Impaired Lung Development Research Articles

Adverse early-life environment impairs postnatal lung development in mice.

Fetal growth restriction (FGR) is a major risk factor for bronchopulmonary dysplasia (BPD). Maternal stress and poor diet are linked to FGR. Effect of perinatal stress on lung development remains unknown. Using a murine model of adverse early life environment (AELE), we hypothesized that maternal exposure to perinatal environmental stress and high-fat diet (Western diet) lead to impaired lung development in the offspring. Female mice were placed on either control diet or Western diet before conception. Those exposed to Western diet were also exposed to perinatal environmental stress, the combination referred to as AELE. Pups were either euthanized at postnatal day 21 (P21) or weaned to control diet and environment until adulthood (8-14 wk old). Lungs were harvested for histology, gene expression by quantitative RT-PCR, microRNA profiling, and immunoblotting. AELE increased the mean linear intercept and decreased the radial alveolar count and secondary septation in P21 and adult mice. Capillary count was also decreased in P21 and adult mice. AELE lungs had decreased vascular endothelial growth factor A (VEGFA), VEGF receptor 2, endothelial nitric oxide synthase, and hypoxia inducible factor-1α protein levels and increased expression of genes that regulate DNA methylation and upregulation of microRNAs that target genes involved in lung development at P21. AELE leads to impaired lung alveolar and vascular growth, which persists into adult age despite normalizing the diet and environment at P21. AELE also alters the expression of genes involved in lung remodeling.

Effect of intermittent hypoxia or hyperoxia on lung development in preterm rat neonates during constant oxygen therapy.

Impaired lung development is a major negative factor in the survival of preterm neonates. The present study was aimed to investigate the impact of constant oxygen, intermittent hyperoxia, and hypoxia on the lung development in preterm rat neonates. Neonatal rats were exposed to 40% O2 with or without brief hyperoxia episodes (95% O2 ) or brief hypoxia episodes (10% O2 ) from day 0 to day 14, or to room air. The body weight, radical alveolar count (RAC), and total antioxidant capacity (TAOC) were significantly lower whereas the lung coefficient and malondialdehyde (MDA) were significantly higher in the hyperoxia and hypoxia groups than the air control and constant oxygen group at day 7, day 14, and day 21 after birth. The lung function indexes were reduced by intermittent hyperoxia and hypoxia. In contrast, the constant oxygen therapy increased the lung function. HIF-1α and VEGF expression were significantly increased by hypoxia and decreased by hyperoxia. The constant oxygen therapy only decreased the HIF-1α expression at day 14 and 21. In summary, the constant oxygen treatment promoted lung function without affecting the antioxidative capacity in preterm rat neonates. While intermittent hyperoxia and hypoxia inhibited lung development, decreased antioxidative capacity, and dysregulated HIF-1α/VEGF signaling in preterm rat neonates.

Sex-differences in LPS-induced neonatal lung injury

Being of the male sex has been identified as a risk factor for multiple morbidities associated with preterm birth, including bronchopulmonary dysplasia (BPD). Exposure to inflammatory stress is a well-recognized risk factor for developing BPD. Whether there is a sex difference in pulmonary innate immune TLR4 signaling, lung injury and subsequent abnormal lung development is unknown. Neonatal (P0) male and female mice (ICR) were exposed to systemic LPS (5 mg/kg, IP) and innate immune signaling, and the transcriptional response were assessed (1 and 5 hours), along with lung development (P7). Male and female mice demonstrated a similar degree of impaired lung development with decreased radial alveolar counts, increased surface area, increased airspace area and increased mean linear intercept. We found no differences between male and female mice in the baseline pulmonary expression of key components of TLR4-NFκB signaling, or in the LPS-induced pulmonary expression of key mediators of neonatal lung injury. Finally, we found no difference in the kinetics of LPS-induced pulmonary NFκB activation between male and female mice. Together, these data support the conclusion that the innate immune response to early postnatal LPS exposure and resulting pulmonary sequelae is similar in male and female mice.

