Nuclear factor-κB (NF-κB) inhibitory protein IκBβ determines apoptotic cell death following exposure to oxidative stress.

The transcription factor NF-κB regulates the cellular response to inflammatory and oxidant stress. Although many studies have evaluated NF-κB activity following exposure to oxidative stress, the role of the IκB family of inhibitory proteins in modulating this activity remains unclear. Specifically, the function of IκBβ in mediating the cellular response to oxidative stress has not been evaluated.

Molecular identification of bacteria in tracheal aspirate fluid from mechanically ventilated preterm infants.

Background: Despite strong evidence linking infections to the pathogenesis of bronchopulmonary dysplasia (BPD), limitations of bacterial culture methods have precluded systematic studies of airway organisms relative to disease outcomes. Application of molecular bacterial identification strategies may provide new insight into the role of bacterial acquisition in the airways of preterm infants at risk for BPD.

Methods: Serial (within 72 hours, 7, 14, and 21 days of life) tracheal aspirate samples were collected from 10 preterm infants with gestational age ≤34 weeks at birth, and birth weight of 500-1250 g who required mechanical ventilation for at least 21 days.

Excess soluble vascular endothelial growth factor receptor-1 in amniotic fluid impairs lung growth in rats: linking preeclampsia with bronchopulmonary dysplasia.

Epidemiological studies have shown that maternal preeclampsia (PE) increases the risk of bronchopulmonary dysplasia (BPD), but the underlying mechanism is unknown. Soluble vascular endothelial growth factor receptor-1 (soluble VEGFR1, known as soluble fms-like tyrosine kinase 1, or sFlt-1), an endogenous antagonist of vascular endothelial growth factor (VEGF), is markedly elevated in amniotic fluid and maternal blood in PE. Therefore, we hypothesized that antenatal exposure to excess sFlt-1 disrupts lung development through impaired VEGF signaling in utero, providing a mechanistic link between PE and BPD.

Circulating myeloid-derived suppressor cells are increased and activated in pulmonary hypertension.

Background: Myeloid-derived suppressor cells (MDSCs) are increased in inflammatory and autoimmune disorders and orchestrate immune cell responses therein. Pulmonary hypertension (PH) is associated with inflammation, autoimmunity, and lung vascular remodeling. Immature myeloid cells are found in the lungs of humans and animals with PH, and we hypothesized that they would be increased in the blood of patients with PH compared with control subjects.

Pulmonary vascular effects of serotonin and selective serotonin reuptake inhibitors in the late-gestation ovine fetus.

Maternal use of selective serotonin (5-HT) reuptake inhibitors (SSRIs) is associated with an increased risk for persistent pulmonary hypertension of the newborn (PPHN), but little is known about 5-HT signaling in the developing lung. We hypothesize that 5-HT plays a key role in maintaining high pulmonary vascular resistance (PVR) in the fetus and that fetal exposure to SSRIs increases 5-HT activity and causes pulmonary hypertension. We studied the hemodynamic effects of 5-HT, 5-HT receptor antagonists, and SSRIs in chronically prepared fetal sheep.

Intrauterine growth restriction decreases pulmonary alveolar and vessel growth and causes pulmonary artery endothelial cell dysfunction in vitro in fetal sheep.

Intrauterine growth restriction (IUGR) increases the risk for bronchopulmonary dysplasia (BPD). Abnormal lung structure has been noted in animal models of IUGR, but whether IUGR adversely impacts fetal pulmonary vascular development and pulmonary artery endothelial cell (PAEC) function is unknown. We hypothesized that IUGR would decrease fetal pulmonary alveolarization, vascular growth, and in vitro PAEC function.

Cinaciguat, a soluble guanylate cyclase activator, augments cGMP after oxidative stress and causes pulmonary vasodilation in neonatal pulmonary hypertension.

Although inhaled NO (iNO) therapy is often effective in treating infants with persistent pulmonary hypertension of the newborn (PPHN), up to 40% of patients fail to respond, which may be partly due to abnormal expression and function of soluble guanylate cyclase (sGC). To determine whether altered sGC expression or activity due to oxidized sGC contributes to high pulmonary vascular resistance (PVR) and poor NO responsiveness, we studied the effects of cinaciguat (BAY 58-2667), an sGC activator, on pulmonary artery smooth muscle cells (PASMC) from normal fetal sheep and sheep exposed to chronic intrauterine pulmonary hypertension (i.e.

Recent progress in understanding pediatric pulmonary hypertension.

