Interaction of eosinophilic and neutrophilic inflammation in patients with chronic rhinosinusitis

PURPOSE OF REVIEW

In the past year, the endotype of chronic rhinosinusitis (CRS) has been studied from a new perspective. Eosinophilic and neutrophilic inflammation are not independent processes in the pathogenesis of CRS. In this review, we will focus on recent research on mixed eosinophilic-neutrophilic inflammation in CRS and discuss the mechanism and potential treatments.

RECENT FINDINGS

Traditionally, patients with eosinophilic CRS (ECRS) present with severe clinical manifestations, comorbidities, and a higher recurrence rate. Recent studies have found that approximately 40% of patients with ECRS present with neutrophilic infiltration, while patients with predominantly eosinophilic infiltration along with neutrophilic inflammation present with more complex inflammation, clinical manifestations and exhibit refractory characteristics.

SUMMARY

The complex inflammatory profile and refractory clinical characteristics of mixed eosinophilic-neutrophilic inflammation in CRS are current challenges for clinicians. We summarize the features of eosinophilic and neutrophilic inflammation and current studies on the mechanisms of mixed eosinophilic-neutrophilic inflammation and suggest potentially effective therapeutic methods. We hope that this review will help with determining precise treatment options for patients.

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.

The current findings in eosinophilic chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a persistent inflammatory disease of the nasal cavity and paranasal sinuses. Traditional classification is denoted by the presence (CRSwNP) or absence of nasal polyps (CRSsNP). Particularly, CRSwNP is distinguished by the presence of infiltrating cells and inflammatory markers in the nasal mucosa. Patients with CRSwNP in Western countries predominantly display a type 2 endotype, whereas those in Asian regions display a mixed type 2 endotype. Nevertheless, recent transcriptome analyses have revealed two types of nasal polyps - type 2 and non-type 2 polyps, suggesting that geographical differences in endotypes likely resulted from the different proportions of each endotype. Moreover, various endotypes of CRSsNP have been identified, making phenotype a crucial factor for predicting treatment efficacy. Type 2 endotypes, designated as eosinophilic CRS (ECRS) in Japan, are characterized by severe eosinophilic infiltration into the paranasal sinus tissue and are particularly refractory. In this review, we discuss the latest developments in ECRS. We also provide recent findings on the involvement of nasal epithelial cells in pathogenesis.

The functional role of CST1 and CCL26 in asthma development

BACKGROUND

Asthma is the most common chronic disease in children with an increasing prevalence. Its development is caused by genetic and environmental factors and allergic sensitization is a known trigger. Dog allergens affect up to 30% of all children and dog dander-sensitized children show increased expression of cystatin-1 (CST1) and eotaxin-3 (CCL26) in nasal epithelium. The aim of our study was to investigate the functional mechanism of CST1 and CCL26 in the alveolar basal epithelial cell line A549.

METHODS

A549 cells were transfected with individual overexpression vectors for CST1 and CCL26 and RNA sequencing was performed to examine the transcriptomics. edgeR was used to identify differentially expressed genes (= DEG, |log2 FC | ≥ 2, FDR < 0.01). The protein expression levels of A549 cells overexpressing CST1 and CCL26 were analyzed using the Target 96 inflammation panel from OLINK (antibody-mediated proximity extension-based assay; OLINK Proteomics). Differentially expressed proteins were considered with a |log2 FC| ≥ 1, p < .05.

RESULTS

The overexpression of CST1 resulted in a total of 27 DEG (1 upregulated and 26 downregulated) and the overexpression of CCL26 in a total of 137 DEG (0 upregulated and 137 downregulated). The gene ontology enrichment analysis showed a significant downregulation of type I and III interferon signaling pathway genes as well as interferon-stimulated genes. At the protein level, overexpression of CST1 induced a significantly increased expression of CCL3, whereas CCL26 overexpression led to increased expression of HGF, and a decrease of CXCL11, CCL20, CCL3 and CXCL10.

CONCLUSION

Our results indicate that an overexpression of CST1 and CCL26 cause a downregulation of interferon related genes and inflammatory proteins. It might cause a higher disease susceptibility, mainly for allergic asthma, as CCL26 is an agonist for CCR-3-carrying cells, such as eosinophils and Th2 lymphocytes, mostly active in allergic asthma.

Lipocalin-2 promotes neutrophilic inflammation in nasal polyps and its value as biomarker

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common chronic inflammatory disease of the nasal cavity and paranasal sinuses. The role of neutrophils in the pathogenesis of CRSwNP has attracted more attention in recent years, due to its association with more severe disease and reduced steroid responsiveness. Lipocalin-2 (LCN2) has been found to modulate neutrophils infiltration in other neutrophilic inflammation including inflammatory bowel disease, rheumatoid arthritis, and psoriasis. The aim was to evaluate the expression and regulator role of LCN2 in neutrophilic inflammation in CRSwNP, and its role as a potential biomarker predicting non-eosinophilic CRSwNP (neCRSwNP).

METHODS

Bioinformatic analysis, immunostainings, real-time PCR and ELISA were used to analyze the expression and location of LCN2 in nasal tissues. The expression of proinflammatory mediators were assessed in nasal tissues and secretions. LCN2 production in human nasal epithelial cells (HNECs) and neutrophils, as well as its role in neutrophilic inflammation was evaluated by in vitro experiments.

RESULTS

LCN2 was mainly located in neutrophils and HNECs of nasal polyps. LCN2 expression was also significantly higher in the polyp tissue and nasal secretions from patients with neCRSwNP. The LCN2 levels were positively correlated with type 3 inflammation markers, including G-CSF, IL-8, and IL-17. LCN2 expression could be upregulated by IL-17 A and TNF-α in HNECs, and LCN2 could also promote the expression of IL-8 in dispersed polyp cells and HNECs.

CONCLUSIONS

LCN2 could serve as a novel biomarker predicting patients with neCRSwNP, and the increased expression of LCN2 may participate in the pathogenesis of neCRSwNP.

Eosinophilic Chronic Rhinosinusitis and Pathogenic Role of Protease

Chronic rhinosinusitis (CRS) is an inflammation of the nasal and paranasal sinus mucosa, and eosinophilic CRS (eCRS) is a subtype characterized by significant eosinophil infiltration and immune response by T-helper-2 cells. The pathogenesis of eCRS is heterogeneous and involves various environmental and host factors. Proteases from external sources, such as mites, fungi, and bacteria, have been implicated in inducing type 2 inflammatory reactions. The balance between these proteases and endogenous protease inhibitors (EPIs) is considered important, and their imbalance can potentially lead to type 2 inflammatory reactions, such as eCRS. In this review, we discuss various mechanisms by which exogenous proteases influence eCRS and highlight the emerging role of endogenous protease inhibitors in eCRS pathogenesis.

Type 2 Cystatins and Their Roles in the Regulation of Human Immune Response and Cancer Progression

Cystatins are a family of intracellular and extracellular protease inhibitors that inhibit cysteine cathepsins-a group of lysosomal cysteine proteases that participate in multiple biological processes, including protein degradation and post-translational cleavage. Cysteine cathepsins are associated with the development of autoimmune diseases, tumor progression, and metastasis. Cystatins are categorized into three subfamilies: type 1, type 2, and type 3. The type 2 cystatin subfamily is the largest, containing 10 members, and consists entirely of small secreted proteins. Although type 2 cystatins have many shared biological roles, each member differs in structure, post-translational modifications (e.g., glycosylation), and expression in different cell types. These distinctions allow the type 2 cystatins to have unique biological functions and properties. This review provides an overview of type 2 cystatins, including their biological similarities and differences, their regulatory effect on human immune responses, and their roles in tumor progression, immune evasion, and metastasis.

Cis- and trans-eQTM analysis reveals novel epigenetic and transcriptomic immune markers of atopic asthma in airway epithelium

BACKGROUND

Expression quantitative trait methylation (eQTM) analyses uncover associations between DNA methylation markers and gene expression. Most eQTM analyses of complex diseases have focused on cis-eQTM pairs (within 1 megabase).

