The acute respiratory distress syndrome

Prone position ventilation for the relief of acute respiratory distress syndrome through improved pulmonary ventilation: Efficacy and safety

BACKGROUND

At present, there is a preliminary clinical consensus that prone position ventilation (PPV) is beneficial to the treatment of acute respiratory distress syndrome (ARDS), and further research on the details of treatment and patients' benefits will help to assess its effectiveness and safety.

AIM

To evaluate the timing, efficacy, and safety of different mechanical ventilation positions (MVP) in treating ARDS.

STUDY DESIGN

The results of clinical trials were directly or indirectly compared by network meta-analysis to compare the effects of different MVP. Two authors independently searched the papers published in PubMed, Embase, Cochrane Library, China Knowledge Infrastructure (CNKI), China Biomedical Discs (CBM), WanFang, and VIP database from January 2000 to August 2022. The outcome indicators were oxygenation index, mechanical ventilation time, ICU hospitalization time, in-hospital mortality, and incidence of adverse events. Two authors independently screened the literature, evaluated the quality of the studies, and completed the data extraction. Stata 14.0 was used to conduct a network Meta-analysis, and the intervention measures were ranked according to the surface under the cumulative ranking curve (SUCRA). Funnel plots were drawn to evaluate publication bias.

RESULTS

According to the inclusion and exclusion criteria, 75 studies (including 6333 patient data) were finally included. According to the analysis results, PPV was the best for improving the oxygenation index. The SUCRA values of mechanical ventilation time, ICU hospitalization time, and in-hospital mortality were ranked as PPV > lateral position ventilation (LPV) > supine position ventilation (SuPV) > semireclining position ventilation (SePV). The SUCRA values in the incidence of adverse events were ranked as LPV > PPV > SuPV > SePV. All outcome measures had good consistency and low statistical heterogeneity. Funnel plot analysis shows that papers reported within three days of mechanical ventilation time, over five days of mechanical ventilation time, and in-hospital mortality were more likely to have publication bias.

CONCLUSIONS

PPV has the best effect on improving the oxygenation index, reducing mechanical ventilation time, shortening ICU hospitalization time, and reducing in-hospital mortality. Early and long-term use of PPV to improve pulmonary ventilatory function will be the key to improving patients' survival and quality of life with ARDS.

RELEVANCE TO CLINICAL PRACTICE

PPV significantly affects patients with ARDS, which can shorten the treatment time and reduce hospital costs. During the treatment, nursing observation should be strengthened to prevent adverse events.

Electric Cell-Substrate Impedance Sensing (ECIS) as a Platform for Evaluating Barrier-Function Susceptibility and Damage from Pulmonary Atelectrauma

Biophysical insults that either reduce barrier function (COVID-19, smoke inhalation, aspiration, and inflammation) or increase mechanical stress (surfactant dysfunction) make the lung more susceptible to atelectrauma. We investigate the susceptibility and time-dependent disruption of barrier function associated with pulmonary atelectrauma of epithelial cells that occurs in acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI). This in vitro study was performed using Electric Cell-substrate Impedance Sensing (ECIS) as a noninvasive evaluating technique for repetitive stress stimulus/response on monolayers of the human lung epithelial cell line NCI-H441. Atelectrauma was mimicked through recruitment/derecruitment (RD) of a semi-infinite air bubble to the fluid-occluded micro-channel. We show that a confluent monolayer with a high level of barrier function is nearly impervious to atelectrauma for hundreds of RD events. Nevertheless, barrier function is eventually diminished, and after a critical number of RD insults, the monolayer disintegrates exponentially. Confluent layers with lower initial barrier function are less resilient. These results indicate that the first line of defense from atelectrauma resides with intercellular binding. After disruption, the epithelial layer community protection is diminished and atelectrauma ensues. ECIS may provide a platform for identifying damaging stimuli, ventilation scenarios, or pharmaceuticals that can reduce susceptibility or enhance barrier-function recovery.

