Reduced expression of antimicrobial PLUNC proteins in nasal polyp tissues of patients with chronic rhinosinusitis

The expression and significance of nasal mucosal glandular hyperplasia and eosinophil infiltration in chronic rhinosinusitis

BACKGROUND

The pathophysiological mechanisms underlying nasal mucosal glandular changes in chronic rhinosinusitis (CRS) remains poorly understood.

OBJECTIVES

This study aimed to examine nasal mucosal glandular density and eosinophil (Eos) infiltration in CRS patients and their role in disease pathogenesis.

MATERIALS AND METHODS

HE staining was used to assess glandular density and Eos infiltration in nasal mucosal lesion tissues from 86 CRS patients during FESS (16 CRS without nasal polyps (CRSsNP), 55 non-eosinophilic CRS with nasal polyps (nECRSwNP), and 15 eosinophilic CRSwNP (ECRSwNP)). Immunohistochemical analysis was conducted to evaluate eosinophil cationic protein (ECP), lysozyme, and immunoglobulin A (IgA) expression within these tissues. The Kruskal-Wallis test was used to reveal the statistical difference in therapeutic efficacy among the groups.

RESULTS

The CRSsNP group showed nasal mucosal glandular density of '+++/++' with minimal Eos infiltration, and 94% achieved control. The nECRSwNP group exhibited atypical glandular hyperplasia and Eos infiltration, with 22% achieving complete control, 51% partial control, and 27% no control. The ECRSwNP group had significant Eos infiltration '++/+++' and reduced glands, with 93% showing uncontrolled conditions.

CONCLUSIONS AND SIGNIFICANCE

The findings suggest that extensive Eos infiltration and ECP secretion contribute to glandular and epithelial damage, reducing lysozyme and IgA production. These changes may promote chronic inflammation and increase the likelihood of nasal polyp recurrence.

Endotyping in Chronic Rhinosinusitis-An EAACI Task Force Report

Chronic rhinosinusitis (CRS) is a clinical syndrome defined by typical sinonasal symptoms persisting for at least 12 weeks. CRS is divided into two distinct phenotypes, CRS with nasal polyps (CRSwNP) and without (CRSsNP). The aim of the review is to provide an update on the current knowledge in CRS endotypes. The prevailing hypothesis regarding the pathogenesis of CRS suggests that dysfunctional interactions between the host and environmental stressors at the mucosal surface drive the diverse inflammatory mechanisms. Genetic and epigenetic variations in the mucosal immune system are believed to play a significant role in the pathomechanisms of CRS. Various environmental agents (such as microbes and irritants) have been implicated in CRS. In a healthy state, the sinonasal mucosa acts as a barrier, modulating environmental stimulation and mounting appropriate immune responses against pathogens with minimal tissue damage. Different endotypes may exist based on the specific mechanistic pathways driving the chronic tissue inflammation of CRS. There is a need to understand endotypes in order to better predict, diagnose, and treat CRS. This literature review provides an update on the role of the endotypes in CRS and the limitations of endotyping CRS in clinical practice. Understanding of the pathogenesis and optimal management of CRS has progressed significantly in the last decades; however, there still are several unmet needs in endotype research.

Remodeling of Paranasal Sinuses Mucosa Functions in Response to Biofilm-Induced Inflammation

Rhinosinusitis (RS) is an acute (ARS) or chronic (CRS) inflammatory disease of the nasal and paranasal sinus mucosa. CRS is a heterogeneous condition characterized by distinct inflammatory patterns (endotypes) and phenotypes associated with the presence (CRSwNP) or absence (CRSsNP) of nasal polyps. Mucosal barrier and mucociliary clearance dysfunction, inflammatory cell infiltration, mucus hypersecretion, and tissue remodeling are the hallmarks of CRS. However, the underlying factors, their priority, and the mechanisms of inflammatory responses remain unclear. Several hypotheses have been proposed that link CRS etiology and pathogenesis with host (eg, "immune barrier") and exogenous factors (eg, bacterial/fungal pathogens, dysbiotic microbiota/biofilms, or staphylococcal superantigens). The abnormal interplay between these factors is likely central to the pathophysiology of CRS by triggering compensatory immune responses. Here, we discuss the role of the sinonasal microbiota in CRS and its biofilms in the context of mucosal zinc (Zn) deficiency, serving as a possible unifying link between five host and "bacterial" hypotheses of CRS that lead to sinus mucosa remodeling. To date, no clear correlation between sinonasal microbiota and CRS has been established. However, the predominance of Corynebacteria and Staphylococci and their interspecies relationships likely play a vital role in the formation of the CRS-associated microbiota. Zn-mediated "nutritional immunity", exerted via calprotectin, alongside the dysregulation of Zn-dependent cellular processes, could be a crucial microbiota-shaping factor in CRS. Similar to cystic fibrosis (CF), the role of SPLUNC1-mediated regulation of mucus volume and pH in CRS has been considered. We complement the biofilms' "mechanistic" and "mucin" hypotheses behind CRS pathogenesis with the "structural" one - associated with bacterial "corncob" structures. Finally, microbiota restoration approaches for CRS prevention and treatment are reviewed, including pre- and probiotics, as well as Nasal Microbiota Transplantation (NMT).

Clinical Characteristics of Eosinophilic Chronic Rhinosinusitis with Nasal Polyps in Adolescents

Introduction

Eosinophilic chronic rhinosinusitis with nasal polyps (CRSwNP) is frequently associated with greater inflammation, poorer prognosis, and a high recurrence rate after sinus surgery.

Objective

This study evaluated the clinical and imaging characteristics of eosinophilic CRSwNP in patients aged 12-17.

Methods

We retrospectively enrolled 139 patients aged 12-17 with bilateral CRSwNP. Clinical characteristics, computed tomography (CT) features, tissue eosinophil counts, and eosinophil activity were evaluated.

Results

Twenty-three (16.5%) patients had recurrent nasal polyps that required revision surgery. Patients requiring revision surgery had higher tissue eosinophil infiltration in the sinus mucosa than those not requiring revision surgery. The optimal cut-off value to distinguish the need for revision surgery was a tissue eosinophil count > 21.5/high-power field determined by the receiver operating characteristic curve. The Lund-Mackay and olfactory cleft opacification scores on CT images were significant predictors of tissue eosinophil count in the univariate analysis, and only olfactory opacification scores remained statistically significant in the multivariate analysis.

Conclusion

This study revealed that the CT feature of the olfactory cleft opacification score could be a significant characteristic of eosinophilic CRSwNP in adolescents.

Unraveling the Role of Epithelial Cells in the Development of Chronic Rhinosinusitis

The pathophysiology of CRS is multifactorial and complex yet needs to be completed. Recent evidence emphasizes the crucial part played by epithelial cells in the development of CRS. The epithelial cells act as physical barriers and play crucial roles in host defense, including initiating and shaping innate and adaptive immune responses. This review aims to present a comprehensive understanding of the significance of nasal epithelial cells in CRS. New research suggests that epithelial dysfunction plays a role in developing CRS through multiple mechanisms. This refers to issues with a weakened barrier function, disrupted mucociliary clearance, and irregular immune responses. When the epithelial barrier is compromised, it can lead to the passage of pathogens and allergens, triggering inflammation in the body. Furthermore, impaired mucociliary clearance can accumulate pathogens and secretions of inflammatory mediators, promoting chronic inflammation. Epithelial cells can release cytokines and chemokines, which attract and activate immune cells. This can result in an imbalanced immune response that continues to cause inflammation. The interaction between nasal epithelial cells and various immune cells leads to the production of cytokines and chemokines, which can either increase or decrease inflammation. By comprehending the role of epithelial cells in CRS, we can enhance our understanding of the disease's pathogenesis and explore new therapeutics.

