The early responses of VEGF and its receptors during acute lung injury: implication of VEGF in alveolar epithelial cell survival

Signaling pathways and potential therapeutic targets in acute respiratory distress syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a common condition associated with critically ill patients, characterized by bilateral chest radiographical opacities with refractory hypoxemia due to noncardiogenic pulmonary edema. Despite significant advances, the mortality of ARDS remains unacceptably high, and there are still no effective targeted pharmacotherapeutic agents. With the outbreak of coronavirus disease 19 worldwide, the mortality of ARDS has increased correspondingly. Comprehending the pathophysiology and the underlying molecular mechanisms of ARDS may thus be essential to developing effective therapeutic strategies and reducing mortality. To facilitate further understanding of its pathogenesis and exploring novel therapeutics, this review provides comprehensive information of ARDS from pathophysiology to molecular mechanisms and presents targeted therapeutics. We first describe the pathogenesis and pathophysiology of ARDS that involve dysregulated inflammation, alveolar-capillary barrier dysfunction, impaired alveolar fluid clearance and oxidative stress. Next, we summarize the molecular mechanisms and signaling pathways related to the above four aspects of ARDS pathophysiology, along with the latest research progress. Finally, we discuss the emerging therapeutic strategies that show exciting promise in ARDS, including several pharmacologic therapies, microRNA-based therapies and mesenchymal stromal cell therapies, highlighting the pathophysiological basis and the influences on signal transduction pathways for their use.

Identification of the key ferroptosis-related genes involved in sepsis progression and experimental validation in vivo

Background: Ferroptosis has a vital role in sepsis, but the mechanism is not known. Understanding the mechanism of ferroptosis during sepsis will aid in developing improved therapeutic strategies.

Methods: We used the Gene Expression Omnibus database and FerrDb database to obtain ferroptosis-related differentially expressed genes (DEGs) between sepsis patients and healthy volunteers (HVs). Analyses of PPI networks, functional enrichment, as well as use of the MCODE algorithm were used to identify key ferroptosis-related DEGs. Expression of key ferroptosis-related DEGs was verified using: GSE57065 and GSE65682 datasets; rats in which ferroptosis was induced with erastin; sepsis-induced acute lung injury (siALI) rats. The effects of acupoint catgut embedding (ACE) on ferroptosis and expression of key ferroptosis-related DEGs in the lungs of siALI rats were also observed. A Cox proportional hazard model was used to verify the effect of key ferroptosis-related DEGs on the survival of sepsis patients. Cytoscape was used to construct ceRNA networks and gene–transcription factor networks.

Results: Between sepsis patients and HVs, we identified 33 ferroptosis-related DEGs. According to analyses of PPI networks and the MCODE algorithm, we obtained four modules, of which the most significant module contained nine ferroptosis-related DEGs. Functional-enrichment analyses showed that four of the nine DEGs were enriched in the MAPK signaling pathway: MAPK14, VEGFA, TGFBR1, and DUSP1. We verified expression of these four genes in GSE57065 and GSE65682 datasets and ferroptosis rats. In addition, expression of these four genes and that of the oxidative-stress indicators GSSG and MDA was upregulated, and glutathione peroxidase-4 (GPX4) expression was downregulated, in siALI rats, but ACE reversed these changes. The Cox proportional hazard model showed that survival of sepsis patients in the high-risk group was shorter than that in the low-risk group. We found that the XIST−hsa-let-7b-5p−TGFBR1/DUSP1 ceRNA network and transcription factor E2F1 may be important regulators of these four DEGs.

Conclusion: Our results suggest that MAPK14, VEGFA, TGFBR1, and DUSP1 may be key regulatory targets of ferroptosis in sepsis, and that ACE pretreatment may be antioxidant treatment for sepsis and alleviate ferroptosis. These findings provide a basis for further ferroptosis-related study in sepsis and provide new targets for its treatment.

Targeting Growth Factor and Cytokine Pathways to Treat Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease of unknown origin that usually results in death from secondary respiratory failure within 2–5 years of diagnosis. Recent studies have identified key roles of cytokine and growth factor pathways in the pathogenesis of IPF. Although there have been numerous clinical trials of drugs investigating their efficacy in the treatment of IPF, only Pirfenidone and Nintedanib have been approved by the FDA. However, they have some major limitations, such as insufficient efficacy, undesired side effects and poor pharmacokinetic properties. To give more insights into the discovery of potential targets for the treatment of IPF, this review provides an overview of cytokines, growth factors and their signaling pathways in IPF, which have important implications for fully exploiting the therapeutic potential of targeting cytokine and growth factor pathways. Advances in the field of cytokine and growth factor pathways will help slow disease progression, prolong life, and improve the quality of life for IPF patients in the future.

Impairment of neutrophil functions and homeostasis in COVID-19 patients: association with disease severity

Background

A dysregulated immune response is emerging as a key feature of critical illness in COVID-19. Neutrophils are key components of early innate immunity that, if not tightly regulated, contribute to uncontrolled systemic inflammation. We sought to decipher the role of neutrophil phenotypes, functions, and homeostasis in COVID-19 disease severity and outcome.

Methods

By using flow cytometry, this longitudinal study compares peripheral whole-blood neutrophils from 90 COVID-19 ICU patients with those of 22 SARS-CoV-2-negative patients hospitalized for severe community-acquired pneumonia (CAP) and 38 healthy controls. We also assessed correlations between these phenotypic and functional indicators and markers of endothelial damage as well as disease severity.

Results

At ICU admission, the circulating neutrophils of the COVID-19 patients showed continuous basal hyperactivation not seen in CAP patients, associated with higher circulating levels of soluble E- and P-selectin, which reflect platelet and endothelial activation. Furthermore, COVID-19 patients had expanded aged-angiogenic and reverse transmigrated neutrophil subsets—both involved in endothelial dysfunction and vascular inflammation. Simultaneously, COVID-19 patients had significantly lower levels of neutrophil oxidative burst in response to bacterial formyl peptide. Moreover patients dying of COVID-19 had significantly higher expansion of aged-angiogenic neutrophil subset and greater impairment of oxidative burst response than survivors.

Conclusions

These data suggest that neutrophil exhaustion may be involved in the pathogenesis of severe COVID-19 and identify angiogenic neutrophils as a potentially harmful subset involved in fatal outcome.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04002-3.

Roles of lung-recruited monocytes and pulmonary Vascular Endothelial Growth Factor (VEGF) in resolving Ventilator-Induced Lung Injury (VILI)

Monocytes and vascular endothelial growth factor (VEGF) have profound effects on tissue injury and repair. In ventilator-induced lung injury (VILI), monocytes, the majority of which are Ly6C+high, and VEGF are known to initiate lung injury. However, their roles in post-VILI lung repair remain unclear. In this study, we used a two-hit mouse model of VILI to identify the phenotypes of monocytes recruited to the lungs during the resolution of VILI and investigated the contributions of monocytes and VEGF to lung repair. We found that the lung-recruited monocytes were predominantly Ly6C+low from day 1 after the insult. Meanwhile, contrary to inflammatory cytokines, pulmonary VEGF decreased upon VILI but subsequently increased significantly on days 7 and 14 after the injury. There was a strong positive correlation between VEGF expression and proliferation of alveolar epithelial cells in lung sections. The expression pattern of VEGF mRNA in lung-recruited monocytes was similar to that of pulmonary VEGF proteins, and the depletion of monocytes significantly suppressed the increase of pulmonary VEGF proteins on days 7 and 14 after VILI. In conclusion, during recovery from VILI, the temporal expression patterns of pulmonary growth factors are different from those of inflammatory cytokines, and the restoration of pulmonary VEGF by monocytes, which are mostly Ly6C+low, is associated with pulmonary epithelial proliferation. Lung-recruited monocytes and pulmonary VEGF may play crucial roles in post-VILI lung repair.

Single-Nucleus RNA-Sequencing Profiling of Mouse Lung. Reduced Dissociation Bias and Improved Rare Cell-Type Detection Compared with Single-Cell RNA Sequencing

Single-cell RNA sequencing (scRNASeq) has advanced our understanding of lung biology, but its utility is limited by the need for fresh samples, loss of cell types by death or inadequate dissociation, and transcriptional stress responses induced during tissue digestion. Single-nucleus RNA sequencing (snRNASeq) has addressed these deficiencies in other tissues, but no protocol exists for lung tissue. We present a snRNASeq protocol and compare its results with those of scRNASeq. Two nuclear suspensions were prepared in lysis buffer on ice while one cell suspension was generated using enzymatic and mechanical dissociation. Cells and nuclei were processed using the 10× Genomics platform, and sequencing data were analyzed by Seurat. A total of 16,110 single-nucleus and 11,934 single-cell transcriptomes were generated. Gene detection rates were equivalent in snRNASeq and scRNASeq (∼1,700 genes and 3,000 unique molecular identifiers per cell) when mapping intronic and exonic reads. In the combined data, 89% of epithelial cells were identified by snRNASeq versus 22.2% of immune cells. snRNASeq transcriptomes are enriched for transcription factors and signaling proteins, with reduction in mitochondrial and stress-response genes. Both techniques improved mesenchymal cell detection over previous studies. Homeostatic signaling relationships among alveolar cell types were defined by receptor-ligand mapping using snRNASeq data, revealing interplay among epithelial, mesenchymal, and capillary endothelial cells. snRNASeq can be applied to archival murine lung samples, improves dissociation bias, eliminates artifactual gene expression, and provides similar gene detection compared with scRNASeq.

