡灌洗液(BALF)中炎性细胞进行分类计数;测定BALF和血清中白细胞介素4(IL-4)浓度;采用SP法和原位杂交法分别检测STAT6及其mRNA的表达。结果:①哮喘组BALF中EOS绝对值和EOS占细胞总数的百分比(EOS%)均高于对照组(P<0.01),而BCG-PSN组上述指标均低于哮喘组(P<0.01);②哮喘组BALF和血清中IL-4浓度均高于对照组(均P<0.01),而BCG-PSN组均低于哮喘组(均P<0.01);③哮喘组STAT6及其mRNA表达均高于对照组,BCG-PSN组则均低于哮喘组(均P<0.01),其主要表达细胞是细支气管上皮细胞。结论:BCG-PSN能削弱STAT6及其mRNA的表达,使IL-4合成减少,这可能是其抑制哮喘气道炎症的重要作用机制。

Objective： To study the effect of polysaccharides nucleic acid fraction of BCG（BCG-PSN）on the expression of signal transducer and activator of transcription 6（STAT6）and its mRNA in the lungs of a rat model of asthma.Methods： Thirty SPF grade young male SD rats were randomly divided into three groups： the control group,asthma group and BCG-PSN group.The inflammatory cells in bronchoalveolar lavage fluid（BALF）were differentially counted by different count fluids.The concentration of IL-4 in serum and BALF were measured with sandwich ELISA.The protein expressions of STAT6 were detected with immunohistochemistry techniques,and the mRNA expression of STAT6 were detected with hybridization in situ,respectively.Results： ①The absolute numbers of EOS in BALF,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 absolute numbers of EOS and EOS% of BCG-PSN group were all significantly lower than those of asthma group（P 0.01）.②The concentrations of IL-4 in BALF and serum of asthma group were significantly higher than those of control group（P 0.01）,while the concentrations of IL-4 in BALF and serum of BCG-PSN group were significantly lower than those of asthma group.③Immunohistochemistry and hybridization in situ showed that the content of STAT6 and STAT6mRNA expression in the lungs of asthma group were higher than those of the control group,while those of BCG-PSN group were all significantly lower than those of the asthma group（P 0.01）,the epithelial cells of bronchioles were the chief expression cells.Conclusion： BCG-PSN signifi-cantly depresses STAT6 and its mRNA expression,thus reduces the synthesis of IL-4 may be the key in an inhibitory effect on airway inflammatory cells in modulating mechanism of asthma.