Pulmonary Capillary Endothelial Cells Research Articles

AlveoMPU: Bridging the Gap in Lung Model Interactions Using a Novel Alveolar Bilayer Film.

The alveoli, critical sites for gas exchange in the lungs, comprise alveolar epithelial cells and pulmonary capillary endothelial cells. Traditional experimental models rely on porous polyethylene terephthalate or polycarbonate membranes, which restrict direct cell-to-cell contact. To address this limitation, we developed AlveoMPU, a new foam-based mortar-like polyurethane-formed alveolar model that facilitates direct cell-cell interactions. AlveoMPU features a unique anisotropic mortar-shaped configuration with larger pores at the top and smaller pores at the bottom, allowing the alveolar epithelial cells to gradually extend toward the bottom. The underside of the film is remarkably thin, enabling seeded pulmonary microvascular endothelial cells to interact with alveolar epithelial cells. Using AlveoMPU, it is possible to construct a bilayer structure mimicking the alveoli, potentially serving as a model that accurately simulates the actual alveoli. This innovative model can be utilized as a drug-screening tool for measuring transepithelial electrical resistance, assessing substance permeability, observing cytokine secretion during inflammation, and evaluating drug efficacy and pharmacokinetics.

Vascular endothelial-derived SPARCL1 exacerbates viral pneumonia through pro-inflammatory macrophage activation

Inflammation induced by lung infection is a double-edged sword, moderating both anti-viral and immune pathogenesis effects; the mechanism of the latter is not fully understood. Previous studies suggest the vasculature is involved in tissue injury. Here, we report that expression of Sparcl1, a secreted matricellular protein, is upregulated in pulmonary capillary endothelial cells (EC) during influenza-induced lung injury. Endothelial overexpression of SPARCL1 promotes detrimental lung inflammation, with SPARCL1 inducing ‘M1-like’ macrophages and related pro-inflammatory cytokines, while SPARCL1 deletion alleviates these effects. Mechanistically, SPARCL1 functions through TLR4 on macrophages in vitro, while TLR4 inhibition in vivo ameliorates excessive inflammation caused by endothelial Sparcl1 overexpression. Finally, SPARCL1 expression is increased in lung ECs from COVID-19 patients when compared with healthy donors, while fatal COVID-19 correlates with higher circulating SPARCL1 protein levels in the plasma. Our results thus implicate SPARCL1 as a potential prognosis biomarker for deadly COVID-19 pneumonia and as a therapeutic target for taming hyperinflammation in pneumonia.

Acute respiratory distress syndrome heterogeneity and the septic ARDS subgroup.

Acute respiratory distress syndrome (ARDS) is an acute diffuse inflammatory lung injury characterized by the damage of alveolar epithelial cells and pulmonary capillary endothelial cells. It is mainly manifested by non-cardiogenic pulmonary edema, resulting from intrapulmonary and extrapulmonary risk factors. ARDS is often accompanied by immune system disturbance, both locally in the lungs and systemically. As a common heterogeneous disease in critical care medicine, researchers are often faced with the failure of clinical trials. Latent class analysis had been used to compensate for poor outcomes and found that targeted treatment after subgrouping contribute to ARDS therapy. The subphenotype of ARDS caused by sepsis has garnered attention due to its refractory nature and detrimental consequences. Sepsis stands as the most predominant extrapulmonary cause of ARDS, accounting for approximately 32% of ARDS cases. Studies indicate that sepsis-induced ARDS tends to be more severe than ARDS caused by other factors, leading to poorer prognosis and higher mortality rate. This comprehensive review delves into the immunological mechanisms of sepsis-ARDS, the heterogeneity of ARDS and existing research on targeted treatments, aiming to providing mechanism understanding and exploring ideas for accurate treatment of ARDS or sepsis-ARDS.

