Lung epithelium development and airway regeneration

Extreme temperatures modulate gene expression in the airway epithelium of the lungs in mice and asthma patients

Background

The objective of this study was to examine the effects of extreme temperatures on the gene signature and pathways of airway epithelial cells in mice and asthma patients.

Methods

We investigated the effects of temperature exposure at normal (22°C), and extreme low (10°C), high (40°C) and temperature fluctuation (40°C for 2 h followed by 10°C for next 2 h) in B6.Sftpc-CreER T2 ;Ai14(RCL-tdT)-D mice and pediatric and adult patient's airway epithelial exposed to extreme temperatures.

Results

We observed that Mmp8, Sftpb, Cxcl15 and Cd14 were significantly upregulated in airway epithelial cells in mice model. Cma1, Kit, Fdx1, Elf1a, Cdkn2aipnl, Htatsf1, Mfsd13a, Gtf2h5, Tiam2, and Trmt10c were significantly upregulated in 40°C exposure in airway epithelial cells. Sftpc, Gpr171, Sic34a2, Cox14, Lamp3, Luc7l, Nxnl, Tmub2, Tob1, and Cd3e genes were significantly upregulated in 10°C exposure group. Pediatric asthma subjects in the extreme high temperature group consistently showed decreased Wfdc21, Cib3, and Sftpc, at the same time increased Tiam2 and Cma1 expression, while in the extreme low temperature group exhibited consistently higher expression of Sftpc and Nxnl, at the same time decreased Wfdc21, Cib3, Cma1, and Dld expression. Notably, the mice in the extreme temperature fluctuation group showed decreased Wfdc21, Cib3, Gpr171, and Cttnbp2 expression, while increased Hbb-bs expression. Adult asthma subjects in the extreme temperature fluctuation group showed consistently decreased Wfdc21, Cib3, Gpr171, and Cttnbp2 expression, while increased Tiam2 and Cma1 expression. We observed that the mild, moderate, and severe asthma subject in the extreme low temperature group showed increased Tob1, Mub2, Sic34a2, Sftpc, Nxnl, Luc71, Lamp3, Gpr171, Cox14, and Cd3e expression, while in the severe asthma subjects showed increased expression in all temperature exposure group.

Conclusion

Our study highlights the effects of extreme temperatures on the gene signature of the airway epithelium in both mice and asthma patients. These findings suggest that extreme temperatures modulate gene expression in the airway epithelium, potentially serving as clinical indicators or biomarkers in response to climate change.

Morphological and molecular aspects of lung development

Healthy breathing relies on normal morphological and functional development of the lung. This includes different prenatal and postnatal developmental stages. Depending on species and postnatal behavior as nest escapers or nest squatters, the duration of individual developmental phases and the state of differentiation of the lungs at birth differ. However, the sequence and morphology of the lung developmental stages are similar in all mammals, so knowledge gained from animal models about development-specific genetic control and regulatory mechanisms can be translated in principle to the human lung. Functional lung development comprises the maturation of the surfactant system, which is closely linked to the morphological development of the pulmonary acini. Although a number of reviews are found in the literature, a presentation that integrates the morphological and molecular regulatory mechanisms is missing. Therefore, the aim of this article was to provide an up-to-date comprehensive review of the main morphological steps and regulatory mechanisms of lung development, including clinical aspects related to developmental disorders.

