Targeted eicosanoid lipidomics of exhaled breath condensate provide a distinct pattern in the aspirin-intolerant asthma phenotype

Pla2g5 contributes to viral-like-induced lung inflammation through macrophage proliferation and LA/Ffar1 lung cell recruitment

Macrophages expressing group V phospholipase A2 (Pla2g5) release the free fatty acid (FFA) linoleic acid (LA), potentiating lung type 2 inflammation. Although Pla2g5 and LA increase in viral infections, their role remains obscure. We generated Pla2g5flox/flox mice, deleted Pla2g5 by using the Cx3cr1cre transgene, and activated bone marrow-derived macrophages (BM-Macs) with poly:IC, a synthetic double-stranded RNA that triggers a viral-like immune response, known Pla2g5-dependent stimuli (IL-4, LPS + IFNγ, IL-33 + IL-4 + GM-CSF) and poly:IC + LA followed by lipidomic and transcriptomic analysis. Poly:IC-activated Pla2g5flox/flox;Cx3cr1cre/+ BM-Macs had downregulation of major bioactive lipids and critical enzymes producing those bioactive lipids. In addition, AKT phosphorylation was lower in poly:IC-stimulated Pla2g5flox/flox;Cx3cr1cre/+ BM-Macs, which was not restored by adding LA to poly:IC-stimulated BM-Macs. Consistently, Pla2g5flox/flox;Cx3cr1cre/+ mice had diminished poly:IC-induced lung inflammation, including inflammatory macrophage proliferation, while challenging Pla2g5flox/flox;Cx3cr1cre/+ mice with poly:IC + LA partially restored lung inflammation and inflammatory macrophage proliferation. Finally, mice lacking FFA receptor-1 (Ffar1)-null mice had reduced poly:IC-induced lung cell recruitment and tissue macrophage proliferation, not corrected by LA. Thus, Pla2g5 contributes to poly:IC-induced lung inflammation by regulating inflammatory macrophage proliferation and LA/Ffar1-mediated lung cell recruitment and tissue macrophage proliferation.

Hypersensitivity to intravenous succinate corticosteroids in patients with nonsteroidal anti-inflammatory drug-exacerbated respiratory disease

Although there are many case reports of asthma exacerbations with intravenous corticosteroids, especially hydrocortisone succinate, in nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD), the frequency and mechanism remain unclear. We hypothesized that N-ERD patients are potentially hypersensitive to succinates, especially succinate corticosteroids, based on the results of previous provocation studies and considered specific mechanisms. The objective of this study was to determine the frequency and mechanism of succinate corticosteroids hypersensitivity in patients with N-ERD. Eleven patients with stable, moderate to severe N-ERD were tested with hydrocortisone sodium succinate (HCs), hydrocortisone sodium phosphate (HCp), methylprednisolone sodium succinate (MPSLs), prednisolone sodium succinate (PSLs), and chloramphenicol sodium succinate (CPs, without a steroidal chemical structure) at doses below the normal dose through intravenous administration using a single-blind test. As a comparison, seven patients with aspirin-tolerant asthma (ATA) also underwent an intravenous provocation test of HCs. The positive intravenous provocation test rates of HCs 100-500 mg, HCp 500 mg, MPSLs 80 mg, PSLs 20 mg, and CPs 500 mg in N-ERD patients were 82% (9/11), 9% (1/11), 50% (5/10), 33% (1/3), and 86% (6/7), respectively. Most positive reactions began with a severe cough within 5 min of intravenous injection. The course of these hypersensitivity symptoms differed from those seen with the usual aspirin challenge test. The HCs 100-500 mg intravenous test was negative in all seven patients with ATA. In conclusion, patients with N-ERD have high rates of potential hypersensitivity to the succinate ester structure, which is not linked to the corticosteroid structure, but to the succinate ester structure. We hypothesized that the mechanism of hypersensitivity observed during rapid intravenous administration of succinate corticosteroids is mast cell activation via succinate receptor stimulation, rather than due to the corticosteroid itself.

Targeted Mass Spectrometry Reveals Interferon-Dependent Eicosanoid and Fatty Acid Alterations in Chronic Myeloid Leukaemia

Bioactive lipids are involved in cellular signalling events with links to human disease. Many of these are involved in inflammation under normal and pathological conditions. Despite being attractive molecules from a pharmacological point of view, the detection and quantification of lipids has been a major challenge. Here, we have optimised a liquid chromatography-dynamic multiple reaction monitoring-targeted mass spectrometry (LC-dMRM-MS) approach to profile eicosanoids and fatty acids in biological samples. In particular, by applying this analytic workflow to study a cellular model of chronic myeloid leukaemia (CML), we found that the levels of intra- and extracellular 2-Arachidonoylglycerol (2-AG), intracellular Arachidonic Acid (AA), extracellular Prostaglandin F2α (PGF2α), extracellular 5-Hydroxyeicosatetraenoic acid (5-HETE), extracellular Palmitic acid (PA, C16:0) and extracellular Stearic acid (SA, C18:0), were altered in response to immunomodulation by type I interferon (IFN-I), a currently approved treatment for CML. Our observations indicate changes in eicosanoid and fatty acid metabolism, with potential relevance in the context of cancer inflammation and CML.

Mast cell-mediated immune regulation in health and disease

Mast cells are important components of the immune system, and they perform pro-inflammatory as well as anti-inflammatory roles in the complex process of immune regulation in health and disease. Because of their strategic perivascular localization, sensitivity and adaptability to the microenvironment, and ability to release a variety of preformed and newly synthesized effector molecules, mast cells perform unique functions in almost all organs. Additionally, Mast cells express a wide range of surface and cytoplasmic receptors which enable them to respond to a variety of cytokines, chemicals, and pathogens. The mast cell's role as a cellular interface between external and internal environments as well as between vasculature and tissues is critical for protection and repair. Mast cell interactions with different immune and nonimmune cells through secreted inflammatory mediators may also turn in favor of disease promoting agents. First and forefront, mast cells are well recognized for their multifaceted functions in allergic diseases. Reciprocal communication between mast cells and endothelial cells in the presence of bacterial toxins in chronic/sub-clinical infections induce persistent vascular inflammation. We have shown that mast cell proteases and histamine induce endothelial inflammatory responses that are synergistically amplified by bacterial toxins. Mast cells have been shown to exacerbate vascular changes in normal states as well as in chronic or subclinical infections, particularly among cigarette smokers. Furthermore, a potential role of mast cells in SARS-CoV-2-induced dysfunction of the capillary-alveolar interface adds to the growing understanding of mast cells in viral infections. The interaction between mast cells and microglial cells in the brain further highlights their significance in neuroinflammation. This review highlights the significant role of mast cells as the interface that acts as sensor and early responder through interactions with cells in systemic organs and the nervous system.

The Role of Omalizumab in NSAID-Exacerbated Respiratory Disease: A Narrative Review

Nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD) is a condition characterized by the triad of chronic rhinosinusitis with nasal polyps, bronchial asthma, and hypersensitivity to nonsteroidal anti-inflammatory drugs. This article explores the current knowledge on the various pathological mechanism(s) of N-ERD-such as arachidonic acid metabolism, cysteinyl leukotrienes, prostaglandins, platelets, IgE, mast cells, eosinophils, basophils, and innate immune system-and the role of omalizumab in its management. The authors dive deep into the role of IgE in N-ERD and its potential as a therapeutic target. IgE plays a significant role in mediating allergic reactions, is intricately linked with mast cells, interacts with multiple immunopathological pathways involved in N-ERD, and tends to be elevated in patients with N-ERD. Multiple real-world studies, observational studies, and case series, as well as 2 phase III trials, have demonstrated the effectiveness of omalizumab in the management of N-ERD. For a disease with such a well-documented history, the pathophysiology of N-ERD and the most effective ways to manage it remain a mystery. With this background, the authors ask-is IgE a missing piece of the N-ERD puzzle, thus explaining the efficacy of omalizumab in the treatment of the disease?

