Local receptor revision and class switching to IgE in chronic rhinosinusitis with nasal polyps

S. aureus biofilm properties correlate with immune B cell subset frequencies and severity of chronic rhinosinusitis

Staphylococcus aureus mucosal biofilms are associated with recalcitrant chronic rhinosinusitis (CRS). However, S. aureus colonisation of sinus mucosa is frequent in the absence of mucosal inflammation. This questions the relevance of S. aureus biofilms in CRS etiopathogenesis. This study aimed to investigate whether strain-level variation in in vitro-grown S. aureus biofilm properties relates to CRS disease severity, in vitro toxicity, and immune B cell responses in sinonasal tissue from CRS patients and non-CRS controls. S. aureus clinical isolates, tissue samples, and matched clinical datasets were collected from CRS patients with nasal polyps (CRSwNP), CRS without nasal polyps (CRSsNP), and controls. B cell responses in tissue samples were characterised by FACS. S. aureus biofilms were established in vitro, followed by measuring their properties of metabolic activity, biomass, colony-forming units, and exoprotein production. S. aureus virulence was evaluated using whole-genome sequencing, mass spectrometry and application of S. aureus biofilm exoproteins to air-liquid interface cultures of primary human nasal epithelial cells (HNEC-ALI). In vitro S. aureus biofilm properties were correlated with increased CRS severity scores, infiltration of antibody-secreting cells and loss of regulatory B cells in tissue samples. Biofilm exoproteins from S. aureus with high biofilm metabolic activity had enriched virulence genes and proteins, and negatively affected the barrier function of HNEC-ALI cultures. These findings support the notion of strain-level variation in S. aureus biofilms to be critical in the pathophysiology of CRS.

Pathogenesis-based application of biologics for chronic rhinosinusitis: Current and future perspectives

Chronic rhinosinusitis (CRS) is heterogeneous and contains diverse pathogenesis including type 1, type 2, and/or type 3 inflammation. For severe type 2 CRS especially CRS with nasal polyps (CRSwNP), biologics that target inflammatory molecules have recently been applied along with further changes in the treatment algorithm for CRS. Currently, a completed phase 3 clinical trial for biologics for severe CRSwNP with inadequate response to surgery and/or intranasal corticosteroids, including omalizumab (anti-IgE), mepolizumab (anti-IL-5), benralizumab (anti-IL-5Rα), and dupilumab (anti-IL-4Rα), have all shown efficacy. Similar phase 3 clinical trials for tezepelumab (anti-TSLP) and etokimab (anti-IL-33) are now underway and completed, respectively. Further studies need to evaluate how to optimally and cost-effectively use biologics for CRS and determine if any biomarkers are indicative of which biologics should be administered. A definition of complete and/or clinical remission of CRS is also needed to determine when to reduce or discontinue biologics. In addition, more precise basic research on CRS, such as endotyping and genotyping, will need to be undertaken in order to determine novel targets for biologics.

Staphylococcus aureus lysate induces an IgE response via memory B cells in nasal polyps

BACKGROUND

Locally increased IgE levels plays a pathologic role in chronic rhinosinusitis with nasal polyps (CRSwNP).

OBJECTIVE

This study aimed to investigate whether Staphylococcus aureus could induce aberrant IgE synthesis in CRSwNP and the potential mechanisms involved.

METHODS

Total IgE, IL-4, IL-5, and IL-13 concentrations in the supernatants of the cultures stimulated with S aureus lysate were assessed by ELISA. S aureus-induced cellular responses were investigated by single-cell RNA sequencing. Flow cytometry and quantitative reverse transcription PCR were used to analyze B-cell subsets and stimulated cell ε-germline transcript expression, respectively. IgE-positive B-cell and germinal center localization were assessed by immunohistochemistry and immunofluorescence.