OBJECTIVES

This study sought to identify cis- and trans-methylation markers associated with gene expression in airway epithelium from youth with and without atopic asthma.

METHODS

In this study, the investigators conducted both cis- and trans-eQTM analyses in nasal (airway) epithelial samples from 158 Puerto Rican youth with atopic asthma and 100 control subjects without atopy or asthma. The investigators then attempted to replicate their findings in nasal epithelial samples from 2 studies of children, while also examining whether their results in nasal epithelium overlap with those from an eQTM analysis in white blood cells from the Puerto Rican subjects.

RESULTS

This study identified 9,108 cis-eQTM pairs and 2,131,500 trans-eQTM pairs. Trans-associations were significantly enriched for transcription factor and microRNA target genes. Furthermore, significant cytosine-phosphate-guanine sites (CpGs) were differentially methylated in atopic asthma and significant genes were enriched for genes differentially expressed in atopic asthma. In this study, 50.7% to 62.6% of cis- and trans-eQTM pairs identified in Puerto Rican youth were replicated in 2 smaller cohorts at false discovery rate-adjusted P < .1. Replicated genes in the trans-eQTM analysis included biologically plausible asthma-susceptibility genes (eg, HDC, NLRP3, ITGAE, CDH26, and CST1) and are enriched in immune pathways.

CONCLUSIONS

Studying both cis- and trans-epigenetic regulation of airway epithelial gene expression can identify potential causal and regulatory pathways or networks for childhood asthma. Trans-eQTM CpGs may regulate gene expression in airway epithelium through effects on transcription factor and microRNA target genes.

Tezepelumab Efficacy in Patients with Severe, Uncontrolled Asthma with Comorbid Nasal Polyps in NAVIGATOR

Purpose

Tezepelumab, a human monoclonal antibody, blocks thymic stromal lymphopoietin. In the phase 3 NAVIGATOR study (NCT03347279), tezepelumab reduced annualized asthma exacerbation rates (AAERs) versus placebo, irrespective of baseline disease characteristics, and improved lung function and symptom control versus placebo in adults and adolescents with severe, uncontrolled asthma. We assessed the efficacy of tezepelumab in patients with severe asthma with or without nasal polyps (NPs) in the 2 years before randomization in NAVIGATOR.

Methods

Patients with severe asthma (N=1059) were randomized (1:1) and received tezepelumab 210 mg or placebo every 4 weeks subcutaneously for 52 weeks. Prespecified exploratory analyses included: AAER over 52 weeks and changes from baseline to week 52 in pre-bronchodilator forced expiratory volume in 1 second, Sino-Nasal Outcome Test (SNOT)-22 scores, and asthma control and health-related quality life (HRQoL) outcomes in NP subgroups. Changes from baseline in fractional exhaled nitric oxide (FeNO), blood eosinophil counts, total immunoglobulin E (IgE), eosinophil-derived neurotoxin (EDN), matrix metalloproteinase-10 (MMP-10), and serum interleukin (IL)-5, IL-6, IL-8 and IL-13 were assessed (post hoc).

Results

Tezepelumab reduced the AAER over 52 weeks versus placebo by 85% (95% confidence interval [CI]: 72, 92; n=118) and 51% (95% CI: 40, 60; n=941) in patients with and without NPs, respectively. At week 52, tezepelumab improved lung function, asthma control and HRQoL versus placebo in patients with and without NPs. Tezepelumab reduced SNOT-22 total scores (least-squares mean difference versus placebo [95% CI]) in patients with NPs at 28 weeks (-12.57 points [-19.40, -5.73]) and 52 weeks (-10.58 points [-17.75, -3.41]). At week 52, tezepelumab reduced blood eosinophil counts and FeNO, IgE, IL-5, IL-13, EDN and MMP-10 levels versus placebo, irrespective of NP status.

Conclusion

Tezepelumab resulted in clinically meaningful improvements in sino-nasal symptoms and asthma outcomes in patients with severe asthma with comorbid NPs.

Thymic Stromal Lymphopoietin (TSLP), Its Isoforms and the Interplay with the Epithelium in Allergy and Asthma

Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine that has emerged as a critical player in the development and progression of allergy and asthma. It is primarily produced by epithelial cells and functions as a potent immune system activator. TSLP acts through interaction with its receptor complex, composed of the TSLP receptor (TSLPR) and interleukin-7 receptor alpha chain (IL-7Rα), activating downstream complex signalling pathways. The TSLP major isoform, known as long-form TSLP (lfTSLP), is upregulated in the airway epithelium of patients with allergic diseases. More research is warranted to explore the precise mechanisms by which short-form TSLP (sfTSLP) regulates immune responses. Understanding the dynamic interplay between TSLP and the dysfunctional epithelium provides insights into the mechanisms underlying allergy and asthma pathogenesis. Targeting TSLP represents an important therapeutic strategy, as it may upstream disrupt the inflammatory cascade and alleviate symptoms associated with allergic inflammation.

Precision medicine in chronic rhinosinusitis - using endotype and endotype-driven therapeutic options

INTRODUCTION

Chronic rhinosinusitis (CRS) is a heterogeneous disease, and its complex pathophysiological characteristics pose a challenge to its clinical treatment. CRS is distinguished not only by clinical phenotype but also by endotype characteristics, which are divided into type 2 CRS and non-type 2 CRS.

AREAS COVERED

In this review, we summarize and discuss current studies that depict the mechanisms and endotypes of CRS. In particular, inflammatory cells and the microbiome play a role in the pathophysiology of CRS. We also listed some of the biomarkers described in recent studies that may serve as a theoretical foundation for additional investigations. We have summarized the advantages and disadvantages of existing treatments and listed the available biological treatments for CRS in detail.

EXPERT OPINION

Endotype-driven therapeutic options face many challenges because of the complexity of the disease. Glucocorticoids, nasal endoscopic surgery, and biological therapy are the main treatments used in clinical practice, but they have limitations. This review provides advice on the clinical management and treatment options for patients with different endotypes, which will be more conducive to improving the quality of life and reducing the financial burden on patients.

A review of current biomarkers in chronic rhinosinusitis with or without nasal polyps

INTRODUCTION

Chronic rhinosinusitis (CRS) is a heterogeneous disease with a variety of cellular and molecular pathophysiologic mechanisms. Biomarkers have been explored in CRS using various phenotypes, such as polyp recurrence after surgery. Recently, the presence of regiotype in CRS with nasal polyps (CRSwNP) and the introduction of biologics for the treatment of CRSwNP has indicated the importance of endotypes, and there is a need to elucidate endotype-based biomarkers.

AREAS COVERED

Biomarkers for eosinophilic CRS, nasal polyps, disease severity, and polyp recurrence have been identified. Additionally, endotypes are being identified for CRSwNP and CRS without nasal polyps using cluster analysis, an unsupervised learning technique.

EXPERT OPINION

Endotypes in CRS have still being established, and biomarkers capable of identifying endotypes of CRS are not yet clear. When identifying endotype-based biomarkers, it is necessary to first identify endotypes clarified by cluster analysis for outcomes. With the application of machine learning, the idea of predicting outcomes using a combination of multiple integrated biomarkers, rather than a single biomarker, will become mainstream.

Epithelial CST1 Promotes Airway Eosinophilic Inflammation in Asthma via the AKT Signaling Pathway

PURPOSE

Epithelial cystatin SN (CST1), a type 2 cysteine protease inhibitor, was significantly upregulated in asthma. In this study, we aimed to investigate the potential role and mechanism of CST1 in eosinophilic inflammation in asthma.

METHODS

Bioinformatics analysis on Gene Expression Omnibus datasets were used to explore the expression of CST1 in asthma. Sputum samples were collected from 76 asthmatics and 22 control subjects. CST1 mRNA and protein expression in the induced sputum were measured by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and western blotting. The possible function of CST1 was explored in ovalbumin (OVA)-induced eosinophilic asthma. Transcriptome sequencing (RNA-seq) was used to predict the possible regulated mechanism of CST1 in bronchial epithelial cells. Overexpression or knockdown of CST1 was further used to verify potential mechanisms in bronchial epithelial cells.

