Infections and the inflammatory response in acute respiratory distress syndrome

Interesting effects of interleukins and immune cells on acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a medical condition characterized by widespread inflammation in the lungs with consequent proportional loss of gas exchange function. ARDS is linked with severe pulmonary or systemic infection. Several factors, including secretory cytokines, immune cells, and lung epithelial and endothelial cells, play a role in the development and progression of this disease. The present study is based on Pubmed database information (1987-2022) using the words "Acute respiratory distress syndrome", "Interleukin", "Cytokines" and "Immune cells". Cytokines and immune cells play an important role in this disease, with particular emphasis on the balance between pro-inflammatory and anti-inflammatory factors. Neutrophils are one of several important mediators of Inflammation, lung tissue destruction, and malfunction during ARDS. Some immune cells, such as macrophages and eosinophils, play a dual role in releasing inflammatory mediators, recruitment inflammatory cells and the progression of ARDS, or releasing anti-inflammatory mediators, clearing the lung of inflammatory cells, and helping to improve the disease. Different interleukins play a role in the development or inhibition of ARDS by helping to activate various signaling pathways, helping to secrete other inflammatory or anti-inflammatory interleukins, and playing a role in the production and balance between immune cells involved in ARDS. As a result, immune cells and, inflammatory cytokines, especially interleukins play an important role in the pathogenesis of this disease Therefore, understanding the relevant mechanisms will help in the proper diagnosis and treatment of this disease.

Levosimendan Ameliorates Cardiopulmonary Function but Not Inflammatory Response in a Dual Model of Experimental ARDS

The calcium sensitiser levosimendan, which is used as an inodilator to treat decompensated heart failure, may also exhibit anti-inflammatory properties. We examined whether treatment with levosimendan improves cardiopulmonary function and is substantially beneficial to the inflammatory response in acute respiratory response syndrome (ARDS). Levosimendan was administered intravenously in a new experimental porcine model of ARDS. For comparison, we used milrinone, another well-known inotropic agent. Our results demonstrated that levosimendan intravenously improved hemodynamics and lung function in a porcine ARDS model. Significant beneficial alterations in the inflammatory response and lung injury were not detected.

Efficacy and safety of corticosteroids in acute respiratory distress syndrome: An overview of meta-analyses

BACKGROUND

Evidence-based recommendations on the efficacy and safety of corticosteroids in acute respiratory distress syndrome (ARDS) remain a therapeutic challenge. Findings from several systematic reviews and meta-analyses are inconsistent. We aimed to assess the published meta-analyses through a systematic review approach and provide further insight into the current uncertainty and also to perform an updated meta-analysis from all the available primary studies.

METHODOLOGY

We followed the Preferred Reporting Items for Systematic Review (PRISMA) guidelines to establish the patients, intervention, control and outcome (PICO) for reviewing published meta-analyses. Data sources such as PubMed/MEDLINE, SCOPUS, Cochrane and Google Scholar from inception to February 2021 were accessed. Prevention of ARDS, mortality, ventilator-free days, ICU stay and safety in terms of occurrence of adverse effects were the patient-related outcomes. The review also assessed meta-analysis design-related outcomes which includes the quality of meta-analysis, factors contributing to the risk of bias, extent and sources of heterogeneity, publication bias and robustness of findings. AMSTAR-2 checklist assessed the quality of published meta-analyses.

RESULTS

A total of 18 meta-analyses were reviewed comprising a total of 38 primary studies and 3760 patients. Fourteen studies were in ARDS, three in community-acquired pneumonia and one in critical care. The overall quality of meta-analyses was observed to be critically low to high. A non-significant risk of publication bias and non-significant level of heterogeneity was observed in the reviewed meta-analysis. Corticosteroid was significantly effective in preventing ARDS among CAP patients. The effect of corticosteroids on mortality was observed to be still inconsistent, whereas significant improvement was observed with ICU and ventilator outcomes compared with the control group. Our meta-analysis observed a significant reduction of mortality in RCTs (RR: 0.78; 95% CI: 0.61 to 0.99) and the duration of mechanical ventilation (MD: -4.75; 95% CI: -7.63 to -1.88); and a significant increase in ventilator-free days (MD: 6.03; 95% CI: 3.59 to 8.47) and ICU-free days (MD: 8.04; 95% CI: 2.70 to 13.38) in ARDS patients treated with corticosteroids compared with the control group.

CONCLUSION

The quality of included studies ranged from critically low to high demonstrating inconsistency in risk of bias. While older studies found no significant effect, recent meta-analyses of RCTs found a significant mortality reduction in the corticosteroid group with considerable levels of heterogeneity. The updated meta-analysis by our team found a significant reduction in mortality in the pooled estimation of RCTs but not in cohort studies. Corticosteroid therapy was effective in terms of ICU and ventilator outcomes with minimal safety concerns. Future meta-analyses should be well executed with specific research questions and well performed with minimal risk of bias to produce good quality evidence.

A Paper-Based IL-6 Test Strip Coupled With a Spectrum-Based Optical Reader for Differentiating Influenza Severity in Children

Influenza virus infection is a major worldwide public health problem. Influenza virus infections are associated with a high hospitalization rate in children between the ages of 5 and 14. The predominant reason for poor influenza prognosis is the lack of any effective means for early diagnosis. Early diagnosis of severe illness is critical to improving patient outcome, and could be especially useful in areas with limited medical resources. Accurate, inexpensive, and easy-to-use diagnostic tools could improve early diagnosis and patient outcome, and reduce overall healthcare costs. We developed an interleukin-6 paper-based test strip that used colloidal gold-conjugated antibodies to detect human interleukin-6 protein. These complexes were captured on a paper-based test strip patterned with perpendicular T lines that were pre-coated with anti-human interleukin-6 antibodies. Applied serum samples interacted with these antibodies and presented as colored bands that could be read using a spectrum-based optical reader. The full-spectrum of the reflected light interleukin-6 protein signal could be obtained from the spectral optics module, and the standard could be used to quantitatively analyze interleukin 6 level in serum. We retrospectively evaluated 10 children (23 serum samples) with severe influenza virus infections, 26 children (26 serum samples) with mild influenza virus infections, and 10 healthy children (10 serum samples). Our system, the combined use of a paper-based test strip and a spectrum-based optical reader, provided both qualitative and quantitative information. When used with the optical reader, the detection limit was improved from a qualitative, naked-eye level of 400 pg/ml to a quantitative, optical reader level of 76.85 pg/ml. After monitoring serum interleukin-6 level via our system, we found a high correlation between our system results and those obtainable using a conventional sandwich enzyme-linked immunosorbent assay method (Rho = 0.706, p < 0.001). The sensitivity and specificity for differentiating between severe and mild influenza using our combined method (test strip coupled with optical reader) were 78.3 and 50.0%, respectively. When interleukin-6 was combined with serum C-reaction protein, the sensitivity and specificity were 85.7 and 95.5%, and the receiver operating characteristic area-under-the-curve was quite high (AUC = 0.911, p < 0.001). The potential advantages of our system, i.e., a paper-based test strip coupled with a spectrum-based optical reader, are as follows: 1) simple user operation; 2) rapid turnaround times–within 20 min; 3) high detection performance; and, 4) low-cost fabrication.

Inhibition of the lipoxin A4 and resolvin D1 receptor impairs host response to acute lung injury caused by pneumococcal pneumonia in mice

Resolution of the acute respiratory distress syndrome (ARDS) from pneumonia requires repair of the injured lung endothelium and alveolar epithelium, removal of neutrophils from the distal airspaces of the lung, and clearance of the pathogen. Previous studies have demonstrated the importance of specialized proresolving mediators (SPMs) in the regulation of host responses during inflammation. Although ARDS is commonly caused by Streptococcus pneumoniae, the role of lipoxin A4 (LXA4) and resolvin D1 (RvD1) in pneumococcal pneumonia is not well understood. In the present experimental study, we tested the hypothesis that endogenous SPMs play a role in the resolution of lung injury in a clinically relevant model of bacterial pneumonia. Blockade of formyl peptide receptor 2 (ALX/FPR2), the receptor for LXA4 and RvD1, with the peptide WRW4 resulted in more pulmonary edema, greater protein accumulation in the air spaces, and increased bacteria accumulation in the air spaces and the blood. Inhibition of this receptor was also associated with decreased levels of proinflammatory cytokines. Even in the presence of antibiotic treatment, WRW4 inhibited the resolution of lung injury. In summary, these experiments demonstrated two novel findings: LXA4 and RvD1 contribute to the resolution of lung injury due to pneumococcal pneumonia, and the mechanism of their benefit likely includes augmenting bacterial clearance and reducing pulmonary edema via the restoration of lung alveolar-capillary barrier permeability.

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.

