Nitrofen-induced Congenital Diaphragmatic Hernia Rat Research Articles

Fetal lung hypoxia and energetic cell failure in the nitrofen-induced congenital diaphragmatic hernia rat model.

Congenital diaphragmatic hernia (CDH) pathogenesis is poorly understood. We hypothesize that fetal CDH lungs are chronically hypoxic because of lung hypoplasia and tissue compression, affecting the cell bioenergetics as a possible explanation for abnormal lung development. To investigate this theory, we conducted a study using the rat nitrofen model of CDH. We evaluated the bioenergetics status using H1 Nuclear magnetic resonance and studied the expression of enzymes involved in energy production, the hypoxia-inducible factor 1α, and the glucose transporter 1. The nitrofen-exposed lungs have increased levels of hypoxia-inducible factor 1α and the main fetal glucose transporter, more evident in the CDH lungs. We also found imbalanced AMP:ATP and ADP:ATP ratios, and a depleted energy cellular charge. Subsequent transcription levels and protein expression of the enzymes involved in bioenergetics confirm the attempt to prevent the energy collapse with the increase in lactate dehydrogenase C, pyruvate dehydrogenase kinase 1 and 2, adenosine monophosphate deaminase, AMP-activated protein kinase, calcium/calmodulin-dependent protein kinase 2, and liver kinase B1, while decreasing ATP synthase. Our study suggests that changes in energy production could play a role in CDH pathogenesis. If confirmed in other animal models and humans, this could lead to the development of novel therapies targeting the mitochondria to improve outcomes.

Upregulated TSP1 and CD47 expression in the lung in nitrofen-induced congenital diaphragmatic hernia.

Persistent pulmonary hypertension remains a major cause of mortality and morbidity in congenital diaphragmatic hernia (CDH). The secreted glycoprotein thrombospondin-1 (TSP1), a ligand for receptor CD47, is widely expressed on both systemic and pulmonary vascular cells. TSP1-CD47 signaling has been reported to be one of the pathogeneses of pulmonary hypertension (PH). After creating a nitrofen-induced CDH rat model, fetuses were sacrificed on D17, D19 and D21 and divided into a control group and a CDH group. Quantitative real-time polymerase chain reaction was performed to determine the pulmonary gene expression of TSP1, CD47 and Runx3 (a regulator of TSP1). An immunofluorescence study was performed to evaluate the expression and localization of TSP1, CD47 and Runx3. The relative mRNA expression of pulmonary TSP1, CD47 and Runx3 on D21 was significantly increased in the CDH group (p=0.005, p=0.001, p=0.046, and p=0.002, respectively). The immunofluorescence study also confirmed the overexpression of TSP1, CD47 and Runx3 in the CDH group. Our results provide evidence that TSP1-CD47 signaling is involved in the pathogenesis of PH in a nitrofen-induced CDH model. Our data suggest that anti-CD47 antibodies can be novel therapeutic targets for the treatment of PH in CDH.

Congenital diaphragmatic hernia: phosphodiesterase-5 and Arginase inhibitors prevent pulmonary vascular hypoplasia in rat lungs.

Severe pulmonary hypoplasia related to congenital diaphragmatic hernia (CDH) continues to be a potentially fatal condition despite advanced postnatal management strategies. To evaluate the effect of the antenatal sildenafil and 2(S)-amino-6-boronohexanoic acid (ABH-Arginase inhibitor) on lung volume, pulmonary vascular development, and nitric oxide (NO) synthesis in a Nitrofen-induced CDH rat model. Nitrofen-induced CDH rat model was used. Nitrofen was administrated on embryonic day(E) 9,5. At E14, five intervention groups were treated separately: Nitrofen, Nitrofen+Sildenafil, Nitrofen+ABH, Nitrofen+Sildenafil+ABH and Control. At term, offspring's lungs were weighed, some paraffin-embedded for histology, others snap-frozen to analyze eNOS, Arginase I-II expression, and activity. In CDH-bearing offsprings, ABH or Sildenafil+ABH preserved the total lung/body-weight index (p < 0.001), preventing pulmonary vascular smooth muscle cell hyperproliferation and improving lung morphometry. Sildenafil+ABH increased 1.7-fold the lung nitrite levels (p < 0.01) without changes in eNOS expression. Sildenafil and ABH improved the number of pulmonary vessels. These results suggest that in this CDH rat model, the basal activity of Arginase participates in the lung volume and, together with phosphodiesterase-5, regulates NOS activity in the term fetal lung. The combined treatment (Sildenafil+ABH) could revert some of the pulmonary features in CDH by improving the local NO synthesis and preventing smooth muscle cell hyperproliferation. This study presents Arginase inhibition as a new therapeutic target and the importance of the combined antenatal treatment to improve pulmonary vascular development in a congenital diaphragmatic hernia (CDH) rat model. This study shows that the action of an Arginase inhibitor (ABH) enhances the effects already described for sildenafil in this model. These results reinforce the importance of prenatal treatments' synergy in recovering the hypoplastic lung in the Nitrofen-induced CDH rat model.