RESULTS

CST1 expression was significantly increased in the epithelial cells and induced sputum of asthma. Increased CST1 was significantly associated with eosinophilic indicators and T helper cytokines. CST1 aggravated airway eosinophilic inflammation in the OVA-induced asthma model. In addition, overexpression of CST1 significantly enhanced the phosphorylation of AKT and the expression of serpin peptidase inhibitor, clade B, member 2 (SERPINB2), while knockdown using anti-CST1 siRNA reversed the trend. Furthermore, AKT had a positive effect on SERPINB2 expression.

CONCLUSIONS

Increased sputum CST1 may play a key role in the pathogenesis of asthma through involvement in eosinophilic and type 2 inflammation through activation of the AKT signaling pathway, further promoting SERPINB2 expression. Therefore, targeting CST1 might be of therapeutic value in treating asthma with severe and eosinophilic phenotypes.

Cystatin SN in type 2 inflammatory airway diseases

Cystatin SN, encoded by CST1, belongs to the type 2 (T2) cystatin protein superfamily. In the past decade, several publications have highlighted the association between cystatin SN and inflammatory airway diseases including chronic rhinosinusitis, rhinitis, asthma, chronic obstructive pulmonary disease, and chronic hypersensitivity pneumonitis. It is, therefore, crucial to understand the role of cystatin SN in the wider context of T2 inflammatory diseases. Here, we review the expression of cystatin SN in airway-related diseases with different endotypes. We also emphasize the physiological and pathological roles of cystatin SN. Physiologically, cystatin SN protects host tissues from destructive proteolysis by cysteine proteases present in the external environment or produced via internal dysregulated expression. Pathologically, the secretion of cystatin SN from airway epithelial cells initiates and amplifies T2 immunity and subsequently leads to disease. We further discuss the development of cystatin SN as a T2 immunity marker that can be monitored noninvasively and assist in airway disease management. The discovery, biology, and inhibition capability are also introduced to better understand the role of cystatin SN in airway diseases.

Current Understanding of the Role of Eosinophils in CRSwNP and Implications for Treatment with Mepolizumab and Benralizumab

BACKGROUND

International consensus statements now subdivide chronic rhinosinusitis (CRS) into several phenotypes and endotypes, including the presence of polyps (CRSwNP) and eosinophilia (eCRSwNP). Biological treatments aimed at blocking eosinophilic inflammation in CRSwNP via interleukin 5 (IL5) or the interleukin 5 receptor (IL5R) have demonstrated limited efficacy thus far.

OBJECTIVE

To review the pathophysiology of eCRSwNP, the evidence for mepolizumab (anti-IL5) and benralizumab (anti-IL5R) in CRSwNP, and to highlight areas for future research and therapeutic intervention.

METHODS

Primary and secondary literature search.

RESULTS

Clinical trials on mepolizumab and benralizumab in CRSwNP are limited and restricted by trial design which prevents direct comparison with other interventions, including surgery. Both agents would appear to provide some benefit in reducing nasal polyp size but limited clinical patient benefit. Molecular biological research highlights that eCRSwNP can occur in the absence of IL5 and that other cells/cytokines play an important part in the disease's pathophysiology.

CONCLUSION

Blockade of IL5/IL5R alone would appear to provide limited "real life" clinical benefit in patients with CRSwNP due to the complexities of the pathophysiology of the condition. Therapy aimed at several simultaneous cytokine targets has logic but well-designed trials are unlikely to be forthcoming in the short term due to the financial cost and commercial conflicts of interest.

Network analyses of upper and lower airway transcriptomes identify shared mechanisms among children with recurrent wheezing and school-age asthma

Background

Predicting which preschool children with recurrent wheezing (RW) will develop school-age asthma (SA) is difficult, highlighting the critical need to clarify the pathogenesis of RW and the mechanistic relationship between RW and SA. Despite shared environmental exposures and genetic determinants, RW and SA are usually studied in isolation. Based on network analysis of nasal and tracheal transcriptomes, we aimed to identify convergent transcriptomic mechanisms in RW and SA.

Methods

RNA-sequencing data from nasal and tracheal brushing samples were acquired from the Gene Expression Omnibus. Combined with single-cell transcriptome data, cell deconvolution was used to infer the composition of 18 cellular components within the airway. Consensus weighted gene co-expression network analysis was performed to identify consensus modules closely related to both RW and SA. Shared pathways underlying consensus modules between RW and SA were explored by enrichment analysis. Hub genes between RW and SA were identified using machine learning strategies and validated using external datasets and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Finally, the potential value of hub genes in defining RW subsets was determined using nasal and tracheal transcriptome data.

Results

Co-expression network analysis revealed similarities in the transcriptional networks of RW and SA in the upper and lower airways. Cell deconvolution analysis revealed an increase in mast cell fraction but decrease in club cell fraction in both RW and SA airways compared to controls. Consensus network analysis identified two consensus modules highly associated with both RW and SA. Enrichment analysis of the two consensus modules indicated that fatty acid metabolism-related pathways were shared key signals between RW and SA. Furthermore, machine learning strategies identified five hub genes, i.e., CST1, CST2, CST4, POSTN, and NRTK2, with the up-regulated hub genes in RW and SA validated using three independent external datasets and qRT-PCR. The gene signatures of the five hub genes could potentially be used to determine type 2 (T2)-high and T2-low subsets in preschoolers with RW.

Conclusions

These findings improve our understanding of the molecular pathogenesis of RW and provide a rationale for future exploration of the mechanistic relationship between RW and SA.

Cystatin SN is a potent upstream initiator of epithelial-derived type 2 inflammation in chronic rhinosinusitis

BACKGROUND

Cystatin SN (CST1) and cystatin SA (CST2) are cysteine protease inhibitors that protect against allergen, viral, and bacterial proteases. Cystatins are overexpressed in the setting of allergic rhinitis and chronic rhinosinusitis with nasal polyps (CRSwNP); however, their role in promoting type 2 inflammation remains poorly characterized.

OBJECTIVE

The purpose of this study was to use integrated poly-omics and a murine exposure model to explore the link between cystatin overexpression in CRSwNP and type 2 inflammation.

METHODS

In this institutional review board- and institutional animal care and use committee-approved study, we compared tissue, exosome, and mucus CST1 and CST2 between CRSwNP and controls (n = 10 per group) by using matched whole exome sequencing, transcriptomic, proteomic, posttranslational modification, histologic, functional, and bioinformatic analyses. C57/BL6 mice were dosed with 3.9 μg/mL of CST1 or PBS intranasally for 5 to 18 days in the presence or absence of epithelial ABCB1a knockdown. Inflammatory cytokines were quantified by using Quansys multiplex assays or ELISAs.

RESULTS

Of the 1305 proteins quantified, CST1 and CST2 were among the most overexpressed protease inhibitors in tissue, exosome, and mucus samples; they were localized to the epithelial layer. Multiple posttranslational modifications were identified in the polyp tissue. Exosomal CST1 and CST2 were strongly and significantly correlated with eosinophils and Lund-Mackay scores. Murine type 2 cytokine secretion and TH2 cell infiltration increased in a time-dependent manner following CST1 exposure and was abrogated by epithelial knockdown of ABCB1a, a regulator of epithelial cytokine secretion.

CONCLUSION

CST1 is a potent upstream initiator of epithelial-derived type 2 inflammation in CRSwNP. Therapeutic strategies targeting CST activity and its associated posttranslational modifications deserve further interrogation.

