Nitrofen-induced Congenital Diaphragmatic Hernia Research Articles

Downregulation of FGFRL1 Contributes to the Development of the Diaphragmatic Defect in the Nitrofen Model of Congenital Diaphragmatic Hernia

The nitrofen model of Congenital Diaphragmatic Hernia (CDH) displays a diaphragmatic defect of the Bochdalek-type and has been widely used to investigate the pathogenesis of CDH. However, the exact pathomechanism of the diaphragmatic defect is still poorly understood. Fibroblast growth factor (FGF) receptor-like 1 (FGFRL1), a member of the FGF receptor family, plays a key role in physiological diaphragmatic development. FGFRL1 is expressed in the fetal diaphragm at low levels in early gestation and its expression steadily increases, becoming most pronounced in later gestational stages. It has been reported that FGFRL1 homozygous null mice have thin, partially amuscular diaphragms and die at birth due to respiratory failure. The aim of this study was to investigate the hypothesis that FGFRL1 gene expression in the diaphragm is downregulated during the later gestational stages in the nitrofen CDH model. Timed pregnant rats were exposed to either olive oil or 100 mg nitrofen on day 9 of gestation (D9). Cesarean section was performed on D18 or D21. Fetal diaphragms (n=40) were micro-dissected and divided into CDH group and controls. Total RNA was extracted from the diaphragms and the mRNA levels of FGFRL1 were determined using real-time PCR. Immunohistochemistry was performed to evaluate diaphragmatic protein expression of FGFRL1. Student's t-test and Mann-Whitney test were used, where appropriate. Statistical significance was considered for p<0.05. Relative mRNA expression levels of FGFRL1 were significantly decreased in the CDH group compared to controls on D18 (3.63 ± 1.65 vs. 6.04 ± 3.12, p<0.05) and D21 (1.36 ± 1.01 vs. 2.57 ± 1.34, p<0.05). Immunoreactivity of FGFRL1 was markedly decreased in the diaphragms of the CDH group compared to controls on D18 and D21. Our data provide strong evidence that downregulation of the FGFRL1 gene during the late stages of gestation may contribute to the development of the diaphragmatic defect in nitrofen-induced CDH.

IGFBP-4 Gene Overexpression in the Nitrofen-Induced Hypoplastic Lung

The precise mechanism of pulmonary hypoplasia (HP) associated with congenital diaphragmatic hernia (CDH) remains unclear. Insulin-like growth factors (IGFs) play an essential role in fetal lung development through IGF receptors (IGFRs) by regulating cellular proliferation, differentiation and survival. It has been reported that the expression of genes involved in IGF-IGFR signaling is altered in the nitrofen-induced hypoplastic lung during the later stages of lung development. IGF-binding proteins (IGFBPs) control bioavailability, activity and disruption of IGFs through the high affinity IGFBP/IGF complexes. IGFBP-4 is a key inhibitor of IGF-IGFR signaling-mediated cell proliferation. It has been revealed that cell proliferation in fetal lung fibroblasts is inhibited by increased IGFBP-4 production. We hypothesized that IGFBP-4 gene expression is increased during the later stages of lung development in the nitrofen-induced CDH lung. Pregnant Sprague-Dawley rats were exposed to either olive oil or nitrofen on day 9 (D9) of gestation. Fetuses were harvested by cesarean section on D18 and D21. Fetal lungs were divided into 3 groups: control, nitrofen without CDH [CDH(-)] and nitrofen with CDH [CDH(+)] (n=24 at each time point). Relative mRNA levels of IGFBP-4 were determined using real-time RT-PCR. Immunohistochemistry was performed to evaluate the protein expression of IGFBP-4. The relative expression levels of IGFBP-4 mRNA were significantly increased in CDH(-) and CDH(+) groups on D18 and D21 compared to controls. Immunohistochemistry showed increased IGFBP-4 expression in mesenchymal compartments on D18 and D21 in hypoplastic lungs compared to controls. Overexpression of pulmonary IGFBP-4 during the later stages of lung development may contribute to pulmonary hypoplasia in the nitrofen-induced CDH model by inhibiting IGF-mediated cell proliferation.

