Acute Lung Injury And Acute Respiratory Distress Syndrome Research Articles

Lavandula stoechas significantly alleviates cigarette smoke-induced acute lung injury via modulation of oxidative stress and the NF-κB pathway

Cigarette smoke (CS) is one of the major triggering factorsfor oxidative stress and contributes to development of acute lung injury and acute respiratory distress syndrome (ALI/ARDS), both of which are marked by severe lung inflammation. Due to the absence of viable treatment options for ALI/ARDS, methanolic extract of Lavandula stoechas (Ls.Met) was used to evaluate the protective effect against CS-induced ALI in both in vivo and in vitro settings.In order to prepare CS-induced ALI murine models, male Swiss albino mice were exposed to whole-body CS for 10 days. Normal saline (10 mL/kg), Ls.Met (250, 450, 750 mg/kg), and dexamethasone (1 mg/kg) were administered orally to respective animal groups (n = 5/group) 1 h prior to CS-exposure. Twenty-four hrs following the last CS-exposure, bronchoalveolar lavage fluid (BALF) and lungs were harvested to examine the important aspects of ALI. Subsequently, in vitro protective effect of Ls.Met (10 and 100 μM) was assessed against 4% CSE (for 24 h)-stimulated RAW 264.7 macrophages.The presence of phenols and flavonoids was verified by HPLC analysis. Ls.Met dose-dependently and remarkably reduced macrophages and neutrophil invasion into the lungs, lung weight coefficient, albumin exudates into the alveoli, and improved hypoxemia and lung histopathological alterations. Notably, Ls.Met attenuated the CS-induced oxidative stress as evidenced by decreased levels of malondialdehyde, total oxidant status (TOS), and myeloperoxidas, alongside enhanced total antioxidant capacity (TAC) production. Moreover, Ls.Met demonstrated a marked reduction in CS-induced overexpression of proinflammatory cytokines (IL-6, IL-1β, and KC) and inhibited the activation of NF-κB, a key signalling pathway involved in inflammation. Lavandula stoechas could thus be a potential therapeutic option for the treatment of CS-induced ALI.

Growth hormone-releasing hormone receptor antagonist MIA-602 attenuates cardiopulmonary injury induced by BSL-2 rVSV-SARS-CoV-2 in hACE2 mice.

COVID-19 pneumonia causes acute lung injury and acute respiratory distress syndrome (ALI/ARDS) characterized by early pulmonary endothelial and epithelial injuries with altered pulmonary diffusing capacity and obstructive or restrictive physiology. Growth hormone-releasing hormone receptor (GHRH-R) is expressed in the lung and heart. GHRH-R antagonist, MIA-602, has been reported to modulate immune responses to bleomycin lung injury and inflammation in granulomatous sarcoidosis. We hypothesized that MIA-602 would attenuate rVSV-SARS-CoV-2-induced pulmonary dysfunction and heart injury in a BSL-2 mouse model. Male and female K18-hACE2tg mice were inoculated with SARS-CoV-2/USA-WA1/2020, BSL-2-compliant recombinant VSV-eGFP-SARS-CoV-2-Spike (rVSV-SARS-CoV-2), or PBS, and lung viral load, weight loss, histopathology, and gene expression were compared. K18-hACE2tg mice infected with rVSV-SARS-CoV-2 were treated daily with subcutaneous MIA-602 or vehicle and conscious, unrestrained plethysmography performed on days 0, 3, and 5 (n = 7 to 8). Five days after infection mice were killed, and blood and tissues collected for histopathology and protein/gene expression. Both native SARS-CoV-2 and rVSV-SARS-CoV-2 presented similar patterns of weight loss, infectivity (~60%), and histopathologic changes. Daily treatment with MIA-602 conferred weight recovery, reduced lung perivascular inflammation/pneumonia, and decreased lung/heart ICAM-1 expression compared to vehicle. MIA-602 rescued altered respiratory rate, increased expiratory parameters (Te, PEF, EEP), and normalized airflow parameters (Penh and Rpef) compared to vehicle, consistent with decreased airway inflammation. RNASeq followed by protein analysis revealed heightened levels of inflammation and end-stage necroptosis markers, including ZBP1 and pMLKL induced by rVSV-SARS-CoV-2, that were normalized by MIA-602 treatment, consistent with an anti-inflammatory and pro-survival mechanism of action in this preclinical model of COVID-19 pneumonia.

A Bibliometric Analysis of Mesenchymal Stem Cell-Derived Exosomes in Acute Lung Injury/Acute Respiratory Distress Syndrome from 2013 to 2022.

