With the development of treatment, the survival rate of premature infants has significantly increased, especially extremely premature infants and very low birth weight infants. This has led to an increase in incidence of bronchopulmonary dysplasia (BPD) year by year. BPD has been one of the most common respiratory system diseases in premature infants, especially the small premature infants. Arrested alveolar development is an important cause of BPD. Therefore, the mechanism of arrested alveolar development and the intervention measures for promoting alveolar development are the focuses of research on BPD. Selecting the appropriate animal model of BPD is the key to obtaining meaningful results in the basic research on BPD. Based on above, several common methods for establishing an animal model of BPD and the corresponding changes in pathophysiology are summarized and evaluated in order to provide a reference for selecting the appropriate animal model in studies on the pathogenesis, pathophysiology, and prevention and control strategies of BPD.
Animals ; Bronchopulmonary Dysplasia ; etiology ; Disease Models, Animal ; Humans ; Hyperoxia ; complications ; Respiration, Artificial ; adverse effects

OBJECTIVES: To study the role of adrenomedullin (ADM) in hyperoxia-induced lung injury by examining the effect of ADM on the expression of calcitonin receptor-like receptor (CRLR), receptor activity-modifying protein 2 (RAMP2), extracellular signal-regulated kinase (ERK), and protein kinase B (PKB) in human pulmonary microvascular endothelial cells (HPMECs) under different experimental conditions. METHODS: HPMECs were randomly divided into an air group and a hyperoxia group ( RESULTS: Compared with the air group, the hyperoxia group had significant increases in the mRNA and protein expression levels of ADM, CRLR, RAMP2, ERK1/2, and PKB ( CONCLUSIONS ERK1/2 and PKB may be the downstream targets of the ADM signaling pathway. ADM mediates the ERK/PKB signaling pathway by regulating CRLR/RAMP2 and participates in the protection of hyperoxia-induced lung injury.
Adrenomedullin/genetics* ; Endothelial Cells ; Humans ; Hyperoxia/complications* ; Lung Injury ; Receptor Activity-Modifying Proteins

OBJECTIVES: To study the role of the low-density lipoprotein receptor-related protein 1 (LRP1)-proline-rich tyrosine kinase 2 phosphorylation (pPyk2)-matrix metalloproteinases 9 (MMP9) pathway in hyperoxia-induced lung injury in neonatal rats. METHODS: A total of 16 neonatal rats were randomly placed in chambers containing room air (air group) or 95% medical oxygen (hyperoxia group) immediately after birth, with 8 rats in each group. All of the rats were sacrificed on day 8 of life. Hematoxylin and eosin staining was used to observe the pathological changes of lung tissue. ELISA was used to measure the levels of soluble LRP1 (sLRP1) and MMP9 in serum and bronchoalveolar lavage fluid (BALF). Western blot was used to measure the protein expression levels of LRP1, MMP9, Pyk2, and pPyk2 in lung tissue. RT-PCR was used to measure the mRNA expression levels of LRP1 and MMP9 in lung tissue. RESULTS: The hyperoxia group had significantly higher levels of sLRP1 and MMP9 in serum and BALF than the air group ( CONCLUSIONS The activation of the LRP1-pPyk2-MMP9 pathway is enhanced in hyperoxia-induced lung injury in neonatal rats, which may be involved in the pathogenesis of bronchopulmonary dysplasia.
Animals ; Animals, Newborn ; Hyperoxia/complications* ; Lung ; Lung Injury/etiology* ; Matrix Metalloproteinase 9/genetics* ; Rats

OBJECTIVETo study the effect of hyperoxia exposure on high mobility group protein-B1 (HMGB1) expression in neonatal mice and the role of HMGB1 in the pathogenesis of bronchopulmonary dysplasia (BPD).

METHODSC57BL/6 mice were randomly exposed to 60% O2 or air 1 day after birth. BPD was induced by 60% O2 exposure. The pulmonary tissue samples were harvested 3, 7 and 14 days after exposure. The pathologic changes of pulmonary tissues were observed by hematoxylin and eosin staining, Masson staining and radical alveolar count. The expression of HMGB1 protein in lungs was detected by immunofluorescence. The expression of HMGB1 mRNA was detected by real-time fluorescent quantitative PCR.

RESULTSIn the BPD group, the lungs developed decreased alceolar septation, swollen alveolar epithelium, stroma edema, interstitial fibrosis and developmental lag when compared with the control group. These changes became more obvious with more prolonged hyperoxia exposure. The expression of HMGB1 protein and mRNA 7 and 14 days after exposure increased significantly in the BPD group compared with that in the control group.

CONCLUSIONSHyperoxia exposure results in an increase in lung HMGB1 expression. The increased HMGB1 expression may be associated with the development of BPD.

