American journal of physiology. Lung cellular and molecular physiology最新文献

Invasive mechanical ventilation is a lifesaving intervention for patients with acute respiratory distress syndrome (ARDS) but it also causes ventilator-induced lung injury (VILI) that can be challenging to avoid due to interpatient and temporal heterogeneity. Thus, the aim of this study was to characterize and predict experimental VILI using readily available measures of lung function. Initially healthy (CTL) and hydrochloric acid (HCL) lung-injured mice were ventilated for 4 h at positive end-expiratory pressure (PEEP) 1, 3, or 8 cmH₂O to produce graded VILI severity as measured in lung function, alveolocapillary leak, and inflammation. Optimally protective PEEP was found to be 8 and 3 cmH₂O in the HCL and CTL groups, respectively. A novel computational model was fit to the data to investigate elastance dynamics described by the "compliance factor" (C_F), which was also used to predict VILI over 4 subsequent hours of ventilation. The model C_F is a sensitive measure of injury-induced alterations in the pressure and pressure history dependence of lung elastance that are known to correlate with recruitment and derecruitment dynamics. The C_F was then combined with PEEP and plateau pressures calculated from 10 min at the start of prolonged ventilation and used to accurately predict VILI outcomes measured 4 h later. This model outperformed other commonly used measures of injury such as driving pressure and mechanical power. The computer model provides a new tool for understanding lung dynamics and for predicting VILI. In future work, this approach could be used to guide identification of lung-protective ventilation settings.NEW & NOTEWORTHY Computer model-based analysis of lung function in healthy and lung-injured mice showed that model compliance factor (C_F) characteristics were sensitive measures of acute lung injury and ventilator-induced lung injury (VILI) severity. The [Formula: see text] Area, calculated from C_F and pressures from minutes 5-15 of ventilation, was a stronger predictor of VILI measured 4 h later than the driving pressure or mechanical power, suggesting potential utility for monitoring ventilation safety and guiding ventilator adjustments to reduce VILI.

Pulmonary fibrosis (PF) is a severe consequence of respiratory infections, characterized by excessive extracellular matrix deposition and irreversible lung architectural damage. Once considered a rare condition, PF is now increasingly recognized in the wake of viral infections, particularly among survivors of viral-induced acute respiratory distress syndrome (ARDS). The COVID-19 pandemic has highlighted in bold relief the observation that many survivors of severe viral pneumonia do not recover fully but develop chronic fibrotic changes that impair lung function. This review examines the clinical evidence and underlying mechanisms linking viral infections-COVID-19, influenza, and other respiratory viruses-to the onset of pulmonary fibrosis. By probing the mechanisms of cellular injury, immune dysregulation, and aberrant repair mechanisms, we aim to illuminate the pathways that transform an acute viral insult into a chronic, fibrotic disease.

Session III of the inaugural biennial Research Symposium on Pulmonary Injury and Repair of the Endothelium (ReSPIRE) highlighted key advancements in endothelial-inflammatory cell interactions. The work presented illustrates a growing recognition that pulmonary endothelial cell interactions and direct cross talk with inflammatory cells are integral in both health and disease in the developing and aging lung. Data presented detail the impact of targeting neutrophil- and macrophage-endothelial interactions in acute lung injury, and the role of fibroblast-endothelial inflammatory communication in interstitial pulmonary fibrosis of the aging lung. In the developing lung, the paradoxical responses of the pulmonary circulation to inflammatory cell interactions and mediators illustrate the complexities in cross talk. State-of-the-art advances in intravital microscopy have recently revealed our ability to visualize and measure the mechanotransduction involved in neutrophil migration. This review highlights these recent advances and suggests future directions for understanding pulmonary endothelial-inflammatory cell cross talk.