Mesenchymal stem cell-derived exosomes (MSC-exosomes) have been found to effectively improve the systemic inflammatory response caused by acute lung injury and acute respiratory distress syndrome (ALI/ARDS), regulate systemic immune disorders, and help injured cells repair. The purpose of this study was to take a holistic view of the current status and trends of MSC-exosomes research in ALI/ARDS. Bibliometrix, Citespace and VOSviewer software were used for bibliometric analysis of the data. We analysed the world trends, country distribution, institution contribution, most relevant journals and authors, research hotspots, and research hotspots related to Coronavirus Disease 2019 (COVID-19) based on the data collected. China possessed the largest number of publications, while the USA had the highest H-index and the number of citations. Both China and the USA had a high influence in this research field. The largest number of publications in the field of MSC-exosomes and ALI/ARDS were mainly from the University of California system. Stem Cell Research & Therapy published the largest number of papers in this scope. The author with the greatest contribution was LEE JW, and ZHU YG published an article in Stem Cell with the highest local citation score. The most frequent keyword and the latest research hotspot were "NF-κB" and "Coronavirus Disease 2019". Furthermore, our bibliometric analysis results demonstrated that MSC-exosomes intervention and treatment can effectively alleviate the inflammatory response caused by ALI/ARDS. Our bibliometric study suggested the USA and China have a strong influence in this field. COVID-19-induced ALI/ARDS had become a hot topic of research.

Severity of acute lung injury in aspiration pneumonia model mice transplanted with human oral microflora

AbstractObjectivesWhen the microflora balance becomes disturbed, referred to as “dysbiosis,” immune homeostasis is altered, triggering various diseases. In the oral cavity, it is also becoming evident that dysbiosis can act as a stimulus for various systemic diseases. Aspiration pneumonia occurs when oral microflora enters the lungs of elderly individuals. Aspiration pneumonia is highly lethal and intractable; thus, a detailed understanding of the interaction between the microflora and lung immunity is essential to establish the optimal treatment.MethodsHuman oral microflora‐associated mice (HOMA) were created by transplanting human oral commensal microflora into germ‐free mice. Then, the effects of oral microflora were analyzed on lung immunity and systemic conditions of acute lung injury and acute respiratory distress syndrome (ALI/ARDS).ResultsThe microflora in HOMA was in a state of dysbiosis. Furthermore, the accumulation of neutrophils in the lungs during septic conditions was more significant in HOMA. Serum tumor necrosis factor alpha (TNF‐α) increased considerably in HOMA during ALI/ARDS. Simultaneously, the tissue distribution of lung macrophages in HOMA decreased more significantly in alveolar macrophages than in tissue macrophages. Finally, we found that microbial compositions in the lungs during ALI/ARDS were only a single or a small number of species, as in aspiration pneumonia in humans.ConclusionSystemic inflammation and lung tissue damage were observed more significantly in HOMA during ALI/ARDS, suggesting that dysbiosis has a synergistic effect with septic shock, resulting in severe injury. Thus, oral and systemic dysbiosis may be a potential target for treating aspiration pneumonia in the elderly.

Protective effects of Stephania pierrei tuber-derived oxocrebanine against LPS-induced acute lung injury in mice.

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) have high mortality rates. Though corticosteroids are commonly used for the treatment of these conditions, their efficacy has not been conclusively demonstrated and their use can induce various adverse reactions. Hence, the application of corticosteroids as therapeutic modalities for ALI/ARDS is limited. Meanwhile, the aporphine alkaloid oxocrebanine isolated from Stephania pierrei tubers has demonstrated anti-inflammatory efficacy in murine/human macrophage cell lines stimulated by lipopolysaccharide (LPS). Accordingly, the primary objectives of the present study are to investigate the anti-inflammatory effects of oxocrebanine on LPS-induced murine alveolar epithelial (MLE-12) cells and its efficacy against LPS-induced murine ALI. Results show that oxocrebanine downregulates the abundance of interleukin (IL)-1beta, IL-6, and inducible nitric oxide synthase, as well as the phosphorylation of nuclear factor-kappaB (NF-κB), stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), p38, protein kinase B (Akt), and glycogen synthase kinase-3beta signalling proteins in LPS-inducedMLE-12 cells. Moreover, in a murine ALI model, oxocrebanine lowers lung injury scores and lung wet/dry weight ratios while reducing inflammatory cell infiltration. It also suppresses LPS-induced tumour necrosis factor-alpha and IL-6 in the bronchoalveolar lavage fluid and plasma. Moreover, oxocrebanine downregulates NF-κB, SAPK/JNK, p38, and Akt phosphorylation in the lung tissues of LPS-treated mice. Taken together, the foregoing results show that oxocrebanine provides significant protection against LPS-induced ALI in mice primarily by suppressing various inflammatory signalling pathways in alveolar epithelial cells and lung tissues. Hence, oxocrebanine might prove effective as an anti-inflammatory agent for the treatment of lung inflammation.

