卡介菌多糖核酸对哮喘小鼠胸腺活化调节趋化因子及mRNA表达的影响

Effects of BCG-PSN on the expression of thymus and activation-regulated chemokine and mRNA in a murine model of allergic asthma

目的观察卡介菌多糖核酸(BCG-PSN)对小鼠哮喘胸腺活化调节趋化因子(thymus and activation regulated chemo-kine,TARC)及mRNA表达的影响。方法以卵清白蛋白(OVA)致敏和激发建立小鼠哮喘模型。30只清洁级♂Balb/c小鼠随机分为3组,每组10只:正常对照组、哮喘组、BCG-PSN治疗组。末次激发24h后留取支气管肺泡灌洗液(BALF)及肺组织。BALF行细胞计数及分类;应用酶联免疫吸附试验(ELISA)法测定BALF中TARC、IL-4和IFN-γ蛋白的浓度;光镜观察肺组织病理变化;逆转录-聚合酶链反应(RT-PCR)法测定肺组织中TARC mRNA的表达;采用免疫组织化学法测定肺组织中TARC蛋白的表达。结果与正常对照组相比,哮喘组BALF中细胞总数、嗜酸粒细胞(EOS)绝对值及百分比、TARC和IL-4浓度、肺组织中TARC蛋白及mRNA的表达均增高,BALF中IFN-γ浓度低于正常对照组。经BCG-PSN干预后,BALF中细胞总数、EOS绝对数及百分比,TARC、IL-4浓度较哮喘组均下降,肺组织中TARC蛋白及mRNA的表达较哮喘组均下调,BALF中IFN-γ浓度较哮喘组增高。免疫组化显示TARC蛋白主要表达于支气管上皮细胞。BALF中TARC浓度与EOS绝对值、IL-4浓度呈正相关。结论卡介菌多糖核酸可降低TARC在肺组织中的表达,降低气道炎症。

Aim To observe the effects of Polysaccharides nucleic acid fraction of BCG （BCG-PSN） on the expression of thymus and activation-regulated chemokine protein and mRNA in a murine model of allergic asthma. Methods The asthmatic models were established by ovalbumin （OVA） sensitized and challenged in murine. Thirty male Balb/c mice were randomly divided into three groups on average, including control group （ group A ）, asthma group （ group B ） and BCG- PSN group （group C ）. Bronchoalveolar lavage fluid （BALF） and lung tissues were collected from mice 24 hours after the last challenge. The total cell numbers and the cell differentials of BALF cells were counted. The levels of TARC and IL-4 and IFN-γ in BALF were measured by enzyme-linked immunosorbent assay （ELISA）. The pathological changes of lung tissue were observed under light microscopy. The expression of TARC mRNA were detected by reverse transcription polymerase chain reaction （RT-PCR） and the expression of TARC protein was detected by immunohistochemistry. Results Compared with control group, the total cell numbers, the absolute numbers of eosinophils （EOS）, the ratios of EOS to the total cell numbers （EOS%） and the levels of TARC and IL-4 in BALF were markedly higher, and the expression of TARC protein and mRNA in lung were also raised in asthma group. The concentrations of IFN-γ in BALF of asthma group were significantly lower than those in control group. The above measured values in BALF were decreased with treatment of BCG-PSN. The expression of TARC protein and mRNA in lung were also reduced in BCG-PSN treated group. The concentrations of IFN-γ in BALF of BCG-PSN group were significantly higher than those in asthma group. Immunohistochemistry showed that the predominant cells in lung tissues that expressed TARC were epithelial cells. Strong positive correlations were found between TARC and absolute numbers of EOS and IL-4 in BALF. Conclusion BCG-PSN can significantly decrease the expression of TARC in murine model of asthma and reduce airway inflammation.