Studies of the role of basophils in aspirin-exacerbated respiratory disease pathogenesis

Clinical and mechanistic advancements in aspirin exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is characterized by the clinical triad of chronic rhinosinusitis with nasal polyps, asthma, and a hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs). AERD is estimated to occur in as many as 15% of patients with chronic rhinosinusitis with nasal polyps and/or asthma. Uniquely, patients with AERD develop respiratory symptoms within 30 to 180 minutes after ingesting NSAIDs such as aspirin or ibuprofen. However, even in the absence of NSAIDs, patients tend to have more severe upper and lower respiratory disease. The underlying pathogenic mechanisms contributing to AERD are complex and intertwined; they include a systemic dysregulation in arachidonic acid metabolism, an aberrant inflammatory response, a disruption in the respiratory epithelial barrier, and an imbalance between the formation and degradation of fibrin locally in nasal polyps. This review will highlight novel mechanistic findings contributing to the pathogenesis of AERD. In addition, recent advancements in the clinical understanding and management of patients with AERD will be discussed.

Mechanistic studies on the role of CHI3L1 in eosinophilic inflammation in chronic sinusitis

More than 10% of adults suffer from chronic rhinosinusitis (CRS), a chronic inflammatory condition that lowers quality of life, reduces productivity, and shortens work hours. Every year, more than 1 million surgeries are performed worldwide as a result of CRS. In recent years, targeted therapy for CRS has become a hotspot of research at home and abroad and has made significant progress, but CRS still has a high recurrence rate. Therefore CRS urgently needs precise targeted therapy. In the pathological process of CRS, the involvement of eosinophils is an important inflammatory mechanism. And excessive aggregation of eosinophils often leads to severe inflammatory responses. Studies have shown that chitinase 3-like protein 1 (CHI3L1) plays a key role in the activation and migration of eosinophils. This review will combine the latest research results to analyse in detail the biological properties of CHI3L1, its expression pattern in CRS, and the possible mechanisms by which it affects eosinophil aggregation by regulating immune responses and inflammatory processes, which will provide insights into the key role of CHI3L1 in the pathological process of CRS and offer a new target for the treatment of CRS.

Aspirin hypersensitivity diagnostic index (AHDI): In vitro test for diagnosing of N-ERD based on urinary 15-oxo-ETE and LTE4 excretion

BACKGROUND

15-oxo-eicosatetraenoic acid (15-oxo-ETE), is a product of arachidonic acid (AA) metabolism in the 15-lipoxygenase-1 (15-LOX-1) pathway. 15-oxo-ETE was overproduced in the nasal polyps of patients with nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD). In this study we investigated the systemic biosynthesis of 15-oxo-ETE and leukotriene E4 (LTE4) and assessed their diagnostic value to identify patients with N-ERD.

METHODS

The study included 64 patients with N-ERD, 59 asthmatics who tolerated aspirin well (ATA), and 51 healthy controls. A thorough clinical characteristics of asthmatics included computed tomography of paranasal sinuses. Plasma and urinary 15-oxo-ETE levels, and urinary LTE4 excretion were measured using high-performance liquid chromatography and tandem mass spectrometry. Repeatability and precision of the measurements were tested.

RESULTS

Plasma 15-oxo-ETE levels were the highest in N-ERD (p < .001). A receiver operator characteristic (ROC) revealed that 15-oxo-ETE had certain sensitivity (64.06% in plasma, or 88.24% in urine) for N-ERD discrimination, while the specificity was rather limited. Modeling of variables allowed to construct the Aspirin Hypersensitivity Diagnostic Index (AHDI) based on urinary LTE4-to-15-oxo-ETE excretion corrected for sex and the Lund-Mackay score of chronic rhinosinusitis. AHDI outperformed single measurements in discrimination of N-ERD among asthmatics with an area under ROC curve of 0.889, sensitivity of 81.97%, specificity of 87.23%, and accuracy of 86.87%.

