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

Multi-omics integration and machine learning identify and validate neutrophil extracellular trap-associated gene signatures in chronic rhinosinusitis with nasal polyps

This study aimed to explore the molecular characteristics of neutrophil extracellular traps (NETs) in chronic rhinosinusitis with nasal polyps (CRSwNP). Differentially expressed gene analysis, weighted gene co-expression network analysis, and machine learning algorithms identified three core NETs-associated genes: CXCR4, CYBB, and PTAFR, which were significantly upregulated in CRSwNP patients. The diagnostic performance of these genes was evaluated using receiver operating characteristic (ROC) curves, and their clinical relevance was validated using multicenter data. Immune infiltration analysis showed strong correlations between these genes and neutrophil and immune cell infiltration. Single-cell RNA sequencing demonstrated that these genes were predominantly expressed in myeloid and immune cells and exhibited dynamic changes during disease progression. These genes may contribute to CRSwNP pathogenesis through IL-17 signaling and metabolism-related pathways. This study identifies novel biomarkers and therapeutic targets for precise diagnosis and personalized treatment of CRSwNP.

Epithelial cell dynamics: Key drivers of type 2 inflammation in eosinophilic chronic rhinosinusitis

Sinonasal mucosal epithelial cells act not only as a physical barrier, but also as dynamic regulators of immune responses through innate and acquired immunity. These cells play a key role in detecting environmental stimuli, such as pathogens, allergens, and pollutants, and in initiating the inflammatory cascade that shapes the overall immune response. By releasing cytokines, such as interleukin (IL)-25 and IL-33, and thymic stromal lymphopoietin, epithelial cells interact with immune cells and promote type 2 inflammation. The pathogenesis of eosinophilic chronic rhinosinusitis (ECRS), which is driven by type 2 inflammation, is heterogeneous. While immune cells have traditionally been considered to be central to the disease pathogenesis, emerging evidence has indicated the critical role of epithelial cells. Furthermore, novel biologics targeting the IL-4/IL-13 signaling pathway have shown potential in alleviating epithelial dysfunction and inflammation. Eosinophilic mucins that accumulate in the sinuses impair mucociliary function, and especially eosinophil extracellular trap cell death (EETosis) stimulate epithelial cells and amplify eosinophilic inflammation. Eosinophilic mucin formation has been shown to significantly increase viscosity through EETosis, and novel biologics targeting the IL-5 signaling pathway hold promise for effectively mitigating this process. To develop targeted interventions, it is important to explore the role of epithelial subpopulations, such as basal cells and tuft cells, in maintaining the balance between tissue repair and chronic inflammation. Single-cell transcriptomics and spatial transcriptomics technologies have provided significant insights into the complexity of epithelial cell-derived inflammation in ECRS. The heterogeneity of the pathogenesis of CRS with nasal polyps and ECRS across patient populations complicates the development of universal therapies, underscoring the need for stratified medicine approaches. Potential future therapeutic strategies include the restoration of epithelial integrity and immune balance by disrupting aberrant crosstalk between epithelial and immune cells, particularly in patients unresponsive to current treatments.

Classification of chronic rhinosinusitis in Taiwan: A comprehensive analysis based on European Position Paper on rhinosinusitis and nasal polyps (EPOS) 2020

BACKGROUND

Chronic rhinosinusitis (CRS) is characterized by heterogeneous clinical presentations and underlying pathophysiology. The European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS) 2020 introduced a new classification system categorizing CRS, moving away from with (CRSwNP) and without polyps (CRSsNP). This study applies the EPOS 2020 framework to categorize CRS patients in Taiwan, focusing on eosinophilic CRS (eCRS) and its clinical implications in this population.

METHODS

A retrospective cross-sectional study analyzed medical records of CRS patients who underwent endoscopic sinus surgery at a Taiwanese medical center from January 1 to December 31, 2023. Patients were classified per EPOS 2020 criteria using clinical history, nasal endoscopy, and CT scans. Demographic data, symptom severity (Sino-Nasal Outcome Test, SNOT-22), olfactory function (Taiwan Smell Identification Test, TWSIT), and inflammatory markers (blood eosinophil count, IgE) were assessed.

RESULTS

Of the cohort (n = 335), 69.8 % were classified as primary CRS, with eCRS accounting for 33.4 % of cases. Among CRSwNP patients, eCRS prevalence was 56.2 %, compared to 19.0 % in CRSsNP patients. eCRS patients exhibited significantly higher eosinophil counts, CT Lund-Mackay scores, and worse olfactory function compared to non-eCRS counterparts (p < 0.01).

CONCLUSIONS

This study underscores the predominance of eCRS among CRS patients in Taiwan and its association with severe disease burden, particularly in CRSwNP. The findings support the utility of EPOS 2020 in characterizing CRS phenotypes and guiding personalized treatment strategies. This research contributes valuable insights into CRS epidemiology in Asia, advocating for further exploration into regional variations and therapeutic approaches.

Allergic Fungal Rhinosinusitis and Eosinophilic Chronic Rhinosinusitis Have Different Phenotypes in Japan

BACKGROUND

Allergic fungal rhinosinusitis (AFRS) is a subtype of chronic rhinosinusitis driven by Types 1 and 3 allergies to fungi. In Japan, it is relatively rare and characterized by prominent eosinophilic infiltration of the sinonasal mucosa, together with eosinophilic mucin containing scattered fungi in the sinus cavity. Eosinophilic chronic rhinosinusitis (eCRS) involves similar eosinophilic infiltration and shares some clinical features with AFRS. However, the clinical differences between eCRS and AFRS remain to be fully elucidated. The aim of this study was to clarify the phenotypes of eCRS and AFRS.

METHODS

This multicenter retrospective study enrolled patients with AFRS and eCRS and compared their clinical parameters. A cluster analysis was conducted to determine the phenotypes of the two diseases.

RESULTS

AFRS patients had a younger age of onset and exhibited milder computed tomography and nasal polyp scores than eCRS patients. Total IgE was significantly higher in AFRS patients than in eCRS patients, while mucosal eosinophil counts were similar. Olfactory disturbances were significantly less severe in AFRS patients compared with eCRS patients. The cluster analysis revealed three phenotypes for AFRS: one that was distinct and independent from eCRS, representing the more classically described AFRS patients, and more the other two that shared characteristics with eCRS.

CONCLUSIONS

AFRS exhibits unique clinical features compared with eCRS. Cluster analysis identified three distinct AFRS phenotypes characterized by CT findings, eosinophilic inflammation, and specific IgE levels against inhaled antigens. These findings underscore the importance of differential diagnosis and personalized treatment strategies for AFRS and eCRS.

Exploring the comorbidity association and biological mechanisms of chronic rhinosinusitis and chronic obstructive pulmonary disease

Although chronic rhinosinusitis (CRS) and chronic obstructive pulmonary disease (COPD) are both common chronic inflammatory diseases, the interaction between their comorbidities remains poorly understood within the unified airway disease framework. This study, for the first time, integrated multi-omics analysis and large-scale epidemiological data to explore their common mechanisms and clinical significance. The NHANES database was used for analysis, and multivariate logistic regression was employed to assess the comorbidity risk of CRS and COPD. Machine-learning models (glmnet, ranger, and xgboost) were used to analyze the NHANES data to determine the best model. Subsequently, Mendelian randomization(MR) was applied to explore relevant associations. Additionally, CRS and COPD datasets from GEO were further analyzed to identify potential targets. The NHANES analysis showed a significant association between CRS and COPD, with MR results indicating that CRS significantly increased the risk of COPD. Multi-omics integration revealed that C3 and CD163 are core targets in CRS/COPD patients. The ranger model was identified as the most suitable in this study. This study provides new evidence that CRS is an independent risk factor for COPD and establishes a unified airway mechanism centered on C3-CD163-mediated inflammation. These findings advance the "one airway, one disease" paradigm and support a dual-target therapeutic strategy.