Challenges in Quantifying 8-OHdG and 8-Isoprostane in Exhaled Breath Condensate

Exhaled breath condensate (EBC) has attracted substantial interest in the last few years, enabling the assessment of airway inflammation with a non-invasive method. Concentrations of 8-Hydroxydesoxyguanosine (8-OHdG) and 8-isoprostane in EBC have been suggested as candidate biomarkers for lung diseases associated with inflammation and oxidative stress. EBC is a diluted biological matrix and consequently, requires highly sensitive chemical analytic methods (picomolar range) for biomarker quantification. We developed a new liquid chromatography coupled to tandem mass spectrometry method to quantify 8-OHdG and 8-isoprostane in EBC simultaneously. We applied this novel biomarker method in EBC obtained from 10 healthy subjects, 7 asthmatic subjects, and 9 subjects with chronic obstructive pulmonary disease. Both biomarkers were below the limit of detection (LOD) despite the good sensitivity of the chemical analytical method (LOD = 0.5 pg/mL for 8-OHdG; 1 pg/mL for 8-isoprostane). This lack of detection might result from factors affecting EBC collections. These findings are in line with methodological concerns already raised regarding the reliability of EBC collection for quantification of 8-OHdG and 8-isoprostane. Precaution is therefore needed when comparing literature results without considering methodological issues relative to EBC collection and analysis. Loss of analyte during EBC collection procedures still needs to be resolved before using these oxidative stress biomarkers in EBC.

The roles of lipid mediators in type I hypersensitivity

Type I hypersensitivity is an immediate immune reaction that involves IgE-mediated activation of mast cells. Activated mast cells release chemical mediators, such as histamine and lipid mediators, which cause allergic reactions. Recent developments in detection devices have revealed that mast cells simultaneously release a wide variety of lipid mediators. Mounting evidence has revealed that mast cell-derived mediators exert both pro- and anti-inflammatory functions and positively and negatively regulate the development of allergic inflammation. This review presents the roles of major lipid mediators released from mast cells. Author believes this review will be helpful for a better understanding of the pathogenesis of allergic diseases and provide a new strategy for the diagnosis and treatment of allergic reactions.

Eicosanoids and Eosinophilic Inflammation of Airways in Stable COPD

Purpose

Lipid mediators, particularly eicosanoids, are associated with airway inflammation, especially with the eosinophilic influx. This study aimed to measure lipid mediators and cells in induced sputum, that could possibly reflect the inflammatory process in the bronchial tree of COPD subjects.

Patients and Methods

Eighty patients diagnosed with COPD and 37 healthy controls participated in the study. Induced sputum samples were ascertained for differential cell count and induced sputum supernatant concentrations of selected eicosanoids by the means of gas chromatography/mass spectrometry and high-performance liquid chromatography/tandem mass spectrometry.

Results

Increased sputum eosinophilia was associated with higher concentrations of selected proinflammatory eicosanoids. In COPD subjects prostaglandin D₂ and 11-dehydro-thromboxane B₂ correlated negatively with airway obstruction measured by FEV₁ and FEV₁/FVC values. COPD subjects with disease exacerbations during past 12 months had significantly higher concentrations of prostaglandin D₂, 12-oxo-eicosatetraenoic acid and 5-oxo-eicosatetraenoic acid.

Conclusion

Stable COPD is often associated with eosinophil influx in the lower airways and elevated concentrations of eicosanoids that is reflected by some disease characteristics.

Mass Spectrometry-based Metabolomics in Translational Research

Metabolomics is the systematic study of metabolite profiles of complex biological systems, and involves the systematic identification and quantification of metabolites. Metabolism is integrated with all biochemical reactions in biological systems; thus metabolite profiles provide collective information on biochemical processes induced by genetic or environmental perturbations. Transcriptomes or proteomes may not be functionally active and not always reflect phenotypic variations. The metabolome, however, consists of the biomolecules closest to the phenotype of living organisms, and is often called the molecular phenotype of biological systems. Thus, metabolome alterations can easily result in disease states, providing important clues to understand pathophysiological mechanisms contributing to various biomedical symptoms. The metabolome and metabolomics have been emphasized in translational research related to biomarker discovery, drug target discovery, drug responses, and disease mechanisms. This review describes the basic concepts, workflows, and applications of mass spectrometry-based metabolomics in translational research.

Current perspective on eicosanoids in asthma and allergic diseases: EAACI Task Force consensus report, part I

Eicosanoids are biologically active lipid mediators, comprising prostaglandins, leukotrienes, thromboxanes, and lipoxins, involved in several pathophysiological processes relevant to asthma, allergies, and allied diseases. Prostaglandins and leukotrienes are the most studied eicosanoids and established inducers of airway pathophysiology including bronchoconstriction and airway inflammation. Drugs inhibiting the synthesis of lipid mediators or their effects, such as leukotriene synthesis inhibitors, leukotriene receptors antagonists, and more recently prostaglandin D₂ receptor antagonists, have been shown to modulate features of asthma and allergic diseases. This review, produced by an European Academy of Allergy and Clinical Immunology (EAACI) task force, highlights our current understanding of eicosanoid biology and its role in mediating human pathology, with a focus on new findings relevant for clinical practice, development of novel therapeutics, and future research opportunities.

Heterogeneity of lower airway inflammation in patients with NSAID-exacerbated respiratory disease

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (N-ERD) asthma is characterized by chronic rhinosinusitis and intolerance of aspirin and other COX1 inhibitors. Clinical data point to a heterogeneity within the N-ERD phenotype.

OBJECTIVE

Our aim was to investigate immune mediator profiles in the lower airways of patients with N-ERD.

METHODS

Levels of cytokines (determined by using Luminex assay) and eicosanoids (determined by using mass spectrometry) were measured in bronchoalveolar lavage fluid (BALF) from patients with N-ERD (n = 22), patients with NSAID-tolerant asthma (n = 21), and control subjects (n = 11). mRNA expression in BALF cells was quantified by using TaqMan low-density arrays.

RESULTS

Lower airway eosinophilia was more frequent in N-ERD (54.5%) than in NSAID-tolerant asthma (9.5% [P = .009]). The type-2 (T2) immune signature of BALF cells was more pronounced in the eosinophilic subphenotype of N-ERD. Similarly, BALF concentrations of periostin and CCL26 were significantly increased in eosinophilic N-ERD and correlated with T2 signature in BALF cells. Multiparameter analysis of BALF mediators of all patients with asthma revealed the presence of 2 immune endotypes: T2-like (with an elevated level of periostin in BALF) and non-T2/proinflammatory (with higher levels of matrix metalloproteinases and inflammatory cytokines). Patients with N-ERD were classified mostly as having the T2 endotype (68%). Changes in eicosanoid profile (eg, increased leukotriene E₄ level) were limited to patients with N-ERD with airway eosinophilia. Blood eosinophilia appeared to be a useful predictor of airway T2 signature (area under the curve [AUC] = 0.83); however, surrogate biomarkers had moderate performance in distinguishing eosinophilic N-ERD (for blood eosinophils, AUC = 0.72; for periostin, AUC = 0.75).

CONCLUSIONS

Lower airway immune profiles show considerable heterogeneity of N-ERD, with skewing toward T2 response and eosinophilic inflammation. Increased production of leukotriene E₄ was restricted to a subgroup of patients with eosinophilia in the lower airway.

