Extracellular vesicles (EVs) are anuclear particles composed of lipid bilayers that contain nucleic acids, proteins, lipids, and organelles. EVs act as an important mediator of cell-to-cell communication by transmitting biological signals or components, including lipids, proteins, messenger RNAs, DNA, microRNAs, organelles, etc, to nearby or distant target cells to activate and regulate the function and phenotype of target cells. Under physiological conditions, EVs play an essential role in maintaining the homeostasis of the pulmonary milieu but they can also be involved in promoting the pathogenesis and progression of various respiratory diseases including chronic obstructive pulmonary disease, asthma, acute lung injury/acute respiratory distress syndrome, idiopathic pulmonary fibrosis (IPF), and pulmonary artery hypertension. In addition, in multiple preclinical studies, EVs derived from mesenchymal stem cells (EVs) have shown promising therapeutic effects on reducing and repairing lung injuries. Furthermore, in recent years, researchers have explored different methods for modifying EVs or enhancing EVs-mediated drug delivery to produce more targeted and beneficial effects. This article will review the characteristics and biogenesis of EVs and their role in lung homeostasis and various acute and chronic lung diseases and the potential therapeutic application of EVs in the field of clinical medicine.
DNA/metabolism* ; Extracellular Vesicles/metabolism* ; Humans ; Lipid Bilayers/metabolism* ; Lung Diseases/therapy* ; Lung Injury/metabolism* ; MicroRNAs/metabolism* ; Proteins/metabolism* ; Respiratory Distress Syndrome

BACKGROUND: Pulmonary microvascular endothelial cells (PMVECs) were not complex, and the endothelial barrier was destroyed in the pathogenesis progress of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Previous studies have demonstrated that hepatocyte growth factor (HGF), which was secreted by bone marrow mesenchymal stem cells, could decrease endothelial apoptosis. We investigated whether mTOR/STAT3 signaling acted in HGF protective effects against oxidative stress and mitochondria-dependent apoptosis in lipopolysaccharide (LPS)-induced endothelial barrier dysfunction and ALI mice. METHODS: In our current study, we introduced LPS-induced PMEVCs with HGF treatment. To investigate the effects of mammalian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) pathway in endothelial oxidative stress and mitochondria-dependent apoptosis, mTOR inhibitor rapamycin and STAT3 inhibitor S3I-201 were, respectively, used to inhibit mTOR/STAT3 signaling. Moreover, lentivirus vector-mediated mTORC1 (Raptor) and mTORC2 (Rictor) gene knockdown modifications were introduced to evaluate mTORC1 and mTORC1 pathways. Calcium measurement, reactive oxygen species (ROS) production, mitochondrial membrane potential and protein, cell proliferation, apoptosis, and endothelial junction protein were detected to evaluate HGF effects. Moreover, we used the ALI mouse model to observe the mitochondria pathological changes with an electron microscope in vivo. RESULTS: Our study demonstrated that HGF protected the endothelium via the suppression of ROS production and intracellular calcium uptake, which lead to increased mitochondrial membrane potential (JC-1 and mitochondria tracker green detection) and specific proteins (complex I), raised anti-apoptosis Messenger Ribonucleic Acid level (B-cell lymphoma 2 and Bcl-xL), and increased endothelial junction proteins (VE-cadherin and occludin). Reversely, mTOR inhibitor rapamycin and STAT3 inhibitor S3I-201 could raise oxidative stress and mitochondria-dependent apoptosis even with HGF treatment in LPS-induced endothelial cells. Similarly, mTORC1 as well as mTORC2 have the same protective effects in mitochondria damage and apoptosis. In in vivo experiments of ALI mouse, HGF also increased mitochondria structural integrity via the mTOR/STAT3 pathway. CONCLUSION In all, these reveal that mTOR/STAT3 signaling mediates the HGF suppression effects to oxidative level, mitochondria-dependent apoptosis, and endothelial junction protein in ARDS, contributing to the pulmonary endothelial survival and barrier integrity.
Animals ; Apoptosis ; Calcium/metabolism* ; Endothelial Cells/metabolism* ; Endothelium/metabolism* ; Hepatocyte Growth Factor/metabolism* ; Lipopolysaccharides/pharmacology* ; Mammals/metabolism* ; Mechanistic Target of Rapamycin Complex 1/metabolism* ; Mechanistic Target of Rapamycin Complex 2/metabolism* ; Mice ; Mitochondria/metabolism* ; Oxidative Stress ; Reactive Oxygen Species/metabolism* ; Respiratory Distress Syndrome ; Sirolimus/pharmacology* ; TOR Serine-Threonine Kinases/metabolism*