Roles of Exosomes in Chronic Rhinosinusitis: A Systematic Review

The pathophysiology of chronic rhinosinusitis (CRS) is multifactorial and not entirely clear. The objective of the review was to examine the current state of knowledge concerning the role of exosomes in CRS. For this systematic review, we searched PubMed/MEDLINE, Scopus, CENTRAL, and Web of Science databases for studies published until 7 August 2022. Only original research articles describing studies published in English were included. Reviews, book chapters, case studies, conference papers, and opinions were excluded. The quality of the evidence was assessed with the modified Office and Health Assessment and Translation (OHAT) Risk of Bias Rating Tool for Human and Animal Studies. Of 250 records identified, 17 were eligible, all of which had a low to moderate risk of overall bias. Presented findings indicate that exosomal biomarkers, including proteins and microRNA, act as promising biomarkers in the diagnostics and prognosis of CRS patients and, in addition, may contribute to finding novel therapeutic targets. Exosomes reflecting tissue proteomes are excellent, highly available material for studying proteomic alterations noninvasively. The first steps have already been taken, but more advanced research on nasal exosomes is needed, which might open a wider door for individualized medicine in CRS.

Periostin as a biomarker in chronic rhinosinusitis: A contemporary systematic review

BACKGROUND

The role of periostin, a matricellular protein encoded by the POSTN gene, in chronic rhinosinusitis with nasal polyposis (CRSwNP) is reviewed. Periostin is considered a potential biomarker of endotype and may be useful for evaluating response to treatment.

METHODS

Search terms in PubMed and Web of Science (1990-March 2022) included: ((periostin) OR (POSTN)) AND ((sinusitis) OR (nasal polyp) OR (CRSwNP) OR (CRS). The primary outcomes were differences in tissue, serum, and nasal lavage between CRSwNP and CRS without NP (CRSsNP) or controls. Associated factors reported to affect periostin expression, data regarding participants' clinical characteristics, disease endotypes, laboratory methods, and samples' origin were also pooled. Studies on <10 patients were excluded.

RESULTS

Out of 101 records harvested through database searching, 29 prospective cross-sectional or case-control studies were eligible for review and qualitative analysis. Tissue sample origin, concurrent infection, current and past medication, primary or recurrent disease, allergic rhinitis, and smoking status should be considered as confounding factors for periostin levels. Periostin and POSTN messenger RNA (mRNA) levels were consistently and significantly higher in CRSwNP than CRSsNP and controls. Despite the distinctly different inflammation patterns among CRSwNP endotypes, periostin-related remodeling patterns seemed to be similar.

CONCLUSION

Tissue and serum periostin levels, and POSTN expression appear elevated in CRSwNP, especially in eosinophilic inflammation, compared to CRSsNP and controls. Disease severity and comorbidities are also reflected in periostin and POSTN values. Carefully designed prospective studies may establish the role of periostin as a biomarker in CRSwNP and allow its incorporation in clinical practice.

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.

Inflammatory molecular endotypes of nasal polyps derived from Caucasian and Japanese populations

BACKGROUND

Emerging evidence suggests that chronic rhinosinusitis with nasal polyps (CRSwNP) is a highly heterogeneous disease with disparate inflammatory characteristics between different racial groups and geographies. Little is known currently about possible distinguishing factors underlying these inflammatory differences.

OBJECTIVE

To interrogate for differences between Caucasian and Japanese CRSwNP disease using whole transcriptome and single-cell RNA gene expression profiling of nasal polyps (NPs).

METHODS

We performed whole transcriptome RNA sequencing (RNA-seq) with endotype stratification of NPs from 8 Caucasian (residing in USA) and 9 Japanese (residing in Japan) patients. Reproducibility was confirmed by qPCR in an independent validation set of 46 Caucasian and 31 Japanese patients. Single-cell RNA-seq stratified key cell types for contributory transcriptional signatures.

RESULTS

Unsupervised clustering analysis identified two major endotypes present within both NP cohorts, which have previously been reported at the cytokine level: 1) type 2 endotype and 2) non-type 2 endotype. Importantly, there was a statistically significant difference in the proportion of these endotypes between these geographically distinct NP subgroups (p = 0.03). Droplet-based single-cell RNA sequencing further identified prominent type 2 inflammatory transcript expression: C-C motif chemokine ligand 13 (CCL13) and CCL18 in M2 macrophages, as well as cystatin SN (CST1) and CCL26 in basal, suprabasal, and secretory epithelial cells.

CONCLUSION

NPs from both racial groups harbor the same two major endotypes, which we determine are present in differing ratios between each cohort with CRSwNP disease. Distinct inflammatory and epithelial cells contribute to the type 2 inflammatory profiles observed.

A Dynamic Transcriptome Map of Different Tissue Microenvironment Cells Identified During Gastric Cancer Development Using Single-Cell RNA Sequencing

Gastric cancer (GC) development trends have identified multiple processes ranging from inflammation to carcinogenesis, however, key pathogenic mechanisms remain unclear. Tissue microenvironment (TME) cells are critical for the progression of malignant tumors. Here, we generated a dynamic transcriptome map of various TME cells during multi-disease stages using single-cell sequencing analysis. We observed a set of key transition markers related to TME cell carcinogenic evolution, and delineated landmark dynamic carcinogenic trajectories of these cells. Of these, macrophages, fibroblasts, and endothelial cells exerted considerable effects toward epithelial cells, suggesting these cells may be key TME factors promoting GC occurrence and development. Our results suggest a phenotypic convergence of different TME cell types toward tumor formation processes in GC. We believe our data would pave the way for early GC detection, diagnosis, and treatment therapies.

Identification of Cysteine Protease Inhibitor CST2 as a Potential Biomarker for Colorectal Cancer

Additional biomarkers for the development and progression of colorectal cancer (CRC) remain to be identified. Hence, the current study aimed to identify potential diagnostic markers for CRC. Analyses of cysteine protease inhibitor [cystatins (CSTs)] expression in CRC samples and its correlation with cancer stage or survival in patients with CRC demonstrated that CRC tissues had greater CST1 and CST2 mRNA expression compared to noncancerous adjacent tissues, while higher CST2 mRNA expression in CRC tissues was correlated with advanced stages and disease-free survival in patients with CRC, encouraging further exploration on the role of CST2 in CRC. Through an online database search and tissue microarray (TMA), we confirmed that CRC samples had higher CST2 expression compared to noncancerous adjacent tissue or normal colorectal tissues at both the mRNA and protein levels. TMA also revealed that colorectal adenoma, CRC, and metastatic CRC tissues exhibited a significantly increased CST2 protein expression. Accordingly, survival analysis demonstrated that the increase in CST2 protein expression was correlated with shorter overall survival of patients with CRC. Moreover, our results found a significant upregulation of CST2 in multiple cancer tissues. Taken together, these findings suggest the potential role of CST2 as a diagnostic and prognostic biomarker for CRC.

Nasal upregulation of CST1 in dog-sensitised children with severe allergic airway disease

Background

The clinical presentation of children sensitised to dog dander varies from asymptomatic to severe allergic airway disease, but the genetic mechanisms underlying these differences are not clear. The objective of the present study was to investigate nasal transcriptomic profiles associated with dog dander sensitisation in school children and to reveal clinical symptoms related with these profiles.

Methods

RNA was extracted from nasal epithelial cell brushings of children sensitised to dog dander and healthy controls. Blood sample analyses included IgE against dog dander, dog allergen molecules, other airborne and food allergens, basophil activation and white blood cell counts. Clinical history of asthma and rhinitis was recorded, and lung function was assessed (spirometry, methacholine provocation and exhaled nitric oxide fraction).

Results

The most overexpressed gene in children sensitised to dog dander compared to healthy controls was CST1, coding for Cystatin 1. A cluster of these children with enhanced CST1 expression showed lower forced expiratory volume in 1 s, increased bronchial hyperreactivity, pronounced eosinophilia and higher basophil allergen threshold sensitivity compared with other children sensitised to dog dander. In addition, multi-sensitisation to lipocalins was more common in this group.

Conclusions

Overexpression of CST1 is associated with more severe allergic airway disease in children sensitised to dog dander. CST1 is thus a possible biomarker of the severity of allergic airway disease and a possible therapeutic target for the future treatment of airborne allergy.

