CD34+ stromal cells/telocytes and their role in mouse lung development: Light microscopy, immunofluorescence, ultrastructural and scanning electron microscopy evidence.

Telocytes (TCs), a novel type of mesenchymal or interstitial cell with specific, very long and thin cellular prolongations, have been found in various mammalian organs and have potential biological functions. However, their existence during lung development is poorly understood. This study aimed to investigate the existence, morphological features, and role of CD34+ SCs/TCs in mouse lungs from foetal to postnatal life using primary cell culture, double immunofluorescence, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The immunofluorescence double staining profiles revealed positive expression of CD34 and PDGFR-α, Sca-1 or VEGFR-3, and the expression of these markers differed among the age groups during lung development. Intriguingly, in the E18.5 stage of development, along with the CD34+ SCs/TCs, haematopoietic stem cells and angiogenic factors were also significantly increased in number compared with those in the E14.5, E16.5, P0 and P7. Subsequently, TEM confirmed that CD34+ SCs/TCs consisted of a small cell body with long telopodes (Tps) that projected from the cytoplasm. Tps consisted of alternating thin and thick segments known as podomers and podoms. TCs contain abundant endoplasmic reticulum, mitochondria and secretory vesicles and establish close connections with neighbouring cells. Furthermore, SEM revealed characteristic features, including triangular, oval, spherical, or fusiform cell bodies with extensive cellular prolongations, depending on the number of Tps. Our findings provide evidence for the existence of CD34+ SCs/TCs, which contribute to vasculogenesis, the formation of the air‒blood barrier, tissue organization during lung development and homoeostasis.

Nrf2 deficiency exacerbated pulmonary pyroptosis in maternal hypoxia-induced intrauterine growth restriction offspring mice.

Maternal prenatal hypoxia is an important contributor to intrauterine growth restriction (IUGR), which impedes fetal lung maturation and leads to the development of chronic lung diseases. Although evidence suggests the involvement of pyroptosis in IUGR, the molecular mechanism of pyroptosis is still unclear. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been found to potentially interact with gasdermin D (GSDMD), the key protein responsible for pyroptosis, indicating its crucial role in inhibiting pyroptosis. Therefore, we hypothesized that Nrf2 deficiency is a key molecular responsible for lung pyroptosis in maternal hypoxia-induced IUGR offspring mice. Pregnant WT and Nrf2-/- mice were exposed to hypoxia (10.5 % O2) to mimic IUGR model. We assessed body weight, lung histopathology, pulmonary angiogenesis, oxidative stress levels, as well as mRNA and protein expressions related to inflammation in the 2-week-old offspring. Additionally, we conducted a dual-luciferase reporter assay to confirm the targeting relationship between Nrf2 and GSDMD. Our findings revealed that offspring with maternal hypoxia-induced IUGR exhibited reduced birth weight, catch-up growth delay, and pulmonary dysplasia. Furthermore, we observed impaired nuclear translocation of Nrf2 and increased GSDMD-mediated pyroptosis in these offspring with IUGR. Moreover, the dual-luciferase reporter assay demonstrated that Nrf2 could directly inhibit GSDMD transcription; deficiency of Nrf2 exacerbated pyroptosis and pulmonary dysplasia in offspring with maternal hypoxia-induced IUGR. Collectively, our findings suggest that Nrf2 deficiency induces GSDMD-mediated pyroptosis and pulmonary dysplasia in offspring with maternal hypoxia-induced IUGR; thus highlighting the potential therapeutic approach of targeting Nrf2 for treating prenatal hypoxia-induced pulmonary dysplasia in offspring.

Correlation of fetal lung area with MRI derived pulmonary volume.

