Integrative metabolome and transcriptome profiling reveals discordant energetic stress between mouse strains with differential sensitivity to acrolein-induced acute lung injury

The role of fatty acid metabolism in acute lung injury: a special focus on immunometabolism

Reputable evidence from multiple studies suggests that excessive and uncontrolled inflammation plays an indispensable role in mediating, amplifying, and protracting acute lung injury (ALI). Traditionally, immunity and energy metabolism are regarded as separate functions regulated by distinct mechanisms, but recently, more and more evidence show that immunity and energy metabolism exhibit a strong interaction which has given rise to an emerging field of immunometabolism. Mammalian lungs are organs with active fatty acid metabolism, however, during ALI, inflammation and oxidative stress lead to a series metabolic reprogramming such as impaired fatty acid oxidation, increased expression of proteins involved in fatty acid uptake and transport, enhanced synthesis of fatty acids, and accumulation of lipid droplets. In addition, obesity represents a significant risk factor for ALI/ARDS. Thus, we have further elucidated the mechanisms of obesity exacerbating ALI from the perspective of fatty acid metabolism. To sum up, this paper presents a systematical review of the relationship between extensive fatty acid metabolic pathways and acute lung injury and summarizes recent advances in understanding the involvement of fatty acid metabolism-related pathways in ALI. We hold an optimistic believe that targeting fatty acid metabolism pathway is a promising lung protection strategy, but the specific regulatory mechanisms are way too complex, necessitating further extensive and in-depth investigations in future studies.

Countermeasures against Pulmonary Threat Agents

Inhaled toxicants are used for diverse purposes, ranging from industrial applications such as agriculture, sanitation, and fumigation to crowd control and chemical warfare, and acute exposure can induce lasting respiratory complications. The intentional release of chemical warfare agents (CWAs) during World War I caused life-long damage for survivors, and CWA use is outlawed by international treaties. However, in the past two decades, chemical warfare use has surged in the Middle East and Eastern Europe, with a shift toward lung toxicants. The potential use of industrial and agricultural chemicals in rogue activities is a major concern as they are often stored and transported near populated areas, where intentional or accidental release can cause severe injuries and fatalities. Despite laws and regulatory agencies that regulate use, storage, transport, emissions, and disposal, inhalational exposures continue to cause lasting lung injury. Industrial irritants (e.g., ammonia) aggravate the upper respiratory tract, causing pneumonitis, bronchoconstriction, and dyspnea. Irritant gases (e.g., acrolein, chloropicrin) affect epithelial barrier integrity and cause tissue damage through reactive intermediates or by direct adduction of cysteine-rich proteins. Symptoms of CWAs (e.g., chlorine gas, phosgene, sulfur mustard) progress from airway obstruction and pulmonary edema to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which results in respiratory depression days later. Emergency treatment is limited to supportive care using bronchodilators to control airway constriction and rescue with mechanical ventilation to improve gas exchange. Complications from acute exposure can promote obstructive lung disease and/or pulmonary fibrosis, which require long-term clinical care. SIGNIFICANCE STATEMENT: Inhaled chemical threats are of growing concern in both civilian and military settings, and there is an increased need to reduce acute lung injury and delayed clinical complications from exposures. This minireview highlights our current understanding of acute toxicity and pathophysiology of a select number of chemicals of concern. It discusses potential early-stage therapeutic development as well as challenges in developing countermeasures applicable for administration in mass casualty situations.

The Tobacco Smoke Component, Acrolein, as a Major Culprit in Lung Diseases and Respiratory Cancers: Molecular Mechanisms of Acrolein Cytotoxic Activity

Acrolein, a highly reactive unsaturated aldehyde, is a ubiquitous environmental pollutant that seriously threatens human health and life. Due to its high reactivity, cytotoxicity and genotoxicity, acrolein is involved in the development of several diseases, including multiple sclerosis, neurodegenerative diseases such as Alzheimer’s disease, cardiovascular and respiratory diseases, diabetes mellitus and even the development of cancer. Traditional tobacco smokers and e-cigarette users are particularly exposed to the harmful effects of acrolein. High concentrations of acrolein have been found in both mainstream and side-stream tobacco smoke. Acrolein is considered one of cigarette smoke’s most toxic and harmful components. Chronic exposure to acrolein through cigarette smoke has been linked to the development of asthma, acute lung injury, chronic obstructive pulmonary disease (COPD) and even respiratory cancers. This review addresses the current state of knowledge on the pathological molecular mechanisms of acrolein in the induction, course and development of lung diseases and cancers in smokers.

