Mepolizumab decreases tissue eosinophils while increasing type-2 cytokines in eosinophilic chronic rhinosinusitis

Global Incidence and Prevalence of Chronic Rhinosinusitis: A Systematic Review

OBJECTIVE

Data on the global prevalence of chronic rhinosinusitis (CRS) is significantly varied and limited across countries and over time. Therefore, we aimed to conduct a comprehensive investigation into the global, regional, and national burden of CRS from the years 1980 to 2021, as well as identify those factors that influence levels of such burden.

DESIGN

We conducted a systematic review and meta-analysis of general population-based observational studies focusing on CRS. We calculated pooled estimates of CRS prevalence and incidence with 95% confidence intervals (CIs). Subgroup analyses were conducted stratifying by sex, age cohorts, geographic regions, smoking status, obesity, and comorbid conditions.

DATA SOURCES

PubMed/MEDLINE, EMBASE, CINAHL, Google Scholar, and Cochrane databases.

ELIGIBILITY CRITERIA FOR SELECTION

We included general population-based observational studies on CRS published from database inception through October 20, 2023.

RESULTS

A total of 28 eligible studies, encompassing more than 237 million participants and 11,342,923 patients with CRS from 20 countries across four continents, were included in the analysis. Global pooled prevalence of CRS and CRS with nasal polyps (CRSwNP) was found to be 8.71% (95% CI, 6.69-11.33; number of studies, 20) and 0.65% (95% CI, 0.56-0.75; number of studies, 4), respectively. The prevalence of CRS was greater in Europe compared with North America, South America, and Asia; adults compared with children; smokers compared with never-smoker; those with obesity compared with normal weight; and those with comorbidities such as asthma, diabetes mellitus, eczema, and nasal septal deviation. Pooled prevalence of CRS increased from 1980 to 2020 (1980-2000: 4.72%; 95% CI, 2.12-10.49; 2014-2020: 19.40%; 95% CI, 12.12-31.07). Similar patterns were observed in CRS incidence.

CONCLUSIONS

Our study provides valuable insights into CRS prevalence and incidence across diverse demographic and clinical factors, highlighting its increasing global burden. The reported prevalence of CRS varies internationally, and may be increasing over time. To enhance data quality and comparability, standardization of reporting methodologies is imperative.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (registration no. CRD42024527805).

TH2 cell compensatory effect following benralizumab treatment for eosinophilic gastritis

BACKGROUND

Eosinophil accumulation is a main feature of eosinophilic gastritis (EoG) and is associated with its histologic diagnosis and pathology. However, a recent clinical trial has demonstrated that EoG endoscopic, noneosinophil histologic, and clinical features remain persistent despite complete eosinophil depletion.

OBJECTIVE

Our aim was to examine gastric T-cell composition and associated cytokine levels of patients with EoG following benralizumab-induced eosinophil depletion versus following administration of placebo.

METHODS

A cohort of subjects with EoG from a subset of subjects who participated in a recent phase 2 benralizumab trial was treated for 12 weeks with administration of 3 doses of benralizumab (anti-IL-5 receptor α antibody [n = 5]) or placebo (n = 4). Single-cell suspensions obtained by gastric biopsy were stimulated with phorbol 12,13-dibutyrate and ionomycin in the presence of brefeldin A and monensin. Harvested cells were fixed, stained, and analyzed by flow cytometry to examine T-cell populations and associated cytokines.

RESULTS

Following benralizumab treatment but not placebo, blood and gastric eosinophil levels decreased 16-fold and 10-fold, respectively. Whereas histologic score and features were significantly decreased, no change was observed in endoscopic score and features. Following complete eosinophil depletion with benralizumab, gastric TH2 cell levels were 3-fold higher than the levels in the patients with EoG who were given placebo; and the levels of associated type 2 cytokine production of IL-4, IL-5, and IL-13 in the benralizumab-treated patients were, respectively, 4-, 5.5-, and 2.5-fold, higher than those in the placebo-treated patients.

CONCLUSION

We have identified a putative positive feedback loop whereby eosinophil depletion results in a paradoxic increase in levels of TH2 cells and derived cytokines; this finding suggests an explanation for the limited success of eosinophil depletion as monotherapy in eosinophil-associated gastrointestinal disorders.

Insight into IL-5 as a Potential Target for the Treatment of Allergic Diseases

Interleukin-5 functions as a B-cell differentiation factor, but more importantly, in the context of this review, it plays a variety of roles in eosinophil biology, including eosinophil differentiation and maturation in the bone marrow, and facilitates eosinophil migration to tissue sites, usually in the context of an allergic reaction. Given the availability of selective anti-IL-5 drugs such as mepolizumab and reslizumab, as well as the IL-5 receptor antagonist benralizumab, it is worth investigating whether they could be used in some cases of allergic disease. Asthma has a well-documented involvement of IL-5 in its pathophysiology and has clear benefits in the case of anti-IL-5 therapy; therefore, current knowledge is presented to provide a reference point for the study of less-described diseases such as atopic dermatitis, chronic rhinosinusitis, chronic spontaneous urticaria, and its association with both IL-5 and anti-IL-5 treatment options. We then review the current literature on these diseases, explain where appropriate potential reasons why anti-IL-5 treatments are ineffective, and then point out possible future directions for further research.

Antibody-based therapeutics for chronic rhinosinusitis with nasal polyps

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a prevalent inflammatory condition with heterogenous underlying endotypes, the most common being type 2 mediated inflammation. Several biologics have been developed to target specific pro-inflammatory cytokines and their receptors with proven efficacy in both quantitative and qualitative outcomes in patients with severe uncontrolled disease. However, there is an ongoing debate on the role of biologics relative to conventional therapies for CRSwNP and their efficacy in patient subgroups with non-polyp type 2 disease.

