雷帕霉素对大鼠肺纤维化模型的干预作用及对转化生长因子表达的影响

Rapamycin in rat model of bleomycin-induced pulmonary fibrosis and its impact on expression of transforming growth factorial

目的研究雷帕霉素对大鼠肺纤维化模型的干预作用及可能的机制。方法150只SD大鼠采用随机数字表随机分成3组，每组50只：①雷帕霉素组。经气管内灌注博莱霉素诱导肺纤维化，随后每日用雷帕霉素口服溶液0．5mg／kg灌胃进行干预；②模型组，气管内灌注用博莱霉素，灌胃用生理盐水；③对照组，气管内灌注和灌胃均用生理盐水。各组动物均于气管内灌药后第3、7、14、28、56天分别处死10只。通过HE染色、Masson胶原染色、天狼猩红染色偏光法及测定肺组织羟脯氨酸浓度来观察肺泡炎和肺纤维化的程度。用逆转录-聚合酶链反应检测肺组织转化生长因子β1（TGF-β1）的mRNA表达。用免疫组化法检测大鼠肺组织TGF-β1蛋白的表达。结果模型组的肺组织羟脯氨酸含量和肺泡炎程度在各时间点均高于对照组，模型组的肺纤维化程度在第14、28和56天高于对照组（P〈0．05）；雷帕霉素组肺组织羟脯氨酸含量在第14、28和56天低于模型组，雷帕霉素组在第14和28天肺泡炎的程度低于模型组，雷帕霉素组在第28和56天肺纤维化程度低于模型组（P〈0．05）；模型组TGF-β1的mRNA表达在第3、7、14和28天高于对照组，雷帕霉素组TGF-β1的mRNA表达在第7和14天低于模型组（P〈0．05）。结论雷帕霉素能减轻博莱霉素诱导的大鼠肺纤维化，这种作用有可能部分通过抑制TGF-β1的表达而实现。

Objective To study the effect of rapamycin on bleomycin induced pulmonary fibrosis in rats and its possible mechanism. Methods One bundrad and fifty SD rats were randomly divided into three groups. In the rapamycin group and the model group, pulmonary fibrosis was induced by intratracheal instillation of bleomycin,and then the former group received rapamycin 0.5 mg/kg daily, but the latter group received oral normal saline. In the control group, normal saline was given both intratracheally and orally. Ten rats in each group were sacrificed on the 3rd,7th, 14th,28th,and 56th day after intratracheal instillation. Histological changes of the lungs were evaluated by HE stain, Masson＇s trichrome stain, and sirius red stain. Hydroxyproline content of the lung tissue was assessed by hydroxyproline concentration. The mRNA expression of transforming growth factor β1 （TGF-β1） was detected by reverse transcription-polymerase chain reaction. TGF-β1 protein expression in lung tissue was assessed by immunobistochemistry. Results The lung hydroxyproline content and alveolitis in the model group were higher than those in the control group at each time point,the degree of pulmonary fibrosis in the model group was higher than that in the control group on the 14th,28th and 56th day （ P〈0.05）. The content of hydroxyproline in lung tissue in the rapamycin group was lower than that in the model group on the 14th,28th and 56th day,alveolitis in the rapamycin group was lower than that in the model group on the 14th and 28th day,the degree of pulmonary fibrosis in the rapamycin group was lower than that inthe model group on the 28th and 56th day （ P〈0.05）. The expression of TGF-β1 mRNA in the model group was higher than that in the control group on the 3rd, 7th, 14th and 28th day, the expression of TGF-β1 mRNA in the rapamycin group was lower than that in the model group on the 7th and 14th day （P〈0.05）. Conclusions Rapamycin alleviates bleomycin-induced pulmonary fibrosis in rats. Inhibiting the expressions of TGF-β1 in lung tissues may be one of the mechanisms.