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

Chronic obstructive pulmonary disease (COPD) is characterized by a deficiency within the lungs of regulatory T cells and an excess of Th17 cells, termed T17/Treg imbalance. Conventional dendritic cells type-1 (cDC1) and type-2 (cDC2) are known to drive Treg and Th17 polarization, respectively, but their roles in COPD are incompletely understood. Using a murine cigarette smoke (CS)-exposure model, we found that after 8 wk of CS exposure, the percentage of lung cDC1, but not cDC2, was significantly decreased (P < 0.05) relative to air-exposed controls. Following intranasal adoptive transfer into naïve recipients, cDC1s were less likely to be retained in the lungs and instead were enriched in mediastinal lymph nodes. Coculture with DCs from cDC1-deficient BATF3^-/- mice induced greater expression of intracellular IL-17 protein by naïve lung CD4⁺ T cells compared with DCs from BATF3^+/+ mice (P < 0.001), which instead more greatly induced intracellular IFN-gamma. LPS-stimulated lung DCs from CS-exposed wild-type mice produced significantly higher amounts of the Th17-polarizing cytokines IL-6 and IL-23. Congruently, whole lung homogenates of CS-exposed mice had increased IL-17 protein expression compared with air-exposed mice (P < 0.05). Naïve CD4⁺ T cells cocultured with lung DCs from CS-exposed mice produced more IL-17 (P < 0.01) than coculture with lung DC from air-exposed mice. Thus, loss of cDC1 and predominance of cDC2 in the lungs of CS-exposed mice drive naïve CD4⁺ T cells toward IL-17 production and could play a role in the Th17/Treg imbalance seen in COPD.NEW & NOTEWORTHY Dendritic cell subsets play unique roles in chronic obstructive pulmonary disease (COPD) pathogenesis. We demonstrated that conventional DC type 1 (cDC1) are decreased, leading to a predominant cDC2 population in the lungs of a clinically relevant murine model of cigarette smoke exposure. This drives naive CD4⁺ T cells toward IL-17 production and could play a role in the Th17/Treg imbalance seen in COPD.

Survivors of coronavirus disease 2019 (COVID-19) can experience long-term lung complications (pulmonary sequelae), but the underlying mechanisms remain unclear. Although most patients with COVID-19 lung injury eventually recover essentially completely, some experience significant residual damage. To investigate the underlying differences, we analyzed, using bronchoalveolar lavage fluid (BALF), the alveolar immune cell compartments of a group of patients with post-COVID-19 interstitial lung disease (ILD) 6 mo after acute COVID-19. Patients were categorized into two groups, based on high-resolution computed tomography (HRCT) evaluation a year later: those with persistent HRCT abnormalities compatible with fibrosis (persistent post-COVID-19 ILD, n = 6) and those with resolved lung lesions (resolved post-COVID-19 ILD, n = 13). In addition, six patients with preexisting ILD were included in the study, after recovery from COVID-19. Bulk RNA transcriptomics analyses of BALF cells revealed innate immunity and inflammation pathways of neutrophil and monocyte chemotaxis to be enriched in patients with persistent HRCT abnormalities post-COVID-19, consistent with an increase in monocyte-like cell recruitment in the lungs. Profibrotic secreted phosphoprotein 1 (SPP1) gene expression was significantly upregulated similar to other fibrotic lung diseases. Conversely, patients with resolved post-COVID-19 ILD showed enhanced BALF cell gene expression signatures, indicative of adaptive immune response activation. BALF gene expression patterns of low T-cell activation, high profibrotic macrophage activation, and neutrophil chemotaxis were similarly observed in patients with preexisting fibrotic ILD following COVID-19. These findings suggest that immune response imbalance leading to prolonged activation of innate immunity and subdued adaptive immune responses may be associated with persistent post-COVID-19 ILD and the development of pulmonary fibrosis.NEW & NOTEWORTHY Survivors of COVID-19 can experience long-term lung complications. We compared bronchoalveolar lavage fluid (BALF) cells from patients who recovered from COVID-19 lung injury and those who experienced significant long term residual damage. A prominent gene expression profile of increased monocyte chemotaxis coupled to decreased T cell activation was observed in persistent fibrotic post-COVID-19 ILD. These findings suggest that prolonged activation of innate immunity and subdued adaptive immune responses may be associated with persistent post-COVID-19 ILD and pulmonary fibrosis.