Distinct Epithelial Cell Profiles in Normal Versus Induced-Congenital Diaphragmatic Hernia Fetal Lungs.

BackgroundRecent studies identified a great diversity of cell types in precise number and position to create the architectural features of the lung that ventilation and respiration at birth depend on. With damaged respiratory function at birth, congenital diaphragmatic hernia (CDH) is one of the more severe causes of fetal lung hypoplasia with unspecified cellular dynamics.Objectives To characterize the epithelial cell tissue in hypoplastic lungs, a careful analysis regarding pulmonary morphology and epithelial cell profile was conducted from pseudoglandular-to-saccular phases in normal versus nitrofen-induced CDH rat lungs.DesignOur analysis comprises three experimental groups, control, nitrofen (NF) and CDH, in which the relative expression levels (western blot) by group and developmental stage were analyzed in whole lung. Spatiotemporal distribution (immunohistochemistry) was revealed by pulmonary structure during normal and hypoplastic fetal lung development. Surfactant protein-C (SP-C), calcitonin gene-related peptide (CGRP), clara cell secretory protein (CCSP), and forkhead box J1 (FOXJ1) were the used molecular markers for alveolar epithelial cell type 2 (AEC2), pulmonary neuroendocrine, clara, and ciliated cell profiles, respectively.ResultsGenerally, we identified an aberrant expression of SP-C, CGRP, CCSP, and FOXJ1 in nitrofen-exposed lungs. For instance, the overexpression of FOXJ1 and CGRP in primordia of bronchiole defined the pseudoglandular stage in CDH lungs, whereas the increased expression of CGRP in bronchi; FOXJ1 and CGRP in terminal bronchiole; and SP-C in BADJ classified the canalicular and saccular stages in hypoplastic lungs. We also described higher expression levels in NF than CDH or control groups for both FOXJ1 in bronchi, terminal bronchiole and BADJ at canalicular stage, and SP-C in bronchi and terminal bronchiole at canalicular and saccular stages. Finally, we report an unexpected expression of FOXJ1 in BADJ at canalicular and saccular stages, whereas the multi cilia observed in bronchi were notably absent at embryonic day 21.5 in induced-CDH lungs.ConclusionThe recognized alterations in the epithelial cell profile contribute to a better understanding of neonatal respiratory insufficiency in induced-CDH lungs and indicate a problem in the epithelial cell differentiation in hypoplastic lungs.

ROBO2 signaling in lung development regulates SOX2/SOX9 balance, branching morphogenesis and is dysregulated in nitrofen-induced congenital diaphragmatic hernia

BackgroundCharacterized by abnormal lung growth or maturation, congenital diaphragmatic hernia (CDH) affects 1:3000 live births. Cellular studies report proximal (SOX2+) and distal (SOX9+) progenitor cells as key modulators of branching morphogenesis and epithelial differentiation, whereas transcriptome studies demonstrate ROBO/SLIT as potential therapeutic targets for diaphragm defect repair in CDH. In this study, we tested the hypothesis that (a) experimental-CDH could changes the expression profile of ROBO1, ROBO2, SOX2 and SOX9; and (b) ROBO1 or ROBO2 receptors are regulators of branching morphogenesis and SOX2/SOX9 balance.MethodsThe expression profile for receptors and epithelial progenitor markers were assessed by Western blot and immunohistochemistry in a nitrofen-induced CDH rat model. Immunohistochemistry signals by pulmonary structure were also quantified from embryonic-to-saccular stages in normal and hypoplastic lungs. Ex vivo lung explant cultures were harvested at E13.5, cultures during 4 days and treated with increasing doses of recombinant rat ROBO1 or human ROBO2 Fc Chimera proteins for ROBO1 and ROBO2 inhibition, respectively. The lung explants were analyzed morphometrically and ROBO1, ROBO2, SOX2, SOX9, BMP4, and β-Catenin were quantified by Western blot.ResultsExperimental-CDH induces distinct expression profiles by pulmonary structure and developmental stage for both receptors (ROBO1 and ROBO2) and epithelial progenitor markers (SOX2 and SOX9) that provide evidence of the impairment of proximodistal patterning in experimental-CDH. Ex vivo functional studies showed unchanged branching morphogenesis after ROBO1 inhibition; increased fetal lung growth after ROBO2 inhibition in a mechanism-dependent on SOX2 depletion and overexpression of SOX9, non-phospho β-Catenin, and BMP4.ConclusionsThese studies provided evidence of receptors and epithelial progenitor cells which are severely affected by CDH-induction from embryonic-to-saccular stages and established the ROBO2 inhibition as promoter of branching morphogenesis through SOX2/SOX9 balance.

