Cysteinyl leukotriene overproduction in aspirin-exacerbated respiratory disease is driven by platelet-adherent leukocytes

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.

Mechanisms of Benefit with Aspirin Therapy in Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is a clinical syndrome characterized by severe persistent asthma, hyperplastic eosinophilic sinusitis with nasal polyps, and an intolerance to aspirin and other NSAIDs that preferentially inhibit COX-1. For more than 30 years, aspirin desensitization has proven to be of significant long-term benefit in carefully selected patients with AERD. Despite this, the exact mechanisms behind the therapeutic effects of aspirin desensitization remain poorly understood. In this article, we review the current understanding of the mechanisms of aspirin desensitization and discuss future areas of investigation.

Lipid Mediators in Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is a syndrome of severe asthma and rhinosinusitis with nasal polyposis with exacerbations of baseline eosinophil-driven and mast cell-driven inflammation after nonsteroidal antiinflammatory drug ingestion. Although the underlying pathophysiology is poorly understood, dysregulation of the cyclooxygenase and 5-lipoxygenase pathways of arachidonic acid metabolism is thought to be key. Central features of AERD pathogenesis are overproduction of proinflammatory and bronchoconstrictor cysteinyl leukotrienes and prostaglandin (PG) D₂ and inhibition of bronchoprotective and antiinflammatory PGE₂. Imbalance in the ratio of these lipid mediators likely leads to the increased eosinophilic and mast cell inflammatory responses in the respiratory tract.

An update on the management of aspirin-exacerbated respiratory disease

INTRODUCTION

Clinical features of aspirin-exacerbated respiratory disease (AERD) consist of moderate to severe asthma associated with chronic rhinosinusitis (CRS), which are derived from overproduction of cysteinyl leukotrienes along with chronic type 2 mediated inflammation in the upper and lower airway mucosa. Area covered: This review provides recent up-to-date information regarding phenotypes of AERD and encompasses comprehensive diagnostic methods and treatment options. To confirm the diagnosis of AERD, provocation testing via nasal, inhalation or the oral route of aspirin remains the gold standard; in vitro diagnostic methods are still not available. Essential management is to avoid cross-reacting cyclooxygenase 1 (COX-1) inhibitors along with use of highly selective COX-2 inhibitors and to maintain pharmacologic treatment depending on the severity of asthma and chronic rhinosinusitis. Recent biologics, including anti-IgE and anti-IL5 antibodies, are required in severe AERD patients with CRS. Aspirin desensitization can be recommended when indicated. Expert commentary: AERD is a heterogeneous disease in terms of severity and associated allergic disease. When performing diagnosis and treatment for AERD, such disease characteristics need to be kept in mind.

Dietary Fatty Acid Modification for the Treatment of Aspirin-Exacerbated Respiratory Disease: A Prospective Pilot Trial

BACKGROUND

The high levels of eicosanoid production and the clinical efficacy of leukotriene-modifying pharmacotherapies for patients with aspirin-exacerbated respiratory disease (AERD) suggest that other interventions targeting arachidonic acid dysregulation may also improve disease control.

OBJECTIVE

To assess the utility of a high omega-3/low omega-6 diet for the treatment of AERD.

METHODS

Prospective, nonblinded dietary intervention in 10 adult patients with AERD at Brigham and Women's Hospital in Boston, MA. The primary objective was for subjects to reduce dietary omega-6 fatty acid consumption to less than 4 g/d and increase omega-3 intake to more than 3 g/d. The primary outcome was change in urinary leukotriene E₄, with changes in other eicosanoids, platelet activation, lung function, and patient-reported questionnaires also assessed.

RESULTS

Of the 10 subjects who screened for the study, all 10 completed the dietary intervention. Urinary leukotriene E₄ decreased by 0.17 ng/mg (95% CI, -0.29 to -0.04; P = .02) and tetranor prostaglandin D-M decreased by 0.66 ng/mg creatinine (95% CI, -1.21 to -0.11; P = .02). There was a 15.1-point reduction in the 22-item Sino-Nasal Outcome Test score (95% CI, -24.3 to -6.0; P = .01), a 0.27-point reduction in the 7-item Asthma Control Questionnaire score (95% CI, -0.52 to -0.03; P = .03), and no change in FEV₁ % predicted (P = .92) or forced vital capacity % predicted (P = .74). All patients lost some weight over the 2-week intervention period, and there were no diet-associated adverse events.

CONCLUSIONS

A high omega-3/low omega-6 diet may be an appropriate adjunct treatment option for patients with AERD.

The role of cysteinyl leukotrienes and their receptors in refractory nasal polyps

Leukotriene signaling is essential in many diseases, including asthma, allergic rhinitis, atherosclerosis and inflammatory bowel disease. Nevertheless, the expression of cysteinyl leukotrienes (CysLTs) and its receptors (CYSLTRs) in different types of nasal polyps (NPs), and the role of their antagonist in the treatment of refractory chronic rhinosinusitis with nasal polyps (CRSwNP) are not well understood. The following study investigates the expression of CysLTs and CYSLTRs in different types of NPs, as well as the role of leukotriene receptor antagonist (montelukast) in refractory NPs. Our data showed that CysLTs and CYSLTRs were significantly elevated in CRSwNP group (p < 0.05), particularly in IL-5⁺NP patients^, compared to patients with chronic rhinosinusitis but without NPs (CRSsNP) and the control group. Furthermore, montelukast have shown the ability to inhibit the expression of MUC5AC, TSLP, IL-4, IL-5, IL-13, and TGF-β in NP explants after treatment with Staphylococcal Enterotoxins B (SEB). In addition, the patients treated by additional montelukast have better outcomes compared to those with INCS only. To conclude, our results demonstrate that the inhibition of CysLTs signaling by montelukast decreases the expression of cytokines and mucin in polyp explants, and in turn promotes the recovery in patients with refractory CRSwNP.

Platelets: an outlook from biology through evidence-based achievements in critical care

Since the original observations by Bizzozero and Osler, we have seen tremendous advances in the understanding of platelets far beyond haemostasis and the restoration of injured endothelium. In this mini-review on platelets, we will briefly outline their historical description and the importance of their evolution, focusing on a 450 million years old living fossil of Limulus polyphemus, a marine chelicerate arthropod, which helped researchers explain the basis for the immunity role of platelets and make correlations with platelet ultrastructure and function. In addition, the impact of the Limulus Amoebocyte Lysate (LAL) test for modern medicine is highlighted. The role of platelets in cardiovascular diseases, their relevance in arterial and venous thrombosis, and the utilization of antithrombotic drugs as therapeutic agents are also reported. Furthermore, platelet receptors are crucial in aggravating or mitigating other diseases, such as cancer and infections, which can recruit cells and have numerous interactions in a process recently coined "NETosis formation", which is also briefly depicted.