Routine Use of Prescription Adderall Leading to Non-cardiogenic Pulmonary Edema and Respiratory Failure

A 47-year-old female with attention-deficit/hyperactivity disorder on prescription Adderall presented to the hospital with worsening dyspnea for the one-month duration. She was admitted to the medical intensive care unit with respiratory failure requiring non-invasive positive pressure ventilation. Cardiac catheterization confirmed the diagnosis of non-cardiogenic pulmonary edema. With the discontinuation of Adderall, use of BiPAP, and aggressive diuresis with loop diuretics, there was evidence of symptomatic, laboratory, and radiological improvement. Her symptoms were attributed to Adderall use as a diagnosis of exclusion. To our knowledge, this paper reports the first case of Adderall-induced non-cardiogenic pulmonary edema leading to respiratory failure. Although case reports of abuse or overdose of other stimulants such as amphetamine and cocaine leading to a plethora of cardiac and pulmonary complications such as acute respiratory distress syndrome (ARDS), cardiogenic pulmonary edema, and non-cardiogenic pulmonary edema exist, there are no reports that using Adderall at routine prescription doses can lead to these problems.

Macrophages in Lung Injury, Repair, and Fibrosis

Fibrosis progression in the lung commonly results in impaired functional gas exchange, respiratory failure, or even death. In addition to the aberrant activation and differentiation of lung fibroblasts, persistent alveolar injury and incomplete repair are the driving factors of lung fibrotic response. Macrophages are activated and polarized in response to lipopolysaccharide- or bleomycin-induced lung injury. The classically activated macrophage (M1) and alternatively activated macrophage (M2) have been extensively investigated in lung injury, repair, and fibrosis. In the present review, we summarized the current data on monocyte-derived macrophages that are recruited to the lung, as well as alveolar resident macrophages and their polarization, pyroptosis, and phagocytosis in acute lung injury (ALI). Additionally, we described how macrophages interact with lung epithelial cells during lung repair. Finally, we emphasized the role of macrophage polarization in the pulmonary fibrotic response, and elucidated the potential benefits of targeting macrophage in alleviating pulmonary fibrosis.

Review and Analysis of Massively Registered Clinical Trials of COVID-19 using the Text Mining Approach

OBJECTIVE

Immediately after the outbreak of nCoV, many clinical trials are registered for COVID-19. The numbers of registrations are now raising inordinately. It is challenging to understand which research areas are explored in this massive pool of clinical studies. If such information can be compiled, then it is easy to explore new research studies for possible contributions in COVID-19 research.

METHODS

In the present work, a text-mining technique of artificial intelligence is utilized to map the research domains explored through the clinical trials of COVID-19. With the help of the open-- source and graphical user interface-based tool, 3007 clinical trials are analyzed here. The dataset is acquired from the international clinical trial registry platform of WHO. With the help of hierarchical cluster analysis, the clinical trials were grouped according to their common research studies. These clusters are analyzed manually using their word clouds for understanding the scientific area of a particular cluster. The scientific fields of clinical studies are comprehensively reviewed and discussed based on this analysis.

RESULTS

More than three-thousand clinical trials are grouped in 212 clusters by hierarchical cluster analysis. Manual intervention of these clusters using their individual word-cloud helped to identify various scientific areas which are explored in COVID19 related clinical studies.

CONCLUSION

The text-mining is an easy and fastest way to explore many registered clinical trials. In our study, thirteen major clusters or research areas were identified in which the majority of clinical trials were registered. Many other uncategorized clinical studies were also identified as "miscellaneous studies". The clinical trials within the individual cluster were studied, and their research purposes are compiled comprehensively in the present work.

