Upregulation of keratinocyte growth factor in the tracheal ligation lamb model of congenital diaphragmatic hernia

Purpose: Congenital diaphragmatic hernia (CDH) carries a high mortality rat e of 60% because of associated anomalies, pulmonary hypoplasia, pulmonary h ypertension, and type II cell dysfunction. Prenatal tracheal ligation has b een shown to improve lung growth in experimental models. This could be caus ed by a direct effect of increased endothoracic pressure in utero, secondar y to the induction of specific growth factors, or both. Keratinocyte growth factor (KGF) is involved in normal lung organogenesis and is a potent mito gen 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. Methods: Eight lambs had left-sided diaphragmatic hernias surgically create d at 80 days' gestation. Tracheal ligation was performed at 110 days in 4 l ambs, 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 f rozen. KGF protein levels were determined by ELISA. Total RNA was isolated, and a RNase protection assay was performed using an ovine cDNA probe for K GF, and a human cDNA probe for GAPDH (house keeping control). Densitometric analysis was used to quantify the relative amounts of mRNA in each sample. Results: 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 0.23 5, 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). Conclusions: Tracheal ligation clearly is accompanied by an upregulation of keratinocyte growth factor protein and gene expression. It is not yet clea r whether keratinocyte growth factor is solely responsible for the growth o bserved in these tracheal ligation preparations. Further growth factor bloc king experiments are required. J Pediatr Surg 36:128-132. Copyright (C) 200 1 by W.B. Saunders Company.