Immune System Regulation Affected by a Murine Experimental Model of Bronchopulmonary Dysplasia: Genomic and Epigenetic Findings

Abstract

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a common cause of abrupted lung development after preterm birth. BPD may lead to increased rehospitalization, more severe and frequent respiratory infections, and life-long reduced lung function. The gene regulation in lungs with BPD is complex, with various genetic and epigenetic factors involved. OBJECTIVES: The aim of this study was to examine the regulatory relation between gene expression and the epigenome (DNA methylation) relevant for the immune system after hyperoxia followed by a recovery period in air using a mouse model of BPD. METHODS: Newborn mice pups were subjected to an immediate hyperoxic condition from birth and kept at 85% O2 levels for 14 days followed by a 14-day period in room air. Next, mice lung tissue was used for RNA and DNA extraction with subsequent microarray-based assessment of lung transcriptome and supplementary methylome analysis. RESULTS: The immune system-related transcriptomeregulation was affected in mouse lungs after hyperoxia. A high proportion of genes relevant in the immune system exhibited significant expression alterations, e.g., B cell-specific genes central to the cytokine-cytokine receptor interaction, the PI3K-AKT, and the B cell receptor signaling pathways. The findings were accompanied by significant DNA hypermethylation observed in the PI3K-AKT pathway and immune system-relevant genes. CONCLUSIONS: Oxygen damage could be partly responsible for the increased susceptibility and abnormal response to respiratory viruses and infections seen in premature babies with BPD through dysregulated genes.