Animals ; Bronchopulmonary Dysplasia ; etiology ; HMGB1 Protein ; analysis ; genetics ; physiology ; Humans ; Hyperoxia ; complications ; Infant, Newborn ; Lung ; pathology ; Mice ; Mice, Inbred C57BL ; RNA, Messenger ; analysis

OBJECTIVETo explore the protective effects of mitochondrial ATP-sensitive potassium channel opener diazoxide on hyperoxia-induced apoptosis of type II alveolar epithelial cells (A549 cells) and possible mechanisms.

METHODSA549 cells were cultured in vitro and divided randomly into control, hyperoxia and diazoxide group. The hyperoxia group was exposed to a mixture of O2 (900 mL/L) and CO2 (50 mL/L) for 10 minutes, then cultured in a closed environment. The diazoxide group was pretreated with diazoxide of 100 μmol/L for 24 hrs before hyperxia induction. The cells were collected 12, 24 and 48 hrs after culture. The morphologic changes of A549 cells were observed under an inverted microscope. A549 cell apoptosis was detected by flow cytometry. The expression of Omi/HtrA2 in the endochylema of A549 cells was determined by immunohistochemistry.

RESULTSA549 cells were damaged and the changes in morphology of the cells were serious in the hyperoxia group. The apoptosis rate of A549 cells and the expression of Omi/HtrA2 in the endochylema increased in the hyperoxia group compared with the control group (P<0.05). The growth and the morphology of A549 cells were greatly improved and the cell injuries were obviously alleviated in the diazoxide group. The expression of Omi/HtrA2 in the endochylema and the apoptosis rate of A549 cells were significantly reduced in the diazoxide group compared with the hyperoxia group (P<0.05).

CONCLUSIONSDiazoxide as an opener of mitoKATP channel can reduce the expression of Omi/HtrA2 and the apoptosis rate of A549 cells, thus relieves the injury of A549 cells induced by hyperoxia.

Apoptosis ; Cells, Cultured ; Cytoprotection ; Diazoxide ; pharmacology ; High-Temperature Requirement A Serine Peptidase 2 ; Humans ; Hyperoxia ; complications ; Lung ; pathology ; Mitochondrial Proteins ; analysis ; Potassium Channels ; physiology ; Serine Endopeptidases ; analysis

PURPOSE: This study was undertaken to determine the effects of intratracheal administration of endotoxin on hyperoxia-induced lung injury in neonatal rats. MATERIALS AND METHODS: Newborn Sprague Dawley rat pups were divided into four experimental groups: normoxia control (NC), normoxia with endotoxin treatment (NE), hyperoxia control (HC), and hyperoxia with endotoxin treatment (HE) groups. In HC and HE, rat pups were subjected to 14 days of hyperoxia (> 95% oxygen) within 12 hours after birth. In endotoxin treated group (NE and HE), Escherichia coli endotoxin (0.5microgram in 0.03mL of saline) was given intratracheally at the 1st, 3rd and 5th postnatal day. Radial alveolar count (RAC), mean linear intercept (MLI), RAC/MLI ratios, and degree of fibrosis were measured to assess the changes in lung morphology. RESULTS: During the research period, survival rates in both HC and HE were notably reduced 7 days after endotoxin was administered, but body weight gain was considerably reduced only in HC. On day 14, significant arrest in alveolarization, as evidenced by the decrease of RAC and RAC/MLI ratio and increase of MLI as well as increased fibrosis, were noted in HC. Although slight but significant arrest in alveolarization and increased fibrosis score were observed in NE compared to NC, the hyperoxia-induced lung damage observed in HC was significantly improved in HE. CONCLUSION: This study suggests that intratracheal administration of endotoxin significantly attenuated hyperoxia-induced lung injury in neonatal rats.
Animals ; Animals, Newborn ; Body Weight ; Drug Administration Routes ; Endotoxins/*administration & dosage ; Hyperoxia/*complications ; Lung Diseases/*chemically induced/*etiology/pathology ; *Lung Injury ; Rats ; Rats, Sprague-Dawley

Animals ; Animals, Newborn ; Antioxidants ; therapeutic use ; Female ; Hyperoxia ; complications ; drug therapy ; Lung Injury ; drug therapy ; etiology ; Male ; Rats ; Rats, Sprague-Dawley

OBJECTIVEResolution of alveolar damage after lung injury requires finely orchestrated processes that include coordinated and effective tissue reconstruction to reestablish a functional barrier. Reconstitution of denuded type I alveolar epithelial cell that undergo apoptotic and necrotic death after lung injury is required in many pulmonary diseases. Disruption of distal airway development and type II-type I alveolar epithelial cell differentiation after lung injury and disordered repair of the alveolus after injury is one of the predominant pathological characteristics of chronic lung disease (CLD) of premature infants. HoxB5 belongs to the Hox gene family encoding transcription factors known for their role in skeletal patterning and the elaboration of organs. HoxB5 is required for embryonic respiratory tract morphogenesis. The present study aimed to test the hypothesis that HoxB5 may participate in the etiology of CLD and to understand possible mechanism.