Aspirin or Nonsteroidal Anti-inflammatory Drug-Exacerbated Chronic Rhinosinusitis

Aspirin (ASA)-exacerbated respiratory disease (AERD) is characterized by upper airway congestion due to eosinophilic inflammation of the nasal and sinus membranes and nasal polyposis, associated with increased leukotriene production that is further accentuated by ASA or other nonsteroidal anti-inflammatory drug (NSAID) ingestion. It occurs in 5% to 10% of subjects with chronic rhinosinusitis (CRS) and in 15% to 40% of those with nasal polyposis. Although AERD with CRS is usually associated with asthma, this is not always the case. The eosinophilic airway inflammation and symptoms precede clinical reactions to ASA or other NSAIDs, but ultimately affected subjects experience worsening of symptoms with ingestion of ASA/NSAIDs. The endotypic mechanism for this worsening is related to a chronic increase in leukotriene and a decrease in prostaglandin production, particularly prostaglandin E2, that is further aggravated by the inhibition of cycloxgenase I. IgE does not likely play a role in the pathogenesis of the disease although nasal and sinus staphylococcal infection increases local IgE level and may increase total IgE and specific IgE levels. Genetic studies suggest that multiple genes may be involved, but the genetic abnormalities may differ in affected subjects from different ethnicities and candidate genes have not been confirmed in multiple studies. Genome-wide association studies have not been revealing. The phenotype is recognized by the mucosal inflammation and worsening of symptoms acutely with ASA/NSAID. There is clinical improvement with ASA desensitization followed by regular ingestion of ASA or other NSAIDs. Further understanding of this unique phenotype and endotype of CRS will likely improve the understanding of other eosinophilic airway diseases.

Microparticles in nasal lavage fluids in chronic rhinosinusitis: Potential biomarkers for diagnosis of aspirin-exacerbated respiratory disease

BACKGROUND

Microparticles (MPs) are submicron-sized shed membrane vesicles released from activated or injured cells and are detectable by flow cytometry. MP levels have been used as biomarkers to evaluate cell injury or activation in patients with pathological conditions.

OBJECTIVE

We sought to compare MP types and levels in nasal lavage fluids (NLFs) from controls and patients with chronic rhinosinusitis without nasal polyps (CRSsNP), chronic rhinosinusitis with nasal polyps (CRSwNP), and aspirin-exacerbated respiratory disease (AERD).

METHODS

We collected NLFs from patients with CRSsNP (n = 33), CRSwNP (n = 45), and AERD (n = 31) and control (n = 24) subjects. Standardized flow cytometry methods were used to characterize the following MP types: endothelial MPs, epithelial MPs (epithelial cell adhesion molecule [EpCAM](+)MPs, E-cadherin(+)MPs), platelet MPs (CD31(+)CD41(+)MPs), eosinophil MPs (EGF-like module-containing mucin-like hormone receptor-like 1[EMR1](+)MPs), mast cell MPs (high-affinity IgE receptor [FcεRI](+)c-kit(+)MPs), and basophil MPs (CD203c(+)c-kit(-)MPs). Basophil activation was evaluated by the mean fluorescence intensity of CD203c on basophil MPs.

RESULTS

Activated mast cell MPs (CD137(+) FcεRI(+)c-kit(+)MPs) were significantly increased in NLFs of controls compared with NLFs of patients with CRSsNP (2.3-fold; P < .02), CRSwNP (2.3-fold; P < .03), and AERD (7.4-fold; P < .0001). Platelet MPs (3.5-fold; P < .01) and basophil MPs (2.5-fold; P < .05) were increased only in patients with AERD. Mean fluorescence intensity of CD203c on MPs was increased in patients with CRSwNP (P < .002) and AERD (P < .0001), but not in patients with CRSsNP. EpCAM(+)MPs in patients with CRSwNP were no different from control (P = .91) and lower than those in patients with CRSsNP (P < .02) and AERD (P < .002).

CONCLUSIONS

Based on released MPs, mast cells, platelets, and basophils were more highly activated in patients with AERD than in patients with CRS. Epithelial injury was lower in patients with CRSwNP than in patients with CRSsNP and AERD. MP analysis may help identify phenotypes of CRS, and in distinguishing AERD from CRSwNP.

Aspirin and Nonsteroidal Antiinflammatory Drugs Hypersensitivity and Management

Aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) are widely used in the United States and throughout the world for a variety of indications. Several unique hypersensitivity syndromes exist to this class of medications, making them one of the common reasons for consultation to the allergist. The lack of any laboratory-based diagnostic studies to assist in identifying the culprits in these reactions make evaluation of aspirin and NSAID hypersensitivity challenging. Identifying patients appropriate for oral challenge and/or desensitization protocols is the standard pragmatic approach to this issue when it arises.

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.

Platelet-Eosinophil Interactions As a Potential Therapeutic Target in Allergic Inflammation and Asthma

The importance of platelet activation during hemostasis is well understood. An understanding of these mechanisms has led to the use of several classes of anti-platelet drugs to inhibit aggregation for the prevention of thrombi during cardiovascular disease. It is now also recognized that platelets can function very differently during inflammation, as part of their role in the innate immune response against pathogens. This dichotomy in platelet function occurs through distinct physiological processes and alternative signaling pathways compared to that of hemostasis (leading to platelet aggregation) and is manifested as increased rheological interactions with leukocytes, the ability to undergo chemotaxis, communication with antigen-presenting cells, and direct anti-pathogen responses. Mounting evidence suggests platelets are also critical in the pathogenesis of allergic diseases such as asthma, where they have been associated with antigen presentation, bronchoconstriction, bronchial hyperresponsiveness, airway inflammation, and airway remodeling in both clinical and experimental studies. In particular, platelets have been reported bound to eosinophils in the blood of patients with asthma and the incidence of these events increases after both spontaneous asthma attacks in a biphasic manner, or after allergen challenge in the clinic. Platelet depletion in animal models of allergic airway inflammation causes a profound reduction in eosinophil recruitment to the lung, suggesting that the association of platelets with eosinophils is indeed an important event during eosinophil activation. Furthermore, in cases of severe asthma, and in animal models of allergic airways inflammation, platelet–eosinophil complexes move into the lung through a platelet P-selectin-mediated, eosinophil β1-integrin activation-dependent process, while platelets increase adherence of eosinophils to the vascular endothelium in vitro, demonstrating a clear interaction between these cell types in allergic inflammatory diseases. This review will explore non-thrombotic platelet activation in the context of allergy and the association of platelets with eosinophils, to reveal how these phenomena may lead to the discovery of novel therapeutic targets.

Update on Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is an acquired disease characterized by chronic eosinophilic airway inflammation with underlying dysregulation of arachidonic acid metabolism. The purpose of this paper is to review the latest developments in our understanding of the underlying pathophysiology including the role of eosinophils, mast cells, innate lymphoid cells (ILC₂), and platelets. Clinical features such as respiratory reactions induced by alcohol, aggressive nasal polyposis, and anosmia will allow for earlier recognition of these patients in clinical practice. The current state of the art management of AERD will be addressed including the ongoing central role for aspirin desensitization and high-dose aspirin therapy.

