Platelet activation markers overexpressed specifically in patients with aspirin-exacerbated respiratory disease

Glucagon-like Peptide-1 Receptor Pathway Attenuates Platelet Activation in Aspirin-Exacerbated Respiratory Disease

Platelets are key contributors to allergic asthma and aspirin-exacerbated respiratory disease (AERD), an asthma phenotype involving platelet activation and IL-33-dependent mast cell activation. Human platelets express the glucagon-like peptide-1 receptor (GLP-1R). GLP-1R agonists decrease lung IL-33 release and airway hyperresponsiveness in mouse asthma models. We hypothesized that GLP-1R agonists reduce platelet activation and downstream platelet-mediated airway inflammation in AERD. GLP-1R expression on murine platelets was assessed using flow cytometry. We tested the effect of the GLP-1R agonist liraglutide on lysine-aspirin (Lys-ASA)-induced changes in airway resistance, and platelet-derived mediator release in a murine AERD model. We conducted a prospective cohort study comparing the effect of pretreatment with liraglutide or vehicle on thromboxane receptor agonist-induced in vitro activation of platelets from patients with AERD and nonasthmatic controls. GLP-1R expression was higher on murine platelets than on leukocytes. A single dose of liraglutide inhibited Lys-ASA-induced increases in airway resistance and decreased markers of platelet activation and recruitment to the lung in AERD-like mice. Liraglutide attenuated thromboxane receptor agonist-induced activation as measured by CXCL7 release in plasma from patients with AERD and CD62P expression in platelets from both patients with AERD (n = 31) and nonasthmatic, healthy controls (n = 11). Liraglutide, a Food and Drug Administration-approved GLP-1R agonist for treatment of type 2 diabetes and obesity, attenuates in vivo platelet activation in an AERD murine model and in vitro activation in human platelets in patients with and without AERD. These data advance the GLP-1R axis as a new target for platelet-mediated inflammation warranting further study in asthma.

Trial of thromboxane receptor inhibition with ifetroban: TP receptors regulate eicosanoid homeostasis in aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is the triad of asthma, nasal polyposis, and respiratory reactions to COX-1 inhibitors. Overproduction of cysteinyl leukotrienes and underproduction of prostaglandin E2 (PGE2) are hallmarks of AERD. A mouse model predicted a key role for the thromboxane-prostanoid (TP) receptor in AERD.

OBJECTIVE

Our aim was to determine whether ifetroban, a TP receptor antagonist, attenuates aspirin-induced respiratory symptoms in patients with AERD.

METHODS

A total of 35 patients with AERD completed a 4-week double-blinded, placebo-controlled trial of ifetroban and underwent an oral aspirin challenge. The primary outcome was change in the provocative dose of aspirin that caused a 2-point increase in Total Nasal Symptom Score. Changes in lung function, eicosanoid levels, and platelet and mast cell activation were assessed. Cultured human nasal fibroblasts were stimulated with or without the TP agonist U46619 and assayed for prostanoid production.

RESULTS

Ifetroban was well tolerated in AERD and did not change the mean 2-point increase in Total Nasal Symptom Score (P = .763). Participants taking ifetroban had greater aspirin-induced nasal symptoms and a greater decline in FEV1 value than did participants receiving placebo (-18.8% ± 3.6% with ifetroban vs -8.4% ± 2.1% with placebo [P = .017]). Four weeks of ifetroban significantly increased urinary leukotriene E4 levels and decreased nasal PGE2 levels compared with placebo. Peak aspirin-induced urinary thromboxane levels correlated with peak urinary leukotriene E4 and prostaglandin D2 metabolite levels in participants taking ifetroban. U46119 significantly potentiated the production of PGE2 by cultured nasal fibroblasts from subjects with AERD but not by cultured nasal fibroblasts from controls without polypoid sinusitis.

CONCLUSION

Contrary to our hypothesis, TP receptor blockade worsened aspirin-induced reactions in AERD, possibly by exacerbating dysregulation of the eicosanoid system. TP signaling on stromal cells may be critical to maintaining PGE2 production when COX-2 function is low.

Omalizumab ameliorates extrarespiratory symptoms in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Omalizumab, an anti-IgE antibody, has clinical efficacy against respiratory symptoms of aspirin-exacerbated respiratory disease (AERD). However, some patients with AERD also present with extrarespiratory (chest, gastrointestinal, and/or cutaneous) symptoms, which are resistant to conventional treatment but can be alleviated by systemic corticosteroids.

OBJECTIVE

We evaluated the efficacy of omalizumab on extrarespiratory symptoms related to AERD.

METHODS

In study 1, a total of 27 consecutive patients with AERD initially prescribed omalizumab at Sagamihara National Hospital between July 2009 and March 2019 were retrospectively studied. Frequency of exacerbations of AERD-related extrarespiratory symptoms was compared before and after omalizumab treatment. In study 2, we reported 3 AERD cases with aspirin challenge-induced extrarespiratory symptoms among patients studied in our previous randomized trial (registration UMIN000018777), which evaluated the effects of omalizumab on hypersensitivity reactions during aspirin challenge to AERD patients. Extrarespiratory symptoms induced during the aspirin challenge were compared between placebo and omalizumab phases.

RESULTS

In study 1, omalizumab treatment was associated with decrease in frequency of exacerbation of chest pain (no. [%] of patients with exacerbation frequency ≥1 time per year, 6 [22.2%] vs 0; P < .001), gastrointestinal symptoms (9 [33.3%] vs 2 [7.4%]; P = .016), and cutaneous symptoms (16 [59.3%] vs 2 [7.4%]; P < .001), even under conditions of treatment-related reduction in systemic corticosteroid dose. Omalizumab also attenuated all the extrarespiratory symptoms during aspirin challenge in study 2.

CONCLUSION

Omalizumab ameliorated extrarespiratory symptoms at baseline (without aspirin exposure) and during aspirin challenge.

Metabolic regulation by prostaglandin E2 impairs lung group 2 innate lymphoid cell responses

BACKGROUND

Group 2 innate lymphoid cells (ILC2s) play a critical role in asthma pathogenesis. Non-steroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD) is associated with reduced signaling via EP2, a receptor for prostaglandin E2 (PGE2 ). However, the respective roles for the PGE2 receptors EP2 and EP4 (both share same downstream signaling) in the regulation of lung ILC2 responses has yet been deciphered.

METHODS

The roles of PGE2 receptors EP2 and EP4 on ILC2-mediated lung inflammation were investigated using genetically modified mouse lines and pharmacological approaches in IL-33-induced lung allergy model. The effects of PGE2 receptors and downstream signals on ILC2 metabolic activation and effector function were examined using in vitro cell cultures.

RESULTS

Deficiency of EP2 rather than EP4 augments IL-33-induced mouse lung ILC2 responses and eosinophilic inflammation in vivo. In contrast, exogenous agonism of EP4 and EP2 or inhibition of phosphodiesterase markedly restricts IL-33-induced lung ILC2 responses. Mechanistically, PGE2 directly suppresses IL-33-dependent ILC2 activation through the EP2/EP4-cAMP pathway, which downregulates STAT5 and MYC pathway gene expression and ILC2 energy metabolism. Blocking glycolysis diminishes IL-33-dependent ILC2 responses in mice where endogenous PG synthesis or EP2 signaling is blocked but not in mice with intact PGE2 -EP2 signaling.