Bronchopulmonary dysplasia-associated pulmonary hypertension

Chronic respiratory sequelae are a major health problem in surviving premature infants. Despite immense improvement in the care of premature infants, the rate of bronchopulmonary dysplasia (BPD) and pulmonary morbidities have remained the same or even slightly increased over the past decades. BPD results from the impairment of lung development following premature birth, and the resultant dysregulated pulmonary vasculature leads to chronic pulmonary hypertension (PH). It is seen more commonly in the setting of moderate to severe BPD. A high index of suspicion is necessary to diagnose PH in BPD. Diagnosis is most commonly done by echocardiogram, but cardiac catheterization may be required to delineate the cardiac structure, cardio-pulmonary vasculature and myocardial function. Once the diagnosis is made, a multidisciplinary approach for management of these patients is suggested, aiming to optimize management of BPD and use of various pulmonary vasodilators. The various therapeutic agents available help reduce pulmonary vascular resistance by acting on the nitric oxide (NO), prostacyclin and/or endothelin pathways. Serial echocardiograms and measurement of biomarkers are used to evaluate the response to therapy. Currently there is not much evidence to support optimal management approaches, but the recent guidelines published by the Pediatric Pulmonary Hypertension Network (PPHNet) provide practical recommendations for screening and management of these infants.

Genetic Strain and Sex Differences in a Hyperoxia-Induced Mouse Model of Varying Severity of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a disease prevalent in preterm babies with a need for supplemental oxygen, resulting in impaired lung development and dysregulated vascularization. Epidemiologic studies have shown that males are more prone to BPD and have a delayed recovery compared with females, for reasons unknown. Herein, we tried to recapitulate mild, moderate, and severe BPD, using two different strains of mice, in males and females: CD1 (outbred) and C57BL/6 (inbred). Aside from higher body weight in the CD1 strain, there were no other gross morphologic differences with respect to alveolar development between the two strains. With respect to lung morphology after oxygen exposure, females had less injury with better preservation of alveolar chord length and decreased alveolar protein leak and inflammatory cells in the bronchoalveolar lavage fluid. In addition, housekeeping genes, which are routinely used as loading controls, were expressed differently in males and females. In the BPD mouse model, gonadotropin-releasing hormone was increased in females compared with males. Specific miRNAs (miR-146 and miR-34a) were expressed differently in the sexes. In the severe BPD mouse model, administering miR-146 mimic to males attenuated lung damage, whereas administering miR-146 inhibitor to females increased pulmonary injury.

An injectable, degradable hydrogel plug for tracheal occlusion in congenital diaphragmatic hernia (CDH)

Congenital Diaphragmatic Hernia (CDH) is a birth defect characterized by failed closure of diaphragm, herniation of viscera in the thoracic cavity and impaired lung development. In most severe cases, fetoscopic endoluminal tracheal occlusion (FETO) is performed through a catheter-mounted balloon to contain pulmonary hypoplasia. To support the success rate of FETO and overcome some of the associated drawbacks, this work aimed at finding an injectable, degradable substitute for the balloon not requiring prenatal removal.Two different types of gels were evaluated as tracheal plugs: calcium-alginate and hyaluronan/methylcellulose blends (HA-MC). The effect of composition on hydrogel properties was evaluated, to identify formulations meeting design requirements. Anatomical tracheal casts were fabricated and filled with a simulated lung fluid to assess injectability, cohesiveness, sealing pressure and persistence of plugs. In vitro cytotoxicity and adhesion of mouse fibroblasts on hydrogels were also investigated.For both hydrogels, adjusting formulation enabled to obtain gelation time within the design range. Furthermore, when injected in the tracheal model, good cohesion and capability to adapt to the anatomical shape were also observed. Effective sealing up to 80 cm H20 was reached for selected compositions and was maintained for over 4 weeks in the in vitro model. Swelling and weight loss were also strongly influenced by composition and varied from few days to several weeks. Despite the absence of in vitro cytotoxicity, a favourably low cell-adhesion was observed for both hydrogels. However, due to their shear-thinning behaviour, HA-MC blends appeared as a particularly suitable candidate for single-surgery tracheal occlusion.

Bronchopulmonary dysplasia: what are its links to COPD?