Effects of inflammatory endotypes on disease trajectory in chronic rhinosinusitis with nasal polyps

BACKGROUND

Although phenotypic features have traditionally guided treatment in chronic rhinosinusitis, recent research has favored categorization on the basis of inflammatory endotype. However, the impact of endotypic differeces on clinical outcomes remains largely unknown.

OBJECTIVE

We sought to compare disease trajectory, primarily time-to-polyp recurrence, between chronic rhinosinusitis with nasal polyp (CRSwNP) endotypes.

METHODS

Samples were obtained from patients with CRSwNP undergoing surgery between 2015 and 2023, and cytokine levels were measured using a multiplex bead assay. Principal-component analysis followed by hierarchical cluster analysis was used to identify endotype clusters. Clinical outcomes were subsequently compared between clusters.

RESULTS

Six CRSwNP disease clusters were identified among the 269 included patients. Cluster 1 (46.5%) was characterized by relatively low inflammation. Cluster 4 (13.3%) and cluster 6 (7.1%) also exhibited low inflammation but with elevated levels of IL-12/IL-21 and CCL5, respectively. Cluster 2 (4.5%) represented a mixed type 1/3 inflammatory endotype (IFN-γHigh/IL-4High/IL-17AHigh), and cluster 3 (10.0%) was characterized by an innate, proinflammatory response (IL-1βHigh/IL-6High/IL-8High). Cluster 5 (18.9%) exhibited type 2-dominant inflammation (IL-5High/IL-9High/IL-13High). When comparing disease trajectory, cluster 2 (IFN-γHigh/IL-4High/IL-17AHigh) and cluster 4 (IL-12High/IL-21High) had the shortest time-to-polyp recurrence, whereas cluster 3 (IL-1βHigh/IL-6High/IL-8High) demonstrated the longest time-to-recurrence (P < .001). Time-to-oral steroid course (P = .13) and time-to-biologic therapy (P = .43) were similar across clusters.

CONCLUSIONS

The study highlights the heterogeneous nature of CRSwNP and differences in disease trajectory between endotypes, notably that patients with mixed type 1 and type 3 inflammation demonstrate more recalcitrant disease. These findings suggest that therapies beyond traditional type 2 inflammation treatments may be needed to effectively reduce CRSwNP disease recurrence.

Signaling lymphocytic activation molecule family 8 disrupts epithelial barrier in chronic rhinosinusitis with nasal polyps through M1 macrophage polarization

BACKGROUND

Recent studies reveal that M1 macrophages accumulate predominantly in noneosinophilic chronic rhinosinusitis with nasal polyps (neCRSwNP). However, the precise mechanisms regulating M1 macrophages and their impact on the epithelial barrier remain unclear.

OBJECTIVE

To investigate the expression and regulatory role of signaling lymphocytic activation molecule family (SLAMF)8, a molecule exclusively expressed in myeloid cells, in M1 macrophage polarization and its potential contribution to neCRSwNP development.

METHODS

We evaluated SLAMF8 expression and its correlation with clinical variables using real-time quantitative polymerase chain reaction and Western blot in sinonasal mucosa samples from CRSwNP and control subjects. Immunofluorescence staining confirmed the co-expression of SLAMF8 with macrophages. After SLAMF8 knockdown, we explored the influence on macrophage M1 polarization and the effect on epithelial-mesenchymal transition (EMT) process and tight junction integrity in epithelial cells through an indirect co-culture system of M1 macrophages with human nasal epithelial cells.

RESULTS

SLAMF8 was highly expressed on M1 macrophages in polyp tissues, notably in neCRSwNP, and correlated with disease severity indices only in neCRSwNP. SLAMF8 knockdown in THP-1 cells reduced M1 macrophage markers (CD86, iNOS, and NLRP3) and decreased secretion of inflammatory cytokines (interleukin-1 beta, interleukin-6, and tumor necrosis factor alpha). Co-culture with M1 macrophage supernatant after SLAMF8 knockdown enhanced epithelial viability, reduced EMT and apoptosis, and up-regulated tight junction markers, occludin and claudin-4, in nasal epithelial cells.

CONCLUSION

SLAMF8 elevation correlates with the EMT, epithelial tight junction, and disease severity in neCRSwNP. SLAMF8 up-regulation promotes M1 macrophage polarization, which facilitates EMT and impairs nasal epithelial barrier function. SLAMF8 may represent a novel therapeutic target for neCRSwNP.

SLC27A2 marks lipid peroxidation in nasal epithelial cells driven by type 2 inflammation in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by persistent inflammation and epithelial cell dysfunction, but the underlying molecular mechanisms remain poorly understood. Here we show that dysregulated lipid metabolism and increased lipid peroxidation in nasal polyp epithelial cells contribute to the pathogenesis of CRSwNP. Integrated analysis of bulk and single-cell RNA sequencing data reveals upregulation of SLC27A2/FATP2 in nasal polyp epithelium, which correlates with increased lipid peroxidation. SLC27A2-positive epithelial cells exhibit enriched expression of lipid peroxidation pathway genes and enhanced responsiveness to IL-4/IL-13 signaling from Th2 and ILC2 cells. Inhibition of IL-4/IL-13 signaling by dupilumab reduces expression of lipid peroxidation-associated genes, including SLC27A2. In eosinophilic CRSwNP, SLC27A2 expression correlates with disease severity. Pharmacological inhibition of FATP2 in air-liquid interface cultures of nasal epithelial cells decreases expression of IL13RA1 and lipid peroxidation-related genes. Our findings identify FATP2-mediated lipid peroxidation as a key driver of epithelial dysfunction and inflammation in CRSwNP, providing new insights into disease mechanisms and potential therapeutic targets.

Analysis of human neutrophils from nasal polyps by single-cell RNA sequencing reveals roles of neutrophils in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 (T2) inflammation. Recent studies, including our own, suggest that neutrophils are also elevated in T2 nasal polyps (NP) and that elevated neutrophils display an activated phenotype. However, the actual roles of neutrophils in NP pathogenesis in T2 CRSwNP are still largely unclear.

OBJECTIVE

To reveal the roles and heterogeneity of neutrophils in NP tissue by single-cell RNA sequencing analysis.

METHODS

We developed a novel microwell-based single-cell RNA sequencing assay using granulocyte-enriched samples from 5 control sinus tissues, 5 NP tissues and patient-matched peripheral blood (PB) samples. This approach allowed for examination of differential expression of genes in NP neutrophils by the Benjamini-Hochberg algorithm and predicted the overall function of NP neutrophils by pathway and Gene Ontology enrichment analyses.

RESULTS

After performing all quality control steps, we successfully detected neutrophils. We identified 333 downregulated and 128 upregulated genes in NP neutrophils (1,151 cells) compared with all PB neutrophils (13,591 cells) (>1.5-fold, q < 0.05) and found commonly dysregulated genes in NP neutrophils compared with both all PB and control sinus tissue neutrophils (3,136 cells). Commonly downregulated genes in NP neutrophils were associated with the innate immune system, and upregulated genes were associated with nuclear factor-κB signaling, cytokine activity, and cellular response to oxygen-containing compounds. NP neutrophils displayed 4 clusters revealing potential heterogeneity of neutrophils in NP tissue.

