合成短肽S247对呼吸机所致肺损伤中肺上皮细胞凋亡的影响

Effect of synthetic polypeptide S247 on the apoptosis of pulmonary epithelial cells in ventilator-induced lung injury

目的研究合成短肽S247对呼吸机相关性肺损伤凋亡的影响,探索其在肺损伤中的防护作用。方法30只清洁级雄性SD大鼠随机分为3组:对照组(C组)、肺损伤组(I组)和S247治疗组(S组),每组10只,大潮气量损伤性通气4 h建立呼吸机相关性肺损伤模型(呼吸参数:Vt=40ml/kg体重,呼吸频率=80次/min,FiO_2=21%),光镜下观察肺病理改变,测定肺湿/干比;收集肺泡灌洗液(BALF),考马思亮兰法测BALF中总蛋白含量,光境下行WBC计数,免疫组织化学检查肺组织Fas、Caspase-3蛋白的表达水平,TUNEL法检测肺组织细胞凋亡情况。结果I组肺病理改变明显,各组肺湿/干比、BALF中总蛋白含量、WBC计数差异都有统计学意义(P<0.05或P<0.01),I组Fas、Caspase-3蛋白的表达水平(0.359±0.055;0.152±0.007)显著增高(P<0.01),凋亡指数(60.000±7.461)明显增加(P<0.01);在用S247后,Fas、Caspase-3蛋白的表达水平(0.240±0.062;0.146±0.004)显著下降(P<0.05),凋亡指数(47.857±3.716)有所减少(P<0.05)。结论S247能通过抑制细胞凋亡,有效降低呼吸机相关性肺损伤的程度。

Objective To study the effect of synthetic polypeptide S247 on the expression of Fas and Caspase-3 protein and cell apoptosis as well as to explore its preventive effect on ventilator-induced lung injury. Methods A total of 30 normal healthy Sprague-Dawley rats weighing between 280 and 320 g were divided into three groups （each having 10 rats） ：Control group （group C） ,lung injury group （group I, hyperventilation group of large tidal volume）, S247 group （group S, blocking agent group）. Each rat received ventilation through tracheotomy tube via mouth. Ventilator-induced lung injury model was established by high volume mechanical ventilation for 4 h in groups I and S with tidal volume （VT） 40 ml/kg, breathing rate （P） = 80/min. After the rats in group S were injected by vena caudalis with synthesized peptide S247 （50 mg/kg） once ,S247 was used by intraperitoneal injection once 3 h for 3 times. The lung pathological changes were examined, lung water was measured, and total protein level and counts of white blood cells （WBC） in bronchoalveolar lavage fluid （BALF） were tested. The expression level of Fas and Caspase-3 protein was also detected by using immunohistochemistry and apoptotic lung cells by TUNEL method. The apoptotic index was calculated. Results There was significant difference in ratio of lung wet/ dry, total protein level and WBC counts in BALF among the three groups （ P 〈 0.05 or P 〈 0.01 ）. The average A values of Fas and Caspase-3 were significantly higher in group I than in group C and group S （ P 〈 0.05）. The apoptotic index in group I was also significantly higher than in group C （ P 〈 0.01 ） and group S （ P 〈 0.05）. Condusion The synthesized peptide S247 can reduce the expression of Fas and Caspase- 3 protein. The synthesized peptide S247 significantly inhibited the apoptosis of pulmonary epithelial cells and relieved the degree of ventilator-induced lung injury.