Targeting Epithelium Dysfunction and Impaired Nasal Biofilms to Treat Immunological, Functional, and Structural Abnormalities of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) with (CRSwNP) or without (CRSsNP) nasal polyps is a prevalent and heterogeneous disorder existing as a spectrum of clinical conditions with complex underlying pathomechanisms. CRS comprises a broad syndrome characterized by multiple immunological features involving complex interactions between the genes, the microbiome, host- and microbiota-derived exosomes, the epithelial barrier, and environmental and micromilieu exposures. The main pathophysiological feature is an epithelial barrier disruption, accompanied by microbiome alterations and unpredictable and multifactorial immunologic overreactions. Extrinsic pathogens and irritants interact with multiple epithelial receptors, which show distinct expression patterns, activate numerous signaling pathways, and lead to diverse antipathogen responses. CRSsNP is mainly characterized by fibrosis and mild inflammation and is often associated with Th1 or Th17 immunological profiles. CRSwNP appears to be associated with moderate or severe type 2 (T2) or Th2 eosinophilic inflammation. The diagnosis is based on clinical, endoscopic, and imaging findings. Possible CRS biomarkers from the peripheral blood, nasal secretions, tissue biopsies, and nasally exhaled air are studied to subgroup different CRS endotypes. The primary goal of CRS management is to maintain clinical control by nasal douching with isotonic or hypertonic saline solutions, administration of nasal and systemic steroids, antibiotics, biologic agents, or, in persistent and more severe cases, appropriate surgical procedures.

Phenotype overlap in the natural history of asthma

The heterogeneity of asthma makes it challenging to unravel the pathophysiologic mechanisms of the disease. Despite the wealth of research identifying diverse phenotypes, many gaps still remain in our knowledge of the disease's complexity. A crucial aspect is the impact of airborne factors over a lifetime, which often results in a complex overlap of phenotypes associated with type 2 (T2), non-T2 and mixed inflammation. Evidence now shows overlaps between the phenotypes associated with T2, non-T2 and mixed T2/non-T2 inflammation. These interconnections could be induced by different determinants such as recurrent infections, environmental factors, T-helper plasticity and comorbidities, collectively resulting in a complex network of distinct pathways generally considered as mutually exclusive. In this scenario, we need to abandon the concept of asthma as a disease characterised by distinct traits grouped into static segregated categories. It is now evident that there are multiple interplays between the various physiologic, cellular and molecular features of asthma, and the overlap of phenotypes cannot be ignored.

The Nasal Innate Immune Proteome After Saline Irrigation: A Pilot Study in Healthy Individuals

BACKGROUND

Previous research has shown diminished nasal immune function following nasal saline irrigation (NSI), returning to baseline at 6 hours. The aim of this study was to examine the immune nasal proteome before and after 14 days of nasal irrigation.

METHODS

Seventeen healthy volunteers received either isotonic (IsoSal) or low salt (LowNa) NSI. Nasal secretions were collected before and 30 min after NSI at baseline and again after 14 days. Specimens were analyzed using mass spectrometry to detect proteins of relevance to nasal immune function.

RESULTS

One thousand eight hundred and sixty-five proteins were identified with significant changes in 71 proteins, of which 23 were identified as part of the innate immune system. Baseline analysis demonstrated an increase of 9 innate proteins after NSI, most after IsoSal. After 14 days, a greater increase in innate peptides was present, with most now in the LowNa group. When NSI solutions were compared, a significant increase in 4 innate proteins, including a 211% in lysozyme, was detected in the LowNa group.

CONCLUSION

LowNa NSI demonstrates evidence of improving the innate immune secretions, especially lysozyme, in healthy volunteers.

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.

Studies on activation and regulation of the coagulation cascade in chronic rhinosinusitis with nasal polyps

BACKGROUND

Increased activation of the coagulation cascade and diminished fibrinolysis combine to promote fibrin deposition and polyp formation in chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP). More information is needed concerning mechanisms of coagulation in CRSwNP.

OBJECTIVE

We investigated the mechanisms as well as the initiation and regulation of coagulation cascade activation in CRS.

METHODS

Samples were collected from 135 subjects with CRSwNP, 80 subjects with chronic CRS without nasal polyps (NP), and 65 control subjects. The levels of activated factor X (FXa), prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex, tissue factor (TF), and TF pathway inhibitor (TFPI) were monitored in CRS by real-time PCR, ELISA, immunohistochemistry, or immunofluorescence. Heteromeric complexes of TF with activated factor VII (FVII) and TF with activated FVII and FXa were assessed by coimmunoprecipitation and Western blotting.

RESULTS

Increased levels of FXa, F1+2, and thrombin-antithrombin complex were detected in NP tissue compared to uncinate tissue from CRS and control subjects. Although free TF protein levels were not increased in NP, immunoprecipitation of TF in NP tissue revealed increased complexes of TF with FVII. Local expression of FVII was detected in sinonasal mucosa, and the ratio of TFPI to FXa was lower in NP tissue.

CONCLUSION

The coagulation cascade is associated with NP compared to control and uncinate tissue from CRS patients, and TF and FVII are produced locally in sinonasal mucosa in patients. TF and FVII can activate the extrinsic coagulation pathway, suggesting that this pathway may activate fibrin deposition in CRSwNP. Reduced formation of the complex of FXa and TFPI in NP may reduce natural suppression of the extrinsic coagulation pathway in CRSwNP.

Construction and analysis of a ceRNA network and patterns of immune infiltration in chronic rhinosinusitis with nasal polyps: based on data mining and experimental verification

Recent studies have revealed the significant role of the competing endogenous RNA (ceRNA) network in human diseases. However, systematic analysis of the ceRNA mechanism in chronic rhinosinusitis with nasal polyps (CRSwNP) is limited. In this study, we constructed a competitive endogenous RNA (ceRNA) network and identified a potential regulatory axis in CRSwNP based on bioinformatics analysis and experimental verification. We obtained lncRNA, miRNA, and mRNA expression profiles from the Gene Expression Omnibus. After analysis of CRSwNP patients and the control groups, we identified 565 DE-lncRNAs, 23 DE-miRNAs, and 1799 DE-mRNAs by the DESeq2 R package or limma R package. Enrichment analysis of 1799 DE-mRNAs showed that CRSwNP was associated with inflammation and immunity. Moreover, we identified 21 lncRNAs, 8 miRNAs and 8 mRNAs to construct the lncRNA-miRNA-mRNA ceRNA network. A potential MIAT/miR-125a/IRF4 axis was determined according to the degree and positive correlation between a lncRNA and its competitive endogenous mRNAs. The GSEA results suggested that IRF4 may be involved in immune cell infiltration. The validation of another dataset confirmed that MIAT and IRF4 were differentially expressed between the CRSwNP and control groups. The area under the ROC curve (AUC) of MIAT and IRF4 was 0.944. The CIBERSORT analysis revealed that eosinophils and M2 macrophages may be involved in the CRSwNP process. MIAT was correlated with dendritic cells and M2 macrophages, and IRF4 was correlated with dendritic cells. Finally, to validate the key genes, we performed in-silico validation using another dataset and experimental validation using immunohistochemistry, immunofluorescence, and Western blot. In summary, the constructed novel MIAT/miR-125a/IRF4 axis may play a critical role in the development and progression of CRSwNP. We believe that the ceRNA network and immune cell infiltration could offer further insight into novel molecular therapeutic targets for CRSwNP.