Novel Perspectives Regarding the Pathology, Inflammation, and Biomarkers of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is an acute inflammation of the lung resulting from damage to the alveolar-capillary membrane, and it is diagnosed using a combination of clinical and physiological variables. ARDS develops in approximately 10% of hospitalised patients with pneumonia and has a mortality rate of approximately 40%. Recent research has identified several biomarkers associated with ARDS pathophysiology, and these may be useful for diagnosing and monitoring ARDS. They may also highlight potential therapeutic targets. This review summarises our current understanding of those clinical biomarkers: (1) biomarkers of alveolar and bronchiolar injury, (2) biomarkers of endothelial damage and coagulation, and (3) biomarkers for treatment responses.

Plasma Insulin-like Growth Factor Binding Protein 7 Contributes Causally to ARDS 28-Day Mortality: Evidence From Multistage Mendelian Randomization

BACKGROUND

ARDS is a devastating syndrome with heterogeneous subtypes, but few causal biomarkers have been identified.

RESEARCH QUESTION

Would multistage Mendelian randomization identify new causal protein biomarkers for ARDS 28-day mortality?

STUDY DESIGN AND METHODS

Three hundred moderate to severe ARDS patients were selected randomly from the Molecular Epidemiology of ARDS cohort for proteomics analysis. Orthogonal projections to latent structures discriminant analysis was applied to detect the association between proteins and ARDS 28-day mortality. Candidate proteins were analyzed using generalized summary data-based Mendelian randomization (GSMR). Protein quantitative trait summary statistics were retrieved from the Efficiency and safety of varying the frequency of whole blood donation (INTERVAL) study (n = 2,504), and a genome-wide association study for ARDS was conducted from the Identification of SNPs Predisposing to Altered Acute Lung Injury Risk (iSPAAR) consortium study (n = 534). Causal mediation analysis detected the role of platelet count in mediating the effect of protein on ARDS prognosis.

RESULTS

Plasma insulin-like growth factor binding protein 7 (IGFBP7) moderately increased ARDS 28-day mortality (OR, 1.11; 95% CI, 1.04-1.19; P = .002) per log2 increase. GSMR analysis coupled with four other Mendelian randomization methods revealed IGFBP7 as a causal biomarker for ARDS 28-day mortality (OR, 2.61; 95% CI, 1.33-5.13; P = .005). Causal mediation analysis indicated that the association between IGFBP7 and ARDS 28-day mortality is mediated by platelet count (OR, 1.03; 95% CI, 1.02-1.04; P = .01).

INTERPRETATION

We identified plasma IGFBP7 as a novel causal protein involved in the pathogenesis of ARDS 28-day mortality and platelet function in ARDS, a topic for further experimental and clinical investigation.

Blood Interleukin-6 Levels Predict Multiple Organ Dysfunction in Critically Ill Patients

BACKGROUND

Predicting multiple organ dysfunction (MOD) in the late phase of critical illnesses is essential. Cytokines are considered biomarkers that can predict clinical outcomes; however, their predictive value for late-phase MOD is unknown. This study aimed to identify the biomarker with the highest predictive value for late-phase MOD.

METHODS

This observational study prospectively evaluated data on adult patients with systemic inflammatory response syndrome, those who presented to the emergency department or were admitted to intensive care units in five tertiary hospitals (n = 174). Seven blood biomarkers levels (interleukin-6 [IL-6], IL-8, IL-10, tumor-necrosis factor-α, white blood cells, C-reactive protein, and procalcitonin) were measured at three timepoints (days 0, 1, and 2). The area under the receiver operating characteristic curve (AUC) was analyzed to evaluate predictive values for MOD (primary outcome, MOD on day 7 [late-phase]; secondary outcome, MOD on day 3 [early-phase]).

RESULTS

Of the measured 7 biomarkers, blood IL-6 levels on day 2 had the highest predictive value for MOD on day 7 using single timepoint data (AUC 0.825, 95% confidence interval [CI] 0.754-0.879). Using three timepoint biomarkers, blood IL-6 levels had the highest predictive value of MOD on day 7 (AUC 0.838, 95% CI 0.768-0.890). Blood IL-6 levels using three timepoint biomarkers had also the highest predictive value for MOD on day 3 (AUC 0.836, 95% CI 0.766-0.888).

CONCLUSION

Of the measured biomarkers, blood IL-6 levels had the highest predictive value for MOD on days 3 and 7. Blood IL-6 levels predict early- and late-phase MOD in critically ill patients.

Modulating TNFα activity allows transgenic IL15-Expressing CLL-1 CAR T cells to safely eliminate acute myeloid leukemia

Background

C-type lectin-like molecule 1 (CLL-1) is highly expressed in acute myeloid leukemia (AML) but is absent in primitive hematopoietic progenitors, making it an attractive target for a chimeric antigen receptor (CAR) T-cell therapy. Here, we optimized our CLL-1 CAR for anti-leukemic activity in mouse xenograft models of aggressive AML.

Methods

First, we optimized the CLL-1 CAR using different spacer, transmembrane and costimulatory sequences. We used a second retroviral vector to coexpress transgenic IL15. We measured the effects of each construct on T cell phenotype and sequential (recursive) co culture assays with tumor cell targets to determine the durability of the anti tumor activity by flow cytometry. We administered CAR T cells to mice engrafted with patient derived xenografts (PDX) and AML cell line and determined anti tumor activity by bioluminescence imaging and weekly bleeding, measured serum cytokines by multiplex analysis. After euthanasia, we examined formalin-fixed/paraffin embedded sections. Unpaired two-tailed Student’s t-tests were used and values of p<0.05 were considered significant. Survival was calculated using Mantel-Cox log-rank test.

Results

In vitro, CLL-1 CAR T cells with interleukin-15 (IL15) were less terminally differentiated (p<0.0001) and had superior expansion compared with CD28z-CD8 CAR T cells without IL15 (p<0.001). In both AML PDX and AML cell line animal models, CLL-1 CAR T coexpressing transgenic IL15 initially expanded better than CD28z-CD8 CAR T without IL15 (p<0.0001), but produced severe acute toxicity associated with high level production of human tumor necrosis factor α (TNFα), IL15 and IL2. Histopathology showed marked inflammatory changes with tissue damage in lung and liver. This acute toxicity could be managed by two strategies, individually or in combination. The excessive TNF alpha secretion could be blocked with anti-TNF alpha antibody, while excessive T cell expansion could be arrested by activation of an inducible caspase nine safety switch by administration of dimerizing drug. Both strategies successfully prolonged tumor-free survival.

Conclusion

Combinatorial treatment with a TNFα blocking antibody and subsequent activation of the caspase-9 control switch increased the expansion, survival and antileukemic potency of CLL-1 CAR T-cells expressing transgenic IL15 while avoiding the toxicities associated with excessive cytokine production and long-term accumulation of activated T-cells.

General Adaptation in Critical Illness: Glucocorticoid Receptor-alpha Master Regulator of Homeostatic Corrections

In critical illness, homeostatic corrections representing the culmination of hundreds of millions of years of evolution, are modulated by the activated glucocorticoid receptor alpha (GRα) and are associated with an enormous bioenergetic and metabolic cost. Appreciation of how homeostatic corrections work and how they evolved provides a conceptual framework to understand the complex pathobiology of critical illness. Emerging literature place the activated GRα at the center of all phases of disease development and resolution, including activation and re-enforcement of innate immunity, downregulation of pro-inflammatory transcription factors, and restoration of anatomy and function. By the time critically ill patients necessitate vital organ support for survival, they have reached near exhaustion or exhaustion of neuroendocrine homeostatic compensation, cell bio-energetic and adaptation functions, and reserves of vital micronutrients. We review how critical illness-related corticosteroid insufficiency, mitochondrial dysfunction/damage, and hypovitaminosis collectively interact to accelerate an anti-homeostatic active process of natural selection. Importantly, the allostatic overload imposed by these homeostatic corrections impacts negatively on both acute and long-term morbidity and mortality. Since the bioenergetic and metabolic reserves to support homeostatic corrections are time-limited, early interventions should be directed at increasing GRα and mitochondria number and function. Present understanding of the activated GC-GRα's role in immunomodulation and disease resolution should be taken into account when re-evaluating how to administer glucocorticoid treatment and co-interventions to improve cellular responsiveness. The activated GRα interdependence with functional mitochondria and three vitamin reserves (B1, C, and D) provides a rationale for co-interventions that include prolonged glucocorticoid treatment in association with rapid correction of hypovitaminosis.

The Association Between the Neutrophil-to-Lymphocyte Ratio and Mortality in Patients With Acute Respiratory Distress Syndrome: A Retrospective Cohort Study

PURPOSE

Systemic inflammation relates to the initiation and progression of acute respiratory distress syndrome (ARDS). As neutrophil-to-lymphocyte ratio (NLR) has been shown to be a prognostic inflammatory biomarker in various diseases, in this study, we sought to explore whether NLR is a prognostic factor in patients with ARDS.

