BMP4 and LGL1 are Down Regulated in an Ovine Model of Congenital Diaphragmatic Hernia

Decreased β-catenin Protein in Lungs From Human Congenital Diaphragmatic Hernia Archival Pathology Specimens: A Case-control Study

BACKGROUND

Lung hypoplasia contributes to congenital diaphragmatic hernia (CDH) associated morbidity and mortality. Changes in lung wingless-type MMTV integration site family member (Wnt)-signalling and its downstream effector beta-catenin (CTNNB1), which acts as a transcription coactivator, exist in animal CDH models but are not well characterized in humans. We aim to identify changes to Wnt-signalling gene expression in human CDH lungs and hypothesize that pathway expression will be lower than controls.

METHODS

We identified 51 CDH cases and 10 non-CDH controls with archival formalin-fixed paraffin-embedded (FFPE) autopsy lung tissue from 2012 to 2022. 11 liveborn CDH cases and an additional two anterior diaphragmatic hernias were excluded from the study, leaving 38 CDH cases. Messenger ribonucleic acid (mRNA) expression of Wnt-signalling effectors WNT2B and CTNNB1 was determined for 19 CDH cases and 9 controls. A subset of CDH cases and controls lung sections were immunostained for β-catenin. Clinical variables were obtained from autopsy reports.

RESULTS

Median gestational age was 21 weeks. 81% (n = 31) of hernias were left-sided. 47% (n = 18) were posterolateral. Liver position was up in 81% (n = 31) of cases. Defect size was Type C or D in 58% (n = 22) of cases based on autopsy photos, and indeterminable in 42% (n = 16) of cases. WNT2B and CTNNB1 mRNA expression did not differ between CDH and non-CDH lungs. CDH lungs had fewer interstitial cells expressing β-catenin protein than non-CDH lungs (13.2% vs 42.4%; p = 0.006).

CONCLUSION

There appear to be differences in the abundance and/or localization of β-catenin proteins between CDH and non-CDH lungs.

LEVEL OF EVIDENCE

Level III.

TYPE OF STUDY

Case-Control Study.

Opposing Effects of TGFβ and BMP in the Pulmonary Vasculature in Congenital Diaphragmatic Hernia

Background: Pulmonary hypertension is the major cause of morbidity and mortality in congenital diaphragmatic hernia (CDH). Mutations in several genes that encode signaling molecules of the transforming growth factor β (TGFβ) and bone morphogenetic protein (BMP) pathways have previously been associated with CDH. Since studies on the activation of these pathways in CDH are scarce, and have yielded inconsistent conclusions, the downstream activity of both pathways was assessed in the nitrofen-CDH rat model.

Methods and Results: Pregnant Sprague-Dawley rats were treated with nitrofen at embryonic day (E) 9.5 to induce CDH in offspring. At E21, lungs were screened for the expression of key factors of both signaling pathways, at both the mRNA transcript and protein levels. Subsequently, paying particular attention to the pulmonary vasculature, increased phosphorylation of SMAD2, and decreased phosphorylation of Smad5 was noted in the muscular walls of small pulmonary vessels, by immunohistochemistry. This was accompanied by increased proliferation of constituent cells of the smooth muscle layer of these vessels.

Conclusions: Increased activation of the TGFβ pathway and decreased activation of the BMP pathway in the pulmonary vasculature of rats with experimentally-induced CDH, suggesting that the deregulated of these important signaling pathways may underlie the development of pulmonary hypertension in CDH.

Pathogenic variants in E3 ubiquitin ligase RLIM/RNF12 lead to a syndromic X-linked intellectual disability and behavior disorder

