Heparin binding VEGF isoforms attenuate hyperoxic embryonic lung growth retardation via a FLK1-neuropilin-1-PKC dependent pathway.

BACKGROUND: Previous work in our laboratory demonstrated that hyperoxia suppressed the expression of vascular endothelial growth factor (VEGF) by the embryonic lung, leading to increased epithelial cell apoptosis and failure of explant airway growth and branching that was rescued by the addition of Vegf165. The aims of this study were to determine protective pathways by which VEGF isoforms attenuate hyperoxic lung growth retardation and to identify the target cell for VEGF action. METHODS: Timed pregnant CD-1 or fetal liver kinase (FLK1)-eGFP lung explants cultured in 3% or 50% oxygen were treated ± Vegf121, VEGF164/Vegf165 or VEGF188 in the presence or absence of anti-rat neuropilin-1 (NRP1) antibody or GO6983 (protein kinase C (PKC) pan-inhibitor) and lung growth and branching quantified. Immunofluorescence studies were performed to determine apoptosis index and location of FLK1 phosphorylation and western blot studies of lung explants were performed to define the signaling pathways that mediate the protective effects of VEGF. RESULTS: Heparin-binding VEGF isoforms (VEGF164/Vegf165 and VEGF188) but not Vegf121 selectively reduced epithelial apoptosis and partially rescued lung bud branching and growth. These protective effects required NRP1-dependent FLK1 activation in endothelial cells. Analysis of downstream signaling pathways demonstrated that the VEGF-mediated anti-apoptotic effects were dependent on PKC activation. CONCLUSIONS: Vegf165 activates FLK1-NRP1 signaling in endothelial cells, leading to a PKC-dependent paracrine signal that in turn inhibits epithelial cell apoptosis.

Pediatric unilobar resection in primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD) causes chronic infections and progressive bronchiectasis that can lead to severe lung disease. Because there are no cures or regenerative therapy options for PCD, treatment of severe lung disease in PCD is focused on managing symptoms, including aggressive administration of antibiotics and diligent airway clearance. The Genetic Disorders of Mucociliary Clearance Consortium (GDMCC) does not recommend routine lobectomy, reserving its use for "rare cases of PCD with severe, localized bronchiectasis" and warns that a lobectomy should be treated with caution. However, if aggressive medical management fails, selective surgical removal of severely defective lung may result in maintenance or improvement of pulmonary function. Certainly, the decision to recommend lung resection in the face of chronic bronchiectasis from PCD requires an extensive discussion before it is considered as an alternative treatment. The purpose of this manuscript was to demonstrate that in selected cases of unilobar disease with bronchiectasis that are not responsive to other therapies (antibiotics and airway clearance), removal of localized necrotic areas of the lung along with prophylactic antibiotics can improve the quality of life of children with PCD associated bronchiectasis and improve growth and nutritional status, and pulmonary function.

A novel presentation of diffuse lung disease caused by congenital hypothyroidism.

A term infant was born with respiratory distress, and subsequent imaging, histopathologic, and hormonal studies confirmed congenital hypothyroidism. This report is intended to alert pediatricians to the possibility of congenital hypothyroidism as a cause of respiratory symptoms of unknown cause in neonates with respiratory distress.

ITGB (Integrin subunit beta) 3 mutation involved in pulmonary hemorrhage and osteopetrosis.

We report on a previously healthy infant who presented with pulmonary hemorrhage due to a rare hematologic disorder. He also had imaging and laboratory studies suggestive of osteopetrosis. A genetic testing uncovered a previously known integrin gene possibly involving both hematologic and bone tissues; however, the latter has been described only in mouse models.

Unusual pulmonary findings in mucolipidosis II.

We report undescribed pulmonary findings in a child with mucolipidosis II (ML-II). Children with ML-II bear significant pulmonary morbidity that may include extensive pulmonary fibrosis, persistent hemosiderosis as well as pulmonary airway excrescences as they reach preschool age.

Pulmonary squamous cell carcinoma associated with repaired congenital tracheoesophageal fistula and esophageal atresia.

We report a 19-year-old man with pulmonary squamous cell carcinoma (SCC) who had a history of vertebral, anal, cardiac, tracheal, esophageal, renal, and radial limb defects (VACTERL) association and tracheoesophageal fistula (TEF) + esophageal atresia (EA) repair as an infant. Children that undergo TEF + EA repair may have an increased risk for developing cancer as they reach adulthood.

VEGF attenuates hyperoxic injury through decreased apoptosis in explanted rat embryonic lung.

Ambient oxygen concentration and vascular endothelial growth factor (VEGF)-A are vital in lung development. Since hypoxia stimulates VEGF-A production and hyperoxia reduces it, we hypothesized that VEGF-A down-regulation by exposure of airways to hyperoxia may result in abnormal lung development. An established model of in vitro rat lung development was used to examine the effects of hyperoxia on embryonic lung morphogenesis and VEGF-A expression. Under physiologic conditions, lung explant growth and branching is similar to that seen in vivo. However, in hyperoxia (50% O2) the number of terminal buds and branch length was significantly reduced after 4 d of culture. This effect correlated with a significant increase in cellular apoptosis and decrease in proliferation compared with culture under physiologic conditions. mRNA for Vegf164 and Vegf188 was reduced during hyperoxia and addition of VEGF165, but not VEGF121, to explants grown in 50% O2 resulted in partial reversal of the decrease in lung branching, correlating with a decrease in cell apoptosis. Thus, hyperoxia suppresses VEGF-A expression and inhibits airway growth and branching. The ability of exogenous VEGF165 to partially reverse apoptotic effects suggests this may be a potential approach for the prevention of hyperoxic injury.