BACKGROUND: Neonatal chest-Xray (CXR)s are commonly performed as a first line investigation for the evaluation of respiratory complications. Although lung area derived from CXRs correlates well with functional assessments of the neonatal lung, it is not currently utilised in clinical practice, partly due to the lack of reference ranges for CXR-derived lung area in healthy neonates. Advanced MR techniques now enable direct evaluation of both fetal pulmonary volume and area. This study therefore aims to generate reference ranges for pulmonary volume and area in uncomplicated pregnancies, evaluate the correlation between prenatal pulmonary volume and area, as well as to assess the agreement between antenatal MRI-derived and neonatal CXR-derived pulmonary area in a cohort of fetuses that delivered shortly after the antenatal MRI investigation. METHODS: Fetal MRI datasets were retrospectively analysed from uncomplicated term pregnancies and a preterm cohort that delivered within 72 h of the fetal MRI. All examinations included T2 weighted single-shot turbo spin echo images in multiple planes. In-house pipelines were applied to correct for fetal motion using deformable slice-to-volume reconstruction. An MRI-derived lung area was manually segmented from the average intensity projection (AIP) images generated. Postnatal lung area in the preterm cohort was measured from neonatal CXRs within 24 h of delivery. Pearson correlation coefficient was used to correlate MRI-derived lung volume and area. A two-way absolute agreement was performed between the MRI-derived AIP lung area and CXR-derived lung area. RESULTS: Datasets from 180 controls and 10 preterm fetuses were suitable for analysis. Mean gestational age at MRI was 28.6 ± 4.2 weeks for controls and 28.7 ± 2.7 weeks for preterm neonates. MRI-derived lung area correlated strongly with lung volumes (p < 0.001). MRI-derived lung area had good agreement with the neonatal CXR-derived lung area in the preterm cohort [both lungs = 0.982]. CONCLUSION: MRI-derived pulmonary area correlates well with absolute pulmonary volume and there is good correlation between MRI-derived pulmonary area and postnatal CXR-derived lung area when delivery occurs within a few days of the MRI examination. This may indicate that fetal MRI derived lung area may prove to be useful reference ranges for pulmonary areas derived from CXRs obtained in the perinatal period.

Defective mesenchymal Bmpr1a-mediated BMP signaling causes congenital pulmonary cysts.

Abnormal lung development can cause congenital pulmonary cysts, the mechanisms of which remain largely unknown. Although the cystic lesions are believed to result directly from disrupted airway epithelial cell growth, the extent to which developmental defects in lung mesenchymal cells contribute to abnormal airway epithelial cell growth and subsequent cystic lesions has not been thoroughly examined. In the present study using genetic mouse models, we dissected the roles of bone morphogenetic protein (BMP) receptor 1a (Bmpr1a)-mediated BMP signaling in lung mesenchyme during prenatal lung development and discovered that abrogation of mesenchymal Bmpr1a disrupted normal lung branching morphogenesis, leading to the formation of prenatal pulmonary cystic lesions. Severe deficiency of airway smooth muscle cells and subepithelial elastin fibers were found in the cystic airways of the mesenchymal Bmpr1a knockout lungs. In addition, ectopic mesenchymal expression of BMP ligands and airway epithelial perturbation of the Sox2-Sox9 proximal-distal axis were detected in the mesenchymal Bmpr1a knockout lungs. However, deletion of Smad1/5, two major BMP signaling downstream effectors, from the lung mesenchyme did not phenocopy the cystic abnormalities observed in the mesenchymal Bmpr1a knockout lungs, suggesting that a Smad-independent mechanism contributes to prenatal pulmonary cystic lesions. These findings reveal for the first time the role of mesenchymal BMP signaling in lung development and a potential pathogenic mechanism underlying congenital pulmonary cysts.