RESULTS

S aureus lysate induced IgE production in the supernatants of nasal polyp (NP) tissues but not in those of healthy nasal mucosa. Moreover, IgE levels increased from days 2 to 4 after stimulation, paralleling the enhanced ε-germline transcript, IL-5, and IL-13 expression. Single-cell RNA sequencing revealed that there were increased IL-5 and IL-13 in group 2 innate lymphoid cells and identified a clonal overlap between unstimulated memory B cells and S aureus-stimulated plasma cells. The enriched IgE within NPs was mainly produced by IgE-negative memory B cells. Cellular evidence indicated that the IgE memory response to S aureus might also exist in the peripheral blood of CRSwNP patients. The S aureus-induced IgE memory response was associated with elevated IgE levels in NPs, asthma, and postoperative CRSwNP recurrence.

CONCLUSIONS

S aureus induced an IgE response via IgE-negative memory B cells in CRSwNP patients, possibly contributing to CRSwNP development.

Chronic rhinosinusitis with nasal polyps: eosinophils versus B lymphocytes in disease pathogenesis

PURPOSE OF REVIEW

To highlight the current evidence that supports the view that eosinophils may not drive disease in chronic rhinosinusitis with nasal polyps (CRSwNP) and the emerging evidence for B cells as an important player in this disease.

RECENT FINDINGS

Eosinophil depletion studies in CRSwNP do not fully support a critical role for eosinophils in CRSwNP. Almost complete eosinophil depletion with dexpramipexole had no impact on polyp size reduction or clinical improvement. Anti-interleukin (IL)-5 and IL-5Rα inhibition were more effective though with less clinical impact when compared to anti-immunoglobulin E (IgE) or IL-4Rα inhibition strategies. As IL-5Rα is also expressed on CRSwNP derived IgE+ and IgG4+ plasma cells to the same extent as eosinophils, improvements in CRSwNP with IL-5 inhibition may suggest a role for B cells over eosinophils in CRSwNP. We review both eosinophils and B cells in the context of CRSwNP and highlight the current evidence that supports an emerging role for B cells.

SUMMARY

Despite many aspects of immunopathology in CRSwNP explainable by B cell dysfunction, B cells have so far been ignored in CRSwNP. Further work is needed, as targeting B cells may offer an exciting new therapeutic option in the future.

We are memory: B-cell responses in allergy and tolerance

The significance of B-cell memory in sustaining IgE-mediated allergies but also ensuring the development of long-term allergen tolerance has remained enigmatic. However, well-thought murine and human studies have begun to shed more light on this highly disputed subject. The present mini review highlights important aspects, like the involvement of IgG1 memory B cells, the meaning of low- or high-affinity IgE antibody production, the impact of allergen immunotherapy, or the relevance of local memory established by ectopic lymphoid structures. Based on recent findings, future investigations should lead to deeper knowledge and the development of improved therapies treating allergic individuals.

Novel insights into central compartment atopic disease - a literature review

INTRODUCTION

Central compartment atopic disease (CCAD) is a newly recognized variant subtype of chronic rhinosinusitis (CRS). Although CCAD has been reported to be correlated with allergy, there is still a considerable gap in our knowledge regarding CCAD.

AREAS COVERED

We have conducted a thorough analysis of the literature on CCAD. This review provides current understanding and therapeutic strategies of CCAD. In this article, we will review the clinical presentations and parameters, allergy-related etiology, endotypes, and recommended management of CCAD.

EXPERT OPINION

CCAD is considered as an aeroallergen-driven type 2/eosinophilic inflammatory pattern. Although CCAD can be diagnosed by endoscopy and radiology, as well as allergen test, pathogenesis and management strategies leave much to be desired, and further studies are needed.

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.

Involvement of CD40-CD40L and ICOS-ICOSL in the development of chronic rhinosinusitis by targeting eosinophils

Background

Chronic rhinosinusitis (CRS), whose prevalence and pathogenesis are age-related, is characterized by nasal tissue eosinophil infiltration. CD40-CD40 ligand (CD40L) pathway involves in the eosinophil-mediated inflammation, and inducible co-stimulator (ICOS)-ICOS ligand (ICOSL) signal can strengthen CD40-CD40L interaction. Whether CD40-CD40L and ICOS-ICOSL have a role in the development of CRS remains unknown.

