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目的 探索let-7d-3p和miRNA-21-5p在二氧化硅(SiO2)诱导的大鼠纤维化肺组织中的差异表达及其意义.方法 SPF级Wistar雄性大鼠随机分为对照组和模型组,每组30只,采用一次性气管内灌注1 ml SiO2悬浊液建立大鼠矽肺模型,对照组大鼠相同方法灌注1ml灭菌生理盐水.分别于染尘后1、7、14、21、28 d采集各组大鼠肺组织,每组取6只,对3只大鼠肺组织进行病理学观察,另外3只采用miRNA微阵列芯片技术筛选肺组织中差异表达的miRNA,通过miRNA芯片筛选结合反转录定量聚合酶链式反应(RT-qPCR)验证let-7d-3p和miRNA-21-5p在两组间的表达水平,对let-7d-3p和miRNA-21-5p进行靶基因预测并进行GO(gene ontology)富集分析和KEGG(kyoto encyclopedia of genes and genomes)通路分析.结果 对照组大鼠1、7、14和21 d Masson染色均可见正常肺组织,未发现胶原纤维,28 d大鼠肺间质和支气管周围仅有少量纤细的胶原分布;模型组大鼠1 d和7 d未发现胶原纤维,14 d染色可见较多以淋巴细胞为主的炎症细胞浸润,未见明显纤维组织,21 d和28 d模型组大鼠肺间质内可见大片状密集的胶原纤维沉积,在肉芽组织、支气管及血管壁周围胶原蛋白增生明显.模型组中let-7d-3p的表达水平均显著下调,miRNA-21-5p表达水平均显著上调,与对照组相比差异均有统计学意义(P＜0.05).结论 模型组中let-7d-3p和miRNA-21-5p表达变化明显,可能与早期矽肺的发生发展有关.“,”Objective To explore the differential expression and significance of let-7 d-3 p and miRNA-21-5 p in silica (SiO2) -induced rat pulmonary fibrosis tissue.Methods SPF male Wistar rats were randomly divided into control group and model group, 30 rats in each group.The silicosis model rats was established by intratracheal instillation of 1 ml SiO2 suspension, the control rats were only treated with 1 ml sterilize normal saline.The lung tissues of experimental rats were collected at 1, 7, 14, 21 and 28 days, respectively after instillation, 6 rats for each group, three rats were used for pathological observation of lung, and the others were used to screen the differential expression of miRNAs in lung tissue by miRNA microarray technology.miRNA chip screening and RT-qPCR were used to verify the expression levels of let-7 d-3 p and miRNA-21-5 p between two groups, the prediction of target genes, the GO (gene ontology) enrichment analysis and KEGG (kyoto encyclopedia of genes and genomes) pathway analysis.Results The results showed that in control group, at 1 d, 7 d, 14 d and 21 d after experiment, no collagen fibers were found in lung tissues by Masson staining, only a small amount of fine collagen around pulmonary interstitial and bronchi could be seen at 28 d after N.S instillation.There was still no collagen fiber were found in the model group at 1 d and 7 d after silica exposure, at the 14 th day there seemed some lymphocytes-predominant inflammatory cells infiltration, but no obvious fibrous tissue was observed in lung tissues.At 21 d and 28 d after exposure, large patches dense collagen fibers deposits could be seen in pulmonary interstitium, and collagen proliferation was quite evident around granulation tissue, bronchi and vascular wall.Additionally, the expression level of let-7 d-3 p showed significantly down-regulated in lung of model group rats, the expression level of miRNA-21-5 p was significantly up-regulated, and were statistically different from the control group (P＜0.05).Conclusion The results suggested that the expressions of let-7 d-3 p and miRNA-21-5 p in silica exposed rats were significantly changed, which might be related to the early occurrence and development of silicosis.