Pulmonary Microvascular Permeability Research Articles

Endothelial cell-derived extracellular vesicles modulate the therapeutic efficacy of mesenchymal stem cells through IDH2/TET pathway in ARDS

BackgroundAcute respiratory distress syndrome (ARDS) is a severe and fatal disease. Although mesenchymal stem cell (MSC)-based therapy has shown remarkable efficacy in treating ARDS in animal experiments, clinical outcomes have been unsatisfactory, which may be attributed to the influence of the lung microenvironment during MSC administration. Extracellular vesicles (EVs) derived from endothelial cells (EC-EVs) are important components of the lung microenvironment and play a crucial role in ARDS. However, the effect of EC-EVs on MSC therapy is still unclear. In this study, we established lipopolysaccharide (LPS) - induced acute lung injury model to evaluate the impact of EC-EVs on the reparative effects of bone marrow-derived MSC (BM-MSC) transplantation on lung injury and to unravel the underlying mechanisms.MethodsEVs were isolated from bronchoalveolar lavage fluid of mice with LPS - induced acute lung injury and patients with ARDS using ultracentrifugation. and the changes of EC-EVs were analysed using nanoflow cytometry analysis. In vitro assays were performed to establish the impact of EC-EVs on MSC functions, including cell viability and migration, while in vivo studies were performed to validate the therapeutic effect of EC-EVs on MSCs. RNA-Seq analysis, small interfering RNA (siRNA), and a recombinant lentivirus were used to investigate the underlying mechanisms.ResultsCompared with that in non-ARDS patients, the quantity of EC-EVs in the lung microenvironment was significantly greater in patients with ARDS. EVs derived from lipopolysaccharide-stimulated endothelial cells (LPS-EVs) significantly decreased the viability and migration of BM-MSCs. Furthermore, engrafting BM-MSCs pretreated with LPS-EVs promoted the release of inflammatory cytokines and increased pulmonary microvascular permeability, aggravating lung injury. Mechanistically, LPS-EVs reduced the expression level of isocitrate dehydrogenase 2 (IDH2), which catalyses the formation of α-ketoglutarate (α-KG), an intermediate product of the tricarboxylic acid (TCA) cycle, in BM-MSCs. α-KG is a cofactor for ten-eleven translocation (TET) enzymes, which catalyse DNA hydroxymethylation in BM-MSCs.ConclusionsThis study revealed that EC-EVs in the lung microenvironment during ARDS can affect the therapeutic efficacy of BM-MSCs through the IDH2/TET pathway, providing potential strategies for improving the therapeutic efficacy of MSC-based therapy in the clinic.

Activation of Pink1/Parkin-mediated mitochondrial autophagy alleviates exertional heat stroke-induced acute lung injury in rats.

To investigate the role of Pink1/Parkin-mediated mitochondrial autophagy in exertional heat stroke-induced acute lung injury in rats. Sixty SD rats were divided into four groups: normal group (CON group), normal Parkin overexpression group (CON + Parkin group), exertional heat stroke group (EHS group), and exertional heat stroke Parkin overexpression group (EHS + Parkin group). Adeno-associated virus carrying the Parkin gene was intravenously injected into the rats to overexpress Parkin in the lung tissue. An exertional heat stroke rat model was established, and survival curves were plotted. Lung micro-CT was performed, and lung coefficient and pulmonary microvascular permeability were measured. Compared with the EHS group, the survival rate of rats in the EHS + Parkin overexpression group was significantly increased, lung coefficient and pulmonary microvascular permeability were reduced, and pathological changes such as exudation and consolidation were significantly reduced. The levels of inflammatory factors IL-6, IL-1β, TNF- α, and ROS were significantly decreased; the degree of mitochondrial swelling in type II alveolar epithelial cells was reduced, and no vacuolization was observed. Lung tissue apoptosis was reduced, and the colocalization fluorescence of Pink1 and Parkin, as well as LC3 and Tom20, were increased. The expression of Parkin and LC3-II/LC3-I ratio in lung tissue were both increased, while the expression of P62, Pink1, MFN2, and PTEN-L was decreased. Impairment of Pink1/Parkin-mediated mitochondrial autophagy function is one of the mechanisms of exertional heat stroke-induced acute lung injury in rats. Activation of the Pink1/Parkin pathway can alleviate acute lung injury caused by exertional heat stroke.