Bronchopulmonary dysplasia (BPD) is a neonatal lung disease characterized by inflammation and scarring leading to long-term tissue damage. Previous whole tissue proteomics identified BPD-specific proteome changes and cell type shifts. Little is known about the proteome-level changes within specific cell populations in disease. Here, we sorted epithelial (EPI) and endothelial (ENDO) cell populations based on their differential surface markers from normal and BPD human lungs. Using a low-input compatible sample preparation method (MicroPOT), proteins were extracted and digested into peptides and subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteome analysis. Of the 4,970 proteins detected, 293 were modulated in abundance or detection in the EPI population and 422 were modulated in ENDO cells. Modulation of proteins associated with actin-cytoskeletal function, such as SCEL, LMO7, and TBA1B was observed in the BPD EPIs. Using confocal imaging and analysis, we validated the presence of aberrant multilayer-like structures comprising SCEL and LMO7, known to be associated with epidermal cornification, in the human BPD lung. This is the first report of the accumulation of cornification-associated proteins in BPD. Their localization in the alveolar parenchyma, primarily associated with alveolar type 1 (AT1) cells, suggests a role in the BPD postinjury response. In the ENDOs, redox balance and mitochondrial function pathways were modulated. Alternative mRNA splicing and cell proliferative functions were elevated in both populations, suggesting potential dysregulation of cell progenitor fate. This study characterized the proteome of epithelial and endothelial cells from the BPD lung for the first time, identifying population-specific changes in BPD pathogenesis.NEW & NOTEWORTHY The study is the first to perform proteomics on sorted pulmonary epithelial and endothelial populations from bronchopulmonary dysplasia (BPD) and age-matched control human donors. We identified an increase in cornification-associated proteins in BPD (e.g., SCEL and LMO7), and evidenced the presence of multilayered structures unique to BPD alveolar regions, associated with alveolar type 1 (AT1) cells. By changing the nature and/or biomechanical properties of the epithelium, these structures may alter the behavior of other alveolar cell types potentially contributing to the arrested alveolarization observed in BPD. Finally, our data suggest the modulation of cell proliferation and redox homeostasis in BPD providing potential mechanisms for the reduced vascular growth associated with BPD.

Cadmium (Cd), a toxic heavy metal found in air pollution, poses serious risks to lung health due to its efficient pulmonary absorption and prolonged biological half-life. This study examines how ad libitum (AL), time-restricted feeding (TRF), and intermittent fasting (IF) influence Cd-induced lung injury and immune responses in mice. Adult male C57BL/6 mice were preacclimated to AL, TRF, or IF regimens for 3 wk, followed by intratracheal exposure to cadmium chloride (CdCl₂; 0.5 mg/kg). Lung mechanics were assessed using flexiVent, bronchoalveolar lavage (BAL) fluid was analyzed for inflammation, and immune profiling was performed on spleens and mediastinal lymph nodes (MLNs) 14 days postexposure. Cd exposure increased immune cell infiltration in BAL fluid. IF mice showed significantly elevated inflammatory cytokines, while TRF mice had a modest increase. Histological analysis revealed greater lung inflammation in TRF mice, whereas lung mechanics were more impaired in IF mice, suggesting distinct injury profiles. Immune profiling showed that IF reduced activated and effector T-cell populations in the spleen but increased them in MLNs, indicating a shift in immune localization. Furthermore, compared to the AL, Cd-exposed IF mice had minimal changes in T-cell distribution but reduced effector CD4⁺ and CD8⁺ T-cells in the spleen and an increase in MLNs. In contrast, TRF mice exhibited minimal changes in T-cell distribution. These findings suggest that dietary regimens modulate immune responses and lung injury following Cd exposure. Feeding patterns play a critical role in shaping susceptibility to environmental toxicants and should be considered in future toxicological and immunological studies.NEW & NOTEWORTHY This study reveals that time-restricted feeding (TRF) and intermittent fasting (IF) distinctly modulate cadmium-induced lung injury and immune responses in mice. TRF worsened lung inflammation, while IF impaired lung function and altered immune cell distribution, indicating divergent mechanisms. These findings highlight how feeding patterns influence pulmonary responses to environmental toxicants and suggest that metabolic rhythms may shape airway immunity, offering new insight into dietary modulation as a potential strategy in lung injury management.