Targeted therapy in eosinophilic chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common and preventable airway disease causing significant worldwide mortality and morbidity. Lifetime exposure to tobacco smoking and environmental particles are the two major risk factors. Over recent decades, COPD has become a growing public health problem with an increase in incidence. COPD is defined by airflow limitation due to airway inflammation and small airway remodelling coupled to parenchymal lung destruction. Most patients exhibit neutrophil-predominant airway inflammation combined with an increase in macrophages and CD8⁺ T-cells. Asthma is a heterogeneous chronic inflammatory airway disease. The most studied subtype is type 2 (T2) high eosinophilic asthma, for which there are an increasing number of biologic agents developed. However, both asthma and COPD are complex and share common pathophysiological mechanisms. They are known as overlapping syndromes as approximately 40% of patients with COPD present an eosinophilic airway inflammation. Several studies suggest a putative role of eosinophilia in lung function decline and COPD exacerbation. Recently, pharmacological agents targeting eosinophilic traits in uncontrolled eosinophilic asthma, especially monoclonal antibodies directed against interleukins (IL-5, IL-4, IL-13) or their receptors, have shown promising results. This review examines data on the rationale for such biological agents and assesses efficacy in T2-endotype COPD patients.

Patients with severe COPD and eosinophilic inflammation experience uncontrolled symptoms despite optimal pharmaceutical treatment. The development of new biomarkers is needed for better phenotyping of patients to propose innovative targeted therapy.https://bit.ly/2KzWuNO

Increased Thrombin-Activatable Fibrinolysis Inhibitor in Response to Sublingual Immunotherapy for Allergic Rhinitis

OBJECTIVES/HYPOTHESIS

The objective of this study was to determine the role of thrombin-activatable fibrinolysis inhibitor (TAFI) as a candidate biomarker for therapeutic efficacy of sublingual immunotherapy (SLIT) and to identify the role of TAFI in the pathogenesis of allergic rhinitis (AR).

STUDY DESIGN

Retrospective cohort study and laboratory study.

METHODS

Serum was collected from patients with allergies to Japanese cedar pollen before, during, and after treatment with SLIT. We measured the levels of immunoreactive TAFI, C3a, and C5a in serum by enzyme-linked immunosorbent assay (ELISA) and assessed their relative impact on a combined symptom-medication score. We also examined the impact of TAFI on mast cells and fibroblasts in experiments performed in vitro.

RESULTS

Serum levels of TAFI increased significantly in response to SLIT. By contrast, serum C3a levels decreased significantly over time; we observed a significant negative correlation between serum levels of TAFI versus C3a and symptom-medication score. Mast cell degranulation was inhibited in response to TAFI, as it was the expression of both CCL11 and CCL5 in cultured fibroblasts.

CONCLUSIONS

High serum levels of TAFI may be induced by SLIT. TAFI may play a critical protective role in pathogenesis of AR by inactivating C3a and by inhibiting mast cell degranulation and chemokines expression in fibroblasts.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Prognostic and pharmacologic value of cystatin SN for chronic rhinosinusitis with nasal polyps

BACKGROUND

Integrated care pathways improve the management of patients with chronic rhinosinusitis with nasal polyps (CRSwNP). The application of integrated care pathways requires development of endotype-based biomarkers to stratify patients. The value of cytokines and markers induced by cytokines for the management of CRSwNP is largely unknown.

OBJECTIVES

Our aim was to determine the prognostic and pharmacologic value of type 2, non-type 2 cytokines, and markers associated with type 2 inflammation, including CCL26, periostin, and cystatin SN, in nasal secretions for CRSwNP.

METHODS

This retrospective study assigned 151 patients with CRSwNP to the discovery and validation phases. Concentrations of cytokines, CCL26, periostin, and cystatin SN in nasal secretions were determined by using Luminex and ELISA. Predictive significance was assessed with receiver-operating characteristic curves. Survival analysis was performed by using Kaplan-Meier curves and Cox regression models.

RESULTS

Cystatin SN was an independent predictor of the uncontrolled status of CRSwNP over a 2-year follow-up after adjustment for other risk factors (hazard ratio = 1.168 and 1.132 in the discovery and validation phases, respectively; both P < .001). Patients with high cystatin SN concentrations presented with a faster onset and higher rate of uncontrolled status than did those with low levels (P < .001). Enhanced medical treatment for patients with high cystatin SN levels postponed the uncontrolled status in the discovery (P = .016) and validation (P = .002) phases but did not completely abolish it by the end of the follow-up.

CONCLUSION

Cystatin SN levels in nasal secretions hold strong prognostic value and can facilitate medical instructions for managing CRSwNP.

Baicalin suppresses type 2 immunity through breaking off the interplay between mast cell and airway epithelial cell

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Japanese herbal medicine Shin'iseihaito was reported to ameliorate the airway type 2 inflammatory response in clinical and experimental studies. Airway type 2 inflammatory diseases, including bronchial asthma and eosinophilic chronic rhinosinusitis (ECRS), often coexist and interact with each other. However, it is still unclear how Shin'iseihaito exerts its pharmacological effects on cells involved in airway mucosa.

AIM OF THE STUDY

This study aims to examine the direct effect of baicalin, a representative bioactive compound of Shin'iseihaito, on type 2 immune responses in human airway epithelial cells and mast cells.

MATERIAL AND METHODS

We measured the plasma pharmacokinetics of flavonoids derived from Shin'iseihaito and investigated the effects of baicalin on type 2 immune responses in human airway epithelial cells and human mast cells.

RESULTS

Baicalin, wogonin, and wogonoside were detected in the plasma. The maximum plasma concentration of baicalin was highest at 1610 ng/ml (3.6 μM). In the normal human bronchial epithelial cells treated with baicalin, with or without stimulation by IFN-γ, the IL-33 expression was significantly downregulated. However, baicalin treatment did not affect the levels of thymic stromal lymphopoietin and IL-25. We noted that IL-33-dependent expression of tryptase mRNA in mast cells was significantly inhibited by baicalin. Also, the expression of IL-5 in mast cells enhanced by stimulation with TSLP plus IL-1β was significantly downregulated by baicalin treatment. Moreover, the enhancement of IL-13 expression in mast cells by IL-33 simulation was also significantly inhibited by baicalin.

CONCLUSIONS

Our results prove that by breaking off the vicious circle of mast cells and airway epithelial cells, baicalin may be an effective alternative therapeutic option for the treatment of type 2 inflammatory diseases, such as ECRS and comorbid asthma.

Mechanisms and biomarkers of inflammatory endotypes in chronic rhinosinusitis without nasal polyps

BACKGROUND

Chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP) is a common disease that is characterized by multiple inflammatory endotypes. However, the molecular mechanisms in CRSsNP are poorly understood compared with those of polypoid CRS.

OBJECTIVE

Our aim was to identify mechanisms and biomarkers associated with inflammatory endotypes underpinning CRSsNP.

METHODS

Ethmoid tissues and nasal lavage fluids (NLFs) were obtained from control patients and patients with CRS. The gene expression profiles were determined by microarray analysis and quantitative RT-PCR, and expression of proteins was measured by ELISA and Luminex analysis.

RESULTS

Microarray found that compared with their levels of expression in control tissue, the levels of expression of 126, 241, and 545 genes were more than 3-fold and significantly elevated in CRSsNP with type 1 (T1) endotype, type 2 (T2) endotype, and type 3 (T3) endotype, respectively. Selected identified genes were confirmed by RT-PCR. Gene set enrichment analysis suggested that T1 CRSsNP was associated with IFN-γ signaling and antiviral immunity controlled by T cells (T_H1 and CD8⁺), natural killer cells, and antigen-presenting cells; T2 CRSsNP was associated with STAT6 signaling and IgE-mediated activation controlled by eosinophils, mast cells, T_H2 cells, group 2 innate lymphoid cells, and antigen-presenting cells; and T3 CRSsNP was associated with IL-17 signaling, acute inflammatory response, complement-mediated inflammation, and infection controlled by neutrophils, T_H17 cells, B cells, and antigen-presenting cells. The results suggest that T1 (CXCL9 and CXCL10), T2 (eosinophilic proteins and CCL26), and T3 (CSF3) endotypic biomarkers in NLF may be able to distinguish tissue endotypes in CRSsNP.