METHODSPremature rat pups were taken out surgically at gestational age 21 d. CLD was induced by hyperoxia exposure in neonatal premature rats. Eighty premature rats were randomly exposed to hyperoxia (FiO2 = 0.90, CLD group) and to room air (FiO2 = 0.21, control group) (n = 40 each). Lung specimens were obtained respectively on days 1, 3, 7, 14 and 21 after exposure. Histopathologic changes was assayed after hematoxylin and eosin (HE) staining and pulmonary development was evaluated by lung coefficient and radical alveolar counts (RAC), dynamic changes of RAC were observed; and the expression of HoxB5, AQP-5, and SP-B mRNA were assayed by reverse transcription polymerase chain reaction (RT-PCR).

RESULTSThere were no significant differences in the RAC and the expression level of HoxB5, AQP-5, and SP-B mRNA between the CLD and the control groups within 3 days after birth (P > 0.05). However, compared to the control group, the RAC of the CLD group was reduced (6.35 +/- 0.83 vs. 7.67 +/- 0.52), and the expression of HoxB5 (0.98 +/- 0.14 vs. 1.20 +/- 0.16), AQP-5 (0.78 +/- 0.11 vs. 1.04 +/- 0.19) mRNA were significantly lower (P < 0.05), while the expression of SP-B mRNA was increased on the 7th day (P < 0.05). On the 14th day, the RAC and the expression of HoxB5, AQP-5 mRNA of CLD group were significantly lower than those of the control group (P < 0.05), and the expression of SP-B mRNA continued to increase (P < 0.05). On the 21st day, the expression of HoxB5, AQP-5 mRNA decreased to the nadir (0.64 +/- 0.11 vs. 1.18 +/- 0.13 and 0.67 +/- 0.12 vs. 0.97 +/- 0.01, respectively) (P < 0.01), on the same day the expression of SP-B mRNA reached to the pinnacle (1.43 +/- 0.07 vs. 1.12 +/- 0.09) (P < 0.01). The expression of HoxB5 mRNA was positively correlated with RAC in the CLD group (r = 0.685, P < 0.01).

CONCLUSIONSWith hyperoxia exposure, the mRNA expression of specific marker of type I alveolar epithelial cell, AQP-5, was decreased while specific marker of type II alveolar epithelial cell, SP-B, was increased; and the expression of HoxB5 mRNA in lung tissues kept on decreasing. Decreased expression of HoxB5 may associate with the disruption of type II-I alveolar epithelial cell differentiation and thus may play an important role in inhibition of lung development with CLD. The altered Hox gene expression may predispose lung pathology.

Animals ; Animals, Newborn ; Female ; Homeodomain Proteins ; genetics ; metabolism ; Hyperoxia ; complications ; Lung ; growth & development ; metabolism ; pathology ; Lung Diseases ; etiology ; metabolism ; pathology ; Pregnancy ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVEVascular endothelial growth factor (VEGF) contributes to lung development and recovery of lung structure from lung injury. This study aimed to explore the changes of expression of VEGF protein and mRNA in neonatal rats following hyperoxic lung injury.

METHODSForty-eight Sprague-Dawley neonatal rats were randomly continually exposed to hyperoxia (FiO2=95%) or to room air (FiO2=21%, control group) 30 minutes after birth. VEGF protein and mRNA expression in the lungs was determined by immunohistochemical methods and reverse tanscription polymerasechain reaction (RT-PCR) respectively 3,7 and 14 days after birth.

RESULTSVEGF protein and mRNA expression increased with increasing postnatal age in the control group. In the hyperoxia exposure group VEGF protein expression decreased markedly at 7 days (7.79+/-5.23 vs 12.67+/-3.82; P<0.01) and 14 days of hyperoxia exposure (5.85+/-3.37 vs 15.10+/-8.91; P<0.01) compared with the controls. VEGF mRNA expression in the hyperoxia exposure group was significantly reduced from 3 days (0.78+/-0.22 vs 1.19+/-0.63) through 14 days of hyperoxia exposure (0.48+/-0.12 vs 1.89+/-0.81) compared with the controls (P<0.01).

CONCLUSIONSVEGF is associated with lung development in neonatal rats. Hyperoxia exposure can decrease VEGF protein and VEGF mRNA expression in the lungs of neonatal rats. VEGF might be involved in the pathogenesis of hyperoxic lung injury.

Animals ; Animals, Newborn ; Female ; Hyperoxia ; complications ; Lung ; chemistry ; metabolism ; Lung Diseases ; etiology ; metabolism ; Male ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Vascular Endothelial Growth Factor A ; analysis ; genetics

Antioxidants ; metabolism ; therapeutic use ; Bronchopulmonary Dysplasia ; drug therapy ; etiology ; metabolism ; Humans ; Hyperoxia ; complications ; Infant, Newborn ; Lung ; metabolism ; Reactive Oxygen Species ; metabolism