Placenta growth factor elevation in the cord blood of premature neonates predicts poor pulmonary outcome

Early Biomarkers of Bronchopulmonary Dysplasia: A Quick Look to the State of the Art

Bronchopulmonary dysplasia (BPD) is one of the most common pulmonary sequelae of extreme preterm birth, with long-lasting respiratory symptoms and reduced lung function. A reliable predictive tool of BPD development is urgent and its search remains one of the major challenges for neonatologists approaching the upcoming arrival of possible new preventive therapies. Biomarkers, identifying an ongoing pathogenetic pathway, could allow both the selection of preterm infants with an evolving disease and potentially the therapeutic targets of the indicted pathogenesis. The "omic" sciences represent well-known promising tools for this objective. In this review, we resume the current laboratoristic, metabolomic, proteomic, and microbiomic evidence in the prediction of BPD. KEY POINTS: · The early prediction of BPD development would allow the targeted implementation of new preventive therapies.. · BPD is a multifactorial disease consequently it is unlikely to find a single disease biomarker.. · "Omic" sciences offer a promising insight in BPD pathogenesis and its development's fingerprints..

Molecular mechanisms underlying hyperoxia-induced lung fibrosis

Supplemental oxygen is often used to treat newborns with respiratory disorders. Exposure to high concentration of oxygen and long-term oxygen causes inflammation and acute lung injury. The acute inflammatory phase is followed by a fibroproliferative repair phase, leading to lung fibrosis. Many infants with lung fibrosis develop significant respiratory morbidities including reactive airways dysfunction and obstructive lung disease during childhood. Despite the absence of effective treatments and the incomplete understanding regarding mechanisms underlying fibrosis, extensive literature regarding lung fibrosis from in vitro and in vivo hyperoxia-exposed models is available. In this review, we discuss molecular mediators and signaling pathways responsible for increased fibroblast proliferation and collagen production, excessive extracellular matrix accumulation, and eventually, lung fibrosis. We discuss each of these mediators separately to facilitate clear understanding as well as significant interactions occurring among these molecular mediators and signaling pathways.

Increased circulating cytokeratin 19 fragment levels in preterm neonates receiving mechanical ventilation are associated with poor outcome

Invasive mechanical ventilation and oxygen toxicity are postnatal contributors to chronic lung disease of prematurity, also known as bronchopulmonary dysplasia (BPD). Cyfra 21-1 is a soluble fragment of cytokeratin 19, which belongs to the cytoskeleton stabilizing epithelial intermediate filaments. As a biomarker of structural integrity, Cyfra 21-1 might be associated with airway injury and lung hypoplasia in neonates. Serum Cyfra 21-1 concentrations for 80 preterm and 80 healthy term newborns were measured within 48 h after birth. Preterm infants with the combined endpoint BPD/mortality had significantly higher Cyfra 21-1 levels compared with those without fulfilling BPD/mortality criteria (P = 0.01). Also, severe RDS (>grade III) was associated with higher Cyfra levels (P = 0.01). Total duration of oxygen therapy was more than five times longer in neonates with high Cyfra 21-1 levels (P = 0.01). Infants with higher Cyfra 21-1 values were more likely to receive mechanical ventilation (50% vs. 17.5%). However, the duration of mechanical ventilation was similar between groups. The median Cyfra value was 1.93 ng/mL (IQR: 1.68-2.53 ng/mL) in healthy term neonates and 8.5 ng/mL (IQR: 3.6-16.0 ng/mL) in preterm infants. Using ROC analysis, we calculated a Cyfra cutoff > 8.5 ng/mL to predict BPD/death with an AUC of 0.795 (P = 0.004), a sensitivity of 88.9%, and a specificity of 55%. Mortality was predicted with a cutoff > 17.4 ng/mL (AUC: 0.94; P = 0.001), a sensitivity of 100%, and a specificity of 84%. These findings suggest that Cyfra 21-1 concentration might be useful to predict poor outcome in premature infants.