Macromolecular biomarkers of chronic obstructive pulmonary disease in exhaled breath condensate

Biomarkers provide important diagnostic and prognostic information on heterogeneous diseases such as chronic obstructive pulmonary disease (COPD). However, finding a suitable specimen for clinical analysis of biomarkers for COPD is challenging. Exhaled breath condensate (EBC) sampling is noninvasive, rapid, cost-effective and easily repeatable. EBC sampling has also provided recent progress in the identification of biological macromolecules, such as lipids, proteins and DNA in EBC samples, which has increased its utility for clinical scientists. In this article, we review applications involving EBC sampling for the analysis of COPD biomarkers and discuss its future potential.

Reference Ranges of 8-Isoprostane Concentrations in Exhaled Breath Condensate (EBC): A Systematic Review and Meta-Analysis

Isoprostanes are physiopathologic mediators of oxidative stress, resulting in lipid peroxidation. 8-isoprostane seems particularly useful for measuring oxidative stress damage. However, no reference range values are available for 8-isoprosante in exhaled breath condensate (EBC) of healthy adults, enabling its meaningful interpretation as a biomarker. We conducted this systematic review and meta-analysis according to the protocol following PROSPERO (CRD42020146623). After searching and analyzing the literature, we included 86 studies. After their qualitative synthesis and risk of bias assessment, 52 studies were included in meta-analysis. The latter focused on studies using immunological analytical methods and investigated how the concentrations of 8-isoprostane differ based on gender. We found that gender had no significant effect in 8-isoprostane concentration. Among other studied factors, such as individual characteristics and factors related to EBC collection, only the device used for EBC collection significantly affected measured 8-isoprostane concentrations. However, adjustment for the factors related to EBC collection, yielded uncertainty whether this effect is due to the device itself or to the other factors. Given this uncertainty, we estimated the reference range values of 8-isoprostane stratified by gender and EBC collection device. A better standardization of EBC collection seems necessary; as well more studies using chemical analytical methods to extend this investigation.

Metabolomics of Exhaled Breath Condensate by Nuclear Magnetic Resonance Spectroscopy and Mass Spectrometry: A Methodological Approach

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Respiratory diseases present a very high prevalence in the general population, with an increase in morbidity, mortality and health-care expenses worldwide. They are complex and heterogeneous pathologies that may present different pathological facets in different subjects, often with personal evolution. Therefore, there is a need to identify patients with similar characteristics, prognosis or treatment, defining the so-called phenotype, but also to mark specific differences within each phenotype, defining the endotypes.

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Biomarkers are very useful to study respiratory phenotypes and endotypes. Metabolomics, one of the recently introduced “omics”, is becoming a leading technique for biomarker discovery. For the airways, metabolomics appears to be well suited as the respiratory tract offers a natural matrix, the Exhaled Breath Condensate (EBC), in which several biomarkers can be measured. In this review, we will discuss the main methodological issues related to the application of Nuclear Magnetic Resonance (NMR) spectroscopy and Mass Spectrometry (MS) to EBC metabolomics for investigating respiratory diseases.

The roles of omega-3 fatty acids and resolvins in allergic conjunctivitis

PURPOSE OF REVIEW

Lipids are one of the most important constituents in our body. Advances of lipidomics are elucidating the new roles of various lipid molecules in allergic diseases. For example, some reports showed anti-inflammatory effects of omega-3 fatty acids (FAs), such as docosahexaenoic acid, eicosapentaenoic acid, and their metabolites, on allergic diseases. Here, we introduce the role of lipid mediators in allergic conjunctivitis mouse model.

RECENT FINDINGS

Lipidomics using liquid chromatography-tandem mass spectrometry can profile numerous lipid molecules from small tissue samples such as conjunctival specimens. Lipidomics analysis showed that various inflammatory lipid mediators are produced in the conjunctival tissue of allergic conjunctivitis mouse model. Dietary omega-3 FAs reduced these inflammatory lipid mediators in the conjunctiva and alleviated allergic conjunctivitis symptoms in mouse models. In addition, the roles of specialized proresolving lipid mediators (SPMs) have been reported for allergic inflammation.

SUMMARY

Lipid mediators have important roles for the pathophysiology of the allergic diseases including allergic conjunctivitis. Omega-3 FAs and SPMs are expected as new treatment tools for allergic conjunctivitis.

Aspirin-exacerbated respiratory disease (AERD): Current understanding of AERD

The characteristics in AERD are severe adult-onset asthma, eosinophilic rhinosinusitis with nasal polyposis, and CysLT overproduction. The cause of AERD have remained unclear, however the decrease in the production of PGE2 caused by the reduction in COX-2 activity is considered to main pathological mechanism of AERD. The mast cell activation and the interaction between platelets and granulocytes are lead to the CysLT overproduction and severe eosinophilic inflammation. The ongoing activation of mast cells is important key pathogenesis in not only stable AERD but exacerbated AERD by aspirin and NSAIDs. In recent years, type 2 inflammation caused by ILC2 activation in patients with AERD have been attracting attention. Omalizumab is effective option for AERD via suppression of mast cell activation and CysLT overproduction. Dupilumab improves sinus symptoms especially in patients with AERD. In near future, anti-platelet drug, CRTH2 antagonist, and anti-TSLP antibody may be useful candidates of therapeutic options in patients with AERD.

Eicosanoid mediator profiles in different phenotypes of nonsteroidal anti-inflammatory drug-induced urticaria

BACKGROUND

The role of arachidonic acid metabolites in NSAID-induced hypersensitivity has been studied in depth for NSAID-exacerbated respiratory disease (NERD) and NSAID-exacerbated cutaneous disease (NECD). However, no information is available for NSAID-induced urticarial/angioedema (NIUA), despite it being the most frequent clinical entity induced by NSAID hypersensitivity. We evaluated changes in leukotriene and prostaglandin metabolites for NIUA patients, using patients with NECD and single-NSAID-induced urticaria/angioedema or anaphylaxis (SNIUAA) for comparison.

METHODS

Urine samples were taken from patients with confirmed NSAID-induced urticaria and healthy controls, at baseline and at various time intervals after ASA administration. Eicosanoid measurement was performed using high-performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.

RESULTS

No differences were found between groups at baseline. Following ASA administration, LTE4 and 9α,11β-PGF2 levels were increased in both NIUA and NECD patients compared to baseline, rising initially, before decreasing toward initial levels. In addition, the levels of these metabolites were higher in NIUA and NECD when compared with the SNIUAA and control groups after ASA administration. No changes were found with respect to baseline values for SNIUAA and control groups.

CONCLUSIONS

We present for the first time data regarding the role of COX-1 inhibition in NIUA. Patients with this entity show a similar pattern eicosanoid levels following ASA challenge to those with NECD. Further studies will help ascertain the cell populations involved and the underlying molecular mechanisms.

Aspirin exacerbated respiratory disease: Current topics and trends

Aspirin-exacerbated respiratory disease is a chronic and treatment-resistant disease, characterized by the presence of eosinophilic rhinosinusitis, nasal polyposis, bronchial asthma, and nonsteroidal anti-inflammatory drugs hypersensitivity. Alterations in arachidonic acid metabolism may induce an imbalance between pro-inflammatory and anti-inflammatory substances, expressed as an overproduction of cysteinyl leukotrienes and an underproduction of prostaglandin E2. Although eosinophils play a key role, recent studies have shown the importance of other cells and molecules in the development of the disease like mast cells, basophils, lymphocytes, platelets, neutrophils, macrophages, epithelial respiratory cells, IL-33 and thymic stromal lymphopoietin, making each of them promissory diagnostic and treatment targets. In this review, we summarize the most important clinical aspects of the disease, including the current topics about diagnosis and treatment, like provocation challenges and aspirin desensitization. We also discuss recent findings in the pathogenesis of the disease, as well as future trends in diagnosis and treatment, including monoclonal antibodies and a low salicylate diet as a treatment option.

