Persistent elevation of inflammatory cytokines predicts a poor outcome in ARDS. Plasma IL-1 beta and IL-6 levels are consistent and efficient predictors of outcome over time

The inflammasome potentiates influenza/Staphylococcus aureus superinfection in mice

Secondary bacterial respiratory infections are commonly associated with both acute and chronic lung injury. Influenza complicated by bacterial pneumonia is an effective model to study host defense during pulmonary superinfection due to its clinical relevance. Multiprotein inflammasomes are responsible for IL-1β production in response to infection and drive tissue inflammation. In this study, we examined the role of the inflammasome during viral/bacterial superinfection. We demonstrate that ASC-/- mice are protected from bacterial superinfection and produce sufficient quantities of IL-1β through an apoptosis-associated speck-like protein containing CARD (ASC) inflammasome-independent mechanism. Despite the production of IL-1β by ASC-/- mice in response to bacterial superinfection, these mice display decreased lung inflammation. A neutrophil elastase inhibitor blocked ASC inflammasome-independent production of IL-1β and the IL-1 receptor antagonist, anakinra, confirmed that IL-1 remains crucial to the clearance of bacteria during superinfection. Delayed inhibition of NLRP3 during influenza infection by MCC950 decreases bacterial burden during superinfection and leads to decreased inflammatory cytokine production. Collectively, our results demonstrate that ASC augments the clearance of bacteria, but can also contribute to inflammation and mortality. ASC should be considered as a therapeutic target to decrease morbidity and mortality during bacterial superinfection.

Cigarette Smoke Exposure Worsens Endotoxin-Induced Lung Injury and Pulmonary Edema in Mice

Introduction

Cigarette smoking (CS) remains a major public health concern and has recently been associated with an increased risk of developing acute respiratory distress syndrome (ARDS). Bronchoalveolar lavage (BAL) experiments in human volunteers have demonstrated that active smokers develop increased alveolar-epithelial barrier permeability to protein after inhaling lipopolysaccharide (LPS). Here we tested the hypothesis that short-term whole-body CS exposure would increase LPS-induced lung edema in mice.

Methods

Adult mice were exposed in a Teague TE-10 machine to CS from 3R4F cigarettes at 100 mg/m3 total suspended particulates for 12 days, then given LPS or saline intratracheally. Control mice were housed in the same room without CS exposure. Post-mortem measurements included gravimetric lung water and BAL protein, cell counts, and lung histology. Cytokines were measured in lung homogenate by ELISA and in plasma by Luminex and ELISA.

Results

In CS-exposed mice, intratracheal LPS caused greater increases in pulmonary edema by gravimetric measurement and histologic scoring. CS-exposed mice also had an increase in BAL neutrophilia, lung IL-6, and plasma CXCL9, a T-cell chemoattractant. Intratracheal LPS concentrated blood hemoglobin to a greater degree in CS-exposed mice, consistent with an increase in systemic vascular permeability.

Conclusions

These results demonstrate that CS exposure in endotoxin injured mice increases the severity of acute lung injury. The increased lung IL-6 in CS-exposed LPS-injured mice indicates that this potent cytokine, previously shown to predict mortality in patients with ARDS, may play a role in exacerbating lung injury in smokers and may have utility as a biomarker of tobacco-related lung injury.

Implications

Our results suggest that short-term CS exposure at levels that cause no overt lung injury may still prime the lung for acute inflammatory damage from a "second hit", a finding that mirrors the increased risk of developing ARDS in patients who smoke. This model may be useful for evaluating the acute pulmonary toxicity of existing and/or novel tobacco products and identifying biomarkers of tobacco-related lung injury.

Effect of vitamin C on azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis-associated early colon cancer in mice

BACKGROUND/OBJECTIVES

The objective of this study was to investigate the effects of vitamin C on inflammation, tumor development, and dysbiosis of intestinal microbiota in an azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced inflammation-associated early colon cancer mouse model.

MATERIALS/METHODS

Male BALB/c mice were injected intraperitoneally with AOM [10 mg/kg body weight (b.w)] and given two 7-d cycles of 2% DSS drinking water with a 14 d inter-cycle interval. Vitamin C (60 mg/kg b.w. and 120 mg/kg b.w.) was supplemented by gavage for 5 weeks starting 2 d after the AOM injection.

RESULTS

The vitamin C treatment suppressed inflammatory morbidity, as reflected by disease activity index (DAI) in recovery phase and inhibited shortening of the colon, and reduced histological damage. In addition, vitamin C supplementation suppressed mRNA levels of pro-inflammatory mediators and cytokines, including cyclooxygenase-2, microsomal prostaglandin E synthase-2, tumor necrosis factor-α, Interleukin (IL)-1β, and IL-6, and reduced expression of the proliferation marker, proliferating cell nuclear antigen, compared to observations of AOM/DSS animals. Although the microbial composition did not differ significantly between the groups, administration of vitamin C improved the level of inflammation-related Lactococcus and JQ084893 to control levels.

CONCLUSION

Vitamin C treatment provided moderate suppression of inflammation, proliferation, and certain inflammation-related dysbiosis in a murine model of colitis associated-early colon cancer. These findings support that vitamin C supplementation can benefit colonic health. Long-term clinical studies with various doses of vitamin C are warranted.

Acute exacerbation of idiopathic pulmonary fibrosis: lessons learned from acute respiratory distress syndrome?

Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease characterized by progressive loss of lung function and poor prognosis. The so-called acute exacerbation of IPF (AE-IPF) may lead to severe hypoxemia requiring mechanical ventilation in the intensive care unit (ICU). AE-IPF shares several pathophysiological features with acute respiratory distress syndrome (ARDS), a very severe condition commonly treated in this setting.A review of the literature has been conducted to underline similarities and differences in the management of patients with AE-IPF and ARDS.During AE-IPF, diffuse alveolar damage and massive loss of aeration occurs, similar to what is observed in patients with ARDS. Differently from ARDS, no studies have yet concluded on the optimal ventilatory strategy and management in AE-IPF patients admitted to the ICU. Notwithstanding, a protective ventilation strategy with low tidal volume and low driving pressure could be recommended similarly to ARDS. The beneficial effect of high levels of positive end-expiratory pressure and prone positioning has still to be elucidated in AE-IPF patients, as well as the precise role of other types of respiratory assistance (e.g., extracorporeal membrane oxygenation) or innovative therapies (e.g., polymyxin-B direct hemoperfusion). The use of systemic drugs such as steroids or immunosuppressive agents in AE-IPF is controversial and potentially associated with an increased risk of serious adverse reactions.Common pathophysiological abnormalities and similar clinical needs suggest translating to AE-IPF the lessons learned from the management of ARDS patients. Studies focused on specific therapeutic strategies during AE-IPF are warranted.

