盐皮质激素受体在实验性肺纤维化小鼠中的动态变化及意义

Dynamic changes of the mineralocorticoid receptor in bleomycin induced pulmonary fibrosis

【目的】探讨盐酸平阳霉素诱导的实验性肺纤维化小鼠肺组织中，盐皮质激素受体（mineralocorticoidreceptor，MR）的动态变化及意义。【方法】C57BL／6小鼠随机分为生理盐水组和盐酸平阳霉素组，气管内一次性滴注盐酸平阳霉素溶液（2．5mg／kg）建立小鼠肺纤维化模型，分别于术后12h、1d、2d、3d、7d、14d、28d取材，采用HE染色、Masson染色方法观察肺组织病理学变化及胶原沉积情况，采用Real—timePCR和Westernblotting法分别检测各组肺组织中MRmRNA和蛋白的表达水平。【结果】病理学结果显示，与生理盐水组相比，盐酸平阳霉素组小鼠在1～7d呈现明显的肺泡炎性改变，术后14d开始出现明显的胶原沉积。实时定量PCR结果显示盐酸平阳霉素组小鼠肺组织中MRmRNA表达水平在急性炎症期12h（6．23±0．89）、1d（5．67±0．92）、2d（3．87±0．63）、3d（3．12±0．37）升高，明显高于生理盐水组，差异均有统计学意义（P〈0．05），随后逐渐下降，降至最低，与生理盐水组表达水平接近，而后再次升高，在纤维化晚期（28d）（4．25±0．72）明显高于生理盐水组（P〈0．05）；Westernblotting结果显示，MR蛋白表达水平变化趋势与MRmRNA相一致，术后12h（5．62±1．28）、1d（5．27±0．73）、2d（3．88±0．34）、3d（2．99±0．35）也明显高于生理盐水组，在给予盐酸平阳霉素14d后，表达水平降低并与生理盐水组接近，在术后28d（3．92±0．36）又再次高于生理盐水组，差异均有统计学意义（P〈0．05）。【结论】MR在盐酸平阳霉素诱导肺纤维化过程中呈现明显的动态变化，并可能参与了肺纤维化的发生与进展过程。

[Objective ] To investigate the alterations of MR in the lungs of bleomycin-induced pulmonary fibrosis. [ Methods ] Pulmo- nary fibrosis was induced by single intratracheal instillation of bleomycin （2.5 mg/kg）. For further analysis, mice were sacrificed on 12 hours, day 1, 2, 3, 7, 14 or 28 after bleomycin administration to establish pulmonary fibrosis model. The sections of lungs were stained with H＆E and Masson＇s trichrome for assessment of pathological changes and deposition of collagen of lung tissues. The levels of ex- pressions of MR mRNA and protein were examined by real-time PCR and Western blotting analysis. [ Results ] The results of histology analysis revealed classical pathological stages of bleomycin induced lung fibrosis, including acute inflammation phase （from day 1 to day 7 post bleomycin）, and fibrosis phase （ from day 14 post bleomycin）. Real-time quantitative PCR analysis of lung tissue from a mouse bleomycin-induced pulmonary fibrosis model showed that the levels of MR mRNA were obviously increased on the 12 hour （6.23 ±0.89）, day 1 （5.67 ± 0.92）, day 2 （3.87 ± 0.63）, day 3 （3.12 ± 0.37）, compared with the NS group with statistical significance, then de- creased gradually. On day 14 after bleomycin instillation, the expres- sion levels of MR mRNA showed almost no difference between the groups, and then were increased again in the late phase of fibrosis （28 d） （4.25 ± 0.72, P〈0.05）. Consistent with the MR mRNA, the lev-els of expressions of MR protein were significantly higher than the NS group on the 12 hour （5.62 ± 1.28）, day 1 （5.27 ± 0.73）, day 2 （3.88 ± 0.34）, day 3 （2.99 ± 0.35）, then decreased on day 14 after bleomycin instillation, and finally reached again a comparatively high- er level on day 28 （3.92 ± 0.36, P〈0.05）. [Conclusion] The dynamic changes were significantly shown in the expression of MR in the different phase of bleomycin-induced pulmonary fibrosis, which were presumably involved in the initialization and progression of pul- monary fibrosis.