Friedmacher Florian, Doi Takashi, Gosemann Jan-Hendrik, Fujiwara Naho, Kutasy Balazs, Puri Prem
National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.
Pediatr Surg Int. 2012 Feb;28(2):195-9. doi: 10.1007/s00383-011-2985-2.
Nitrofen model of congenital diaphragmatic hernia (CDH) has been widely used to investigate the pathogenesis of pulmonary hypoplasia (PH). Fibroblast growth factor (FGF) signaling pathway plays a fundamental role in fetal lung development. FGF7 and FGF10, which are critical for lung morphogenesis, have been reported to be downregulated in nitrofen-induced PH. FGF signaling is mediated by a family of four single transmembrane receptors, FGFR1-4. FGFR2 and FGFR3 have been shown to be expressed predominantly in the late stages of developing lungs. In addition, the upregulation of FGFR2 gene expression has been associated with severe defects in lung development and resulted in arrested alveologenesis similar to PH seen in the nitrofen model. Furthermore, FGFR3(-/-)FGFR4(-/-) double mutants showed thinner mesenchyme and larger air spaces. We designed this study to test the hypothesis that FGFR gene expression is upregulated in the late stages of lung development in the nitrofen CDH model.
Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Cesarean section was performed and fetuses were harvested on D18 and D21. Fetal lungs were divided into three groups: control, nitrofen without CDH [CDH(-)], and nitrofen with CDH [CDH(+)] (n = 24 at each time-point). Pulmonary gene expression levels of FGFR1-4 were analyzed by real-time RT-PCR. Immunohistochemistry was also performed to evaluate protein expression/distribution at each time-point.
The relative messenger RNA expression levels of pulmonary FGFR2 and FGFR3 on D21 were significantly increased in CDH(-) (6.38 ± 1.93 and 7.84 ± 2.86, respectively) and CDH(+) (7.09 ± 2.50 and 7.25 ± 3.43, respectively) compared to controls (P < 0.05 and P < 0.01, respectively), whereas no significant alteration was observed on D18. There were no differences in FGFR1 and FGFR4 expression at both time-points. Increased immunoreactivity of FGFR2 and FGFR3, mainly in the distal epithelium and mesenchyme, was observed in the nitrofen-induced hypoplastic lungs on D21 compared to controls.
Upregulation of FGFR2 and FGFR3 pulmonary gene expression in the late stages of fetal lung development may disrupt FGFR-mediated alveologenesis resulting in PH in the CDH model.
先天性膈疝（CDH）的硝呋烯腙模型已被广泛用于研究肺发育不全（PH）的发病机制。成纤维细胞生长因子（FGF）信号通路在胎儿肺发育中起重要作用。据报道，对肺形态发生至关重要的FGF7和FGF10在硝呋烯腙诱导的PH中表达下调。FGF信号由四种单跨膜受体家族FGFR1 - 4介导。FGFR2和FGFR3已被证明主要在发育中肺的后期表达。此外，FGFR2基因表达的上调与肺发育的严重缺陷有关，并导致肺泡形成停滞，类似于硝呋烯腙模型中所见的PH。此外，FGFR3（-/-）FGFR4（-/-）双突变体显示间充质更薄且气腔更大。我们设计本研究以检验以下假设：在硝呋烯腙CDH模型中，FGFR基因表达在肺发育后期上调。
妊娠第9天（D9）的孕鼠分别暴露于橄榄油或硝呋烯腙。在D18和D21进行剖宫产并收获胎儿。将胎儿肺分为三组：对照组、无CDH的硝呋烯腙组[CDH（-）]和有CDH的硝呋烯腙组[CDH（+）]（每个时间点n = 24）。通过实时RT-PCR分析FGFR1 - 4的肺基因表达水平。还进行了免疫组织化学以评估每个时间点的蛋白表达/分布。
与对照组相比，D21时CDH（-）组（分别为6.38±1.93和7.84±2.86）和CDH（+）组（分别为7.09±2.50和7.25±3.43）肺组织中FGFR2和FGFR3的相对信使RNA表达水平显著升高（分别为P < 0.05和P < 0.01），而在D18时未观察到显著变化。在两个时间点，FGFR1和FGFR4的表达均无差异。与对照组相比，在D21时硝呋烯腙诱导的发育不全肺中观察到FGFR2和FGFR3的免疫反应性增加，主要在远端上皮和间充质中。
胎儿肺发育后期FGFR2和FGFR3肺基因表达上调可能破坏FGFR介导的肺泡形成，导致CDH模型中的PH。
