Abstract Rationale Preclinical rodent models of Bronchopulmonary Dysplasia often use only neonatal hyperoxia (O2) without exposure to the positive pressure mechanical ventilation (MV) commonly required in extremely premature infants. These models fail to fully recapitulate the lung function abnormalities and extracellular matrix (ECM) remodeling seen in former premature newborns. Our objective was to determine if a novel, survivable, non-invasive mouse model of combined neonatal O2-MV induces short-term transcriptomic shifts and later longer-term lung functional deficits and ECM remodeling in young adult mice. Methods Neonatal mice were exposed to either room air (RA) or hyperoxia (100% O2) on postnatal day (PND) 0. Cumulatively across PND1-4, the MV-exposed mice received 43,000 cycles of non-invasive positive-pressure ventilation with either RA or O2, breathing passive gas when not ventilated (Figure 1A). Separate non-ventilated mice were kept as controls. At PND4, lungs were harvested for bulk transcriptomics and histology, with separate mice returned to RA for PND28 recovery studies. At PND28, mice underwent pulmonary function testing, whole lung proteomics, and histology. Transcriptomic and proteomic data were analyzed using statistical software packages (DESeq2, ROmicsProcessor). Results At PND28, O2-control animals had increased compliance compared to RA-control mice, consistent with alveolar simplification. O2-MV animals, however, showed reversal of these functional changes (increased resistance, decreased compliance) without histological recovery, consistent with a stiffer, simplified lung (Figure 1B). PND28 whole-lung proteomics in O2-MV mice revealed ECM remodeling, with increased basement membrane collagen, decreased fibrillar collagen, and dysregulation of elastin compared to O2-controls (Figure 1C). Proteomic pathways were enriched for ECM-related pathways compared to O2-controls. At PND4, we identified transcriptomic shifts in the O2-MV group (Figure 1D), suggesting that the changes at PND28 were initiated during exposure rather than during recovery. Gene expression changes in O2-MV mice at PND4 included increased basement membrane collagen (Col4), metalloproteinases (Mmp2), and ECM glycoproteins (Thbs1), with decreased fibrillar (Col1) collagen and elastin (Eln) (Figure 1E). Transcriptomic pathways were enriched for actin-filament- and tight-junction-related pathways. Conclusion Simultaneous exposure to O2- MV results in long-term functional deficits and a simplified, stiffened lung with associated ECM remodeling. Short-term transcriptomic shifts are also unique to combined O2-MV, suggesting combined exposures may drive distinct lung responses that remain invisible in single exposures (O2 or MV) alone. This abstract is funded by: NIH K08HL155491
Dylag et al. (Fri,) studied this question.