CONCLUSIONS

Elevated neutrophils in NP tissue appear to exist in several subphenotypes that may play important pathogenic roles in CRSwNP.

New insights into the endotypes of chronic rhinosinusitis in the biologic era

Chronic rhinosinusitis (CRS) exhibits significant heterogeneity and has been generally classified as type 1 (T1), T2, and T3 endotypes according to the histopathologic and inflammatory features of the nasal mucosa. T2 inflammation has been regarded as the predominant endotype of CRS linked to disease severity and refractory conditions. The development of biological agents that specifically target key molecules involved in T2 inflammation offers a highly effective and promising therapeutic approach for CRS. Recent findings have expanded the understanding of CRS endotypes by incorporating a range of disease-related molecules for classification, with progress made on the endotyping of CRS without nasal polyps. In addition, there has been an increasing emphasis on the study of mixed inflammatory endotypes. This review examines recent findings on CRS endotyping and the related noninvasive biomarkers, as well as novel mechanisms governing endotype formation, and addresses the efficacy of biologics in targeting T2 inflammation. Further research is warranted to understand if newly identified CRS endotypes show clinical significance for precision medicine and the management and treatment of refractory CRS in the era of biologics.

The role of fibroblast in chronic rhinosinusitis with nasal polyps: a key player in the inflammatory process

INTRODUCTION

Fibroblasts are the primary supporting cells in connective tissue and have long been thought to contribute to chronic rhinosinusitis with nasal polyps (CRSwNP) by producing extracellular matrix (ECM), leading to fibrosis and tissue remodeling. However, recent studies have highlighted the critical role of nasal polyp-derived fibroblasts (NPDFs) in triggering and intensifying the inflammatory response in CRSwNP.

AREAS COVERED

This review undertook a comprehensive literature search across the PubMed database, Web of Science since 2000, offering an in-depth summary of the pivotal role of NPDFs in tissue remodeling and inflammatory responses in CRSwNP. Additionally, single-cell RNA sequencing data provides a deeper exploration of the heterogeneity and functional mechanisms of fibroblasts in CRSwNP. Consequently, these insights point to fibroblasts as promising therapeutic targets for effectively treating CRSwNP.

EXPERT OPINION

Current data underscore the essential role of fibroblasts in the pathogenesis of CRSwNP. Fully elucidating the specific mechanisms by which fibroblasts contribute to the disease process is crucial for developing targeted therapies. Furthermore, advancements in single-cell RNA sequencing pave the way for selectively targeting and depleting pathological fibroblast subpopulations. Despite these advancements, the clinical development of fibroblast-targeted therapies in CRSwNP remains challenging.

HMOX1 as a potential drug target for upper and lower airway diseases: insights from multi-omics analysis

BACKGROUND

Oxidative stress is key in inflammatory airway diseases. Heme oxygenase 1 (HMOX1) regulates oxidative stress, but its role in airway diseases needs exploration.

METHODS

Differentially expressed genes (DEGs) between healthy nasal mucosa and chronic rhinosinusitis with nasal polyps (CRSwNP) were identified from Gene Expression Omnibus (GEO). Candidate genes were further screened using Gene Set Enrichment Analysis (GSEA) and Random Forest (RF) algorithms. Causal inference between candidate genes and upper and lower airway diseases (CRSwNP, allergic rhinitis (AR), and asthma (AS)) was conducted using bidirectional two-sample Mendelian randomization (TwoSampleMR) analysis. Single-cell RNA sequencing (scRNA-seq) data were used to determine the cellular localization and intercellular interactions of candidate genes. Molecular docking was used to identify potential therapeutic agents.

RESULTS

HMOX1 expression was significantly elevated in CRSwNP. TwoSampleMR analysis indicated a negative causal relationship between HMOX1 exposure and the occurrence of upper and lower airway diseases (CRSwNP [(odds ratio (OR)/95% confidence interval (CI): 0.945/(0.893-0.999), P = 0.044], AR [OR/95% CI: 0.997/(0.994-0.999), P = 0.007], and AS [OR/95% CI: 0.935/(0.895-0.977), P = 0.003]). scRNA-seq data revealed HMOX1 localization in M2 macrophages. Molecular docking identified 15 antioxidants, including Acetylcysteine and Quercetin, that can upregulate HMOX1 expression.

CONCLUSION

HMOX1 may have a protective role in the pathogenesis of upper and lower airway diseases (CRSwNP, AR, and AS) by modulating oxidative stress. Antioxidants that increase HMOX1 expression could offer new therapeutic avenues for these diseases.

CLINICAL TRIAL

Not applicable.

Chronic rhinosinusitis with nasal polyps: Key considerations in the multidisciplinary team approach

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a recurrent inflammatory disease associated with several comorbidities and a significant disease burden for patients. Treatments include corticosteroids and sinonasal surgery, but these can be associated with the risk of adverse events and nasal polyp recurrence. Biologic treatments such as mepolizumab can be used as an add-on treatment and are effective at reducing surgery and corticosteroid use.

MAIN TEXT

Patients with CRSwNP may be seen by a specialist in one of several different areas and often experience delayed diagnosis due to the need to see multiple physicians, as well as misdiagnosis resulting from lack of sufficient expertise within any one speciality. Multidisciplinary team (MDT) approaches have been shown to be effective in optimising the treatment and clinical management of other respiratory diseases, such as aspirin-exacerbated respiratory disease and severe asthma. In CRSwNP, an MDT approach may reduce diagnostic delays, mitigate secondary disease burden, and reduce overprescription of corticosteroids and antibiotics.

CONCLUSION

This article provides an overview of the patient perspective of MDTs, existing approaches and barriers to adoption, lessons learnt from allied and rare diseases, how to address under-recognised aspects of CRSwNP, and other key considerations for developing an MDT approach.

Omics in allergy and asthma

This review explores the transformative impact of omics technologies on allergy and asthma research in recent years, focusing on advancements in high-throughput technologies related to genomics and transcriptomics. In particular, the rapid spread of single-cell RNA sequencing has markedly advanced our understanding of the molecular pathology of allergic diseases. Furthermore, high-throughput genome sequencing has accelerated the discovery of monogenic disorders that were previously overlooked as ordinary intractable allergic diseases. We also introduce microbiomics, proteomics, lipidomics, and metabolomics, which are quickly growing areas of research interest, although many of their current findings remain inconclusive as solid evidence. By integrating these omics data, we will gain deeper insights into disease mechanisms, leading to the development of precision medicine approaches that promise to enhance treatment outcomes.

Factors for predicting the outcome of surgery for non-eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Despite the large patient base in Asia, the prognostic factors of patients with non-eosinophilic chronic rhinosinusitis with nasal polyps (CRSwNPs) remain largely undetermined.

OBJECTIVE

To systematically investigate the predictive value of clinical and biological variables for non-eosinophilic CRSwNP.

METHODS

A total of 51 patients with non-eosinophilic CRSwNP who underwent functional endoscopic surgery were recruited. Clinical information and assessment were comprehensively collected before and after surgery. A broad spectrum of biomarkers was measured in tissue homogenates using multiple assays. A random forest algorithm and stepwise logistic regression were used to construct clinical, biological, and combined models.

