Overactivated Epithelial NF-κB Disrupts Lung Development in Congenital Diaphragmatic Hernia

From past to present: A bibliometric and visualized study of the most impactful publications on congenital diaphragmatic hernia (CDH)

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a severe birth defect characterized by significant infant mortality and morbidity. While numerous articles have been published on CDH, little is known about the characteristics of the most impactful articles. In this study, we aimed to identify and characterize the most important publications in the CDH field from a bibliometric perspective.

METHODS

Articles addressing CDH were retrieved in October 2024 from the Web of Science™ and ranked by citation number. The top 100 publications were analyzed for their bibliometric parameters including number of citations, subject of study, level of evidence, country of origin, journals and publication year. A visualized study of identified articles was performed using the VOSviewer software.

RESULTS

In total, 4,637 publications with 84,163 citations from 713 journals were identified. The 100 most cited papers were published between 1962 and 2018, mainly in the Journal of Pediatric Surgery (37%). The USA was the leading country for number of publication and degree of collaboration with other countries. Citations per article ranged from 117 to 497 (median 162). Retrospective studies (36%) and studies with low evidence level IV (41%) dominated. The terms CDH, extracorporeal membrane oxygenation (ECMO), survival, pulmonary hypoplasia, preoperative stabilization, prenatal diagnosis, high frequency oscillatory ventilation (HFOV) and fetoscopic endoluminal tracheal occlusion (FETO) were identified as high-frequency keywords in co-occurrence analysis. Morbidity and mortality (21%), surgical management (16%) and animal model research (14%) were the top three topics of interest.

CONCLUSIONS

Our findings identify the most referenced works, including the countries and journals of origin, in CDH over the past five decades. These manuscripts highlight advances in the understanding and management, with an increased focus on prenatal diagnosis, long-term outcomes and innovative treatments. However, the field remains hindered by a lack of high-level evidence studies, underscoring the need for more randomized controlled trials and translational research to improve clinical outcomes.

LEVEL OF EVIDENCE

IV.

Prenatal VEGF Nanodelivery Reverses Congenital Diaphragmatic Hernia-associated Pulmonary Abnormalities

Rationale: Congenital diaphragmatic hernia (CDH) results in lung hypoplasia. In severe cases, tracheal occlusion (TO) can be offered to promote lung growth. However, the benefit is limited, and novel treatments are required to supplement TO. VEGF (vascular endothelial growth factor) is downregulated in animal models of CDH and could be a therapeutic target, but its role in human CDH is not known. Objectives: To investigate whether VEGF supplementation could be a suitable treatment for CDH-associated lung pathology. Methods: Fetal lungs from patients with CDH were used to determine pulmonary morphology and VEGF expression. A novel human ex vivo model of fetal lung compression recapitulating CDH features was developed and used to determine the effect of exogenous VEGF supplementation. A nanoparticle-based approach for intrapulmonary delivery of VEGF was developed by conjugating it on functionalized nanodiamonds, which was tested in experimental CDH in vivo. Measurements and Main Results: VEGF expression was downregulated in the distal pulmonary epithelium of human CDH fetuses in conjunction with attenuated cell proliferation. The compression model resulted in impaired branching morphogenesis similar to CDH and downregulation of VEGF expression in conjunction with reduced proliferation of terminal bud epithelial progenitors; these could be reversed by exogenous supplementation of VEGF. Prenatal delivery of VEGF with the functionalized nanodiamond VEGF platform in CDH fetal rats resulted in lung growth and pulmonary arterial remodeling that was complementary to that achieved by TO alone with appearances comparable to healthy controls. Conclusions: This innovative approach could have a significant impact on the treatment of CDH.

Fetal Tracheal Occlusion Correlates with Normalized YAP Expression and Alveolar Epithelial Differentiation in Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is characterized by incomplete closure of the diaphragm. Although the ensuing compression to the fetal lung causes lung hypoplasia, specific cellular phenotypes and developmental signaling defects in the alveolar epithelium in CDH are not fully understood. Employing lung samples from human CDH, a surgical lamb model, and a nitrofen rat model, we investigated whether lung compression impairs alveolar epithelial differentiation and Yes-associated protein (YAP)-mediated mechanosensing. We showed that CDH in humans and lambs caused defective alveolar epithelial differentiation manifested by more alveolar epithelial type II (ATII) cells, fewer ATI cells, and the emergence of cells coexpressing ATI and ATII markers. Associated with these alveolar epithelial defects, we found a decrease in the level and nuclear localization of YAP. Reduced YAP and abnormal distal lung development were evident as early as 21 weeks of gestation in human CDH. In addition, rat fetuses with CDH also showed diminished nuclear YAP and more abundant ATII cells. In contrast, the littermates without the hernia had no such alveolar phenotypes. Furthermore, fetal tracheal occlusion in the surgical lamb model of CDH fully normalized nuclear YAP and rescued alveolar epithelial defects in a gestational age-dependent manner. Taken together, our findings across species indicate that lung compression in CDH is sufficient to disrupt alveolar epithelial differentiation and impair YAP signaling. Tracheal occlusion can restore nuclear YAP and rescue the alveolar defects in CDH, depending on the timing and the duration of this prenatal surgical intervention.

