Aspirin-intolerant asthma (AIA) assessment using the urinary biomarkers, leukotriene E4 (LTE4) and prostaglandin D2 (PGD2) metabolites

Critical pathomechanisms of NSAID-exacerbated respiratory disease (N-ERD) clarified by treatment with omalizumab, an anti-IgE antibody

Characteristic symptoms of NSAID-exacerbated respiratory disease (N-ERD) include asthma, chronic eosinophilic rhinosinusitis with nasal polyposis, cysteinyl LT (CysLT) overproduction and NSAIDs hypersensitivity. Some N-ERD patients present with episodic treatment-resistant extra-respiratory symptoms (CysLT-associated coronary artery vasospasm, gastroenteritis, or skin rash). Even when using standard treatments for respiratory and extra-respiratory symptoms, including systemic corticosteroids and aspirin desensitization, it is difficult to control the clinical symptoms and severe type 2 inflammation involved with mast cells, eosinophils, ILC2s, and platelet activation. Few treatment options are applicable in a clinical setting. Therefore, identifying effective treatments is essential for managing N-ERD patients who suffer from these conditions. Our previous observational study demonstrated 12-month omalizumab treatment of N-ERD was clinically effective against respiratory symptoms. Despite the remaining eosinophilia, omalizumab significantly reduced urinary LTE4 and PGD2 metabolites to near normal levels at steady state. Based on the preliminary study, we demonstrated that omalizumab induced tolerance to aspirin in N-ERD patients 3 months after therapy initiation and suppressed activation of mast cells during 24 h of initiation in a randomized manner. Moreover, omalizumab had significant efficacy against extra-respiratory symptoms at baseline (lacking aspirin exposure) as well as throughout aspirin challenge. This review addresses the latest discoveries related to N-ERD pathogenesis and the significant effectiveness of omalizumab on N-ERD as a mast cell stabilizer. Our findings regarding omalizumab-associated mast cell inhibitory effects are indirect evidence that mast cell dysregulation and, possibly, IgE are pivotal components of N-ERD.

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?

Prostanoid Metabolites as Biomarkers in Human Disease

Prostaglandins (PGD₂, PGE₂, PGF_2α), prostacyclin (PGI₂), and thromboxane A₂ (TXA₂) together form the prostanoid family of lipid mediators. As autacoids, these five primary prostanoids propagate intercellular signals and are involved in many physiological processes. Furthermore, alterations in their biosynthesis accompany a wide range of pathological conditions, which leads to substantially increased local levels during disease. Primary prostanoids are chemically instable and rapidly metabolized. Their metabolites are more stable, integrate the local production on a systemic level, and their analysis in various biological matrices yields valuable information under different pathological settings. Therefore, prostanoid metabolites may be used as diagnostic, predictive, or prognostic biomarkers in human disease. Although their potential as biomarkers is great and extensive research has identified major prostanoid metabolites that serve as target analytes in different biofluids, the number of studies that correlate prostanoid metabolite levels to disease outcome is still limited. We review the metabolism of primary prostanoids in humans, summarize the levels of prostanoid metabolites in healthy subjects, and highlight existing biomarker studies. Since analysis of prostanoid metabolites is challenging because of ongoing metabolism and limited half-lives, an emphasis of this review lies on the reliable measurement and interpretation of obtained levels.

Omalizumab-induced aspirin tolerance in N-ERD patients is independent of atopic sensitization

BACKGROUND

NSAID-exacerbated respiratory disease (N-ERD) comprises the triad of chronic rhinosinusitis with nasal polyps (CRSwNP), asthma and intolerance to inhibitors of the cyclooxygenase-1-enzyme. The impact of omalizumab on prevention of aspirin-induced hypersensitivity in N-ERD patients with and without atopic sensitization has not been thoroughly addressed.

OBJECTIVE

To investigate the effect of omalizumab treatment on aspirin tolerance in atopic and non-atopic N-ERD patients.

METHODS

This single-center, prospective trial evaluated overall omalizumab-induced aspirin tolerability in N-ERD patients by performing aspirin challenge testing before and after 6 months of anti-IgE therapy. The impact of omalizumab on CRSwNP, asthma as well as serum and tissue biomarkers in patients with and without comorbid atopic sensitizations was further analyzed.