CONCLUSIONS

We confirmed 15-oxo-ETE as a second to cysteinyl leukotrienes biomarker of N-ERD. An index based on these eicosanoids corrected for sex and Lund-Mackay score has a similar diagnostic value as gold standard oral aspirin challenge in the studied group of patients with asthma.

Anti-IgE therapy in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory condition characterized by type 2 (T2) immune responses with significant impacts on quality of life and health care costs. Local IgE production in nasal polyp tissue plays a key role in the T2 inflammatory cascade. Omalizumab, an anti-IgE monoclonal antibody, is an effective treatment for some patients with CRSwNP regardless of the patient's allergic status. Clinical trials, including the pivotal POLYP 1 and POLYP 2 studies, demonstrated omalizumab's efficacy in reducing nasal polyp size, improving symptom scores, and enhancing quality of life, particularly in patients with comorbid asthma and aspirin-exacerbated respiratory disease. As we summarize in this review, omalizumab's effect appears to involve the reduction in local IgE and T2 inflammation; however, this remains poorly understood. Notably, omalizumab's effectiveness appears to be partially sustained after long-term therapy, though symptoms and inflammation begin to return at discontinuation. Ongoing research is needed to determine the optimal duration of therapy and potential for biologics to modify the disease course. Additionally, further studies are needed to identify biomarkers to predict treatment response and to compare omalizumab with other biologics such as dupilumab in head-to-head trials. Omalizumab is one of the key T2-targeted therapeutic options for CRSwNP, with sustained effectiveness and strong safety profile.

Unique effect of aspirin on local 15-oxo-eicosatetraenoic acid synthesis in asthma patients with aspirin hypersensitivity

BACKGROUND

Nonsteroidal anti-inflammatory drugs-exacerbated respiratory disease (NSAIDs-ERD) is characterized by altered arachidonic acid (AA) metabolism. Aspirin hypersensitivity is diagnosed using aspirin challenge, while induced sputum is collected to perform cell counts and to identify local biomarkers in induced sputum supernatant (ISS). This study aimed to assess the levels of a newly identified eicosanoid, 15-oxo-eicosatetraenoic acid (15-oxo-ETE), in ISS at baseline and during aspirin-induced bronchospasm in patients with NSAIDs-ERD.

METHODS

Oral aspirin challenge was performed in 27 patients with NSAIDs-ERD and in 17 patients with aspirin-tolerant asthma (ATA) serving as controls. Sputum was collected before and after aspirin challenge to determine eosinophil, neutrophil, macrophage, and lymphocyte counts as well as the concentration of AA metabolites via 15-lipoxygenase-1 (15-LOX-1) and 5-LOX pathways in ISS. Chromatography-tandem mass spectrometry was used to measure ISS levels of 15-oxo-ETE, 15-hydroxyeicosatetranoic acid (15-HETE), and leukotriene E4 (LTE4).

RESULTS

At baseline, ISS levels of 15-oxo-ETE were higher in NSAIDs-ERD than in ATA (p = 0.04). In contrast, baseline 15-HETE levels in ISS were lower in patients with NSAIDs-ERD (p = 0.03). After aspirin challenge, 15-oxo-ETE levels decreased only in patients with NSAIDs-ERD (p = 0.001) who developed bronchospasm. In both study groups, there was a reduction in sputum macrophage count after aspirin challenge (p = 0.03 and p = 0.02, respectively) irrespective of bronchospasm.

CONCLUSIONS

Patients with NSAIDs-ERD are characterized by higher baseline 15-oxo-ETE levels in ISS than patients with ATA. Aspirin-induced bronchospasm inhibited the local generation of 15-oxo-ETE.