Age-Related Increase of Collagen/Fibrin Deposition and High PAI-1 Production in Human Nasal Polyps

Objective: Our previous studies showed an age-related increased prevalence of nasal polyps (NP) and reduced production of S100A8/9 in elderly patients with chronic rhinosinusitis with NP (CRSwNP). In this study, we investigated an unbiased age-related gene expression profile in CRSwNP subjects and healthy controls, and further identified the differences in their tissue remodeling. Methods: Microarrays using NP and uncinate tissues from health controls (elderly, age ≥65 vs. non-elderly, age 18-49) were performed, and differentially regulated genes were analyzed. Quantitative real-time PCR (qPCR), Immunostaining, Periodic acid-Schiff (PAS), trichrome staining, Western blot, and ELISA were performed for further investigation. Results: Microarrays identified differentially expressed genes according to disease and age; 278 in NP vs. controls, 75 in non-elderly NP vs. non-elderly controls, and 32 in elderly NP vs. elderly controls. qPCR confirmed that the PLAT gene was downregulated and the SERPINB2 gene upregulated in NP vs. controls. The serous glandular cell-derived antimicrobial protein/peptide-related genes such as BPIFB3, BPIFB2, LPO, and MUC7 were remarkably reduced in NP, regardless of age. SERPINE1 gene (plasminogen activator inhibitor-1, PAI-1) expression was significantly increased in elderly NP versus elderly controls. IHC and western blot confirmed significantly decreased production of MUC7 and LPO in NP versus controls. There was a trend of age-related reduction of submucosal gland cells in normal controls. Trichrome and immunofluorescence staining demonstrated an age-related increase of collagen and fibrin deposition in NP, consistent with increased PAI-1 production. Conclusion: This study demonstrated age-related differential glandular remodeling patterns and fibrosis in NP and normal controls. PAI-1 expression was significantly increased in elderly NP versus elderly controls, suggesting PAI-1 as a potential treatment target in elderly NP.

Expression of Oxidative Stress and Inflammation-Related Genes in Nasal Mucosa and Nasal Polyps from Patients with Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a prevalent, multifaceted inflammatory condition affecting the nasal cavity and the paranasal sinuses, frequently accompanied by formation of nasal polyps (CRSwNP). This apparently uniform clinical entity is preceded by heterogeneous changes in cellular and molecular patterns, suggesting the presence of multiple CRS endotypes and a diverse etiology. Alterations of the upper airway innate defense mechanisms, including antimicrobial and antioxidant capacity, have been implicated in CRSwNP etiology. The aim of this study was to investigate mRNA expression patterns of antioxidative enzymes, including superoxide dismutase (SOD) and peroxiredoxin-2 (PRDX2), and innate immune system defense players, namely the bactericidal/permeability-increasing fold-containing family A, member 1 (BPIFA1) and PACAP family members, particularly adenylate-cyclase-activating polypeptide receptor 1 (ADCYAP1) in nasal mucosa and nasal polyps from CRSwNP patients. Additional stratification based on age, sex, allergic comorbidity, and disease severity was applied. The results showed that ADCYAP1, BPIFA1, and PRDX2 transcripts are differentially expressed in nasal mucosa and scale with radiologically assessed disease severity in CRSwNP patients. Sinonasal transcriptome is not associated with age, sex, and smoking in CRSwNP. Surgical and postoperative corticosteroid (CS) therapy improves endoscopic appearance of the mucosa, but variably reverses target gene expression patterns in the nasal cavity of CRSwNP patients. Transcriptional cross-correlations analysis revealed an increased level of connectedness among differentially expressed genes under inflammatory conditions and restoration of basic network following CS treatment. Although results of the present study imply a possible engagement of ADCYAP1 and BPIFA1 as biomarkers for CRSwNP, a more profound study taking into account disease severity and CRSwNP endotypes prior to the treatment would provide additional information on their sensitivity.

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.

Transcriptomic and Lipidomic Profiles in Nasal Polyps of Glucocorticoid Responders and Non-Responders: Before and After Treatment

Background: The pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) and mechanisms underlying different responses to systemic glucocorticoids (GC) remain unclear. The major aim of this study was to explore the transcriptomic and oxidative lipidomic signatures and the effects of GC in patients with different clinical responses.

Methods: Nasal polyp biopsies were obtained before and after 14-day oral GC treatment from 16 patients with CRSwNP, and normal nasal mucosa specimens were collected from 12 control subjects. RNA sequencing and oxidative lipidomics were performed, and differential gene expression analysis was conducted in the Responder and Non-responder groups at baseline and after treatment.

Results: In the Responder group, GC significantly improved clinical symptoms and reduced tissue eosinophil infiltration. Meanwhile, GC led to a pronounced transcriptomic reversion with robust suppression of inflammatory responses and abnormal metabolism of extracellular matrix, as well as restoration of cilia function. However, non-responders were mainly characterized by epithelial hyperplasia and keratinization, with much less transcriptomic improvement after GC treatment. Higher expression of type 2 inflammatory molecules (CCL13, IGHE, CCL18, CCL23, CCR3, and CLC) with lower levels of LACRT, PPDPFL, DES, C6, MUC5B, and SCGB3A1 were related to a stronger clinical response to GC. Besides decreased prostaglandins and increased leukotrienes, increased dysregulation in other oxylipid mediators derived from polyunsaturated fatty acids was determined in nasal polyps, which was ameliorated by GC treatment.

Conclusion: Systemic GC exert anti-inflammatory effects, improve tissue remodeling, restore cilia function, and ameliorate dysregulation of oxylipid mediator pathway in CRSwNP. GC-responders exhibited different transcriptomic signatures from non-responders.

Barrier Impairment and Type 2 Inflammation in Allergic Diseases: The Pediatric Perspective

Allergic diseases represent a global burden. Although the patho-physiological mechanisms are still poorly understood, epithelial barrier dysfunction and Th2 inflammatory response play a pivotal role. Barrier dysfunction, characterized by a loss of differentiation, reduced junctional integrity, and altered innate defence, underpins the pathogenesis of allergic diseases. Epithelial barrier impairment may be a potential therapeutic target for new treatment strategies Up now, monoclonal antibodies and new molecules targeting specific pathways of the immune response have been developed, and others are under investigation, both for adult and paediatric populations, which are affected by atopic dermatitis (AD), asthma, allergic rhinitis (AR), chronic rhinosinusitis with nasal polyps (CRSwNP), or eosinophilic esophagitis (EoE). In children affected by severe asthma biologics targeting IgE, IL-5 and against IL-4 and IL-13 receptors are already available, and they have also been applied in CRSwNP. In severe AD Dupilumab, a biologic which inhibits both IL-4 and IL-13, the most important cytokines involved in inflammation response, has been approved for treatment of patients over 12 years. While a biological approach has already shown great efficacy on the treatment of severe atopic conditions, early intervention to restore epithelial barrier integrity, and function may prevent the inflammatory response and the development of the atopic march.

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.

Interaction Between Serum/Glucocorticoid-Regulated Kinase 1 and Interleukin-6 in Chronic Rhinosinusitis

PURPOSE

Serum/glucocorticoid-regulated kinase 1 (SGK1) has recently emerged as a critical regulator of inflammatory diseases. In this study, we examined SGK1 expression and its possible pathogenic roles in chronic rhinosinusitis (CRS).

