Dynamic behavior and lineage plasticity of the pulmonary venous endothelium.

Repair of the pulmonary vascular bed and the origin of new vasculature remain underexplored despite the critical necessity to meet oxygen demands after injury. Given their critical role in angiogenesis in other settings, we investigated the role of venous endothelial cells in endothelial regeneration after adult lung injury. Here we identified Slc6a2 as a marker of pulmonary venous endothelial cells and generated a venous-specific, inducible Cre mouse line.

Bronchopulmonary Dysplasia with Pulmonary Hypertension Associates with Loss of Semaphorin Signaling and Functional Decrease in FOXF1 Expression.

Lung injury in preterm infants leads to structural and functional respiratory deficits, with a risk for bronchopulmonary dysplasia (BPD) that in its most severe form is accompanied by pulmonary hypertension (PH). To examine cellular and molecular dynamics driving evolving BPD in humans, we performed single-cell RNA sequencing of preterm infant lungs in early stages of BPD and BPD+PH compared to term infants. Analysis of the endothelium revealed a unique aberrant capillary cell-state primarily in BPD+PH marked by expression.

The emerging role of extracellular vesicles in bronchopulmonary dysplasia.

Extracellular vesicle (EV) biology in neonatal lung development and disease is a rapidly growing area of investigation. Although EV research in the neonatal population lags behind EV research in adult lung diseases, recent discoveries demonstrate promise in furthering our understanding of the pathophysiology of bronchopulmonary dysplasia and the potential use of EVs in the clinical setting, as both biomarkers and therapeutic agents. This review article explores some of the recent advances in this field and our evolving knowledge of the role of EVs in bronchopulmonary dysplasia.

A novel role for PGE-EP in the developmental programming of the mouse ductus arteriosus: consequences for vessel maturation and function.

The ductus arteriosus (DA) is a vascular shunt that allows oxygenated blood to bypass the developing lungs in utero. Fetal DA patency requires vasodilatory signaling via the prostaglandin E (PGE) receptor EP. However, in humans and mice, disrupted PGE-EP signaling in utero causes unexpected patency of the DA (PDA) after birth, suggesting another role for EP during development.

Developmental trajectory of extracellular vesicle characteristics from the lungs of preterm infants.

Extracellular vesicles (EVs) are secreted lipid-enclosed particles that have emerged as potential biomarkers and therapeutic agents in lung disease, including bronchopulmonary dysplasia (BPD), a leading complication of preterm birth. Many unanswered questions remain about the content and cargo of EVs in premature infants and their role in lung development. To characterize EVs during human lung development, tracheal aspirates were collected from premature neonates between 22 and 35 wk gestational age and analyzed via nanoparticle tracking analysis, electron microscopy, and bead-based flow cytometry.

CXCL12 defines lung endothelial heterogeneity and promotes distal vascular growth.

There is a growing amount of data uncovering the cellular diversity of the pulmonary circulation and mechanisms governing vascular repair after injury. However, the molecular and cellular mechanisms contributing to the morphogenesis and growth of the pulmonary vasculature during embryonic development are less clear. Importantly, deficits in vascular development lead to significant pediatric lung diseases, indicating a need to uncover fetal programs promoting vascular growth.

Mildred T. Stahlman: a centenarian who pioneered modern scientific neonatal intensive care.

Neonatology pioneer Mildred (Millie) T. Stahlman celebrated her 100th birthday on July 31, 2022. Her distinguished career at Vanderbilt University Medical Center in Nashville, TN, is reviewed to commemorate this milestone.

Racing against time: leveraging preclinical models to understand pulmonary susceptibility to perinatal acetaminophen exposures.

Over the past decade, clinicians have increasingly prescribed acetaminophen (APAP) for patients in the neonatal intensive care unit (NICU). Acetaminophen has been shown to reduce postoperative opiate burden, and may provide similar efficacy for closure of the patent ductus arteriosus (PDA) as nonsteroidal anti-inflammatory drugs (NSAIDs). Despite these potential benefits, APAP exposures have spread to increasingly less mature infants, a highly vulnerable population for whom robust pharmacokinetic and pharmacodynamic data for APAP are lacking.

Bronchopulmonary dysplasia is associated with polyhydramnios in a scan for novel perinatal risk factors.

Background: The pathogenesis of bronchopulmonary dysplasia (BPD) is multifactorial, and there are limited data about prenatal exposures and risk of BPD.

Study Design: Our study performed parallel analyses using a logistic regression model in a cohort of 4527 infants with data from a curated registry and using a phenome wide association study (PheWAS) based on ICD9/10-based phecodes. We examined 20 prenatal exposures from a neonatal intensive care unit (NICU) curated registry database related to pregnancy and maternal health as well as 94 maternal diagnosis phecodes with a PheWAS analysis.

A single-cell atlas of mouse lung development.

Lung organogenesis requires precise timing and coordination to effect spatial organization and function of the parenchymal cells. To provide a systematic broad-based view of the mechanisms governing the dynamic alterations in parenchymal cells over crucial periods of development, we performed a single-cell RNA-sequencing time-series yielding 102,571 epithelial, endothelial and mesenchymal cells across nine time points from embryonic day 12 to postnatal day 14 in mice. Combining computational fate-likelihood prediction with RNA in situ hybridization and immunofluorescence, we explore lineage relationships during the saccular to alveolar stage transition.

AP-3-dependent targeting of flippase ATP8A1 to lamellar bodies suppresses activation of YAP in alveolar epithelial type 2 cells.