Objectives

The aim of this study is to investigate the association of CD40-CD40L and ICOS-ICOSL expression with CRS and underlying mechanisms.

Methods

Immunohistology detected the expression of CD40, CD40L, ICOS, and ICOSL. Immunofluorescence was performed to evaluate the co-localizations of CD40 or ICOSL with eosinophils. Correlations between CD40-CD40L and ICOS-ICOSL as well as clinical parameters were analyzed. Flow cytometry was used to explore the activation of eosinophils by CD69 expression and the CD40 and ICOSL expression on eosinophils.

Results

Compared with the non-eCRS subset, ECRS (eosinophilic CRS) subset showed significantly increased CD40, ICOS, and ICOSL expression. The CD40, CD40L, ICOS, and ICOSL expressions were all positively correlated with eosinophil infiltration in nasal tissues. CD40 and ICOSL were mainly expressed on eosinophils. ICOS expression was significantly correlated with the expression of CD40-CD40L, whereas ICOSL expression was correlated with CD40 expression. ICOS-ICOSL expression positively correlated with blood eosinophils count and disease severity. rhCD40L and rhICOS significantly enhanced the activation of eosinophils from patients with ECRS. Tumor necrosis factor-α (TNF-α) and interleukin-5 (IL-5) obviously upregulated CD40 expression on eosinophils, which was significantly inhibited by the p38 mitogen-activated protein kinase (MAPK) inhibitor.

Conclusions

Increased CD40-CD40L and ICOS-ICOSL expressions in nasal tissues are linked to eosinophils infiltration and disease severity of CRS. CD40-CD40L and ICOS-ICOSL signals enhance eosinophils activation of ECRS. TNF-α and IL-5 regulate eosinophils function by increasing CD40 expression partly via p38 MAPK activation in patients with CRS.

Autoimmunity: A New Focus on Nasal Polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) has long been considered a benign, chronic inflammatory, and hyperplastic disease. Recent studies have shown that autoimmune-related mechanisms are involved in the pathology of nasal polyps. Activated plasma cells, eosinophils, basophils, innate type 2 lymphocytes, mast cells, and proinflammatory cytokine in polyp tissue indicate the mobilization of innate and adaptive immune pathways during polyp formation. The discovery of a series of autoantibodies further supports the autoimmune nature of nasal polyps. Local homeostasis dysregulation, infection, and chronic inflammation may trigger autoimmunity through several mechanisms, including autoantigens overproduction, microbial translocation, molecular mimicry, superantigens, activation or inhibition of receptors, bystander activation, dysregulation of Toll-Like Receptors (TLRs), epitope spreading, autoantigens complementarity. In this paper, we elaborated on the microbiome-mediated mechanism, abnormal host immunity, and genetic changes to update the role of autoimmunity in the pathogenesis of chronic rhinosinusitis with nasal polyps.

B Lineage Cells and IgE in Allergic Rhinitis and CRSwNP and the Role of Omalizumab Treatment

BACKGROUND

Allergic rhinitis (AR) and chronic rhinosinusitis (CRS) are two prevalent nasal diseases where both type 2 inflammation and immunoglobulin E (IgE) may play important roles. Although they can exist independently or comorbidly, subtle but important differences exist in immunopathogenesis.

OBJECTIVE

To summarize current knowledge of pathophysiological roles of B lineage cells and IgE in AR and CRS with nasal polyps (CRSwNP).

METHODS

Searched PubMed database, reviewed AR and CRSwNP-related literature, and discussed disease diagnosis, comorbidity, epidemiology, pathophysiology, and treatment. Similarities and differences in B-cell biology and IgE are compared in the 2 conditions.

