JNK在缺血后处理减轻再灌注损伤肺细胞凋亡中的作用

目的: 探讨C-Jun氨基末端激酶(JNK)在缺血后处理(IPO)减轻缺血/再灌注损伤大鼠肺细胞凋亡中的作用。方法: 雄性SD大鼠随机分成5组(n＝8),即对照组(C组)、肺缺血/再灌注组(I/R组)、肺缺血/再灌注+缺血后处理组(IPO组)、缺血后处理+溶剂对照组(PPCES溶液)(P组)、缺血后处理+SP600125组(SP组)。分别于再灌注 2 h 颈动脉取血、留取左肺组织,检测血清超氧化物歧化酶(SOD)、丙二醛(MDA)、髓过氧化物酶(MPO),检测肺组织湿/干重比(W/D)和总肺含水量(TLW);光电镜观察肺组织形态学结构改变,并进行肺组织损伤定量评估(IQA);原位末端标记法(TUNEL)检测肺细胞凋亡情况并计算凋亡指数(AI)。结果: 与C组相比,I/R组血清SOD活性显著降低,MDA含量、MPO活力显著升高(P均<0.01),肺组织W/D、TLW、IQA和AI均显著升高(P<0.05 或P<0.01),光镜电镜下肺组织结构发生明显损伤;IPO组、P组、SP组与I/R组相比,MDA含量、MPO活力显著降低,SOD活性升高(P<0.05 或P<0.01),肺组织W/D、TLW、IQA和AI均显著降低(P<0.05 或P<0.01),光镜电镜下肺组织结构损伤情况有所改善;P组与IPO组比较各项指标均无明显差异(P均>0.05);SP组与IPO组相比,MDA含量、MPO活力显著降低,SOD活性升高(P<0.05 或P<0.01),肺组织W/D、TLW、IQA和AI均显著降低(P<0.05或P<0.01),光镜电镜下肺组织结构未见明显损伤。结论: I/R导致大鼠肺组织过度氧化应激,激活JNK,肺内中性粒细胞聚集,导致肺组织结构严重破坏,细胞大量凋亡;IPO可以减轻氧化应激,抑制JNK通路的激活,从而改善其结构破坏和细胞凋亡。

Effects of JNK on ischemic postconditioning attenuating pneumocyte apoptosis after lung ischemia/reperfusion injury

AIM: To investigate the effects of C-Jun N-terminal Kinase (JNK) on ischemic postconditioning (IPO) attenuating pneumocyte apoptosis after lung ischemia/reperfusion injury in rats.METHODS: Adult male Sprague-Dawley rats were randomly divided into 5 groups based upon the intervention (n=8): control group (C), LIR group (I/R), LIR+IPO group(IPO), IPO+solution countrol group (P), IPO+SP600125 group(SP). At the end of the experiment, blood specimens drawn from the arteria carotis were tested for the content of Malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and myeloperoxidase (MPO); left lung tissue was isolated, the ratio of wet lung weight to dry lung wet (W/D),and total lung water content (TLW) were measured. The histological structure of the left lung were observed under light and electron transmission microscopes, and scored by alveolar damage index of quantitative assessment (IQA). the pneumocyte apoptosis index (AI) was achieved by terminal deoxynucleotidyl transferase mediated dUTP nick end abeling (TUNEL).RESULTS: Compared with C group, W/D, TLW, IQA, AI and MDA level, MPO activity of IPO were significantly increased, only SOD activity was reduced(P<0.05 or P<0.01), and was obviously morphological abnormality in lung tissue. Compared with I/R group, W/D, TLW, IQA, AI and MDA level, MPO activity of IPO were significantly decreased, only SOD activity was improved(P<0.05 or P<0.01), and morphological abnormality in lung tissue was obviously reduced. All the indexes between P and IPO were little or no significant(P＞0.05). All the indexes of SP group except for the expression of SOD activity were obviously reduced, SOD activity were increased(P<0.05 or P<0.01), and the abnormal changes of the structure in I/R was also reversed markedly.CONCLUSION: IPO may attenuate pneumocyte apoptosis in LIRI by reducing oxidant generation, then inhibiting activation of JNK, decreasing neutrophils filtration.