搜索结果：American journal of physiology. Lung cellular and molecular physiology

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) are common and critical pulmonary conditions involving numerous inflammatory factors and oxidative stress responses. Inflammatory responses and oxidative stress are closely related to the development of ALI/ARDS and form an important theoretical basis for treatment and drug development. Although there has been extensive research on the resolution of inflammation in ALI/ARDS, no systematic bibliometric analysis has been conducted in this field. The researchers used bibliometrics to search the Web of Science Core Collection (WOSCC) database for research literature on the resolution of inflammation in ALI/ARDS from 2005 to 2024. Visualization mapping analysis was performed using tools such as CiteSpace and VOSviewer to analyze authors, research institutions, countries, journals, cocited literature, and keywords. A total of 375 articles were included. The research showed an upward trend, with the highest number of publications in 2022. The United States took the leading position in this field, followed by China. JIN SW had the highest number of publications, while D'Alessio FR had the highest citation count. Harvard University had the highest intermediary centrality, the American Journal of Physiology-Lung Cellular and Molecular Physiology published the most articles, and the American Journal of Respiratory and Critical Care Medicine had the highest impact factor. Resolvin D1 (RvD1) and Resolvin E1 (RvE1) played a key role in the resolution of inflammation. Drug delivery systems (DDSs), such as black phosphorus nanosheets (BPNSs) and liposomes, could efficiently deliver these mediators to enhance therapeutic effects and reduce side effects. Over the past 20 years, interest in the resolution of inflammation in ALI/ARDS has grown. The United States has dominated research in this area. The study of RvD1 and RvE1 has become a hot topic, and the development of DDSs has provided new strategies for clinical treatment.

Animal models of bronchopulmonary dysplasia (BPD) have allowed the discovery of pathological and disease-management pathways. The laboratory mouse is the go-to model for first-step experimental in vivo studies. BPD encompasses disturbances to lung structure and function, including breathing patterns and gas exchange. Despite advances in quantitative assessment of lung structure in mice, most mouse modeling studies continue to use disordered lung structure as the primary experimental endpoint. Technical challenges associated with lung function studies in neonatal mice have limited enthusiasm for drawing correlations between lung structure and lung function. As this represents a key limitation of mouse BPD models, methodologies were developed here to adapt two established techniques: unrestrained whole body plethysmography (WBP) and the forced oscillation technique (FOT), enabling reliable conscious and anesthetized assessments of lung function in mouse pups. Diseased mice presented with alveolar simplification as well as a reduced tidal volume and breathing frequency, as assessed by WBP. Changes in respiratory mechanics, namely reduced tissue damping and tissue elastance, were revealed by FOT. Alterations to pressure/volume loops suggested an obstructive pattern of disease. In a clinical cohort of 65 patients with BPD, decreased tidal volume but unchanged breathing frequency was noted. Thus, with some exceptions, disturbances to lung function in experimentally modeled elements of BPD in mice paralleled those of infants with BPD. This report serves the dual function of reporting an innovative methodology, describing protocols for using WBP and FOT in neonatal mice, while reporting functional respiratory mechanics outcomes in mice in which BPD was experimentally modeled.NEW & NOTEWORTHY Clinically, respiratory disease in newborns is diagnosed and managed using lung function tests; while in animal models of newborn lung disease, lung structure is the primary experimental endpoint. Here, a comprehensive experimental protocol for assessing lung function in newborn mice is provided. Observed disturbances in lung function were discussed in the context of parallel structural changes to the lung architecture, and comparisons were drawn with clinical lung function studies in infants with BPD.