Acute and chronic effects of intravitreal bevacizumab on lung biomarkers of angiogenesis in the rat exposed to neonatal intermittent hypoxia

PURPOSE/AIM

Intravitreal bevacizumab (Avastin) is an irreversible vascular endothelial growth factor (VEGF) inhibitor used to treat severe retinopathy of prematurity (ROP) in extremely low gestational age neonates (ELGANs). ELGANs who are at the highest risk for developing severe ROP often experience brief intermittent hypoxia (IH) episodes which may cause oxidative damage. We tested the hypothesis that intravitreal Avastin leaks into the systemic circulation during exposure to IH and has adverse effects on biomarkers of pulmonary microvascular maturation, thus leading to pulmonary hemorrhage and long-term pulmonary sequelae.

METHODS

Neonatal rats at postnatal day (PN) 0 (birth) were exposed to either: 1) hyperoxia (50% O₂) or 2) neonatal IH (50% O₂ with brief episodes of 12% O₂) from PN0 to PN14. Room air (RA) littermates served as controls. At PN14, the time of eye opening in rats, a single dose of Avastin (0.125 mg in 5 µL) was injected into the vitreous cavity of the left eyes. A control group received equivalent volume saline. At PN23 and PN45, blood gases, lung-to-body weight ratios, histology, immunofluorescence, and lung biomarkers of angiogenesis were examined.

RESULTS

At PN23, Avastin increased lung VEGF, nitric oxide derivatives (NOx), and hypoxia-inducible factor (HIF)_1a in the hyperoxia-exposed groups, but decreased soluble VEGFR-1 (sVEGFR-1). At PN45, lungs from animals exposed to neonatal IH and treated with Avastin were severely hemorrhagic with morphologic changes in lung architecture consistent with chronic lung disease. This was associated with higher VEGF and NOx levels, and lower insulin-like growth factor (IGF)-I and sVEGFR-1.

CONCLUSIONS

These findings prove our hypothesis that intravitreal Avastin penetrates the blood-ocular barrier in IH and alters lung biomarkers of angiogenesis. Avastin targeting of VEGF could affect normal lung development which may be exaggerated under pathologic conditions such as IH, ultimately leading to vascular permeability, vessel rupture, and pulmonary hemorrhage.

Vascular endothelial growth factor contributes to lung vascular hyperpermeability in sepsis-associated acute lung injury

Vascular endothelial growth factor (VEGF) is a prime regulator of vascular permeability. Acute lung injury (ALI) is characterized by high-permeability pulmonary edema in addition to refractory hypoxemia and diffuse pulmonary infiltrates. In this study, we examined whether VEGF can be implicated as a pulmonary vascular permeability factor in sepsis-associated ALI. We found that a great increase in lung vascular leak occurred in mice instilled intranasally with lipopolysaccharide (LPS), as assessed by IgM levels in bronchoalveolar lavage fluid. Treatment with the VEGF-neutralizing monoclonal antibody bevacizumab significantly reduced this hyperpermeability response, suggesting active participation of VEGF in non-cardiogenic lung edema associated with LPS-induced ALI. However, this was not solely attributable to excessive levels of intrapulmonary VEGF. Expression levels of VEGF were significantly reduced in lung tissues from mice with both intranasal LPS administration and cecal ligation and puncture (CLP)-induced sepsis, which may stem from decreases in non-endothelial cells-dependent VEGF production in the lungs. In support of this assumption, stimulation with LPS and interferon-γ (IFN-γ) significantly increased VEGF in human pulmonary microvascular endothelial cells (HPMECs) at mRNA and protein levels. Furthermore, a significant rise in plasma VEGF levels was observed in CLP-induced septic mice. The increase in VEGF released from HPMECs after LPS/IFN-γ challenge was completely blocked by either specific inhibitor of mitogen-activated protein kinase (MAPK) subgroups. Taken together, our results indicate that VEGF can contribute to the development of non-cardiogenic lung edema in sepsis-associated ALI due to increased VEGF secretion from pulmonary vascular endothelial cells through multiple MAPK-dependent pathways.

Peripheral Circulating Exosome-Mediated Delivery of miR-155 as a Novel Mechanism for Acute Lung Inflammation

Emerging evidence has revealed that excessive activation of macrophages may result in an adverse lung inflammation involved in sepsis-related acute lung injury (ALI). However, it has never been clearly identified whether peripheral circulating serum exosomes participate in the pathogenesis of sepsis-related ALI. Therefore, the purposes of our study were to investigate the effect of serum exosomes on macrophage activation and elucidate a novel mechanism underlying sepsis-related ALI. Here we found that exosomes were abundant in the peripheral blood from ALI mice and selectively loaded microRNAs (miRNAs), such as miR-155. In vivo experiments revealed that intravenous injection of serum exosomes harvested from ALI mice, but not control mice, increased the number of M1 macrophages in the lung, and it caused lung inflammation in naive mice. In vitro, we demonstrated that serum exosomes from ALI mice delivered miR-155 to macrophages, stimulated nuclear factor κB (NF-κB) activation, and induced the production of tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6. Furthermore, we also showed that serum exosome-derived miR-155 promoted macrophage proliferation and inflammation by targeting SHIP1 and SOCS1, respectively. Collectively, our data suggest the important role of circulating exosomes secreted into peripheral blood as a key mediator of septic lung injury via exosome-shuttling miR-155.

Protective effect of bevacizumab on chemotherapy-related acute exacerbation of interstitial lung disease in patients with advanced non-squamous non-small cell lung cancer

Background

Acute exacerbation of interstitial lung disease (AE-ILD) is the most serious complication in lung cancer patients with pre-existing ILD receiving chemotherapy. The role of vascular endothelial growth factor (VEGF) in pathogenesis of AE-ILD is conflicting. The influence of bevacizumab (Bev), a monoclonal antibody against VEGF, on lung cancer patients with pre-existing ILD remains unclear. We examined the effect of Bev on reducing AE-ILD risk in non-squamous non-small cell lung cancer (NSCLC) patients receiving chemotherapy.

Methods

We analysed incidence of AE-ILD and outcomes of 48 patients with advanced non-squamous NSCLC with ILD who received first-line chemotherapy with (Bev group, n = 17) and without (non-Bev group, n = 31) Bev between July 2011 and July 2016. Gray’s test, which was competing risk analysis during the study period, was performed for both groups.

Results

The most common regimen used for first-line chemotherapy was the combination of carboplatin plus pemetrexed (PEM) in both groups. The incidences of chemotherapy-related AE-ILD 120 days after first-line chemotherapy initiation were significantly lower in the Bev than in the non-Bev groups (0% vs. 22.6%, p = 0.037, Gray’s test). However, there were no differences in development of progressive disease of lung cancer and other events as the competing risk factors of AE-ILD between the two groups. Only patients receiving PEM-containing regimens also showed a significant difference in the incidence of AE-ILD between the two groups (p = 0.044). The overall-cumulative incidence of AE-ILD during the first-line and subsequent chemotherapy was 29.2% (14 of the 48). The median progression-free survival was significantly longer in the Bev than in the non-Bev groups (8.0 vs. 4.3 months, p = 0.026).

Conclusions

The addition of Bev to chemotherapy regimens may reduce the risk of chemotherapy-related AE-ILD in patients with lung cancer.

Electronic supplementary material

The online version of this article (10.1186/s12890-019-0838-2) contains supplementary material, which is available to authorized users.