Epithelial Dysfunction in Congenital Diaphragmatic Hernia: Mechanisms, Models and Emerging Therapies

Congenital diaphragmatic hernia (CDH) is a complex disorder whereby improper formation of the diaphragm allows herniation of the internal organs into the thoracic cavity, resulting in pulmonary hypoplasia among other complications. Although epithelial dysfunction is central to CDH pathology, relatively little attention has been paid to the underlying mechanisms orchestrating epithelial malfunction. Proinflammatory signaling downstream of impaired mechanotransduction due to in utero lung compression has been elucidated to drive epithelial cell phenotypes. This has been illustrated by a reduction in nuclear YAP and the upregulation of NF-kB in CDH models. In this review, we draw from recent findings using emerging technologies to examine epithelial cell mechanisms in CDH and discuss the role of compression as a central and, crucially, sufficient driver of CDH phenotypes. In recognition of the limitations of using genetic knockout models to recapitulate such a heterogenic and etiologically complicated disease, we discuss alternative models such as the established nitrofen rat model, air-liquid interface (ALI) cultures, organoids and ex vivo lung explants. Throughout, we acknowledge the importance of involving mechanical compression in the modeling of CDH in order to faithfully recapitulate the disease. Finally, we explore novel therapeutic strategies from stem cell and regenerative therapies to precision medicine and the importance of defining CDH endotypes in order to guide treatments.

Comparative Transcriptome Analysis of Human and Mouse Canalicular Lungs in Fetal Diaphragmatic Hernia

BACKGROUND

The nitrofen model of congenital diaphragmatic hernia (CDH) is widely used in translational research. However, the molecular pathways associated with pulmonary hypoplasia in this model compared to the human CDH phenotype have not been well described. The aim of this study was to investigate differentially expressed genes (DEG) and signaling pathways in early stage fetal lungs in mouse and human CDH.

METHODS

CDH lung tissue was obtained from human fetuses (21-23 weeks gestation) and nitrofen mouse pups (E15.5). NovaSeq Flowcell RNA-seq was performed to evaluate differentially expressed transcriptional and molecular pathways (DEGs) in fetal mice with CDH, compared with age-matched normal mouse lungs and human CDH samples.

RESULTS

There were thirteen overlapping DEGs in human and mouse CDH lung samples compared to controls. These genes were involved in extracellular matrix, myogenesis, cilia, and immune modulation pathways. Human CDH was associated with an upregulation of collagen formation and extracellular matrix reorganization whereas mouse CDH was associated with an increase in muscular contraction. The most common cell types upregulated in human and mouse CDH samples were ciliated airway cells.

CONCLUSIONS

This study highlights the unique gene transcriptional patterns in early fetal mouse and human lungs with CDH. These data have implications when determining the translational potential of novel therapies in CDH using nitrofen-based animal models.

LEVEL OF EVIDENCE

Level IV.

STUDY TYPE

Basic science/case series.

Sex-specific differences in the severity of pulmonary hypoplasia in experimental congenital diaphragmatic hernia and implications for extracellular vesicle-based therapy

PURPOSE

Amniotic fluid stem cell extracellular vesicles (AFSC-EVs) hold regenerative potential to treat hypoplastic lungs secondary to congenital diaphragmatic hernia (CDH). This study aims to investigate sex-specific differences in pulmonary hypoplasia severity and responses to AFSC-EV administration in an experimental CDH mouse model.

METHODS

C57BL/6J dams were fed with nitrofen + bisdiamine (left-sided CDH) or olive oil only (control) at embryonic day (E) 8.5. Lungs were dissected (E18.5), grown ex vivo and treated with medium ± AFSC-EVs that were collected via ultracentrifugation and characterized (nanoparticle tracking analysis, electron microscopy, Western blotting). Pulmonary hypoplasia was assessed via mean linear intercept (MLI). Gene and protein expression changes (Cd31, Enos, Il1b, TNFa) were measured via RT-qPCR and immunofluorescence. Pups were genotyped for Sry.