Effect of ambroxol on lung development of rat models with nitrofen-induced congenital diaphragmatic hernia

To investigate the effects of ambroxol on rat models with nitrofen-induced congenital diaphragmatic hernia (CDH) and its potential mechanism. Nine pregnant female SD rats were randomly divided into 3 groups at Day 9.5: 2 ml olive oil intragastrically in control group (2 rats) and 200 mg nitrofen in nitrofen (2 rats) and ambroxol groups (5 rats). Antenatal ambroxol was given intraperitoneally to ambroxol group at Days 18.5, 19.5 and 20.5 of gestation while control and nitrofen groups only received intraperitoneal normal saline. At Day 21.5 the fetuses were delivered by cesarean section. Incidence of hernia, lung weight/body weight (LW/BW), mean terminal branch density (MTBD), percentage of lung alveolar area (PLAA), percentage of wall thickness (MT%) and the expression of TGF-β1 were observed. There were 19 CDH fetuses in nitrofen group (68.4%). The incidence of hernia in ambroxol group was 65.1% (28/43). There was no significant difference (P>0.05) between two groups. LW/BW and PLAA decreased while MTBD and MT% increased significantly in the nitrofen group versus the control group [(45±6) mg/g vs (60±7) mg/g, (50.1±4.0)% vs (58.4±3.0)%, (14.0±1.8) vs (8.5±1.1), (45±6)% vs (29±6)%, all P=0.001]. After ambroxol intervention, the ambroxol group showed a higher PLAA but a lower MTBD and MT% [(54.0±2.0)%, (12.2±2.1), (39±4)%] than those in the nitrofen group (P=0.001, 0.006, 0.002). The expression of TGF-β1 in pulmonary tissues of the nitrofen group was significantly higher than that in the control group (13,594±3113 vs 9447±1355, P=0.001). It decreased after ambroxol intervention (10 015±818, P=0.01). Though with no effect upon the occurrence of CDH in rats, the administration of ambroxol may improve the pulmonary maturity. The down-regulated expression of TGF-β1 and the oxidative stability are possible mechanisms.

Insulinlike growth factor receptor type 1 and type 2 are downregulated in the nitrofen-induced hypoplastic lung

Purpose In congenital diaphragmatic hernia (CDH), high mortality rates are attributed to severe pulmonary hypoplasia. The insulinlike growth factor receptor type 1 (IGF-1R) and type 2 (IGF-2R) play a critical role in the alveologenesis during lung development. The IGF-1R null mutation mice die after birth because of respiratory failure. The IGF-2R knockout mice showed retarded lungs with poorly formed alveoli. We hypothesized that IGF-1R and IGF-2R gene expression levels are downregulated in the nitrofen-induced CDH model. Methods Pregnant rats were exposed to either olive oil or 100 mg of nitrofen on day 9.5 (D9.5) of gestation. Fetuses were harvested on D18 and D21 and divided into control and nitrofen groups. Relative messenger RNA (mRNA) levels of IGF-1R and IGF-2R were determined using real time reverse transcription polymerase chain reaction. Immunohistochemistry was performed to determine protein expression. Results Relative levels of IGF-1R mRNA were significantly decreased in the nitrofen group (2.91 ± 0.81) on D21 compared to controls (5.29 ± 2.59) ( P < .05). Expression levels of IGF-2R mRNA on D21 were also significantly decreased in nitrofen group (1.76 ± 0.49) compared to controls (3.59 ± 2.45) ( P < .05). Immunohistochemistry performed on D21 showed decreased IGF-1R and also IGF-2R expression in nitrofen group. Conclusion Downregulation of IGF-1R and IGF-2R gene expression may interfere with normal alveologenesis causing pulmonary hypoplasia in the nitrofen-induced CDH model.

Insulin receptor is downregulated in the nitrofen-induced hypoplastic lung

Purpose The pathogenesis of pulmonary hypoplasia in congenital diaphragmatic hernia (CDH) is still poorly understood. During fetal lung development, the insulin receptor (IR) plays an important role by mediating the cellular uptake of glucose, which is a major substrate for the biosynthesis of surfactant phospholipids. In fetal rat lung, IR gene expression has been revealed on type II pneumocytes. Recent studies have demonstrated that downregulation of pulmonary IR in late gestation causes pulmonary hypoplasia by inhibition of surfactant synthesis. We hypothesized that pulmonary gene expression of IR is downregulated during the late stages of lung development in the nitrofen-induced CDH model. Methods Timed pregnant Sprague-Dawley rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Cesarean deliveries were performed on D15, D18, and D21. Fetal lungs were divided into 3 groups: control, nitrofen without CDH (CDH[−]), and nitrofen with CDH (CDH[+]) (n = 8 at each time-point, respectively). Relative messenger RNA (mRNA) levels of IR were determined by using real time reverse transcription polymerase chain reaction. Immunohistochemistry was performed to evaluate protein expression of IR. Results Relative expression levels of IR mRNA on D21 were significantly decreased in CDH(−) and CDH(+) group (3.99 ± 1.50 and 5.14 ± 0.99, respectively) compared to control (7.45 ± 3.95; P < .05). Immunohistochemistry showed decreased IR expression in the proximal alveolar epithelium on D21 in hypoplastic lungs compared to control lungs. Conclusion Downregulation of IR gene and protein expression in hypoplastic lung during late stages of lung development may interfere with normal surfactant synthesis, causing pulmonary hypoplasia in the nitrofen-induced CDH model.