RESULTS

A total of 41.2% patients with non-eosinophilic CRSwNP were uncontrolled more than 6 months after surgery. We identified 1 clinical variable (22-item Sino-Nasal Outcome Test score) and 4 biomarkers (programmed cell death ligand 1, platelet-derived growth factor subunit β [PDGF-β], macrophage inflammatory protein-3b, and PDGF-α) that were significantly predictive of the surgical outcome. The clinical, biological, and combined models had predictive ability with areas under the curve of 0.78, 0.83, and 0.89, respectively. PDGF-β and programmed cell death ligand 1 were identified as independent biomarkers for the prognosis of patients with CRSwNP without considerable eosinophilic infiltration.

CONCLUSION

This study reveals that clinical and biological factors, such as the 22-item Sino-Nasal Outcome Test score and PDGF-β, are predictive of the postfunctional endoscopic surgical prognosis of patients with non-eosinophilic CRSwNP.

Cross‑Cultural Validation of the Chronic Rhinosinusitis Patient-Reported Outcomes (CRS-PRO) Questionnaire in Portuguese

Introduction Chronic rhinosinusitis (CRS) presents with different clinical patterns with variable responses to treatment. Clear criteria for specifying disease severity and assessing symptom control are lacking in the current literature. We aimed to perform a cross-cultural adaptation of the chronic rhinosinusitis patient-reported outcomes (CRS-PRO), creating a Portuguese version to use as a routine questionnaire in the evaluation of patients with CRS. Methods The CRS-PRO questionnaire was translated according to the recommendations of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) through a three-step procedure including a backward translation. Results After translation completion, the questionnaire was evaluated in 40 participants (23 men) who completed the questionnaire on two separate occasions in 1.4 minutes (SD 0.615). Twenty of them were patients with CRS (60% with polyps), and the other 20 were healthy subjects who were considered a control group. The average age of the study participants was 43 years old (SD 16). The intraclass correlation coefficient (ICC) values for the CRS with nasal polyps (CRSwNP) group ranged from 0.65 to 0.89, indicating good to excellent reliability across the 12 items. All ICC values were statistically significant (p < 0.01). Conclusion This study presents the Portuguese version of the CRS-PRO questionnaire, an adapted, validated, and well-accepted instrument for evaluating CRS symptoms in the Portuguese-speaking population.

Single cell RNA sequencing of human eosinophils from nasal polyps reveals eosinophil heterogeneity in chronic rhinosinusitis tissue

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 inflammation in the United States, but the actual roles that eosinophils play in CRSwNP remain largely unclear.

OBJECTIVE

To reveal the roles and heterogeneity of eosinophils in nasal polyp (NP) tissue, we performed single cell RNA sequencing (scRNA-Seq) analysis of NP tissue.

METHODS

Sinonasal tissues (NP and control sinus tissue) and patient matched peripheral blood (PB) samples were obtained from 5 control patients and 5 patients with CRSwNP. Eosinophils were enriched before processing for scRNA-Seq. The gene expression profiles in eosinophils were determined by microwell-based scRNA-Seq technology (BD Rhapsody platform). We predicted the overall function of NP eosinophils by Gene Ontology (geneontology.org) enrichment and pathway analyses and confirmed expression of selected genes by flow cytometry.

RESULTS

After filtering out contaminating cells, we detected 5,542 eosinophils from control PB, 3,883 eosinophils from CRSwNP PB, 101 eosinophils from control sinus tissues (not included in further analyses), and 9,727 eosinophils from NPs by scRNA-Seq. We found that 204 genes were downregulated and 354 genes upregulated in NP eosinophils compared to all PB eosinophils (>1.5-fold, Padj < .05). Upregulated genes in NP eosinophils were associated with activation, cytokine-mediated signaling, growth factor activity, NF-κB signaling, and antiapoptotic molecules. NP eosinophils displayed 4 clusters revealing potential heterogeneity of eosinophils in NP tissue.

CONCLUSIONS

Elevated eosinophils in NP tissue appear to exist in several subtypes that may play important pathogenic roles in CRSwNP, in part by controlling inflammation and hyperproliferation of other cells.

Neutrophil Extracellular Traps as a Biomarker in Refractory Non-Type 2 CRSwNP

PURPOSE

Chronic rhinosinusitis (CRS) is classified into type 2 (T2) and non-T2 inflammation. T2 CRS presents as a severe form, CRS with nasal polyps (CRSwNP), which often occurs with asthma as a comorbidity worldwide. Some cases of non-T2 CRS show nasal polyposis and refractoriness, mainly in Asian countries. However, its mechanism remains elusive. To investigate a biomarker for the refractoriness of non-T2 CRSwNP via RNA sequencing.

METHODS

RNA sequencing by using nasal polyps (NPs) and ethmoidal mucosa (EM) from CRS subjects and uncinate tissues from controls was performed, and differentially expressed genes (DEGs) were analyzed (cutoffs: expression change > 2-fold, P < 0.01). Immunofluorescence staining and enzyme-linked immunosorbent assay were performed.

RESULTS

We identified DEGs among T2-NP, non-T2-NP, T2-EM, non-T2-EM, and controls (NP vs. controls: 1,877 genes, EM vs. controls: 1,124 genes, T2-NP vs. controls: 1,790 genes, non-T2-NP vs. controls: 2,012 genes, T2-EM vs. controls: 740 genes, non-T2-EM vs. controls: 1,553 genes). The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that neutrophil extracellular trap (NET) formation, systemic lupus erythematosus, and the phagosome were enriched in non-T2-NP vs. controls and non-T2-EM vs. controls. Immunofluorescence staining confirmed that NETs were elevated in non-T2-NP. Cytokine analysis demonstrated that NETs were significantly related to the refractoriness in non-T2-NPs.

CONCLUSIONS

This study demonstrated DEGs between T2 and non-T2 inflammation. These results suggest that NETs may contribute to the refractoriness in non-T2-NPs and have a promise as a therapeutic strategy for patients with refractory non-T2-NP.

Evaluation of CNPase and TGFβ1/Smad Signalling Pathway Molecule Expression in Sinus Epithelial Tissues of Patients with Chronic Rhinosinusitis with (CRSwNP) and without Nasal Polyps (CRSsNP)

Chronic rhinosinusitis with and without nasal polyps (CRSwNP and CRSsNP, respectively) is a chronic inflammatory disease affecting almost 5 to 12% of the population and exhibiting high recurrence rates after functional endoscopic sinus surgery (FESS). TGFβ1-related pathways contribute to tissue remodelling, which is one of the key aspects of CRS pathogenesis. Additionally, adenosine signalling participates in inflammatory processes, and CNPase was shown to elevate adenosine levels by metabolizing cyclic monophosphates. Thus, the aim of this study was to assess the expression levels of Smad2, pSmad3, TGFβ1, and CNPase protein via immunohistochemistry in sinus epithelial tissues from patients with CRSwNP (n = 20), CRSsNP (n = 23), and non-CRS patients (n = 8). The expression of Smad2, pSmad3, TGFβ1, and CNPase was observed in the sinus epithelium and subepithelial area of all three groups of patients, and their expression correlated with several clinical symptoms of CRS. Smad2 expression was increased in CRSsNP patients compared to CRSwNP patients and controls (p = 0.001 and p < 0.001, respectively), pSmad3 expression was elevated in CRSwNP patients compared to controls (p = 0.007), TGFβ1 expression was elevated in CRSwNP patients compared to controls (p = 0.009), and CNPase was decreased in CRSsNP patients compared to controls (p = 0.03). To the best of our knowledge, we are the first to demonstrate CNPase expression in the upper airway epithelium of CRSwNP, CRSsNP, and non-CRS patients and point out a putative synergy between CNPase and TGFβ1/Smad signalling in CRS pathogenesis that emerges as a novel still undiscovered aspect of CRS pathogenesis; further studies are needed to explore its function in the course of the chronic inflammation of the upper airways.