Potential mechanism and key genes involved in mechanical ventilation and lipopolysaccharide‑induced acute lung injury

Mechanical ventilation (MV) and lipopolysaccharide (LPS) infection are common causes of acute lung injury. The aim of the present study was to identify the key genes and potential mechanisms involved in mechanical ventilation (MV) and lipopolysaccharide (LPS)-induced acute lung injury (ALI). Gene expression data of adult C57BL/6 mice with ALI induced by inhaling LPS, MV and LPS + MV were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) associated with MV, LPS and LPS + MV were screened, followed by functional enrichment analysis, protein-protein interaction network construction, and prediction of transcription factors and small molecule drugs. Finally, the expression of key genes was verified in vivo using reverse transcription-quantitative PCR. A total of 63, 538 and 1,635 DEGs were associated with MV, LPS and LPS + MV, respectively. MV-associated genes were significantly enriched in the ‘purine ribonucleotide metabolic process’. LPS and LPS + MV-associated genes were significantly enriched in ‘cellular response to cytokine stimulus’ and ‘cell chemotaxis’. All three conditions were enriched in ‘TNF signaling pathway’ and ‘IL-17 signaling pathway’. Expression levels of C-X-C motif chemokine ligand (CXCL)2, CXCL3 and CXCL10 were upregulated in the LPS and LPS + MV groups. Adenosine A2b receptor, zinc finger and BTB domain-containing 16 and hydroxycarboxylic acid receptor 2 were identified as DEGs in the MV group. Compared with the control group, Early growth response 1 and activating TF 3 was upregulated in all three groups. Similarities and differences were observed among the MV- and LPS-induced ALI, and MV may enhance the effects of LPS on gene expression. MV may affect urine ribonucleotide metabolic-related processes, whereas LPS may cause cell chemotaxis and cytokine stimulus responses in ALI progression. The inflammatory response was shared by MV and LPS. The results of the present study may provide insight into a theoretical basis for the study and treatment of ALI.

Pulmonary microbiome patterns correlate with the course of the disease in patients with sepsis-induced ARDS following major abdominal surgery

BACKGROUND

Patients with sepsis-induced Acute Respiratory Distress Syndrome (ARDS) are hallmarked by high mortality rates. Early, targeted antibiotic therapy is crucial for patients' survival. The clinical use of a Next Generation Sequencing (NGS)-based approach for pathogen identification may lead to an improved diagnostic performance. Therefore, the objective of this study was to examine changes in the pulmonary-microbiome and resulting influences on patients' outcome in septic ARDS, but also to compare NGS- and culture-based diagnostic methods for pathogen identification.

METHODS

In total, 30 patients in two groups were enrolled in the study: (1) 15 septic ARDS patients following major abdominal surgery and (2) 15 patients undergoing oesophageal resection serving as controls. In the ARDS group, blood samples were collected at ARDS onset as well as 5 days and 10 days afterwards. At the same timepoints, bronchoalveolar lavages (BAL) were performed to collect epithelial lining fluid for culture-, as well as NGS-based analyses and to evaluate longitudinal changes in the pulmonary microbiome. In the control group, only one BAL and one blood sample were collected.

RESULTS

ARDS patients showed a significantly reduced α-diversity (p=0.007**) and an increased dominance (p=0.012*) in their pulmonary-microbiome. The α-diversity-index correlated with the length of stay in the intensive care unit (p-value=0.015) and the need for mechanical ventilation (p-value=0.009). In 42.9% of all ARDS patients, culture-based results were negative, while NGS findings indicated bacterial colonization.

CONCLUSION

Sepsis-induced ARDS is associated with a significant dysbiosis of patients' pulmonary-microbiome, which is closely correlated with the clinical course of the disease.

TRIAL REGISTRATION

This prospective, observational pilot study was approved by the Ethics Committee of the Medical Faculty of Heidelberg (trial code no. S-063/2015) and was prospectively registered in the German clinical trials register (DRKS-ID: DRKS00008317 prospectively registered: 28.10.2015). All study patients or their legal representatives signed written informed consent.