RLIM, also known as RNF12, is an X-linked E3 ubiquitin ligase acting as a negative regulator of LIM-domain containing transcription factors and participates in X-chromosome inactivation (XCI) in mice. We report the genetic and clinical findings of 84 individuals from nine unrelated families, eight of whom who have pathogenic variants in RLIM (RING finger LIM domain-interacting protein). A total of 40 affected males have X-linked intellectual disability (XLID) and variable behavioral anomalies with or without congenital malformations. In contrast, 44 heterozygous female carriers have normal cognition and behavior, but eight showed mild physical features. All RLIM variants identified are missense changes co-segregating with the phenotype and predicted to affect protein function. Eight of the nine altered amino acids are conserved and lie either within a domain essential for binding interacting proteins or in the C-terminal RING finger catalytic domain. In vitro experiments revealed that these amino acid changes in the RLIM RING finger impaired RLIM ubiquitin ligase activity. In vivo experiments in rlim mutant zebrafish showed that wild type RLIM rescued the zebrafish rlim phenotype, whereas the patient-specific missense RLIM variants failed to rescue the phenotype and thus represent likely severe loss-of-function mutations. In summary, we identified a spectrum of RLIM missense variants causing syndromic XLID and affecting the ubiquitin ligase activity of RLIM, suggesting that enzymatic activity of RLIM is required for normal development, cognition and behavior.

The effects of tracheal occlusion on Wnt signaling in a rabbit model of congenital diaphragmatic hernia

PURPOSE

Tracheal occlusion (TO) reverses pulmonary hypoplasia (PH) in congenital diaphragmatic hernia (CDH), but its mechanism of action remains poorly understood. Wnt signaling plays a critical role in lung development, but few studies exist. The purpose of our study was to a) confirm that our CDH rabbit model produced PH which was reversed by TO and b) determine the effects of CDH +/- TO on Wnt signaling.

METHODS

CDH was created in fetal rabbits at 23 days, TO at 28 days, and lung collection at 31 days. Lung body weight ratio (LBWR) and mean terminal bronchiole density (MTBD) were determined. mRNA and miRNA expression was determined in the left lower lobe using RT-qPCR.

RESULTS

Fifteen CDH, 15 CDH + TO, 6 sham CDH, and 15 controls survived and were included in the study. LBWR was low in CDH, while CDH + TO was similar to controls (p = 0.003). MTBD was higher in CDH fetuses and restored to control levels in CDH + TO (p < 0.001). Reference genes TOP1, SDHA, and ACTB were consistently expressed within and between treatment groups. miR-33 and MKI67 were increased, and Lgl1 was decreased in CDH + TO.

CONCLUSION

TO reversed pulmonary hypoplasia and stimulated early Wnt signaling in CDH fetal rabbits.

TYPE OF STUDY

Basic science, prospective.

LEVEL OF EVIDENCE

II.

Improving pregnancy outcomes in humans through studies in sheep

Experimental studies that are relevant to human pregnancy rely on the selection of appropriate animal models as an important element in experimental design. Consideration of the strengths and weaknesses of any animal model of human disease is fundamental to effective and meaningful translation of preclinical research. Studies in sheep have made significant contributions to our understanding of the normal and abnormal development of the fetus. As a model of human pregnancy, studies in sheep have enabled scientists and clinicians to answer questions about the etiology and treatment of poor maternal, placental, and fetal health and to provide an evidence base for translation of interventions to the clinic. The aim of this review is to highlight the advances in perinatal human medicine that have been achieved following translation of research using the pregnant sheep and fetus.

Genetic profile of isolated congenital diaphragmatic hernia revealed by targeted next-generation sequencing

BACKGROUND

Congenital diaphragmatic hernia (CDH) is characterized by a defective closure of the diaphragm occurring as an isolated defect in 60% of cases. Lung size, liver herniation, and pulmonary circulation are major prognostic indices. Isolated CDH genetics is heterogeneous and poorly understood. Whether genetic lesions are also outcome determinants has never been explored.

OBJECTIVES

To identify isolated CDH genetic causes, to fine map the mutational burden, and to search for a correlation between the genotype and the disease severity and outcome.

METHODS

Targeted massively parallel sequencing of 143 human and mouse CDH causative and candidate genes in a cohort of 120 fetuses with isolated CDH and detailed outcome measures.

RESULTS

Pathogenic and likely pathogenic variants were identified in 10% of the cohort. These variants affect both known CDH causative genes, namely, ZFPM2, GATA4, and NR2F2, and new genes, namely, TBX1, TBX5, GATA5, and PBX1. In addition, mutation burden analysis identified LBR, CTBP2, NSD1, MMP14, MYOD1, and EYA1 as candidate genes with enrichment in rare but predicted deleterious variants. No obvious correlation between the genotype and the phenotype or short-term outcome has been found.

CONCLUSION

Targeted resequencing identifies a genetic cause in 10% of isolated CDH and identifies new candidate genes.

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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.