Serum biomarkers in acute respiratory distress syndrome an ailing prognosticator

Pulmonary surfactants and the respiratory-renal connection in steroid-sensitive nephrotic syndrome of childhood

Steroid-sensitive nephrotic syndrome (SSNS) in childhood is usually due to minimal change disease (MCD). Unlike many glomerular conditions, SSNS/MCD is commonly precipitated by respiratory infections. Of interest, pulmonary inflammation releases surfactants in circulation which are soluble agonists of SIRPα, a podocyte receptor that regulates integrin signaling. Here, we characterized this pulmonary-renal connection in MCD and performed studies to determine its importance. Children with SSNS/MCD in relapse but not remission had elevated plasma surfactants and urinary SIRPα. Sera from relapsing subjects triggered podocyte SIRPα signaling via tyrosine phosphatase SHP-2 and nephrin dephosphorylation, a marker of podocyte activation. Further, addition of surfactants to MCD sera from patients in remission replicated these findings. Similarly, nasal instillation of toll-like receptor 3 and 4 agonists in mice resulted in elevated serum surfactants and their binding to glomeruli triggering proteinuria. Together, our data document a critical pulmonary-podocyte signaling pathway involving surfactants and SIRPα signaling in SSNS/MCD.

A Potential Role of the Renin-Angiotensin-System for Disturbances of Respiratory Chemosensitivity in Acute Respiratory Distress Syndrome and Severe Acute Respiratory Syndrome

Acute respiratory distress syndrome (ARDS) represents an acute diffuse inflammation of the lungs triggered by different causes, uniformly leading to a noncardiogenic pulmonary edema with inhomogeneous densities in lung X-ray and lung CT scan and acute hypoxemia. Edema formation results in "heavy" lungs, inducing loss of compliance and the need to spend more energy to "move" the lungs. Consequently, an ARDS patient, as long as the patient is breathing spontaneously, has an increased respiratory drive to ensure adequate oxygenation and CO2 removal. One would expect that, once the blood gases get back to "physiological" values, the respiratory drive would normalize and the breathing effort return to its initial status. However, in many ARDS patients, this is not the case; their respiratory drive appears to be upregulated and fully or at least partially detached from the blood gas status. Strikingly, similar alteration of the respiratory drive can be seen in patients suffering from SARS, especially SARS-Covid-19. We hypothesize that alterations of the renin-angiotensin-system (RAS) related to the pathophysiology of ARDS and SARS are involved in this dysregulation of chemosensitive control of breathing.

An NMR based panorama of the heterogeneous biology of acute respiratory distress syndrome (ARDS) from the standpoint of metabolic biomarkers

Acute respiratory distress syndrome (ARDS), manifested by intricate etiology and pathophysiology, demands careful clinical surveillance due to its high mortality and imminent life support measures. NMR based metabolomics provides an approach for ARDS which culminates from a wide spectrum of illness thereby confounding early manifestation and prognosis predictors. ¹ H NMR with its manifold applications in critical disease settings can unravel the biomarker of ARDS thus holding potent implications by providing surrogate endpoints of clinical utility. NMR metabolomics which is the current apogee platform of omics trilogy is contributing towards the possible panacea of ARDS by subsequent validation of biomarker credential on larger datasets. In the present review, the physiological derangements that jeopardize the whole metabolic functioning in ARDS are exploited and the biomarkers involved in progression are addressed and substantiated. The following sections of the review also outline the clinical spectrum of ARDS from the standpoint of NMR based metabolomics which is an emerging element of systems biology. ARDS is the main premise of intensivists textbook, which has been thoroughly reviewed along with its incidence, progressive stages of severity, new proposed diagnostic definition, and the preventive measures and the current pitfalls of clinical management. The advent of new therapies, the need for biomarkers, the methodology and the contemporary promising approaches needed to improve survival and address heterogeneity have also been evaluated. The review has been stepwise illustrated with potent biometrics employed to selectively pool out differential metabolites as diagnostic markers and outcome predictors. The following sections have been drafted with an objective to better understand ARDS mechanisms with predictive and precise biomarkers detected so far on the basis of underlying physiological parameters having close proximity to diseased phenotype. The aim of this review is to stimulate interest in conducting more studies to help resolve the complex heterogeneity of ARDS with biomarkers of clinical utility and relevance.