Consultation for Chronic Rhinosinusitis With Nasal Polyps and Asthma: Clinical Presentation, Diagnostic Workup, and Treatment Options

Chronic rhinosinusitis (CRS) is characterized by chronic inflammation of the sinonasal mucosa, affects over 12% of the US population, and costs over $20 billion annually. CRS can be divided into 2 major phenotypes based on whether nasal polyps are present (chronic rhinosinusitis with nasal polyps [CRSwNP]) or absent (chronic rhinosinusitis without nasal polyps). This grand rounds review will discuss the clinical approach to patients with CRSwNP, including typical presentations, workup, and currently available treatment options. Tools that physicians can use to assess subjective sinonasal symptoms, as well as objective measures of disease, will be reviewed. Additional focus will be on recognizing clinical comorbidities commonly associated with CRSwNP, including asthma, bronchiectasis, allergic rhinitis, and nonsteroidal anti-inflammatory drug-exacerbated respiratory disease. Clinical outcomes can be improved by providing a comprehensive approach to evaluating (and managing) patients with CRSwNP.

Risk factors investigation for different outcomes between unilateral and bilateral chronic rhinosinusitis with nasal polyps patients

BACKGROUND

Studies involving chronic rhinosinusitis with nasal polyps (CRSwNP) have mostly focused on bilateral cases, making unilateral CRSwNP inadequately recognized. This study examined the differences in clinical characteristics, outcomes, and risk factors for poor outcomes between unilateral and bilateral CRSwNP to facilitate a better assessment in the two groups.

METHODS

Demographic information, tissue and blood cells, endoscopic scores, Lund-Mackay scores, recurrence rates, and disease control conditions were compared between 310 unilateral and 596 bilateral CRSwNP patients. Furthermore, the stepwise regression multivariate Cox proportional hazard models were performed to generate risk factors for poor outcomes in the two groups.

RESULTS

Bilateral cases exhibited higher rates of smoking, AR, and asthma comorbidities, along with higher numbers of tissue eosinophils and blood inflammatory cells when compared to unilateral patients. Endoscopic nasal polyp score, total computed tomography (CT) score (with scores for each sinus cavity), and adjusted CT scores were significantly higher in the bilateral group, except for a markedly higher adjusted maxillary score in the unilateral group. Furthermore, significantly higher proportions of bilateral patients experienced nasal polyp recurrence, uncontrolled status, and most disease control-related symptoms at follow-up. The primary risk factors for poor outcomes were asthma, tissue eosinophils, and total CT score in the bilateral group and blood basophils in the unilateral group.

CONCLUSIONS

Bilateral CRSwNP patients experience worse disease severity and outcomes than their unilateral counterparts. Primarily, asthma, tissue eosinophils, and total CT score were risk factors for poor outcomes in bilateral CRSwNP patients, with blood basophils in unilateral cases.

Endotypic heterogeneity and pathogenesis in chronic rhinosinusitis

PURPOSE OF REVIEW

This review aims to provide updates in realms of endotypic heterogeneity, pathogenesis at the molecular level, potential of biomarkers, and cutting-edge scope of biologics in CRS.

RECENT FINDINGS

High-dimensional analyses, such as transcriptomes, and machine learning, have significantly enhanced CRS endotyping, uncovering diverse pathogenetic mechanisms contributing to its heterogeneity. The dynamic process of epithelial remodeling in CRS pathogenesis has gained more clarity and support as exemplified by IL-13 and oncostatin M (OSM) that are shown intricately linked to epithelial barrier dysfunction. Moreover, anti-dsDNA autoantibody, BAFF, periostin, and cystatin SN show promise as potentials biomarkers, offering diagnostic and prognostic value for CRS.

SUMMARY

The identification of inflammatory molecules involved in endotype specific signaling pathways provides insights into the underlying mechanisms and verifiable biomarkers for diagnosis and prediction of disease severity. More comprehensive clinical studies should be conducted to facilitate biologics from bench to bedside in treating CRS.

