Search Results (55)

Mucosal microbiota contribute broadly to host defense and immune homeostasis, while the lung and gut microbiota form a particularly important bidirectional ecological and immunological network that shapes pulmonary host defense, inflammatory injury, and tissue repair. In pneumonia, loss of colonization resistance and altered microbial metabolite production may weaken innate and adaptive immunity; respiratory infection, antibiotics, and critical-care exposures can, in turn, remodel both microbial communities. In acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), intestinal barrier failure, circulating microbial products, immune cell trafficking and, in selected settings, lymphatic or hematogenous dissemination of gut-derived organisms may aggravate alveolar–capillary injury. Alveolar macrophages integrate these signals through pattern-recognition, metabolic, and epigenetic pathways, linking microbial ecology to pathogen clearance and inflammatory resolution. The evidence, however, remains uneven. Mechanistic causality rests largely on animal studies, most human data are associative, and trials of microbiota-directed interventions are heterogeneous and strain-specific. This Review examines bacterial and viral pneumonia, sepsis-associated ALI and ventilator-associated injury; separates mechanistic, observational, and interventional evidence; and evaluates probiotics, live biotherapeutic products, microbial metabolites, and dietary approaches. Translation will depend on longitudinal sampling, source-resolved microbial tracking, metabolite-informed patient stratification, and adequately powered trials with clinically relevant endpoints. Full article

Plasma surfactant protein B (SPB) is a marker of alveolar–capillary barrier injury and is elevated in heart failure (HF). We assessed whether cardiopulmonary exercise testing (CPET) changes plasma SPB in advanced HF and whether the SPB response relates to exercise limitations, resting pulmonary hemodynamics, and outcomes. Fifty-one patients (mean age 55.6 ± 7.5 years) with advanced HF (NYHA II–III, left ventricular ejection fraction ≤ 35%) underwent comprehensive evaluation, including CPET and invasive hemodynamic assessment. Blood samples were collected before and after CPET. Patients were followed for 23.5 ± 12.6 months. The composite endpoint included death, urgent heart transplantation, or left ventricular assist device implantation. SPB concentrations increased after CPET (median [IQR]: 77.5 [60.5–106.5] vs. 87.2 [63.5–111.9] ng/mL; p < 0.001). Greater relative increases occurred in NYHA III patients and correlated with NT-proBNP. Relative SPB changes correlated positively with the VE/VCO₂ slope and negatively with the anaerobic threshold but not with resting systolic pulmonary artery pressure or pulmonary vascular resistance. Neither baseline nor post-exercise levels, nor their changes, predicted clinical outcomes. In conclusion, the SPB response to exercise reflects dynamic pulmonary barrier stress related to functional limitations in advanced HF but lacks prognostic value in this cohort. Full article

Preterm infants, especially extremely preterm infants under 28 weeks of gestation, face high mortality rates due to respiratory distress resulting from pulmonary immaturity. Conventional mechanical ventilation and extracorporeal membrane oxygenation (ECMO) therapy inevitably cause irreversible lung injury or severe complications, respectively. Here, we developed a microfluidic oxygenator (MO) mimicking the human alveolar-capillary barrier to provide respiratory support for preterm infants. These structures promoted uniform flow distribution, reduced high-shear stress and flow stagnation, and improved gas exchange efficiency. In vitro experiments demonstrated that a single-layer MO raised blood oxygen saturation from 64.7% to 96.5% at 8 mL/min, with a corrected vol% oxygen transfer of 5.24% (52.4 mL O₂/L blood). Hemolysis and coagulation measurements after a 6 h circulation confirmed good hemocompatibility, with most blood damage attributable to the pump. An eight-layer stacked MO was configured with a total priming volume of approximately 5.6 mL and a pressure drop of 25–35 mmHg at 24–40 mL/min, indicating its potential in pumpless extracorporeal circulation for preterm neonates. This MO holds promise for providing minimally invasive and customizable respiratory support in an artificial uterus system. Full article