Future Horizons in Allergy

There are several advances in diagnosis and management for the otolaryngologist treating allergy. These include new technologies and the refinement of current techniques, and reflect overall trends in health care toward personalized medicine. Local immunoglobulin, urinary leukotriene E4, lipidomics, microRNA within extracellular vesicles, and optical rhinometry all offer to improve the diagnostic accuracy of allergy and related nonallergic conditions. New delivery systems for intranasal steroids and antihistamines, recombinant allergens, advances in allergen immunotherapy delivery, and biologics will improve current management options. These developments will aid the otolaryngologist in diagnosing and treating allergy and related diseases.

Derivatization enhanced separation and sensitivity of long chain-free fatty acids: Application to asthma using targeted and non-targeted liquid chromatography-mass spectrometry approach

Long chain-free fatty acids (LCFFAs) play pivotal roles in various physiological functions, like inflammation, insulin resistance, hypertension, immune cell behavior and other biological activities. However, the detection is obstructed by the low contents, structural diversity, high structural similarity, and matrix interference. Herein, a fast cholamine-derivatization, within 1 min at room temperature, coupled with liquid chromatography-mass spectrometry (LC-MS) approach was developed to determine LCFFAs in complex samples. After derivatization, the ionization and separation efficiency were significantly improved, which resulted in up to 2000-fold increase of sensitivity compared with non-derivatization method, and the limits of detection were at low femtogram level. As well, this approach was applied successfully in the rapid profiling or quantification of targeted and non-targeted LCFFAs in the sera of healthy human and asthma patients. The targeted metabolomics method showed that the contents of 17 PUFAs were significantly changed in asthma patients, especially hydroxyeicosatetraenoic acids (HETEs), hydroperoxyeicosatetraenoic acid (HPETEs) and prostaglandins (PGs). The non-targeted method resulted in the tentatively identification of 35 LCFFAs including 31 saturated and mono-unsaturated LCFFAs, and 4 bile acids, except for 27 poly-unsaturated fatty acids (PUFAs), and the multivariate analysis indicated that eicosapentaenoic acid (EPA), ursodeoxycholic acid, deoxycholic acid, isodeoxycholic acid, palmitic acid, 2-lauroleic acid and lauric acid also have significant difference between healthy and asthma groups except for 17 PUFAs. To the best of our knowledge, this is the first report on the relationship of asthma with 5(S)-, 15(S)-HPETE, 8(S)-, 11(S)-HETE, 15(S)-HEPE, PGA2, PGB2, PGE1, PGF1α, PGJ2, and 13, 14-dehydro-15-keto PGF2α (DK-PGF2α).

Probiotic Lactobacillus acidophilus bacteria or synthetic TLR2 agonist boost the growth of chicken embryo intestinal organoids in cultures comprising epithelial cells and myofibroblasts

The intestinal epithelial cells reside in close proximity to myofibroblasts and microbiota, which are supposed to have an impact on intestinal stem cells fate and to influence processes of tissue maturation and regeneration. Mechanism underlying these phenomena and their diversity among vertebrates can be studied in 3D organoid cultures. We investigated the growth of chicken embryo intestinal epithelial organoids in Matrigel with and without Toll-like receptors (TLRs) stimulation. The organoid cultures contained also some myofibroblasts with potential to promote intestinal stem cell survival. Organoid cells, expressing TLR4, TLR2 type 1 and TLR2 type 2 were incubated with their agonists (lipopolysaccharide - LPS and Pam3CSK4) or co-cultured with Lactobacillus acidophilus bacteria (LA-5). Pam3CSK4 and LA-5 promoted organoid growth, which was demonstrated by comparing the morphological parameters (mean number and area of organoids). The profile of prostaglandins (PG), known to promote intestinal regeneration, in supernatants from organoid and fibroblast cultures were evaluated. Both PGE₂ and PGD₂ were detected. As compared to unstimulated controls, supernatants from the Pam3CSK4-stimulated organoids contained twice as much of PGE₂ and PGD₂. The changes in production of prostaglandins and the support of epithelial cell growth by myofibroblasts are factors potentially responsible for stimulatory effect of TLR2 activation.

A European Respiratory Society technical standard: exhaled biomarkers in lung disease

Breath tests cover the fraction of nitric oxide in expired gas (F_eNO), volatile organic compounds (VOCs), variables in exhaled breath condensate (EBC) and other measurements. For EBC and for F_eNO, official recommendations for standardised procedures are more than 10 years old and there is none for exhaled VOCs and particles. The aim of this document is to provide technical standards and recommendations for sample collection and analytic approaches and to highlight future research priorities in the field. For EBC and F_eNO, new developments and advances in technology have been evaluated in the current document. This report is not intended to provide clinical guidance on disease diagnosis and management.Clinicians and researchers with expertise in exhaled biomarkers were invited to participate. Published studies regarding methodology of breath tests were selected, discussed and evaluated in a consensus-based manner by the Task Force members.Recommendations for standardisation of sampling, analysing and reporting of data and suggestions for research to cover gaps in the evidence have been created and summarised.Application of breath biomarker measurement in a standardised manner will provide comparable results, thereby facilitating the potential use of these biomarkers in clinical practice.

Metabolomic analysis identifies potential diagnostic biomarkers for aspirin-exacerbated respiratory disease

BACKGROUND

To date, there has been no reliable in vitro test to diagnose aspirin-exacerbated respiratory disease (AERD).

OBJECTIVE

To investigate potential diagnostic biomarkers for AERD using metabolomic analysis.

METHODS

An untargeted profile of serum from asthmatics in the first cohort (group 1) comprising 45 AERD, 44 patients with aspirin-tolerant asthma (ATA), and 28 normal controls was developed using the ultra-high-performance liquid chromatography (UHPLC)/Q-ToF MS system. Metabolites that discriminate AERD from ATA were quantified in both serum and urine, which were collected before (baseline) and after the lysine-aspirin bronchoprovocation test (Lys-ASA BPT). The serum metabolites were validated in the second cohort (group 2) comprising 50 patients with AERD and 50 patients with ATA.

RESULTS

A clear discrimination of metabolomes was found between patients with AERD and ATA. In group 1, serum levels of LTE₄ and LTE₄ /PGF₂ α ratio before and after the Lys-ASA BPT were significantly higher in patients with AERD than in patients with ATA (P < 0.05 for each), and urine baseline levels of these two metabolites were significantly higher in patients with AERD. Significant differences of serum metabolite levels between patients with AERD and ATA were replicated in group 2 (P < 0.05 for each). Moreover, serum baseline levels of LTE₄ and LTE₄ /PGF₂ α ratio discriminated AERD from ATA with 70.5%/71.6% sensitivity and 41.5%/62.8% specificity, respectively (AUC = 0.649 and 0.732, respectively P < 0.001 for each). Urine baseline LTE₄ levels were significantly correlated with the fall in FEV₁ % after the Lys-ASA BPT in patients with AERD (P = 0.008, r = 0.463).

CONCLUSIONS AND CLINICAL RELEVANCE

Serum metabolite level of LTE₄ and LTE₄ /PGF₂ α ratio was identified as potential in vitro diagnostic biomarkers for AERD using the UHPLC/Q-ToF MS system, which were closely associated with major pathogenetic mechanisms underlying AERD.

Induced sputum supernatant bioactive lipid mediators can identify subtypes of asthma

BACKGROUND

Induced sputum (IS) allows to measure mediators of asthmatic inflammation in bronchial secretions. The specific role of induced sputum supernatant (ISS) endogenous bioactive lipid mediators in subtypes of asthma is not well understood.

OBJECTIVE

To investigate the interactions between airway inflammation and clinical phenotypes of asthma, we integrated induced sputum supernatant (ISS) eicosanoids and quantitative assessment of infiltrating cells into new subtypes with the means of latent class analysis (LCA).

