mTOR Inhibition Promotes Pneumonitis through Inducing Endothelial Contraction and Hyperpermeability
mTOR Inhibition Promotes Pneumonitis through Inducing Endothelial Contraction and Hyperpermeability
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mTOR 抑制通过诱导内皮收缩和通透性过高促进肺炎
DOI：
10.1165/rcmb.2020-0390oc
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发表时间：
2021-12-01
影响因子：
6.4
通讯作者：
Sun, ChongXiu
中科院分区：
文献类型：
--
作者：
Chen, Xiaolin;Hu, Chengxiu;Sun, ChongXiu
内皮细胞（EC）屏障功能受损是炎症性疾病的标志。mTOR抑制剂，广泛应用于临床治疗，通过尚未完全理解的机制引起肺炎。本研究旨在阐明由mTOR抑制（mTORi）引起的肺炎发病机制的EC机制。对具有mTOR复合物组分（Mtor、Rptor或Rictor）的EC特异性缺失的小鼠施用LPS以诱导肺损伤。用药理学抑制剂、siRNA或过表达质粒处理培养的EC。用伊文思蓝法在体内评价EC屏障功能，用跨内皮电阻和白蛋白通量测定在体外评价EC屏障功能。mTORi增加基础和TNF α诱导的EC通透性，这是由肌球蛋白轻链（MLC）磷酸化依赖性细胞收缩引起的。mTOR激酶活性被mTORi失活触发PKC δ/p38/NF-κ B信号传导，其显著上调TNF α诱导的MLCK（MLC激酶）表达，而Raptor促进PKC α/MYPT I的磷酸化，而不依赖于其与mTOR的相互作用，导致MLCP（MLC磷酸酶）活性的抑制。在LPS处理的小鼠中，mTOR、Raptor或Rictor中的EC特异性缺陷加重了肺部炎症。这些发现揭示了mTORi诱导PKC依赖性内皮MLC磷酸化、收缩和高通透性，从而促进肺炎。
Compromised endothelial-cell (EC) barrier function is a hallmark of inflammatory diseases. mTOR inhibitors, widely applied as clinical therapies, cause pneumonitis through mechanisms that are not yet fully understood. This study aimed to elucidate the EC mechanisms underlying the pathogenesis of pneumonitis caused by mTOR inhibition (mTORi). Mice with EC-specific deletion of mTOR complex components (Mtor, Rptor or Rictor) were administered LPS to induce pulmonary injury. Cultured ECs were treated with pharmacologic inhibitors, siRNA, or overexpression plasmids. EC barrier function was evaluated in vivo with Evans blue assay and in vitro by measurement of transendothelial electrical resistance and albumin flux. mTORi increased basal and TNF alpha- induced EC permeability, which was caused by myosin light chain (MLC) phosphorylation-dependent cell contraction. Inactivation of mTOR kinase activity by mTORi triggered PKC delta/p38/NF-kappa B signaling that significantly upregulated TNF alpha-induced MLCK (MLC kinase) expression, whereas Raptor promoted the phosphorylation of PKC alpha/MYPT I independently of its interaction with mTOR, leading to suppression of MLCP (MLC phosphatase) activity. EC-specific deficiency in mTOR, Raptor or Rictor aggravated lung inflammation in LPS-treated mice. These findings reveal that mTORi induces PKC-dependent endothelial MLC phosphorylation, contraction, and hyperpermeability that promote pneumonitis.