NecroX-5 alleviate lipopolysaccharide-induced acute respiratory distress syndrome by inhibiting TXNIP/NLRP3 and NF-κB

The activation of NLRP3 inflammasome and NF-κB pathway, associating with oxidativestress, have been implicated in the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). NecroX-5 has been reported to exhibit theeffectsofanti-oxidation and anti-stress in various diseases. However, the role of NecroX-5 in ALI has not been explicitly demonstrated. The aim of this study was to explore the therapeutic effects and potential mechanism action of NecroX-5 on ALI. Here, we found that NecroX-5 pretreatment dramatically diminished the levels of IL-1β, IL-18 and ROS in in RAW264.7 cells challenged with LPS and ATP. Furthermore, NecroX-5 suppressed the activation of NLRP3 inflammasome and NF-κB signalpathway. In addition, NecroX-5 also inhibited the thioredoxin-interacting protein (TXNIP) expression. In vivo, NecroX-5 reduced the LPS-induced lung histopathological injury, the number of TUNEL-positive cells, lung wet/dry (W/D) ratio, levels of total protein and inflammatory cytokines in the bronchoalveolar lavage fluid (BALF) in mice. Additionally, LPS-induced upregulation of myeloperoxidase (MPO), ROS production and malondialdehyde (MDA) were inhibited by NecroX-5 administration. Thus, our results demonstrate that NecroX-5 protects against LPS-induced ALI by inhibiting TXNIP/NLRP3 and NF-κB.

PIM1 inhibitor SMI-4a attenuated lipopolysaccharide-induced acute lung injury through suppressing macrophage inflammatory responses via modulating p65 phosphorylation

PIM kinase is involved in the cellular processes of growth, differentiation and apoptosis. However, the role of PIM1 in lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains largely unknown. A trend of PIM1 in the lung tissue of LPS-induced ALI at different time points was detected. Histology, wet/dry (W/D) ratio, inflammatory cells in the bronchoalveolar lavage fluid (BALF) and survival rate analyses were performed when mice received the PIM1 inhibitor SMI-4a intratracheally 3 h before LPS administration. Cytokine production in vivo and in vitro was measured after SMI-4a pretreatment. NF-κB subunit p65 expression in nuclei and phosphorylation at Ser276 in lung tissues or cells were detected by Western blot analysis. The results showed that PIM1 mRNA and protein were upregulated in the lung tissue of LPS-induced ALI. The PIM1 inhibitor SMI-4a markedly improved the survival rate after lethal LPS administration, reduced the severity of lung edema, attenuated the histologic injuries of the lung tissue and reduced the counts of infiltrated inflammatory cells in the BALF. The PIM1 inhibitor SMI-4a suppressed the production of cytokines in LPS-treated RAW264.7 cell supernatants and BALF. Furthermore, LPS administration upregulated the levels of nuclear p65 and phosphorylated p65 (p-p65) at Ser276, whereas pretreatment with the PIM1 inhibitor SMI-4a reduced p65 upregulation in the nucleus and p-p65 at Ser276. Taken together, these data indicate that the PIM1 inhibitor SMI-4a may serve as a promising therapeutic strategy for LPS-induced ALI by suppressing macrophage production of cytokines via a reduction of p65 activities.

IRF-1 Intervention in the Classical ROS-Dependent Release of NETs during LPS-Induced Acute Lung Injury in Mice

Previously, we demonstrated that neutrophil extracellular traps (NETs) play an essential role in lipopolysaccharide (LPS)-induced acute lung injury. However, the underlying mechanism is unclear. In this study, we showed that knockout of interferon regulatory factor 1 (IRF-1) in mice strongly attenuated the generation of NETs and reactive oxygen species (ROS) production in neutrophils from bronchoalveolar lavage fluid and alleviated LPS-induced lung injury and systemic inflammation. Our in vitro experiments demonstrated that LPS-stimulated platelets induce NET release through two distinct processes: an ROS-independent early/rapid NETosis and a later ROS-dependent classical NETosis. Notably, the classical ROS-dependent pathway plays a dominant role in the generation of NETs. Furthermore, we showed that IRF-1 knockout does not affect the formation of NETs in early/rapid NETosis, but significantly attenuates ROS production and the generation of NETs in classical NETosis, which determines the total levels of NETs released by LPS-stimulated platelets. In conclusion, IRF-1 deficiency plays a key role in moderating the excessive NETs formed via ROS in the classical pathway and retaining the protective role of the low-NET levels generated in early/rapid NETosis, which may serve as a novel target in acute lung injury/acute respiratory distress syndrome.