Expression and function of phosphodiesterases in nitrofen‐induced congenital diaphragmatic hernia in rats

Congenital diaphragmatic hernia (CDH) is an anomaly associated with pulmonary hypoplasia and pulmonary hypertension (PH). The limited efficacy of current approaches to treat PH in CDH, including inhaled nitric oxide (NO), drives the search for other therapies. Phosphodiesterases (PDEs) degrade cyclic nucleotide second messenger cAMP and cGMP downstream of NO thereby limiting the vasodilatory response to NO. To identify therapeutic targets by cataloguing the expression and function of PDE isoforms in the pulmonary vasculature in nitrofen-induced CDH in fetal rats. Quantitative RT-PCR revealed PDE1-5 and PDE9 mRNA expression in pulmonary arteries (PAs) of control and nitrofen-induced CDH term fetal rats. In this order of potency, the PDE inhibitors Sildenafil (PDE5) > EHNA (PDE2) > Rolipram (PDE4) > Cilostamide (PDE3) all dilated isolated third generation PA after pre-constriction with the thromboxane analog U46619. Hyperoxic pre-incubation of PAs significantly attenuated vasodilatation induced by the PDE5 inhibitor Sildenafil (65% vs. 33%, P < 0.004). CDH PAs dilated significantly less to PDE2 inhibitor EHNA compared to control (51% vs. 72%, P < 0.05). Subsequently PDE2 protein expression was higher in PAs of CDH animals. Most PDE isoforms exist in the PAs of fetal rats and their inhibition causes pulmonary vasodilatation. PDE5 inhibition was the most potent vasodilator, however, there were no differences between groups. PDE5-induced vasodilatation was attenuated by hyperoxic pre-incubation. PDE inhibitors might be considered therapeutic targets in combination with iNO in neonates with CDH.

Up-regulation of Wnt5a gene expression in the nitrofen-induced hypoplastic lung

Purpose The pathogenesis of pulmonary hypoplasia in nitrofen-induced congenital diaphragmatic hernia (CDH) still remains unclear. Wnt signaling pathways play a critical role in lung development. Whereas canonical Wnt signaling regulates branching morphogenesis during early lung development, the noncanonical Wnt5a controls late lung morphogenesis, including patterning of distal airway and vascular tubulogenesis (alveolarization). Overexpression of Wnt5a in transgenic mice and in the chick has been reported to result in severe pulmonary hypoplasia. We designed this study to test the hypothesis that the pulmonary Wnt5a gene expression is up-regulated in late stages of lung morphogenesis in CDH. Methods Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Fetal lungs were harvested on D15, D18, and D21 and divided into 3 groups: control; nitrofen without CDH, CDH(−); and nitrofen with CDH, CDH(+) (n = 8 at each time-point, respectively). Wnt5a pulmonary gene expression was analyzed by real-time reverse transcription polymerase chain reaction. Immunohistochemistry was performed to evaluate Wnt5a protein expression at each time-point. Results Pulmonary relative mRNA expression levels of Wnt5a were significantly increased in CDH(−) and CDH(+) at D18 (1.61 ± 0.92 and 1.81 ± 1.20, respectively) and D21 (2.40 ± 0.74* and 2.65 ± 0.35*, respectively) compared to controls at D18 and D21 (0.90 ± 0.17* and 1.69 ± 0.53**, respectively) (* P < .05, ** P < .001 vs control ). Strong Wnt5a immunoreactivity was seen in the distal epithelium at D18 and D21 in nitrofen-induced hypoplastic lung compared to controls. Conclusion Up-regulation of pulmonary Wnt5a gene expression in the late lung morphogenesis may interfere with patterning of alveolarization, causing pulmonary hypoplasia in the nitrofen-induced CDH.

Upregulation of Slit-2 and Slit-3 gene expressions in the nitrofen-induced hypoplastic lung