The Association of Pregnancy-induced Hypertension with Bronchopulmonary Dysplasia - A Retrospective Study Based on the Korean Neonatal Network database

The prevalence of pregnancy-induced hypertension (PIH) and preeclampsia (PE) are 5-10% and 2-4%, respectively. PIH might affect angiogenesis in preterm neonates, but its association with bronchopulmonary dysplasia (BPD) remains controversial. This study evaluated the association between PIH and BPD in very low-birth weight infants. We retrospectively analysed the maternal, perinatal, and neonatal data of preterm infants born before 30 weeks of gestation, selected from the nationwide registry of very low-birth weight infants, between January 2013 and December 2014. As a result, 1,624 infants without maternal PIH (gestational age: 27.3 ± 1.8 weeks) and 203 infants with maternal PIH (28.0 ± 1.4 weeks, p < 0.001) were included. Birth weight was higher in the non-PIH group, compared with the PIH group (1027.4 ± 250.2 vs. 876.4 ± 261.5 g, p < 0.001). Multivariate logistic regression showed that PIH was associated with BPD (adjusted OR 1.474, 95% confidence interval 1.025-2.121), after adjusting for confounders, including small-for-gestation age (SGA). The result of present study is consistent with the current concept of BPD as an early form of pulmonary vascular disease, for both PIH and BPD are attributed by abnormal vascular formation.

Bronchopulmonary dysplasia

In the absence of effective interventions to prevent preterm births, improved survival of infants who are born at the biological limits of viability has relied on advances in perinatal care over the past 50 years. Except for extremely preterm infants with suboptimal perinatal care or major antenatal events that cause severe respiratory failure at birth, most extremely preterm infants now survive, but they often develop chronic lung dysfunction termed bronchopulmonary dysplasia (BPD; also known as chronic lung disease). Despite major efforts to minimize injurious but often life-saving postnatal interventions (such as oxygen, mechanical ventilation and corticosteroids), BPD remains the most frequent complication of extreme preterm birth. BPD is now recognized as the result of an aberrant reparative response to both antenatal injury and repetitive postnatal injury to the developing lungs. Consequently, lung development is markedly impaired, which leads to persistent airway and pulmonary vascular disease that can affect adult lung function. Greater insights into the pathobiology of BPD will provide a better understanding of disease mechanisms and lung repair and regeneration, which will enable the discovery of novel therapeutic targets. In parallel, clinical and translational studies that improve the classification of disease phenotypes and enable early identification of at-risk preterm infants should improve trial design and individualized care to enhance outcomes in preterm infants.

Predicting the likelihood of bronchopulmonary dysplasia in premature neonates

Introduction: Bronchopulmonary dysplasia (BPD) is the most common serious pulmonary morbidity in premature infants. Despite ongoing advances in neonatal care, the incidence of BPD has not improved. A potential explanation for this phenomenon is the limited ability for accurate early prediction of the risk of BPD. BPD continues to represent a therapeutic challenge and no single effective therapy exists for this condition. Areas covered: Here, we review risk factors of BPD derived from clinical data, biological fluid biomarkers, respiratory management data, and scientific advancements using 'omics' technologies, and their ability to predict the pathogenesis of BPD in preterm neonates. Risk factors and biomarkers were identified via literature search with a focus on the last 5 years of data. Expert opinion: The most accurate predictive tools utilize risk factors that encompass a variety of categories. Numerous predictive models have been proposed but suffer from a lack of adequate validation. An ideal model should include multiple, easily measurable variables validated across a heterogeneous population. In addition to evaluating recent BPD prediction models, we suggest approaches to enhance future models.

Outcomes of singleton small for gestational age preterm infants exposed to maternal hypertension: a retrospective cohort study

BACKGROUND

Hypertensive disorders of pregnancy (HDP) are a major cause of small for gestational age (SGA). Preterm SGA infants have higher rates of adverse outcomes than appropriate for gestational age infants. However, the outcomes are not well established in the setting of HDP.