Nicotinamide mononucleotide as a therapeutic agent to alleviate multi-organ failure in sepsis

BackgroundSepsis-caused multi-organ failure remains the major cause of morbidity and mortality in intensive care units with limited therapeutics. Nicotinamide mononucleotide (NMN), a precursor of nicotinamide adenine dinucleotide (NAD+), has been recently reported to be protective in sepsis; however, its therapeutic effects remain to be determined. This study sought to investigate the therapeutic effects of NMN in septic organ failure and its underlying mechanisms.MethodsSepsis was induced by feces-injection-in-peritoneum in mice. NMN was given after an hour of sepsis onset. Cultured neutrophils, macrophages and endothelial cells were incubated with various agents.ResultsWe demonstrate that administration of NMN elevated NAD+ levels and reduced serum lactate levels, oxidative stress, inflammation, and caspase-3 activity in multiple organs of septic mice, which correlated with the attenuation of heart dysfunction, pulmonary microvascular permeability, liver injury, and kidney dysfunction, leading to lower mortality. The therapeutic effects of NMN were associated with lower bacterial burden in blood, and less ROS production in septic mice. NMN improved bacterial phagocytosis and bactericidal activity of macrophages and neutrophils while reducing the lipopolysaccharides-induced inflammatory response of macrophages. In cultured endothelial cells, NMN mitigated mitochondrial dysfunction, inflammation, apoptosis, and barrier dysfunction induced by septic conditions, all of which were offset by SIRT3 inhibition.ConclusionNAD+ repletion with NMN prevents mitochondrial dysfunction and restrains bacterial dissemination while limiting inflammatory damage through SIRT3 signaling in sepsis. Thus, NMN may represent a therapeutic option for sepsis.

Human umbilical cord mesenchymal stromal cell small extracellular vesicle transfer of microRNA-223-3p to lung epithelial cells attenuates inflammation in acute lung injury in mice.

Acute lung injury (ALI), manifested as strong pulmonary inflammation and alveolar epithelial damage, is a life-threatening disease with high morbidity and mortality. Small extracellular vesicles (sEVs), secreted by multiple types of cells, are critical cellular communication mediators and can inhibit inflammation by transferring bioactive molecules, such as microRNAs (miRNAs). Thus, we hypothesized that sEVs derived from mesenchymal stromal cells (MSC sEVs) could transfer miRNAs to attenuate inflammation of lung epithelial cells during ALI. C57BL/6 male mice were intratracheally administered LPS (10mg/kg). Six hours later, the mice were randomly administered with MSC sEVs (40µg per mouse in 150µl of saline), which were collected by ultracentrifugation. Control group received saline administration. After 48h, the mice were sacrificed to evaluate pulmonary microvascular permeability and inflammatory responses. In vitro, A549 cells and primary human small airway epithelial cells (SAECs) were stimulated with LPS with or without MSC sEVs treatment. In vitro, MSC sEVs could also inhibit the inflammation induced by LPS in A549 cells and SAECs (reducing TNF-α, IL-1β, IL-6 and MCP-1). Moreover, MSC sEV treatment improved the survival rate, alleviated pulmonary microvascular permeability, and inhibited proinflammatory responses (reducing TNF-α, IL-1β, IL-6 and JE-1) in ALI mice. Notably, miR-223-3p was found to be served as a critical mediator in MSC sEV-induced regulatory effects through inhibition of poly (adenosine diphosphate-ribose) polymerase-1 (PARP-1) in lung epithelial cells. Overall, these findings suggest that MSC sEVs may offer a novel promising strategy for ALI.

Nitric oxide-mediated the therapeutic properties of induced pluripotent stem cell for paraquat-induced acute lung injury.

The mortality rate associated with acute lung injury (ALI) and its severe form, acute respiratory distress syndrome, is high. Induced pluripotent stem cell (iPSC) therapy is a potential treatment method for ALI, but its therapeutic efficacy is limited in injured lungs. Nitric oxide (NO) has various physiological actions. The current study investigated the effect of iPSCs pretreated with NO donors in paraquat (PQ)-induced ALI mouse model. Male C57BL/6 mice were intraperitoneally injected with PQ, followed by infusion of phosphate-buffered saline, iPSCs, L-arginine pretreated iPSCs, or Nitro-L-arginine methylester (L-NAME) pretreated iPSCs through the tail veins. Histopathological changes, pulmonary microvascular permeability, and inflammatory cytokine levels were analyzed after 3 or 28d. The effects on iPSC proliferation, migration, and adhesion were evaluated in vitro. More L-arginine-pretreated iPSCs were selectively trafficked into the injured pulmonary tissue of mice with LPS-induced ALI, drastically diminishing the histopathologic changes and inflammatory cytokine levels (IL-1β and IL-6). There was also markedly improved pulmonary microvascular permeability and pulmonary function. The NO inhibitor abolished the protective effects of iPSCs. In addition, the ability of L-arginine to promote the proliferation and migration of iPSCs was decreased by L-NAME pretreatment, suggesting that NO might mediate the therapeutic benefits of iPSC. The improvement of the iPSC physiological changes by the endogenous gaseous molecule NO reduces lung injury severity. L-Arginine represents a pharmacologically important strategy for enhancing the therapeutic potential of iPSCs.

Integrated Analysis of Tracheobronchial Fluid from Before and After Cardiopulmonary Bypass Reveals Activation of the Integrated Stress Response and Altered Pulmonary Microvascular Permeability.