RESULTS

Out of 33 patients included in the study, 56% developed complete aspirin tolerance and 18% tolerated higher dosages after 24 weeks. Polyp size and disease-specific symptoms (NPS:-1.9±0.3,p<0.001;SNOT-20:-16.7±3.7,p<0.001;ACT:+3.2±0.7,p<0.001) improved in all patients irrespective of atopic sensitization. Effectiveness of omalizumab was accompanied by an increase in mean total serum IgE (307.8±42kU/L,p<0.001) and a decrease in ECP (-10.6±6.7 μg/L ) and in relative eosinophilia (-2.5±0.7%, p<0.01). While there was a significant reduction of tissue IgE (p<0.05) in all patients after 4 weeks, the number of local eosinophils decreased only in atopic individuals (p<0.05).

CONCLUSION

Omalizumab induced complete aspirin tolerance in the majority (56%) of patients independent of atopic sensitization and demonstrated clinical efficacy in the treatment of CRSwNP and asthma. Inhibition of IgE can therefore be a promising treatment option in preventing NSAID hypersensitivity reactions in N-ERD patients.

Divergent PGD2 and leukotriene C4 metabolite excretion following aspirin therapy: Ten patients with systemic mastocytosis

Aspirin-exacerbated respiratory disease and some cases of chronic idiopathic urticaria are disorders in which increased baseline urinary excretion of leukotriene(LT)E4 further increases following aspirin administration. Increased urinary excretion of the metabolites of prostaglandin D2, 11β-prostaglandin(PG)F2α and (2,3-dinor)-11β-PGF2α, have been documented in systemic mastocytosis (SM) and in mast cell activation syndrome (MCAS). Symptoms due to increased baseline and/or episodic release of PGD2 can be prevented with aspirin, an inhibitor of cyclooxygenase (COX)1 and COX2. Here by retrospective chart review we discovered 8 of 10 patients with SM in whom normalization of an elevated urinary (2,3-dinor)-11β-PGF2α occurred with aspirin therapy also had a parallel increased excretion of LTE4 by an average of nearly 13-fold. How widespread this phenomenon occurs in SM is unknown; however, this occurrence needs to be considered when interpreting changes in these urinary mast cell mediator metabolites during aspirin therapy.

Adult-onset eosinophilic airway diseases

Eosinophilic airway inflammation is one of the cardinal features of allergic airway diseases such as atopic asthma and allergic rhinitis. These childhood-onset conditions are mediated by allergen and allergen-specific IgE and often accompanied by other allergic diseases including food allergy and eczema. They can develop consecutively in the same patient, which is referred to as an allergic march. In contrast, some phenotypes of asthma, nonsteroidal anti-inflammatory drugs-exacerbated airway disease (N-ERD), chronic rhinosinusitis with nasal polyps (CRSwNP)/eosinophilic CRS and allergic bronchopulmonary aspergillosis/mycosis (ABPA/ABPM) are adult-onset airway diseases, which are characterized by prominent peripheral blood eosinophilia. Most of these conditions, except for ABPA/ABPM, are nonatopic, and the coexistence of multiple diseases, including an adult-onset eosinophilic systemic disease, eosinophilic granulomatosis with polyangiitis (EGPA), is common. In this review, we focus on eosinophil biology, genetics and clinical characteristics and the pathophysiology of adult-onset eosinophilic asthma, N-ERD, CRSwNP/eosinophilic CRS, ABPA/ABPM and EGPA, while exploring the common genetic, immunological and pathological conditions among these adult-onset eosinophilic diseases.