Cellular senescence is increasingly recognized as a hallmark of chronic obstructive pulmonary disease (COPD), with higher levels in lung fibroblasts from COPD patients. Upon senescence, both hypomethylation and hypermethylation have been described but not in COPD-derived fibroblasts yet. This study investigated whether altered DNA methylation can be a driver of fibroblast senescence in COPD. Genome-wide gene expression and DNA methylation data were generated from primary lung fibroblasts of 11 COPD stage IV patients and 10 matched controls. Gene expression of six well-known senescence genes was compared between COPD and control. COPD-associated senescence genes were correlated with their related CpG sites in an expression quantitative trait methylation (eQTM) analysis. Methylation levels of significant eQTMs were compared between COPD and control fibroblasts. A causal relationship between altered DNA methylation and senescence was validated in 5-Aza-2'-deoxycytidine (5-Aza-2'-dC)-treated primary lung fibroblasts. Gene expression of CDKN1A, CDKN2A, and CDKN2B was higher, while LMNB1 expression was lower in COPD-derived fibroblasts compared to controls. A total of 19 eQTMs were found for the COPD-associated senescence genes CDKN1A (9), CDKN2A (1), and LMNB1 (9). Among these, seven CpG sites (4 for CDKN1A and 3 for LMNB1) exhibited differential methylation between COPD and control. Treatment with 5-Aza-2'-dC led to global demethylation and increased senescence and, importantly, confirmed the association between senescence and hypomethylation of the COPD-associated CpG site cg04924375. Altered DNA methylation is linked to fibroblast senescence in COPD, and seven CpG sites are identified as potential epigenetic regulators of the senescence genes CDKN1A and LMNB1.NEW & NOTEWORTHY This study identifies DNA methylation as a mechanistic contributor to lung fibroblast senescence in chronic obstructive pulmonary disease (COPD). By integrating DNA methylation data with the transcriptomic data of senescence-related genes, we uncovered seven COPD-associated CpG sites linked to the senescence regulators CDKN1A and LMNB1. Pharmacological demethylation induces fibroblast senescence and is consistent with a functional role for hypomethylation at cg04924375, providing new insight into epigenetic regulation of cellular senescence in COPD lung fibroblasts.

Rigorous and reproducible evaluation of lung tissue under different conditions is necessary to interpret development, injury, and pharmacologic interventions. Common histological measurements in the distal lung include mean linear intercept (MLI) as a metric of alveolarization and airspace volume density (ASVD) as a metric of airspaces relative to tissue. Historically, these have been performed manually in a time-intensive process, with reproducible trends but a high degree of variability between individuals. To improve the reproducibility and throughput of lung morphometry, we developed AlveolEye, an open-source, semiautomated, computer vision-assisted tool that rapidly and reproducibly calculates MLI and ASVD from images of standard hematoxylin and eosin-stained tissue sections. AlveolEye-assisted MLI calculation closely aligns with manually derived measurements for corresponding images, with preservation of trends in measurements between noninjured controls and neonatal mice subjected to two different injury models. Analyzing human tissue of varying ages suggests that the approach developed in AlveolEye is generalizable across species. Notably, AlveolEye markedly reduced the average variation across individual analyzers, with the greatest improvement in precision among individuals with the least experience in performing lung morphometry. The design of AlveolEye is intentionally semiautomated, preserving the investigator's ability to assess and adjust parameters based on sample characteristics. AlveolEye facilitates efficient lung morphological measurements on larger sample sizes, allowing for greater statistical power for preclinical studies, and improves precision across individual observers, allowing for improved rigor in experimental design and execution.NEW & NOTEWORTHY Calculating lung morphometric measurements is time-intensive, with a high degree of interrater variability. We developed a semiautomated tool, AlveolEye, which uses computer vision to perform rapid and precise lung morphometry, reducing variability and improving efficiency. AlveolEye presents an opportunity for improved rigor, efficiency, and reproducibility in studies of lung development, injury, and regeneration.

Acute exacerbation of idiopathic pulmonary fibrosis is a life-threatening condition characterized by neutrophilic inflammation. S100A8/A9, an alarmin released by activated neutrophils and monocytes/macrophages, plays a pivotal role in regulating inflammatory responses. However, its specific involvement in acute exacerbations of pulmonary fibrosis remains unclear. This study evaluated the role of S100A8/A9 in the pathogenesis of acute exacerbations of pulmonary fibrosis. S100A8/A9 levels were measured in bronchoalveolar lavage fluid and serum from patients with idiopathic interstitial pneumonia, with and without acute exacerbations. To model acute exacerbations of pulmonary fibrosis, mice were intratracheally administered bleomycin followed by lipopolysaccharide. Subsequently, inflammatory cell infiltration, cytokine levels, morphological changes, and fibrosis marker levels in lung tissue and airways were analyzed. S100A8/A9 levels were significantly higher in the bronchoalveolar lavage fluid and serum of patients with idiopathic interstitial pneumonia experiencing acute exacerbations relative to those without; these levels were correlated with patient prognosis. In an experimental mouse model, intratracheal administration of bleomycin followed by lipopolysaccharide resulted in a significant increase in airway S100A8/A9 levels compared with bleomycin alone and control mice. Anti-S100A8/A9 neutralizing antibody Ab45 mitigated airway inflammation and lung fibrosis in mice with acute exacerbations of pulmonary fibrosis, reducing S100A8/A9 levels and neutrophil extracellular traps. In vitro, recombinant S100A8/A9 or lipopolysaccharide and neutrophils activated and differentiated fibroblasts; these effects were inhibited by anti-S100A8/A9 neutralizing antibody Ab45 and the humanized form of Ab45 (HuAb45). These findings highlight S100A8/A9 as a potential prognostic biomarker and therapeutic target for acute exacerbations of pulmonary fibrosis.NEW & NOTEWORTHY During acute exacerbation of idiopathic interstitial pneumonia, bronchoalveolar lavage fluid (BALF) and serum S100A8/A9 levels were elevated and associated with poor prognosis. In a mouse model of acute pulmonary fibrosis exacerbation, therapeutic targeting of S100A8/A9 attenuated lung inflammation and fibrosis, accompanied by reduced S100A8/A9 levels and neutrophil extracellular traps within airways. In vitro experiments demonstrated that neutrophil-derived S100A8/A9 promoted activation of lung fibroblasts and their differentiation into myofibroblasts, which was effectively inhibited by neutralizing antibodies.

