The highly orchestrated interactions between the epithelium and mesenchyme required for normal lung development can be disrupted by perinatal
inflammation in preterm infants, although the mechanisms are incompletely understood. We used transgenic (inhibitory κB
kinase β transactivated) mice that conditionally express an activator of the NF-κB pathway in airway epithelium to investigate the impact of epithelial-derived
inflammation during lung development. Epithelial NF-κB activation selectively impaired saccular stage lung development, with a phenotype comprising rapidly progressive distal airspace dilation, impaired gas exchange, and perinatal lethality. Epithelial-derived
inflammation resulted in disrupted elastic fiber organization and down-regulation of
elastin assembly components, including fibulins 4 and 5,
lysyl oxidase like-1, and
fibrillin-1. Fibulin-5 expression by saccular stage lung fibroblasts was consistently inhibited by treatment with bronchoalveolar lavage fluid from inhibitory κB
kinase β transactivated mice, Escherichia coli
lipopolysaccharide, or tracheal aspirates from preterm infants exposed to
chorioamnionitis. Expression of a dominant NF-κB inhibitor in fibroblasts restored fibulin-5 expression after
lipopolysaccharide treatment, whereas reconstitution of fibulin-5 rescued extracellular
elastin assembly by saccular stage lung fibroblasts.
Elastin organization was disrupted in saccular stage lungs of preterm infants exposed to systemic
inflammation. Our study reveals a critical window for
elastin assembly during the saccular stage that is disrupted by inflammatory signaling and could be amenable to interventions that restore elastic fiber assembly in the developing lung.