Purpose The pathogenesis of pulmonary hypoplasia in the nitrofen-induced congenital diaphragmatic hernia (CDH) is not clearly understood. Slit-2 and Slit-3 are expressed in fetal lung and play a key role in directing the functional organization and differentiation of lung mesenchyme during branching morphogenesis. We hypothesized that the pulmonary gene expression levels of Slit genes are altered in the nitrofen-induced CDH. Materials and Methods Pregnant rats were exposed to either olive oil or nitrofen on day 9 of gestation (D9). Fetal lungs were harvested on D15 and D21 and divided into 2 groups as follows: CDH (n = 9 at each time-point) and control (n = 9 at each time-point). The pulmonary gene expression levels of Slit-2, Slit-3, Robo1, and Robo2 were analyzed by real time reverse transcription polymerase chain reaction. Student's t test or Mann-Whitney U test was used for statistical analysis. Results Relative messenger RNA expression levels of Slit-2 and Slit-3 were significantly increased in CDH lungs compared to control at both D15 and D21 ( P < .05). However, there were no significant differences between CDH and controls in the pulmonary gene expression levels of Robo1 and Robo2 at each time-point. Conclusion Our results provide evidence, for the first time, that Slit genes are upregulated in nitrofen-induced hypoplastic lungs in both early and late stages of lung development. Altered pulmonary Slit gene expression may disrupt branching lung morphogenesis resulting in pulmonary hypoplasia.

Downregulation of insulin-like growth factor binding protein 3 and 5 in nitrofen-induced pulmonary hypoplasia

The high mortality in congenital diaphragmatic hernia (CDH) is mainly attributed to pulmonary hypoplasia. Recent studies suggest that retinoid signaling pathway (RSP) is inhibited in the nitrofen-induced hypoplastic lung. The insulin-like growth factor (IGF) system plays a crucial role in fetal lung development by interaction of IGFBP-3 and IGFBP-5 with RSP. We hypothesized that pulmonary IGFBP-3 and IGFBP-5 gene expression levels are downregulated in the nitrofen-induced pulmonary hypoplasia. Pregnant rats were exposed to either olive oil or 100 mg nitrofen on day 9.5 (D9.5) of gestation. Fetal lungs were harvested on D18 and D21 and divided into control and nitrofen groups. IGFBP-3 and IGFBP-5 pulmonary gene and protein expression were determined using real-time RT-PCR and immunohistochemistry. Relative levels of IGFBP-3 mRNA were significantly decreased in the nitrofen group (8.00 +/- 14.44) in D21 compared to controls (14.81 +/- 16.11; p < 0.05). Expression levels of IGFBP-5 mRNA were also significantly decreased in nitrofen group (10.66 +/- 4.83) on D18 compared to controls (17.92 +/- 4.77). Immunohistochemistry showed decreased IGFBP-3 expression on D21 and decreased IGFBP-5 immunoreactivity on D18 in hypoplastic lungs compared to controls. Downregulation of IGFBP-3 and IGFBP-5 gene expression may cause pulmonary hypoplasia in the nitrofen-induced CDH model by interfering with retinoid signaling pathway.

Early development of the primordial mammalian diaphragm and cellular mechanisms of nitrofen‐induced congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a frequently occurring cause of neonatal respiratory distress and is associated with high mortality and long-term morbidity. Evidence from animal models suggests that CDH has its origins in the malformation of the pleuroperitoneal fold (PPF), a key structure in embryonic diaphragm formation. The aims of this study were to characterize the embryogenesis of the PPF in rats and humans, and to determine the potential mechanism that leads to abnormal PPF development in the nitrofen model of CDH. Analysis of rat embryos, and archived human embryo sections, allowed the timeframe of PPF formation to be determined for both species, thus delineating a critical period of diaphragm development in relation to CDH. Experiments on nitrofen-exposed NIH 3T3 cells in vitro led us to hypothesize that nitrofen might cause diaphragmatic hernia in vivo by two possible mechanisms: through decreased cell proliferation or by inducing apoptosis. Data from nitrofen-exposed rat embryos indicates that the primary mechanism of nitrofen teratogenesis in the PPF is through decreased cell proliferation. This study provides novel insight into the embryogenesis of the PPF in rats and humans, and it indicates that impaired cell proliferation might contribute to abnormal diaphragm development in the nitrofen model of CDH.

Effect of prenatal tetrandrine administration on transforming growth factor- β1 level in the lung of nitrofen-induced congenital diaphragmatic hernia rat model