Pulmonary macrophages are central regulators of lung injury and repair following acute inhalation of toxic chemicals. Strategically positioned within the airspaces and lung parenchyma, resident macrophage populations act as first responders that sense epithelial and endothelial injury, initiate sterile inflammatory responses, and coordinate immune cell recruitment, thereby influencing whether injury resolves or progresses to chronic inflammation and fibrosis. Recent advances have revealed substantial heterogeneity and plasticity among lung macrophages shaped by developmental origin, anatomical niche, and local microenvironmental cues. Alveolar and interstitial macrophages engage in extensive bidirectional cross talk with epithelial and endothelial cells through cytokines, growth factors, and extracellular vesicles that collectively maintain pulmonary homeostasis and regulate responses to injury. In experimental models of vesicant, particulate, volatile organic compounds, microbial toxins, and toxic gas exposure, pulmonary macrophages undergo profound transcriptional, metabolic, and functional reprogramming. Early depletion of resident alveolar macrophages coupled with disproportionate recruitment of monocyte-derived macrophages has emerged as a conserved pathogenic feature of severe chemical-induced lung injury. This review summarizes current understanding of pulmonary macrophage ontogeny, functional specialization, and macrophage-epithelial cross talk during acute chemical inhalation injury, and discusses emerging therapeutic strategies aimed at modulating macrophage responses to restore pulmonary homeostasis. Collectively, these insights position pulmonary macrophages as critical gatekeepers of lung injury and repair and as promising targets for intervention in chemical-induced lung disease.

With the rising prevalence of vaping, there is a pressing need to identify biomarkers of toxicity related to chronic effects induced by the inhalation of electronic nicotine delivery system (ENDS) aerosols. In a mouse model, we investigated the long-term pulmonary effects associated with exposures to cinnamon-flavored ENDS aerosols for up to 6 mo. Following exposures and after 2 mo of recovery, pulmonary function testing and lung biochemical responses were assessed. Despite similar serum cotinine concentrations in male and female mice, males exposed for 6 mo to ENDS aerosols exhibited significant reductions in tidal and minute volumes, breathing frequency, and elevated respiratory elastance, while significantly increased tissue damping and respiratory resistance were observed in both sexes. All parameters, except minute volume and breathing frequency in males, returned to baseline following recovery. Although there were no significant changes in pulmonary inflammation in all groups, lung RNA sequencing revealed significant upregulation of Cxcl5, a neutrophil chemotactic chemokine, in all groups exposed to ENDS aerosols. In total, 69 genes in males and 63 genes in females, were dysregulated, including upregulated proinflammatory and oxidative stress-related genes. HIF-1α in lung tissue, and CXCL5 serum concentrations, were significantly elevated in the ENDS and recovery groups, respectively, compared with controls. Overall, this study showed that pulmonary inflammation is not a hallmark of long-term ENDS aerosol exposure, whereas altered lung function is a sensitive indicator of lung damage in mice.NEW & NOTEWORTHY In mice, inhalation of cinnamon-flavored electronic nicotine delivery system (ENDS) aerosols for 6 mo induced pulmonary effects, including hypoxia and molecular changes. Our data suggest that hypoxia may be linked to lung function deterioration, independent of pulmonary inflammation. Overall, our findings indicate that altered lung structure and function, rather than pulmonary inflammation, are sensitive indicators of lung damage in mice chronically exposed to ENDS aerosols.