METHODS

One hundred and thirty-nine asthmatics with and without aspirin hypersensitivity underwent sputum induction. High-performance liquid chromatography or gas chromatography coupled with mass spectrometry was used to profile eicosanoids. Nineteen variables covering clinical characteristics, IS inflammatory cells and eicosanoids were considered in the LCA.

RESULTS

Four phenotypic asthma classes were distinguished. Class 1 with mild-to-moderate asthma, chronic rhinosinusitis (CRS), high PGA2 in ISS and almost equal distribution of inflammation cell patterns. Class 3 subjects also had mild-to-moderate asthma but without upper airway symptoms. Induced sputum was often paucigranulocytic with low levels of lipid mediators. Classes 2 and 4 represented severe asthma with CRS and impaired lung function despite high doses of steroids. High blood and sputum eosinophilia was in line with high cysteinyl leukotrienes and PGD2 in ISS only in class 2. Class 4 subjects tended to have increased sputum neutrophilia and PGE2 in ISS. Aspirin hypersensitivity was most frequent among class 2 subjects.

CONCLUSIONS & CLINICAL RELEVANCE

The LCA revealed four distinct asthma classes differing in eicosanoid pathways.

Dynamic model of eicosanoid production with special reference to non-steroidal anti-inflammatory drug-triggered hypersensitivity

The authors developed a mathematical model of arachidonic acid (AA) degradation to prostaglandins (PGs) and leukotrienes (LTs), which are implicated in the processes of inflammation and hypersensitivity to non-steroidal anti-inflammatory drugs (NSAIDs). The model focuses on two PGs (PGE2 and PGD2) and one LT (LTC4), their % increases and their ratios. Results are compared with experimental studies obtained from non-asthmatics (NAs), and asthmatics tolerant (ATA) or intolerant (AIA) to aspirin. Simulations are carried out for predefined model populations NA, ATA and three AIA, based on the differences of two enzymes, PG E synthase and/or LTC4-synthase in two states, that is, no-inflammation and inflammation. Their model reveals that the model population with concomitant malfunctions in both enzymes is the most sensitive to NSAIDs, since the duration and the capacity for bronchoconstriction risk are highest after simulated oral dosing of indomethacin. Furthermore, inflammation prolongs the duration of the bronchoconstriction risk in all AIA model populations, and the sensitivity analysis reveals multiple possible scenarios leading to hypersensitivity, especially if inflammatory processes affect the expression of multiple enzymes of the AA metabolic pathway. Their model estimates the expected fold-changes in enzyme activities and gives valuable information for further targeted transcriptomic/proteomic and metabolomic studies.

Hypersensitivity to Aspirin and other NSAIDs: Diagnostic Approach in Patients with Chronic Rhinosinusitis

Hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs) associated with chronic rhinosinusitis (CRS) and/or asthma comprises a distinct clinical syndrome referred to as NSAIDs exacerbated respiratory disease (NERD). Patients with NERD tend to have more severe course of both upper (CRS and nasal polyps) and lower airway (asthma) diseases and are usually recalcitrant to conventional treatment modalities. Diagnosing and phenotyping of patients with NERD are critical for prevention of drug-induced adverse reactions and open novel options for management of underlying chronic airway inflammatory diseases. Diagnosis of NERD is based on detailed clinical history confirmed by challenge with aspirin, but new diagnostic approaches are currently being developed. This review article focuses on the diagnostic approach to a patient with CRS and hypersensitivity to NSAIDs, emphasizing the importance of diagnosis for proper patient's management.

Aspirin-intolerant asthma in the population: prevalence and important determinants

BACKGROUND

Population-based studies on aspirin-intolerant asthma (AIA) are very few, and no previous population study has investigated risk factors for the condition.

OBJECTIVE

To investigate the prevalence and risk factors of AIA in the general population.

METHODS

A questionnaire on respiratory health was mailed to 30,000 randomly selected subjects aged 16-75 years in West Sweden, 29,218 could be traced and 18,087 (62%) responded. The questionnaire included questions on asthma, respiratory symptoms, aspirin-induced dyspnoea and possible determinants.

RESULTS

The prevalence of AIA was 0.5%, 0.3% in men and 0.6% in women (P = 0.014). Sick leave, emergency visits due to asthma and all investigated lower respiratory symptoms were more common in AIA than in aspirin-tolerant asthma (ATA). Obesity was a strong risk factor for AIA (BMI > 35: odds ratio (OR) 12.1; 95% CI 2.49-58.5), and there was a dose-response relationship between increasing body mass index (BMI) and risk of AIA. Obesity, airborne occupational exposure and visible mould at home were considerably stronger risk factors for AIA than for ATA. Current smoking was a risk factor for AIA (OR 2.55; 95% CI 1.47-4.42), but not ATA.

CONCLUSION

Aspirin-intolerant asthma identified in the general population was associated with a high burden of symptoms, uncontrolled disease and a high morbidity. Increasing BMI increased the risk of AIA in a dose-response manner. A number of risk factors, including obesity and current smoking, were considerably stronger for AIA than for ATA.

Lipidomics: Novel insight into the biochemical mechanism of lipid metabolism and dysregulation-associated disease

The application of lipidomics, after genomics, proteomics and metabolomics, offered largely opportunities to illuminate the entire spectrum of lipidome based on a quantitative or semi-quantitative level in a biological system. When combined with advances in proteomics and metabolomics high-throughput platforms, lipidomics provided the opportunity for analyzing the unique roles of specific lipids in complex cellular processes. Abnormal lipid metabolism was demonstrated to be greatly implicated in many human lifestyle-related diseases. In this review, we focused on lipidomic applications in brain injury disease, cancer, metabolic disease, cardiovascular disease, respiratory disease and infectious disease to discover disease biomarkers and illustrate biochemical metabolic pathways. We also discussed the analytical techniques, future perspectives and potential problems of lipidomic applications. The application of lipidomics in disease biomarker discovery provides the opportunity for gaining novel insights into biochemical mechanism.

Aspirin provocation increases 8-iso-PGE2 in exhaled breath condensate of aspirin-hypersensitive asthmatics

BACKGROUND

Isoprostanes are bioactive compounds formed by non-enzymatic oxidation of polyunsaturated fatty acids, mostly arachidonic, and markers of free radical generation during inflammation. In aspirin exacerbated respiratory disease (AERD), asthmatic symptoms are precipitated by ingestion of non-steroid anti-inflammatory drugs capable for pharmacologic inhibition of cyclooxygenase-1 isoenzyme. We investigated whether aspirin-provoked bronchoconstriction is accompanied by changes of isoprostanes in exhaled breath condensate (EBC).

METHODS

EBC was collected from 28 AERD subjects and 25 aspirin-tolerant asthmatics before and after inhalatory aspirin challenge. Concentrations of 8-iso-PGF2α, 8-iso-PGE2, and prostaglandin E2 were measured using gas chromatography/mass spectrometry. Leukotriene E4 was measured by immunoassay in urine samples collected before and after the challenge.

RESULTS

Before the challenge, exhaled 8-iso-PGF2α, 8-iso-PGE2, and PGE2 levels did not differ between the study groups. 8-iso-PGE2 level increased in AERD group only (p=0.014) as a result of the aspirin challenge. Urinary LTE4 was elevated in AERD, both in baseline and post-challenge samples. Post-challenge airways 8-iso-PGE2 correlated positively with urinary LTE4 level (p=0.046), whereas it correlated negatively with the provocative dose of aspirin (p=0.027).

CONCLUSION

A significant increase of exhaled 8-iso-PGE2 after inhalatory challenge with aspirin was selective and not present for the other isoprostane measured. This is a novel finding in AERD, suggesting that inhibition of cyclooxygenase may elicit 8-iso-PGE2 production in a specific mechanism, contributing to bronchoconstriction and systemic overproduction of cysteinyl leukotrienes.