Ozone exposure increases the risk of infection, worsens lung diseases, and causes systemic health issues. As ambient ozone levels continue to rise globally, effective interventions are needed to reduce these harmful effects. Vitamin D, known for its anti-inflammatory properties, has been inversely linked to various lung conditions, including ozone-induced airway inflammation and reduced lung function. However, oral vitamin D supplementation has shown inconsistent results, possibly due to poor delivery to lung tissues. This study explores a novel approach using vitamin D aerosols to counter ozone-induced damage in primary human bronchial epithelial cells. Cells were pretreated with vitamin D aerosols apically or as a bulk addition basolaterally before ozone exposure at the air-liquid interface. Both treatment routes significantly reduced the ozone-induced secretion of the inflammatory cytokine IL-8. Furthermore, vitamin D suppressed the ozone-induced expression of inflammation- and oxidative stress-related genes, including CXCL8, FFAR2, PTGS2 (COX-2), and NFKB2. Gene set enrichment analysis indicated that vitamin D reversed ozone-driven pathways related to inflammation, oxidative stress, and immune dysfunction. In addition, vitamin D pretreatment reduced lipid peroxidation, glutathione oxidation, and formation of ozone-derived oxysterols, suggesting a membrane antioxidant effect. These findings support vitamin D's potential as a protective agent against inhaled oxidants and highlight inhaled delivery as a promising therapeutic strategy for treating lung diseases.NEW & NOTEWORTHY Vitamin D aerosols have the potential to protect against exposure to ozone and other inhaled oxidants and prevent the development and exacerbation of lung disease. Here, we show that aerosolized vitamin D treatment decreased ozone-induced oxidative stress and inflammatory responses, as well as decreased production of an oxysterol, β-epoxycholesterol, indicating vitamin D may act as a membrane antioxidant in the airway epithelium.

Idiopathic pulmonary fibrosis (IPF) is a fatal disease characterized by progressive and irreversible loss of lung function. CSP7 exerts antifibrotic effects on fibrotic lung (myo)fibroblasts, which are the primary effector cells in progressive pulmonary fibrosis (PF) via restoring p53-microRNA-34a-feedback induction. However, p53-microRNA-34a's role in the antifibrotic effects of nintedanib and pirfenidone has not been explored. We compared the effects of oral-gavage-fed standard-of-care antifibrotic drugs, nintedanib or pirfenidone, with CSP7 administered by intraperitoneal injection or via airway by dry powder inhalation against bleomycin-induced PF using wild type, p53 flox (p53^fl/fl), microRNA-34a flox (microRNA-34a^fl/fl), and tamoxifen inducible conditional knockout mice lacking p53 (p53^cKO) or microRNA-34a (miR-34a^cKO) expression in lung fibroblasts. Compared with wild type or p53^fl/fl or microRNA-34a^fl/fl mice, p53^cKO and miR-34a^cKO mice exhibited more severe post-bleomycin body weight and lung function loss, lower survival, and more extracellular matrix deposition. Although daily treatment of wild-type mice with CSP7 or with nintedanib or pirfenidone between days 14 and 21 post-bleomycin improved survival, body weight and lung function, combination of CSP7 with nintedanib or pirfenidone was more effective than either drug. Interestingly, p53^cKO- and miR-34a^cKO-PF mice resisted these treatments, supporting the importance of restoration of p53-miR-34a-feedback induction in lung (myo)fibroblasts for the antifibrotic effects.NEW & NOTEWORTHY Pulmonary fibrosis is a progressive and fatal fibroproliferative disease. The current drugs (nintedanib/pirfenidone) only slow clinical progression. Myofibroblasts are the primary effector cells of PF. We found that CSP7, nintedanib and pirfenidone exert antifibrotic effects through restoring p53-microRNA-34a feedback induction in lung (myo)fibroblasts. We further found that daily treatment of mice with CSP7/nintedanib/pirfenidone between days 14 and 21 post-bleomycin lung fibrosis improve survival, body weight and lung function, and combination therapy had added benefit.