Japanese guidelines for adult asthma 2020

Bronchial asthma is characterized by chronic airway inflammation, which manifests clinically as variable airway narrowing (wheezes and dyspnea) and cough. Long-standing asthma may induce airway remodeling and become intractable. The prevalence of asthma has increased; however, the number of patients who die from it has decreased (1.3 per 100,000 patients in 2018). The goal of asthma treatment is to control symptoms and prevent future risks. A good partnership between physicians and patients is indispensable for effective treatment. Long-term management with therapeutic agents and the elimination of the triggers and risk factors of asthma are fundamental to its treatment. Asthma is managed by four steps of pharmacotherapy, ranging from mild to intensive treatments, depending on the severity of disease; each step includes an appropriate daily dose of an inhaled corticosteroid, which may vary from low to high. Long-acting β₂-agonists, leukotriene receptor antagonists, sustained-release theophylline, and long-acting muscarinic antagonists are recommended as add-on drugs, while anti-immunoglobulin E antibodies and other biologics, and oral steroids are reserved for very severe and persistent asthma related to allergic reactions. Bronchial thermoplasty has recently been developed for severe, persistent asthma, but its long-term efficacy is not known. Inhaled β₂-agonists, aminophylline, corticosteroids, adrenaline, oxygen therapy, and other approaches are used as needed during acute exacerbations, by selecting treatment steps for asthma based on the severity of the exacerbations. Allergic rhinitis, eosinophilic chronic rhinosinusitis, eosinophilic otitis, chronic obstructive pulmonary disease, aspirin-exacerbated respiratory disease, and pregnancy are also important conditions to be considered in asthma therapy.

Group 2 innate lymphoid cells in nasal polyposis

OBJECTIVE

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by a chronic type 2 inflammatory response in the paranasal sinuses. Group 2 innate lymphoid cells (ILC2s) are potent innate immune cells that contribute to type 2 inflammation by producing cytokines such as interleukin (IL)-4, IL-5, and IL-13. There is increasing evidence suggesting that ILC2s play an important role in the CRSwNP pathogenesis.

DATA SOURCES

We reviewed published literature obtained through PubMed inquiries.

STUDY SELECTIONS

Studies relevant to the presence, function, and activation of ILC2s in CRSwNP were included.

RESULTS

Nasal polyps (NPs) are one of the first tissues in which human ILC2s were discovered, and many groups have since reported that these cells are highly elevated in NPs. ILC2s in NPs are also highly activated and produce type 2 cytokines in vivo. Mediators known to activate ILC2s, including receptor activator of nuclear factor kappa-Β ligand, thymic stromal lymphopoietin, various lipid mediators (including prostaglandin D₂ and cysteinyl leukotrienes), IL-4, and IL-13 have also been shown to be elevated in NPs compared with healthy sinonasal tissue. Other well-known ILC2 activators, IL-25 and IL-33, are sometimes elevated in NPs in some countries. Furthermore, activation of ILC2s by means of 4 distinct transcriptional pathways (nuclear factor kappa-light-chain-enhancer of activated B cells, nuclear factor of activated T cells, signal transducer and activator of transcription 5, and signal transducer and activator of transcription 6) is needed for the most robust generation of type 2 cytokines.

CONCLUSION

ILC2-mediated type 2 inflammation plays a crucial role in the pathogenesis of CRSwNP. Targeting the upstream mediators responsible for activating ILC2s and the downstream products that these cells release may play an important role in modifying the inflammatory response and improving clinical outcomes in CRSwNP.

Urinary prostaglandin D2 and E2 metabolites associate with abdominal obesity, glucose metabolism, and triglycerides in obese subjects

Obesity is associated with low-grade chronic inflammation, which contributes to the development of the metabolic syndrome and its associated complications, such as insulin resistance and type-2 diabetes. Limited data from animal and human studies support local generation of pro-inflammatory prostanoid lipid mediators in white adipose tissue. However, the link between systemic prostanoid levels and parameters characterizing the metabolic syndrome is missing in human obesity. Therefore, we performed a targeted lipidomic analysis using urine samples from obese human subjects (n = 45) and show for the first time in humans that urinary prostanoid levels correlate with metabolic parameters that indicate a dysregulated glucose and triglyceride metabolism. We identified tetranor-PGDM and tetranor-PGEM as the two major urinary prostanoid metabolites in obese subjects with levels of 247 ± 31 and 23.3 ± 4.0 pmol/mg creatinine, respectively. Tetranor-PGDM was significantly associated with serum triglycerides, while tetranor-PGEM was associated with abdominal obesity as defined by an increased waist-to-hip ratio (WHR), with glycated hemoglobin (HbA1c), and with impaired oral glucose tolerance. These results confirm the previously established notion of low-grade chronic inflammation in obesity and further identify an association of the prostanoid pathway with obesity-associated dyslipidemia, abdominal obesity, and insulin resistance.