Congenital disorders are medical conditions that are present from birth. Although many congenital disorders are rare, they can have a severe impact on the quality of life of those affected. For example, congenital pulmonary airway malformation (CPAM) is a rare congenital disorder that occurs in around 1 out of every 25,000 pregnancies. In CPAM, abnormal, fluid-filled sac-like pockets of tissue, known as cysts, form within the lungs of unborn babies. After birth, these cysts become air-filled and do not behave like normal lung tissue and stop a baby's lungs from working properly. In severe cases, babies with CPAM need surgery immediately after birth. We still do not understand exactly what the underlying causes of CPAM might be. CPAM is not considered to be hereditary ­ that is, it does not appear to be passed down in families ­ nor is it obviously linked to any environmental factors. CPAM is also very difficult to study, because researchers cannot access tissue samples during the critical early stages of the disease. To overcome these difficulties, Luo et al. wanted to find a way to study CPAM in the laboratory. First, they developed a non-human animal 'model' that naturally forms CPAM-like lung cysts, using genetically modified mice where the gene for the signaling molecule Bmpr1a had been deleted in lung cells. Normally, Bmpr1a is part of a set of the molecular instructions, collectively termed BMP signaling, which guide healthy lung development early in life. However, mouse embryos lacking Bmpr1a developed abnormal lung cysts that were similar to those found in CPAM patients, suggesting that problems with BMP signalling might also trigger CPAM in humans. Luo et al. also identified several other genes in the Bmpr1a-deficient mouse lungs that had abnormal patterns of activity. All these genes were known to be controlled by BMP signaling, and to play a role in the development and organisation of lung tissue. This suggests that when these genes are not controlled properly, they could drive formation of CPAM cysts when BMP signaling is compromised. This work is a significant advance in the tools available to study CPAM. Luo et al.'s results also shed new light on the molecular mechanisms underpinning this rare disorder. In the future, Luo et al. hope this knowledge will help us develop better treatments for CPAM, or even help to prevent it altogether.

Effect of estrogen receptor α on cardiopulmonary adaptation to chronic developmental hypoxia in a rat model.

Humans living at high-altitude (HA) have adapted to this environment by increasing pulmonary vascular and alveolar growth. RNA sequencing data from a novel murine model that mimics this phenotypical response to HA suggested estrogen signaling via estrogen receptor alpha (ERα) may be involved in this adaptation. We hypothesized ERα was a key mediator in the cardiopulmonary adaptation to chronic hypoxia and sought to delineate the mechanistic role ERα contributes to this process by exposing novel loss-of-function ERα mutant (ERαMut) rats to simulated HA. ERα mutant or wild-type (wt) rats were exposed to normoxia or hypoxia starting at conception and continued postnatally until 6 wk of age. Both wt and ERαMut animals born and raised in hypoxia exhibited lower body mass and higher hematocrits, total alveolar volumes (Va), diffusion capacities of carbon monoxide (DLCO), pulmonary arteriole (PA) wall thickness, and Fulton indices than normoxia animals. Right ventricle adaptation was maintained in the setting of hypoxia. Although no major physiologic differences were seen between wt and ERαMut animals at either exposure, ERαMut animals exhibited smaller mean linear intercepts (MLI) and increased PA total and lumen areas. Hypoxia exposure or ERα loss-of-function did not affect lung mRNA abundance of vascular endothelial growth factor, angiopoietin 2, or apelin. Sexual dimorphisms were noted in PA wall thickness and PA lumen area in ERαMut rats. In summary, in room air-exposed rats and rats with peri- and postnatal hypoxia exposure, ERα loss-of-function was associated with decreased alveolar size (primarily driven by hypoxic animals) and increased PA remodeling.NEW & NOTEWORTHY By exposing novel loss-of-function estrogen receptor alpha (Erα) mutant rats to a novel model of human high-altitude exposure, we demonstrate that ERα has subtle but inconsistent effects on endpoints relevant to cardiopulmonary adaptation to chronic hypoxia. Given that we observed some histologic, sex, and genotype differences, further research into cell-specific effects of ERα during hypoxia-induced cardiopulmonary adaptation is warranted.

Ameliorative mechanism of dietary vitamin d and magnesium on newborn's pulmonary toxicity induced by cadmium.