Salvianolic acid B as an anti-emphysema agent I: In vitro stimulation of lung cell proliferation and migration, and protection against lung cell death, and in vivo lung STAT3 activation and VEGF elevation

Emphysema causes progressive and life-threatening alveolar structural destruction/loss, yet remains irreversible and incurable to date. Impaired vascular endothelial growth factor (VEGF) signaling has been proposed as a new pathogenic mechanism, and if so, VEGF recovery may enable reversal of emphysema. Thus, we hypothesized that salvianolic acid B (Sal-B), a polyphenol in traditional Chinese herbal danshen, is an alveolar structural recovery agent for emphysema by virtue of VEGF stimulation/elevation via activation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3), as stimulating lung cell proliferation and migration, and protecting against lung cell death. Using in vitro human lung microvascular endothelial (HMVEC-L) and alveolar epithelial (A549) cell systems, Sal-B was examined for 1) stimulation of cell proliferation by the MTT and BrdU assays; 2) promotion of cell migration by the scratch wound closure assay; 3) protection against emphysema-like induced cell death by the trypan blue exclusion and flow cytometry assays; and 4) mechanistic involvement of JAK2/STAT3/VEGF in these activities. Sal-B was also spray-dosed to the lungs of healthy rats for two weeks to verify the lung's STAT3 activation and VEGF elevation by western blot, as well as the absence of functional and morphological abnormalities. All the in vitro cell-based activities were concentration-dependent. At 25 μM, Sal-B 1) stimulated cell proliferation by 1.4-2.6-fold; 2) promoted migratory cell wound closure by 1.5-1.7-fold; and 3) protected against cell death induced with H₂O₂ (oxidative stress) and SU5416 (VEGF receptor blockade) by 49-86%. JAK2 and STAT3 inhibitors and VEGF receptor antagonist each opposed these Sal-B's activities by over 65%, suggesting the mechanistic involvement of JAK2/STAT3 activation and VEGF stimulation/elevation. In rats, Sal-B at 0.2 mg/kg enabled 1.9 and 1.5-fold increased STAT3 phosphorylation and VEGF elevation in the lungs, respectively, while causing no functional and morphological abnormalities. Hence, Sal-B was projected to be a new class of anti-emphysema agent capable of reversing alveolar structural destruction/loss via JAK2/STAT3/VEGF-dependent stimulation of lung cell proliferation and migration, and inhibition of induced lung cell death.

Physiological Role of Vascular Endothelial Growth Factors as Homeostatic Regulators

The vascular endothelial growth factor (VEGF) family of proteins are key regulators of physiological systems. Originally linked with endothelial function, they have since become understood to be principal regulators of multiple tissues, both through their actions on vascular cells, but also through direct actions on other tissue types, including epithelial cells, neurons, and the immune system. The complexity of the five members of the gene family in terms of their different splice isoforms, differential translation, and specific localizations have enabled tissues to use these potent signaling molecules to control how they function to maintain their environment. This homeostatic function of VEGFs has been less intensely studied than their involvement in disease processes, development, and reproduction, but they still play a substantial and significant role in healthy control of blood volume and pressure, interstitial volume and drainage, renal and lung function, immunity, and signal processing in the peripheral and central nervous system. The widespread expression of VEGFs in healthy adult tissues, and the disturbances seen when VEGF signaling is inhibited support this view of the proteins as endogenous regulators of normal physiological function. This review summarizes the evidence and recent breakthroughs in understanding of the physiology that is regulated by VEGF, with emphasis on the role they play in maintaining homeostasis. © 2017 American Physiological Society. Compr Physiol 8:955-979, 2018.

VEGF (Vascular Endothelial Growth Factor) and Fibrotic Lung Disease

Interstitial lung disease (ILD) encompasses a group of heterogeneous diseases characterised by varying degrees of aberrant inflammation and fibrosis of the lung parenchyma. This may occur in isolation, such as in idiopathic pulmonary fibrosis (IPF) or as part of a wider disease process affecting multiple organs, such as in systemic sclerosis. Anti-Vascular Endothelial Growth Factor (anti-VEGF) therapy is one component of an existing broad-spectrum therapeutic option in IPF (nintedanib) and may become part of the emerging therapeutic strategy for other ILDs in the future. This article describes our current understanding of VEGF biology in normal lung homeostasis and how changes in its bioavailability may contribute the pathogenesis of ILD. The complexity of VEGF biology is particularly highlighted with an emphasis on the potential non-vascular, non-angiogenic roles for VEGF in the lung, in both health and disease.

Antifibrotic role of vascular endothelial growth factor in pulmonary fibrosis

The chronic progressive decline in lung function observed in idiopathic pulmonary fibrosis (IPF) appears to result from persistent nonresolving injury to the epithelium, impaired restitution of the epithelial barrier in the lung, and enhanced fibroblast activation. Thus, understanding these key mechanisms and pathways modulating both is essential to greater understanding of IPF pathogenesis. We examined the association of VEGF with the IPF disease state and preclinical models in vivo and in vitro. Tissue and circulating levels of VEGF were significantly reduced in patients with IPF, particularly in those with a rapidly progressive phenotype, compared with healthy controls. Lung-specific overexpression of VEGF significantly protected mice following intratracheal bleomycin challenge, with a decrease in fibrosis and bleomycin-induced cell death observed in the VEGF transgenic mice. In vitro, apoptotic endothelial cell–derived mediators enhanced epithelial cell injury and reduced epithelial wound closure. This process was rescued by VEGF pretreatment of the endothelial cells via a mechanism involving thrombospondin-1 (TSP1). Taken together, these data indicate beneficial roles for VEGF during lung fibrosis via modulating epithelial homeostasis through a previously unrecognized mechanism involving the endothelium.

Elevated VEGF is associated with less severe disease in IPF patients, and VEGF overexpression ameliorates bleomycin-induced lung fibrosis in a murine model.

Poly-lactic acid nanoparticles (PLA-NP) promote physiological modifications in lung epithelial cells and are internalized by clathrin-coated pits and lipid rafts

Background

Poly-lactic acid nanoparticles (PLA-NP) are a type of polymeric NP, frequently used as nanomedicines, which have advantages over metallic NP such as the ability to maintain therapeutic drug levels for sustained periods of time. Despite PLA-NP being considered biocompatible, data concerning alterations in cellular physiology are scarce.

Methods

We conducted an extensive evaluation of PLA-NP biocompatibility in human lung epithelial A549 cells using high throughput screening and more complex methodologies. These included measurements of cytotoxicity, cell viability, immunomodulatory potential, and effects upon the cells’ proteome. We used non- and green-fluorescent PLA-NP with 63 and 66 nm diameters, respectively. Cells were exposed with concentrations of 2, 20, 100 and 200 µg/mL, for 24, 48 and 72 h, in most experiments. Moreover, possible endocytic mechanisms of internalization of PLA-NP were investigated, such as those involving caveolae, lipid rafts, macropinocytosis and clathrin-coated pits.

Results

Cell viability and proliferation were not altered in response to PLA-NP. Multiplex analysis of secreted mediators revealed a low-level reduction of IL-12p70 and vascular epidermal growth factor (VEGF) in response to PLA-NP, while all other mediators assessed were unaffected. However, changes to the cells’ proteome were observed in response to PLA-NP, and, additionally, the cellular stress marker miR155 was found to reduce. In dual exposures of staurosporine (STS) with PLA-NP, PLA-NP enhanced susceptibility to STS-induced cell death. Finally, PLA-NP were rapidly internalized in association with clathrin-coated pits, and, to a lesser extent, with lipid rafts.

Conclusions

These data demonstrate that PLA-NP are internalized and, in general, tolerated by A549 cells, with no cytotoxicity and no secretion of pro-inflammatory mediators. However, PLA-NP exposure may induce modification of biological functions of A549 cells, which should be considered when designing drug delivery systems. Moreover, the pathways of PLA-NP internalization we detected could contribute to the improvement of selective uptake strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-016-0238-1) contains supplementary material, which is available to authorized users.

Anti-Vascular Endothelial Growth Factor Antibody Suppresses ERK and NF-κB Activation in Ischemia-Reperfusion Lung Injury

Ischemia-reperfusion (IR)-induced acute lung injury (ALI) is implicated in several clinical conditions like lung transplantation, acute pulmonary embolism after thrombolytic therapy, re-expansion of collapsed lung from pneumothorax or pleural effusion, cardiopulmonary bypass and etc. Because mortality remains high despite advanced medical care, prevention and treatment are important clinical issues for IR-induced ALI. Vascular endothelial growth factor (VEGF) has a controversial role in ALI. We therefore conducted this study to determine the effects of anti-VEGF antibody in IR-induced ALI. In the current study, the IR-induced ALI was conducted in a rat model of isolated-perfused lung in situ in the chest. The animals were divided into the control, control + preconditioning anti-VEGF antibody (bevacizumab, 5mg/kg), IR, IR + preconditioning anti-VEGF antibody (1mg/kg), IR+ preconditioning anti-VEGF antibody (5mg/kg) and IR+ post-IR anti-VEGF antibody (5mg/kg) group. There were eight adult male Sprague-Dawley rats in each group. The IR caused significant pulmonary micro-vascular hyper-permeability, pulmonary edema, neutrophilic infiltration in lung tissues, increased tumor necrosis factor-α, and total protein concentrations in bronchoalveolar lavage fluid. VEGF and extracellular signal-regulated kinase (ERK) were increased in IR-induced ALI. Administration of preconditioning anti-VEGF antibody significantly suppressed the VEGF and ERK expressions and attenuated the IR-induced lung injury. This study demonstrates the important role of VEGF in early IR-induced ALI. The beneficial effects of preconditioning anti-VEGF antibody in IR-induced ALI include the attenuation of lung injury, pro-inflammatory cytokines, and neutrophilic infiltration into the lung tissues.

