• Huozhi Wu, Shaoqing Lei, Jiang Yuan, Xin Liu, Dayong Zhang, Xiaoxia Gu, Liangqing Zhang, and Zhengyuan Xia.
• Department of Cardiothoracic Surgery, Fifth Affiliated Hospital of Zunyi Medical College, Zhuhai, China.
• J. Surg. Res. 2013 May 1;181(2):204-12.

BackgroundThe early growth response-1 (Egr-1) gene is upregulated after an ischemia-reperfusion (IR) challenge and upregulates target genes, such as proinflammatory cytokines. Ischemic postconditioning (IPostC) attenuates lung IR injury and reduces the systemic inflammatory response by activating heme oxygenase-1 (HO-1). However, the role of Egr-1 in IPostC protection against lung IR injury and inflammation and its interplay with HO-1 in IPostC protection is unknown.Materials And MethodsSprague-Dawley rats or cultured A549 cells were subjected to IR or hypoxia/reoxygenation with or without IPostC or hypoxic postconditioning in the presence or absence of Egr-1 inhibition using Egr-1 antisense oligodeoxyrinonucleotide or Egr-1 small interfering RNA transfection. Lung injury was assessed by measuring the lung wet/dry weight ratio, histologic change, and malondialdehyde content. The amount of lactate dehydrogenase release in culture medium was detected to evaluate cell injury. The protein expression of Egr-1, interleukin (IL)-1β, and HO-1 was assessed by Western blot.ResultsInhibition of Egr-1 significantly attenuated lung IR injury and the inflammation response caused by IR or hypoxia/reoxygenation, as shown by the alleviated lung pathologic changes, decreased pulmonary malondialdehyde content, wet/dry ratio, reduced release of the cytokines tumor necrosis factor-α, IL-6, and IL-8 in the bronchoalveolar lavage, and reduced Egr-1, IL-1β, and HO-1 protein expression and HO-1 activity. IPostC or hypoxic postconditioning reduced the postischemic Egr-1 expression and conferred similar protection against lung IR injury as Egr-1 inhibition.ConclusionsEgr-1 plays an important role in regulating the HO-1 production induced by IR or hypoxia/reoxygenation. Thus, downregulation of Egr-1 expression might represent one of the major mechanisms whereby IPostC confers protection against pulmonary IR insult.Copyright © 2013 Elsevier Inc. All rights reserved.

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