METHODS

Immunohistochemistry, western blotting, Bio-Plex assay, enzyme-linked immunosorbent assays, and quantitative real-time polymerase chain reaction were performed to assess protein and gene expression levels. The mRNA expression levels of SGK1 and interleukin-6 (IL-6) were extracted from a CRS database to perform correlation analysis. Stable cell lines with SGK1 overexpression (16HBE) and knockdown (A549) were constructed to investigate the interaction between SGK1 and IL-6 in vitro.

RESULTS

SGK1 exhibited strong cytoplasmic and nuclear staining in the epithelial layers and the lamina propria of nasal polyps (NPs) and in the mucosal tissues of CRS without nasal polyps (CRSsNP). The mRNA and protein expression levels of SGK1 and IL-6 were significantly increased in NPs and CRSsNP tissues, compared to control tissues. SGK1 phosphorylation was significantly greater in NPs than in CRSsNP tissues (P < 0.01). The mRNA levels of SGK1 and IL-6 were significantly correlated (P < 0.001, r = 0.649). Exposure to IL-6 significantly increased SGK1 expression in cultured dispersed NP cells, 16HBE cells, and A549 cells. IL-6 expression was significantly down-regulated in SGK1-overexpressing 16HBE cells (P < 0.01) and significantly up-regulated in SGK1-knockdown A549 cells (P < 0.05). Administration of GSK650394, a SGK1 inhibitor, significantly increased IL-6 self-induced mRNA expression in cultured dispersed NP cells and 16HBE cells.

CONCLUSIONS

The interaction between SGK1 and IL-6 may play an anti-inflammatory role in IL-6-induced inflammation in the pathogenesis of CRS.

The Multifunctional Roles of Short Palate, Lung, and Nasal Epithelium Clone 1 in Regulating Airway Surface Liquid and Participating in Airway Host Defense

Short palate, lung, and nasal epithelium clone 1 (SPLUNC1) is a kind of secretory protein, and gets expressed abundantly in normal respiratory epithelium of humans. As a natural immune molecule, SPLUNC1 is proved to be involved in inflammatory response and airway host defense. This review focuses on summarizing and discussing the role of SPLUNC1 in regulating airway surface liquid (ASL) and participating in airway host defense. PubMed and MEDLINE were used for searching and identifying the data in this review. The domain of bactericidal/permeability-increasing protein in SPLUNC1 and the α-helix, α4, are essential for SPLUNC1 to exert biological activities. As a natural innate immune molecule, SPLUNC1 plays a significant role in inflammatory response and airway host defense. Its special expression patterns are not only observed in physiological conditions, but also in some respiratory diseases. The mechanisms of SPLUNC1 in airway host defense include modulating ASL volume, acting as a surfactant protein, inhibiting biofilm formation, as well as regulating ASL compositions, such as LL-37, mucins, Neutrophil elastase, and inflammatory cytokines. Besides, potential correlations are found among these different mechanisms, especially among different ASL compositions, which should be further explored in more systematical frameworks. In this review, we summarize the structural characteristics and expression patterns of SPLUNC1 briefly, and mainly discuss the mechanisms of SPLUNC1 exerted in host defense, aiming to provide a theoretical basis and a novel target for future studies and clinical treatments.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

[Antimicrobial peptides and proteins in chronic rhinosinusitis]

The pathogenesis of chronic rhinosinusitis（CRS） is closely related to the interactions between the environmental stimuli and the innate defense system. A vast of defensive molecules, such as antimicrobial peptides and proteins（AMPs） could be secreted by the airway epithelial cells and submucosal glands. As an essential component of innate immune system, AMPs are associated with multiple airway disease, such as CRS, chronic obstructive pulmonary disease, bronchiectasis, allergic asthma and so on. AMPs are expressed vastly in nasal mucosa and could exert fundamental antibacterial and inflamatory regulative functions. However, the pathophysiological mechanism of AMPs in CRS is still unclear. What's more, the heterogeneity among studies is relatively high. Thus, the paper was aimed to review the potential function and inflammatory regulation of AMPs in CRS. More rigorous studies with larger samples are needed in the future, to shed light on its possible pathogeneisis mechanisms.

[Management strategies for chronic rhinosinusitis with nasal polyps in adults]

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the categories of chronic rhinosinusitis and is defined by the presence of bilateral polyps. It is frequently associated with other conditions (asthma, atopy, aspirin intolerance), which worsen its prognosis.

STATE OF ART

The pathophysiology of CRSwNP is still poorly understood. The genesis of polyps is thought to be based on an initial epithelial lesion caused by environmental factors in the context of self-maintained chronic local inflammation. Multiple local and general factors can be involved in this inflammation, which is mainly of Th2 type in Europe. Abnormalities of the epithelial barrier and the immune system (eosinophilia, cytokines, T and B lymphocytes), genetic factors and pathogens, including Staphylococcus aureus, have been incriminated. The treatment of CRSwNP is mainly based on the application of local corticosteroids. Surgery remains an important part of patient management where CRSwNP becomes resistant to topical therapy. The management of CRSwNP may be at a turning point thanks to the arrival of biological therapies (anti-IgE, anti-IL-5, anti-IL-4/IL-13) the initial results of which are promising.

PERSPECTIVES/CONCLUSIONS

With the new concept of endotypes, current avenues of research are moving towards a better understanding of the inflammatory mechanisms of CRSwNP. Immunotherapy appears to be a promising future for the treatment of CRSwNP.

Reduced Expression of Antimicrobial Protein Secretory Leukoprotease Inhibitor and Clusterin in Chronic Rhinosinusitis with Nasal Polyps

Introduction

Antimicrobial peptides and proteins (AMPs) constitute the first line of defense against pathogenic microorganisms in the airway. The association between AMPs and chronic rhinosinusitis with nasal polyps (CRSwNP) requires further investigations. This study is aimed at investigating the expression and regulation of major dysregulated AMPs in the nasal mucosa of CRSwNP.

Methods

The expression of AMPs was analyzed in nasal tissue from patients with eosinophilic (E) CRSwNP and nonECRSwNP and healthy subjects using RNA sequencing. The 10 most abundant AMPs expressed differentially in CRSwNP patients were verified by real-time PCR, and of these, the expression and regulation of secretory leukoprotease inhibitor (SLPI) and clusterin (CLU) were investigated further.

Results

The 10 most abundant AMPs expressed differentially in CRSwNP compared to healthy control, regardless of subtypes, included BPIFA1, BPIFB1, BPIFB2, CLU, LTF, LYZ, and SLPI, which were downregulated, and S100A8, S100A9, and HIST1H2BC, which were upregulated. ELISA and immunofluorescence confirmed the decreased expression of SLPI and CLU levels in CRSwNP. SLPI is expressed in both nasal epithelial cells and glandular cells, whereas CLU is mainly expressed in glandular cells. AB/PAS staining further demonstrated that both SLPI and CLU were mainly produced by mucous cells in submucosal glands. Furthermore, the numbers of submucosal glands were significantly decreased in nasal polyp tissue of CRSwNP compared to nasal tissue of controls. SLPI was downregulated by TGF-β1 and IL-4 in cultured nasal tissues in vitro, while CLU expression was inhibited by TGF-β1. Glucocorticoid treatment for 2 weeks significantly increased the expression of all downregulated AMPs, but not LYZ. Additionally, budesonide significantly increased the expression of SLPI and CLU in cultured nasal tissues.

Conclusion

The expression of major antimicrobial proteins is significantly decreased in nasal tissue of CRSwNP. The expression of SLPI and CLU is correlated with the numbers of submucosal glands and regulated by inflammatory cytokines and glucocorticoids.

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.