Hyperoxia (HO) and mechanical ventilation (MV) are the mainstay of treatment for patients with acute respiratory failure, but both interventions can also accelerate further lung injury, highlighting the need for better therapeutic approaches. We previously found that HO decreases epithelial TREK-1 expression and promotes epithelial inflammation, but the consequences of TREK-1 deficiency in a clinically relevant system of combined HO + ST (stretch) exposure remain unknown. We found that in both mouse lung tissue and primary human alveolar epithelial cells, HO + ST downregulates TREK-1 protein levels. The injurious consequences of TREK-1 downregulation are evidenced in alveolar epithelial cells following pharmacological and genetic TREK-1 inhibition and in lungs of TREK-1 KO mice by potentiation of HO + ST-induced cytosolic ROS production, caspase-8 and caspase-1 activation, IL-1β production, and MIP-1α, and CXCL-10/IP-10 secretion. In addition, HO + MV-exposed TREK-1 KO mice show increased histological lung injury scores, total cell, macrophage, and neutrophil counts in the bronchoalveolar lavage fluid (BALF). Mechanistically, HO + ST depolarized the epithelial electrical membrane potential (Em) and raised iCa²⁺ levels, which was potentiated after pharmacological and genetic TREK-1 inhibition. Both Ca²⁺ influx through voltage-gated Ca²⁺ channels and Ca²⁺ release from intracellular stores increased iCa²⁺ levels following TREK-1 inhibition. Intratracheal administration of two structurally different pharmacological TREK-1 activators (ML335, BL1249) improved HO + ST-induced BALF total and differential cell counts, total protein levels, ROS production, caspase-8 and capase-1 production, and cytokine concentrations. Therefore, these findings highlight TREK-1 as new potential target for intervention against HO + ST/MV-induced lung and epithelial injury and lay the groundwork for future rational drug development.NEW & NOTEWORTHY No targeted interventions exist that improve the outcomes of patients with acute lung injury/ARDS. A few studies investigated Na⁺ and Ca²⁺ channels/transporters for potential therapeutic intervention but with limited translational success. This study highlights the regulatory role of TREK-1 K⁺ channels during HO+stretch/mechanical ventilation-induced lung injury in ROS production, caspase activation, cytokine secretion, and explores the underlying TREK-1-mediated signaling mechanisms. These preclinical findings lay the groundwork for future rational drug design targeting TREK-1 channels.

Particulate matter (PM) < 2.5 µm (PM_2.5) contributes to many chronic respiratory disorders, but the mechanisms for this are not fully understood. The actions of PM_2.5 on lung epithelial cells have been well studied, but their effect on lung fibroblasts has not been as extensively reported. Bone morphogenetic protein 2 (BMP2), part of the transforming growth factor cytokine family, plays crucial roles in the development, morphogenesis, repair, and functions as a critical mediator in the pathogenesis of lung diseases such as pulmonary fibrosis and chronic obstructive lung disease. Here, we investigate the impact of PM_2.5 on fibroblast BMP2 production and the role of BMP2 in mediating fibroblast-to-myofibroblast differentiation and matrix generation. Treatment of fibroblasts to PM_2.5 resulted in a dose-dependent rise in BMP2 mRNA and protein secretion, which was specific to BMP2 and not observed with other BMP family members. In normal quiescent fibroblasts, BMP2 induced an increase in collagen and α-smooth muscle actin expression. Interestingly, BMP2 exerted an opposite effect in TGF-β1-differentiated myofibroblasts, whereby BMP2 downregulated collagen levels. These differential responses aligned with variations in p38 and ERK1/2 phosphorylation. Fibroblasts treated with high concentrations of PM_2.5 demonstrated reduced collagen and α-smooth muscle actin expression, an effect reversed by BMP2 silencing or gremlin, a BMP2 antagonist. Overall, PM_2.5 was observed to induce BMP2 production in fibroblasts, and this was associated with suppression of fibroblast activation and matrix production by PM_2.5. These findings highlight a potential mechanism whereby PM_2.5 contributes to lung disease through impairment of fibroblast regenerative and repair capabilities.NEW & NOTEWORTHY Particulate matter <2.5 µm (PM_2.5) from air pollution contributes to many different lung diseases, but the mechanisms are not fully understood. Here, we demonstrated that PM_2.5 caused an upregulation of bone morphogenetic protein 2 (BMP2) in lung fibroblasts. BMP2 can promote myofibroblast differentiation or inhibit collagen expression, depending on the context, and can be a means by which PM_2.5 contributes to fibrotic and nonfibrotic lung diseases.

