| BackgroundPulmonary fibrosis is a chronic interstitial lung disease with complex etiology,with a poor prognosis and an unclear pathogenesis.Lysine-specific demethylase 2A（Lysine-specific demethylase 2A,KDM2A）plays an important role in maintaining chromatin state and gene activation,and its abnormal expression level is associated with many diseases.Recent studies have found that knocking down the KDM2 A gene in cells can down-regulate the signal expression of transforming growth factor-β1（TGF-β1）,and TGF-β1 is the main mediator in the development of pulmonary fibrosis,suggesting that KDM2 A may Involved in regulating the formation of pulmonary fibrosis.However,the current research on KDM2 A mainly focuses on the tumor field,and the research on pulmonary fibrosis is relatively rare.The purpose of this experiment was to construct a mouse model of pulmonary fibrosis and to explore the expression changes of KDM2 A in the progression of pulmonary fibrosis.ObjectiveTo explore the expression changes of KDM2 A in the progression of pulmonary fibrosis,in order to provide a potential new direction for seeking the pathogenesis of pulmonary fibrosis.Methods1.C57BL/6J male mice aged 8 to 10 weeks were randomly assigned to 3 groups after adaptive feeding for 1 week,namely control group（n = 11）,14 d model group（n =11）and 21 d model group（n = 11）.After the mice in the model group were anesthetized,bleomycin（BLM）working solution（dose 2 mg/kg）was drawn with a lacrimal duct irrigation needle,and the liquid was slowly injected into the trachea of the mice to establish a pulmonary fibrosis model.On the 14 th day and the 21 st day after modeling,the lung tissues of mice in the 14 day model group and the 21 day model group were collected,and finally the lung tissues of the control group mice were collected.2.The pathological changes of lung tissue in each group were observed by HE staining and Masson staining,and the scores of alveolitis and fibrosis were performed according to the Szapiel method.3.Immunohistochemical analysis of α-smooth muscle actin（α-SMA）,fibronectin（FN）,transforming growth factor-β1（TGF-β1）and KDM2 A protein expression and scored by immunohistochemistry.4.Western blot was used to detect the expression of α-SMA,FN,TGF-β1 and KDM2 A protein in lung tissue of each group.Results1.HE,Masson staining（1）In the control group,the lung structure was normal,there was no inflammatory cell infiltration in the alveoli,and there was no fibrotic change in the lung interstitium;（2）In the 14 day model group,the lung structure was damaged to varying degrees,the alveolar septum was generally thickened,a large number of inflammatory cells were infiltrated in the alveoli,and the blue collagen fiber deposition could be clearly observed in the bronchi and pulmonary interstitium at all levels;（3）In the 21 day model group,the damage to the lung structure was obvious,the alveolar septa were significantly widened,and some alveoli collapsed and merged,and even formed fibrous plates.Large areas of blue collagen fiber deposition were observed.2.Scoring of alveolitis and fibrosis（1）Compared with the control group,the alveolitis score of the 14 day model group was significantly increased（P < 0.001）;compared with the 14 day model group,the alveolitis score of the 21 day model group was slightly increased,but the difference was not statistically significant（P > 0.05）.（2）Compared with the control group,the fibrosis score of the 14 d model group was significantly increased（P < 0.001）;the 21 d model group had a significantly higher fibrosis score than the 14 d model group（P < 0.001）.3.Immunohistochemical StainingCompared with the control group,the protein immunohistochemical scores ofα-SMA（P < 0.001）,FN（P < 0.001）,TGF-β1（P < 0.001）,and KDM2A（P < 0.001）in the model group were significantly increased on the 14 th day;Compared with the 14 day model group,the protein immunohistochemical scores of α-SMA（P<0.001）,FN（P <0.05）,TGF-β1（P < 0.001）and KDM2A（P < 0.01）in the model group were also increased.4.Western blotCompared with the control group,the protein expressions of α-SMA（P < 0.001）,FN（P < 0.001）,TGF-β1（P < 0.001）and KDM2A（P < 0.001）in the 14 day model group were significantly increased;Compared with the 14 d model group,the expressions ofα-SMA（P < 0.001）,FN（P < 0.01）,TGF-β1（P < 0.001）and KDM2A（P < 0.001）were increased.5.Correlation analysisThe protein expressions of TGF-β1 and KDM2 A in mouse lung tissue increased to varying degrees with the increase of fibrosis.The correlation analysis of the two protein expression results showed that TGF-β1 and KDM2 A protein expression were positively correlated sex,correlation coefficient r = 0.9161,P < 0.0001.ConclusionsThe expression of KDM2 A gradually increased in the progression of pulmonary fibrosis,and was positively correlated with the expression of TGF-β1.It may participate in the formation of pulmonary fibrosis by regulating the expression of TGF-β1. |
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