CONCLUSION

We have defined a mechanism for optimal suppression of mouse lung ILC2 responses by endogenous PGE2 -EP2 signaling which underpins the clinical findings of defective EP2 signaling in patients with NERD. Our findings also indicate that exogenously targeting the PGE2 -EP4-cAMP and energy metabolic pathways may provide novel opportunities for treating the ILC2-initiated lung inflammation in asthma and NERD.

Updates on immune mechanisms in aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease has fascinated and frustrated specialists in allergy/immunology, pulmonology, and otorhinolaryngology for decades. It generally develops in previously healthy young adults and is unremitting and challenging to treat. The classical triad of asthma, nasal polyposis, and pathognomonic respiratory reactions to aspirin and other cyclooxygenase-1 inhibitors is accompanied by high levels of mast cell activation, cysteinyl leukotriene production, platelet activation, and severe type 2 respiratory inflammation. The "unbraking" of mast cell activation and further cysteinyl leukotriene generation induced by cyclooxygenase-1 inhibition reflect an idiosyncratic dependency on cyclooxygenase-1-derived products, likely prostaglandin E2, to maintain a tenuous homeostasis. Although cysteinyl leukotrienes are clear disease effectors, little else was known about their cellular sources and targets, and the contributions from other mediators and type 2 respiratory inflammation effector cells to disease pathophysiology were unknown until recently. The applications of targeted biological therapies, single-cell genomics, and transgenic animal approaches have substantially advanced our understanding of aspirin-exacerbated respiratory disease pathogenesis and treatment and have also revealed disease heterogeneity. This review covers novel insights into the immunopathogenesis of aspirin-exacerbated respiratory disease from each of these lines of research, including the roles of lipid mediators, effector cell populations, and inflammatory cytokines, discusses unanswered questions regarding cause and pathogenesis, and considers potential future therapeutic options.

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?

Is there a relationship between morphological and functional platelet changes and depressive disorder?

BACKGROUND

Blood platelets, due to shared biochemical and functional properties with presynaptic serotonergic neurons, constituted, over the years, an attractive peripheral biomarker of neuronal activity. Therefore, the literature strongly focused on the investigation of eventual structural and functional platelet abnormalities in neuropsychiatric disorders, particularly in depressive disorder. Given their impact in biological psychiatry, the goal of the present paper was to review and critically analyze studies exploring platelet activity, functionality, and morpho-structure in subjects with depressive disorder.

METHODS

According to the PRISMA guidelines, we performed a systematic review through the PubMed database up to March 2020 with the search terms: (1) platelets in depression [Title/Abstract]"; (2) "(platelets[Title]) AND depressive disorder[Title/Abstract]"; (3) "(Platelet[Title]) AND major depressive disorder[Title]"; (4) (platelets[Title]) AND depressed[Title]"; (5) (platelets[Title]) AND depressive episode[Title]"; (6) (platelets[Title]) AND major depression[Title]"; (7) platelet activation in depression[All fields]"; and (8) platelet reactivity in depression[All fields]."

RESULTS

After a detailed screening analysis and the application of specific selection criteria, we included in our review a total of 106 for qualitative synthesis. The studies were classified into various subparagraphs according to platelet characteristics analyzed: serotonergic system (5-HT2A receptors, SERT activity, and 5-HT content), adrenergic system, MAO activity, biomarkers of activation, responsivity, morphological changes, and other molecular pathways.

CONCLUSIONS

Despite the large amount of the literature examined, nonunivocal and, occasionally, conflicting results emerged. However, the findings on structural and metabolic alterations, modifications in the expression of specific proteins, changes in the aggregability, or in the responsivity to different pro-activating stimuli, may be suggestive of potential platelet dysfunctions in depressed subjects, which would result in a kind of hyperreactive state. This condition could potentially lead to an increased cardiovascular risk. In line with this hypothesis, we speculated that antidepressant treatments would seem to reduce this hyperreactivity while representing a potential tool for reducing cardiovascular risk in depressed patients and, maybe, in other neuropsychiatric conditions. However, the problem of the specificity of platelet biomarkers is still at issue and would deserve to be deepened in future studies.

Updates on treatment options in aspirin exacerbated respiratory disease

PURPOSE OF REVIEW

The aim is to describe why this review is timely and relevant. Acetylsalicylic acid exacerbated respiratory disease (AERD) is a clinically significant disease affecting approximately 7% of all asthmatics or around 1,400,000 persons in the United States alone. A large portion of these patients remain undiagnosed. This review summarizes up to date knowledge on the pathophysiology, treatment opinions and provides an expert opinion on how to approach the AERD patient.

RECENT FINDINGS

Findings describe the main themes in the literature covered by the article. Review of the current knowledge in terms of the key cells, cytokines/chemokines contributing to the acquired disease state of AERD. It also provides clinical approach toward the AERD patient with regards to current treatment options.

SUMMARY

Summary describes the implications of the findings for clinical practice or research. This is an up-to-date review of the current literature, with insight into how to approach the management of an AERD patient.

Fucoidan-functionalized activated platelet-hitchhiking micelles simultaneously track tumor cells and remodel the immunosuppressive microenvironment for efficient metastatic cancer treatment

Tumor metastasis is responsible for most mortality in cancer patients, and remains a challenge in clinical cancer treatment. Platelets can be recruited and activated by tumor cells, then adhere to circulating tumor cells (CTCs) and assist tumor cells extravasate in distant organs. Therefore, nanoparticles specially hitchhiking on activated platelets are considered to have excellent targeting ability for primary tumor, CTCs and metastasis in distant organs. However, the activated tumor-homing platelets will release transforming growth factor-β (TGF-β), which promotes tumor metastasis and forms immunosuppressive microenvironment. Therefore, a multitalent strategy is needed to balance the accurate tumor tracking and alleviate the immunosuppressive signals. In this study, a fucoidan-functionalized micelle (FD/DOX) was constructed, which could efficiently adhere to activated platelets through P-selectin. Compared with the micelle without P-selectin targeting effect, FD/DOX had increased distribution in both tumor tissue and metastasis niche, and exhibited excellent anti-tumor and anti-metastasis efficacy on 4T1 spontaneous metastasis model. In addition, due to the contribution of fucoidan, FD/DOX treatment was confirmed to inhibit the expression of TGF-β, thereby stimulating anti-tumor immune response and reversing the immunosuppressive microenvironment. The fucoidan-functionalized activated platelets-hitchhiking micelle was promising for the metastatic cancer treatment.