Selective inhibition of JNK located on mitochondria protects against mitochondrial dysfunction and cell death caused by endoplasmic reticulum stress in mice with LPS‑induced ALI/ARDS.

Few pharmacological interventions are able to improve the mortality rate of acute lung injury and acute respiratory distress syndrome (ALI/ARDS). The aim of this research was to elucidate whether endoplasmic reticulum (ER) stress and c-Jun-N-terminal kinase (JNK)-mitochondria pathways serve important roles in ALI/ARDS and to determine whether the key component Sab is a potential treatment target. The current study investigated the activation of ER stress and the JNK pathway, the content of JNK located on the mitochondria during ER stress and lipopolysaccharide (LPS)-induced ALI/ARDS by western blot analysis. The treatment effects of Tat-SabKIM1, a selective inhibitor of JNK located on mitochondria were explored by multiple methods including histopathological evaluation, lung cell apoptosis tested by TUNEL assay, mitochondrial membrane permeability and survival analysis. The results verified that ER stress was enhanced during LPS-induced ALI/ARDS and could induce activation of the JNK pathway and JNK-mitochondrial localization as well as mitochondrial dysfunction and cell death. Tat-SabKIM1 alleviated LPS injection-induced lung injury and improved mouse survival rates by specifically inhibiting JNK localization to mitochondria and mito-JNK signal activation without affecting cytosolic/nuclear JNK activation. The protective effect of Tat-SabKIM1 against ALI/ARDS was partly caused by inhibition of the excessive activation of mitochondria-mediated apoptosis and autophagy. These results showed the important role of Sab as a treatment target of ALI/ARDS and the potential treatment effect of Tat-SabKIM1. In conclusion, abnormal activation of the JNK-mitochondrial pathway could significantly disrupt the normal physiological function of lung cells, resulting in the occurrence of ALI/ARDS and selective inhibit of JNK located on mitochondria by Tat-SabKIM1 had a protective effect against the mitochondrial dysfunction and cell death caused by endoplasmic reticulum stress in mice with LPS-induced ALI/ARDS.

Dynamic alterations in the lung microbiota in a rat model of lipopolysaccharide-induced acute lung injury

The lung microbiota have been found to be substantially altered in numerous pulmonary disorders, and crosstalk between the host pathophysiology and lung microbiota plays critical roles in the regulation of disease states. The aim of this study was to investigate dynamic changes in the lung microbiota during different stages of acute lung injury and acute respiratory distress syndrome (ALI/ARDS). Rats receiving an intraperitoneal administration of lipopolysaccharide (LPS) were sacrificed at 12 and 48 h after injection, and the hematological parameters, serum cytokine levels, and histological characteristics of the lung tissue and lung microbiota were assessed. After LPS injection, along with fluctuations of systemic cytokine levels and the onset and regression of pulmonary edema, the diversity, components, and functionalities of the pulmonary microbiota underwent significant dynamic changes. The volatility of the α-diversity indices narrowed after LPS injection, and the indices significantly decreased 48 h later. The abundance of 18 genera and functionality of adenosine triphosphate–binding cassette (ABC) transporters, pentose phosphate, and bacterial chemotaxis pathways were found to significantly differ between specified time points. Several significant correlations between the components and functionalities of the lung microbiota and indicative symptoms of ALI/ARDS were also observed. Brevibacterium was correlated with cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-10, and IL-6 and with hematological percentage of neutrophils (NEU%); Wnt, Notch, and chronic myeloid leukemia signaling pathways were correlated with IL-1β; mitogen-activated protein kinase (MAPK) signaling pathway–yeast was correlated with IL-10; and the pathways of ascorbate and aldarate metabolism and basal transcription factors were correlated with platelet-related indicators. The correlations between the lung microbiota and indicative symptoms of ALI/ARDS identified in this study support further investigation into the underlying mechanism of host–microbiota interactions during lung injury and repair.

Endotoxin stabilizes protein arginine methyltransferase 4 (PRMT4) protein triggering death of lung epithelia