Impact of sub-acute acrolein inhalation on the molecular regulation of mitochondrial metabolism in rat lung

Nowadays, mitochondria are recognized as key players in the pathogenesis of a variety of smoking-associated lung diseases. Acrolein, a component of cigarette smoke, is a known driver of biological mechanisms underlying smoking-induced respiratory toxicity. The impact of sub-acute acrolein inhalation in vivo on key processes controlling mitochondrial homeostasis in cells of the airways however is unknown. In this study, we investigated the activity/abundance of a myriad of molecules critically involved in mitochondrial metabolic pathways and mitochondrial quality control processes (mitochondrial biogenesis and mitophagy) in the lungs of Sprague-Dawley rats that were sub-acutely exposed to filtered air or 3 ppm acrolein by whole-body inhalation (5 h/day, 5 days/week for 4 weeks). Acrolein exposure induced a general inflammatory response in the lung as gene expression analysis revealed an increased expression of Icam1 and Cinc1 (p < 0.1; p < 0.05). Acrolein significantly decreased enzyme activity of hydroxyacyl-Coenzyme A dehydrogenase (p < 0.01), and decreased Pdk4 transcript levels (p < 0.05), suggestive of acrolein-induced changes in metabolic processes. Investigation of constituents of the mitochondrial biogenesis pathways and mitophagy machinery revealed no pronounced alterations. In conclusion, sub-acute inhalation of acrolein did not affect the regulation of mitochondrial metabolism and quality control, which is in contrast to more profound changes after acute exposure in other studies.

Disruption of the Molecular Regulation of Mitochondrial Metabolism in Airway and Lung Epithelial Cells by Cigarette Smoke: Are Aldehydes the Culprit?

Chronic obstructive pulmonary disease (COPD) is a devastating lung disease for which cigarette smoking is the main risk factor. Acetaldehyde, acrolein, and formaldehyde are short-chain aldehydes known to be formed during pyrolysis and combustion of tobacco and have been linked to respiratory toxicity. Mitochondrial dysfunction is suggested to be mechanistically and causally involved in the pathogenesis of smoking-associated lung diseases such as COPD. Cigarette smoke (CS) has been shown to impair the molecular regulation of mitochondrial metabolism and content in epithelial cells of the airways and lungs. Although it is unknown which specific chemicals present in CS are responsible for this, it has been suggested that aldehydes may be involved. Therefore, it has been proposed by the World Health Organization to regulate aldehydes in commercially-available cigarettes. In this review, we comprehensively describe and discuss the impact of acetaldehyde, acrolein, and formaldehyde on mitochondrial function and content and the molecular pathways controlling this (biogenesis versus mitophagy) in epithelial cells of the airways and lungs. In addition, potential therapeutic applications targeting (aldehyde-induced) mitochondrial dysfunction, as well as regulatory implications, and the necessary required future studies to provide scientific support for this regulation, have been covered in this review.

Metabolomics profile in acute respiratory distress syndrome by nuclear magnetic resonance spectroscopy in patients with community-acquired pneumonia

Background

Acute respiratory distress syndrome (ARDS) is a challenging clinical problem. Discovering the potential metabolic alterations underlying the ARDS is important to identify novel therapeutic target and improve the prognosis. Serum and urine metabolites can reflect systemic and local changes and could help understanding metabolic characterization of community-acquired pneumonia (CAP) with ARDS.

