TGF-β signaling promotes survival and repair in rat alveolar epithelial type 2 cells during recovery after hyperoxic injury
TGF-β signaling promotes survival and repair in rat alveolar epithelial type 2 cells during recovery after hyperoxic injury
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DOI：
10.1152/ajplung.00294.2007
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发表时间：
2008-04-01
影响因子：
4.9
通讯作者：
Warburton, D.
中科院分区：
文献类型：
--
作者：
Buckley, S.;Shi, W.;Warburton, D.
在氧暴露期间用肌苷处理的高氧大鼠在支气管肺泡灌洗液（BAL）中具有增加的活性转化生长因子（TGF）-β水平，然而从这些动物分离的肺泡上皮2型细胞（AEC 2）表现出较少的高氧诱导的DNA损伤和增加的活性Smad 2表达。为了确定TGF-β 1信号本身是否保护AEC 2免受高氧损伤，将新鲜分离的来自高氧大鼠的AEC 2与TGF-β 1孵育24小时，并通过荧光素激活的细胞分选仪分析TdT介导的dUTP缺口末端标记来测定DNA损伤。TGF-β 1在类似于肌苷处理的高氧动物BAL中的浓度范围内（50- 5，000 pg/ml）具有保护作用。TGF-β 1还增强了高氧诱导的DNA修复活性和细胞迁移，刺激了纤连蛋白的自分泌分泌，加速了单层划痕伤口的闭合，并通过AEC 2将高氧耗尽的VEGF分泌恢复到含氧量正常的水平。TGF-β受体I型激活素样激酶-4、-5和-7抑制肽SB-505124消除了TGF-β对高氧DNA损伤的保护作用，并增加了常氧细胞中TdT介导的dUTP缺口末端标记。这些数据表明，内源性TGF-β介导的Smad信号传导是体外AEC 2稳态所需的，而外源性TGF-β 1治疗高氧损伤的AEC 2导致细胞能够存活、修复、迁移、分泌基质，并比单独高氧引发的AEC 2更有效地诱导新血管形成。
Hyperoxic rats treated with inosine during oxygen exposure have increased levels of active transforming growth factor (TGF)-beta in the bronchoalveolar lavage (BAL), yet alveolar epithelial type 2 cells (AEC2) isolated from these animals demonstrate less hyperoxia-induced DNA damage and increased expression of active Smad2. To determine whether TGF-beta 1 signaling per se protected AEC2 against hyperoxic damage, freshly isolated AEC2 from hyperoxic rats were incubated with TGF-beta 1 for 24 h and assayed for DNA damage by fluorescein-activated cell sorter analysis of TdT-mediated dUTP nick end labeling. TGF-beta 1 was protective over a concentration range similar to that in BAL of inosine-treated hyperoxic animals (50-5,000 pg/ml). TGF-beta 1 also augmented hyperoxia-induced DNA repair activity and cell migration, stimulated autocrine secretion of fibronectin, accelerated closure of a monolayer scratch wound, and restored hyperoxia-depleted VEGF secretion by AEC2 to normoxic levels. The TGF-beta receptor type I activin-like kinase-4, -5, and -7 inhibitor peptide SB-505124 abolished the protective effect of TGF-beta on hyperoxic DNA damage and increased TdT-mediated dUTP nick end labeling in normoxic cells. These data suggest that endogenous TGF-beta-mediated Smad signaling is required for AEC2 homeostasis in vitro, while exogenous TGF-beta 1 treatment of hyperoxia-damaged AEC2 results in a cell that is equipped to survive, repair, migrate, secrete matrix, and induce new blood vessel formation more efficiently than AEC2 primed by hyperoxia alone.