Protective Effects of Anti-IL17 on Acute Lung Injury Induced by LPS in Mice

Introduction: T helper 17 (Th17) has been implicated in a variety of inflammatory lung and immune system diseases. However, little is known about the expression and biological role of IL-17 in acute lung injury (ALI). We investigated the mechanisms involved in the effect of anti-IL17 in a model of lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. Methods: Mice were pre-treated with anti-IL17, 1h before saline/LPS intratracheal administration alongside non-treated controls and levels of exhaled nitric oxide (eNO), cytokine expression, extracellular matrix remodeling and oxidative stress, as well as immune cell counts in bronchoalveolar lavage fluid (BALF), and respiratory mechanics were assessed in lung tissue. Results: LPS instillation led to an increase in multiple cytokines, proteases, nuclear factor-κB, and Forkhead box P3 (FOXP3), eNO and regulators of the actomyosin cytoskeleton, the number of CD4+ and iNOS-positive cells as well as the number of neutrophils and macrophages in BALF, resistance and elastance of the respiratory system, ARG-1 gene expression, collagen fibers, and actin and 8-iso-PGF2α volume fractions. Pre-treatment with anti-IL17 led to a significant reduction in the level of all assessed factors. Conclusions: Anti-IL17 can protect the lungs from the inflammatory effects of LPS-induced ALI, primarily mediated by the reduced expression of cytokines and oxidative stress. This suggests that further studies using anti-IL17 in a treatment regime would be highly worthwhile.

Extracellular ATP is a danger signal activating P2X7 receptor in a LPS mediated inflammation (ARDS/ALI)

Acute respiratory distress syndrome (ARDS) is a life-threating lung condition resulting from a direct and indirect injury to the lungs [1, 2]. Pathophysiologically it is characterized by an acute alveolar damage, an increased permeability of the microvascular-barrier, leading to protein-rich pulmonary edema and subsequent impairment of arterial oxygenation and respiratory failure [1]. This study examined the role of extracellular ATP in recruiting inflammatory cells to the lung after induction of acute lung injury with lipopolysaccharide (LPS). However, the precise mechanism is poorly understood. Our objective was to investigate the functional role of the P2X7 receptor in the pathogenesis of acute respiratory distress syndrome (ARDS/ acute lung injury (ALI)) in vitro and in vivo. We show that intratracheally applied LPS causes an acute accumulation of ATP in the BALF (bronchoalveolar lavage) and lungs of mice. Prophylactic and therapeutic inhibition of P2X7R signalling by a specific antagonist and knock-out experiments was able to ameliorate the inflammatory response demonstrated by reduced ATP-levels, number of neutrophils and concentration of pro-inflammatory cytokine levels in the BALF. Experiments with chimeric mice showed that P2X7R expression on immune cells was responsible for the observed effect. Consistently, the inflammatory response is diminished only by a cell-type specific knockdown of P2X7 receptor on non-stationary immune cells. Since the results of BALF from patients with acute ARDS or pneumonia simulated the in vivo data after LPS exposure, the P2X7 receptor may be a new therapeutic target for treatment in acute respiratory distress syndrome (ARDS/ALI).

Factors associated with advance directives completion among patients with advance care planning communication in Taipei, Taiwan

Background

Although advance directives (AD) have been implemented for years in western countries, the concept of AD is not promoted extensively in eastern countries. In this study we evaluate a program to systematically conduct advance care planning (ACP) communication for hospitalized patients in Taiwan and identify the factors associated with AD completion.

Methods

In this retrospective evaluation of a clinical ACP program, we identified adult patients with chronic life-limiting illness admitted to Taipei City Hospital between April 2015 and January 2016. Trained healthcare providers held an ACP meeting to discuss patients’ preference regarding end-of-life care and AD completion. A multiple logistic regression was performed to determine the factors associated with the AD completion.

