Objective To investigate the expression and significance of Krüppel-like factor 4 ( KLF4) in the lung tissues of mice with bleomycin-induced pulmonary fibrosis.Methods C57BL/6 mice were randomly divided into a control group and a BLM group. The mice in the BLM group were given a single intratracheal injection of bleomycin ( 2.5 mg/kg) , while those in the control group were injected with isodose physiological saline. The mice were sacrificed at the 12h and on the day 1, 2, 3, 7, 14 and 28, then HE stain and Masson’s trichrome stain were used to detect the architecture of alveolar and the deposition of cellularity and collagen. Real time-polymerase chain reaction ( RT-PCR ) and immunohistochemical technology were performed to investigate the expression of KLF4. Results In the bleomycin-induced pulmonary fibrosis, acute inflammation was observed on the day 1, 2 and 3, the inflammation was exacerbated and the collagen deposition began to be observed on the day 7, the architecture of alveolar was destroyed and the collagen deposition was more obvious on the day 14, while the alveolar structure was nearly recovered to normal, and the inflammation and collagen deposition were attenuated on the day 28. The expression of KLF4 mRNA increased from the day 1, then decreased, arrived at the minimumon the day 3, and then gradually increased until the day 28. The trend of KLF4 protein expression showed roughly the same as the KLF4 mRNA level, which started to increase on the day 1, then decreased, arrived at the minimum on the day 3,then gradually increased until the day 14 and then decreased again. Conclusion The expressions of KLF4 mRNA and protein are dynamically changed in the process of experimental pulmonary fibrosis, suggesting KLF4 may contribute to the pathogenesis of pulmonary fibrosis.
ObjectiveTo investigate the effects and mechanism of atorvastatin in the experimental pulmonary fibrosis. MethodsFifty-four C57BL/6 mice were randomly divided into a control group,a bleomycin group and an atorvastatin group. The mice in the bleomycin group and the atorvastatin group received a single dose intratracheal injection of bleomycin (2.5 mg/kg),while the mice in the control group were injected with isodose physiological saline. The mice in the atorvastatin group were treated with atorvastatin 10 mg·kg-1·d-1 by intragastric administration the day after bleomycin instillation. All groups were sacrificed on the day 3,14 and 28,respectively. HE staining and Masson staining were used to detect the architecture of alveolar and the deposition of cellularity and collagen. RT-PCR and immunohistochemical technology were performed to detect the expression of Krüppel like factor 4 (KLF4). Zymography was used to investigate the activation of matrix metalloproteinase-2(MMP-2). ResultsAfter the treatment of bleomycin,the lung tissues showed acute inflammation on the day 3,the collagen deposition was more obvious and the architecture of alveolar was destroyed on the day 14. The alveolar structure,the inflammation and collagen deposition were attenuated on the day 28 compared with the day 14. Compared with the bleomycin group,the inflammation and the collagen deposition were significantly reduced in the atorvastatin group (P<0.05). Compared with bleomycin group,the expression of KLF4 significantly decreased in the atorvastatin group,although the expression of KLF4 mRNA increased on the day 3 compared with the bleomycin group (0.502±0.261 vs. 0.326±0.164,P<0.05). The expression of KLF4 protein on the day 3 was significantly decreased compared with the bleomycin group (0.048±0.015 vs. 0.130±0.017,P<0.05). After the intervention of bleomycin,the activation of MMP-2 on the day 3 and 14 significantly increased compared with the control group (3.136±1.321 and 3.449±0.356 vs. 0.983±0.147,P<0.05),and significantly decreased after the treatment of atorvastatin (2.191±0.800 and 2.506±0.761). ConclusionAtorvastatin may have anti-inflammation and anti-fibrosis activities in experimental pulmonary fibrosis through KLF4 pathway.