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.

Blood Eosinophil Percentage and Improved Sinus CT Score as Diagnostic Tools for ECRS

Objective

Differentiating 2 types of chronic rhinosinusitis with nasal polyps (CRSwNP) is important for the treatment. The current diagnostic methods using single indicators, including peripheral blood eosinophils and traditional sinus computed tomography (CT) scores, are not accurate. In this study, we aimed to investigate the diagnostic value of combining peripheral blood eosinophils and improved sinus CT scores for eosinophic chronic rhinosinusitis (ECRS).

Study Design

Retrospective cohort.

Setting

Tertiary medical center.

Methods

We conducted a study involving 81 patients with CRSwNP. Peripheral blood samples were collected from the non-ECRS and ECRS groups. Improved three-dimensional volume image analysis and Lund-Mackay scoring system were performed to quantify the thickening of sinus mucosa. Multivariate binary logistic regression analysis was carried out to detect the predictive value of the scoring indicators. For significant indexes, receiver operating characteristic (ROC) curve analysis was applied.

Results

The ECRS group had higher levels of blood eosinophil percentage and count, ethmoid sinus score, total sinus score, the ratio of ethmoid sinus score and maxillary sinus score, and the difference between ethmoid and maxillary score, compared to the non-ECRS group (P < 0.05). Binary logistic regression analysis demonstrated that both blood eosinophil percentage and the improved E - M score (subtraction of ethmoid and maxillary sinus scores) were significant predictors of ECRS diagnosis (P < .01). ROC curve analysis indicated that the combination of improved E - M score and blood eosinophil percentage had a higher diagnostic value compared to either factor alone (area under the curve = 0.874).

Conclusion

Our study suggested the combination of improved total ethmoid sinus-maxillary score and blood eosinophil percentage is more accurate in predicting the diagnosis of ECRS.

Systematic Review of Protein Biomarkers in Adult Patients With Chronic Rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous condition characterized by differing inflammatory endotypes. The identification of suitable biomarkers could enable personalized approaches to treatment selection.

OBJECTIVE

This study aimed to identify and summarize clinical studies of biomarkers in adults with CRS in order to inform future research into CRS endotypes.

METHODS

We conducted systematic searches of MEDLINE and Web of Science from inception to January 30, 2022 and included all clinical studies of adult CRS patients and healthy controls measuring biomarkers using enzyme-linked immunosorbent assays or Luminex immunoassays. Outcomes included the name and tissue type of identified biomarkers and expression patterns within CRS phenotypes. Study quality was assessed using the National Institutes of Health quality assessment tool for observational cohort and cross-sectional studies. A narrative synthesis was performed.

RESULTS

We identified 78 relevant studies involving up to 9394 patients, predominantly with CRS with nasal polyposis. Studies identified 80 biomarkers from nasal tissue, 25 from nasal secretions, 14 from nasal lavage fluid, 24 from serum, and one from urine. The majority of biomarkers found to distinguish CRS phenotypes were identified in nasal tissue, especially in nasal polyps. Serum biomarkers were more commonly found to differentiate CRS from controls. The most frequently measured biomarker was IL-5, followed by IL-13 and IL-4. Serum IgE, IL-17, pentraxin-3 and nasal phospho-janus kinase 2, IL-5, IL-6, IL-17A, granulocyte-colony stimulating factor, and interferon gamma were identified as correlated with disease severity.

CONCLUSION

We have identified numerous potential biomarkers to differentiate a range of CRS phenotypes. Future studies should focus on the prognostic role of nasal tissue biomarkers or expand on the more limited studies of nasal secretions and nasal lavage fluid.We registered this study in PROSPERO (CRD42022302787).

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.

Pathological and therapeutic implications of eosinophil-derived semaphorin 4D in eosinophilic chronic rhinosinusitis

BACKGROUND

Eosinophilic chronic rhinosinusitis (ECRS) is a subtype of chronic rhinosinusitis. Clinical markers for ECRS disease activity and treatment strategies have not been sufficiently established. Although semaphorins are originally identified as neuronal guidance factors, it is becoming clear that they play key roles in immune regulation and inflammatory diseases.

OBJECTIVE

We sought to investigate the pathological functions and therapeutic potential of semaphorin 4D (SEMA4D) in ECRS.