Purpose Of Review: Pulmonary artery hypertension (PAH) in children contributes significantly to morbidity and mortality in diverse pediatric cardiac, lung, hematologic and other diseases. Advances in pulmonary vascular biology over the past few decades have significantly expanded therapeutic strategies; however, many unique issues persist regarding our understanding of pediatric PAH.

Recent Findings: Recent studies of pediatric PAH include those that highlight gaps in our understanding of pediatric diseases associated with PAH from those of adult onset, emphasizing the strong need for specific studies regarding unique aspects of the pathogenesis and treatment of children with PAH.

Pathogenesis and treatment of bronchopulmonary dysplasia.

Purpose Of Review: Bronchopulmonary dysplasia (BPD) is a chronic lung disease of infancy affecting mostly premature infants with significant morbidity and mortality. Improved survival of very immature infants has led to increased numbers of infants with this disorder. Acute and chronic lung injury and impaired postnatal lung growth are thought to be responsible for the development of BPD.

Pulmonary hypertension in children: a historical overview.

Pulmonary arterial hypertension in children contributes significantly to morbidity and mortality in diverse pediatric cardiac, lung, hematologic, and other diseases. Pulmonary arterial hypertension is generally a disease of small pulmonary arteries characterized by vascular narrowing due to high-tone and abnormal vasoreactivity, structural remodeling of the vessel wall, intraluminal obstruction, and decreased vascular growth and surface area. Without therapy, high pulmonary vascular resistance contributes to progressive right ventricular failure, low cardiac output, and death.

Impaired vascular endothelial growth factor signaling in the pathogenesis of neonatal pulmonary vascular disease.

Abstract Of diverse growth factors that contribute to normal lung development, vascular endothelial growth factor (VEGF) plays an especially prominent role in the normal growth and development of the pulmonary circulation in the fetus and newborn. Strong experimental and clinical data support the role of impaired VEGF signaling in the pathogenesis of two major clinical disorders of the developing lung circulation: persistent pulmonary hypertension of the newborn (PPHN) and bronchopulmonary dysplasia (BPD). These disorders are each characterized by impaired vascular growth, structure and reactivity, which are at least partly due to endothelial cell dysfunction.

Bone marrow-derived angiogenic cells restore lung alveolar and vascular structure after neonatal hyperoxia in infant mice.

Neonatal hyperoxia impairs vascular and alveolar growth in mice and decreases endothelial progenitor cells. To determine the role of bone marrow-derived cells in restoration of neonatal lung structure after injury, we studied a novel bone marrow myeloid progenitor cell population from Tie2-green fluorescent protein (GFP) transgenic mice (bone marrow-derived angiogenic cells; BMDAC). We hypothesized that treatment with BMDAC would restore normal lung structure in infant mice during recovery from neonatal hyperoxia.

Towards improving the care of children with pulmonary hypertension: The rationale for developing a Pediatric Pulmonary Hypertension Network.

Pulmonary hypertension (PH) and related pulmonary vascular diseases contribute to high morbidity and mortality and treatment options remain limited. Despite the availability of new drug therapies, the long-term outcomes of patients with severe PH remain poor. This may be especially true for many children with PH.

Inhaled nitric oxide improves lung structure and pulmonary hypertension in a model of bleomycin-induced bronchopulmonary dysplasia in neonatal rats.

Whether inhaled nitric oxide (iNO) prevents the development of bronchopulmonary dysplasia (BPD) in premature infants is controversial. In adult rats, bleomycin (Bleo) induces lung fibrosis and pulmonary hypertension, but the effects of Bleo on the developing lung and iNO treatment on Bleo-induced neonatal lung injury are uncertain. Therefore, we sought to determine whether early and prolonged iNO therapy attenuates changes of pulmonary vascular and alveolar structure in a model of BPD induced by Bleo treatment of neonatal rats.

Hyperoxia disrupts vascular endothelial growth factor-nitric oxide signaling and decreases growth of endothelial colony-forming cells from preterm infants.

Exposure of preterm infants to hyperoxia impairs vascular growth, contributing to the development of bronchopulmonary dysplasia and retinopathy of prematurity. Disruption of vascular endothelial growth factor (VEGF)-nitric oxide (NO) signaling impairs vascular growth. Endothelial progenitor cells (EPCs) may play an important role in vascular growth.

Development and pathology of pulmonary hypertension.