Abstract 15509: “Root” Endothelial Cells: A Novel Population That Regulates Lung Capillary and Artery Maintenance and Repair

Introduction: Pulmonary capillary endothelial cells (ECs) are vital for various lung functions, such as maintaining the capillary network, promoting angiogenesis and facilitating gas and nutrient exchange. Recent advancements in single-cell transcriptomics have uncovered novel populations of general capillary ECs (gCaps) in the lungs. Understanding specialized EC types provides valuable insights into pulmonary vascular diseases. We aimed to challenge current understanding of the regenerative capabilities of lung resident ECs. Methods: Highly enriched ECs isolated from rat and mouse lungs underwent single-cell transcriptomics to explore EC population diversity. Results: UMAP annotation of ECs identified five novel general capillary cell populations (gCaps A-E). Lineage confirmation was achieved by Apelin receptor expression. Two distinct zonations (AV-zonation) were observed between pulmonary artery and vein ECs, with specific gCaps phenotypes (A: Clic4+, B: Flot1+, D: Scn7a+, E: Lingo2+), indicating a gradual phenotypic transition from arterial to vein ECs. Within the AV-zonation, a small population of gCapB (Flot1+) cells, resided at the interface of small artery ECs and gCap A and D, exhibiting characteristics of Root cells. RNA velocity analysis suggested Root cells as the origin of capillary and arterial cell lineages. PAGA analysis revealed high transcriptional similarity between gCapB and gCaps A, D, E and arterial cells, suggesting gCapB's role in capillary and arteriole formation and repair. Root cells exhibited upregulation of transcription factors Fos and Jun, promoting EC proliferation and angiogenesis, along with the Foxo and associated cell cycle regulation pathways. Root cells also displayed high G2M and S scores, indicating mitotic activity, supporting their role as the origin of capillary and arterial ECs. Elevated expression of CDKn1a and 1c, crucial for stem cell maintenance and differentiation further implied the repair potential of Root cells. Conclusions: Root Cells (gCapB) play a crucial role in regulating capillary and arteriole formation and repair by serving as a source of capillary and arterial ECs. These findings enhance our understanding of pulmonary vascular maintenance and repair mechanisms.

Programmed antigen capture-harnessed dendritic cells by margination-hitchhiking lung delivery.

Adoptive T cells and immunotherapy suppress the most destructive metastatic tumors and prevent tumor recurrence by inducing T lymphocytes. However, the heterogeneity and immune privilege of invasive metastatic clusters often reduce immune cell infiltration and therapeutic efficacy. Here, the red blood cells (RBC)-hitchhiking mediated lung metastasis delivery of multi-grained iron oxide nanostructures (MIO) programming the antigen capture, dendritic cell harnessing, and T cell recruitment is developed. MIO is assembled to the surface of RBCs by osmotic shock-mediated fusion, and reversible interactions enable the transfer of MIO to pulmonary capillary endothelial cells by intravenous injection by squeezing RBCs at the pulmonary microvessels. RBC-hitchhiking delivery revealed that >65% of MIOs co-localized in tumors rather than normal tissues. In alternating magnetic field (AMF)-mediated magnetic lysis, MIO leads to the release of tumor-associated antigens, namely neoantigens and damage-associated molecular patterns. It also acted as an antigen capture agent-harnessed dendritic cells delivers these antigens to lymph nodes. By utilizing site-specific targeting, erythrocyte hitchhiker-mediated delivery of MIO to lung metastases improves survival and immune responses in mice with metastatic lung tumors.

AQP5 and AQP1 as targets for prophylactic countermeasures for pulmonary hyperbaric oxygen toxicity