Objective: We aim to comprehensively describe the transcriptional activity and signaling of pulmonary parenchymal and immune cells before and after cardiopulmonary bypass (CPB) by using a multi-omic approach coupled with functional cellular assays. We hypothesize that key signaling pathways from specific cells within the lung alter pulmonary endothelial cell function resulting in worsening or improving disease. Methods: We collected serial tracheobronchial lavage samples from intubated patients less than 2-years-old undergoing surgery with CPB. Samples were immediately processed for single cell RNA sequencing (10x Genomics). Cell clustering, cell-type annotation, and visualization were performed, and differentially expressed genes (DEG) between serial samples were identified. Metabolomic and proteomic analyses were performed on the supernatant using mass spectrometry and a multiplex assay (SomaScan) respectively. Functional assays were done using electric cell-substrate impedance sensing to measure resistance across human pulmonary microvascular endothelial cells (HPMECs). Results: Analysis of eight patients showed a heterogeneous mixture of pulmonary parenchymal and immune cells. Cell clustering demonstrated time-dependent changes in the transcriptomic signature indicating altered cellular phenotypes after CPB. DEG analysis was represented by genes involved in host defense, innate immunity, and the mitochondrial respiratory transport chain. Ingenuity pathway analysis showed upregulation of the integrated stress response across all cell types after CPB. Metabolomic analysis demonstrated upregulation of ascorbate and aldarate metabolism. Unbiased proteomic analysis revealed upregulation of proteins involved in cytokine and chemokine pathways. Post-CPB patient supernatant improved HMPEC barrier function, suggesting a protective cellular response to CPB. Conclusion: Children who undergo CPB for cardiac surgery have distinct cell populations, transcriptional activity, and metabolism that change over time. The response to ischemia-reperfusion injury in the lower airway of children appears to be protective, with the need to identify potential targets through future investigations.

Protective effect of barium chloride pretreatment on lung in mice with acute respiratory distress syndrome

To explore whether barium chloride (BaCl2) preconditioning has the protective effect on lipopolysaccharide (LPS)-induced acute respiratory distress syndrome (ARDS) model in mice and the possible mechanism. Sixty 8-12 week old healthy C57BL/6 male mice were randomly divided into control group, ARDS model group and BaCl2 pretreatment group, with 20 mice in each group. The BaCl2 pretreatment group was continuously injected with BaCl2 (4 mg/kg through the tail vein) for 3 days before ARDS model establishment. ARDS model was established by intratracheally injecting (3 mg/kg) LPS. The control group was intratracheally given the same volume of 0.9% normal saline. On 24th hour after ARDS model establishment, some mice were sacrificed for obtaining fresh lung tissue. And the right lower lobe of the lung was separated for observing the pathological changes of lung tissue while the left lung tissue was used to measure the wet/dry weight ratio (W/D) of the lung. Some mice were sacrificed for observing pulmonary microvascular permeability at 2nd hours after injecting Evans blue (EB) through tail vein. The left mice were killed for alveolar lavage to measure the levels of tumor necrosis factor-α (TNF-α) via enzyme linked immunosorbent assay (ELISA). Comparing with the control group, ARDS model group showed typical ARDS pathological changes, which included the increased W/D ratio (4.951±0.161 vs. 3.449±0.299, P < 0.01) and the content of EB in the lung tissue (μg/g: 0.130±0.027 vs. 0.085±0.011, P < 0.01), the damaged alveolar wall structure, lung congestion and exudates in the alveoli, as well as amounts of inflammatory cells. The pathological score of lung injury (10.33±1.15 vs. 1.67±0.58) and the level of TNF-α in BALF (ng/L: 900.85±247.80 vs. 68.21±5.79) were significantly increased in the ARDS model group (both P < 0.01). Comparing with the ARDS model group, the lung W/D ratio (4.620±0.125 vs. 4.951±0.161) and the EB content in the lung tissue (μg/g: 0.108±0.011 vs. 0.130±0.027) of BaCl2 pretreatment group were significantly reduced (both P < 0.01). And the damaged pulmonary structural BaCl2 pretreatment group were significantly alleviated. In addition, the pulmonary pathological score (5.00±1.00 vs. 10.33±1.15) and the level of TNF-α in BALF (ng/L: 169.16±73.33 vs. 900.85±247.80) were significantly decreased (both P < 0.01). Barium chloride pretreatment can improve the lung histopathological changes of ARDS model mice induced by LPS by reducing the permeability of pulmonary capillaries and local inflammatory reaction.Barium chloride has the protective effect against LPS attack in mice model of ARDS.

Protectin DX Relieve Hyperoxia-induced Lung Injury by Protecting Pulmonary Endothelial Glycocalyx.

