Sexual dimorphism of the pulmonary transcriptome in neonatal hyperoxic lung injury: identification of angiogenesis as a key pathway

Abstract

Bronchopulmonary dysplasia (BPD) is characterized by impaired alveolar secondary septation and vascular growth. Exposure to high concentrations of oxygen (hyperoxia) contributes to the development of BPD. The male sex is considered an independent risk factor for the development of BPD. The reasons underlying sexually dimorphic outcomes in premature neonates are not known. We hypothesized that sex-specific modulation of biological processes in the lung under hyperoxic conditions contributes to sex-based differences. Neonatal male and female mice (C57BL/6) were exposed to hyperoxia [95% [Formula: see text], postnatal day (PND) 1-5: saccular stage of lung development] and euthanized on PND 7 or 21. Pulmonary gene expression was studied using RNA-Seq on the Illumina HiSeq 2500 platform. Analysis of the pulmonary transcriptome revealed differential sex-specific modulation of crucial pathways such as angiogenesis, response to hypoxia, inflammatory response, and p53 pathway. Candidate genes from these pathways were validated at the mRNA level by qPCR. Analysis also revealed sex-specific differences in the modulation of crucial transcription factors. Focusing on the differential modulation of the angiogenesis pathway, we also showed sex-specific differential activation of α-regulated genes using ChIP-qPCR and differences in expression of crucial genes () modulating angiogenesis. We demonstrate the translational relevance of our findings by showing that our murine sex-specific differences in gene expression correlate with those from a preexisting human BPD data set. In conclusion, we provide novel molecular insights into differential sex-specific modulation of the pulmonary transcriptome in neonatal hyperoxic lung injury and highlight angiogenesis as one of the crucial differentially modulated pathways.

Control Interventions Can Impact Alveolarization and the Transcriptome in Developing Mouse Lungs

“…These data highlight the ability of induction agents per se to alter lung development and the lung transcriptome when used to drive genome recombination. These are important considerations, given the increasing use of both conditional, inducible genome recombination (Surate Solaligue et al, ) and RNA‐Seq (Bhattacharya et al, ; Coarfa et al, ) to study post‐natal lung development. It may be useful to extend this idea to examine the inertness of other control interventions employed in newborn and adolescent mice for any impact on “baseline” alveolar architecture.…”

“…Screening for the male‐specific Sry locus and the sex‐independent Il3 genes, as described previously (Lambert et al, ), allowed determination of the sex of experimental animals. Since the lung transcriptome has been documented to have sex‐specific differenced (albeit under conditions of aberrant growth; Coarfa et al, ), and since the course of normal (Pozarska et al, ) and aberrant lung (Lingappan et al, ) alveolarization may be impacted by sex, the sex of each experimental animal is indicated in all graphs that report stereology and mRNA abundance data.…”

Pulmonary endothelial cells exhibit sexual dimorphism in their response to hyperoxia

“…Pulmonary endothelial cells are among the most sensitive to exposure to high concentrations of O 2 compared with other cell populations in the lung (22). Neonatal male mice exposed to hyperoxia show greater arrest in lung alveolarization and angiogenesis compared with females (10,19). Enomoto et al (12) reported that male neonatal rat pups had greater pulmonary arterial muscle contraction upon exposure to hyperoxia.…”

Endothelial to mesenchymal transition during neonatal hyperoxia‐induced pulmonary hypertension

“…Compared with females, male mice are more susceptible to developing neonatal hyperoxia‐induced lung injury [24,25,43]. This may be due to sex differences in the pulmonary transcriptome [44]. In addition, male sex is associated with increased severity of pulmonary hypertension in BPD patients [19].…”