Liu Xiaomei, Lin Yan, Tian Baoling, Miao Jianing, Xi Chunyan, Liu Caixia
Key Laboratory of Health Ministry for Congenital Malformations, Shengjing Hospital of China Medical University ShenYang, China.
Department of Internal Medicine, Shengjing Hospital of China Medical University ShenYang, China.
Int J Clin Exp Pathol. 2014 May 15;7(6):3101-11. eCollection 2014.
Epidemiological studies have demonstrated that intrauterine growth restriction (IUGR) increases the risk for respiratory morbidity from infancy, throughout childhood and into adulthood. Chronic restriction of nutrients causes abnormalities in the airways and lungs of offspring, but whether IUGR adversely impacts fetal pulmonary vascular development and underlying mechanisms remain under investigation. In this study, we investigated the effects of protein malnutrition in utero on pulmonary alveolarization and vascular growth of the fetal lung and placentae. Pregnant rats were feed with an isocaloric low-protein diet (8% protein) until delivery. Placenta and fetal lungs were harvested on 20th day of gestation (term 21 days of gestation). Lung index (lung weight as a percentage of body weight), total DNA and protein, radial alveolar count, arteriolar wall thickness, lung maturity and angiogenic factor VEGF were assessed. The lung was hypoplastic in IUGR fetus, evidenced by reduction in lung weight, DNA and protein content. Protein restriction in utero led to higher glycogen levels, but reduced number of alveoli as confirmed by the measurement of radial alveolar counts. IUGR fetus had significantly reduced VEGF, Flk-1 levels in lung but no changes in Flt-1 mRNA. Furthermore, IUGR was associated with increased lung miR-126-3p levels, which modulated the expression of angiogenic factor. In contrast, with regard to the placenta, IUGR fetus presented with decreased expression of VEGF, with no changes in VEGF receptors and expression-regulating miRNAs. This work suggested that VEGF signaling defect plays an important role in the defective lung development, which may explain the increased incidence of respiratory infections in IUGR patients.
流行病学研究表明,宫内生长受限(IUGR)会增加从婴儿期到整个儿童期直至成年期发生呼吸系统疾病的风险。营养物质的长期受限会导致后代气道和肺部出现异常,但IUGR是否会对胎儿肺血管发育产生不利影响及其潜在机制仍在研究中。在本研究中,我们调查了子宫内蛋白质营养不良对胎儿肺和胎盘的肺泡化及血管生长的影响。将怀孕大鼠喂食等热量的低蛋白饮食(8%蛋白质)直至分娩。在妊娠第20天(妊娠期为21天)收获胎盘和胎儿肺。评估肺指数(肺重量占体重的百分比)、总DNA和蛋白质、肺泡计数、小动脉壁厚度、肺成熟度和血管生成因子VEGF。IUGR胎儿的肺发育不全,表现为肺重量、DNA和蛋白质含量降低。子宫内蛋白质限制导致糖原水平升高,但通过测量肺泡计数证实肺泡数量减少。IUGR胎儿肺中的VEGF、Flk-1水平显著降低,但Flt-1 mRNA无变化。此外,IUGR与肺miR-126-3p水平升高有关,其调节血管生成因子的表达。相比之下,关于胎盘,IUGR胎儿的VEGF表达降低,VEGF受体和表达调节性miRNA无变化。这项研究表明,VEGF信号缺陷在肺发育缺陷中起重要作用,这可能解释了IUGR患者呼吸道感染发病率增加的原因。