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

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.

Lung diseases are major global causes of morbidity and mortality, yet the molecular basis of their observed sex differences remains unclear. Beyond their roles in reproductive biology, estrogens are central regulators of pulmonary homeostasis through three principal receptors: estrogen receptor α (ERα), estrogen receptor β (ERβ), and the G-protein-coupled estrogen receptor (GPER1). These receptors are widely expressed across the airway epithelium, smooth muscle, fibroblasts, lung endothelium, and immune cells, where they integrate slow, genomic transcriptional programs and rapid, membrane-initiated signaling cascades to regulate inflammation, oxidative balance, and tissue remodeling. ERβ, often the dominant pulmonary isoform, tends to preserve extracellular matrix integrity and attenuate maladaptive inflammation, whereas ERα frequently amplifies pro-inflammatory transcriptional programs. GPER1 mediates rapid non-genomic responses that modulate vascular tone, airway smooth-muscle reactivity, and innate immune function, and is both an important regulator of allergic inflammation and a modulator of oncogenic signaling. Together, estrogen receptor subtype balance, subcellular localization, and ligand context determine whether estrogenic signaling is protective or pathogenic. Clinically, this framework helps explain life-course and sex differences, such as post-pubertal female predominance of asthma, menstrual and pregnancy-related exacerbations, and enhanced Chronic Obstructive Pulmonary Disease (COPD) susceptibility in women at lower tobacco exposure. In this review, we synthesize mechanistic and clinical evidence across lung diseases; delineate areas where data remain incomplete or contradictory; and outline opportunities for experimental and translational innovation. These include development of receptor-selective or biased ligands, inhaled or localized delivery, and implementation of sex-aware clinical trial designs to leverage estrogen-receptor biology for precision respiratory therapeutics.

Microgravity is known to promote muscle loss and impair physical performance. The carotid bodies (CB) chemoreceptors are sensitive to several stimuli and have been associated with peripheral vascular control and deterioration in exercise performance. Accordingly, it is plausible that the CB chemoreflex drive may modify the microgravity-induced muscle changes and, consequently, exercise performance. Thus, it is reasonable to propose that a microgravity environment can alter the CB chemoreflex drive, affecting exercise performance. Hence, we aimed to determine the effects of simulated microgravity, through the hind-limb suspension model, on hypoxic ventilatory chemoreflex drive and to examine whether modulation of the CB chemoreflex function influences exercise performance. Adult male Wistar Kyoto rats underwent hind-limb suspension (HLS, n=6) or the Sham condition (n=4) for 2 weeks. A separate group of rats received bilateral injection of two adeno-associated viruses (AAVs) in the CB bifurcation (AVV-TH-Cre-SV40 and AVV-hSyn-DREADD(Gi)-mCherry) (HLS+CB-G_i, n=4) to partially inhibit the CB chemosensory responses. Clozapine-N-oxide (1 mg/kg/day) was administered via osmotic minipump to activate the inhibitory DREADD-Gi receptor. Before and after exposure to HLS, we measured the hypobaric-hypoxic ventilatory response (HHVR), muscle performance, and VO₂peak. HLS promotes a significant increase in HHRV and a decrease in body weight, back leg muscle strength, soleus mass, and VO₂peak. Notably, CB inhibition reduced the HLS-induced deterioration in muscle mass and strength, as well as body weight loss. Our findings suggest a novel role for CB chemoreceptors in mediating the decline in muscle strength induced by HLS, reduced muscle mass, and body weight loss.

Interest in respiratory stimulants has increased over the years. Research have intensified after the introduction of opioids that cause respiratory depression. In the most recent years, the indiscriminate consumption of opioids has generated concern and, consequently, there has been a growing number of studies focusing on respiratory stimulants that can mitigate opioid-induced respiratory depression (OIRD) without inducing withdrawal, as well as identifying the molecular mechanisms. Carotid Bodies (CBs) are polymodal sensors capable of detecting and responding to a wide variety of chemical stimuli, such as hypoxia, hypercapnia, hypoglycemia, hyperinsulinemia, hyperleptinemia, among others. CBs have emerged as a potential therapeutic target to alleviate or eliminate OIRD. In this review, we present the most recent data on the mechanisms by which CBs may counteract OIRD We also discuss if CBs stimulation may be a therapeutic target for relieve OIRD without affecting analgesia.

Pulmonary fibrosis (PF) is a major cause of morbidity and mortality. Although increased oxidative stress and altered metabolism are implicated in PF pathobiology, our knowledge regarding the contribution of the glucose metabolism to the synthesis of extracellular matrix (ECM) is still incomplete. Therefore, our objective was to determine altered metabolic pathways that contribute to bleomycin sulfate (BLM; 5 mg/kg)-induced PF in rats. We determined the effects of nebulized BLM on PF in CRISPR-edited rats expressing glucose-6-phosphate dehydrogenase (G6PD) variant (S188F; G6PD^S188F) and their wild-type (WT) littermates. Unexpectedly, application of BLM increased lung tissue volume in G6PD^S188F rats as compared to WT littermates. Masson's Trichrome staining and Ashcroft scoring revealed increased collagen in perivascular regions and around the airways and hydroxyproline within the lungs of G6PD^S188F + BLM as compared to WT + BLM rats. In addition, mass-spectrometry-based proteomics and spatial proteomics confirmed increased expression of pro-fibrotic proteins, including collagen1a1 and baculoviral IAP Repeat Containing 5, in the lungs of G6PD^S188F + BLM rats compared to WT + BLM rats. Since BLM increased expression of KEAP1, we suggest that BLM inactivated NRF2 and increased oxidized glutathione, an indicator of oxidative stress that increases ECM, in lungs of G6PD^S188F rats. Finally, unbiased metabolomics revealed down-regulated spermidine, a polyamine pathway metabolite that decreases BLM-induced collagen deposition, in the lungs of G6PD^S188F + BLM rats. Therefore, we propose that dysregulated polyamine pathway and antioxidant state exacerbated BLM-induced synthesis of ECM-related proteins in G6PD^S188F variant rats as compared to their WT littermates.

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.