Improvement of batyl alcohol on alveolarization arrest in newborn rats with bronchopulmonary dysplasia / 上海交通大学学报（医学版）

Objective: To investigate whether batyl alcohol (BTA) can improve the pathology of bronchopulmonary dysplasia (BPD) in newborn rats induced by lipopolysaccharide (LPS) and the mechanism. Methods: Pregnant SD rats (16.5 d) were randomly assigned into Saline group, LPS group, and LPS+BTA group. Amniocentesis injection of LPS was performed to establish neonatal bronchopulmonary dysplasia (BPD) rat model. In LPS+BTA group, LPS and BTA were injected at the same time. After birth, LPS+BTA group was injected with BTA continuously everyday for 7 days. The other two groups were injected with normal saline of equal volume. Lung tissues of neonatal rats on the first, third and seventh day after birth were stained by hematoxylin-eosin (H-E) and resorcin-fuchsin respectively, to observe alveolarization arrest. The mRNA and protein levels of interleukin 1β (IL-1β) in newborn rats lungs were detected by real-time PCR and ELISA. In vitro, mouse macrophages RAW264.7 were cultured to detect IL-1β mRNA levels and protein levels after treatment with LPS and BTA. SD rat bone marrow macrophages were isolated and treated with LPS and BTA. RNA-sequence was taken to screen for possible targets of BTA inhibition of inflammation. Results: The results of H-E staining showed that LPS+BTA group had a milder pathology of BPD, with more secondary septa counts, more alveolar counts, and smaller mean linear intercept (all P<0.05); after BTA intervention the expression levels of IL-1β mRNA and protein in lung tissues of neonatal rats were significantly lower than those in LPS group (both P<0.05). In vitro, IL-1β mRNA and protein increased after LPS stimulation (both P=0.000), but decreased in the LPS+BTA group (both P<0.05). RNA-sequence results showed that BTA inhibited the expressions of some inflammatory factors, such as thrombospondin1 (Thbs1), triggering receptor expressed on myeloid cells 1 (Trem1), and cluster of differentiation 274 (Cd274), and promoted the expressions of some anti-inflammatory factors, such as complement C1q C chain (C1qc), RT1 class Ⅱ, locus Da (RT1-Da), and RT1 class Ⅱ, locus Db1 (RT1-Db1). Conclusion: BTA can improve lung pathology of neonatal rats with BPD by downregulating the expression of IL-1β and reducing inflammatory response.

La nueva displasia broncopulmonar desde el punto de vista de neumólogo pediatra / New bronchopulmonary dysplasia, from a pediatric pulmonologist´s perspective

Bronchopulmonary dysplasia (BPD) is the most prevalent chronic lung disease of prematurity. The so-called new BPD has replaced the classic BPD described by Northway, as a result of maternal use of corticosteroids, early surfactant and less aggressive mechanical ventilation and the survival of younger premature, born during the canalicular stage and that completed their alveolization outside the uterus. The new BPD is a less severe disease, but lung function is impaired in the long-term. An update of the new BPD, focused on the management after discharge from neonatology, from a pediatric pulmonologist perspective is presented.

La Displasia Broncopulmonar (DBP) es la enfermedad pulmonar crónica más prevalente del prematuro. La denominada nueva DBP ha reemplazado a la DBP clásica descripta por Northway, como consecuencia del uso de corticoides maternos, surfactante precoz, ventilación mecánica menos agresiva y la sobrevivencia de prematuros más pequeños, que nacen en etapa canalicular de su desarrollo pulmonar y completan su alveolización fuera del útero. La nueva DBP es una patología menos severa, pero con compromiso funcional respiratorio a largo plazo. A continuación se describe una actualización de la nueva DBP, enfocada en el manejo realizado luego del alta de neonatología, desde el punto de vista del Neumólogo Pediatra.

Advances in arrested late lung development and bronchopulmonary dysplasia / 国际儿科学杂志

The process of late lung development is disturbed in bronchopulmonary dysplasia (BPD).One of the keys in late lung development is secondary septation, in which secondary septa arise from primary septa, producing plenty of small alveoli, which significantly increase the surface area of gas exchange.Secondary septation,together with architectural changes to the vascular structure of the lung which minimize the distance between the blood and the inspired air, are the targets of late lung development.BPD is a disease of premature infants in which development of the alveoli is stunted caused by many factors including volutrauma,inflammation,and oxygen toxicity.Compared with early lung development, the later development of the immature lung remains unclear.This paper is to emphasize remarkable latest research of arrested late lung development and BPD.