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in premature infants with limited treatments and poor prognosis. Damaged endothelial glycocalyx leads to vascular permeability, lung edema and inflammation. However, whether hyperoxia increases neonatal pulmonary microvascular permeability by degrading the endothelial glycocalyx remains unknown. Newborn mice were maintained in 60-70% O2 for 7 days. Protectin DX (PDX), an endogenous lipid mediator, was injected intraperitoneally on postnatal d 0, 2, 4 and 6. Lung samples and bronchoalveolar lavage fluid were taken at the end of the study. Primary human umbilical vein endothelial cells (HUVECs) were cultured in 80%O2. Hyperoxia exposure for 7 days led to neonatal mice alveolar simplification with less radial alveolar count (RAC), mean linear intercept (MLI) and mean alveolar diameter (MAD) compared to the control group. Hyperoxia exposure increased lung vascular permeability with more fluid and proteins and inflammatory factors, including TNF-α and IL-1β, in bronchoalveolar lavage fluid while reducing the heparan sulfate (HS), the most abundant component of the endothelial glycocalyx, in the pulmonary endothelial cells. PDX relieve these changes. PDX attenuated hyperoxia-induced high expression of heparanase (HPA), the endoglycosidase that shed endothelial glycocalyx, p-P65, P65, and low expression of SIRT1. BOC-2 and EX527 abolished the affection of PDX both in vivo and intro. In summary, our findings indicate that PDX treatment relieves hyperoxia-induced alveolar simplification, vascular leakage and lung inflammation by attenuating pulmonary endothelial glycocalyx injury via the SIRT1/NF-κB/ HPA pathway.

Recombinant Human Thrombomodulin Reduces Mortality and Acute Lung Injury Caused by Septic Peritonitis in Rats.

This study aimed to investigate the therapeutic effects of recombinant human thrombomodulin (rhTM) on acute lung injury (ALI) caused by sepsis in rats. Rats that underwent cecal ligation and puncture (CLP) were treated with or without rhTM, and then mortality was analyzed. In another set of experiments, ALI was assessed. Furthermore, microthrombosis in the lungs was investigated by immunohistochemistry. Moreover, plasma inflammatory and anti-inflammatory cytokines, such as TNF-α, high-mobility group box chromosomal protein 1 (HMGB-1), and IL-10, were evaluated by ELISA. Production of TNF-α and HMGB-1 by isolated tissue macrophages (Mφs) was assessed in vitro. Mortality after CLP was significantly improved by rhTM treatment. In addition, rhTM treatment improved the wet/dry weight ratio of the lungs, the pulmonary microvascular permeability, and the lung injury scores in animals that underwent CLP. Microthrombosis was detected in the lungs after CLP. These pathophysiological changes were blunted by rhTM treatment. Increased plasma TNF-α and HMGB-1 levels were blunted by rhTM treatment; however, the anti-inflammatory cytokine IL-10 was significantly greater in the rhTM(+) group than in the rhTM(-) group. Increased TNF-α and HMGB-1 production by the tissue Mφs stimulated with LPS were significantly blunted by rhTM treatment in vitro, but the production of IL-10 by the tissue Mφs was not changed in the cells incubated with rhTM. Overall, rhTM improved the mortality caused by septic peritonitis. The possible mechanisms are most likely anti-inflammatory and anticoagulant effects, which lead to the prevention of ALI.

Protective effect of Ulinastatin on acute lung injury in diabetic sepsis rats

This study explored the protective effect and its possible mechanism of ulinastatin (UTI) on acute lung injury (ALI) in type 2 diabetes mellitus (DM) sepsis rats. Following treatment with UTI, the wet/dry weight (W/D) ratio, pathological changes, hypoxia-inducible factor-1ɑlpha (HIF-1ɑ) protein and Toll-like receptor 4 (TLR4) mRNA expression of lung tissues, the expression levels of interleukin-1beta (IL-1ß), IL-18, and tumor necrosis factor-alpha (TNF-ɑ), the contents of malondialdehyde (MDA) and superoxide dismutase (SOD) in serum were detected in type 2 DM sepsis rats. It was found that rats with type 2 DM and sepsis showed obvious damage in lung tissues with significantly increased inflammatory cells, necrosis, and swelling of alveolar epithelial cells, but UTI decreased the lung damage induced by DM and sepsis. In addition, compared with the control, the W/D ratio, serum IL-1ß, IL-18 and TNF-ɑ contents, HIF-1ɑ protein expression, TLR4 mRNA expression, pulmonary microvascular permeability, MDA content in serum in type 2 DM and sepsis groups were significantly increased in type 2 DM sepsis rats (p < 0.05). However, compared with the groups with type 2 DM sepsis, the W/D ratio, serum IL-1ß, IL-18, TNF-ɑ contents, HIF-1ɑ protein expression, TLR4 mRNA expression, and pulmonary microvascular permeability in UTI-treated group were significantly decreased, but the activity of SOD increased (p < 0.05). This study indicates that UTI can effectively reduce ALI induced by diabetic sepsis in rats through inhibiting inflammatory response, reducing oxidative stress, regulating hypoxia response pathway, and improving pulmonary microvascular permeability.