RESULTS

Both AR and CRSwNP have evidence for pathological type 2 inflammation, B-cell activation and differentiation, and IgE production. However, distinctions exist in the clinical and serological profiles at diagnosis, as well as treatments utilized. B-cell activation in AR may more frequently be regulated in the germinal center of lymphoid follicles, whereas CRSwNP may occur via extrafollicular pathways although controversies remain in these initial activating events. Oligoclonal and antigen-specific IgE maybe predominate in AR, but polyclonal and antigen-nonspecific IgE may predominate in CRSwNP. Omalizumab has been shown efficacious in treating both AR and CRSwNP in multiple clinical trials but is the only Food and Drug Administration-approved anti-IgE biologic to treat CRSwNP or allergic asthma. Staphylococcus aureus frequently colonizes the nasal airway and has the ability to activate type two responses including B-cell responses although the extent to which it modulates AR and CRSwNP disease severity is being investigated.

CONCLUSION

This review highlights current knowledge of the roles of B cells and IgE in the pathogenesis of AR and CRSwNP and a small comparison between the 2 diseases. More systemic studies should be done to elevate the understanding of these diseases and their treatment.

Clinical characteristics of central compartment atopic disease in Southern China

BACKGROUND

Central compartment atopic disease (CCAD) is a newly reported subset of chronic rhinosinusitis. It was considered associated with inhalant antigen. However, CCAD in Chinese population is not fully studied yet.

DESIGN

Prospective cohort study.

OBJECTIVE

This study aimed to describe the clinical manifestations of CCAD and compared the following two subtypes: sinonasal polyps and concomitant polypoid disease in the central compartment (CRSwNP/CC) and CRSwNP not otherwise specified (CRSwNP NOS). Also, we compared the clinical manifestations of atopy CCAD and non-atopy CCAD.

METHODS

We consecutively enrolled CRSwNP patients without prior sinus surgery, and assessed the nasal endoscopy and computed tomography of the paranasal sinuses. Allergy was confirmed by skin or serum testing. Eosinophilic CRSwNP (ECRS) was considered as tissue eosinophils to total inflammatory cells >10%.

RESULTS

We enrolled a total of 116 patients, including 39 with CCAD, 38 with CRSwNP/CC and 39 with CRSwNP NOS. Atopy was detected in 37.1% of the CCAD group, an incidence showing no significant difference from those in the other two groups (37.1% in the CRSwNP/CC group, 31.0% in the CRSwNP NOS group; p = 0.846). However, the incidence of ECRS in the CCAD group was the highest among the different groups (97.4% in the CCAD group vs. 67.6% in the CRSwNP/CC group vs. 35.1% in the CRSwNP NOS group; p = 0.000). In addition, the incidence of asthma in the CCAD group (33.3%) was significantly higher than that in the CRSwNP NOS group (10.3%), but quite similar to CRSwNP/CC (34.2%). In the subgroup analysis of CCAD, only total serum IgE and sIgE demonstrated significant differences between atopy CCAD and non-atopy CCAD.

CONCLUSION

CCAD in Southern China may associate with asthma and significant eosinophilia, with a lower incidence of systemic allergy based on skin and serum testing.

IgE+ plasmablasts predict the onset of clinical allergy

Introduction

IgE+ plasmablasts develop following allergen exposure and B cell activation. They secrete IgE and therefore are directly linked to maintain the mechanisms of IgE-mediated allergies. Here, we show that the presence of IgE+ plasmablasts in peripheral blood not only coincides with clinical allergy, but also predicts the upcoming development of clinical disease.

Methods

Using an equine model of naturally occurring allergy, we compared the timing of allergen exposure, arrival of IgE+ plasmablasts in peripheral blood, and onset of clinical disease.

Results

We found that IgE+ plasmablasts predict the development of clinical allergy by at least 3 weeks and can be measured directly by flow cytometry or by IgE secretion following in vitro culture. We also compared the IgE secretion by IgE+ plasmablasts with total plasma IgE concentrations and found that while IgE secretion consistently correlates with clinical allergy, total plasma IgE does not.

Discussion

Together, we describe IgE+ plasmablasts as a reliable and sensitive predictive biomarker of allergic disease development.

The link between allergic rhinitis and chronic rhinosinusitis

PURPOSE OF REVIEW

Allergic rhinitis and chronic rhinosinusitis (CRS) are common disorders affecting millions of people worldwide. Although allergic rhinitis and CRS are distinct clinical entities, certain CRS endotypes share similar pathological mechanisms as those seen in patients with allergic rhinitis. This review assesses the literature behind the similarities and differences seen in patients with CRS and allergic rhinitis, and the role atopy might play in the pathophysiology of CRS.