Dysregulation of Vascular Endothelial Progenitor Cells Lung-Homing in Subjects with COPD

Chronic obstructive pulmonary disease (COPD) is characterized by fixed airflow limitation and progressive decline of lung function and punctuated by occasional exacerbations. The disease pathogenesis may involve activation of the bone marrow stimulating mobilization and lung-homing of progenitor cells. We investigated the hypothesis that lower circulating numbers of vascular endothelial progenitor cells (VEPCs) are a consequence of increased lung-sequestration in COPD. Nonatopic, current or ex-smokers with diagnosed COPD and nonatopic, nonsmoking normal controls were enrolled. Blood and induced sputum extracted primitive hemopoietic progenitors (HPCs) and VEPC were enumerated by flow cytometry. Migration and adhesive responses to fibronectin were assessed. In sputum, VEPC numbers were significantly greater in COPD compared to normal controls. In blood, VEPCs were significantly lower in COPD versus normal controls. There were no differences in HPC levels between the two groups in either compartment. Functionally, there was a greater migrational responsiveness of progenitors from COPD subjects to stromal cell-derived factor-1alpha (SDF-1α) compared to normal controls. This was associated with greater numbers of CXCR4⁺ progenitors in sputum from COPD. Increased migrational responsiveness of progenitor cells may promote lung-homing of VEPC in COPD which may disrupt maintenance and repair of the airways and contribute to COPD disease pathogenesis.

The effect of insulin-loaded linear poly(ethylene glycol)-brush-like poly(l-lysine) block copolymer on renal ischemia/reperfusion-induced lung injury through downregulating hypoxia-inducible factor

The aim of this study was to observe the therapeutic effect of insulin-loaded linear poly(ethylene glycol)-brush-like poly(l-lysine) block copolymer poly(ethylene glycol)-b-(poly(ethylenediamine l-glutamate)-g-poly(l-lysine)) (PEG-b-(PELG-g-PLL) on renal ischemia/reperfusion-induced lung injury through downregulating hypoxia-inducible factor (HIF) as compared to free insulin. Sprague Dawley rats were pretreated with 30 U/kg insulin or insulin/PEG-b-(PELG-g-PLL) complex, and then subjected to 45 minutes of ischemia and 24 hours of reperfusion. The blood and lungs were collected, the level of serum creatinine and blood urea nitrogen were measured, and the dry/wet lung ratios, the activity of superoxide dismutase and myeloperoxidase, the content of methane dicarboxylic aldehyde and tumor necrosis factor-α, and the expression of HIF-1α and vascular endothelial growth factor (VEGF) were measured in pulmonary tissues. Both insulin and insulin/PEG-b-(PELG-g-PLL) preconditioning improved the recovery of renal function, reduced pulmonary oxidative stress injury, restrained inflammatory damage, and downregulated the expression of HIF-1α and VEGF as compared to ischemia/reperfusion group, while insulin/PEG-b-(PELG-g-PLL) significantly improved this effect.

Azithromycin attenuates cigarette smoke extract-induced oxidative stress injury in human alveolar epithelial cells

Cigarette smoking has been verified to be one of the most important etiological factors causing the development of bronchogenic carcinoma and chronic obstructive pulmonary disease. Azithromycin (AZM) has been demonstrated to have antioxidant capacity. In the present study, whether AZM is able to attenuate cigarette smoke extract (CSE)-induced A549 cell oxidative stress injury was investigated. Cells were incubated with CSE in the presence or absence of AZM. Cell viability was measured using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The expression of vascular endothelial growth factor (VEGF) was analyzed using western blotting and ELISA. The expression of epithelial cell structural proteins, zona occludens (ZO)-1 and occludin was determined using western blotting and immunofluorescence staining. Reactive oxygen species (ROS) production was examined by flow cytometry and fluorescence staining. The results demonstrated that the exposure of A549 cells to CSE decreased cell viability in a dose- and time-dependent manner. AZM significantly attenuated the CSE-induced decreases in the expression of VEGF and epithelial cell structural proteins, including ZO-1 and occludin. CSE also stimulated ROS production in the A549 cell, while AZM significantly reversed the effects of CSE. In addition, the inhibition of ROS by N-acetyl-L-cysteine had similar effects as AZM on the expression of VEGF and epithelial cell structural proteins and also enhanced cell proliferation. In conclusion, AZM attenuated CSE-induced oxidative stress injury in A549 cells and may be a promising therapeutic agent for smoking-associated pulmonary diseases.

Salidroside exerts angiogenic and cytoprotective effects on human bone marrow-derived endothelial progenitor cells via Akt/mTOR/p70S6K and MAPK signalling pathways

BACKGROUND AND PURPOSE

With the increase of age, increased susceptibility to apoptosis and senescence may contribute to proliferative and functional impairment of endothelial progenitor cells (EPCs). The aim of this study was to investigate whether salidroside (SAL) can induce angiogenic differentiation and inhibit oxidative stress-induced apoptosis in bone marrow-derived EPCs (BM-EPCs), and if so, through what mechanism.

EXPERIMENTAL APPROACH

BM-EPCs were isolated and treated with different concentrations of SAL for up to 4 days. Cell proliferation, migration and tube formation ability were detected by DNA content quantification, transwell assay and Matrigel-based angiogenesis assay. Gene and protein expression were assessed by qRT-PCR and Western blot respectively.

KEY RESULTS

Treatment with SAL promoted cellular proliferation and angiogenic differentiation of BM-EPCs, and increased VEGF and NO secretion, which in turn mediated the enhanced angiogenic differentiation of BM-EPCs. Furthermore, SAL significantly attenuated hydrogen peroxide (H₂O₂)-induced cell apoptosis, reduced the intracellular level of reactive oxygen species and restored the mitochondrial membrane potential of BM-EPCs. Moreover, SAL stimulated the phosphorylation of Akt, mammalian target of rapamycin and p70 S6 kinase, as well as ERK1/2, which is associated with cell migration and capillary tube formation. Additionally, SAL reversed the phosphorylation of JNK and p38 MAPK induced by H₂O₂ and suppressed the changes in the Bax/Bcl-xL ratio observed after stimulation with H₂O₂.

CONCLUSIONS AND IMPLICATIONS

These findings identify novel mechanisms that regulate EPC function and suggest that SAL has therapeutic potential as a new agent to enhance vasculogenesis as well as protect against oxidative endothelial injury.

Serum levels of vascular endothelial growth factor in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a third leading cause of death.

METHODS

In this case control study, we prepared 5 cc bloods from the antecubital vein of 100 COPD patients and 40 healthy individuals as control group. Vascular endothelial growth factor (VEGF) expression protein level was measured by ELISA in both groups.

RESULTS

We found that concentration of VEGF in blood serum of patients with COPD (189.9±16pg/ml) was significantly higher than the control group (16.4±3.48pg/ml) (p<0.001). While VEGF serum level in emphysematous patients wasn't significantly different with control group (p=0.07). Furthermore VEGF serum level in COPD patients was proportionally increased with severity of disease (p<0.001). Besides all COPD patients, regardless of their smoking status, were experienced significantly higher levels of VEGF than healthy ones (p=0.001; z=4.3).

CONCLUSION

Our results suggest VEGF serum concentration as the sensitive index for severity and activity of COPD and its prognosis.

Vascular endothelial growth factor in acute lung injury and acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is the most severe form of lung injury, characterised by alveolar oedema and vascular permeability, in part due to disruption of the alveolar capillary membrane integrity. Vascular endothelial growth factor (VEGF) was originally identified as a vascular permeability factor and has been implicated in the pathogenesis of acute lung injury/ARDS. This review describes our current knowledge of VEGF biology and summarises the literature investigating the potential role VEGF may play in normal lung maintenance and in the development of lung injury.

Dexamethasone attenuates VEGF expression and inflammation but not barrier dysfunction in a murine model of ventilator-induced lung injury

Background

Ventilator–induced lung injury (VILI) is characterized by vascular leakage and inflammatory responses eventually leading to pulmonary dysfunction. Vascular endothelial growth factor (VEGF) has been proposed to be involved in the pathogenesis of VILI. This study examines the inhibitory effect of dexamethasone on VEGF expression, inflammation and alveolar–capillary barrier dysfunction in an established murine model of VILI.

Methods

Healthy male C57Bl/6 mice were anesthetized, tracheotomized and mechanically ventilated for 5 hours with an inspiratory pressure of 10 cmH₂O (“lower” tidal volumes of ∼7.5 ml/kg; LV_T) or 18 cmH₂O (“higher” tidal volumes of ∼15 ml/kg; HV_T). Dexamethasone was intravenously administered at the initiation of HV_T–ventilation. Non–ventilated mice served as controls. Study endpoints included VEGF and inflammatory mediator expression in lung tissue, neutrophil and protein levels in bronchoalveolar lavage fluid, PaO₂ to FiO₂ ratios and lung wet to dry ratios.