Deferoxamine Improves Alveolar and Pulmonary Vascular Development by Upregulating Hypoxia-inducible Factor-1alpha in a Rat Model of Bronchopulmonary Dysplasia

Fetal lung development normally occurs in a hypoxic environment. Hypoxia-inducible factor (HIF)-1alpha is robustly induced under hypoxia and transactivates many genes that are essential for fetal development. Most preterm infants are prematurely exposed to hyperoxia, which can halt hypoxia-driven lung maturation. We were to investigate whether the HIF-1alpha inducer, deferoxamine (DFX) can improve alveolarization in a rat model of bronchopulmonary dysplasia (BPD). A rat model of BPD was produced by intra-amniotic lipopolysaccharide (LPS) administration and postnatal hyperoxia (85% for 7 days), and DFX (150 mg/kg/d) or vehicle was administered to rat pups intraperitoneally for 14 days. On day 14, the rat pups were sacrificed and their lungs were removed and examined. A parallel in vitro study was performed with a human small airway epithelial cell line to test whether DFX induces the expression of HIF-1alpha and its target genes. Alveolarization and pulmonary vascular development were impaired in rats with BPD. However, DFX significantly ameliorated these effects. Immunohistochemical analysis showed that HIF-1alpha was significantly upregulated in the lungs of BPD rats treated with DFX. DFX was also found to induce HIF-1alpha in human small airway epithelial cells and to promote the expression of HIF-1alpha target genes. Our data suggest that DFX induces and activates HIF-1alpha, thereby improving alveolarization and vascular distribution in the lungs of rats with BPD.

Rosiglitazone, a Peroxisome Proliferator-Activated Receptor-gamma Agonist, Restores Alveolar and Pulmonary Vascular Development in a Rat Model of Bronchopulmonary Dysplasia

PURPOSE: We tested whether rosiglitazone (RGZ), a peroxisome proliferator-activated receptor-gamma agonist, can restore alveolar development and vascular growth in a rat model of bronchopulmonary dysplasia (BPD). MATERIALS AND METHODS: A rat model of BPD was induced through intra-amniotic delivery of lipopolysaccharide (LPS) and postnatal hyperoxia (80% for 7 days). RGZ (3 mg/kg/d, i.p.) or vehicle was given daily to rat pups for 14 days. This model included four experimental groups: No BPD+vehicle (V), No BPD+RGZ, BPD+V, and BPD+RGZ. On D14, alveolarization, lung vascular density, and right ventricular hypertrophy (RVH) were evaluated. RESULTS: Morphometric analysis revealed that the BPD+RGZ group had significantly smaller and more complex airspaces and larger alveolar surface area than the BPD+V group. The BPD+RGZ group had significantly greater pulmonary vascular density than the BPD+V group. Western blot analysis revealed that significantly decreased levels of vascular endothelial growth factor (VEGF) and its receptor VEGFR-2 by the combined exposure to intra-amniotic LPS and postnatal hyperoxia were restored by the RGZ treatment. RVH was significantly lesser in the BPD+RGZ group than in the BPD+V group. CONCLUSION: These results suggest that RGZ can restore alveolar and pulmonary vascular development and lessen pulmonary hypertension in a rat model of BPD.

Alveolar Aspect of Bronchopulmonary Dysplasia

The pathologic hallmark of new bronchopulmonary dysplasia (BPD) is an arrest in alveolarization and vascular development. Alveoli are the fully mature gas-exchange units and alveolarization denotes the process through which the developing lung attains its fully mature structure. In human, alveolarization is mainly a postnatal event and begins in utero around 35 postmenstrual weeks and continues to 2 postnatal years. Beginning of respiration with very immature lungs as a result of preterm delivery renders the immature lung to be exposed to various injuries such as mechanical stretch, hyperoxia, infection/inflammation and leads to a disruption of normal alveolarization process, which is a main pathologic finding of BPD. Better understanding of the control mechanisms of normal alveolarization process should help us to figure out the pathophysiology of BPD and discover effective preventive or therapeutic measures for BPD. In this review, the pathologic evolution of BPD from 'old' to 'new' BPD, the detailed mechanisms of normal alveolarization, and the factors that disrupt normal alveolarization will be discussed.