The expansive role of oxylipins on platelet biology

In mammals, three major oxygenases, cyclooxygenases (COXs), lipoxygenases (LOXs), and cytochrome P450 (CYP450), generate an assortment of unique lipid mediators (oxylipins) from polyunsaturated fatty acids (PUFAs) which exhibit pro- or anti-thrombotic activity. Over the years, novel oxylipins generated from the interplay of theoxygenase activity in various cells, such as the specialized pro-resolving mediators (SPMs), have been identified and investigated in inflammatory disease models. Although platelets have been implicated in inflammation, the role and mechanism of these SPMs produced from immune cells on platelet function are still unclear. This review highlights the burgeoning classes of oxylipins that have been found to regulate platelet function; however, their mechanism of action still remains to be elucidated.

Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is characterized by the triad of asthma, sinonasal polyposis, and aspirin intolerance. The hallmark of the disease is baseline overproduction of cysteinyl leukotrienes via the 5-lipoxygenase pathway, exacerbated by ingestion of aspirin. Patients with AERD have high rates of recidivistic polyposis following sinus surgery, although the improvement in quality of life following surgery is similar to aspirin-tolerant patients. The diagnosis is secured by a positive aspirin provocation test, usually administered by a medical allergist. Aspirin therapy is a unique treatment consideration for patients with AERD.

Copy number variation in ALOX5 and PTGER1 is associated with NSAIDs-induced urticaria and/or angioedema

OBJECTIVE

Cross-intolerance to NSAIDs is a class of drug hypersensitivity reaction, of which NSAIDs-induced urticaria and/or angioedema (NIUA) are the most frequent clinical entities. They are considered to involve dysregulation of the arachidonic acid pathway; however, this mechanism has not been confirmed for NIUA. In this work, we assessed copy number variations (CNVs) in eight of the main genes involved in the arachidonic acid pathway and their possible genetic association with NIUA.

MATERIALS AND METHODS

CNVs in ALOX5, LTC4S, PTGS1, PTGS2, PTGER1, PTGER2, PTGER3, and PTGER4 were analyzed using TaqMan copy number assays. Genotyping was carried out by real-time quantitative PCR. Individual genotypes were assigned using the CopyCaller Software. Statistical analysis was carried out using GraphPad prism 5, PLINK, EPIDAT, and R version 3.1.2.

RESULTS AND CONCLUSION

A total of 151 cases and 139 controls were analyzed during the discovery phase and 148 cases and 140 controls were used for replication. CNVs in open reading frames were found for ALOX5, PTGER1, PTGER3, and PTGER4. Statistically significant differences in the CNV frequency between NIUA and controls were found for ALOX5 (Pc=0.017) and PTGER1 (Pc=1.22E-04). This study represents the first analysis showing an association between CNVs in exonic regions of ALOX5 and PTGER1 and NIUA. This suggests a role of CNVs in this pathology that should be explored further.

Urinary Leukotriene E4 to Determine Aspirin Intolerance in Asthma: A Systematic Review and Meta-Analysis

BACKGROUND

Urinary leukotriene E4 (ULTE4) may be a biomarker that distinguishes aspirin-intolerant asthma from other asthma subtypes.

OBJECTIVE

To estimate the diagnostic testing accuracy of ULTE4 as a marker of aspirin intolerance in patients with asthma using previously published studies.

METHODS

We identified relevant clinical studies from a systematic review of English and non-English articles using MEDLINE, EMBASE, and CENTRAL (inception to February 10, 2015). Articles were screened at the abstract and full-text level by 2 independent reviewers. We included previously published studies that analyzed ULTE4 in human subjects with asthma characterized as having or not having aspirin intolerance on the basis of a specified definition: convincing history of aspirin intolerance, positive aspirin challenge, or both as the criterion standard. Individual-level data points from all included studies were obtained and analyzed.

RESULTS

The search strategy identified 867 potential articles, of which 86 were reviewed at the full-text level and 10 met criteria for inclusion. The sensitivity, specificity, positive predictive value, and negative predictive values of ULTE4 to determine aspirin intolerance in subjects with asthma were 0.55, 0.82, 0.75, and 0.66 (Amersham-enzyme immunoassay); 0.76, 0.77, 0.70, and 0.78 (Cayman-enzyme immunoassay); 0.70, 0.81, 0.86, and 0.79 (mass spectrometry); and 0.81,0.79, 0.65, and 0.88 (radioimmunoassay) at optimal thresholds of 192, 510, 167 to 173, and 66 to 69 pg/mg Cr, respectively. The diagnostic odds ratio for each methodology was 6.0, 11.9, 10.5, and 19.1, respectively.

CONCLUSIONS

ULTE4 is a marker for aspirin-intolerant asthma and could potentially be used as a clinical test to identify the risk of aspirin intolerance in subjects with asthma.

Cysteinyl leukotriene E4 activates human group 2 innate lymphoid cells and enhances the effect of prostaglandin D2 and epithelial cytokines

Background

Group 2 innate lymphoid cells (ILC2s) are a potential innate source of type 2 cytokines in the pathogenesis of allergic conditions. Epithelial cytokines (IL-33, IL-25, and thymic stromal lymphopoietin [TSLP]) and mast cell mediators (prostaglandin D₂ [PGD₂]) are critical activators of ILC2s. Cysteinyl leukotrienes (cysLTs), including leukotriene (LT) C₄, LTD₄, and LTE₄, are metabolites of arachidonic acid and mediate inflammatory responses. Their role in human ILC2s is still poorly understood.

Objectives

We sought to determine the role of cysLTs and their relationship with other ILC2 stimulators in the activation of human ILC2s.

Methods

For ex vivo studies, fresh blood from patients with atopic dermatitis and healthy control subjects was analyzed with flow cytometry. For in vitro studies, ILC2s were isolated and cultured. The effects of cysLTs, PGD₂, IL-33, IL-25, TSLP, and IL-2 alone or in combination on ILC2s were defined by using chemotaxis, apoptosis, ELISA, Luminex, quantitative RT-PCR, and flow cytometric assays. The effect of endogenous cysLTs was assessed by using human mast cell supernatants.

Results

Human ILC2s expressed the LT receptor CysLT₁, levels of which were increased in atopic subjects. CysLTs, particularly LTE₄, induced migration, reduced apoptosis, and promoted cytokine production in human ILC2s in vitro. LTE₄ enhanced the effect of PGD₂, IL-25, IL-33, and TSLP, resulting in increased production of type 2 and other proinflammatory cytokines. The effect of LTE₄ was inhibited by montelukast, a CysLT₁ antagonist. Interestingly, addition of IL-2 to LTE₄ and epithelial cytokines significantly amplified ILC2 activation and upregulated expression of the receptors for IL-33 and IL-25.

