泛素特异性蛋白酶7在博莱霉素诱导的小鼠炎症及肺纤维化过程中的表达及作用

目的:观察和评价泛素特异性蛋白酶7（USP7）在博莱霉素诱导的小鼠炎症及肺纤维化过程中的作用。方法:正常野生型成年小鼠36只，随机分为空白组及博莱霉素组。博莱霉素组采用博莱霉素气管内滴注复制小鼠肺纤维化模型，空白组用同等方法注入同样体积的0.9%氯化钠注射液制备对照模型。造模后第7、14、21天处死小鼠，取小鼠肺组织进行肺系数测定、羟脯氨酸含量测定、HE染色、Masson染色、免疫组织化学染色，观察博莱霉素诱导的小鼠炎症及肺纤维化过程，肺组织中USP7表达水平的动态变化及其与肺胶原蛋白含量的关系。结果:在各时间点博莱霉素组肺系数显著高于空白组（P<0.01）。博莱霉素组羟脯氨酸含量在各时间点的差异均有统计学意义（P<0.01），在第14天和第21天均显著高于空白组（P<0.01）。肺组织病理切片HE染色、Masson染色结果表明博莱霉素气管内给药能诱导的小鼠炎症及肺纤维化过程。免疫组织化学观察半定量USP7结果显示，USP7弱表达于正常肺组织中。在各时间点，博莱霉素组USP7表达差异均有统计学意义（P<0.01），且均较空白组明显增强（P<0.05~P<0.01），并随着时间的延长，表达逐渐减弱（P<0.01）。结论:USP7在博莱霉素诱导的小鼠炎症及肺纤维化过程中呈现明显的动态变化，可能在肺纤维化的发生、发展各个环节中起着一定作用。

Expression and significance of USP7 in mice with pulmonary inflammation and fibrosis induced by bleomycin

Objective: To investigate the expression and significance of ubiquitin-specific protease 7(USP7) in mice with pulmonary inflammation and fibrosis induced by bleomycin.Methods: Thirty six mice were randomly divided into the blank group and bleomycin group.The mice of bleomycin group were induced by bleomycin injection in trachea to establish the mouse pulmonary fibrosis model,and the blank group were injected with the same volume saline.After 7,14 and 21 days of molding,the mice were sacrificed.The lung coefficient and hydroxyproline contents were measured.The pathological change of lung tissue was observed using the HE staining and Masson's staining.The dynamic change of USP7 level in inflammation and fibrosis pulmonary tissue induced by bleomycin were detected using the immunohistochemical staining,and the correlation of which with lung collagen content was analyzed.Results: The lung coefficient value at each time-point in bleomycin group was significantly higher than that in blank group(P<0.01).The difference of the hydroxyproline content among each time-point in bleomycin group was statistically signficant(P<0.01),and the hydroxyproline content in bleomycin group at day 14 and 21 were significantly higher than that in blank group(P<0.01).The results of HE and staining and Masson showed that the bleomycin injection in trachea could induce the pulmonary inflammation and fibrosis in mice.The immunohistochemical staining showed the expression level of USP7 was low in normal lung tissue.The difference of the expression level of USP7 in bleomycin group among different time-points was statistically significant(P<0.01),which significantly increased compared with the blank group(P<0.05 to P<0.01),and gradually decreased with the time prolonging(P<0.01).Conclusions: The level change of USP7 in mice with pulmonary inflammation and fibrosis induced by bleomycin is dynamical,and which may play certain role in the occurrence and development of pulmonary fibrosis.