METHODS

A retrospective study was performed on patients diagnosed as ARDS admitted to the intensive care unit (ICU). We calculated the NLR by dividing the neutrophil count by the lymphocyte count and categorized patients into four groups based on quartile of NLR values. The association of NLR quartiles and 28-day mortality was assessed using multivariable Cox regression. Secondary outcomes included ICU mortality and hospital mortality.

RESULTS

A total of 224 patients were included in the final analysis. The median (interquartile range) NLRs from first quartile to fourth quartile were as follows: 6.88 (4.61-7.94), 13.06 (11.35-14.89), 20.99 (19.09-23.19), and 39.39 (32.63-50.15), respectively. The 28-day mortalities for the same groups were as follows: 10.7%, 19.6%, 41.4%, and 53.6% (P < 0.001). Cox regression analysis showed NLR was a significant risk factor predicting 28-day mortality (first quartile, reference group; second quartile, adjusted hazard ratio [HR]= 1.674, 95% confidence interval [CI], 0.462-6.063, P = 0.432; third quartile, HR = 5.075, 95% CI, 1.554-16.576, P = 0.007; fourth quartile, HR = 5.815, 95% CI, 1.824-18.533, P = 0.003). Similar trends were observed for ICU mortality and hospital mortality.

CONCLUSIONS

High NLR was associated with the poor outcome in critically ill patients with ARDS. The NLR therefore seems to be a prognostic biomarker of outcomes in critically ill patients with ARDS. Further investigation is required to validate this relationship with data collected prospectively.

Paralytics, Sedation, and Steroids in Acute Respiratory Distress Syndrome

In this article, we discuss the literature behind the use of paralytics, sedation, and steroids in acute respiratory distress syndrome. We explore the controversies and discuss the recommendations for the use of these agents.

Genomic and Genetic Approaches to Deciphering Acute Respiratory Distress Syndrome Risk and Mortality

Significance: Acute respiratory distress syndrome (ARDS) is a severe, highly heterogeneous critical illness with staggering mortality that is influenced by environmental factors, such as mechanical ventilation, and genetic factors. Significant unmet needs in ARDS are addressing the paucity of validated predictive biomarkers for ARDS risk and susceptibility that hamper the conduct of successful clinical trials in ARDS and the complete absence of novel disease-modifying therapeutic strategies. Recent Advances: The current ARDS definition relies on clinical characteristics that fail to capture the diversity of disease pathology, severity, and mortality risk. We undertook a comprehensive survey of the available ARDS literature to identify genes and genetic variants (candidate gene and limited genome-wide association study approaches) implicated in susceptibility to developing ARDS in hopes of uncovering novel biomarkers for ARDS risk and mortality and potentially novel therapeutic targets in ARDS. We further attempted to address the well-known health disparities that exist in susceptibility to and mortality from ARDS. Critical Issues: Bioinformatic analyses identified 201 ARDS candidate genes with pathway analysis indicating a strong predominance in key evolutionarily conserved inflammatory pathways, including reactive oxygen species, innate immunity-related inflammation, and endothelial vascular signaling pathways. Future Directions: Future studies employing a system biology approach that combines clinical characteristics, genomics, transcriptomics, and proteomics may allow for a better definition of biologically relevant pathways and genotype-phenotype connections and result in improved strategies for the sub-phenotyping of diverse ARDS patients via molecular signatures. These efforts should facilitate the potential for successful clinical trials in ARDS and yield a better fundamental understanding of ARDS pathobiology.

MERS-CoV infection is associated with downregulation of genes encoding Th1 and Th2 cytokines/chemokines and elevated inflammatory innate immune response in the lower respiratory tract

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MERS-CoV infection downregulates Th1 and Th2 cytokines and chemokines.

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MERS-CoV infection provokes high levels of IL-1α, IL-1β and IL-8 (CXCL8).

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Inflammatory cytokines/chemokines correlate with MERS-CoV case fatality rate.

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Th1/Th2 downregulation may contribute to severe infection and evolution of ARDS.

MERS-CoV, a highly pathogenic virus in humans, is associated with high morbidity and case fatality. Inflammatory responses have a significant impact on MERS-CoV pathogenesis and disease outcome. However, CD4⁺ T-cell induced immune responses during acute MERS-CoV infection are barely detectable, with potent inhibition of effector T cells and downregulation of antigen presentation. The local pulmonary immune response, particularly the Th1 and Th2-related immune response during acute severe MERS-CoV infection is not fully understood. In this study, we offer the first insights into the pulmonary gene expression profile of Th1 and Th2-related cytokines/chemokines (Th1 & Th2 responses) during acute MERS-CoV infection using RT² Profiler PCR Arrays. We also quantified the expression level of primary inflammatory cytokines/chemokines. Our results showed a downregulation of Th2, inadequate (partial) Th1 immune response and high expression levels of inflammatory cytokines IL-1α and IL-1β and the neutrophil chemoattractant chemokine IL-8 (CXCL8) in the lower respiratory tract of MERS-CoV infected patients. Moreover, we identified a high viral load in all included patients. We also observed a correlation between inflammatory cytokines, Th1, and Th2 downregulation and the case fatality rate. Th1 and Th2 response downregulation, high expression of inflammatory cytokines, and high viral load may contribute to lung inflammation, severe infection, the evolution of pneumonia and ARDS, and a higher case fatality rate. Further study of the molecular mechanisms underlying the Th1 and Th2 regulatory pathways will be vital for active vaccine development and the identification of novel therapeutic strategies.

Extracorporeal life support and systemic inflammation

Extracorporeal life support (ECLS) encompasses a wide range of extracorporeal modalities that offer short- and intermediate-term mechanical support to the failing heart or lung. Apart from the daily use of cardiopulmonary bypass (CPB) in the operating room, there has been a resurgence of interest and utilization of veno-arterial and veno-venous extracorporeal membrane oxygenation (VA- and VV-ECMO, respectively) and extracorporeal carbon dioxide removal (ECCO₂R) in recent years. This might be attributed to the advancement in technology, nonetheless the morbidity and mortality associated with the clinical application of this technology is still significant. The initiation of ECLS triggers a systemic inflammatory response, which involves the activation of the coagulation cascade, complement systems, endothelial cells, leukocytes, and platelets, thus potentially contributing to morbidity and mortality. This is due to the release of cytokines and other biomarkers of inflammation, which have been associated with multiorgan dysfunction. On the other hand, ECLS can be utilized as a therapy to halt the inflammatory response associated with critical illness and ICU therapeutic intervention, such as facilitating ultra-protective mechanical ventilation. In addition to addressing the impact on outcome of the relationship between inflammation and ECLS, two different but complementary pathophysiological perspectives will be developed in this review: ECLS as the cause of inflammation and ECLS as the treatment of inflammation. This framework may be useful in guiding the development of novel therapeutic strategies to improve the outcome of critical illness.

Machine learning for patient risk stratification for acute respiratory distress syndrome

BACKGROUND

Existing prediction models for acute respiratory distress syndrome (ARDS) require manual chart abstraction and have only fair performance-limiting their suitability for driving clinical interventions. We sought to develop a machine learning approach for the prediction of ARDS that (a) leverages electronic health record (EHR) data, (b) is fully automated, and (c) can be applied at clinically relevant time points throughout a patient's stay.

METHODS AND FINDINGS

We trained a risk stratification model for ARDS using a cohort of 1,621 patients with moderate hypoxia from a single center in 2016, of which 51 patients developed ARDS. We tested the model in a temporally distinct cohort of 1,122 patients from 2017, of which 27 patients developed ARDS. Gold standard diagnosis of ARDS was made by intensive care trained physicians during retrospective chart review. We considered both linear and non-linear approaches to learning the model. The best model used L2-logistic regression with 984 features extracted from the EHR. For patients observed in the hospital at least six hours who then developed moderate hypoxia, the model achieved an area under the receiver operating characteristics curve (AUROC) of 0.81 (95% CI: 0.73-0.88). Selecting a threshold based on the 85th percentile of risk, the model had a sensitivity of 56% (95% CI: 35%, 74%), specificity of 86% (95% CI: 85%, 87%) and positive predictive value of 9% (95% CI: 5%, 14%), identifying a population at four times higher risk for ARDS than other patients with moderate hypoxia and 17 times the risk of hospitalized adults.

CONCLUSIONS

We developed an ARDS prediction model based on EHR data with good discriminative performance. Our results demonstrate the feasibility of a machine learning approach to risk stratifying patients for ARDS solely from data extracted automatically from the EHR.

Association of High Mobility Group Box Protein B1 Gene Polymorphisms with Pneumonia Susceptibility and Severity

OBJECTIVE

To investigate the relationship between the high mobility group box protein B1 (HMGB1) single nucleotide polymorphisms (SNPs) rs1412125, rs2249825, and rs1045411 with pneumonia in terms of susceptibility, severity, and inflammatory response.