Protective Effect of Amygdalin on LPS-Induced Acute Lung Injury by Inhibiting NF-κB and NLRP3 Signaling Pathways

The acute lung injury (ALI) is a leading cause of morbidity and mortality in critically ill patients. Amygdalin is derived from the bitter apricot kernel, an efficacious Chinese herbal medicine. Although amygdalin is used by many cancer patients as an antitumor agent, there is no report about the effect of amygdalin on acute lung injury. Here we explored the protective effect of amygdalin on ALI using lipopolysaccharide (LPS)-induced murine model by detecting the lung wet/dry ratio, the myeloperoxidase (MPO) in lung tissues, inflammatory cells in the bronchoalveolar lavage fluid (BALF), inflammatory cytokines production, as well as NLRP3 and NF-κB signaling pathways. The results showed that amygdalin significantly reduced LPS-induced infiltration of inflammatory cells and the production of TNF-α, IL-1β, and IL-6 in the BALF. The activity of MPO and lung wet/dry ratio were also attenuated by amygdalin. Furthermore, the western blotting analysis showed that amygdalin remarkably inhibited LPS-induced NF-κB and NLRP3 activation. These findings indicate that amygdalin has a protective effect on LPS-induced ALI in mice. The mechanism may be related to the inhibition of NF-κB and NLRP3 signaling pathways.

Temporal Changes in Microrna Expression in Blood Leukocytes from Patients with the Acute Respiratory Distress Syndrome

BACKGROUND

MicroRNA (miRNA) control gene transcription by binding to and repressing the translation of messenger RNA (mRNA). Their role in the acute respiratory distress syndrome (ARDS) is undefined.

METHODS

Blood leukocytes from 51 patients enrolled in a prior randomized trial of corticosteroids for ARDS were analyzed. After screening eight patients with microarrays for altered miRNA expression, 25 miRNAs were selected for further analysis using RT-PCR in all 51 patients.

RESULTS

On day 0, the 51 patients had APACHE III score of 60.4 ± 17.7 and PaO2/FiO2 of 117 ± 49. 21 miRNA were expressed at increased levels in blood leukocytes at the onset of ARDS compared with healthy controls. These miRNA remained elevated at day 3 and increased further by day 7 (log2 fold change from 0.66 to 5.7 fold, P <0.05 compared to day 0). In a subgroup analysis (37 patients treated with corticosteroids and 14 treated with placebo), the interaction of miRNA expression over time and steroid administration was not significant suggesting that systemic corticosteroids had no effect on the miRNA detected in our study. In contrast, corticosteroids but not placebo decreased IL-6 and C-reactive protein at day 3 (P < 0.001) demonstrating an early systemic anti-inflammatory response whereas both treatment arms had decreased values by day 7 (P <0.001).

CONCLUSIONS

Expression of miRNA is increased in blood leukocytes of patients with ARDS at day 0 and day 3 and rises further by day 7, when systemic inflammation is subsiding. These effects appear independent of the administration of steroids, suggesting different inflammatory modifying roles for each in the resolving phases of ARDS.

Nephrogenic acute respiratory distress syndrome: A narrative review on pathophysiology and treatment

The kidneys have a close functional relationship with other organs especially the lungs. This connection makes the kidney and the lungs as the most organs involved in the multi-organ failure syndrome. The combination of acute lung injury (ALI) and renal failure results a great clinical significance of 80% mortality rate. Acute kidney injury (AKI) leads to an increase in circulating cytokines, chemokines, activated innate immune cells and diffuse of these agents to other organs such as the lungs. These factors initiate pathological cascade that ultimately leads to ALI and acute respiratory distress syndrome (ARDS). We comprehensively searched the English medical literature focusing on AKI, ALI, organs cross talk, renal failure, multi organ failure and ARDS using the databases of PubMed, Embase, Scopus and directory of open access journals. In this narrative review, we summarized the pathophysiology and treatment of respiratory distress syndrome following AKI. This review promotes knowledge of the link between kidney and lung with mechanisms, diagnostic biomarkers, and treatment involved ARDS induced by AKI.

Cytokine-Ion Channel Interactions in Pulmonary Inflammation

The lungs conceptually represent a sponge that is interposed in series in the bodies’ systemic circulation to take up oxygen and eliminate carbon dioxide. As such, it matches the huge surface areas of the alveolar epithelium to the pulmonary blood capillaries. The lung’s constant exposure to the exterior necessitates a competent immune system, as evidenced by the association of clinical immunodeficiencies with pulmonary infections. From the in utero to the postnatal and adult situation, there is an inherent vital need to manage alveolar fluid reabsorption, be it postnatally, or in case of hydrostatic or permeability edema. Whereas a wealth of literature exists on the physiological basis of fluid and solute reabsorption by ion channels and water pores, only sparse knowledge is available so far on pathological situations, such as in microbial infection, acute lung injury or acute respiratory distress syndrome, and in the pulmonary reimplantation response in transplanted lungs. The aim of this review is to discuss alveolar liquid clearance in a selection of lung injury models, thereby especially focusing on cytokines and mediators that modulate ion channels. Inflammation is characterized by complex and probably time-dependent co-signaling, interactions between the involved cell types, as well as by cell demise and barrier dysfunction, which may not uniquely determine a clinical picture. This review, therefore, aims to give integrative thoughts and wants to foster the unraveling of unmet needs in future research.

Critical Illness-Related Corticosteroid Insufficiency (CIRCI): A Narrative Review from a Multispecialty Task Force of the Society of Critical Care Medicine (SCCM) and the European Society of Intensive Care Medicine (ESICM)

OBJECTIVE

To provide a narrative review of the latest concepts and understanding of the pathophysiology of critical illness-related corticosteroid insufficiency (CIRCI).

PARTICIPANTS

A multi-specialty task force of international experts in critical care medicine and endocrinology and members of the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

DATA SOURCES

Medline, Database of Abstracts of Reviews of Effects (DARE), Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Database of Systematic Reviews.

RESULTS

Three major pathophysiologic events were considered to constitute CIRCI: dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, altered cortisol metabolism, and tissue resistance to glucocorticoids. The dysregulation of the HPA axis is complex, involving multidirectional crosstalk between the CRH/ACTH pathways, autonomic nervous system, vasopressinergic system, and immune system. Recent studies have demonstrated that plasma clearance of cortisol is markedly reduced during critical illness, explained by suppressed expression and activity of the primary cortisol-metabolizing enzymes in the liver and kidney. Despite the elevated cortisol levels during critical illness, tissue resistance to glucocorticoids is believed to occur due to insufficient glucocorticoid alpha-mediated anti-inflammatory activity.

CONCLUSIONS

Novel insights into the pathophysiology of CIRCI add to the limitations of the current diagnostic tools to identify at-risk patients and may also impact how corticosteroids are used in patients with CIRCI.

Molecular and Immune Biomarkers in Acute Respiratory Distress Syndrome: A Perspective From Members of the Pulmonary Pathology Society

Acute respiratory distress syndrome (ARDS) is a multifactorial syndrome with high morbidity and mortality rates, characterized by deficiency in gas exchange and lung mechanics that lead to hypoxemia, dyspnea, and respiratory failure. Histologically, ARDS is characterized by an acute, exudative phase, combining diffuse alveolar damage and noncardiogenic edema, followed by a later fibroproliferative phase. Despite an enhanced understanding of ARDS pathogenesis, the capacity to predict the development of ARDS and to risk-stratify patients with the disease remains limited. Biomarkers may help to identify patients at the greatest risk of developing ARDS, to evaluate response to therapy, to predict outcome, and to improve clinical trials. The ARDS pathogenesis is presented in this article, as well as concepts and information on biomarkers that are currently used clinically or are available for laboratory use by academic and practicing pathologists and the developing and validating of new assays, focusing on the assays' major biologic roles in lung injury and/or repair and to ultimately suggest innovative, therapeutic approaches.

