Identification of clinically relevant chronic rhinosinusitis endotypes using cluster analysis of mucus cytokines

Endotypes of Chronic Rhinosinusitis with Primary and Recurring Nasal Polyps in the Latvian Population

Chronic rhinosinusitis (CRS) is a complex syndrome with various inflammatory mechanisms resulting in different patterns of inflammation that correlate with the clinical phenotypes of CRS. Our aim was to use detected IL-1, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, Ki 67, HBD-2, HBD-3, and LL-37 to classify specific inflammatory endotypes in chronic rhinosinusitis with the tissue of nasal polyps (CRSwNP). Samples from 35 individuals with primary and recurrent CRSwNP were taken during surgery. The tissues were stained for the previously mentioned biomarkers immunohistochemically. A hierarchical cluster analysis was performed. The clinical parameters were compared between clusters. Five clusters had significantly different biomarkers between groups. There were no significant differences in the clinical parameters, except for the Lund-Mackay score, which was significantly higher in cluster 4 compared to that of cluster 1 (p = 0.024). Five endotypes of (CRSwNP) are characterized by different combinations of type 1, type 2, and type 3 tissue inflammation patterns. In the Latvian population, endotypes associated with neutrophilic inflammation or a combination of neutrophilic inflammation and type 2 inflammation are predominant. Increased proliferation marker Ki 67 values are not associated with more severe inflammation in the tissue samples of chronic rhinosinusitis with nasal polyps.

IL-13 and IL-13-induced periostin levels are specifically decreased in patients following endoscopic sinus surgery for chronic rhinosinusitis

BACKGROUND

Type 2 (T2) inflammation plays a pathogenic role in chronic rhinosinusitis (CRS). The effects of endoscopic sinus surgery (ESS) on T2 inflammation are unknown.

OBJECTIVE

The aim of this study was to compare T2 inflammatory biomarkers from middle meatal (MM) mucus for distinguishing patients with CRS from CRS-free patients, identifying major phenotypes (CRS without nasal polyps [CRSsNP] and CRS with nasal polyps [CRSwNP]), assessing endotypic change, and establishing cross-sectional and longitudinal outcomes in patients undergoing ESS.

METHODS

MM mucus samples were collected from patients with CRSsNP and patients with CRSwNP before and 6 to 12 months after ESS and compared with samples from CRS-free control patients. T2 biomarkers were evaluated both continuously and using threshold-based definitions of T2 endotype to identify relationships with patient-reported (based on the 22-Item Sinonasal Outcomes Test and Chronic Rhinosinusitis Patient-Reported Outcomes Measure) and clinician-reported (radiographic and endoscopic) severity. Linear mixed models were developed to analyze clinical variables associated with T2 biomarker levels.

RESULTS

A total of 154 patients with CRS (89 with CRSsNP and 65 with CRSwNP) were enrolled, with a mean interval of 9 months between ESS and follow-up. An analysis of pre-ESS MM mucus samples revealed elevated levels of T2 mediators in patients with CRSwNP versus in patients with CRSsNP and CRS-free controls. Temporally stable correlations between levels of IL-13 and IL-5, levels of periostin and complement 5a, and levels of eosinophil cationic protein (ECP) and eotaxin-3 were observed. On this basis and on the basis of pathologic significance, levels of IL-13, periostin and ECP were further analyzed. After ESS, levels of IL-13 and periostin decreased significantly, whereas ECP levels remained unchanged. Across pre- and post-ESS evaluation, the T2 endotype was associated with radiographic severity but did not predict outcomes. CRSwNP status and African American race were associated with higher levels of IL-13 and periostin, whereas ECP level was higher in patients undergoing extensive surgery.

CONCLUSION

ESS decreased levels of IL-13 and periostin in the middle meatus. T2 inflammation after ESS was correlated with patient- and clinician-reported severity across phenotypes. Pre-ESS T2 inflammation did not predict post-ESS outcomes.

Particulate matter exposure is associated with increased inflammatory cytokines and eosinophils in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is thought to result from complex interactions between the host immune system, microbiota, and environmental exposures. Currently, there is limited data regarding the impact of ambient particulate matter ≤2.5 μm in diameter (PM2.5) in the pathogenesis of CRS, despite evidence linking PM2.5 to other respiratory diseases. We hypothesized that PM2.5 may result in differential cytokine patterns that could inform our mechanistic understanding of the effect of environmental factors on CRS.

METHODS

We conducted an analysis of data prospectively collected from 308 CRS patients undergoing endoscopic sinus surgery. Cytokines were quantified in intraoperative mucus specimens using a multiplex flow cytometric bead assay. Clinical and demographic data including zip codes were extracted and used to obtain tract-level income and rurality measures. A spatiotemporal machine learning model was used to estimate daily PM2.5 levels for the year prior to each patient's surgery date. Spearman correlations and regression analysis were performed to characterize the relationship between mucus cytokines and PM2.5. RESULTS: Several inflammatory cytokines including IL-2, IL-5/IL-13, IL-12, and 21 were significantly correlated with estimated average 6, 9, and 12-month preoperative PM2.5 levels. These relationships were maintained for most cytokines after adjusting for age, income, body mass index, rurality, polyps, asthma, and allergic rhinitis (AR) (p < .05). There were also higher odds of asthma (OR = 1.5, p = .01) and AR (OR = 1.48, p = .03) with increasing 12-month PM2.5 exposure. Higher tissue eosinophil counts were associated with increasing PM2.5 levels across multiple timeframes (p < .05).

CONCLUSIONS

Chronic PM2.5 exposure may be an independent risk factor for development of a mixed, type-2 dominant CRS inflammatory response.

The interleukin-4/interleukin-13 pathway in type 2 inflammation in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is predominantly a type 2 inflammatory disease associated with type 2 (T2) cell responses and epithelial barrier, mucociliary, and olfactory dysfunction. The inflammatory cytokines interleukin (IL)-4, IL-13, and IL-5 are key mediators driving and perpetuating type 2 inflammation. The inflammatory responses driven by these cytokines include the recruitment and activation of eosinophils, basophils, mast cells, goblet cells, M2 macrophages, and B cells. The activation of these immune cells results in a range of pathologic effects including immunoglobulin E production, an increase in the number of smooth muscle cells within the nasal mucosa and a reduction in their contractility, increased deposition of fibrinogen, mucus hyperproduction, and local edema. The cytokine-driven structural changes include nasal polyp formation and nasal epithelial tissue remodeling, which perpetuate barrier dysfunction. Type 2 inflammation may also alter the availability or function of olfactory sensory neurons contributing to loss of sense of smell. Targeting these key cytokine pathways has emerged as an effective approach for the treatment of type 2 inflammatory airway diseases, and a number of biologic agents are now available or in development for CRSwNP. In this review, we provide an overview of the inflammatory pathways involved in CRSwNP and describe how targeting key drivers of type 2 inflammation is an effective therapeutic option for patients.

All chronic rhinosinusitis endotype clusters demonstrate improvement in patient-reported and clinical outcome measures after endoscopic sinus surgery

BACKGROUND

It is unclear whether chronic rhinosinusitis (CRS) endotypes show a differential response to endoscopic sinus surgery (ESS). We explored patient mucous inflammatory cytokine expression and associations with patient-reported and clinically measured post-operative outcome measures.

METHODS

Patients with CRS were prospectively recruited between 2016 and 2021 into a national multicenter, observational study. Mucus was collected from the olfactory cleft preoperatively and evaluated for 26 biomarkers using cluster analysis. Patient-reported outcome measures included the 22-item Sino-Nasal Outcome Test (SNOT-22) and Questionnaire of Olfactory Dysfunction (QOD). Additional clinical measures of disease severity included threshold, discrimination, and identification (TDI) scores using "Sniffin' Sticks" testing and Lund-Kennedy endoscopic score (LKES).

RESULTS

A total of 115 patients were clustered into type 2 inflammatory, non-type 2 inflammatory, noninflammatory, and two indeterminate clusters based on individual protein levels. Overall, the type 2 inflammatory cluster was found to have the highest mean improvement in both SNOT-22 (-28.3 [standard deviation, ±16.2]) and TDI (6.5 [standard deviation, ±7.9]) scores 6 months after ESS. However, on average, all endotype clusters demonstrated improvement in all outcome measures after ESS without statistically significant between-group differences in SNOT-22 (p = 0.738), QOD (p = 0.306), TDI (p = 0.358), or LKES (p = 0.514) measures.

CONCLUSIONS

All CRS endotype clusters responded favorably to surgery and showed improvements in patient-reported and objective outcome measures. Thus, ESS should be considered a more generalized CRS therapy, and benefits appear to not be limited to specific endotypes.