Upregulated EFNB2 and EPHB4 promotes lung development inanitrofen-induced congenital diaphragmatic hernia rat model.

Congenital diaphragmatic hernia (CDH) is a common congenital malformation associated with high mortality rates, mainly due to pulmonary hypoplasia and persistent pulmonary hypertension following birth. The present study aimed to investigate abnormal lung development in a rat CDH model, and examine temporal and spatial changes in the expression of ephrin type-B receptor 4 (EPHB4) and ephrin-B2 (EFNB2) during fetal lung development, to elucidate the role of these factors during lung morphogenesis. Pregnant rats received nitrofen on embryonic day (E) 8.5 to induce CDH, and fetal lungs were collected on E13.5, E15.5, E17.5, E19.5, and E21.5. The mean linear intercept (MLI) and mean alveolar number (MAN) were observed in fetal lung tissue at E21.5 following hematoxylin and eosin staining. E13.5 fetal lungs were cultured for 96 h in serum-free medium and branch development was observed under a microscope. The gene and protein expression levels of EPHB4 and EFNB2 were assessed by reverse transcription-quantitative polymerase chain reaction analysis, and immunoblotting and immunohistochemistry, respectively. The fetal rat lungs were treated with EFNB2 and the activity of key signaling pathways was assessed. The lung index (lung weight/body weight) at E21.5 was significantly lower in the CDH rats, compared with that in the control fetal rats. The MLI and MAN were also lower in the CDH group. The number of lung terminal buds at E13.5 (embryonic stage), and the lung-explant perimeter and surface were all smaller in the CDH group rats than in the control group at the same age. Pulmonary hypoplasia was observed following 96 h of in vitro culture. No significant differences were found in the expression levels of EFNB2 and EPHB4 between the CDH and control groups at E13.5 (embryonic stage) or E15.5 (pseudoglandular stage), however, EFNB2 and EPHB4 were significantly upregulated at E17.5 (canalicular stage), and at E19.5 and E21.5 (saccular/alveolar stages). EFNB2 stimulated pulmonary branching and EFNB2 supplementation decreased the activity of p38, c-Jun NH2-terminal kinase, extracellular signal-regulated kinase, and signal transducer and activator of transcription. The CDH fetal rats developed pulmonary dysplasia at an early stage of fetal pulmonary development. Upregulated expression of EFNB2 and EPHB4 was observed in the rat lung of nitrofen-induced CDH, and the increased expression of EFNB2 promoted rat lung development in the nitrofen-induced CDH model.

STATs in Lung Development: Distinct Early and Late Expression, Growth Modulation and Signaling Dysregulation in Congenital Diaphragmatic Hernia

Background: Congenital diaphragmatic hernia (CDH) is a life-threatening developmental anomaly, intrinsically combining severe pulmonary hypoplasia and hypertension. During development, signal transducers and activators of transcription (STAT) are utilized to elicit cell growth, differentiation, and survival. Methods: We used the nitrofen-induced CDH rat model. At selected gestational time points, lungs were divided into two experimental groups, i.e., control or CDH. We performed immunohistochemistry and western blotting analysis to investigate the developmental expression profile of the complete family of STATs (STAT1-6), plus specific STATs activation (p-STAT3, p-STAT6) and regulation by SOCS (SOCS3) in normal lungs against those of diseased lungs. The normal fetal lung explants were treated with piceatannol (STAT3 inhibitor) in vitro followed by morphometrical analysis. Results: Molecular profiling of STATs during the lung development revealed distinct early and late expression signatures. Experimental CDH altered the STATs expression, activation, and regulation in the fetal lungs. In particular, STAT3 and STAT6 were persistently over-expressed and early over-activated. Piceatannol treatment dose-dependently stimulated the fetal lung growth. Conclusion: These findings suggest that STATs play an important role during normal fetal lung development and CDH pathogenesis. Moreover, functionally targeting STAT signaling modulates fetal lung growth, which highlights that STAT3 and STAT6 signaling might be promising therapeutic targets in reducing or preventing pulmonary hypoplasia in CDH.