Lung epithelial cell death is a prominent feature of acute lung injury and acute respiratory distress syndrome (ALI/ARDS), which results from severe pulmonary infection leading to respiratory failure. Multiple mechanisms are believed to contribute to the death of epithelia; however, limited data propose a role for epigenetic modifiers. In this study, we report that a chromatin modulator protein arginine N-methyltransferase 4/coactivator-associated arginine methyltransferase 1 (PRMT4/CARM1) is elevated in human lung tissues with pneumonia and in experimental lung injury models. Here PRMT4 is normally targeted for its degradation by an E3 ubiquitin ligase, SCFFBXO9, that interacts with PRMT4 via a phosphodegron to ubiquitinate the chromatin modulator at K228 leading to its proteasomal degradation. Bacterial-derived endotoxin reduced levels of SCFFBXO9 thus increasing PRMT4 cellular concentrations linked to epithelial cell death. Elevated PRMT4 protein caused substantial epithelial cell death via caspase 3-mediated cell death signaling, and depletion of PRMT4 abolished LPS-mediated epithelial cell death both in cellular and murine injury models. These findings implicate a unique molecular interaction between SCFFBXO9 and PRMT4 and its regulation by endotoxin that impacts the life span of lung epithelia, which may play a key role in the pathobiology of tissue injury observed during critical respiratory illness.

Clinical Strains of Pseudomonas aeruginosa Secrete LasB Elastase to Induce Hemorrhagic Diffuse Alveolar Damage in Mice.

BackgroundAcute lung injury and acute respiratory distress syndrome (ALI/ARDS) are most often caused by bacterial pneumonia and characterized by severe dyspnea and high mortality. Knowledge about the lung injury effects of current clinical bacterial strains is lacking. The aim of this study was to investigate the ability of representative pathogenic bacteria isolated from patients to cause ALI/ARDS in mice and identify the major virulence factor.MethodsSeven major bacterial species were isolated from clinical sputum and unilaterally instilled into the mouse airway. A histology study was performed to determine the lung injury effect. Virulence genes were examined by PCR. Sequence types of P. aeruginosa strains were identified by MLST. LC-MS/MS was used to analysis the bacterial exoproducts proteome. LasB was purified through a DEAE-cellulose column, and its toxicity was tested both in vitro and in vivo.ResultsStaphylococcus aureus, Streptococcus pneumoniae, Streptococcus agalactiae, Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli were randomly separated and tested 3 times. Among them, gram-negative bacteria have much more potential to cause acute lung injury than gram-positive bacteria. However, P. aeruginosa is the only pathogen that induces diffuse alveolar damage, hemorrhage and hyaline membranes in the lungs of mice. The lung injury effect is associated with the excreted LasB elastase. Purified LasB recapitulated lung injury similar to P. aeruginosa infection in vivo. We found that this was due to the powerful degradation effect of LasB on the extracellular matrix of the lung and key proteins in the coagulation cascade without inducing obvious cellular apoptosis. We also report for the first time that LasB could induce DIC-like coagulopathy in vitro.ConclusionP. aeruginosa strains are most capable of inducing ALI/ARDS in mice among major clinical pathogenic bacteria tested, and this ability is specifically attributed to their LasB production.

Selective inhibition of JNK mitochondrial location is protective against seawater inhalation‑induced ALI/ARDS.

Localization of phosphorylated (p)-JNK to the mitochondria can lead to functional mitochondrial disorder, resulting in a decrease in energy supply and membrane potential, as well as an increase in reactive oxygen species production and apoptosis. JNK is involved in the occurrence of acute lung injury (ALI), and activation of the JNK pathway is one of the crucial factors resulting in injury. The aim of the present study was to investigate whether the JNK-mitochondria (mitoJNK) location participated in the occurrence of ALI and acute respiratory distress syndrome (ALI/ARDS). The present study examined the activation of the JNK pathway, the content of JNK located on the mitochondria and the treatment effects of a cell-permeable peptide Tat-SabKIM1, which can selectively inhibit the location of JNK on mitochondria. The expression levels of proteins were detected by western blot analysis. Lung injuries were evaluated by histological examination, wet-to-dry weight ratios, and H2O2 and malondialdehyde concentrations in the lung tissues. Lung cells apoptosis was evaluated using TUNEL assay. The results demonstrated that JNK was phosphorylated and activated during seawater inhalation-induced ALI/ARDS, not only in the routine JNK pathway but also in the mitoJNK pathway. It was also found that Tat-SabKIM1 could specifically inhibit JNK localization to mitochondria and the activation of mitoJNK signaling. Furthermore, Tat-SabKIM1 could inhibit Bcl-2-regulated autophagy and mitochondria-mediated apoptosis. In conclusion, mitoJNK localization disrupted the normal physiological functions of the mitochondria during ALI/ARDS, and selective inhibition of JNK and mitochondrial SH3BP5 (also known as Sab) binding with Tat-SabKIM1 can block deterioration from ALI/ARDS.

Comparative Efficacy of Seven Kinds of Chinese Medicine Injections in Acute Lung Injury and Acute Respiratory Distress Syndrome: A Network Meta-analysis of Randomized Controlled Trials.

