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目的探讨地塞米松对哮喘小鼠胸腺活化调节趋化因子(TARC)及其mRNA表达的影响。方法30只清洁级雄性BALB/C小鼠分为3组:正常对照组、哮喘组和地塞米松组。以卵清白蛋白(OVA)致敏激发法制备小鼠哮喘模型,末次激发24h后留取支气管肺泡灌洗液(BALF)及肺组织。BALF行嗜酸性粒细胞(EOS)计数及分类;采用酶联免疫吸附法(ELISA)测BALF中TARC和IL-4水平;免疫组化法和逆转录-聚合酶链反应(RT-PCR)法分别检测TARC蛋白和TARC mRNA在肺组织中的表达。结果①哮喘组BALF中细胞总数,EOS绝对数和EOS占细胞总数的百分数(EOS%)均显著高于正常对照组,地塞米松组上述指标均显著低于哮喘组(均P<0.01);②哮喘组BALF中TARC,IL-4浓度均显著高于对照组,地塞米松干预后BALF中TARC,IL-4浓度均显著低于哮喘组(均P<0.01)。③免疫组化及RT-PCR结果显示,肺组织中TARC蛋白及其mR-NA的表达,哮喘组显著高于对照组,地塞米松组较哮喘组显著减弱(均P<0.01),免疫组化显示,TARC蛋白主要表达于支气管上皮细胞。④相关性分析显示,小鼠BALF中TARC浓度与EOS绝对值、IL-4浓度均呈显著正相关(均P<0.01)。结论糖皮质激素(地塞米松)可抑制TARC在哮喘小鼠气道上皮中的表达,可能是其治疗哮喘气道炎症的部分作用机制。
Objective To investigate the effect of dexamethasone on thymic activation-regulated chemokine (TARC) and its mRNA expression in asthmatic mice. Methods Thirty clean-grade male BALB / C mice were divided into three groups: normal control group, asthma group and dexamethasone group. Mouse asthma model was induced by ovalbumin (OVA) sensitization and bronchoalveolar lavage fluid (BALF) and lung tissue were collected 24h after the last challenge. BALF count and classification of eosinophils (EOS); TARC and IL-4 levels in BALF were detected by enzyme-linked immunosorbent assay (ELISA); Immunohistochemistry and reverse transcription-polymerase chain reaction The expression of TARC protein and TARC mRNA in lung tissue were detected respectively. Results ① The percentage of total cells, EOS and EOS in the asthmatic BALF were significantly higher than those in the normal control group (P <0.01). The above indexes in the dexamethasone group were significantly lower than those in the asthma group (all P <0.01). ② The concentrations of TARC and IL-4 in BALF of asthma group were significantly higher than those in control group. The concentrations of TARC and IL-4 in BALF were significantly lower in dexamethasone group than those in asthma group (all P <0.01). ③ Immunohistochemistry and RT-PCR results showed that the expression of TARC protein and mR-NA in lung tissue was significantly higher in asthma group than that in control group (P <0.01) TARC protein is mainly expressed in bronchial epithelial cells. (4) Correlation analysis showed that there was a significant positive correlation between TARC concentration in BALF and EOS absolute value and IL-4 concentration (all P <0.01). Conclusion Glucocorticoids (dexamethasone) can inhibit the expression of TARC in the airway epithelium of asthmatic mice and may be part of its mechanism of action in the treatment of airway inflammation in asthma.