Conclusion

CysLTs, particularly LTE₄, are important contributors to the triggering of human ILC2s in inflammatory responses, particularly when combined with other ILC2 activators.

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Zusammenfassung. Das Widal-Syndrom umfasst eine klinische Trias mit chroniquer Rhinosinusitis und nasalen Polypen, Asthma bronchiale und eine Unverträglichkeit auf Acetylsalicylsäure (Aspirin) und anderen nichtsteroidalen Entzündungshemmern (NSAID). Etwa 7 % der Asthmatiker und 10 % der Patienten mit chronischer Rhinosinusitis leiden darunter. Asthma und NSAID-Unverträglichkeit treten häufig mehrere Jahre nach Beginn der Rhinosinusitis auf, was zur Verzögerung der Diagnose führt. Zurzeit gibt es keine spezifischen Biomarker. Der Provokationstest mit Aspirin bleibt der Gold-Standard für die Diagnose, sollte aber wegen des Risikos eines schweren Asthmaanfalls nur durch den Spezialisten durchgeführt werden. Die Grundbehandlung beruht auf der Kombination topischer Kortikosteroide und Montelukast, sowie der Vermeidung von Hemmern der Zyklooxygenase-1. Therapierefraktäre Fälle können auf eine Desensibilisierung mit Aspirin oder neuerdings auf Biologika wie Mepolizumab ansprechen.

Current complications and treatment of aspirin-exacerbated respiratory disease

INTRODUCTION

Aspirin-exacerbated respiratory disease is defined by the clinical tetrad of aspirin sensitivity, nasal polyps, asthma, and chronic rhinosinusitis. Patients experience acute upper and lower airway reactions with exposure to aspirin and other cyclooxygenase-1 inhibiting medications. However, airway inflammation and disease progression occur even in the absence of exposure to these medications, often leading to aggressive polyp formation and need for systemic corticosteroids to treat exacerbations in asthma and rhinosinusitis. Areas covered: This review focuses on the direct and indirect complications of aspirin-exacerbated respiratory disease. Current and potential management strategies are discussed with emphasis on aspirin desensitization. Expert commentary: Aspirin desensitization remains the gold standard of treatment. Demonstrated benefits of desensitization include improved symptom scores, reduction in use of systemic corticosteroids, slowing of polyp regrowth, and tolerance of aspirin and other NSAIDs for various therapeutic purposes. Continued investigation into the pathogenic mechanisms of AERD is likely to yield new diagnostic and therapeutic approaches.

Directed transport of neutrophil-derived extracellular vesicles enables platelet-mediated innate immune response

The innate immune response to bacterial infections requires the interaction of neutrophils and platelets. Here, we show that a multistep reciprocal crosstalk exists between these two cell types, ultimately facilitating neutrophil influx into the lung to eliminate infections. Activated platelets adhere to intravascular neutrophils through P-selectin/P-selectin glycoprotein ligand-1 (PSGL-1)-mediated binding, a primary interaction that allows platelets glycoprotein Ibα (GPIbα)-induced generation of neutrophil-derived extracellular vesicles (EV). EV production is directed by exocytosis and allows shuttling of arachidonic acid into platelets. EVs are then specifically internalized into platelets in a Mac1-dependent fashion, and relocated into intracellular compartments enriched in cyclooxygenase1 (Cox1), an enzyme processing arachidonic acid to synthesize thromboxane A₂ (TxA₂). Finally, platelet-derived-TxA₂ elicits a full neutrophil response by inducing the endothelial expression of ICAM-1, intravascular crawling, and extravasation. We conclude that critical substrate–enzyme pairs are compartmentalized in neutrophils and platelets during steady state limiting non-specific inflammation, but bacterial infection triggers regulated EV shuttling resulting in robust inflammation and pathogen clearance.

Interaction between platelets and neutrophils promotes neutrophil activation. Here the authors show that neutrophils initiate the cross-talk with platelets by shuttling arachidonic acid via extracellular vesicles, which platelets convert to thromboxane A₂ that then elicits neutrophil activation.

Exploration of the Sphingolipid Metabolite, Sphingosine-1-phosphate and Sphingosine, as Novel Biomarkers for Aspirin-exacerbated Respiratory Disease

Sphingolipid (SL) metabolites have been suggested to be important inflammatory mediators in airway inflammation and asthma. However, little is known about SL metabolites in aspirin-exacerbated respiratory disease (AERD). We aimed to explore the potential AERD biomarkers by conducting lipidomics targeting SL metabolites. The levels of SL metabolites in serum and urine samples from 45 AERD patients and 45 aspirin-tolerant asthma (ATA) patients were quantified through mass spectrometry. During the lysine-aspirin bronchoprovocation test (ASA-BPT), the levels of serum sphingomyelin (SM) were significantly decreased in AERD (P < 0.05) but not in ATA. The serum SM levels were positively correlated with airway responsiveness to methacholine. At the basal status before the ASA-BPT, the levels of serum sphingosine-1-phosphate (S1P) and urine sphingosine were significantly higher in the AERD patients compared with that of ATA patients (P < 0.001) and were positively correlated with a greater decrease in FEV₁ (%) values following the ASA-BPT test (P < 0.001 for each), and with serum periostin level (P < 0.05 for each). This study is the first to evaluate serum S1P and urine sphingosine as potential biomarkers of AERD as well as to examine the metabolic disturbance of SL in AERD patients.

Aspirin-exacerbated respiratory disease: Prevalence, diagnosis, treatment, and considerations for the future

Aspirin-exacerbated respiratory disease (AERD) is a late onset condition characterized by the Samter triad (aspirin sensitivity [as well as sensitivity to any nonselective cyclooxygenase inhibitor], nasal polyps, asthma) and additional features, including eosinophilic chronic rhinosinusitis, hypereosinophilia, anosmia, frequent absence of atopy, and, intolerance to ingestion of red wine and other alcoholic beverages. The diagnosis is rare, and, because of this, it is also often missed by physicians. However, it is highly overexpressed in patients with severe asthma (and severe chronic rhinosinusitis with nasal polyps), which makes its recognition essential. For this review, we considered mechanisms involved in the pathogenesis of this disease and discussed the clinical symptoms of AERD. We also discussed the role of aspirin desensitization in the treatment of AERD. Also, we considered medications (e.g, leukotriene modifiers) and surgical interventions that have a role in the treatment of AERD.