Background: Chinese medicine injection is wildly used in Acute Lung Injury and Acute respiratory distress syndrome (ALI/ARDS) treatment. However, what kinds of CMIs are more effective in the ALI/ARDS treatment is uncertain. Objectives: Compare the efficacy of different CMIs to identify the optimal one for the therapy of ALI/ARDS patients. Data sources: We searched the data up to April 30, 2020 from MEDLINE, EMBASE, The Cochrane Library, Web of Science, the China Science Journal Citation Report (VIP database), WanFang and the China National Knowledge Infrastructure Study selection: Randomized Clinical Trials assessed at least one of the following outcomes: mortality, Oxygenation Index, length of ICU stay, mechanical ventilation duration, APACHEⅡ score, SOFA score and Murray score, for adult patients of ALI/ADRS. Eligible Studies should also use CMIs as complementary therapies in addition to the standard treatment. Data extraction and synthesis: Two reviewers independently assessed the data. Then, we used a Bayesian random-effects network meta-analysis for data synthesis. Results: Twenty-six studies were selected (involved 2073 participants). Seven kinds of CMIs were evaluated. Compared with standard treatment, Xuebijing is associated with lower mortality. Tanreqing and Xuebijing have the best effect on improving the Oxygenation Index. Huangqi, Danshen, Tanreqing and Xuebijing can significantly reduce the APACHE II score (Huangqi works better than Xuebijing). Huangqi and Xuebijing have the best effect on reducing mechanical ventilation duration and Murray score, while Xuebijing has the best effect on shortening the length of ICU stay. Conclusions: As adjuvant drugs, Xuebijing, Tanreqing and Huangqi show certain effects on treating ALI/ARDS in different aspects.

The Role of Deubiquitinating Enzymes in Acute Lung Injury and Acute Respiratory Distress Syndrome.

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) are characterized by an inflammatory response, alveolar edema, and hypoxemia. ARDS occurs most often in the settings of pneumonia, sepsis, aspiration of gastric contents, or severe trauma. The prevalence of ARDS is approximately 10% in patients of intensive care. There is no effective remedy with mortality high at 30–40%. Most functional proteins are dynamic and stringently governed by ubiquitin proteasomal degradation. Protein ubiquitination is reversible, the covalently attached monoubiquitin or polyubiquitin moieties within the targeted protein can be removed by a group of enzymes called deubiquitinating enzymes (DUBs). Deubiquitination plays an important role in the pathobiology of ALI/ARDS as it regulates proteins critical in engagement of the alveolo-capillary barrier and in the inflammatory response. In this review, we provide an overview of how DUBs emerge in pathogen-induced pulmonary inflammation and related aspects in ALI/ARDS. Better understanding of deubiquitination-relatedsignaling may lead to novel therapeutic approaches by targeting specific elements of the deubiquitination pathways.

Regulation of the NLRP3 inflammasome and macrophage pyroptosis by the p38 MAPK signaling pathway in a mouse model of acute lung injury.

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) is characterized by uncontrolled progressive lung inflammation. Macrophages serve a key role in the pathogenesis of ALI/ARDS. Macrophage pyroptosis is a process of cell death releasing the proinflammatory cytokines interleukin (IL)-1β and IL-18. It was hypothesized that macrophage pyroptosis may partially account for the uncontrolled lung inflammation of ALI/ARDS. In the present study, greater macrophage pyroptosis in lipopolysaccharide (LPS)-treated macrophages and the ALI/ARDS mouse model was observed. The expression of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing (NLRP)3 and IL-1β and cleavage of caspase-1 were significantly elevated following LPS treatment accompanied by greater activation of p38 mitogen-activated protein kinase (MAPK) signaling in vitro and in vivo. However, blocking p38 MAPK signaling through the inhibitor SB203580 significantly suppressed the acute lung injury and excessive lung inflammation in vivo, consistent with the reduced expression of the NLRP3 inflammasome and IL-1β and cleavage of caspase-1. Pretreatment of the rat NR8383 macrophage cell line with SB203580 significantly decreased the population of caspase-1+PI+ pyroptotic cells and expression of NLRP3/IL-1β. However, a larger population of Annexin V+PI- apoptotic cells was observed following blocking of the p38 MAPK signaling pathway. The results indicated that blockage of p38 MAPK signaling pathway skewed macrophage cell death from proinflammatory pyroptosis towards non-inflammatory apoptosis. These effects may contribute to attenuated acute lung injury and excessive inflammation in the SB203580-treated mice. The results may provide a novel therapeutic strategy for the treatment of uncontrolled lung inflammation in patients with ALI/ARDS.