RESULTS

Experimental CDH showed a male predominance without sex differences for pulmonary hypoplasia severity, fetal lung vascularization, and inflammation. AFSC-EV administration led to improved lung growth (decreased MLI), improved fetal lung vascularization (increased Cd31 and Enos), and decreased fetal lung inflammation (Il1b, TNFa). There was no sex-specific response to AFSC-EV administration.

CONCLUSION

This study shows sex-independent impaired lung growth, vascularization and fetal lung inflammation in a CDH mouse model. Antenatal administration of AFSC-EVs reverses aspects of pulmonary hypoplasia secondary to CDH independent of the biological sex.

Cellular origins and translational approaches to congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is a complex developmental abnormality characterized by abnormal lung development, a diaphragmatic defect and cardiac dysfunction. Despite significant advances in management of CDH, mortality and morbidity continue to be driven by pulmonary hypoplasia, pulmonary hypertension, and cardiac dysfunction. The etiology of CDH remains unknown, but CDH is presumed to be caused by a combination of genetic susceptibility and external/environmental factors. Current research employs multi-omics technologies to investigate the molecular profile and pathways inherent to CDH. The aim is to discover the underlying pathogenesis, new biomarkers and ultimately novel therapeutic targets. Stem cells and their cargo, non-coding RNAs and agents targeting inflammation and vascular remodeling have produced promising results in preclinical studies using animal models of CDH. Shortcomings in current therapies combined with an improved understanding of the pathogenesis in CDH have given rise to novel promising experimental treatments that are currently being evaluated in clinical trials. This review provides insight into current developments in translational research, ranging from the cellular origins of abnormal cardiopulmonary development in CDH and the identification of novel treatment targets in preclinical CDH models at the bench and their translation to clinical trials at the bedside.

Fetal hypoplastic lungs have multilineage inflammation that is reversed by amniotic fluid stem cell extracellular vesicle treatment

Antenatal administration of extracellular vesicles from amniotic fluid stem cells (AFSC-EVs) reverses features of pulmonary hypoplasia in models of congenital diaphragmatic hernia (CDH). However, it remains unknown which lung cellular compartments and biological pathways are affected by AFSC-EV therapy. Herein, we conducted single-nucleus RNA sequencing (snRNA-seq) on rat fetal CDH lungs treated with vehicle or AFSC-EVs. We identified that intra-amniotically injected AFSC-EVs reach the fetal lung in rats with CDH, where they promote lung branching morphogenesis and epithelial cell differentiation. Moreover, snRNA-seq revealed that rat fetal CDH lungs have a multilineage inflammatory signature with macrophage enrichment, which is reversed by AFSC-EV treatment. Macrophage enrichment in CDH fetal rat lungs was confirmed by immunofluorescence, flow cytometry, and inhibition studies with GW2580. Moreover, we validated macrophage enrichment in human fetal CDH lung autopsy samples. Together, this study advances knowledge on the pathogenesis of pulmonary hypoplasia and further evidence on the value of an EV-based therapy for CDH fetuses.

Prenatal Brain Maturation is Delayed in Neonates with Congenital Diaphragmatic Hernia

OBJECTIVE

To assess brain development in fetuses with congenital diaphragmatic hernia (CDH) using a fetal Total Maturation Score (fTMS).

STUDY DESIGN

This is a retrospective cohort study using data from a single-center clinical registry. Neonates with an antenatal diagnosis of CDH between 2014 and 2020 and prenatal brain magnetic resonance imaging (MRI) (n = 48) were included. We compared our study sample with historical healthy controls (n = 48). The relationship between fTMS and gestational age (GA), as well as the association between fTMS and key prenatal variables and placental pathologic findings, were evaluated.

RESULTS

Compared with healthy controls, neonates with CDH had a significant delay in fTMS (P value <.001). Within the CDH cohort, there was no significant difference in fTMS based on CDH severity, intrathoracic liver position, right vs left CDH, sex, presence of abnormal echocardiogram findings, treatment with extracorporeal membrane oxygenation (ECMO), or in-hospital mortality. Placentas of neonates with CDH had a high proportion of fetal vascular malperfusion (56%) and chronic inflammation (67%), and relatively large placentas had a protective effect on prenatal brain maturation (P value = .025).

CONCLUSIONS

Prenatal brain maturation in neonates with CDH is delayed. Placental pathology may influence fetal brain development. The etiology and clinical impact of prenatal brain immaturity in neonates with CDH warrant further investigation.