Background: Magnetic particle imaging (MPI) is an emerging, tracer-based modality that directly detects superparamagnetic iron oxide nanoparticles (SPIONs) with exceptional sensitivity, quantitative signal behavior, and full immunity to air–tissue susceptibility artifacts. These features make MPI particularly well-suited for pulmonary imaging, where traditional techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine-based ventilation/perfusion (V/Q) imaging are limited by radiation exposure, low contrast, and motion-related signal degradation. Objective: This review synthesizes the current state of MPI for lung imaging, with emphasis on its physical principles, tracer development, preclinical applications, and its potential role in assessing pulmonary perfusion, vascular integrity, inflammation, and therapeutic responses. Methods: A systematic evaluation of preclinical studies was performed across three major application domains: pulmonary perfusion mapping, cell tracking and therapeutic monitoring, and vascular injury and permeability assessment. Study designs, SPION formulations, MPI acquisition strategies, and validation methods, including histopathology, biodistribution, broncho-alveolar lavage fluid (BALF) analysis, and Evans Blue assays, were examined to characterize methodological consistency and imaging performance. Results: MPI consistently demonstrated high-contrast, quantitative visualization of pulmonary blood flow, endothelial barrier disruption, inflammatory signaling, and transplanted or inhaled cell populations. Tracer engineering played a critical role: macroaggregated albumin superparamagnetic iron oxide nanoparticles (MAA-SPIONs) enabled capillary-level perfusion mapping, LS-008 improved temporal resolution and vascular delineation, Synomag/Synomag-D allowed quantification of vascular leakage in acute and chronic lung injury, and vascular cell adhesion molecule-1 (VCAM-1)-targeted probes provided molecular-level assessment of inflammation. Hybrid MPI-CT and MPI-MRI approaches further enhanced anatomic localization and enabled accurate pulmonary blood volume (PBV) estimation. Across studies, MPI measurements showed strong agreement with established biological assays and remained free of the artifacts that limit CT and MRI in the lung. Conclusions: Preclinical evidence demonstrates that MPI is a robust, radiation-free, and quantitatively precise modality for functional and molecular lung imaging. Its ability to map perfusion, track therapeutic agents, and noninvasively quantify vascular permeability positions MPI as a promising future alternative or complement to CT, MRI, and nuclear medicine for pulmonary assessment. Continued tracer optimization, system scaling, and clinical validation are key steps toward translating MPI into routine clinical use. Full article

Acute respiratory distress syndrome (ARDS) is a high-mortality condition lacking targeted treatments. Emerging evidence indicates that circadian rhythm disruption is a key factor in the development of ARDS. Core clock proteins control essential processes, including alveolar–capillary barrier function, inflammation, and tissue repair. The intensive care unit (ICU) environment and underlying illness create double hits that impair biological clocks, leading to a cycle of excessive inflammation and organ damage. This review highlights the central role of circadian rhythms in ARDS. Despite strong preclinical evidence, there are still many challenges for clinical application, including a lack of high-quality human studies and uncertainty about the optimal timing of interventions. Incorporating biological rhythm stabilization into multimodal ARDS management is a prerequisite step toward precision medicine. Future research should focus on mechanistic and translational studies to confirm the safety and effectiveness of chronomedicine in improving long-term patient outcomes. Full article