Emerging evidence suggests that adverse early life events can affect long-term health trajectories throughout life. Preterm birth, in particular, is a significant early life event that affects approximately 10% of live births. Worldwide, prematurity is the number one cause of death in children less than 5 years of age and has been shown to disrupt normal lung development with lasting effects into adult life. Along with impaired lung development, interventions used to support gas exchange and other sequelae of prematurity can lead to the development of bronchopulmonary dysplasia (BPD). BPD is a chronic respiratory disease of infancy characterized by alveolar simplification, small airways disease, and pulmonary vascular changes. Although many survivors of BPD improve with age, survivors of BPD often have chronic lung disease characterized by airflow obstruction and intermittent pulmonary exacerbations. Long-term lung function trajectories as measured by FEV1 can be lower in children and adults with a history BPD. In this review, we discuss the epidemiology and manifestations of BPD and its long-term consequences throughout childhood and into adulthood. Available evidence suggests that disrupted lung development, genetic susceptibility and subsequent environment and infectious events that occur in prenatal and postnatal life likely increase the predisposition of children with BPD to develop early onset chronic obstructive pulmonary disease (COPD). The reviews of this paper are available via the supplemental material section.

Effect of Vitamin D supplementation during pregnancy on maternal and perinatal outcomes.

Vitamin D deficiency is common globally with a higher prevalence in women, especially during pregnancy. Among the pregnant women, Vitamin D deficiency was reported up to 80% in the Asian group. Vitamin D deficiency was related to a higher risk of maternal complications including preeclampsia, impaired glucose tolerance, and cesarean section rate, and neonatal complications including low birthweight, neonatal hypocalcemia seizure, and impaired skeletal, lung and immune development. There were no data supporting Vitamin D deficiency screening routinely in pregnancy regarding cost-effectiveness or health benefits. The measurement of Vitamin D in the high-risk group of women is necessary. Subsequent supplement with Vitamin D with and without calcium supplement during pregnancy had been statistically significantly reported to decrease the risk of preeclampsia, preterm birth, and low birth body weight. However, due to a lack of studies, the strategies of dietary and nutritional supplement for fetal growth restriction prevention are not statistically effective and are not yet recommended. The present review is to provide an overview of the clinical and the experimental evidence of Vitamin D deficiency-related complication and review of available options for the prevention and management of these complications.

Impact of Maternal Air Pollution Exposure on Children's Lung Health: An Indian Perspective.

Air pollution has become an emerging invisible killer in recent years and is a major cause of morbidity and mortality globally. More than 90% of the world’s children breathe toxic air every day. India is among the top ten most highly polluted countries with an average PM10 level of 134 μg/m3 per year. It is reported that 99% of India’s population encounters air pollution levels that exceed the World Health Organization Air Quality Guideline, advising a PM2.5 permissible level of 10 μg/m3. Maternal exposure to air pollution has serious health outcomes in offspring because it can affect embryonic phases of development during the gestation period. A fetus is more prone to effects from air pollution during embryonic developmental phases due to resulting oxidative stress as antioxidant mechanisms are lacking at that stage. Any injury during this vulnerable period (embryonic phase) will have a long-term impact on offspring health, both early and later in life. Epidemiological studies have revealed that maternal exposure to air pollution increases the risk of development of airway disease in the offspring due to impaired lung development in utero. In this review, we discuss cellular mechanisms involved in maternal exposure to air pollution and how it can impact airway disease development in offspring. A better understanding of these mechanisms in the context of maternal exposure to air pollution can offer a new avenue to prevent the development of airway disease in offspring.

186 - Loss of the transcriptional repressor Rev-erbα results in increased oxidative phosphorylation and reduced fatty acid utilization in mouse embryonic fibroblasts