Results

Particularly HV_T–ventilation led to alveolar–capillary barrier dysfunction as reflected by reduced PaO₂ to FiO₂ ratios, elevated alveolar protein levels and increased lung wet to dry ratios. Moreover, VILI was associated with enhanced VEGF production, inflammatory mediator expression and neutrophil infiltration. Dexamethasone treatment inhibited VEGF and pro–inflammatory response in lungs of HV_T–ventilated mice, without improving alveolar–capillary permeability, gas exchange and pulmonary edema formation.

Conclusions

Dexamethasone treatment completely abolishes ventilator–induced VEGF expression and inflammation. However, dexamethasone does not protect against alveolar–capillary barrier dysfunction in an established murine model of VILI.

XB130 mediates cancer cell proliferation and survival through multiple signaling events downstream of Akt

XB130, a novel adaptor protein, mediates RET/PTC chromosome rearrangement-related thyroid cancer cell proliferation and survival through phosphatidyl-inositol-3-kinase (PI3K)/Akt pathway. Recently, XB130 was found in different cancer cells in the absence of RET/PTC. To determine whether RET/PTC is required of XB130-related cancer cell proliferation and survival, WRO thyroid cancer cells (with RET/PTC mutation) and A549 lung cancer cells (without RET/PTC) were treated with XB130 siRNA, and multiple Akt down-stream signals were examined. Knocking-down of XB130 inhibited G₁-S phase progression, and induced spontaneous apoptosis and enhanced intrinsic and extrinsic apoptotic stimulus-induced cell death. Knocking-down of XB130 reduced phosphorylation of p21Cip1/WAF1, p27Kip1, FOXO3a and GSK3β, increased p21Cip1/WAF1protein levels and cleavages of caspase-8 and-9. However, the phosphorylation of FOXO1 and the protein levels of p53 were not affected by XB130 siRNA. We also found XB130 can be phosphorylated by multiple protein tyrosine kinases. These results indicate that XB130 is a substrate of multiple protein tyrosine kinases, and it can regulate cell proliferation and survival through modulating selected down-stream signals of PI3K/Akt pathway. XB130 could be involved in growth and survival of different cancer cells.

Immune responses in the lungs of patients with tuberculous pleural effusion without pulmonary tuberculosis

Background

Tuberculous pleural effusion (TPE) is one of the most common forms of extrapulmonary tuberculosis. Because most studies of TPE focused on the pleural space, little information regarding lung parenchyma is available. We therefore aimed to investigate immune responses in the lung parenchyma of TPE patients without pulmonary tuberculosis.

Methods

Patients with any evidence of pulmonary tuberculosis, either from radiologic or bacteriologic evaluation, were excluded. Bronchoalveolar lavage fluid (BALF) was collected from 10 newly diagnosed, untreated, HIV-negative TPE patients and 10 healthy controls. We analyzed T-lymphocyte subpopulations and measured 10 cytokines in BALF. Cytokine levels in BALF were standardised using urea.

Results

The concentrations of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), and the CD4+/CD8+ ratio of T-lymphocytes were significantly higher in TPE patients without pulmonary tuberculosis than in the controls. Of the cytokines measured in BALF, VEGF showed the highest concentration. No difference was observed in T-helper type 2 cytokines between the 2 groups.

Conclusion

There were significant immune responses and increases in IFN-γ, TNF-α, and VEGF in the lung parenchyma of TPE patients without pulmonary tuberculosis. This result suggests that TPE may induce a significant immune response in lung parenchyma.

XB130 as an independent prognostic factor in human esophageal squamous cell carcinoma

BACKGROUND

Adaptor proteins, with multimodular structures, can participate in the regulation of various cellular functions. A novel adaptor protein XB130 has been implicated as a substrate and regulator of tyrosine kinase-mediated signaling and in controlling cell proliferation and apoptosis in thyroid and lung cancer cells. However, its expression and role in gastrointestinal cancer have not been investigated. We sought to determine the role of XB130 in cell cycle progression of esophageal squamous cell carcinoma (ESCC) cells and to examine its expression and effects on the prognosis of patients with ESCC.

METHODS

Expression of XB130 in human ESCC cell lines was analyzed by Western blot testing and immunofluorescent staining. Knockdown experiments with XB130 small interfering RNA (siRNA) were conducted, and the effect on cell cycle progression was analyzed. Immunohistochemistry of XB130 for 52 primary tumor samples obtained from patients with ESCC undergoing esophagectomy was performed.

RESULTS

XB130 was highly expressed in TE2, TE5, and TE9 cells. In these cells, knockdown of XB130 with siRNA inhibited G1-S phase progression and increased the expression of p21, the cyclin-dependent kinase inhibitor. Immunohistochemistry showed that 71.2% of the patients expressed XB130 in the nuclei and/or cytoplasm of the ESCC cells. Further, nuclear expression of XB130 was an independent prognostic factor of postoperative survival.

CONCLUSIONS

These observations suggest that the expression of XB130 in ESCC cells may affect cell cycle progression and impact prognosis of patients with ESCC. A deeper understanding of XB130 as a mediator and/or biomarker in ESCC is needed.

Bioinformatics insights into acute lung injury/acute respiratory distress syndrome

Bioinformatics is the application of omics science, information technology, mathematics and statistics in the field of biomarker detection. Clinical bioinformatics can be applied for identification and validation of new biomarkers to improve current methods of monitoring disease activity and identify new therapeutic targets. Acute lung injurt (ALI)/Acute respiratory distress syndrome (ARDS) affects a large number of patients with a poor prognosis. The present review mainly focused on the progress in understanding disease heterogeneity through the use of evolving biological, genomic, and genetic approaches and the role of clinical bioinformatics in the pathogenesis and treatment of ALI/ARDS. The remarkable advances in clinical bioinformatics can be a new way for understanding disease pathogenesis, diagnosis and treatment.

Claudin 1 mediates TNFα-induced gene expression and cell migration in human lung carcinoma cells

Epithelial-mesenchymal transition (EMT) is an important mechanism in carcinogenesis. To determine the mechanisms that are involved in the regulation of EMT, it is crucial to develop new biomarkers and therapeutic targets towards cancers. In this study, when TGFβ1 and TNFα were used to induce EMT in human lung carcinoma A549 cells, we found an increase in an epithelial cell tight junction marker, Claudin 1. We further identified that it was the TNFα and not the TGFβ1 that induced the fibroblast-like morphology changes. TNFα also caused the increase in Claudin-1 gene expression and protein levels in Triton X-100 soluble cytoplasm fraction. Down-regulation of Claudin-1, using small interfering RNA (siRNA), inhibited 75% of TNFα-induced gene expression changes. Claudin-1 siRNA effectively blocked TNFα-induced molecular functional networks related to inflammation and cell movement. Claudin-1 siRNA was able to significantly reduce TNF-enhanced cell migration and fibroblast-like morphology. Furthermore, over expression of Claudin 1 with a Claudin 1-pcDNA3.1/V5-His vector enhanced cell migration. In conclusion, these observations indicate that Claudin 1 acts as a critical signal mediator in TNFα-induced gene expression and cell migration in human lung cancer cells. Further analyses of these cellular processes may be helpful in developing novel therapeutic strategies.

Leukemia inhibitory factor signaling is required for lung protection during pneumonia

Lung infections represent a tremendous disease burden and a leading cause of acute lung injury. STAT3 signaling is essential for controlling lung injury during pneumonia. We previously identified LIF as a prominent STAT3-activating cytokine expressed in the airspaces of pneumonic lungs, but its physiological significance in this setting has never been explored. To do so, Escherichia coli was intratracheally instilled into C57BL/6 mice in the presence of neutralizing anti-LIF IgG or control IgG. Anti-LIF completely eliminated lung LIF detection and markedly exacerbated lung injury compared with control mice as evidenced by airspace albumin content, lung liquid accumulation, and histological analysis. Although lung bacteriology was equivalent between groups, bacteremia was more prevalent with anti-LIF treatment, suggestive of compromised barrier function rather than impaired antibacterial defense as the cause of dissemination. Inflammatory cytokine expression was also exaggerated in anti-LIF-treated lungs, albeit after injury had ensued. Interestingly, alveolar neutrophil recruitment was modestly but significantly reduced compared with control mice despite elevated cytokine levels, indicating that inflammatory injury was not a consequence of excessive neutrophilic alveolitis. Lastly, the lung transcriptome was dramatically remodeled during pneumonia, but far more so following LIF neutralization, with gene changes implicating cell death and epithelial homeostasis among other processes relevant to tissue injury. From these findings, we conclude that endogenous LIF facilitates tissue protection during pneumonia. The LIF-STAT3 axis is identified in this study as a critical determinant of lung injury with clinical implications for pneumonia patients.