Mast Cells in Aspirin-Exacerbated Respiratory Disease

PURPOSE OF REVIEW

Aspirin-exacerbated respiratory disease (AERD) is a syndrome of high type 2 inflammation and is known to critically involve mast cell activation. The mast cell is an important cell in the baseline inflammatory processes in the upper and lower airway by maintaining and amplifying type 2 inflammation. But it also is prominent in the hypersensitivity reaction to COX-1 inhibition which defines this condition.

RECENT FINDINGS

Recent work highlights the mast cell as a focal point in AERD pathogenesis. Using AERD as a specific model of both high type 2 asthma and chronic sinusitis, the role of mast cell activity can be better understood in other aspects of airway inflammation. Further dissecting out the mechanism of COX-1-mediated mast cell activation in AERD will be an important next phase in our understanding of NSAID-induced hypersensitivity as well as AERD pathophysiology.

Venous blood parameters in determination of respiratory impairment in amyotrophic lateral sclerosis

This study aimed to investigate the relationship between venous blood parameters and respiratory functions in patients with amyotrophic lateral sclerosis (ALS) and develop a model to predict respiratory impairment for individual patients with ALS. A total of 416 ALS patients were included in the study, and various hematologic and biochemical laboratory parameters as well as demographic and clinical factors were collected and compared. A multivariable logistic regression model was constructed to assess the association between FVC and venous blood biomarkers and clinical factors. The results showed that along with onset age, bulbar-onset, disease duration, BMI, eosinophil count (EO#), basophil count (BASO#), creatinine (CREA), uric acid (URCI) and low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL/HDL) ratio were associated with reduced FVC. The area under the ROC curve is 0.735 for the test set and 0.721 for the validation set. The study also developed a relatively acceptable model for predicting respiratory impairment in ALS patients. These findings suggest that EO#, BASO#, CREA, URIC and LDL/HDL ratio can be useful in assessing FVC in ALS and can be easily accessible, accurate, and low-cost parameters.

Aspirin-exacerbated respiratory disease: Updates in the era of biologics

OBJECTIVE

Aspirin-exacerbated respiratory disease (AERD) is a chronic respiratory condition characterized by severe chronic rhinosinusitis with nasal polyps (CRSwNP), eosinophilic asthma, and respiratory reactions to cyclooxygenase inhibitors. The management of AERD has evolved recently with the availability of respiratory biologics for treatment of severe asthma and CRSwNP. The objective of this review is to provide an update on the management of AERD in the era of respiratory biologic therapy.

DATA SOURCES

A literature review of pathogenesis and treatment of AERD, with a specific focus on biologic therapies in AERD, was performed through publications gathered from PubMed.

STUDY SELECTIONS

Original research, randomized controlled trials, retrospective studies, meta-analyses, and case series of high relevance are selected and reviewed.

RESULTS

Aspirin therapy after desensitization (ATAD) and respiratory biologic therapies targeting interleukin (IL)-4Rα, IL-5, IL-5Rα, and immunoglobulin E, all have some efficacy in the treatment of CRSwNP and asthma in patients with AERD. There are currently no head-to-head studies comparing ATAD vs respiratory biologic therapy, or specific respiratory biologics, for asthma and CRSwNP in patients with AERD.

CONCLUSION

Advances in our understanding of the fundamental drivers of the chronic respiratory inflammation in asthma and CRSwNP have led to the identification of several potential therapeutic targets for these diseases that can be used in patients with AERD. Further study of the use of ATAD and biologic therapy, independently and together, will help to inform future treatment algorithms for patients with AERD.