Defining preclinical models is of utmost importance for pleural mesothelioma (PM) to improve prognosis and predict therapeutic response. Using cells isolated from pleural fluid (PF) and diagnostic pleural biopsy (PB), we generated PM patient-derived organoids (PM-PDOs) and reactive-mesothelial (RM) patient-derived organoids (RM-PDOs) aiming at assessing the proportion of successful cultures both from PF and PB. We also compared the architectural and immune-histochemical features of PM-PDOs with those of parental tissues and evaluated the PM-PDOs response to chemoimmunotherapy. We obtained 11 successful PM-PDOs from 15 PF/PB (73.3%). The rate of success was higher in epithelioid PM (88.8%) compared with biphasic PM (40.0%) (P = 0.175), and when using PF (60.0%) compared with PB (20.0%) (P = 0.001). We also obtained 3 RM effective cultures from 6 asbestos-exposed patients (50%) with nonspecific pleuritis. Transcriptome analysis identified gene expression profile in PM-PDOs, which differentiate from RM-PDOs. PM-PDOs successfully maintained the histological architecture and molecular markers of their parental tumor tissues. The macrophagic component (CD68⁺ and CD163⁺) was an important component in RM-PDOs and was present in all three PM histotypes. Epithelioid PM-PDOs showed resistance to both Cis/PeMtx and pembrolizumab plus peripheral blood mononuclear cells (PBMCs), whereas both biphasic and sarcomatoid subtypes were sensitive to immunotherapy. Notably, immunotherapy induced an upregulation of PD-L1 expression and activated the STAT3/NF-κB signaling pathway, suggesting a mechanism of immune evasion. PF offers a valuable source of cancer and stromal cells to generate PDO, reinforcing its clinical utility for patients who cannot undergo invasive procedures.NEW & NOTEWORTHY Using cells isolated from pleural effusion and pleural biopsy, we established an efficient 3-D culture system for generating PM and reactive mesothelial (RM) patient-derived organoids. PM-PDOs expressed a specific gene profile, preserved the histological architecture, showing markers of the parental tumor tissues and recapitulated the tumor microenvironment (e.g., macrophages and tumor lymphocytes), which is an important factor influencing responses to therapy. This approach will be useful for drug screening, contributing to a more accurate selection of therapeutic options.

The potential for early life air pollutant exposure to result in later onset respiratory disease in children and adults is an emerging public health concern. Fetal growth restriction (FGR) and childhood respiratory infections are associated with impaired lung function in adulthood, and later in life, death from chronic obstructive pulmonary disease (COPD). We previously showed that early gestational exposure of rats to the oxidant air pollutant, ozone, resulted in asymmetrical FGR and lung developmental delays. Herein, we investigate effects of early gestational, periadolescent, and combined ozone exposure on offspring health, lung injury, antioxidant reserve, and innate immune responses. Results revealed similar ozone effects in all offspring irrespective of exposure timing in terms of minor weight loss, reduced body temperature (1.5-2.0°C), and moderate lung injury. Lung injury was inversely correlated with lung antioxidant capacity. Progeny of ozone-exposed dams (i.e., FGR-prone offspring) showed greater variability in ventilatory responses (EF₅₀, Penh) and increased Penh correlated with greater lung injury. FGR-prone offspring had more variable, often blunted immunoinflammatory responses to subsequent ozone exposure. Enhanced expression for antioxidant (Nrf2-related or ARE) genes were observed in FGR-prone males, whereas decreased expression for hypoxia (Hif-related or HRE) and RAAS genes (Ace, Agtr1, and Ace2) was observed in FGR-prone females, potentially suggesting that cross talk between redox transcription factors, Hif/RAAS, NF-κB, and Nrf2 led to differential responses. Collectively, these findings indicate that early life oxidant air pollutant exposure and resultant redox and RAAS dysregulation may impact both lung development and innate immune responses in a sex-dependent manner, effects that may increase vulnerability to respiratory infections.NEW & NOTEWORTHY This research investigates exposure factors and potential mechanisms contributing both to FGR and altered innate immune responses, effects that may impair lung function, limit immunity to respiratory pathogens, and perpetuate lung disease risk across the life span. Results suggest that oxidative stress and resultant redox and RAAS imbalance occurring at critical developmental intervals could be a central mechanism by which exposure to oxidant air pollutants negatively affect fetal growth, lung growth, and innate immune responsiveness.