AREAS COVERED

This review examines the evidence on the efficacy and safety of biologics in CRSwNP, recommendations for their use, and discusses the broader economic factors influencing their application in clinical practice.

EXPERT OPINION

Emerging real-life data demonstrating the variable efficacy of the available biologics for patients with CRSwNP, coupled with the high cost compared to conventional therapies such as surgery, renders biologics to be considered as an add-on therapy in the majority of cases. However, ongoing research into increasing biologic dose intervals and novel therapies targeting alternative pathways may offer a more cost-effective and sustainable option in future.

Clinical feature-based diagnosis criteria of eosinophil and non-eosinophil chronic rhinosinusitis in Taiwan

Background

The prevalence of eosinophilic chronic rhinosinusitis (ECRS) has increased in Taiwan with a higher recurrence rate of nasal polyps after surgery. Therefore, we aimed to formulate the pre-operative diagnostic criteria for patients with ECRS in Taiwan.

Methods

This case-control study included patients diagnosed with CRS with nasal polyps (CRSwNP) who underwent functional endoscopic sinus surgery (FESS) at a tertiary hospital in Taiwan. The patients were classified into ECRS and non-eosinophilic CRS (NECRS) groups based on their histopathology. Demographic data, symptom severity scores, and computed tomography findings of the two groups were analyzed. We utilized receiver operating characteristic curve (ROC) analysis to evaluate parameters that could predict the diagnosis of ECRS.

Results

Total 408 CRSwNP patients were enrolled (ECRS group: 163; NECRS group: 245). ECRS group was strongly associated with asthma (6.1% vs. 2.0%, p = .03), higher blood eosinophil counts (4.3% vs. 2.7%, p < .01), higher serum IgE (285.3 vs. 50.2 IU/mL, p = .02), and higher 22-item Sino-Nasal Outcome Test (SNOT-22) score (40.5 vs. 36.7, p = .03). The ECRS criteria based on ROC curve included the SNOT-22 (>45, 2 points), serum eosinophil count percentage (>4%, 4 points), asthma (4 points), total serum IgE (>140 IU/mL, 4 points), Lund-Mackay score (>9.5, 4 points), and ethmoid-to-maxillary opacification ratio on CT (>1.5, 5 points). The cutoff score was 14 points (sensitivity, 70.2%; specificity, 93.3%).

Conclusions

Clinical-feature-based criteria may predict the diagnosis of ECRS before FESS in Taiwan.

Level of Evidence

Level 3.

Innovative treatments for severe uncontrolled chronic rhinosinusitis with nasal polyps

INTRODUCTION

In recent years, endotypes of chronic rhinosinusitis (CRS) based on the underlying immune mechanisms provided a better understanding of this heterogeneous disease and are frequently applied in diagnosis and treatment.

AREAS COVERED

In this manuscript, we aim to review novel treatment approaches for this often uncontrolled disease and highlight endotype-driven medical algorithms that could be beneficial in daily clinical practice.

EXPERT OPINION

With the development of endotyping and the mucosal inflammatory concept, several type 2-targeted biologics and surgical options are nowadays available for treating CRS. However, a better understanding based on clinical trials and real-life experience in daily practice is needed to optimize patient selection, biological drug selection, treatment duration, prediction, and long-term follow-up strategies. Indirect comparison analysis suggested that dupilumab might be the most effective biologic for treating CRS with nasal polyps, but the role and timing of surgery remain unclear. More real-life studies and comparative trials are needed for the optimal integration of biologics into clinical pathways in combination with established treatment approaches such as nasal and oral glucocorticosteroids and adequate surgery to provide long-term perspectives.

The Role of Biologics in the Treatment of Chronic Rhinosinusitis

The last decade has seen significant developments in the field of biologics for the treatment of chronic rhinosinusitis with nasal polyps (CRSwNP). Translational research borne from knowledge of the pathophysiology of type 2 inflammatory disease of the lower airways and the strong association with CRSwNP, has led to major therapeutic breakthroughs, with phase 3 trials of four biologics completed at the time of writing, and more underway. This article explores the evidence behind biologics for CRSwNP, the guidance on their use and the health economic factors influencing their position amongst the established therapeutic options for this common chronic condition.

Eosinophilic Airway Diseases: From Pathophysiological Mechanisms to Clinical Practice

Eosinophils play a key role in airway inflammation in many diseases, such as allergic and non-allergic asthma, chronic rhinosinusitis with nasal polyps, and chronic obstructive pulmonary disease. In these chronic disabling conditions, eosinophils contribute to tissue damage, repair, remodeling, and disease persistence through the production a variety of mediators. With the introduction of biological drugs for the treatment of these respiratory diseases, the classification of patients based on clinical characteristics (phenotype) and pathobiological mechanisms (endotype) has become mandatory. This need is particularly evident in severe asthma, where, despite the great scientific efforts to understand the immunological pathways underlying clinical phenotypes, the identification of specific biomarkers defining endotypes or predicting pharmacological response remains unsatisfied. In addition, a significant heterogeneity also exists among patients with other airway diseases. In this review, we describe some of the immunological differences in eosinophilic airway inflammation associated with severe asthma and other airway diseases and how these factors might influence the clinical presentation, with the aim of clarifying when eosinophils play a key pathogenic role and, therefore, represent the preferred therapeutic target.