MiR-449a Affects Epithelial Proliferation during the Pseudoglandular and Canalicular Phases of Avian and Mammal Lung Development

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.

Exploring new perspectives on congenital diaphragmatic hernia: A comprehensive review

Congenital diaphragmatic hernia (CDH) represents a developmental anomaly that profoundly impacts the embryonic development of both the respiratory and cardiovascular systems. Understanding the influences of developmental defects, their origins, and clinical consequences is of paramount importance for further research and the advancement of therapeutic strategies for this condition. In recent years, groundbreaking studies in the fields of metabolomics and genomics have significantly expanded our knowledge regarding the pathogenic mechanisms of CDH. These investigations introduce novel diagnostic and therapeutic avenues. CDH implies a scarcity of available information within this domain. Consequently, a comprehensive literature review has been undertaken to synthesize existing data, providing invaluable insights into this rare disease. Improved comprehension of the molecular underpinnings of CDH has the potential to refine diagnostic precision and therapeutic interventions, thus potentially enhancing clinical outcomes for CDH patients. The identification of potential biomarkers assumes paramount significance for early disease detection and risk assessment in CDH, facilitating prompt recognition and the implementation of appropriate interventions. The process of translating research findings into clinical practice is significantly facilitated by an exhaustive literature review. It serves as a pivotal step, enabling the integration of novel, more effective diagnostic and therapeutic modalities into the management of CDH patients.

Descriptive and Functional Genomics in Neonatal Respiratory Distress Syndrome: From Lung Development to Targeted Therapies

In this up-to-date study, we first aimed to highlight the genetic and non-genetic factors associated with respiratory distress syndrome (RDS) while also focusing on the genomic aspect of this condition. Secondly, we discuss the treatment options and the progressing therapies based on RNAs or gene therapy. To fulfill this, our study commences with lung organogenesis, a highly orchestrated procedure guided by an intricate network of conserved signaling pathways that ultimately oversee the processes of patterning, growth, and differentiation. Then, our review focuses on the molecular mechanisms contributing to both normal and abnormal lung growth and development and underscores the connections between genetic and non-genetic factors linked to neonatal RDS, with a particular emphasis on the genomic aspects of this condition and their implications for treatment choices and the advancing therapeutic approaches centered around RNAs or gene therapy.

Congenital lung malformations: Dysregulated lung developmental processes and altered signaling pathways

Congenital lung malformations comprise a diverse group of anomalies including congenital pulmonary airway malformation (CPAM, previously known as congenital cystic adenomatoid malformation or CCAM), bronchopulmonary sequestration (BPS), congenital lobar emphysema (CLE), bronchogenic cysts, and hybrid lesions. Little is known about the signaling pathways that underlie the pathophysiology of these lesions and the processes that may promote their malignant transformation. In the last decade, the use of transgenic/knockout animal models and the implementation of next generation sequencing on surgical lung specimens have increased our knowledge on the pathophysiology of these lesions. Herein, we provide an overview of normal lung development in humans and rodents, and we discuss the current state of knowledge on the pathophysiology and molecular pathways that are altered in each congenital lung malformation.

Fetal lung regeneration using stem cell-derived extracellular vesicles: A new frontier for pulmonary hypoplasia secondary to congenital diaphragmatic hernia

The poor outcomes of babies with congenital diaphragmatic hernia (CDH) are directly related to pulmonary hypoplasia, a cosndition characterized by impaired lung development. Although the pathogenesis of pulmonary hypoplasia is not fully elucidated, there is now evidence that CDH patients have missing or dysregulated microRNAs (miRNAs) that regulate lung development. A prenatal therapy that supplements these missing/dysregulated miRNAs could be a strategy to rescue normal lung development. Extracellular vesicles (EVs), also known as exosomes when of small dimensions, are lipid-bound nanoparticles that can transfer their heterogeneous cargo (proteins, lipids, small RNAs) to target cells to induce biological responses. Herein, we review all studies that show evidence for stem cell-derived EVs as a regenerative therapy to rescue normal development in CDH fetal lungs. Particularly, we report studies showing that administration of EVs derived from amniotic fluid stem cells (AFSC-EVs) to models of pulmonary hypoplasia promotes fetal lung growth and maturation via transfer of miRNAs that are known to regulate lung developmental processes. We also describe that stem cell-derived EVs exert effects on vascular remodeling, thus possibly preventing postnatal pulmonary hypertension. Finally, we discuss future perspectives and challenges to translate this promising stem cell EV-based therapy to clinical practice. This article is protected by copyright. All rights reserved.