Distinct Metabolic Endotype Mirroring Acute Respiratory Distress Syndrome (ARDS) Subphenotype and its Heterogeneous Biology

Predisposing aetiologies in Acute Respiratory Distress Syndrome (ARDS), perpetuates to heterogeneous clinical course hampering therapeutic response. Therefore, physiological variables need to be identified by stratifying ARDS subphenotypes and endotype, to target ARDS heterogeneity. The present study is stimulated by the fact that the ARDS heterogeneity arises from diverse pathophysiological changes leading to distinct ARDS endotypes characterized by perturbed biological mechanism which can be exploited in terms of metabolic profile by metabolomics. Biological endotypes using (n = 464 patients and controls), mBALF and serum samples were identified by high - resolution NMR spectroscopy from two clinically diagnosed ARDS subtypes grouped under mild, moderate and severe ARDS as subphenotype1and pulmonary and extra - pulmonary ARDS as subphenotype2. The identified mBALF endotypes (isoleucine, leucine, valine, lysine/arginine, tyrosine, threonine) and serum endotypes (proline, glutamate, phenylalanine, valine) in both subphenotypes by statistical analysis were tested for their reproducibility and robustness. By combining metabolic endotypes with clinical based mortality score (APACHE and SOFA) added to their predictive performance as ARDS mortality predictors. Thus, a comprehensive set of mBALF endotypes representing compartmentalized lung milieu and serological endotypes representing systemic markers of ARDS subtypes were validated. The interlinked biological pathway of these disease specific endotype further elucidated their role as candidate biomarker in governing ARDS heterogeneous biology.

Transplantation of Endothelial Progenitor Cells Attenuates Lipopolysaccharide-Induced Lung Injury via Inhibiting the Inflammatory Secretion of Neutrophils in Rats

BACKGROUND

Endothelial progenitor cells (EPCs) are special types of stem cells and are a potential novel therapeutic approach in acute lung injury (ALI). Transplantation of EPCs can ameliorate the inflammatory state by reducing adhesion and exudation of inflammatory cells. However, the mechanism underlying the effect of EPCs on inflammatory response modulation remains unclear. The aim of the present study was to investigate the effect of EPCs on the modulation of neutrophils in vitro and in vivo.

MATERIALS AND METHODS

EPCs were cocultured with neutrophils after lipopolysaccharide stimulation in vitro or transplanted into ALI rats, and neutrophil inflammatory mediators including tumor necrosis factor-α, interleukin-1β, neutrophil elastase, myeloperoxidase and matrix metalloproteinases-9 were detected by enzyme-linked immunosorbent assay, an myeloperoxidase detection kits, reverse transcription-polymerase chain reaction and western blotting.

RESULTS

The results showed that EPCs significantly downregulated the expression of inflammatory mediators when cocultured with neutrophils in vitro or in vivo.

CONCLUSIONS

These findings demonstrated that EPCs contributed to lung injury in ALI rats by downregulating neutrophil inflammatory mediators.

Safety and efficacy of nintedanib in idiopathic pulmonary fibrosis: A real-life observational study in Greece

BACKGROUND

Nintedanib represents an antifibrotic compound able to slow down disease progression of patients with idiopathic pulmonary fibrosis (IPF).

OBJECTIVE

To investigate the safety and efficacy of nintedanib in patients with IPF in a real-life setting.

METHODS

This was a multicentre, retrospective, observational, real-life study for patients with IPF receiving nintedanib between October 2014 and October 2016.

RESULTS

We identified 94 patients with IPF receiving nintedanib (72 males, mean age±SD: 73.8 ± 7.5, mean%FVC±SD = 68.1 ± 18.3, mean%DLCo±SD = 44.4 ± 14.5). Diarrhea (n = 52, 55.3%) was the most commonly reported adverse event. Twenty patients (21.2%) had to permanently discontinue nintedanib due to severe adverse events. In the 6-months follow-up, median decline in %FVC predicted and %DLCO predicted were 1.36 (95%Cl: 0 to 2.97) and 4.00 (95%Cl: 2.01 to 6.20), respectively, when deaths were censored and excluded from the analysis. At 12 months, mean%FVC±SD and mean%DLCo±SD were 64.5 ± 19.1 and 43.7 ± 15.4, respectively. With regards to mortality, 17 patients (18.1%) died over a study period of 730 days.