METHODS

The genotypes of HMGB1 rs1412125 (-1615T > C), rs2249825 (3814C > G), and rs1045411 (2262C > T) loci in 328 patients with community-acquired pneumonia (CAP) and 317 healthy subjects were analyzed by Sanger sequencing. The expression and secretion of the inflammatory cytokines HMGB1, interleukin (IL)-10, tumor necrosis factor-alpha (TNF-α), and IL-6 were determined after lipopolysaccharide (LPS) stimulation of peripheral whole blood cells.

RESULTS

The risk of CAP was higher in carriers of the mutant HMGB1 rs1412125 and rs2249825 alleles than those that had the wild type alleles (adjusted odds ratio [OR] = 1.241; 95% confidence interval [CI] = 1.061-1.448; p = 0.007; adjusted OR = 1.225; 95% CI = 1.038-1.427; p = 0.016, respectively). Moreover, the mutation-carrying patients with CAP were more likely to develop severe community-acquired pneumonia (SCAP). There was no correlation between the HMGB1 rs1045411 SNP alleles and CAP or SCAP (p > 0.05). The expression and secretion of the inflammatory cytokines HMGB1, IL-10, TNF-α, and IL-6 was significantly higher in LPS-stimulated peripheral blood among patients with mutations at the rs1412125 and rs2249825 loci compared with those with wild type alleles (p < 0.05). The 30-day mortality rates for CAP patients with mutations at the rs1412125 and rs2249825 loci of HMGB1 were significantly higher than those that had wild type alleles. The mortality rate difference between rs1045411 wild-type CAP patients and mutant was not significant (p = 0.789).

CONCLUSION

SNPs at the rs1412125 and rs2249825 loci of HMGB1 are associated with pneumonia in terms of susceptibility, severity, and inflammatory response.

Recombinant chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) protects against LPS-induced lung injury in mice

Acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS) are clinical conditions caused by trauma, lung infection or sepsis. ALI/ARDS is associated with massive recruitment of neutrophils into the lung with release of reactive oxygen species and excessive inflammatory response that damage alveolar tissue. Here we report the successful use of a potent recombinant chemotaxis inhibitory protein (rCHIPS) derived from Staphylococcus aureus in reducing the severity of ALI/ARDS. Treatment with rCHIPS reduces pulmonary inflammation and permeability in mice after intranasal administration of lipopolysaccharide (LPS). rCHIPS treatment significantly reduces lung myeloperoxidase (MPO) activity, pro-inflammatory cytokines, broncho-alveolar lavage (BAL) fluid protein content as well as histopathological changes. In addition, treatment with rCHIPS significantly diminishes neutrophils and leukocytes recruitment into lung tissue after LPS administration and hence protects mice from reactive oxygen species mediated lung injury. Our finding reveals potential therapeutic benefits of using rCHIPS for the treatment of ALI/ARDS.

Too much of a good thing: How modulating LTB4 actions restore host defense in homeostasis or disease

The ability to regulate inflammatory pathways and host defense mechanisms is critical for maintaining homeostasis and responding to infections and tissue injury. While unbalanced inflammation is detrimental to the host; inadequate inflammation might not provide effective signals required to eliminate pathogens. On the other hand, aberrant inflammation could result in organ damage and impair host defense. The lipid mediator leukotriene B₄ (LTB₄) is a potent neutrophil chemoattractant and recently, its role as a dominant molecule that amplifies many arms of phagocyte antimicrobial effector function has been unveiled. However, excessive LTB₄ production contributes to disease severity in chronic inflammatory diseases such as diabetes and arthritis, which could potentially be involved in poor host defense in these groups of patients. In this review we discuss the cellular and molecular programs elicited during LTB₄ production and actions on innate immunity host defense mechanisms as well as potential therapeutic strategies to improve host defense.

Autotransfusion during Extracorporeal Membrane Oxygenation

To reduce allogeneic blood transfusion requirements during extracorporeal membrane oxygenation (ECMO) we evaluated an autotransfusion device which processes and retransfuses erythrocytes of changed ECMO-systems. We studied 10 elective changes of ECMO-systems in 7 patients. Hemoglobin levels, the amount of retransfused autologous blood and of transfused allogeneic packed red blood cell units were documented within 48 h after the system change and compared to the measurements obtained from former ECMO-system changes without using any autotransfusion device. We determined the Horrowitz-index, Interleukin 6, 10, TNF-α and endothelin-I concentrations and coagulation parameters during the 48 hours after system change to study the compatibility of this procedure. Allogeneic blood transfusion was reduced from 7 to 2 units of packed red cells using the autotransfusion device. Additionally, no hints of any harmful side effects in these patients was observed.

Early application of low-dose glucocorticoid improves acute respiratory distress syndrome: A meta-analysis of randomized controlled trials

Previous clinical trials have investigated the effect of glucocorticoid therapy in acute respiratory distress syndrome (ARDS), with controversial results, particularly with regard to the early administration of low dose glucocorticoid. The present meta-analysis aimed to assess whether the application of glucocorticoid was able to reduce mortality in patients with ARDS. A literature search was performed using online databases, including MEDLINE, Embase, Cochrane and CNKI regardless of whether the studies were published in English or Chinese. Following assessment via inclusion and exclusion criteria, two reviewers screened controlled randomized trials which investigated glucocorticoid therapy in ARDS patients and independently extracted data. The quality of all of the included trials was evaluated based on blinding, randomization and other methods. A total of 14 studies with 1,441 patients met the inclusion criteria. The results of the meta-analysis demonstrated that glucocorticoid significantly reduced the overall mortality of patients with ARDS [relative ratio (RR), 0.68; 95% confidence interval (CI), 0.50-0.91; P<0.05], particularly with a low-dose of glucocorticoid (RR, 0.57; 95% CI, 0.39-0.84; P<0.05) at the early phase of ARDS (RR, 0.37; 95% CI, 0.16-0.86; P<0.05), and a longer duration of steroids (RR, 0.44; 95% CI, 0.30-0.64; P<0.05). Administration of steroids also significantly increased the number of days that patients remained alive and were off mechanical ventilation (RR, 3.08; 95% CI, 1.49-4.68; P<0.05) without significantly increasing the novel infection rate (RR, 1.00; 95% CI, 0.44-2.25; P<0.05). Due to inconsistencies and other limitations, the quality of the studies used for the meta-analysis of the effect of glucocorticoid on mortality was low. In conclusion, early use of low dose glucocorticoid may effectively reduce mortality in patients with ARDS. However, this conclusion may be affected by the limited quality of the studies included in the present meta-analysis.

Dexamethasone inhibits endotoxin-induced coagulopathy in human lungs

Essentials Glucocorticoids are associated with an increased risk of thrombosis. Healthy volunteers received dexamethasone or placebo in an endotoxin lung instillation model. Dexamethasone suppressed thrombin generation in bronchoalveolar lavage. Glucocorticoids inhibit endotoxin induced pulmonary coagulopathy.

SUMMARY

Background Activation of local and systemic coagulation is a common finding in patients with pneumonia. There is evidence that glucocorticoids have procoagulant activity in the circulation, particularly in the context of inflammation. The effects of glucocorticoids on local pulmonary coagulation have not yet been investigated. Objective To use a human model of lung inflammation based on the local instillation of endotoxin in order to investigate whether glucocorticoids alter pulmonary coagulation. Methods Twenty-four healthy volunteers were randomized to receive either dexamethasone or placebo in a double-blind trial. Endotoxin was instilled via bronchoscope into right or left lung segments, followed by saline into the contralateral site. Six hours later, a bilateral bronchoalveolar lavage (BAL) was performed and coagulation parameters were measured. Results Endotoxin induced activation of coagulation in the bronchoalveolar compartment: the level of prothrombin fragment 1 + 2 (F1 + 2 ) was increased three-fold (248 pmol L-1 , 95% confidence interval [CI] 43-454 versus 743 pmol L-1 , 95% CI 437-1050) and the level of thrombin-antithrombin complex (TATc) was increased by ~ 50% (31 μg L-1 , 95% CI 18-45 versus 49 μg L-1 , 95% CI 36-61) as compared with saline-challenged segments. Dexamethasone reduced F1 + 2 (284 pmol L-1 , 95% CI 34-534) and TATc (9 μg L-1 , 95% CI 0.7-17) levels almost to those measured in BAL fluid from the saline-instilled segments in the placebo group. Dexamethasone even profoundly reduced F1 + 2 levels (80%) in saline-instilled lung segments (50 pmol L-1 , 95% CI 12-87). In contrast, dexamethasone had no effect on systemic F1 + 2 levels. Conclusions Dexamethasone inhibits endotoxin-induced coagulopathy in lungs. This trial is the first to provide insights into the effects of glucocorticoids on pulmonary coagulation in response to endotoxin.