Increased CaSR and TRPC6 pulmonary vascular expression in the nitrofen-induced model of congenital diaphragmatic hernia

The high morbidity and mortality rates in congenital diaphragmatic hernia (CDH) are attributed primarily to severe lung hypoplasia and/or persistent pulmonary hypertension (PPH). PPH in CDH is characterized by abnormal vascular remodeling with thickening of medial and adventitial layers and extension of smooth muscle into previously nonmuscularized arteries. Excessive proliferation of pulmonary arterial smooth muscle cells (PASMC) is an important contributor to the concentric pulmonary arterial remodeling. An increase in cytosolic-free Ca2+ concentration in PASMC is a major trigger for pulmonary vasoconstriction and a key stimulus for PASMC proliferation and migration. Calcium-sensing receptor (CaSR), a member of the G-protein coupled receptor family, is activated by cations (e.g., Ca2+, Mg2+) and polyamines. Under normal physiological conditions, the expression levels of CaSR in the pulmonary vasculature are very low. Canonical transient receptor potential channels (TRPCs) constitute a series of nonselective cation channels with variable degree of Ca2+ selectivity. TRPC6 has been reported to play a crucial role in the regulation of neo-muscularization, vasoreactivity, and vasomotor tone in the pulmonary vasculature. We hypothesized that CaSR and TRPC6 expression is upregulated in the pulmonary vasculature of nitrofen-induced CDH rats. Following ethical approval (REC1103), time-pregnant Sprague Dawley rats received nitrofen or vehicle on gestational day (D) 9. D21 fetuses were divided into CDH and control (n = 12). Quantitative real-time polymerase chain reaction (QRT-PCR), western blotting, and confocal-immunofluorescence microscopy were performed to detect lung gene and protein expression of CaSR and TRPC6. QRT-PCR and western blot analysis revealed that CaSR and TPRC6 expression was significantly increased in the CDH group compared to controls (p < 0.05). Confocal-immunofluorescence microscopy revealed that CaSR and TRPC6 lung expression was markedly increased in CDH group compared to controls. Increased CaSR and TRPC6 expression in CDH lung suggests that CaSR interacting with TRPC6 may contribute to abnormal vascular remodeling resulting in pulmonary vasoconstriction and development of PPH.

Downregulated Elastin Microfibril Interfacer 1 Expression in the Pulmonary Vasculature of Experimental Congenital Diaphragmatic Hernia.

Pulmonary hypertension (PH) is a severe complication of congenital diaphragmatic hernia (CDH). Transforming growth factor-β (TGFβ) signaling is suggested to be involved in PH development by regulating embryonic angiogenesis, cell proliferation, and cell differentiation. Altered TGFβ signaling has been demonstrated in experimental CDH lungs. Elastin microfibril interfacer 1 (Emilin-1) is an extracellular matrix glycoprotein expressed in endothelial and vascular smooth muscle cells and known to regulate TGFβ processing and arterial diameter. We designed this study to investigate the pulmonary vascular expression of Emilin-1 in nitrofen-induced CDH rats. Following ethical approval (REC913b, REC1103), time-pregnant Sprague Dawley rats received nitrofen or vehicle on gestational day 9 (D9). Fetuses were sacrificed on D21 and divided into CDH group and control group. Quantitative real-time polymerase chain reaction (n = 11 each group), Western blot analysis, and confocal microscopy were used to determine the gene and protein expression of Emilin-1. Relative Emilin-1 messenger RNA (ribonucleic acid) levels were significantly downregulated in CDH lung tissue compared with controls (CDH: 0.043 ± 0.003; control: 0.067 ± 0.004; p < 0.001). Western blotting confirmed the decreased pulmonary Emilin-1 protein expression in CDH lungs. Confocal microscopy demonstrated a markedly diminished expression of Emilin-1 in the CDH pulmonary vasculature compared with controls. To our knowledge, this study demonstrates for the first time a decreased Emilin-1 gene and protein expression in the pulmonary vasculature of nitrofen-induced CDH. Emilin-1 deficiency through its interaction with TGFß may result in abnormal vascular remodeling resulting in PH in this model.