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.

Evaluation of Neutrophil Activation Status According to the Phenotypes of Adult Asthma

Purpose

Neutrophils are considered key effector cells in the pathogenic mechanisms of airway inflammation in asthma. This study assessed the activation status of neutrophils in adult asthmatics, and the therapeutic potential of FTY720, a synthetic sphingosine-1-phosphate analog, on activated neutrophils using an in vitro stimulation model.

Methods

We isolated peripheral blood neutrophils (PBNs) from 59 asthmatic patients (including 20 aspirin-exacerbated respiratory disease [AERD] and 39 aspirin-tolerant asthma [ATA] groups). PBNs were stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or lipopolysaccharide (LPS) and their activation status was determined based on reactive oxygen species (ROS) production, cell surface expression of CD11b, interleukin (IL)-8 and matrix metallopeptidase (MMP)-9 release. PBNs were primed with FTY720 to evaluate its anti-inflammatory action.

Results

In vitro PBN stimulation with fMLP or LPS induced a significant increase in ROS/CD11b/IL-8/MMP-9 levels (P < 0.05 for all). In asthmatics, fMLP-induced ROS level was significantly correlated with values of forced expiratory volume in 1 second/forced vital capacity (r = −0.278; P = 0.036), maximal mid-expiratory flow (r = −0.309; P = 0.019) and PC20 methacholine (r = −0.302; P = 0.029). In addition, ROS levels were significantly higher in patients with AERD and in those with severe asthma than in those with ATA or non-severe asthma (P < 0.05 for all). FTY720 treatment could suppress ROS/CD11b levels, and LPS-induced IL-8 and MMP-9 levels (P < 0.05 for all). Responders to FTY720 treatment had significantly higher neutrophil counts in sputum (P = 0.004).

Conclusions

Our findings suggest a useful in vitro PBN stimulation model for evaluating the neutrophil functional status and the therapeutic potentials of neutrophil-targeting candidates in asthmatics.

Potential Biomarkers for NSAID-Exacerbated Respiratory Disease

Asthma is a common chronic disease with several variant phenotypes and endotypes. NSAID-exacerbated respiratory disease (NERD) is one such endotype characterized by asthma, chronic rhinosinusitis (CRS) with nasal polyps, and hypersensitivity to aspirin/cyclooxygenase-1 inhibitors. NERD is more associated with severe asthma than other asthma phenotypes. Regarding diagnosis, aspirin challenge tests via the oral or bronchial route are a standard diagnostic method; reliable in vitro diagnostic tests are not available. Recent studies have reported various biomarkers of phenotype, diagnosis, and prognosis. In this review, we summarized the known potential biomarkers of NERD that are distinct from those of aspirin-tolerant asthma. We also provided an overview of the different NERD subgroups.

Group 2 innate lymphoid cells are recruited to the nasal mucosa in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by tissue eosinophilia and mast cell activation, including abundant production of prostaglandin D₂ (PGD₂). Group 2 innate lymphoid cells (ILC2s), which promote tissue eosinophilia and mast cell responses, undergo chemotaxis and cytokine production in response to PGD₂, but it is unknown whether ILC2s are active in patients with AERD.

OBJECTIVE

We sought to determine whether ILC2 numbers change in peripheral blood and the nasal mucosa during COX-1 inhibitor-induced reactions in patients with AERD.

METHODS

Blood and nasal scrapings were collected at baseline, during reactions, and after completion of ketorolac/aspirin challenge/desensitization in 12 patients with AERD. ILC2s and eosinophils were quantitated by means of flow cytometry. Urine was also collected, and quantification of PGD₂ metabolite and leukotriene E₄ levels was done by using ELISA. Baseline and nonsteroidal anti-inflammatory drug reaction clinical data were correlated with cell changes.