Cystic fibrosis (CF) is a multiorgan disease caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene, leading to chronic pulmonary infections and hyperinflammation. Among pathogens colonizing the CF lung, Pseudomonas aeruginosa is predominant, infecting over 50% of adults with CF, and becoming antibiotic-resistant over time. Current therapies for CF, while providing tremendous benefits, fail to eliminate persistent bacterial infections, chronic inflammation, and irreversible lung damage, necessitating novel therapeutic strategies. Our group engineered mesenchymal stromal cell-derived extracellular vesicles (MSC EVs) to carry the microRNA let-7b-5p as a dual anti-infective and anti-inflammatory treatment. MSC EVs are low-immunogenicity platforms with innate antimicrobial and immunomodulatory properties, whereas let-7b-5p reduces inflammation. This study demonstrates that MSC EVs effectively blocked the formation of antibiotic-resistant P. aeruginosa biofilms on primary human bronchial epithelial cells (pHBECs), and let-7b-5p loading into MSC EVs conferred additional anti-inflammatory effects by reducing P. aeruginosa-induced IL-8 secretion by pHBECs. This approach holds promise for improving outcomes for people with CF, and future work will focus on optimizing delivery strategies and expanding the clinical applicability of MSC EVs to target other CF-associated pathogens.NEW & NOTEWORTHY This is the first study demonstrating that mesenchymal stromal cell extracellular vesicles (MSC EVs) block antibiotic-resistant P. aeruginosa biofilm formation and that let-7b-5p-loaded MSC EVs reduce inflammation in CF primary human bronchial epithelial cells.

Bronchopulmonary dysplasia (BPD) is the most common adverse outcome in preterm neonates and a high risk for early-onset emphysema and asthma. BPD is characterized by disrupted alveolar and microvascular development due to a variety of pathogenic factors, such as hyperoxia, inflammation, and dysbiosis. The resulting clinical manifestations are challenging, and current treatment options are limited. To improve therapeutic options, it is imperative to understand underlying causes. Resident lung mesenchymal stromal cells (L-MSCs) are important for alveolar microvascularization, repair, and regeneration. Here, we report the immediate effects of hyperoxia- and antibiotics-induced reduced bacterial load on L-MSCs and alveolar development using the hyperoxia-induced BPD mouse model. Newborn mice were exposed to hyperoxia from postnatal day 4 (P4) to P14, with room air recovery from P14 to P21. Dams received antibiotics-supplemented water (ampicillin, gentamycin, and vancomycin) from embryonic day 15 (E15) to P21. Hyperoxia significantly impaired alveolar development between P14 and P21, whereas both hyperoxia and antibiotic exposure impaired lung microvascular development. Moreover, hyperoxia reduced the number of pericytes, proliferative mesenchymal progenitors, Col13a1^POS matrix fibroblasts, and P2RY14^POS alveolar myofibroblasts. RNA sequencing (RNA-seq) of LY6A-sorted L-MSCs revealed differential expression of 103 genes in hyperoxia, 10 of which are related to mast cell biology. Antibiotic exposure also altered mesenchymal cell distribution, suggesting an additional impact on lung development. The transcriptomic landscape and distribution of important L-MSC subtypes and microvascular development are affected by hyperoxia and antibiotic exposure in a BPD mouse model. In conclusion, we show that hyperoxia- and antibiotics-induced reduced bacterial load affect the mesenchymal cell population, which may contribute to the development of BPD.NEW & NOTEWORTHY Bronchopulmonary dysplasia (BPD) is associated with preterm-born children, and antibiotic treatment increases the incidence. Lung repair is affected in BPD, and here we focused on the LY6A^POS lung mesenchymal cells (L-MSCs), which modulate repair. We show that hyperoxia, which induces BPD in rodents, and antibiotics affect the transcriptome of these cells, resulting in altered signaling to mast cells. Antibiotics also affected the hyperoxia-induced changes in the cellular composition of L-MSCs at early alveologenesis.