The alveolar epithelium, composed of type 1 (AT1) and type 2 (AT2) cells, is central to gas exchange and the lung's response to injury. Historically viewed as a simple barrier, recent advances have unveiled the profound dynamics and plasticity of these cells in orchestrating tissue repair. This mini-review synthesizes recent breakthroughs in our understanding of the cellular and molecular mechanisms governing alveolar regeneration. We focus on the expanding diversity of progenitor cells, including resident AT2 cells and newly identified multipotent progenitors in the distal airways, and the complex signaling networks that dictate their fate. Furthermore, we explore the emergence of transitional cell states during repair and how aberrant cellular behaviors can drive pathological outcomes like fibrosis. A deeper comprehension of this dynamic cellular behavior is paramount for developing novel therapeutic strategies to promote effective lung repair and combat chronic lung disease.

The lung is a uniquely demanding target for regeneration because its function depends on the coordinated integration of cellular diversity, three-dimensional architecture, cyclic mechanical forces, vascular perfusion, immune surveillance, and extracellular matrix remodeling. Although single-cell and spatial profiling, lineage tracing, and induced pluripotent stem cell (iPSC)-derived models have transformed our understanding of lung cell states and developmental potential, these descriptive approaches have also highlighted a central bottleneck: the field still lacks broadly adopted platforms to test whether engineered tissues and regenerative interventions restore "function" under physiological load. In this review, we focus on emerging technologies that enable functional biodesign in the lung biology by coupling engineered constructs to measurement systems that approximate native mechanics, flow, and immune dynamics. We highlight lung-scale experimental systems including engineered whole lung scaffolds, and we examine dynamic imaging platforms, exemplified by crystal ribcage approaches, that allow us to quantify alveolar mechanics, capillary perfusion, immune-cell behavior, and matrix remodeling in real time. We then discuss regenerative constructs as design problems defined by region-specific constraints and disease-associated transitional states, and we survey cell-based, molecular, and subcellular interventions that shift repair strategies from replacement toward targeted functional augmentation. Finally, we draw lessons from medical device translation, durability, infection resistance, and mechanical integrity, as nonnegotiable benchmarks for regenerative success. Together, these platforms establish an evidence framework, in which lung regeneration is evaluated by physiological performance rather than inferred from molecular or structural endpoints, accelerating progress from descriptive biology to reproducible, clinically actionable repair.

Pulmonary lymphatics play multiple essential roles in lung homeostasis through interstitial fluid removal, traffic of immune cells, and antigen presentation. This highly branching vascular bed comprises initial capillaries, pre-collecting vessels, and collecting lymphatics, and it is lined by characteristic lymphatic endothelial cells (LECs). These cells are distinct from blood endothelial cells in their structure, molecular markers (e.g., PROX1, LYVE-1, VEGFR-3), and responsiveness to inflammatory and mechanical stimuli. In health, LECs preserve barrier integrity, promote immune surveillance, and support unidirectional lymph flow. However, during pulmonary inflammation or injury, LECs may undergo phenotypic changes that impair function and promote local coagulation. This review consolidates current knowledge on pulmonary lymphatic vessel structure and function and LEC biology, with a focus on their involvement in inflammation and coagulation pathways. We examine how cigarette smoke disrupts LEC homeostasis, leading to endothelial injury, procoagulant factor upregulation [e.g., tissue factor, plasminogen activator inhibitor-1 (PAI-1)], and fibrin-rich thrombosis in lung lymphatics. Although vaping induces oxidative stress and vascular inflammation, its effects on the pulmonary lymphatic system have not been clearly explained. Based on pathological features shared with smoking, we propose potential mechanisms by which e-cigarette aerosols may contribute to lymphatic endothelial dysfunction and altered coagulation in lungs. Given the increasing prevalence of vaping, further research using in vitro, in vivo, and human studies is needed to elucidate how inhaled toxicants alter LEC function and to identify novel targets for preserving lymphatic health in lung disease.