102 Vaping of Vitamin E Acetate Causes Acute Lung Injury in a Dose-dependent Manner in Sheep

IntroductionThe Centers for Disease Control and Prevention and the Food and Drug Administration have reported an increasing number of clinical cases of pulmonary injury following the use of e-cigarette/vaping products. Although the causative factors for the national outbreak of electronic-cigarette, or vaping product use-associated lung injury (EVALI) has not been established, CDC reported that vitamin E acetate (VEA) is strongly linked to the EVALI outbreak. In this study, we tested the hypothesis that VEA vaping causes acute lung injury in a dose-dependent manner in a sheep model.MethodsSheep were surgically prepared under anesthesia and analgesia with multiple vascular catheters (pulmonary arterial, left atrial, and femoral arterial). To assess pulmonary edema, the mediastinal lymph node vessel draining the lung was cannulated. After a 5-day surgical recovery, a tracheostomy tube and urinary catheter were placed. Then, the sheep were placed on a mechanical ventilator and VEA vaping was immediately started in the following groups: (1) vaped with glycerol (n=1); (2) vaped with 0.4mg of VEA (n=2); (3) vaped with 0.6mg of VEA (n=1); (4) vaped with 0.8mg of VEA (n=7); and (5) not injured, not treated (Sham, n=6). Sheep were resuscitated with lactated Ringer’s solution (4mL/kg/hr). Sheep in a conscious state was monitored with 4 hrs intervals for cardiopulmonary variables for 48 hrs.ResultsPulmonary gas exchange, represented by the PaO2/FiO2 ratio, was unchanged in sham, glycerol, and 0.4 mg VEA groups. In the 0.6 VEA group, the PaO2/FiO2 ratio was decreased from 42 to 48 hrs, while in the 0.8 mg VEA group, it was strongly decreased starting at 24 hrs and remained low throughout the remaining period. Lung lymph flow, an index of pulmonary microvascular permeability, was increased more than 2-fold in 0.6 and 0.8 mg VEA groups. Lung compliance also tended to decrease in all VEA groups.ConclusionsVEA vaping causes acute lung injury in a dose-dependent manner in sheep. Further studies should investigate underlying mechanistic aspects that cause increased microvascular permeability.

PM2.5 induces pulmonary microvascular injury in COPD via METTL16-mediated m6A modification

Fine particulate matter (PM2.5) exposure is a significant cause of chronic obstructive pulmonary disease (COPD), but the detailed mechanisms involved in COPD remain unclear. In this study, we established PM2.5-induced COPD rat models and showed that PM2.5 induced pulmonary microvascular injury via accelerating vascular endothelial apoptosis, increasing vascular permeability, and reducing angiogenesis, thereby contributing to COPD development. Moreover, microvascular injury in COPD was validated by measurements of plasma endothelial microparticles (EMPs) and serum VEGF in COPD patients. We then performed m6A sequencing, which confirmed that altered N6-methyladenosine (m6A) modification was induced by PM2.5 exposure. The results of a series of experiments demonstrated that the expression of methyltransferase-like protein 16 (METTL16), an m6A regulator, was upregulated in PM2.5-induced COPD rats, while the expression of other regulators did not differ upon PM2.5-induction. To clarify the regulatory effect of METTL16-mediated m6A modification induced by PM2.5 on pulmonary microvascular injury, cell apoptosis, permeability, and tube formation, the m6A level in METTL16-knockdown pulmonary microvascular endothelial cells (PMVECs) was evaluated, and the target genes of METTL16 were identified from a set of the differentially expressed and m6A-methylated genes associated with vascular injury and containing predicted sites of METTL16 methylation. The results showed that Sulfatase 2 (Sulf2) and Cytohesin-1 (Cyth1) containing the predicted METTL16 methylation sites, exhibited higher m6A methylation and were downregulated after PM2.5 exposure. Further studies demonstrated that METTL16 may regulate Sulf2 expression via m6A modification and thereby contribute to PM2.5-induced microvascular injury. These findings not only provide a better understanding of the role played by m6A modification in PM2.5-induced microvascular injury, but also identify a new therapeutic target for COPD.

Glaucocalyxin A alleviates lipopolysaccharide-induced inflammation and apoptosis in pulmonary microvascular endothelial cells and permeability injury by inhibiting STAT3 signaling.