Cadmium (Cd) exposure in mothers can cause respiratory issues in newborns, but the exact toxicity mechanisms are not fully understood. Vitamin D deficiency in Cd-exposed rats is associated with increased cadmium accumulation in tissues. Finding a cost-effective medication that is vital for the body while also reducing the effects of poisoning is crucial in treating poisonings. To investigate the mechanisms of Cd-induced lung toxicity, we examined the impact of prolonged Cd exposure in female rats before pregnancy on newborn lung health, focusing on sera TNF-α level, lung P53, Foxo1 mRNA, and lung VEGF, and BMP-4 protein level. A total of 50 rats were divided into control, Cd, Cd+Vitamin D, Cd+Mg, and Cd + Vitamin D+Mg groups. Cd exposure resulted in higher serum TNF-α levels and a significant rise in P53 mRNA levels. Additionally, the occurrence of hemorrhage, inflammatory cell infiltration, and thickening of alveolar walls decreased following treatment with vitamin D + Mg. Although Cd did not affect the newborns' body weight, it did impair their lung function. These findings suggest that the Cd-induced increase in the P53 gene expression could be alleviated by vitamin D and Mg, along with the elevation of VEGF and BMP-4 proteins and Foxo1 gene expression. The study revealed that environmental toxins can sometimes harm molecules and proteins, leading to damage in critical fetal tissues. However, these issues can be mitigated through essential supplements. STRUCTURED ABSTRACT: The increasing role of Cd in the erratic behavior of numerous biological and molecular entities, notably the development of fetal lung tissue, has made it beneficial to investigate the possible adverse effects of Cd exposure in pregnant mothers and fetal organ development, where instinctive molecular events occur. Researchers are encouraged to create new aspects of medications to reduce clinical symptoms and improve the quality of life due to exposure to metal toxins, particularly in industrialized countries. The present study aimed to evaluate histopathological and molecular modifications of fetal lungs caused by maternal Cd toxicosis and evaluate the possible ameliorating effects of vitamin D and Mg alone and in combination with fetal lung developmental abnormalities, followed by maternal toxin induction, which can be generalized to humans. Fifty female Wistar rats were purchased from the Pasteur Institute of Iran. To induce the model, cadmium at a dose of 2 mg/kg body weight was injected intraperitoneally into the female rats over 28 days before mating (5 days after injection in a week). Afterward, the female rats were randomly divided into type IV polycarbonate cages and mated with healthy male rats. The pregnancy was confirmed by observation of the vaginal plaque, which was subsequently observed, and the number of days of embryo formation was calculated. Subsequently, the pregnant rats were assigned to the following groups and received PBS, vitamin D, Mg, or vitamin D + Mg. At the end of the nine-day treatment period (the 6th day of pregnancy to the 14th day), the neonates were born vaginally, and their body weight and mortality were recorded. The P53 and Foxo1 gene expression levels in the left and right lobes of the homogenized lungs of the newborns in each group were assessed. TNF-alpha was detected in the sera collected from the newborns by ELISA. The isolated left and right lung tissues were homogenized in radioimmunoprecipitation assay (RIPA) buffer and the superior phase was collected to determine the total protein content by Lowry's method and VEGF and BMP-4 protein levels. The obtained lung samples from newborn rats were fixed in a 10% formalin solution for tissue processing. The fixed samples were embedded in paraffin, and serial paraffin sections were prepared for hematoxylin and eosin staining. This study is the first to examine how maternal Cd exposure affects fetal lung development and to estimate the impact of prescribing Mg and vitamin D during pregnancy. The present study assessed the effects of a repeated dose of Cd for 4 weeks before pregnancy on the lung development of newborn rats born to mothers treated with vitamin D and Mg. The results showed that the P53 gene was overexpressed in the model group, while Foxo1 gene expression was downregulated, negatively impacting the lung structure and developmental indices of the fetuses. Therefore, the intake of vitamin D and Mg may contribute to improving the various stages of Cd-induced lung injury by modulating lung inflammation and mucosal secretion while also positively influencing the number of surviving offspring.

Impact of different tissue dissociation protocols on endothelial cell recovery from developing mouse lungs.