METHODS

Retrospective population-based study using the Canadian Neonatal Network database from January 1, 2010 to December 31, 2016 of SGA infants <33 weeks gestation. Using multivariable models, we determined the adjusted odds ratios (AORs) with 95% confidence intervals (CI) for mortality, bronchopulmonary dysplasia (BPD), severe intraventricular hemorrhage (IVH), severe retinopathy of prematurity, necrotizing enterocolitis, late-onset sepsis, and patent ductus arteriosus (PDA) in infants of HDP mothers and compared them to infants of non-HDP mothers.

RESULTS

Of the 2081 eligible SGA infants, 1317 (63%) were born to HDP mothers and had lower odds of mortality (AOR 0.57, 95% CI 0.39-0.83) and BPD (AOR 0.69, 95% CI 0.53-0.90). Sub-group analysis demonstrated decreased mortality in 26-28 and 29-32 weeks gestation groups, decreased BPD in 29-32 weeks gestation group, and decreased PDA in <26 weeks gestation group.

CONCLUSION

Preterm SGA infants of HDP mothers have lower odds of mortality and BPD compared to infants of non-HDP mothers.

Hypertensive disorders during pregnancy are associated with reduced severe intraventricular hemorrhage in very-low-birth-weight infants

OBJECTIVE

To determine differences in severe intraventricular hemorrhage (IVH) between very-low-birth-weight (≤1500 g, VLBW) infants born to mothers with and without hypertensive disorders (HD).

DESIGN/METHODS

Retrospective analysis from the Optum Neonatal Database. The primary outcome of interest was severe IVH (grade 3 or 4). Secondary outcomes included other neonatal morbidities, mortality, and length of hospitalization. Outcomes were compared between VLBW infants born to mothers with and without HD.

RESULTS

A total of 5456 infants met inclusion criteria. After multivariable regression analysis, risks of severe IVH and bronchopulmonary dysplasia (BPD) were lower ([OR 0.42, 95% CI 0.33-0.89, p = 0.01] and [OR 0.75, 95% CI 0.58-0.97, p = 0.03], respectively) and median length of hospitalization was decreased in the HD group (49 versus 61 days, p < 0.001).

CONCLUSIONS

VLBW infants born to mothers with HD have a decreased risk of severe IVH, BPD, and a shorter duration of hospitalization.

Addressing the challenges of phenotyping pediatric pulmonary vascular disease

Pediatric pulmonary vascular disease (PVD) and pulmonary hypertension (PH) represent phenotypically and pathophysiologically diverse disease categories, contributing substantial morbidity and mortality to a complex array of pediatric conditions. Here, we review the multifactorial nature of pediatric PVD, with an emphasis on improved recognition, phenotyping, and endotyping strategies for pediatric PH. Novel tailored approaches to diagnosis and treatment in pediatric PVD, as well as the implications for long-term outcomes, are highlighted.

Biomarkers for Bronchopulmonary Dysplasia in the Preterm Infant

Bronchopulmonary dysplasia (BPD) is a chronic inflammatory lung disease of very-low-birth-weight (VLBW) preterm infants, associated with arrested lung development and a need for supplemental oxygen. Over the past few decades, the incidence of BPD has significantly raised as a result of improved survival of VLBW infants requiring mechanical ventilation. While early disease detection is critical to prevent chronic lung remodeling and complications later in life, BPD is often difficult to diagnose and prevent due to the lack of good biomarkers for identification of infants at risk, and overlapping symptoms with other diseases, such as pulmonary hypertension (PH). Due to the current lack of effective treatment available for BPD and PH, research is currently focused on primary prevention strategies, and identification of biomarkers for early diagnosis, that could also represent potential therapeutic targets. In addition, novel histopathological, biochemical, and molecular factors have been identified in the lung tissue and in biological fluids of BPD and PH patients that could associate with the disease phenotype. In this review, we provide an overview of biomarkers for pediatric BPD and PH that have been identified in clinical studies using various biological fluids. We also present a brief summary of the information available on current strategies and guidelines to prevent and diagnose BPD and PH, as well as their pathophysiology, risk factors, and experimental therapies currently available.