9α,11β-PGF2, a Prostaglandin D2 Metabolite, as a Marker of Mast Cell Activation in Bee Venom-Allergic Patients

Mast cell (MC) mediators, among them prostaglandin D₂ (PGD₂) and 9α,11β-PGF₂, PGD₂’s metabolite, play a key role in allergic reactions, including bee venom anaphylaxis (BVA). Assessment of these mediators has never been performed in BVA. The aim of the study was to assess the activation of MC during in vivo provocation with bee venom (BV) and to measure PGD₂ and 9α,11β-PGF₂ in the course of an allergen challenge. The second aim was to determine if assessment of these mediators could be useful for predicting adverse events during venom immunotherapy (VIT). In 16 BV-VIT patients and 12 healthy subjects, levels of PGD₂ and 9α,11β-PGF₂ were assessed during BV provocation by means of the skin chamber method. Chamber fluids, collected at 5 and 15 min, were analyzed for both mediators by gas chromatography mass spectrometry negative ion chemical ionization. BVA in comparison to non-allergic patients had a significantly higher ratio of 9α,11β-PGF₂ in allergen-challenged chambers to 9α,11β-PGF₂ in allergen-free chambers after 15 min of provocation (p = 0.039). Allergen challenge resulted in a significant increase of 9α,11β-PGF₂ levels between 5 and 15 min after provocation only in BVA patients (p < 0.05). Analysis of log-transformed PGD2 levels showed significant difference between changes in PGD₂ concentration between BVA and healthy subjects. No study patient developed adverse reactions during. 9α,11β-PGF₂ is actively generated during the early allergic response to BV. Skin chamber seems to be a promising, non-invasive and safe model of in vivo allergen provocation in BV-allergic patients. High or low levels of both mediators do not predict occurrence of adverse events during VIT.

Induced sputum eicosanoids during aspirin bronchial challenge of asthmatic patients with aspirin hypersensitivity

BACKGROUND

Altered metabolism of eicosanoids is a characteristic finding in aspirin-exacerbated respiratory disease (AERD). Bronchial challenge with lysyl-aspirin can be used as a confirmatory diagnostic test for this clinical condition. Induced sputum allows to measure mediators of asthmatic inflammation in bronchial secretions.

OBJECTIVES

To investigate the influence of inhaled lysyl-aspirin on sputum supernatant concentration of eicosanoids during the bronchial challenge test. Subjects with asthma hypersensitive to nonsteroidal anti-inflammatory drugs were compared with aspirin-tolerant asthmatic controls.

METHODS

Induced sputum was collected before and following bronchial challenge with lysyl-aspirin. Sputum differential cell count and sputum supernatant concentrations of selected lipoxygenases products: 5-,12-,15-hydroxyeicosatetraenoic acid, cysteinyl leukotrienes, leukotriene B4 , 11-dehydro-thromboxane B2 , and prostaglandins E2 , D2 , and F2α and their metabolites, were measured using validated methods of chromatography-mass spectrometry.

RESULTS

Aspirin precipitated bronchoconstriction in all AERD subjects, but in none of the aspirin-tolerant asthmatics. Phenotypes of asthma based on the sputum cytology did not differ between the groups. Baseline sputum eosinophilia correlated with a higher leukotriene D4 (LTD4 ) and leukotriene E4 (LTE4 ) concentrations. LTC4 , PGE2 , and 11-dehydro-TXB2 did not differ between the groups, but levels of LTD4 , LTE4 , and PGD2 were significantly higher in AERD group. Following the challenge, LTD4 and LTE4 increased, while PGE2 and LTB4 decreased in AERD subjects only.

CONCLUSIONS

During the bronchial challenge, decrease in PGE2 and its metabolite is accompanied by a surge in bronchoconstrictory cysteinyl leukotrienes produced at the expense of LTB4 in AERD subjects. Bronchial PGE2 inhibition in AERD seems specific and sensitive to a low dose of aspirin.

Th2-type cytokine-induced mucus metaplasia decreases susceptibility of human bronchial epithelium to rhinovirus infection

Human rhinoviruses (RVs) are a major cause of exacerbations in asthma and other chronic airway diseases. A characteristic feature of asthmatic epithelium is goblet cell metaplasia and mucus hypersecretion. Bronchial epithelium is also an important source of lipid mediators, including pro- and antiinflammatory eicosanoids. By using air-liquid interface cultures of airway epithelium from patients with asthma and nonasthmatic control subjects, we compared RV16 replication-induced changes in mRNA expression of asthma candidate genes and eicosanoid production in the epithelium with or without IL-13-induced mucus metaplasia. Mucus metaplastic epithelium was characterized by a 20-fold less effective replication of RV16 and blunted changes in gene expression; this effect was seen to the same extent in patients with asthma and control subjects. We identified ciliary cells as the main target for RV16 by immunofluorescence imaging and demonstrated that the numbers of ciliary cells decreased in RV16-infected epithelium. RV16 infection of mucociliary epithelium resulted in overexpression of genes associated with bronchial remodeling (e.g., MUC5AC, FGF2, and HBEGF), induction of cyclooxygenase-2, and increased secretion of prostaglandins. These responses were similar in both studied groups. These data indicate that structural changes associated with mucus metaplasia renders airway epithelium less susceptible to RV infection. Thus, exacerbations of the lung disease caused by RV may result from severe impairment in mucociliary clearance or activation of immune defense rather than from preferential infection of mucus metaplastic epithelium. Repeated rhinoviral infections of compromised epithelium may contribute to the remodeling of the airways.

Aspirin-intolerant asthma: a comprehensive review of biomarkers and pathophysiology

Aspirin-exacerbated respiratory disease is a tetrad of nasal polyps, chronic hypertrophic eosinophilic sinusitis, asthma, and sensitivity to aspirin. Unawareness of this clinical condition by patients and physicians may have grave consequences because of its association with near-fatal asthma. The pathogenesis of aspirin-intolerant asthma is not related with an immunoglobin E mechanism, but with an abnormal metabolism of the lipoxygenase (LO) and cyclooxygenase (COX) pathways. At present, a diagnosis of aspirin sensitivity can be established only by provocative aspirin challenge, which represents a health risk for the patient. This circumstance has encouraged the search for aspirin intolerance-specific biomarkers. Major attempts have focused on mediators related with inflammation and eicosanoid regulation. The use of modern laboratory techniques including high-throughput methods has facilitated the detection of dozens of biological metabolites associated with aspirin-intolerant asthma disease. Not surprisingly, the majority of these is implicated in the LO and COX pathways. However, substantial amounts of data reveal the participation of many genes deriving from different ontologies. Biomarkers may represent a powerful, noninvasive tool in the diagnosis of aspirin sensitivity; moreover, they could provide a new way to classify asthma phenotypes.

Liquid chromatography-mass spectrometry measurement of leukotrienes in asthma and other respiratory diseases

Leukotrienes (LTs), including cysteinyl-LTs (LTC4, LTD4 and LTE4) and LTB4, are potent inflammatory lipid mediators which have been involved in the pathophysiology of respiratory diseases. LC-MS/MS techniques for measuring LT concentrations in sputum supernatants, serum, urine and exhaled breath condensate (EBC) have been developed. In asthmatic adults, reported LTB4 and LTE4 concentrations in sputum range from 79 to 7,220 pg/ml and from 11.9 to 891 pg/ml, respectively. Data on sputum LT concentrations in healthy subjects are not available. In EBC, reported LTE4 concentrations range from 38 to 126 pg/ml (95% CI) in adult asthma patients and from 34 to 48 pg/ml in healthy subjects. LTB4 concentrations in EBC range from 175 to 315 pg/ml (interquartile range) in asthmatic children, and from 25 to 245 pg/ml in healthy children. Enabling an accurate quantitative assessment of LTs in biological fluids, LC-MS/MS techniques provide a valuable tool for exploring the pathophysiological role of LTs in respiratory disease and might be useful for assessing the effects of therapeutic intervention. This review presents the analytical aspects of the LC-MS/MS techniques for measuring LT concentrations in biological fluids and discusses their potential utility for the assessment of airway inflammation and monitoring of pharmacological treatment in patients with asthma phenotypes and other respiratory diseases.