Oxygen exchange between lungs and systemic tissues is essential for life. However, breathing air with high O 2 levels can cause pulmonary O 2 toxicity (POT)—a serious health hazard for divers breathing O 2 -enriched gases at high pressure, and patients undergoing hyperbaric O 2 therapy or breathing through a mechanical ventilator. POT occurs because increased rates of O 2 uptake ( J O2 ) across the air-blood barrier lead to high intracellular O 2 concentration in alveolar type I cells (AT I Cs), AT II Cs, and in pulmonary capillary endothelial cells (PCECs). In principle, one could reduce POT by reducing J O2 . According to Fick’s law of diffusion, one approach for reducing J O2 would be to decrease O 2 membrane permeability ( P M, O2 ). In this work, we focus on the possibility of mitigating POT damage by manipulating P M, O2 across the cell membranes of AT I Cs (which cover about 90% of the alveolar surface) and PCECs.Research from the past 25 years has shown that membrane proteins (e.g., some aquaporins, AQPs) can conduct gases, thereby increasing P M . Notably, AQP5, which has the highest-known CO 2 permeability, is highly expressed in the apical membrane of AT I Cs, and AQP1, which can conduct both CO 2 and O 2 , is highly expressed in both PCECs membranes.We hypothesize that AQP5 mediates a large fraction of J O2 across the alveolar wall, and AQP1 does the same across PCECs membranes. If true, genetic deletion of AQP5 and/or AQP1 should reduce POT. We test this hypothesis with (1) a normobaric POT mouse model in which male mice (wild type, WT, vs knockout, KO) are continuously exposed to >99% O 2 (“↑O 2 ”) vs room Air (“Air”) for ~60-72 hr; (2) KO mice genetically deficient in AQP5, AQP1, or both (double knockouts, dKO); and (3) POT assays, namely H 2 O/dry-lung weight ratio (marker of lung edema) and, on bronchiolar-alveolar lavage fluid, lactate dehydrogenase (LDH; marker for AT I C leakage) and protein (mainly albumin from blood plasma; marker for blood-gas-barrier leakiness).Consistent with previous work (on WT and AQP5- & AQP1-KOs) by others, “H 2 O/dry weight” data show no differences between WT and KOs under “↑O 2 ” conditions. This negative result is consistent with the observed 10–15% weight loss (presumably all H 2 O), which would have reduced net Starling forces for ultrafiltration, making AQP KOs irrelevant. However, preliminary LDH and protein data are consistent with the idea that the KO of AQP5 and/or AQP1 reduces POT. For “↑O 2 ,” the AQP1-KO (vs. WT) shows a weak trend towards lower LDH; AQP5-KO and dKO show trends so strong that mean LDH does not differ from WT/“Air.” Moreover, for “↑O 2 ,” AQP5-KO and dKO have protein levels markedly lower than WT/“↑O 2 .” Finally, for “↑O 2 ,” we observe a progressive decrease in mouse mortality in the sequence WT > AQP1-KO >> AQP5-KO > dKO. If the observed trends continue for larger N’s, our data would argue that AQP5 and AQP1 are protective for POT and point, for the first time, towards a role of AQP5 in conducting O 2 . ONR: N00014-20-1-2737 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Influence of P-glycoprotein on pulmonary disposition of the model substrate [11C]metoclopramide assessed by PET imaging in rats

In the lungs, the membrane transporter P-glycoprotein (P-gp) is expressed in the apical (i.e. lumen-facing) membrane of airway epithelial cells and in the luminal (blood-facing) membrane of pulmonary capillary endothelial cells. To better understand the influence of P-gp on the pulmonary disposition of inhaled P-gp substrate drugs, we measured the intrapulmonary pharmacokinetics of the intratracheally (i.t.) aerosolized model P-gp substrate [11C]metoclopramide in presence and absence of P-gp activity by means of positron emission tomography (PET) imaging in rats. Data were compared to data previously acquired with the model P-gp substrates (R)-[11C]verapamil and [11C]N-desmethyl-loperamide, using the same experimental set-up. Groups of wild-type rats, either untreated or treated with the P-gp inhibitor tariquidar, and Abcb1a/b(-/-) rats underwent 90-min dynamic PET scans after i.t. aerosolization of [11C]metoclopramide. Lung exposure to [11C]metoclopramide was expressed as the area under the right lung concentration-time curve (AUClung). AUClung values were significantly higher in Abcb1a/b(-/-) rats (1.8-fold, p ≤ 0.0001) and in tariquidar-treated wild-type rats (1.6-fold, p ≤ 0.01) than in untreated wild-type rats. This differed from previously obtained results with (R)-[11C]verapamil and [11C]N-desmethyl-loperamide, which showed decreased exposure in the rat lung in absence of P-gp activity. Our results suggest that transepithelial transfer of [11C]metoclopramide was not or only to a small extent affected by P-gp activity, presumably due to the compound's high passive permeability. The increased lung retention of [11C]metoclopramide may be due to decreased P-gp-mediated clearance into the blood in absence of P-gp activity in capillary endothelial cells. The overall effect of P-gp on the lung exposure to inhaled P-gp substrate drugs may, thus, be determined by a balance of opposing effects at the pulmonary epithelium and endothelium.

