1Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine.
2Acute Lung Injury Center of Excellence.
Am J Respir Cell Mol Biol. 2019 Aug;61(2):244-256. doi: 10.1165/rcmb.2018-0207OC.
Primary graft dysfunction (PGD) is a major cause of morbidity and mortality after lung transplantation. Ischemia-reperfusion injury (IRI) is a key event that contributes to PGD, though complex interactions affect donor lungs status, such as preceding brain death (BD), hemorrhagic shock (HS), and pre-engraftment lung management, the latter recognized as important risk factors for PGD. We hypothesized that a multi-hit isogenic mouse model of lung transplantation is more closely linked to PGD than IRI alone. Left lung transplants were performed between inbred C57BL/6 mice. A one-hit model of IRI was established by inducing cold ischemia (CI) of the donor lungs at 0°C for 1, 72, or 96 hours before engraftment. Multi-hit models were established by inducing 24 hours of HS and/or 3 hours of BD before 24 hours of CI. The recipients were killed at 24 hours after transplant and lung graft samples were analyzed. In the one-hit model of IRI, up to 72-hour CI time resulted in minimal cellular infiltration near small arteries after 24-hour reperfusion. Extension of CI time to 96 hours led to increased cellular infiltration and necroptotic pathway activation, without evidence of apoptosis, after 24-hour reperfusion. In a multi-hit model of PGD, "HS + BD + IRI" demonstrated increased lung injury, cellular infiltration, and activation of necroptotic and apoptotic pathways compared with IRI alone. Treatment with an inhibitor of receptor-interacting protein kinase 1 kinase, necrostatin-1, resulted in a significant decrease of downstream necroptotic pathway activation in both single- and multi-hit models of IRI. Thus, activation of necroptosis is a central event in IRI after prolonged CI, though it may not be sufficient to cause PGD alone. Pathological evaluation of donor lungs after CI-induced IRI, in conjunction with pre-engraftment donor lung factors in our multi-hit model, demonstrated early evidence of lung injury consistent with PGD. Our findings support the premise that pre-existing donor lung status is more important than CI time alone for inflammatory pathway activation in PGD, which may have important clinical implications for donor lung retrieval.
原发性移植物功能障碍（PGD）是肺移植后发病率和死亡率的主要原因。缺血再灌注损伤（IRI）是导致 PGD 的一个关键事件，但复杂的相互作用会影响供体肺的状态，如先前的脑死亡（BD）、失血性休克（HS）和移植前的肺管理，后者被认为是 PGD 的重要危险因素。我们假设，肺移植的多打击同种小鼠模型与单独的 IRI 相比，与 PGD 的联系更紧密。在近交 C57BL/6 小鼠之间进行左肺移植。通过在移植前将供体肺置于 0°C 下进行 1、72 或 96 小时的冷缺血（CI），建立 IRI 的单次打击模型。通过在 24 小时的 CI 前诱导 24 小时的 HS 和/或 3 小时的 BD，建立多打击模型。在移植后 24 小时处死受体，并分析肺移植物样本。在 IRI 的单次打击模型中，在 24 小时再灌注后，长达 72 小时的 CI 时间导致小动脉附近的细胞浸润最小。CI 时间延长至 96 小时后，在 24 小时再灌注后，导致细胞浸润和坏死性途径激活增加，而没有凋亡的证据。在 PGD 的多打击模型中，与单独的 IRI 相比，“HS+BD+IRI”显示出更高的肺损伤、细胞浸润以及坏死性和凋亡途径的激活。用受体相互作用蛋白激酶 1 激酶抑制剂 necrostatin-1 治疗，在 IRI 的单打击和多打击模型中均显著降低下游坏死性途径的激活。因此，在长时间 CI 后，坏死性凋亡的激活是 IRI 的一个中心事件，尽管它可能不足以单独引起 PGD。在我们的多打击模型中，对 CI 诱导的 IRI 后供体肺的病理评估以及移植前供体肺因素的评估，显示出与 PGD 一致的早期肺损伤证据。我们的发现支持这样的前提，即供体肺的预先存在的状态比 IRI 时间本身对 PGD 中炎症途径的激活更为重要，这可能对供体肺的获取具有重要的临床意义。