Adult chronic rhinosinusitis

Chronic rhinosinusitis (CRS) occurs in >10% of the adult population in Europe and the USA and can be differentiated into CRS without nasal polyps and CRS with nasal polyps (CRSwNP). Both phenotypes are characterized by a high disease burden and an overlapping spectrum of symptoms, with facial pain and loss of smell being the most differentiating. Great progress has been made in the understanding of CRS pathophysiology: from the epithelium and epithelial-mesenchymal transition to innate and adaptive immunity pathways and, finally, on the role of eosinophils and Staphylococcus aureus in the persistence of disease. Although clinical manifestations and diagnostic tools (including nasal endoscopy and imaging) have undergone major changes over the past few years, management (including pharmacotherapy, surgery and biologics) has experienced enormous progress based on the growing knowledge of key mediators in severe CRSwNP. The introduction of endotyping has led to a differentiation of 'tailored' surgical approaches, focusing on the mucosal concept in those with severe CRSwNP and on the identification of patients eligible for extended surgery and possibly biologics in the future.

WITHDRAWN: Dupilumab: A review of potential in the treatment of Chronic rhinosinusitis with nasal polyps (CRSwNP)

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Molecular biology of BPIFB1 and its advances in disease

Bactericidal/permeability-increasing (BPI)-fold-containing family B member 1 (BPIFB1), also known as long-palate lung and nasal epithelium clone 1 (LPLUNC1), belongs to the BPI-fold-containing family, is a newly discovered natural immune protection molecule, which, having the function of bactericidal and osmotic enhancement protein domain, can respond to the external physical and chemical stimuli. The gene of BPIFB1 is located at chromosome 20q11.21-20q11.22, and contains 16 exons and 15 introns, encoding 484 amino acids. The 5' terminal of the BPIFB1 protein has a signal peptide sequence composed of 19 amino acids. BPIFB1 is abnormally expressed in nasopharyngeal carcinoma (NPC), gastric cancer, and other cancer tissues, regulate chronic infections and inflammation, indicating that it may play an important role in the development of tumors. Meanwhile, BPIFB1 has well-recognized roles in sensing and responding to Gram-negative bacteria due to its structural similarity with BPI protein and lipopolysaccharide (LPS)-binding protein, both of which are innate immune molecules with recognized roles in sensing and responding to Gram-negative bacteria, so it can regulate cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), asthma, and other respiratory diseases. In this article, we will discuss the progress of BPIFB1 in a variety of diseases and fully understand its function.

Airway Epithelial Dynamics in Allergy and Related Chronic Inflammatory Airway Diseases

Allergic rhinitis, chronic rhinosinusitis, and asthma are highly prevalent, multifactorial chronic airway diseases. Several environmental and genetic factors affect airway epithelial dynamics leading to activation of inflammatory mechanisms in the airways. This review links environmental factors to host epithelial immunity in airway diseases. Understanding altered homeostasis of the airway epithelium might provide important targets for diagnostics and therapy of chronic airway diseases.

Unexpected effects of systemic steroids on the CRSwNP proteome: is protein upregulation more important than inhibition?

BACKGROUND

Oral steroids, traditionally thought of as immunosuppressive agents that are broad in their immunomodulatory effects, are a mainstay of treatment to reduce disease burden in chronic rhinosinusitis with nasal polyps (CRSwNP). The purpose of this study was to determine how differentially expressed proteins in CRSwNP are affected by oral steroid therapy.

METHODS

Matched exosomal proteomic arrays were quantified using aptamer-based methods in systemic steroid-naive CRSwNP patients before and after a standardized oral prednisone course (n = 12). Previously identified differentially expressed proteins in CRSwNP patients were compared to determine the effect of steroids on expression. Fisher's exact test and t test were applied to normalized protein expression profiles to determine significance.

RESULTS

Of 18 proteins previously identified to be highly underexpressed in CRSwNP, 16 (89%) had an average increase after systemic steroid treatment (p < 0.05). Lactoperoxidase, initially present at 9-fold lower concentrations in CRSwNP subjects, increased by 209% after steroid treatment. A similar trend was observed with other proteins of interest, including platelet factor 4 and C-C motif ligand 28. The converse of this steroid effect was not true; of the 53 proteins that are highly overexpressed in CRSwNP, only 22 (42%) decreased in quantity with steroid use.

CONCLUSION

Proteomic analysis of differentially expressed proteins in CRSwNP demonstrates that systemic steroids cause almost uniform upregulation of transcriptionally decreased proteins, whereas the effects of steroids on transcriptionally increased proteins are more heterogeneous. Thus, proteomic analysis may be an effective tool to understand specific therapeutic benefits of steroid use in polyp disease and to create more targeted treatments.

Role of RANK-L as a potential inducer of ILC2-mediated type 2 inflammation in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 inflammation with accumulation of activated group 2 innate lymphoid cells (ILC2s) and elevation of thymic stromal lymphopoietin (TSLP). A member of the TNF superfamily (TNFSF), TNFSF15, is known to induce the production of type 2 cytokines in ILC2s. Although ILC2s have been implicated in CRSwNP, the presence and role of TNFSFs in ILC2-mediated type 2 inflammation in CRSwNP has not been elucidated. Here, we investigate the involvement of TNFSFs in ILC2-mediated type 2 inflammation in CRSwNP. We found that receptor activator of NF-κB (RANK) ligand (RANK-L (TNFSF11)) was significantly elevated in nasal polyps (NPs), and that the receptor of RANK-L, RANK, was expressed on ILC2s in human peripheral blood and NPs. An agonistic antibody against RANK induced production of type 2 cytokines in human ILC2s, and TSLP significantly enhanced this reaction. The membrane-bound RANK-L was detected mainly on CD45 + immune cells, including T_H2 cells in NPs. The co-culture of NP-derived ILC2s and T_H2 cells significantly enhanced production of type 2 cytokines, and anti-RANK-L monoclonal antibody suppressed this enhancement. In conclusion, RANK-L, together with TSLP, may play an inductive role in the ILC2-mediated type 2 inflammation in CRSwNP.

Diverse phenotypes and endotypes of fungus balls caused by mixed bacterial colonization in chronic rhinosinusitis

BACKGROUND

The pathogenic roles of fungus and bacteria in chronic rhinosinusitis (CRS) remain unclear. Recently, we described the bacterial ball, which is distinct from the fungus ball, as an unusual phenotype of bacterial infection. In this study, we investigated the clinical, histopathologic, and immunologic characteristics of sinonasal microorganic materials, including fungus ball and bacterial ball.

METHODS

In this study, we enrolled 80 CRS patients with sinonasal microorganic materials and 10 control subjects who underwent skull base surgery or endoscopic dacryocystorhinostomy and had no signs or symptoms of nasal inflammation. All specimens were stained with hematoxylin-eosin, Gomori-methenamine-silver, and Gram stain to identify fungal organisms and Gram-positive/negative bacterial colonies. The expression of tumor necrosis factor (TNF)-α; interleukin (IL)-1β; S100A7; S100A8/A9; and short, palate, lung, and nasal epithelial clone 1 (SPLUNC1) were evaluated by enzyme-linked immunosorbent assay using sinus lavage fluid.

RESULTS

We histologically classified sinonasal microorganic materials into the following 4 groups: fungus ball (n = 45); bacterial ball (n = 6); mixed ball (formed by a mixture of fungus and bacteria, n = 27); and double ball (formed by separate fungal and bacterial balls, n = 2). Compared with the fungus ball, the mixed ball was more frequently detected in immunocompromised patients (p < 0.0001). In addition, TNF-α expression was significantly higher in fungus and mixed balls than in control, whereas the mixed ball showed higher expression of IL-1β compared with the fungus ball. Moreover, the expression of S100A7 and S100A8/A9 protein in the mixed ball was significantly decreased when compared with the fungus ball, whereas there was no significant difference in SPLUNC1 expression between fungus and mixed balls.