Mechanistic and clinical updates in AERD: 2021-2022

Aspirin-exacerbated respiratory disease (AERD) is a unique and often clinically severe disease affecting a subgroup of adults with asthma and chronic rhinosinusitis with nasal polyposis. Works published in 2021-2022 confirmed the critical role of lipid mediator dysregulation and mast cell activation and expanded our understanding of basophils, macrophages, fibrin dysregulation, and the 15-lipoxygenase pathway in disease pathogenesis. Translational studies established inflammatory heterogeneity in the upper and lower airway at baseline and during aspirin-induced respiratory reactions. Clinical cohorts provided insights into the mechanistic actions of frequently utilized biologic therapies in AERD. These advances are already changing clinical care delivery and affecting patient outcomes. Despite this, further work is needed to improve clinical tools to reliably diagnose AERD and identify factors that could prevent development of the disease altogether. Additionally, the impact of inflammatory heterogeneity on clinical trajectories and the utility and safety of combination biologic and daily aspirin therapies remains unanswered.

[Correlation between chronic sinusitis subtypes and basophil levels in peripheral blood]

Objective:To explore the clinical correlation between peripheral blood basophil levels and chronic sinusitis （CRS） subtypes. Methods:One hundred and twenty-six patients with CRS and 103 healthy cases from physical examination admitted to the First Affiliated Hospital of Soochow University from January 2021 to October 2022 were retrospectively analyzed. According to the histopathological classification, CRS patients were divided into eosinophilic chronic sinusitis （eCRS） group （47 cases） and non eosinophilic chronic sinusitis （non-eCRS） group （79 cases）. The differences among the three groups in peripheral blood inflammation cell counts, eosinophils-to-basophils ratio（bEBR）, basophils-to-neutrophils ratio（BNR）, basophils-to-lymphocytes ratio（BLR）, basophils-to-monocytes ratio（BMR） were compared, and study the correlation between each index and Lund-Mackay score, and the correlation between basophils in peripheral blood and other inflammatory cells. Results:The counts of basophils in the peripheral blood of the healthy control group, eCRS group and non-eCRS group were 0.03±0.01, 0.04±0.02, 0.03±0.02, respectively, the eosinophils-to-basophils ratio（bEBR） were 5.64±4.22, 8.38±5.95, 4.55±3.90, the basophils-to-neutrophils ratio（BNR） were 0.01±0, 0.01±0.01, 0.01±0.01, and the basophils-to-lymphocytes ratio（BLR） were 0.01±0.01, 0.02±0.01, and 0.02±0.01, respectively, the basophils-to-monocytes ratio（BMR） were 0.08±0.04, 0.11±0.06, and 0.08 ±0.04 respectively. There was a statistically significant difference between eCRS group and healthy control group, non-eCRS group（P<0.01）, while there was no statistically significant difference between non-eCRS group and healthy control group（P>0.05）. Basophil counts （r=0.185 5, P<0.05）, BLR（r=0.226 9, P<0.05）, BMR（r=0.228 1, P<0.01） in patients with CRS were positively correlated with Lund Makey score. In addition, basophils were also positively correlated with eosinophils（r=0.479 2, P<0.01）, lymphocytes（r=0.259 4, P<0.01）, and monocytes（r=0.256 4, P<0.01） in patients with CRS. Conclusion:The peripheral blood basophil count, BLR and BMR were significantly increased in eCRS, and were significantly positively correlated with Lund -Makey score. It has the potential to develop into disease biomarkers and new therapeutic targets of eCRS.

Non-eosinophilic asthma in nonsteroidal anti-inflammatory drug exacerbated respiratory disease

BACKGROUND

The cellular inflammatory pattern of nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD) is heterogeneous. However, data on the heterogeneity of non-eosinophilic asthma (NEA) with aspirin hypersensitivity are scanty. By examination of N-ERD patients based on clinical data and eicosanoid biomarkers we aimed to identify NEA endotypes potentially guiding clinical management.

METHODS

Induced sputum was collected from patients with N-ERD. Sixty six patients (49.6% of 133 N-ERD) with NEA were included in the hierarchical cluster analysis based on clinical and laboratory data. The quality of clustering was evaluated using internal cluster validation with different indices and a practical decision tree was proposed to simplify stratification of patients.

