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.