Prenatal diagnosis of pulmonary hypoplasia

Outcomes of fetal lower urinary tract obstruction based on timing of oligohydramnios onset

OBJECTIVE

Fetal Lower Urinary Tract Obstruction (LUTO) is associated with oligohydramnios and significant fetal morbidity, resulting in poor lung development and perinatal death. However, oligohydramnios may develop at different gestational periods, and the impact of timing on fetal outcomes remains unknown. Our objective was to characterize the impact onset of oligohydramnios had on prenatal outcomes.

METHODS

This study is a retrospective cohort study of all patients with a prenatal diagnosis of LUTO at our tertiary referral center from 2014 to 2023. All patients underwent detailed ultrasonography and interdisciplinary counseling and were subsequently delivered at our institution. Data were obtained from electronic medical records and complete extraction was required for final inclusion.

RESULTS

During the study time period, 93 patients met inclusion criteria of which 68 (73.1%) developed oligohydramnios during their pregnancy. 63 (93%) of these pregnancies resulted in livebirths with 28 (41.1%) perinatal deaths. Onset of oligohydramnios was earlier in pregnancies with perinatal death (23 vs. 28 weeks, p = 0.004) and associated with pulmonary hypoplasia.

CONCLUSIONS

Our data show the impact of oligohydramnios timing in pregnancy on pulmonary hypoplasia and ultimately perinatal death. This allows for detailed patient counseling on the impact oligohydramnios may have on pregnancies by the gestational age of onset.

Use of Virtual Touch Tissue Quantification Elastography Technique in Fetal Lung Maturation: A Preliminary Study

ABSTRACT

This study is an analysis of fetal lung stiffness by virtual touch tissue quantification (VTTQ) elastography to predict fetal lung maturation. Evaluation of fetal lungs was first performed in B mode, and fetal lungs were analyzed at 3 different periods at third trimester in each pregnant woman, at 28 to 31, 32 to 36, and 37 to 41 weeks. Fetal lung elastography was performed at regions with the least acoustic shadow and far from ribs and heart. Each fetal lung assessment were done by taking mean lung stiffness obtained by measuring stiffness of both left and right fetal lungs. T test analysis showed no significant difference in fetal lung stiffness between male and female fetuses among 3 gestational periods. Analysis of variance was performed to evaluate fetal lung stiffness of the fetuses at 3 different gestational periods (28-31, 32-36, and 37-41 weeks). This analysis showed significant difference ( P < 0.01). Duncan multiple comparison analysis did not show significant difference in fetal lung stiffness between 28 and 31 weeks and 32 and 36 weeks, whereas fetal lung stiffness of fetuses at 37 to 41 weeks were significantly greater ( P < 0.01). This study is first step to analyze fetal lung maturation noninvasively using VTTQ elastography technique by measuring fetal lung stiffness.

Prenatal screening and diagnosis of pulmonary artery anomalies

Congenital pulmonary artery anomalies are rare. Their antenatal diagnosis requires good knowledge of fetal cardiac anatomy because their clinical presentation varies depending on the type and severity of the underlying lesion. Screening of these vascular anomalies can be straightforward in some cases because of significant associated consequences that are detected easily on ultrasound, while other anomalies have considerably less obvious features. There may be an associated genetic syndrome. The aim of this review was to define anomalies of the main pulmonary artery and its branches and to propose, through the identification of suspicious findings during routine antenatal heart examination, an optimal screening method for the pulmonary artery pathway. We propose that pulmonary artery anomalies can be classified antenatally into four types of disorder. Herein we describe 14 cases subgrouped accordingly as: anomalies of the pulmonary valvular region, with stenosis or atresia of the valve (n = 4); conotruncal abnormalities (n = 4); anomalies associated with abnormal origin or course of the pulmonary artery (n = 4); and anomalies associated with abnormal growth of the pulmonary artery and its branches (n = 2). We highlight the need to differentiate the three-vessel view from the three-vessel-and-trachea view when assessing a fetus with a congenital pulmonary artery anomaly. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Mediastinal shift angle (MSA) measurement with MRI: a simple and effective tool for prenatal risk stratification in fetuses with congenital diaphragmatic hernia

OBJECTIVES

To investigate the predictive value of mediastinal shift angle (MSA) in congenital diaphragmatic hernia (CDH).