Stimulation of the atypical chemokine receptor 3 (ACKR3) by a small-molecule agonist attenuates fibrosis in a preclinical liver but not lung injury model

Atypical chemokine receptor 3 (ACKR3, formerly CXC chemokine receptor 7) is a G protein-coupled receptor that recruits β-arrestins, but is devoid of functional G protein signaling after receptor stimulation. In preclinical models of liver and lung fibrosis, ACKR3 was previously shown to be upregulated after acute injury in liver sinusoidal and pulmonary capillary endothelial cells, respectively. This upregulation was linked with a pro-regenerative and anti-fibrotic role for ACKR3. A recently described ACKR3-targeting small molecule agonist protected mice from isoproterenol-induced cardiac fibrosis. Here, we aimed to evaluate its protective role in preclinical models of liver and lung fibrosis. After confirming its in vitro pharmacological activity (i.e., ACKR3-mediated β-arrestin recruitment and receptor binding), in vivo administration of this ACKR3 agonist led to increased mouse CXCL12 plasma levels, indicating in vivo interaction of the agonist with ACKR3. Whereas twice daily in vivo administration of the ACKR3 agonist lacked inhibitory effect on bleomycin-induced lung fibrosis, it had a modest, but significant anti-fibrotic effect in the carbon tetrachloride (CCl4)-induced liver fibrosis model. In the latter model, ACKR3 stimulation affected the expression of several fibrosis-related genes and led to reduced collagen content as determined by picro-sirius red staining and hydroxyproline quantification. These data confirm that ACKR3 agonism, at least to some extent, attenuates fibrosis, although this effect is rather modest and heterogeneous across various tissue types. Stimulating ACKR3 alone without intervening in other signaling pathways involved in the multicellular crosstalk leading to fibrosis will, therefore, most likely not be sufficient to deliver a satisfactory clinical outcome.

Correlation between circulating endothelial cell level and acute respiratory distress syndrome in postoperative patients.

BACKGROUNDAcute respiratory distress syndrome (ARDS) is injury of alveolar epithelial cells and capillary endothelial cells caused by various factors, including endogenous and exogenous lung factors, leading to diffuse pulmonary interstitial and alveolar edema, and acute respiratory failure. ARDS involves alveolar epithelial cells and pulmonary interstitial capillary endothelial cells. Circulating endothelial cells (CECs) are the only marker that directly reflects vascular endothelial injury in vivo. There have been few studies on the correlation between peripheral blood CECs and ARDS at home and abroad. The lungs are the organs with the highest capillary density and the most endothelial cells, thus, it is speculated that when ARDS occurs, CECs are stimulated and damaged, and released into the circulatory system. AIMTo explore the correlation between CEC level and severity of ARDS in patients postoperatively.METHODSBlood samples were collected from all patients on day 2 (d2) and day 5 (d5) after surgery. The control group comprised 32 healthy volunteers. Number of CECs was measured by flow cytometry, and operation time was recorded. Changes in various indexes of patients were monitored, and diagnosis of ARDS was determined based on ARDS Berlin definition. We comprised d2 CECs in different groups, correlation between operation time and d2 CECs, ARDS of different severity by d2 CECs, and predictive value of d2 CECs for ARDS in postoperative patients.RESULTSThe number of d2 CECs in the ARDS group was significantly higher than that in the healthy control group (P < 0.001). The number of d2 CECs in the ARDS group was significantly higher than that in the non-ARDS group (P < 0.001). The number of d2 CECs in the non-ARDS group was significantly higher than that in the healthy control group (P < 0.001). Operation time was positively correlated with number of CECs on d2 (rs = 0.302, P = 0.001). The number of d2 CECs in the deceased group was significantly higher than that in the improved group (P < 0.001). There was no significant difference in number of d2 CECs between patients with mild and moderate ARDS. The number of d2 CECs in patients with severe ARDS was significantly higher than that in patients with mild and moderate ARDS (P = 0.041, P = 0.037). There was no significant difference in number of d5 and d2 CECs in the non-ARDS group after admission to intensive care. The number of d5 CECs was higher than the number of d2 CECs in the ARDS improved group (P < 0.001). The number of d5 CECs was higher than the number of d2 CECs in the ARDS deceased group (P = 0.002). If the number of CECs was > 1351/mL, sensitivity and specificity of predicting ARDS were 80.8% and 78.1%, respectively. CONCLUSIONChanges in number of CECs might predict occurrence and adverse outcome of ARDS after surgery, and higher numbers of CECs indicate worse prognosis of ARDS.

