烟曲霉暴露对支气管哮喘大鼠气道黏蛋白MUC2表达的影响

Effects of chronic Aspergillus fumigatus exposure on the expression of mucin MUC2 in the airways of asthmatic rats

目的研究烟曲霉暴露对支气管哮喘（简称哮喘）大鼠气道黏蛋白MUC2表达的影响。方法70只雄性Wistar大鼠随机数字表法分为7组（每组10只）：慢性哮喘（A）组、慢性哮喘＋烟曲霉孢子吸入1周（B）组、3周（C）组和5周（D）组、慢性哮喘＋生理盐水吸入（E）组、卵清白蛋白（OVA）致敏生理盐水激发（F）组和OVA致敏生理盐水激发＋烟曲霉孢子吸入（G）组。测定各组大鼠的基础气道阻力和气道阻力变化率，ELISA法测定支气管肺泡灌洗液（BALF）中IL-13水平，RT—PCR法检测肺组织MUC2mRNA水平，免疫组织化学染色测定气道上皮细胞MUC2表达强度。结果D组大鼠基础气道阻力为（1．06±0．28）cmH2O·ml^-1·s^-1、气道阻力变化率为（85．69±5．68）％、BALF中IL-13为（197±34）mg／L肺组织MUC2 mRNA／β-actinm RNA为（3．0±0．6）、气道上皮细胞MUC2表达强度（A值）为（871±70）均高于A组[（O．52±0．13）cmH2O·ml^-1·s^-1、（31．62±3．62）％、（54±9）mg／L、（1．8±0．4）、（202±36）]、B组[（O．54±0．14）amH2O·ml^-1·s^-1、（35．90±2．62）％、（96±16）mg／L、（1.9±0．3）、（258±48）]、C组[（O．89±0．22）cmH2O·ml^-1·s^-1、（60．91±4．26）％、（136±22）mg／L、（2．3±0．5）、（546±53）]和E组[（60．91±4．26）cmH2O·ml^-1·s^-1、（31．64±3．47）％、（37±8）mg／L、（1．7±0．4）、（188±39）]（P〈O．01或P〈0．05）；A组高于F组[（O．33±0．08）cmH2O·ml^-1·s^-1、（16．85±3．62）％、（23±6）mg／L、（0．5±0．2）、（87±18）]和G组[（0．34±0．12）cmH2O·ml^-1·s^-1、（16．52±3．34）％、（25±6）mg／L、（O．5±0．1）、（88±15）]（P〈O．01或P〈O．05）；大鼠肺组织MUC2 mRNA／β-actin mRNA和气道上皮细胞MUC2表达强度（A值）均与BALF中IL-13水平正相关（r=0．648，P〈0．05；r=0．676，P〈O．05），与气道阻力变化率正相关（r=0．644，P〈0．05；r=0．584，P〈0．05）。结论慢性烟曲霉暴露可上调哮喘大鼠气道黏蛋白MuC2基因表达，气道黏液分泌增多，黏稠度和黏滞度增加，导致气道反应性增高。

Objective To explore the effects of chronic Aspergillus fumigatus exposure on the expression of mucin MUC2 in the airways of asthmatic rats. Methods Seventy male Wistar rats were randomly divided into 7 groups： chronic asthma group （group A）, chronic asthma plus Af spores inhalation for 1 week （group B）, 3 weeks （group C） and 5 weeks （group D）, chronic asthma plus saline inhalation for 5 weeks （group E）, OVA-sensitized and-saline-challenged group （group F） and OVA- sensitized and-saline-challenged plus Af spores inhalation for 5 weeks （group G） （each n= 10）. The airway resistance and change rate after administration of acetylcholine chloride were measured using a computerized system, the IL-13 levels in BALF were measured by ELISA, the levels of MUC2 mRNA in the rat lung tissues were measured by RT-PCR, and the expressions of mucin MUC2 were demonstrated by immunohistochemistry. Results The basic airway resistance in group D was （1.06 ±0.28）cmH2O·ml^-1·s^-1, the change rate of airway resistance after administration of acetylcholine chloride was （85.69±5.68）%, the IL-13 level in BALF was （197-±-34） mg/L, the MUC2 mRNA/β-aetin mRNA in lung tissues was （3.0±0.6）, and the muein MUC2 expression level in airway epithelial cells（value A） was （871±70）, all were higher than that in group A [（0.52±0.13） cmH2O·ml^-1·s^-1 ,（31.62±3.62）%, （54±9） mg/L,（1. 8±0. 4）,（202±36）], group B [（0. 54±0. 14） cmH2O·ml^-1·s^-1,（35.90± 2.62）%,（96±16） mg/L,（1.9±0.3）,（258±48）], group C [（0.89±0.22）cmH2O·ml^-1·s^-1, （60.91±4.26）%,（136±22） mg/L,（2.3±0.5）,（546±54）] and group E [（60.91±4.26） cmH2O·ml^-1·s^-1,（31.64±3.47）%,（37i8） mg/L,（1.7±0.4）,（188±39）]（P 〈0.01 or P 〈0.05, respectively）. The indexes in group A were higher than that in group F [（0.33±0.08） cmH2O·ml^-1·s^-1 ,（16.85±3.62）%,（23±6） mg/L,（0.5±0.2）,（87±18）] and in group G [（0.34±0.12）cmH2O·ml^-1·s^-1,（16.52±3.34）%, （25± 6） mg/L, （0.5±0.1）, （88± 15）] （P 〈0.01 or P 〈0.05, respectively）. The MUC2 mRNA/β-aetin mRNA in rat lung tissues and the mucin MUC2 expression levels（value A） in airway epithelial cells were both positively correlated with the IL-13 level in BALF（ r =0. 648, P 〈0.05; r =0. 676, P 〈0.05） and the change rate of airway resistance （ r =0. 644, P 〈 0.05; r = 0. 584, P 〈0.05）. Conclusions Chronic Aspergillus {umigatus exposure can upregulate the expression of mucin MUC2 in the airways of asthmatic rats, increase the Viscosity and secretion of airway mucus, and promote the airway hypersensitivity.