Project description:To understand the molecular mechanisms of human lung macrophage development, function, and role in BPD pathogenesis, we conducted a clinical study using isolated tracheal aspirate macrophages from intubated preterm infants born before 30 wk gestation. One hundred twenty-eight patients intubated for respiratory distress syndrome and surfactant administration were consented for the study.
Project description:Sash1 acts as a scaffold in TLR4 signaling. We generated Sash1-/- mice, which die in the perinatal period due to respiratory distress. Constitutive or endothelial-restricted Sash1 loss leads to a reduction of surfactant-associated protein synthesis. We show that Sash1 interacts with β-arrestin 1 downstream of the TLR4 pathway to activate Akt and eNOS in microvascular endothelial cells. Generation of nitric oxide downstream of Sash1 in endothelial cells activated cGMP in adjacent alveolar type 2 cells to induce transcription of surfactant genes. Thus we identify a critical cell nonautonomous function for Sash1 in embryonic development in which endothelial Sash1 affects alveolar type 2 cells and promotes pulmonary surfactant production through nitric oxide signaling. Lack of pulmonary surfactant is a major cause of respiratory distress and mortality in preterm infants, and these findings identify the endothelium as a potential target for therapy.
Project description:Pulmonary surfactant (PS) produced by alveolar type II (ATII) cells is necessary in maintaining normal lung function, and a decrease or change in composition of PS is the main cause of alveolar collapse in acute respiratory distress syndrome (ARDS). But the mechanism of decrease or com-position change of PS is still unknown.
Project description:Intrahepatic cholestasis of pregnancy (ICP) is estimated to impact between 0.4% and 5% of pregnancies worldwide. This disease is associated with elevated maternal bile acids and frequently untoward neonatal outcomes such as respiratory distress and asphyxia. Multiple candidate genes have been implicated, but none have provided insight into the mechanisms of neonatal respiratory distress and death. Herein our studies demonstrate that maternal cholestasis (due to Abcb11 deficiency) produces 100% neonatal death within 24h due to atelectasis producing pulmonary hypoxia, which recapitulates the respiratory distress and asphyxia of human ICP. We show that these neonates have elevated pulmonary bile acids that are associated with disrupted structure of pulmonary surfactant. Maternal absence of Nr1i2 superimposed upon Abcb11 deficiency strongly increased neonatal survival and is directly related to reduced maternal bile acid concentrations. The mechanism accounting for reduced serum bile acids in the mothers deficient in both Nr1i2 and Abcb11 appears related to disrupted reabsorption of intestinal bile acids due to changes in transporter expression. These findings provide novel insights into pulmonary failure by revealing bile acids capability to disrupt the structure of surfactant producing collapsed alveoli, pulmonary failure and ultimately death. These findings have important implications for neonatal health especially when maternal bile acids are elevated during pregnancy and highlight a potential pathway and targets amenable to therapeutic intervention to ameliorate this condition.
Project description:Intrahepatic cholestasis of pregnancy (ICP) is estimated to impact between 0.4% and 5% of pregnancies worldwide. This disease is associated with elevated maternal bile acids and frequently untoward neonatal outcomes such as respiratory distress and asphyxia. Multiple candidate genes have been implicated, but none have provided insight into the mechanisms of neonatal respiratory distress and death. Herein our studies demonstrate that maternal cholestasis (due to Abcb11 deficiency) produces 100% neonatal death within 24h due to atelectasis producing pulmonary hypoxia, which recapitulates the respiratory distress and asphyxia of human ICP. We show that these neonates have elevated pulmonary bile acids that are associated with disrupted structure of pulmonary surfactant. Maternal absence of Nr1i2 superimposed upon Abcb11 deficiency strongly increased neonatal survival and is directly related to reduced maternal bile acid concentrations. The mechanism accounting for reduced serum bile acids in the mothers deficient in both Nr1i2 and Abcb11 appears related to disrupted reabsorption of intestinal bile acids due to changes in transporter expression. These findings provide novel insights into pulmonary failure by revealing bile acids capability to disrupt the structure of surfactant producing collapsed alveoli, pulmonary failure and ultimately death. These findings have important implications for neonatal health especially when maternal bile acids are elevated during pregnancy and highlight a potential pathway and targets amenable to therapeutic intervention to ameliorate this condition. We used microarrays to measure changes in gene expression profiles in lung tissues from Abcb11+/- lungs after interbreeding C57BL/6 wild-type female or C57BL/6 Abcb11-/- female mice against either C57BL/6 wild-type male mice or C57BL/6 Abcb11-/- male mice to create only heterozygote offspring. We also measured profiles in liver tissues from age-matched C57BL/6 wild-type and C57BL/6 Abcb11-/- mice. Lung tissues were collected from day E17.5, E18.5 and neonatal (N0) mice. Liver tissues were collected from 1.5-month-old C57BL/6 wildtype and Abcb11-/- mice.