Transcriptomic analysis of lung tissues after hUC-MSCs and FTY720 treatment of lipopolysaccharide-induced acute lung injury in mouse models

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) refer to acute and progressive hypoxic respiratory failure caused by non-cardiogenic factors, which is a common condition occurring in critically ill patients with widespread pulmonary inflammation. Use of a single medication or target cannot treat ALI/ARDS. Mesenchymal stem cells (MSCs) and FTY720, as an analogue of sphingosine-1-phosphate (S1P), can mitigate lipopolysaccharide (LPS)-induced inflammatory lung injury.In this investigation, the clinical efficacy of MSCs alone, FTY720 alone, and a MSC and FTY720 combination in the treatment of LPS-induced lung injury was evaluated in mouse models. The experimental results demonstrated that both MSCs and FTY720 alleviate lung injuries in mice. The combined application of MSCs and FTY720 yielded higher clinical efficacy in mitigating lung injuries compared with use of MSCs or FTY720 alone. Transcriptomic analysis was performed using an Agilent gene expression chip. By analyzing the differences in gene expression of lung tissues between treated and non-treated ALI/ARDS mice, Gene Ontology and Pathway terms related to ALI/ARDS treatment were identified. Moreover, the target genes which might play a pivotal role in the treatment of ALI/ARDS were also detected, thus providing a theoretical basis for multi-target or multi-drug combined treatment of ALI/ARDS and lay a solid foundation for clinical treatment of ALI/ARDS.

Endothelial Caveolin‐1 Positive Microvesicles and Apoptotic Bodies as Early Biomarkers of Acute Lung Injury and Possible Mediators of TGF‐β‐mediated Repair/Remodeling

Endothelial cell injury is a hallmark of Acute Lung Injury and Acute Respiratory Distress Syndrome (ALI/ARDS). We and others have shown endothelial cell caveolin‐1 (Cav‐1) expression is critical for maintaining vascular homeostasis. The aim of this study was to determine how Cav‐1 is depleted during ALI/ARDS and how this may lead to defective vascular repair. ALI was induced in C57BL6 WT mice (male; 2.5–3 months old) by nebulized Escherichia coli lipopolysaccharide (LPS; 10 mg over 1 hr daily for 1 or 4 days). Lung pathology and Cav‐1+ EVs in platelet‐free plasma were assessed by immunohistochemistry, quantification of immune cell number in bronchoalveolar lavage fluid, and western blot. In vitro, human pulmonary artery endothelial cells (HPAECs) and isolated bone marrow‐derived macrophages (BMDMs) were treated with LPS or EVs from control or LPS‐treated animals. At 24 hs, LPS‐induced ALI increased the total number of EVs in murine plasma by 50%. Characterization of isolated EVs indicated Cav‐1 is abundantly expressed in large microvesicles and apoptotic bodies when compared with smaller vesicles, suggesting Cav1+ EVs may be an endothelial cell damage‐associated factor. By western blot, we observed EV‐Cav‐1 expression was increased by 38% after 24 hrs of LPS exposure (0.61 ± 0.05 to 0.98 ± 0.16 a.u.) in control and LPS‐treated mice, respectively (n= 8–10 mice; P<0.05) and decreased below basal level after 96 hrs indicating endothelial Cav‐1 depletion may be partially due to release Cav‐1+ EVs into the circulation. In vitro, LPS‐treated HPAECs released Cav1+ EVs in a concentration‐dependent manner and EVs‐derived from LPS‐treated mice induced TGF‐β release from BMDMs. Thus, EC‐Cav‐1 depletion may be due in part to EV shedding as a result of EC damage which in vivo may be a mechanism of macrophage‐dependent TGF‐β‐induced vascular repair/remodeling. These novel observations may provide an important link to new ways of preventing the onset or progression of ALI/ARDS.Support or Funding InformationCNPq Fellowship‐CsF/Brazil (SDO) and HL125356 and DOD W911NF‐15‐R‐002 (RDM, MGB).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Depletion of Caveolin‐1 in Lung Vasculature and Increase in Caveolin‐1 Positive Circulating Extracellular Vesicles as Early Biomarkers of Endothelial Injury