Automatic regulation of NF-κB by pHSP70/IκBαm to prevent acute lung injury in mice

Controlling target gene expression is a vital step in the procedure of gene therapy upon acute lung injury (ALI). Excessive activation of nuclear factor-kappa B (NF-κB) has been the key point of the inflammation overwhelming process in onset of ALI. We designed and tested a variety of plasmid named pHSP70/IκBαm which conditionally carries a mutant inhibitor of kappa B (IκB) transgene to regulate the activity of NF-κB signaling pathway in its response to an inflammatory stimulus that causes acute lung injury. Results recorded along our experiments showed that pHSP70/IκBαm was able to control mutant IκB expression in RAW264.7 cells with reference to the level of inflammatory response induced by LPS, thereby inhibiting NF-κB activation and downstream inflammatory cytokine expression. Vivo experiments revealed that construction naming pHSP70/IκBαm reduced LPS-induced lung injury and the secretion of inflammatory factors from lungs, hearts, and livers of sample mice in a LPS dose-dependent manner. In conclusion, the promoter heat shocking protein 70(HSP70) regulatory sequence of the construction was shown to drive mutant IκB expression so that its levels were positively associated with the dose of LPS used to induce acute lung injury. NF-κB activation and the downstream expression of inflammatory factors were therefore down-regulated in along an efficient path and ameliorating the damage as a consequence of LPS-induced acute lung injury.

Fifty Years of Research in ARDS. Genomic Contributions and Opportunities

Clinical factors alone poorly explain acute respiratory distress syndrome (ARDS) risk and ARDS outcome. In the search for individual factors that may influence ARDS risk, the past 20 years have witnessed the identification of numerous genes and genetic variants that are associated with ARDS. The field of ARDS genomics has cycled from candidate gene association studies to bias-free approaches that identify new candidates, and increasing effort is made to understand the functional consequences that may underlie significant associations. More recently, methodologies of causal inference are being applied to maximize the information gained from genetic associations. Although challenges of sample size, both recognized and unrecognized phenotypic heterogeneity, and the paucity of early ARDS lung tissue limit some applications of the rapidly evolving field of genomic investigation, ongoing genetic research offers unique contributions to elucidating ARDS pathogenesis and the paradigm of precision ARDS medicine.

Point-of-care washing of allogeneic red blood cells for the prevention of transfusion-related respiratory complications (WAR-PRC): a protocol for a multicenter randomised clinical trial in patients undergoing cardiac surgery

INTRODUCTION

The transfusion-related respiratory complications, transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO), are leading causes of transfusion-related morbidity and mortality. At present, there are no effective preventive strategies with red blood cell (RBC) transfusion. Although mechanisms remain incompletely defined, soluble biological response modifiers (BRMs) within the RBC storage solution may play an important role. Point-of-care (POC) washing of allogeneic RBCs may remove these BRMs, thereby mitigating their impact on post-transfusion respiratory complications.

METHODS AND ANALYSIS

This is a multicenter randomised clinical trial of standard allogeneic versus washed allogeneic RBC transfusion for adult patients undergoing cardiac surgery testing the hypothesis that POC RBC washing is feasible, safe, and efficacious and will reduce recipient immune and physiologic responses associated with transfusion-related respiratory complications. Relevant clinical outcomes will also be assessed. This investigation will enrol 170 patients at two hospitals in the USA. Simon's two-stage design will be used to assess the feasibility of POC RBC washing. The primary safety outcomes will be assessed using Wilcoxon Rank-Sum tests for continuous variables and Pearson chi-square test for categorical variables. Standard mixed modelling practices will be employed to test for changes in biomarkers of lung injury following transfusion. Linear regression will assess relationships between randomised group and post-transfusion physiologic measures.

ETHICS AND DISSEMINATION

Safety oversight will be conducted under the direction of an independent Data and Safety Monitoring Board (DSMB). Approval of the protocol was obtained by the DSMB as well as the institutional review boards at each institution prior to enrolling the first study participant. This study aims to provide important information regarding the feasibility of POC washing of allogeneic RBCs and its potential impact on ameliorating post-transfusion respiratory complications. Additionally, it will inform the feasibility and scientific merit of pursuing a more definitive phase II/III clinical trial.

REGISTRATION

ClinicalTrials.gov registration number is NCT02094118 (Pre-results).

Alternative pre-mRNA splicing of Toll-like receptor signaling components in peripheral blood mononuclear cells from patients with ARDS

A key physiological feature of acute respiratory distress syndrome (ARDS) is inflammation. Toll-like receptor (TLR) signaling is required to combat the infection that underlies many ARDS cases but also contributes to pathological inflammation. Several TLR signaling pathway genes encoding positive effectors of inflammation also produce alternatively spliced mRNAs encoding negative regulators of inflammation. An imbalance between these isoforms could contribute to pathological inflammation and disease severity. To determine whether splicing in TLR pathways is altered in patients with ARDS, we monitored alternative splicing of MyD88 and IRAK1, two genes that function in multiple TLR pathways. The MyD88 and IRAK1 genes produce long proinflammatory mRNAs (MyD88_L and IRAK1) and shorter anti-inflammatory mRNAs (MyD88_S and IRAK1c). We quantified mRNA encoding inflammatory cytokines and MyD88 and IRAK1 isoforms in peripheral blood mononuclear cells (PBMCs) from 104 patients with ARDS and 30 healthy control subjects. We found that MyD88 pre-mRNA splicing is altered in patients with ARDS in a proinflammatory direction. We also observed altered MyD88 isoform levels in a second critically ill patient cohort, suggesting that these changes may not be unique to ARDS. Early in ARDS, PBMC IRAK1c levels were associated with patient survival. Despite the similarities in MyD88 and IRAK1 alternative splicing observed in previous in vitro studies, there were differences in how MyD88 and IRAK1 alternative splicing was altered in patients with ARDS. We conclude that pre-mRNA splicing of TLR signaling genes is altered in patients with ARDS, and further investigation of altered splicing may lead to novel prognostic and therapeutic approaches.

Mechanical versus humoral determinants of brain death-induced lung injury

Background

The mechanisms of brain death (BD)-induced lung injury remain incompletely understood, as uncertainties persist about time-course and relative importance of mechanical and humoral perturbations.

Methods

Brain death was induced by slow intracranial blood infusion in anesthetized pigs after randomization to placebo (n = 11) or to methylprednisolone (n = 8) to inhibit the expression of pro-inflammatory mediators. Pulmonary artery pressure (PAP), wedged PAP (PAWP), pulmonary vascular resistance (PVR) and effective pulmonary capillary pressure (PCP) were measured 1 and 5 hours after Cushing reflex. Lung tissue was sampled to determine gene expressions of cytokines and oxidative stress molecules, and pathologically score lung injury.