RESULTS

ILC2 numbers significantly increased in nasal mucosal samples and decreased in blood at the time of COX-1 inhibitor reactions in 12 patients with AERD. These changes were not observed in 2 patients without AERD. Furthermore, eosinophil numbers decreased in blood concurrently with significant increases in urinary PGD₂ metabolite and leukotriene E₄ levels. The magnitude of increases in nasal mucosal ILC2 numbers positively correlated with maximum symptom scores during challenges. Furthermore, blood ILC2 numbers during the reaction correlated with time for the reaction to resolve, possibly reflecting reaction severity.

CONCLUSIONS

ILC2s are recruited to the nasal mucosa during COX-1 inhibitor-induced reactions in patients with AERD, correlating with enhanced production of prostaglandins and leukotrienes.

Design, Synthesis and Cellular Characterization of a Dual Inhibitor of 5-Lipoxygenase and Soluble Epoxide Hydrolase

The arachidonic acid cascade is a key player in inflammation, and numerous well-established drugs interfere with this pathway. Previous studies have suggested that simultaneous inhibition of 5-lipoxygenase (5-LO) and soluble epoxide hydrolase (sEH) results in synergistic anti-inflammatory effects. In this study, a novel prototype of a dual 5-LO/sEH inhibitor KM55 was rationally designed and synthesized. KM55 was evaluated in enzyme activity assays with recombinant enzymes. Furthermore, activity of KM55 in human whole blood and endothelial cells was investigated. KM55 potently inhibited both enzymes in vitro and attenuated the formation of leukotrienes in human whole blood. KM55 was also tested in a cell function-based assay. The compound significantly inhibited the LPS-induced adhesion of leukocytes to endothelial cells by blocking leukocyte activation.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

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.

Symptom-Based Clustering in Chronic Rhinosinusitis Relates to History of Aspirin Sensitivity and Postsurgical Outcomes

BACKGROUND

Symptoms burden in chronic rhinosinusitis (CRS) may be assessed by interviews or by means of validated tools such as the 22-item SinoNasal Outcome Test (SNOT-22). However, when only the total SNOT-22 scores are used, the pattern of symptom distribution and heterogeneity in patient symptoms is lost.

OBJECTIVES

To use a standardized symptom assessment tool (SNOT-22) on preoperative symptoms to understand symptom heterogeneity in CRS and to aid in characterization of distinguishing clinical features between subgroups.

METHODS

This was a retrospective review of 97 surgical patients with CRS. Symptom-based clusters were derived on the basis of presurgical SNOT-22 scores using unsupervised analysis and network graphs. Comparison between clusters was performed for clinical and demographic parameters, postsurgical symptom scores, and presence or absence of a history of aspirin sensitivity.

RESULTS

Unsupervised analysis reveals coclustering of specific symptoms in the SNOT-22 tool. Using symptom-based clustering, patients with CRS were stratified into severe overall (mean total score, 90.8), severe sinonasal (score, 62), moderate sinonasal (score, 40), moderate nonsinonasal (score, 37) and mild sinonasal (score, 16) clusters. The last 2 clusters were associated with lack of history of aspirin sensitivity. The first cluster had a rapid relapse in symptoms postoperatively, and the last cluster demonstrated minimal symptomatic improvement after surgery.

CONCLUSION

Symptom-based clusters in CRS reveal a distinct grouping of symptom burden that may relate to aspirin sensitivity and treatment outcomes.

Leukotriene E4 induces MUC5AC release from human airway epithelial NCI-H292 cells

BACKGROUND

Hypersecretion of mucin in the airway epithelium is an important feature of allergic airway diseases. Of the 3 cysteinyl leukotrienes (CysLTs; LTC4 LTD4 and LTE4), only LTE4 is sufficiently stable to be detectable in extracellular fluids. However, LTE4 has received little attention because it binds poorly to the CysLT1 and CysLT2 receptors; therefore, little is known about the effects of LTE4 on mucous secretion. Recently, studies have focused on the P2Y12 receptor as a potential receptor for LTE4, because this receptor is required for LTE4-mediated pulmonary inflammation. In our previous study, we confirmed the expression of P2Y12 receptor in human airway epithelial cells. To clarify the roles of LTE4 in airway epithelial cells, we investigated mucus secretion by LTE4 in vitro.