Two Genetically Similar H9N2 Influenza A Viruses Show Different Pathogenicity in Mice

H9N2 Avian influenza virus has repeatedly infected humans and other mammals, which highlights the need to determine the pathogenicity and the corresponding mechanism of this virus for mammals. In this study, we found two H9N2 viruses with similar genetic background but with different pathogenicity in mice. The A/duck/Nanjing/06/2003 (NJ06) virus was highly pathogenic for mice, with a 50% mouse lethal dose (MLD₅₀) of 10^2.83 50% egg infectious dose (EID₅₀), whereas the A/duck/Nanjing/01/1999 (NJ01) virus was low pathogenic for mice, with a MLD₅₀ of >10^6.81 EID₅₀. Further studies showed that the NJ06 virus grew faster and reached significantly higher titers than NJ01 in vivo and in vitro. Moreover, the NJ06 virus induced more severe lung lesions, and higher levels of inflammatory cellular infiltration and cytokine response in lungs than NJ01 did. However, only 12 different amino acid residues (HA-K157E, NA-A9T, NA-R435K, PB2-T149P, PB2-K627E, PB1-R187K, PA-L548M, PA-M550L, NP-G127E, NP-P277H, NP-D340N, NS1-D171N) were found between the two viruses, and all these residues except for NA-R435K were located in the known functional regions involved in interaction of viral proteins or between the virus and host factors. Summary, our results suggest that multiple amino acid differences may be responsible for the higher pathogenicity of the NJ06 virus for mice, resulting in lethal infection, enhanced viral replication, severe lung lesions, and excessive inflammatory cellular infiltration and cytokine response in lungs. These observations will be helpful for better understanding the pathogenic potential and the corresponding molecular basis of H9N2 viruses that might pose threats to human health in the future.

Association of serum interleukin-6, interleukin-8, and Acute Physiology and Chronic Health Evaluation II score with clinical outcome in patients with acute respiratory distress syndrome

Background and Aim:

Studies on potential biomarkers in experimental models of acute lung injury (ALI) and clinical samples from patients with ALI have provided evidence to the pathophysiology of the mechanisms of lung injury and predictor of clinical outcome. Because of the high mortality and substantial variability in outcomes in patients with acute respiratory distress syndrome (ARDS), identification of biomarkers such as cytokines is important to determine prognosis and guide clinical decision-making.

Materials and Methods:

In this study, we have included thirty patients admitted to Intensive Care Unit diagnosed with ARDS, and serum samples were collected on day 1 and 7 and were analyzed for serum interleukin-6 (IL-6) and IL-8 by ELISA method, and Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring was done on day 1.

Results:

The mortality in the patients observed with ARDS was 34%. APACHE II score was significantly higher in nonsurvivors as compared to survivors. There were no significant differences in gender and biochemical and hematological parameters among the survivors and nonsurvivors. Serum IL-6 and IL-8 levels on day 1 were significantly higher in all the ARDS patients as compared to healthy controls and these levels were returned to near-normal basal levels on day 7. The serum IL-6 and IL-8 levels measured on day 7 were of survivors. As compared to survivors, the IL-6 and IL-8 levels were significantly higher in nonsurvivors measured on day 1. Spearman's rank correlation analysis indicated a significant positive correlation of APACHE II with IL-8. By using APACHE II score, IL-6, and IL-8, the receiver operating characteristic curve was plotted and the provided predictable accuracy of mortality (outcome) was 94%.

Conclusion:

The present study highlighted the importance of measuring the cytokines such as IL-6 and IL-8 in patients with ARDS in predicting the clinical outcome.

Asthma as a disruption in iron homeostasis

Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam's razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e.g. asthma associated with infections, smoking, and obesity). Comparable associations between asthma co-morbidity (e.g. eczema, urticaria, restless leg syndrome, and pulmonary hypertension) with iron deficiency support such a shared mechanistic pathway. Therapies directed at asthma demonstrate a capacity to impact iron homeostasis, further strengthening the relationship. Finally, pathophysiologic events producing asthma, including inflammation, increases in Th2 cells, and muscle contraction, can correlate with iron availability. Recognition of a potential association between asthma and an absolute and/or functional iron deficiency suggests specific therapeutic interventions including inhaled iron.

Fulminant anaplastic large cell lymphoma (ALCL) concomitant with primary cytomegalovirus (CMV) infection, and human herpes virus 8 (HHV-8) infection together with Epstein-Barr-virus (EBV) reactivation in a patient with asymptomatic HIV-infection

Background

Most malignant lymphomas in HIV-patients are caused by reactivation of EBV-infection. Some lymphomas have a very rapid fulminant course. HHV-8 has also been reported to be a cause of lymphoma. The role of CMV in the development of lymphoma is not clear, though both CMV and HHV-8 have been reported in tissues adjacent to the tumour in Burkitt lymphoma patients. Here we present a patient with asymptomatic HIV infection, that contracted a primary cytomegalovirus (CMV) infection and human herpes virus 8 (HHV-8) infection. Three weeks before onset of symptoms the patient had unprotected sex which could be possible source of his CMV and also HHV-8 infection He deteriorated rapidly and died with a generalized anaplastic large cell lymphoma (ALCL).

Methods

A Caucasian homosexual male with asymptomatic human immunodeficiency virus (HIV) infection contracted a primary cytomegalovirus (CMV) infection and human herpes virus 8 (HHV-8) infection. He deteriorated rapidly and died with a generalized anaplastic large cell lymphoma (ALCL). Clinical and laboratory records were compiled. Immunohistochemistry was performed on lymphoid tissues, a liver biopsy, a bone marrow aspirate and the spleen during the illness and at autopsy. Serology and PCR for HIV, CMV, EBV, HHV-1–3 and 6–8 was performed on blood drawn during the course of disease.

Results

The patient presented with an acute primary CMV infection. Biopsies taken 2 weeks before death showed a small focus of ALCL in one lymph node of the neck. Autopsy demonstrated a massive infiltration of ALCL in lymph nodes, liver, spleen and bone marrow. Blood samples confirmed primary CMV- infection, a HHV-8 infection together with reactivation of Epstein- Barr-virus (EBV).

Conclusion

Primary CMV-infection and concomitant HHV-8 infection correlated with reactivation of EBV. We propose that these two viruses influenced the development and progression of the lymphoma. Quantitative PCR blood analysis for EBV, CMV and HHV-8 could be valuable in diagnosis and treatment of this type of very rapidly developing lymphoma. It is also a reminder of the importance of prevention and prophylaxis of several infections by having protected sex.

Key mechanisms governing resolution of lung inflammation

Innate immunity normally provides excellent defence against invading microorganisms. Acute inflammation is a form of innate immune defence and represents one of the primary responses to injury, infection and irritation, largely mediated by granulocyte effector cells such as neutrophils and eosinophils. Failure to remove an inflammatory stimulus (often resulting in failed resolution of inflammation) can lead to chronic inflammation resulting in tissue injury caused by high numbers of infiltrating activated granulocytes. Successful resolution of inflammation is dependent upon the removal of these cells. Under normal physiological conditions, apoptosis (programmed cell death) precedes phagocytic recognition and clearance of these cells by, for example, macrophages, dendritic and epithelial cells (a process known as efferocytosis). Inflammation contributes to immune defence within the respiratory mucosa (responsible for gas exchange) because lung epithelia are continuously exposed to a multiplicity of airborne pathogens, allergens and foreign particles. Failure to resolve inflammation within the respiratory mucosa is a major contributor of numerous lung diseases. This review will summarise the major mechanisms regulating lung inflammation, including key cellular interplays such as apoptotic cell clearance by alveolar macrophages and macrophage/neutrophil/epithelial cell interactions. The different acute and chronic inflammatory disease states caused by dysregulated/impaired resolution of lung inflammation will be discussed. Furthermore, the resolution of lung inflammation during neutrophil/eosinophil-dominant lung injury or enhanced resolution driven via pharmacological manipulation will also be considered.

Serial inflammatory biomarkers of the severity, course and outcome of late onset acute respiratory distress syndrome in critically ill patients with or at risk for the syndrome after new-onset fever

AIM

Accurate biomarkers of the acute respiratory distress syndrome (ARDS) may help risk stratification and management. We assessed the relation between several biomarkers and the severity, course and outcome of late onset ARDS in 101 consecutive critically ill patients with new onset fever.

MATERIALS AND METHODS

On study days 0, 1, 2 and 7 we measured angiopoietin-2 (ANG2), pentraxin-3 (PTX3), interleukin-6 (IL-6), procalcitonin (PCT) and midregional proadrenomedullin (proADM). ARDS was defined by the Berlin definition and by the lung injury score (LIS).

RESULTS

At baseline, 48% had ARDS according to the Berlin definition and 86% according to the LIS. Baseline markers poorly predicted maximum Berlin categories attained within 7 days, whereas ANG2 best predicted maximum LIS. Depending on the ARDS definition, the day-by-day area under the receiver operating characteristic curves suggested greatest monitoring value for IL-6 and PCT, followed by ANG2. ANG2 and proADM predicted outcome, independently of disease severity.