Variants of CEP68 gene are associated with acute urticaria/angioedema induced by multiple non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most consumed drugs worldwide because of their efficacy and utility in the treatment of pain and inflammatory diseases. However, they are also responsible for an important number of adverse effects including hypersensitivity reactions. The most important group of these reactions is triggered by non-immunological, pharmacological mechanisms catalogued under the denomination of cross-intolerance (CRI), with acute urticaria/angioedema induced by multiple NSAIDs (MNSAID-UA) the most frequently associated clinical entity. A recent genome-wide association study identified the gene encoding the centrosomal protein of 68 KDa (CEP68) as the major locus associated with aspirin intolerance susceptibility in asthmatics. In this study, we aimed to assess the role of this locus in susceptibility to CRI to NSAIDs by examining 53 common gene variants in a total of 635 patients that were classified as MNSAID-UA (n = 399), airway exacerbations (n = 110) or blended pattern (n = 126), and 425 controls. We found in the MNSAID-UA group a number of variants (17) associated (lowest p-value = 1.13×10⁻⁶), including the non-synonymous Gly74Ser variant (rs7572857) previously associated with aspirin intolerance susceptibility in asthmatics. Although not being significant in the context of multiple testing, eight of these variants were also associated with exacerbated respiratory disease or blended reactions. Our results suggest that CEP68 gene variants may play an important role in MNSAID-UA susceptibility and, despite the different regulatory mechanisms involved depending on the specific affected organ, in the development of hypersensitivity reactions to NSAIDs.

Lipidomics applications for discovering biomarkers of diseases in clinical chemistry

Lipids are the fundamental components of biological membranes as well as the metabolites of organisms. Lipids play diverse and important roles in biologicals. The lipid imbalance is closely associated with numerous human lifestyle-related diseases, such as atherosclerosis, obesity, diabetes, and Alzheimer's disease. Lipidomics or lipid profiling is a system-based study of all lipids aiming at comprehensive analysis of lipids in the biological system. Lipidomics has been accepted as a lipid-related research tool in lipid biochemistry, clinical biomarker discovery, disease diagnosis, and in understanding disease pathology. Lipidomics will not only provide insights into the specific functions of lipid species in health and disease, but will also identify potential biomarkers for establishing preventive or therapeutic programs for human diseases. This review presents an overview of lipidomics followed by in-depth discussion of its application to the study of human diseases, including extraction methods of lipids, analytical technologies, data analysis, and clinical research in cancer, neuropsychiatric disease, cardiovascular disease, kidney disease, and respiratory disease. We describe the current status of the identification of metabolic biomarkers in different diseases. We also discuss the lipidomics for the future perspectives and their potential problems. The application of lipidomics in clinical studies may provide new insights into lipid profiling and pathophysiological mechanisms.

Genome-wide association study in NSAID-induced acute urticaria/angioedema in Spanish and Han Chinese populations

AIM

Acute urticaria/angioedema (AUA) induced by cross-intolerance to NSAIDs is the most frequent clinical entity in hypersensitivity reactions to drugs. In this work, we conducted a genome-wide association study in Spanish and Han Chinese patients suffering from NSAID-induced AUA.

MATERIALS & METHODS

A whole-genome scan was performed on a total of 232 cases (112 Spanish and 120 Han Chinese) with NSAID-induced AUA and 225 unrelated controls (124 Spanish and 101 Han Chinese).

RESULTS

Although no polymorphism reached genome-wide significance, we obtained suggestive associations for three clusters in the Spanish group (RIMS1, BICC1 and RAD51L 1) and one region in the Han Chinese population (ABI3BP). Five regions showed suggestive associations after meta-analysis: HLF, RAD51L1, COL24A1, GalNAc-T13 and FBXL7. A majority of these genes are related to Ca(2+), cAMP and/or P53 signaling pathways.

CONCLUSION

The associations described were different from those related to the metabolism of arachidonic acid and could provide new mechanisms underlying NSAID-induced AUA.

Mediator release after nasal aspirin provocation supports different phenotypes in subjects with hypersensitivity reactions to NSAIDs

BACKGROUND

Multiple NSAID-induced urticaria/angioedema (MNSAID-UA) is an entity well differentiated from aspirin-exacerbated respiratory disease (AERD), although no detailed phenotype analysis has yet been performed. The objective was to evaluate the functional characteristics of MNSAID-UA subjects by analyzing the response to nasal lysine-aspirin challenge and measurement of nasal inflammatory mediator release compared with AERD subjects and controls.

METHODS

The study included 85 subjects with confirmed hypersensitivity to NSAIDs (≥3 episodes with >2 different NSAIDs or positive drug provocation) with either cutaneous (MNSAID-UA, n = 25) or respiratory manifestations (AERD, n = 60) and 30 tolerant controls (15 aspirin-tolerant asthmatic patients and 15 healthy controls). Nasal lavages at 0, 15, 60, and 120 min after lysine-aspirin challenge were analyzed for ECP, tryptase, PGE2 , PGD2 , LTD4 , and LTE4 .

RESULTS

Lysine nasal challenge was positive in 80% of the AERD cases but positive only in 12% of the MNSAID-UA group. MNSAID-UA subjects showed no changes in nasal ECP, whereas subjects with AERD had increased levels of ECP, with the highest peak at 15 min after challenge (P < 0.05). Tryptase levels were higher in AERD compared with MNSAID-UA and controls with the highest release of tryptase at 60 min (P < 0.05). Significant increases in PGD2 , LTD4 , and LTE4 were observed in AERD (at 60 min for PGD2 , LTD4 , and LTE4 ) but not in MNSAID-UA or control subjects (P < 0.05).

CONCLUSIONS

Data support the observation that MNSAID-UA, although sharing a common response with AERD to COX inhibitors, seems to have a distinctive phenotype, based on the response to nasal challenge and the release of inflammatory mediators.

Eicosanoid biosynthesis during mucociliary and mucous metaplastic differentiation of bronchial epithelial cells

The purpose of this study was to examine the profile of eicosanoids secreted by human bronchial epithelial cells (HBEC) during their in vitro differentiation toward mucociliary or mucous metaplastic phenotype. Eicosanoids were measured in supernatants by mass spectrometry, and corresponding gene expression by real-time PCR. Primary HBEC produced mainly prostaglandins (PGE2, PGD2) and epoxides (e.g. 14,15-EET), but during further mucociliary differentiation we observed a gradual increase in secretion of lipoxygenase derived HETEs. Treatment with IL-13 and IL-4 induced mucous metaplasia and resulted in downregulation of PG pathway, and potent induction of 15-lipoxygenase (marked release of 15-HETE). The deficiency in PG production sustained during long term culture of mucous metaplastic epithelia. In conclusions, Th2-type cytokines induce changes in eicosanoid metabolism of airway epithelial cells, resulting in an immense induction of 15-lipoxygenase pathway, and inhibition of PG pathways. Deficient production of immunomodulatory PGs may promote chronic inflammation and airway remodeling.