Flow cytometry and fluorescence-activated cell sorting are widely used to study endothelial cells, for which the generation of viable single-cell suspensions is an essential first step. Two enzymatic approaches, collagenase A and dispase, are widely employed for endothelial cell isolation. In this study, the utility of both enzymatic approaches, alone and in combination, for endothelial cell isolation from juvenile and adult mouse lungs was assessed, considering the number, viability, and subtype composition of recovered endothelial cell pools. Collagenase A yielded an 8-12-fold superior recovery of viable endothelial cells from lung tissue from developing mouse pups, compared to dispase, although dispase proved superior in efficiency for epithelial cell recovery. Single-cell RNA-Seq revealed that the collagenase A approach yielded a diverse endothelial cell subtype composition of recovered endothelial cell pools, with broad representation of arterial, capillary, venous, and lymphatic lung endothelial cells; while the dispase approach yielded a recovered endothelial cell pool highly enriched for one subset of general capillary endothelial cells, but poor representation of other endothelial cells subtypes. These data indicate that tissue dissociation markedly influences the recovery of endothelial cells, and the endothelial subtype composition of recovered endothelial cell pools, as assessed by single-cell RNA-Seq.

Vangl-dependent mesenchymal thinning shapes the distal lung during murine sacculation.

The planar cell polarity (PCP) complex is speculated to function in murine lung development, where branching morphogenesis generates an epithelial tree whose distal tips expand dramatically during sacculation. Here, we show that PCP is dispensable in the airway epithelium for sacculation. Rather, we find a Celsr1-independent role for the PCP component Vangl in the pulmonary mesenchyme: loss of Vangl1/2 inhibits mesenchymal thinning and expansion of the saccular epithelium. Further, loss of mesenchymal Wnt5a mimics sacculation defects observed in Vangl2-mutant lungs, implicating mesenchymal Wnt5a/Vangl signaling as a key regulator of late lung morphogenesis. A computational model predicts that sacculation requires a fluid mesenchymal compartment. Lineage-tracing and cell-shape analyses are consistent with the mesenchyme acting as a fluid tissue, suggesting that loss of Vangl1/2 impacts the ability of mesenchymal cells to exchange neighbors. Our data thus identify an explicit function for Vangl and the pulmonary mesenchyme in actively shaping the saccular epithelium.

Association of Fetal Lung Development Disorders with Adult Diseases: A Comprehensive Review.

Fetal lung development is a crucial and complex process that lays the groundwork for postnatal respiratory health. However, disruptions in this delicate developmental journey can lead to fetal lung development disorders, impacting neonatal outcomes and potentially influencing health outcomes well into adulthood. Recent research has shed light on the intriguing association between fetal lung development disorders and the development of adult diseases. Understanding these links can provide valuable insights into the developmental origins of health and disease, paving the way for targeted preventive measures and clinical interventions. This review article aims to comprehensively explore the association of fetal lung development disorders with adult diseases. We delve into the stages of fetal lung development, examining key factors influencing fetal lung maturation. Subsequently, we investigate specific fetal lung development disorders, such as respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), congenital diaphragmatic hernia (CDH), and other abnormalities. Furthermore, we explore the potential mechanisms underlying these associations, considering the role of epigenetic modifications, transgenerational effects, and intrauterine environmental factors. Additionally, we examine the epidemiological evidence and clinical findings linking fetal lung development disorders to adult respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), and other respiratory ailments. This review provides valuable insights for healthcare professionals and researchers, guiding future investigations and shaping strategies for preventive interventions and long-term care.

Emerging role of cellular senescence in normal lung development and perinatal lung injury.

Cellular senescence is a status of irreversible growth arrest, which can be triggered by the p53/p21cip1 and p16INK4/Rb pathways via intrinsic and external factors. Senescent cells are typically enlarged and flattened, and characterized by numerous molecular features. The latter consists of increased surfaceome, increased residual lysosomal activity at pH 6.0 (manifested by increased activity of senescence-associated beta-galactosidase [SA-ß-gal]), senescence-associated mitochondrial dysfunction, cytoplasmic chromatin fragment, nuclear lamin b1 exclusion, telomere-associated foci, and the senescence-associated secretory phenotype. These features vary depending on the stressor leading to senescence and the type of senescence. Cellular senescence plays pivotal roles in organismal aging and in the pathogenesis of aging-related diseases. Interestingly, senescence can also both promote and inhibit wound healing processes. We recently report that senescence as a programmed process contributes to normal lung development. Lung senescence is also observed in Down Syndrome, as well as in premature infants with bronchopulmonary dysplasia and in a hyperoxia-induced rodent model of this disease. Furthermore, this senescence results in neonatal lung injury. In this review, we briefly discuss the molecular features of senescence. We then focus on the emerging role of senescence in normal lung development and in the pathogenesis of bronchopulmonary dysplasia as well as putative signaling pathways driving senescence. Finally, we discuss potential therapeutic approaches targeting senescent cells to prevent perinatal lung diseases.