Physiological Modeling of the Vascularized Human Lung Organoid

Human lung organoids (hLOs) derived from induced pluripotent stem cells (iPSCs) are of great interest, as they inform lung development, such as differentiation of lung epithelial subtypes in the distal alveolar unit. An unaddressed question is whether introducing endothelial cells (ECs) and vascularization provides a better representation of hLOs. Here we describe a method in which vessels become integrated with hLOs. hLOs were generated by combining human iPSC-derived lung progenitor cells (LPs) with ECs at varying LP:EC ratios. At the optimal combination of both cells, we observed vessel infiltration of hLOs compared to without ECs. Red blood cells were seen in hLOs implanted into kidney capsules of NOD/SCID mice. Both human and mouse ECs conjoined to form chimeric vessels in hLOs. The vascularized hLOs showed alveolar type II epithelial (ATII) cells and ATI cells, although there was no difference in 1:1 ATII/ATI ratio. We observed primitive airway sacs with alveolar epithelial cells lining the lumen of vascularized hLOs. Electron microscopy revealed surfactant production in ATII cells of vascularized hLOs in contrast to absence of vessels. The vascularized hLOs also mounted a robust inflammatory response characterized by influx of mouse neutrophils after challenging mice with LPS. Thus, interactions of ECs with LPs generated vascularized hLOs that induced ATII and ATI differentiation, although not reaching to the ratio of 1:9 seen in mature human lungs. hLOs also showed the LPS induced inflammatory response upon transplantation into recipient mice. Our results show the potential of vascularized hLOs for studying human lung development and inflammatory lung injury.

Notch 2 from bone marrow mesenchymal stem cells alleviates smoke inhalation-induced lung injury by mediating alveolar cell differentiation

BACKGROUND

Smoke inhalation-induced lung injury (SILI) is the major fatality in fire- and blast-related accidents. Bone marrow mesenchymal stem cells (BMSCs) have a potential therapeutic role in SILI through directional differentiation into AT1, AT2, and pulmonary vascular endothelial cells. The present study proposes to evaluate the effect of Notch 2 on the directional differentiation of BMSCs and to characterize its reparative role in a SILI model.

METHODS

pGMLV-SC5 RNAi and pcDNA 3.1 lentivirus exogenously regulate Notch 2 expression in rat-derived BMSCs and BMSCs were injected into the tail vein of the SILI rat model. H&E, Masson and TUNEL stains characterized pathological changes in rat lung tissue. ELISA, western blot, and RT-qPCR identified inflammatory factors (IL-1β, IL-6 and TNF-α), Notch 2 pathway- (Notch 2 and Hes1), lung fibrosis- (α-SMA and E-cadherin), AT1- (AQP5), and AT2- (SPC and SPD) associated markers.

RESULTS

pGMLV-SC5 RNAi or pcDNA 3.1 lentivirus could decrease or increase Notch 2 expression in BMSCs. In vivo imaging showed that BMSCs could be localized in the lungs of the SILI model at 24 h after model development. Treatment with BMSCs alleviated diffuse congestion, lung fibrosis, and alveolar cell apoptosis in lung tissues of the SILI model. Treatment of BMSCs decreased the levels of IL-1β, IL-6, TNF-α, and α-SMA and increased the expression of Notch 2, Hes1, E-cadherin, AQP5, SPC, and SPD in the SILI model. Overexpression of Notch 2 enhances the therapeutic effect of BMSCs on lung injury in the SILI model. Notably, overexpression of Notch 2 attenuated the BMSCs-induced upregulation of AQP5 expression and enhanced the BMSCs-induced upregulation of SPC and SPD expression.

CONCLUSION

Notch 2 contributes to lung injury repair in the SILI rat model by facilitating the differentiation of BMSCs to AT2. This study provides a new idea and target for the treatment of BMSCs for SILI.

Engineered hydrogel biomaterials facilitate lung progenitor cell differentiation from induced pluripotent stem cells