Results

A total of 2878 patients were determined to be eligible for ACP during the study, among which 1798 (62.5%) completed ACP and data was available for 1411 patients (49.1%). Of the 1411 patients who received ACP communication with complete data, the rate of AD completion was 82.6%. The overall mean (SD) age was 78.2 (14.4) years. Adjusting for other variables, AD completion was associated with patients aged ≥ 85 years [adjusted odds ratio (AOR) = 1.80, 95% CI 1.21–2.67], critical illness (AOR = 1.17, 95% CI 1.06–1.30), and social workers participating in ACP meetings (AOR = 1.74, 95% CI 1.24–2.45).

Conclusion

The majority of inpatients with chronic life-limiting illness had ACP communication as part of this ACP program and over 80% completed an AD. Our study demonstrates the feasibility of implementing ACP discussion in East Asia and suggests that social workers may be an important component of ACP communication with patients.

Regenerative Medicine and Immunomodulatory Therapy: Insights From the Kidney, Heart, Brain, and Lung

Regenerative medicine was initially focused on tissue engineering to replace damaged tissues and organs with constructs derived from cells and biomaterials. More recently, this field of inquiry has expanded into exciting areas of translational medicine modulating the body’s own endogenous processes, to prevent tissue damage in organs and to repair and regenerate these damaged tissues. This review will focus on recent insights derived from studies in which the manipulation of the innate immunologic system may diminish acute kidney injury and enhance renal repair and recovery without the progression to chronic kidney disease and renal failure. The manner in which these interventions may improve acute and chronic organ dysfunction, including the heart, brain, and lung, will also be reviewed.

[Acute respiratory distress syndrome in childhood: Changing definition and news from the Pediatric Consensus Conference]

Acute respiratory distress syndrome (ARDS) is a rapidly progressive hypoxemic respiratory insufficiency induced by alveolar filling mainly caused by alveolocapillary wall disruption, following direct or indirect pulmonary injury. Much less frequent in children than in adults, pediatric intensivists had long applied adult guidelines to their daily practice. In 2015, experts from the Pediatric Acute Lung Injury Consensus Conference (PALICC) published the first international guidelines specifically dedicated to pediatric ARDS. After a short summary of the history of the ARDS definition since its first report in 1967, we describe the main diagnostic and therapeutic guidelines for PALICC.

The natural product bergenin ameliorates lipopolysaccharide-induced acute lung injury by inhibiting NF-kappaB activition

ETHNOPHARMACOLOGICAL RELEVANCE

Bergenin, an active constituent of the plants of the genus Bergenia, was reported to have anti-inflammatory effects in the treatment of chronic bronchitis and chronic gastritis clinically. However, its therapeutic effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and its potential mechanisms of actions were still unknown.

AIM OF THIS STUDY

To evaluate the effect of bergenin on murine model of acute lung injury induced by LPS and also to explore its potential mechanisms.

MATERIALS AND METHODS

Half an hour and 12h after an intranasal inhalation of LPS, male BALB/c mice were treated with bergenin (50,100 and 200mg/kg) or dexamethasone (DEX, 5mg/kg) by gavage. Twenty-four hours after LPS exposure, the lung wet/dry ratio, histological changes, myeloperoxidase (MPO) in lung tissues, inflammatory cells (in BALF) and cytokines (in BALF and serum) were detected. Meanwhile, the protein expression of MyD88 and the phosphorylation of NF-κB p65 in lung tissue were analyzed using immunoblot analysis. Moreover, the nuclear translocation and the phosphorylation of NF-κB p65 in Raw264.7 cells were also analyzed. The viability of Raw264.7 cells was determined by MTT assay.