Developmental Pathways Underlying Lung Development and Congenital Lung Disorders

Lung organogenesis is a highly coordinated process governed by a network of conserved signaling pathways that ultimately control patterning, growth, and differentiation. This rigorously regulated developmental process culminates with the formation of a fully functional organ. Conversely, failure to correctly regulate this intricate series of events results in severe abnormalities that may compromise postnatal survival or affect/disrupt lung function through early life and adulthood. Conditions like congenital pulmonary airway malformation, bronchopulmonary sequestration, bronchogenic cysts, and congenital diaphragmatic hernia display unique forms of lung abnormalities. The etiology of these disorders is not yet completely understood; however, specific developmental pathways have already been reported as deregulated. In this sense, this review focuses on the molecular mechanisms that contribute to normal/abnormal lung growth and development and their impact on postnatal survival.

Intrauterine Hypoxia and Epigenetic Programming in Lung Development and Disease

Clinically, intrauterine hypoxia is the foremost cause of perinatal morbidity and developmental plasticity in the fetus and newborn infant. Under hypoxia, deviations occur in the lung cell epigenome. Epigenetic mechanisms (e.g., DNA methylation, histone modification, and miRNA expression) control phenotypic programming and are associated with physiological responses and the risk of developmental disorders, such as bronchopulmonary dysplasia. This developmental disorder is the most frequent chronic pulmonary complication in preterm labor. The pathogenesis of this disease involves many factors, including aberrant oxygen conditions and mechanical ventilation-mediated lung injury, infection/inflammation, and epigenetic/genetic risk factors. This review is focused on various aspects related to intrauterine hypoxia and epigenetic programming in lung development and disease, summarizes our current knowledge of hypoxia-induced epigenetic programming and discusses potential therapeutic interventions for lung disease.

Fetal lung underdevelopment is rescued by administration of amniotic fluid stem cell extracellular vesicles in rodents

Fetal lung underdevelopment, also known as pulmonary hypoplasia, is characterized by decreased lung growth and maturation. The most common birth defect found in babies with pulmonary hypoplasia is congenital diaphragmatic hernia (CDH). Despite research and clinical advances, babies with CDH still have high morbidity and mortality rates, which are directly related to the severity of lung underdevelopment. To date, there is no effective treatment that promotes fetal lung growth and maturation. Here, we describe a stem cell-based approach in rodents that enhances fetal lung development via the administration of extracellular vesicles (EVs) derived from amniotic fluid stem cells (AFSCs). Using fetal rodent models of pulmonary hypoplasia (primary epithelial cells, organoids, explants, and in vivo), we demonstrated that AFSC-EV administration promoted branching morphogenesis and alveolarization, rescued tissue homeostasis, and stimulated epithelial cell and fibroblast differentiation. We confirmed this regenerative ability in in vitro models of lung injury using human material, where human AFSC-EVs obtained following good manufacturing practices restored pulmonary epithelial homeostasis. Investigating EV mechanism of action, we found that AFSC-EV beneficial effects were exerted via the release of RNA cargo. MicroRNAs regulating the expression of genes involved in lung development, such as the miR17-92 cluster and its paralogs, were highly enriched in AFSC-EVs and were increased in AFSC-EV-treated primary lung epithelial cells compared to untreated cells. Our findings suggest that AFSC-EVs hold regenerative ability for underdeveloped fetal lungs, demonstrating potential for therapeutic application in patients with pulmonary hypoplasia.

Autophagy Is Required for Maturation of Surfactant-Containing Lamellar Bodies in the Lung and Swim Bladder

Autophagy is an intracellular degradation system, but its physiological functions in vertebrates are not yet fully understood. Here, we show that autophagy is required for inflation of air-filled organs: zebrafish swim bladder and mouse lung. In wild-type zebrafish swim bladder and mouse lung type II pulmonary epithelial cells, autophagosomes are formed and frequently fuse with lamellar bodies. The lamellar body is a lysosome-related organelle that stores a phospholipid-containing surfactant complex that lines the air-liquid interface and reduces surface tension. We find that autophagy is critical for maturation of the lamellar body. Accordingly, atg-deficient zebrafish fail to maintain their position in the water, and type-II-pneumocyte-specific Fip200-deficient mice show neonatal lethality with respiratory failure. Autophagy suppression does not affect synthesis of the surfactant phospholipid, suggesting that autophagy supplies lipids and membranes to lamellar bodies. These results demonstrate an evolutionarily conserved role of autophagy in lamellar body maturation.