Aspirin-Exacerbated Respiratory Disease as an Endotype of Chronic Rhinosinusitis

Aspirin-Exacerbated Respiratory Disease (AERD) and Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) are both characterized by the presence of chronic sinonasal inflammation and nasal polyps. Unlike in CRSwNP, AERD patients develop respiratory reactions following ingestion of COX-1 inhibitors. AERD patients also, on average, have worse upper respiratory disease with increased sinonasal symptoms, mucosal inflammation and requirements for revision sinus surgery when compared to CRSwNP patients. While no single genetic factor has been identified in either CRSwNP or AERD to date, differences in the metabolism of arachidonic acid as well as innate immune cell activation may uniquely contribute to AERD pathogenesis.

Platelets in Pulmonary Immune Responses and Inflammatory Lung Diseases

Platelets are essential for physiological hemostasis and are central in pathological thrombosis. These are their traditional and best known activities in health and disease. In addition, however, platelets have specializations that broaden their functional repertoire considerably. These functional capabilities, some of which are recently discovered, include the ability to sense and respond to infectious and immune signals and to act as inflammatory effector cells. Human platelets and platelets from mice and other experimental animals can link the innate and adaptive limbs of the immune system and act across the immune continuum, often also linking immune and hemostatic functions. Traditional and newly recognized facets of the biology of platelets are relevant to defensive, physiological immune responses of the lungs and to inflammatory lung diseases. The emerging view of platelets as blood cells that are much more diverse and versatile than previously thought further predicts that additional features of the biology of platelets and of megakaryocytes, the precursors of platelets, will be discovered and that some of these will also influence pulmonary immune defenses and inflammatory injury.

Eosinophils and Mast Cells in Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) involves overexpression of proinflammatory mediators, including 5-lipoxygenase and leukotriene C₄ synthase (LTC₄S), resulting in constitutive overproduction of cysteinyl leukotrienes. Mast cells and eosinophils have roles in mediating many of the observed effects. Increased levels of both interleukin-4 (IL-4) and interferon (IFN)-γ are present in the tissue of patients with AERD. Previous studies showed that IL-4 is primarily responsible for the upregulation of LTC₄S by mast cells. Our studies show that IFN-γ, but not IL-4, drives this process in eosinophils. This article examines the overall role that eosinophils and mast cells contribute to the pathophysiology of AERD.

A Review of Classification Schemes for Chronic Rhinosinusitis with Nasal Polyposis Endotypes

Objective

The recent development of endotypes to categorize disease variants of chronic rhinosinusitis (CRS) reflects an evolving understanding of the various pathophysiologic and pathogenetic mechanisms that contribute to the clinical heterogeneity of CRS manifestations. This review highlights popular endotype‐based criteria used to define different CRS with nasal polyposis (CRSwNP) subtypes and further discusses the emerging therapeutic advances for each classificatory approach.

Data Sources

PubMed literature review.

Methods

A review of the current literature was conducted to determine present‐day uses of immunologic and molecular profiles in the CRSwNP disease spectrum to identify specific endotypes.

Results

Four distinct but overlapping classification schemes have emerged to define endotypes within the CRSwNP phenotype: 1) type 2 cytokine‐based approach, 2) eosinophil‐based approach, 3) immunoglobulin (Ig)E‐based approach, and 4) cysteinyl based approach. The identification of key inflammatory biomarkers related to these CRSwNP endotypes has broadened the classification of CRS beyond common phenotypic expressions. Furthermore, CRSwNP endotypes may improve the selection of CRSwNP patients who are suitable candidates for biomarker‐specific treatment options, such as anti‐interleukin‐5; anti‐IgE; and platelet‐directed therapies.

Conclusion

Chronic rhinosinusitis endotyping with key biomarker patterns of inflammation allows for improved diagnostic and potentially therapeutic classifications of CRSwNP variants.

Clustering drug-drug interaction networks with energy model layouts: community analysis and drug repurposing

Analyzing drug-drug interactions may unravel previously unknown drug action patterns, leading to the development of new drug discovery tools. We present a new approach to analyzing drug-drug interaction networks, based on clustering and topological community detection techniques that are specific to complex network science. Our methodology uncovers functional drug categories along with the intricate relationships between them. Using modularity-based and energy-model layout community detection algorithms, we link the network clusters to 9 relevant pharmacological properties. Out of the 1141 drugs from the DrugBank 4.1 database, our extensive literature survey and cross-checking with other databases such as Drugs.com, RxList, and DrugBank 4.3 confirm the predicted properties for 85% of the drugs. As such, we argue that network analysis offers a high-level grasp on a wide area of pharmacological aspects, indicating possible unaccounted interactions and missing pharmacological properties that can lead to drug repositioning for the 15% drugs which seem to be inconsistent with the predicted property. Also, by using network centralities, we can rank drugs according to their interaction potential for both simple and complex multi-pathology therapies. Moreover, our clustering approach can be extended for applications such as analyzing drug-target interactions or phenotyping patients in personalized medicine applications.

Eicosanoid Mediators in the Airway Inflammation of Asthmatic Patients: What is New?

Lipid mediators contribute to inflammation providing both pro-inflammatory signals and terminating the inflammatory process by activation of macrophages. Among the most significant biologically lipid mediators, these are produced by free-radical or enzymatic oxygenation of arachidonic acid named "eicosanoids". There were some novel eicosanoids identified within the last decade, and many of them are measurable in clinical samples by affordable chromatography-mass spectrometry equipment or sensitive immunoassays. In this review, we present some recent advances in understanding of the signaling by eicosanoid mediators during asthmatic airway inflammation. Eicosanoid profiling in the exhaled breath condensate, induced sputum, or their metabolites measurements in urine is complementary to the cellular phenotyping of asthmatic inflammation. Special attention is paid to aspirin-exacerbated respiratory disease, a phenotype of asthma manifested by the most profound changes in the profile of eicosanoids produced. A hallmark of this type of asthma with hypersensitivity to non-steroid anti-inflammatory drugs (NSAIDs) is to increase biosynthesis of cysteinyl leukotrienes on the systemic level. It depends on transcellular biosynthesis of leukotriene C₄ by platelets that adhere to granulocytes releasing leukotriene A₄. However, other abnormalities are also reported in this type of asthma as a resistance to anti-inflammatory activity of prostaglandin E₂ or a robust eosinophil interferon-γ response resulting in cysteinyl leukotrienes production. A novel mechanism is also discussed in which an isoprostane structurally related to prostaglandin E₂ is released into exhaled breath condensate during a provoked asthmatic attack. However, it is concluded that any single eicosanoid or even their complex profile can hardly provide a thorough explanation for the mechanism of asthmatic inflammation.

Is there a future for biologics in the management of chronic rhinosinusitis?

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous inflammatory condition of the sinonasal mucosa consisting of poorly defined subtypes and characterized by variable clinical manifestations, responses to therapy, and underlying pathophysiologies. In the related disorder of asthma, progress has been made in defining disease subtypes on both clinical and pathophysiologic levels, facilitating the development of targeted biologic pharmacotherapy. The potential role of these drugs for the management of CRS will be reviewed. The objective of this work is to highlight the emerging therapeutic targets in CRS in light of evolving treatment options for asthma and enhanced understandings of the clinical manifestations and pathophysiology of CRS.