Methods

Clinical data of patients with suspected CAP at the First Affiliated Hospital of Wenzhou Medical University were collected from May 2020 to February 2021. Consecutive patients with CAP were enrolled and divided into two groups: CAP with and without ARDS groups. ¹H nuclear magnetic resonance-based metabolomics analyses of serum and urine samples were performed before and after treatment in CAP with ARDS (n = 43) and CAP without ARDS (n = 45) groups. Differences metabolites were identifed in CAP with ARDS. Furthermore, the receiver operating characteristic (ROC) curve was utilized to identify panels of significant metabolites for evaluating therapeutic effects on CAP with ARDS. The correlation heatmap was analyzed to further display the relationship between metabolites and clinical characteristics.

Results

A total of 20 and 42 metabolites were identified in the serum and urine samples, respectively. Serum metabolic changes were mainly involved in energy, lipid, and amino acid metabolisms, while urine metabolic changes were mainly involved in energy metabolism. Elevated levels of serum 3-hydroxybutyrate, lactate, acetone, acetoacetate, and decreased levels of serum leucine, choline, and urine creatine and creatinine were detected in CAP with ARDS relative to CAP without ARDS. Serum metabolites 3-hydroxybutyrate, acetone, acetoacetate, citrate, choline and urine metabolite 1-methylnicotinamide were identified as a potential biomarkers for assessing therapeutic effects on CAP with ARDS, and with AUCs of 0.866 and 0.795, respectively. Moreover, the ROC curve analysis revealed that combined characteristic serum and urine metabolites exhibited a better classification system for assessing therapeutic effects on CAP with ARDS, with a AUC value of 0.952. In addition, differential metabolites strongly correlated with clinical parameters in patients with CAP with ARDS.

Conclusions

Serum- and urine-based metabolomics analyses identified characteristic metabolic alterations in CAP with ARDS and might provide promising circulatory markers for evaluating therapeutic effects on CAP with ARDS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02075-w.

Acrolein inhalation acutely affects the regulation of mitochondrial metabolism in rat lung

Exposure of the airways to cigarette smoke (CS) is the primary risk factor for developing several lung diseases such as Chronic Obstructive Pulmonary Disease (COPD). CS consists of a complex mixture of over 6000 chemicals including the highly reactive α,β-unsaturated aldehyde acrolein. Acrolein is thought to be responsible for a large proportion of the non-cancer disease risk associated with smoking. Emerging evidence suggest a key role for CS-induced abnormalities in mitochondrial morphology and function in airway epithelial cells in COPD pathogenesis. Although in vitro studies suggest acrolein-induced mitochondrial dysfunction in airway epithelial cells, it is unknown if in vivo inhalation of acrolein affects mitochondrial content or the pathways controlling this. In this study, rats were acutely exposed to acrolein by inhalation (nose-only; 0-4 ppm), 4 h/day for 1 or 2 consecutive days (n = 6/group). Subsequently, the activity and abundance of key constituents of mitochondrial metabolic pathways as well as expression of critical proteins and genes controlling mitochondrial biogenesis and mitophagy were investigated in lung homogenates. A transient decreasing response in protein and transcript abundance of subunits of the electron transport chain complexes was observed following acrolein inhalation. Moreover, acrolein inhalation caused a decreased abundance of key regulators associated with mitochondrial biogenesis, respectively a differential response on day 1 versus day 2. Abundance of components of the mitophagy machinery was in general unaltered in response to acrolein exposure in rat lung. Collectively, this study demonstrates that acrolein inhalation acutely and dose-dependently disrupts the molecular regulation of mitochondrial metabolism in rat lung. Hence, understanding the effect of acrolein on mitochondrial function will provide a scientifically supported reasoning to shortlist aldehydes regulation in tobacco smoke.