Treatable Traits in Asthma: The Importance of Extrapulmonary Traits-GERD, CRSwNP, Atopic Dermatitis, and Depression/Anxiety

Treatable traits is a personalized medicine approach to the management of airway disease. Assessing traits within the 3 domains of pulmonary, extrapulmonary, and behavioral/lifestyle/risk factor traits, and applying targeted treatments to effectively manage these traits, enables a holistic and personalized approach to care. Asthma is a heterogeneous and complex airway disease that is frequently complicated by several extrapulmonary traits that impact asthma outcomes and predict future outcomes. We propose that the identification of extrapulmonary and behavioral risk factor traits and the implementation of targeted therapy will lead to improved management of people with asthma. Furthermore, many extrapulmonary traits present as "connected comorbidities"; that is, they coexist with asthma, have an impact on asthma, and effective treatment improves both asthma and the comorbidity or the comorbidities may share a similar mechanism. In this review, we explore this concept and look at atopic dermatitis, chronic rhinosinusitis with nasal polyps, gastroesophageal reflux disease, anxiety, and depression as treatable traits of asthma and how these can be managed using this approach.

Current and Novel Biologic Therapies for Patients with Asthma and Nasal Polyps

A substantial portion of asthma and nasal polyps (NPs) share a common pathogenesis, which includes type 2-mediated inflammation. Distinct endotypes and phenotypes characterizing asthma and chronic rhinosinusitis have been identified. With emerging evidence describing pathophysiology, novel targets for biologic monoclonal antibody treatments have been developed. There are currently six biologic therapies approved by the US Food and Drug Administration to treat asthma, including omalizumab, mepolizumab, reslizumab, benralizumab, dupilumab, and tezepelumab, three of these-omalizumab, mepolizumab, and dupilumab-are also approved for NPs.

Clinical Subtypes of Neutrophilic Asthma: A Cluster Analysis From Australasian Severe Asthma Network

BACKGROUND

Clinical heterogeneity may exist within asthma subtypes defined by inflammatory markers. However, the heterogeneity of neutrophilic asthma (NA) remains largely unexplored.

OBJECTIVE

To explore potential clusters and the stability of NA.

METHODS

Participants with NA from the Australasian Severe Asthma Network underwent a multidimensional assessment. They were then asked to participate in a 12-month longitudinal cohort study. We explored potential clusters using a hierarchical cluster analysis and validated the differential future risk of asthma exacerbations in the identified clusters. A decision tree analysis was developed to predict cluster assignments. Finally, the stability of prespecified clusters was examined within 1 month.

RESULTS

Three clusters were identified in 149 patients with NA. Cluster 1 (n = 99; 66.4%) was characterized by female-predominant nonsmokers with well-controlled NA, cluster 2 (n = 16; 10.7%) by individuals with comorbid anxiety/depressive symptoms with poorly controlled NA, and cluster 3 by older male smokers with late-onset NA. Cluster 2 had a greater proportion of participants with severe exacerbations (P = .005), hospitalization (P = .010), and unscheduled visits (P = .013) and a higher number of emergency room visits (P = .039) than that of the other two clusters. The decision tree assigned 92.6% of participants correctly. Most participants (87.5%; n = 7) in cluster 2 had a stable NA phenotype, whereas participants of clusters 1 and 3 had variable phenotypes.

CONCLUSIONS

We identified three clinical clusters of NA, in which cluster 2 represents an uncontrolled and stable NA subtype with an elevated risk of exacerbations. These findings have clinical implications for the management of NA.

Prevalence of type 2 inflammatory signatures and efficacy of dupilumab in patients with chronic rhinosinusitis with nasal polyps from two phase 3 clinical trials: SINUS-24 and SINUS-52

BACKGROUND

This post hoc analysis of the international SINUS-24/-52 trials (NCT02912468/NCT02898454) aimed to assess dupilumab efficacy in patients with severe chronic rhinosinusitis with nasal polyps (CRSwNP) according to different definitions of type 2 inflammatory signature.

METHODS

Six definitions of type 2 inflammation were used: ≥150 eosinophils/μL or total immunoglobulin E (IgE) ≥100 IU/mL with a coexisting type 2 condition; ≥150 eosinophils/μL or total IgE ≥100 IU/mL; ≥150 eosinophils/μL; ≥250 eosinophils/μL or total IgE ≥100 IU/mL; coexisting asthma or ≥300 eosinophils/μL; presence of a coexisting type 2 condition. Odds ratios (ORs; dupilumab vs. placebo) for achieving clinically meaningful improvement (≥1 point) from baseline to week 24 (pooled SINUS-24/-52) and week 52 (SINUS-52) were calculated for nasal polyp score (NPS; range 0-8), nasal congestion/obstruction score (NC; 0-3), and loss of smell score (LoS; 0-3).

RESULTS

At baseline (n = 724), most patients displayed a type 2 inflammatory signature across definitions (64.2%-95.3%). At week 24, ORs for clinically meaningful improvement ranged from 11.9 to 14.9 for NPS across type 2 definitions, 6.5-9.6 for NC, and 12.2-17.8 for LoS (all p < 0.0001). OR ranges were similar or greater at week 52: 19.0-36.6, 7.6-12.1, and 9.2-33.5, respectively (all p < 0.0001).

CONCLUSION

Most patients with CRSwNP in the SINUS study had type 2 inflammation. Dupilumab demonstrated robust efficacy across definitions of type 2 inflammation, consistent with its profile as an inhibitor of Interleukin-4 and Interleukin-13 signaling, key and central drivers of type 2 inflammation in CRSwNP.

KEY POINTS

This study assessed type 2 inflammation prevalence and dupilumab efficacy in chronic rhinosinusitis with nasal polyps according to algorithm-defined type 2 inflammation Dupilumab efficacy was similar across all type 2 definitions.

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.

Inflammatory characteristics of central compartment atopic disease

BACKGROUND

Central compartment atopic disease (CCAD) is an emerging phenotype of chronic rhinosinusitis with nasal polyposis (CRSwNP) characterized by prominent central nasal inflammatory changes. This study compares the inflammatory characteristics of CCAD relative to other phenotypes of CRSwNP.

METHODS

A cross-sectional analysis of data from a prospective clinical study was performed on patients with CRSwNP who were undergoing endoscopic sinus surgery (ESS). Patients with CCAD, aspirin-exacerbated respiratory disease (AERD), allergic fungal rhinosinusitis (AFRS), and non-typed CRSwNP (CRSwNP NOS) were included and mucus cytokine levels and demographic data were analyzed for each group. Chi-squared/Mann-Whitney U tests and partial least squares discriminant analysis (PLS-DA) were performed for comparison and classification.

RESULTS

A total of 253 patients were analyzed (CRSwNP, n = 137; AFRS, n = 50; AERD, n = 42; CCAD, n = 24). Patients with CCAD were the least likely to have comorbid asthma (p = 0.0004). The incidence of allergic rhinitis in CCAD patients did not vary significantly compared to patients with AFRS and AERD, but was higher compared to patients with CRSwNP NOS (p = 0.04). On univariate analysis, CCAD was characterized by less inflammatory burden, with reduced levels of interleukin 6 (IL-6), IL-8, interferon gamma (IFN-γ), and eotaxin relative to other groups and significantly lower type 2 cytokines (IL-5, IL-13) relative to both AERD and AFRS. These findings were supported by multivariate PLS-DA, which clustered CCAD patients into a relatively homogenous low-inflammatory cytokine profile.

CONCLUSIONS

CCAD has unique endotypic features compared to other patients with CRSwNP. The lower inflammatory burden may be reflective of a less severe variant of CRSwNP.

Diverse Endotypes of Chronic Rhinosinusitis and Clinical Implications

Chronic rhinosinusitis (CRS) is a highly heterogeneous disease characterized by inflammation in the nasal and sinus mucosa. The CRS phenotypes, based on the presence or absence of nasal polyps, are known as CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). However, this classification has limitations in fully capturing the mechanisms and clinical manifestations of CRS. To address the heterogeneity of CRS, there has been a growing focus on classifying the condition into distinct endotypes. Endotype classification involves grouping patients based on specific molecular, immunological, and clinical characteristics, allowing for more personalized and targeted treatment approaches.This review delves into the current state of endotype classifications for CRS. It explores the role of geographic factors, microbiome, and subphenotype in shaping different endotypes. Additionally, the review examines how various clinical features are associated with specific endotypes, providing valuable insights into tailoring treatment options for better outcomes and transitions between different endotypes.Overall, this review offers a comprehensive and up-to-date perspective on the intricate realm of CRS endotype classifications. By unraveling the molecular and clinical intricacies, this review lays the foundation for more precise, effective, and individualized treatment strategies in the management of CRS.