RECENT FINDINGS

In examining the associations between allergic rhinitis and CRS, most studies have focused primarily on CRS with nasal polyps and type 2 inflammation in CRS. Recent studies have demonstrated the similarities and differences in pathologic mechanisms behind allergic rhinitis and CRS, with an emphasis on patient endotypes, genetics, and the nasoepithelial immunologic barrier. Related immunopathology shared by allergic rhinitis and type 2 inflammation in CRS has allowed for therapeutic overlap with biologic treatments.

SUMMARY

Allergic rhinitis and CRS often present as comorbid conditions, and understanding the relationship between allergic rhinitis and CRS is important when considering treatment options. Advances in understanding the genetics and immunology, as well as biologic and immunotherapeutic treatments have improved outcomes in patients with CRS, especially in the setting of atopy.

Local Immunoglobulin E in nasal polyps: Role and modulation

In the airway, IgE is traditionally regarded as a key mediator in allergic diseases, such as AR and allergic asthma. However, growing evidence demonstrates the importance of local IgE in airway inflammatory diseases, irrespective of the presence of allergy. In this review, we discuss the most recent evidence for IgE in chronic rhinosinusitis with nasal polyps(CRSwNP), including the local IgE’s characteristics, the modulation of its synthesis, and its function. The levels of local IgE are significantly elevated in polyps independently of IgE serum levels and atopic status. Local IgE, which is correlated with type 2 inflammation, is polyclonal and functional. IgE is produced by active B cells and is dependent on the class switch recombination(CSR). In NPs, this process is triggered by not only allergens but also microbial colonization, especially the superantigen- Staphylococcus aureus. The production of local IgE is modulated by lymphocytes(such as Tfh, ILC2s, iTreg), cytokines(such as IL-4, IL-13, IFN-γ, TGF-β, IL-2, IL-21), transcription factors, and B cell-intrinsic factor. Due to the central role of IgE in NPs, it is regarded as an ideal target for therapy and has been proved to be clinically successful. Based on this knowledge, we believe that exploring the trigger and regulatory factors for the activation of local B cells and CSR to IgE will provide more valuable information for us to recognize the pathological mechanisms of local IgE and offer the possible option for new therapeutic targets of nasal polyps.

Sequential class switch recombination to IgE and allergen-induced accumulation of IgE+ plasmablasts occur in the nasal mucosa of local allergic rhinitis patients

BACKGROUND

The involvement of allergen-specific (s)IgE in local allergic rhinitis (LAR) has been debated. Here, we investigate the effect of nasal allergen challenge with Dermatophagoides pteronyssinus (NAC-DP) in mucosal and peripheral B-cell subpopulations in LAR patients.

METHODS

Nine LAR, 5 allergic rhinitis (AR), and 5 non-atopic healthy control (HC) individuals were subjected to a 3-day NAC-DP protocol, and nasal biopsies and blood samples were collected before and after provocation. Nasal biopsies were used for immunohistochemistry and gene expression studies, whereas the frequency of lymphocyte subsets and basophil activation test (BAT) were analyzed in blood samples by flow cytometry. sIgG was measured in sera.

RESULTS

NAC-DP induced an increase in IgE⁺ CD38⁺ plasmablasts in the nasal mucosa of LAR patients, but not in AR or HC individuals. Markers of sequential recombination to IgE (εCSR) (from IgG) were observed in 33% of LAR, 20% of AR, and 0% of HC subjects. NAC-DP increased the proportion of peripheral CD19⁺ CD20⁺ CD38⁺ plasmablasts in AR and LAR patients, but not in HC. Expression of the mucosal homing receptor CXCR3 in peripheral CD19⁺ CD20⁺ CD38⁺ plasmablasts from LAR, AR, and HC individuals was 7%, 5%, and 0.5%, respectively. In vitro DP stimulation increased proliferating CD19⁺ CD20⁺ CD38⁺ plasmablasts in LAR and AR patients, but not in HC. Serum DP-sIgG was higher in LAR and AR patients as compared to HC. BAT was positive in 33%, 100%, and 0% of LAR, AR, and HC subjects, respectively.