Purpose Tetrandrine (Tet) is a bisbenzylisoquinoline alkaloid isolated from the root of Stephania tetrandra, which has been used in traditional Chinese medicine to treat patients with silicosis, asthma, and pulmonary hypertension, and others and can be used as a pulmonary therapeutic agent. We hypothesized that it can also improve the lung growth in congenital diaphragmatic hernia (CDH) for its multiple biological effects. There are increasing evidences that suggest transforming growth factor β1(TGF- β1) plays a crucial role in fetal lung growth and morphogenesis. The aim of this study was to evaluate the effect of prenatal administration of Tet and to investigate its possible mechanism on the expression of TGF- β1 in the lung of nitrofen-induced CDH rat model. Methods A CDH model was induced in pregnant Sprague-Dawley rats by administration of nitrofen on day 9.5 of gestation (Ed9.5 term, day 22). Tetrandrine (30 mg/kg) was given through gavage (once a day, for 3 days) on Ed11.5. Accordingly, there were 3 groups as follows: control (n = 9), CDH (n = 9), and CDH + Tet (n = 9). All the fetuses were delivered by cesarean delivery on Ed16.5, 18.5, and 21.5, respectively, to check if diaphragmatic hernia existed on each fetus, then the lung tissue weight (LW) and body weight (BW) of each fetus were recorded. Histologic evaluations and TGF- β1 immunohistochemistry staining in the lung sample were performed for image analysis. Results Diaphragmatic hernia was observed in 95 of the 112 rat fetuses in CDH and CDH + Tet groups on Ed18.5 and Ed21.5 (84.8%), the incidence between the 2 groups had no statistical significance ( P = .642). Lung weight/body weight in the CDH group and the CDH + Tet group were lower than that in the control group ( P < .01), and LW/BW in the CDH group was lower than that in the CDH + Tet group ( P < .05). Observed under the light microscope and electron microscope, marked hypoplasia of the lungs in fetuses among the CDH groups was observed, in contrast to improvement of the lungs in CDH + Tet fetuses. Statistical differences in morphological parameters (percentage of alveoli area, counting bronchus) were found even on Ed16.5 when diaphragm had not closed ( P < .01). The number of type II pneumocytes and lamellar bodies in each group had no significant difference ( P > .05). The immunoreactivity of TGF- β1 in CDH group and CDH + Tet group were markedly stronger than that in the control group ( P < .01). In addition, TGF- β1 expression in the CDH group was stronger than that in the CDH + Tet group ( P < .01). Conclusion Nitrofen can interfere with lung development early in the fetal rat development before and separate from diaphragm development, and increased expression of TGF- β1 in the lung of CDH rat model may suppress lung growth and development. Prenatal treatment with Tet can improve the growth of the lung of the nitrofen-induced CDH fetuses and its mechanism seems to be involved in downregulating the expression of TGF- β1. It is a likely new approach to treat CDH and its coexistent lung hypoplasia by maternal Tet administration.

The Myenteric Plexus of the Esophagus is Abnormal in an Experimental Congenital Diaphragmatic Hernia Model

Infants surviving congenital diaphragmatic hernia (CDH) suffer from anatomical and functional esophageal abnormalities. Previous work in the nitrofen animal model of CDH demonstrated malformations in neural crest-derived structures, including the vagus and recurrent laryngeal nerves. The aim of the present study was to assess whether the esophageal myenteric plexus is abnormal in rats with CDH. We used the nitrofen-induced CDH fetal rat model. Two sections of the proximal, medium and distal esophagus from both groups were processed for immunohistochemical staining with anti-neuron specific enolase and anti-S-100 antibodies; the number of stained areas was recorded for each group. Whole-mount preparations of the entire esophagus of Control and CDH animals were histochemically stained for acetylcholinesterase; the density and area of the ganglia and the number of cells/ganglia were determined. Comparisons between groups were made by standard statistical methods. The number of immunohistochemically stained areas in transversal sections were decreased in CDH animals for anti-enolase (11.5+/-6.06 vs. 1.93+/-1.49, control vs. CDH, p<0.001) and anti S-100 antibodies (8.57+/-4.1 vs. 4.06+/-2.82, p<0.001). In whole-mount preparations the number of ganglia per high power field (35.16+/-6.57 vs. 29.29+/-10.26, p<0.05), the number of cells per ganglia (11.85+/-3.52 vs. 2.28+/-4.61, p<0.0001) and the relative area of the ganglia (0.35+/-0.32 vs. 0.18+/-0.42%, p<0.001), were also significantly decreased in CDH animals compared with Controls. Esophageal intrinsic innervation is defective in rat fetuses with CDH. If patients with CDH bear the same anomalies, this may explain some of their esophageal motility disorders. Finally, these findings support the concept of neural crest involvement in the pathogenic pathways of CDH.

