Overactivated Epithelial NF-κB Disrupts Lung Development in Congenital Diaphragmatic Hernia.

Abnormal lung development is the main cause of morbidity and mortality in neonates with congenital diaphragmatic hernia (CDH), a common birth defect (1:2,500) of largely unknown pathobiology. Recent studies discovered that inflammatory processes, and specifically NF-κB-associated pathways, are enriched in human and experimental CDH. However, the molecular signaling of NF-κB in abnormal CDH lung development and its potential as a therapeutic target require further investigation. Using sections and hypoplastic lung explant cultures from the nitrofen rat model of CDH and human fetal CDH lungs, we demonstrate that NF-κB and its downstream transcriptional targets are hyperactive during abnormal lung formation in CDH. NF-κB activity was especially elevated in the airway epithelium of nitrofen and human CDH lungs at different developmental stages. Fetal rat lung explants had impaired pseudoglandular airway branching after exposure to nitrofen, together with increased phosphorylation and transcriptional activity of NF-κB. Dexamethasone, the broad and clinically applicable antiinflammatory NF-κB antagonist, rescued lung branching and normalized NF-κB signaling in hypoplastic lung explants. Moreover, specific NF-κB inhibition with curcumenol similarly rescued ex vivo lung hypoplasia and restored NF-κB signaling. Last, we showed that prenatal intraperitoneal dexamethasone administration to pregnant rat dams carrying fetuses with hypoplastic lungs significantly improves lung branching and normalizes NF-κB in vivo. Our results indicate that NF-κB is aberrantly activated in human and nitrofen CDH lungs. Antiinflammatory treatment with dexamethasone and/or specific NF-κB inhibition should be investigated further as a therapeutic avenue to target lung hypoplasia in CDH.

Proteomic Profiling of Hypoplastic Lungs Suggests an Underlying Inflammatory Response in the Pathogenesis of Abnormal Lung Development in Congenital Diaphragmatic Hernia.

The pathogenesis of lung hypoplasia in congenital diaphragmatic hernia (CDH), a common birth defect, is poorly understood. The diaphragmatic defect can be repaired surgically, but the abnormal lung development contributes to a high mortality in these patients. To understand the underlying pathobiology, we compared the proteomic profiles of fetal rat lungs at the alveolar stage (E21) that were either exposed to nitrofen in utero (CDH lungs, n=5) or exposed to vehicle only (non-CDH control lungs, n=5). Pathway analysis of proteomic datasets showed significant enrichment in inflammatory response proteins associated with cytokine signaling and Epstein Barr Virus in nitrofen CDH lungs. Among the 218 significantly altered proteins between CDH and non-CDH control lungs were Tenascin C, CREBBP, LYN, and STAT3. We showed that Tenascin C was decreased around the distal airway branches in nitrofen rat lungs and human CDH lungs, obtained from stillborn fetuses that did not receive pre- or postnatal treatment. In contrast, STAT3 was significantly increased in the airway epithelium of nitrofen lungs at E21. STAT3 inhibition after direct nitrofen exposure to fetal rat lung explants (E14.5) partially rescued the hypoplastic lung phenotype ex vivo by increasing peripheral lung budding. Moreover, we demonstrated that several STAT3-associated cytokines (IL-15, IL-9, andIL-2) are increased in fetal tracheal aspirates of CDH survivors compared with nonsurvivors after fetoscopic endoluminal tracheal occlusion. With our unbiased proteomics approach, we showed for the first time that downstream inflammatory processes are likely involved in the pathogenesis of abnormal lung development in CDH.