Downregulation of KCNQ5 expression in the rat pulmonary vasculature of nitrofen-induced congenital diaphragmatic hernia

PurposePulmonary hypertension (PH) is a common complication of congenital diaphragmatic hernia (CDH). Voltage-gated potassium channels KCNQ1, KCNQ4, and KCNQ5 are expressed by rodent pulmonary artery smooth muscle cells, contributing to their vascular tone. We hypothesized that KCNQ1, KCNQ4, and KCNQ5 expression is altered in the pulmonary vasculature of nitrofen-induced CDH rats. MethodsAfter ethical approval (REC913b), time-pregnant rats received nitrofen or vehicle on gestational day (D)9. D21 fetuses were divided into CDH and control group (n=22). QRT-PCR and western blotting were performed to determine gene and protein expression of KCNQ1, KCNQ4, and KCNQ5. Confocal microscopy was used to detect these proteins in the pulmonary vasculature. ResultsRelative mRNA level of KCNQ5 (p=0.025) was significantly downregulated in CDH lungs compared to controls. KCNQ1 (p=0.052) and KCNQ4 (p=0.574) expression was not altered. Western blotting confirmed the decreased pulmonary KCNQ5 protein expression in CDH lungs. Confocal-microscopy detected a markedly diminished KCNQ5 expression in pulmonary vasculature of CDH fetuses. ConclusionsDownregulated pulmonary expression of KCNQ5 in CDH lungs suggests that this potassium channel may play an important role in the development of PH in this model. KCNQ5 channel activator drugs may be a potential therapeutic target for the treatment of PH in CDH. Level of evidence2b (Centre for Evidence-Based Medicine, Oxford)

Decreased Endoglin expression in the pulmonary vasculature of nitrofen-induced congenital diaphragmatic hernia rat model.

Pulmonary hypertension (PH) remains a therapeutical challenge in neonates born with congenital diaphragmatic hernia (CDH). Endoglin (Eng), an auxiliary receptor component of the transforming growth factor β (TGFβ) signalling pathway, is expressed mainly by endothelial cells and has been found to be involved in angiogenesis and vascular remodelling. Genetic studies have linked TGFβ and Eng mutations to human arterial PH and other cardiovascular syndromes. Eng interacts with the TGFβ receptors 1 and 2 (Tgfβr1, Tgfβr2). We designed this study to investigate the hypothesis that Eng is altered in the pulmonary vasculature of rats with nitrofen-induced CDH subjected to its interdependency with Tgfβr1 and Tgfβr2. After ethical approval (Rec 913b), time-pregnant Sprague-Dawley rats received either nitrofen or olive oil on gestational day (D9). The foetuses (n=22) were sacrificed and divided into CDH and control group on D21. Gene and protein expressions of Eng, Tgfβr1 and Tgfβr2 were assessed via qRT-PCR and western blotting. Immunofluorescence staining for Eng was combined with CD34 to evaluate Eng expression in the pulmonary vasculature. Relative mRNA levels of Eng, Tgfβr1 and Tgfβr2 were significantly downregulated in CDH lungs compared to controls (Eng CDH 0.341±0.022, Eng Ctrl 0.471±0.031, p=0.0015; Tgfβr1 CDH 0.161±0.008, Tgfβr1 Ctrl 0.194±0.01, p=0.0114; Tgfβr2 CDH 0.896±0.099, Tgfβr2 Ctrl 1.379±0.081, p=0.0006) Western blotting confirmed the reduced pulmonary protein expression of these three proteins in the CDH lungs. A markedly diminished endothelial expression of Eng in the pulmonary vasculature of nitrofen-exposed foetuses compared to controls was seen in laser scanning confocal-microscopy. This study demonstrates for the first time a reduced expression of Endoglin in the pulmonary vasculature of nitrofen-induced CDH. Abnormal Eng/Tgfβr1/Tgfβr2 signalling may contribute to impaired vascular remodelling and development of PH in this CDH animal model.

Placental oxidative stress is increased in a nitrofen-induced congenital diaphragmatic hernia rat

Placental oxidative stress is increased in a nitrofen-induced congenital diaphragmatic hernia rat

Downregulation of Forkhead box F1 gene expression in the pulmonary vasculature of nitrofen-induced congenital diaphragmatic hernia.