Lipidomics applications in health, disease and nutrition research

The structural and functional diversity of lipids accounts for their involvement into a wide range of homeostatic processes and disease states, including lifestyle-related diseases as well as genetic conditions. Challenges presented by this diversity have been addressed to a great extent by the development of lipidomics, a platform that makes possible the detailed profiling and characterisation of lipid species present in any cell, organelle, tissue or body fluid, and allows for a wider appreciation of the biological role of lipid networks. Progress in the field of lipidomics has been greatly facilitated by recent advances in MS and includes a range of analytical platforms supporting applications spanning from qualitative and quantitative assessment of multiple species to lipid imaging. Here we review these MS techniques currently in routine use in lipidomics, alongside with new ones that have started making an impact in the field. Recent applications in health, disease and nutrition-related questions will also be discussed with a view to convey the importance of lipidomics contributions to biosciences and food technology.

Exhaled eicosanoid profiles in children with atopic asthma and healthy controls

RATIONALE

Chronic endobronchial inflammation is a hallmark of pediatric asthma and involves the arachidonic acid pathway. Its non-volatile metabolites can be quantified in the exhaled breath condensate (EBC), and single substances have been studied as non-invasive biomarkers for the diagnosis and monitoring of children with asthma. The aim of this study was to compare the content and profile of a wider range of eicosanoids in the EBC between patients and a control group.

MATERIALS AND METHODS

EBC was sampled from 33 children (aged 12.4 ± 3.1 years) with stable atopic asthma (26 on inhaled steroid treatment) and 25 healthy controls (11.8 ± 3.2 years). Validated high performance liquid chromatography coupled with a tandem mass spectrometry platform (HPLC-MS2 ) was used to measure 13 different compounds. In addition, exhaled nitric oxide levels (FeNO) were measured and bronchial hyperresponsiveness (BHR) was assessed by an exercise challenge test in all subjects. An analytical approach was used for multivariate regression modeling of disease status using the most relevant variables.

RESULTS

The levels of PGEM (P < 0.001), PGD2 (P < 0.001), 6keto-PGF1α (P = 0.03), LTC4 (P < 0.001), trans-LTC4 (P = 0.04), and 5HETE (P = 0.02) were significantly higher in asthmatics compared to healthy children, while 11-dehydro TXB2 was significantly less abundant (P = 0.02). The eicosanoids asthma classification ratio (EACR) was computed as the logistic regression function using four variables: PGEM, PGD2, LTC4, and 5HETE. This composite parameter discriminated asthmatic from healthy children better than FEV1, FeNO, or BHR.

CONCLUSION

Complementary measurements of PGEM, PGD2, LTC4, and 5HETE in small-volume EBC samples are feasible by HPLC-MS2 and showed a specific profile in our study population. EACR should be evaluated further in the context of diagnosing and monitoring childhood asthma.

12-hydroxy-eicosatetraenoic acid (12-HETE): a biomarker of Churg-Strauss syndrome

BACKGROUND

Churg-Strauss syndrome (CSS) shares similarities with asthma and hypereosinophilic syndrome (HES). Eicosanoids--important inflammatory and signaling molecules--are present in exhaled breath condensate (EBC) and broncho-alveolar lavage fluid (BALF).

OBJECTIVES

To assess eicosanoid profile both in EBC and BALF of CSS subjects searching for a pattern characteristic of this syndrome.

METHODS

EBCs from 23 CSS patients, 30 asthmatics, 12 HES patients and 54 healthy controls (HC) were assessed quantitatively for 19 eicosanoids by a high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS). In addition, in 21 of 23 CSS subjects and in nine asthmatics, eicosanoids were determined in BALF.

RESULTS

EBC from CSS patients showed markedly elevated levels of 12-HETE as compared with other studied groups. BALF was characterized by a significant elevation of 12-HETE and its metabolite 12-tetranor HETE in CSS as compared with asthma. Clinical activity of CSS correlated with 12-HETE and its metabolites levels in BALF, but not in EBC.

CONCLUSION AND CLINICAL RELEVANCE

CSS is clearly distinguished from bronchial asthma, and HES by a marked increase in 12-HETE concentration in both EBC and BALF. This points to a possible new pathogenic mechanism in CSS and may help in future in establishing the diagnosis of CSS.

Reduced expression of the prostaglandin E2 receptor E-prostanoid 2 on bronchial mucosal leukocytes in patients with aspirin-sensitive asthma

BACKGROUND

Prostaglandin E(2) (PGE(2)) is thought to play a role in the pathogenesis of aspirin-sensitive asthma (ASA).

OBJECTIVE

We sought to extend our previous observations implicating impaired inflammatory cell responsiveness to PGE(2) as a pathogenetic mechanism in patients with aspirin-sensitive rhinosinusitis to the bronchial mucosa in patients with ASA.

METHODS

Immunohistochemistry was used to enumerate inflammatory cells and their expression of cysteinyl leukotriene receptors 1 and 2 (CysLT(1) and CysLT(2)) and the PGE(2) receptors E-prostanoid 1 to 4 (EP(1)-EP(4)) in bronchial biopsy specimens from patients with ASA, patients with aspirin-tolerant asthma, and control subjects (n= 15 in each group). Concentrations of PGE(2) in bronchoalveolar lavage fluid were measured by using ELISA. The effects of PGE(2) and EP receptor agonists on CD3/CD28-stimulated cytokine production by PBMCs were measured by using ELISA. Airways responsiveness to LTD(4)in vivo was measured in asthmatic patients by means of bronchial challenge.

RESULTS

Compared with patients with aspirin-tolerant asthma, patients with ASA had increased bronchial mucosal neutrophil and eosinophil numbers but reduced percentages of T cells, macrophages, mast cells, and neutrophils expressing EP(2). Both groups showed increased bronchial sensitivity to inhaled LTD(4), but this did not correlate with mucosal expression of CysLT(1) or CysLT(2). Bronchoalveolar lavage fluid PGE(2) concentrations were comparable in all groups. In vitro PGE(2) inhibited cytokine production by PBMCs through EP(2) but not other PGE(2) receptors.

CONCLUSION

Our data are consistent with the hypothesis that impaired inhibition of inflammatory leukocytes by PGE(2) acting through the EP(2) receptor has a role in the pathogenesis of ASA.

Exhaled Eicosanoids following Bronchial Aspirin Challenge in Asthma Patients with and without Aspirin Hypersensitivity: The Pilot Study

Background. Special regulatory role of eicosanoids has been postulated in aspirin-induced asthma. Objective. To investigate effects of aspirin on exhaled breath condensate (EBC) levels of eicosanoids in patients with asthma. Methods. We determined EBC eicosanoid concentrations using gas chromatography/mass spectrometry (GC-MS) and high-performance liquid chromatography/mass spectrometry (HPLC-MS²) or both. Determinations were performed at baseline and following bronchial aspirin challenge, in two well-defined phenotypes of asthma: aspirin-sensitive and aspirin-tolerant patients. Results. Aspirin precipitated bronchial reactions in all aspirin-sensitive, but in none of aspirin-tolerant patients (ATAs). At baseline, eicosanoids profile did not differ between both asthma groups except for lipoxygenation products: 5- and 15-hydroxyeicosatetraenoic acid (5-, 15-HETE) which were higher in aspirin-induced asthma (AIA) than inaspirin-tolerant subjects. Following aspirin challenge the total levels of cysteinyl-leukotrienes (cys-LTs) remained unchanged in both groups. The dose of aspirin had an effect on magnitude of the response of the exhaled cys-LTs and prostanoids levels only in AIA subjects. Conclusion. The high baseline eicosanoid profiling of lipoxygenation products 5- and 15-HETE in EBC makes it possible to detect alterations in aspirin-sensitive asthma. Cysteinyl-leukotrienes, and eoxins levels in EBC after bronchial aspirin administration in stable asthma patients cannot be used as a reliable diagnostic index for aspirin hypersensitivity.