咪喹莫特对哮喘小鼠TGF-β_1及Smads蛋白的影响

The Effect of Imiquimod Inhalation on TGF-β1,Smads in Mouse Asthma Models with Airway Remodeling

目的观察咪喹莫特对哮喘小鼠肺组织转化生长因子β1(TGF-β1)及其信号转导分子Smads表达的影响。方法40只小鼠按随机数字表法分成4组,每组10只。正常对照组(A组)、哮喘模型组(B组)、布地奈德治疗组(C组)和咪喹莫特治疗组(D组)。小鼠于第0、14天以卵白蛋白(OVA)致敏,第24天开始雾化吸入1%OVA激发并持续28 d,建立哮喘气道重塑模型,C组和D组在吸入OVA前2 h分别雾化吸入布地奈德或咪喹莫特30 min。于最后1次雾化结束后24 h,对肺组织切片行苏木精-伊红(HE)染色观察病理学改变、过碘酸雪夫(AB-PAS)染色定量杯状细胞百分比及黏液分泌、Masson染色测定胶原沉积;用免疫组化方法检测肺组织TGF-β1的蛋白表达水平;用逆转录-聚合酶链反应半定量检测肺组织TGF-β1mRNA以及Smad2、Smad7 mRNA表达水平。结果B组杯状细胞增生明显,伴黏液高分泌,气管壁胶原过度沉积,与A组比较差异有统计学意义(P<0.05);D组杯状细胞轻度增生,黏液分泌减少,气管壁胶原沉积减轻,与B组比较差异有统计学意义(P<0.05);B组TGF-β1蛋白和mRNA、Smad2mRNA的表达较A组增加,差异有统计学意义(P<0.05),C、D组TGF-β1蛋白和mRNA、Smad2mRNA的表达下降,与B组比较差异均有统计学意义(P<0.05),D组可显著上调Smad7mRNA的表达,与B组比较差异有统计学意义(P<0.05)。结论雾化吸入咪喹莫特通过抑制慢性哮喘小鼠肺组织TGF-β1蛋白和mRNA、Smad2mRNA的过度表达,上调Smad7mRNA的表达,从而阻断TGF-β1的胞内信号转导,可在一定程度上减轻哮喘小鼠的气道重塑。

Objective To observe the effects of aerosol Imiquimod on the airway remodeling and the expression of transforming growth factor-β1 （TGF-β1）, Smad2, and Smad7 in mouse asthma models. Methods Forty BALB/c mice were divided into 4 groups, ten in each group. Normal group（A）, model group （B）, Budesonide group （C）, and Imiquimod group （D）. Mice were sensitized on days 0 and 14 by OVA and challenged from days 24 to51 by OVA repeatedly to establish a chronic model of asthma characterized by airway remodeling, group D were interfered with aerosol Imiquimod 30 min before challenge, and group C were interfered with aerosol Budesonide 30 min before challenge. Group A were treated with saline instead of OVA. The outcome measurements included airway inflammatory indices, and the degree of mucus secretion in the lumens, the amount of collagen deposition around the bronchus, and depth of airway smooth muscle （ASM） by HE, PAS and Masson＇s staining. The expressions of TGF-t31, TGF-β1mRNA, Smad2 mRNA, and Smad7 mRNA were detected by immunohistochemistry and RT-PCR. Results ① The airway wall, smooth muscle of group B were thicker than that of group A（P〈0.05）, While these airway structural changes were decreased in group D and group C（P 〈 0.05） ; ② mucus hypersecretion, goblet cell hyperpla-sia, airway smooth muscle hypertrophy, and RBM collagen deposition were obvious in group B （P 〈 0.05）, while significantly decreased in group D and group C（P 〈 0.05） ; ③ the expressions of TGF-β1, TGF-β1 mRNA and Smad2 mRNA in group B were significantly higher than those in group A （ P 〈 0 .05 ） , while decreased in D and group C as compared with group B （ P 〈 0.05） ; ④ the expression of Smad7mRNA in C group was significantly higher than that in group B . Conclusion Imiquimod aerosol inhalation could decrease the expression of TGF - β1 , TGF - β1 mRNA, Smad2 mRNA, increase the expression of Smad7 mRNA in chronic mouse asthma models and inhibit airway remodeling.