CONCLUSION

Whereas IL-6 and PCT had some disease monitoring value, ANG2 was the only biomarker capable of both predicting the severity, monitoring the course and predicting the outcome of late onset ARDS in febrile critically ill patients, irrespective of underlying risk factor, thereby yielding the most specific ARDS biomarker among those studied.

Effect of sesamin against cytokine production from influenza type A H1N1-induced peripheral blood mononuclear cells: computational and experimental studies

In 2009, swine flu (H1N1) had spread significantly to levels that threatened pandemic influenza. There have been many treatments that have arisen for patients since the WHO first reported the disease. Although some progress in controlling influenza has taken place during the last few years, the disease is not yet under control. The development of new and less expensive anti-influenza drugs is still needed. Here, we show that sesamin from the seeds of the Thai medicinal plant Sesamum indicum has anti-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs) induced by 2009 influenza virus type A H1N1. In this study, the combinatorial screening method combined with the computational approach was applied to investigate the new molecular binding structures of sesamin against the 2009 influenza virus type A H1N1 (p09N1) crystallized structure. Experimental methods were applied to propose the mechanisms of sesamin against cytokine production from H1N1-induced human PBMC model. The molecular dynamics simulation of sesamin binding with the p09N1 crystallized structure showed new molecular binding structures at ARG118, ILE222, ARG224, and TYR406, and it has been proposed that sesamin could potentially be used to produce anti-H1N1 compounds. Furthermore, the mechanisms of sesamin against cytokine production from influenza type A H1N1-induced PBMCs by ELISA and signaling transduction showed that sesamin exhibits the ability to inhibit proinflammatory cytokines, IL-1β and TNF-α, and to enhance the activity of the immune cell cytokine IL-2 via downregulating the phosphorylated JNK, p38, and ERK1/2 MAPK signaling pathways. This information might very well be useful in the prevention and treatment of immune-induced inflammatory disorders.

Acute Respiratory Distress Syndrome: Mortality in a Single Center According to Different Definitions

BACKGROUND

Mortality in acute lung injury (ALI) remains high, with outcome data arising mostly from multicenter studies. We undertook this investigation to determine hospital mortality in patients with ALI in a single center.

METHODS

We studied patients admitted between 2005 and 2012 with ALI and acute respiratory distress syndrome (ARDS) according to the American European Consensus Conference (AECC) criteria and recorded clinical variables. Thereafter, patients were classified as subgroups according to the AECC and Berlin definition in order to compare the clinical characteristics and outcomes.

RESULTS

In the 93 patients comprising the study, hospital mortality was 38%. Mortality at 28 days was 36%. Multivariate analysis associated hospital mortality with age and Pao₂/Fio₂ on day 1 ( P < .001). Differences resulted between the subgroups of AECC (ALI vs ARDS) and Berlin (mild vs moderate vs severe ARDS) in the lung injury score, Pao₂/Fio₂, Pao₂/P_Ao₂, PaCo₂ on day 1, and hospital mortality.

CONCLUSION

The overall hospital mortality (38%) was similar to that of other studies and according to the presence of ARDS (Pao₂/Fio₂ ≤ 200), we found significant differences between ALI and ARDS (AECC) and between mild and moderate or severe ARDS (Berlin) in baseline respiratory variables and mortality.

The Omega-3 Fatty Acid Docosahexaenoic Acid Modulates Inflammatory Mediator Release in Human Alveolar Cells Exposed to Bronchoalveolar Lavage Fluid of ARDS Patients

BACKGROUND

This study investigated whether the 1 : 2 ω-3/ω-6 ratio may reduce proinflammatory response in human alveolar cells (A549) exposed to an ex vivo inflammatory stimulus (bronchoalveolar lavage fluid (BALF) of acute respiratory distress syndrome (ARDS) patients). Methods. We exposed A549 cells to the BALF collected from 12 ARDS patients. After 18 hours, fatty acids (FA) were added as docosahexaenoic acid (DHA, ω-3) and arachidonic acid (AA, ω-6) in two ratios (1 : 2 or 1 : 7). 24 hours later, in culture supernatants were evaluated cytokines (TNF-α, IL-6, IL-8, and IL-10) and prostaglandins (PGE2 and PGE3) release. The FA percentage content in A549 membrane phospholipids, content of COX-2, level of PPARγ, and NF-κB binding activity were determined.

RESULTS

The 1 : 2 DHA/AA ratio reversed the baseline predominance of ω-6 over ω-3 in the cell membranes (P < 0.001). The proinflammatory cytokine release was reduced by the 1 : 2 ratio (P < 0.01 to <0.001) but was increased by the 1 : 7 ratio (P < 0.01). The 1 : 2 ratio reduced COX-2 and PGE2 (P < 0.001) as well as NF-κB translocation into the nucleus (P < 0.01), while it increased activation of PPARγ and IL-10 release (P < 0.001). Conclusion. This study demonstrated that shifting the FA supply from ω-6 to ω-3 decreased proinflammatory mediator release in human alveolar cells exposed to BALF of ARDS patients.

Low-dose corticosteroid use and mortality in severe community-acquired pneumonia patients

The relationship between low-dose corticosteroid use and mortality in patients with severe community-acquired pneumonia (CAP) remains unclear.

6925 patients with severe CAP who received mechanical ventilation with or without shock (defined as use of catecholamines) at 983 hospitals were identified using a Japanese nationwide administrative database. The main outcome measure was 28-day mortality.

2524 patients with severe CAP who received catecholamines were divided into corticosteroid (n=631) and control (n=1893) groups. The 28-day mortality was significantly different between corticosteroid and control groups (unmatched: 24.6% versus 36.3%, p<0.001; propensity score-matched: 25.3% versus 32.6%, p=0.01; inverse probability-weighted: 27.5% versus 34.2%, p<0.001). 4401 patients with severe CAP who did not receive catecholamines were also divided into corticosteroid (n=1112) and control (n=3289) groups. The 28-day mortality was not significantly different between corticosteroid and control groups in propensity score-matched analyses (unmatched: 16.0% versus 19.4%, p=0.01; propensity score-matched: 17.7% versus 15.6%, p=0.22; inverse probability-weighted: 18.8% versus 18.2%, p=0.44).

Low-dose corticosteroid use may be associated with reduced 28-day mortality in patients with septic shock complicating CAP.

Predictive value of plasma biomarkers for mortality and organ failure development in patients with acute respiratory distress syndrome

PURPOSE

To evaluate the predictive value of 6 different biomarkers in the development of multiple-organ failure (MOF) and mortality in a contemporary prospective cohort of acute respiratory distress syndrome (ARDS).

METHODS

Patients with ARDS admitted to a tertiary referral center during an 8-month period were included. Plasma sample collection of 6 different biomarkers on days 1, 3, and 5 after ARDS onset was performed (von Willebrand factor, thrombin-antithrombin III complex, plasminogen activator inhibitor 1, interleukin 8, receptor for advanced glycation end-products, and club cell secretory protein). Main outcomes included hospital mortality and development of MOF. Logistic regression models for MOF and mortality prediction were created including biomarkers levels and clinical predictors.

RESULTS

One hundred patients were included in the study. Do-not-resuscitate status and McCabe score were independently associated with increased mortality. None of the 6 biomarkers measured at the time of ARDS diagnosis predicted hospital mortality. After adjustment for important clinical characteristics, elevated day-1 interleukin 8 levels were associated with the development of MOF.

CONCLUSIONS

Addition of biomarkers did not improve mortality prediction in this cohort of ARDS. Association between elevated interleukin 8 levels and progression of organ failures suggests an important role of exaggerated inflammatory response in the development of MOF.

Plasma biomarkers for acute respiratory distress syndrome: a systematic review and meta-analysis*

OBJECTIVE

Numerous studies have focused on biomarkers for acute lung injury and acute respiratory distress syndrome. Although several biomarkers have been identified, their relative performance is unclear. We aim to provide a quantitative overview of plasma-derived biomarkers associated with acute respiratory distress syndrome diagnosis or mortality.

DATA SOURCES

MEDLINE (inception to January 2012) and personal databases.

STUDY SELECTION

English-language studies on plasma biomarkers associated with acute respiratory distress syndrome diagnosis or mortality.

DATA EXTRACTION

Demographic variables, plasma levels of biomarker, statistical data, acute respiratory distress syndrome occurrence, and mortality rates were retrieved. The methodological quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies score. Clinical outcomes included 1) diagnosis of acute respiratory distress syndrome in the at-risk population and 2) mortality in acute respiratory distress syndrome patients. For each biomarker, pooled odds ratios for clinical outcome were calculated by meta-analysis, and biomarkers were ranked according to pooled odds ratio.

