Fig. 1

Oxygen exposure reduces intestinal antimicrobial peptide expression. A Neonatal C57BL/6 J mice were exposed to normoxia or hyperoxia from the 3^rd-14.^th day of life (n = 4 litters with 5–7 neonatal mice/litter per exposure group). FiO₂, fraction of inspired oxygen. SPF, specific-pathogen-free. B Representative photomicrographs of the distal lung sections of 14-day-old mice. C Hyperoxia exposure is associated with alterations in lung morphology and function. Data are shown as mean ± SEM, with significance testing by a two-tailed t-test. D Volcano plot of ileal gene expression array showing gene expression altered by hyperoxia exposure. E Heatmap showing genes regulated by hyperoxia exposure. F Principal components analysis showing differential clustering of normoxia and hyperoxia exposed ileal genes. PC, principal component. G Ileal antimicrobial peptide expression is decreased in hyperoxia-exposure mice. H Community diversity of the adherent and luminal ileal bacterial microbiome is not significantly altered by hyperoxia exposure. I The relative abundance of an operational taxonomic unit (OTU 002) that aligns to the genus Staphylococcus increases after hyperoxia exposure, as do OTUs aligning to Corynebacterium (OTU 124) and Romboutsia (OTU 013). Data are shown as mean ± SEM, with significance testing by a two-tailed t-test. J Principal coordinates analysis of Bray–Curtis dissimilarity shows global alterations in community composition in hyperoxia-exposed mice. Significance testing by permutational ANOVA (PERMANOVA), with equivocal dispersion confirmed by permutational multivariate analysis of dispersion (PERMDISP). PC, principal component. K Loading plot of principal components analysis of Hellinger transformed Euclidian distances showing the contribution of specific genera to the global community composition. Schematic in (A) was generated using BioRender. See also Figures S1, S2 and S5