High-altitude workers in the Los Andes Mountains, known as “the Chilean miner model,” are exposed to chronic intermittent hypobaric hypoxia (CIHH). This intermittent condition differs from other models of chronic hypoxia, mainly due to the hypoxic pattern and the cardiovascular and pulmonary effects. There are reports of cardiopulmonary dysfunction and remodeling in human and animal models. However, research on some mechanisms of vascular function and the consequences of lung remodeling induced by CIHH is still lacking. Therefore, this study aims to characterize the effects of CIHH exposure on lung structure and redox status in a rat model of the Chilean miner, involving intermittent exposure to chronic cycles of normoxia/hypobaric hypoxia (96 h/96 h) in an experimental hypoxic chamber. Our results demonstrate that CIHH acts as a primary driver of pulmonary vascular remodeling by significantly increasing the medial wall thickness of small pulmonary arteries (<100 μm) and promoting a shift toward a more muscularized phenotype in previously non-muscularized vessels. Structurally, this was characterized by a marked reduction in alveolar space and a significant increase in the thickness of the alveolar-capillary barrier, suggesting impaired gas exchange capacity. These structural changes were strongly associated with a pro-oxidant state, evidenced by increased lipid peroxidation (malondialdehyde levels) and a concomitant reduction in antioxidant enzyme activities, such as superoxide dismutase (SOD) and catalase (CAT), in lung tissue. In conclusion, the CIHH model effectively replicates the complex interplay between chronic oxidative damage and structural lung remodeling, identifying the thickening of the arterial medial wall and alveolar septa as key pathological features of probably CIHH-induced pulmonary hypertension. Full article

Background/Objectives: High-altitude pulmonary edema (HAPE) remains a serious condition with limited preventive options. This study evaluated the prophylactic protective effects of nebulized human umbilical cord mesenchymal stem cell-derived extracellular vesicles (hUC-MSC-EVs) in a rat model of hypobaric hypoxia-induced lung injury and explored potential mechanistic clues, with a focus on oxidative stress and TEK/Tie2 signaling. Methods: Rats were exposed to hypobaric hypoxia (47 kPa; 9.7% O₂) for 72 h and received prophylactic nebulized hUC-MSC-EVs (300 μg/rat). Lung injury was evaluated by histopathology, wet-to-dry ratio, and bronchoalveolar lavage fluid (BALF) protein concentration. Invasive pulmonary function indices were measured using a forced oscillation system. BALF cytokines (TNF-α, IL-6, and IL-10), reactive oxygen species (ROS), and TEK/Tie2 expression in lung tissue were assessed. In addition, transcriptome sequencing (RNA-seq) was performed to characterize global transcriptional changes. N-acetylcysteine (NAC), a classical antioxidant, was included as an auxiliary mechanistic intervention to assess the association of ROS with TEK/Tie2 changes. Results: Compared with hypoxia controls, prophylactic nebulized hUC-MSC-EVs reduced histopathological injury, pulmonary edema, and barrier leakage, and improved pulmonary function indices. hUC-MSC-EV intervention also attenuated inflammatory responses in BALF, with decreased TNF-α and IL-6 and increased IL-10. Hypobaric hypoxia increased ROS accumulation and decreased TEK/Tie2 expression, whereas nebulized hUC-MSC-EVs reduced ROS and partially preserved TEK/Tie2 expression. NAC pretreatment similarly reduced ROS and was accompanied by Tie2 preservation. Conclusions: Prophylactic nebulized hUC-MSC-EVs mitigated hypobaric hypoxia-induced lung injury, accompanied by reduced oxidative stress, improved vascular barrier integrity, and preservation of TEK/Tie2 expression. These findings support nebulized hUC-MSC-EVs as a potential lung-targeted prophylactic strategy for hypobaric hypoxia-induced lung injury and suggest that ROS imbalance may be associated with Tie2 preservation. Full article

Acute respiratory distress syndrome (ARDS) remains a leading cause of morbidity and mortality in critically ill patients despite advances in supportive care and lung-protective ventilation. The syndrome is characterized by biological heterogeneity involving epithelial and endothelial injury, dysregulated inflammation, surfactant dysfunction, and impaired alveolar–capillary barrier integrity. This review integrates experimental, translational, and clinical evidence to examine the biological and molecular basis underlying ARDS, with particular emphasis on alveolar–capillary architecture, immune dysregulation, pulmonary mechanics, and the temporal evolution of diffuse alveolar damage. We further discuss emerging concepts in ARDS phenotyping and biomarker-based stratification as tools to address therapeutic heterogeneity and improve prognostic precision. Collectively, the evidence supports a shift from syndromic management toward biologically informed, precision-based approaches that may enable targeted interventions and improved clinical outcomes in ARDS. Full article