Animals ; Aquaporins/metabolism* ; Disease Models, Animal ; Glycoproteins/pharmacology* ; Humans ; Lung/metabolism* ; Protective Agents/pharmacology* ; Respiratory Distress Syndrome/physiopathology* ; Sus scrofa ; Trypsin Inhibitors/pharmacology* ; Up-Regulation

The 2019 novel coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has occurred in China and around the world. SARS-CoV-2-infected patients with severe pneumonia rapidly develop acute respiratory distress syndrome (ARDS) and die of multiple organ failure. Despite advances in supportive care approaches, ARDS is still associated with high mortality and morbidity. Mesenchymal stem cell (MSC)-based therapy may be an potential alternative strategy for treating ARDS by targeting the various pathophysiological events of ARDS. By releasing a variety of paracrine factors and extracellular vesicles, MSC can exert anti-inflammatory, anti-apoptotic, anti-microbial, and pro-angiogenic effects, promote bacterial and alveolar fluid clearance, disrupt the pulmonary endothelial and epithelial cell damage, eventually avoiding the lung and distal organ injuries to rescue patients with ARDS. An increasing number of experimental animal studies and early clinical studies verify the safety and efficacy of MSC therapy in ARDS. Since low cell engraftment and survival in lung limit MSC therapeutic potentials, several strategies have been developed to enhance their engraftment in the lung and their intrinsic, therapeutic properties. Here, we provide a comprehensive review of the mechanisms and optimization of MSC therapy in ARDS and highlighted the potentials and possible barriers of MSC therapy for COVID-19 patients with ARDS.
Adoptive Transfer ; Alveolar Epithelial Cells ; pathology ; Animals ; Apoptosis ; Betacoronavirus ; Body Fluids ; metabolism ; CD4-Positive T-Lymphocytes ; immunology ; Clinical Trials as Topic ; Coinfection ; prevention & control ; therapy ; Coronavirus Infections ; complications ; immunology ; Disease Models, Animal ; Endothelial Cells ; pathology ; Extracorporeal Membrane Oxygenation ; Genetic Therapy ; methods ; Genetic Vectors ; administration & dosage ; therapeutic use ; Humans ; Immunity, Innate ; Inflammation Mediators ; metabolism ; Lung ; pathology ; physiopathology ; Mesenchymal Stem Cell Transplantation ; methods ; Mesenchymal Stem Cells ; physiology ; Multiple Organ Failure ; etiology ; prevention & control ; Pandemics ; Pneumonia, Viral ; complications ; immunology ; Respiratory Distress Syndrome, Adult ; immunology ; pathology ; therapy ; Translational Medical Research