A series of observation on the expression of TGF-beta1 in the lung of nitrofen-induced congenital diaphragmatic hernia rat model

To access the expression of transforming growth factor beta1 (TGF-beta1) in the lung of Nitrofen-induced congenital diaphragmatic hernia rat model. Twelve timed-pregnant Sprague-Dawley rats were randomly divided into two groups, namely control group and CDH group on day 9.5 of gestation. Each rat in the CDH group was given 125 mg of Nitrofen (dissolved in seed fat) by gavage. Each rat in the control group was given the same dose of single oil. On day 16 of gestation, the two groups mentioned above were divided into three subgroups, and fetuses were delivered by cesarean section respectively on day 16, 18 and 21 of gestation. After the fetuses were checked for diaphragmatic hernia, lung tissue weight (LW) and body weight (BW) of each fetus on gestational day 21 were recorded. Lung histologic evaluations were made with microscope and TGF-beta1 immunohistochemistry staining were performed with image analyzing. At day 16 of gestation, no visible diaphragm closure was observed in all fetuses. Diaphragmatic hernia was observed in 32 of the 44 rat fetuses of the CDH groups on day 18 and day 21 of gestation (72.7%). Lw/Bw of the 21d subgroups of CDH group were lower than those of corresponding control group (P < 0.01). Observed under the microscope, the lungs of fetuses in CDH groups showed marked hypoplasia. The expression of TGF-beta1 was detected in cytoplasmic, without definite expression in nuclear. It was significantly stronger that the expression of TGF-beta1 was in the lungs of the CDH group than that of the control group (P < 0.01). Nitrofen interferes with lung development in early stage of the fetal before the diaphragm developed. TGF-beta1 would be one of the important factors which lead to pulmonary hypoplasia.

SPC2996 – a potent, specific, long-lived and safe inhibitor of Bcl-2 in cultured cells and experimental animals shows efficacy in patients with chronic lymphocytic leukaemia

Pleuroperitoneal folds (PPFs) are the source of the primordial diaphragm's muscle connective tissue (MCT), and developmental mutations have been shown to result in congenital diaphragmatic hernia (CDH). The protein paired-related homeobox 1 (Prx1) labels migrating PPF cells and stimulates expression of transcription factor 4 (Tcf4), a novel MCT marker that controls morphogenesis of the fetal diaphragm. We hypothesized that diaphragmatic Prx1 and Tcf4 expression is decreased in the nitrofen-induced CDH model.Time-mated rats were exposed to either nitrofen or vehicle on gestational day 9 (D9). Fetal diaphragms were microdissected on D13, D15, and D18, and divided into control and nitrofen-exposed specimens. Gene expression levels of Prx1 and Tcf4 were analyzed by qRT-PCR. Immunofluorescence double staining for Prx1 and Tcf4 was performed to evaluate protein expression and localization.Relative mRNA expression of Prx1 and Tcf4 was significantly downregulated in PPFs (D13), developing diaphragms (D15) and fully muscularized diaphragms (D18) of nitrofen-exposed fetuses compared to controls. Confocal laser scanning microscopy revealed markedly diminished Prx1 and Tcf4 expression in diaphragmatic MCT of nitrofen-exposed fetuses on D13, D15, and D18 compared to controls.Decreased expression of Prx1 and Tcf4 in the fetal diaphragm may cause defects in the PPF-derived MCT, leading to development of CDH in the nitrofen model.Level 2c (Centre for Evidence-Based Medicine, Oxford).

Perinatal profile of ventricular overload markers in congenital diaphragmatic hernia

Background In congenital diaphragmatic hernia (CDH), pulmonary hypertension increases right ventricle (RV) afterload, which could impair heart function and contribute to poor outcome for most affected infants. Nevertheless, the real significance of vascular pulmonary alterations in perinatal hemodynamics is largely unknown. It is defined that ventricular pressure overload induces increased myocardium gene expression of B-type natriuretic peptide (BNP) and components of the renin-angiotensinogen and endothelin (ET)–1 systems. Our aim was to evaluate perinatal myocardium expression of these genes associated with ventricular pressure overload in a nitrofen-induced CDH rat model. Methods In the nitrofen-induced CDH rat model, fetuses from dated pregnant Sprague-Dawley rats at 15.5, 17.5, 19.5 and 21.5 days postcoitum as well as newborn pups were assigned to 3 experimental groups: control, nitrofen (exposed to nitrofen, without CDH), and CDH (exposed to nitrofen, with CDH). Myocardial samples collected from the RV and left ventricle (LV) were processed for quantification of messenger RNA (mRNA) of BNP, angiotensinogen, and ET-1. Results The perinatal expression of BNP, angiotensinogen, and ET-1 mRNA in the RV and LV of the control group revealed daily changes. During gestation, the expression of BNP and angiotensinogen mRNA underwent significant oscillation compared with control in both nitrofen-exposed fetuses, although we cannot identify significant differences between the nitrofen and CDH groups. After birth, we found a significant increasing expression of all studied genes only in the RV of CDH pups. Conclusions Perinatal myocardial quantification of BNP, angiotensinogen, and ET-1 mRNA levels suggests that both nitrofen-exposed and control pups revealed prenatal variations of expression of the studied genes. Moreover, CDH is associated with significant molecular alterations only in the RV after birth.