RESULTS

The most frequent NEA pattern was paucigranulocytic (PGA; 75.8%), remaining was neutrophilic asthma (NA; 24.2%). Four clusters were identified. Cluster #3 included the highest number of NEA patients (37.9%) with severe asthma and PGA pattern (96.0%). Cluster #1 (24.2%) included severe only asthma, with a higher prevalence of NA (50%). Cluster #2 (25.8%) comprised well-controlled mild or severe asthma (PGA; 76.5%). Cluster #4 contained only 12.1% patients with well-controlled moderate asthma (PGA; 62.5%). Sputum prostaglandin D2 levels distinguished cluster #1 from the remaining clusters with an area under the curve of 0.94.

CONCLUSIONS

Among identified four NEA subtypes, clusters #3 and #1 represented N-ERD patients with severe asthma but a different inflammatory signatures. All the clusters were discriminated by sputum PGD2 levels, asthma severity, and age of patients. The heterogeneity of non-eosinophilic N-ERD suggests a need for novel targeted interventions.

Endotyping Chronic Rhinosinusitis with Nasal Polyps: Understanding Inflammation Beyond Phenotypes

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a heterogenous group of inflammatory conditions impacting the nose and paranasal sinuses. Our understanding of the underlying pathobiology of CRSwNP has substantially improved due to ongoing translational research efforts. Advances in treatment options, including targeted respiratory biologic therapy for CRSwNP, allow for more personalized approaches for CRSwNP patient care. Patients with CRSwNP are typically classified to one or more endotype based on the presence of type 1, type 2, and type 3 inflammation. This review will discuss recent advances in our understanding of CRSwNP and how this may impact current and future treatment approaches for patients with CRSwNP.

What happens to basophils and tryptase, LXA4 and CysLTs during aspirin desensitization?

INTRODUCTION

Aspirin desensitization (AD) is an effective treatment in patients with non-steroidal anti-inflammatory drugs (NSAID)-exacerbated respiratory disease (NERD) by providing inhibitory effect on symptoms and polyp recurrence. However, limited data is available on how AD works. We aimed to study comprehensively the mechanisms underlying AD by examining basophil activation (CD203c upregulation), mediator-releases of tryptase, CysLT, and LXA₄, and LTB₄ receptor expression for the first 3 months of AD.

METHODS

The study was conducted in patients with NERD who underwent AD (group 1: n = 23), patients with NERD who received no desensitization (group 2: n = 22), and healthy volunteers (group 3, n = 13). All participants provided blood samples for flow cytometry studies (CD203c and LTB₄ receptor), and mediator releases (CysLT, LXA_4, and tryptase) for the relevant time points determined.

RESULTS

All baseline parameters of CD203c and LTB₄ receptor expressions, tryptase, CysLT, and LXA₄ releases were similar in each group (p > 0.05). In group 1, CD203c started to be upregulated at the time of reactions during AD, and continued to be high for 3 months when compared to controls. All other study parameters were comparable with baseline and at the other time points in each group (p > 0.05).

CONCLUSION

Although basophils are active during the first 3 months of AD, no releases of CysLT, tryptase or LXA₄ exist. Therefore, our results suggest that despite active basophils, inhibition of mediators can at least partly explain underlying the mechanism in the first three months of AD.

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?

Immunological Aspects of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is related to persistent inflammation with a dysfunctional relationship between environmental agents and the host immune system. Disturbances in the functioning of the sinus mucosa lead to common clinical symptoms. The major processes involved in the pathogenesis of CRS include airway epithelial dysfunctions that are influenced by external and host-derived factors which activate multiple immunological mechanisms. The molecular bases for CRS remain unclear, although some factors commonly correspond to the disease: bacterial, fungal and viral infections, comorbidity diseases, genetic dysfunctions, and immunodeficiency. Additionally, air pollution leads increased severity of symptoms. CRS is a heterogeneous group of sinus diseases with different clinical courses and response to treatment. Immunological pathways vary depending on the endotype or genotype of the patient. The recent knowledge expansion into mechanisms underlying the pathogenesis of CRS is leading to a steadily increasing significance of precision medicine in the treatment of CRS. The purpose of this review is to summarize the current state of knowledge regarding the immunological aspects of CRS, which are essential for ensuring more effective treatment strategies.