Emerging Biomarkers Beyond Leukotrienes for the Management of Nonsteroidal Anti-inflammatory Drug (NSAID)-Exacerbated Respiratory Disease

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD) is a unique condition characterized by aspirin/NSAID hypersensitivity, adult-onset asthma, and/or chronic rhinosinusitis with nasal polyps. Arachidonic acid metabolism dysregulation and intense eosinophilic/type 2 inflammation are central mechanisms in NERD. Studies have been conducted on various biomarkers, and urinary leukotriene E4 is considered the most available biomarker of NERD. However, the pathophysiology of NERD is heterogeneous and complex. Epithelial cells and platelets can interact with immune cells in NERD, and novel biomarkers related to these interactions have recently been investigated. We summarize emerging novel biomarkers of NERD and discuss their roles in the management of NERD.

Platelets: a potential role in chronic respiratory diseases?

Platelets are small anucleate cells known for their role in haemostasis and thrombosis. In recent years, an increasing number of observations have suggested that platelets are also immune cells and key modulators of immunity. They express different receptors and molecules that allow them to respond to pathogens, and to interact with other immune cells. Platelets were linked to the pathogenesis of some inflammatory disorders including respiratory diseases such as asthma and idiopathic pulmonary fibrosis. Here, we discuss the involvement of platelets in different immune responses, and we focus on their potential role in various chronic lung diseases.

In addition to their essential role in haemostasis and thrombosis, platelets are strong modulators of different immune responses, and could be involved in the physiopathology of several chronic airway diseaseshttps://bit.ly/3cB6Xnj

Pathomechanisms of AERD—Recent Advances

The pathomechanisms behind NSAID-exacerbated respiratory disease are complex and still largely unknown. They are presumed to involve genetic predisposition and environmental triggers that lead to dysregulation of fatty acid and lipid metabolism, altered cellular interactions involving transmetabolism, and continuous and chronic inflammation in the respiratory track. Here, we go through the recent advances on the topic and sum up the current understanding of the background of this illness that broadly effects the patients' lives.

Platelets, Not an Insignificant Player in Development of Allergic Asthma

Allergic asthma is a chronic and heterogeneous pulmonary disease in which platelets can be activated in an IgE-mediated pathway and migrate to the airways via CCR3-dependent mechanism. Activated platelets secrete IL-33, Dkk-1, and 5-HT or overexpress CD40L on the cell surfaces to induce Type 2 immune response or interact with TSLP-stimulated myeloid DCs through the RANK-RANKL-dependent manner to tune the sensitization stage of allergic asthma. Additionally, platelets can mediate leukocyte infiltration into the lungs through P-selectin-mediated interaction with PSGL-1 and upregulate integrin expression in activated leukocytes. Platelets release myl9/12 protein to recruit CD4⁺CD69⁺ T cells to the inflammatory sites. Bronchoactive mediators, enzymes, and ROS released by platelets also contribute to the pathogenesis of allergic asthma. GM-CSF from platelets inhibits the eosinophil apoptosis, thus enhancing the chronic inflammatory response and tissue damage. Functional alterations in the mitochondria of platelets in allergic asthmatic lungs further confirm the role of platelets in the inflammation response. Given the extensive roles of platelets in allergic asthma, antiplatelet drugs have been tested in some allergic asthma patients. Therefore, elucidating the role of platelets in the pathogenesis of allergic asthma will provide us with new insights and lead to novel approaches in the treatment of this disease.

Innate immune cell dysregulation drives inflammation and disease in aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is a complex inflammatory disorder that is not generally viewed as a disease involving the adaptive immune system but instead one largely driven by the innate immune system. This article focuses on the cellular dysregulation involving 4 central cell types: eosinophils, basophils, mast cells, and innate lymphoid type 2 cells. AERD can be envisioned as involving a self-perpetuating vicious circle in which mediators produced by a differentiated activated epithelial layer, such as IL-25, IL-33, and thymic stromal lymphopoietin, engage and activate each of these innate immune cells. The activation of these innate immune cells with their production of additional cytokine/chemokine and lipid mediators leads to further recruitment and activation of these innate immune cells. More importantly, numerous mediators produced by these innate immune cells provoke the epithelium to induce further inflammation. This self-perpetuating cycle of inflammation partially explains both current interventions suggested to ameliorate AERD (eg, aspirin desensitization, leukotriene modifiers, anti-IL-5/IL-5 receptor, anti-IL-4 receptor, and anti-IgE) and invites exploration of novel targets as specific therapies for this condition (prostaglandin D₂ antagonists or cytokine antagonists [IL-25, IL-33, thymic stromal lymphopoietin]). Several of these interventions currently show promise in small retrospective analyses but now require definite clinical trials.

The blocking effect of the glycoprotein IIb/IIIa receptor in the mouse model of asthma

BACKGROUND

It is apparent that the interaction between platelets and eosinophils plays a critical role in the activation of allergic inflammation. We investigated whether blocking of the glycoprotein (GP) IIb/IIIa receptor can attenuate allergic inflammation and airway hyperresponsiveness through inhibition of platelet-eosinophil aggregation (PEA) in asthma.

METHODS

BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA) on days 0 and 14, followed by 3 nebulized OVA challenges on days 28-30. On each challenge day, 5 mg/kg tirofiban was administered intraperitoneally 30 min before the challenge. Mice were assessed for airway hyperresponsiveness (AHR), airway inflammation, and the degree of PEA. Finally, the activation levels of platelets and eosinophils were evaluated.

RESULTS

Tirofiban treatment decreased AHR and eosinophilic inflammation in Bronchoalveolar Lavage (BAL) fluid. This treatment also reduced the levels of interleukin (IL)-4, IL-5, and IL-13 in BAL fluid and airway inflammatory cell infiltration in histological evaluation. Interestingly, the blocking of the GP IIb/IIIa receptor more reduced PEA in both blood and lung tissue of tirofiban-treated mice than in those of the positive control mice, and both eosinophilic and platelet activations were attenuated in tirofiban-treated mice.

CONCLUSIONS

The blocking of GP IIb/IIIa receptor with tirofiban can attenuate AHR and airway inflammation through the inhibition of PEA and activation.

Pharmacogenomics of Hypersensitivity to Non-steroidal Anti-inflammatory Drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are extensively prescribed in daily clinical practice. NSAIDs are the main cause of drug hypersensitivity reactions all over the world. The inhibition of cyclooxygenase enzymes by NSAIDs can perpetuate arachidonic acid metabolism, shunting to the 5-lipoxygenase pathway and its downstream inflammatory process. Clinical phenotypes of NSAID hypersensitivity are diverse and can be classified into cross-reactive or selective responses. Efforts have been made to understand pathogenic mechanisms, in which, genetic and epigenetic backgrounds are implicated in various processes of NSAID-induced hypersensitivity reactions. Although there were some similarities among patients, several genetic polymorphisms are distinct in those exhibiting respiratory or cutaneous symptoms. Moreover, the expression levels, as well as the methylation status of genes related to immune responses were demonstrated to be involved in NSAID-induced hypersensitivity reactions. There is still a lack of data on delayed type reactions. Further studies with a larger sample size, which integrate different genetic pathways, can help overcome current limitations of gen etic/epigenetic studies, and provide valuable information on NSAID hypersensitivity reactions.

Cellular interactions in aspirin-exacerbated respiratory disease

PURPOSE OF REVIEW

The purpose of this review is to summarize the complex cellular interactions of aspirin-exacerbated respiratory disease (AERD) and how these interactions promote pathogenic mechanisms of AERD.