CONCLUSION

Our findings suggest that fungal and bacterial interactions are diverse in CRS. Specifically, the mixed ball is prevalent in CRS with an immunocompromised state and it may decrease epithelial barrier function.

Identification of key genes and pathways in chronic rhinosinusitis with nasal polyps using bioinformatics analysis

PURPOSE

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a prevalent inflammatory disease of yet unknown etiology. The purpose of this study was to uncover key genes and pathways related to the pathogenesis of CRSwNP via bioinformatics approaches.

MATERIALS AND METHODS

The gene expression profile of GSE36830 extracted from Gene Expression Omnibus database was used to screen differentially expressed genes (DEGs) between nasal polyp samples and control samples. Furthermore, functional and pathway enrichment analysis was performed using the clusterProfiler package in R language. In addition, protein-protein interaction (PPI) network was constructed by STRING database and functional modules were detected using Molecular Complex Detection algorithm.

RESULTS

A total of 538 DEGs (326 up-regulated and 212 down-regulated) were identified. The most significantly enriched pathways for up-regulated and down-regulated genes were hematopoietic cell lineage and salivary secretion, respectively. Moreover, twenty hub genes with high connectivity degrees were selected from the PPI network, such as TYRO protein tyrosine kinase binding protein (TYROBP), G protein subunit gamma 2 (GNG2), CCR7, and CCR3. Besides, six important modules were obtained, which were highly associated with chemokine signaling pathway, Th1 and Th2 cell differentiation, complement and coagulation cascades, cell cycle, systemic lupus erythematosus, and Staphylococcus aureus infection.

CONCLUSIONS

The results of this study may provide new insights into potential molecular mechanisms of CRSwNP. Nevertheless, further experiments are needed to confirm these findings.

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.

Lipophilic Allergens, Different Modes of Allergen-Lipid Interaction and Their Impact on Asthma and Allergy

Molecular allergology research has provided valuable information on the structure and function of single allergenic molecules. There are several allergens in food and inhalant allergen sources that are able to interact with lipid ligands via different structural features: hydrophobic pockets, hydrophobic cavities, or specialized domains. For only a few of these allergens information on their associated ligands is already available. Several of the allergens are clinically relevant, so that it is highly probable that the individual structural features with which they interact with lipids have a direct effect on their allergenic potential, and thus on allergy development. There is some evidence for a protective effect of lipids delaying the enzymatic digestion of the peanut (Arachis hypogaea) allergen Ara h 8 (hydrophobic pocket), probably allowing this molecule to get to the intestinal immune system intact (sensitization). Oleosins from different food allergen sources are part of lipid storage organelles and potential marker allergens for the severity of the allergic reaction. House dust mite (HDM), is more often associated with allergic asthma than other sources of inhalant allergens. In particular, lipid-associated allergens from Dermatophagoides pteronyssinus which are Der p 2, Der p 5, Der p 7, Der p 13, Der p 14, and Der p 21 have been reported to be associated with severe allergic reactions and respiratory symptoms such as asthma. The exact mechanism of interaction of these allergens with lipids still has to be elucidated. Apart from single allergens glycolipids have been shown to directly induce allergic inflammation. Several-in parts conflicting-data exist on the lipid (and allergen) and toll-like receptor interactions. For only few single allergens mechanistic studies were performed on their interaction with the air-liquid interface of the lungs, in particular with the surfactant components SP-A and SP-D. The increasing knowledge on protein-lipid-interaction for lipophilic and hydrophobic food and inhalant allergens on the basis of their particular structure, of their capacity to be integral part of membranes (like the oleosins), and their ability to interact with membranes, surfactant components, and transport lipids (like the lipid transfer proteins) are essential to eventually clarify allergy and asthma development.

Chronic rhinosinusitis: pathogenesis, therapy options, and more

INTRODUCTION

When rhinosinusitis - the inflammation of the nasal cavity and paranasal sinuses - persists for over 12 weeks, it is termed 'chronic rhinosinusitis' (CRS). Both innate and adaptive immunity contribute to the heterogeneous inflammatory pathogenesis of CRS, which is driven by genetic and environmental factors and the microbiome. CRS is classified by the presence of polyps. Molecular mechanisms in CRS with nasal polyps are similar to those in atopic diseases.

AREAS COVERED

This review focuses on the immune pathogenesis of CRS, differences between the two CRS subtypes, and latest treatments that may aid in the provision of personalized medicine.

EXPERT OPINION

Basic research in the last decade has helped significantly in enhancing our knowledge of the pathophysiologic processes of CRS, due to which there is now a better understanding of the associated natural history, physiopathology, novel treatments, and prevention strategies. Treatment success depends on the clarification of the underlying pathogenesis and disease-contributing factors. The exploration of disease endotypes and introduction of novel agents are important advancements. Prior studies performed without disease-endotyping resulted in the inefficiency of certain drugs and insignificant results. The identification of biomarkers, development of personalized approaches, and utilization of disease algorithms are required for CRS therapy success.

Pathophysiologic mechanisms of chronic rhinosinusitis and their roles in emerging disease endotypes

OBJECTIVE

Chronic rhinosinusitis (CRS) is a heterogeneous disorder with distinct pathophysiologic mechanisms. Based on transcription factor expression and cytokine production patterns in different innate lymphoid cell (ILC) types, in parallel with those of adaptive CD4⁺ T-helper (T_H) cells and CD8⁺ cytotoxic T (Tc) cells, new perspectives on endotypes of patients are emerging for the immune response deviation into type 1 (orchestrated by ILC1s and Tc1, and T_H1 cells), type 2 (characterized by ILC2s and Tc2 and T_H2 cells), and type 3 (mediated by ILC3s and Tc17 and T_H17 cells). In addition, cluster analysis has been applied to endotyping of CRS in recent years, which has provided additional novel insights into CRS pathogenesis. This review assessed pathologic mechanisms of CRS based on type 1, 2, and 3 immune responses and how they inform us to begin to understand CRS endotypes. This review also assessed recent cluster analysis studies of CRS endotypes. The impact of endotype on therapeutic management of CRS also is summarized.

DATA SOURCES

Review of published literature.

STUDY SELECTIONS

Relevant literature concerning CRS endotypes and possible underlying mechanisms was obtained from a PubMed search and summarized.

RESULTS AND CONCLUSION

CRS with and without nasal polyps are composed of distinct endotypes with distinct deviated immune responses, pathogenic mechanisms, and different responses to medical and surgical treatment. An endotype of CRS with prominent type 2 immune responses is the best-studied endotype and generally can benefit from treatment with steroids and specific type 2 disrupting biologics.

Clinical efficacy of sublingual immunotherapy is associated with restoration of steady-state serum lipocalin 2 after SLIT: a pilot study

Background

So far, only a few biomarkers in allergen immunotherapy exist that are associated with a clinical benefit. We thus investigated in a pilot study whether innate molecules such as the molecule lipocalin-2 (LCN2), with implications in immune tolerance demonstrated in other fields, may discriminate A) between allergic and non-allergic individuals, and B) between patients clinically responding or non-responding to sublingual allergen immunotherapy (SLIT) with house dust mite (HDM) extract. Moreover, we assessed haematological changes potentially correlating with allergic symptoms.