The Development and Pathology working group was charged with reviewing the present knowledge, gaps in understanding, and areas for further studies in a broad range of themes. These themes in pulmonary vascular biology and pathobiology involved: 1) pulmonary vascular development; 2) pulmonary vascular disease accompanying fetal development and perinatal life; 3) properties of pulmonary vascular endothelial cells; 4) role of bone marrow cells in pulmonary vascular disease; 5) insights into pulmonary thromboembolic disease; 6) role of pathology in the assessment of pulmonary vascular disease; and 7) considerations of tissue banking for research in pulmonary hypertension. These important goals provide a blueprint for future research that may significantly impact our present and future understanding of pulmonary hypertension.

Cinaciguat, a soluble guanylate cyclase activator, causes potent and sustained pulmonary vasodilation in the ovine fetus.

Impaired nitric oxide-cGMP signaling contributes to severe pulmonary hypertension after birth, which may in part be due to decreased soluble guanylate cyclase (sGC) activity. Cinaciguat (BAY 58-2667) is a novel sGC activator that causes vasodilation, even in the presence of oxidized heme or heme-free sGC, but its hemodynamic effects have not been studied in the perinatal lung. We performed surgery on eight fetal (126 +/- 2 days gestation) lambs (full term = 147 days) and placed catheters in the main pulmonary artery, aorta, and left atrium to measure pressures.

Role of endothelin receptor antagonists in the treatment of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a severe disease with marked morbidity and mortality for which therapeutic strategies have been limited. Basic research in vascular biology has implicated endothelin-1 (ET-1) and its receptors (ET(A) and ET(B)) in diverse preclinical models of PAH, and ET-1 has been shown to contribute significantly to PAH in human patients. Despite the complexity of roles of the ET receptors in the development or reversal of PAH in the laboratory, the introduction of endothelin receptor antagonists (ETRAs) to clinical medicine has substantially expanded our therapeutic approach toward severe PAH.

Fasudil inhibits the myogenic response in the fetal pulmonary circulation.

In addition to high pulmonary vascular resistance (PVR) and low pulmonary blood flow, the fetal pulmonary circulation is characterized by mechanisms that oppose vasodilation. Past work suggests that high myogenic tone contributes to high PVR and may contribute to autoregulation of blood flow in the fetal lung. Rho-kinase (ROCK) can mediate the myogenic response in the adult systemic circulation, but whether high ROCK activity contributes to the myogenic response and modulates time-dependent vasodilation in the developing lung circulation are unknown.

Left ventricular diastolic dysfunction in bronchopulmonary dysplasia.

We report 2 infants with severe bronchopulmonary dysplasia in whom left ventricular diastolic dysfunction contributed to clinical abnormalities, including pulmonary hypertension and recurrent pulmonary edema. We speculate that close monitoring for left ventricular diastolic dysfunction may assist with clinical management and improve outcomes of infants with severe bronchopulmonary dysplasia.

Short- and long-term effects of inhaled iloprost therapy in children with pulmonary arterial hypertension.

Objectives: This study investigated the short- and long-term outcome of children with pulmonary arterial hypertension (PAH) treated with inhaled iloprost.

Background: Inhaled iloprost has been approved for the treatment of adults with PAH, but little is known about the effects in children with PAH.

Methods: We evaluated the acute effects of inhaled iloprost on hemodynamic status and lung function and the response to long-term therapy in 22 children (range 4.

Impaired VEGF and nitric oxide signaling after nitrofen exposure in rat fetal lung explants.

We hypothesized that abnormal fetal lung growth in experimental congenital diaphragmatic hernia after maternal nitrofen exposure alters lung structure due to impaired VEGF signaling, which can be reversed with VEGF or nitric oxide (NO) treatment. Timed-pregnant Sprague-Dawley rats were treated with nitrofen on embryonic day 9 (E9), and fetal lungs were harvested for explant culture on E15. Explants were maintained in 3% O2 for 3 days and were treated with NO gas or recombinant human VEGF protein for 3 days.

Early inhaled nitric oxide treatment decreases apoptosis of endothelial cells in neonatal rat lungs after vascular endothelial growth factor inhibition.

Vascular endothelial growth factor (VEGF) receptor blockade impairs lung growth and decreases nitric oxide (NO) production in neonatal rat lungs. Inhaled NO (iNO) treatment after VEGF inhibition preserves lung growth in infant rats by unknown mechanisms. We hypothesized that neonatal VEGF inhibition disrupts lung growth by causing apoptosis in endothelial cells, which is attenuated by early iNO treatment.