CHI3L1 on fibrinolytic system imbalance in chronic rhinosinusitis with nasal polyp

Background

Chronic rhinosinusitis (CRS) is an inflammatory disease affecting more than 10% of the global adult population. It is classified into Th1, Th2, and Th17 endotypes and eosinophilic and non-eosinophilic types. Th2-based inflammation and eosinophilic CRS (ECRS) are associated with tissue remodeling and fibrinolytic system impairment.

Objective

To elucidate the role of eosinophils in inducing fibrin deposition in CRS nasal polyp tissues and explore potential regulatory mechanisms.

Methods

We analyzed the expression of genes related to the serpin family and fibrinolytic system using Gene Expression Omnibus and Next-generation sequencing data. Differentially expression genes (DEGs) analysis was used to compare control and nasal polyp tissues, followed by KEGG and Gene ontology (GO) analysis. We measured the expression and correlation of plasminogen activator-1 (PAI-1), tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA), and urokinase plasminogen activator surface receptor (u-PAR) in CRS tissues, and evaluated the effect of eosinophils on the fibrinolytic system using a cytokine array and co-culture.

Results

Nasal polyp tissues showed upregulated PAI-1, u-PA, and u-PAR expression and downregulated t-PA expression. Fibrinolytic system-related genes positively correlated with Th2 cytokines, except for t-PA. Eosinophil-derived Chitinase-3-like protein 1 (CHI3L1) increased PAI-1 expression and decreased t-PA levels in fibroblasts and epithelial cells. The inhibition of CHI3L1 suppresses these alterations.

Conclusion

CHI3L1 contributes to fibrin deposition by impairing the fibrinolytic system during nasal polyp formation. The regulation of CHI3L1 expression may inhibit fibrin deposition and edema in ECRS, presenting a potential treatment for this condition.

The oxidant-antioxidant imbalance was involved in the pathogenesis of chronic rhinosinusitis with nasal polyps

Background

Although oxidative stress is involved in the pathophysiological process of chronic rhinosinusitis with nasal polyps (CRSwNP), the specific underlying mechanism is still unclear. Whether antioxidant therapy can treat CRSwNP needs further investigation.

Methods

Immunohistochemistry, immunofluorescence, western blotting and quantitative polymerase chain reaction (qPCR) analyses were performed to detect the distribution and expression of oxidants and antioxidants in nasal polyp tissues. qPCR revealed correlations between oxidase, antioxidant enzymes and inflammatory cytokine levels in CRSwNP patients. Human nasal epithelial cells (HNEpCs) and primary macrophages were cultured to track the cellular origin of oxidative stress in nasal polyps(NPs) and to determine whether crocin can reduce cellular inflammation by increasing the cellular antioxidant capacity.

Results

The expression of NOS2, NOX1, HO-1 and SOD2 was increased in nasal epithelial cells and macrophages derived from nasal polyp tissue. Oxidase levels were positively correlated with those of inflammatory cytokines (IL-5 and IL-6). Conversely, the levels of antioxidant enzymes were negatively correlated with those of IL-13 and IFN-γ. Crocin inhibited M1 and M2 macrophage polarization as well as the expression of NOS2 and NOX1 and improved the antioxidant capacity of M2 macrophages. Moreover, crocin enhanced the ability of antioxidants to reduce inflammation via the KEAP1/NRF2/HO-1 pathway in HNEpCs treated with SEB or LPS. Additionally, we observed the antioxidant and anti-inflammatory effects of crocin in nasal explants.

Conclusion

Oxidative stress plays an important role in the development of CRSwNP by promoting various types of inflammation. The oxidative stress of nasal polyps comes from epithelial cells and macrophages. Antioxidant therapy may be a promising strategy for treating CRSwNP.

Uncovering the Cellular Microenvironment in Chronic Rhinosinusitis via Single-Cell RNA Sequencing: Application and Future Directions

Chronic rhinosinusitis (CRS) is a heterogenic disease characterized by persistent mucosal inflammation of the upper airway. Researches of CRS have progressed from phenotype-based to endotype-based, looking more deeply into molecular biomarkers, signaling pathways, and immune microenvironment. Single-cell RNA sequencing is an effective tool in analyzing composition, function, and interaction of cells in disease microenvironment at transcriptome level, showing great advantage in analyzing potential biomarkers, pathogenesis, and heterogeneity of chronic airway inflammation in an unbiased manner. In this article, we will review the latest advances in scRNA-seq studies of CRS to provide new perspectives for the diagnosis and treatment of this heterogeneous disease.

Clinical characteristics in Japanese patients with chronic rhinosinusitis who underwent endoscopic sinus surgery

OBJECTIVE

There is heterogeneity in the pathophysiology of chronic rhinosinusitis (CRS). Obtaining a detailed understanding of patient profiles in specific regions can provide valuable information not only for clinical practice but also future research plans. The aim of this study was to investigate the characteristics of patients who underwent endoscopic sinus surgery (ESS) for CRS.

METHODS

This retrospective, single-center study examined the features of 453 patients with CRS who underwent ESS in the Tokyo area of Japan. The study evaluated various factors in patients with CRS including sex and age, the Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis (JESREC) score, the recurrence rate of CRS, comorbidities of asthma and/or allergic diseases, and IgE sensitization to 12 inhaled allergens.

RESULTS

Age-related declines in the sensitization rate to inhaled allergens were observed, and the most notable age-related decrease in specific IgE antibodies was observed for house dust mites (HDM) (p = 8.3 × 10-7). Sensitization to HDM, cat dander, and various types of fungi, including Aspergillus, was frequently observed in the CRS with asthma group, with rates of 54%, 17%, and 17%, respectively. We found that 23% of the patients had recurrence. In the recurrence group, the positive rates of specific IgE antibodies for birch and cat dander were significantly higher than in the no recurrence group. Bronchial asthma was identified as an important factor for recurrence. Among male patients, the recurrence group was younger than the no-recurrence group (p = 0.0032). Severe eosinophilic CRS (ECRS) showed early recurrence after surgery, with over the half of the patients experiencing at least one recurrence within 2 years post-surgery. Among patients with ECRS, the recurrence rate for females was 1.92 times higher than for males.

CONCLUSION

Our study revealed the influences of age and sex on various clinical phenotypes of CRS patients undergoing ESS. There was a high sensitization rate to cat dander in both the recurrence and asthma groups. Further research on diverse disease etiologies is necessary to improve therapeutic strategies for patients with CRS.

Interaction of eosinophilic and neutrophilic inflammation in patients with chronic rhinosinusitis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Endotypic heterogeneity and pathogenesis in chronic rhinosinusitis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

The current findings in eosinophilic chronic rhinosinusitis

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

Long-Term Efficacy of Dupilumab for Eosinophilic Chronic Rhinosinusitis

BACKGROUND

Eosinophilic chronic rhinosinusitis (eCRS) is a type 2 inflammatory disease that frequently recurs after surgery. In recent years, dupilumab has been available for the treatment of refractory chronic rhinosinusitis since 2020 in Japan. Although there are some reports of its usefulness, there are not enough reports of its clinical efficacy for longer than 1 year, especially for olfactory recovery.