Induction of cellular antioxidant defense by amifostine improves ventilator-induced lung injury

OBJECTIVES

To test the hypothesis that preconditioning animals with amifostine improves ventilator-induced lung injury via induction of antioxidant defense enzymes. Mechanical ventilation at high tidal volume induces reactive oxygen species production and oxidative stress in the lung, which plays a major role in the pathogenesis of ventilator-induced lung injury. Amifostine attenuates oxidative stress and improves lipopolysaccharide-induced lung injury by acting as a direct scavenger of reactive oxygen and nitrogen species. This study tested effects of chronic amifostine administration on parameters of oxidative stress, lung barrier function, and inflammation associated with ventilator-induced lung injury.

DESIGN

Randomized and controlled laboratory investigation in mice and cell culture.

SETTING

University laboratory.

SUBJECTS

C57BL/6J mice.

INTERVENTIONS

Mice received once-daily dosing with amifostine (10-100 mg/kg, intraperitoneal injection) 3 days consecutively before high tidal volume ventilation (30 mL/kg, 4 hrs) at day 4. Pulmonary endothelial cell cultures were exposed to pathologic cyclic stretching (18% equibiaxial stretch) and thrombin in a previously verified two-hit model of in vitro ventilator-induced lung injury.

MEASUREMENTS AND MAIN RESULTS

Three-day amifostine preconditioning before high tidal volume attenuated high tidal volume-induced protein and cell accumulation in the alveolar space judged by bronchoalveolar lavage fluid analysis, decreased Evans Blue dye extravasation into the lung parenchyma, decreased biochemical parameters of high tidal volume-induced tissue oxidative stress, and inhibited high tidal volume-induced activation of redox-sensitive stress kinases and nuclear factor-kappa B inflammatory cascade. These protective effects of amifostine were associated with increased superoxide dismutase 2 expression and increased superoxide dismutase and catalase enzymatic activities in the animal and endothelial cell culture models of ventilator-induced lung injury.

CONCLUSIONS

Amifostine preconditioning activates lung tissue antioxidant cell defense mechanisms and may be a promising strategy for alleviation of ventilator-induced lung injury in critically ill patients subjected to extended mechanical ventilation.

Acute lung injury: how macrophages orchestrate resolution of inflammation and tissue repair

Lung macrophages are long living cells with broad differentiation potential, which reside in the lung interstitium and alveoli or are organ-recruited upon inflammatory stimuli. A role of resident and recruited macrophages in initiating and maintaining pulmonary inflammation in lung infection or injury has been convincingly demonstrated. More recent reports suggest that lung macrophages are main orchestrators of termination and resolution of inflammation. They are also initiators of parenchymal repair processes that are essential for return to homeostasis with normal gas exchange. In this review we will discuss cellular cross-talk mechanisms and molecular pathways of macrophage plasticity which define their role in inflammation resolution and in initiation of lung barrier repair following lung injury.

Interleukin-6 mediates pulmonary vascular permeability in a two-hit model of ventilator-associated lung injury

To test the hypothesis that interleukin-6 (IL-6) contributes to the development of ventilator-associated lung injury (VALI), IL-6-deficient (IL6(-/-)) and wild-type control (WT) mice received intratracheal hydrochloric acid followed by randomization to mechanical ventilation (MV + IT HCl) or spontaneous ventilation (IT HCl). After 4 hours, injury was assessed by estimation of lung lavage protein concentration and total and differential cell counts, wet/dry lung weight ratio, pulmonary cell death, histologic inflammation score (LIS), and parenchymal myeloperoxidase (MPO) concentration. Vascular endothelial growth factor (VEGF) concentration was measured in lung lavage and homogenate, as IL-6 and stretch both regulate expression of this potent mediator of permeability. MV-induced increases in alveolar barrier dysfunction and lavage VEGF were attenuated in IL6(-/-) mice as compared with WT controls, whereas tissue VEGF concentration increased. The effects of IL-6 deletion on alveolar permeability and VEGF concentration were inflammation independent, as parenchymal MPO concentration, LIS, and lavage total and differential cell counts did not differ between WT and IL6(-/-) mice following MV + IT HCl. These data support a role for IL-6 in promoting VALI in this two-hit model. Strategies to interfere with IL-6 expression or signaling may represent important therapeutic targets to limit the injurious effects of MV in inflamed lungs.

Hydroxyethyl starch reduces high stretch ventilation-augmented lung injury via vascular endothelial growth factor

Disruption of epithelial and endothelial barriers found in patients with acute lung injury often results in the need for the support of mechanical ventilation. High tidal volume (V(T)) mechanical ventilation can increase lung damage through lung inflammation, but the mechanisms are unclear. We hypothesized that a colloid supply with hydroxyethyl starch would decrease neutrophil infiltration, lung edema, and vascular endothelial growth factor (VEGF) production in mice exposed to high V(T) mechanical ventilation. Male C57BL/6 mice, weighing 20 g to 25 g, were exposed to high V(T) (30 mL/kg) mechanical ventilation with room air for 1 h to 5 h and infused with 15 mL/kg/h normal saline or hydroxyethyl starch intravenously at the beginning and every 30 min during ventilation. Evans blue dye, lung wet-to-dry weight ratio, histopathologic grading of lung tissue, myeloperoxidase, and inflammatory cytokine were measured to establish the extent of lung injury. Knockdown of VEGF by short interfering RNA (siRNA) was used to explore the role of VEGF. High V(T) ventilation induced the increases of microvascular permeability, neutrophil influx, expressions of VEGF mRNA and VEGF, production of VEGF protein, positive staining of VEGF in epithelium, and apoptotic epithelial cell death. Lung injury induced by high V(T) ventilation was attenuated with the supply of hydroxyethyl starch and pharmacologic inhibition of VEGF expression by siRNA. We conclude that hydroxyethyl starch reduces high V(T) mechanical ventilation-induced lung injury and neutrophil infiltration through an inhibition of VEGF expression.

The potential of nanoscale combinations of self-assembling peptides and amino acids of the Src tyrosine kinase inhibitor in acute lung injury therapy

Many newly discovered therapeutic agents require a delivery platform in order to translate them into clinical applications. For this purpose, a nanoscale formulation strategy was developed for the Src tyrosine kinase inhibitor PP2. The formulation utilizes the combination of the self-assembling peptides (EAK16-II) and amino acids to minimize the use of the toxic organic solvent DMSO; hence, the biocompatibility of the PP2 nanoformulations was significantly improved. They were found to be non-hemolytic and safe for intravenous and intratracheal administration; the formulations did not alter PP2 activity in Src inhibition on cultured cells. The PP2 nanoformulation was further evaluated on a lipopolysaccharide (LPS)-induced acute lung injury mouse model. Results revealed that the pretreatment of PP2 nanoformulation could decrease the inflammatory cell infiltration and the pro-inflammatory cytokine TNF-α production in the bronchoalveolar lavage fluid after LPS stimulation. The promising therapeutic efficacy and the formulation strategy developed in this work may help further translate PP2 and other hydrophobic therapeutic agents into clinical applications.

XB130, a novel adaptor protein, promotes thyroid tumor growth

Adaptor proteins with multimodular structures can participate in the regulation of various cellular functions. We have cloned a novel adaptor protein, XB130, which binds the p85α subunit of phosphatidyl inositol 3-kinase and subsequently mediates signaling through RET/PTC in TPC-1 thyroid cancer cells. In the present study, we sought to determine the role of XB130 in the tumorigenesis in vivo and in related molecular mechanisms. In WRO thyroid cancer cells, knockdown of XB130 using small interfering RNA inhibited G(1)-S phase progression, induced spontaneous apoptosis, and enhanced intrinsic and extrinsic apoptotic stimulus-induced cell death. Growth of tumors in nude mice formed from XB130 shRNA stably transfected WRO cells were significantly reduced, with decreased cell proliferation and increased apoptosis. Microarray analysis identified 246 genes significantly changed in XB130 shRNA transfected cells. Among them, 57 genes are related to cell proliferation or survival, including many transcription regulators. Ingenuity Pathway Analysis showed that the top-ranked disease related to XB130 is cancer, and the top molecular and cellular functions are cellular growth and proliferation and cell cycle. A human thyroid tissue microarray study identified expression of XB130 in normal thyroid tissue as well as in human thyroid carcinomas. These observations suggest that the expression of XB130 in these cancer cells may affect cell proliferation and survival by controlling the expression of multiple genes, especially transcription regulators.

Long pentraxin PTX3 deficiency worsens LPS-induced acute lung injury

OBJECTIVE

Long pentraxin PTX3 is an inflammatory mediator and a component of the humoral arm of innate immunity. PTX3 expression is increased in animals with acute lung injury (ALI) and in patients with sepsis or acute respiratory distress syndrome and is considered to be a potential biomarker for these diseases. However, the role of PTX3 in the pathogenesis of ALI is not fully understood. We hypothesized that PTX3, as an important immune modulator, may determine the severity of ALI.

METHODS

Lipopolysaccharide (LPS) was intra-tracheally administrated to PTX3 knock-out (PTX3-KO) and wild-type (WT) mice. Lung injury, neutrophil infiltration, cell death, fibrin deposition, and tissue factor expression in the lung were determined. Local and systemic inflammatory responses were assessed by measuring cytokines in the lung and plasma.