Despite recent advances in preventative options, respiratory syncytial virus (RSV) infection is still a major cause of hospitalizations of young children and older adults, with no specific treatment available. The aryl hydrocarbon receptor (AHR) is a transcription factor originally identified as the mediator of the toxic effects of environmental pollutants but later shown to be also activated by dietary and endogenous ligands. AHR is involved in various physiological and pathophysiological processes, including host response to infections. Many clinically relevant viruses have been shown to induce AHR activation as a strategy to evade antiviral immunity and promote replication, including the severe acute respiratory syndrome coronavirus 2. It is currently not known whether RSV infection affects the AHR pathway. In this study, we investigated the effects of RSV infection on the AHR signaling pathway by using in vitro and in vivo experimental models. We found that RSV infection led to inhibition of the AHR-dependent gene transcription in human airway epithelial cells and in the lungs of mice. Human lung epithelial cells lacking AHR showed upregulation of genes related to inflammatory response and airway remodeling, as well as increased production of proinflammatory mediators in response to RSV infection. In contrast, administration of the dietary AHR ligand indole-3-carbinol to mice led to beneficial effects on RSV-associated disease, including anti-inflammatory and antiviral activity. Collectively, our results suggest that the AHR has a protective role during RSV infection, and therefore its modulation can be explored as a novel therapeutic target for RSV-induced disease.NEW & NOTEWORTHY Our study reveals that respiratory syncytial virus (RSV) downregulates the aryl hydrocarbon receptor (AHR) pathway in human airway epithelial cells and mouse lungs. Loss of the AHR in lung cells led to an exacerbated inflammatory response, and the AHR ligand indole-3-carbinol (I3C) showed in vivo anti-inflammatory and antiviral activity during RSV infection. Our data suggest that AHR plays a protective role during RSV infection and can be explored as a novel therapeutic target.

Bronchopulmonary dysplasia (BPD) associated pulmonary hypertension (PH) or BPD-PH is a lung disease of infants with significant morbidity. Adrenomedullin (Adm) is an angiogenic peptide that signals through calcitonin receptor-like receptor (Calcrl) and receptor activity modifying protein 2 (RAMP2). Adm deficiency potentiates hyperoxia-induced experimental BPD-PH in mice; however, whether Adm overexpression can mitigate this lung disease is unclear. Thus, we tested the hypothesis that Adm overexpression attenuates hyperoxia (HO)-induced murine experimental BPD-PH by using a novel transgenic mouse that overexpresses Adm globally (Adm^hi/hi mice). One-day-old Adm^hi/hi mice or their wild-type littermates (Adm^+/+ mice) were exposed to HO ([Formula: see text] 70%) for 14 days and allowed to recover in normoxia (NO, [Formula: see text] 21%) for an additional 14 days. Controls were maintained in NO for 28 days. On postnatal day (P) 14, we harvested the lungs to determine the extent of Adm expression and apoptosis. On P28, we quantified alveolarization, lung vascularization, and PH. HO-exposed Adm^+/+ mice demonstrated increased lung apoptosis, decreased alveolarization and lung vascularization, and indices of PH, indicating that neonatal HO exposure causes BPD-PH. However, Adm overexpression attenuated experimental BPD-PH, as evident by the decreased extent of hyperoxia-induced lung apoptosis and inflammation, alveolar and vascular simplification, pulmonary vascular remodeling, and PH in Adm^hi/hi mice than in Adm^+/+ mice. Collectively, our results demonstrate that Adm overexpression attenuates HO-induced murine experimental BPD-PH, emphasizing the therapeutic potential of Adm for BPD-PH in preterm infants.NEW & NOTEWORTHY The deficiency of the proangiogenic peptide, adrenomedullin (Adm), exacerbates the severe infantile lung disorder, bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH), in mice. However, whether Adm therapy can mitigate this disease is unclear. Our study, conducted with a rigorous methodology, suggests a potential solution. Using a novel mouse that overexpresses Adm to overcome the pharmacological limitations of the peptide, we demonstrate that Adm can mitigate this disorder, highlighting the therapeutic potential of Adm for human BPD-PH.

