McCabe A J, Carlino U, Holm B A, Glick P L
Buffalo Institute of Fetal Therapy (BIFT), The Children's Hospital of Buffalo (Kaleida Health), Departments of Surgery, The State University of New York at Buffalo, School of Medicine and Biomedical Sciences, NY,USA.
J Pediatr Surg. 2001 Jan;36(1):128-32. doi: 10.1053/jpsu.2001.20029.
Congenital diaphragmatic hernia (CDH) carries a high mortality rate of 60% because of associated anomalies, pulmonary hypoplasia, pulmonary hypertension, and type II cell dysfunction. Prenatal tracheal ligation has been shown to improve lung growth in experimental models. This could be caused by a direct effect of increased endothoracic pressure in utero, secondary to the induction of specific growth factors, or both. Keratinocyte growth factor (KGF) is involved in normal lung organogenesis and is a potent mitogen of alveolar type II cells. The authors have therefore investigated the protein and mRNA levels of keratinocyte growth factor in the lung tissue of control, CDH, and CDH tracheal ligation lambs.
Eight lambs had left-sided diaphragmatic hernias surgically created at 80 days' gestation. Tracheal ligation was performed at 110 days in 4 lambs, and they were delivered by cesarean section at 140 to 145 days. Twin littermates served as controls. The lungs were dissected en bloc and snap frozen. KGF protein levels were determined by ELISA. Total RNA was isolated, and a RNase protection assay was performed using an ovine cDNA probe for KGF, and a human cDNA probe for GAPDH (house keeping control). Densitometric analysis was used to quantify the relative amounts of mRNA in each sample.
There was a significant decrease in the KGF protein levels of the CDH samples (110 v 73.2 pg/mg protein, P =.02). This decrease was mirrored by a significant fall in the level of mRNA expression for KGF (0.694 v 0.235, P = .02). Tracheal ligation normalized the KGF protein levels (96.1 pg/mg protein). This elevation of KGF protein was accompanied by an upregulation of KGF gene expression to control levels (0.56).
Tracheal ligation clearly is accompanied by an upregulation of keratinocyte growth factor protein and gene expression. It is not yet clear whether keratinocyte growth factor is solely responsible for the growth observed in these tracheal ligation preparations. Further growth factor blocking experiments are required.
先天性膈疝（CDH）由于合并其他异常、肺发育不全、肺动脉高压及Ⅱ型细胞功能障碍，死亡率高达60%。在实验模型中，产前气管结扎已被证明可促进肺生长。这可能是由于子宫内胸内压升高的直接作用，继发于特定生长因子的诱导，或两者兼而有之。角质形成细胞生长因子（KGF）参与正常肺器官形成，是肺泡Ⅱ型细胞的有效促分裂原。因此，作者研究了对照、CDH及CDH气管结扎羔羊肺组织中角质形成细胞生长因子的蛋白质和mRNA水平。
8只羔羊在妊娠80天时通过手术造成左侧膈疝。4只羔羊在妊娠110天时进行气管结扎，并于140至145天时剖宫产分娩。同窝双生羔羊作为对照。将肺整体解剖并速冻。通过酶联免疫吸附测定法（ELISA）测定KGF蛋白水平。分离总RNA，使用针对KGF的绵羊cDNA探针和针对甘油醛-3-磷酸脱氢酶（GAPDH，管家对照）的人cDNA探针进行核糖核酸酶保护试验。使用密度分析法对每个样本中mRNA的相对含量进行定量。
CDH样本的KGF蛋白水平显著降低（110对73.2 pg/mg蛋白，P = 0.02）。KGF mRNA表达水平的显著下降反映了这种降低（0.694对0.235，P = 0.02）。气管结扎使KGF蛋白水平恢复正常（96.1 pg/mg蛋白）。KGF蛋白的这种升高伴随着KGF基因表达上调至对照水平（0.56）。
气管结扎明显伴随着角质形成细胞生长因子蛋白和基因表达的上调。尚不清楚角质形成细胞生长因子是否是这些气管结扎制剂中观察到的生长的唯一原因。需要进一步进行生长因子阻断实验。