Nicotine, a primary component of tobacco, cigarette smoke, and miscellaneous vaping products, can significantly impact respiratory health. Nicotine can exacerbate asthma through its actions on multiple cell types in airways. In this context, airway smooth muscle (ASM) is a key cell type for contractility and remodeling and could be a target of nicotine. We previously showed that ASM expresses functional nicotinic acetylcholine receptors (nAChRs) and that asthmatic ASM have higher α7 subunit of nAChR (α7nAChR) expression and function, which could make them more susceptible to deleterious effects of nicotine. We explore this paradigm in the current study by evaluating the effect of short term versus chronic nicotine exposure in regulating airway hyperreactivity (AHR) and remodeling in a mixed allergen (MA) model of asthma applied to wild-type (WT) versus global α7nAChR knockout (Glα7KO) versus smooth muscle-specific α7nAChR KO (smα7KO) mice. We hypothesized that the detrimental effect of nicotine occurs via α7nAChR in ASM, and that global α7nAChR KO has worsened impact of airway remodeling. Interestingly, we found that smα7KO improved lung function and AHR in MA-challenged alone, as well as in the presence of nicotine. In contrast, MA-challenged Glα7KO in the presence of nicotine showed worsened AHR. Lung histology of smα7KO mice showed reduced airway collagen deposition compared with WT and Glα7KO mice. Immunofluorescence analysis showed smα7KO reduced remodeling proteins. These data suggest that in vivo, α7nAChR has complex effects on AHR versus remodeling with worsening of ASM-mediated AHR or remodeling, but protective effects in non-ASM mediated AHR potentially involving epithelial cells and the immune system.NEW & NOTEWORTHY The studies demonstrate the differential effects of the nicotinic acetylcholine receptors (nAChRs) regulating airway hyperreactivity (AHR) and remodeling in a mixed allergen model of asthma. We compared wild-type (WT) versus global α7nAChR knockout (Glα7KO) versus smooth muscle-specific α7nAChR KO (smα7KO) mice. We found that smα7KO improved lung function and AHR in mice challenged with MA and in the presence of nicotine, whereas MA-challenged Glα7KO in the presence of nicotine showed worsened AHR.

Disruptions during perinatal fetal lung development can lead to postnatal chronic lung diseases such as bronchopulmonary dysplasia (BPD). Along with decreased alveolar and pulmonary vascular growth, abnormal airway growth occurs in BPD. Previous studies in rats have shown that antenatal endotoxin (AN-ETX) mimicking maternal chorioamnionitis causes dysanapsis during the neonatal period. Whether dysanaptic growth alters long-term lung function remains unknown. We hypothesized that antenatal endotoxin causes persistent differences between airway and distal lung growth with age in experimental BPD. Sprague-Dawley rats were exposed to AN-ETX at embryonic day 20 (E20) by intraamniotic injection and delivered on E22, analogous to human preterm 26-28 wk gestation. Pups raised via naive foster dams were evaluated for BPD-associated parameters on postnatal days 14 (D14) and 28 (D28), akin to infancy and childhood human lung development. Lung histologic morphometry, lung mechanics testing, and airway and pulmonary vasculature microcomputed tomography (µCT) evaluations were performed to assess growth at D14 and D28. AN-ETX-exposed rats demonstrated persistent somatic growth failure, decreased alveolarization, decreased vascularization, right ventricular hypertrophy, and impaired lung mechanics at both D14 and D28. AN-ETX exposure decreased large airway size at D14, but also medium airway diameters by D28. AN-ETX exposure caused early airflow obstruction at D14 [decreased forced expiratory volume over 0.1 s to forced vital capacity (FEV0.1/FVC) ratio], which worsened by D28 (decreased FEV0.1 and FEV0.1/FVC ratio). Adverse antenatal stress alone is sufficient to cause sustained abnormalities of lung development beyond the neonatal period. Early dysanapsis may predispose to structural obstructive disease and impair lung function over the lifespan.NEW & NOTEWORTHY Disruptions during perinatal lung development can lead to chronic lung diseases such as bronchopulmonary dysplasia (BPD). Rats exposed to a single intraamniotic endotoxin injection were evaluated for BPD-associated parameters of lung structure and function on postnatal days 14 and 28, akin to human infancy and childhood. Endotoxin-exposed rats demonstrated persistent impairments in lung development and function. This is the first preclinical study to suggest that early dysanaptic growth may predispose to lifelong impaired lung function.