RECENT FINDINGS

In addition to characteristic changes in eicosanoid levels, recent studies have identified increases in alarmin cytokines (IL-33, thymic stromal lymphopoietin) as well as activated innate lymphoid and plasma cell populations in samples from AERD patients.

SUMMARY

Patients with AERD typically demonstrate high levels of proinflammatory eicosanoids including cysteinyl leukotrienes (CysLTs) and prostaglandin D2 (PGD2) and hyporesponsiveness to prostaglandin E2 (PGE2). CysLTs are released by mast cells, eosinophils, and adherent platelets and promote epithelial release of IL-33, which activates mast cells and group 2 innate lymphoid cells (ILC2s) in concert with CysLTs. TSLP induces PGD2 release from mast cells which activates and recruits eosinophils, basophils, Th2 cells, and ILC2s via CRTH2. In turn, ILC2s and other cell types produce Th2 cytokines IL-4, IL-5, and IL-13 that, along with CysLTs and PGD2, promote bronchoconstriction, eosinophilic tissue inflammation, and mucus production.

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.

Formation of nasal polyps: The roles of innate type 2 inflammation and deposition of fibrin

Chronic rhinosinusitis (CRS) is one of the most common chronic diseases worldwide. It is a heterogeneous disease, and geographical or ethnic differences in inflammatory pattern in nasal mucosa are major issues. Tissue eosinophilia in CRS is highly associated with extensive sinus disease, recalcitrance, and a higher nasal polyp (NP) recurrence rate after surgery. The prevalence of eosinophilic CRS (ECRS) is increasing in Asian countries within the last 2 decades, and this trend appears to be occurring across the world. International consensus criteria for ECRS are required for the accurate understanding of disease pathology and precision medicine. In a multicenter large-scale epidemiological survey, the "Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis study," ECRS was definitively defined when the eosinophil count in nasal mucosa is greater than or equal to 70 eosinophils/hpf (magnification, ×400), and this study proposed an algorithm that classifies CRS into 4 groups according to disease severity. The main therapeutic goal with ECRS is to eliminate or diminish the bulk of NP tissue. NPs are unique abnormal lesions that grow from the lining of the nasal and paranasal sinuses, and type 2 inflammation plays a critical role in NP development in patients with ECRS. An imbalance between protease and endogenous protease inhibitors might play a pivotal role in the initiation and exacerbation of type 2 inflammation in ECRS. Intraepithelial mast cells in NPs, showing a tryptase+, chymase- phenotype, may also enhance type 2 inflammation. Intense edema and reduced fibrosis are important histological features of eosinophilic NPs. Mucosal edema mainly consists of exuded plasma protein, and excessive fibrin deposition would be expected to contribute to the retention of proteins from capillaries and thereby perpetuate mucosal edema that may play an etiological role in NPs. Upregulation of the coagulation cascade and downregulation of fibrinolysis strongly induce abnormal fibrin deposition in nasal mucosa, and type 2 inflammation plays a central role in the imbalance of coagulation and fibrinolysis.

Inflammatory heterogeneity in aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is a mechanistically distinct subtype of chronic rhinosinusitis with nasal polyps (CRSwNP). Although frequently associated with type 2 inflammation, literature characterizing the milieu of inflammatory cytokines and lipid mediators in AERD has been conflicting.

OBJECTIVE

We sought to identify differences in the upper airway inflammatory signature between CRSwNP and AERD and determine whether endotypic subtypes of AERD may exist.

METHODS

Levels of 7 cytokines representative of type 1, type 2, and type 3 inflammation, and 21 lipid mediators were measured in nasal mucus from 109 patients with CRSwNP, 30 patients with AERD, and 64 non-CRS controls. Differences in inflammatory mediators were identified between groups, and patterns of inflammation among patients with AERD were determined by hierarchical cluster analysis.

RESULTS

AERD could be distinguished from CRSwNP by profound elevations in IL-5, IL-6, IL-13, and IFN-γ; however, significant heterogeneity existed between patients. Hierarchical cluster analysis identified 3 inflammatory subendotypes of AERD characterized by (1) low inflammatory burden, (2) high type 2 cytokines, and (3) comparatively low type 2 cytokines and high levels of type 1 and type 3 cytokines. Several lipid mediators were associated with asthma and sinonasal disease severity; however, lipid mediators showed less variability than cytokines.

CONCLUSIONS

AERD is associated with elevations in type 2 cytokines (IL-5 and IL-13) and the type 1 cytokine, IFN-γ. Among patients with AERD, the inflammatory signature is heterogeneous, supporting subendotypes of the disease. Variability in AERD immune signatures should be further clarified because this may predict clinical response to biologic medications that target type 2 inflammation.

Longitudinal Outcomes of Severe Asthma: Real-World Evidence of Multidimensional Analyses

BACKGROUND

There have been few studies assessing long-term outcomes of asthma based on regular follow-up data.

OBJECTIVE

We aimed to demonstrate clinical outcomes of asthma by multidimensional analyses of a long-term real-world database and a prediction model of severe asthma using machine learning.

METHODS

The database included 567 severe and 1337 nonsevere adult asthmatics, who had been monitored during a follow-up of up to 10 years. We evaluated longitudinal changes in eosinophilic inflammation, lung function, and the annual number of asthma exacerbations (AEs) using a linear mixed effects model. Least absolute shrinkage and selection operator logistic regression was used to develop a prediction model for severe asthma. Model performance was evaluated and validated.

RESULTS

Severe asthmatics had higher blood eosinophil (P = .02) and neutrophil (P < .001) counts at baseline than nonsevere asthmatics; blood eosinophil counts showed significantly slower declines in severe asthmatics than nonsevere asthmatics throughout the follow-up (P = .009). Severe asthmatics had a lower level of forced expiratory volume in 1 second (P < .001), which declined faster than nonsevere asthmatics (P = .033). Severe asthmatics showed a higher annual number of severe AEs than nonsevere asthmatics. The prediction model for severe asthma consisted of 17 variables, including novel biomarkers.

CONCLUSIONS

Severe asthma is a distinct phenotype of asthma with persistent eosinophilia, progressive lung function decline, and frequent severe AEs even on regular asthma medication. We suggest a useful prediction model of severe asthma for research and clinical purposes.

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.

Omalizumab for Aspirin Hypersensitivity and Leukotriene Overproduction in Aspirin-exacerbated Respiratory Disease. A Randomized Controlled Trial

Rationale: Aspirin-exacerbated respiratory disease is characterized by severe asthma, nonsteroidal antiinflammatory drug hypersensitivity, nasal polyposis, and leukotriene overproduction. Systemic corticosteroid therapy does not completely suppress lifelong aspirin hypersensitivity. Omalizumab efficacy against aspirin-exacerbated respiratory disease has not been investigated in a randomized manner.

Objectives: To evaluate omalizumab efficacy against aspirin hypersensitivity, leukotriene E₄ overproduction, and symptoms during an oral aspirin challenge in patients with aspirin-exacerbated respiratory disease using a randomized design.