METHODS

A retrospective analysis was performed on 87 fetuses with prenatally diagnosed left-sided CDH (LCDH) and 88 controls. MSA was measured on magnetic resonance imaging (MRI). Lung area to head circumference ratio (LHR), ratio of the observed/expected LHR (O/E LHR), total fetal lung volume (TFLV), and observed/expected total fetal lung volume (O/E TFLV) were also measured. Correlation of MSA with pulmonary hypertension (PH), extracorporeal membrane oxygenation (ECMO) use, duration of hospitalization and survival in neonates with CDH was analyzed. Performance of MSA in prediction of postnatal outcomes was compared with LHR, O/E LHR, TFLV, and O/E TFLV.

RESULTS

There were significant differences in MSA values not only between the CDH group and the control group but also in CDH patients with different survival outcomes. MSA was inversely correlated with O/E LHR, O/E TFLV, and TFLV. MSA, LHR, O/E LHR, TFLV, and O/E TFLV could all be used to predict survival of CDH patients. In addition, the receiver operating characteristic (ROC) curve showed that the test performance of MSA was similar to that of TFLV, O/E TFLV, and O/E LHR, but superior to that of LHR. MSA was also correlated with PH, need for ECMO support, and duration of hospitalization.

CONCLUSION

MRI measurement of MSA can provide various prognostic information for prenatally diagnosed LCDH, in addition to postnatal survival. The test performance of MSA is similar to TFLV, O/E TFLV, and O/E LHR.

KEY POINTS

• Mediastinal shift angle (MSA) can be measured quickly and reproducibly on MRI images. • MSA could provide more prognostic information other than postnatal survival for LCDH with good test performance. • MSA should be incorporated into prenatal risk stratification for LCDH to improve planning of postnatal management.

Management of the CDH patient on ECLS

Congenital diaphragmatic hernia (CDH) is the most common indication for respiratory extracorporeal life support (ECLS) in neonates. The survival rate of CDH neonates treated with ECLS is 50%, and this figure has remained relatively stable over the last few decades. This is likely because the current population of CDH neonates who require ECLS have a higher risk profile [1]. The management of neonates with CDH has evolved over time to emphasize postnatal stabilization, gentle ventilation, and multi-modal treatment of pulmonary hypertension. In order to minimize practice variation, many centers have adopted CDH-specific clinical practice guidelines, however care is not standardized between different centers and outcomes vary [3]. The purpose of this review is to summarize our current understanding of issues central to the care of neonates with CDH treated with ECLS and specifically highlight how the use of the Extracorporeal Life Support Organization (ELSO) data have added to our understanding of CDH.

Enteral nutrition support for infants with pulmonary hypoplasia: A qualitative evaluation of caregiver and provider perspectives

BACKGROUND

Enteral nutrition is a critical intervention that supports the growth of children with pulmonary hypoplasia (PH). We explored the experiences of caregivers and providers caring for children with PH to better understand gaps in knowledge transfer and identify barriers and facilitators to caregiving to inform interventions that may improve support.

METHODS

This qualitative study included 10 interviews with caregivers and 10 clinical team members at a single integrated care program for children with PH. An inductive and iterative coding strategy was employed to produce a codebook. After cluster analysis, themes were generated to capture participant sentiments.

RESULTS

Themes were defined along a care continuum (1) initiation, (2) adaptation, and (3) maintenance that represented distinct phases of adjustment to enteral nutrition support (1) in the perinatal period and initial neonatal intensive care unit (NICU) admission, (2) from discharge planning through the family's first days at home and establishment of a stable feeding regime, and (3) through long-term follow-up and weaning. Notable subthemes included uncertainty, partnerships in training, and obstacles to adaptation.

CONCLUSIONS

Among children with PH, the caregiver-provider relationship during the perinatal and NICU course is critical to promoting caregiver adaptation to the needs of the child. Ongoing considerations to support resource alignment and transition to a stable feeding regimen may facilitate caregiver adjustment to a "new normal," culminating in successful growth and/or weaning. These findings will inform interventions focused on training curricula, discharge planning, and the provision of follow-up in the context of an integrated care program for PH.

Fetal Lung Echo Texture in Pregnancies at Risk for Pulmonary Hypoplasia

Pulmonary hypoplasia is associated with severe respiratory distress immediately after birth and frequently leads to neonatal death. In this study, we compared the fetal lung echo texture in pregnancies at high and low risk for pulmonary hypoplasia. Ultrasonic tissue heterogeneity was determined by a dynamic range calculation. This quantification uses a dithering technique based on the Floyd-Steinberg algorithm, in which the pixels are transformed into a binary map. Pregnancies at high risk for pulmonary hypoplasia showed decreased fetal lung heterogeneity on ultrasound imaging. This image-processing technique may allow improved risk stratification, patient counseling, and treatment approaches for pulmonary hypoplasia.