Lung progenitor (LP) cells identified by the expression of transcription factor NK2 homeobox 1 (NKX2.1) are essential for the development of all lung epithelial cell types and hold tremendous potential for pulmonary research and translational regenerative medicine applications. Here, we present engineered hydrogels as a promising alternative to the naturally derived materials that are often used to differentiate human-induced pluripotent stem cells (iPSCs) into LP cells. Poly(ethylene glycol) norbornene (PEGNB) hydrogels with defined composition were used to systematically investigate the role of microenvironmental stiffness, cell origin, and splitting during the differentiation process. Results demonstrated that each factor impacted LP differentiation efficiency and that the soft hydrogels replicating healthy lung stiffness [elastic modulus (E) = 4.00 ± 0.25 kPa] produced the highest proportion of LP cells based on flow cytometric analysis results (54%) relative to the stiff hydrogels (48%) and Matrigel controls (32%) at the end of the nonsplit differentiation protocol. Collectively, these results showed that engineered hydrogels provide a well-defined microenvironment for iPSC-to-LP differentiation and perform as effectively as the current gold standard Matrigel-coated tissue culture plastic. Adopting engineered biomaterials in cell culture protocols may enable greater control over differentiation parameters and has the potential to enhance the clinical translation of iPSC-derived LP cells.NEW & NOTEWORTHY Standard iPSC differentiation protocols rely on Matrigel, a basement membrane extract from mouse sarcoma cells that is poorly defined and exhibits significant batch-to-batch variation. Due to these limitations, Matrigel-derived products have never been approved by the Food and Drug Administration. This study introduces a novel method for differentiating iPSCs into lung progenitor cells using well-defined hydrogel substrates. These biomaterials not only enhance differentiation efficiency but also streamline the regulatory pathway, facilitating their potential therapeutic application.

High-Frequency Percussive Ventilation: A Promising Rescue Strategy in Severe Lung Disease of Extremely Low Gestational Age Neonates

Objective: The aim of this study was to evaluate high-frequency percussive ventilation (HFPV) as a rescue strategy for extremely low gestational age neonates (ELGANs) with severe lung disease. Methods: This is a retrospective review of 16 ELGANs with severe lung disease who were placed on HFPV following a lack of improvement on other modes of conventional and high-frequency ventilation. Results: The gestational age of these 16 infants was 25 (24, 26) weeks and their birth weight was 640 (535, 773) grams [median (IQR)], with the survivors being more immature compared to those who died [24 (23, 26) and 26 (25, 28) weeks, respectively; (p = 0.04)]; and with an overall mortality of 31% (N = 5). Of those who died, 60% were SGA (p = 0.02). Following placement on HFPV, the survivors had a statistically significant decrease in their respiratory severity scores (RSSs) [11 (9, 14) to 6 (5, 13), p = 0.03] compared to those who did not survive [15 (11, 16) to 11 (6.8, 14.5), p = 0.32] due to an improvement in their oxygenation [FiO2: 0.95 (0.85, 1) to 0.6 (0.4, 0.9), p = 0.01; compared to 1 (1, 1) to 1 (0.7, 1); survivors and non-survivors, respectively; p = 0.32]. Chest X-rays also showed significantly improved aeration due to decreased areas of atelectasis in those who survived. Conclusions: HFPV may be an appropriate rescue mode of high-frequency ventilation in the ELGAN population with severe lung disease, particularly for patients with impaired oxygenation and ventilation difficulties due to shifting atelectasis and mucous plugging.

Interplay between Lung Diseases and Viral Infections: A Comprehensive Review

The intricate relationship between chronic lung diseases and viral infections is a significant concern in respiratory medicine. We explore how pre-existing lung conditions, including chronic obstructive pulmonary disease, asthma, and interstitial lung diseases, influence susceptibility, severity, and outcomes of viral infections. We also examine how viral infections exacerbate and accelerate the progression of lung disease by disrupting immune responses and triggering inflammatory pathways. By summarizing current evidence, this review highlights the bidirectional nature of these interactions, where underlying lung diseasesincrease vulnerability to viral infections, while these infections, in turn, worsen the clinical course. This review underscores the importance of preventive measures, such as vaccination, early detection, and targeted therapies, to mitigate adverse outcomes in patients with chronic lung conditions. The insights provided aim to inform clinical strategies that can improve patient management and reduce the burden of chronic lung diseases exacerbated by viral infections.