Effects of airway deformation and alveolar pores on particle deposition in the lungs

The distal lung (G14-G23), which are composed of alveoli and bronchi, are responsible for almost all gas exchange and micro- and nanoparticle deposition in the lungs. In the existing research using computational fluid dynamics, the geometric modeling accuracy of the bronchial bifurcation structure is given priority, and then the alveoli are attached to bronchi as discrete spherical crowns. This method ignores the correlation between alveoli. In fact, the alveoli have a tessellated distribution, and adjacent alveoli are connected by several alveolar pores. Due to the huge number of alveoli, this seemingly small difference will be greatly amplified, which may lead to a large deviation in the prediction of the overall flow. Accordingly, the objective of this study is to construct a two-dimensional distal lung model including the bronchi, acini, and alveolar pores by using the methods of regular hexagonal tessellational subdivision, fusion, and coordinate transformation. A moving boundary is introduced to simulate the process of airflow and particle deposition in the distal lung, and the effects of bronchial deformation, respiratory frequency, and alveolar pores are obtained. The results show that there are significant differences in intrapulmonary flow patterns with and without alveolar pores. Alveolar pores can establish bypass ventilation downstream of a blockage, thus providing a pathway for particles to enter the airways downstream of the blockage. Changing the respiratory frequency and the amplitude of bronchial deformation will change the relative velocity between particles and moving wall, which, in turn, will change the particle deposition efficiency in the distal lung. To summarize this study, a geometric modeling method for the distal lung with alveolar pores is established, and the important roles of detailed characteristics of the distal lung are revealed. The findings of this study provide a reasonable hydrodynamic mechanism for the prevention of related respiratory diseases.

Role of Basophils in a Broad Spectrum of Disorders

Basophils are the rarest granulocytes and have long been overlooked in immunological research due to their rarity and similarities with tissue-resident mast cells. In the last two decades, non-redundant functions of basophils have been clarified or implicated in a broad spectrum of immune responses, particularly by virtue of the development of novel analytical tools for basophils. Basophils infiltrate inflamed tissues of patients with various disorders, even though they circulate in the bloodstream under homeostatic conditions. Depletion of basophils results in the amelioration or exaggeration of inflammation, depending on models of disease, indicating basophils can play either beneficial or deleterious roles in a context-dependent manner. In this review, we summarize the recent findings of basophil pathophysiology under various conditions in mice and humans, including allergy, autoimmunity, tumors, tissue repair, fibrosis, and COVID-19. Further mechanistic studies on basophil biology could lead to the identification of novel biomarkers or therapeutic targets in a broad range of diseases.

Mechanisms and pathogenesis of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by local inflammation of the upper airways and is historically divided into 2 main phenotypes: CRS with nasal polyps and CRS without nasal polyps. Inflammation in CRS is mainly characterized by 3 endotypes based on elevation of canonical lymphocyte cytokines: type (T) 1 (T1) by TH1 cytokine IFN-γ, T2 by TH2 cutokines IL-4, IL-5, and IL-13, and T3 by TH17 cytokines including IL-17. Inflammation in both CRS without nasal polyps and CRS with nasal polyps is highly heterogeneous, and the frequency of various endotypes varies geographically around the world. This finding complicates establishment of a unified understanding of the mechanisms of pathogenesis in CRS. Sinonasal epithelium acts as a passive barrier, and epithelial barrier dysfunction is a common feature in CRS induced by endotype-specific cytokines directly and indirectly. The sinonasal epithelium also participates in both innate immunity via recognition by innate pattern-recognition receptors and promotes and regulates adaptive immunity via release of chemokines and innate cytokines including thymic stromal lymphopoietin. The purpose of this review was to discuss the contribution of the epithelium to CRS pathogenesis and to update the field regarding endotypic heterogeneity and various mechanisms for understanding pathogenesis in CRS.