High mortality and morbidity in infants born with congenital diaphragmatic hernia (CDH) are attributed to pulmonary hypoplasia and pulmonary hypertension (PH). Forkhead box (Fox) transcription factors are known to be crucial for cell proliferation and homeostasis. FoxF1 is essential for lung morphogenesis, vascular development, and endothelial proliferation. Mutations in FoxF1 and also the Fox family member FoxC2 have been identified in neonates with PH. In human and experimental models of arterial PH, the Fox protein FoxO1 was found to be downregulated. We hypothesized that Fox expression is altered in the lungs of the nitrofen-induced CDH rat model and investigated the expression of FoxF1, FoxC2, and FoxO1. Following ethical approval (Rec 913b), time-pregnant Sprague-Dawley rats received nitrofen or vehicle on gestational day (D9). Fetuses were sacrificed on D21, inspected for CDH and divided into CDH (n=11) and control group (n=11). Gene expression of FoxF1, FoxC2, and FoxO1 was evaluated with qRT-PCR. Detected alterations of mRNA levels were subsequently assessed on the protein level by performing western blot analysis and laser scanning confocal microscopy. The relative mRNA level of FoxF1 was significantly downregulated in CDH lungs compared to controls (FoxF1 CDH 1.047±0.108, FoxF1 Ctrl 1.419±0.01, p=0.014). Relative mRNA levels of FoxC2 and FoxO1 were not found to be altered between the experimental groups (FoxC2 CDH 30.74±8.925, FoxC2 Ctrl 27.408±7.487, p=0.776; FoxO1 CDH 0.011±0.002, FoxO1 Ctrl 0.011±0.001, p=0.809). On the protein level, western blotting demonstrated a reduced pulmonary protein expression of FoxF1 in CDH lungs. Confocal microscopy showed a markedly diminished expression of FoxF1 in the pulmonary vasculature of CDH lungs compared to controls. Our study demonstrates a strikingly reduced expression of FoxF1 in the pulmonary vasculature of nitrofen-induced CDH. Altered FoxF1 gene expression during embryogenesis may participate in vascular maldevelopment resulting in PH in this animal model.

Decreased Desmin expression in the developing diaphragm of the nitrofen-induced congenital diaphragmatic hernia rat model.

Congenital diaphragmatic hernia (CDH) is presumed to originate from defects in the primordial diaphragmatic mesenchyme, mainly comprising of muscle connective tissue (MCT). Thus, normal diaphragmatic morphogenesis depends on the structural integrity of the underlying MCT. Developmental mutations that inhibit normal formation of diaphragmatic MCT have been shown to result in CDH. Desmin (DES) is a major filament protein in the MCT, which is essential for the tensile strength of the developing diaphragm muscle. DES -/- knockout mice exhibit significant reductions in stiffness and elasticity of the developing diaphragmatic muscle tissue. Furthermore, sequence changes in the DES gene have recently been identified in human cases of CDH, suggesting that alterations in DES expression may lead to diaphragmatic defects. This study was designed to investigate the hypothesis that diaphragmatic DES expression is decreased in fetal rats with nitrofen-induced CDH. Time-mated Sprague-Dawley rats were exposed to either nitrofen or vehicle on gestational day 9 (D9). Fetuses were harvested on selected time-points D13, D15 and D18, and dissected diaphragms (n=72) were divided into control and nitrofen-exposed specimens (n=12 per time-point and experimental group, respectively). Laser-capture microdissection was used to obtain diaphragmatic tissue elements. Diaphragmatic gene expression of DES was analyzed by quantitative real-time polymerase chain reaction. Immunofluorescence double staining for DES was combined with the mesenchymal marker GATA4 to evaluate protein expression and localization in developing fetal diaphragms. Relative mRNA expression levels of DES were significantly decreased in pleuroperitoneal folds on D13 (1.49±1.79 vs. 3.47±2.32; p<0.05), developing diaphragms on D15 (1.49±1.41 vs. 3.94±3.06; p<0.05) and fully muscularized diaphragms on D18 (2.45±1.47 vs. 5.12±3.37; p<0.05) of nitrofen-exposed fetuses compared to controls. Confocal laser scanning microscopy demonstrated markedly diminished immunofluorescence of DES mainly in diaphragmatic MCT, which was associated with a reduction of proliferating mesenchymal cells in nitrofen-exposed fetuses on D13, D15 and D18 compared to controls. Decreased expression of DES in the fetal diaphragm may disturb the basic integrity of myofibrils and the cytoskeletal network during myogenesis, causing malformed MCT and leading to diaphragmatic defects in the nitrofen-induced CDH model.