MiR-181c-5p mediates apoptosis of vascular endothelial cells induced by hyperoxemia via ceRNA crosstalk

Oxygen therapy has been widely used in clinical practice, especially in anesthesia and emergency medicine. However, the risks of hyperoxemia caused by excessive O2 supply have not been sufficiently appreciated. Because nasal inhalation is mostly used for oxygen therapy, the pulmonary capillaries are often the first to be damaged by hyperoxia, causing many serious consequences. Nevertheless, the molecular mechanism by which hyperoxia injures pulmonary capillary endothelial cells (LMECs) has not been fully elucidated. Therefore, we systematically investigated these issues using next-generation sequencing and functional research techniques by focusing on non-coding RNAs. Our results showed that hyperoxia significantly induced apoptosis and profoundly affected the transcriptome profiles of LMECs. Hyperoxia significantly up-regulated miR-181c-5p expression, while down-regulated the expressions of NCAPG and lncRNA-DLEU2 in LMECs. Moreover, LncRNA-DLEU2 could bind complementarily to miR-181c-5p and acted as a miRNA sponge to block the inhibitory effect of miR-181c-5p on its target gene NCAPG. The down-regulation of lncRNA-DLEU2 induced by hyperoxia abrogated its inhibition of miR-181c-5p function, which together with the hyperoxia-induced upregulation of miR-181c-5p, all these significantly decreased the expression of NCAPG, resulting in apoptosis of LMECs. Our results demonstrated a ceRNA network consisting of lncRNA-DLEU2, miR-181c-5p and NCAPG, which played an important role in hyperoxia-induced apoptosis of vascular endothelial injury. Our findings will contribute to the full understanding of the harmful effects of hyperoxia and to find ways for effectively mitigating its deleterious effects.

Mechanism of Tanreqing Injection in treatment of acute lung injury based on network pharmacology and molecular docking

This study aimed to explore the mechanism of Tanreqing Injection in the treatment of acute lung injury(ALI) based on network pharmacology and molecular docking. The active components and action targets of Tanreqing Injection were retrieved from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP), PubChem, and SwissTargetPrediction databases, as well as available literature reports. The ALI-related targets were obtained from the GeneCards database and then mapped with Tanreqing Injection targets. Following the construction of &quot;drug-component-potential target&quot; network with Cytoscape 3.6.1, the potential targets were input into STRING to yield the protein-protein interaction(PPI) network, which was plotted using Cytoscape 3.6.1. Then the screened key targets were subjected to gene ontology(GO) and Kyoto encyclopedia of genes and genomes(KEGG) enrichment analysis based on DAVID database. The top three key targets RAC-alpha serine/threonine-protein kinase(AKT1), albumin(ALB) and interleukin-6(IL6) were docked to the top three key compounds by PyMOL and AutoDock vina. A total of 58 active components of Tanreqing Injection, 597 corresponding targets and 503 common targets shared by Tanreqing Injection and ALI were fi-gured out, with the key targets AKT1, ALB and IL6 involved. GO and KEGG enrichment analysis yielded 1 445 biological processes and 148 signaling pathways, respectively. Molecular docking verified a good binding ability of the top three key targets to the top three key compounds. The analysis based on network pharmacology and molecular docking uncovered that Tanreqing Injection directly or indirectly regulated the pulmonary capillary endothelial cells and alveolar epithelial cells via anti-inflammation, thus alleviating ALI.

Endothelial metabolism in pulmonary vascular homeostasis and acute respiratory distress syndrome.

Capillary endothelial cells possess a specialized metabolism necessary to adapt to the unique alveolar-capillary environment. Here, we highlight how endothelial metabolism preserves the integrity of the pulmonary circulation by controlling vascular permeability, defending against oxidative stress, facilitating rapid migration and angiogenesis in response to injury, and regulating the epigenetic landscape of endothelial cells. Recent reports on single-cell RNA-sequencing reveal subpopulations of pulmonary capillary endothelial cells with distinctive reparative capacities, which potentially offer new insight into their metabolic signature. Lastly, we discuss broad implications of pulmonary vascular metabolism on acute respiratory distress syndrome, touching on emerging findings of endotheliitis in coronavirus disease 2019 (COVID-19) lungs.

The upregulation of miR-204-3p in LPS-induced acute lung injury aggravated pulmonary endothelial cells apoptosis via targeting sulfatase 2.