Results

Intracranial hypertension caused a transient increase in blood pressure followed, after brain death was diagnosed, by persistent increases in PAP, PCP and the venous component of PVR, while PAWP did not change. Arterial PO₂/fraction of inspired O₂ (PaO₂/FiO₂) decreased. Brain death was associated with an accumulation of neutrophils and an increased apoptotic rate in lung tissue together with increased pro-inflammatory interleukin (IL)-6/IL-10 ratio and increased heme oxygenase(HO)-1 and hypoxia inducible factor(HIF)-1 alpha expression. Blood expressions of IL-6 and IL-1β were also increased. Methylprednisolone pre-treatment was associated with a blunting of increased PCP and PVR venous component, which returned to baseline 5 hours after BD, and partially corrected lung tissue biological perturbations. PaO₂/FiO₂ was inversely correlated to PCP and lung injury score.

Conclusions

Brain death-induced lung injury may be best explained by an initial excessive increase in pulmonary capillary pressure with increased pulmonary venous resistance, and was associated with lung activation of inflammatory apoptotic processes which were partially prevented by methylprednisolone.

Bronchial microdialysis monitoring of inflammatory response in open abdominal aortic aneurysm repair; an observational study

Aortic surgery results in ischemia-reperfusion injury that induces an inflammatory response and frequent complications. The magnitude of the inflammatory response in blood and bronchi may be associated with the risk of immediate complications. The purpose of the study was to evaluate bronchial microdialysis as a continuous monitoring of cytokines in bronchial epithelial lining fluid (ELF) and to determine whether bronchial ELF cytokine levels reflect the ischemia-reperfusion injury and risk for complications during open abdominal aortic aneurysm (AAA) repair. We measured cytokines in venous blood using microdialysis and in serum for comparison. Sixteen patients scheduled for elective open AAA repair were included in a prospective observational study. Microdialysis catheters were introduced into a bronchi and a cubital vein. Eighteen cytokines were measured using a Bio-Plex Magnetic Human Cytokine Panel. Samples were collected before and during cross-clamping of the aorta as well as from 0 to 60 min and from 60 to 120 min of reperfusion. The ELF levels of several cytokines changed significantly during reperfusion. In particular, IL-6 increased more than 10-fold and IL-13 more than 5-fold during ischemia and reperfusion. Also, the venous levels of several inflammatory and anti-inflammatory cytokines increased and exhibited their highest concentration during reperfusion. Both bronchial and venous cytokine levels correlated with duration of the procedure, intensive care days, and preoperative kidney disease. Three patients suffered organ failure as a direct consequence of the procedure, and in these patients the bronchial ELF concentrations of 17 of 18 cytokines differed significantly from patients without such complications. Bronchial microdialysis is suited for continuous monitoring of inflammation during open AAA repair. The bronchial ELF cytokine levels may be useful in predicting immediate complications such as organ failure in patients undergoing vascular surgery.

A Protective Role of Glibenclamide in Inflammation-Associated Injury

Glibenclamide is the most widely used sulfonylurea drug for the treatment of type 2 diabetes mellitus (DM). Recent studies have suggested that glibenclamide reduced adverse neuroinflammation and improved behavioral outcomes following central nervous system (CNS) injury. We reviewed glibenclamide's anti-inflammatory effects: abundant evidences have shown that glibenclamide exerted an anti-inflammatory effect in respiratory, digestive, urological, cardiological, and CNS diseases, as well as in ischemia-reperfusion injury. Glibenclamide might block K_ATP channel, Sur1-Trpm4 channel, and NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome activation, decrease the production of proinflammatory mediators (TNF-α, IL-1β, and reactive oxygen species), and suppress the accumulation of inflammatory cells. Glibenclamide's anti-inflammation warrants further investigation.

Pulmonary arterial hypertension and acute respiratory distress syndrome in a patient with adult-onset stills disease

Adult-onset Still’s disease (AOSD) is an inflammatory disorder characterized by recurrent fevers, arthralgia, leukocytosis, and a salmon-colored rash. Diagnosis is made based on the Yamaguchi criteria. Various cardiac and pulmonary manifestations have been described in association with AOSD, including acute respiratory distress syndrome (ARDS) and pulmonary arterial hypertension (PAH). We describe the first case of both PAH and ARDS in a patient with AOSD who, despite aggressive therapy, declined rapidly and ultimately died. There was concern for pulmonary veno-occlusive disease given the rate of her decompensation, but this was found not to be the case on autopsy. Treatment of AOSD with cardiopulmonary involvement requires rapid identification of AOSD followed by aggressive immunosuppression.

Novel translational approaches to the search for precision therapies for acute respiratory distress syndrome

In the 50 years since acute respiratory distress syndrome (ARDS) was first described, substantial progress has been made in identifying the risk factors for and the pathogenic contributors to the syndrome and in characterising the protein expression patterns in plasma and bronchoalveolar lavage fluid from patients with ARDS. Despite this effort, however, pharmacological options for ARDS remain scarce. Frequently cited reasons for this absence of specific drug therapies include the heterogeneity of patients with ARDS, the potential for a differential response to drugs, and the possibility that the wrong targets have been studied. Advances in applied biomolecular technology and bioinformatics have enabled breakthroughs for other complex traits, such as cardiovascular disease or asthma, particularly when a precision medicine paradigm, wherein a biomarker or gene expression pattern indicates a patient's likelihood of responding to a treatment, has been pursued. In this Review, we consider the biological and analytical techniques that could facilitate a precision medicine approach for ARDS.

Surfactant inhibits ATP-induced release of interleukin-1β via nicotinic acetylcholine receptors

Interleukin (IL)-1β is a potent pro-inflammatory cytokine of innate immunity involved in host defense. High systemic IL-1β levels, however, cause life-threatening inflammatory diseases, including systemic inflammatory response syndrome. In response to various danger signals, the pro-form of IL-1β is synthesized and stays in the cytoplasm unless a second signal, such as extracellular ATP, activates the inflammasome, which enables processing and release of mature IL-1β. As pulmonary surfactant is known for its anti-inflammatory properties, we hypothesize that surfactant inhibits ATP-induced release of IL-1β. Lipopolysaccharide-primed monocytic U937 cells were stimulated with an ATP analog in the presence of natural or synthetic surfactant composed of recombinant surfactant protein (rSP)-C, palmitoylphosphatidylglycerol, and dipalmitoylphosphatidylcholine (DPPC). Both surfactant preparations dose-dependently inhibited IL-1β release from U937 cells. DPPC was the active constituent of surfactant, whereas rSP-C and palmitoylphosphatidylglycerol were inactive. DPPC was also effective in primary mononuclear leukocytes isolated from human blood. Experiments with nicotinic antagonists, siRNA technology, and patch-clamp experiments suggested that stimulation of nicotinic acetylcholine receptors (nAChRs) containing subunit α9 results in a complete inhibition of the ion channel function of ATP receptor, P2X7. In conclusion, the surfactant constituent, DPPC, efficiently inhibits ATP-induced inflammasome activation and maturation of IL-1β in human monocytes by a mechanism involving nAChRs.

Plasma Concentrations of Soluble Suppression of Tumorigenicity-2 and Interleukin-6 Are Predictive of Successful Liberation From Mechanical Ventilation in Patients With the Acute Respiratory Distress Syndrome

OBJECTIVES

Soluble suppression of tumorigenicity-2 and interleukin-6 concentrations have been associated with the inflammatory cascade of acute respiratory distress syndrome. We determined whether soluble suppression of tumorigenicity-2 and interleukin-6 levels can be used as prognostic biomarkers to guide weaning from mechanical ventilation and predict the need for reintubation.