Decreased expression of miR-33 in fetal lungs of nitrofen-induced congenital diaphragmatic hernia rat model

BackgroundThe pathogenesis of congenital diaphragmatic hernia (CDH) and the causes of pulmonary hypoplasia and hypertension remain unclear. miRNAs have been identified to play important regulatory roles in pulmonary pathological processes and lung development. We carried out the study to investigate the hypothesis that specific miRNAs are expressed differently in the lungs of nitrofen-induced rats, and to explore the possible targeting genes and roles of miR-33 in the pathological process of CDH. MethodsPregnant rats were divided into nitrofen and control group, and were exposed to nitrofen or vehicle respectively on D9. Fetuses were harvested on D21 and left lungs were dissected. 4 samples from each group underwent miRNAs microarray analysis using Agilent miRNA Array. Quantitative real-time polymerase chain reaction (qRT-PCR) was further performed to validate the miR-33 expression. Results11 miRNAs exhibited increased expression in nitrofen group compared with control (p<0.05): miR-3588, miR-382*, miR-363, miR-375, miR-487b, miR-483, miR-382, miR-495, miR-434, miR-181a, and miR-99a. 14 miRNAs showed decreased expression (p<0.05): miR-33, miR-193, miR-338, miR-30c-2*, miR-22, miR-18a, miR-532-5p, miR-28, miR-96, miR-551b, miR-141, miR-362*, miR-30a*, and miR-3559-5p. Among them, miR-33 expression was markedly decreased in CDH lungs compared to controls and the result was confirmed by qRT-PCR. ConclusionDecreased expression of miR-33 was found in the nitrofen-induced hypoplastic lung on D21. This finding suggests that pathogenesis of lung hypoplasia and CDH in the nitrofen model involve epigenetic layer of regulation.

Increased pulmonary RhoA expression in the nitrofen-induced congenital diaphragmatic hernia rat model

PurposePersistent pulmonary hypertension remains a major cause of mortality and morbidity in cases of congenital diaphragmatic hernia (CDH). Recently, RhoA/Rho-kinase-mediated vasoconstriction has been reported to be important in the pathogenesis of pulmonary hypertension (PH). Several recent reports have described that fasudil, a potent Rho-kinase inhibitor and vasodilator, could represent a potential therapeutic option for PH. We designed this study to investigate the hypothesis that the expression level of RhoA is increased in the nitrofen-induced CDH rat model. The expression level of Wnt11, an activator of RhoA, was also evaluated. MethodsPregnant rats were treated with or without nitrofen on gestational day 9 (D9). Fetuses were sacrificed on D17, D19 and D21 and were divided into control and CDH groups. Quantitative real-time polymerase chain reaction was performed to determine the pulmonary gene expression levels of both Wnt11 and RhoA. An immunofluorescence study was also performed to evaluate the expression and localization of RhoA. ResultsThe relative mRNA expression levels of pulmonary Wnt11 and RhoA on D21 were significantly increased in the CDH group compared with the control group (p=0.016 and p=0.008, respectively). The immunofluorescence study confirmed the overexpression of RhoA in the pulmonary vessels of CDH rats on D21. ConclusionsOur results provide evidence that the RhoA/Rho-kinase-mediated pathway is involved in the pathogenesis of PH in the nitrofen-induced CDH rat model. Our data also suggest that the fasudil, a Rho-kinase inhibitor, could represent a therapeutic option for the treatment of PH in CDH.

Prevention of pulmonary hypoplasia and pulmonary vascular remodeling by antenatal simvastatin treatment in nitrofen-induced congenital diaphragmatic hernia.

Congenital diaphragmatic hernia (CDH) has a high mortality rate mainly due to lung hypoplasia and persistent pulmonary hypertension of the newborn (PPHN). Simvastatin has been shown to prevent the development of pulmonary hypertension (PH) in experimental models of PH. We, therefore, hypothesized that antenatal simvastatin would attenuate PPHN in nitrofen-induced CDH in rats. The efficacy of antenatal simvastatin was compared with antenatal sildenafil, which has already been shown to improve pathological features of PPHN in nitrofen-induced CDH. On embryonic day (E) 9.5, nitrofen or vehicle was administered to pregnant Sprague-Dawley rats. On E11, nitrofen-treated rats were randomly assigned to antenatal simvastatin (20 mg·kg(-1)·day(-1) orally), antenatal sildenafil (100 mg·kg(-1)·day(-1) orally), or placebo administration from E11 to E21. On E21, fetuses were delivered by cesarean section, killed, and checked for left-sided CDH. Lung tissue was then harvested for further pathobiological evaluation. In nitrofen-induced CDH, simvastatin failed to reduce the incidence of nitrofen-induced CDH in the offspring and to increase the body weight, but improved the lung-to-body weight ratio and lung parenchyma structure. Antenatal simvastatin restored the pulmonary vessel density and external diameter, and reduced the pulmonary arteriolar remodeling compared with nitrofen-induced CDH. This was associated with decreased lung expression of endothelin precursor, endothelin type A and B receptors, endothelial and inducible nitric oxide synthase, together with restored lung activation of apoptotic processes mainly in the epithelium. Antenatal simvastatin presented similar effects as antenatal therapy with sildenafil on nitrofen-induced CDH. Antenatal simvastatin improves pathological features of lung hypoplasia and PPHN in experimental nitrofen-induced CDH.