Glaucocalyxin A (GLA), an ent-kauranoid diterpene derived from Rabdosia japonica var. glaucocalyx, possesses antibacterial, anti-oxidative and anti-neuroinflammatory properties. The present study aimed to investigate the potential mechanisms underlying GLA in the pathogenesis of pneumonia. Human pulmonary microvascular endothelial cells (hPMVECs) treated with lipopolysaccharide (LPS) were treated with GLA, followed by the detection of cell viability, inflammation, apoptosis and cell permeability. Furthermore, the protein expression levels of apoptosis- and permeability-associated proteins were determined using western blot analysis. Following treatment with a signal transducer and activator of transcription 3 (STAT3) activator, the protein expression levels of STAT3 and endoplasmic reticulum stress-associated proteins were determined, to confirm whether STAT3 signaling was mediated by GLA. Lastly, the mRNA expression level of inflammatory cytokines, apoptosis and permeability injury were also determined following treatment with a STAT3 activator. The results revealed that GLA ameliorated inflammation, apoptosis and permeability injury in LPS-induced hPMVECs. Following treatment with a STAT3 activator, the therapeutic effects of GLA on LPS-induced hPMVECs were abrogated. In conclusion, GLA alleviated LPS-induced inflammation, apoptosis and permeability injury in hPMVECs by inhibiting STAT3 signaling, which highlighted the potential therapeutic value of GLA in the treatment of pneumonia.

CircRNA_0001679/miR-338-3p/DUSP16 axis aggravates acute lung injury.

Acute lung injury (ALI) is a respiratory disorder characterized by acute respiratory failure. circRNA mus musculus (mmu)-circ_0001679 was reported overexpressed in septic mouse models of ALI. Here the function of circ_0001679 in sepsis-induced ALI was investigated. In vitro models and animal models with ALI were, respectively, established in mouse lung epithelial (MLE)-12 cells and C57BL/6 mice. Pulmonary specimens were harvested for examination of the pathological changes. The pulmonary permeability was examined by wet-dry weight (W/D) ratio and lung permeability index. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β in the bronchoalveolar lavage fluid (BALF), the lung tissues, and the supernatant of MLE-12 cells were measured by enzyme linked immunosorbent assay . Apoptosis was determined by flow cytometry. Bioinformatics analysis and luciferase reporter assay were used to assess the interactions between genes. We found that circ_0001679 was overexpressed in lipopolysaccharide (LPS)-stimulated MLE-12 cells. circ_0001679 knockdown suppressed apoptosis and proinflammatory cytokine production induced by LPS. Moreover, circ_0001679 bound to mmu-miR-338-3p and miR-338-3p targeted dual-specificity phosphatases 16 (DUSP16). DUSP16 overexpression reversed the effect of circ_0001679 knockdown in LPS-stimulated MLE-12 cells. Furthermore, circ_0001679 knockdown attenuated lung pathological changes, reduced pulmonary microvascular permeability, and suppressed inflammation in ALI mice. Overall, circ_0001679 knockdown inhibits sepsis-induced ALI progression through the miR-338-3p/DUSP16 axis.

Elevated Cytokine Levels in Plasma of Patients with SARS-CoV-2 Do Not Contribute to Pulmonary Microvascular Endothelial Permeability.

ABSTRACTThe vascular endothelial injury occurs in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, but the mechanisms are poorly understood. We sought to determine the frequency and type of cytokine elevations and their relationship to endothelial injury induced by plasma from patients with SARS-CoV-2 versus controls. Plasma from eight consecutively enrolled patients hospitalized with acute SARS-CoV-2 infection was compared to controls. Endothelial cell (EC) barrier integrity was evaluated using ECIS (electric cell-substrate impedance sensing) on human lung microvascular EC. Plasma from all SARS-CoV-2 but none from controls decreased transendothelial resistance to a greater degree than that produced by tumor necrosis factor-alpha (TNF-α), the positive control for the assay. Thrombin, angiopoietin 2 (Ang2), and vascular endothelial growth factor (VEGF), complement factor C3a and C5a, and spike protein increased endothelial permeability, but to a lesser extent and a shorter duration when compared to SARS-CoV-2 plasma. Analysis of Ang2, VEGF, and 15 cytokines measured in plasma revealed striking patient-to-patient variability within the SARS-CoV-2 patients. Pretreatment with thrombin inhibitors, single, or combinations of neutralizing antibodies against cytokines, Ca3 and C5a receptor antagonists, or with ACE2 antibody failed to lessen the SARS-CoV-2 plasma-induced EC permeability. The EC barrier destructive effects of plasma from patients with SARS-CoV-2 were susceptible to heat inactivation. Plasma from patients hospitalized with acute SARS-CoV-2 infection uniformly disrupts lung microvascular integrity. No predicted single, or set of, cytokine(s) accounted for the enhanced vascular permeability, although the factor(s) were heat-labile. A still unidentified but potent circulating factor(s) appears to cause the EC disruption in SARS-CoV-2 infected patients.IMPORTANCE Lung vascular endothelial injury in SARS-CoV-2 patients is one of the most important causes of morbidity and mortality and has been linked to more severe complications including acute respiratory distress syndrome (ARDS) and subsequent death due to multiorgan failure. We have demonstrated that in eight consecutive patients with SARS-CoV-2, who were not selected for evidence of endothelial injury, the diluted plasma-induced intense lung microvascular damage, in vitro. Known endothelial barrier-disruptive agents and proposed mediators of increased endothelial permeability in SARS-CoV-2, induced changes in permeability that were smaller in magnitude and shorter in duration than plasma from patients with SARS-CoV-2. The effect on endothelial cell permeability of plasma from patients with SARS-CoV-2 was heat-labile. The main plasma factor that causes the increased endothelial permeability remains to be identified. Our study provides a possible approach for future studies to understand the underlying mechanisms leading to vascular injury in SARS-CoV-2 infections.