CONCLUSION

These results suggest that allergen exposure induces the sequential εCSR of IgG⁺ CD19⁺ CD20⁺ CD38⁺ plasmablasts in the nasal mucosa of LAR patients.

Chronic and Recurrent Sinusitis in Children, as Manifestation of Immune Dysfunction and Atopic Background

Rhinosinusitis in children, as in adults, can be classified by duration (acute, recurrent, and chronic) and by cause (viral, bacterial, and inflammatory) and needs to be treated accordingly after careful investigation which include through clinical history, laboratory tests, and, if necessary, nasal endoscopy and imaging studies.

Early IgE Production Is Linked with Extrafollicular B- and T-Cell Activation in Low-Dose Allergy Model

Despite its paramount importance, the predominant association of early IgE production with harmless antigens, via germinal-center B- and T-cell subpopulations or extrafollicular activation, remains unresolved. The aim of this work was to clarify whether the reinforced IgE production following the subcutaneous immunization of BALB/c mice with low antigen doses in withers adipose tissue might be linked with intensified extrafollicular or germinal-center responses. The mice were immunized three times a week for 4 weeks in the withers region, which is enriched in subcutaneous fat and tissue-associated B cells, with high and low OVA doses and via the intraperitoneal route for comparison. During long-term immunization with both low and high antigen doses in the withers region, but not via the intraperitoneal route, we observed a significant accumulation of B220-CD1d-CD5-CD19+ B-2 extrafollicular plasmablasts in the subcutaneous fat and regional lymph nodes but not in the intraperitoneal fat. Only low antigen doses induced a significant accumulation of CXCR4+ CXCR5- CD4+ extrafollicular T helpers in the withers adipose tissue but not in the regional lymph nodes or abdominal fat. Only in subcutaneous fat was there a combination of extrafollicular helper accumulation. In conclusion, extrafollicular B- and T-cell activation are necessary for early IgE class switching.

Chronic Rhinosinusitis, S. aureus Biofilm and Secreted Products, Inflammatory Responses, and Disease Severity

Chronic rhinosinusitis (CRS) is a persistent inflammation of the nasal cavity and paranasal sinuses associated with tissue remodelling, dysfunction of the sinuses’ natural defence mechanisms, and induction of different inflammatory clusters. The etiopathogenesis of CRS remains elusive, and both environmental factors, such as bacterial biofilms and the host’s general condition, are thought to play a role. Bacterial biofilms have significant clinical relevance due to their potential to cause resistance to antimicrobial therapy and host defenses. Despite substantial medical advances, some CRS patients suffer from recalcitrant disease that is unresponsive to medical and surgical treatments. Those patients often have nasal polyps with tissue eosinophilia, S. aureus-dominant mucosal biofilm, comorbid asthma, and a severely compromised quality of life. This review aims to summarise the contemporary knowledge of inflammatory cells/pathways in CRS, the role of bacterial biofilm, and their impact on the severity of the disease. Here, an emphasis is placed on S. aureus biofilm and its secreted products. A better understanding of these factors might offer important diagnostic and therapeutic perceptions for recalcitrant disease.

The development of the mucosal concept in chronic rhinosinusitis and its clinical implications

In the last 2 decades, an increasing understanding of pathophysiological mechanisms in chronic rhinosinusitis opened an avenue from phenotyping to endotyping, from eosinophilic inflammation to type 2 immunity, and from the "ventilation and drainage" paradigm to the mucosal concept for therapeutic considerations. With the advent of type 2 endotyping and targeted biomarkers, precise endotype-driven therapeutic options are possible including biologics and adapted surgical approaches. We here aim to focus on the complexity and heterogeneity of the features of chronic rhinosinusitis (CRS) endotypes, especially for those with nasal polyps, including its history, latest developments, clinical associations and endotype-driven solutions. In order to better manage uncontrolled severe CRS in clinical practice, medical decisions based on a profound understanding of the pathology and immunology of this heterogeneous disease, aiding a precision-medicine based approach for patient's treatment are pivotal.