OBJECTIVE: To investigate the effects of Hippo signaling pathway on lung injury repair of mesenchymal stem cells (MSC) in acute respiratory distress syndrome (ARDS) and its mechanism. METHODS: Mouse bone marrow-derived MSC (mMSCs) cell lines with low expression of large tumor suppressor 2 (LATS2) were constructed by lentiviral vector transfection. Male C57BL/6 mice aging 6-8 weeks old were divided into four groups according to random number table (n = 36). The ARDS animal model (ARDS group) was reproduced by intratracheally injection of 2 g/L lipopolysaccharide (LPS) 50 μL, the normal saline (NS) control group was injected with an equal volume of NS. After 4 hours of model reproduction, 5×10⁴ mMSCs transfected with blank lentivirus vector (MSC-shcontrol group) or shLATS2 lentivirus vector (MSC-shLATS2 group) were transplanted intratracheally, while NS control group and ARDS group were injected with equal volume of phosphate buffered saline (PBS). Mice were sacrificed at 3, 7, and 14 days after modeling, and lung tissue and bronchoalveolar lavage fluid (BALF) were harvested. Near-infrared fluorescence imaging, immunofluorescence staining and Western Blot were used to track mMSCs in lung tissue. Retension and proportion of mMSC differentiation into type II alveolar epithelial cells (AEC II) were evaluated. Lung tissue wet weight/body weight ratio (LWW/BW) and total protein (TP) and albumin (ALB) in BALF were determined to reflect pulmonary edema. The expression of Occludin protein in lung epithelium was tested by Western Blot to reflect permeability of epithelium. The levels of interleukins (IL-1β, IL-6, IL-10) in BALF were assessed by enzyme-linked immunosorbent assay (ELISA) to reflect lung inflammation. Hematoxylin-eosin (HE) staining and modified Masson staining were carried out, and the scores were assessed to reflect lung injury and evaluate pulmonary fibrosis. RESULTS: The signal intensity of isolated lung fluorescence images at 3 days in the MSC-shLATS2 group was significantly higher than that in the MSC-shcontrol group (fluorescence intensity: 0.039±0.005 vs. 0.017±0.002, P < 0.05), the number of green fluorescent protein (GFP)-positive cells in lung tissue was also significantly higher than that in the MSC-shcontrol group (cells/HP: 29.65±6.98 vs. 17.50±4.58, P < 0.05), but they all decreased with time; and the proportion of mMSCs differentiated into AEC II was significantly increased [(64.12±15.29)% vs. (19.64±3.71)%, P < 0.05]. Compared with the NS control group, the levels of surface active protein C (SPC) and Occludin protein in the ARDS group were significantly decreased, LWW/BW ratio and TP, ALB and inflammatory factors levels in BALF were significantly increased; extensive alveolar and interstitial edema, hemorrhage and diffuse inflammatory cell infiltration were found in lung tissue, and the lung injury score was significantly increased; collagen fibers were deposited in alveolar septum and alveolar cavity, and pulmonary fibrosis score was also increased significantly. Compared with the ARDS group, the expression levels of SPC and Occludin at 14 days in the MSC-shcontrol group and the MSC-shLATS2 group were significantly increased (SPC/β-actin: 0.51±0.12, 0.68±0.10 vs. 0.27±0.08, Occludin/β-actin: 0.49±0.19, 0.79±0.11 vs. 0.25±0.08, all P < 0.05), TP, ALB, IL-1β, IL-6 levels in BALF at 3 days were significantly decreased [TP (g/L): 8.08±1.72, 5.12±0.87 vs. 12.55±2.09; ALB (g/L): 0.71±0.21, 0.44±0.18 vs. 1.18±0.29, IL-1β (ng/L): 99.26±14.32, 60.11±8.58 vs. 161.86±25.17, IL-6 (ng/L): 145.54±13.29, 101.74±11.55 vs. 258.79±27.88, all P < 0.05], and IL-10 was significantly increased (ng/L: 190.83±22.61, 316.65±37.88, both P < 0.05). Furthermore, all the above parameters in the MSC-shLATS2 group were significantly improved as compared with those in the MSC-shcontrol group (all P < 0.05). LWW/BW ratio in the MSC-shLATS2 group was significantly lower than that in the ARDS group and the MSC-shcontrol group (mg/g: 9.85±1.51 vs. 16.78±1.92, 14.88±1.74, both P < 0.05). CONCLUSIONS Inhibiting Hippo signaling pathway by low expression of LATS2 could promote the retention of mMSCs in lung tissue and differentiation into AEC II cells of ARDS mice, improve pulmonary edema and alveolar epithelial permeability, regulate pulmonary inflammatory response, and alleviate pathological damage and fibrosis of lung tissue.
Animals ; Hippo Signaling Pathway ; Lung Injury/prevention & control* ; Male ; Mesenchymal Stem Cells/metabolism* ; Mice ; Mice, Inbred C57BL ; Protein Serine-Threonine Kinases/metabolism* ; Respiratory Distress Syndrome/metabolism* ; Signal Transduction