RESULTS

Results showed that bergenin significantly decreased pulmonary edema, improved histological changes and reduced MPO activity in lung tissues. Moreover, bergenin obviously decreased inflammatory cells, IL-1β and IL-6 production in BALF, as well as IL-1β, TNF-α and IL-6 production in serum of LPS-induced ALI mice. Furthermore, bergenin markedly inhibited LPS-induced NF-κB p65 phosphorylation, as well as the expression of MyD88 but not the expression of NF-κB p65 in lung tissues. Additionally, bergenin also significantly inhibited the nuclear translocation and the phosphorylation of NF-κB p65 stimulated by LPS in Raw264.7 cells.

CONCLUSIONS

These findings suggested that bergenin had a therapeutic effect on LPS-induced ALI by inhibiting NF-κB activition.

Neutrophil extracellular traps are indirectly triggered by lipopolysaccharide and contribute to acute lung injury

Neutrophil extracellular traps (NETs) facilitate the extracellular killing of pathogens. However, excessive NETs formation and poor degradation are associated with exacerbated immune responses and tissue injury. In this study, we investigated the role of NETs in lipopolysaccharide (LPS)-mediated acute lung injury (ALI) and assessed the use of DNase I, for the treatment of ALI. Additionally, we focused on the controversial issue of whether LPS directly induces NETs release in vitro. NETs formation was detected in murine ALI tissue in vivo and was associated with increased NETs markers, citrullinated-histone H3 tissue levels and NET-DNA levels in BALF. Treatment with DNase I significantly degraded NETs and reduced citrullinated-histone H3 levels, which protected against ALI and ameliorated pulmonary oedema and total protein in BALF. In addition, DNase I significantly reduced IL-6 and TNF-α levels in plasma and BALF. In vitro, LPS-activated platelets rather than LPS alone efficiently induced NETs release. In conclusion, NETs formed during LPS-induced ALI, caused organ damage and initiated the inflammatory response. NETs degradation by DNase I promoted NET-protein clearance and protected against ALI in mice; thus, DNase I may be a new potential adjuvant for ALI therapy. Specifically, LPS induced NETs formation in an indirect manner via platelets activation.

NEMO-Binding Domain Peptide Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Inhibiting the NF-κB Signaling Pathway

The aim of the present study is to investigate the protective effects and relevant mechanisms exerted by NEMO-binding domain peptide (NBD) against lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice. The ALI model was induced by intratracheally administered atomized LPS (5 mg/kg) to BABL/c mice. Half an hour before LPS administration, we treated the mice with increasing concentrations of intratracheally administered NBD or saline aerosol. Two hours after LPS administration, each group of mice was sacrificed. We observed that NBD pretreatment significantly attenuated LPS-induced lung histopathological injury in a dose-dependent manner. Western blotting established that NBD pretreatment obviously attenuated LPS-induced IκB-α and NF-κBp65 activation and NOX1, NOX2, and NOX4 overexpression. Furthermore, NBD pretreatment increased SOD and T-AOC activity and decreased MDA levels in lung tissue. In addition, NBD also inhibited TNF-α and IL-1β secretion in BALF after LPS challenge. In conclusion, NBD protects against LPS-induced ALI in mice.

Management of refractory hypoxemia

Mechanical ventilation remains the cornerstone in the management of severe acute respiratory failure. Acute respiratory distress syndrome (ARDS) is the most common cause of respiratory failure. It is associated with substantial mortality, and unmanageable refractory hypoxemia remains the most feared clinical possibility. If hypoxemia persists despite application of lung protective ventilation, additional therapies including inhaled vasodilators, prone positioning, recruitment maneuvers, high-frequency oscillatory ventilation, neuromuscular blockade (NMB), and extracorporeal membrane oxygenation may be needed. NMB and prone ventilation are modalities that have been clearly linked to reduced mortality in ARDS. Rescue therapies pose a clinical challenge requiring a precarious balance of risks and benefits, as well as, in-depth knowledge of therapeutic limitations.

