目的 观察雷公藤红素对肺纤维化大鼠肺组织酪氨酸激酶2(Janus kinase 2，JAK2)/信号转导与转录激活因子3(signal transducer and activator of transcription 3，STAT3)信号通路的影响。方法 体外实验中用MTT方法评估雷公藤红素对A549细胞增殖的影响，确定雷公藤红素的最佳给药浓度，并观察A549细胞中BCL-2、BAX蛋白表达。动物实验采用第1、14天予以气管滴注博来霉素(4 mg·kg-1);复制36只肺纤维化大鼠模型，随机平均分为模型对照组、雷公藤红素组及阳性药物对照组，另设12只大鼠作为空白对照组。造模完成后，给予各组大鼠相应药物干预，连续给药21d，末次给药后取材。苏木素-伊红染色观察肺组织病理变化，Masson染色光镜观察肺组织支气管周围蓝色胶原纤维沉积。透射电镜观察肺组织超微结构。蛋白免疫印迹法检测肺组织STAT3、p-STAT3、JAK2、p-JAK2、caspase3蛋白含量。结果 雷公藤红素对A549细胞具有抑制作用，不同组别雷公藤红素分别作用36h、48h，其IC50值均接近2。2μmol/L。雷公藤红素抑制活化的A549细胞中BCL-2蛋白表达，促进BAX蛋白表达。经雷公藤红素作用之后，肺纤维化大鼠气道上皮下胶原纤维沉积显著降低，肺组织STAT3、p-STAT3、JAK2、p-JAK2、Caspase-3蛋白表达降低。结论 雷公藤红素通过改变Bax/Bcl-2比值从而对A549细胞产生诱导凋亡的作用，且随着时间的延长而增加。雷公藤红素能减轻肺纤维化大鼠胶原沉积来阻止肺纤维化程度，其机制可能与抑制JAK2/STAT3信号通路相关。
Experimental study of celastrol on the improvement of pulmonary fibrosis by inhibiting JAK2/STAT3 pathway
Objective To observe the effects of celastrol on the signaling pathway of Janus kinase 2(JAK2)/signal transducer and activator of transcription 3(STAT3)in the lung tissues of lung fibrosis rats.Methods MTT method was used to evaluate the effect of celastrol on the proliferation of A549 cells and to determine the optimal concentration of celastrol.Then observe the ex-pressions of BCL-2 and BAX protein in A549 cells.Using tracheal drip of bleomycin on day 1、day 14 with the dose of 4 mg·kg-1.36 SD rats in the stable phase model of lung fibrosis were replicated and randomly divided into the model control group,the celastrol group,and the positive drug control group averagely,with another 12 SD rats were treated as the blank control group.After the completion of modeling,the rats in each group were given the corresponding drugs,and the drugs were administered continu-ously for 21 days.After the last administration,the materials were taken.Hematoxylin-Eosin staining was used to observe the pathological changes in the lung tissues,and Masson staining was used to observe the deposition of blue collagen fibers in lung tis-sues around bronchi.Masson staining to observe the blue collagen fiber deposition around the bronchioles of lung tissues.The ul-trastructure of lung tissue was observed by transmission electron microscopy.The protein levels of STAT3,p-STAT3,JAK2,p-JAK2 and caspase3 in lung tissue were detected by Western blot.Results Celastrol had inhibitory effect on A549 cells.The IC50 values of celastrol in different groups were both close to 2.2umol/L for 36h and 48h.Celastrol can inhibite the expression of BCL-2 protein and promote the expression of BAX protein in activated A549 cells.After treatment with celastrol,the collagen fiber deposition in airway subepitheliumlung with fibrosis rats decreased significantly.The expression of STAT3,p-STAT3,JAK2,p-JAK2 and caspase3 proteins in lung tissue decreased.Conclusion Celastrol can induce apoptosis of A549 cells by changing the Bax/Bcl-2 ratio,and the effect increased with the extension of time.Celastrol can alleviate the collagen fiber deposition around the bronchioles of lung tissues in lung fibrosis rats.The mechanism may be related to the inhibition of JAK2/STAT3 signaling pathway.
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