Comparing Protein and Gene Expression Signature between Nasal Polyps and Nasal Fluids in Chronic Rhinosinusitis

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a serious inflammatory condition. Nasal fluids (NFs) present a noninvasive alternative to nasal biopsy for studying CRSwNP pathogenesis. We aimed to compare the protein and mRNA inflammation signature between nasal polyps (NPs) and NFs.

METHOD

The performance of polyvinyl alcohol (PVA) sponges and NFs absorbable device (NFAD) for collecting NFs from 20 patients with CRSwNP was compared using the Luminex assay. The other group consisted of four healthy controls and an additional 21 CRSwNP patients (including eosinophilic CRSwNP [ECRSwNP] and non-eosinophilic CRSwNP [NECRSwNP]) for protein quantification by Olink platform and gene expression evaluation by RNA-sequencing. Spearman's analysis was performed to detect correlations between protein expression levels in NFs and clinical assessment variables.

RESULTS

NFAD-collected NFs contained at least a 2-fold higher concentration of cytokines than that obtained using PVA sponge, and these cytokines levels are significantly associated with NPs (ρ > 0.45, p < 0.05). Differentially expressed proteins between NFs and NPs were significantly correlated in the ECRSwNP subgroup compared with controls (ρ = 0.41, p < 0.01). Levels of Th2/IL-13, MCP4, and CCL4, characteristic of eosinophilic infiltration, were increased in ECRSwNP patients. A significant correlation between gene and protein expression was observed (ρ = 0.34, p < 0.01). PDL2 levels in NFs were positively correlated with ECRSwNP postoperative recurrence, the nasal VAS, and SNOT-22 scores (ρ > 0.68, p < 0.05 for all).

CONCLUSION

Our study revealed similarities and discrepancies in inflammatory signatures between NPs and NFs in the same CRSwNP patient.

Epithelial innate immune response to Pseudomonas aeruginosa-derived flagellin in chronic rhinosinusitis

BACKGROUND

Pseudomonas aeruginosa is a common colonizing pathogen in the upper respiratory tract and is associated with recalcitrant chronic rhinosinusitis (CRS). Herein we sought to characterize the effect of P. aeruginosa-derived flagellin on human sinonasal epithelial cell (HSNEC) immune responses and determine whether these pathways are disrupted in CRS.

METHODS

Air-liquid interface cultures were established from CRS and healthy control donors. Cells were incubated with P. aeruginosa-derived flagellin for 24 hours and transcriptional changes were assessed using whole transcriptome RNA sequencing. Apical and basolateral secretion of the pro-inflammatory cytokines in interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 were measured after stimulation by lipopolysaccharide or flagellin and responses were compared between CRS and healthy control patients.

RESULTS

HSNECs were weakly responsive to lipopolysaccharide, whereas flagellin stimulated a profound innate immune response dominated by TNF-α, IL-1β, and IL-17 signaling and activation of the IL-17C/IL-23 axis. CRS-derived HNSECs showed an altered innate immune response to flagellin, characterized by a profound increase in TNF-α secretion coupled with reduced IL-6 secretion.

CONCLUSIONS

Flagellin activates a potent innate immune response in HSNECs characterized by pro-inflammatory mediators and cytokines/chemokines associated with neutrophilic inflammation. HSNECs from CRS patients have a dysregulated innate immune response to flagellin characterized by an imbalance between IL-6 and TNF-α secretion.

Tissue Eosinophilia is Superior to an Analysis by Polyp Status for the Chronic Rhinosinusitis Transcriptome: An RNA Study

OBJECTIVE

RNA sequencing (transcriptomics) is used to study biological pathways. However, the yield of data depends on comparing well-characterized cohorts. We compared tissue eosinophilia versus nasal polyp (NP) status as the metric to characterize transcriptomic mechanisms at play in eosinophilic and non-eosinophilic chronic rhinosinusitis (CRS) versus controls.

METHODS

RNA sequencing was conducted on sinonasal tissue samples of CRS and controls. Analyses were conducted based on polyp status [with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP)] as well as tissue eosinophil levels per high power field (eos/hpf)[non-eosinophilic (<10 eos/hpf, neCRS) or eosinophilic (≥10 eos/hpf, eCRS)]. The yield of differentially expressed genes (DEGs) and biological pathways through Ingenuity Pathway Analysis (IPA) were compared.

RESULTS

CRS tissue differed from controls by 736 statistically significant DEGs. Both NP status and tissue eosinophilia were effective in differentiating CRS from controls and into two distinct subgroups. Statistically significant DEGs identified when comparing CRS by NP status were 60, whereas 110 DEGs were identified using eosinophil cutoff ≥10 and <10 eos/hpf. Additionally, heatmaps showed greater homogeneity within each CRS subgroup when analyzed by tissue eosinophilia versus NP status. On IPA, the IL-17 signaling pathway was significantly different only by tissue eosinophilia status, not NP status, being higher in CRS <10 eos/hpf.

CONCLUSION

Tissue eosinophilia is superior to an analysis by NP status for the study of CRS transcriptome by RNA sequencing in identifying DEGs. Classification of CRS samples by eosinophil counts agnostic of NP status may offer advantageous insights into CRS pathogenetic mechanisms.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:2480-2489, 2023.

A Decade of Pathogenesis Advances in Non-Type 2 Inflammatory Endotypes in Chronic Rhinosinusitis: 2012-2022

Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by localized inflammation of the upper airways. CRS includes two main phenotypes, namely, CRS with nasal polyps and CRS without nasal polyps. The phenotype-based classification method cannot reflect the pathological mechanism. The endotype-based classification method has been paid more and more attention by researchers. It is mainly divided into type 2 and non-type 2 endotypes. The mechanism driving the pathogenesis of non-type 2 inflammation is currently unknown. In this review, the PubMed and Web of Science databases were searched to conduct a critical analysis of representative literature works on the pathogenesis of non-type 2 inflammation in CRS published in the past decade. This review summarizes the latest evidence that may lead to the pathogenesis of non-type 2 inflammation. It is the main method that analyzing the pathogenesis from the perspective of immunology. Genomics and proteomics technique provide new approaches to the study of the pathogenesis. Due to differences in race, environment, geography, and living habits, there are differences in the occurrence of non-type 2 inflammation, which increase the difficulty of understanding the pathogenesis of non-type 2 inflammation in CRS. Studies have confirmed that non-type 2 endotype is more common in Asian patients. The emergence of overlap and unclassified endotypes has promoted the study of heterogeneity in CRS. In addition, as the source of inflammatory cells and the initiation site of the inflammatory response, microvessels and microlymphatic vessels in the nasal mucosal subepithelial tissue participate in the inflammatory response and tissue remodeling. It is uncertain whether CRS patients affect the risk of infection with SARS-CoV-2. In addition, the pathophysiological mechanism of non-type 2 CRS combined with COVID-19 remains to be further studied, and it is worth considering how to select the befitting biologics for CRS patients with non-type 2 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 novel inflammatory endotype diagnostic model based on cytokines in chronic rhinosinusitis with nasal polyps

Background

Type 2 CRSwNP is characterized by severe symptoms, multiple comorbidities, longer recovery course and high recurrence rate. A simple and cost-effective diagnostic model for CRSwNP endotype integrating clinical characteristics and histopathological features is urgently needed.

Objective

To establish a clinical diagnostic model of inflammatory endotype in CRSwNP based on the clinical characteristics, pathological characteristics, and cytokines profile in the polyp tissue of patients.

Methods

A total of 244 participants with CRSwNP were enrolled at 2 different centers in China and Belgium from 2018 to 2020. IL-5 level of nasal polyp tissue was used as gold standard. Clinical characteristics were used to establish diagnostic models. The area under the receiver operating curve (AUC) was used to evaluate the diagnostic performance. The study was approved by the ethics board of the First Affiliated Hospital of Sun Yat-sen University ([2020] 302), and written informed consent was obtained from all subjects before inclusion.

Results

In total, 134 patients from China (training set) and 110 patients from Belgium (validation set) were included. The logistic regression (LR) model in predicting inflammatory endotype of CRSwNP showed the AUC of 83%, which was better than the diagnostic performance of machine learning models (AUC of 61.14%-82.42%), and single clinical variables. We developed a simplified scoring system based on LR model which shows similar diagnostic performance to the LR model (P = 0.6633).