Acute lung injury (ALI) results from the injury of alveolar epithelial cells and pulmonary capillary endothelial cells, with a high mortality rate ranging from 29% to 42%. Therefore, more efficient therapeutic strategies for ALI are necessary. Numerous studies revealed that miRNAs play a role in the regulation of ALI. Lipopolysaccharide (LPS) can induce an inflammatory response and has been widely applied in the establishment of the mouse ALI model. Here, we reported that miR-204-3p expression was upregulated by LPS treatment with increased cytokine secretion. LPS treatment promoted cell apoptosis, accompanied by abnormal cell structure and unobvious alveolar structure. These effects could be prevented by down-regulation of miR-204-3p, and promoted by miR-204-3p overexpression. Sulfatase 2 (SULF2) appeared to be the target of miR-204-3p predicted by TargetScan. Downregulation of miR-204-3p enhanced the protein level of SULF2, indicating that SULF2 was a target of miR-204-3p, which could negatively regulate the expression of SULF2. Thus, targeting miR-204-3p may be a potential therapeutic strategy for ALI.

Urinary Trypsin Inhibitor Protects Tight Junctions of Septic Pulmonary Capillary Endothelial Cells by Regulating the Functions of Macrophages.

BackgroundOur previous study found that urinary trypsin inhibitor (ulinastatin, UTI) protected tight junctions (TJs) of lung endothelia via TNF-α inhibition, thereby alleviating pulmonary capillary permeability in septic rats. As the activated macrophage is the main source of TNF-α in sepsis, we speculate that UTI may exert the above effects by regulating the functions of macrophages.MethodsBone-marrow derived macrophages (BMDM) were divided into control, lipopolysaccharide (LPS), UTI+LPS and UTI groups. TNF-α, TGF-β, IL-10, CD86, CD206 and MCP-1 expression were assessed by Western blot. The phagocytosis and migration of BMDM were detected. Pulmonary microvascular endothelial cells (PMVECs) were cultured with the conditioned medium (CM) from each group of BMDM above. Sprague-Dawley rats were divided into sham, cecal ligation and puncture (CLP), and UTI+CLP groups. Western blot and immunofluorescence were used to detected zonula occludens-1 (ZO-1), occludin and claudin-5 expression in PMVECs, as well as TNF-α, TGF-β, iNOS, CD86 and CD206 expression in lungs. Pulmonary capillary permeability was assessed by extravasated Evans blue, lung injury score (LIS), wet-to-dry weight ratio and electron microscope.ResultsTNF-α and CD86 expression were increased in LPS-treated BMDM, but were reversed by UTI pretreatment. TGF-β, IL-10 and CD206 expression were the opposite. UTI markedly decreased phagocytosis and migration of LPS-treated BMDM. ZO-1, occludin and claudin-5 expression were markedly decreased in PMVECs of the CM-LPS group, but significantly increased in the CM-UTI+LPS group. TNF-α, iNOS and CD86 expression were increased in the lungs of CLP-rats but decreased with UTI pretreatment, while TGF-β and CD206 expression were the opposite. UTI markedly ameliorated the lung EB leakage, improved LIS, reduced the wet-to-dry ratio and revised the damaged TJs of PMVECs in CLP-rats.ConclusionUTI effectively inhibits the conversion of M1 macrophage but increases M2, reduces the phagocytosis and migration, which helps to protect endothelia TJs and reduce pulmonary capillary permeability during sepsis.

Bilobalide Ameliorates Sepsis Induced Acute Lung Injury by Inactivating Toll-Like Receptor 4/Myeloid Differentiation Factor 88/Nuclear Factor-Kappa B Pathway

Acute lung injury refers to the injury of alveolar epithelial cells and pulmonary capillary endothelial cells caused by noncardiac factors. To better combat the disease, there is an urgent need to develop more effective drugs. Sepsis is a syndrome of systemic inflammation caused by infection, and the molecular mechanism by which sepsis induces acute lung injury has not been clearly determined. Bilobalide is a unique component of Ginkgo biloba. Although it has multiple biological functions, its role in sepsis induced acute lung injury needs further study. In this study, we found that bilobalide alleviated cecal ligation and puncture induced acute lung injury. Additionally, bilobalide regulated cecal ligation and puncture induced lung injury through toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-kappa B pathway. We therefore conclude that bilobalide may be a potential drug for the treatment of sepsis induced acute lung injury.

Metformin: one of the possible options to reduce the mortality of severe coronavirus disease 2019?