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.

New concepts for the pathogenesis and management of aspirin-exacerbated respiratory disease

PURPOSE OF REVIEW

The purpose of this review is to provide a comprehensive summary of the current understanding of the pathogenesis of aspirin-exacerbated respiratory disease (AERD), and an update on its management.

RECENT FINDINGS

Elevated levels of 15-oxo-eicosatetraenoic acid (15-Oxo-ETE), a newly described metabolite of arachidonic acid, have been identified in nasal polyps of AERD patients. In nasal polyps, activated basophils, and interleukin-5 -receptor-α-positive IL-5Rα+ plasma cells are associated with more severe nasal polyposis in AERD. Alveolar monocyte-derived macrophages and their persistent proinflammatory activation were suggested as putative factors contributing to AERD. Although not AERD-specific, three biological agents are now available for the management of both nasal polyposis and asthma.

SUMMARY

A newly downstream product of 15-lipoxygenase, 15-Oxo-ETE, was recently found to be significantly elevated in nasal polyps from AERD patients. This eicosanoid metabolite likely originates from an interplay between epithelial cells and mast cells. Nasal polyp basophils, IL-5Rα+ plasma cells, and alveolar macrophages were identified as important contributors to inflammation in AERD. Besides traditional aspirin desensitization and treatment for AERD management, several biologics for treatment of asthma are available, including three that have been approved for nasal polyposis. These biologic agents show variable rates of success in controlling AERD symptoms.

Elevated Serum Leptin Levels in Patients With Eosinophilic Chronic Rhinosinusitis

Background: Eosinophilic chronic sinusitis (ECRS) is a subtype of CRS with nasal polyps (CRSwNP) that is frequently comorbid with asthma. Notably, ECRS patients often show a high recurrence of NPs after surgical resection. Leptin is a hormone produced by adipocytes that has been implicated in airway inflammatory diseases. However, to date, the role of leptin in ECRS has not been investigated. Objective: To determine whether the serum levels of leptin are altered in patients with ECRS. Methods: In total, 40 patients with ECRS, 15 patients with non-eosinophilic CRS (non-ECRS), and 12 individuals without CRS (control) were included in this study. Patient's serum leptin levels were assessed, and the number of eosinophils in their NPs were measured through a histological evaluation of the three densest areas with cellular infiltrate beneath the epithelial surface. Finally, nasal fibroblast cultures established from NPs were stimulated with varying concentrations of recombinant leptin in vitro to determine whether leptin affects eotaxin-3 (Chemokine (C-C motif) ligand 26 :26: CCL26) expression. Results: The serum leptin levels in both the ECRS and non-ECRS groups were significantly higher than those in the control subjects (p < 0.0001 vs. ECRS; p < 0.05 vs. non-ECRS). Furthermore, ECRS patients displayed significantly elevated serum leptin levels compared to non-ECRS patients (p < 0.001), although there was no difference in body mass index between the groups. Notably, serum leptin levels were correlated with the proportion of eosinophils in peripheral blood (r = 0.3575, p < 0.01) and the number of eosinophils in NPs (r = 0.5109, p < 0.0001). Serum leptin levels were also correlated with eotaxin-3 mRNA expression in NPs (r = 0.5374, p < 0.01). Finally, leptin significantly augmented eotaxin-3 expression in nasal fibroblasts established in vitro from NPs in a leptin receptor-dependent manner (p < 0.05). Conclusion: Leptin levels are elevated in ECRS patients and may both promote and indicate the severity of ECRS as well as systemic type 2-biased inflammatory responses. Combined, these data indicate that circulating leptin may play a significant role in the development of eosinophilic inflammation in NPs.

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.

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.