Jinzhou Zhang, Tao He, Wensheng Chen, Wen Wang, Jincheng Liu, Qin Cui, Hailong Zhu, Weiyong Liu, Dinghua Yi
Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China.
J Trauma. 2008 Apr;64(4):1055-60. doi: 10.1097/TA.0b013e318047c07c.
Polymorphonuclear neutrophil (PMN) apoptosis is suppressed after acute lung injury (ALI), and strategies aimed at inducing PMN apoptosis are thought to be promising therapies for ALI. However, the mechanisms underlying PMN apoptotic suppression are unknown. Cyclo-oxygenase-2 (COX-2) has been shown to regulate tumor cell apoptosis and is up-regulated by inflammatory mediators in PMN. Therefore, we set out to determine whether up-regulation of COX-2 expression contributes to PMN apoptosis after ALI.
Experimental ALI was established in New Zealand rabbits by blunt chest trauma, and a correlation analysis of COX-2 immunohistochemical staining in lung tissue and PMN apoptosis in bronchoalveolar lavage fluid (BALF) was performed. Apoptosis was measured by flow cytometric analysis of annexin V and propidium iodide dual staining. As an in vitro correlate, normal PMNs were treated with BALF from injured lung (BALFALI) in the presence or absence of the COX-2 inhibitor, NS398. COX-2 mRNA levels and PMN apoptosis were then measured.
PMN apoptosis was significantly decreased in BALF after injury. In contrast, COX-2 expression was significantly increased after injury. COX-2 protein expression and PMN apoptosis exhibited a strong inverse correlation (gamma = -0.75, p < 0.01). In vitro experiments revealed apoptosis of normal PMNs was significantly decreased by the addition of BALFALI. The addition of BALFALI was also associated with increased COX-2 mRNA levels. Treatment of cultures with NS398, 10 minutes before BALFALI addition, partially reversed all of these effects.
Up-regulation of intrapulmonary COX-2 expression contributes to the suppression of PMN apoptosis after ALI.
急性肺损伤（ALI）后多形核中性粒细胞（PMN）凋亡受到抑制，旨在诱导PMN凋亡的策略被认为是治疗ALI的有前景的疗法。然而，PMN凋亡抑制的潜在机制尚不清楚。环氧合酶-2（COX-2）已被证明可调节肿瘤细胞凋亡，并在PMN中被炎症介质上调。因此，我们着手确定COX-2表达上调是否有助于ALI后PMN的凋亡。
通过钝性胸部创伤在新西兰兔中建立实验性ALI，并对肺组织中COX-2免疫组化染色与支气管肺泡灌洗液（BALF）中PMN凋亡进行相关性分析。通过膜联蛋白V和碘化丙啶双重染色的流式细胞术分析来测量凋亡。作为体外对照，在存在或不存在COX-2抑制剂NS398的情况下，用损伤肺的BALF（BALFALI）处理正常PMN。然后测量COX-2 mRNA水平和PMN凋亡。
损伤后BALF中PMN凋亡显著降低。相反，损伤后COX-2表达显著增加。COX-2蛋白表达与PMN凋亡呈强烈负相关（γ = -0.75，p < 0.01）。体外实验显示，添加BALFALI可显著降低正常PMN的凋亡。添加BALFALI还与COX-2 mRNA水平升高有关。在添加BALFALI前10分钟用NS398处理培养物，可部分逆转所有这些效应。
肺内COX-2表达上调有助于ALI后PMN凋亡的抑制。