DESIGN, SETTING, AND PATIENTS

We assayed plasma soluble suppression of tumorigenicity-2 (n = 826) concentrations and interleukin-6 (n = 755) concentrations in the Fluid and Catheter Treatment Trial, a multicenter randomized controlled trial of conservative fluid management in acute respiratory distress syndrome. We tested whether soluble suppression of tumorigenicity-2 and interleukin-6 levels were associated with duration of mechanical ventilation, the probability of passing a weaning assessment, and the need for reintubation.

MEASUREMENTS AND MAIN RESULTS

In models adjusted for Acute Physiology and Chronic Health Evaluation score and other relevant variables, patients with higher day 0 and day 3 median soluble suppression of tumorigenicity-2 and interleukin-6 concentrations had decreased probability of extubation over time (day 0 soluble suppression of tumorigenicity-2: hazard ratio, 0.85; 95% CI, 0.72-1.00; p = 0.05; day 0 interleukin-6: hazard ratio, 0.64; 95% CI, 0.54-0.75; p < 0.0001; day 3 soluble suppression of tumorigenicity-2: hazard ratio, 0.64; 95% CI, 0.54-0.75; p < 0.0001; and day 3 interleukin-6: hazard ratio, 0.73; 95% CI, 0.62-0.85; p = 0.0001). Higher biomarker concentrations were also predictive of decreased odds of passing day 3 weaning assessments (soluble suppression of tumorigenicity-2: odds ratio, 0.62: 95% CI, 0.44-0.87; p = 0.006 and interleukin-6: odds ratio, 0.61; 95% CI, 0.43-0.85; p = 0.004) and decreased odds of passing a spontaneous breathing trial (soluble suppression of tumorigenicity-2: odds ratio, 0.45; 95% CI, 0.28-0.71; p = 0.0007 and interleukin-6 univariate analysis only: odds ratio, 0.55; 95% CI, 0.36-0.83; p = 0.005). Finally, higher biomarker levels were significant predictors of the need for reintubation for soluble suppression of tumorigenicity-2 (odds ratio, 3.23; 95% CI, 1.04-10.07; p = 0.04) and for interleukin-6 (odds ratio, 2.58; 95% CI, 1.14-5.84; p = 0.02).

CONCLUSIONS

Higher soluble suppression of tumorigenicity-2 and interleukin-6 concentrations are each associated with worse outcomes during weaning of mechanical ventilation and increased need for reintubation in patients with acute respiratory distress syndrome. Biomarker-directed ventilator management may lead to improved outcomes in weaning of mechanical ventilation in patients with acute respiratory distress syndrome.

Effect of Renin-Angiotensin System Blockage in Patients with Acute Respiratory Distress Syndrome: A Retrospective Case Control Study

Background

Acute respiratory distress syndrome (ARDS) remains a life-threatening disease. Many patients with ARDS do not recover fully, and progress to terminal lung fibrosis. Angiotensin-converting enzyme (ACE) inhibitor is known to modulate the neurohormonal system to reduce inflammation and to prevent tissue fibrosis. However, the role of ACE inhibitor in the lungs is not well understood. We therefore conducted this study to elucidate the effect of renin-angiotensin system (RAS) blockage on the prognosis of patients with ARDS.

Methods

We analyzed medical records of patients who were admitted to the medical intensive care unit (ICU) at a tertiary care hospital from January 2005 to December 2010. ARDS was determined using the Berlin definition. The primary outcome was the mortality rate of ICU. Survival analysis was performed after adjustment using propensity score matching.

Results

A total of 182 patients were included in the study. Thirty-seven patients (20.3%) took ACE inhibitor or angiotensin receptor blocker (ARB) during ICU admission, and 145 (79.7%) did not; both groups showed similar severity scores. In the ICU, mortality was 45.9% in the RAS inhibitor group and 58.6% in the non-RAS inhibitor group (P = 0.166). The RAS inhibitor group required a longer duration of mechanical ventilation (29.5 vs. 19.5, P = 0.013) and longer ICU stay (32.1 vs. 20.2 days, P < 0.001). In survival analysis, the RAS inhibitor group showed better survival rates than the non-RAS group (P < 0.001).

Conclusions

ACE inhibitor or ARB may have beneficial effect on ARDS patients.

Kupffer Cell p38 Mitogen-Activated Protein Kinase Signaling Drives Postburn Hepatic Damage and Pulmonary Inflammation When Alcohol Intoxication Precedes Burn Injury

OBJECTIVES

Clinical and animal studies demonstrate that alcohol intoxication at the time of injury worsens postburn outcome. The purpose of this study was to determine the role and mechanism of Kupffer cell derangement in exacerbating postburn end organ damage in alcohol-exposed mice.

DESIGN

Interventional study.

SETTING

Research Institute.

SUBJECTS

Male C57BL/6 mice.

INTERVENTIONS

Alcohol administered 30 minutes before a 15% scald burn injury. Antecedent Kupffer cell depletion with clodronate liposomes (0.5 mg/kg). p38 mitogen-activated protein kinase inhibition via SB203580 (10 mg/kg).

MEASUREMENTS AND MAIN RESULTS

Kupffer cells were isolated 24 hours after injury and analyzed for p38 activity and interleukin-6 production. Intoxicated burned mice demonstrated a two-fold (p < 0.05) elevation of Kupffer cell p38 activation relative to either insult alone, and this corresponded to a 43% (p < 0.05) increase in interleukin-6 production. Depletion of Kupffer cells attenuated hepatic damage as seen by decreases of 53% (p < 0.05) in serum alanine aminotransferase and 74% (p < 0.05) in hepatic triglycerides, as well as a 77% reduction (p < 0.05) in serum interleukin-6 levels compared to matched controls. This mitigation of hepatic damage was associated with a 54% decrease (p < 0.05) in pulmonary neutrophil infiltration and reduced alveolar wall thickening by 45% (p < 0.05). In vivo p38 inhibition conferred nearly identical hepatic and pulmonary protection after the combined injury as mice depleted of Kupffer cells.

CONCLUSIONS

Intoxication exacerbates postburn hepatic damage through p38-dependent interleukin-6 production in Kupffer cells.

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.

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.

Chromatin Kinases Act on Transcription Factors and Histone Tails in Regulation of Inducible Transcription

The inflammatory response requires coordinated activation of both transcription factors and chromatin to induce transcription for defense against pathogens and environmental insults. We sought to elucidate the connections between inflammatory signaling pathways and chromatin through genomic footprinting of kinase activity and unbiased identification of prominent histone phosphorylation events. We identified H3 serine 28 phosphorylation (H3S28ph) as the principal stimulation-dependent histone modification and observed its enrichment at induced genes in mouse macrophages stimulated with bacterial lipopolysaccharide. Using pharmacological and genetic approaches, we identified mitogen- and stress-activated protein kinases (MSKs) as primary mediators of H3S28ph in macrophages. Cell-free transcription assays demonstrated that H3S28ph directly promotes p300/CBP-dependent transcription. Further, MSKs can activate both signal-responsive transcription factors and the chromatin template with additive effects on transcription. Specific inhibition of MSKs in macrophages selectively reduced transcription of stimulation-induced genes. Our results suggest that MSKs incorporate upstream signaling inputs and control multiple downstream regulators of inducible transcription.