Asthma is a chronic respiratory disease affecting over 230 million people worldwide, with higher prevalence in women. Environmental allergens such as house dust mite (HDM) trigger airway inflammation and hyperresponsiveness (AHR), yet the epigenetic mechanisms underlying these responses remain poorly understood. Furthermore, the role of estrogen receptors in the context of asthma is understudied. We aimed to investigate whether estrogen receptor-specific DNA methylation contributes to HDM-induced airway remodeling and hyperresponsiveness. Male and female C57BL/6J wild-type mice and estrogen receptor &#x3b1; and &#x3b2; knockout mice (Esr1-/- and Esr2-/-) were exposed to HDM or phosphate-buffered saline for 5 wk. DNA methylation and RNA sequencing data were obtained from snap-frozen whole lung tissues. HDM exposure resulted in widespread differential methylation of genes associated with inflammation and AHR, including Itgal, Tmem267, Rap1b, Bmf, Mid1, Fgd1, Ddx4, Comtd1, Filip1l, Grb10, and Chst7. Notably, the absence of estrogen receptor &#x3b2; (in Esr2-/- mice) produced the most pronounced methylation patterns, particularly in females. Pathway enrichment analysis revealed asthma-relevant processes such as extracellular matrix remodeling, leukocyte adhesion and migration, airway smooth muscle contraction, and inflammatory signaling. Integration of methylation and gene expression data confirmed significant correlations (P < 0.05) for Itgal, Rap1b, and Tmem267, and a marginal correlation for Chst7 (P < 0.1), implicating these genes in allergic asthma pathogenesis. Our findings demonstrate that HDM exposure induces sex-specific epigenetic changes mediated by estrogen receptor status, highlighting a potential mechanism for increased asthma susceptibility in women. These results can inform estrogen receptor-targeted treatment strategies for allergic airway diseases.NEW & NOTEWORTHY Understanding estrogen receptor-mediated epigenetic regulation provides a foundation for developing sex-specific interventions for asthma, addressing the higher prevalence and severity observed in women. In this study, we demonstrate that exposure to house dust mite in the mouse lung is associated with epigenetic alterations in genes linked to airway hyperresponsiveness and lung inflammation. These alterations were dependent on the presence or absence of estrogen receptors.

Pulmonary homeostasis and regeneration require coordination between epithelial cells, immune populations, vascular networks, extracellular matrix, and stromal cells. This mini review examines recent advances in lung niche biology that were a focus of the 2025 Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Diseases Conference. Here, we emphasize the impact of nonepithelial compartments essential for tissue function and repair. Reflecting the conference's emphasis on comprehensive niche biology, we highlight how nonepithelial compartments, including stromal, vascular, and immune cells, serve as essential regulators of tissue function and repair, a perspective that unified many of the presentations and discussions. In diseases such as pulmonary fibrosis and chronic obstructive pulmonary disease, disruption of these niche interactions, rather than isolated cellular defects, drives regenerative failure. Spatial transcriptomic approaches reveal how pathological cell states colocalize within aberrant microniches. These insights suggest that effective therapeutics must target entire multicellular ecosystems, with advanced organoid platforms offering promising tools for developing niche-modulating interventions.

Bronchopulmonary dysplasia (BPD) is a neonatal lung injury characterized by inflammation and alveolar and vascular hypoplasia that currently lacks effective treatment. Thrombospondin (TSP)-1 is an angiostatic and proinflammatory protein, recently implicated in BPD pathogenesis, that both activates transforming growth factor (TGF)-&#x3b2;1 and suppresses nitric oxide (NO) signaling. To gain further insight into the relative importance of downstream effects of TSP-1, our objective in a neonatal rat model of hyperoxia-intermittent hypoxia (H-IH)-induced lung injury was to compare effects of inhibiting 1) TSP-1-mediated TGF-&#x3b2;1 activation alone (LSKL) or 2) global TSP-1 signaling (soluble CD47 receptor ligand trap; sCD47r). From postnatal days (PND) 1-21, rat pups were exposed to air or H-IH (PND 1-7 85% O2, PND 7-14 60% O2, and PND 14-21 air with intermittent exposure to 10% O2 for 10 min every 4 h) while either receiving daily subcutaneous LSKL (20 mg/kg) or third daily sCD47r (3 mg/kg). Controls were treated with vehicle or were continuously exposed to normoxia. Exposure to H-IH increased lung contents of TSP-1 and active TGF-&#x3b2;1 and caused macrophage influx, alveolar and pulmonary vascular hypoplasia, and pulmonary hypertension (PH). Both strategies prevented H-IH-mediated effects on active TGF-&#x3b2;1 content, macrophage influx, abnormal lung morphology, and PH, while only sCD47r increased lung NO content and signaling. These observations in a clinically relevant model indicate that multiple strategies aimed at suppressing TSP-1 signaling are effective in preventing lung injury and that targeting TSP-1-mediated activation of TGF-&#x3b2;1 is sufficient to achieve these effects.NEW & NOTEWORTHY Thrombospondin (TSP)-1, an angiostatic and proinflammatory protein recently implicated in bronchopulmonary dysplasia (BPD) pathogenesis, activates transforming growth factor (TGF)-&#x3b2;1 and suppresses nitric oxide signaling via separate receptor-mediated pathways. In a rat model of BPD, treatment with LSKL (targeting TSP-1-mediated TGF-&#x3b2;1 activation alone) had equivalent preventive effects on inhibited alveolarization, inflammation, and pulmonary hypertension to global inhibition of TSP-1 (soluble ligand trap). We conclude that limiting TSP-1-mediated activation of TGF-&#x3b2;1 appears sufficient to prevent experimental BPD.

