Introduction

We have earlier shown that hyperoxia (HO)-induced sphingosine kinase 1 (SPHK1)/sphingosine-1-phosphate (S1P) signaling contribute to bronchopulmonary dysplasia (BPD). S1P acts through G protein-coupled receptors, S1P₁ through S1P₅. Further, we noted that heterozygous deletion of S1pr1 ameliorated the HO-induced BPD in the murine model. The mechanism by which S1P₁ signaling contributes to HO-induced BPD was explored.

Methods

S1pr1^+/+ and S1pr1^+/− mice pups were exposed to either room air (RA) or HO (75% oxygen) for 7 days from PN 1–7. Lung injury and alveolar simplification was evaluated. Lung protein expression was determined by Western blotting and immunohistochemistry (IHC). In vitro experiments were performed using human lung microvascular endothelial cells (HLMVECs) with S1P₁ inhibitor, NIBR0213 to interrogate the S1P₁ signaling pathway.

Results

HO increased the expression of S1pr1 gene as well as S1P₁ protein in both neonatal lungs and HLMVECs. The S1pr1^+/− neonatal mice showed significant protection against HO-induced BPD which was accompanied by reduced inflammation markers in the bronchoalveolar lavage fluid. HO-induced reduction in ANG-1, TIE-2, and VEGF was rescued in S1pr1^+/− mouse, accompanied by an improvement in the number of arterioles in the lung. HLMVECs exposed to HO increased the expression of KLF-2 accompanied by reduced expression of TIE-2, which was reversed with S1P₁ inhibition.

Conclusion

HO induces S1P₁ followed by reduced expression of angiogenic factors. Reduction of S1P₁ signaling restores ANG-1/ TIE-2 signaling leading to improved angiogenesis and alveolarization thus protecting against HO-induced neonatal lung injury.

中文翻译：

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高氧诱导的 S1P1 信号通过抑制 TIE-2 减少血管生成，导致实验性支气管肺发育不良

介绍

我们之前已经表明，高氧 (H2O) 诱导的鞘氨醇激酶 1 (SPHK1)/1-磷酸鞘氨醇 (S1P) 信号传导有助于支气管肺发育不良 (BPD)。S1P 通过 G 蛋白偶联受体 S1P ₁至 S1P ₅发挥作用。此外，我们注意到S1pr1的杂合缺失改善了小鼠模型中 H O 诱导的 BPD。探索了S1P ₁信号传导促进 H2O 诱导的 BPD 的机制。

方法

从 PN 1-7 开始， S1pr1 ^+/+和S1pr1 ^+/-小鼠幼崽暴露于室内空气 (RA) 或 H2O (75% 氧气) 7 天。评估了肺损伤和肺泡简化。通过蛋白质印迹和免疫组织化学（IHC）确定肺蛋白表达。_{使用具有 S1P 1}抑制剂 NIBR0213 的人肺微血管内皮细胞 (HLMVEC) 进行体外实验，以询问 S1P ₁信号通路。

结果

H2O 增加了新生儿肺和 HLMVECs中S1pr1基因和 S1P _{1蛋白的表达。}S1pr1 ^+/-新生小鼠显示出对 H2O 诱导的 BPD 的显着保护，同时伴有支气管肺泡灌洗液中炎症标志物的减少。H2O 诱导的 ANG-1、TIE-2 和 VEGF 减少在S1pr1 ^{+/ -}小鼠中得到拯救，伴随着肺中小动脉数量的改善。暴露于 H2O 的 HLMVEC 增加了 KLF-2 的表达，同时 TIE-2 的表达减少，这与 S1P ₁抑制相反。

结论

H2O 诱导 S1P ₁，然后降低血管生成因子的表达。S1P ₁信号传导的减少可恢复 ANG-1/TIE-2 信号传导，从而改善血管生成和肺泡化，从而防止 H2O 诱导的新生儿肺损伤。