Project description:Acute Respiratory Distress Syndrome (ARDS) is a common cause of respiratory failure yet has few pharmacologic therapies, reflecting the mechanistic heterogeneity of lung injury. We hypothesized that damage to the alveolar epithelial glycocalyx, a layer of glycosaminoglycans interposed between the epithelium and surfactant, contributes to lung injury in ARDS patients. Using mass spectrometry of airspace fluid noninvasively collected from mechanically-ventilated patients, we found that airspace glycosaminoglycan shedding (an index of glycocalyx degradation) occurred predominantly in patients with direct lung injury and was associated with duration of mechanical ventilation. Male patients had increased shedding which correlated with airspace concentrations of matrix metalloproteinases. Selective epithelial glycocalyx degradation in mice was sufficient to induce surfactant dysfunction, a key characteristic of ARDS, leading to microatelectasis and decreased lung compliance. Rapid colorimetric quantification of airspace glycosaminoglycans was feasible and could provide point-of-care prognostic information to clinicians and/or be used for predictive enrichment in clinical trials.
Project description:Low serum levels or deficiency of 1α,25-dihydroxyvitamin D3 (VD3) are associated with a higher mortality in trauma patients with sepsis or acute respiratory distress syndrome, although the molecular mechanisms behind this observation are not yet understood. VD3 is known to stimulate lung maturity, alveolar type II cell differentiation and pulmonary surfactant synthesis. This study aims to expand the knowledge by quantitative characterization of NCI-H441 cells upon VD3 treatment at the proteome level.
Project description:In this study, We proposed a reprogramming-derived bovine model of NRDS based on typical phenotypes of neonatal respiratory distress syndrome (NRDS) and high reproducibility and replication rates as well as a steerable background of neonatal cloned cows suffering from NRDS. With the aid of miRNA sequencing, construction of the miRNA–gene network and functional enrichment of target genes, the effects of specific miRNAs on lung development and surfactant homeostasis were determined in this model. We identified 12 miRNAs targeting SFTPB, SFTPC and NKX2-1 genes, demonstrated repression effects of three miRNAs on NKX2-1 and SFTPC expression in vivo and through which miRNAs disturbed lung development and surfactant homeostasis in the NRDS bovine model.
Project description:Bronchopulmonary dysplasia (BPD) is a multifactorial chronic lung disease of premature neonates. The development of BPD depends on several prenatal and postnatal factors that induce inflammation, altering alveolar growth and pulmonary vascular development. Animal models are essential to investigating the precise molecular pathways leading to BPD. The preterm rabbit combines many advantages of both small (e.g., rodents) and large BPD models (i.e., preterm lambs and baboons). For instance, preterm rabbits display mild-to-moderate respiratory distress at delivery, which, along with ongoing exposure to high oxygen concentration (95% O2), leads to functional and morphological lung changes that resemble the phenotype of human BPD. Nevertheless, the molecular pathways leading to the development of the BPD-like phenotype in this model remain largely ununderstood. We, therefore, aimed to characterize the longitudinal gene expression in the lungs of preterm rabbits continuously exposed to 95% O2 on postnatal days 3, 5, and 7. The longitudinal transcriptomic analysis revealed different expression patterns for several genes and pathways. Over time, extracellular matrix organization and angiogenesis were increasingly downregulated, while apoptosis, RNA processing, and inflammation showed the opposite trend.