Effect of antenatal tetrandrine administration on endothelin-1 and epidermal growth factor levels in the lungs of rats with experimental diaphragmatic hernia

Purpose The aim of this study was to evaluate the effect of the traditional Chinese medicine tetrandrine (Tet) and to determine its possible mechanism on expression of endothelin-1 (ET-1) and epidermal growth factor (EGF) in the lung of a rat model of nitrofen-induced congenital diaphragmatic hernia (CDH). Methods A single oral dose (115 mg/kg) of nitrofen on day 9.5 of pregnancy was maternally administered to induce CDH. Pregnant rats were divided into 4 groups on day 18.5: control (n = 5), CDH (n = 5), CDH+dexamethasone (Dex) (n = 5), and CDH+Tet (n = 5). All fetuses were delivered by cesarean delivery on day 21.5. Accordingly, there were 4 groups of fetuses: control (n = 38), CDH (n = 25), CDH+Dex (n = 21), and CDH+Tet (n = 22). Lung tissue weight (LW) and body weight (BW) of each fetus were recorded, lung histologic evaluations and ET-1 and EGF immunohistochemistry staining were performed, and image analysis was performed after lung processing. Results Five female rats in the control group produced 38 fetuses without CDH. CDH was observed in 68 of the 128 rat fetuses (53.1%) among the other 3 groups. The LW/BW ratio of the CDH group was significantly lower than those of the Dex and EGF groups ( P < .05). The lungs of fetuses with CDH showed marked abnormal structure such as pulmonary hypoplasia and vascular remodeling, in contrast to improved pulmonary structure in lungs of fetuses in the CDH+Dex and CDH+Tet groups. Statistical differences in morphologic parameters (radial alveolar counts, percentage of alveoli, percentage of medial wall thickness, and vascular volume) were found ( P < .05). The immunoreactivity of EGF and ET-1 in the CDH group was markedly stronger than that in the control, CDH+Dex, and CDH+Tet groups ( P < .01). In addition, EGF and ET-1 expression in the CDH+Dex and CDH+Tet groups was stronger than that in the control group ( P < .05). There was no difference in lung EGF and ET-1 immunoreactivity between CDH+Dex and CDH+Tet groups ( P > .05). Conclusion Antenatal treatment with Tet may improve lung growth and vascular remodeling, and its mechanism seems to be involved in decreasing EGF and ET-1 expression. Tet administered maternally may be a hopeful new therapeutic option in the treatment of CDH and may be effective in helping to avoid the side effects of Dex.

Pulmonary epithelial cell differentiation in the nitrofen-induced congenital diaphragmatic hernia

Background/Aim In congenital diaphragmatic hernia (CDH), there is pulmonary neuroendocrine cell (PNEC) hyperplasia and Clara (nonendocrine) cell hypoplasia, the meaning of which remains unknown. In embryonic/fetal lung, an intricate cross talk between Notch pathway and basic helix-loop-helix transcription factors Mash1 and Hes1 determines the balance between endocrine and nonendocrine epithelial cell fate. Differences at the molecular level in pulmonary epithelial cell differentiation between control and CDH hypoplastic lungs were investigated. Material and Methods The nitrofen-induced CDH rat model was used. At 15.5 days postconception (dpc), fetuses were assigned to 2 experimental groups: control and nitrofen (exposed to nitrofen, without CDH), whereas at 17.5, 19.5, and 21.5 dpc, fetuses were assigned to 3 experimental groups: control, nitrofen, and CDH (exposed to nitrofen, with CDH). The fetal lungs were processed for expression quantification of CC10, Hes1, Mash1, and Dll1 by real-time polymerase chain reaction. Results In control fetuses, expression of all studied genes increased with gestational age. In nitrofen-exposed fetal lungs, endocrine cell marker Mash1 was downregulated only at the earliest studied gestational age, whereas Dll1 expression levels were significantly increased in the CDH group at 19.5 and 21.5 dpc. Regarding nonendocrine markers, Hes1 presented increased expression at 15.5 and 19.5 dpc, whereas CC10 was downregulated at 17.5 and 19.5 dpc but not at term. Conclusions This study suggests that PNEC hyperplasia in CDH fetal lung is likely because of Notch signaling deregulation, whereas Clara cell hypoplasia in CDH lungs could be a consequence of protein synthesis delay, reflecting a functional maturation hindrance and not a cell fate commitment problem.