Preterm newborns with immature lungs receive life-saving supplemental oxygen. This treatment has improved survival rates but can also be toxic. Hyperoxia impairs lung development, causing long term respiratory and neurodevelopmental consequences. There are no therapeutic targets for supplemental oxygen toxicity. We have previously shown that exposure to hyperoxia (95% O2/5 % CO2) for 24 hours reduced levels of the transcriptional repressor and metabolic regulator, Rev-erbα, in mouse lung fibroblasts. We hypothesized that loss of Rev-erbα alters metabolism and substrate utilization in a mouse embryonic fibroblast (MEF) model. To test this, knockout (KO) and wild type (WT) MEF were grown to 80% confluency. Oxidative phosphorylation (oxphos), glycolysis, and substrate utilization were measured using a Seahorse XF24 Bioanalyzer. Rev-erbα KO MEF had increased oxphos compared with WT. Levels of glycolytic extracellular acidification were unchanged. Mitochondrial to nuclear DNA copy number ratios, measured by determining the levels of mitochondrial NADH dehydrogenase 1 over nuclear hexokinase 2, by PCR, were also unchanged. This demonstrated that increased oxphos was not caused by mitochondrial biogenesis. Rev-erbα KO MEF exhibited increased expression of ribose-5-phosphate isomerase and transketolase mRNA. These enzymes provide metabolic intermediates to glycolysis as part of the oxidative pentose phosphate pathway and may increase the amount of pyruvate available for oxphos. Rev-erbα KO MEF additionally exhibited a reduced dependency on fatty acids and glutamine. Reduced dependency on fatty acids may be related to a four-fold increase in expression of acyl-CoA synthetase 6 compared with WT. This enzyme is known to provide acyl-CoA for triacylgylceride synthesis in neurons, but whether it directs acyl-CoA to or away from beta oxidation in MEFs is unclear. In conclusion, loss of Rev-erbα increases oxphos and reduces fatty acid dependency in MEFs. We speculate that loss of Rev-erbα transcriptional repression causes upregulation of enzymes governing oxphos and acyl-CoA utilization for energy.

Combustion-derived particles inhibit in vitro human lung fibroblast-mediated matrix remodeling

BackgroundThe continuously growing human exposure to combustion-derived particles (CDPs) drives in depth investigation of the involved complex toxicological mechanisms of those particles. The current study evaluated the hypothesis that CDPs could affect cell-induced remodeling of the extracellular matrix due to their underlying toxicological mechanisms. The effects of two ultrafine and one fine form of CDPs on human lung fibroblasts (MRC-5 cell line) were investigated, both in 2D cell culture and in 3D collagen type I hydrogels. A multi-parametric analysis was employed.ResultsIn vitro dynamic 3D analysis of collagen matrices showed that matrix displacement fields induced by human lung fibroblasts are disturbed when exposed to carbonaceous particles, resulting in inhibition of matrix remodeling. In depth analysis using general toxicological assays revealed that a plausible explanation comprises a cascade of numerous detrimental effects evoked by the carbon particles, including oxidative stress, mitochondrial damage and energy storage depletion. Also, ultrafine particles revealed stronger toxicological and inhibitory effects compared to their larger counterparts. The inhibitory effects can be almost fully restored when treating the impaired cells with antioxidants like vitamin C.ConclusionsThe unraveled in vitro pathway, by which ultrafine particles alter the fibroblasts’ vital role of matrix remodeling, extends our knowledge about the contribution of these biologically active particles in impaired lung tissue repair mechanisms, and development and exacerbation of chronic lung diseases. The new insights may even pave the way to precautionary actions. The results provide justification for toxicological assessments to include mechanism-linked assays besides the traditional in vitro toxicological screening assays.

Antenatal management of congenital diaphragmatic hernia today and tomorrow.

Congenital diaphragmatic hernia is rare birth defect, which can be easily corrected after birth. The main problem is that herniation of viscera during fetal life impairs lung development, leading to a 30% mortality and significant morbidity. In isolated cases the outcome can be accurately predicted prenatally by medical imaging. Cases with a poor prognosis can be treated before birth; clinically this is by fetoscopic endoluminal tracheal occlusion. Obstruction of the airways triggers lung growth. This procedure is currently being evaluated in a global clinical trial for left sided cases; right sided cases with poor prognosis are offered the procedure clinically. The search for more potent and less invasive therapies continues. Prenatal transplacental sildenafil administration will in due course be tried clinically, with the aim to reduce the occurrence of persistent pulmonary hypertension, either alone or in combination with fetal surgery. Other medical approaches are in an earlier translational phase.

