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目的 观察骨化三醇[1,25(OH)2D3]对博来霉素诱导的小鼠肺纤维化的干预作用,并初步探讨其作用机制.方法 将90只6～8周龄的SPF级雄性C57BL/6小鼠按随机数字表法分为模型组、治疗组和对照组(30只/组),向模型组、治疗组小鼠气管内注入博来霉素复制肺纤维化模型,对照组注人生理盐水.自第2天起治疗组用橄榄油稀释1,25(OH)2D3给予0.5 μg· kg-1·d-1灌胃,其余2组给予等量的橄榄油.每组分别于手术后第14、21、28天各处死1/3,取肺组织行HE、Masson染色观察肺泡炎和肺纤维化改变,酸水解法测羟脯氨酸含量,实时RT-PCR法检测肺组织中Ⅰ型胶原、α-平滑肌肌动蛋白(α-SMA)、Wnt3a、Wnt4、Wnt7a mRNA的表达量,免疫组织化学检测α-SMA蛋白和β-链蛋白(β-catenin)表达量.结果 治疗组肺泡炎在第14、21天以及肺纤维化在3个时间段均较模型组轻(均P＜0.05).治疗组的羟脯氨酸含量、Ⅰ型胶原、α-SMA、Wnt3a、Wnt4 mRNA 以及α-SMA、β-链蛋白表达量在3个时间段均低于模型组(均P＜0.05).第28天治疗组的羟脯氨酸含量、Ⅰ型胶原、α-SMA、Wnt3a、Wnt4、Wnt7a mRNA表达水平分别为0.67±0.14、1.66±0.34、1.37±0.41、1.43±0.27、1.29±0.19和1.18±0.20,明显低于模型组(1.10±0.16、3.50 ±0.74、2.68±0.61、2.60±0.58、2.23±0.45、1.93±0.36)；α-SMA、β-链蛋白表达量分别为0.44±0.13、0.25±0.05,明显低于模型组(0.98±0.20、0.58±0.06).结论 1,25(OH)2D3能明显减轻博来霉素诱导的小鼠肺纤维化,其作用机制可能与抑制Wnt信号通路有关.“,”Objective To observe the effects of 1,25 (OH)2D3 on bleomycin-induced pulmonary fibrosis in mice and to explore its mechanisms.Methods Ninety male C57BL/6 mice,6 to 8 weeks old,were randomly divided into 3 groups according to the table of random numbers:a control group,a model group and a treatment group (n =30 each).Bleomycin was injected to the mice in the latter 2 groups by single intratracheal injection to duplicate the pulmonary fibrosis model,while the control group was injected with saline.From the next day,the mice in the treatment group received 1,25(OH)2D3 (0.5 μg · kg-1 ·d-1) diluted in olive oil by gavage daily,while the other groups were treated with equivalent olive oil.Ten mice in each group were killed randomly on day 14,21 and 28 after surgery respectively.Pulmonary alveolitis and fibrosis were evaluated by using hematoxylin-eosin and Masson stain method.The content of hydroxyproline was measured by acid hydrolysis method.The mRNA levels of collagen1α1,α-SMA,Wnt3a,Wnt4,and Wnt7a in the lung tissues were measured by real-time RT-PCR,while the protein expression of α-SMA and β-catenin were assessed by immunohistochemistry.Results Pulmonary alveolitis at day 14,21 and fibrosis at day14,21,28 in the treatment group were remarkably reduced compared to the model group (all P ＜ 0.05).Compared with the model group,the treatment group showed decreased content of hydroxyproline,decreased mRNA levels of collagen1α1,α-SMA,Wnt3a,Wnt4 and decreased protein expression of α-SMA and β-catenin at the 3 time points (all P ＜0.05).The content of hydroxyproline and the mRNA levels of collagen1 α1,o-SMA,Wnt3a,Wnt4,Wnt7a in the treatment group at 28 d were 0.67 ±0.14,1.66 ±0.34,1.37 ±0.41,1.43 ±0.27,1.29 ±0.19,1.18 ±0.20,respectively,all of which were significantly lower than those in the model group (1.10 ±0.16,3.50 ±0.74,2.68 ±0.61,2.60 ±0.58,2.23 ± 0.45,1.93 ± 0.36,respectively).Protein expression of α-SMA and β-catenin in the treatment group were 0.44 ± 0.13 and 0.25 ± 0.05,respectively,which were also significantly lower than those of the model group(0.98 ±0.20,0.58 ±0.06,respectively).Conclusion 1,25 (OH)2D3 was shown to reduce pulmonary fibrosis induced by bleomycin in mice,and its mechanisms might be associated with Wnt signaling suppression.