Conclusion

The LR model in this diagnostic study provided greater accuracy in prediction of inflammatory endotype of CRSwNP than those obtained from the machine learning model and single clinical variable. This indicates great potential for the use of diagnostic model to facilitate inflammatory endotype evaluation when tissue cytokines are unable to be measured.

Endotypes of chronic rhinosinusitis based on inflammatory and remodeling factors

BACKGROUND

Previous studies on the endotyping of chronic rhinosinusitis (CRS) that were based on inflammatory factors have broadened our understanding of the disease. However, the endotype of CRS combined with inflammatory and remodeling features has not yet been clearly elucidated.

OBJECTIVE

We sought to identify the endotypes of patients with CRS according to inflammatory and remodeling factors.

METHODS

Forty-eight inflammatory and remodeling factors in the nasal mucosal tissues of 128 CRS patients and 24 control subjects from northern China were analyzed by Luminex, ELISA, and ImmunoCAP. Sixteen factors were used to perform the cluster analysis. The characteristics of each cluster were analyzed using correlation analysis and validated by immunofluorescence staining.

RESULTS

Patients were classified into 5 clusters. Clusters 1 and 2 showed non-type 2 signatures with low biomarker concentrations, except for IL-19 and IL-27. Cluster 3 involved a low type 2 endotype with the highest expression of neutrophil factors, such as granulocyte colony-stimulating factor, IL-8, and myeloperoxidase, and remodeling factors, such as matrix metalloproteinases and fibronectin. Cluster 4 exhibited moderate type 2 inflammation. Cluster 5 exhibited high type 2 inflammation, which was associated with relatively higher levels of neutrophil and remodeling factors. The proportion of CRS with nasal polyps, asthma, allergies, anosmia, aspirin sensitivity, and the recurrence of CRS increased from clusters 1 to 5.

CONCLUSION

Diverse inflammatory mechanisms result in distinct CRS endotypes and remodeling profiles. The explicit differentiation and accurate description of these endotypes will guide targeted treatment decisions.

Association of computed tomography scores to psychophysical measures of olfaction: A systematic review and meta-analysis

BACKGROUND

While various sinus computed tomography (CT) scoring systems have been proposed and used in the literature, no single system has been identified as superior. The strength of associations between CT scoring systems and measures of olfaction also remains unclear.

METHODS

A systematic review of PubMed, CINAHL, Scopus, and the Cochrane Library was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies that reported both CT scores and measures of olfaction in a cross-sectional manner were included.

RESULTS

A total of 37 studies were eligible for meta-analysis. Of 8035 patients with chronic rhinosinusitis, 55.6% were male patients and 53.2% had chronic rhinosinusitis with nasal polyps. Analysis by meta-regression was performed of Lund-Mackay (LM) versus Smell Identification Test-40 (SIT-40; 12 studies), Brief Smell Identification Test (BSIT; 10 studies), Sniffin' Sticks (SS; 10 studies), and Toyota & Takagi (T&T) olfactometry (four studies). A significant moderate association was found between LM and SIT-40 (R²  = 0.612, p < 0.001) and LM and SS (R²  = 0.612, p < 0.001). An association between LM and BSIT approached significance (R²  = 0.461, p = 0.054). No significant associations were noted between LM and T&T olfactometry and between LM and SS when stratified by nasal polyp status.

CONCLUSION

There is a significant moderate association of current CT scoring systems to SIT-40 and SS. Further research should focus on associations of objective measures of olfaction to CT scores of the nasal cavity, sinuses, and olfactory cleft, as well as other disease markers.

Association of cytokine profile with prior treatment failure and revision surgery in chronic rhinosinusitis

BACKGROUND

Inflammatory patterns in chronic rhinosinusitis (CRS) may predict disease severity, need for multiple sinus surgeries, and treatment response. This study analyzes nasal mucus inflammatory cytokine patterns in patients with (CRSwNP) and without (CRSsNP) nasal polyposis and their association with revision sinus surgery.

METHODS

A total of 319 CRS patients who underwent sinus surgery were included. Cytokines were quantified in intraoperative mucus specimens using a multiplex flow cytometric bead assay. Cytokine expression patterns in patients with 0, 1, and ≥2 previous surgeries were analyzed using Kruskal-Wallis and principal component (PC) regression analyses.

RESULTS

There were 122 (38%) patients with CRSsNP and 197 (62%) with CRSwNP. On univariate analysis, interleukin (IL)-1β, IL-6, IL-8, and IL-21 were associated with increasing number of sinus surgeries in CRSsNP, as were IL-2, IL-4, IL-5, IL-6, IL-9, IL-17A, and tumor necrosis factor (TNF)-α in CRSwNP. PC analysis with continuous Poisson regression in CRSwNP demonstrated that high IL-5 and IL-13 and low IL-1β, IL-12, and IL-21 were associated with more prior surgeries. In CRSsNP low IL-13 and high IL-5 and regulated-on-activation, normal T-cell-expressed and secreted (RANTES) were associated with more prior surgeries. Age remained a significant covariate in the full regression model for CRSsNP, but was nonsignificant in CRSwNP.

CONCLUSION

In CRSwNP, elevated IL-5 and IL-13 levels were higher at time of surgery in patients with more prior surgeries. Type 2 cytokines in CRSsNP demonstrated mixed associations with revision surgery. For both phenotypes, IL-10, IL-12, and IL-21 were consistently lower as number of prior surgeries increased, suggesting that treatment-resistant disease may be modulated by impairment in these signaling pathways.

Persistent discharge or edema after endoscopic sinus surgery in patients with chronic rhinosinusitis is associated with a type 1 or 3 endotype

BACKGROUND

Patients with chronic rhinosinusitis (CRS) may have persistence of polyps, discharge, or edema after endoscopic sinus surgery (ESS). Inflammation in CRS can be classified into three endotypes, with the presence of polyps associated with the type 2 endotype. Here, we evaluate the endotypic underpinnings of discharge or edema without polyps after ESS.

METHODS

At a visit 6-12 months post ESS, patients underwent endoscopy and completed the CRS-PRO and SNOT-22. Luminex analysis of middle meatal mucus obtained at that visit was performed for IFN-γ, ECP, and IL-17a. Type 1, 2, and 3 endotypes were defined as greater than the 90th percentile expression of each marker, respectively, in controls. Wilcoxon rank-sum and chi-squared tests were used to compare cytokine levels and endotype prevalence between those with and without endoscopic findings.

RESULTS

A total of 122 CRS patients completed a clinical exam (median: 8.2 months post ESS). Of the 122 patients, 107 did not have polyps on endoscopy. Of these 107 patients, 48 had discharge, 44 had edema, and 46 had neither discharge nor edema. Compared with those patients without any findings, patients with discharge or edema reported significantly worse severity as measured by CRS-PRO (10.5 vs. 7.0, p = 0.009; 12.0 vs. 7.0, p < 0.001; respectively), and had higher post-ESS IFN-γ, ECP, and IL-17a. Patients with discharge had higher prevalence of only T1 and T3 endotypes, while patients with edema had higher prevalence of only the T3 endotype.

CONCLUSIONS

Post-ESS discharge or edema in the absence of polyps was associated with higher patient-reported outcome severity and was more strongly associated with type 1 or 3 inflammation.

S100A8 enhances IL-1β production from nasal epithelial cells in eosinophilic chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis is classified into eosinophilic chronic rhinosinusitis (ECRS) and non-eosinophilic chronic rhinosinusitis (NECRS). ECRS is a refractory allergic disease involving a variety of immune and epithelial cells. S100A8 is a damage-associated molecular pattern that is closely related to allergic inflammation. However, the pathological implications of S100A8 in ECRS have not been clarified.

METHODS

We evaluated the role of S100A8 in the pathogenesis of ECRS. Gene expression profiles of nasal polyps obtained from patients with ECRS or NECRS were evaluated using RNA sequencing.

RESULTS

S100A8 was identified as a significantly upregulated gene in nasal polyps associated with ECRS. Immunohistochemistry consistently revealed intense S100A8 staining in nasal polyps from patients with ECRS. Human nasal epithelial cells expressed the receptor for advanced glycation end products and Toll-like receptor 4. Recombinant S100A8 protein induced interleukin-1β secretion in human nasal epithelial cells.

CONCLUSIONS

Our data demonstrate that S100A8 results in production of interleukin-1β in the nasal epithelium, which may be involved in the pathogenesis of ECRS.