CONCLUSIONS

Inflammatory endotypes in CRSsNP were controlled by different molecular mechanisms. NLF biomarker assays may allow for more precise and personalized medical treatments in CRS.

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.

Definition and characteristics of acute exacerbation in adult patients with chronic rhinosinusitis: a systematic review

Background

Acute exacerbations (AE) in chronic rhinosinusitis (CRS) have been increasingly recognized as an important clinical issue. The purpose of this study is to summarize the current definitions and evaluation parameters of AE and then identify and quantify the clinical and immunopathologic characteristics of AE in CRS.

Methods

A systematic review of the literature was performed on PubMed, Scopus, and Cochrane databases from January 1990 through August 2020 to identify studies relating to AE in CRS. Exclusion criteria included non-English and non-human studies, and case reports.

Results

The definitions of AE in CRS among all the studies were based on a description of short-term worsening sinonasal symptoms. Patient-reported sinus infection and exacerbation related medical treatment during the preceding 3 months to 1 year were used to evaluate the frequency of AE in CRS. The average decline in 22-item Sino-Nasal Outcome Test (SNOT-22) score during an exacerbation was 7.83 points relative to baseline. Comorbid asthma, SNOT-22 scores ≥24, allergic rhinitis, eosinophil count ≥150/μL and autoimmune disease were positively associated with an exacerbation-prone CRS phenotype. AE in chronic rhinosinusitis with nasal polyps (CRSwNP) was associated with increased expression of mucus cytokines including myeloperoxidase (percentage increase [PI] = 101%), IL-5 (PI = 125%), and IL-6 (PI = 162%) and could be predicted by the increasing mucus cystatin and periostin.

Conclusion

The definition of AE in CRS is largely driven by patient-reported symptoms and is associated with several risk factors. Quantitative changes in mucus cytokines associated with AE in CRSwNP and may be used to predict events. The development of a consistent definition of AE in CRS is critical to help define disease control and treatment efficacy.

Clinical Research Needs for the Management of Chronic Rhinosinusitis with Nasal Polyps in the New Era of Biologics: A National Institute of Allergy and Infectious Diseases Workshop

The development of biologics targeting various aspects of type 2 inflammation for the treatment of chronic rhinosinusitis with nasal polyps (CRSwNP) will provide clinicians with powerful tools to help treat these patients. However, other therapies are also available, and positioning of biologics in a management algorithm will require comparative trials. In November 2019, the National Institute of Allergy and Infectious Diseases convened a workshop to consider potential future trial designs. Workshop participants represented a wide spectrum of clinical specialties, including otolaryngology, allergy, and pulmonary medicine, as well as expertise in CRSwNP pathophysiology and in trial methodology and statistics. The workshop discussed the current state of knowledge in CRSwNP and considered the advantages and disadvantages of various clinical trial or observational study designs and various clinical outcomes. The output from this workshop, which is presented in this report, will hopefully provide investigators with adequate information and ideas to design future studies and answer critical clinical questions. It will also help clinicians understand the current state of the management of CRSwNP and its gaps and be more able to interpret the new information to come.

Latest advances in chronic rhinosinusitis with nasal polyps endotyping and biomarkers, and their significance for daily practice

The term chronic rhinosinusitis (CRS) comprises of an assortment of diseases that share a common feature: inflammation of the sinonasal mucosa. The phenotype classification of CRS, based on the presence of polyps, has failed to offer a curative treatment for the disease, particularly in refractory cases. Chronic rhinosinusitis with nasal polyps (CRSwNP) remains a challenging entity. Researchers have made efforts trying to characterize subtypes of the disease according to the endotypes, which are delineated by different immunological pathways, using biomarkers. Even if the inflammatory processes controlling CRSwNP are not fully understood, data suggested that the disease associated with a type 2 inflammatory mechanisms can be also linked to the type 1 or type 3 pathomechanism, being highly heterogeneous. Biomarkers for CRSwNP are proposed, such as: eosinophil count, cytokines, metalloproteinases, bitter and sweet taste receptors, and the nasal microbiome. For endotyping to be clinically applicable and simply determined, biomarkers referring to the intrinsic biomolecular mechanism still need to be found. Precision medicine is becoming the new standard of care, but innovative therapies such as biologics may be rather challenging for the clinicians in their daily practice. This new approach to CRSwNP implies patient selection and a simple algorithm for deciding the right treatment, easy to implement and adjust. Our review points out the ongoing new research on the pathophysiology of CRSwNP, biomarkers and treatment opportunities. It allows clinicians to keep abreast of current evidence-based knowledge and to individualize the management of CRSwNP, especially in refractory cases.

Dupilumab: Basic aspects and applications to allergic diseases

Interleukin (IL)-4 and IL-13, signature type 2 cytokines, exert their actions by binding to two types of receptors sharing the IL-4R α chain (IL-4Rα). Since IL-4 and IL-13 play important and redundant roles in the pathogenesis of allergic diseases, blocking both the IL-4 and IL-13 signals would be a powerful and effective strategy for treating allergic diseases. Dupilumab (Dupixent®) is a fully human monoclonal antibody recognizing IL-4Rα and blocking both the IL-4 and IL-13 signals. Dupilumab was first prescribed for atopic dermatitis (AD) patients and has been widely approved for adult patients with moderate to severe AD since 2018. Dupilumab has since been used for asthma, receiving approval for uncontrolled asthma in 2019. A phase 3 study using dupilumab for chronic rhinosinusitis with nasal polyps (CRSwNP) has been just completed, with positive results. Several clinical trials of dupilumab for other diseases in which type 2 inflammation is dominant are now underway. It is hoped that dupilumab will open the door to a new era for treating allergic patients with AD, asthma, and CRSwNP, and for more patients with type 2 inflammations.

Blood eosinophil count and airway epithelial transcriptome relationships in COPD versus asthma

BACKGROUND

Whether the clinical or pathophysiologic significance of the "treatable trait" high blood eosinophil count in COPD is the same as for asthma remains controversial. We sought to determine the relationship between the blood eosinophil count, clinical characteristics and gene expression from bronchial brushings in COPD and asthma.

METHODS

Subjects were recruited into a COPD (emphysema versus airway disease [EvA]) or asthma cohort (Unbiased BIOmarkers in PREDiction of respiratory disease outcomes, U-BIOPRED). We determined gene expression using RNAseq in EvA (n = 283) and Affymetrix microarrays in U-BIOPRED (n = 85). We ran linear regression analysis of the bronchial brushings transcriptional signal versus blood eosinophil counts as well as differential expression using a blood eosinophil > 200 cells/μL as a cut-off. The false discovery rate was controlled at 1% (with continuous values) and 5% (with dichotomized values).

RESULTS

There were no differences in age, gender, lung function, exercise capacity and quantitative computed tomography between eosinophilic versus noneosinophilic COPD cases. Total serum IgE was increased in eosinophilic asthma and COPD. In EvA, there were 12 genes with a statistically significant positive association with the linear blood eosinophil count, whereas in U-BIOPRED, 1197 genes showed significant associations (266 positive and 931 negative). The transcriptome showed little overlap between genes and pathways associated with blood eosinophil counts in asthma versus COPD. Only CST1 was common to eosinophilic asthma and COPD and was replicated in independent cohorts.

CONCLUSION

Despite shared "treatable traits" between asthma and COPD, the molecular mechanisms underlying these clinical entities are predominately different.