METHODS

This article is a review of recent studies regarding current and future advances in biomarker-directed therapies in the medical treatment of CRS.

RESULTS

Various biologic therapies used in the management of asthma have demonstrated clinical promise for CRS, particularly within the CRS with nasal polyposis (CRSwNP) phenotype. Several randomized, double-blind, placebo-controlled studies increasingly support the targeting of immunoglobulin E (IgE) and interleukin (IL)-5 pathways to improve outcome measures in CRSwNP patients. The IL-4/IL-13 pathway and other type 2 inflammatory pathways have also shown potential as targets for CRSwNP, but all pathways require further investigation.

CONCLUSION

Recalcitrant CRS in the United States and Europe is most commonly associated with nasal polyposis and a type 2 cytokine skewing in the tissue, resulting in tissue infiltration of eosinophils, mast cells, and basophils. Targeting biomarkers of the associated type 2 pathways may be a practical treatment option for recalcitrant CRSwNP in the future.

Aspirin-exacerbated respiratory disease and current treatment modalities

Aspirin-exacerbated respiratory disease (AERD) refers to the combination of asthma, chronic rhinosinusitis with nasal polyposis, and acute upper and lower respiratory tract reactions to the ingestion of aspirin (acetylsalicylic acid, ASA) and other cyclooxygenase-1 inhibiting non-steroidal anti-inflammatory drugs. AERD affects 0.3-0.9 % of the general population. AERD generally occurs due to abnormalities in mediators and expression of arachidonic acid biosynthesis. Local IgE responses to staphylococcal enterotoxins may also be responsible for eosinophilic activation in the nasal polyp tissues of AERD patients. Clinical features of AERD include the onset of nasal congestion with anosmia, progressing to chronic pansinusitis and nasal polyps that regrow rapidly after surgery. Aspirin desensitization, Leukotriene-modifying agents, biologic agents, management of asthma, chronic rhinosinusitis, and nasal polyposis are recommended as treatment modalities. Immunotherapy is prescribed only to those AERD patients who experience clear seasonal or perennial allergy symptoms in addition to the symptoms attributable to chronic nasal polyposis. There are also investigational and dietary therapies. In this review, the important aspects of AERD will be presented, along with a literature survey.

Eosinophil production of prostaglandin D2 in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) differs from aspirin-tolerant disease in part because of eosinophilic tissue infiltration and overexpression of arachidonic acid metabolic pathway components that lead to enhanced secretion of cysteinyl leukotrienes and prostaglandin (PG) D₂ observed constitutively and paradoxically in response to aspirin and other COX inhibitors. We have previously demonstrated the capacity of IFN-γ to drive cysteinyl leukotriene expression and response.

OBJECTIVE

We investigated eosinophils as a source of PGD₂ production in patients with AERD.

METHODS

Eosinophils were enriched from tissue and peripheral blood obtained from control subjects, patients with aspirin-tolerant disease, and patients with AERD. mRNA was extracted and evaluated for expression of hematopoietic prostaglandin D synthase (hPGDS). Expression of hPGDS protein was confirmed with Western hybridization and immunofluorescence staining. Cells were stimulated with aspirin, and secretion of PGD₂ was quantified. CD34⁺ progenitor cells were isolated and matured into eosinophils in the presence or absence of IFN-γ and hPGDS mRNA, and PGD₂ release was measured.

RESULTS

Gene expression analysis revealed that eosinophils from tissue and blood of patients with AERD display increased levels of hPGDS compared with asthmatic and control samples. Western hybridization confirmed the increase in hPGDS mRNA translated to increased protein expression. Immunofluorescence confirmed mast cells and eosinophils from tissue of patients with AERD and asthma demonstrated hPGDS expression, with higher levels in eosinophils from patients with AERD. Incubation of eosinophils from blood and tissue with aspirin stimulated PGD₂ release. IFN-γ-matured eosinophil progenitors showed enhanced hPGDS expression and increased levels of PGD₂ release at baseline and after aspirin stimulation.

CONCLUSIONS

In addition to mast cells, eosinophils represent an important source of PGD₂ in patients with AERD and identify a new target for therapeutic intervention.

Leukotriene E4 elicits respiratory epithelial cell mucin release through the G-protein-coupled receptor, GPR99

Cysteinyl leukotrienes (cysLTs), leukotriene C4 (LTC4), LTD4, and LTE4 are proinflammatory lipid mediators with pathobiologic function in asthma. LTE4, the stable cysLT, is a weak agonist for the type 1 and type 2 cysLT receptors (CysLTRs), which constrict airway smooth muscle, but elicits airflow obstruction and pulmonary inflammation in patients with asthma. We recently identified GPR99 as a high-affinity receptor for LTE4 that mediates cutaneous vascular permeability. Here we demonstrate that a single intranasal exposure to extract from the respiratory pathogen Alternaria alternata elicits profound epithelial cell (EpC) mucin release and submucosal swelling in the nasal mucosa of mice that depends on cysLTs, as it is absent in mice deficient in the terminal enzyme for cysLT biosynthesis, LTC4 synthase (LTC4S). These mucosal changes are associated with mast cell (MC) activation and absent in MC-deficient mice, suggesting a role for MCs in control of EpC function. Of the three CysLTRs, only GPR99-deficient mice are fully protected from EpC mucin release and swelling elicited by Alternaria or by intranasal LTE4 GPR99 expression is detected on lung and nasal EpCs, which release mucin to doses of LTE4 one log lower than that required to elicit submucosal swelling. Finally, mice deficient in MCs, LTC4S, or GPR99 have reduced baseline numbers of goblet cells, indicating an additional function in regulating EpC homeostasis. These results demonstrate a novel role for GPR99 among CysLTRs in control of respiratory EpC function and suggest that inhibition of LTE4 and of GPR99 may have therapeutic benefits in asthma.

Update on the Management of Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is an adult-onset upper and lower airway disease consisting of eosinophilic nasal polyps, asthma, and respiratory reactions to cyclooxygenase 1 (COX-1) inhibitors. Management includes guideline-based treatment of asthma and sinus disease, avoidance of COX-1 inhibitors, and for some patients aspirin desensitization followed by high-dose aspirin therapy. Despite this, many patients have inadequately controlled symptoms and require multiple sinus surgeries. In this review, we discuss the current standard approaches to the management of AERD, and we introduce several therapeutics under development that may hold promise for the treatment of AERD.

Diagnostic Utility of Urinary LTE4 in Asthma, Allergic Rhinitis, Chronic Rhinosinusitis, Nasal Polyps, and Aspirin Sensitivity

BACKGROUND

Urinary leukotriene E4 (LTE4) is a well-validated marker of the cysteinyl leukotriene pathway, and LTE4 elevation has been described in conditions such as asthma, aspirin sensitivity, and chronic rhinosinusitis (CRS). There have been a number of reports investigating the role of spot urine LTE4 to predict aspirin sensitivity; however, variability in urinary LTE4 may affect the accuracy of this approach.