Abstract 11496: Increased Pulmonary Microvascular Endothelial Permeability by E-Cigarette Aerosol: The Pathway from Lung to Peripheral Blood Vessels

Background: We reported that permeability of cultured microvascular endothelial cells is increased by incubation in e-cigarette (e-cig) users’ serum relative to that from smokers or non-users. It is unclear whether this is a direct effect of aerosol chemicals that reach the circulation, or an indirect response mediated by the e-cig users’ pulmonary epithelium. Hypothesis: Vaping increases microvascular endothelial permeability indirectly by signaling from alveolar epithelium. Methods: E-cig aerosol condensates were derived from e-liquids with and without nicotine (12 mg/mL free base), each containing menthol, vanillin, ethyl maltol, or cinnamaldehyde (2 mg/mL). Cell permeability was measured in human lung microvascular endothelial cells (HMVEC-Ls) using electric cell-substrate impedance sensing. Human Type II lung alveolar epithelial cells (ATII) were grown in serum-free air-liquid interface and exposed to e-cig aerosols with 0, 18, or 36 mg/mL nicotine (free base and salt), or air, 1 h/day for 3 days in an exposure chamber inside a CO 2 incubator. Results: Incubation of HMVEC-Ls with 0.3% v/v e-cig aerosol condensates from most e-liquids, with and without nicotine, decreased cell permeability (in contrast to the increased permeability that we reported from incubation with e-cig user serum). The exception was menthol + nicotine, which increased permeability (but reduced viability). When HMVEC-Ls were instead incubated with supernatant collected from ATII cells after exposure to e-cig aerosols, permeability was increased when supernatants were from exposure to aerosol with 36 mg/ml nicotine salt, but not 36 or 18 mg/mL freebase nicotine. Supernatants from similarly exposed ATII cells contained higher levels of the proinflammatory proteins MCP-1, IL-8, GROα, and MIP-1β when aerosol contained 36 mg/mL freebase nicotine (3/6 wells) or nicotine salt (5/6), but not 18 mg/ml nicotine (0/6). Conclusion: HVMEC-L permeability was not directly increased by e-cig aerosol condensate, but was increased by supernatant of alveolar epithelial cells exposed to high-nicotine aerosol, potentially mediated by elevated ATII cytokine production, indicating a potential indirect mechanism by which vaping increases pulmonary microvascular permeability.

High concentration of hydrogen ameliorates lipopolysaccharide-induced acute lung injury in a sirt1-dependent manner

The aim of this study was to investigate the efficacy and underlying mechanism of high concentration of hydrogen on lipopolysaccharide (LPS)-induced acute lung injury (ALI). We have established a corresponding mouse model and examined the function of hydrogen inhalation on lung pathology and pulmonary edema induced by LPS, as well as contents of IL-1β, TNF-α and IL-8. The pulmonary microvascular permeability and 66.7 % hydrogen on the expression of sirt1 and its downstream signaling molecules were tested. Results showed that 66.7 % hydrogen alleviated lung pathological changes and pulmonary edema caused by LPS, and reduced the degree of ALI by inhibiting pro-inflammatory cytokine release and oxidative stress response, thereby decreasing the expression of molecules related to intercellular adhesion. sirt1 contributed to the repair of LPS-induced ALI by hydrogen through the regulation of NF-κB and catalase expression. In conclusion, 66.7 % hydrogen protected against LPS-induced ALI by suppressing inflammatory response and oxidative stress mediated by NF-κB and catalase in a sirt1-dependent manner.