Methods: We performed a double-blind, randomized, crossover, placebo-controlled, single-center study at Sagamihara National Hospital between August 2015 and December 2016. Atopic patients (20–79 yr old) with aspirin-exacerbated respiratory disease diagnosed by systemic aspirin challenge were randomized (1:1) to a 3-month treatment with omalizumab or placebo, followed by a >18-week washout period (crossover design). The primary endpoint was the difference in area under logarithm level of urinary leukotriene E₄ concentration versus time curve in the intent-to-treat population during an oral aspirin challenge.

Measurements and Main Results: Sixteen patients completed the study and were included in the analysis. The area under the logarithm level of urinary leukotriene E₄ concentration versus time curve during an oral aspirin challenge was significantly lower in the omalizumab phase (median [interquartile range], 51.1 [44.5–59.8]) than in the placebo phase (80.8 [interquartile range, 65.4–87.8]) (P < 0.001). Ten of 16 patients (62.5%) developed oral aspirin tolerance up to cumulative doses of 930 mg in the omalizumab phase (P < 0.001).

Conclusions: Omalizumab treatment inhibited urinary leukotriene E₄ overproduction and upper/lower respiratory tract symptoms during an oral aspirin challenge, resulting in aspirin tolerance in 62.5% of the patients with aspirin-exacerbated respiratory disease.

Plasma P-Selectin Is Inversely Associated with Lung Function and Corticosteroid Responsiveness in Asthma

BACKGROUND

Severe asthma has multiple phenotypes for which biomarkers are still being defined. Plasma P-selectin reports endothelial and/or platelet activation.

OBJECTIVE

To determine if P-selectin is associated with features of asthma in a longitudinal study.

METHODS

Plasmas from 70 adult patients enrolled in the Severe Asthma Research Program (SARP) III at the University of Wisconsin-Madison were analyzed for concentration of P-selectin at several points over the course of 3 years, namely, at baseline (BPS), after intramuscular triamcinolone acetonide (TA) injection, and at 36 months after baseline. Thirty-four participants also came in during acute exacerbation and 6 weeks after exacerbation.

RESULTS

BPS correlated inversely with forced expiratory volume in 1 s (FEV1) and with residual volume/total lung capacity, an indicator of air trapping. BPS was inversely associated with FEV1 change after TA, by regression analysis. FEV1 did not change significantly after TA if BPS was above the median, whereas patients with BPS below the median had significantly increased FEV1 after TA. BPS was higher in and predicted assignment to SARP phenotype cluster 5 ("severe fixed-airflow asthma"). P-selectin was modestly but significantly increased at exacerbation but returned to baseline within 3 years.

CONCLUSIONS

High BPS is associated with airway obstruction, air trapping, the "severe fixed-airflow" cluster, and lack of FEV1 improvement in response to TA injection. P-selectin concentration, which is a stable trait with only modest elevation during exacerbation, may be a useful biomarker for a severe asthma pheno- or endotype characterized by low pulmonary function and lack of corticosteroid responsiveness.

Ceramide/sphingosine-1-phosphate imbalance is associated with distinct inflammatory phenotypes of uncontrolled asthma

BACKGROUND

Asthma is associated with inflammatory dysregulation, but the underlying metabolic signatures are unclear. This study aimed to classify asthma inflammatory phenotypes based on cellular and metabolic features.

METHODS

To determine cellular and metabolic profiles, we assessed inflammatory cell markers using flow cytometry, sphingolipid (SL) metabolites using LC-MS/MS, and serum cytokines using ELISA. Targeted gene polymorphisms were determined to identify genetic predispositions related to the asthma inflammatory phenotype.

RESULTS

In total, 137 patients with asthma and 20 healthy controls (HCs) were enrolled. Distinct cellular and metabolic profiles were found between them; patients with asthma showed increased expressions of inflammatory cell markers and higher levels of SL metabolites compared to HCs (P < .05 for all). Cellular markers (CD66⁺ neutrophils, platelet-adherent eosinophils) and SL metabolic markers (C16:0 and C24:0 ceramides) for uncontrolled asthma were also identified; higher levels were observed in uncontrolled asthma compared to controlled asthma (P < .05 for all). Asthmatics patients with higher levels of CD66⁺ neutrophils had lower FEV1(%), higher ACQ (but lower AQLO) scores, and higher sphingosine and C16:0 ceramide levels compared to those with low levels of CD66⁺ neutrophils. Asthmatics patients with higher levels of platelet-adherent eosinophils had higher S1P levels compared to those with lower levels of platelet-adherent eosinophils. Patients carrying TT genotype of ORMDL3 had more CD66⁺ neutrophils; those with AG/ GG genotypes of SGMS1 exhibited higher platelet-adherent eosinophils.

CONCLUSION

Patients with uncontrolled asthma possess distinct inflammatory phenotypes including increased CD66⁺ neutrophils and platelet-adherent eosinophils, with an imbalanced ceramide/S1P rheostat, potentially involving ORMDL3 and SGMS1 gene polymorphisms. Ceramide/S1P synthesis could be targeted to control airway inflammation.

NSAID-Exacerbated Respiratory Disease (NERD): From Pathogenesis to Improved Care

Nonsteroidal antiinflammatory drug (NSAID)-exacerbated respiratory disease (NERD) is characterized by moderate-to-severe asthma and a higher prevalence of chronic rhinosinusitis/nasal polyps, but is a highly heterogeneous disorder with various clinical manifestations. Two major pathogenic mechanisms are: (1) overproduction of cysteinyl leukotrienes with dysregulation of arachidonic acid metabolism and (2) increased type 2 eosinophilic inflammation affected by genetic mechanisms. Aspirin challenge is the gold standard to diagnose NERD, whereas reliable in vitro biomarkers have yet not been identified. Therapeutic approaches have been done on the basis of disease severity with the avoidance of culprit and cross-reacting NSAIDs, and when indicated, aspirin desensitization is an effective treatment option. Biologic approaches targeting Type 2 cytokines are emerging as potential therapeutic options. Here, we summarize the up-to-date evidence of pathophysiologic mechanisms and diagnosis/management approaches to the patients with NERD with its phenotypic classification.

Increased thrombin-activatable fibrinolysis inhibitor levels in patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous chronic inflammatory disease subdivided based on the presence or absence of nasal polyps (NPs). Histologic features of chronic rhinosinusitis with nasal polyps (CRSwNP) include inflammatory cell infiltration and excessive fibrin deposition in NPs. Thrombin-activatable fibrinolysis inhibitor (TAFI) is an enzyme that plays an antifibrinolytic role in the body. The significance of TAFI has been documented in patients with chronic inflammatory diseases, including chronic lung disease; however, it has not been evaluated in the pathogenesis of NPs.

OBJECTIVE

The objective of this study was to evaluate the potential role of TAFI in the pathogenesis of NPs.

METHODS

Nasal lavage fluid was collected from control subjects and patients with CRS. We measured levels of thrombin/anti-thrombin complex (TATc) and TAFI protein using an ELISA.