Angiogenic Factors in Cord Blood of Preterm Infants Predicts Subsequently Developing Bronchopulmonary Dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) of prematurity is associated with impaired angiogenesis. Excess soluble fms-like tyrosine kinase-1 (sFlt-1) and lower levels of vascular endothelial growth factor (VEGF) impaired alveolarization in preterm rats. Overexpression of placenta growth factor (PlGF) in mice caused airspace enlargement, which is similar to BPD pathologically. Our study aimed to clarify whether cord blood levels of these angiogenic factors were associated with the development of BPD in preterm infants.

METHODS

Preterm infants of gestational age (GA) <35 weeks who already had all the data of cord blood VEGF, PlGF, and sFlt-1 levels in our previous studies were enrolled. Cord blood levels of VEGF, PlGF, and sFlt-1 were collected. BPD was defined as the need for supplemental oxygen or mechanical ventilation support at the postmenstrual age of 36 weeks. We used the Mann-Whitney U test for comparison between infants with and without BPD, and multivariate analysis with logistic regression to assess the association of these molecules and the development of BPD.

RESULTS

Infants with BPD had lower GA [(27 weeks (24-34) vs. 31 weeks (28-24)], lower birth body weight [882 g (620-1232) vs. 1538 g (886-2328)], a higher incidence of respiratory distress syndrome (RDS) (58% vs. 14%), and a higher level of PlGF [21.45 pg/dL (6.03-474.01) vs. 7.43 pg/dL (0.09-23.75)] as compared with those infants without BPD. The levels of VEGF and sFlt-1 did not differ significantly between the two groups. Multivariate logistic regression revealed that lower birth body weight (p = 0.022) and higher level of PlGF (p = 0.012) were significantly correlated with the development of BPD independently. There was no significant association between the level of VEGF or sFlt-1 and the development of BPD.

CONCLUSION

Cord blood level of PlGF, rather than VEGF or sFlt-1, was significantly increased in the BPD group. Consistent with our previous report, cord blood level of PlGF may be considered as a biomarker to predict subsequently developing BPD in preterm infants.

Biomarkers, Early Diagnosis, and Clinical Predictors of Bronchopulmonary Dysplasia

The pathogenesis of bronchopulmonary dysplasia (BPD) is multifactorial, and the clinical phenotype of BPD is extremely variable. Several clinical and laboratory biomarkers have been proposed for the early identification of infants at higher risk of BPD and for determination of prognosis of infants with a diagnosis of BPD. The authors review available literature on prediction tools and biomarkers of BPD, using clinical variables and biomarkers based on imaging, lung function measures, and measurements of various analytes in different body fluids that have been determined to be associated with BPD either in a targeted manner or by unbiased omic profiling.

Plasma vascular endothelial growth factor A and placental growth factor: novel biomarkers of pulmonary hypertension in congenital diaphragmatic hernia

Pulmonary hypertension (PH) due to abnormal pulmonary vascular development is an important determinant of illness severity in congenital diaphragmatic hernia (CDH). Vascular endothelial growth factor A (VEGFA) and placental growth factor (PLGF) may be important mediators of pulmonary vascular development in health and disease. This prospective study investigated the relationship between plasma VEGFA and PLGF and measures of pulmonary artery pressure, oxygenation, and cardiac function in CDH. A cohort of 10 infants with CDH consecutively admitted to a surgical neonatal intensive care unit (NICU) was recruited. Eighty serial plasma samples were obtained and analyzed by multiplex immunoassay to quantify VEGFA and PLGF. Concurrent assessment of pulmonary artery pressure (PAP) and cardiac function were made by echocardiography. Plasma VEGFA was higher and PLGF was lower in CDH compared with existing normative data. Combined plasma VEGFA:PLGF ratio correlated positively with measures of PAP, diastolic ventricular dysfunction, and oxygenation index. Nonsurvivors had higher VEGFA:PLGF ratio than survivors at days 3–4 of life and in the second week of life. These findings suggest that increased plasma VEGFA and reduced PLGF correlate with clinical severity of pulmonary vascular disease and may be associated with adverse outcome in CDH. This potential role for combined plasma VEGFA and PLGF in CDH as disease biomarkers, pathogenic mediators, and therapeutic targets merits further investigation.

