The Children's Research Centre, Our Lady's Children's Hospital, Dublin 12, Ireland.
J Pediatr Surg. 2009 Dec;44(12):2302-6. doi: 10.1016/j.jpedsurg.2009.07.069.
The pathogenesis of pulmonary hypoplasia in nitrofen-induced congenital diaphragmatic hernia (CDH) still remains unclear. Wnt signaling pathways play a critical role in lung development. Whereas canonical Wnt signaling regulates branching morphogenesis during early lung development, the noncanonical Wnt5a controls late lung morphogenesis, including patterning of distal airway and vascular tubulogenesis (alveolarization). Overexpression of Wnt5a in transgenic mice and in the chick has been reported to result in severe pulmonary hypoplasia. We designed this study to test the hypothesis that the pulmonary Wnt5a gene expression is up-regulated in late stages of lung morphogenesis in CDH.
Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Fetal lungs were harvested on D15, D18, and D21 and divided into 3 groups: control; nitrofen without CDH, CDH(-); and nitrofen with CDH, CDH(+) (n = 8 at each time-point, respectively). Wnt5a pulmonary gene expression was analyzed by real-time reverse transcription polymerase chain reaction. Immunohistochemistry was performed to evaluate Wnt5a protein expression at each time-point.
Pulmonary relative mRNA expression levels of Wnt5a were significantly increased in CDH(-) and CDH(+) at D18 (1.61 +/- 0.92 and 1.81 +/- 1.20, respectively) and D21 (2.40 +/- 0.74* and 2.65 +/- 0.35*, respectively) compared to controls at D18 and D21 (0.90 +/- 0.17* and 1.69 +/- 0.53**, respectively) (*P < .05, **P < .001 vs control ). Strong Wnt5a immunoreactivity was seen in the distal epithelium at D18 and D21 in nitrofen-induced hypoplastic lung compared to controls.
Up-regulation of pulmonary Wnt5a gene expression in the late lung morphogenesis may interfere with patterning of alveolarization, causing pulmonary hypoplasia in the nitrofen-induced CDH.
在二硝基酚诱导的先天性膈疝（CDH）中，肺发育不全的发病机制仍不清楚。Wnt 信号通路在肺发育中起着关键作用。经典 Wnt 信号在早期肺发育中调节分支形态发生，而非经典 Wnt5a 控制晚期肺形态发生，包括远端气道的模式形成和血管管腔形成（肺泡化）。转基因小鼠和鸡中 Wnt5a 的过表达已被报道导致严重的肺发育不全。我们设计了这项研究来检验以下假设：在 CDH 的肺形态发生晚期，肺 Wnt5a 基因表达上调。
妊娠大鼠在妊娠第 9 天（D9）接受橄榄油或二硝基酚处理。在 D15、D18 和 D21 收获胎儿肺，并分为 3 组：对照组；无 CDH 的二硝基酚组，CDH(-)；有 CDH 的二硝基酚组，CDH(+)（分别在每个时间点各有 8 只）。通过实时逆转录聚合酶链反应分析 Wnt5a 肺基因表达。在每个时间点进行免疫组织化学以评估 Wnt5a 蛋白表达。
在 D18（1.61±0.92 和 1.81±1.20）和 D21（2.40±0.74和 2.65±0.35）时，CDH(-)和 CDH(+)的肺相对 mRNA 表达水平明显高于对照组，分别在 D18 和 D21（0.90±0.17和 1.69±0.53*）（*P<0.05，**P<0.001 与对照组相比）。在二硝基酚诱导的肺发育不全的远端上皮中，在 D18 和 D21 时，与对照组相比，Wnt5a 免疫反应性较强。
晚期肺形态发生中肺 Wnt5a 基因表达的上调可能干扰肺泡化的模式形成，导致二硝基酚诱导的 CDH 中的肺发育不全。
