槲皮素对重症急性胰腺炎肺损伤大鼠肺泡中性粒细胞凋亡的影响

Effects of quercetin on apoptosis of alveolar polymorphonuclear neutrophils in severe acute pancreatitis rats with lung injury

目的:探讨槲皮素对重症急性胰腺炎(SAP)大鼠肺泡中性粒细胞(polymorphonuclear neutrophil,PMN)凋亡的影响及机制。方法:48只成年SD大鼠随机分为4组,每组12只,即假手术(sham组)、SAP组、槲皮素低剂量(50 mg/kg)组及槲皮素高剂量(100 mg/kg)组。逆行性胆胰管注射5%牛磺胆酸钠建立SAP大鼠模型。槲皮素组在胰腺炎模型基础上予槲皮素干预,sham组和SAP组给予等量生理盐水。经支气管肺泡灌洗分离收集PMN。荧光显微镜观察细胞形态学变化;流式细胞术检测PMN凋亡指数;Western blotting检测Bax和Bcl-2蛋白表达;荧光分光光度计法检测caspase-3活性。结果:荧光显微镜下观察发现SAP组PMN固缩,核染色质凝聚;与sham组比较,SAP组PMN凋亡指数降低,Bax蛋白表达减弱,Bcl-2蛋白表达增强,caspase-3活性减弱(P<0.01);而槲皮素处理后PMN凋亡指数升高,Bax蛋白表达增强,Bcl-2蛋白表达减弱,caspase-3活性增强(P<0.05),呈现浓度依赖性,而且,槲皮素能减轻SAP引起的肺损伤。结论:SAP时存在肺泡PMN凋亡延迟,槲皮素通过上调PMN Bax蛋白表达和抑制Bcl-2蛋白表达,诱导PMN凋亡。槲皮素减轻SAP引起的肺损伤可能与其诱导PMN凋亡有关。

AIM： To explore the effects of quercetin （Que） on the apoptosis of alveolar polymorphonuclear neutrophils （PMN） isolated from severe acute pancreatitis （SAP） rats with lung injury. METHODS： Forty-eight SD rats were randomly divided into 4 groups： sham group, SAP group, low-dose （50 mg/kg） Que group and high-dose （100 mg/ kg） Que group. SAP was induced by retrograde administration of 5% sodium taurocholate into the biliary pancreatic duct. The SAP rats in Que groups were given quercetin, while the rats in sham group and SAP group received an infusion of phys- iological saline. Alveolar PMN were harvested by the collection of bronchoalveolar lavage fluid. The cell morphological changes were observed under fluorescent microscope. The cell apoptotic index was analyzed by flow cytometry. The protein levels of Bax and Bcl-2 were examined by Western blotting. Caspase-3 activity was measured by fluorescence spectropho- tometry. RESULTS： Cell shrinkage and condensation of chromosomes were observed in alveolar PMN from SAP rats. Compared with sham group, the apoptotic index of alveolar PMN reduced in SAP group. The protein expression of Bax was significantly reduced, that of Bcl-2 was significantly enhanced, and caspase-3 actxwty was attenuated. After Que pretreat- ment, the apoptotie index of alveolar PMN increased, the protein expression of Bax was significantly enhanced, that of Bcl- 2 was significantly reduced, and caspase-3 activity increased~ The effects of Que presented a concentration-dependent man- ner, indicating that Que alleviated SAP-induced lung injury. CONCLUSION： The apoptosis of alveoar PMN is delayed in SAP rats. Quercetin induces apoptosis of alveolar PMN by up-regulating the expression of Bax and down-regulating the ex- pression of Bcl-2.