RationaleEndothelial cell activation and dysfunction are hallmark features of Acute Lung Injury and Acute Respiratory Distress Syndrome (ALI/ARDS). Caveolin‐1 (Cav‐1) is highly expressed in pulmonary microvascular endothelial cells (PMVECs) and plays a key role in maintaining vascular homeostasis. The aim of this study was to determine whether the lung inflammatory response to endotoxin promotes PMVEC Cav‐1 depletion and appearance of Cav‐1 positive circulating extracellular vesicles (Cav‐1+ EVs) and whether this contributes to ALI.MethodsALI was induced in C57BL6 WT mice (male; 2.5–3 months old) by nebulized Escherichia coli lipopolysaccharide (LPS; 10 mg over 1 hr daily for 1 or 4 days). Lung pathology, Cav‐1 and eNOS expression, Cav‐1 ubiquitination, and Cav‐1+ EVs were quantified in total lung or platelet‐free plasma by immunoshistochemistry and western blot, respectively. Broncho‐alveolar lavage fluid (BALF) obtained from control and LPS‐treated mice was used to measure inflammatory cell, cytokine, and albumin levels.ResultsAlveolar accumulation of plasma albumin, immune cells, and pro‐inflammatory and regulatory cytokines (TNF‐α, IL‐1β, IL‐6, TGF‐β) was signficantly elevated in LPS‐treated WT mice. Intermittent airway LPS exposure for 96 hrs also increased Cav‐1 phosphorylation and ubiquitination (Ub) and decreased total lung Cav‐1 expression by 48 ± 4.16 % (n=3–4 mice; P<0.05) when compared to untreated WT mice. Depletion of EC Cav‐1 was accompanied by a decrease in eNOS dimerization indicative of endothelial dysfunction. In addition, circulating Cav‐1+ EVs increased by 38% after 24 hrs of LPS exposure (0.61 ± 0.05 to 0.98 ± 0.16 a.u.) in control and LPS‐treated mice, respectively (n= 8–10 mice; P<0.05) and decreased below basal level after 96 hrs indicating PMVEC Cav‐1 depletion may be due to both Cav‐1 ubiquitination and proteosomal degradation as well as release Cav‐1+ EVs into the circulation. PMVEC Cav‐1 depletion in response to endotoxin exposure was associated with endothelial dysfunction and vascular injury suggesting EC Cav‐1 depletion may play a significant role in the onset of ALI. Similar lung pathology was observed in EC‐specific Cav‐1−/− mice.ConclusionEndothelial cell Cav‐1 depletion and Cav‐1+ EVs may be an early biomarker of pulmonary vascular injury that may predict pulmonary vascular inflammatory disease due to endothelial dysfunction.Support or Funding InformationFinancial support: CNPq Fellowship‐CsF/Brazil (SDO) and HL125356 and DOD W911NF‐15‐R‐002 (RDM, MGB).

Statins for the prevention and treatment of acute lung injury and acute respiratory distress syndrome: A systematic review and meta-analysis.

The purpose of this meta-analysis was to assess whether statins could reduce the morbidity of acute lung injury and acute respiratory distress syndrome (ALI/ARDS) in high-risk patients and improve the clinical outcomes of patients with ALI/ARDS. Studies were obtained from PubMed, Medline, Embase and Cochrane Central Register of Controlled Trials. Randomized controlled trials (RCTs) and cohort studies, which reported morbidity, mortality, ventilator-free days, length of stay in intensive care unit and hospital or oxygenation index, were included in our meta-analysis. Risk ratio (RR) and weighted mean difference (WMD) were calculated using fixed or random effect model. A total of 13 studies covering 12 145 patients were included. Both the only RCT (P = 0.10) and cohort studies (RR, 1.02; 95% CI, 0.67 to 1.55; P = 0.94) showed that statin therapy did not lower the morbidity of ALI/ARDS in high-risk patients. The mortality of ALI/ARDS patients was less likely to be improved by statins (RCT, RR, 1.00; 95% CI, 0.84 to 1.20; P = 0.97; cohort studies, RR, 1.04; 95% CI, 0.85 to 1.27; P = 0.72). Moreover, no significant difference was observed in ventilator-free days, length of stay in intensive care unit as well as hospital and oxygenation index. This meta-analysis suggests that statins neither provide benefit for lowering the morbidity of ALI/ARDS in high-risk patients nor improve the clinical outcomes of ALI/ARDS patients. Hence, it may not be appropriate to advocate statin use for the prevention and treatment of ALI/ARDS.

Emodin suppresses LPS-induced inflammation in RAW264.7 cells through a PPARγ-dependent pathway

Inflammation is a defense and protective response to multiple harmful stimuli. Over and uncontrolled inflammation can lead to local tissues or even systemic damages and injuries. Actually, uncontrolled and self-amplified inflammation is the fundament of the pathogenesis of a variety of inflammatory diseases, including sepsis shock, acute lung injury and acute respiratory distress syndrome (ALI/ARDS). Our recent study showed that emodin, the main active component of Radix rhizoma Rhei, could significantly ameliorate LPS-induced ALI/ARDS in mice. However, its underlying signal pathway was not still very clear. Then, the aim of current study was to explore whether emodin could attenuate LPS-induced inflammation in RAW264.7 cells, and its involved potential mechanism. The mRNA and protein expression of ICAM-1, MCP-1 and PPARγ were measured by qRCR and western blotting, the production of TNF-α was evaluated by ELISA. Then, the phosphorylation of NF-κB p65 was also detected by western blotting. And NF-κB p65 DNA binding activity was analyzed by ELISA as well. Meanwhile, siRNA-PPARγ transfection was performed to knockdown PPARγ expression in cells. Our data revealed that LPS-induced the up-regulation of ICAM-1, MCP-1 and TNF-α, LPS-induced the down-regulation of PPARγ, and LPS-enhanced NF-κB p65 activation and DNA binding activity were substantially suppressed by emdoin in RAW264.7 cells. Furthermore, our data also figured out that these effects of emdoin were largely abrogated by siRNA-PPARγ transfection. Taken together, our results indicated that LPS-induced inflammation were potently compromised by emodin very likely through the PPARγ-dependent inactivation of NF-κB in RAW264.7 cells.