Serum concentrations of cytokines in infants with retinopathy of prematurity

Retinopathy of prematurity (ROP) is the leading cause of blindness in preterm infants. In this study, we investigated the cytokine levels in cord blood of normal preterm neonates and preterm infants developed ROP. Serum levels of 10 cytokines in umbilical cord blood were measured by multiplex protein arrays from 62 healthy preterm neonates and 30 preterm neonate cases who developed ROP at later stage. Results showed that serum levels of cytokines including interleukin 7 (IL-7), monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein 1 alpha (MIP-1α), and macrophage inflammatory protein 1 beta (MIP-1β) were significantly increased in cases who developed ROP than in healthy preterm neonates (3.5-fold, 3.2-fold, 3.4-fold, and 2.1-fold, respectively), whereas levels of these four cytokines did not reveal any significant differences between healthy preterm infants and normal infants. When comparing the expression of cytokines in ROP patients with different clinical parameters, ROP cases whose gestational age at delivery earlier than 29.0 weeks demonstrated increased levels of MCP-1 and MIP-1β than those later than 29.0 weeks (p < 0.05). Also, ROP cases with birth weight less than 1.28 kg revealed significantly higher level of MIP-1β than those who were heavier than 1.28 kg (p < 0.05). These data indicated that levels of IL-7, MCP-1, MIP-1α, and MIP-1β were associated with increased risk of ROP, in which MIP-1β may be further correlated with the severity of ROP.

Early biomarkers as predictors for bronchopulmonary dysplasia in preterm infants: a systematic review

BACKGROUND

Bronchopulmonary dysplasia (BPD) is usually diagnosed in preterm infants at least 28 days after birth. Great interest lies in the potential to identify biomarkers that predict development of the disease and future neurodevelopmental outcomes. We have reviewed the existing literature on early biomarkers as predictors for BPD in preterm infants.

METHODS

Two reviewers independently searched the databases of PubMed, EMBASE, and Google Scholar for studies pertaining to biomarkers for BPD. Studies were assessed using Quality Assessment of Diagnostic Accuracy Studies criteria.

RESULTS

We identified 46 relevant articles that are summarized in the review. These studies assessed over 30 potential biomarkers. Sensitivity and specificity of biomarkers were reported or could be calculated for only 16 articles, and ranged from 0 to 100 %. Based on the nine highest quality studies, serum KL-6, CC16, neutrophil gelatinase-associated lipocalin, and end-tidal carbon monoxide (etCO) perform extremely well in predicting the early diagnosis of established BPD, highlighting these biomarkers as promising candidates for future research.

CONCLUSIONS

Published data from studies on serum biomarkers and etCO suggest that biomarkers may have great potential to predict the subsequent BPD and neurodevelopmental outcomes. These biomarkers need validation in larger studies, and the generalizability of biomarkers for predicting BPD, as well as the neurodevelopmental outcomes, needs to be further explored.

Preeclampsia and the risk of bronchopulmonary dysplasia in VLBW infants: a population based study

BACKGROUND

Preeclampsia remains a leading cause of maternal mortality and preterm delivery. Both preeclampsia and bronchopulmonary dysplasia (BPD) of prematurity are associated with impaired angiogenesis. However, the relationship between maternal preeclampsia and BPD remains controversial. This study aims to test whether or not preeclampsia is associated with development of BPD in a cohort of premature infants.