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.

Suppressive oligonucleotides inhibit inflammation in a murine model of mechanical ventilator induced lung injury

BACKGROUND

Mechanical ventilation (MV) is commonly used to improve blood oxygenation in critically ill patients and for general anesthesia. Yet the cyclic mechanical stress induced at even moderate ventilation volume settings [tidal volume (Vt) <10 mL/kg] can injure the lungs and induce an inflammatory response. This work explores the effect of treatment with suppressive oligonucleotides (Sup ODN) in a mouse model of ventilator-induced lung injury (VILI).

METHODS

Balb/cJ mice were mechanically ventilated for 4 h using clinically relevant Vt and a positive end-expiratory pressure of 3 cmH₂O under 2-3% isoflurane anesthesia. Lung tissue and bronchoalveolar lavage fluid were collected to assess lung inflammation and lung function was monitored using a FlexiVent^®.

RESULTS

MV induced significant pulmonary inflammation characterized by the influx and activation of CD11c⁺/F4/80⁺ macrophages and CD11b⁺/Ly6G⁺ polymorphonuclear cells into the lung and bronchoalveolar lavage fluid. The concurrent administration of Sup ODN attenuated pulmonary inflammation as evidenced by reduced cellular influx and production of inflammatory cytokines. Oligonucleotide treatment did not worsen lung function as measured by static compliance or resistance.

CONCLUSIONS

Treatment with Sup ODN reduces the lung injury induced by MV in mice.

Alcohol and lung injury and immunity

Annually, excessive alcohol use accounts for more than $220 billion in economic costs and 80,000 deaths, making excessive alcohol use the third leading lifestyle-related cause of death in the US. Patients with an alcohol-use disorder (AUD) also have an increased susceptibility to respiratory pathogens and lung injury, including a 2-4-fold increased risk of acute respiratory distress syndrome (ARDS). This review investigates some of the potential mechanisms by which alcohol causes lung injury and impairs lung immunity. In intoxicated individuals with burn injuries, activation of the gut-liver axis drives pulmonary inflammation, thereby negatively impacting morbidity and mortality. In the lung, the upper airway is the first checkpoint to fail in microbe clearance during alcohol-induced lung immune dysfunction. Brief and prolonged alcohol exposure drive different post-translational modifications of novel proteins that control cilia function. Proteomic approaches are needed to identify novel alcohol targets and post-translational modifications in airway cilia that are involved in alcohol-dependent signal transduction pathways. When the upper airway fails to clear inhaled pathogens, they enter the alveolar space where they are primarily cleared by alveolar macrophages (AM). With chronic alcohol ingestion, oxidative stress pathways in the AMs are stimulated, thereby impairing AM immune capacity and pathogen clearance. The epidemiology of pneumococcal pneumonia and AUDs is well established, as both increased predisposition and illness severity have been reported. AUD subjects have increased susceptibility to pneumococcal pneumonia infections, which may be due to the pro-inflammatory response of AMs, leading to increased oxidative stress.

The role of stretch-activated ion channels in acute respiratory distress syndrome: finally a new target?

Mechanical ventilation (MV) and oxygen therapy (hyperoxia; HO) comprise the cornerstones of life-saving interventions for patients with acute respiratory distress syndrome (ARDS). Unfortunately, the side effects of MV and HO include exacerbation of lung injury by barotrauma, volutrauma, and propagation of lung inflammation. Despite significant improvements in ventilator technologies and a heightened awareness of oxygen toxicity, besides low tidal volume ventilation few if any medical interventions have improved ARDS outcomes over the past two decades. We are lacking a comprehensive understanding of mechanotransduction processes in the healthy lung and know little about the interactions between simultaneously activated stretch-, HO-, and cytokine-induced signaling cascades in ARDS. Nevertheless, as we are unraveling these mechanisms we are gathering increasing evidence for the importance of stretch-activated ion channels (SACs) in the activation of lung-resident and inflammatory cells. In addition to the discovery of new SAC families in the lung, e.g., two-pore domain potassium channels, we are increasingly assigning mechanosensing properties to already known Na(+), Ca(2+), K(+), and Cl(-) channels. Better insights into the mechanotransduction mechanisms of SACs will improve our understanding of the pathways leading to ventilator-induced lung injury and lead to much needed novel therapeutic approaches against ARDS by specifically targeting SACs. This review 1) summarizes the reasons why the time has come to seriously consider SACs as new therapeutic targets against ARDS, 2) critically analyzes the physiological and experimental factors that currently limit our knowledge about SACs, and 3) outlines the most important questions future research studies need to address.

Tsr Chemoreceptor Interacts With IL-8 Provoking E. coli Transmigration Across Human Lung Epithelial Cells

Bacterial colonization of epithelial surfaces and subsequent transmigration across the mucosal barrier are essential for the development of infection. We hypothesized that the methyl-accepting proteins (MCPs), known as chemoreceptors expressed on Escherichia coli (E. coli) bacterial surface, play an important role in mediating bacterial transmigration. We demonstrated a direct interaction between human interleukin-8 (IL-8) and Tsr receptor, a major MCP chemoreceptor. Stimulation of human lung epithelial cell monolayer with IL-8 resulted in increased E. coli adhesion and transmigration of the native strain (RP437) and a strain expressing only Tsr (UU2373), as compared to a strain (UU2599) with Tsr truncation. The augmented E. coli adhesion and migration was associated with a higher expression of carcinoembryonic antigen-related cell adhesion molecule 6 and production of inflammatory cytokines/chemokines, and a lower expression of the tight junction protein claudin-1 and the plasma membrane protein caveolin-1 in lung epithelial cells. An increased E. coli colonization and pulmonary cytokine production induced by the RP437 and UU2373 strains was attenuated in mice challenged with the UU2599 strain. Our results suggest a critical role of the E. coli Tsr chemoreceptor in mediating bacterial colonization and transmigration across human lung epithelium during development of pulmonary infections.

Neutrophil-Related Inflammatory Mediators in Septic Acute Respiratory Distress Syndrome

To disclose the participation of neutrophils in septic acute respiratory distress syndrome (ARDS), characteristics of various inflammatory mediators were examined in septic patients. Forty-seven gram-negative septic patients were divided into ARDS (n = 23) and non-ARDS (n = 24) groups at the transferred point to the intensive care unit. The mediators were measured simultaneously at the transferred point, and then subsequently on days 1, 3, and 5. At the transferred point, the ARDS group showed significantly higher levels of interleukin-8 (IL-8), macrophage inflammatory peptide-1-alpha (MIP-1-α), soluble intercellular adhesion molecule-1 (sICAM-1), and neutrophil elas-tase despite lower neutrophil counts compared to the non-ARDS group. The ARDS group sustained significantly higher levels of sICAM-1 until day 5 and neutrophil elas-tase until day 1 compare to the non-ARDS group. Furthermore, nonsurviving ARDS patients (n = 8) showed significantly higher levels of tumor necrosis factor-alpha, IL-6, IL-8, and IL-10 compared to surviving ARDS patients (n = 15) at the transferred point. In conclusion, neutrophil-related inflammatory mediators, IL-8, MIP-1-α, sICAM-1, and neutrophil elastase, appear to possibly participate in septic ARDS. Cytokines might also play an important role in the mortality of such cases.