Genetic determinants of ammonia-induced acute lung injury in mice

In this study, a genetically diverse panel of 43 mouse strains was exposed to ammonia, and genome-wide association mapping was performed employing a single-nucleotide polymorphism (SNP) assembly. Transcriptomic analysis was used to help resolve the genetic determinants of ammonia-induced acute lung injury. The encoded proteins were prioritized based on molecular function, nonsynonymous SNP within a functional domain or SNP within the promoter region that altered expression. This integrative functional approach revealed 14 candidate genes that included Aatf, Avil, Cep162, Hrh4, Lama3, Plcb4, and Ube2cbp, which had significant SNP associations, and Aff1, Bcar3, Cntn4, Kcnq5, Prdm10, Ptcd3, and Snx19, which had suggestive SNP associations. Of these genes, Bcar3, Cep162, Hrh4, Kcnq5, and Lama3 are particularly noteworthy and had pathophysiological roles that could be associated with acute lung injury in several ways.

Albumin Protects Lung Cells against Acrolein Cytotoxicity and Acrolein-Adducted Albumin Increases Heme Oxygenase 1 Transcripts

Albumin is an abundant protein in the lung lining fluid that forms an interface between lung epithelial cells and the external environment. In the lung, albumin can be targeted for adduction by inhaled acrolein. Acrolein, an α,β-unsaturated aldehyde, reacts with biomolecules via Michael addition at the β-carbon or Schiff base formation at the carbonyl carbon. To gain insight into acrolein's mode of action, we investigated in vitro albumin-acrolein reactivity and the consequence of albumin adduction by acrolein on cytotoxicity and transcript changes in NCI-H441 and human airway epithelial cells (HAEC). Albumin protected NCI-H441 cells from acrolein toxicity. In addition, albumin inhibited acrolein-induced increase of transcripts associated with cellular stress response, activating transcription factor 3 (ATF3), and antioxidant response, heme oxygenase 1 (HMOX1) in HAEC cells. Acrolein-adducted albumin itself increased HMOX1 transcripts but not ATF3 transcripts. The HMOX1 transcript increase was inhibited by hydralazine, a carbonyl scavenger, suggesting that the carbonyl group of acrolein-adducted albumin mediated HMOX1 transcript increase. In acutely exposed C57BL/6J mice, bronchoalveolar lavage protein carbonylation increased. Acrolein-adducted albumin Cys34 was identified by nLC-MS/MS. These findings indicate that adduction of albumin by acrolein confers a cytoprotective function by scavenging free acrolein, decreasing a cellular stress response, and inducing an antioxidant gene response. Further, these results suggest that β-carbon reactivity may be required for acrolein's cytotoxicity and ATF3 transcript increase, and the carbonyl group of acrolein-adducted albumin can induce HMOX1 transcript increase.

Metabolomic Profile of ARDS by Nuclear Magnetic Resonance Spectroscopy in Patients With H1N1 Influenza Virus Pneumonia

PURPOSE

The integrated analysis of changes in the metabolic profile could be critical for the discovery of biomarkers of lung injury, and also for generating new pathophysiological hypotheses and designing novel therapeutic targets for the acute respiratory distress syndrome (ARDS). This study aimed at developing a nuclear magnetic resonance (NMR)-based approach for the identification of the metabolomic profile of ARDS in patients with H1N1 influenza virus pneumonia.

METHODS

Serum samples from 30 patients (derivation set) diagnosed of H1N1 influenza virus pneumonia were analyzed by unsupervised principal component analysis to identify metabolic differences between patients with and without ARDS by NMR spectroscopy. A predictive model of partial least squares discriminant analysis (PLS-DA) was developed for the identification of ARDS. PLS-DA was trained with the derivation set and tested in another set of samples from 26 patients also diagnosed of H1N1 influenza virus pneumonia (validation set).

RESULTS

Decreased serum glucose, alanine, glutamine, methylhistidine and fatty acids concentrations, and elevated serum phenylalanine and methylguanidine concentrations, discriminated patients with ARDS versus patients without ARDS. PLS-DA model successfully identified the presence of ARDS in the validation set with a success rate of 92% (sensitivity 100% and specificity 91%). The classification functions showed a good correlation with the Sequential Organ Failure Assessment score (R = 0.74, P < 0.0001) and the PaO2/FiO2 ratio (R = 0.41, P = 0.03).

CONCLUSIONS

The serum metabolomic profile is sensitive and specific to identify ARDS in patients with H1N1 influenza A pneumonia. Future studies are needed to determine the role of NMR spectroscopy as a biomarker of ARDS.