CONCLUSION

Nintedanib demonstrated an acceptable safety and efficacy profile in our real-world observational study. Prospective observational studies in the context of registries that collect well-defined supporting data over time are sorely needed to answer residual questions on drug's performance.

Lethal acute lung injury and hypoglycemia after subcutaneous administration of monochloroacetic acid

Hypoglycemia is suspected in the acute lethal toxicity induced by cutaneous exposure to monochloroacetic acid (MCA). Although it has been shown that hepato-renal dysfunction is involved, the mechanism and the target organs that directly affect mortality remain to be determined. We suspected respiratory failure as a main cause of death in some reported cases. We investigated dose-response effects, hypoglycemia, and lung injury in rats exposed to MCA. Serum glucose, blood gases, and parameters of alveolar injury in bronchoalveolar lavage fluid (BALF) were analysed 2 and 4 h after subcutaneous administration of MCA (108, 135 or 163 mg/kg). Apparent pulmonary injury and hypoglycemia were not identified 2 h after administration, but lactate dehydrogenase (LDH) and total cells in BALF were dose-dependently increased; and severe hypoglycemia was identified 4 h after administration. Blood gas analysis showed remarkable alveolar gas dysfunction as exchange in the 163 mg/kg group. Thus, hypoglycemia and lung injury appear to cause death in response to MCA exposure.

Administration of microparticles from blood of the lipopolysaccharide-treated rats serves to induce pathologic changes of acute respiratory distress syndrome

This study was conducted to investigate the effect of intratracheal and intravenous administration of microparticles (MPs) on developing acute respiratory distress syndrome (ARDS). The blood MPs from lipopolysaccharide-treated rats were collected and examined by transmission electron microscopy (TEM). Cellular source of the MPs was identified by fluorescent-labeled antibodies after the circulating MPs were delivered to naïve rats. Levels of myeloperoxidase (MPO), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-10 productions in bronchoalveolar lavage fluid (BALF) and plasma were determined 24 h after the rats received intratracheal and intravenous administration of the MPs. Histopathologic examination of lungs was performed by light microscope. A TEM image of MPs showed spherical particles at a variable diameter from 0.1 to 0.5 µm. Endothelial- and leukocyte-derived vesicles were abundant in the investigated samples. Treatment with MPs may lead to significant increases in MPO, TNF-α, IL-1β, and IL-10 productions in BALF and plasma of the rats (all P < 0.001). Morphological observation indicated that alveolar structures were destroyed with a large amount of neutrophil infiltration in the lungs of the MP-treated rats. Perivascular and/or intra-alveolar hemorrhage were serious and hyaline membrane formed in the alveoli. Intratracheal and intravenous approaches to delivery of the circulating MPs to naïve recipient rats may induce ARDS. This presents an inducer of the onset of ARDS and provides potential therapeutic targets for attenuating lung injury.

Identification of novel single nucleotide polymorphisms associated with acute respiratory distress syndrome by exome-seq

Acute respiratory distress syndrome (ARDS) is a lung condition characterized by impaired gas exchange with systemic release of inflammatory mediators, causing pulmonary inflammation, vascular leak and hypoxemia. Existing biomarkers have limited effectiveness as diagnostic and therapeutic targets. To identify disease-associating variants in ARDS patients, whole-exome sequencing was performed on 96 ARDS patients, detecting 1,382,399 SNPs. By comparing these exome data to those of the 1000 Genomes Project, we identified a number of single nucleotide polymorphisms (SNP) which are potentially associated with ARDS. 50,190SNPs were found in all case subgroups and controls, of which89 SNPs were associated with susceptibility. We validated three SNPs (rs78142040, rs9605146 and rs3848719) in additional ARDS patients to substantiate their associations with susceptibility, severity and outcome of ARDS. rs78142040 (C>T) occurs within a histone mark (intron 6) of the Arylsulfatase D gene. rs9605146 (G>A) causes a deleterious coding change (proline to leucine) in the XK, Kell blood group complex subunit-related family, member 3 gene. rs3848719 (G>A) is a synonymous SNP in the Zinc-Finger/Leucine-Zipper Co-Transducer NIF1 gene. rs78142040, rs9605146, and rs3848719 are associated significantly with susceptibility to ARDS. rs3848719 is associated with APACHE II score quartile. rs78142040 is associated with 60-day mortality in the overall ARDS patient population. Exome-seq is a powerful tool to identify potential new biomarkers for ARDS. We selectively validated three SNPs which have not been previously associated with ARDS and represent potential new genetic biomarkers for ARDS. Additional validation in larger patient populations and further exploration of underlying molecular mechanisms are warranted.