RESULTS

TATc levels in nasal lavage fluid were significantly increased in patients with CRSwNP and patients with chronic rhinosinusitis without nasal polyps (CRSsNP) compared with control subjects, and TAFI levels in nasal lavage fluid were also significantly increased in patients with CRSwNP compared with those in control subjects and patients with CRSsNP. There was a significant correlation between TATc and TAFI levels in nasal lavage fluid. Interestingly, patients with CRS and asthma showed increased TATc and TAFI levels in nasal lavage fluid compared with those in patients with CRS without asthma, especially patients with CRSwNP.

CONCLUSIONS

Increased TATc and TAFI levels in nasal passages of patients with CRSwNP might participate in fibrin deposition in NPs and might play a role in the pathogenesis of CRSwNP and asthma.

Unique Effect of Aspirin Therapy on Biomarkers in Aspirin-exacerbated Respiratory Disease. A Prospective Trial

Rationale: Daily high-dose aspirin therapy benefits many patients with aspirin-exacerbated respiratory disease but provides no benefit for aspirin-tolerant patients with asthma. Type 2 inflammation characterizes aspirin-exacerbated respiratory disease.Objectives: To determine whether high-dose aspirin therapy changes biomarkers of type 2 inflammation in aspirin-exacerbated respiratory disease.Methods: Forty-two subjects with aspirin-exacerbated respiratory disease underwent an aspirin desensitization and were placed on high-dose aspirin (1,300 mg daily). Fifteen aspirin-tolerant subjects with asthma were also placed on high-dose aspirin. Biologic specimens and clinical parameters were collected at baseline and after 8 weeks on aspirin. Urinary eicosanoids, plasma tryptase and cytokine levels, platelet-leukocyte aggregates, and granulocyte transcripts were assessed.Measurements and Main Results: Eight weeks of high-dose aspirin decreased nasal symptoms and urinary prostaglandin E metabolite (P < 0.05) and increased urinary leukotriene E4 (P < 0.01) levels in subjects with aspirin-exacerbated respiratory disease, but not in those with aspirin-tolerant asthma. Urinary prostaglandin D2 and thromboxane metabolites decreased in both groups. Only in subjects with aspirin-exacerbated respiratory disease, exhaled nitric oxide (P < 0.05), plasma tryptase (P < 0.01), and blood eosinophil (P < 0.01) and basophil (P < 0.01) counts increased and plasma tryptase correlated with eosinophil counts (Pearson r = 0.514; P < 0.01) on aspirin. After correction for eosinophil counts, aspirin-induced changes in blood granulocyte transcripts did not differ between groups. Aspirin had no effect on platelet-leukocyte aggregates, platelet activation markers, or plasma cytokines in either group.Conclusions: High-dose aspirin therapy for 8 weeks paradoxically increases markers of type 2 inflammation in subjects with aspirin-exacerbated respiratory disease, despite reducing nasal symptoms. This effect of aspirin is unique to aspirin-exacerbated respiratory disease and not observed in subjects with aspirin-tolerant asthma.

Increased expression of L-plastin in nasal polyp of patients with nonsteroidal anti-inflammatory drug-exacerbated respiratory disease

BACKGROUND

Most patients with nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (NERD) suffer from recurrence of nasal polyps. However, little is known about the specific cellular and molecular mechanisms contributing to the pathogenesis of nasal polyp development in patients with NERD in particular, especially at baseline when cyclooxygenase 1 inhibitors are not present. The objectives of this study were to identify proteins involved in the pathogenesis of nasal polyps in patients with NERD.

METHODS

We collected nasal polyp tissue from patients with NERD and from patients with aspirin-tolerant chronic rhinosinusitis with nasal polyps (CRSwNP). Protein profiles were analyzed by 2-dimensional electrophoresis and identified several proteins, including L-plastin, as highly expressed. We examined L-plastin and tissue factor (TF) expression by immunohistochemical and immunofluorescence analyses. To examine the role of L-plastin in eosinophils, we knocked down L-plastin expression in Eol-1 cells by using siRNA transfection.

RESULTS

L-plastin protein levels in nasal polyp tissue were increased in patients with NERD relative to those in patients with aspirin tolerant CRSwNP. Immunofluorescence analysis revealed that L-plastin was dominantly expressed in eosinophils and L-plastin and TF were co-expressed in eosinophils in NERD nasal polyp tissue. Knockdown of L-plastin in Eol-1 cells disrupted the cell surface distribution of TF by stimulation with granulocyte macrophage colony-stimulating factor.

CONCLUSION

Increased expression of L-plastin by eosinophils may contribute to abnormal fibrin deposition through TF translocation to the eosinophil cell surface in NERD nasal polyp tissue, which in turn may contribute to the pathogenesis of NERD.

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.

Cysteinyl leukotriene receptor 2 drives lung immunopathology through a platelet and high mobility box 1-dependent mechanism

Cysteinyl leukotrienes (cysLTs) facilitate eosinophilic mucosal type 2 immunopathology, especially in aspirin-exacerbated respiratory disease (AERD), by incompletely understood mechanisms. We now demonstrate that platelets, activated through the type 2 cysLT receptor (CysLT₂R), cause IL-33-dependent immunopathology through a rapidly inducible mechanism requiring the actions of high mobility box 1 (HMGB1) and the receptor for advanced glycation end products (RAGE). Leukotriene C₄ (LTC₄) induces surface HMGB1 expression by mouse platelets in a CysLT₂R-dependent manner. Blockade of RAGE and neutralization of HMGB1 prevent LTC₄-induced platelet activation. Challenges of AERD-like Ptges^-/- mice with inhaled lysine aspirin (Lys-ASA) elicit LTC₄ synthesis and cause rapid intrapulmonary recruitment of platelets with adherent granulocytes, along with platelet- and CysLT₂R-mediated increases in lung IL-33, IL-5, IL-13, and bronchoalveolar lavage fluid HMGB1. The intrapulmonary administration of exogenous LTC₄ mimics these effects. Platelet depletion, HMGB1 neutralization, and pharmacologic blockade of RAGE eliminate all manifestations of Lys-ASA challenges, including increase in IL-33, mast cell activation, and changes in airway resistance. Thus, CysLT₂R signaling on platelets prominently utilizes RAGE/HMGB1 as a link to downstream type 2 respiratory immunopathology and IL-33-dependent mast cell activation typical of AERD. Antagonists of HMGB1 or RAGE may be useful to treat AERD and other disorders associated with type 2 immunopathology.

Understanding Platelets in Infectious and Allergic Lung Diseases

Emerging evidence suggests that platelets, cytoplasmic fragments derived from megakaryocytes, can no longer be considered just as mediators in hemostasis and coagulation processes, but as key modulators of immunity. Platelets have received increasing attention as the emergence of new methodologies has allowed the characterization of their components and functions in the immune continuum. Platelet activation in infectious and allergic lung diseases has been well documented and associated with bacterial infections reproduced in several animal models of pulmonary bacterial infections. Direct interactions between platelets and bacteria have been associated with increased pulmonary platelet accumulation, whereas bacterial-derived toxins have also been reported to modulate platelet function. Recently, platelets have been found extravascular in the lungs of patients with asthma, and in animal models of allergic lung inflammation. Their ability to interact with immune and endothelial cells and secrete immune mediators makes them one attractive target for biomarker identification that will help characterize their contribution to lung diseases. Here, we present an original review of the last advances in the platelet field with a focus on the contribution of platelets to respiratory infections and allergic-mediated diseases.