Bio-Inspired Silver Nanoparticles Impose Metabolic and Epigenetic Toxicity to Saccharomyces cerevisiae

Silver nanoparticles (AgNPs) have many applications in various fields, including biomedical applications. Due to the broad range of applications, they are considered as the leading fraction of manufactured nanoparticles. AgNPs are synthesized by different types of chemical and biological (green) methods. Previously, biologically synthesized AgNPs were considered safe for the environment and humans. However, new toxicity evidence have initiated a more careful assessment to delineate the toxicity mechanisms associated with these nanoparticles. This study demonstrates the use of aqueous gooseberry extract for AgNP preparation in a time- and cost-effective way. Ultraviolet-visible spectroscopy, X-ray diffraction, transmission electron microscopy, and dynamic light scattering confirm the formation of AgNPs, with an average size between 50 and 100 nm. Untargeted ¹H-nuclear magnetic resonance-based metabolomics revealed manyfold up- and down-regulation in the concentration of 55 different classes of annotated metabolites in AgNP-exposed yeast Saccharomyces cerevisiae cells. Based on their chemical nature and cellular functions, these metabolites are classified into amino acids, glycolysis and the tricarboxylic acid (TCA) cycle, organic acids, nucleotide metabolism, urea cycle, and lipid metabolism. Transcriptome analysis revealed that the genes involved in oxidative stress mitigation maintain their expression levels, whereas the genes of the TCA cycle and lipid metabolism show drastic down-regulation upon AgNP exposure. Moreover, they can induce alteration in histone epigenetic marks by altering the methylation and acetylation of selected histone H3 and H4 proteins. Altogether, we conclude that the selected dose of biologically synthesized AgNPs impose toxicity by modulating the transcriptome, epigenome, and metabolome of eukaryotic cells, which eventually cause disequilibrium in cellular metabolism leading to toxicity.

Identification of differentially expressed proteins in the injured lung from zinc chloride smoke inhalation based on proteomics analysis

Background

Lung injury due to zinc chloride smoke inhalation is very common in military personnel and leads to a high incidence of pulmonary complications and mortality. The aim of this study was to uncover the underlying mechanisms of lung injury due to zinc chloride smoke inhalation using a rat model.

Methods: Histopathology analysis of rat lungs after zinc chloride smoke inhalation was performed by using haematoxylin and eosin (H&E) and Mallory staining. A lung injury rat model of zinc chloride smoke inhalation (smoke inhalation for 1, 2, 7 and 14 days) was developed. First, isobaric tags for relative and absolute quantization (iTRAQ) and weighted gene co-expression network analysis (WGCNA) were used to identify important differentially expressed proteins. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to study the biological functions of differentially expressed proteins. Then, analysis of lung injury repair-related differentially expressed proteins in the early (day 1 and day 2) and middle-late stages (day 7 and day 14) of lung injury after smoke inhalation was performed, followed by the protein-protein interaction (PPI) analysis of these differentially expressed proteins. Finally, the injury repair-related proteins PARK7 and FABP5 were validated by immunohistochemistry and western blot analysis.

Results

Morphological changes were observed in the lung tissues after zinc chloride smoke inhalation. A total of 27 common differentially expressed proteins were obtained on days 1, 2, 7 and 14 after smoke inhalation. WGCNA showed that the turquoise module (which involved 909 proteins) was most associated with smoke inhalation time. Myl3, Ckm, Adrm1 and Igfbp7 were identified in the early stages of lung injury repair. Gapdh, Acly, Tnni2, Acta1, Actn3, Pygm, Eno3 and Tpi1 (hub proteins in the PPI network) were identified in the middle-late stages of lung injury repair. Eno3 and Tpi1 were both involved in the glycolysis/gluconeogenesis signalling pathway. The expression of PARK7 and FABP5 was validated and was consistent with the proteomics analysis.

Conclusion

The identified hub proteins and their related signalling pathways may play crucial roles in lung injury repair due to zinc chloride smoke inhalation.