Introduction: Uremic toxins have been shown to cause adverse pulmonary effects by inducing endothelial and epithelial dysfunction, disrupting the alveolar-capillary barrier, and increasing inflammation and oxidative stress. This article reviews these effects with a specific focus on chronic kidney disease and the mechanisms by which uremic toxins affect lung tissue. Methods: A narrative review was conducted using keywords related to uremic toxins and lung injury to search the PubMed database. An advanced literature review was conducted in PubMed to identify studies explaining the mechanisms underlying lung pathophysiology in chronic kidney disease (CKD), with particular focus on CKD-induced pulmonary epithelial and endothelial dysfunction. Additionally, to highlight the pathological processes of lung congestion in CKD, studies on CKD-induced dysfunction of the alveolar-capillary barrier were retrieved. Studies published up to November 2025 were evaluated. Results: A total of 148 articles were reviewed in full text. Uremic toxins negatively impact lung tissue structure and function through multiple mechanisms, including oxidative stress, inflammation, and direct effects. Uremic toxins appear to share signaling pathways in endothelial cells, including those linked to Mitogen-activated protein kinases (MAPK), the Aryl Hydrocarbon Receptor (AhR), the receptor for advanced glycation end products (RAGE), and pro-inflammatory transcription factors such as nuclear factor κB (NF-κB). Additionally, oxidative stress acts as a pro-inflammatory signal shared by several uremic toxins. The mechanisms behind the harmful interactions between CKD and lung disease are mostly unknown, although more evidence exists for acute kidney injury (AKI). Conclusions: Chronic kidney disease, which leads to the buildup of uremic toxins, negatively affects the lungs. Overall, the accumulation of uremic toxins in CKD impairs endothelial and epithelial cells and the alveolar capillary barrier. Further research is needed to understand the specific mechanisms underlying these effects and to identify therapeutic options to protect the lungs in these patients. Full article

Cardiogenic pulmonary edema (CPE) is a life-threatening manifestation of acute heart failure characterized by rapid accumulation of fluid in the interstitial and alveolar spaces, leading to severe dyspnea, hypoxemia, and respiratory failure. The condition arises from elevated left-sided filling pressures that increase pulmonary capillary hydrostatic pressure, disrupt alveolo-capillary barrier integrity, and impair gas exchange. Neurohormonal activation further perpetuates congestion and increases myocardial workload, creating a vicious cycle of hemodynamic overload and respiratory compromise. Respiratory support is a cornerstone of management in CPE, aimed at stabilizing oxygenation, reducing the work of breathing, and facilitating ventricular unloading while definitive therapies, such as diuretics, vasodilators, inotropes, or mechanical circulatory support (MCS), address the underlying cause. Among available modalities, non-invasive ventilation (NIV) with continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) has the strongest evidence base in moderate-to-severe CPE, consistently reducing the need for intubation and providing rapid relief of dyspnea. High-flow nasal cannula (HFNC) represents an emerging alternative in patients with moderate hypoxemia or intolerance to mask ventilation, and should be considered an adjunctive option in selected patients with less severe disease or NIV intolerance, although its efficacy in severe presentations remains uncertain. Invasive mechanical ventilation is reserved for refractory cases, while extracorporeal membrane oxygenation (ECMO) and other advanced circulatory support modalities may be necessary in cardiogenic shock. Integration of respiratory strategies with hemodynamic optimization is essential, as positive pressure ventilation favorably modulates preload and afterload, synergizing with pharmacological unloading. Future directions include personalization of ventilatory strategies using advanced monitoring, novel interfaces to improve tolerability, and earlier integration of MCS. In summary, respiratory support in CPE is both a bridge and a decisive therapeutic intervention, interrupting the cycle of hypoxemia and hemodynamic deterioration. A multidisciplinary, individualized approach remains central to improving outcomes in this high-risk population. Full article