OBJECTIVE: To explore whether extracellular histones aggravate acute respiratory distress syndrome (ARDS) by inducing peripheral blood mononuclear cell (PBMC) pyroptosis. METHODS: Twenty patients with ARDS admitted to Shanghai Pulmonary Hospital, Tongji University School of Medicine from April to September in 2019 were enrolled, and 20 healthy volunteers were enrolled as controls. In vivo experiment: peripheral blood samples of patients with ARDS within 24 hours after diagnosis and healthy volunteers were collected, and the levels of plasma extracellular histone, interleukins (IL-1β and IL-18) and lactic dehydrogenase (LDH) were determined by enzyme-linked immunosorbent assay (ELISA). PBMC were harvested, the expression levels of the pyroptosis associated N terminal-gasdermin-D (GSDMD-N) protein were determined by Western Blot. In vitro experiment: PBMC isolated from healthy volunteers were divided into four groups. Blank control group without any treatment; lipopolysaccharide (LPS) group was treated with 1 mg/L LPS for 4 hours; LPS+histones group was treated with 100 mg/L exogenous histones for 24 hours after LPS treatment; LPS+histone+heparin group was treated with 200 U heparin for 24 hours after LPS and exogenous histones treatment. The GSDMD-N protein expression was determined by Western Blot, and the levels of IL-1β, IL-18 and LDH in cell supernatant were determined by ELISA. Spearman test was used to test the correlation among the parameters. RESULTS: In vivo experiment results: compared with healthy control group, the GSDMD-N protein expression in PBMC of patients with ARDS was significantly increased [GSDMD-N/GAPDH: 0.136 (0.062, 0.246) vs. 0.026 (0.018, 0.036), P < 0.01], as well as the plasma levels of IL-1β, IL-18, LDH and extracellular histones [IL-1β (ng/L): 120.0 (94.2, 213.0) vs. 88.5 (82.3, 105.3), IL-18 (ng/L): 164.5 (70.8, 236.3) vs. 60.5 (52.0, 89.0), LDH (U/L): 30.9 (24.7, 39.5) vs. 19.8 (17.2, 21.5), extracellular histones (mg/L): 73.0 (42.8, 112.9) vs. 12.2 (9.6, 16.9), all P < 0.01], indicating that the PBMC of ARDS patients had significant pyroptosis and release of a large number of inflammatory factors. The oxygenation index (PaO₂/FiO₂) of ARDS patients was 135.5 (94.5, 196.0) mmHg (1 mmHg = 0.133 kPa). Correlation analysis showed that the expression of GSDMD-N protein in patients with ARDS was negatively correlated with PaO₂/FiO₂ (r = -0.935, P < 0.01) and positively correlated with IL-1β, IL-18, LDH and extracellular histones (r value was 0.844, 0.843, 0.887, 0.899, respectively, all P < 0.01). In vitro experiment results: compared with blank control group, the expression of GSDMD-N protein in PBMC and the levels of inflammatory mediators in the supernatant of the LPS group were significantly increased [GSDMD-N/GAPDH: 0.035±0.006 vs. 0.028±0.006, IL-1β (ng/L): 39.8±5.5 vs. 22.6±4.7, IL-18 (ng/L): 31.2±4.4 vs. 20.0±2.2, LDH (U/L): 51.2±7.3 vs. 36.6±7.6, all P < 0.05], indicating that LPS stimulation could increase PBMC pyroptosis and the release of inflammatory mediators. Compared with LPS group, the expression of GSDMD-N protein and the levels of inflammatory mediators of the LPS+histones group were further increased [GSDMD-N/GAPDH: 0.114±0.009 vs. 0.035±0.006, IL-1β (ng/L): 119.0±18.7 vs. 39.8±5.5, IL-18 (ng/L): 49.2±8.5 vs. 31.2±4.4, LDH (U/L): 127.8±19.8 vs. 51.2±7.3, all P < 0.01], indicating that the stimulation of LPS on PBMC could be significantly amplified by exogenous histone treatment, GSDMD-N protein expression could be up-regulated and inflammatory factor release could be promoted to further induce PBMC pyroptosis. These adverse effects of exogenous histones on PBMC could be abrogated by heparin, the expression of GSDMD-N protein and the levels of inflammatory mediators were significantly lower than those of LPS+histones group [GSDMD-N/GAPDH: 0.063±0.004 vs. 0.114±0.009, IL-1β (ng/L): 46.8±8.6 vs. 119.0±18.7, IL-18 (ng/L): 33.0±5.1 vs. 49.2±8.5, LDH (U/L): 65.4±11.0 vs. 127.8±19.8, all P < 0.05]. CONCLUSIONS Extracellular histones in plasma may aggravate ARDS by mediating PBMC pyroptosis.
China ; Histones/metabolism* ; Humans ; Interleukin-1beta ; Intracellular Signaling Peptides and Proteins ; Leukocytes, Mononuclear ; Phosphate-Binding Proteins ; Pyroptosis ; Respiratory Distress Syndrome