Ilex kaushue and Its Bioactive Component 3,5-Dicaffeoylquinic Acid Protected Mice from Lipopolysaccharide-Induced Acute Lung Injury

Acute lung injury (ALI) is a severe respiratory disease with high mortality rates worldwide. Recent reports suggest that human neutrophil elastase (HNE) plays a key role in the inflammatory response that is characteristic of ALI, which indicates that the development of HNE inhibitors could be an efficient treatment strategy. In the current study, an enzyme-based screening assay was used to identify effective HNE inhibitors from a number of traditional Chinese medicines (TCMs). Among them, a water extract of Ilex kaushue (IKWE) effectively inhibited HNE activity (IC₅₀, 11.37 ± 1.59 μg/mL). Using bioactivity-guided fractionation, one new compound and 23 known compounds were identified. Compound 6 (identified as 3,5-dicaffeoylquinic acid; 3,5-DCQA) exerted the most potent and selective inhibitory effect on HNE activity (IC₅₀, 1.86 ± 0.06 μM). In a cell-based assay, 3,5-DCQA not only directly reduced superoxide generation and elastase activity but also attenuated the Src family kinase (SRKs)/Vav signaling pathway in N-formyl-L-Met-L-Leu-L-Phe (fMLF)-stimulated human neutrophils. In an animal disease model, both 3,5-DCQA and standardized IKWE protected against lipopolysaccharide-induced ALI in mice, which provides support for their potential as candidates in the development of new therapeutic agents for neutrophilic inflammatory diseases.

Noninvasive ventilation on mortality of acute respiratory distress syndrome

[Purpose] The aim of this study was to assess the efficacy of noninvasive ventilation (NIV) in acute respiratory distress syndrome (ARDS). [Subjects and Methods] The clinical data of 58 patients with ARDS that required mechanical ventilation in two intensive care units (ICU) was reviewed. [Results] Endotracheal intubation was performed in 55.17% of the total patients and in 39.53% of the patients who received NIV treatment. The APACHE II score for patients who only received IV was significantly higher than those who only underwent NIV (25.67 ± 5.30 vs. 18.12 ± 7.20). However, there were no significant differences in 28-day/90-day survival rates, duration of mechanical ventilation, and length of ICU stay between these two groups. For patients from a NIV-to-IV group, the APACHE II scores before endotracheal intubation were higher than the scores from IV patients (26.12 ± 4.08 vs. 21.94 ± 6.10). The 90-day survival rate in the NIV-to-IV group was significantly lower than that of the IV-only group (23.5% vs. 73.3%), although there was no difference in the 28-day survival rate between the two groups. [Conclusion] The application of NIV reduces the percentage of patients requiring endotracheal intubation.

Endothelial-to-mesenchymal transition in lipopolysaccharide-induced acute lung injury drives a progenitor cell-like phenotype

Pulmonary vascular endothelial function may be impaired by oxidative stress in endotoxemia-derived acute lung injury. Growing evidence suggests that endothelial-to-mesenchymal transition (EndMT) could play a pivotal role in various respiratory diseases; however, it remains unclear whether EndMT participates in the injury/repair process of septic acute lung injury. Here, we analyzed lipopolysaccharide (LPS)-treated mice whose total number of pulmonary vascular endothelial cells (PVECs) transiently decreased after production of reactive oxygen species (ROS), while the population of EndMT-PVECs significantly increased. NAD(P)H oxidase inhibition suppressed EndMT of PVECs. Most EndMT-PVECs derived from tissue-resident cells, not from bone marrow, as assessed by mice with chimeric bone marrow. Bromodeoxyuridine-incorporation assays revealed higher proliferation of capillary EndMT-PVECs. In addition, EndMT-PVECs strongly expressed c-kit and CD133. LPS loading to human lung microvascular endothelial cells (HMVEC-Ls) induced reversible EndMT, as evidenced by phenotypic recovery observed after removal of LPS. LPS-induced EndMT-HMVEC-Ls had increased vasculogenic ability, aldehyde dehydrogenase activity, and expression of drug resistance genes, which are also fundamental properties of progenitor cells. Taken together, our results demonstrate that LPS induces EndMT of tissue-resident PVECs during the early phase of acute lung injury, partly mediated by ROS, contributing to increased proliferation of PVECs.

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.