Acute lung injury (ALI) is in part precipitated by hyperbaric oxygen or other mechanical insults. It constitutes the fundamental pathological process underlying acute respiratory distress syndrome (ARDS). The manifestation of the condition is characterized by an uncontrolled inflammatory response and alveolar edema, consequent to the disruption of the alveolar–capillary barrier. This phenomenon is associated with elevated morbidity and mortality rates. The current therapeutic interventions for ALI are not well researched or articulated. However, recent studies have indicated that stem cells may possess therapeutic potential in the context of ALI. The present study demonstrates that these exosome preparations have the capacity to significantly ameliorate radiographic findings, histological parameters, and vascular permeability in murine models of ALI. Concurrently, they attenuate the inflammatory response to a certain extent. The present review commences with an examination of the pathogenic mechanisms and manifestations of pulmonary injury induced by hyperbaric oxygen or other external factors. The subsequent sections of the text provide detailed accounts of the latest advances in exosome-based therapies for mitigating such injury, including their mechanisms of action and future translational prospects. While exosome-based treatments have demonstrated considerable advancement in preclinical research, numerous challenges must be surmounted before their widespread implementation in clinical settings can be realized, underscoring the necessity for sustained research in this domain. Full article

Acute Respiratory Distress Syndrome (ARDS) is a severe complication of acute lung injury (ALI) characterized by acute hypoxemic respiratory failure and diffuse alveolar damage, with a high mortality rate and a current lack of treatments beyond supportive care. Its complex pathophysiology involves immune cell activation, pro-inflammatory cytokine release, and disruption of the alveolar–capillary barrier, leading to pulmonary edema and fibrosis. This review explores the potential of small interfering RNA (siRNA) therapy as a novel pathogenetic treatment for ARDS. The mechanism of RNA interference is described, highlighting its high specificity for silencing target genes. The paper then evaluates various animal models used in ARDS preclinical research, noting the advantages of large animals (pigs) for their physiological similarity to humans and the suitability of rodents for studying long-term fibrotic stages. Finally, the review summarizes promising in vivo studies where siRNA-mediated knockdown of several genes (e.g., TIMP1, BTK, LCN2, HDAC7, CCL2, NOX4, TNFα and TLR4) significantly reduced inflammation, improved lung histology, and increased survival. The collective evidence underscores siRNA’s considerable potential for developing targeted therapies against ARDS, moving beyond symptomatic care to address the root molecular mechanisms of the disease. Full article

Lung ischemia–reperfusion injury (LIRI) remains a major contributor to perioperative morbidity and mortality in thoracic surgery, especially for lung transplantations, where it is one of the principal drivers of primary graft dysfunction (PGD). Although substantial advances have been made in surgical technique, donor management, and perioperative care, LIRI continues to pose a significant clinical challenge. Mechanistically, LIRI reflects a combined pathology of oxidative stress, endothelial and glycocalyx disruption, innate immune activation, mitochondrial dysfunction, and regulated cell death, resulting in loss of alveolar–capillary barrier integrity and gas exchange failure. Current management is phase-specific and multimodal, spanning donor care and preservation, controlled reperfusion and lung-protective ventilation, and pharmacological treatments. Treatment candidates that target oxidative stress and inflammatory cascades (e.g., antioxidants, complement and adenosine pathways, mesenchymal stromal cell products, and dipeptidyl-peptidase-4 inhibition) show promise, yet translation into a clinical scenario remains difficult. Increasing evidence supports endothelial-preserving and mitochondria-sparing strategies, rigorous perioperative bundles, and biomarker-guided trials to move from pathophysiology to practice. Ultimately, addressing LIRI requires an integrated, multidisciplinary approach that spans surgical, anesthetic, and pharmacologic domains, with the goal of improving both early outcomes and long-term graft survival in lung transplant patients. Full article