[Expression and predictive value of type Ⅱ inflammatory cytokines in nasal secretion in eosinophilic chronic rhinosinusitis with nasal polyps]

Objective:To analyze the expression of type Ⅱ inflammatory-related cytokines in nasal secretions of patients with eosinophilic chronic rhinosinusitis with nasal polyps（ECRSwNP）, and to preliminarily explore the role of type Ⅱ inflammatory cytokines in nasal secretions in predicting ECRSwNP. Methods:A prospective analysis was made of 91 patients with CRSwNP who underwent endoscopic sinus surgery in Peking University Third Hospital from November 2020 to June 2021. All the selected patients had their SNOT-22 score, Lund-Mackay score and blood eosinophilia collected before surgery. Percentage and absolute value; the nasal secretions of patients were collected before operation, and enzyme-linked immunosorbent assay was used to detect the typeⅡinflammatory cytokines（IL-4, IL-5, IL-13, IL-25, IL-33, Eotaxin-3, periostin）, intraoperative nasal polyp tissue was collected for eosinophil count. According to the proportion of eosinophils in the tissue≥10%, they were divided into ECRSwNP group and nECRSwNP group. The clinical baseline data and type Ⅱ inflammatory cytokines were compared between the two groups, and the related factors of ECRSwNP were evaluated by univariate logistic regression analysis. The receiver operating characteristic（ROC） curve was used to evaluate the predictive potential of each clinical index. Results:The SNOT-22 score, Lund-Mackay score, blood eosinophil percentage and absolute value in the ECRSwNP group were higher than those in the nECRSwNP group（P<0.05）. In the nECRSwNP group（P<0.01）. Logistic regression analysis found that IL-5, Eotaxin-3 and blood eosinophil percentage were risk factors for ECRSwNP（P<0.05）. ROC analysis found that IL-5, Eotaxin-3 and blood eosinophil percentage had predictive diagnostic value（P<0.01）, among which blood eosinophil percentage had the greatest predictive value（AUC=0.756）. The prediction model composed of Eotaxin-3, SNOT-22 score, sinus CT Lund-Mackay score, blood eosinophil percentage and blood eosinophil absolute value had better prediction effect on ECRSwNP（AUC=0.873）. Conclusion:Type Ⅱ inflammatory cytokines IL-5 and Eotaxin-3 in nasal secretions may be involved as biomarkers for early diagnosis of ECRSwNP.

[Research progress of biomarkers in nasal secretions in endotypes diagnosis and clinical application of chronic rhinosinusitis]

With the development of studies on the endotypes of chronic rhinosinusitis （CRS） and the biomarkers of nasal secretions, the studies of CRS endotypes based on nasal secretion have become more abundant. This paper summarizes the endotypes classification of CRS, the collection methods of nasal secretion and the nasal secretion biomarkers related to the endotypes of CRS, in order to provide a reference for establishing the corresponding endotypes of CRS based on the nasal secretion biomarkers.

CRS-PRO and SNOT-22 correlations with type 2 inflammatory mediators in chronic rhinosinusitis

The 22-item Sino-Nasal Outcome Test (SNOT-22) and 12-item Patient Reported Outcomes in Chronic Rhinosinusitis (CRS-PRO) instrument are validated patient-reported outcomes measures in CRS. In this study we assess the correlation of these with type 2 (T2) biomarkers before and after endoscopic sinus surgery (ESS).

METHODS

Middle meatal mucus data were collected and the SNOT-22 and CRS-PRO were administered to 123 patients (71 CRS without nasal polyps [CRSsNP], 52 CRS with nasal polyps [CRSwNP]) with CRS before and 6 to 12 months after undergoing ESS. Interleukin (IL)-4, IL-5, IL-13, and eosinophilic cationic protein (ECP) were measured using a multiplexed bead assay and enzyme-linked immunoassay. Pre- and post-ESS SNOT-22 and CRS-PRO were compared with T2 biomarkers.

RESULTS

Before ESS neither PROM correlated with any biomarker. After ESS, CRS-PRO showed a correlation with 2 mediators (IL-5 and IL-13: p = 0.012 and 0.003, respectively) compared with none for the SNOT-22. For CRSwNP patients, pre-ESS CRS-PRO and SNOT-22 correlated with IL-4 (p = 0.04 for both). However, after ESS, CRS-PRO correlated with 3 biomarkers (IL-5, IL-13, and ECP: p = 0.02, 0.024, and 0.04, respectively) and SNOT-22 with 2 biomarkers (IL-5 and IL-13: p = 0.038 and 0.02, respectively). There were no significant relationships between any of the T2 biomarkers pre- or post-ESS among patients with CRSsNP. Exploratory analyses of the subdomains showed the SNOT-22 rhinologic and CRS-PRO rhinopsychologic subdomains correlated better with the T2 biomarkers. On individual item analysis, IL-13 correlated significantly post-ESS with 8 of 12 items on the CRS-PRO vs 6 of 22 items on the SNOT-22.

CONCLUSION

The CRS-PRO total score showed a significant correlation with T2 biomarkers especially when assessed post-ESS and among CRSwNP patients.

Characterization of Cytokines and Proliferation Marker Ki-67 in Chronic Rhinosinusitis with Recurring Nasal Polyps

Background: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammation of the mucosa of the nose and paranasal sinuses with the presence of polyps, affecting between 2.7% and 4.4% of the population. Cytokine analysis has become important in research on inflammatory mechanisms in CRSwNP. Therefore, our aim is to investigate the complex appearance, relative distribution, and interlinks of IL-1, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, and Ki-67 in CRSwNP. Methods: Samples of nasal polyps were obtained from 19 patients with previously diagnosed CRSwNP and the recurrence of polyps after previous surgeries. The control group consisted of samples from 17 otherwise healthy individuals with isolated nasal septum deviations. Tissues were stained for previously mentioned cytokines and Ki-67 immunohistochemically. Results: Polyp samples showed an increased presence of cytokines in subepithelial connective tissue and a decreased appearance in epithelium when compared to controls. There were several very strong, strong, and moderate correlations among factors. Conclusions: IL-6 strongly correlates with other cytokines as well as with the proliferation marker Ki-67, which suggests significant stimulation of this regulatory cytokine and its possible involvement in the pathogenesis of recurrent nasal polyps. IL-4, IL-7, IL-10, and IL-12 correlate with Ki-67, which suggests the possible involvement of these cytokines in tissue cell proliferation in the case of recurrent nasal polyps.

Levels of eicosanoids in nasal secretions associated with nasal polyp severity in chronic rhinosinusitis

Severe nasal polyposis and mucosal inflammation, in patients with chronic rhinosinusitis (CRS) may include a dysregulated eicosanoid profile, but a clinical role for eicosanoids in CRS with nasal polyps (NP; CRSwNP) remains to be elucidated. This study focused on assessing levels and clinical implications of inflammatory mediators in nasal secretions and urine from patients with different NP severity or Aspirin Exacerbated Respiratory Disease (AERD). Levels of leukotrienes E₄ and B₄, prostaglandins D₂ and E₂ as well as 15(S)-hydroxyeicosatetraenoic acid were measured with enzyme immunoassays and cytokines with magnetic bead immunoassays. Patients with CRSwNP were subdivided based on NP score; CRSwNP-low (NP score ≤ 4, n = 11) or CRSwNP-high (NP score ≥ 5, n = 32) and compared to CRS without polyps (CRSsNP, n = 12), CRSwNP-AERD (n = 11) and individuals without CRS (n = 25). Smell test score, fractional exhaled nitric oxide (FeNO), blood eosinophils and Sinonasal outcome test-22 were assessed as clinical markers. Leukotriene E₄, prostaglandin D₂ and 15(S)-hydroxyeicosatetraenoic acid in nasal secretions correlated with NP score. Nasal leukotriene E₄ also correlated with FeNO and smell test score, with highest levels found in CRSwNP-AERD. Levels of prostaglandin D₂ in nasal secretion as well as urinary levels of the prostaglandin D₂ metabolite 11β-prostaglandin F_2α differed between CRSNP-high and CRSwNP-low. Urinary 11β-prostaglandin F_2α was associated with asthma comorbidity whereas a similar association with prostaglandin D₂ in nasal secretions was not observed. In conclusion, subdividing patients based on NP severity in combination with analysis of eicosanoids in non-invasively collected nasal secretions, may have clinical implications when assessing CRS disease severity.

Utilization of Nasal Mucus to Investigate the Pathophysiology of Chronic Rhinosinusitis

BACKGROUND

Nasal mucus is proving to be a useful means by which to study the pathogenesis of chronic rhinosinusitis (CRS). Given the increase in publications examining nasal mucus and the lack of a review on this topic, we will focus on this noninvasive approach to studying CRS. Particular attention will be drawn towards inflammatory cytokines and biomarkers and their influence on disease severity.