METHODS

Confluent NCI-H292 cells were stimulated with LTE4 (0.01-1 μM) for 24 h. The release and production of MUC5AC protein, a gel-forming mucin, were evaluated with an enzyme-linked immunosorbent assay.

RESULTS

Western blot analysis revealed that NCI-H292 cells expressed P2Y12 receptor protein. LTE4 significantly induced the release of MUC5AC mucin in a dose-dependent manner. Th2 cytokines such as IL-4 (10 ng/mL) and IL-13 (10 ng/mL) accelerated the LTE4-induced release of MUC5AC protein. MRS2935, a P2Y12 receptor antagonist, partially inhibited the LTE4-induced release of MUC5AC protein in the airway. In contrast, MK571, a CysLT1 receptor antagonist, did not affect the release of MUC5AC protein elicited by LTE4.

CONCLUSIONS

These results suggest that LTE4 may play some important roles in allergic mucus secretion partially via activation of P2Y12 receptor.

Association and management of eosinophilic inflammation in upper and lower airways

This review discussed the contribution of eosinophilic upper airway inflammation includes allergic rhinitis (AR) and chronic rhinosinusitis (CRS) to the pathophysiology and course of asthma, the representative counterpart in the lower airway. The presence of concomitant AR can affect the severity of asthma in patients who have both diseases; however, it is still debatable whether the presence of asthma affects the severity of AR. Hypersensitivity, obstruction and/or inflammation in the lower airway can be detected in patients with AR without awareness or diagnosis of asthma, and AR is known as a risk factor for the new onset of wheeze and asthma both in children and adults. Allergen immunotherapy, pharmacotherapy and surgery for AR can contribute to asthma control; however, a clear preventive effect on the new onset of asthma has been demonstrated only for immunotherapy. Pathological similarities such as epithelial shedding are also seen between asthma and CRS, especially eosinophilic CRS. Abnormal sinus findings on computed tomography are seen in the majority of asthmatic patients, and asthmatic patients with CRS show a significant impairment in Quality of Life (QOL) and pulmonary function as compared to those without CRS. Conversely, lower airway inflammation and dysfunction are seen in non-asthmatic patients with CRS. Treatments for CRS that include pharmacotherapy such as anti-leukotrienes, surgery, and aspirin desensitization show a beneficial effect on concomitant asthma. Acting as a gatekeeper of the united airways, the control of inflammation in the nose is crucial for improvement of the QOL of patients with co-existing AR/CRS and asthma.

Prostaglandin D₂: a dominant mediator of aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin desensitization followed by high-dose aspirin therapy is routinely performed for patients with aspirin-exacerbated respiratory disease (AERD). Little is known about the contributions of mediators other than cysteinyl leukotrienes to aspirin reactions and to the therapeutic benefit of high-dose aspirin therapy.

OBJECTIVE

We investigated differences in urinary eicosanoid metabolite levels and blood eosinophil counts in patients with AERD who tolerate and those who fail aspirin desensitization and also in patients with AERD who were successfully treated with high-dose aspirin therapy.

METHODS

Twenty-nine patients with AERD were stratified into those who tolerated aspirin desensitization (group I) and those who did not (group II). Urine was analyzed for eicosanoid metabolites at baseline, during aspirin reactions, and during high-dose aspirin therapy. Blood was analyzed for cell differentials at baseline and during aspirin therapy.

RESULTS

Basal prostaglandin D2 metabolite (PGD-M; 13.6 ± 2.7 vs 7.0 ± 0.8 pmol/mg creatinine [Cr], P < .05) and thromboxane metabolite (TX-M; 1.4 ± 0.3 vs 0.9 ± 0.1 pmol/mg Cr, P < .01) levels were higher in group II than in group I. During aspirin reactions, PGD-M levels remained unchanged, whereas TX-M levels (0.7 ± 0.1 pmol/mg Cr, P = .07) tended to decrease in group I. In contrast, PGD-M levels increased dramatically in group II (61.3 ± 19.9 pmol/mg Cr, P < .05), whereas TX-M levels did not change. The decrease in FEV1 inversely correlated with basal urinary levels of both leukotriene E4 and PGD-M. Blood eosinophil and basophil levels increased and urinary PGD-M levels (2.2 ± 0.8 pmol/mg Cr, P < .001) decreased on 2 months of high-dose aspirin therapy in group I.