DATA SYNTHESIS

Fifty-four studies appeared eligible for meta-analysis, together including 3,753 patients. We identified 20 biomarkers for diagnosis of acute respiratory distress syndrome in the at-risk population and 19 biomarkers for mortality of acute respiratory distress syndrome patients. The biomarkers most strongly associated with acute respiratory distress syndrome diagnosis in the at-risk population, when increased, were Krebs von den Lungen-6 (odds ratio [95% CI], 6.1 [3.0-12.1]), lactate dehydrogenase (5.7 [1.7-19.1]), soluble receptor for advanced glycation end products (3.5 [1.7-7.2]), and von Willebrand Factor (3.1 [2.0-5.2]). The biomarkers most strongly associated with acute respiratory distress syndrome mortality, when increased, were interleukin-4 (18.0 [6.0-54.2]), interleukin-2 (11.8 [4.3-32.2]), angiopoietin-2 (6.4 [1.3-30.4]), and Krebs von den Lungen-6 (5.1 [3.0-12.2]). Decreased levels of Protein C were associated with increased odds for acute respiratory distress syndrome diagnosis and mortality.

CONCLUSIONS

This meta-analysis provides a unique ranking of plasma biomarkers according to their strength of association with acute respiratory distress syndrome diagnosis or acute respiratory distress syndrome mortality. The relative performance of biomarkers among studies shown in this ranking may help to improve acute respiratory distress syndrome diagnosis and outcome prediction.

Exploring the heterogeneity of effects of corticosteroids on acute respiratory distress syndrome: a systematic review and meta-analysis

Introduction

The effectiveness of corticosteroid therapy on the mortality of acute respiratory distress syndrome (ARDS) remains under debate. We aimed to explore the grounds for the inconsistent results in previous studies and update the evidence.

Methods

We searched MEDLINE, Cochrane Central Register of Controlled Trials and Web of Science up to December 2013. Eligible studies included randomized clinical trials (RCTs) and cohort studies that reported mortality and that had corticosteroid nonusers for comparison. The effect of corticosteroids on ARDS mortality was assessed by relative risk (RR) and risk difference (RD) for ICU, hospital, and 60-day mortality using a random-effects model.

Results

Eight RCTs and 10 cohort studies were included for analysis. In RCTs, corticosteroids had a possible but statistically insignificant effect on ICU mortality (RD, −0.28; 95% confidence interval (CI), −0.53 to −0.03 and RR, 0.55; 95% CI, 0.24 to 1.25) but no effect on 60-day mortality (RD, −0.01; 95% CI, −0.12 to 0.10 and RR, 0.97; 95% CI, 0.75 to 1.26). In cohort studies, corticosteroids had no effect on ICU mortality (RR, 1.05; 95% CI, 0.74 to 1.49) but non-significantly increased 60-day mortality (RR, 1.30; 95% CI, 0.96 to 1.78). In the subgroup analysis by ARDS etiology, corticosteroids significantly increased mortality in influenza-related ARDS (three cohort studies, RR, 2.45, 95% CI, 1.40 to 4.27).

Conclusions

The effects of corticosteroids on the mortality of ARDS differed by duration of outcome measures and etiologies. Corticosteroids did not improve longer-term outcomes and may cause harm in certain subgroups. Current data do not support routine use of corticosteroids in ARDS. More clinical trials are needed to specify the favorable and unfavorable subgroups for corticosteroid therapy.

A human lung xenograft mouse model of Nipah virus infection

Nipah virus (NiV) is a member of the genus Henipavirus (family Paramyxoviridae) that causes severe and often lethal respiratory illness and encephalitis in humans with high mortality rates (up to 92%). NiV can cause Acute Lung Injury (ALI) in humans, and human-to-human transmission has been observed in recent outbreaks of NiV. While the exact route of transmission to humans is not known, we have previously shown that NiV can efficiently infect human respiratory epithelial cells. The molecular mechanisms of NiV-associated ALI in the human respiratory tract are unknown. Thus, there is an urgent need for models of henipavirus infection of the human respiratory tract to study the pathogenesis and understand the host responses. Here, we describe a novel human lung xenograft model in mice to study the pathogenesis of NiV. Following transplantation, human fetal lung xenografts rapidly graft and develop mature structures of adult lungs including cartilage, vascular vessels, ciliated pseudostratified columnar epithelium, and primitive “air” spaces filled with mucus and lined by cuboidal to flat epithelium. Following infection, NiV grows to high titers (10⁷ TCID₅₀/gram lung tissue) as early as 3 days post infection (pi). NiV targets both the endothelium as well as respiratory epithelium in the human lung tissues, and results in syncytia formation. NiV infection in the human lung results in the production of several cytokines and chemokines including IL-6, IP-10, eotaxin, G-CSF and GM-CSF on days 5 and 7 pi. In conclusion, this study demonstrates that NiV can replicate to high titers in a novel in vivo model of the human respiratory tract, resulting in a robust inflammatory response, which is known to be associated with ALI. This model will facilitate progress in the fundamental understanding of henipavirus pathogenesis and virus-host interactions; it will also provide biologically relevant models for other respiratory viruses.

Nipah virus (NiV) is a highly pathogenic zoonotic virus that causes fatal disease in humans and a variety of other mammalian hosts including pigs. Given the lack of effective therapeutics and vaccines, this virus is considered a public health and agricultural concern, and listed as category C priority pathogen for biodefense research by the National Institute of Allergy and Infectious Diseases. Both animal-to-human and human-to-human transmission has been observed. Studies on the molecular mechanisms of NiV-mediated pathogenesis have been hampered by the lack of biologically relevant in vivo models for studying the initial host responses to NiV infection in the human lung. We show here a new small animal model in which we transplant human lung tissue for studying the pathogenesis of NiV. We showed that NiV can replicate to high levels in the human lung. NiV causes extensive damage to the lung tissue and induces important regulators of the inflammatory response. This study is the first to use a human lung transplant for studying infectious diseases, a powerful model for studying the pathogenesis of NiV infection, and will open up new possibilities for studying virus-host interactions.

A nonpathogenic duck-origin H9N2 influenza A virus adapts to high pathogenicity in mice

H9N2 influenza viruses continue to circulate in wild birds and poultry in Eurasian countries and have repeatedly infected mammals, including pigs and humans, posing a significant threat to public health. To understand the adaptation of H9N2 influenza viruses to mammals, we serially passaged a nonpathogenic duck-origin H9N2 influenza virus, A/duck/Jiangsu/1/2008 (DK1), in mouse lungs. Increased virulence was detectable after five sequential passages, and a highly pathogenic mouse-adapted strain (DK1-MA) with a 50% mouse lethal dose of 10(2.37) 50% egg infectious dose was obtained after 18 passages. DK1-MA grew faster and reached significantly higher titers than DK1 in mouse lungs and could sporadically spread to other organs. Moreover, DK1-MA induced a greater magnitude of pulmonary edema and higher levels of inflammatory cellular infiltration in bronchoalveolar lavage fluids than DK1 did. Genomic sequence alignment revealed eight amino acid substitutions (HA-L80F, HA-N193D, NA-A27T, PB2-F404L, PA-D3V, PA-S225R, NP-V105M, M1-A166V) in six viral proteins of DK1-MA compared with DK1 virus. Except for HA-L80F, the other seven substitutions were all located in known functional regions involved in interaction of viral proteins or interaction between the virus and host factors. Taken together, our results suggest that multiple amino acid substitutions may be involved in the adaptation of H9N2 avian influenza virus to mice, resulting in lethal infection, enhanced viral replication, severe pulmonary edema, and excessive inflammatory cellular infiltration in lungs. These observations provide helpful insights into the pathogenic potential of H9N2 avian influenza viruses that could pose threats to human health in the future.

Highly pathogenic porcine reproductive and respiratory syndrome virus infection results in acute lung injury of the infected pigs

Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) was firstly characterized in 2006 in China. The virus has caused great economic loss to the Chinese swine production during the past years. Herein, we experimentally infected SPF pigs using two strains of PRRSV with different pathogenicity and observed the lung pathological changes looking for new sights on the possible pathogenesis associated with the virulence of HP-PRRSV. The results indicated that the HP-PRRSV-infected pigs died and exhibited severe pathological changes of lungs featuring increased neutrophils, mast cells and mononuclear macrophages, compared with the pigs inoculated with low pathogenic (LP-) PRRSV. Furthermore, the pigs infected with HP-PRRSV showed the higher levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interleukin (IL)-8 and histamine, leukotriene B4 (LTB4), platelet activation factor (PAF) in sera than those inoculated with LP-PRRSV. Additionally, the fibrosis of lung was observed in the HP-PRRSV-infected pigs. At present, our findings suggest that the aberrant immune responses triggered by HP-PRRSV infection are closely related to acute lung injury (ALI), and especially the pathological changes in lung vascular system are of particular significance. These associated pathological changes of lung are in part responsible for the additional morbidity and mortality observed in HP-PRRSV infection.