Identification of Novel Genes and Biological Pathways That Overlap in Infectious and Nonallergic Diseases of the Upper and Lower Airways Using Network Analyses

Previous genetic studies on susceptibility to otitis media and airway infections have focused on immune pathways acting within the local mucosal epithelium, and outside of allergic rhinitis and asthma, limited studies exist on the overlaps at the gene, pathway or network level between the upper and lower airways. In this report, we compared [1] pathways identified from network analysis using genes derived from published genome-wide family-based and association studies for otitis media, sinusitis, and lung phenotypes, to [2] pathways identified using differentially expressed genes from RNA-sequence data from lower airway, sinus, and middle ear tissues, in particular cholesteatoma tissue compared to middle ear mucosa. For otitis media, a large number of genes (n = 1,806) were identified as differentially expressed between cholesteatoma and middle ear mucosa, which in turn led to the identification of 68 pathways that are enriched in cholesteatoma. Two differentially expressed genes CR1 and SAA1 overlap in middle ear, sinus, and lower airway samples and are potentially novel genes for otitis media susceptibility. In addition, 56 genes were differentially expressed in both tissues from the middle ear and either sinus or lower airways. Pathways that are common in upper and lower airway diseases, whether from published DNA studies or from our RNA-sequencing analyses, include chromatin organization/remodeling, endocytosis, immune system process, protein folding, and viral process. Taken together, our findings from genetic susceptibility and differential tissue expression studies support the hypothesis that the unified airway theory wherein the upper and lower respiratory tracts act as an integrated unit also applies to infectious and nonallergic airway epithelial disease. Our results may be used as reference for identification of genes or pathways that are relevant to upper and lower airways, whether common across sites, or unique to each disease.

Personalized Medicine in Chronic Rhinosinusitis: Phenotypes, Endotypes, and Biomarkers

Chronic rhinosinusitis (CRS) is a heterogeneous disease process with a complex underlying cause. Improved understanding of CRS pathophysiology has facilitated new approaches to management of the patient with CRS that rely on targeting patient-specific characteristics and individual inflammatory pathways. A more personalized approach to care will ultimately incorporate a combination of phenotypic and endotypic classification systems to guide treatment. This review summarizes current evidence with respect to CRS phenotypes and endotypes, as well as the identification of potential biomarkers with potential to guide current and future treatment algorithms.

Eosinophilic chronic rhinosinusitis

Eosinophilic chronic rhinosinusitis (ECRS) is a subgroup of chronic rhinosinusitis with nasal polyps (CRSwNP), which is associated with severe eosinophilic infiltration and intractable. Its symptoms include dysosmia, nasal obstruction, and visous nasal discharge. The cause of ECRS is not clear, although it is thought that Staphylococcus aureus and its enterotoxins are involved in stimulating the Th2 system to promote IgE production and eosinophil infiltration through various pathways. While, the coagulation system is activated and the fibrinolytic system is suppressed, leading to deposition of fibrinous networks in nasal polyps. Therefore, a fibrin-degrading agent could be a new treatment for ECRS. Genetic analysis of nasal polyp cells using next-generation sequencing has identified some of the factors involved in ECRS, including periostin, which can be used as a biomarker of this condition. A protease inhibitor could be a therapeutic agent for ECRS. Regarding the role of eosinophils, many researchers have been interested in the mechanism of ETosis. However, the mechanism leading to development of nasal polyps is unknown. In Japan (as well as in East Asia), the incidence of non-ECRS is decreasing and that of ECRS is increasing, but the reason is also unknown. Thanks to the development of biologics therapy, it is thought that there will be a shift to precision medicine in the future.

Escalation in mucus cystatin 2, pappalysin-A, and periostin levels over time predict need for recurrent surgery in chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is treated using oral/topical steroids and surgery. Despite maximal medical therapy, some patients remain recalcitrant. Mucus cystatin 2, pappalysin-A, and periostin can predict the presence of CRSwNP and correlate with disease severity. This study was designed to determine whether prospective sampling of these mucus proteins could predict medical failure and the need for revision surgery.

METHODS

This investigation was an institutional review board-approved, prospective study of 66 patients with CRSwNP. All patients underwent surgery, administration of topical/oral steroids, and outpatient mucus sampling at 10 time-points over 2 years. Five proteins, including cystatin 2 (CST2), pappalysin-A (PAPP-A), and periostin (PST), were analyzed and correlated with subjective parameters (including scores on the 22-item Sino-Nasal Outcomes Test [SNOT-22]). Variables were then analyzed and compared between those requiring revision surgery within 2 years (n = 5) and those with stable disease (n = 61).

RESULTS

All patients demonstrated a significant decline in CST2, PAPP-A, and periostin after their initial surgery. The recalcitrant group demonstrated escalations in all proteins despite steroids, with levels higher than those of the stable group at 1 year (CST2: 258.1 ± 205.2 pg/mL vs 235.3 ± 275.7 pg/mL, p = 0.86; PAPP-A: 170.3 ± 150.4 pg/mL vs 74.6 ± 106.7 pg/mL, p < 0.05; periostin: 188.8 ± 192.4 ng/mL vs 54.5 ± 47.6 ng/mL, p < 0.001). Escalation in all proteins correlated significantly with worsening SNOT-22 score at each time-point (domain 1: 8.2 ± 1.3 vs 5.5 ± 1.1; p < 0.05).

CONCLUSION

Early recurrences and medical recalcitrance in CRSwNP may be predicted noninvasively through the serial, prospective sampling of mucus CST2, PAPP-A, and periostin levels. These biosignatures may help to predict disease course and guide individualized therapy.

Discriminant analysis followed by unsupervised cluster analysis including exosomal cystatins predict presence of chronic rhinosinusitis, phenotype, and disease severity

BACKGROUND

Cystatins are epithelial protease inhibitors that participate in sinonasal immunity and inflammation. Nasal mucus-derived exosomes (NMDEs) are small vesicles secreted by epithelial cells that carry protein cargo reflective of their host cell. NMDEs have been used as a noninvasive biomarker source to study chronic rhinosinusitis with nasal polyps (CRSwNP) proteomics with superior sensitivity to whole mucus. The purpose of this study was to noninvasively quantify exosomal cystatins in a heterogenous population to determine their utility in predicting phenotype and disease severity.

METHODS

This was an Institutional Review Board-approved study in which NMDEs were purified from 105 patients undergoing sinonasal surgery by ultracentrifugation. Demographic and clinical variables were collected and phenotypes were assigned a priori. Linear discriminant analysis was executed based on normalized Cystatin values as phenotype predictor variables. Unsupervised cluster analysis was performed using Ward's linkage followed by Duda/Hart Je(2)/Je(1) index cluster stopping rules. Analysis of variance (ANOVA), Welch's test, and Fisher's exact tests were used for continuous and categorical variables.

RESULTS

NMDE Cystatin-2 expression segregated by phenotype (mean ± standard error [SEM]): control (23.4 ± 4.2 pg/µg, n = 32); CRS without NP (CRSsNP) (56.6 ± 8.3 pg/µg, n = 33); and CRSwNP (130.5 ± 16.7 pg/µg, n = 40) (p < 0.0001). Seven clusters were identified among patients where the highest NMDE Cystatin-2 levels clustered with asthma, tissue eosinophilia, and aspirin-exacerbated respiratory disease (AERD).

CONCLUSION

Cystatin levels in NMDEs predict CRS phenotype and disease severity. As a "liquid biopsy," noninvasive NMDE collection offers a promising opportunity to study disease pathophysiology, discriminate disease states, and potentially reveal novel therapeutic targets.