Assessment of BOLD response in the fetal lung

OBJECTIVE

Assessment of lung development and maturity is of utmost importance in prenatal counseling. Blood oxygen level-dependent (BOLD) effect MRI was developed for functional evaluations of organs. To date, no data are available in fetal lungs and nothing is known about the existence of a BOLD effect in the lungs. The aim of our study was to evaluate if a BOLD response could be detected in fetal lungs.

MATERIALS AND METHODS

From January 2014 to December 2016, 38 healthy pregnant women were prospectively enrolled. After a routine scan on a 1.5-T MRI device (normoxic period), maternal hyperoxia was induced for 5 min before the BOLD sequence (hyperoxic period). R2* was evaluated by fitting average intensity of the signal, both for normoxic (norm) and hyperoxic (hyper) periods.

RESULTS

A significant BOLD response was observed after maternal hyperoxia in the lungs with a mean R2* decrease of 12.1 ± 2.5% (p < 0.001), in line with the placenta response with a mean R2* decrease of 19.2 ± 5.9% (p < 0.0001), confirming appropriate oxygen uptake. Conversely, no significant BOLD effect was observed for the brain nor the liver with a mean ∆R2* of 3.6 ± 3.1% (p = 0.64) and 2.8 ± 3.7% (p = 0.23).

CONCLUSION

This study shows for the first time in human that a BOLD response can be observed in the normal fetal lung despite its prenatal "non-functional status." If confirmed in congenital lung and chest malformations, this property could be used in addition to the lung volume for a better prediction of postnatal respiratory status.

KEY POINTS

• Blood oxygen level-dependent (BOLD) effect MRI was developed for functional evaluations of organs and could have interesting implications for the fetal organs. • Assessment of lung development is of utmost importance in prenatal counseling, but to date no data are available in fetal lungs. • BOLD response can be observed in the normal fetal lung opening the way to studies on fetus with pathological lungs.

Fetal, neonatal, and infant death in central China (Hubei): A 16-year retrospective study of forensic autopsy cases

Data based on forensic autopsy in neonates and infants in China are rare in the literature. The purpose of this study is to evaluate the characteristics of fetal, neonatal, and infant death and to determine the main cause of death among them.A retrospective analysis of fetal and infant forensic autopsies referred to the Tongji Forensic Medical Center (TFMC) in Hubei, central China, during a 16-year period between January 1999 and December 2014, was performed.In this period, there were 1111 males and 543 females; the total male-to-female ratio (MFR) was 2.05:1. There were 173 fetal and infant autopsies conducted, comprised of 43 fetal, 84 neonatal (<28 days) and 46 infant (4 weeks to 1 year) cases. The annual case number ranged from 5 in 2004 to 18 in 2014 (annual mean of 10.8). MFR was 1.75:1. About 94% of these deaths (163/173) resulted from natural causes, 6 cases (3.5%) were accidental deaths, and 4 (2.3%) resulted from homicide (4 abandoned babies). Among fetuses, the most common causes of death were placental and umbilical cord pathologies (28%, 12/43), followed by intrapartum asphyxia resulting from amniotic fluid aspiration (AFA) or meconium aspiration syndrome (MAS) (18.6%, 8/43), congenital malformation (14%, 6/43), and intrapartum infection (9.3%, 4/43). A majority of neonatal deaths (66.7%, 56/84) died within 24 hours of birth. The main causes of neonatal death were asphyxia resulting from AFA, MAS, or hyaline membrane disease, and congenital malformation. The main causes of infant (1-12 months) death were infectious diseases, including pneumonia, meningitis, and viral brainstem encephalitis.This study was the 1st retrospective analysis of autopsies of fetal, neonatal, and infant death in TFMC and central China. We delineate the common causes of early demise among cases referred for autopsy, and report a male preponderance in this population. Our data observed that placental and/or umbilical cord pathology, asphyxia due to AFA, and/or MAS, and pneumonia were the leading causes of fetal, neonatal, and infant death, respectively. And it can inform clinical practitioners about the underlying causes of some of the most distressing cases in their practices.