According to the world epidemic report, the mortality of patients with severe coronavirus disease 2019 (COVID-19) is high. Diabetic patients are more susceptible to COVID-19. Since the mortality of COVID-19 patients with diabetes is on the top of list, hyperglycemia is considered an independent risk factor for severe COVID-19. Up to now, there is few effective treatment for severe patients infected with 2019 novel coronavirus (2019-nCoV). Clinical studies observed that cytokine storms existed in patients with severe COVID-19. Sustained high levels of cytokines cause diffuse damage to pulmonary capillary endothelial cells and alveolar epithelial cells, resulting in acute respiratory distress syndrome (ARDS). ARDS is the main cause of death in COVID-19 patients. Host-directed therapy (HDT) is an emerging therapeutic method in the field of anti-infection, which can activate the self-protective immune response, suppress excessive inflammatory response, and be used to assist the treatment of traditional drugs to shorten the course of disease. Metformin has been shown to be effective in HDT and can assist in the treatment of the viral and bacterial infectious disease. This paper discusses the rationality and potential therapeutic mechanism of metformin in the treatment of severe COVID-19. It was speculated that the use of metformin for controlling blood glucose in severe COVID-19 patients with diabetes may prevent or inhibit the occurrence of ARDS, thereby reducing the mortality of COVID-19 patients. The possible mechanism is that metformin could inhibit cytokine storm via suppressing interleukin-6 (IL-6) signaling, prevent the process of lung fibrosis, suppress endocytosis, thereby elevating angiotensin converting enzyme 2 (ACE2) expression.

Reverse-D-4F improves endothelial progenitor cell function and attenuates LPS-induced acute lung injury

BackgroundPatients with acute lung injury (ALI) have increased levels of pro-inflammatory mediators, which impair endothelial progenitor cell (EPC) function. Increasing the number of EPC and alleviating EPC dysfunction induced by pro-inflammatory mediators play important roles in suppressing ALI development. Because the high density lipoprotein reverse-D-4F (Rev-D4F) improves EPC function, we hypothesized that it might repair lipopolysaccharide (LPS)-induced lung damage by improving EPC numbers and function in an LPS-induced ALI mouse model.MethodsLPS was used to induce ALI in mice, and then the mice received intraperitoneal injections of Rev-D4F. Immunohistochemical staining, flow cytometry, MTT, transwell, and western blotting were used to assess the effect of Rev-D4F on repairment of lung impairment, and improvement of EPC numbers and function, as well as the signaling pathways involved.ResultsRev-D4F inhibits LPS-induced pulmonary edema and decreases plasma levels of the pro-inflammatory mediators TNF-α and ET-1 in ALI mice. Rev-D4F inhibited infiltration of red and white blood cells into the interstitial space, reduced lung injury-induced inflammation, and restored injured pulmonary capillary endothelial cells. In addition, Rev-D4F increased numbers of circulating EPC, stimulated EPC differentiation, and improved EPC function impaired by LPS. Rev-D4F also acted via a PI3-kinase-dependent mechanism to restore levels of phospho-AKT, eNOS, and phospho-eNOS suppressed by LPS.ConclusionsThese findings indicate that Rev-D4F has an important vasculoprotective role in ALI by improving the EPC numbers and functions, and Rev-D4F reverses LPS-induced EPC dysfuncion partially through PI3K/AKT/eNOS signaling pathway.

Ulinastatin Ameliorates Pulmonary Capillary Endothelial Permeability Induced by Sepsis Through Protection of Tight Junctions via Inhibition of TNF-α and Related Pathways.