Role of regulatory T cells in mouse lung development.

Regulatory T cells (Tregs) constitute a specialized subset of T cells with dual immunoregulatory and modulatory functions. Recent studies have reported that Tregs mediate immune responses and regulate the development and repair processes in non-lymphoid tissues, including bone and cardiac muscle. Additionally, Tregs facilitate the repair and regeneration of damaged lung tissues. However, limited studies have examined the role of Tregs in pulmonary development. This study aimed to evaluate the role of Tregs in pulmonary development by investigating the dynamic alterations in Tregs and their hallmark cellular factor Forkhead box P3 (Foxp3) at various stages of murine lung development and establishing a murine model of anti-CD25 antibody-induced Treg depletion. During the early stages of murine lung development, especially the canalicular and saccular stages, the levels of Treg abundance and expression of Foxp3 and transforming growth factor-ß (TGF-ß) were upregulated. This coincided with the proliferation period of alveolar epithelial cells and vascular endothelial cells, indicating an adaptation to the dynamic lung developmental processes. Furthermore, the depletion of Tregs disrupted lung tissue morphology and downregulated lung development-related factors, such as surfactant protein C (SFTPC), vascular endothelial growth factor A (VEGFA) and platelet endothelial cell adhesion molecule-1 (PECAM1/CD31). These findings suggest that Tregs promote murine lung development.

Single-Cell Transcriptomic Profiling Identifies Molecular Phenotypes of Newborn Human Lung Cells.

While animal model studies have extensively defined the mechanisms controlling cell diversity in the developing mammalian lung, there exists a significant knowledge gap with regards to late-stage human lung development. The NHLBI Molecular Atlas of Lung Development Program (LungMAP) seeks to fill this gap by creating a structural, cellular and molecular atlas of the human and mouse lung. Transcriptomic profiling at the single-cell level created a cellular atlas of newborn human lungs. Frozen single-cell isolates obtained from two newborn human lungs from the LungMAP Human Tissue Core Biorepository, were captured, and library preparation was completed on the Chromium 10X system. Data was analyzed in Seurat, and cellular annotation was performed using the ToppGene functional analysis tool. Transcriptional interrogation of 5500 newborn human lung cells identified distinct clusters representing multiple populations of epithelial, endothelial, fibroblasts, pericytes, smooth muscle, immune cells and their gene signatures. Computational integration of data from newborn human cells and with 32,000 cells from postnatal days 1 through 10 mouse lungs generated by the LungMAP Cincinnati Research Center facilitated the identification of distinct cellular lineages among all the major cell types. Integration of the newborn human and mouse cellular transcriptomes also demonstrated cell type-specific differences in maturation states of newborn human lung cells. Specifically, newborn human lung matrix fibroblasts could be separated into those representative of younger cells (n = 393), or older cells (n = 158). Cells with each molecular profile were spatially resolved within newborn human lung tissue. This is the first comprehensive molecular map of the cellular landscape of neonatal human lung, including biomarkers for cells at distinct states of maturity.

Antenatal Administration of Extracellular Vesicles Derived From Amniotic Fluid Stem Cells Improves Lung Function in Neonatal Rats With Congenital Diaphragmatic Hernia.