miRNAs in Lung Development and Diseases

The development of the lung involves a diverse group of molecules that regulate cellular processes, organ formation, and maturation. The various stages of lung development are marked by accumulation of small RNAs that promote or repress underlying mechanisms, depending on the physiological environment in utero and postnatally. To some extent, the pathogenesis of various lung diseases is regulated by small RNAs. In this review, we discussed miRNAs regulation of lung development and diseases, that is, COPD, asthma, pulmonary fibrosis, and pulmonary arterial hypertension, and also highlighted possible connotations for human lung health.

Heterochronic regulation of lung development via the Lin28-Let-7 pathway

The heterochronic gene Lin28 regulates diverse developmental processes. It was shown previously that global Lin28A overexpression during mouse embryogenesis results in perinatal lethality. However, the reason for this early lethality has not been elucidated. Here, we showed that Lin28A overexpression prevents normal lung development via the inhibition of the Let-7 micro RNAs, thus causing the perinatal lethality. We further found that Lin28A overexpression in lung mesenchymal cells, but not epithelial cells, is sufficient to recapitulate the lung phenotype. Moreover, we defined the specific time window wherein Lin28A expression exerts its effect. Deep characterization of the transgenic lungs suggests that the Lin28A-Let-7 pathway delays the transition from one developmental stage to another but does not completely abrogate the differentiation capacity of the lung progenitor cells. Finally, we suggested that the effect of Lin28A-Let-7 on embryonic lung development is mediated at least in part through the TGF-β1-signaling pathway. Altogether, these findings define for the first time the Lin28-Let-7 pathway as a critical heterochronic regulator of lung development.-Komarovsky Gulman, N., Armon, L., Shalit, T., Urbach, A. Heterochronic regulation of lung development via the Lin28-Let-7 pathway.

Elevated Krüppel-like factor 5 expression in spatiotemporal mouse lungs is similar to human congenital cystic adenomatoid malformation of the lungs

Objective

The study aimed to investigate the role of high Krüppel-like factor 5 (KLF5) expression on the pathogenesis of congenital cystic adenomatoid malformation of the lungs (CCAML) in mice.

Methods

A mouse model of high KLF5 expression in the lungs was established. KLF5 expression and the pulmonary lumen diameter were examined by immunohistochemistry to determine a successful model. Basement membrane damage and activity of matrix metalloproteinase-9 (MMP-9) were examined. After an adenovirus carrying KLF5 gene transfection in lung adenocarcinoma (H441) was created, changes in expression and activity of MMP-9 were determined.

Results

In a mouse model with high KLF5 expression, the pulmonary lumen was markedly enlarged, indicating establishment of CCAML. The basement membrane was degraded, and MMP-9 activity was significantly higher in the model group compared with the control group. Moreover, mice in a cellular model after transfection also showed higher MMP-9 activity than did controls.

Conclusion

High KLF5 expression may play a pivotal role in the pathogenesis of CCAML, partly through regulating the activity of MMP-9.

Effects and molecular mechanisms of intrauterine infection/inflammation on lung development

BACKGROUND

Intrauterine infection/inflammation plays an important role in the development of lung injury and bronchopulmonary dysplasia (BPD) in preterm infants, While a multifactorial genesis is likely, mechanisms involved in BPD after intrauterine infection/inflammation are largely unknown. Recent studies have suggested microRNAs (miRNAs) are likely to play a role. Therefore, this study aimed to study the effects and mechanisms of intrauterine infection/inflammation on lung development, and to identify miRNAs related to lung injury and BPD.

METHODS

An animal model of intrauterine infection/inflammation was established with pregnant SD rats endocervically inoculated with E.coli. The fetal and neonatal rats were observed at embryonic day (E) 17, 19, 21 and postnatal day (P) 1, 3, 7, 14, respectively. Body weight, lung weight, the expression levels of NLRP3, TNF-α, IL-lβ, IL-6, VEGF, Collagen I, SP-A, SP-B and SP-C in the lung tissues of fetal and neonatal rats were measured. Expression profiles of 1218 kinds of miRNAs in the lungs of neonatal rats were detected by miRNA microarray technique. Target genes of the identified miRNAs were predicted through online software.