OBJECTIVE

Here, we explored the utility of 24-hour urinary LTE4 in 5 clinical diagnoses of allergic rhinitis, asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), CRS without nasal polyps, and aspirin sensitivity.

METHODS

This was a retrospective review of patients who had 24-hour quantification of urinary LTE4 by a clinically validated liquid chromatography tandem mass spectrometry method and their assigned diagnoses after assessment and clinical care.

RESULTS

Twenty-four-hour urinary LTE4 elevations were seen in those with asthma and those with CRSwNP but influenced by underlying aspirin sensitivity. Elevation in LTE4 was significant in those with CRSwNP after adjusting for aspirin sensitivity. Allergic rhinitis was not associated with elevated LTE4 excretion. Receiver operator characteristic analysis of 24-hour urinary LTE4 showed that a cutoff value of 166 pg/mg Cr suggested the presence of history of aspirin sensitivity with 89% specificity, whereas a cutoff value of 241 pg/mg Cr discriminated "challenge-confirmed" aspirin-sensitive subjects with 92% specificity.

CONCLUSIONS

Elevated 24-hour excretion of urinary LTE4 is a reliable and simple test to identify aspirin sensitivity in patients with respiratory diagnoses.

Aspirin-exacerbated respiratory disease: pathophysiological insights and clinical advances

Asthma and chronic rhinosinusitis are heterogeneous airway diseases of the lower and upper airways, respectively. Molecular and cellular studies indicate that these diseases can be categorized into unique endotypes, which have therapeutic implications. One such endotype is aspirin-exacerbated respiratory disease (AERD), which encompasses the triad of asthma, aspirin (or nonsteroidal anti-inflammatory drug) hypersensitivity, and nasal polyposis. AERD has unique pathophysiological features that distinguish it from aspirin-tolerant asthma and other forms of chronic rhinosinusitis. This review details molecular and cellular features of AERD and highlights current and future therapies that are based on these insights.

PLA2G5 regulates transglutaminase activity of human IL-4-activated M2 macrophages through PGE2 generation

Phospholipases A2 are enzymes that liberate membrane-bound lipids in a tissue and cell-specific fashion. Group V secretory phospholipase A2 is necessary for the development of M2 macrophages and their effector functions in a mouse model of the T-helper-2 allergic airway inflammation. However, the function of group V phospholipase A2 in human M2 activation and T-helper-2 inflammation is ill-defined. Transglutaminase-2, a protein cross-linking enzyme, is a newly identified marker of both human and mouse interleukin-4-activated M2 macrophages and is also found in the lungs of patients with asthma. We report that group V phospholipase A2 and transglutaminase-2 colocalized in macrophages of human nasal polyp tissue obtained from patients with T-helper-2 eosinophilic inflammation, and their coexpression positively correlated with the number of eosinophils in each tissue specimen. We demonstrate that in human monocyte-derived macrophages activated by interleukin-4, group V phospholipase A2 translocated and colocalized with transglutaminase-2 in the cytoplasm and on the membrane of macrophages. Moreover, knocking down group V phospholipase A2 with small interfering ribonucleic acid reduced macrophage transglutaminase activity, whereas mass spectrometry analysis of lipids also showed reduced prostaglandin E2 production. Finally, exogenous prostaglandin E2 restored transglutaminase activity of group V phospholipase A2-small interfering ribonucleic acid-treated macrophages. Thus, our study shows a novel function of group V phospholipase A2 in regulating the transglutaminase activity of human interleukin-4-activated M2 macrophages through prostaglandin E2 generation and suggests that group V phospholipase A2 is a functionally relevant enzyme that may have therapeutic value for the treatment of human T-helper-2 inflammatory disorders.

Aspirin-Exacerbated Diseases: Advances in Asthma with Nasal Polyposis, Urticaria, Angioedema, and Anaphylaxis

Aspirin-exacerbated diseases are important examples of drug hypersensitivities and include aspirin-exacerbated respiratory disease (AERD), aspirin- or non-steroidal anti-inflammatory drug (NSAID)-induced urticaria/angioedema, and aspirin- or NSAID-induced anaphylaxis. While each disease subtype may be distinguished by unique clinical features, the underlying mechanisms that contribute to these phenotypes are not fully understood. However, the inhibition of the cyclooxygenase-1 enzyme is thought to play a significant role. Additionally, eosinophils, mast cells, and their products, prostaglandins and leukotrienes, have been identified in the pathogenesis of AERD. Current diagnostic and treatment strategies for aspirin-exacerbated diseases remain limited, and continued research focusing on each of the unique hypersensitivity reactions to aspirin is essential. This will not only advance the understanding of these disease processes, but also lead to the subsequent development of novel therapeutics that patients who suffer from aspirin-induced reactions desperately need.

Association of TRPM3 Polymorphism (rs10780946) and Aspirin-Exacerbated Respiratory Disease (AERD)

INTRODUCTION

Aspirin-exacerbated respiratory disease (AERD) refers to the combination of asthma rhinosinusitis and poliposis; ingestion of aspirin or other non-steroid anti-inflammatory drugs exacerbate asthma-like symptoms. The pathogenesis of AERD is unknown, and genetic and environmental factors contribute to the disease. Our objective is identifying polymorphisms associated with susceptibility in a Mexican mestizo population.

METHODS

Primarily we performed custom Illumina goldengate array-based genotyping of 1512 SNPs, carefully selected from a variety of acute/chronic inflammatory lung conditions previously reported. Four SNPs in TRPM3 gene showed the lowest p-values (rs10780946, rs7025694, rs1889915, and rs7047645). We further selected rs10780946 and rs7025694 for validation using Taqman genotyping (n = 743; 288 AERD, 272 ATA, and 183 HC).

RESULTS

rs10780946 showed association when compared between AERD and ATA groups under co-dominant (p = 0.006), dominant (p = 0.002), overdominant (p = 0.01), and log-additive (p = 0.03) genetic models. AERD showed increased heterozygous TC (rs10780946-rs7025694) haplotype compared to ATA and HC (p < 0.05). We could not confirm any association between rs7025694 and AERD.

CONCLUSION

rs10780946 TRPM3 polymorphism is associated with AERD susceptibility.

