The Expression Of Cathepsin B In The Lung On Idiopathic Pulmonary Fibrosis Of The Rat And Intervention Study Of Astragaloside

Objective To examine the change of Cathepsin B in lung from rats with pulmonary fibrosis on different times after bleomycin-treated and to compare with the saline control group,to investigate the role of CB protein in the pathogenesis of experimental pulmonary fibrosis;To examine cell apoptosis and the change of CB expression in the lung of rats with experimental pulmonary fibrosis,to investigate the changes and significance of apoptosis and CB protein in experimental pulmonary fibrosis ; To examine the change of CB in lung from astragaloside-treated rats with bleomycin-induced pulmonary fibrosis and to compare with the bleomycin-treated group,in order to explore the effect of astragalaside on Cathepsin B expression in the lung of rats with experimental pulmonary fibrosis.Method Forty-eight Sprague Dawley ( SD )were randomly divided into three groups: rats were randomly divided into three groups:normal control group(C group),model group(B group) and treatment group(T group). Six rats in model group were sacrificed on 7,14,28 and 35days respectively after intratracheal instillation. The model group and the treatment group were induced to produce pulmonary fibrosis with bleomycin endotracheally,while the control group was given with normal saline instead in the same condition.From the second day the rats in the treatment group were treated with 0.1g/L astragaloside 2 ml ig ,while the other rats with CMC 2ml intragastric injection instead.On the 7th,14th,and 28th day the Lungs were isolated. Pathological changes in the lungs were evaluated by HE stain and Masson's trichrome stain. The hydroxyprolline of pulmonary homogenate were measured for evaluation of the degree of pulmonary fibrosis. The mRNA expression of CB was evaluated by RT-PCR quantitative analysis,and the immunohistochemical method was used to investigate the change of CB protein. TUNEL was used to detect the change of cell apoptosis.Results1,HE/Masson Staining on the lung tissueThe lung of normal control group rat had no change lesion in every point,but that of Model group showed acute inflammation:there were a great deal of poly-cyte and monocyte infiltration in alveolar space and interstitia,company edema and slight hemorrhage.Alveoli normal structure was destructed by granulation in severe areas. Alveolitis relieved on the 14d, but hemorrhage and edema were still existing, with fibroblast increasing,interval widening obviously, collagen deposited and patches of fibrosis.In 28d-group, alveolitis did not decreased obviously. Alveola structure was destructed, with mass collagen deposited around neonate blood capillary. Alveolar interval and part of alveolar spacearea occupied by collagen and fibrin.Inflammatory cell in interstitia was mainly lymphocyte infiltration. Alveolitis of treatment and model group in every phase was markedly severe compared with normal control group.While PF was significantly different from normal control group just on 14 and 28d.Treatment group has the same tendency as model group;but the degree of alveolitis and pulmonary fibrosis decreased.These results suggested astragaloside may relieve alveolitis and PF induced by bleomycin in rats.2,HYP concentrationHYP concentrations of model group was higher than normal control and treatment group (P<0.01).But that of model group increased gradually ;That of treatment group took on low level,but increased too,HYP was higher than that of control group and lower than model group(P<0.01 or P<0.05).3,The change of cell apoptisis index in lung tissueThe apoptosis index of lung cells on 28d in the model group was higher than that of control group and treatment group.There was significant difference between the three groups(F=79.90,P<0.01).4,CB and CB mRNA in lung tissueThe result of immunohistochemistry and RT-PCR suggested that the expression of CB protein and mRNA in the lung also increased after 7 d by treated with bleomycin, increased on the 14th day and further increased on the 28th day. But decreased on the 35th day.The expression of CB protein and mRNA in fibrosis group was higher than that in the control group (P<0.05 or P<0.01);That of treatment group took on low level,but increased too, the expression of CB protein and mRNA were higher than that of control group and lower than model group(P<0.01 or P<0.05).conclusion1,CB protein and CB mRNA are dynamically changed in the lung with experimental pulmonary fibrosis, which may contribute to the pathogenesis of pulmonary fibrosis.2,The apoptosis index of lung cells,CB gene and protein was up-regulated in lung tissue of pulmonary fibrosis,which may play an important role in the development of disease. 3,Astragaloside might play pivotal role in curing the experimental pulmonary fibrosis in Spague-Dawley rats by suppressing excessive expressing of lung CB.