Premature infants exposed to supplemental oxygen (O2) are at increased risk of developing airway diseases such as asthma, hyperoxic lung injury (HLI), and bronchopulmonary dysplasia (BPD). Therefore, it is important to understand how O2 detrimentally impacts developing airways. Previous studies found that severe (80%-90%) O2 exposure increases reactive oxygen species (ROS) and lipid peroxidation, inducing ferroptosis in models of HLI. However, the impact of clinically relevant moderate (<60%) O2 exposure is less understood. Recognizing the importance of smooth muscle in airway dysfunction, the present study uses human fetal airway smooth muscle (fASM) as a model to investigate whether hyperoxia contributes to the establishment of a ferroptotic phenotype. fASM pretreated with or without deferoxamine (DFO; 100 &#xb5;M) or ferrostatin (Fer-1; 10 &#xb5;M) was exposed for 48 h to normoxia (21% O2) versus moderate to severe hyperoxia (50%, 70%, or 90% O2). The effects of hyperoxia on antioxidant systems, iron metabolism, and lipid peroxidation, and the alleviating effect of DFO or Fer-1 were examined. Moderate hyperoxia impaired antioxidant systems involved in preventing ferroptosis and dysregulated iron metabolism. Interestingly, only severe hyperoxia (90% O2) induced negative effects on downstream mechanisms involving early onset of ferroptosis such as increased labile iron and lipid peroxidation. DFO and Fer-1 showed no rescue effect on antioxidant systems. However, DFO decreased cytosolic iron, and Fer-1 decreased lipid peroxidation byproducts. Together, these data highlight the impact of supplemental oxygen on premature airways and introduce the concept of a dose-dependent effect of hyperoxia in the context of iron metabolism, lipid peroxidation, and ultimately ferroptosis.NEW & NOTEWORTHY Recognizing that antioxidant systems are impaired in the airways of premature infants, we used human fetal airway cells to explore the impact of oxygen on iron regulation and iron-mediated cell death (ferroptosis). We find moderate hyperoxia impairs antioxidant systems that prevent ferroptosis and dysregulates iron metabolism, while severe hyperoxia has a negative effect on mechanisms driving the early onset of ferroptosis. Inhibitors of ferroptosis decrease iron and lipid peroxidation, demonstrating links between oxygen and iron regulation in developing airways.

Bronchopulmonary dysplasia (BPD), a lung disease associated with preterm birth, is characterized by arrested alveolarization and impaired pulmonary vascular growth. Exposure to early-life hyperoxia is a disease-contributing factor, and endothelial determinants of injury versus repair remain incompletely defined. We hypothesized that endothelial-specific loss of Hif-1&#x3b1; during the saccular stage of development would adversely impact lung development and augment injury after hyperoxia exposure. Tamoxifen-inducible endothelial-specific Hif-1&#x3b1; knockout and Hif-1&#x3b1; fl/fl littermates were exposed to room air or 95% O&#x2082; from postnatal day (PND) 1-5, and lungs were analyzed at PND7 and PND21 for morphometry, vascular density, and lung endothelial transcriptomic response. Endothelial Hif-1&#x3b1; deletion had no impact on baseline alveolarization but reduced vascular density under normoxia and significantly worsened hyperoxia-induced alveolar simplification, septal thickening, and vascular rarefaction. Hyperoxia increased endothelial proliferation in both genotypes after 48 hours of recovery in normoxia. Bulk RNA sequencing of the lung endothelial cells revealed a shared hyperoxia injury program (e.g., Inhba, Serpine1 induction; Esm1, Gpihbp1, Car2 suppression). The transcriptomic response in HIF1&#x3b1; ECKO endothelial cells was significantly muted compared to wild-type endothelial cells, lacking induction of Hmox1, Prdx6, and Anxa1. Hif-1&#x3b1;-deficient endothelial cells upregulated Col18a1 and Ackr3 and showed enrichment of TNF-NF&#x3ba;B, TGF-&#x3b2;, and cell-cycle checkpoint pathways, consistent with maladaptive remodeling. Cross-referencing with human single-cell BPD data demonstrated that genes identified in the murine hyperoxia model exhibit conserved but heterogeneous endothelial expression patterns across BPD disease states. These findings identify endothelial Hif-1&#x3b1; as a central determinant of recovery after neonatal hyperoxia exposure.