Fetal primary pleural effusions: Prenatal diagnosis and management

Fetal pleural effusions can be associated with significant perinatal morbidity and mortality. When diagnosed antenatally, referral to a tertiary fetal medicine center is recommended for a detailed ultrasound evaluation for additional structural abnormalities or features suggestive of congenital infections or fetal anemia. The effusions should be characterized as unilateral or bilateral, and presence of hydrops and/or mediastinal shift should be documented. Additional testing should include fetal echocardiography, maternal testing for blood group and screen, hemoglobinopathies, and congenital infections. Invasive genetic testing is recommended with infectious testing on amniotic or pleural fluid. Pleuroamniotic shunting is recommended for large primary pleural effusions with significant mediastinal shift or hydrops, as several large series have demonstrated improvement in perinatal survival, particularly in hydropic fetuses. Delivery should occur in a tertiary care center with neonatal expertise, and infants should be followed up long-term for respiratory and neurodevelopmental outcomes.

Quantitative Ultrasound Texture Analysis for Differentiating Preterm From Term Fetal Lungs

OBJECTIVES

To differentiate preterm (<37 weeks' gestation) from term (≥37 weeks' gestation) fetal lungs by using quantitative texture analysis of ultrasound images.

METHODS

This study retrospectively evaluated singleton gestations with valid dating at 20 weeks' gestational age (GA) or later between January 2015 and December 2015. Images were obtained from Voluson E8 ultrasound systems (GE Healthcare, Milwaukee, WI). A region of interest was selected in each fetal lung image at the level of the 4 heart chambers from an area that appeared most representative of the overall lung tissue and had the least shadow. Ultrasonic tissue heterogeneity (heterogeneity index) based on dynamic range calculation was determined for all lung images. This quantification was performed with a custom-made software program that used a dithering technique based on the Floyd-Steinberg algorithm, in which the pixels are transformed into a binary map. Regression analysis was used to determine the correlation and functional association between the heterogeneity index and GA. A receiver operating characteristic curve was used to identify the optimal heterogeneity index cutoff point for differentiating preterm from term fetal lungs.

RESULTS

A total of 425 fetal lung ultrasound images (313 preterm and 112 term) were analyzed. Quantitative texture analysis predicted GA with sensitivity and specificity of 87.9% and 92.0%, respectively, based on the optimal receiver operating characteristic cutoff point.

CONCLUSIONS

Quantitative ultrasound texture analysis of fetal lung tissue can differentiate preterm fetal lungs from term fetal lungs. Our data suggest that decreased fetal lung heterogeneity on ultrasound imaging is associated with preterm fetuses.

Predicting outcomes in congenital diaphragmatic hernia

Identification of CDH infant populations at high risk for mortality postnatally may help to develop targeted care strategies, guide discussions surrounding palliation and contribute to standardizing reporting and benchmarking, so that care strategies at different centers can be compared. Clinical prediction rules are evidence-based tools that combine multiple predictors to estimate the probability that a particular outcome in an individual patient will occur. In CDH, a suitable clinical prediction rule can stratify high- and low-risk populations and provide the ability to tailor management strategies based on severity. The ideal prediction tool for infants born with CDH would be validated in a large population, generalizable, easily applied in a clinical setting and would clearly discriminate patients at the highest and lowest risk of death. To date, 4 postnatal major clinical prediction rules have been published and validated in the North American CDH population. These models contain variables such as birth weight, Apgar score, blood gases, as well as measures of pulmonary hypertension, and associated anomalies. In an era of standardized care plans and population-based strategies, the appropriate selection and application of a generalizable tool to provide an opportunity for benchmarking, policy creation, and centralizing the care of high-risk populations. A well-designed clinical prediction tool remains the most practical and expedient way to achieve these goals.

Evaluating skeletal dysplasias on prenatal ultrasound: an emphasis on predicting lethality

Lethal skeletal dysplasias can be diagnosed by prenatal ultrasound (US) using several sonographic parameters. Degree of femoral shortening, lung volumes, femur length to abdominal circumference ratio, and chest circumference to abdominal circumference ratio are the most sensitive and specific predictors. Although there are more than 450 different skeletal dysplasias, only a few are lethal in the perinatal period. We review current fetal US literature and present an updated algorithmic approach to first establish lethality and, second, evaluate for hallmark sonographic features to help determine a specific diagnosis.

[Congenital anomalies of poor prognosis. Genetics Consensus Committee]

INTRODUCTION

The Genetic Branch of the Chilean Society of Paediatrics, given the draft Law governing the decriminalisation of abortion on three grounds, focusing on the second ground, which considers the "embryo or foetus suffering from a congenital structural anomaly or a genetic disorder incompatible with life outside the womb", met to discuss the scientific evidence according to which congenital anomalies (CA) may be included in this draft law.