A sustained contraction of the airway smooth muscle increases its contractile capacity through a time-dependent process called force adaptation and concordantly increases the response to methacholine in healthy subjects. Whether this occurs in asthma remains to be investigated. The present study aimed at evaluating force adaptation on the methacholine response in asthmatic patients. Thirty-four very mild to mild asthmatic patients underwent a methacholine challenge on two separate visits. Although the same cumulative concentration was administered on both visits, one challenge was preceded by force adaptation induced by inhaling low concentrations of methacholine at 5-min intervals. On each visit, respiratory mechanics were monitored before and throughout the methacholine challenge by oscillometry, and the degree of inflammation was assessed by measuring the fraction of exhaled nitric oxide. The results demonstrate that the final response to methacholine was greater in the challenge with than without force adaptation. For example, whereas the average change in respiratory system reactance caused by the methacholine challenge without force adaptation was 55.4 ± 67.9%, it amounted to 118.1 ± 150.7% with force adaptation (P = 0.0069). Interestingly, force adaptation on the methacholine response was weakly but negatively correlated with the degree of inflammation. In fact, when patients were split into two groups, one with the least inflammation and one with the most inflammation, force adaptation potentiated the methacholine response in the former but not in the latter. We conclude that although force adaptation potentiates the response to methacholine in asthmatic patients, this effect is mainly driven by patients with very little inflammation.NEW & NOTEWORTHY A sustained contraction of the airway smooth muscle (ASM) increases its contractility through force adaptation, but whether this alters the methacholine response in asthma is unknown. Asthmatic patients underwent two methacholine challenges with identical cumulative concentration but one including a period of ASM preactivation. The preactivation enhanced the response in patients with little inflammation but not in more inflamed patients. This suggests that force adaptation increases the methacholine response only in patients with low inflammation.

The respiratory system is integrated to optimize efficiency. Dysfunction of one element often impacts others. For example, in chronic obstructive pulmonary disease (COPD), both obstructive sleep apnea and small airways dysfunction are associated with worse emphysema. In bronchopulmonary dysplasia (BPD), cystic lung disease and tracheobronchomalacia are often comorbid. Furthermore, childhood asthma predisposes to COPD. Although mouse models have elucidated key mechanisms in respiratory disease, to date, no models have accounted for how conducting airway dysfunction impacts alveolar structure and function. We report a novel murine partial tracheal occlusion (PTO) model and a complementary esophageal pressure monitoring technique to begin answering these questions. A 50% reduction in trachea diameter was achieved using a 19-gauge needle to prevent complete closure of a microsurgical clip on the anterior trachea. Esophageal pressure was measured by advancing a 3.5-French pressure transducing catheter 3 cm into the esophagus. In 8-10-wk-old C57BL/6 mice, PTO did not cause appreciable alteration of distal lung structure despite a 10-mmHg increase in transpulmonary pressure gradient. However, PTO after tracheal aspiration of 0.5 units of porcine pancreatic elastase (PPE) resulted in 20 µm greater (P < 0.001) mean linear intercept than PPE + sham. This model can be leveraged in mouse models of asthma, BPD, and COPD to understand how conducting airway dysfunction and increased transpulmonary pressure impacts distal lung structure. The PTO model is a relatively simple, well-tolerated model of conducting airway dysfunction that potentiates distal lung injury and expands our understanding of how mechanical forces influence pathological remodeling processes in the distal lung.NEW & NOTEWORTHY Lung diseases often involve both the conducting airways and the lung parenchyma, but we do not have tools to determine the mechanisms by which one affects the other. We developed a mouse partial tracheal occlusion model that increases the pressure required to generate a breath and also a novel way to measure this pressure. We can now test different hypotheses about how lung strain causes pathological lung remodeling.