The synergistic effects of clopidogrel with montelukast may be beneficial for asthma treatment

Platelets modulate asthma pathogenesis by forming the platelet‐eosinophil aggregation (PEA), which facilitates the activation of eosinophils. Platelets exhibit the purinergic receptor (P2Y12R), which responds to cysteinyl leukotriene E4 (LTE₄). We have suggested that the combination of an antiplatelet drug (clopidogrel, [Clo]) and montelukast (Mon) would synergistically suppress asthma. BALB/c mice were intraperitoneally sensitized with ovalbumin (OVA) on days 0 and 14 and subsequently challenged on days 28‐30 and 42‐44. Mice were administered with Clo (10 mg/kg), Mon (10 mg/kg) or both drugs (Clo/Mon) orally 30 minutes before the OVA (1%) challenge on days 42‐44. Mice were assayed for airway hyper‐responsiveness (AHR) to methacholine and airway inflammation. Clopidogrel and montelukast attenuated the increased AHR; the combined treatment was more effective than a single treatment for total and eosinophil counts (all P < 0.05). Levels of interleukin (IL)‐4, IL‐5, IL‐13, platelet factor 4, eosinophil peroxidase and LTE₄ increased in the bronchoalveolar lavage fluid of asthmatic mice, but these levels decreased in mice treated with Clo/Mon (all P < 0.05). Goblet cell hyperplasia decreased in response to Clo/Mon. Mouse platelets and eosinophils were isolated and co‐cultured for an in vitro assay with 10 µmol/L adenosine diphosphate (ADP), LTE₄ (200 nmol/L), Mon (1 µmol/L), Clo (1 µmol/L) and Clo/Mon (1 µmol/L). Flow cytometry revealed that the increased formation of the PEA (%) was fully mediated by ADP and partly mediated by LTE₄. Clo/Mon reduced ADP‐induced PEA formation and P‐selectin expression (P < 0.05). In conclusion, Clo/Mon synergistically relieved asthma by inhibiting ADP‐mediated PEA formation.

A trial of type 12 purinergic (P2Y12) receptor inhibition with prasugrel identifies a potentially distinct endotype of patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by asthma, recurrent nasal polyposis, and respiratory reactions on ingestion of COX-1 inhibitors. Increased numbers of platelet-leukocyte aggregates are present in the sinus tissue and blood of patients with AERD compared with that of aspirin-tolerant patients, and platelet activation can contribute to aspirin-induced reactions.

OBJECTIVE

We sought to determine whether treatment with prasugrel, which inhibits platelet activation by blocking the type 12 purinergic (P2Y12) receptor, would attenuate the severity of sinonasal and respiratory symptoms induced during aspirin challenge in patients with AERD.

METHODS

Forty patients with AERD completed a 10-week, double-blind, placebo-controlled crossover trial of prasugrel. All patients underwent oral aspirin challenges after 4 weeks of prasugrel and after 4 weeks of placebo. The primary outcome was a change in the provocative dose of aspirin that would elicit an increase in Total Nasal Symptom Score (TNSS) of 2 points. Changes in lung function, urinary eicosanoids, plasma tryptase, platelet-leukocyte aggregates, and platelet activation were also recorded.

RESULTS

Prasugrel did not significantly change the mean increase in TNSS of 2 points (79 ± 15 for patients receiving placebo and 139 ± 32 for patients receiving prasugrel, P = .10), platelet-leukocyte aggregates, or increases in urinary leukotriene E4 and prostaglandin D2 metabolite levels during aspirin-induced reactions in the study population as a whole. Five subjects (responders) reacted to aspirin while receiving placebo but did not have any reaction to aspirin challenge after the prasugrel arm. In contrast to prasugrel nonresponders (35 subjects), the prasugrel responders had smaller reaction-induced increases in TNSS; did not have significant aspirin-induced increases in urinary leukotriene E4, prostaglandin D2 metabolite, or thromboxane B2 levels; and did not display increases in serum tryptase levels during aspirin reactions on the placebo arm, all of which were observed in the nonresponders.

CONCLUSION

In the overall study population, prasugrel did not attenuate aspirin-induced symptoms, possibly because it failed to decrease the frequencies of platelet-adherent leukocytes or to diminish aspirin-induced mast cell activation. In a small subset of patients with AERD who had greater baseline platelet activation and milder upper respiratory symptoms during aspirin-induced reactions, P2Y12 receptor antagonism with prasugrel completely inhibited all aspirin-induced reaction symptoms, suggesting a contribution from P2Y12 receptor signaling in this subset.

Recent developments and highlights in biomarkers in allergic diseases and asthma

The potential of precision medicine in allergy and asthma has only started to be explored. A significant clarification in the pathophysiology of rhinitis, chronic rhinosinusitis, asthma, food allergy and drug hypersensitivity was made in the last decade. This improved understanding led to a better classification of the distinct phenotypes and to the discovery of new drugs such as biologicals, targeting phenotype-specific mechanisms. Nevertheless, many conditions remain poorly understood such as non-eosinophilic airway diseases or non-IgE-mediated food allergy. Moreover, there is a need to predict the response to specific therapies and the outcome of drug and food provocations. The identification of patients at risk of progression towards severity is also an unmet need in order to establish adequate preventive or therapeutic measures. The implementation of precision medicine in the clinical practice requires the identification of phenotype-specific markers measurable in biological matrices. To become useful, these biomarkers need to be quantifiable by reliable systems, and in samples obtained in an easy, rapid and cost-efficient way. In the last years, significant research resources have been put in the identification of valid biomarkers for asthma and allergic diseases. This review summarizes these recent advances with focus on the biomarkers with higher clinical applicability.

Endothelial dysfunction and platelet hyperactivity in type 2 diabetes mellitus: molecular insights and therapeutic strategies

The incidence and prevalence of diabetes mellitus is rapidly increasing worldwide at an alarming rate. Type 2 diabetes mellitus (T2DM) is the most prevalent form of diabetes, accounting for approximately 90-95% of the total diabetes cases worldwide. Besides affecting the ability of body to use glucose, it is associated with micro-vascular and macro-vascular complications. Augmented atherosclerosis is documented to be the key factor leading to vascular complications in T2DM patients. The metabolic milieu of T2DM, including insulin resistance, hyperglycemia and release of excess free fatty acids, along with other metabolic abnormalities affects vascular wall by a series of events including endothelial dysfunction, platelet hyperactivity, oxidative stress and low-grade inflammation. Activation of these events further enhances vasoconstriction and promotes thrombus formation, ultimately resulting in the development of atherosclerosis. All these evidences are supported by the clinical trials reporting the importance of endothelial dysfunction and platelet hyperactivity in the pathogenesis of atherosclerotic vascular complications. In this review, an attempt has been made to comprehensively compile updated information available in context of endothelial and platelet dysfunction in T2DM.