Therapeutic potential of mesenchymal stem cell transplantation in a nitrofen-induced congenital diaphragmatic hernia rat model.

The aim of this study was to evaluate the efficacy of mesenchymal stem cells (MSCs) in a nitrofen-induced congenital diaphragmatic hernia (CDH) rat model. Pregnant rats were exposed to nitrofen on embryonic day 9.5 (E9.5). MSCs were isolated from the enhanced green fluorescent protein (eGFP) transgenic rat lungs. The MSCs were transplanted into the nitrofen-induced E12.5 rats via the uterine vein, and the E21 lung explants were harvested. The study animals were divided into three: the control group, the nitrofen-induced left CDH (CDH group), and the MSC-treated nitrofen-induced left CDH (MSC-treated CDH group). The specimens were morphologically analyzed using HE and immunohistochemical staining with proliferating cell nuclear antigen (PCNA), surfactant protein-C (SP-C), and α-smooth muscle actin. The alveolar and medial walls of the pulmonary arteries were significantly thinner in the MSC-treated CDH group than in the CDH group. The alveolar air space areas were larger, while PCNA and the SP-C positive cells were significantly higher in the MSC-treated CDH group, than in the CDH group. MSC engraftment was identified on immunohistochemical staining of the GFP in the MSC-treated CDH group. MSC transplantation potentially promotes alveolar and pulmonary artery development, thereby reducing the severity of pulmonary hypoplasia.

A morphometric investigation of pulmonary sympathetic innervation in nitrofen-induced congenital diaphragmatic hernia rats

1) Abstract Pulmonary hypoplasia influences prognosis in congenital diaphragmatic hernia (CDH) . However the abnormality of pulmonary innervation is not clearly understood. We immunohistochemically examined the lungs of CDH model rats with special reference to sympathetic innervation. Pregnant rats were received nitrofen on gestational day 9 and the fetuses were recovered on gestational day 22. Control animals received only olive oil. Fetal lungs were dissected and the weight was measured. Whole mount sections at the level of main bronchus were immunostained using anti‑tyrosine hydroxylase (TH) antibody as a sympathetic marker. The proportion of area of TH‑immunoreactive nerve fi bers relative to the total lung area was calculated. The mean lung weight of CDH aff ected side was signifi cantly lower than that of ipsilateral side of controls. The percentage of TH‑positive area of CDH affected side was significantly lower than that of unaffected side. The reduction of pulmonary sympathetic innervation may play an important role in respiratory morbidity in CDH.

Amniotic lamellar body count and congenital diaphragmatic hernia in humans and in a rat model

We examined the extent of fetal lung hypoplasia and lung maturation using the amniotic lamellar body count (LBC) in congenital diaphragmatic hernia (CDH). We obtained 30 amniotic fluid samples from human CDH cases during cesarean section. We assessed LBC, magnetic resonance imaging (MRI), and ultrasound findings for predicting the prognosis of CDH. We collected newborn amniotic fluid and lung tissue at embryonic day (E)21 from normal and nitrofen-induced CDH rats (administered 100 mg orally at E9). Amniotic LBCs in rats were measured using light microscopy. In human CDH, LBC was significantly higher in the surviving than in the deceased group (P < 0.01). A significant positive correlation was observed between LBC and percentage of fetal lung volume on MRI (P < 0.001; r = 0.716). In rats, LBC was significantly higher in controls than in CDH rats (P < 0.01) and correlated with fetal lung weight. We conclude that LBC is useful for predicting lung hypoplasia in human CDH after 35 gestational weeks and in a rat model of nitrofen-induced CDH.