Aspirin induces IL-4 production: augmented IL-4 production in aspirin-exacerbated respiratory disease

Aspirin hypersensitivity is a hallmark of aspirin-exacerbated respiratory disease (AERD), a clinical syndrome characterized by the severe inflammation of the respiratory tract after ingestion of cyclooxygenase-1 inhibitors. We investigated the capacity of aspirin to induce interleukin-4 (IL-4) production in inflammatory cells relevant to AERD pathogenesis and examined the associated biochemical and molecular pathways. We also compared IL-4 production in peripheral blood mononuclear cells (PBMCs) from patients with AERD vs aspirin-tolerant asthma (ATA) upon exposure to aspirin. Aspirin induced IL-4 expression and activated the IL-4 promoter in a report assay. The capacity of aspirin to induce IL-4 expression correlated with its activity to activate mitogen-activated protein kinases, to form DNA-protein complexes on P elements in the IL-4 promoter and to synthesize nuclear factor of activated T cells, critical transcription factors for IL-4 transcription. Of clinical importance, aspirin upregulated IL-4 production twice as much in PBMCs from patients with AERD compared with PBMCs from patients with ATA. Our results suggest that IL-4 is an inflammatory component mediating intolerance reactions to aspirin, and thus is crucial for AERD pathogenesis.

Cytokines in Chronic Rhinosinusitis. Role in Eosinophilia and Aspirin-exacerbated Respiratory Disease

RATIONALE

The mechanisms that underlie the pathogenesis of chronic rhinosinusitis without nasal polyps (CRSsNP), chronic rhinosinusitis with nasal polyps (CRSwNP), and aspirin-exacerbated respiratory disease (AERD) are not clear.

OBJECTIVES

To first evaluate the inflammatory profiles of CRSsNP and CRSwNP tissues and then to investigate whether clinical differences observed between CRSwNP and AERD are in part secondary to differences in inflammatory mediator expression within nasal polyp (NP) tissues.

METHODS

Expression levels of numerous inflammatory mediators were determined by quantitative real-time polymerase chain reaction, ELISA, and multiplex immunoassay.

MEASUREMENTS AND MAIN RESULTS

CRSwNP NP had increased levels of type 2 mediators, including IL-5 (P < 0.001), IL-13 (P < 0.001), eotaxin-2 (P < 0.001), and monocyte chemoattractant protein (MCP)-4 (P < 0.01), compared with sinonasal tissue from subjects with CRSsNP and control subjects. Expression of IFN-γ messenger RNA or protein was low and not different among the chronic rhinosinusitis subtypes examined. Compared with CRSwNP, AERD NP had elevated protein levels of eosinophil cationic protein (ECP) (P < 0.001), granulocyte-macrophage colony-stimulating factor (GM-CSF) (P < 0.01), and MCP-1 (P = 0.01), as well as decreased gene expression of tissue plasminogen activator (tPA) (P = 0.02). Despite the higher eosinophilia in AERD, there was no associated increase in type 2 mediator protein levels observed.

CONCLUSIONS

CRSwNP was characterized by a predominant type 2 inflammatory environment, whereas CRSsNP did not reflect a classic type 1 milieu, as has been suggested previously. AERD can be distinguished from CRSwNP by elevated ECP levels, but this enhanced eosinophilia is not associated with elevations in traditional type 2 inflammatory mediators associated with eosinophil proliferation and recruitment. However, other factors, including GM-CSF, MCP-1, and tPA, may be important contributors to AERD pathogenesis.

The whole-genome expression analysis of peripheral blood mononuclear cells from aspirin sensitive asthmatics versus aspirin tolerant patients and healthy donors after in vitro aspirin challenge

Background

Up to 30 % of adults with severe asthma are hypersensitive to aspirin and no unambiguous theory exists which provides a satisfactory explanation for the occurrence of aspirin-induced asthma (AIA) in some asthmatic patients. Therefore, the aim of this study was to compare the AIA expression profile against aspirin tolerant asthma (ATA) and healthy volunteers (HV) profile in peripheral blood mononuclear cells (PBMCs) after in vitro aspirin challenge in Caucasian population.

Methods

PBMCs were separated from blood of three groups of subjects - 11 AIA, 7 ATA and 15 HV and then stimulated by either 2 μM lysine aspirin or 20 μM lysine as a control. Subsequently, RNA was isolated, transcribed into cDNA and subjected to microarray and qPCR studies. Simultaneously, protein was extracted from PBMCs and used in further immunoblotting analysis.

Results

The validation of results at mRNA level has shown only three genes, whose expression was significantly altered between comprising groups. mRNA expression of CNPY3 in PBMCs in AIA was significantly lower (-0.41 ± 2.67) than in HV (1.04 ± 2.69), (p = 0.02); mRNA expression of FOSL1 in PBMCs in AIA was also significantly decreased (-0.66 ± 2.97) as opposed to HV (0.31 ± 4.83), (p = 0.02). While mRNA expression of ERAS in PBMCs was increased (1.15 ± 0.23) in AIA in comparison to HV (-1.32 ± 0.41), (p = 0.03). At protein level the changed expression of one protein was confirmed. Protein expression of FOSL1 in PBMCs in AIA was both significantly lower (-0.86 ± 0.08) than in ATA (0.39 ± 0.42), (p = 0.046) and in HV (0.9 ± 0.27), (p = 0.007).

Conclusions

This pilot study implies a positive association between CNPY3, ERAS, FOSL1 and aspirin-intolerant asthma, suggesting that these findings would be useful for further investigations of NSAIDs mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0305-4) contains supplementary material, which is available to authorized users.

P2Y12 antagonist attenuates eosinophilic inflammation and airway hyperresponsiveness in a mouse model of asthma

Leukotriene E4 (LTE4) that plays a key role in airway inflammation is expressed on platelets and eosinophils. We investigated whether blocking of the P2Y12 receptor can suppress eosinophilic inflammation in a mouse model of asthma because platelets and eosinophils share this receptor to be activated. BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA), followed by OVA nebulization. On each challenge day, clopidogrel, a P2Y12 antagonist was administered 30 min. before each challenge. Forty‐eight hours after the last OVA challenge, mice were assessed for airway hyperresponsiveness (AHR), cell composition and cytokine levels, including chemokine ligand 5 (CCL5), in bronchoalveolar lavage (BAL) fluid. EOL cells were treated with LTE4, with or without clopidogrel treatment, and intracellular and extracellular eosinophil cationic protein (ECP) expressions were measured to find the inhibiting function of P2Y12 antagonist on eosinophilic activation. The levels of P2Y12 expression were increased markedly in the lung homogenates of OVA‐sensitized and ‐challenged mice after platelet depletion. Administration of clopidogrel decreased AHR and the number of airway inflammatory cells, including eosinophils, in BAL fluid following OVA challenge. These results were associated with decreased levels of Th2 cytokines and CCL5. Histological examination showed that inflammatory cells as well as mucus‐containing goblet cells were reduced in clopidogrel‐administered mice compared to vehicle‐treated mice. Clopidogrel inhibited extracellular ECP secretion after LTE4 stimulation in EOL‐1 cells. Clopidogrel could prevent development of AHR and airway inflammation in a mouse model of asthma. P2Y12 can be a novel therapeutic target to the suppression of eosinophils in asthma.