Zinc oxide nanoparticles impose metabolic toxicity by de-regulating proteome and metabolome in Saccharomyces cerevisiae

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Untargeted proteomic and metabolic approaches provide complete toxicity assessment.

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ZnO-NPs de-regulate the proteome and metabolome of S. cerevisiae.

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ZnO-NPs affect the key metabolites of central metabolic pathways.

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Protein and/or metabolite can be used as biomarker specific to the ZnO-NPs induced toxicity.

As zinc oxide nanoparticles are being increasingly used in various applications, it is important to assess their potential toxic implications. Stress responses and adaptations are primarily controlled by modulation in cellular proteins (enzyme) and concentration of metabolites. To date proteomics or metabolomics applications in nanotoxicity assessment have been applied to a restricted extent. Here we utilized 2DE and ¹H NMR based proteomics and metabolomics respectively to delineate the toxicity mechanism of zinc oxide nanoparticles (ZnO-NPs) in budding yeast S. cerevisiae. We found that the physiological and metabolic processes were altered in the S. cerevisiae upon ZnO-NPs exposure. Almost 40% proteins were down-regulated in ZnO-NPs (10 mg L⁻¹) exposed cell as compared to control. Metabolomics and system biology based pathway analysis, revealed that ZnO-NPs repressed a wide range of key metabolites involved in central carbon metabolism, cofactors synthesis, amino acid and fatty acid biosynthesis, purines and pyrimidines, nucleoside and nucleotide biosynthetic pathways. These metabolic changes may be associated with the energy metabolism, antioxidation, DNA and protein damage and membrane stability. We concluded that untargeted proteomic and metabolic approaches provide more complete measurements and suggest probable molecular mechanisms of nanomaterials toxicity.

Zinc Oxide Nanoparticle Caused Plasma Metabolomic Perturbations Correlate with Hepatic Steatosis

Zinc oxide nanoparticles (ZnO NPs), known for their chemical stability and strong adsorption, are used in everyday items such as cosmetics, sunscreens, and prophylactic drugs. However, they have also been found to adversely affect organisms; previously we found that ZnO NPs disrupt pubertal ovarian development, inhibit embryonic development by upsetting γ-H2AX and NF-κB pathways, and even disturb skin stem cells. Non-targeted metabolomic analysis of biological organisms has been suggested as an unbiased tool for the investigation of perturbations in response to NPs and their underlying mechanisms. Although metabolomics has been used in nanotoxicological studies, very few reports have used it to investigate the effects of ZnO NPs exposure. In the current investigation, through a metabolomics-based approach, we discovered that ZnO NPs caused changes in plasma metabolites involved in anti-oxidative mechanisms, energy metabolism, and lipid metabolism in hen livers. These results are in line with earlier findings that ZnO NPs perturb the tricarboxylic acid cycle and in turn result in the use of alternative energy sources. We also found that ZnO NPs disturbed lipid metabolism in the liver and consequently impacted blood lipid balance. Changes in plasma metabolomes were correlated with hepatic steatosis.

Alda-1 Protects Against Acrolein-Induced Acute Lung Injury and Endothelial Barrier Dysfunction

Inhalation of acrolein, a highly reactive aldehyde, causes lung edema. The underlying mechanism is poorly understood and there is no effective treatment. In this study, we demonstrated that acrolein not only dose-dependently induced lung edema but also promoted LPS-induced acute lung injury. Importantly, acrolein-induced lung injury was prevented and rescued by Alda-1, an activator of mitochondrial aldehyde dehydrogenase 2. Acrolein also dose-dependently increased monolayer permeability, disrupted adherens junctions and focal adhesion complexes, and caused intercellular gap formation in primary cultured lung microvascular endothelial cells (LMVECs). These effects were attenuated by Alda-1 and the antioxidant N-acetylcysteine, but not by the NADPH inhibitor apocynin. Furthermore, acrolein inhibited AMP-activated protein kinase (AMPK) and increased mitochondrial reactive oxygen species levels in LMVECs-effects that were associated with impaired mitochondrial respiration. AMPK total protein levels were also reduced in lung tissue of mice and LMVECs exposed to acrolein. Activation of AMPK with 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside blunted an acrolein-induced increase in endothelial monolayer permeability, but not mitochondrial oxidative stress or inhibition of mitochondrial respiration. Our results suggest that acrolein-induced mitochondrial dysfunction may not contribute to endothelial barrier dysfunction. We speculate that detoxification of acrolein by Alda-1 and activation of AMPK may be novel approaches to prevent and treat acrolein-associated acute lung injury, which may occur after smoke inhalation.