METHODS

A literature review of papers published in English pertaining to nasal mucus was performed using the PubMed database. The search utilized combinations of the following keywords: sinusitis, polyps, sample collection, nasal mucus, or nasal secretion. Studies solely on acute or bacterial sinusitis, allergic rhinitis, or cystic fibrosis were not included.

RESULTS

A wide variety of materials and methods have been used to collect nasal mucus. Numerous assay types have been performed with the most common being ELISA, cytometric bead array, and proteomics. Most studies have focused on examining the levels of Th1/Th2 cytokines along with chemokines associated with type 2 immunity. Other factors identified include growth factors, senescence-associated proteins, complement, and antimicrobial defenses have also been identified. Nasal mucus cytokines have proven useful in cluster analysis and predicting postoperative improvement in Sino-nasal Outcome Test (SNOT-22) scores. One limitation of the use of nasal mucus is that some studies have suggested that nasal mucus does not always reflect the tissue microenvironment.

CONCLUSIONS

Nasal mucus represents a critical tool by which to examine the sinonasal microenvironment in a noninvasive manner. Unlike studies of tissue, it can be utilized in both surgically and medically managed patients and avoids the trauma of biopsies. However, studies are still needed to determine the most effective method for nasal mucus collection. Studies should also take care to confirm that nasal mucus markers do, in fact, reflect the levels of the product studied in the tissue.

Body Composition-Specific Asthma Phenotypes: Clinical Implications

Background: Previous studies have indicated the limitations of body mass index for defining disease phenotypes. The description of asthma phenotypes based on body composition (BC) has not been largely reported. Objective: To identify and characterize phenotypes based on BC parameters in patients with asthma. Methods: A study with two prospective observational cohorts analyzing adult patients with stable asthma (n = 541 for training and n = 179 for validation) was conducted. A body composition analysis was performed for the included patients. A cluster analysis was conducted by applying a 2-step process with stepwise discriminant analysis. Logistic regression models were used to evaluate the association between identified phenotypes and asthma exacerbations (AEs). The same algorithm for cluster analysis in the independent validation set was used to perform an external validation. Results: Three clusters had significantly different characteristics associated with asthma outcomes. An external validation identified the similarity of the participants in training and the validation set. In the training set, cluster Training (T) 1 (29.4%) was “patients with undernutrition”, cluster T2 (18.9%) was “intermediate level of nutrition with psychological dysfunction”, and cluster T3 (51.8%) was “patients with good nutrition”. Cluster T3 had a decreased risk of moderate-to-severe and severe AEs in the following year compared with the other two clusters. The most important BC-specific factors contributing to being accurately assigned to one of these three clusters were skeletal muscle mass and visceral fat area. Conclusion: We defined three distinct clusters of asthma patients, which had distinct clinical features and asthma outcomes. Our data reinforced the importance of evaluating BC to determining nutritional status in clinical practice.

Epidemiology of Chronic Rhinosinusitis: Prevalence and Risk Factors

Knowledge of chronic rhinosinusitis (CRS) epidemiology may directly impact patient care: aiding patient identification and establishing accurate diagnosis as well as informing treatment decisions. The objective of this review is to summarize the current evidence on the epidemiology of CRS, with a focus on prevalence and risk factors. Although the presence of either symptoms or objective findings alone have yielded CRS prevalence estimates of over 10%, the presence of both-consistent with guideline-based diagnostic criteria for CRS-has suggested that the true prevalence of CRS is consistently less than 5%, with approximately one-third of patients with CRS having nasal polyps, in epidemiologic studies from around the world. In comparison, the prevalence of CRS endotypes-pathophysiologic subclassification of CRS most commonly as related to type 2 or non-type 2 inflammation-has been found to vary significantly by region. The epidemiology of CRS is modified and ultimately determined by risk factors: genetic/hereditary, demographic, environmental, and imparted by predictive pre-/comorbid disease. The understanding of these epidemiologic relationships may help the provider to optimally identify and understand each individual's CRS disease process, thereby improving both diagnosis and treatment.

Current Insight into Treatment of Chronic Rhinosinusitis: Phenotypes, Endotypes and Implications for Targeted Therapeutics

Chronic rhinosinusitis (CRS) is characterized by persistent locoregional mucosal inflammation of the paranasal sinuses and upper airway that has substantial associated health care costs¹. Personalized approaches to care that incorporate use of molecular biomarkers, phenotypes and inflammatory endotypes is a major focus of research at this time, and the concurrent rise of targeted therapeutics and biologic therapies has the potential to rapidly advance care and improve outcomes. Recent findings suggest that improved understanding of CRS phenotypic and endotypic heterogeneity, and incorporation of these characteristics into clinical care pathways, may facilitate more effective selection of surgical and/or therapeutic interventions². Ultimately, these personalized approaches have the potential to target specific inflammatory pathways, increase efficacy, reduce costs, and limit side effects. This review summarizes recent advances in the identification and characterization of CRS phenotypes, endotypes, and biomarkers and reviews potential implications for targeted therapeutics.

Clinical and biological markers in disease and biologics to treat chronic rhinosinusitis

PURPOSE OF REVIEW

Chronic rhinosinusitis (CRS) is a heterogeneous disorder with diverse responses to conventional anti-inflammatory medical and surgical treatments. Even for the newly developed mAbs targeting type 2 (T2) reaction, a considerable number of patients with CRS with nasal polyps (CRSwNP) exhibited unsatisfying response. Identifying patients with a tendency to poor prognosis is critical for selecting targeted therapies to improve the treatment outcome. This review focuses on clinical and biological markers associated with prognosis of CRS patients under conventional medical and surgical treatments and provides an update summary of potential markers for T2 biologics.

RECENT FINDINGS

Allergic rhinitis, asthma, prior sinus surgery, nasal polyps, tissue eosinophilia and neutrophilia, blood eosinophilia and high levels of Charcot-Leyden crystal, cystatin SN, chemokine (C-C motif) ligand 17, macrophage inflammatory protein-1β and interleukin (IL)-5 in nasal secretions have been associated with poor prognosis in CRS patients under conventional medical and surgical treatments. Blood eosinophil level might be a biomarker for anti-IL-5 (mepolizumab) and anti-IL-5R (benralizumab) biologic in patients with refractory CRSwNP.

SUMMARY

Several clinical and biological markers have been associated with poor response to conventional treatments in CRS patients; however, majority of them should be verified by large-scale multicentre studies. More efforts are needed to identify biomarkers for biologics.

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.

In vitro and in vivo evaluation of probiotic properties of Corynebacterium accolens isolated from the human nasal cavity

Corynebacterium accolens strains are increasingly recognized as beneficial bacteria that can confer a health benefit on the host. In the current study, the probiotic potential of three C. accolens strains, C779, C781 and C787 derived from a healthy human nasal cavity were investigated. These strains were examined for their adhesion to HNECs, competition with Staphylococcus aureus for adhesion, toxicity, induction of IL-6, antibiotic susceptibility and the presence of antibiotic resistance and virulence genes. Furthermore, the safety and efficacy of strains were evaluated in vivo using Caenorhabditis elegans. The adhesion capacity of C. accolens to HNECs was strain-dependent. Highest adhesion was observed for strain C781. None of the C. accolens strains tested caused cell lysis. All strains were able to outcompete S. aureus for cell adhesion and caused a significant decrease of IL-6 production by HNECs co-exposed to S. aureus when compared to the control groups. All strains were sensitive or showed intermediate sensitivity to 10 different antibiotics. Whole Genome Sequence analysis showed C. accolens C781 and C787 did not possess antibiotic resistance genes whereas strain C779 harboured 5 genes associated with resistance to Aminoglycoside, Chloramphenicol and Erythromycin. In addition, no virulence genes were detected in any of the 3 strains. Moreover, the tested strains had no detrimental effect on worm survival and induced protection from S. aureus-mediated infection. Taken all together, C. accolens strains, C781 and C787 displayed probiotic potential and hold promise for use in clinical applications for combating dysbiosis in chronic rhinosinusitis.

Highlights in the advances of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a complex upper airway inflammatory disease with a broad spectrum of clinical variants. As our understanding of the disease pathophysiology evolves, so too does our philosophy towards the approach and management of CRS. Endotyping is gaining favour over phenotype-based classifications, owing to its potential in prognosticating disease severity and delivering precision treatment. Endotyping is especially useful in challenging CRS with nasal polyposis cases, for whom novel treatment options such as biologicals are now available. The latest European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS2020) reflects these changes with updated rhinosinusitis classifications and new integrated care pathways. With the coronavirus disease 2019 (COVID-19) pandemic, physicians and rhinologists have to balance the responsibility of managing their patients' upper airway while adequately protecting themselves from droplet and aerosol transmission. This review summarises the key updates from EPOS2020, endotype-based classification and biomarkers. The role of biologicals in CRS and the lessons we can draw from their use in severe asthma will be examined. Finally, the principles of CRS management during COVID-19 will also be discussed.