MATERIALS AND METHODS

We conducted a retrospective cohort study assessing the association between preeclampsia and the risk of developing BPD in very-low-birth-weight (VLBW) infants registered in the Premature Baby Foundation of Taiwan from 1997 through 2006. All 21 neonatal departments in Taiwan participated in the data collection. A total of 8,653 VLBW infants were registered in the database. The exclusion criteria included congenital anomalies, chromosome anomalies, infants that died before 36 weeks post-conceptual (PCA), and those whose BPD status were unavailable. BPD was defined as oxygen dependence at 36 weeks postmenstrual age. The association between maternal preeclampsia and BPD was assessed using a multivariate-adjusted logistic regression model.

RESULTS

In the end, a total of 5,753 cases were enrolled in this study. The incidence of preeclampsia was 14.7% (n=847) and the overall incidence of BPD was 34.9%. Infants with maternal preeclampsia had a higher gestational age, higher incidence of cesarean section and being small for their gestational age, lower incidence of respiratory distress syndrome, patent ductus arteriosus, and sepsis. BPD occurred significantly less frequently in the maternal preeclampsia group (24.1% vs. 36.7%; adjusted odds ratio: 0.78; 95% confidence interval, 0.62-0.98). Subgroup analysis showed that the association between preeclampsia and BPD was significant only in those VLBW infants with a gestational age between 31-34 weeks.

CONCLUSION

This data supports the association between fetal exposure to maternal preeclampsia and a reduced risk of BPD in relatively mature VLBW infants.

Biomarkers in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a complex disorder secondary to gene-environment interactions, and is the commonest chronic lung disease in infancy. There is no specific or effective treatment available to date for BPD. Since the aetiopathogenesis of BPD is multifactorial, involving diverse molecular signaling pathways, a variety of biomarkers detected in biological fluids have been proposed for early identification of infants predisposed to BPD. This review will be restricted to biomarker studies in human infants, conducted mostly in the last decade. The majority of the studies have been conducted using blood, urine or tracheal aspirate samples. Despite the multitude of biomarkers proposed, most studies have been conducted in small numbers of infants, with few being replicated by independent investigators. Confirmatory studies with adequate sample sizes and assessment of the role of putative biomarkers in the aetiology of BPD in developmentally appropriate animal models and human lungs with BPD will enhance the potential for therapeutic interventions. Genomic and proteomic approaches have the greatest potential to significantly advance the field of biomarkers in BPD.

Maternal preeclampsia predicts the development of bronchopulmonary dysplasia

OBJECTIVE

To test the hypothesis that exposure to preeclampsia is associated with an increased risk of bronchopulmonary dysplasia (BPD).

STUDY DESIGN

A prospective cohort study of 107 babies born between 23 and 32 weeks gestation, collecting maternal, neonatal, and placental data.

RESULTS

Of the 107 infants studied, 27 (25%) developed BPD. The bivariate odds ratio (OR) for the relationship between pre-eclampsia and BPD was 2.96 (95% confidence interval [CI] = 1.17 to 7.51; P = .01). When controlling for gestational age, birth weight z-score, chorioamnionitis, and other clinical confounders, the OR of developing BPD was 18.7 (95% CI = 2.44 to 144.76). Including the occurrence of preeclampsia, clinical chorioamnionitis, male sex, and maternal tobacco use in addition to gestational age and birth weight z-score accounted for 54% of the variability of the odds of developing BPD.

CONCLUSIONS

BPD is increased for infants exposed to preeclampsia. This has possible implications for the prevention of BPD with proangiogenic agents, such as vascular endothelial growth factor.

Pitfalls, problems, and progress in bronchopulmonary dysplasia

Bronchopulmonary dysplasia is a chronic lung disease associated with premature birth and characterized by early lung injury. In this review we discuss some pitfalls, problems, and progress in this condition over the last decade, focusing mainly on the last 5 years, limited to studies in human neonates. Changes in the definition, pathogenesis, genetic susceptibility, and recent biomarkers associated with bronchopulmonary dysplasia will be discussed. Progress in current management strategies, along with novel approaches/therapies, will be critically appraised. Finally, recent data on long-term pulmonary and neurodevelopmental outcomes of infants with bronchopulmonary dysplasia will be summarized.