METHODS

Twenty patients with eCRS who had recurrence after surgery and had been receiving dupilumab were enrolled retrospectively. The nasal polyp score (NPS), computed tomography (CT) score, T&T olfactometer, and olfactory cleft opacification on CT were evaluated at baseline, at an average of 5.1 months later (short term), and at an average of 18.3 months later (long term).

RESULTS

At the short-term evaluation, there were significant improvements in the NPS and CT scores (P < .001, P = .008, respectively). The CT score was further improved at the long-term evaluation compared to the short-term evaluation (P = .018) and baseline (P = .008). T&T detection/recognition thresholds and olfactory cleft opacification showed significant improvements only at the long-term evaluation compared to baseline (P = .002, P = .006, and, P = .006, respectively).

CONCLUSION

The NPS remained improved, and the CT score showed further improvement with long-term treatment, whereas olfactory function and olfactory cleft opacification showed significant improvement only after long-term treatment. There was a dissociation between the time to improve in the NPS and CT scores and the time to improve in olfactory function and olfactory cleft opacification. Based on these results, dupilumab should be administered for longer than 1 year, especially for olfactory function.

Cross-cultural adaptation of the CRS-PRO questionnaire into French

BACKGROUND

Chronic rhinosinusitis (CRS), encompasses many different clinical patterns with variable response to treatment. Precise criteria specifying disease severity and control are lacking in the current literature. Our aim was to perform a cross-cultural adaptation of the CRS-PRO, creating a French version for use as a routine questionnaire in the assessment of patients with CRS.

METHODS

The CRS-PRO questionnaire was translated according to the recommendations of the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) through a three-step procedure including a backward translation.

RESULTS

Seven of 12 items were initially discordant between the three translators before achieving consensus (Step 1). Two of 12 items were discordant between the backward translation and the initial CRS-PRO version regarding the word "mucus"(Step 2). Step 3 allowed the creation of a French proof-read version of the CRS-PRO questionnaire. Thirty patients were included for initial validation, mean age of 49.2 ± 15 years and 63.3% (19/30) male. It took them 67 ± 23 s to complete the questionnaire without any patients requiring more than 2 min.

CONCLUSION

This study presents the French version of the CRS-PRO questionnaire-an adapted, validated, and well-accepted instrument to evaluate the CRS symptoms in the French speaking population.

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.

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

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

Surgery for chronic rhinosinusitis with nasal polyps: An update

This update aimed to evaluate surgical indications in the management of chronic rhinosinusitis with nasal polyps (CRSwNP). It was conducted and reported according to the criteria stipulated by the Synthesis Without Meta-analysis (SwiM) guidelines. From the PubMed-National Library of Medicine database, 1098 articles were identified for the period 2006-2021 using the key words "nasal polyps" and "surgery". After screening and analysis, 39 publications were selected. The efficacy of surgery on functional improvement in CRSwNP, measured by the specific quality-of-life score SNOT-22, is established, and improvement in olfactory function is expected in 50% of patients. The rate of surgical revision is at least 10-15% at 4 years, but the disease can be controlled for several years, with the interval between primary surgery and symptomatic recurrence exceeding 10 years in some cases. The criteria for surgery are not clearly defined in the literature. However, several authors consider failure of ≥ 8 weeks' well-conducted local medical treatment and use of more than 2 courses of systemic corticosteroids as a reliable indication. No studies or meta-analyses are currently available to determine the superiority of one surgical technique over another.

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.

Prognostic factors for post-operative outcomes in chronic rhinosinusitis with nasal polyps: a systematic review

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) has a high recurrence rate after surgery despite the availability of medical treatments. Multiple clinical and biological factors have been associated with poor post-operative outcomes in patients with CRSwNP. However, these factors and their prognostic values have not yet been extensively summarized.

AREAS COVERED

This systematic review included 49 cohort studies exploring the prognostic factors for post-operative outcomes in CRSwNP. A total of 7802 subjects and 174 factors were included. All investigated factors were classified into three categories according to their predictive value and evidence quality, of which 26 factors were considered plausible for post-operative outcome prediction. Previous nasal surgery, ethmoid-to-maxillary (E/M) ratio, fractional exhaled nitric oxide, tissue eosinophil count or percentage, tissue neutrophil count, tissue IL-5, tissue eosinophil cationic protein, and CLC or IgE in nasal secretion provided more reliable information for prognosis in at least two studies.

EXPERT OPINION

Exploring predictors through noninvasive or minimally invasive methods for specimen collection is recommended for future work. Models combining multiple factors must be established, as no single factor is effective for the whole population.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

New insights into the pathophysiology and therapeutic targets of asthma and comorbid chronic rhinosinusitis with or without nasal polyposis

Asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP) are chronic respiratory diseases. These two disorders often co-exist based on common anatomical, immunological, histopathological, and pathophysiological basis. Usually, asthma with comorbid CRSwNP is driven by type 2 (T2) inflammation which predisposes to more severe, often intractable, disease. In the past two decades, innovative technologies and detection techniques in combination with newly introduced targeted therapies helped shape our understanding of the immunological pathways underlying inflammatory airway diseases and to further identify several distinct clinical and inflammatory subsets to enhance the development of more effective personalized treatments. Presently, a number of targeted biologics has shown clinical efficacy in patients with refractory T2 airway inflammation, including anti-IgE (omalizumab), anti-IL-5 (mepolizumab, reslizumab)/anti-IL5R (benralizumab), anti-IL-4R-α (anti-IL-4/IL-13, dupilumab), and anti-TSLP (tezepelumab). In non-type-2 endotypes, no targeted biologics have consistently shown clinical efficacy so far. Presently, multiple therapeutical targets are being explored including cytokines, membrane molecules and intracellular signalling pathways to further expand current treatment options for severe asthma with and without comorbid CRSwNP. In this review, we discuss existing biologics, those under development and share some views on new horizons.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Endotypes of Nasal Polyps in Children: A Multidisciplinary Approach

Nasal polyps (NPs) are rarely reported in childhood and usually represent red flags for systemic diseases, such as cystic fibrosis (CF), primary ciliary dyskinesia (PCD) and immunodeficiencies. The European Position Paper released in 2020 (EPOS 2020) provided a detailed classification and defined the correct diagnostic and therapeutic approaches. We report a one-year experience of a multidisciplinary team, made up of otorhinolaryngologists, allergists, pediatricians, pneumologists and geneticists, with the aim of ensuring a personalized diagnostic and therapeutic management of the pathology. In 16 months of activity, 53 patients were admitted (25 children with chronic rhinosinusitis with polyposis and 28 with antro-choanal polyp). All patients underwent phenotypic and endo-typic assessment, using proper classification tools for nasal pathology (both endoscopic and radiological), as well as adequate cytological definition. An immuno-allergic evaluation was carried out. Pneumologists evaluated any lower airway respiratory disease. Genetic investigations concluded the diagnostic investigation. Our experience enhanced the complexity of children's NPs. A multidisciplinary assessment is mandatory for a targeted diagnostic and therapeutic pathway.

Cystatin SN in type 2 inflammatory airway diseases

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

Core Outcome Measures in Chronic Rhinosinusitis With Nasal Polyps: In Practice and Research

Heterogeneity in outcomes used in clinical trials prevents meta-analysis and contributes to research waste. Core outcome sets aim to address this by defining a small number of essential outcomes that should be measured in all effectiveness trials. Adoption in routine clinical practice can further improve outcomes for patients.There has been a rapid growth in therapeutic options available for patients with chronic rhinosinusitis with nasal polyps, but difficulty comparing results leads to uncertainty into optimum management, and there is a need to define a core outcome set. We consider whether work already undertaken needs to be modified for patients with nasal polyps.We recommend that a core outcome set should include assessment of disease specific quality of life, nasal polyp score, evaluation of sense of smell, alongside need for OCS and surgical treatment and complications from the disease or treatment. Further work is required to achieve international consensus regarding the choice of nasal polyp scoring system.