CD8+ Treg cells suppress CD8+ T cell-responses by IL-10-dependent mechanism during H5N1 influenza virus infection

Although Treg-cell-mediated suppression during infection or autoimmunity has been described, functions of Treg cells during highly pathogenic avian influenza virus infection remain poorly characterized. Here we found that in Foxp3-GFP transgenic mice, CD8⁺ Foxp3⁺ Treg cells, but not CD4⁺ Foxp3⁺ Treg cells, were remarkably induced during H5N1 infection. In addition to expressing CD25, the CD8⁺ Foxp3⁺ Treg cells showed a high level of GITR and produced IL-10. In an adoptive transfer model, CD8⁺ Treg cells suppressed CD8⁺ T-cell responses and promoted H5N1 virus infection, resulting in enhanced mortality and increased virus load in the lung. Furthermore, in vitro neutralization of IL-10 and studies with IL-10R-deficient mice in vitro and in vivo demonstrated an important role for IL-10 production in the capacity of CD8⁺ Treg cells to inhibit CD8⁺ T-cell responses. Our findings identify a previously unrecognized role of CD8⁺ Treg cells in the negative regulation of CD8⁺ T-cell responses and suggest that modulation of CD8⁺ Treg cells may be a therapeutic strategy to control H5N1 viral infection.

CD4+ T cells recognize unique and conserved 2009 H1N1 influenza hemagglutinin epitopes after natural infection and vaccination

Influenza A/California/4/2009 (H1N1/09) is a recently emerged influenza virus capable of causing serious illness or death in otherwise healthy individuals. Serious outcomes were most common in young adults and children, suggesting that pre-existing heterologous immunity may influence the severity of infection. Using tetramers, we identified CD4(+) T-cell epitopes within H1N1/09 hemagglutinin (HA) that share extensive homology with seasonal influenza and epitopes that are unique to H1N1/09 HA. Ex vivo tetramer staining revealed that T cells specific for conserved epitopes were detectable within the memory compartment, whereas T cells specific for unique epitopes were naive and infrequent prior to infection or vaccination. Following infection, the frequencies of T cells specific for unique epitopes were 11-fold higher, reaching levels comparable to those of T cells specific for immunodominant epitopes. In contrast, the frequencies of T cells specific for conserved epitopes were only 2- to 3-fold higher following infection. In general, H1HA-reactive T cells exhibited a memory phenotype, expressed CXCR3 and secreted IFN-γ, indicating a predominantly Th1-polarized response. A similar Th1 response was seen in vaccinated subjects, but the expansion of T cells specific for HA epitopes was comparatively modest after vaccination. Our findings indicate that CD4(+) T cells recognize both strain-specific and conserved epitopes within the influenza HA protein and suggest that naive T cells specific for HA epitopes undergo significant expansion, whereas memory T cells specific for the conserved epitopes undergo more restrained expansion.

Henipavirus pathogenesis in human respiratory epithelial cells

Hendra virus (HeV) and Nipah virus (NiV) are deadly zoonotic viruses for which no vaccines or therapeutics are licensed for human use. Henipavirus infection causes severe respiratory illness and encephalitis. Although the exact route of transmission in human is unknown, epidemiological studies and in vivo studies suggest that the respiratory tract is important for virus replication. However, the target cells in the respiratory tract are unknown, as are the mechanisms by which henipaviruses can cause disease. In this study, we characterized henipavirus pathogenesis using primary cells derived from the human respiratory tract. The growth kinetics of NiV-Malaysia, NiV-Bangladesh, and HeV were determined in bronchial/tracheal epithelial cells (NHBE) and small airway epithelial cells (SAEC). In addition, host responses to infection were assessed by gene expression analysis and immunoassays. Viruses replicated efficiently in both cell types and induced large syncytia. The host response to henipavirus infection in NHBE and SAEC highlighted a difference in the inflammatory response between HeV and NiV strains as well as intrinsic differences in the ability to mount an inflammatory response between NHBE and SAEC. These responses were highest during HeV infection in SAEC, as characterized by the levels of key cytokines (interleukin 6 [IL-6], IL-8, IL-1α, monocyte chemoattractant protein 1 [MCP-1], and colony-stimulating factors) responsible for immune cell recruitment. Finally, we identified virus strain-dependent variability in type I interferon antagonism in NHBE and SAEC: NiV-Malaysia counteracted this pathway more efficiently than NiV-Bangladesh and HeV. These results provide crucial new information in the understanding of henipavirus pathogenesis in the human respiratory tract at an early stage of infection.

Effect on extrapulmonary sepsis-induced acute lung injury by hemoperfusion with neutral microporous resin column

The aim of this study was to investigate the effect of neutral microporous resin hemoperfusion on oxygenation improvement, removal of inflammatory cytokines in plasma and bronchoalveolar lavage, and mortality in acute lung injury induced by extrapulmonary sepsis. Forty-six patients with acute lung injury induced by extrapulmonary sepsis were randomized to HA type hemoperfusion treatment (N=25) or standard therapy (N=21). Those undergoing hemoperfusion treatment received HA330 hemoperfusion. We measured the plasma and bronchoalveolar lavage concentrations of TNF-α and IL-1, and the following parameters were compared between the control group and the hemoperfusion group on days 0, 3 and 7: lung injury measurements (arterial oxygen tension/fractional inspired oxygen ratio, lung injury score, chest X-ray score); interstitial edema of lung (extravascular lung water). Duration of mechanical ventilation, hospital, 28-day, and intensive care unit mortality were also observed. Patients treated with HA hemoperfusion showed a significant removal of plasma and bronchoalveolar lavage TNF-α and IL-1 over time while in the study. Patients in the HA group also demonstrated not only significant improvement of PaO2 /FiO2 , but also decreased Lung Injury Score and chest X-ray score at days 3 and 7. Furthermore, the measurements of the arterial oxygen tension/fractional inspired oxygen ratio, lung injury score and extravascular lung water (EVLWI) significantly correlated with and the concentration of cytokines in the plasma (all P<0.05). The HA hemoperfusion treatment group had a significant reduction in duration of mechanical ventilation, length of intensive care unit stay, and intensive care unit mortality. Significant removal of inflammatory cytokines from circulation and lung by hemoperfusion treatment using the HA type cartridge may contribute to the improvement of lung injury and intensive care unit outcome in extrapulmonary septic patients.

Regional pulmonary inflammation in an endotoxemic ovine acute lung injury model

The regional distribution of inflammation during acute lung injury (ALI) is not well known. In an ovine ALI model we studied regional alveolar inflammation, surfactant composition, and CT-derived regional specific volume change (sVol) and specific compliance (sC). 18 ventilated adult sheep received IV lipopolysaccharide (LPS) until severe ALI was achieved. Blood and bronchoalveolar lavage (BAL) samples from apical and basal lung regions were obtained at baseline and injury time points, for analysis of cytokines (IL-6, IL-1β), BAL protein and surfactant composition. Whole lung CT images were obtained in 4 additional sheep. BAL protein and IL-1β were significantly higher in injured apical vs. basal regions. No significant regional surfactant composition changes were observed. Baseline sVol and sC were lower in apex vs. base; ALI enhanced this cranio-caudal difference, reaching statistical significance only for sC. This study suggests that apical lung regions show greater inflammation than basal ones during IV LPS-induced ALI which may relate to differences in regional mechanical events.

Interleukin-6 is a potential biomarker for severe pandemic H1N1 influenza A infection

Pandemic H1N1 influenza A (H1N1pdm) is currently a dominant circulating influenza strain worldwide. Severe cases of H1N1pdm infection are characterized by prolonged activation of the immune response, yet the specific role of inflammatory mediators in disease is poorly understood. The inflammatory cytokine IL-6 has been implicated in both seasonal and severe pandemic H1N1 influenza A (H1N1pdm) infection. Here, we investigated the role of IL-6 in severe H1N1pdm infection. We found IL-6 to be an important feature of the host response in both humans and mice infected with H1N1pdm. Elevated levels of IL-6 were associated with severe disease in patients hospitalized with H1N1pdm infection. Notably, serum IL-6 levels associated strongly with the requirement of critical care admission and were predictive of fatal outcome. In C57BL/6J, BALB/cJ, and B6129SF2/J mice, infection with A/Mexico/4108/2009 (H1N1pdm) consistently triggered severe disease and increased IL-6 levels in both lung and serum. Furthermore, in our lethal C57BL/6J mouse model of H1N1pdm infection, global gene expression analysis indicated a pronounced IL-6 associated inflammatory response. Subsequently, we examined disease and outcome in IL-6 deficient mice infected with H1N1pdm. No significant differences in survival, weight loss, viral load, or pathology were observed between IL-6 deficient and wild-type mice following infection. Taken together, our findings suggest IL-6 may be a potential disease severity biomarker, but may not be a suitable therapeutic target in cases of severe H1N1pdm infection due to our mouse data.