Engraftment of Intraperitoneally Injected Bone Marrow Cells to Newborn Mice Injected with an Angiogenesis Inhibitor

PURPOSE: Bronchopulmonary dysplasia (BPD) is characterized by arrested vascular and alveolar growth in the premature lung. Considering the consequences of arrested lung growth, the idea of administering bone marrow cells to enhance the inborn repair mechanism is promising as this may reduce the morbidity and mortality of BPD. We followed enhanced green fluorescent protein (EGFP)-labeled bone marrow cells (BMC) injected intraperitoneally into non-EGFP mice in order to determine their fate after transplantation. METHODS: An angiogenesis inhibitor, SU1498, was injected subcutaneously on day 3 in non-EGFP C57BL/6 newborn mice to create a model of arrested alveolar development. On the following day, 1x10(6) BMCs isolated from major histocompatibility complex (MHC)- matched syngenic EGFP mice were injected intraperitoneally to non-EGFP BPD mice. Morphometric analysis, immunostaining, and confocal microscopy were performed to determine the fate of EGFP-positive stem cells in the injured lung. RESULTS: SU1498 injection reduced alveolar surface area and mean alveolar volume in newborn mice. BMC injection resulted in recovery of lung structure comparable to controls. EGFP-positive BMCs were identified in the lungs of the recipient mice after intraperitoneal injection. The injected EGFP cells were co-stained with endothelial and epithelial cells of the developing lung as determined by confocal microscopy. CONCLUSION: Our results illustrated that EGFP-positive BMCs engrafted and trans- differentiated into epithelial and endothelial cells after intraperitoneal injection in a mouse model of arrested alveolar development.

The Effects of Bone Marrow-Derived Mesenchymal Stem Cells on Alveolarization Inhibition Induced by Hyperoxia in Neonatal Rat

PURPOSE: We sought to determine whether bone marrow-derived mesenchymal stem cells (BMMSC) could attenuate the inhibition of alveolarization induced by hyperoxia. METHODS: Human BMMSC (SNU-hMSC) were infused into the peritoneal cavity (IP) or trachea (IT) of neonatal rats exposed to hyperoxia (90% O2 from D1) on D5. The rats were then exposed to the same degree of hyperoxia for another 9d and sacrificed on D21. Morphometric analysis of the lungs and immunofluorescent staining in order to determine cell fates of infused SNU-hMSC were performed. RESULTS: The airspace of the hyperoxia control group (90% O2 for 14d) was significantly larger and more simple (mean linear intercept [Lm] : 68+/-16 micrometer vs 33+/-3 micrometer) and the alveolar surface area [SA] was significantly smaller (646+/-72 cm2 vs 1,042+/-477 cm2) than those of the normoxia control group. The Lm of the BMMSC- infused groups was significantly shorter irrespective of infusion route (52+/-2 micrometer [IP], 50+/-8 micrometer [IT] vs 68+/-16 micrometer) and the SA of the BMMSC IP infusion group was significantly larger (646+/-172 cm2 vs 346+/-142 cm2) than those of the hyperoxia control group. The IT-, but not IP-, infused BMMSC groups were observed in lung tissue and assumed to be type I and type II alveolar epithelial cell phenotypes. CONCLUSION: BMMSC, when infused into neonatal rats exposed to hyperoxia, significantly attenuated the inhibition of alveolarization irrespective of the infusion route. It seems that BMMSC, when infused IT, engrafts into lung tissue and differentiates into alveolar epithelial cells. These results indicate that BMMSC could be considered as a potential candidate therapy for bronchopulmonary dysplasia.

Factors Involved in Lung Development and Alveolarization / 소아과

Lung development is a sum of processes that involve harmonized orchestration of expressions of various factors in time and space. The mastermind governing these phenomena is not known, but cumulative efforts so far have helped us gain some insights as to what are involved in and how complex the developmental process is. Beginning as primitive foregut, lungs undergo processes called branching morphogenesis and alveolarization to attain complex structures that enable effective gas exchange through conducting airways and acini. Some transcription factors, peptide growth factors, extracellular matrix proteins, and integrin and related factors are among many factors that are known to be involved. They are spatially localized and compartmentalized to render specific actions such as cellular proliferation, differentiation and apoptosis, meanwhile timely expressions of the same factors at specified time intervals are essential. Some are expressed in epithelial cells whereas others in mesenchymal cells; the crosstalks among them seem critical in coordination of developmental processes. Understanding these molecular mechanisms of lung development under normal and abnormal conditions may help devise methods to prevent as well as to revert aberrant development seen in many clinical conditions known as bronchopulmonary dysplasia, pulmonary fibrosis, and emphysema.