Epidemiology and aetiology of chronic rhinosinusitis in Asia-A narrative review

BACKGROUND

Despite having a similar prevalence to Western populations, literature on chronic rhinosinusitis (CRS) in the Asian population is sparse. There is limited data on the epidemiology and aetiology of CRS in Asia.

OBJECTIVES

To review the current literature on the epidemiology and aetiology of CRS in Asia.

METHODS

This is a narrative review of published data on the epidemiology and aetiology of CRS. Studies on CRS in Asian countries, published in English and indexed on PubMed or Google Scholar were reviewed. Where available, data extracted included epidemiology, endotype and cytokine profiles and genetic profiles.

RESULTS AND CONCLUSION

The prevalence of CRS in Asia ranges widely from 2.1% to 28.4%. Type 2 inflammation has been reported in 5%-55% of Asian patients, with lower levels of Type 2 cytokines reported in head to head comparisons of Western versus Asian patients. Notably, there exists marked heterogeneity in criterion of the tissue eosinophilic infiltration for diagnosis of type 2 CRS. Our review suggests that differences in prevalence of CRS and proportion of eosinophilic CRS between Asia and Europe and the Americas requires further study. Large-scale Asian studies utilising standardised definitions are needed to bridge this gap. Head to head genetic and microbiomal analysis may also be useful in understanding differences in CRS between the Asian and Western populations.

Genetics and epigenetics of chronic rhinosinusitis

Discerning the genetics and epigenetics of chronic rhinosinusitis (CRS) may optimize outcomes through early diagnostics, personalized and novel therapeutics, and early prognostication. CRS associated with cystic fibrosis and primary ciliary dyskinesia has well-characterized genetic mutations. Most CRS subjects, however, do not exhibit identifiable monogenic alterations. Clustering in related individuals is seen in CRS with nasal polyps. Spouses of subjects with CRS without nasal polyps also may be at increased risk of the same disease. These observations generate questions on genetic and environmental influences in CRS. Genome-wide association studies have identified variations and polymorphisms between CRS and control subjects in genes related to innate and adaptive immunity. Candidate gene and transcriptomics studies have investigated and identified genetic variations related to immunity, inflammation, epithelial barrier function, stress-response, antigen processing, T-cell regulation, and cytokines in CRS. Epigenetic studies have identified mechanisms through which environmental factors may affect these gene functions. However, causality is not determined for most variations. Inferences drawn from these data must be measured because most investigations report unreplicated results from small study populations. Large, replicated studies in tight cohorts across diverse populations remain a pressing need in studying CRS genetics.

Increased CYR61 expression activates CCND1/c-Myc pathway to promote nasal epithelial cells proliferation in chronic rhinosinusitis with nasal polyps

PURPOSE

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is a chronic sinonasal inflammatory disease characterized histologically by hyperplastic nasal epithelium and epithelial cells proliferation. Cysteine-rich angiogenic inducer 61 (CYR61) acts as a positive regulator of cell cycle process. Cyclin D1 (CCND1) and c-Myc play key roles in the processes of cell cycle and cell growth. The purpose of our research was to explore the expression and roles of CYR61, CCND1 and c-Myc in CRSwNP.

METHODS

FeaturePlot and vlnPlot functions embedded in the seurat package (version 4.1.1) of R software (version 4.2.0) were applied to explore the cellular distribution of CYR61, CCND1 and c-Myc in the single-cell RNA sequencing (scRNA-seq) dataset of nasal tissue samples. CYR61, CCND1 and c-Myc immunolabeling and mRNA levels in nasal tissue samples were assessed by immunohistochemistry and real-time PCR. Co-localization of CYR61, CCND1 and c-Myc with basal epithelial cell marker P63 was assayed using double-label immunofluorescence staining. Furthermore, we collected and cultured human nasal epithelial cells (HNEC) to assess the regulation and role of CYR61 in vitro study.

RESULTS

CYR61, CCND1 and c-Myc were primarily expressed by nasal epithelial cells. Significant upregulation of CYR61, CCND1 and c-Myc positive cells and increased levels of CYR61, CCND1 and c-Myc mRNA were found in nasal polyps in comparison to control samples. Of note, CYR61 mRNA and protein levels were altered by SEB, LPS, IFN-γ, IL-13, IL-17A and TGF-β1 in HNEC. In addition, CYR61 intervention could increase CCND1 and c-Myc mRNA and protein levels to promote HNEC proliferation, and siRNA against ITGA2 (si-ITGA2) could reverse CYR61 induced upregulation of CCND1 and c-Myc mRNA and protein levels in HNEC and cell proliferation of HNEC.

CONCLUSIONS

CYR61, CCND1 and c-Myc were primarily expressed by epithelial cells in nasal mucosa. CYR61, CCND1 and c-Myc expression levels were increased in CRSwNP compared with controls. CYR61 could interact with ITGA2 to enhance HNEC proliferation via upregulating CCND1 and c-Myc levels in the HNEC, leading to hyperplastic nasal epithelium in CRSwNP.

Prevalence and risk factors of chronic rhinosinusitis among Chinese: A systematic review and meta-analysis

Background

Chronic rhinosinusitis (CRS) can be seen in people of all ages. CRS heavily affects the quality of a patient's daily life and also causes tremendous economic burdens on patients' families and society. The prevalence of CRS in different countries varies and no systematic review of the prevalence of CRS among Chinese has been published previously. The objective of this systematic review and meta-analysis is to determine the prevalence of CRS among Chinese and to explore the main risk factors of CRS among Chinese.

Methods

Using relevant keywords, data resources including PubMed, Scopus, Web of Science, Google Scholar, Embase, Cochrane Library, Chinese National Knowledge of Infrastructure (CNKI), WANGFANG, VIP, and China Biomedical Literature database (CMB) were searched to obtain literature reporting the prevalence of and risk factors of CRS among Chinese which were clearly diagnosed with CRS from inception to 30 June 2022. The random/fixed effect model was used for meta-analysis, and the I² index was employed to assess heterogeneity among studies. All analyses were performed by using the STATA version 16.0 software. The study was registered with PROSPERO, register number. CRD42022341877.

Result

A total of 12 relevant kinds of literature were qualified for the present systematic review, including 4,033 patients. The results showed that the overall prevalence of CRS among Chinese was 10% (95%CI: 0.06-0.13, I² = 99.6%, P < 0.001). The prevalence of CRS among Chinese who lived in urban cities was 18% (95%CI: -0.07 to 0.43, I² = 99.9%, P < 0.001), which was obviously lower than the prevalence of CRS among Chinese who lived in rural areas (27%, 95%CI: -0.14 to 0.68, I² = 99.8%, P < 0.001). The prevalence of CRS among Chinese before 2010 was 23% (95%CI: -0.05 to 0.50, I² = 99.8%, P < 0.001), which was remarkably higher than the prevalence of CRS among Chinese after 2010 (7%, 95%CI: 0.05-0.09, I² = 99.0%, P < 0.001). The prevalence of CRS among Chinese who were divorced was 17% (95%CI: 0.12-0.22, I² = 0.0%, P = 0.436), while the prevalence of CRS among Chinese who were married, widowed, and unmarried was 9% (95%CI: 0.06-0.11, I² = 88.1%, P = 0.004), 9% (95%CI: 0.06-0.11, I² = 0.0%, P = 0.863), and 9% (95%CI: 0.08-0.10, I² = 0.0%, P = 0.658), respectively. The prevalence of CRS among Han and minority Chinese was 8% (95%CI: 0.07-0.10, I² = 69.6%, P = 0.070) and 12% (95%CI: 0.10-0.15, I² = 38.6%, P = 0.202), respectively. The prevalence of CRS among Chinese who was never exposed to moldy or damp environments was 8% (95%CI: 0.08-0.09, I² = 0.0%, P = 0.351), the prevalence of CRS among Chinese who was occasionally exposed to moldy or damp environments was 16% (95%CI: 0.10-0.22, I² = 78.9%, P = 0.030), and the prevalence of CRS among Chinese who was frequently or every day exposed to moldy or damp environments was up to 20% (95%CI: 0.15-0.24, I² = 0.0%, P = 0.558).