RESULTS

LPS instillation induced ALI in both PTX3-KO and WT mice. Interestingly, PTX3 deficiency significantly increased the magnitude/extent of lung injury compared to that in WT mice. The severe lung injury was accompanied by elevated neutrophil infiltration, cell death, and fibrin deposition in the lung. PTX3 deficiency also enhanced LPS-induced tissue factor expression/activation in the lung and increased tumor necrosis factor-alpha and monocyte chemoattractant protein-1 levels in the plasma.

CONCLUSION

Our data suggest that the endogenously expressed PTX3 plays a protective role in the pathogenesis of ALI and that a lack of PTX3 may enhance neutrophil recruitment, cell death, activation of coagulation cascades, and inflammatory responses in the lung.

The protein kinase C cascade regulates recruitment of matrix metalloprotease 9 to podosomes and its release and activation

Podosomes are transient cell surface structures essential for degradation of extracellular matrix during cell invasion. Protein kinase C (PKC) is involved in the regulation of podosome formation; however, the roles of individual PKC isoforms in podosome formation and proteolytic function are largely unknown. Recently, we reported that PDBu, a PKC activator, induced podosome formation in normal human bronchial epithelial cells. Here, we demonstrate that phorbol-12,13-dibutyrate (PDBu)-induced podosome formation is mainly mediated through redistribution of conventional PKCs, especially PKCα, from the cytosol to the podosomes. Interestingly, although blocking atypical PKCζ did not affect PDBu-induced podosome formation, it significantly reduced matrix degradation at podosomes. Inhibition of PKCζ reduced recruitment of matrix metalloprotease 9 (MMP-9) to podosomes and its release and activation. Downregulation of MMP-9 by small interfering RNA (siRNA) or neutralization antibody also significantly reduced matrix degradation. The regulatory effects of PKCζ on matrix degradation and recruitment of MMP-9 to podosomes were PKCζ kinase activity dependent. PDBu-induced recruitment of PKCζ and MMP-9 to podosomes was blocked by inhibition of novel PKC with rottlerin or PKCδ siRNA. Our data suggest that multiple PKC isozymes form a signaling cascade that controls podosome formation and dynamics and MMP-9 recruitment, release, and activation in a coordinated fashion.

Bone marrow-derived mononuclear cell therapy in experimental pulmonary and extrapulmonary acute lung injury

OBJECTIVE

To hypothesize that bone marrow-derived mononuclear cell (BMDMC) therapy might act differently on lung and distal organs in models of pulmonary or extrapulmonary acute lung injury with similar mechanical compromises. The pathophysiology of acute lung injury differs according to the type of primary insult.

DESIGN

Prospective, randomized, controlled, experimental study.

SETTING

University research laboratory.

MEASUREMENTS AND MAIN RESULTS

In control animals, sterile saline solution was intratracheally (0.05 mL) or intraperitoneally (0.5 mL) injected. Acute lung injury animals received Escherichia coli lipopolysaccharide intratracheally (40 microg, ALIp) or intraperitoneally (400 microg, ALIexp). Six hours after lipopolysaccharide administration, ALIp and ALIexp animals were further randomized into subgroups receiving saline (0.05 mL) or BMDMC (2 x 10) intravenously. On day 7, BMDMC led to the following: 1) increase in survival rate; 2) reduction in static lung elastance, alveolar collapse, and bronchoalveolar lavage fluid cellularity (higher in ALIexp than ALIp); 3) decrease in collagen fiber content, cell apoptosis in lung, kidney, and liver, levels of interleukin-6, KC (murine interleukin-8 homolog), and interleukin-10 in bronchoalveolar lavage fluid, and messenger RNA expression of insulin-like growth factor, platelet-derived growth factor, and transforming growth factor-beta in both groups, as well as repair of basement membrane, epithelium and endothelium, regardless of acute lung injury etiology; 4) increase in vascular endothelial growth factor levels in bronchoalveolar lavage fluid and messenger RNA expression in lung tissue in both acute lung injury groups; and 5) increase in number of green fluorescent protein-positive cells in lung, kidney, and liver in ALIexp.

CONCLUSIONS

BMDMC therapy was effective at modulating the inflammatory and fibrogenic processes in both acute lung injury models; however, survival and lung mechanics and histology improved more in ALIexp. These changes may be attributed to paracrine effects balancing pro- and anti-inflammatory cytokines and growth factors, because a small degree of pulmonary BMDMC engraftment was observed.

Functions of type II pneumocyte-derived vascular endothelial growth factor in alveolar structure, acute inflammation, and vascular permeability

Vascular endothelial growth factor-A (VEGF) is a potent regulator of vascular permeability, inflammatory response, and cell survival in the lung. To explore the functions of VEGF produced locally in type II pneumocytes, we generated mice with a conditional deletion of VEGF-A using Cre recombinase driven by the human surfactant protein C (SPC) promoter. In 7- to 10-week-old VEGF-knockout (SPC-VEGF-KO) mice, lung histology and physiology were essentially normal, except for higher dynamic lung compliance and lower pulmonary vascular permeability. Emphysema was seen in 28- to 32-week-old animals. To investigate the role of type II pneumocyte-derived VEGF in acute lung injury, we challenged 7- to 10-week-old SPC-VEGF-KO mice and their wild-type littermates with intestinal ischemia-reperfusion. Bronchoalveolar lavage fluid total cell count, pulmonary permeability, and lung injury score were significantly attenuated, and total lung VEGF levels were significantly lower in SPC-VEGF-KO mice compared with wild-type controls. In SPC-VEGF-KO mice, activated caspase 3-positive type II epithelial cells were increased after intestinal ischemia-reperfusion, even though there was no significant difference in the total number of cells positive for terminal deoxynucleotidyl transferase dUTP nick-end labeling. We conclude that VEGF in type II cells helps protect alveolar epithelial cells from caspase-dependent apoptosis. However, VEGF produced from type II cells may contribute to increased vascular permeability during acute lung injury.

PTX3 as a potential biomarker of acute lung injury: supporting evidence from animal experimentation

OBJECTIVE

Increased expression of long pentraxin 3 (PTX3) has been found in patients with sepsis or acute respiratory distress syndrome. Tissue factor (TF) activation plays an important role in the pathogenesis of acute lung injury. The present study sought to determine the relationship between PTX3 expression and TF activation in acute lung injury.

METHODS

Lung injury was induced by intratracheal instillation of lipopolysaccharide (LPS) in mice, and the PTX3 expression, TF activation and lung injury were determined. We also treated the lung injury with an anti-human tissue factor monoclonal antibody in human tissue factor knock-in (hTF-KI) mice.

RESULTS

Balb/c mice were challenged with increasing doses of LPS. After 24 h, PTX3 protein in the bronchioalveolar lavage fluid was increased in parallel with the severity of lung injury, and correlated with tissue factor (TF) activity. The expression and distribution of PTX3 and TF were further documented in detail 6 h after LPS (5 mg/kg) instillation. Treatment with anti-human TF monoclonal antibody dramatically attenuated LPS-induced lung injury, alveolar fibrin deposition and inflammatory cell infiltration in"humanized" hTF-KI mice 6 h after LPS challenge. The PTX3 expression was significantly decreased by the anti-coagulant therapy.

CONCLUSION

These results support the clinical finding that PTX3 may be a useful biomarker to the reflect severity of lung injury and provide effective therapies. The interplay between PTX3 and TF could be a potential mechanism that mediates lung injury.

A potential role for reactive oxygen species and the HIF-1alpha-VEGF pathway in hypoxia-induced pulmonary vascular leak

Acute hypoxia causes pulmonary vascular leak and is involved in the pathogenesis of pulmonary edema associated with inflammation, acute altitude exposure, and other critical illnesses. Reactive oxygen species, HIF-1, and VEGF have all been implicated in various hypoxic pathologies, yet the ROS-HIF-1-VEGF pathway in pulmonary vascular leak has not been defined. We hypothesized that the ROS-HIF-1-VEGF pathway has an important role in producing hypoxia-induced pulmonary vascular leak. Human pulmonary artery endothelial cell (HPAEC) monolayers were exposed to either normoxia (21% O(2)) or acute hypoxia (3% O(2)) for 24 h and monolayer permeability and H(2)O(2), nuclear HIF-1alpha, and cytosolic VEGF levels were determined. HPAEC were treated with antioxidant cocktail (AO; ascorbate, glutathione, and alpha-tocopherol), HIF-1 siRNA, or the VEGF soluble binding protein fms-like tyrosine kinase-1 (sFlt-1) to delineate the role of the ROS-HIF-1-VEGF pathway in hypoxia-induced HPAEC leak. Additionally, mice exposed to hypobaric hypoxia (18,000 ft, 10% O(2)) were treated with the same antioxidant to determine if in vitro responses corresponded to in vivo hypoxia stress. Hypoxia increased albumin permeativity, H(2)O(2) production, and nuclear HIF-1alpha and cytosolic VEGF concentration. Treatment with an AO lowered the hypoxia-induced HPAEC monolayer permeability as well as the elevation of HIF-1alpha and VEGF. Treatment of hypoxia-induced HPAEC with either an siRNA designed against HIF-1alpha or the VEGF antagonist sFlt-1 decreased monolayer permeability. Mice treated with AO and exposed to hypobaric hypoxia (18,000 ft, 10% O(2)) had less pulmonary vascular leak than those that were untreated. Our data suggest that hypoxia-induced permeability is due, in part, to the ROS-HIF-1alpha-VEGF pathway.