Recent advances in understanding the roles of blood platelets in the pathogenesis of allergic inflammation and bronchial asthma

Platelets play an essential role in hemostasis to minimize blood loss due to traumatic injury. In addition, they contain various immune-associated molecules and contribute to immunological barrier formation at sites of vascular injury, thereby protecting against invading pathogens. Platelets are also crucially involved in development of allergic diseases, including bronchial asthma. Platelets in asthmatics are more activated than those in healthy individuals. By using a murine asthma model, platelets were shown to be actively involved in progression of the disease, including in airway eosinophilia and airway remodeling. In the asthmatic airway, pathological microvascular angiogenesis, a component of airway remodeling, is commonly observed, and the degree of abnormality is significantly associated with disease severity. Therefore, in order to repair the newly formed and structurally fragile blood vessels under inflammatory conditions, platelets may be continuously activated in asthmatics. Importantly, platelets constitutively express IL-33 protein, an alarmin cytokine that is essential for development of bronchial asthma. Meanwhile, the concept of development of allergic diseases has recently changed dramatically, and allergy researchers now share a belief in the centrality of epithelial barrier functions. In particular, IL-33 released from epithelial barrier tissue at sites of eczema can activate the antigen-non-specific innate immune system as an alarmin that is believed to be necessary for subsequent antigen-specific acquired immunological responses. From this perspective, we propose in this review a possible mechanism for how activated platelets act as an alarmin in development of bronchial asthma.

Platelet activation parameters and platelet-leucocyte-conjugate formation in glioblastoma multiforme patients

Patients with glioblastoma multiforme (GBM) suffer from an increased incidence of vascular thrombotic events. However, key influencing factors of the primary hemostasis have not been characterized in GBM patients to date. Thus, the present study determines the activation level of circulating platelets in GBM patients, in-vitro reactivity to agonist-induced platelet stimulation and the formation of circulating platelet-leucocyte conjugates as well as the plasma levels of the proinflammatory lipid mediator sphingosine-1-phosphate (S1P). The endogenous thrombin potential (ETP) was determined as global marker for hemostasis. The 21 GBM patients and 21 gender and age matched healthy individuals enrolled in this study did not differ in mean total platelet count. Basal surface expression of platelet CD63 determined by flow cytometry was significantly increased in GBM patients compared to controls as was observed for the concentration of soluble P-selectin in the plasma of GBM patients. While the ETP was not affected, the immunomodulatory lipid S1P was significantly decreased in peripheral blood in GBM. Interestingly, monocyte expression of PSGL-1 (CD162) was decreased in GBM patient blood, possibly explaining the rather decreased formation of platelet-monocyte conjugates. Our study reveals an increased CD63 expression and P-selectin expression/ secretion of circulating platelets in GBM patients. In parallel a down-modulated PSGL-1 expression in circulating monocytes and a trend towards a decreased formation of heterotypic platelet-monocyte conjugates in GBM patients was seen. Whether this and the observed decreased plasma level of the immunomodulatory S1P reflects a systemic anti-inflammatory status needs to be addressed in future studies.

Aspirin-exacerbated respiratory disease: an update

PURPOSE OF REVIEW

The pathophysiology of aspirin-exacerbated respiratory disease (AERD) is not fully understood and diagnostic methods and so far, treatments for AERD have not been standardized. We summarize recent research into the pathological mechanisms of AERD, diagnostic methods, and treatments for AERD patients.

RECENT FINDINGS

In AERD pathophysiology, not only the reduced expression of E prostanoid 2 but also the dysfunction of its pathway could be involved. Moreover, eosinophils of AERD patients could be directly activated by aspirin to produce prostaglandin D2. Platelet activations are well known to be involved in AERD; however, plasma markers do not change during aspirin challenge tests. Additionally, novel genetic polymorphisms, such as P2RY12 and dipeptidyl peptidase 10 gene, and epigenetic predispositions of AERD were found. In AERD diagnosis, bronchial and nasal aspirin challenges have been applied in addition to oral challenge. Serum periostin has been suggested as a potential biomarker for AERD. Apart from standard pharmacological treatment and aspirin desensitization, biologics, including omalizumab and mepolizumab, as well as CRTH2 antagonists have been suggested as promising therapies for AERD treatment.

SUMMARY

AERD is usually associated with severe asthma phenotypes. AERD pathophysiology mainly involves the dysregulation of eicosanoid metabolisms, activations of effector cells, which could be influenced by genetic/epigenetic factors. Understanding the pathophysiology of AERD is key to improve the diagnostic methods and proper management of AERD patients.

IQCA-TAVV: To explore the effect of P-selectin, GPIIb/IIIa, IL-2, IL-6 and IL-8 on deep venous thrombosis

Deep vein thrombosis (DVT) associates with considerable morbidity, functional disability and mortality. Due to the lack of suitable inhibitor the correlation of various factors in DVT onset remains unknown. In this context we analyzed the structure of anti-platelet aggregation agent, P-selectin down-regulator, GPIIb/IIIa down-regulator and anti-inflammatory agent, thereby designed N-(3S-1,2,3,4-tetrahydroisoquinoline-3-carbonyl)- Thr-Ala-Arg-Gly-Asp(Val)-Val (IQCA-TAVV) as an inhibitor of DVT to receive evaluations. The docking predicted that IQCA-TAVV can target P-selectin and GPIIb/IIIa. The UV showed that IQCA-TAVV can act on P-selectin and GPIIb/IIIa. ELISA indicated that IQCA-TAVV concentration dependently inhibited activated platelets to express P-selectin and GPIIb/IIIa, and the minimal effective concentration was 1 nM. IC50 of IQCA-TAVV against platelet aggregation induced by arachidonic acid, adenosine diphosphate and platelet activating factor fell within a range of 0.13 nM to 0.30 nM. In vivo IQCA-TAVV dose-dependently inhibited venous thrombosis and the minimal effective dose was 1 nmol/kg. On ear edema model the anti-inflammation activity of 10 nmol/kg IQCA-TAVV equaled that of 1.1mmol/kg aspirin. The concentration of IL-2, IL-6 and IL-8 in the serum of the ear edema mice were also significantly decreased by 10 nmol/kg IQCA-TAVV. Even at 1 μmol/kg of dose IQCA-TAVV still did not injure the kidney, the liver, and the nerves of healthy mice. Thereby IQCA-TAVV depicts a relationship of three levels (inhibiting platelet activation, targeting externalized membrane receptor, decreasing serum inflammatory factor) for the down-regulation of P-selectin, GPIIb/IIIa, IL-2, IL-6 and IL-8 in DVT.

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.

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.

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.

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.

Platelet Activation: The Mechanisms and Potential Biomarkers

Beyond hemostasis and thrombosis, an increasing number of studies indicate that platelets play an integral role in intercellular communication, mediating inflammatory and immunomodulatory activities. Our knowledge about how platelets modulate inflammatory and immunity has greatly improved in recent years. In this review, we discuss recent advances in the pathways of platelet activation and potential application of platelet activation biomarkers to diagnosis and prediction of disease states.

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.