RESULTS

Intrauterine infection/inflammation compromised not only weight development but also lung development of the fetal and neonatal rats. The results showed significantly increased expression of NLRP3, TNF-α, IL-1β, IL-6, Collagen I, and significantly decreased expression of VEGF, SP-A, SP-B and SP-C in the fetal and neonatal rat lung tissues in intrauterine infection group compared to the control group at different observation time point (P < 0.05). Forty-three miRNAs with significant differential expression were identified. Possible target genes regulated by the identified miRNAs are very rich.

CONCLUSIONS

Intrauterine infection/inflammation results in lung histological changes which are very similar to those observed in BPD. Possible mechanisms may include NLRP3 inflammasome activation followed by inflammatory cytokines expression up-regulated, inhibiting the expression of pulmonary surfactant proteins, interfering with lung interstitial development. There are many identified miRNAs which target a wide range of genes and may play an important role in the processes of lung injury and BPD.

Lung microRNA deregulation associated with impaired alveolarization in rats after intrauterine growth restriction

Intrauterine growth restriction (IUGR) was recently described as an independent risk factor of bronchopulmonary dysplasia, the main respiratory sequelae of preterm birth. We previously showed impaired alveolarization in rat pups born with IUGR induced by a low-protein diet (LPD) during gestation. We conducted a genome-wide analysis of gene expression and found the involvement of several pathways such as cell adhesion. Here, we describe our unbiased microRNA (miRNA) profiling by microarray assay and validation by qPCR at postnatal days 10 and 21 (P10 and P21) in lungs of rat pups with LPD-induced lung-alveolarization disorder after IUGR. We identified 13 miRNAs with more than two-fold differential expression between control lungs and LPD-induced IUGR lungs. Validated and predicted target genes of these miRNAs were related to “tissue repair” at P10 and “cellular communication regulation” at P21. We predicted the deregulation of several genes associated with these pathways. Especially, E2F3, a transcription factor involved in cell cycle control, was expressed in developing alveoli, and its mRNA and protein levels were significantly increased at P21 after IUGR. Hence, IUGR affects the expression of selected miRNAs during lung alveolarization. These results provide a basis for deciphering the mechanistic contributions of IUGR to impaired alveolarization.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.

Polygenic Causes of Congenital Diaphragmatic Hernia Produce Common Lung Pathologies

Congenital diaphragmatic hernia (CDH) is one of the most common and lethal congenital anomalies, and significant evidence is available in support of a genetic contribution to its etiology, including single-gene knockout mice associated with diaphragmatic defects, rare monogenetic disorders in humans, familial aggregation, and association of CDH with chromosomal abnormalities. Structural lung defects in the form of lung hypoplasia are almost invariably seen in patients with CDH and frequently in animal models of this condition. Better understanding of the mechanisms of pulmonary defects in CDH has the potential for creating targeted therapies, particularly in postnatal stages, when therapeutics can have maximum clinical impact on the surviving cohorts. Successful treatment of CDH is dependent on the integration of human genomic and genetic data with developmental expression profiling, mouse knockouts, and gene network and pathway modeling, which have generated a large number of candidate genes and pathways for follow-up studies. In particular, defective alveolarization appears to be a common and potentially actionable phenotype in both patients and animal models.

MicroRNA-based screens for synthetic lethal interactions with c-Myc

microRNAs (miRs) are small, non-coding RNAs, which play crucial roles in the development and progression of human cancer. Given that miRs are stable, easy to synthetize and readily introduced into cells, they have been viewed as having potential therapeutic benefit in cancer. c-Myc (Myc) is one of the most commonly deregulated oncogenic transcription factors and has important roles in the pathogenesis of cancer, thus making it an important, albeit elusive therapeutic target. Here we review the miRs that have been identified as being both positive and negative targets for Myc and how these participate in the complex phenotypes that arise as a result of Myc-driven transformation. We also discussseveral recent reports of Myc-synthetic lethal interactions with miRs.These highlight the importance and complexity of miRs in Myc-mediated biological functions and the opportunities for Myc-driven human cancer therapies.