Hypertonic saline attenuates TNF-alpha-induced NF-kappaB activation in pulmonary epithelial cells

Resuscitation with hypertonic saline (HTS) attenuates acute lung injury (ALI) and modulates postinjury hyperinflammation. TNF-alpha-stimulated pulmonary epithelium is a major contributor to hemorrhage-induced ALI. We hypothesized that HTS would inhibit TNF-alpha-induced nuclear factor (NF)-kappaB proinflammatory signaling in pulmonary epithelial cells. Therefore, we pretreated human pulmonary epithelial cells (A549) with hypertonic medium (180 mM NaCl) for 30 min, followed by TNF-alpha stimulation (10 ng/mL). Key regulatory steps and protein concentrations in this pathway were assessed for significant alterations. Hypertonic saline significantly reduced TNF-alpha-induced intercellular adhesion molecule 1 levels and NF-kappaB nuclear localization. The mechanism is attenuated phosphorylation and delayed degradation of IkappaB alpha. Hypertonic saline did not alter TNF-alpha-induced p38 mitogen-activated protein kinase phosphorylation or constitutive vascular endothelial growth factor expression, suggesting that the observed inhibition is not a generalized suppression of protein phosphorylation or cellular function. These results show that HTS inhibits TNF-alpha-induced NF-kappaB activation in the pulmonary epithelium and, further, our understanding of its beneficial effects in hemorrhage-induced ALI.

Vascular endothelial growth factor receptor and coreceptor expression in human acute respiratory distress syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) is characterized by the development of noncardiogenic pulmonary edema, which has been related to the bioactivity of vascular endothelial growth factor (VEGF). Vascular endothelial growth factor receptors and coreceptors regulate this bioactivity. We hypothesized VEGF receptors 1 and 2 (VEGFR1, VEGFR2) and coreceptor neuropilin-1 (NRP-1) would be expressed in human lung tissue with a significant change in expression in ARDS lung.

METHODS

Archival "normal" (no lung pathology and non-ARDS), "early" (within 48 hours), and "later" (after day 7) ARDS lung-tissue sections (n = 5) were immunostained for VEGFR1, VEGFR2, and NRP-1 from human subjects (n = 4). Staining was assessed densitometrically using Histometrix software.

RESULTS

VEGFR1, VEGFR2, and NRP-1 were expressed on both sides of the alveolar-capillary membrane in both normal and ARDS human lung tissue. In later ARDS, there was a significant up-regulation of VEGFR1 and VEGFR2 versus normal and early ARDS (P < .0001). Neuropilin-1 was down-regulated in early ARDS versus normal lung (P < .05), with normalization in later ARDS (P < .001).

CONCLUSION

Differential temporal VEGFR1, VEGFR2, and NRP-1 up-regulation occurs in human ARDS, providing evidence of further functional regulation of VEGF bioactivity via VEGFR2 consistent with a protective role for VEGF in lung injury recovery. The mechanisms behind these observations remain to be clarified.

Vascular Endothelial Growth Factor (VEGF) isoform expression and activity in human and murine lung injury

BACKGROUND

The properties of vascular endothelial growth factor (VEGF) as a potent vascular permogen and mitogen have led to investigation of its potential role in lung injury. Alternate spliced VEGF transcript generates several isoforms with potentially differing functions. The purpose of this study was to determine VEGF isoform expression and source in normal and ARDS subjects and investigate the expression and regulation of VEGF isoforms by human alveolar type 2 (ATII) cells.

METHODS

VEGF protein expression was assessed immunohistochemically in archival normal and ARDS human lung tissue. VEGF isoform mRNA expression was assessed in human and murine lung tissue. Purified ATII cells were cultured with proinflammatory cytokines prior to RNA extraction/cell supernatant sampling/proliferation assay.

MEASUREMENTS AND MAIN RESULTS

VEGF was expressed on alveolar epithelium, vascular endothelium and alveolar macrophages in normal and ARDS human lung tissue. Increases in VEGF expression were detected in later ARDS in comparison to both normal subjects and early ARDS (p < 0.001). VEGF121, VEGF165 and VEGF189 isoform mRNA expression increased in later ARDS (p < 0.05). The ratio of soluble to cell-associated isoforms was lower in early ARDS than normal subjects and later ARDS and also in murine lung injury. ATII cells constitutionally produced VEGF165 and VEGF121 protein which was increased by LPS (p < 0.05). VEGF165 upregulated ATII cell proliferation (p < 0.001) that was inhibited by soluble VEGF receptor 1 (sflt) (p < 0.05).

CONCLUSION

These data demonstrate that changes in VEGF isoform expression occur in ARDS which may be related to their production by and mitogenic effect on ATII cells; with potentially significant clinical consequences.

Vascular endothelial growth factor in severe sepsis and septic shock

BACKGROUND

Vascular endothelial growth factor (VEGF) levels have been shown to be elevated in severe sepsis. We investigated the value of VEGF in predicting organ dysfunction and hospital mortality in adult patients with severe sepsis.

METHODS

We conducted a prospective observational cohort study in 24 closed multidisciplinary intensive care units (ICU) in Finland. All ICU admission episodes (4500) were screened for severe sepsis from November 1, 2004, to February 28, 2005. Patients were eligible if they fulfilled the criteria for severe sepsis.

RESULTS

Severe sepsis was found in 470 patients. Laboratory samples were obtained after informed consent from 250 patients at study entry (day 0) and from 215 patients after 72 h. These samples were compared with samples from 30 healthy individuals. The ICU mortality was 13.2% and hospital mortality 26%. Median serum VEGF concentrations on day 0 were 423 pg/mL (interquartile range [IQR] 159 and 858 pg/mL), and after 72 h were 521 pg/mL (IQR 182 and 1092 pg/mL), which were both higher than in healthy controls (P = 0.029 and 0.003, respectively). Low VEGF concentrations were associated with more severe renal and hematological dysfunction (Sequential Organ Failure Assessment scores 3-4 compared with scores 0-2). VEGF concentrations in day 0 and after 72 h were lower in nonsurvivors (P = 0.01 and <0.01, respectively) than in survivors, but the receiver operating characteristic curve analyses of concentrations of VEGF on day 0 and at 72 h revealed areas under the curve of 0.58 and 0.63 (95% confidence limits 0.48-0.68 and 0.54-0.72, P = 0.1 and 0.009, respectively).

CONCLUSIONS

VEGF concentrations are increased in patients with severe sepsis. Low concentrations are associated with hematological and renal dysfunction. VEGF concentrations were lower in nonsurvivors than in survivors, but did not adequately predict hospital mortality in patients with severe sepsis.

Developmental regulation of NO-mediated VEGF-induced effects in the lung

Vascular endothelial growth factor (VEGF) is known to have a pivotal role in lung development and in a variety of pathologic conditions in the adult lung. Our earlier studies have shown that NO is a critical mediator of VEGF-induced vascular and extravascular effects in the adult murine lung. As significant differences have been reported in the cytokine responses in the adult versus the neonatal lung, we hypothesized that there may be significant differences in VEGF-induced alterations in the developing as opposed to the mature lung. Furthermore, nitric oxide (NO) mediation of these VEGF-induced effects may be developmentally regulated. Using a novel externally regulatable lung-targeted transgenic murine model, we found that VEGF-induced pulmonary hemorrhage was mediated by NO-dependent mechanisms in adults and newborns. VEGF enhanced surfactant production in adults as well as increased surfactant and lung development in newborns, via an NO-independent mechanism. While the enhanced survival in hyperoxia in the adult was partly NO-dependent, there was enhanced hyperoxia-induced lung injury in the newborn. In addition, human amniotic fluid VEGF levels correlated positively with surfactant phospholipids. Tracheal aspirate VEGF levels had an initial spike, followed by a decline, and then a subsequent rise, in human neonates with an outcome of bronchopulmonary dysplasia or death. Our data show that VEGF can have injurious as well as potentially beneficial developmental effects, of which some are NO dependent, others NO independent. This opens up the possibility of selective manipulation of any VEGF-based intervention using NO inhibitors for maximal potential clinical benefit.

Year in review 2006: Critical Care--Multiple organ failure, sepsis, and shock

In 2006, Critical Care provided important and clinically relevant research data in the field of multiple organ failure, sepsis, and shock. This review summarizes the results of the experimental studies and clinical trials and discusses them in the context of the relevant scientific and clinical background.