Expression of Bid/Bcl-xl and apoptosis in epithelial cells of pulmonary fibrosis rats and intervention study of cucumin

Objective To investigate the expression of Bcl-2 family protein and apoptosis in epithelial cells of pulmonary fibrosis rats induced by bleomycin on different times,and observe the curcumin intervention in the formation stage of pulmonary fibrosis and explore its possible mechanism.Methods Seventy-two Sprague Dawley rats were randomly divided into four groups:control group,model group,cucumin group,and prednisone group.Model group,cucumin group,and prednisone group were induced to produce pulmonary fibrosis with bleomycin endotracheally while control group was given with normal saline instead in the same condition.From the second day after bleomycin administration,the curcumin group was given with curcumin (300 mg/kg) while prednisone group with prednisone (5 mg/kg) per day by intragastric administration,respectively.The control group and model group were given with 1％ sodium carboxymethyl cellulose (10 ml/kg).Six rats of each group were randomly sacrificed on 7th,14th,and 28th day after bleomycin administration,respectively.The histological changes of the lung were evaluated by HE and Masson staining.The level of hydroxyproline in lung tissue was assessed by digestion method.The immunohistochemical method was used to investigate the changes of Bid and Bcl-xl protein.TUNEL was used to detect the change of cell apoptosis.Results The cell apoptosis index,hydroxyproline and histological changes of the lung in cucumin group were lower than those in model group (P ＜0.01).There was no significant difference in the expression of Bid protein between model group and cucumin group.The expression of Bcl-xl protein in model group was lower than that in cucumin group (P ＜0.01).Conclusions Cucumin can reduce the expression of pulmonary fibrosis through inhibition of apoptosis of epithelial cells.It may up-regulate the expression of Bcl-xl in alveolar epithelial cells and bronchial cells of pulmonary fibrosis rats but not down-regulate the expression of Bid. Key words: Pulmonary fibrosis;  Apoptosis ;  Bid ;  Bcl-xl;  Cucumin