CONCLUSION

Failure to tolerate aspirin desensitization in a subset of patients with AERD is associated with prostaglandin D2 overproduction. The increase in blood eosinophil and basophil counts during high-dose aspirin therapy might reflect the functional consequences of decreased prostaglandin D2 release and the therapeutic benefit of aspirin.

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.

An update on the pathogenesis of the upper airways in aspirin-exacerbated respiratory disease

PURPOSE OF REVIEW

The key features of aspirin-exacerbated respiratory diseases (AERDs) include chronic, severe asthma and a high prevalence (60-80%) of chronic rhinosinusitis with nasal polyps, all of which are exacerbated by exposure to aspirin and other NSAIDs. Although the pathogenic mechanisms of AERD are not completely understood, repeated instances have shown intense eosinophilic infiltrations of upper and lower airway mucosa, and dysregulation of arachidonate metabolisms. Here, recent updates on the pathogenic mechanisms of chronic rhinosinusitis with nasal polyps in aspirin-exacerbated respiratory diseases are summarized.

RECENT FINDINGS

Intense eosinophilic infiltration is closely related to the elevated production of cytokines and chemokines such as IL-5 and eotaxin. The response of local immunoglobulin E to staphylococcal enterotoxins contributes to eosinophilic inflammation in nasal polyp tissue. Other characteristics include the overproduction of cysteinyl leukotrienes and increased expression of cysteinyl leukotriene receptor-1, reduced production of prostaglandin E2, and the down-regulation of cyclooxygenase-2 and E-prostanoid receptor subtype-2. A recent gene expression profiling study has also suggested that periostin is the most up-regulated gene in the nasal polyp tissue of AERD patients.

SUMMARY

Chronic rhinosinusitis with nasal polyps is a major comorbid condition of AERD patients that is closely associated with severe asthmatic symptoms. Significant pathologic findings in nasal polyp tissues include intense eosinophilic inflammation, which is caused by elevated production of eosinophil-related cytokines and chemokines, specific immunoglobulin E responses to staphylococcal enterotoxins, and altered arachidonic acid metabolism. This could affect the current treatments and methodologies that are used to control asthma, leading to a more severe and intractable AERD phenotype.

Prostaglandin E2 receptors in asthma and in chronic rhinosinusitis/nasal polyps with and without aspirin hypersensitivity

Chronic rhinosinusitis with nasal polyps (CRSwNP) and asthma frequently coexist and are always present in patients with aspirin exacerbated respiratory disease (AERD). Although the pathogenic mechanisms of this condition are still unknown, AERD may be due, at least in part, to an imbalance in eicosanoid metabolism (increased production of cysteinyl leukotrienes (CysLTs) and reduced biosynthesis of prostaglandin (PG) E2), possibly increasing and perpetuating the process of inflammation. PGE2 results from the metabolism of arachidonic acid (AA) by cyclooxygenase (COX) enzymes, and seems to play a central role in homeostasis maintenance and inflammatory response modulation in airways. Therefore, the abnormal regulation of PGE2 could contribute to the exacerbated processes observed in AERD. PGE2 exerts its actions through four G-protein-coupled receptors designated E-prostanoid (EP) receptors EP1, EP2, EP3, and EP4. Altered PGE2 production as well as differential EP receptor expression has been reported in both upper and lower airways of patients with AERD. Since the heterogeneity of these receptors is the key for the multiple biological effects of PGE2 this review focuses on the studies available to elucidate the importance of these receptors in inflammatory airway diseases.

Rhinosinusitis and nasal polyps in aspirin-exacerbated respiratory disease

The presence of aspirin-exacerbated respiratory disease (AERD) in a patient with chronic rhinosinusitis with nasal polyps and asthma is associated with severe eosinophilic upper and lower airway disease. This article deals with the inflammatory disease of the respiratory tract as it relates to the sinuses. Involvement of the sinuses in AERD is almost universal, depending on the stage of onset of the disease and evaluation by computed tomography. This article explores the clinical aspects, physiopathology, and treatment of rhinosinusitis as it relates to AERD.