The role of steroids following major trauma

This article reviews the indications and evidence for the administration of steroids to patients who have suffered significant trauma. Uncontroversial indications are rare. In spinal cord injury steroids are often given but the practical benefits are questionable. The case for treatment in head injury is unproven. Consideration should be given to treating all those patients who develop acute respiratory distress syndrome (ARDS), although treatment should be deferred to the later (fibroproliferative) stages. The role of steroids in sepsis is complicated and, although steroid administration can have dramatic effects on vasopressor requirements, convincing evidence for mortality reduction is not available.

Aetiology, outcomes & predictors of mortality in acute respiratory distress syndrome from a tertiary care centre in north India

BACKGROUND & OBJECTIVES

Acute respiratory distress syndrome (ARDS) is a common disorder in critically ill patients and is associated with high mortality. There is a paucity of literature on this condition from developing countries. This prospective observational study was designed to find out the aetiology, outcomes and predictors of mortality in ARDS.

METHODS

Sixty four consecutive patients who satisfied American-European Consensus Conference (AECC) definition of ARDS from medical Intensive Care Unit (ICU) of a tertiary care centre in New Delhi, India, were enrolled in the study. Demographic, biochemical and ventilatory variables were recorded for each patient. Baseline measurements of serum interleukin (IL)-1β, IL-6, tumour necrosis factor-alpha (TNF-α), procalcitonin (PCT) and high sensitivity C-reactive protein (hsCRP) were performed.

RESULTS

Common causes of ARDS included pneumonia [44/64 (68.7%)], malaria [9/64 (14.1%)] and sepsis [8/64 (12.5%]. Eight of the 64 (12.5%) patients had ARDS due to viral pneumonia. The 28-day mortality was 36/64 (56.2%).Independent predictors of mortality included non-pulmonary organ failure, [Hazard ratio (HR) 7.65; 95% CI 0.98-59.7, P=0.05], Simplified Acute Physiology Score (SAPS-II) [HR 2.36; 95% CI 1.14-4.85, P=0.02] and peak pressure (P peak ) [HR 1.13; 95% CI 1.00-1.30, P = 0.04] at admission.

INTERPRETATION & CONCLUSIONS

Bacterial and viral pneumonia, malaria and tuberculosis resulted in ARDS in a considerable number of patients. Independent predictors of mortality included non-pulmonary organ failure, SAPS II score and P peak at baseline. Elevated levels of biomarkers such as TNF-α, PCT and hsCRP at admission might help in identifying patients at a higher risk of mortality.

Proteomic study of acute respiratory distress syndrome: current knowledge and implications for drug development

The acute respiratory distress syndrome (ARDS) is a common cause of acute respiratory failure, and is associated with substantial mortality and morbidity. Dozens of clinical trials targeting ARDS have failed, with no drug specifically targeting lung injury in widespread clinical use. Thus, the need for drug development in ARDS is great. Targeted proteomic studies in ARDS have identified many key pathways in the disease, including inflammation, epithelial injury, endothelial injury or activation, and disordered coagulation and repair. Recent studies reveal the potential for proteomic changes to identify novel subphenotypes of ARDS patients who may be most likely to respond to therapy and could thus be targeted for enrollment in clinical trials. Nontargeted studies of proteomics in ARDS are just beginning and have the potential to identify novel drug targets and key pathways in the disease. Proteomics will play an important role in phenotyping of patients and developing novel therapies for ARDS in the future.

Enhanced resolution of experimental ARDS through IL-4-mediated lung macrophage reprogramming

Despite intense investigation, acute respiratory distress syndrome (ARDS) remains an enormous clinical problem for which no specific therapies currently exist. In this study, we used intratracheal lipopolysaccharide or Pseudomonas bacteria administration to model experimental acute lung injury (ALI) and to further understand mediators of the resolution phase of ARDS. Recent work demonstrates macrophages transition from a predominant proinflammatory M1 phenotype during acute inflammation to an anti-inflammatory M2 phenotype with ALI resolution. We tested the hypothesis that IL-4, a potent inducer of M2-specific protein expression, would accelerate ALI resolution and lung repair through reprogramming of endogenous inflammatory macrophages. In fact, IL-4 treatment was found to offer dramatic benefits following delayed administration to mice subjected to experimental ALI, including increased survival, accelerated resolution of lung injury, and improved lung function. Expression of the M2 proteins Arg1, FIZZ1, and Ym1 was increased in lung tissues following IL-4 treatment, and among macrophages, FIZZ1 was most prominently upregulated in the interstitial subpopulation. A similar trend was observed for the expression of macrophage mannose receptor (MMR) and Dectin-1 on the surface of alveolar macrophages following IL-4 administration. Macrophage depletion or STAT6 deficiency abrogated the therapeutic effect of IL-4. Collectively, these data demonstrate that IL-4-mediated therapeutic macrophage reprogramming can accelerate resolution and lung repair despite delayed use following experimental ALI. IL-4 or other therapies that target late-phase, proresolution pathways may hold promise for the treatment of human ARDS.

Regulation of inflammasomes by ubiquitination

Inflammasomes are multi-protein complexes that regulate the innate immune response by facilitating the release of inflammatory cytokines in response to pathogen exposure or cellular damage. Pro-inflammatory inflammasome signaling is vital to host defense and helps initiate the process of tissue repair following an insult to the host, but can be injurious, when excessive or chronic. As such, inflammasome activity is tightly regulated. Here we discuss one critical mechanism of inflammasome regulation, ubiquitination, that functions as a universal modulator of protein stability and trafficking. Recent studies have provided important insights into the regulation of inflammasome activation by protein ubiquitination. We review the molecular regulation of inflammasome function, specifically, as it relates to ubiquitination, and discuss the implications for the development of therapeutics to specifically target aberrant inflammasome signaling.

Neonatal Type II Alveolar Epithelial Cell Transplant Facilitates Lung Reparation in Piglets With Acute Lung Injury and Extracorporeal Life Support

OBJECTIVES

Type II alveolar epithelial cells have potential for lung growth and reparation. Extracorporeal membrane oxygenation is used as life support for lung impairment resulting from acute respiratory distress syndrome. We hypothesized that intratracheal transplantation of isogeneic primary type II alveolar epithelial cells in combination with extracorporeal membrane oxygenation may facilitate lung reparation for acute lung injury (ALI).

DESIGN

A randomized, controlled experiment.

SETTING

An animal laboratory in a university pediatric center.

SUBJECTS

Twenty-eight 4- to 6-week young piglets, weighing 7-8 kg.

INTERVENTIONS

Type II alveolar epithelial cells from neonatal male piglet lungs were isolated, purified, cultured, and labeled with chemical stain PKH26. After 3-6 hours of induction of ALI by IV endotoxin and mechanical ventilation (MV), young female piglets were allocated to five groups (n = 5): ALI-MV, ALI treated with MV; ALI-EC, ALI treated with both MV and venovenous extracorporeal membrane oxygenation; ALI-EC-T, ALI-EC protocol plus intratracheal type II alveolar epithelial cell transplant; CON-MV, healthy animals treated with MV; and CON-EC-T, healthy animals treated with venovenous extracorporeal membrane oxygenation. After 24 hours, animals were weaned from treatment for recovery in the ensuing 14 days, with their lungs assessed for injury and reparation.