METHODOLOGY

Experts in clinical genetics focused on 10 CA, reviewed the literature evidence, and met to discuss it.

RESULTS

It was agreed not to use the term "incompatible with life outside the womb", as there are exceptions and longer survivals, and change to "congenital anomaly of poor prognosis (CAPP)". Ten CA were evaluated: serious defects of neural tube closure: anencephaly, iniencephaly and craniorachischisis, pulmonary hypoplasia, acardiac foetus, ectopia cordis, non-mosaic triploidy, "limb body wall" complex, "body stalk" anomaly, trisomy 13, trisomy 18, and bilateral renal agenesis. Findings on the prevalence, natural history, prenatal diagnostic methods, survival, and reported cases of prolonged survival were analysed. Post-natal survival, existence of treatments, and outcomes, as well as natural history without intervention, were taken into account in classifying a CA as a CAPP.

CONCLUSION

A CAPP would be: anencephaly, severe pulmonary hypoplasia, acardiac foetus, cervical ectopia cordis, non-mosaic triploidy, limb body wall complex, body stalk anomaly, non-mosaic trisomy 13, non-mosaic trisomy 18, and bilateral renal agenesis. For their diagnosis, it is required that all pregnant women have access to assessments by foetal anatomy ultrasound and occasionally MRI, and cytogenetic and molecular testing.

Severe antenatally diagnosed renal disorders: background, prognosis and practical approach

Nowadays most renal disorders, especially urinary tract malformations and renal cystic disease, are diagnosed antenatally. In cases of severe bilateral disease, intrauterine renal dysfunction may lead to renal oligohydramnios (ROH), resulting in pulmonary hypoplasia which affects perinatal mortality and morbidity as well as the long-term outcome. However, some infants may only have mild pulmonary and renal disease, and advances in postnatal and dialysis treatment have resulted in improved short- and long-term outcome even in those infants with severe ROH. Here, we review the current state of knowledge and clinical experience of patients presenting antenatally with severe bilateral renal disorders and ROH. By addressing underlying mechanisms, intrauterine tools of diagnosis and treatment as well as published outcome data, we hope to improve antenatal counselling and postnatal care. KEY SUMMARY POINTS: 1. Nowadays most renal disorders are diagnosed antenatally, especially urinary tract malformations and renal cystic disease. 2. Severe kidney dysfunction may lead to renal oligohydramnios, which can cause pulmonary hypoplasia and is a risk factor of perinatal mortality and postnatal renal outcome. However, as considerable clinical heterogeneity is present, outcome predictions need to be treated with caution. 3. Advances in postnatal and dialysis treatment have resulted in improved short- and long-term outcomes even in infants with severe renal oligohydramnios. 4. A multidisciplinary approach with specialist input is required when counselling a family with an ROH-affected fetus as the decision-making process is very challenging.

Prediction of lethal pulmonary hypoplasia by means fetal lung volume in skeletal dysplasias: a three-dimensional ultrasound assessment

OBJECTIVE

The aim of this study was to assess the capacity of three-dimensional ultrasound (3DUS) for predicting lethality in fetuses with skeletal dysplasia.

METHODS

Twenty-four fetuses between 20 and 32 weeks of gestation were assessed. Bilateral lung volume scans were performed three times in each fetus during one ultrasound session. The virtual organ computer-aided analysis method was used to obtain a sequence of six sections of each lung around a fixed axis, and a rotation angle of 30° was adopted. Fetal lung volume measurements were analyzed according to the reference range. After birth, lung hypoplasia was diagnosed considering clinical and radiological criteria.

RESULTS

Of all cases of skeletal dysplasia, 18 (75%) were lethal. Among the lethal cases, after postnatal diagnosis, four were osteogenesis imperfecta type II, three were thanatophoric dysplasia and two were campomelic dysplasia. The remaining nine cases remained without a definitive diagnosis. The accuracy of 3DUS in predicting lethality in fetuses with skeletal dysplasia was high, with a sensitivity of 83.3%, specificity of 100%, positive predictive value of 100% and negative predictive value of 66.7%. The kappa index of 0.174 showed a good agreement between the possibility of lethality when the 3DUS volume measurement was altered and real lethality after birth (p < 0.001).

CONCLUSION

This study suggests that the 3DUS lung volume measurement is a good predictor of lethal pulmonary hypoplasia in fetuses with skeletal dysplasia, with high accuracy.

