过氧化物酶体增殖物激活受体-γ及其配体在大鼠气道黏液高分泌中的作用

Effect of peroxisome proliferators activated receptor gamma and its ligand on airway mucus hypersecretion in rats

目的探讨过氧化物酶体增殖物激活受体-γ（PPAR-γ）及其配体对气道黏液高分泌的作用及其机制。方法应用随机数字表法将36只SD大鼠随机分为4组，其中生理盐水对照组（6只）雾化吸入生理盐水；罗格列酮对照组（6只）雾化吸入生理盐水，同时给予罗格列酮8mg／kg灌胃；丙烯醛组（6只）雾化吸入丙烯醛3．0mg／L，6h／d，连续12d；罗格列酮干预组根据不同剂量又分为低、中、高剂量组，每组各6只，在雾化吸入丙烯醛的同时分别给予2、4和8mg／kg罗格列酮灌胃。采用HE染色及阿辛蓝-过碘酸雪夫染色法观察支气管肺组织的病理改变和气道黏液物质改变，应用实时荧光定量逆转录-PCR及免疫组织化学SP法检测黏蛋白5AC和PPAR-γ的表达水平。组间比较采用方差分析，两组比较采用q检验，相关性分析采用Pearson法。结果丙烯醛组、牛理盐水对照组及低、中、高剂量罗格列酮干预组气道黏液物质的相对着色叫积分别为（60．2±9．3）％、（4．9±1．0）％、（53．3±8．5）％、（26．5±7．4）％和（12．54-3．7）％，组间比较差异有统计学意义（F=93．80，P〈0．01）。黏蛋白5AC蛋白在丙烯醛组、生理盐水对照组及低、中、高剂量罗格列酮干预组表达的积分吸光度值分别为4339±453、1636±282、3996±346、3048±331和2376±343，组间比较差异有统计学意义（F=67．74，P〈0．01）；PPAR-γ蛋白表达的积分吸光度值分别为1159±184、838±151、1272±189、1568±282和1872±270，组间比较差异有统计学意义（F=21．53，P〈0．01）。内烯醛组、生理盐水对照组及低、中、高剂量罗格列酮干预组黏蛋白5ACmRNA表达的相对拷贝数分别为35．3±10．0、2．2±0．7、30．5±10．2、18．6±5．3和10．8±2．6，组间比较差异有统计学意义（F=29．67，P〈0．01）；PPAR-γmRNA的相对拷贝数分别为7．8±1．9、2．0±0．6、9．8±2．8、18．6±5．3和31．6±8．9，组间比较差异有统计学意义（F=39．47，P〈0．01）。丙烯醛组PPAR-γ蛋白水平与黏蛋白5ACmRNA表达呈负相关（r=-0．880，P〈0．01）。结论内烯醛致气道黏液高分泌过程与PPAR-γ表达异常有关；PPAR-γ及其配体罗格列酬可以抑制丙烯醉诱导的气道黏液高分泌，其具体机制可能与下调黏蛋白5AC的表达有关。

Objective To explore the effect and the molecular mechanisms of peroxisome proliferators activated receptor gamma （PPAR-γ）and its ligand on airway mucus hypersecretion. Methods Thirty-six Sprague-Dawley rats were randomized into the following groups： （ 1 ） Rats in the saline control group （n = 6） received normal saline inhalation; （2） Rats in the rosiglitazone control group（ n = 6） received inhaled saline and oral rosiglitazone 8 mg/kg simultaneously; （3） Rats in the acrolein group （n = 6 ） received inhaled acroline 3. 0 mg/L, 6 h/day, for 12 days; （4）Rats in the rosiglitazone intervention group （n = 18） received inhaled aerolein and oral roslglitazone 2 mg/kg, 4 mg/kg, 8 mg/kg, respectively, as the low dose, the moderate dose and the high dose intervention groups （n = 6 each）. The lung tissue sections were stained with HE for histopathologlcal examination. The changes of airway mucus were examined with AB-PAS. Expressions of MUCSAC and PPAR-γ protein in the bronchial epithelium were detected by immunohistochemistry. The expression of mRNA was measured with real time RT-PCR. The data were analyzed with SPSS 10. 0 software. Variables were compared with One-Way ANOVA and q test. The correlations between variables were analyzed using Pearson＇ s correlation coefficient. Results The levels of airway mucuswere （60.2±9.3）%, （4.9±1.0）%, （53.3 ±8.5）%, （26.5 ±7.4）%, （12.5 ±3.7 ） % respectively in the acrolein group, the saline control group, the low dose rosiglitazone intervention group, the moderate dose rosiglitazone intervention group, and the high dose rosiglitazonc intervention group, the difference being significant among groups （F = 93.80, P 〈 0. 01 ）. The protein expressions of MUC5AC in the bronchial epithelium examined by immunohistochemistry were 4339 ± 453, 1636 ±282, 3996 ± 346, 3048± 331, 2376± 343 respectively in the aerolein group, the saline control group, the low dose rosiglitazone intervention group, the moderate dose rosiglitazone intervention group, and the high dose rosiglitazone intervention group, the difference being significant among groups （ F = 67. 74, P 〈0. 01 ）. The protein expressions of PPAR-γ were 1159 ± 184, 838 ± 151, 1272 ± 189, 1568 ± 282, 1872 ± 270 respectively in the acrolein group, the saline control group, the low dose rosiglitazone intervention group, the moderate dose rosiglitazone intervention group, and the high dose rosiglitazone intervention group, the difference being significant among groups （ F = 21.53, P 〈 0.01 ）. The mRNA expressions of MUCSAC （ the relative copies） were 35.3± 10. 0, 2. 2± 0.7, 30. 5 ± 10. 2, 18.6 ± 5.3, 10. 8 ± 2. 6 respectively in the acrolein group, the saline control group, the low dose rosiglitazone intervention group, the moderate dose rosiglitazone intervention group, and the high dose rosiglitazone intervention group, the difference being significant among groups （F =29. 67, P 〈0. 01 ）. The mRNA expressions of PPAR-γ （the relative copies） were 7.8 ± 1. 9, 2.0 ±0. 6, 9. 8 ±2. 8, 18. 6 ±5.3, 31.6 ± 8.9 in the acrolein group, the saline control group, the low dose rosiglitazone intervention group, the moderate dose rosiglitazone intervention group, and the high dose rosiglitazone intervention group, the difference being significant among groups （ F = 39. 47, P〈0. 01 ）. The expression of MUC5AC mRNA was negatively correlated with the protein expression of PPAR-γ in the acrolein group （ r = - 0. 880, P 〈 0. 01 ）. Conclusions PPAR-γ was involved in airway mucus hyperseeretion induced by acrolein. PPAR-γ and its ligand rosiglitazone inhibited acrolein-induced airway mucus bypersecretion, possibly through dowuregulation of MUC5AC.