Project description:Bronchopulmonary dysplasia (BPD), a chronic pulmonary sequela of preterm birth, increases susceptibility to respiratory viral infection. Exposure to hyperoxia of neontal mice (a model of BPD) increases the number of activated, IL-12 producing lung CD103+ dendritic cells (DCs) and augments the inflammatory response to rhinovirus infection. We used microarray analysis to detail the effect of hyperoxia on the gene expression of the two main subsets of lung cDC, including CD103+ DCs and CD11bhi DC. We identified distinct up- and down-regulated genes in response to hyperoxia in both cDC subclasses.
Project description:Growth Differentiation Factor 15 (GDF15) is a divergent member of the TGF-β superfamily, and its expression increases under various stress conditions, including inflammation, hyperoxia, and senescence. GDF15 expression is increased in neonatal murine BPD models, and GDF15 loss exacerbates oxidative stress and decreases viability in vitro in pulmonary epithelial and endothelial cells. Our overall hypothesis is that the loss of GDF15 will exacerbate hyperoxic lung injury in the neonatal lung in vivo. We exposed neonatal Gdf15-/- mice and wild-type (WT) controls on a similar background to room air or hyperoxia (95% O2) for 5 days after birth. The mice were euthanized on PND 21. Gdf15 -/- mice had higher mortality and lower body weight than WT mice after exposure to hyperoxia. Upon exposure to hyperoxia, female mice had higher alveolar simplification in the Gdf15-/- group than the female WT group. Gdf15-/- and WT mice showed no difference in the degree of the arrest in angiogenesis upon exposure to hyperoxia. Gdf15-/- mice showed lower macrophage count in the lungs compared to WT mice. Our results suggest that Gdf15 deficiency decreases the tolerance to hyperoxic lung injury with evidence of sex-specific differences.
Project description:Bronchopulmonary dysplasia (BPD) is characterized by an arrest in alveolarization, abnormal vascular development and variable interstitial fibroproliferation in the premature lung. Endothelial to mesenchymal transition (Endo-MT) may be a source of pathologic fibrosis in many organ systems. Whether Endo-MT contributes to the pathogenesis of BPD is not known. We tested the hypothesis that pulmonary endothelial cells will show increased expression of Endo-MT markers upon exposure to hyperoxia and that sex as a biological variable will modulate differences in expression. WT and Cdh5-PAC CreERT2 (endothelial reporter) neonatal male and female mice (C57BL6) were exposed to hyperoxia (0.95 FiO2) either during the saccular stage of lung development (95% FiO2; PND1-5) or through the saccular and early alveolar stages of lung development (75% FiO2; PND1-14). Expression of Endo-MT markers were measured in whole lung and endothelial cell mRNA. Sorted lung endothelial cells were subjected to bulk RNA-Seq. We show that exposure of the neonatal lung to hyperoxia leads to upregulation of key markers of EndoMT Neonatal male mice show higher expression of genes related to EndoMT. Furthermore, using lung sc-RNAseq data from neonatal lung we were able to show that xxx. Markers related to Endo-MT are upregulated in the neonatal lung upon exposure to hyperoxia and show sex-specific differences. Mechanisms mediating EndoMT in the injured neonatal lung can modulate the response of the neonatal lung to hyperoxic injury and need further investigation.
Project description:Recovery from lung injury during the neonatal period requires the orchestration of many biological pathways. Modulation of biological pathways can drive the developing lung towards proper repair or persistent maldevelopment after injury that can lead to a disease phenotype. Sex as a biological variable can modulate these pathways differently in the male and female lung exposed to neonatal hyperoxia. In this study, we assessed the contribution of cellular diversity in the male and female neonatal lung following injury. Our objective was to investigate sex and cell-type specific transcriptional changes that drive repair or persistent injury in the neonatal lung at single-cell resolution and delineate the alterations in the immune-endothelial cell communication networks in the developing lung using single cell RNA sequencing (sc-RNAseq) in a murine model of hyperoxic lung injury. We generated transcriptional profiles of >55,000 cells isolated from the lungs of postnatal day 1 (PND 1) andpostnatal day 21 (PND 21) neonatal male and female C57BL/6 mice exposed to 95% FiO2between PND 1-5 (saccular stage of lung development).We show the presence of sex-based differences in the transcriptional states of lung endothelial and immune cells at PND 1 and PND 21. Furthermore, we demonstrate that biological sex significantly influences the response to injury, with a greater number of differentially expressed genes showing sex-specific patterns than those shared between male and female lungs. Pseudotime trajectory analysis highlighted genes needed for lung development that were altered by hyperoxia. Finally, we show intercellular communication between endothelial and immune cells at saccular and alveolar stages of lung development with sex-based biases in the cross-talk and identify novel ligand-receptor pairs. Our findings provide valuable insights into the cell diversity, transcriptional state, developmental trajectory, and cell-cell communication underlying neonatal lung injury, with implications for understanding lung development and therapeutic interventions while highlighting the crucial role of sex as a biological variable.
Project description:Altered functions of the lung epithelial surface likely contribute to the respiratory morbidities in infants with bronchopulmonary dysplasia (BPD). Infants with BPD exhibit decreased expressions of secretoglobins (SCGBs), including Clara cell secretory protein (CCSP). Expression of lung SCGB and annexin A1 (ANXA1) is persistently altered in CCSP knockout mice suggesting that CCSP indirectly influences innate immune responses. The present studies tested the hypothesis that neonatal hyperoxic exposure induces deficits in CCSP expression that are associated with persistent alterations in lung SCGB and ANXA1 expression. Newborn C3H/HeN mice were exposed to room air (RA) or 85% O2 from birth and were sacrificed at 14?d or returned to RA for 14?d. Neonatal hyperoxia followed by RA recovery was associated with decreased lung CCSP and SCGB3A1 protein but not mRNA expression. Hyperoxia-induced alterations in the charge characteristics of ANXA1 were unchanged by RA recovery and were associated with elevated lung macrophage numbers. These findings support a model in which hyperoxia-induced alterations in Clara cell function influence lung innate immune function through effects on immunomodulatory proteins. Studies to determine the mechanism(s) by which CCSP alterations affect SCGBs, ANXA1, and innate immune responses in BPD are warranted.