METHODS

Serum soluble SEMA4D levels in patients with paranasal sinus diseases were measured by ELISA. The expression of SEMA4D in blood cells and nasal polyp tissues was assessed by flow cytometry and immunohistochemistry, respectively. Generation of soluble SEMA4D was evaluated in matrix metalloproteinase-treated eosinophils. Endothelial cells were stimulated with recombinant SEMA4D, followed by eosinophil transendothelial migration assays. Allergic chronic rhinosinusitis was induced in mice using Aspergillus protease with ovalbumin. The efficacy of treatment with anti-SEMA4D antibody was evaluated histologically and by nasal lavage fluid analysis.

RESULTS

Serum soluble SEMA4D levels were elevated in patients with ECRS and positively correlated with disease severity. Tissue-infiltrated eosinophils in nasal polyps from patients with ECRS stained strongly with anti-SEMA4D antibody. Cell surface expression of SEMA4D on eosinophils from patients with ECRS was reduced, which was due to matrix metalloproteinase-9-mediated cleavage of membrane SEMA4D. Soluble SEMA4D induced eosinophil transendothelial migration. Treatment with anti-SEMA4D antibody ameliorated eosinophilic infiltration in sinus tissues and nasal lavage fluid in the ECRS animal model.

CONCLUSIONS

Eosinophil-derived SEMA4D aggravates ECRS. Levels of serum SEMA4D reflect disease severity, and anti-SEMA4D antibody has therapeutic potential as a treatment for ECRS.

Amphiregulin-Producing Pathogenic Memory T Helper 2 Cells Instruct Eosinophils to Secrete Osteopontin and Facilitate Airway Fibrosis

Memory T cells provide long-lasting protective immunity, and distinct subpopulations of memory T cells drive chronic inflammatory diseases such as asthma. Asthma is a chronic allergic inflammatory disease with airway remodeling including fibrotic changes. The immunological mechanisms that induce airway fibrotic changes remain unknown. We found that interleukin-33 (IL-33) enhanced amphiregulin production by the IL-33 receptor, ST2^hi memory T helper 2 (Th2) cells. Amphiregulin-epidermal growth factor receptor (EGFR)-mediated signaling directly reprogramed eosinophils to an inflammatory state with enhanced production of osteopontin, a key profibrotic immunomodulatory protein. IL-5-producing memory Th2 cells and amphiregulin-producing memory Th2 cells appeared to cooperate to establish lung fibrosis. The analysis of polyps from patients with eosinophilic chronic rhinosinusitis revealed fibrosis with accumulation of amphiregulin-producing CRTH2^hiCD161^hiCD45RO⁺CD4⁺ Th2 cells and osteopontin-producing eosinophils. Thus, the IL-33-amphiregulin-osteopontin axis directs fibrotic responses in eosinophilic airway inflammation and is a potential target for the treatment of fibrosis induced by chronic allergic disorders.

Residual exhaled nitric oxide elevation in asthmatics is associated with eosinophilic chronic rhinosinusitis

OBJECTIVE

Eosinophilic chronic rhinosinusitis (ECRS) is as a subgroup of chronic rhinosinusitis (CRS) with nasal polyps. ECRS is a refractory disease closely related to bronchial asthma. Fractionated exhaled nitric oxide (FeNO) levels were reportedly elevated in some asthmatics with CRS after adequate treatment, suggesting that residual eosinophilic airway inflammation or ECRS might affect FeNO levels.

METHODS

To investigate the association between asthma with ECRS and FeNO levels, we examined FeNO levels in 133 asthmatics (99 with ECRS and 34 without ECRS) and 13 patients with ECRS without asthma. The severity of asthma was defined by the Global Initiative for Asthma guidelines and that of sinusitis was evaluated by the sinus CT score based on the Lund-Mackay scale.

RESULTS AND CONCLUSIONS

FeNO levels were elevated even in well-controlled asthmatics with ECRS, whereas asthmatics without ECRS and ECRS patients without asthma did not have high FeNO levels (>50 ppb). Although FeNO levels were not correlated with asthma severity, they were positively correlated with the sinus CT score. In asthmatics with ECRS, patients with higher FeNO levels had more severe ECRS and asthma. There is a possibility of having comorbid ECRS, particularly in asthmatics with high FeNO levels even after adequate treatment, including ICS, suggesting that asthma and ECRS may be closely associated as one airway disease with eosinophilic inflammation. Continual awareness of the coexistent ECRS is ideally recommended for asthmatics with high FeNO levels.