Grb7, Grb10 and Grb14, encoding the growth factor receptor-bound 7 family of signalling adaptor proteins have overlapping functions in the regulation of fetal growth and post-natal glucose metabolism

BACKGROUND

The growth factor receptor bound protein 7 (Grb7) family of signalling adaptor proteins comprises Grb7, Grb10 and Grb14. Each can interact with the insulin receptor and other receptor tyrosine kinases, where Grb10 and Grb14 inhibit insulin receptor activity. In cell culture studies they mediate functions including cell survival, proliferation, and migration. Mouse knockout (KO) studies have revealed physiological roles for Grb10 and Grb14 in glucose-regulated energy homeostasis. Both Grb10 KO and Grb14 KO mice exhibit increased insulin signalling in peripheral tissues, with increased glucose and insulin sensitivity and a modestly increased ability to clear a glucose load. In addition, Grb10 strongly inhibits fetal growth such that at birth Grb10 KO mice are 30% larger by weight than wild type littermates.

RESULTS

Here, we generate a Grb7 KO mouse model. We show that during fetal development the expression patterns of Grb7 and Grb14 each overlap with that of Grb10. Despite this, Grb7 and Grb14 did not have a major role in influencing fetal growth, either alone or in combination with Grb10. At birth, in most respects both Grb7 KO and Grb14 KO single mutants were indistinguishable from wild type, while Grb7:Grb10 double knockout (DKO) were near identical to Grb10 KO single mutants and Grb10:Grb14 DKO mutants were slightly smaller than Grb10 KO single mutants. In the developing kidney Grb7 had a subtle positive influence on growth. An initial characterisation of Grb7 KO adult mice revealed sexually dimorphic effects on energy homeostasis, with females having a significantly smaller renal white adipose tissue depot and an enhanced ability to clear glucose from the circulation, compared to wild type littermates. Males had elevated fasted glucose levels with a trend towards smaller white adipose depots, without improved glucose clearance.

CONCLUSIONS

Grb7 and Grb14 do not have significant roles as inhibitors of fetal growth, unlike Grb10, and instead Grb7 may promote growth of the developing kidney. In adulthood, Grb7 contributes subtly to glucose mediated energy homeostasis, raising the possibility of redundancy between all three adaptors in physiological regulation of insulin signalling and glucose handling.

The impact of hormones on lung development and function: an overlooked aspect to consider from early childhood

The impact of hormones on the respiratory system constitutes a multifaceted and intricate facet of human biology. We propose a comprehensive review of recent advancements in understanding the interactions between hormones and pulmonary development and function, focusing on pediatric populations. We explore how hormones can influence ventilation, perfusion, and pulmonary function, from regulating airway muscle tone to modulating the inflammatory response. Hormones play an important role in the growth and development of lung tissues, influencing them from early stages through infancy, childhood, adolescence, and into adulthood. Glucocorticoids, thyroid hormones, insulin, ghrelin, leptin, glucagon-like peptide 1 (GLP-1), retinoids, cholecalciferol sex steroids, hormones derived from adipose tissue, factors like insulin, granulocyte-macrophage colony-stimulating factor (GM-CSF) and glucagon are key players in modulating respiratory mechanics and inflammation. While ample evidence underscores the impact of hormones on lung development and function, along with sex-related differences in the prevalence of respiratory disorders, further research is needed to clarify their specific roles in these conditions. Further research into the mechanisms underlying hormonal effects is essential for the development of customizing therapeutic approaches for respiratory diseases. Understanding the impact of hormones on lung function could be valuable for developing personalized monitoring approaches in both medical and surgical pediatric settings, in order to improve outcomes and the quality of care for pediatric patients.

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.

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.

Mechanics of Lung Development

We summarize how skeletal muscle and lung developmental biology fields have been bridged to benefit from mouse genetic engineering technologies and to explore the role of fetal breathing-like movements (FBMs) in lung development, by using skeletal muscle-specific mutant mice. It has been known for a long time that FBMs are essential for the lung to develop properly. However, the cellular and molecular mechanisms transducing the mechanical forces of muscular activity into specific genetic programs that propel lung morphogenesis (development of the shape, form and size of the lung, its airways, and gas exchange surface) as well as its differentiation (acquisition of specialized cell structural and functional features from their progenitor cells) are only starting to be revealed. This chapter is a brief synopsis of the cumulative findings from that ongoing quest. An update on and the rationale for our recent International Mouse Phenotyping Consortium (IMPC) search is also provided.