MEASUREMENTS AND MAIN RESULTS

Lung injury for animals in ALI-MV was moderate to severe, whereas much milder injuries in ALI-EC-T and ALI-EC were found. More PKH26-labeled type II alveolar epithelial cells were detected by fluorescence in the lungs of ALI-EC-T than in CON-EC-T as further verified by the expression of messenger RNA of sex-determining region of Y chromosome. Electromicroscopically intact type II alveolar epithelial cells and prominent lattice-like tubular myelin were also found in ALI-EC-T and CON-MV but not in ALI-EC. The hydroxyproline level in lung tissue was significantly lower in ALI-EC-T than in ALI-EC and ALI-MV, with most of the lung histopathologic and pathobiologic manifestations in favor of ALI-EC-T.

CONCLUSIONS

The preliminary data suggested that type II alveolar epithelial cell transplant facilitated lung reparation for ALI in this model.

Diagnostic workup for ARDS patients

Acute respiratory distress syndrome (ARDS) is defined by the association of bilateral infiltrates and hypoxaemia following an initial insult. Although a new definition has been recently proposed (Berlin definition), there are various forms of ARDS with potential differences regarding their management (ventilator settings, prone positioning use, corticosteroids). ARDS can be caused by various aetiologies, and the adequate treatment of the responsible cause is crucial to improve the outcome. It is of paramount importance to characterize the mechanisms causing lung injury to optimize both the aetiological treatment and the symptomatic treatment. If there is no obvious cause of ARDS or if a direct lung injury is suspected, bronchoalveolar lavage (BAL) should be strongly considered to identify microorganisms responsible for pneumonia. Blood samples can also help to identify microorganisms and to evaluate biomarkers of infection. If there is no infectious cause of ARDS or no other apparent aetiology is found, second-line examinations should include markers of immunologic diseases. In selected cases, open lung biopsy remains useful to identify the cause of ARDS when all other examinations remain inconclusive. CT scan is fundamental when there is a suspicion of intra-abdominal sepsis and in some cases of pneumonia. Ultrasonography is important not only in evaluating biventricular function but also in identifying pleural effusions and pneumothorax. The definition of ARDS remains clinical and the main objective of the diagnostic workup should be to be focused on identification of its aetiology, especially a treatable infection.

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.

Gprc5a-deficiency confers susceptibility to endotoxin-induced acute lung injury via NF-κB pathway

Susceptibility to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) varies greatly among patients in sepsis/septic shock. The genetic and biochemical reasons for the difference are not fully understood. G protein coupled receptor family C group 5 member A (GPRC5A), a retinoic acid target gene, is predominately expressed in the bronchioalveolar epithelium of lung. We hypothesized that Gprc5a is important in controlling the susceptibility to ALI or ARDS. In this study, we examined the susceptibility of wild-type and Gprc5a-knockout (ko) mice to induced ALI. Administration of endotoxin LPS induced an increased pulmonary edema and injury in Gprc5a-ko mice, compared to wild-type counterparts. Consistently, LPS administration induced higher levels of inflammatory cytokines (IL-1β and TNFα) and chemokine (KC) in Gprc5a-ko mouse lungs than in wild-type. The enhanced pulmonary inflammatory responses were associated with dysregulated NF-κB signaling in the bronchioalveolar epithelium of Gprc5a-ko mouse lungs. Importantly, selective inhibition of NF-κB through expression of the super-repressor IκBα in the bronchioalveolar epithelium of Gprc5a-ko mouse lungs alleviated the LPS-induced pulmonary injury, and inflammatory response. Thus, Gprc5a is critical for lung homeostasis, and Gprc5a deficiency confers the susceptibility to endotoxin-induced pulmonary edema and injury, mainly through NF-κB signaling in bronchioalveolar epithelium of lung.

A Pathophysiologic Approach to Biomarkers in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is an acute-onset hypoxic condition with radiographic bilateral lung infiltration. It is characterized by an acute exudative phase combining diffuse alveolar damage and lung edema followed by a later fibroproliferative phase. Despite an improved understanding of ARDS pathobiology, our ability to predict the development of ARDS and risk-stratify patients with the disease remains limited. Biomarkers may help to identify patients at the highest risk of developing ARDS, assess response to therapy, predict outcome, and optimize enrollment in clinical trials. After a short description of ARDS pathobiology, here, we review the scientific evidence that supports the value of various ARDS biomarkers with regard to their major biological roles in ARDS-associated lung injury and/or repair. Ongoing research aims at identifying and characterizing novel biomarkers, in order to highlight relevant mechanistic explorations of lung injury and repair, and to ultimately develop innovative therapeutic approaches for ARDS patients. This review will focus on the pathophysiologic, diagnostic, and therapeutic implications of biomarkers in ARDS and on their utility to ultimately improve patient care.

Pseudomonas aeruginosa lectin LecB inhibits tissue repair processes by triggering β-catenin degradation

Pseudomonas aeruginosa is an opportunistic pathogen that induces severe lung infections such as ventilator-associated pneumonia and acute lung injury. Under these conditions, the bacterium diminishes epithelial integrity and inhibits tissue repair mechanisms, leading to persistent infections. Understanding the involved bacterial virulence factors and their mode of action is essential for the development of new therapeutic approaches. In our study we discovered a so far unknown effect of the P. aeruginosa lectin LecB on host cell physiology. LecB alone was sufficient to attenuate migration and proliferation of human lung epithelial cells and to induce transcriptional activity of NF-κB. These effects are characteristic of impaired tissue repair. Moreover, we found a strong degradation of β-catenin, which was partially recovered by the proteasome inhibitor lactacystin. In addition, LecB induced loss of cell-cell contacts and reduced expression of the β-catenin targets c-myc and cyclin D1. Blocking of LecB binding to host cell plasma membrane receptors by soluble l-fucose prevented these changes in host cell behavior and signaling, and thereby provides a powerful strategy to suppress LecB function. Our findings suggest that P. aeruginosa employs LecB as a virulence factor to induce β-catenin degradation, which then represses processes that are directly linked to tissue recovery.

Chronic critical illness: the price of survival

BACKGROUND

The evolution of the techniques used in the intensive care setting over the past decades has led on one side to better survival rates in patients with acute conditions and severely impaired vital functions. On the other side, it has resulted in a growing number of patients who survive an acute event, but who then become dependent on one or more life support techniques. Such patients are called chronically critically ill patients.

MATERIALS & METHODS

No absolute definition of the disease is currently available, although most patients are characterized by the need for prolonged mechanical ventilation. Mortality rates are still high even after dismissal from intensive care unit (ICU) and transfer to specialized rehabilitation care settings.

RESULTS

In recent years, some studies have tried to clarify the pathophysiological characteristics underlying chronic critical illness (CCI), a disease that is also characterized by severe endocrine and inflammatory impairments, partly accounting for the almost constant set of symptoms.

DISCUSSION

Currently, no specific treatment is available. However, a strategic early therapeutic approach on ICU admission might try to prevent the progress of the acute disease towards chronic critical illness.