Background: Increased permeability of pulmonary capillary is a common consequence of sepsis that leads to acute lung injury. In this connection, ulinastatin, a urinary trypsin inhibitor (UTI), is used clinically to mitigate pulmonary edema caused by sepsis. However, the underlying mechanism of UTI in alleviating sepsis-associated pulmonary edema remains to be fully elucidated. As tight junctions (TJs) between the pulmonary microvascular endothelial cells (PMVECs) play a pivotal role in the permeability of pulmonary capillary, this study investigated the effect of UTI on expression of junctional proteins in PMVECs during sepsis.Methods: Male adult Sprague Dawley rats were subjected to cecal ligation and puncture (CLP) and divided into sham, CLP, and UTI+CLP groups. UTI was administered every 8 h for 3 days before CLP. At 48 h after surgery, Evans blue (EB) was administered to evaluate the pulmonary vascular leakage. Histological staining was used for evaluation of lung injury score. Using immunofluorescence staining and Western blot, the expression of junctional proteins (occludin, claudin-5, and ZO-1) in pulmonary endothelia was assessed. In vitro, PMVECs were divided into control, lipopolysaccharide (LPS), and UTI+LPS groups for examination of expression of junctional proteins and TNF-α as well as inhibitor of NF-κB (IκB), p38 mitogen-activated protein kinases (p38 MAPKs), c-Jun N-terminal kinases (JNKs), and extracellular signal-regulated kinases (ERKs) signaling pathways. Additionally, the expression of various junctional proteins was determined in PMVECs of control, LPS, and TNF-α receptor antagonist-LPS groups. PMVECs were also treated with TNF-α and TNF-α receptor antagonist and the expression of various junctional proteins was assessed.Results: Compared with the CLP group, UTI markedly decreased EB leakage and lung injury score. The expression of occludin, claudin-5, and ZO-1 was decreased in both CLP rats and LPS-treated PMVECs, but it was reversed by UTI and TNF-α receptor antagonist. TNF-α expression was vigorously elevated in the lung of CLP rats and in LPS-challenged PMVECs, which were suppressed by UTI. In addition, TNF-α also reduced occludin, claudin-5, and ZO-1 expression in PMVECs, but these effects of TNF-α were antagonized by pretreatment with TNF-α receptor antagonist. Furthermore, UTI inhibited LPS-induced activation of NF-κB and mitogen-activated protein kinases (MAPKs) pathways in PMVECs.Conclusion: UTI effectively protects TJs and helps to attenuate the permeability of pulmonary capillary endothelial cells during sepsis through inhibiting NF-κB and MAPKs signal pathways and TNF-α expression.

Sera From Children After Cardiopulmonary Bypass Reduces Permeability of Capillary Endothelial Cell Barriers.

Children undergoing cardiopulmonary bypass develop clinically impactful capillary leak of unclear etiology. A widely held hypothesis that exposure of circulating cells to the cardiopulmonary bypass circuit induces the release of inflammatory mediators that act to disrupt intercellular junctions of capillary endothelial cells inducing paracellular capillary leak either directly or through new gene expression. Cohort study. Tertiary pediatric hospital. Twenty children undergoing surgery with cardiopulmonary bypass for congenital heart disease. Serum was collected before cardiopulmonary bypass, 2 hours after cardiopulmonary bypass, and 18 hours after cardiopulmonary bypass. None. We analyzed the effects of 10% patient sera on the "function, structure, and gene expression" of cultured human dermal and pulmonary microvascular endothelial cells. Changes in barrier "function" were measured using transendothelial electrical resistance. Associations between changes in transendothelial electrical resistance and subject characteristics were analyzed using linear mixed effects model with area under the resistance curve as outcome. Changes in junctional "structure" were assessed by analyzing the organization of the endothelial cell junctional proteins claudin-5 and VE-cadherin using immunofluorescence microscopy. Changes in inflammatory "gene expression" were measured using real-time quantitative reverse transcription-polymerase chain reaction. All serum samples induced a transient, 120-minute increase in transendothelial electrical resistance followed by persistent loss of barrier function. Unexpectedly, sera collected postcardiopulmonary bypass-induced significantly less loss of barrier function in both dermal and pulmonary capillary endothelial cell compared with precardiopulmonary bypass sera. Consistent with the transendothelial electrical resistance results, claudin-5 and vascular endothelial-cadherin junctional staining showed less disruption in cultures treated with postcardiopulmonary bypass sera. Expression of genes commonly associated with inflammation was largely unaffected by patient sera. Contrary to the hypothesis, sera taken from children after cardiopulmonary bypass induces less capillary barrier disruption relative to sera taken from children before cardiopulmonary bypass, and none of the sera induced significant changes in expression of inflammatory genes.

New Insights into the Immune Molecular Regulation of the Pathogenesis of Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome is an inflammatory disease characterized by dysfunction of pulmonary epithelial and capillary endothelial cells, infiltration of alveolar macrophages and neutrophils, cell apoptosis, necroptosis, NETosis, and fibrosis. Inflammatory responses have key effects on every phase of acute respiratory distress syndrome. The severe inflammatory cascades impaired the regulation of vascular endothelial barrier and vascular permeability. Therefore, understanding the relationship between the molecular regulation of immune cells and the pulmonary microenvironment is critical for disease management. This article reviews the current clinical and basic research on the pathogenesis of acute respiratory distress syndrome, including information on the microenvironment, vascular endothelial barrier and immune mechanisms, to offer a strong foundation for developing therapeutic interventions.