Extracorporeal carbon dioxide removal for patients with acute respiratory failure secondary to the acute respiratory distress syndrome: a systematic review

Acute respiratory distress syndrome (ARDS) continues to have significant mortality and morbidity. The only intervention proven to reduce mortality is the use of lung-protective mechanical ventilation strategies, although such a strategy may lead to problematic hypercapnia. Extracorporeal carbon dioxide removal (ECCO₂R) devices allow uncoupling of ventilation from oxygenation, thereby removing carbon dioxide and facilitating lower tidal volume ventilation. We performed a systematic review to assess efficacy, complication rates, and utility of ECCO₂R devices. We included randomised controlled trials (RCTs), case-control studies and case series with 10 or more patients. We searched MEDLINE, Embase, LILACS (Literatura Latino Americana em Ciências da Saúde), and ISI Web of Science, in addition to grey literature and clinical trials registries. Data were independently extracted by two reviewers against predefined criteria and agreement was reached by consensus. Outcomes of interest included mortality, intensive care and hospital lengths of stay, respiratory parameters and complications. The review included 14 studies with 495 patients (two RCTs and 12 observational studies). Arteriovenous ECCO₂R was used in seven studies, and venovenous ECCO₂R in seven studies. Available evidence suggests no mortality benefit to ECCO₂R, although post hoc analysis of data from the most recent RCT showed an improvement in ventilator-free days in more severe ARDS. Organ failure-free days or ICU stay have not been shown to decrease with ECCOvR. Carbon dioxide removal was widely demonstrated as feasible, facilitating the use of lower tidal volume ventilation. Complication rates varied greatly across the included studies, representing technological advances. There was a general paucity of high-quality data and significant variation in both practice and technology used among studies, which confounded analysis. ECCO₂R is a rapidly evolving technology and is an efficacious treatment to enable protective lung ventilation. Evidence for a positive effect on mortality and other important clinical outcomes is lacking. Rapid technological advances have led to major changes in these devices and together with variation in study design have limited applicability of analysis. Further well-designed adequately powered RCTs are needed.

Protective effects of alpha-lipoic Acid on oleic Acid-induced acute lung injury in rats

BACKGROUND

Oxidative stress is believed to be an important factor in the pathogenesis of acute lung injury (ALI).

AIMS

The aim of this study was to investigate the possible protective role of alpha-lipoic acid (α-LA) on oleic acid (OA)-induced ALI in rats.

STUDY DESIGN

Animal experiment.

METHODS

A total of thirty-five rats were divided into five groups in the study. Group 1 served as a control group. Rats in Group 2 (α-LA) were administered α-LA intraperitoneally at a dose of 100 mg/kg body weight (BW). Rats in Group 3 (OA) were administered OA intravenously at a dose of 100 mg/kg BW. In Group 4 (pre-OA-α-LA), α-LA was given 15 minutes prior to OA infusion, and in Group 5 (post-OA-α-LA), α-LA was given two hours after OA infusion. Four hours after the OA infusion, rats were decapitated. Blood samples were collected to measure serum levels of malondialdehyde (MDA) and glutathione (GSH), and the levels of activity for superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Lung tissue samples were taken for histopathological examination.

RESULTS

Exposure to OA resulted in increases in serum MDA levels (p<0.001), as well as histopathological lesions in lung tissue, and decreases in CAT (p<0.05), GSH-Px (p<0.05) activities and GSH (p<0.05) levels. On the other hand, MDA levels were decreased significantly (p<0.001), while CAT (p<0.05), GSH-Px (p<0.01) activities and GSH (p<0.05) levels were increased significantly in the pre-OA-α-LA group compared with the OA group.

CONCLUSION

α-LA was found to lessen oxidative stress and to have positive effects on antioxidants in cases of OA-induced ALI. In conclusion, α-LA appears to have protective effects against ALI and potential for the prevention of ALI.