Use of immunoproteomics to identify immunogenic proteins in a rat model of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a common and life‑threatening clinical syndrome, and seeking biomarkers of ARDS has been an area of continuing research. The present study hypothesized that alterations to certain immunogenic substances occur in injured lungs and are able to specifically bind with corresponding proteins in the blood, and that these proteins may be readily detected. To investigate this hypothesis, a rat model of ARDS was established by cecal ligation and puncture surgery, and an immunoproteomics approach, using serum as the primary antibody in a western blot analysis, was used with the aim of identifying immunogenic proteins in the injured lungs. Ingenuity Pathway Analysis (IPA) was used for bioinformatics analysis, and mass spectrometric analysis was used to identify a total of 38 differentially expressed immunogenic proteins. Bioinformatics analysis revealed that the top canonical pathways in which the identified proteins may be involved were gluconeogenesis I, glycolysis I, choline degradation I, NADH repair and heme degradation. IPA Biomarker Filter analysis with the terms 'acute respiratory distress syndrome/acute lung injury' was used to screen 13 proteins as candidate biomarkers. These proteins were described as antigens, and suggested that paired antibodies may be detected in the plasma of patients at high risk of ARDS. Analysis of these identified proteins may provide novel insights into the potential pathological mechanisms of ARDS.

Effect of acute ozone exposure on the lung metabolomes of obese and lean mice

Pulmonary responses to the air pollutant, ozone, are increased in obesity. Both obesity and ozone cause changes in systemic metabolism. Consequently, we examined the impact of ozone on the lung metabolomes of obese and lean mice. Lean wildtype and obese db/db mice were exposed to acute ozone (2 ppm for 3 h) or air. 24 hours later, the lungs were excised, flushed with PBS to remove blood and analyzed via liquid-chromatography or gas-chromatography coupled to mass spectrometry for metabolites. Both obesity and ozone caused changes in the lung metabolome. Of 321 compounds identified, 101 were significantly impacted by obesity in air-exposed mice. These included biochemicals related to carbohydrate and lipid metabolism, which were each increased in lungs of obese versus lean mice. These metabolite changes may be of functional importance given the signaling capacity of these moieties. Ozone differentially affected the lung metabolome in obese versus lean mice. For example, almost all phosphocholine-containing lysolipids were significantly reduced in lean mice, but this effect was attenuated in obese mice. Glutathione metabolism was also differentially affected by ozone in obese and lean mice. Finally, the lung metabolome indicated a role for the microbiome in the effects of both obesity and ozone: all measured bacterial/mammalian co-metabolites were significantly affected by obesity and/or ozone. Thus, metabolic derangements in obesity appear to impact the response to ozone.

