Neutrophilic inflammation during lung development disrupts elastin assembly and predisposes adult mice to COPD

J Clin Invest. 2020 Oct 27;139481. doi: 10.1172/JCI139481. Online ahead of print.


Emerging evidence indicates that early life events can increase the risk for developing chronic obstructive pulmonary disease (COPD). Using an inducible transgenic mouse model for NF-κB activation in the airway epithelium, we found that a brief period of inflammation during the saccular stage [postnatal day (PN)3 - PN5] but not alveolar stage (PN10 - PN12) of lung development disrupts elastic fiber assembly, resulting in permanent reduction in lung function and development of a COPD-like lung phenotype that progresses through 24 months of age. Neutrophil depletion prevented disruption of elastic fiber assembly and restored normal lung development. Mechanistic studies uncovered a role for neutrophil elastase (NE) in downregulating expression of critical elastic fiber assembly components, particularly fibulin-5 and elastin. Further, both purified human NE and NE-containing exosomes from tracheal aspirates of premature infants with lung inflammation down-regulated elastin and fibulin-5 expression by saccular stage mouse lung fibroblasts. Together, our studies define a critical developmental window for assembling the elastin scaffold in the distal lung, which is required to support lung structure and function throughout the lifespan. While neutrophils play a well-recognized role in COPD development in adults, neutrophilic inflammation may also contribute to early life predisposition to COPD.

Keywords: COPD; Extracellular matrix; Inflammation; Neutrophils; Pulmonology.