ObjectiveAcute respiratory distress syndrome (ARDS) is an acute and lethal clinical syndrome that is characterized by the injury of alveolar epithelium, which impairs active fluid transport in the lung, and impedes the reabsorption of edema fluid from the alveolar space. This review aimed to discuss the role of pro-resolving mediators on the regulation of alveolar fluid clearance (AFC) in ARDS.

Data SourcesArticles published up to September 2017 were selected from the PubMed, with the keywords of "alveolar fluid clearance" or "lung edema" or "acute lung injury" or "acute respiratory distress syndrome", and "specialized pro-resolving mediators" or "lipoxin" or "resolvin" or "protectin" or "maresin" or "alveolar epithelial cells" or "aspirin-triggered lipid mediators" or "carbon monoxide and heme oxygenase" or "annexin A1".

Study SelectionWe included all relevant articles published up to September 2017, with no limitation of study design.

ResultsSpecialized pro-resolving mediators (SPMs), as the proinflammatory mediators, not only upregulated epithelial sodium channel, Na,K-ATPase, cystic fibrosis transmembrane conductance regulator (CFTR), and aquaporins levels, but also improved Na,K-ATPase activity to promote AFC in ARDS. In addition to the direct effects on ion channels and pumps of the alveolar epithelium, the SPMs also inhibited the inflammatory cytokine expression and improved the alveolar epithelial cell repair to enhance the AFC in ARDS.

ConclusionsThe present review discusses a novel mechanism for pulmonary edema fluid reabsorption. SPMs might provide new opportunities to design "reabsorption-targeted" therapies with high degrees of precision in controlling ALI/ARDS.

Acute Lung Injury ; metabolism ; Animals ; Cystic Fibrosis Transmembrane Conductance Regulator ; metabolism ; Humans ; Respiratory Distress Syndrome, Adult ; metabolism

BACKGROUNDAn acute respiratory distress syndrome (ARDS) is still one of the major challenges in critically ill patients. This study aimed to investigate the effect of inhibiting c-Jun N-terminal kinase (JNK) on ARDS in a lipopolysaccharide (LPS)-induced ARDS rat model.

METHODSThirty-six rats were randomized into three groups: control, LPS, and LPS + JNK inhibitor. Rats were sacrificed 8 h after LPS treatment. The lung edema was observed by measuring the wet-to-dry weight (W/D) ratio of the lung. The severity of pulmonary inflammation was observed by measuring myeloperoxidase (MPO) activity of lung tissue. Moreover, the neutrophils in bronchoalveolar lavage fluid (BALF) were counted to observe the airway inflammation. In addition, lung collagen accumulation was quantified by Sircol Collagen Assay. At the same time, the pulmonary histologic examination was performed, and lung injury score was achieved in all three groups.

RESULTSMPO activity in lung tissue was found increased in rats treated with LPS comparing with that in control (1.26 ± 0.15 U in LPS vs. 0.77 ± 0.27 U in control, P < 0.05). Inhibiting JNK attenuated LPS-induced MPO activity upregulation (0.52 ± 0.12 U in LPS + JNK inhibitor vs. 1.26 ± 0.15 U in LPS, P < 0.05). Neutrophils in BALF were also found to be increased with LPS treatment, and inhibiting JNK attenuated LPS-induced neutrophils increase in BALF (255.0 ± 164.4 in LPS vs. 53 (44.5-103) in control vs. 127.0 ± 44.3 in LPS + JNK inhibitor, P < 0.05). At the same time, the lung injury score showed a reduction in LPS + JNK inhibitor group comparing with that in LPS group (13.42 ± 4.82 vs. 7.00 ± 1.83, P = 0.001). However, the lung W/D ratio and the collagen in BALF did not show any differences between LPS and LPS + JNK inhibitor group.