Intra-Amniotic Soluble Endoglin Impairs Lung Development in Neonatal Rats

Soluble endoglin (sENG) is increased in the amniotic fluid of women with preeclampsia and chorioamnionitis. Preterm infants born to women with these disorders have an increased risk of aberrant lung development. Whether this increased risk is secondary to elevated sENG levels is unclear. The objective of this study was to determine whether intrauterine exposure to an adenovirus overexpressing sENG impairs neonatal lung angiogenesis by modulating lung endothelial nitric oxide synthase (eNOS) signaling. Pregnant Sprague-Dawley rats were randomly assigned to receive ultrasound-guided intra-amniotic injections of adenovirus overexpressing sENG (Ad-sENG) or control adenovirus (Ad-control) on embryonic day 17. After this exposure, rat pups were maintained in normoxia and evaluated on postnatal day 14. Intra-amniotic Ad-sENG decreased lung vascular endothelial growth factor receptor 2 and eNOS expression in rat pups. This was accompanied by a marked decrease in lung angiogenesis and alveolarization. Ad-sENG-exposed pups also had an increase in right ventricular systolic pressure, weight ratio of right ventricle to left ventricle plus septum, and pulmonary vascular remodeling. In addition, exposure of human pulmonary artery endothelial cells to recombinant sENG reduced endothelial tube formation and protein levels of eNOS, phosphorylated eNOS, and phosphorylated Smad1/5. Together, our findings demonstrate that intrauterine exposure to an adenovirus overexpressing sENG disrupts lung development by impairing Smad1/5-eNOS signaling. We speculate that sENG-mediated dysregulation of Smad1/5-eNOS signaling contributes to impaired lung development and potentially primes the developing lung for further postnatal insults. Further studies exploring the relationship between amniotic fluid sENG levels and preterm respiratory outcomes will be necessary.

Chronic vitamin D deficiency induces lung fibrosis through activation of the renin-angiotensin system

Pulmonary fibrosis, which influences lung function and exacerbates a patient’s condition, is the ultimate stage of many lung diseases. Vitamin D deficiency is associated with pulmonary fibrosis and impaired lung function, but the underlying mechanism has not yet been fully elucidated. Moreover, vitamin D deficiency may cause over-activation of the renin-angiotensin system (RAS), which aggravates extracellular matrix (ECM) deposition and lung fibrosis. This study aims to investigate the effect of chronic vitamin D deficiency on lung fibrosis in otherwise healthy mice and to explore the role of RAS in this process. Mice were depleted of vitamin D through diet control and were compared with healthy subjects. Chronic vitamin D deficiency destructs lung structures, impairs lung development and stimulates ECM deposition. RAS components are also found to increase. These effects seem to worsen with prolonged vitamin D deficiency. By giving RAS blockers, these changes can be largely rescued. However, a smooth muscle relaxant whose regulatory effect on blood pressure is independent of RAS does not show similar effects. This study demonstrated that chronic vitamin D deficiency may induce RAS activation, which subsequently stimulates the expression of profibrotic factors and activates the fibrotic cascade. This profibrotic effect of RAS is independent of elevated blood pressure.

Pulmonary exposure to metallic nanomaterials during pregnancy irreversibly impairs lung development of the offspring

Due to the growing commercial applications of manufactured nanoparticles (NPs), toxicological studies on NPs, especially during the critical window of development, are of major importance. The aim of the study was to assess the impact of respiratory exposure to metallic and metal oxide NPs during pregnancy on lung development of the offspring and to determine the key parameters involved in lung alterations. Pregnant mice were exposed to weekly doses of 100 μg (total dose 300 μg) of titanium dioxide (TiO2), cerium oxide (CeO2), silver (Ag) NPs or saline solution by nonsurgical intratracheal instillation. The offspring lungs were analyzed at different stages of lung development: fetal stage (gestational day 17.5), pulmonary alveolarization (post-delivery day 14.5) and lung maturity (post-delivery day 49.5). Regardless of the type of NP, maternal exposure during gestation induced long-lasting impairment of lung development of the offspring. This effect was accompanied by: i) decreased placental efficiency together with the presence of NPs in placenta, ii) no increase of inflammatory mediators present in amniotic fluid, placenta or offspring lungs and iii) decreased pulmonary expression of vascular endothelial growth factor-α (VEGF-α) and matrix metalloproteinase 9 (MMP-9) at the fetal stage, and fibroblast growth factor-18 (FGF-18) at the alveolarization stage. Respiratory exposure to metallic NPs during pregnancy induces stereotyped impairment of lung development with a lasting effect in adult mice, independently of the chemical nature of the NP.