Functional genomic assessment of phosgene-induced acute lung injury in mice

In this study, a genetically diverse panel of 43 mouse strains was exposed to phosgene and genome-wide association mapping performed using a high-density single nucleotide polymorphism (SNP) assembly. Transcriptomic analysis was also used to improve the genetic resolution in the identification of genetic determinants of phosgene-induced acute lung injury (ALI). We prioritized the identified genes based on whether the encoded protein was previously associated with lung injury or contained a nonsynonymous SNP within a functional domain. Candidates were selected that contained a promoter SNP that could alter a putative transcription factor binding site and had variable expression by transcriptomic analyses. The latter two criteria also required that ≥10% of mice carried the minor allele and that this allele could account for ≥10% of the phenotypic difference noted between the strains at the phenotypic extremes. This integrative, functional approach revealed 14 candidate genes that included Atp1a1, Alox5, Galnt11, Hrh1, Mbd4, Phactr2, Plxnd1, Ptprt, Reln, and Zfand4, which had significant SNP associations, and Itga9, Man1a2, Mapk14, and Vwf, which had suggestive SNP associations. Of the genes with significant SNP associations, Atp1a1, Alox5, Plxnd1, Ptprt, and Zfand4 could be associated with ALI in several ways. Using a competitive electrophoretic mobility shift analysis, Atp1a1 promoter (rs215053185) oligonucleotide containing the minor G allele formed a major distinct faster-migrating complex. In addition, a gene with a suggestive SNP association, Itga9, is linked to transforming growth factor β1 signaling, which previously has been associated with the susceptibility to ALI in mice.

Modified Jiu Wei Qiang Huo decoction improves dysfunctional metabolomics in influenza A pneumonia-infected mice

In order to study the effective mechanism of a traditional Chinese medicine (TCM), modified Jiu Wei Qiang Huo decoction (MJWQH), against H1N1-induced pneumonia in mice, we chose a holistic approach. A reverse-phase liquid chromatography with quadruple time-of-flight mass spectrometry (LC-Q-TOF-MS) was developed to determine metabolomic biomarkers in mouse serum for the MJWQH effects. Thirteen biomarkers of H1N1-induced pneumonia in mice serum were identified, which comprised l-valine, lauroylcarnitine, palmitoyl-l-carnitine, l-ornithine, uric acid, taurine, O-succinyl-l-homoserine, l-leucine, l-phenylalanine, PGF2α, 20-ethyl-PGE2, arachidonic acid, and glycerophospho-N-arachidonoyl ethanolamine. Among them, metabolites of amino acids, fatty acids and arachidonic acid had the most relevant changes in mice with H1N1-induced pneumonia. MJWQH effectively improved weight loss, lung index, biomarkers and inflammatory mediators such as prostaglandin E2 and phospholipase A2 in the infected mice. Importantly, MJWQH reversed the elevated biomarkers to the control levels from the infection, which provided a systematic view and a theoretical basis for its prevention or treatment. The results suggest that the protective effect of MJWQH against H1N1-induced pneumonia is possibly through regulation of pathways for amino acid, fatty acid and arachidonic acid metabolism. They also suggest that the LC-MS-based metabolomic strategy is a powerful tool for elucidation of the mechanisms of TCM.

Integrative assessment of chlorine-induced acute lung injury in mice

The genetic basis for the underlying individual susceptibility to chlorine-induced acute lung injury is unknown. To uncover the genetic basis and pathophysiological processes that could provide additional homeostatic capacities during lung injury, 40 inbred murine strains were exposed to chlorine, and haplotype association mapping was performed. The identified single-nucleotide polymorphism (SNP) associations were evaluated through transcriptomic and metabolomic profiling. Using ≥ 10% allelic frequency and ≥ 10% phenotype explained as threshold criteria, promoter SNPs that could eliminate putative transcriptional factor recognition sites in candidate genes were assessed by determining transcript levels through microarray and reverse real-time PCR during chlorine exposure. The mean survival time varied by approximately 5-fold among strains, and SNP associations were identified for 13 candidate genes on chromosomes 1, 4, 5, 9, and 15. Microarrays revealed several differentially enriched pathways, including protein transport (decreased more in the sensitive C57BLKS/J lung) and protein catabolic process (increased more in the resistant C57BL/10J lung). Lung metabolomic profiling revealed 95 of the 280 metabolites measured were altered by chlorine exposure, and included alanine, which decreased more in the C57BLKS/J than in the C57BL/10J strain, and glutamine, which increased more in the C57BL/10J than in the C57BLKS/J strain. Genetic associations from haplotype mapping were strengthened by an integrated assessment using transcriptomic and metabolomic profiling. The leading candidate genes associated with increased susceptibility to acute lung injury in mice included Klf4, Sema7a, Tns1, Aacs, and a gene that encodes an amino acid carrier, Slc38a4.