Chronic hypoxia during development can impair lung and pulmonary vascular growth, but most mouse models of hypoxia-induced pulmonary hypertension expose adult animals for limited periods and do not capture lifelong or multigenerational hypoxic exposure. We developed a multigenerational model of lifelong moderate hypoxia by maintaining wild-type C57BL/6J mice at 13% inspired oxygen fraction ([Formula: see text]), beginning before fertilization and continuing through gestation, postnatal development, and adulthood. This exposure permitted breeding over two generations. Pregnancy and delivery rates were largely preserved, but second-generation litters had fewer pups alive at birth and reduced overall survival to weaning, primarily because of fetal or perinatal loss. Among surviving adults, both first- and second-generation hypoxia-exposed mice developed pulmonary hypertension, right ventricular systolic dysfunction, right ventricular hypertrophy, and reduced exercise capacity compared with age-matched room air control mice. These functional abnormalities were accompanied by alveolar simplification, increased lung compliance, increased muscularization of small pulmonary arterioles, and reduced peripheral pulmonary vascular density. Several measures, including right ventricular systolic pressure and right ventricular remodeling, were modestly worse in second-generation mice. Hemoglobin concentration was increased in both hypoxia-exposed generations, whereas exploratory analysis of gastrocnemius muscle showed no detectable reduction in skeletal muscle capillary density in first-generation mice. Thus, lifelong exposure to 13% [Formula: see text] establishes a survivable but pathological model of developmental hypoxia that permits multigenerational studies while producing persistent lung developmental abnormalities, pulmonary vascular disease, right ventricular dysfunction, erythrocytosis, and exercise limitation.NEW & NOTEWORTHY Lifelong exposure of C57BL/6J mice to 13% inspired oxygen fraction ([Formula: see text]) permits multigenerational breeding while producing persistent developmental lung disease, pulmonary vascular remodeling, pulmonary hypertension, right ventricular dysfunction, erythrocytosis, and reduced exercise capacity. Second-generation mice show reduced perinatal viability and modestly worse pulmonary vascular/right ventricular remodeling. This model enables investigation of chronic prenatal and postnatal hypoxia without the severe early mortality observed with more extreme hypoxic exposure.

Acute respiratory distress syndrome (ARDS) remains a critical condition associated with high morbidity and mortality, particularly when triggered by sepsis. Endothelial dysfunction is a central hallmark of ARDS pathology, but the precise mechanisms underlying pulmonary microvascular dysfunction remain poorly understood. Extracellular vesicles (EVs) have emerged as crucial mediators of cell-cell communication during inflammation; however, their role in endothelial dysfunction in ARDS is less clearly defined. We utilized a human pulmonary microvascular endothelial cell (HPMEC)-based model of sepsis-induced acute lung injury to investigate whether inflammatory EVs (iEVs), derived from endothelial cells treated with bacterial lipopolysaccharide (LPS), impair na&#xef;ve HPMEC function. EVs were characterized by nanoparticle tracking analysis, transmission electron microscopy, and immunofluorescence, confirming purity and uptake. iEV exposure significantly reduced barrier integrity by electric cell-substrate impedance sensing (ECIS) and increased cell migration; effects partially reversed by the TLR4 inhibitor TAK-242. Adhesion and tube formation were unaffected. Pre-treatment of donor HPMECs with the neutral sphingomyelinase inhibitor GW4869 attenuated the barrier-disrupting capacity of the resulting iEVs, implicating ceramide-dependent EV biogenesis in generating pathogenic cargo. Trypan Blue staining confirmed that these effects reflect altered signaling rather than cell death. iEV exposure upregulated TLR4, MyD88, IL-6, ICAM-1, VCAM-1, E-selectin, and Jag1 mRNA, with TAK-242 attenuating IL-6 and ICAM-1 induction. Our results highlight endothelial-derived EVs and TLR4-dependent pathways as amplifiers of pulmonary vascular injury in sepsis-induced ARDS, identifying EV biogenesis and EV-mediated signaling as novel therapeutic targets.