Pravastatin attenuates sepsis-induced acute lung injury through decreasing pulmonary microvascular permeability via inhibition of Cav-1/eNOS pathway

BackgroundDisruption of alveolar endothelial barrier caused by inflammation drives the progression of septic acute lung injury (ALI). Pravastatin, an inhibitor of HMG Co-A reductase, has potent anti-inflammatory effects. In the present study, we aim to explore the beneficial role of pravastatin in sepsis‐induced ALI and its related mechanisms. MethodsA septic ALI model was established by cecal ligation and puncture (CLP) in mice. The pulmonary microvascular endothelial cells (PMVECs) were challenged with lipopolysaccharide (LPS). The pathological changes in lung tissues were examined by HE staining. The pulmonary microvascular permeability was determined by lung wet-to-dry (W/D) weight ratio and Evans blue staining. The total protein concentration in bronchoalveolar lavage fluid (BALF) was detected by BCA assay. The levels of TNF-α, IL-1β, and IL-6 were assessed by qRT-PCR and ELISA. Apoptosis was determined by flow cytometry and TUNEL. Western blotting was performed for detection of target protein levels. The expression of VE-Cadherin in lung tissues was evaluated by immunohistochemical staining. ResultsPravastatin improved survival rate, attenuated lung pathological changes and reduced pulmonary microvascular permeability in septic mice. In addition, pravastatin restrained sepsis-induced inflammatory response and apoptosis in the lung tissues and PMVECs. Moreover, pravastatin up-regulated the levels of junction proteins ZO-1, JAM-C, and VE-Cadherin. Finally, pravastatin suppressed inflammation, apoptosis and enhanced the expression of junction proteins via regulating Cav-1/eNOS signaling pathway in LPS-exposed PMVECs. ConclusionPravastatin ameliorates sepsis-induced ALI through improving alveolar endothelial barrier disruption via modulating Cav-1/eNOS pathway, which may be an effective candidate for treating septic ALI.

Human mesenchymal stromal cells small extracellular vesicles attenuate sepsis-induced acute lung injury in a mouse model: the role of oxidative stress and the mitogen-activated protein kinase/nuclear factor kappa B pathway

Background aimsAcute lung injury (ALI) secondary to sepsis is a complex disease associated with high morbidity and mortality. Mesenchymal stem cells (MSCs) and their conditioned medium have been demonstrated to reduce alveolar inflammation, improve lung endothelial barrier permeability and modulate oxidative stress in vivo and in vitro. Recently, MSCs have been found to release small extracellular vesicles (sEVs) that can deliver functionally active biomolecules into recipient cells. The authors’ study was designed to determine whether sEVs released by MSCs would be effective in sepsis-induced ALI mice and to identify the potential mechanisms. MethodsA total of 6 h after cercal ligation and puncture, the mice received saline, sEV-depleted conditioned medium (sEVD-CM) or MSC sEVs via the tail vein. ResultsThe administration of MSC sEVs improved pulmonary microvascular permeability and inhibited both histopathological changes and the infiltration of polymorphonuclear neutrophils into lung tissues. In addition, the activities of antioxidant enzymes were significantly increased in the group treated with sEVs compared with the saline and sEVD-CM groups, whereas lipid peroxidation was significantly decreased. Furthermore, sEVs were found to possibly inhibit phosphorylation of the mitogen-activated protein kinase/nuclear factor kappa B (MAPK/NF-κB) pathway and degradation of IκB but increase the activities of nuclear factor erythroid 2-related factor 2 and heme oxygenase 1. ConclusionsThese findings suggest that one of the effective therapeutic mechanisms of sEVs against sepsis-induced ALI may be associated with upregulation of anti-oxidative enzymes and inhibition of MAPK/NF-κB activation.

The roles of sodium-potassium-chloride cotransporter isoform-1 in acute lung injury.

Acute lung injury (ALI) is often characterized by severe lung inflammation and pulmonary edema with poor gas exchange and hypoxemia. Alveolar inflammation and water flooding are, in fact, notable features of ALI pathogenesis. The sodium-potassium-chloride co-transporter isoform 1 (NKCC1), localized at the basolateral surface of the lung epithelium, drives water transport via back transport of Na+ and Cl− to the alveolar air space. NKCC1, therefore, is crucial in regulating alveolar fluid. Increased expression of NKCC1 results in increased alveolar fluid secretion and impaired alveolar fluid clearance. During ALI, the with no lysine kinase (WNK), oxidative stress responsive kinase 1 (OSR1), and STE20/SPS1-related proline/alanine-rich kinase (SPAK) pathways are activated, which upregulates NKCC1 expression. Proinflammatory cytokines also enhance the expression of NKCC1 via c-Jun N-terminal kinase-and p38-dependent pathways. NKCC1 activation also increases the expression of proinflammatory cytokines via cell rupture and activation of macrophages. Increased proinflammatory cytokines, in turn, recruit inflammatory cells to the site of injury and cause further lung damage. Animals with high expression of NKCC1 show more severe lung injury with presentations of more severe pulmonary edema and microvascular permeability, higher expression of proinflammatory cytokines, and greater neutrophilic infiltration. In contrast, animals with low expression of NKCC1 or those treated with NKCC1 inhibitors show less severe lung injury with milder levels of presentations of ALI. These reports collectively highlight a novel role of NKCC1 in ALI pathogenesis. Manipulation of NKCC1 expression levels could, therefore, represent novel modalities for effective ALI treatment.