α2AR 活化调控肺巨噬细胞极性转换对AKI致ALI的保护作用及机制研究

Acute lung injury(ALI) induced by Acute kidney injury(AKI) is one of common clinical manifestations of perioperative multiple organ dysfunction or failure. The mortality of combined AKI and ALI is as high as 80%. Therefore, it is of great significance to search for the related methods and mechanisms of lung protection. The imbalance of pulmonary macrophage (MФ) polarity homeostasis may be crucial to the damaged inflammation during ALI induced by AKI. M1Ф possesses pro-inflammatory function while M2Ф exerts anti-inflammatory and tissue repair properties. Macrophage polarity homeostasis-targeted interventions may be an importantly potential value to prevent ALI. The research supported by our previous foundation proved that α2 adrenoceptor(α2AR) activation could attenuate pulmonary vascular hyper-permeability caused by AKI through FAK signaling within pulmonary microvascular endothelial cells . Moreover, α2AR activation provided also the anti-inflammatory effect with an unclear mechanism. Besides, our preliminary experiments demonstrated that in the mice alveolar MФ, α2AR activation orchestrated its polarity from MФ or M1Ф to M2Ф in the presence or absence of LPS. Herein, the aim of the current study is to illustrate the mechanism of pulmonary MФ polarity switch modulated by α2AR activation as well as the value through the in vivo real-time microscopy and molecular biology techniques applied to the animal model with AKI-induced ALI or in vitro pulmonary blood barrier model. The novel strategy for relieving AKI-induced ALI may be anticipated.

急性肾损伤（AKI）所致急性肺损伤（ALI）是围术期多器官功能障碍或衰竭常见表现之一，AKI合并ALI时死亡率高达80%，探索相应肺保护手段和机制意义重大。肺内巨噬细胞（MФ）极性失稳态可能是AKI致ALI损伤性炎症反应的关键环节，M1Ф呈促炎活性，M2Ф具抗炎与组织修复功能，以其为靶标的防治研究具重要潜在价值。我们前期基金研究证实，α2肾上腺素受体（α2AR）活化通过肺微血管内皮细胞黏着斑激酶（FAK）信号通路减轻AKI所致肺血管高通透性，同时展现出机制不明的抗炎作用。进一步预实验显示小鼠肺泡MФ的α2AR活化，不仅可调控其极性转向M2Ф，还可逆转LPS所致极性变化从M1Ф到M2Ф。本研究拟通过建立AKI致ALI动物及体外肺血屏障模型，采用实时显微成像及相关分子生物学技术，阐明α2AR活化调控肺MФ保护性极性转换的具体机制及意义，以期为AKI所致ALI的防治提供一种新策略。

围术期缺血再灌注（IR）所致急性肾损伤（AKI）常见，AKI所诱发系统性炎症反应和氧化应激反应可致肾外远端器官病理性损伤和功能障碍，此为其死亡率居高不下的重要原因。由于肺脏拥有巨大毛细血管网络，更易形成肾-肺交联应答而出现急性肺损伤（ALI）。重症患者单纯AKI死亡率为44.7-53%，AKI合并ALI时死亡率高达80%，目前缺乏有效防治手段，探索相应肺保护方法和机制意义重大。肺部巨噬细胞对ALI炎症反应的启动、维持与消退、损伤肺组织的修复与重塑发挥了重要调控作用。本项目基于前期α2肾上腺素受体（α2AR）活化改善AKI所致肺血管高通透性的研究发现及预实验结果提示，通过构建AKI致ALI、LPS致ALI动物模型，体外培养肺巨噬细胞（MH-S）、肺微血管内皮细胞（PMVECs）和肺上皮细胞（A549），应用α2AR激动剂右美托咪定（Dex）及α2AR拮抗剂阿替美唑（Atip），采用蛋白质芯片、免疫荧光、Western blot、Real-time PCR、ELISA和流式细胞等技术，探索了AKI致ALI时肺部巨噬细胞极性变化状况、Dex对巨噬细胞极性转换及系统性炎症反应的作用及机制、Dex对PMVECs和肺上皮细胞的保护作用。研究发现，①Dex可调控巨噬细胞极性从促炎型（M1）向抗炎修复型（M2）转换，抑制肾IR系统性炎症反应并减轻ALI；②Dex通过α2AR/PI3K/Akt通路改善肾脏IR诱导的肺细胞凋亡；③Dex通过激活Akt、STAT6和IRF4调节ALI的巨噬细胞极性表型转换，并保护肺上皮细胞；④Dex还可通过激活胆碱能抗炎通路减轻肾IR损伤。这些研究结果，对临床应用α2AR激动剂改善围术期AKI及其合并ALI的预后提供了基础理论。

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