Mesenchymal stem cells: a promising therapy for the acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a pulmonary syndrome with growing prevalence and high mortality and morbidity that increase with age. There is no current therapy able to restore pulmonary function in ARDS patients. Preclinical models of ARDS have demonstrated that intratracheal or systemic administration of mesenchymal stem cells (MSCs) protects the lung against injury. The mechanisms responsible for the protective effects are multiple, including the secretion of multiple paracrine factors capable of modulating the immune response and restoring epithelial and endothelial integrity. Recent studies have demonstrated that MSCs can also control oxidative stress, transfer functional mitochondria to the damaged cells, and control bacterial infection by secretion of antibacterial peptides. These characteristics make MSCs promising candidates for ARDS therapy.

Biomarkers in acute lung injury--marking forward progress

This article reviews the state of the art regarding biomarkers for prediction, diagnosis, and prognosis in acute lung injury. Biomarkers and the goals of biomarker research are defined. Progress along 4 general routes is examined. First, the results of wide-ranging existing protein biomarkers are reported. Second, newer biomarkers awaiting or with strong potential for validation are described. Third, progress in the fields of genomics and proteomics is reported. Finally, given the complexity and number of potential biomarkers, the results of combining clinical predictors with protein and other biomarkers to produce better prognostic and diagnostic indices are examined.

Acute lung failure

Lung failure is the most common organ failure seen in the intensive care unit. The pathogenesis of acute respiratory failure (ARF) can be classified as (1) neuromuscular in origin, (2) secondary to acute and chronic obstructive airway diseases, (3) alveolar processes such as cardiogenic and noncardiogenic pulmonary edema and pneumonia, and (4) vascular diseases such as acute or chronic pulmonary embolism. This article reviews the more common causes of ARF from each group, including the pathological mechanisms and the principles of critical care management, focusing on the supportive, specific, and adjunctive therapies for each condition.

Translational research: from benchside to bedside

Translation of the achievements of basic science into everyday clinical practice remains a major issue in contemporary medicine, and is addressed through a new discipline, translational research, which aims to bridge the gap between basic and clinical research. Translational research encompasses laboratory studies, clinical demands, public health and health management, policies and economics; it is crucial in the evolution of contemporary biomedical science; and its interventions follow the political-economic, ethical-social and educational-scientific approaches. Translational research can progress through reorganisation of academic teams in a translational way. New academic posts translationally orientated are urgently needed, particularly in the field of trauma medicine, where lack of awareness of this new evolution is evident.

Lung Transplantation: Current Status and Challenges

The lung is an anatomically complex vital organ whose normal physiology depends on actively regulated ventilation and perfusion, and maintenance of a delicate blood-air barrier over a huge surface area in direct contact with a potentially hostile environment. Despite significant progress over the past 25 years, both short- and long-term outcomes remain significantly inferior for lung recipients relative to other "solid" organs. This review summarizes the current status of lung transplantation so as to frame the principle challenges currently facing end-stage lung-failure patients and the practitioners who care for them.

Biologic markers of mortality in acute lung injury

Acute lung injury (ALI) is a clinical syndrome in which patients develop severe and progressive pulmonary gas exchange defects and pulmonary mechanical dysfunction. The high morbidity and mortality (40%) associated with ALI provide a compelling need to identify clinical and/or biochemical parameters that robustly risk stratify patients for both accurate prognostication and clinical trial purposes. In this review, we will examine and critically evaluate studies pertaining to biochemical markers of mortality in ALI. These markers may not only serve as prognostic measures of disease, but in some cases, add to our overall understanding of the pathophysiology of ALI.

Surfactant protein D in human lung diseases

The lung is continuously exposed to inhaled pollutants, microbes and allergens. Therefore, the pulmonary immune system has to defend against harmful pathogens, while an inappropriate inflammatory response to harmless particles must be avoided. In the bronchoalveolar space this critical balance is maintained by innate immune proteins, termed surfactant proteins. Among these, surfactant protein D (SP-D) plays a central role in the pulmonary host defence and the modulation of allergic responses. Several human lung diseases are characterized by decreased levels of bronchoalveolar SP-D. Thus, recombinant SP-D has been proposed as a therapeutical option for cystic fibrosis, neonatal lung disease and smoking-induced emphysema. Furthermore, SP-D serum levels can be used as disease activity markers for interstitial lung diseases. This review illustrates the emerging role of SP-D translated from in vitro studies to human lung diseases.