Neonatal outcomes of fetuses diagnosed with life-limiting conditions when individualized comfort measures are proposed

OBJECTIVE

To describe the neonatal outcomes of a case series of infants who were prenatally diagnosed with potential life-limiting conditions and to whom individualized comfort measures were offered.

STUDY DESIGN

This is a retrospective analysis of the postnatal outcomes of a selected population of 49 infants prenatally diagnosed with potential life-limiting conditions whose parents were prenatally referred for counseling to the comfort care team.

RESULT

The prenatal diagnosis was confirmed postnatally in 45 infants. The only four survivors had a significant discrepancy between prenatal and postnatal diagnosis. Whether they were treated with individualized comfort measures (n=28) or intensive care (n=17), all the newborns died with similar median age at death (2 days).

CONCLUSION

Diagnostic accuracy is the main determinant of outcomes. Provision of intensive care neither prevents the death of infants affected by life-limiting conditions nor prolongs life compared with that of infants treated with individualized comfort measures.

Economical Analysis of Different Clinical Approaches in Pre-Viability Amniorrhexis-A Case Series

Prolonged oligohydramnios following extreme preterm prelabour rupture of membranes (EPPROM) is traditionally associated with a high morbidity and mortality to both the mother and the baby. The clinical maternal evaluation and fetal ultrasound assessment may provide important prognostic information for the clinicians and should be taken into account when counselling the patients so as to provide them with enough information to make decision of continuing or interrupting the pregnancy. Current financial constraints on the National Healthcare Service (NHS) resources make it imperative for clinical decision-makers and budgetary planners to make the right decision of continuing or terminating a second trimester pre-viability amniorrhexis for desperate parents. To assess the economic consequences following EPPROM, the risk of infection to both baby and mother, psychological impact on the parents and associated complications and further disability after delivery on this fragile group of patients to the NHS resources. We review the clinical course, outcome, and the challenges to parents and health care professionals on three pregnancies complicated by EPPROM, occurring before 24 weeks’ gestation with a membrane rupture to delivery interval (latent period) of 14 days or more. The anticipated birth of an extremely premature infant poses many challenges for parents and health care professionals. As parents are faced with difficult decisions that can have a long-term impact on the infant, family and country’s resources, it is critical to provide the type of information and support that is needed by them. Taking all these into consideration with the period of ventilation and respiratory assistance in Neonatal Intensive Care Unit (NICU) is essential to provide maximum chances for survival, minimizing the risk for long term sequelae of the neonate and provides the parents enough time to decide on making the right decision with the associated guidance of the healthcare provider.

Expression of Sproutys and SPREDs is decreased during lung branching morphogenesis in nitrofen-induced pulmonary hypoplasia

PURPOSE

Pulmonary hypoplasia (PH) is a life-threatening condition associated with congenital diaphragmatic hernia (CDH), characterized by defective lung development. Sproutys and Sprouty-related proteins (SPREDs) play a key role in lung branching morphogenesis through modification of epithelial-mesenchymal interactions. During the pseudoglandular stage, Sproutys are highly expressed in distal airway epithelium, while SPREDs within the surrounding mesenchyme. Sprouty2/4 knockouts show severe defects in branching morphogenesis with reduced number of distal airways. SPRED-1 and SPRED-2 are strongly expressed in regions of new airway formation, highlighting their important function in branching pattern. We hypothesized that expression of Sprouty2, Sprouty4, SPRED-1 and SPRED-2 is decreased during lung branching morphogenesis in nitrofen-induced PH.

METHODS

Timed-pregnant rats received either nitrofen or vehicle on E9.5. On E15.5 (n = 16), fetal lungs were micro-dissected and divided into controls and PH, while on E18.5 (n = 24) groups were: control, PH without CDH [CDH(-)], and PH with CDH [CDH(+)]. Pulmonary gene expression levels of Sprouty2, Sprouty4, SPRED-1 and SPRED-2 were analyzed by qRT-PCR. Immunohistochemistry was performed to evaluate protein expression/distribution.

RESULTS

On E18.5, relative mRNA expression levels of Sprouty2, Sprouty4, SPRED-1 and SPRED-2 were significantly decreased in CDH(-) and CDH(+) groups compared to controls (P < 0.05). Immunoreactivity of Sprouty2, Sprouty4, SPRED-1 and SPRED-2 was markedly diminished on E18.5 in nitrofen-induced PH.

CONCLUSION

Decreased expression of Sproutys and SPREDs during the terminal pseudoglandular stage may disrupt lung branching morphogenesis by interfering with epithelial-mesenchymal interactions contributing to PH.