BACKGROUND: The severity of pulmonary hypoplasia is a main determinant of outcome for babies with congenital diaphragmatic hernia (CDH). Antenatal administration of extracellular vesicles derived from amniotic fluid stem cells (AFSC-EVs) has been shown to rescue morphological features of lung development in the rat nitrofen model of CDH. Herein, we evaluated whether AFSC-EV administration to fetal rats with CDH is associated with neonatal improvement in lung function. METHODS: AFSC-EVs were isolated by ultracentrifugation and characterized by size, morphology, and canonical marker expression. At embryonic (E) day 9.5, dams were gavaged with olive oil (control) or nitrofen to induce CDH. At E18.5, fetuses received an intra-amniotic injection of either saline or AFSC-EVs. At E21.5, rats were delivered and subjected to a tracheostomy for mechanical ventilation (flexiVent system). Groups were compared for lung compliance, resistance, Newtonian resistance, tissue damping and elastance. Lungs were evaluated for branching morphogenesis and collagen quantification. RESULTS: Compared to healthy control, saline-treated pups with CDH had fewer airspaces, more collagen deposition, and functionally exhibited reduced compliance and increased airway resistance, elastance, and tissue damping. Conversely, AFSC-EV administration resulted in improvement of lung mechanics (compliance, resistance, tissue damping, elastance) as well as lung branching morphogenesis and collagen deposition. CONCLUSIONS: Our studies show that the rat nitrofen model reproduces lung function impairment similar to that of human babies with CDH. Antenatal administration of AFSC-EVs improves lung morphology and function in neonatal rats with CDH. LEVEL OF EVIDENCE: N/A (animal and laboratory study).

Itaconic acid regulation of TFEB-mediated autophagy flux alleviates hyperoxia-induced bronchopulmonary dysplasia.

BACKGROUND: Premature infants often require oxygen supplementation, which can elicit bronchopulmonary dysplasia (BPD) and lead to mitochondrial dysfunction. Mitochondria play important roles in lung development, in both normal metabolism and apoptosis. Enhancing our comprehension of the underlying mechanisms in BPD development can facilitate the effective treatments. METHODS: Plasma samples from BPD and non-BPD infants were collected at 36 weeks post-menstrual age and used for metabolomic analysis. Based on hyperoxia-induced animal and cell models, changes in mitophagy and apoptosis were evaluated following treatment with itaconic acid (ITA). Finally, the mechanism of action of ITA in lung development was comprehensively demonstrated through rescue strategies and administration of corresponding inhibitors. RESULTS: An imbalance in the tricarboxylic acid (TCA) cycle significantly affected lung development, with ITA serving as a significant metabolic marker for the outcomes of lung development. ITA improved the morphological changes in BPD rats, promoted SP-C expression, and inhibited the degree of alveolar type II epithelial cells (AEC II) apoptosis. Mechanistically, ITA mainly promotes the nuclear translocation of transcription factor EB (TFEB) to facilitate dysfunctional mitochondrial clearance and reduces apoptosis in AEC II cells by regulating autophagic flux. CONCLUSION: The metabolic imbalance in the TCA cycle is closely related to lung development. ITA can improve lung development by regulating autophagic flux and promote the nuclear translocation of TFEB, implying its potential therapeutic utility in the treatment of BPD.

Bulk RNA sequencing of human pediatric lung cell populations reveals unique transcriptomic signature associated with postnatal pulmonary development.