Lamellar bodies (LBs) are lysosome-related organelles (LROs) of surfactant-producing alveolar type 2 (AT2) cells of the distal lung epithelium. Trafficking pathways to LBs have been understudied but are likely critical to AT2 cell homeostasis given associations between genetic defects of endosome to LRO trafficking and pulmonary fibrosis in Hermansky Pudlak syndrome (HPS). Our prior studies uncovered a role for AP-3, defective in HPS type 2, in trafficking Peroxiredoxin-6 to LBs.

Single-cell RNA sequencing reveals profibrotic roles of distinct epithelial and mesenchymal lineages in pulmonary fibrosis.

Pulmonary fibrosis (PF) is a form of chronic lung disease characterized by pathologic epithelial remodeling and accumulation of extracellular matrix (ECM). To comprehensively define the cell types, mechanisms, and mediators driving fibrotic remodeling in lungs with PF, we performed single-cell RNA sequencing of single-cell suspensions from 10 nonfibrotic control and 20 PF lungs. Analysis of 114,396 cells identified 31 distinct cell subsets/states.

Distinct Spatiotemporally Dynamic Wnt-Secreting Niches Regulate Proximal Airway Regeneration and Aging.

Our understanding of dynamic interactions between airway basal stem cells (ABSCs) and their signaling niches in homeostasis, injury, and aging remains elusive. Using transgenic mice and pharmacologic studies, we found that Wnt/β-catenin within ABSCs was essential for proliferation post-injury in vivo. ABSC-derived Wnt ligand production was dispensable for epithelial proliferation.

Age-determined expression of priming protease TMPRSS2 and localization of SARS-CoV-2 infection in the lung epithelium.

The SARS-CoV-2 novel coronavirus global pandemic (COVID-19) has led to millions of cases and hundreds of thousands of deaths around the globe. While the elderly appear at high risk for severe disease, hospitalizations and deaths due to SARS-CoV-2 among children have been relatively rare. Integrating single-cell RNA sequencing (scRNA-seq) of the developing mouse lung with temporally-resolved RNA-in-situ hybridization (ISH) in mouse and human lung tissue, we found that expression of SARS-CoV-2 Spike protein primer was highest in ciliated cells and type I alveolar epithelial cells (AT1), and expression was increased with aging in mice and humans.

SARS-CoV-2 Receptor ACE2 Is an Interferon-Stimulated Gene in Human Airway Epithelial Cells and Is Detected in Specific Cell Subsets across Tissues.

There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), which causes the disease COVID-19. SARS-CoV-2 spike (S) protein binds angiotensin-converting enzyme 2 (ACE2), and in concert with host proteases, principally transmembrane serine protease 2 (TMPRSS2), promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues and the factors that regulate ACE2 expression remain unknown.

Hyperoxia Injury in the Developing Lung Is Mediated by Mesenchymal Expression of Wnt5A.

Bronchopulmonary dysplasia (BPD) is a leading complication of preterm birth that affects infants born in the saccular stage of lung development at <32 weeks of gestation. Although the mechanisms driving BPD remain uncertain, exposure to hyperoxia is thought to contribute to disease pathogenesis. To determine the effects of hyperoxia on epithelial-mesenchymal interactions and to define the mediators of activated Wnt/β-catenin signaling after hyperoxia injury.

Successful Establishment of Primary Type II Alveolar Epithelium with 3D Organotypic Coculture.

Alveolar type II (AT2) epithelial cells are uniquely specialized to produce surfactant in the lung and act as progenitor cells in the process of repair after lung injury. AT2 cell injury has been implicated in several lung diseases, including idiopathic pulmonary fibrosis and bronchopulmonary dysplasia. The inability to maintain primary AT2 cells in culture has been a significant barrier in the investigation of pulmonary biology.

A Shared Pattern of β-Catenin Activation in Bronchopulmonary Dysplasia and Idiopathic Pulmonary Fibrosis.

Wnt/β-catenin signaling is necessary for normal lung development, and abnormal Wnt signaling contributes to the pathogenesis of both bronchopulmonary dysplasia (BPD) and idiopathic pulmonary fibrosis (IPF), fibrotic lung diseases that occur during infancy and aging, respectively. Using a library of human normal and diseased human lung samples, we identified a distinct signature of nuclear accumulation of β-catenin phosphorylated at tyrosine 489 and epithelial cell cytosolic localization of β-catenin phosphorylated at tyrosine 654 in early normal lung development and fibrotic lung diseases BPD and IPF. Furthermore, this signature was recapitulated in murine models of BPD and IPF.

Development of a Three-Dimensional Bioengineering Technology to Generate Lung Tissue for Personalized Disease Modeling.

Stem cell technologies, especially patient-specific, induced stem cell pluripotency and directed differentiation, hold great promise for changing the landscape of medical therapies. Proper exploitation of these methods may lead to personalized organ transplants, but to regenerate organs, it is necessary to develop methods for assembling differentiated cells into functional, organ-level tissues. The generation of three-dimensional human tissue models also holds potential for medical advances in disease modeling, as full organ functionality may not be necessary to recapitulate disease pathophysiology.

Posttranslational modification of β-catenin is associated with pathogenic fibroblastic changes in bronchopulmonary dysplasia.

Bronchopulmonary dysplasia (BPD) is a common complication of premature birth. The histopathology of BPD is characterized by an arrest of alveolarization with fibroblast activation. The Wnt/β-catenin signaling pathway is important in early lung development.

A three-dimensional human model of the fibroblast activation that accompanies bronchopulmonary dysplasia identifies Notch-mediated pathophysiology.

Bronchopulmonary dysplasia (BPD) is a leading complication of premature birth and occurs primarily in infants delivered during the saccular stage of lung development. Histopathology shows decreased alveolarization and a pattern of fibroblast proliferation and differentiation to the myofibroblast phenotype. Little is known about the molecular pathways and cellular mechanisms that define BPD pathophysiology and progression.