Conclusion

This meta-analysis shows that the prevalence of CRS among Chinese is at a high level. People who have some risk factors, such as occasional or frequent or everyday exposure to moldy or damp environments, have a higher prevalence of CRS. We should attach more importance to the risk factors of CRS in clinical practice and disseminate scientific information and carry out education to lower the prevalence of CRS in China.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=341877, identifier: CRD42022341877.

Heterogeneity of asthma with nasal polyposis phenotypes: A cluster analysis

BACKGROUND

Chronic rhinosinusitis with nasal polyposis (CRSwNP) affects a significant number of asthmatic patients and is notably associated with a more difficult-to-control asthma and marked inflammation. We need more studies on this specific asthma phenotype and its possible subphenotypes, in order to better individualize treatments.

AIM

The aim of this study is to identify and characterize subphenotypes of asthma patients with CRSwNP using clinical, physiological and inflammatory variables.

METHODS

K-means cluster analysis was performed on 17 clinical, physiological, and inflammatory variables from 1263 patients of all asthma severity and on a subpopulation of patients with asthma and CRSwNP. Study was registered on ClinicalTrials.gov (NCT03694847).

RESULTS

On the overall population, three groups were identified. Cluster T1 (n = 708) are young, have a short asthma duration and a low prevalence of CRSwNP. Cluster T2 (n = 263) have the longest asthma duration and Cluster T3 (n = 292) are older with the shortest asthma duration. Patients in Clusters T2 and T3 have similar prevalences of CRSwNP. On the subpopulation of asthma with CRSwNP, three clusters were also identified. Cluster S1 (n = 83) have mild-to-moderate asthma with normal lung function. Clusters S2 (N = 53) and S3 (N = 42) include patients with severe asthma and decreased lung function, but those in Cluster S2 have a longer asthma duration, whereas those Cluster S3 have late-onset asthma.

CONCLUSIONS

Despite coexistence of asthma and CRSwNP, not all patients have the same evolution of their asthma. Different phenotypes of asthma with CRSwNP can be identified and exploration of the characteristics of these subgroups could lead to a better individualized, targeted management.

M2 macrophage-related gene signature in chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common sinonasal inflammatory disorder with high heterogeneity. Increasing evidence have indicated that the infiltration of macrophages especially M2 macrophages play pivotal roles in the pathogenesis of CRSwNP, but the underlying mechanisms remain undetermined. This study sought to identify potential biomarkers related to M2 macrophages in CRSwNP.

METHODS

The expression datasets of GSE136825 and GSE179265 were download from Gene Expression Omnibus (GEO) database and merged. Then, CIBERSORT and weighted gene co-expression network analysis (WGCNA) algorithms were applied to identify M2 macrophage-related gene modules. Thereafter, differentially expressed genes (DEGs) related to M2 macrophages were selected to perform functional enrichment analyses. A protein-protein interaction (PPI) network was built to identify hub genes and quantitative real-time reverse transcriptions PCR was used to verify the bioinformatics results.

RESULTS

A total of 92 DEGs associated with M2 macrophages were identified for further analysis. The results of Gene ontology (GO) and Kyoto Encyclopedia of genes and genomes (KEGG) analyses illustrated that M2 macrophage-associated DEGs primarily enriched in immune responses and extracellular matrix structure. PPI network analysis identified 18 hub genes related to M2 macrophages that might be pivotal in the pathogenesis of CRSwNP. After verification, AIF1, C1QA, C1QB, C3AR1, CCR1, CD163, CD4, CD53, CD86, CSF1R, CYBB, FCER1G, FCGR3A, IL10RA, ITGB2, LAPTM5, PLEK, TYROBP were identified as potential M2 macrophage-related biomarkers for CRSwNP.

CONCLUSION

These findings yield new insights into the hub genes and mechanisms related to M2 macrophages in the pathogenesis of CRSwNP. Further studies of these hub genes would help better understand the disease progression and identify potential treatment targets.

Endotyping of nasal polyps in a multiracial Asian population

Background: Chronic rhinosinusitis is a heterogenous disease with variation in the endotypes of nasal polyps, with type 2 inflammation being more prevalent in Caucasian populations whereas Chinese populations are more heterogenous. We aim to describe the variation in endotypes for patients with chronic rhinosinusitis with nasal polyposis in our unique multiracial population. Methodology: Demographic, clinical and structured histopathological data of 66 patients who underwent sinus surgery for nasal polyposis were evaluated retrospectively. Results: 54.6% had eosinophilic disease, and 45.4% had non-eosinophilic disease with no significant demographic differences between the 2 populations. There were significantly higher peripheral eosinophil levels in patients with eosinophil-predominant inflammation on tissue histology (mean absolute eosinophil count 0.59 ± 0.18 x 109) compared with non-eosinophilic disease (mean absolute eosinophil count 0.24 ± 0.11 x 109). Structured histopathological reporting revealed that patients with eosinophilic disease had higher degree of inflammation and eosinophil aggregates. Conclusions: Our population is shown to have a slight preponderance toward eosinophilic disease, however the Chinese majority tended to have non-eosinophilic disease. Serum eosinophilia and the presence of asthma seems to correlate well with tissue eosinophilia, which can potentially be utilised as markers of type 2 inflammatory disease.

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.

Distinct Gene Set Enrichment Profiles in Eosinophilic and Non-Eosinophilic Chronic Rhinosinusitis with Nasal Polyps by Bulk RNA Barcoding and Sequencing

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease with a high symptom burden, including nasal congestion and smell disorders. This study performed a detailed transcriptomic analysis in CRSwNP classified as eosinophilic CRS (ECRS), nonECRS according to the Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis (JESREC) criteria, and a group of ECRS with comorbid aspirin intolerant asthma (Asp). Gene expression profiles of nasal polyps and the uncinate process in CRSwNP patients and normal subjects (controls) were generated by bulk RNA barcoding and sequencing (BRB-seq). A differentially expressed genes (DEGs) analysis was performed using DESeq2 software in iDEP to clarify any relationship between gene expression and disease backgrounds. A total of 3004 genes were identified by DEGs analysis to be associated with ECRS vs control, nonECRS vs control, and Asp vs control. A pathway analysis showed distinct profiles between the groups. A Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) showed distinct phenotype-specific pathways of expressed genes. In the specific pathway of “cytokine–cytokine receptor interaction”, the differentially expressed genes were widely distributed. This study indicates that transcriptome analysis using BRB-seq may be a valuable tool to explore the pathogenesis of type 2 inflammation in CRSwNP.

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.

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.