Potential Role of Prenatal Inflammation in the Impairment of Lung Development Following Mechanical Ventilation of Preterm Lambs.

Our objective was to determine the effects of severe fetal inflammation, associated with an increase in the number and activation state of fetal polymorphonuclear leukocytes (PMNLs), on postnatal lung development in mechanically ventilated preterm lambs. Four groups of preterm fetal sheep (0.85 term) were surgically prepared: (1) a granulocyte-colony stimulating factor (GCSF) group received intravenous GCSF to increase fetal PMNL count, (2) a lipopolysaccharide (LPS) group received intra-amniotic LPS to activate the fetal PMNLs, (3) a GCSF + LPS group received both GCSF and LPS, and (4) a control group received saline. After 10-day mechanical ventilation following preterm delivery, the lungs were examined histologically and analyzed morphometrically. Compared to the control group, the GCSF + LPS group exhibited necrotizing funisitis, lower surface density of alveolar walls, lower numerical density of alveoli, greater alveolar radius, and lower volume density of secondary septal crests (all P < .05). There was no evidence of tissue destruction, or elastin fragmentation or thick deposits of elastin, in the alveolar walls in any of the 4 groups. The mechanical ventilation following severe prenatal inflammation did not lead to overt lung injury or degradation of elastin but resulted in arrested alveolarization in the lungs of preterm lambs.

Impact of air pollution in respiratory allergic diseases

Allergic respiratory disease, which includes allergic rhinoconjunctivitis and asthma, is one of the most common diseases, with a major impact on a patient's quality of life. Air pollution is one of the main factors associated with the development of allergic respiratory disease, it has been shown to impair lung development in children and adolescents. The origins of particulate matter produced from various sources, including those issued by traffic and the burning of fuels such as coal, gasoline and diesel. Diesel emissions represent the majority of the particulate matter in urban air pollution. It has been found that the co-exposure of diesel emissions and airborne allergens increases allergen-specific IgE levels, severity of asthma, inflammation and airway hyper-responsiveness. In vivo and in vitro studies have reported the activation of anti-transcription and pro-inflammatory mediators. Polycyclic aromatic hydrocarbons, metal components or metabolites may increase due to the formation of oxygen reactive species that interact with DNA, producing different types of damage as oxidative damage.

Lethal lung hypoplasia and vascular defects in mice with conditional Foxf1 overexpression.

ABSTRACTFOXF1 heterozygous point mutations and genomic deletions have been reported in newborns with the neonatally lethal lung developmental disorder, alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV). However, no gain-of-function mutations in FOXF1 have been identified yet in any human disease conditions. To study the effects of FOXF1 overexpression in lung development, we generated a Foxf1 overexpression mouse model by knocking-in a Cre-inducible Foxf1 allele into the ROSA26 (R26) locus. The mice were phenotyped using micro-computed tomography (micro-CT), head-out plethysmography, ChIP-seq and transcriptome analyses, immunohistochemistry, and lung histopathology. Thirty-five percent of heterozygous R26-Lox-Stop-Lox (LSL)-Foxf1 embryonic day (E)15.5 embryos exhibit subcutaneous edema, hemorrhages and die perinatally when bred to Tie2-cre mice, which targets Foxf1 overexpression to endothelial and hematopoietic cells. Histopathological and micro-CT evaluations revealed that R26Foxf1; Tie2-cre embryos have immature lungs with a diminished vascular network. Neonates exhibited respiratory deficits verified by detailed plethysmography studies. ChIP-seq and transcriptome analyses in E18.5 lungs identified Sox11, Ghr, Ednrb, and Slit2 as potential downstream targets of FOXF1. Our study shows that overexpression of the highly dosage-sensitive Foxf1 impairs lung development and causes vascular abnormalities. This has important clinical implications when considering potential gene therapy approaches to treat disorders of FOXF1 abnormal dosage, such as ACDMPV.

Prenatal stress challenge in mice impairs lung development sex-specifically in female fetuses

Prenatal stress challenge in mice impairs lung development sex-specifically in female fetuses

Prenatal stress challenge in mice impairs lung development sex-specifically in female fetuses

Prenatal stress challenge in mice impairs lung development sex-specifically in female fetuses