Methods

LCN2-concentrations were assessed in sera of healthy and allergic subjects (n = 126) as well as of house dust mite (HDM) allergics before and during HDM- sublingual immunotherapy (SLIT) in a randomized, double-blind, placebo-controlled trial for 24 weeks. Sera pre-SLIT (week 0), post-SLIT (week 24) and 9 months after SLIT were assessed for LCN2 levels and correlated with total nasal symptom scores (TNSS) obtained during chamber challenge at week 24 in patients receiving HDM- (n = 31) or placebo-SLIT (n = 10).

Results

Allergic individuals had significantly (p < 0.0001) lower LCN2-levels than healthy controls. HDM-allergic patients who received HDM-SLIT showed a significant increase in LCN2 9 months after termination of HDM-SLIT (p < 0.001), whereas in subjects receiving placebo no increase in LCN2 was observed. Among blood parameters a lower absolute rise in the lymphocyte population (p < 0.05) negatively correlated with symptom improvement (Pearson r 0.3395), and a lower relative increase in the neutrophils were associated with improvement in TNSS (p < 0.05). LCN2 levels 9 months after immunotherapy showed a low positive correlation with the relative improvement of symptoms (Pearson r 0.3293). LCN2-levels 9 months off-SLIT were significantly higher in patients whose symptoms improved during chamber challenge than in those whose symptoms aggravated (p < 0.01).

Conclusion

Serum LCN2 concentrations 9 months off-SLIT correlated with clinical reactivity in allergic patients. An increase in the LCN2 levels 9 months after HDM-SLIT was associated with a clinical benefit. Serum LCN2 may thus contribute to assess clinical reactivity in allergic patients.

Trial registration

Part of the data were generated from clinicaltrials.gov Identifier NCT01644617.

Biomarkers in Chronic Rhinosinusitis with Nasal Polyps

Chronic rhinosinusitis is a complex disease that exists along the inflammatory spectrum between types 1 and 2 inflammation. The classic phenotypic differentiation of chronic rhinosinusitis based on the presence or absence of inflammatory polyps remains one of the best differentiators of response to therapy. Development of biologics for the treatment of atopic disease and asthma and topical therapies for sinusitis have placed renewed emphasis on understanding the pathophysiology of polyp disease. Identification of key markers of polyposis will allow for better stratification of inflammatory polyp disease endotypes to objectively identify medical therapies and track response to treatment.

The Role of BPIFA1 in Upper Airway Microbial Infections and Correlated Diseases

The mucosa is part of the first line of immune defense against pathogen exposure in humans and prevents viral and bacterial infection of the soft palate, lungs, uvula, and nasal cavity that comprise the ear-nose-throat (ENT) region. Bactericidal/permeability-increasing fold containing family A, member 1 (BPIFA1) is a secretory protein found in human upper aerodigestive tract mucosa. This innate material is secreted in mucosal fluid or found in submucosal tissue in the human soft palate, lung, uvula, and nasal cavity. BPIFA1 is a critical component of the innate immune response that prevents upper airway diseases. This review will provide a brief introduction of the roles of BPIFA1 in the upper airway (with a focus on the nasal cavity, sinus, and middle ear), specifically its history, identification, distribution in various human tissues, function, and diagnostic value in various upper airway infectious diseases.

Crystal structure of the mouse innate immunity factor bacterial permeability-increasing family member A1

Bacterial permeability-increasing family member A1 (BPIFA1) is an innate immunity factor and one of the most abundantly secreted proteins in the upper airways. BPIFA1 is multifunctional, with antimicrobial, surfactant and lipopolysaccharide-binding activities, as well as established roles in lung hydration. Here, the 2.5 Å resolution crystal structure of BPIFA1 from Mus musculus (mBPIFA1) is presented and compared with those of human BPIFA1 (hBPIFA1) and structural homologs. Structural distinctions between mBPIFA1 and hBPIFA1 suggest potential differences in biological function, including the regulation of a key pulmonary ion channel.

Modelling upper respiratory tract diseases: getting grips on host-microbe interactions in chronic rhinosinusitis using in vitro technologies

Chronic rhinosinusitis (CRS) is a chronic inflammation of the mucosa of the nose and paranasal sinuses affecting approximately 11% of the adult population in Europe. Inadequate immune responses, as well as a dysbiosis of the sinonasal microbiota, have been put forward as aetiological factors of the disease. However, despite the prevalence of this disease, there is no consensus on the aetiology and mechanisms of pathogenesis of CRS. Further research requires in vitro models mimicking the healthy and diseased host environment along with the sinonasal microbiota. This review aims to provide an overview of CRS model systems and proposes in vitro modelling strategies to conduct mechanistic research in an ecological framework on the sinonasal microbiota and its interactions with the host in health and CRS.

Loss of the homeostatic protein BPIFA1, leads to exacerbation of otitis media severity in the Junbo mouse model

Otitis Media (OM) is characterized by epithelial abnormalities and defects in innate immunity in the middle ear (ME). Although, BPIFA1, a member of the BPI fold containing family of putative innate defence proteins is abundantly expressed by the ME epithelium and SNPs in Bpifa1 have been associated with OM susceptibility, its role in the ME is not well characterized. We investigated the role of BPIFA1 in protection of the ME and the development of OM using murine models. Loss of Bpifa1 did not lead to OM development. However, deletion of Bpifa1 in Evi1^Jbo/+ mice, a model of chronic OM, caused significant exacerbation of OM severity, thickening of the ME mucosa and increased collagen deposition, without a significant increase in pro-inflammatory gene expression. Our data suggests that BPIFA1 is involved in maintaining homeostasis within the ME under steady state conditions and its loss in the presence of inflammation, exacerbates epithelial remodelling leading to more severe OM.

Infectious Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a persistent inflammatory disease that affects a multitude of people worldwide. The pathogenesis of CRS involves many factors including genetics, status of the sinonasal microbiome, infections, and environmental influences. Comorbidities associated with CRS include asthma, allergic rhinitis, bronchiectasis, and certain kinds of immunodeficiency. CRS can be divided into different subtypes based on endotypes and phenotypes. Infectious CRS is one such category. The etiology of infectious CRS is usually secondary to chronic bacterial infection that commonly begins with a viral upper respiratory tract infection. Humoral antibody deficiencies can underlie difficult-to-treat or recurrent CRS. Infectious CRS can be treated with antimicrobials, topical or oral corticosteroids, and nasal saline irrigations. Patients with CRS and humoral immunodeficiency may require an aggressive treatment approach including immunoglobulin replacement therapy. Despite advancements in the field of CRS, targeted therapies and reliable biomarkers are still lacking.

Potential Involvement of the Epidermal Growth Factor Receptor Ligand Epiregulin and Matrix Metalloproteinase-1 in Pathogenesis of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a heterogeneous chronic inflammatory disease of the nose and paranasal sinuses that presents without or with nasal polyps (CRSwNP). Notable features of CRSwNP are the frequent presence of type 2 allergic inflammation and high prevalence of Staphylococcus aureus (SA) colonization. As inflammation persists, sinus tissue undergoes epithelial damage and repair along with polyp growth, despite active medical management. Because one feature of damaged tissue is enhancement of growth factor signaling, we evaluated the presence of epidermal growth factor receptor (EGFR) ligands and matrix metalloproteinases (MMPs) in CRS. The objectives of this study were to analyze the expression of EGFR ligands and MMPs in patients with CRS and to investigate the possible role of SA on epithelial activation. Sinonasal tissues were collected during surgery from control subjects and patients with CRS. Tissues were processed as described previously for analysis of mRNA (RT-PCR) and proteins (ELISA) for the majority of EGFR ligands within the tissue extracts. CRS tissue was used for evaluation of the distribution of epiregulin (EREG), an EGFR ligand, and MMP-1 by immunohistochemistry. In parallel studies, expression of these genes and proteins was analyzed in cultured primary airway epithelial cells. Elevated expression of EREG and MMP-1 mRNA and protein was observed in uncinate and polyp tissue from patients with CRSwNP. Immunohistochemistry study of clinical samples revealed that airway epithelial cells expressed both of these proteins. Cultured primary human airway epithelial cells expressed MMP-1, and MMP-1 was further induced by stimulation with EREG or heat-killed SA (HKSA). The induction of MMP-1 by HKSA was blocked by an antibody against EREG, suggesting that endogenous EREG induces MMP-1 after stimulation with HKSA. EREG and MMP-1 were found to be elevated in nasal polyp and uncinate tissues in patients with CRSwNP. Elevated expression of EREG and MMP-1 may be related to polyp formation in CRS, and colonization of SA might further enhance this process.