Below median birth weight in appropriate-for-gestational-age preterm infants as a risk factor for bronchopulmonary dysplasia

AIMS

To assess the presence of chorioamnionitis and intrauterine growth as prenatal risk factors for broncho pulmonary dysplasia (BPD) in appropriate-for-gestational-age (AGA) infants of <28 weeks' gestation.

METHODS

Gender, race, birth weight, gestational age, histology of the placenta, diagnosis of BPD at 36 weeks' gestation, postnatal dexamethasone treatment, and death were recorded in 150 preterm infants born at <28 weeks' gestation, and admitted between 1996 and 2001.

RESULTS

In 122 AGA infants (mean gestational age: 26.18 weeks, mean birth weight: 837 g), BPD was associated with gestational age-related birth weights below the 50(th) centile. Intrauterine growth deceleration started between 25 and 26 weeks' gestation. Chorioamnionitis was not related to BPD.

CONCLUSIONS

AGA infants of 26-28 weeks' gestation with birth weights below the median showed an increased risk of developing BPD.

Cyclic stretch induces PlGF expression in bronchial airway epithelial cells via nitric oxide release

Mechanical strain of lung tissue is an important stimulus for the production of growth factors that are critical for lung growth and development. However, excessive mechanical strain, as may occur during mechanical ventilation, may produce an increase in growth factors that may contribute to lung injury. We hypothesized that mechanical strain of primary bronchial airway epithelial cells (BAEpCs) induced the production of placental growth factor (PlGF), a member of the VEGF family. BAEpCs were cultured on a deformable silicoelastic membrane and exposed to different magnitudes of stretch. Stretch induced PlGF and nitric oxide (NO) production that increased with increasing magnitude of stretch. Stretch also induced PlGF and inducible NO synthase ( iNOS) gene expression. The stretch-induced PlGF production and NO synthesis were attenuated by PD98059, a specific mitogen-activated protein kinase kinase-1 and -2 inhibitor. Inhibition of NO generation by l-NAME or l-NMMA or scavenging NO by carboxy-PTIO prevented stretch-mediated erk1/2 activation. In addition, in unstretched BAEpCs, exogenous NO enhanced erk1/erk2 activation. Our data suggest that mechanical stretch of BAEpCs induces iNOS expression and induces PlGF release in an erk1/2 activation-dependent manner.

Nonassociation of Interleukin 4 Intron 3 and 590 Promoter Polymorphisms with Bronchopulmonary Dysplasia for Ventilated Preterm Infants

Interleukin 4 (IL-4) stimulates and amplifies the inflammatory response, stimulates collagen synthesis in fibroblasts, promotes the progression to fibrosis and has been shown to inhibit the production of several inflammatory cytokines in the development of bronchopulmonary dysplasia (BPD) and airway hyperreactivity. We aimed to investigate whether IL-4 polymorphisms in ventilated preterm infants were associated with BPD. BPD was defined as infants who remained dependent on active respiratory support or oxygen supplementation at 36 weeks postconceptional age. A case-control study of 224 preterm infants (<30 weeks) who had respiratory distress syndrome and needed intermittent mandatory ventilation (IMV) were undertaken between January 1999 and December 2003. The typing of each genetic polymorphism was performed by polymerase-chain-reaction-based restriction analysis. Genotype distribution and allelic frequencies were compared between ventilated preterm infants who developed BPD and those who did not and the duration of IMV. The demography of these ventilated BPD and non-BPD preterm infants was not different. We observed no significant differences in genotype distribution or allelic frequency of the IL-4 intron 3 or IL-4 promoter polymorphisms between ventilated preterm infants who developed BPD and who did not. There was no significant association of the genotype or allelic frequency of IL-4 polymorphism with duration of IMV. We conclude that neither IL-4 intron 3 nor the 590 promoter polymorphism is a useful marker for predicting the susceptibility to BPD in ventilated Taiwanese preterm infants.