Epithelial-Cell-Derived Extracellular Vesicles in Pathophysiology of Epithelial Injury and Repair in Chronic Rhinosinusitis: Connecting Immunology in Research Lab to Biomarkers in Clinics

Epithelial barrier disruption and failure of epithelial repair by aberrant epithelial-mesenchymal transition (EMT)-induced basal cells observed in nasal mucosa of chronic rhinosinusitis (CRS) are speculated to play important roles in disease pathophysiology. Microparticles (MPs) are a type of extracellular vesicle (EV) released by budding or shedding from the plasma membrane of activated or apoptotic cells. MPs are detected in nasal lavage fluids (NLFs) and are now receiving attention as potential biomarkers to evaluate the degree of activation of immune cells and injury of structural cells in nasal mucosa of subjects with sinus disease. There are three types of epithelial-cell-derived MPs, which are defined by the expression of different epithelial specific markers on their surface: EpCAM, E-cadherin, and integrin β6 (ITGB6). When these markers are on MPs that are also carrying canonical EMT/mesenchymal markers (Snail (SNAI1); Slug (SNAI2); alpha-smooth muscle actin (αSMA, ACTA2)) or pro- and anti-coagulant molecules (tissue factor (TF); tissue plasminogen activator (tPA); plasminogen activator inhibitor-1 (PAI-1)), they provide insight as to the roles of epithelial activation for EMT or regulation of coagulation in the underlying disease. In this review, we discuss the potential of epithelial MPs as research tools to evaluate status of nasal mucosae of CRS patients in the lab, as well as biomarkers for management and treatment of CRS in the clinic.

Pathophysiological and Clinical Aspects of Chronic Rhinosinusitis: Current Concepts

Adult chronic rhinosinusitis (CRS) is a chronic inflammation of the mucosa of the nose and paranasal sinuses. According to the latest EPOS guidelines CRS should be regarded as primary or secondary with distinction between diffuse and localized disease. Further pathophysiologic research identified different inflammatory patterns leading to the term “endotyping of CRS.” The primary focus of endotyping is to define a dominant inflammatory type allowing for better orientation of therapy. The current approach proposes the differentiation between type 2 (eosinophilic) and non-type 2 inflammatory responses. In this review pathophysiological concepts of CRS will be discussed, focusing on the different inflammatory endotypes of T cells with special attention to the eosinophilic type 2 inflammatory response. The contribution of innate and adaptive immune system responses is presented. The possibility of endotyping based on sinonasal secretions sampling is brought to attention because it is indicative of corticosteroid responsiveness and available to most ENT surgeons. Furthermore, the clinical aspects of the three distinct phenotypes are analyzed in view of their characteristics, the related endoscopic findings, typical radiological imaging, histopathology findings, their relation toward allergy and obvious therapeutical implications. This overview will enable clinicians to relate pathophysiological patterns with clinical observations by explaining the different inflammatory mechanisms, hence providing a better understanding of therapy.

Management of Chronic Rhinosinusitis with Nasal Polyposis in the Era of Biologics

Purpose of Review

Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a phenotypic designation of the broader condition of chronic rhinosinusitis. The advent of targeted biologics has shown promise in targeting different aspects of the inflammatory pathway, yet there remains a lack of consensus on the correct timing and use of these medications. This review seeks to provide a concise update of the available literature on the pathophysiology of CRSwNP, the evolution and cost utility of biologics as it pertains to management of patients with CRSwNP, and evidence for each available biologic and its use in CRSwNP.

Recent Findings

There are two biologics with FDA approval for use in CRSwNP: dupilumab and omalizumab. Recent clinical trials of other biologic therapies targeting type 2 inflammatory pathways have also demonstrated efficacy both in symptom scores and nasal polyp reduction. However, studies have questioned the cost utility of these medications compared to other interventions. Furthermore, timing of use with respect to other interventions including surgery remains challenging.

Characterization of Cytokines and Proliferation Marker Ki67 in Chronic Rhinosinusitis with Nasal Polyps: A Pilot Study

Background and Objectives: Chronic rhinosinusitis (CRS) is a condition that affects as much as 10.9% of the population and, along with presence of nasal polyps, is associated with significant morbidity and decreased quality of life. Studies on molecular pathways that have been activated in nasal polyp tissue are mainly based on cytokine concentration detection. Therefore, our aim is to investigate the complex appearance, relative distribution and interlinks of IL-1, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12 and Ki 67 in chronic rhinosinusitis with nasal polyps (CRSwNP) affected human nasal mucosa. Materials and Methods: Samples of nasal polyps were obtained from 12 patients with previously diagnosed CRSwNP and no prior surgery. Control group consisted of samples from 17 otherwise healthy individuals with isolated nasal septum deviation. Tissues were stained for IL-1, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12 and Ki67 immunohistochemically. Non-parametric statistic, Mann–Whitney U test and Spearman’s rank correlation coefficient were used. Results: All factors, except connective tissue cytokine IL-10 and proliferation marker Ki-67, had increased presence in connective tissue and decreased presence in epithelium of nasal polyps when compared to controls. Very strong and strong positive correlations between factors were observed. Conclusions: Decreased appearance of IL-1α, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12 positive structures in the nasal epithelium with selective increase of IL-1α and IL-12 in nasal subepithelial connective tissue characterize the cytokine endotype with dysfunctional epithelial barrier and local stimulation of immune response in the connective tissue in case of chronic rhinosinusitis with polyps. Decrease of IL-6 in both—epithelium and connective tissue with strong correlation between it and IL-7 and IL-10 in connective tissue suggests significant stimulation of this regulatory cytokine and, possibly, the important role in pathogenesis of the development in nasal polyps. Correlations between Ki67 and cytokines indicate possible involvement of IL-4, IL-7 and IL-12 in regulation of cellular proliferation.

Novel therapeutic approaches targeting endotypes of severe airway disease

Introduction: Severe asthma and chronic rhinosinusitis (CRS), with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP), are heterogeneous diseases characterized by different mechanistic pathways (endotypes) and variable clinical presentations (phenotypes).Areas covered: This review provides the clinician with an overview of the prevalence and clinical impact of severe chronic upper and lower airways disease and suggests a novel therapeutic approach with biological agents with possible biomarkers. To select relevant literature for inclusion in this review, we conducted a literature search using the PubMed database, using terms 'severe airways disease' AND 'endotype' AND 'treatment.' The literature review was performed for publication years 2010-2020, restricting the articles to humans and English language publications.Expert opinion: The coronavirus disease (COVID-19) pandemic has brought forth many challenges for patients with severe airway disease and healthcare practitioners involved in care. These patients could have an increased risk of developing severe SARS-CoV-2 disease, although treatment with biologics is not associated with a worse prognosis. Eosinopenia on hospital admission plays a key role as a diagnostic and prognostic biomarker.

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.

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.

Olfactory cleft mucus inflammatory proteins in CRS: a case-control study

BACKGROUND

Multiple hypotheses are evolving that suggest several, potentially overlapping etiologies for olfactory dysfunction (OD) in chronic rhinosinusitis (CRS). Understanding inflammatory cytokine profiles of the olfactory cleft (OC) and their association with olfactory function is foundational for future clinical care and research.

METHODS

This cross-sectional, case-control study evaluates associations among OC mucus inflammatory proteins, psychophysical olfactory testing, and computed tomography (CT) analysis of the OC and sinuses. Normative reference intervals were determined for each protein and odds ratios (ORs) were used to compare proportions of altered expression between CRS without nasal polyposis (CRSsNP) and CRS without nasal polyposis (CRSwNP).

RESULTS

Case subjects with CRS (n = 151) and controls (n = 74) were evaluated. A majority of OC proteins tested were found within detectable ranges for cases and controls. The CRS cohort had significantly higher concentrations for 23 of 26 proteins. CRS cases with abnormal levels of C-C motif chemokine ligand 2 (CCL2), CCL3, interleukin 5 (IL5), IL10, and IL13 associated with greater olfactory deficits. The prevalence of elevated IL5 and IL13 in anosmic patients was 64.6% and 62.5%, respectively (p < 0.004). CRS cases with the highest odds of elevated expression in CRSwNP were IL5 (OR = 10.83) and IL13 (OR = 8.36). However, both IL5 and IL13 were still elevated in approximately 14% of CRSsNP patients. The highest magnitude of correlation between the total percent of OC opacification was found to be with IL5 (r = 0.543; p < 0.001), whereas other moderate correlations were noted with immunoglobulin E (IgE), IL10, and IL13.