Postnatal lung development results in an increasingly functional organ prepared for gas exchange and pathogenic challenges. It is achieved through cellular differentiation and migration. Changes in the tissue architecture during this development process are well-documented and increasing cellular diversity associated with it are reported in recent years. Despite recent progress, transcriptomic and molecular pathways associated with human postnatal lung development are yet to be fully understood. In this study, we investigated gene expression patterns associated with healthy pediatric lung development in four major enriched cell populations (epithelial, endothelial, and nonendothelial mesenchymal cells, along with lung leukocytes) from 1-day-old to 8-yr-old organ donors with no known lung disease. For analysis, we considered the donors in four age groups [less than 30 days old neonates, 30 days to < 1 yr old infants, toddlers (1 to < 2 yr), and children 2 yr and older] and assessed differentially expressed genes (DEG). We found increasing age-associated transcriptional changes in all four major cell types in pediatric lung. Transition from neonate to infant stage showed highest number of DEG compared with the number of DEG found during infant to toddler- or toddler to older children-transitions. Profiles of differential gene expression and further pathway enrichment analyses indicate functional epithelial cell maturation and increased capability of antigen presentation and chemokine-mediated communication. Our study provides a comprehensive reference of gene expression patterns during healthy pediatric lung development that will be useful in identifying and understanding aberrant gene expression patterns associated with early life respiratory diseases.NEW & NOTEWORTHY This study presents postnatal transcriptomic changes in major cell populations in human lung, namely endothelial, epithelial, mesenchymal cells, and leukocytes. Although human postnatal lung development continues through early adulthood, our results demonstrate that greatest transcriptional changes occur in first few months of life during neonate to infant transition. These early transcriptional changes in lung parenchyma are particularly notable for functional maturation and activation of alveolar type II cell genes.

Pulmonary vasculature development in congenital diaphragmatic hernia: a novel automated quantitative imaging analysis.

PURPOSE: Impaired fetal lung vasculature determines the degree of pulmonary hypertension in the congenital diaphragmatic hernia (CDH). This study aims to demonstrate the morphometric measurements that differ in pulmonary vessels of fetuses with CDH. METHODS: Nitrofen-induced CDH Sprague-Dawley rat fetuses were scanned with microcomputed tomography. The analysis of the pulmonary vascular tree was performed with artificial intelligence. RESULTS: The number of segments in CDH was significantly lower than that in the control group on the left (U = 2.5, p = 0.004) and right (U = 0, p = 0.001) sides for order 1(O1), whereas there was a significant difference only on the right side for O2 and O3. The pooled element numbers in the control group obeyed Horton's law (R2 = 0.996 left and R2 = 0.811 right lungs), while the CDH group broke it. Connectivity matrices showed that the average number of elements of O1 springing from elements of O1 on the left side and the number of elements of O1 springing from elements of O3 on the right side were significantly lower in CDH samples. CONCLUSION: According to these findings, CDH not only reduced the amount of small order elements, but also destroyed the fractal structure of the pulmonary arterial trees.

Prediction of bronchopulmonary dysplasia by the chest radiographic thoracic area on day one in infants with exomphalos.

OBJECTIVES: To determine if infants with exomphalos had abnormal antenatal lung growth as indicated by lower chest radiographic thoracic areas (CRTA) on day one compared to controls and whether the CRTA could predict the development of bronchopulmonary dysplasia (BPD). METHODS: Infants with exomphalos cared for between January 2004 and January 2023 were included. The controls were term, newborn infants ventilated for absent respiratory drive at birth, without lung disease and had no supplemental oxygen requirement by 6 h of age. The radiographs were imported as digital image files by Sectra PACS software (Sectra AB, Linköping, Sweden). Free-hand tracing of the perimeter of the thoracic area was undertaken and the CRTA calculated by the software. RESULTS: Sixty-four infants with exomphalos and 130 controls were included. Infants with exomphalos had a lower median (IQR) CRTA (1,983 [1,657-2,471] mm2) compared to controls (2,547 [2,153-2,932] mm2, p<0.001). Following multivariable regression analysis, infants with exomphalos had lower CRTAs compared to controls (p=0.001) after adjusting for differences in gestational age and male sex. In the exomphalos group, the CRTAs were lower in those who developed BPD (n=14, 1,530 [1,307-1,941] mm2) compared to those who did not (2,168 [1,865-2,672], p<0.001). Following multivariable regression analysis, the CRTA was associated with BPD development (p=0.021) after adjusting for male sex and gestational age. CONCLUSIONS: Lower CRTAs on day one in the exomphalos infants compared to the controls predicted BPD development.

Decreased ß-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 ß-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 ß-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 ß-catenin proteins between CDH and non-CDH lungs. LEVEL OF EVIDENCE: Level III. TYPE OF STUDY: Case-Control Study.