弥猴肠缺血再灌注后生长抑素含量与中性粒细胞寿命的相关性探讨

Somatostatin levels and polymorphonuclear neutrophil life in intestinal ischemia reperfusion of macaque

目的探讨多器官功能障碍综合征时中性粒细胞凋亡延迟的潜在原因,以增加对全身炎症反应内源性保护机制的认识。方法对照组、实验组各5只弥猴用放射免疫分析法测定其外周血、肠黏膜生长抑素浓度;生长抑素与猕猴外周血中性粒细胞共同孵育后,观察猕猴外周血中性粒细胞的形态变化,流式细胞仪测定细胞凋亡率,电泳分析中性粒细胞DNA断裂片段,生物分子相互作用系统检测中性粒细胞上生长抑素受体(SSTR-1、SSTR-2)。结果猕猴肠缺血再灌注后,猕猴外周血及小肠黏膜中生长抑素含量均明显下降;中性粒细胞凋亡率由阻断前的15.4%±1.4%,显著降低至3.5%±0.5%(P<0.05);腹腔巨噬细胞凋亡率由阻断前的14.1%±1.7%增加至20.2%±1.8%(P<0.05);体外实验表明,生长抑素可使中性粒细胞体积缩小,细胞质密度增加,染色质固缩,细胞核变小;中性粒细胞凋亡率(50.2%±1.8%)明显高于对照组(20.0%±2.2%,P<0.01);中性粒细胞的DNA片段断裂分析电泳可见Ladder带。中性粒细胞上生长抑素受体能与生长抑素受体SSTR-1抗体、SSTR-2抗体发生结合反应,其特异结合量分别为(548±20)RU/m l及(28±21)RU/m l。结论生理状态下,生长抑素通过猕猴外周血中性粒细胞上生长抑素受体介导,诱导其凋亡;肠缺血再灌注后猕猴外周血及小肠黏膜中生长抑素含量明显下降,这使中性粒细胞凋亡延迟,从而推动了全身炎症反应综合征和多器官功能障碍综合征的发生。

Objective To investigate the association of somatostatin （SST）levels in plasma or jejunum tissue and polymorphonuclear neutrophil （PMN） life in intestinal ischemia reperfusion of macaque. Methods MODS model in macaque was established by clamping superior mesenteric artery, The levels of SST in plasma and jejunum tissue were measured by radioimmunoassay. After incubated with SST, the apoptotic PMN were determined by the morphological studies, flow cytometer and DNA agarose electrophoresis. The expression of SSTR on PMN was detected by biosensor, Results SST levels in macaque plasma or jejunum tissue were significantly decreased after intestinal ischemia reperfusion （IR） injury, The apoptotic rate of PMN was obviously reduced （ 15.4% ± 1,4% to 3, 5% ± 0. 5% ,P 〈 0. 05 ）. However, the number of apoptotic macrophage from abdominal cavity was clearly increased. The apoptotic rate of PMN was significantly increased （ 20. 0% ± 2. 2% to 50. 2% ± 1.8%, P 〈 0. 01 ） after incubated with SST in vitro. Specific DNA ladder bands from PMN were visualized with agarose electrophoresis. Specific bindings between PMN and the antibodies for SSTR1 （548 RU/ml ±20RU/ml） or SSTR2 （28 RU/ ml ± 21RU/ml） were detected. Conclusion The physiological apoptosis of PMN in macaque could be induced by SST through SSTRs on PMN. The decreased SST levels in macaque plasma or jejunum tissue in the state of intestinal ischemia reperfusion might extend PMN life and promote the occurrence of MODS.