Background: Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome (ARDS), remain major causes of morbidity and mortality, yet no targeted pharmacological therapy is available. Excessive neutrophil and macrophage infiltration drives reactive oxygen species (ROS) production and cytokine release, leading to alveolar–capillary barrier disruption and fatal respiratory failure. Methods: We applied an integrative multi-omics strategy combining single-cell transcriptomics, peripheral blood proteomics, and lung tissue proteomics in a lipopolysaccharide (LPS, 10 mg/kg)-induced mouse ALI model to identify key signaling pathways. Harpagide, an iridoid glycoside identified from our natural compound screen, was evaluated in vivo (40 and 80 mg/kg) and in vitro (0.1–1 mg/mL). Histopathology, oxidative stress markers (SOD, GSH, and MDA), cytokine levels (IL-6 and IL-1β), and signaling proteins (HIF-1α, p-PI3K, p-AKT, Nrf2, and HO-1) were quantitatively assessed. Direct target engagement was probed using surface plasmon resonance (SPR), the cellular thermal shift assay (CETSA), and 100 ns molecular dynamics (MD) simulations. Results: Multi-omics profiling revealed robust activation of HIF-1, PI3K/AKT, and glutathione-metabolism pathways following the LPS challenge, with HIF-1α, VEGFA, and AKT as core regulators. Harpagide treatment significantly reduced lung injury scores by ~45% (p < 0.01), collagen deposition by ~50%, and ROS accumulation by >60% relative to LPS (n = 6). The pro-inflammatory cytokines IL-6 and IL-1β were reduced by 55–70% at the protein level (p < 0.01). Harpagide dose-dependently suppressed HIF-1α and p-AKT expression while enhancing Nrf2 and HO-1 levels (p < 0.05). SPR confirmed direct binding of Harpagide to HIF-1α (KD = 8.73 µM), and the CETSA demonstrated enhanced thermal stability of HIF-1α. MD simulations revealed a stable binding conformation within the inhibitory/C-TAD region after 50 ns. Conclusions: This study reveals convergent immune–microenvironmental regulatory mechanisms across cellular and tissue levels in ALI and demonstrates the protective effects of Harpagide through multi-pathway modulation. These findings offer new insights into the pathogenesis of ALI and support the development of “one-drug, multilayer co-regulation” strategies for systemic inflammatory diseases. Full article

Acute lung injury (ALI) is a severe pulmonary disorder characterized by the disruption of the alveolar–capillary barrier, leading to impaired oxygenation and pulmonary edema. Current pharmacological interventions primarily involve the use of steroid drugs, oxygen radical scavengers, and bronchodilators. However, the therapeutic efficacy of these interventions remains inconsistent. Canthin-6-ones, a class of tryptophan-derived alkaloids, exhibit anti-inflammatory, antioxidant, and immunomodulatory properties. In this study, we synthesized a novel Canthin-6-one derivative, namely HCX3, and evaluated its potential beneficial effects and underlying mechanisms on ALI. Prior to the experimental study, network pharmacology analysis revealed that HCX3 may exert anti-inflammatory effects in the context of ALI through the regulation of multiple signaling pathways, including the NF-κB pathways. To validate these findings, Lipopolysaccharide (LPS) was employed to stimulate RAW 264.7 macrophages and bone marrow-derived macrophages (BMDMs) to construct cellular models of inflammatory response associated with ALI. Our data demonstrated that exposure to HCX3 significantly inhibited the transcription and the secretion of multiple pro-inflammatory mediators, including IL-1β, IL-6, and TNF-α, in a dose-dependent manner. Additionally, HCX3 reduced LPS-induced phosphorylation levels of p65 and IκB-α in macrophages, indicating an inhibitory effect of the compound on the activation of NF-κB signaling pathway. Collectively, our data suggest that HCX3 exhibits significant anti-inflammatory effects by inhibiting NF-κB-related signaling pathways, providing new insights for ALI treatment. Full article