CONCLUSION

This study confirmed that OC inflammatory proteins vary both by disease phenotype and in their association with OD. Type 2 inflammatory mediators are increased in CRS, especially within the CRSwNP group. However, a substantial proportion of CRSsNP also express type 2 inflammatory mediators. Further research is necessary to understand the complex roles OC mucous inflammatory proteins might play in defining endotype and in impacting CRS-related OD. ©2021 ARSAAOA, LLC.

Association of Mast Cell Burden and TIM-3 Expression with Recalcitrant Chronic Rhinosinusitis with Nasal Polyps

OBJECTIVES

Previous work showed that higher polyp mast cell load correlated with worse postoperative endoscopic appearance in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Polyp epithelial mast cells showed increased expression of T-cell/transmembrane immunoglobulin and mucin domain protein 3 (TIM-3), a receptor that promotes mast cell activation and cytokine production. In this study, CRSwNP patients were followed post-operatively to investigate whether mast cell burden or TIM-3 expression among mast cells can predict recalcitrant disease.

METHODS

Nasal polyp specimens were obtained via functional endoscopic sinus surgery (FESS) and separated into epithelial and stromal layers via enzymatic digestion. Mast cells and TIM-3-expressing mast cells were identified via flow cytometry. Mann-Whitney U tests and Cox proportional hazard models assessed whether mast cell burden and TIM-3 expression were associated with clinical outcomes, including earlier recurrence of polypoid edema and need for treatment with steroids.

RESULTS

Twenty-three patients with CRSwNP were studied and followed for 6 months after undergoing FESS. Higher mast cell levels were associated with earlier recurrence of polypoid edema: epithelial HR = 1.283 (P = .02), stromal HR = 1.103 (P = .02). Percent of mast cells expressing TIM-3 in epithelial or stromal layers was not significantly associated with earlier recurrence of polypoid edema. Mast cell burden and TIM-3+ expression were not significantly associated with need for future treatment with steroids post-FESS.

CONCLUSIONS

Mast cell load in polyp epithelium and stroma may predict a more refractory postoperative course for CRSwNP patients. The role of TIM-3 in the chronic inflammatory state seen in CRSwNP remains unclear.

Endotyping chronic rhinosinusitis based on olfactory cleft mucus biomarkers

BACKGROUND

Although chronic rhinosinusitis (CRS) is considered the most treatable form of olfactory dysfunction, there has been relatively little clinical attention focused on assessing endotypes as they pertain to olfactory loss.

OBJECTIVES

The goal of this study was to explore inflammatory endotypes in CRS using an unsupervised cluster analysis of olfactory cleft (OC) biomarkers in a phenotype-free approach.

METHODS

Patients with CRS were prospectively recruited and psychophysical olfactory testing, Questionnaire of Olfactory Dysfunction (QOD-NS), and bilateral OC endoscopy were obtained. Mucus was collected from the OC and evaluated for 26 biomarkers using principal component analysis. Cluster analysis was performed using only OC biomarkers and differences in olfactory measures were compared across clusters.

RESULTS

A total of 198 subjects (128 with CRS and 70 controls) were evaluated. Evaluation of OC biomarkers indicated 6 principal components, explaining 69.50% of the variance, with type 2, mixed type 1/T_h17-cell, growth factor, and neutrophil chemoattractant inflammatory signatures. A total of 10 clusters were identified that differed significantly in frequency of controls, and subjects with CRS with nasal polyps, and subjects with CRS without nasal polyps across the clusters (likelihood ratio test, χ₁₈²=178.64; P < .001). Olfactory measures differed significantly across clusters, including olfactory testing, QOD-NS, and OC endoscopy (P < .001 for all).

CONCLUSIONS

Clustering based solely on OC biomarkers can organize patients into clinically meaningful endotypes that discriminate between subjects with CRS and controls. Validation studies are necessary to confirm these findings and further refine olfactory endotypes.

Elevated mucus interleukin-17A levels are associated with increased prior sinus surgery for chronic rhinosinusitis

BACKGROUND

Recent advances in molecular biology have enabled the identification of potential inflammatory endotypes of chronic rhinosinusitis (CRS), with prior work suggesting differential short-term surgical outcome trajectories based on cytokine signatures. However, there is a paucity of data assessing long-term treatment failure and need for revision surgery based on inflammatory biomarkers.

METHODS

Retrospective analysis of prospectively collected cross-sectional data from 231 patients electing surgical therapy for CRS. Intraoperative mucus specimens were quantitatively sampled for inflammatory cytokines using a multiplex flow cytometric bead assay. Univariate Spearman correlations between cytokine levels and prior number of surgeries were assessed. A stepwise adjusted multivariate Poisson regression analysis was used to model patient-reported prior sinus surgery counts as a function of cytokine levels.

RESULTS

Several cytokines (interleukin [IL]-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, IL-17A, tumor necrosis factor α [TNF-α], interferon γ [IFN-γ], and eotaxin) demonstrated significant positive correlations with number of prior surgeries. However, only higher IL-17A levels were independently associated with a higher number of prior sinus surgeries (β = 0.345, p = 0.0003) after adjusting for the significant covariates of age (β = 0.018, p = 0.0036), Lund-Mackay score (β = -0.046, p = 0.02), history of aspirin-exacerbated respiratory disease (β = 1.01, p < 0.0001) and allergic fungal rhinosinusitis (β = 1.08, p < 0.0001). Higher levels of regulated on activation, normal T-cell expressed and secreted (RANTES) were conversely associated with a lower number of prior surgeries (β = -0.17, p = 0.048).

CONCLUSION

An IL-17A-predominant cytokine profile is linked to an increased number of prior sinus surgeries. Thus, type 3 inflammatory markers may indicate a particularly difficult-to-treat, recalcitrant CRS endotype.

Advances in the Knowledge of the Underlying Airway Remodeling Mechanisms in Chronic Rhinosinusitis Based on the Endotypes: A Review

Chronic rhinosinusitis (CRS) is a chronic inflammatory condition of the nasal and paranasal sinus mucosa that affects up to 10% of the population worldwide. CRS is the most representative disease of the upper respiratory tract where airway remodeling occurs, including epithelial damage, thickening of the basement membrane, fibrosis, goblet cell hyperplasia, subepithelial edema, and osteitis. CRS is divided into two phenotypes according to the presence or absence of nasal polyps: CRS with nasal polyp (CRSwNP) and CRS without nasal polyps (CRSsNP). Based on the underlying pathophysiologic mechanism, CRS is also classified as eosinophilic CRS and non-eosinophilic CRS, owing to Type 2 T helper (Th2)-based inflammation and Type 1 T helper (Th1)/Type 17 T helper (Th17) skewed immune response, respectively. Differences in tissue remodeling in CRS are suggested to be based on the clinical phenotype and endotypes; this is because fibrosis is prominent in CRSsNP, whereas edematous changes occur in CRSwNP, especially in the eosinophilic type. This review aims to summarize the latest information on the different mechanisms of airway remodeling in CRS according to distinct endotypes.

[Neutrophil extracellular traps in the pathogenesis of chronic rhinosinusitis]

The review presents the current understanding of the pathogenesis of chronic rhinosinusitis. The causes of damage to the mucous membrane of the paranasal sinuses are most often the result of a combination of immunological, infectious and anatomical factors. This indicates the need for a multidisciplinary approach to the study of the pathogenesis of this pathology. There is no single universally recognized classification of chronic rhinosinusitis, which takes into account histological and immunological changes in the mucous membrane of the paranasal sinuses. The discovery of the mechanism of completion of the life cycle of neutrophils - the formation of a neutrophil extracellular trap or NETosis, different from necrosis and apoptosis, opened up new prospects in the study of the pathogenesis of inflammatory processes, including rhinosinusitis. Neutrophil extracellular traps reduce the permeability of the epithelial barrier in the mucous membrane of the paranasal sinuses. This determines their possible role in the etiopathogenesis of rhinosinusitis. In recent years, more and more attention has been paid to the feasibility, effectiveness and safety of therapy that affects the immune component of the inflammatory process, including NETosis. The data obtained in the study of extracellular traps can be used in clinical practice. It is neutrophil extracellular traps that can become a potential target in the treatment of patients with chronic rhinosinusitis.

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.