CONCLUSIONSInhibiting JNK alleviated LPS-induced acute lung inflammation and had no effects on pulmonary edema and fibrosis. JNK inhibitor might be a potential therapeutic medication in ARDS, in the context of reducing lung inflammatory.

Animals ; Anthracenes ; therapeutic use ; Collagen ; metabolism ; JNK Mitogen-Activated Protein Kinases ; antagonists & inhibitors ; metabolism ; Lipopolysaccharides ; toxicity ; Lung ; drug effects ; metabolism ; pathology ; Male ; Rats ; Respiratory Distress Syndrome, Adult ; chemically induced ; drug therapy ; Signal Transduction ; drug effects

OBJECTIVEAcute respiratory distress syndrome (ARDS) is an acute and lethal clinical syndrome that is characterized by hypoxemic respiratory failure and diffuse alveolar inflammatory damage. This review aimed to search and discuss the mass spectrometry (MS)-based proteomic studies on different subsets of ARDS patients.

DATA SOURCESOriginal research articles were collected from the PubMed database published in English up to December 2015.

STUDY SELECTIONThe literature search was done using the term "(acute lung injury OR acute respiratory distress syndrome) AND (proteomics OR proteome OR mass spectrum OR differential in-gel electrophoresis OR two-dimensional polyacrylamide gel electrophoresis)". Related original research articles were included and were carefully analyzed.

RESULTSEight original proteomic researches on ARDS patients were found. The common proteomic modalities were two-dimensional (2D) high-performance liquid chromatography-based electronic spray ion-MS/MS and 2D-polyacrylamide gel electrophoresis/differential in-gel electrophoresis-based matrix-assisted laser desorption ionization-time of flight/MS. They compared the proteome between ARDS patients and normal controls and analyzed the dynamic changes of proteome at different ARDS stages or severity. The disturbed proteome in ARDS patients includes plasma acute-phase proteins, inflammatory/immune-associated proteins, and coagulation proteins.

CONCLUSIONSAlthough several previous studies have provided some useful information about the lung proteome in ARDS patients and gained several interesting disease-associated biomarkers, clinical proteomic studies in ARDS patients are still in the initial stage. An increased cooperation is still needed to establish a global and faithful database containing disease-specific proteome from the largest ARDS subsets.

Acute-Phase Proteins ; metabolism ; Humans ; Lung ; metabolism ; pathology ; Mass Spectrometry ; methods ; Precision Medicine ; methods ; Proteomics ; methods ; Respiratory Distress Syndrome, Adult ; metabolism

To treat respiratory distress syndrome, surfactant is currently delivered via less invasive surfactant administration (LISA) or INtubation SURfactant Extubation (INSURE). The aim of this study was to compare the effect of the two delivery methods of surfactant on cerebral autoregulation. Near infrared spectroscopy monitoring was carried out to detect cerebral oxygen saturation (ScO), and the mean arterial blood pressure (MABP) was simultaneously recorded. Of 44 preterm infants included, the surfactant was administrated to 22 via LISA and 22 via INSURE. The clinical characteristics, treatments and outcomes of the infants showed no significant differences between the two groups. The correlation coefficient of ScOand MABP (r) 5 min before administration was similar in the two groups. During surfactant administration, rincreased in both groups (0.44±0.10 to 0.54±0.12 in LISA, 0.45±0.11 to 0.69±0.09 in INSURE). In the first and second 5 min after instillation, rwas not significantly different from baseline in the LISA group, but increased in the first 5 min after instillation (0.59±0.13, P=0.000 compared with the baseline in the same group) and recovered in the second 5 min after instillation (0.48±0.10, P=0.321) in the INSURE group. There were significant differences in the change rates of rbetween the two groups during and after surfactant administration. Our results suggest that cerebral autoregulation may be affected transiently by surfactant administration. The effect duration of LISA is shorter than that of INSURE (<5 min in LISA vs. 5-10 min in INSURE).
Administration, Intranasal ; adverse effects ; Brain ; metabolism ; Female ; Homeostasis ; Humans ; Infant, Newborn ; Infant, Premature ; Intubation ; adverse effects ; Male ; Oxygen Consumption ; Pulmonary Surfactants ; administration & dosage ; therapeutic use ; Respiratory Distress Syndrome, Newborn ; drug therapy ; therapy