Research progress of cystatin SN in cancer

Cystatin SN, belonging to the type 2 cystatin superfamily, is widely expressed and distributed in mammals. Cystatin SN is involved in inflammation, cell cycle, cellular senescence, tumorigenesis, and metastasis. Cystatin SN is also known to participate in signaling pathways like Wnt signaling pathway, GSK3 signaling pathway, AKT signaling pathway, and IL-6 signaling pathway. Cystatin SN was found to be highly expressed in peritumoral normal tissues in esophageal squamous cell carcinoma (ESCC); however, low cystatin SN expression was found in ESCC cancer tissues. Conversely, in other cancer types such as lung cancer, breast cancer, gastric cancer, pancreatic cancer, and colorectal cancer, high cystatin SN expression in cancer tissues but low cystatin SN expression in peritumoral normal tissues was found. Survival analyses showed that high cystatin SN expression benefited ESCC patients but did harm to other types of cancer patients. Univariate and multivariate analyses indicated that cystatin SN possibly acts as a marker for cancer prognosis. Here, we provide a brief introduction about the role of cystatin SN in cancer and discuss the different prognostic effects of cystatin SN on different tumors. Cystatin SN might be a potential marker for cancer prognosis and a target for cancer therapy.

Epithelium-derived cystatin SN enhances eosinophil activation and infiltration through IL-5 in patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

The interaction between epithelial cells and immune cells plays an important role in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP); however, the mechanism or mechanisms underlying T_H-biased inflammation in this process are largely unknown. Profiling protein expression in patients with CRSwNP by using shotgun proteomics suggested that cystatin SN (CST1), a type 2 cysteine protease inhibitor, might play a role because this was expressed with the greatest difference in patients with eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) and those with noneosinophilic chronic rhinosinusitis with nasal polyps (nonECRSwNP).

OBJECTIVES

We sought to investigate the expression and role of CST1 in modulating eosinophilic inflammation in patients with CRSwNP.

METHODS

Sinonasal tissues were collected from 192 patients with ECRSwNP, 52 patients with nonECRSwNP, and 40 control subjects. CST1 mRNA expression, localization, and concentration in the tissues were measured by using real-time PCR, in situ hybridization, immunohistochemistry, and an ELISA. Recombinant CST1 was used to further explore the function of the molecule in dispersed nasal polyp cells and eosinophils extracted from polyp tissues and peripheral blood.

RESULTS

CST1 was mainly expressed by epithelial cells and significantly increased in patients with ECRSwNP but decreased in patients with nonECRSwNP compared with that in control subjects. CST1 expression was further increased in patients with ECRSwNP and comorbid asthma and correlated with eosinophil percentages in tissue samples. CST1 was induced by IL-4 and IL-13 in tissue from both patients with ECRSwNP and those with nonECRSwNP and repressed by IL-17A in patients with nonECRSwNP in the presence of neutrophils. CST1 enhanced eosinophil activation and recruitment through induction of IL-5.

CONCLUSION

Epithelium-derived CST1 modulates eosinophil activation and recruitment, expression of which could be regulated by T_H2 and T_H17 cytokines.

Induction of peripheral lymph node addressin in human nasal mucosa with eosinophilic chronic rhinosinusitis

Eosinophilic chronic rhinosinusitis (ECRS) is characterised by formation of nasal polyps with prominent eosinophilic infiltration; however, how eosinophils are recruited in this pathological setting remains unclear. In the present study, we carried out quantitative immunohistochemical analysis of nasal polyps associated with ECRS (n=30) and non-ECRS (n=30) to evaluate expression of an L-selectin ligand peripheral lymph node addressin (PNAd) on vascular endothelial cells. We found that PNAd was induced primarily on the luminal surface of venular vessels present in nasal mucosa in both ECRS and non-ECRS, while the number of PNAd-expressing vessels in ECRS significantly exceeded that seen in non-ECRS. Moreover, the number of eosinophils attached to the luminal surface of PNAd-expressing vessels in ECRS was significantly greater than that in non-ECRS, while the number of neutrophils and lymphocytes attached did not differ significantly between conditions. Furthermore, eosinophils, which express cell surface L-selectin, adhered to PNAd-expressing Chinese hamster ovary (CHO) cells in a calcium-dependent manner, and that adhesion was significantly inhibited by pretreatment of eosinophils with DREG-56, an anti-human L-selectin monoclonal antibody. These findings combined suggest that interaction between L-selectin and PNAd plays at least a partial role in eosinophil recruitment in human nasal mucosa with ECRS.

Translating transcription: proteomics in chronic rhinosinusitis with nasal polyps reveals significant discordance with messenger RNA expression

BACKGROUND

Much of the literature examining chronic rhinosinusitis with nasal polyps (CRSwNP) immunopathology has been predicated on messenger RNA (mRNA) analysis with the assumption that transcriptional changes would reflect end-effector protein expression. The purpose of this study was to test this hypothesis using matched transcriptomic and proteomic data sets.

METHODS

Matched tissue proteomic and transcriptomic arrays were quantified in CRSwNP polyp tissue and control inferior turbinate tissue (n = 10/group). Mucus samples were additionally collected in 6 subjects from each group. Proteins were grouped into functional categories by bioinformatics and differential expression analyses. Log-log regression and Pearson correlations were performed to determine the level of agreement between data sets.

RESULTS

Of the 1310 proteins examined, 393 were significantly differentially expressed in CRSwNP. On regression analysis, differences in protein expression were poorly predicted by differences in mRNA expression (R² = 0.020, p < 0.05). Several genes canonically thought to be overexpressed in CRSwNP, including IL-5, IL-13, TSLP, CCL13, and CCL26, showed substantial increases in mRNA transcription, but had minimally or unchanged protein expression. Others, including IgE, periostin, CCL18, and CST1/2, were increased at both the transcriptomic and proteomic levels. Among differentially regulated proteins, tissue and mucus protein levels showed weak correlation (r = 0.26, p < 0.0001).

CONCLUSION

Proteomic analysis in CRSwNP has revealed novel disease-associated proteins and pathways, yet correlates poorly with transcriptomic data. The increasing availability of proteomic arrays opens the door to new potential explanatory mechanisms in CRSwNP and suggests that mRNA based studies should be validated with protein analysis.

Eotaxin-3 as a Plasma Biomarker for Mucosal Eosinophil Infiltration in Chronic Rhinosinusitis

Objective: Chronic rhinosinusitis with nasal polyps exhibits marked eosinophilic infiltration and its mucosal eosinophilia is associated with more severe symptoms. The Japanese epidemiological survey of refractory eosinophilic chronic rhinosinusitis found that patients with nasal polyps required multiple surgeries when there were higher infiltrating eosinophils in the mucosa. In order to identify plasma biomarkers for local eosinophil infiltration in rhinosinusitis for surgery, we examined the levels of molecules in the plasma of patients and compared the number of infiltrating eosinophils in the nasal mucosa.

Materials and Methods: Mucosal tissues from 97 patients with chronic rhinosinusitis (CRS) were obtained from the nasal polyps during surgery. Tissues were immediately fixed and sections were stained with hematoxylin-eosin. The number of eosinophils in the mucosa was counted at HPF (x 400). Blood samples were obtained and the plasma was stored at −80°C. We measured the plasma cytokine and chemokine levels using multiple assay systems according to the manufacturers' protocols. The tissues were divided into high- and low-eosinophil mucosal infiltration group for recurrence after endoscopic sinus surgery (ESS). We also observed chemokine secretion from nasal fibroblasts.

Results: The plasma level of eotaxin-3/ CC chemokine ligand 26 (CCL26) was significantly higher in the high-eosinophil mucosal infiltration group (p < 0.005). The number of infiltrating eosinophils in the mucosa was significantly higher in the group with the higher eotaxin-3 level (p < 0.001), but there was no significant difference in the blood eosinophil numbers among two groups. A significant positive correlation was found between the mucosal eosinophil count and the plasma levels of eotaxin-3 (p < 0.005). The levels of interleukin 33 (IL-33) (p < 0.001) and thymic stromal-derived lymphopoietin (TSLP) (p < 0.005) were significantly higher in the high-level eotaxin-3 group. IL-13 strongly induced the secretion of eotaxin-3 from human nasal fibroblasts (p < 0.05).

Conclusion: This is the first report suggesting eotaxin-3 as a plasma biomarker for mucosal eosinophil infiltration. Furthermore, the level of eotaxin-3 was found to be closely related to IL-33 and TSLP levels which indicate respiratory diseases.