Embryonic Essential Myosin Light Chain Regulates Fetal Lung Development in Rats

Congenital diaphragmatic hernia (CDH) is currently the most life-threatening congenital anomaly the major finding of which is lung hypoplasia. Lung hypoplasia pathophysiology involves early developmental molecular insult in branching morphogenesis and a late mechanical insult by abdominal herniation in maturation and differentiation processes. Since early determinants of lung hypoplasia might appear as promising targets for prenatal therapy, proteomics analysis of normal and nitrofen-induced hypoplastic lungs was performed at 17.5 days after conception. The major differentially expressed protein was identified by mass spectrometry as myosin light chain 1a (MLC1a). Embryonic essential MLC1a and regulatory myosin light chain 2 (MLC2) were characterized throughout normal and abnormal lung development by immunohistochemistry and Western blot. Disruption of MLC1a expression was assessed in normal lung explant cultures by antisense oligodeoxynucleotides. Since early stages of normal lung development, MLC1a was expressed in vascular smooth muscle (VSM) cells of pulmonary artery, and MLC2 was present in parabronchial smooth muscle and VSM cells of pulmonary vessels. In addition, early smooth muscle differentiation delay was observed by immunohistochemistry of alpha-smooth muscle actin and transforming growth factor-beta1. Disruption of MLC1a expression during normal pulmonary development led to significant growth and branching impairment, suggesting a role in branching morphogenesis. Both MLC1a and MLC2 were absent from hypoplastic fetal lungs during pseudoglandular stage of lung development, whereas their expression partially recovered by prenatal treatment with vitamin A. Thus, a deficiency in contractile proteins MLC1a and MLC2 might have a role among the early molecular determinants of lung hypoplasia in the rat model of nitrofen-induced CDH.

Fetal Tracheal Occlusion for the Treatment of Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) continues to be associated with significant mortality and morbidity rates despite advances in neonatal care. Fetal intervention for CDH has been studied for 25 years. After initial difficulties encountered with open fetal repair, attention has turned to tracheal occlusion (TO) as a method to correct pulmonary hypoplasia before birth. This article reviews our contribution to this field of research and outlines the current status of this treatment modality. Using the fetal lamb model, we have studied the effects of fetal TO on tracheal fluid pressure, lung growth and type II pneumocyte maturation, and surfactant production. We developed a minimally invasive and reversible technique of TO, using a detachable balloon placed using single-port tracheoscopy. We examined differential lung growth, structural maturation, pulmonary artery remodeling, and lung function during an 8-h resuscitation period in lambs, comparing normal controls, lambs with a surgically created CDH, those with CDH+TO, and those with CDH+TO and release of TO 1 week before delivery. We also studied the potential benefits of maternal betamethasone administration and the administration of surfactant at birth. Using a neonatal piglet model, we examined the effect of postnatal pulmonary distension with perfluorocarbon on lung growth. More recently, we turned to the rat nitrofen-induced CDH model to study the effects of TO on bronchial branching and some molecular markers of lung growth (Shh and LGL1). Fetal TO is being used to treat human CDH, but its application remains limited by the absence of reliable and widely reproducible prenatal prognostic criteria. A better understanding of the molecular events guiding the lung growth seen with TO may help to refine its use in humans.

Effect of tetrandrine on endothelin expression in the lungs and clinical significance thereof: experiment with rat models with nitrofen-induced congenital diaphragmatic hernia

To investigate the effects of tetrandrine on endothelin expression in the lungs and its clinical significance. 25 pregnant female SD rats were randomly divided into 5 equal groups: Groups A to D were fed with nitrofen to cause congenital diaphragmatic hernia (CDH) in the fetuses. Group A was injected with normal saline, Group B with dexamethasone (DXM), Group C with tetrandrine, and Group D with DXM + tetrandrine. Group E was control Group. On day 21.5 of pregnancy the fetuses were delivered by cesarean section and killed. Microscopy was used to observe the CDH formation, and the relative wall thickness (RWA) and relative wall area (RWA) of pulmonary arterioles. The lung/body weight ratio, and relative integrated optical density (IOD) of pulmonary arteriole and bronchiole were observed. The expression of endothelin in the lung tissues was detected by immunohistochemistry. 9 rats of Group A-D produced 57 fetuses with CDH with a CDH arte of 45.2%. The lung/body weight ratios, and RWA values of Group A-D were all significantly lower than that of Group E (all P < 0.05). The RWT of pulmonary arteriole was significantly lower in Groups B and C compared with Group E (both P < 0.05). The RWT and RWA of Group A were significantly lower than those of Group B-D (all P < 0.05). The values of relative IOD of pulmonary tissues and of pulmonary arteriole of Group A-D were all significantly lower than those of Group E (all P < 0.05). A positive correlation existed between the relative IOD of endothelin in pulmonary arteriole and in bronchiole (P < 0.01), and among the RWT and RWA of pulmonary arteriole, and relative IOD (all P < 0.01). Tetrandrine improves the pulmonary hypoplasia and degrades the pulmonary hypertension.