Neutrophils are a major source of the epithelial barrier disrupting cytokine oncostatin M in patients with mucosal airways disease

BACKGROUND

We have previously shown that oncostatin M (OSM) levels are increased in nasal polyps (NPs) of patients with chronic rhinosinusitis (CRS), as well as in bronchoalveolar lavage fluid, after segmental allergen challenge in allergic asthmatic patients. We also showed in vitro that physiologic levels of OSM impair barrier function in differentiated airway epithelium.

OBJECTIVE

We sought to determine which hematopoietic or resident cell type or types were the source of the OSM expressed in patients with mucosal airways disease.

METHODS

Paraffin-embedded NP sections were stained with fluorescence-labeled specific antibodies against OSM, GM-CSF, and hematopoietic cell-specific markers. Live cells were isolated from NPs and matched blood samples for flow cytometric analysis. Neutrophils were isolated from whole blood and cultured with the known OSM inducers GM-CSF and follistatin-like 1, and OSM levels were measured in the supernatants. Bronchial biopsy sections from control subjects, patients with moderate asthma, and patients with severe asthma were stained for OSM and neutrophil elastase.

RESULTS

OSM staining was observed in NPs, showed colocalization with neutrophil elastase (n = 10), and did not colocalize with markers for eosinophils, macrophages, T cells, or B cells (n = 3-5). Flow cytometric analysis of NPs (n = 9) showed that 5.1% ± 2% of CD45+ cells were OSM+, and of the OSM+ cells, 56% ± 7% were CD16+Siglec-8-, indicating neutrophil lineage. Only 0.6 ± 0.4% of CD45+ events from matched blood samples (n = 5) were OSM+, suggesting that increased OSM levels in patients with CRS was locally stimulated and produced. A majority of OSM+ neutrophils expressed arginase 1 (72.5% ± 12%), suggesting an N2 phenotype. GM-CSF levels were increased in NPs compared with those in control tissue and were sufficient to induce OSM production (P < .001) in peripheral blood neutrophils in vitro. OSM+ neutrophils were also observed at increased levels in biopsy specimens from patients with severe asthma. Additionally, OSM protein levels were increased in induced sputum from asthmatic patients compared with that from control subjects (P < .05).

CONCLUSIONS

Neutrophils are a major source of OSM-producing cells in patients with CRS and severe asthma.

Group 2 innate lymphoid cells are elevated and activated in chronic rhinosinusitis with nasal polyps

Background

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is characterized by type 2 inflammation with high levels of Th2 cytokines. Although T helper cytokines are released from T cells, innate lymphoid cells (ILC) are also known to produce high levels of the same cytokines. However, the presence of various types of ILC in CRS is poorly understood.

Objective

The objective of this study was to fully characterize the presence of all ILC subsets in CRS and to identify phenotypical differences of group 2 ILC (ILC2) in CRSwNP compared to ILC2 from non‐type 2 inflamed areas.

Methods

We investigated the presence of ILC subsets in peripheral blood mononuclear cells (PBMC) from healthy subjects, tonsil tissue, ethmoid tissue from control subjects and patients with non‐polypoid CRS (CRSsNP) and CRSwNP, as well as nasal polyp (NP) tissue from CRSwNP by flow cytometry. Sorted ILC2 were cultured in the presence and absence of IL‐33 and production of IL‐5 and IL‐13 was assessed by Luminex.

Results

We found that all ILC subsets were present in NP but ILC2 were dominant and significantly elevated compared to PBMC, tonsil, CRSsNP, and normal sinus tissue. We also found that inducible T‐cell co‐stimulator (ICOS) and side scatter were increased and CD127 was down‐regulated in ILC2 from NP compared to blood or tonsil ILC2. Thymic stromal lymphopoietin, IL‐7, and IL‐33 were able to down‐regulate expression of CD127 and increase side scatter in blood ILC2. Furthermore, sorted NP ILC2 but not blood ILC2 spontaneously released type 2 cytokines including IL‐5 and IL‐13.

Conclusions and Clinical Relevance

These results suggest that ILC2 are not only elevated but also activated in CRSwNP in vivo and that ILC2 may play important roles in the type 2 inflammation in CRSwNP.

Immunopathogenesis of Chronic Rhinosinusitis and Nasal Polyposis

Chronic rhinosinusitis (CRS) is a troublesome, chronic inflammatory disease that affects over 10% of the adult population, causing decreased quality of life, lost productivity, and lost time at work and leading to more than a million surgical interventions annually worldwide. The nose, paranasal sinuses, and associated lymphoid tissues play important roles in homeostasis and immunity, and CRS significantly impairs these normal functions. Pathogenic mechanisms of CRS have recently become the focus of intense investigations worldwide, and significant progress has been made. The two main forms of CRS that have been long recognized, with and without nasal polyps, are each now known to be heterogeneous, based on underlying mechanism, geographical location, and race. Loss of the immune barrier, including increased permeability of mucosal epithelium and reduced production of important antimicrobial substances and responses, is a common feature of many forms of CRS. One form of CRS with polyps found worldwide is driven by the cytokines IL-5 and IL-13 coming from Th2 cells, type 2 innate lymphoid cells, and probably mast cells. Type 2 cytokines activate inflammatory cells that are implicated in the pathogenic mechanism, including mast cells, basophils, and eosinophils. New classes of biological drugs that block the production or action of these cytokines are making important inroads toward new treatment paradigms in polypoid CRS.

Allergic Aspergillus Rhinosinusitis

Allergic fungal rhinosinusitis (AFRS) is a unique variety of chronic polypoid rhinosinusitis usually in atopic individuals, characterized by presence of eosinophilic mucin and fungal hyphae in paranasal sinuses without invasion into surrounding mucosa. It has emerged as an important disease involving a large population across the world with geographic variation in incidence and epidemiology. The disease is surrounded by controversies regarding its definition and etiopathogenesis. A working group on "Fungal Sinusitis" under the International Society for Human and Animal Mycology (ISHAM) addressed some of those issues, but many questions remain unanswered. The descriptions of "eosinophilic fungal rhinosinusitis" (EFRS), "eosinophilic mucin rhinosinusitis" (EMRS) and mucosal invasion by hyphae in few patients have increased the problem to delineate the disease. Various hypotheses exist for etiopathogenesis of AFRS with considerable overlap, though recent extensive studies have made certain in depth understanding. The diagnosis of AFRS is a multi-disciplinary approach including the imaging, histopathology, mycology and immunological investigations. Though there is no uniform management protocol for AFRS, surgical clearing of the sinuses with steroid therapy are commonly practiced. The role of antifungal agents, leukotriene antagonists and immunomodulators is still questionable. The present review covers the controversies, recent advances in pathogenesis, diagnosis, and management of AFRS.