Inhibition of Alveolar Macrophage Pyroptosis Reduces Lipopolysaccharide-induced Acute Lung Injury in Mice.

Background:Pyroptosis is the term for caspase-1-dependent cell death associated with pro-inflammatory cytokines. The role of alveolar macrophage (AM) pyroptosis in the pathogenesis of the acute lung injury and acute respiratory distress syndrome (ALI/ARDS) remains unclear.Methods:C57BL/6 wild-type mice were assigned to sham, lipopolysaccharide (LPS) + vehicle, LPS + acetyl-tyrosyl-valyl- alanyl-aspartyl-chloromethylketone (Ac-YVAD-CMK) and LPS + Z-Asp-Glu-Val-Asp-fluoromethylketone groups. Mice were given intraperitoneal (IP) injections of LPS. Drugs were IP injected 1 h before LPS administration. Mice were sacrificed 16 h after LPS administration, and AMs were isolated. Western blot analysis for active caspase-1 and cleaved caspase-3, evaluation of lung injury and a cytokine release analysis were performed. AMs were treated with LPS and adenosine triphosphate (ATP); caspase-1-dependent cell death was evaluated using flow cytometry; the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) pyroptosomes were examined by immunofluorescence.Results:The expression of activated caspase-1 in AMs was enhanced following LPS challenge compared with the sham group. In the ex vivo study, the caspase-1/propidium iodide-positive cells, caspase-1 specks and ASC pyroptosomes were up-regulated in AMs following LPS/ATP stimulation. The specific caspase-1 inhibitor Ac-YVAD-CMK inhibited the activation of caspase-1 and pyroptotic cell death. Ac-YVAD-CMK also reduced the lung injury, pulmonary edema and total protein in bronchoalveolar lavage fluid (BALF). In addition, Ac-YVAD-CMK significantly inhibited interleukin-β (IL-1β) release both in serum and BALF and reduced the levels of IL-18, tumor necrosis factor-α (TNF-α), High Mobility Group Box 1 (HMGB1) in BALF during LPS-induced ALI/ARDS.Conclusions:This study reported AM pyroptosis during LPS-induced ALI/ARDS in mice and has demonstrated that Ac-YVAD-CMK can prevent AM-induced pyroptosis and lung injury. These preliminary findings may form the basis for further studies to evaluate this pathway as a target for prevention or reduction of ALI/ARDS.

Enteral Immunomodulatory Diet (Omega-3 Fatty Acid, γ-Linolenic Acid and Antioxidant Supplementation) for Acute Lung Injury and Acute Respiratory Distress Syndrome: An Updated Systematic Review and Meta-Analysis.

Enteral immunomodulatory nutrition is considered as a promising therapy for the treatment of acute lung injury and acute respiratory distress syndrome (ALI/ARDS). However, there are still some divergences, and it is unclear whether this treatment should be recommended for patients with ALI/ARDS. Therefore, we conducted this systematic review and meta-analysis to assess the efficacy and safety of an enteral immunomodulatory diet on the clinical outcomes of ALI/ARDS patients. Methods: We retrieved potentially relevant clinical trials though electronic databases. All trials of enteral immunomodulatory diet for ALI/ARDS were included. Analyses of the overall all-cause mortality, 28-day ventilator-free days and 28-day intensive care unit (ICU) free days were conducted. Results: In total six controlled trials were evaluated. The pooled results did not show a significant reduction in the risk of all-cause mortality (M-H RR (the overall Mantel-Haenszel relative risk), 0.81 (95% CI, 0.50–1.31); p = 0.38; 6 trials, n = 717) in ALI/ARDS patients treated with the immunomodulatory diet. This treatment also did not extend the ventilator-free days and ICU-free days. However, patients with high mortality might benefit from this treatment. Conclusions: The enteral immunomodulatory diet could not reduce the severity of the patients with ALI/ARDS. Whereas, for ALI/ARDS patients with high mortality, this treatment might reduce the all-cause mortality, but its use should be treated with discretion.