Positionspapier: Empfehlungen zur Anwendung von Omalizumab bei chronischer Rhinosinusitis mit Polyposis nasi (CRSwNP) im deutschen Gesundheitssystem – Empfehlungen des Ärzteverbandes Deutscher Allergologen (AeDA) und der AGs Klinische Immunologie, Allergologie und Umweltmedizin und Rhinologie und Rhinochirurgie der Deutschen Gesellschaft für HNO-Heilkunde, Kopf- und Halschirurgie (DGHNOKHC)

Hintergrund Die chronische Rhinosinusitis mit Nasenpolypen (CRSwNP) ist eine multifaktorielle entzündliche Erkrankung der paranasalen Schleimhäute, der als Endotyp meistens eine TH2-Inflammation zugrunde liegt. IgE-Antikörper spielen dabei eine wichtige Rolle. Der anti-IgE-Antikörper Omalizumab wurde im August 2020 für die Therapie der schweren CRSwNP zugelassen.

Methoden In einer Literatursuche wurde die Immunologie der CRSwNP analysiert und die Evidenz zur Wirkung von Omalizumab bei dieser Erkrankung ermittelt durch Recherchen in Medline, Pubmed sowie den nationalen und internationalen Studien- und Leitlinien-Registern und der Cochrane Library.

Ergebnisse Basierend auf diesen Angaben aus der internationalen Literatur werden von einem Expertengremium Empfehlungen für die Anwendung von Omalizumab bei CRSwNP im deutschen Gesundheitssystem gegeben.

Schlussfolgerung Omalizumab ist zugelassen für Patienten ab 18 Jahren mit schwerer chronischer Rhinosinusitis mit Nasenpolypen als Zusatztherapie zu intranasalen Kortikosteroiden (INCS), wenn durch eine Therapie mit INCS keine ausreichende Krankheitskontrolle erzielt werden kann.

The Role of IgE in Upper and Lower Airway Disease: More Than Just Allergy!

Immunoglobulin E (IgE) is a well-known key factor in allergic airway disease; however, its central role in non-allergic airway inflammation is often underestimated. In some airway diseases, IgE is produced as a result of allergic sensitization. However, in others, IgE production occurs despite the lack of a specific allergen. Although multiple pathways contribute to the production of IgE in airway disease, it is its activity in mediating the inflammatory response that is associated with disease. Therefore, an understanding of IgE as the unifying component of upper and lower airway diseases has important implications for both diagnosis and treatment. Understanding the role of IgE in each upper and lower airway disease highlights its potential utility as a diagnostic marker and therapeutic target. Further classification of these diseases by whether they are IgE mediated or non–IgE mediated, rather than by the existence of an underlying allergic component, accounts for both systemic and localized IgE activity. Improvements in diagnostic methodologies and standardization of clinical practices with this classification in mind can help identify patients with IgE-mediated diseases. In doing so, this group of patients can receive optimal care through targeted anti-IgE therapeutics, which have already demonstrated efficacy across numerous IgE-mediated upper and lower airway diseases.

Extrafollicular IgD+ B cells generate IgE antibody secreting cells in the nasal mucosa

Increased IgE is a typical feature of allergic rhinitis. Local class-switch recombination has been intimated but B cell precursors and mechanisms remain elusive. Here we describe the dynamics underlying the generation of IgE-antibody secreting cells (ASC) in human nasal polyps (NP), mucosal tissues rich in ASC without germinal centers (GC). Using VH next generation sequencing, we identified an extrafollicular (EF) mucosal IgD+ naïve-like intermediate B cell population with high connectivity to the mucosal IgE ASC. Mucosal IgD+ B cells, express germline epsilon transcripts and predominantly co-express IgM. However, a small but significant fraction co-express IgG or IgA instead which also show connectivity to ASC IgE. Phenotypically, NP IgD+ B cells display an activated profile and molecular evidence of BCR engagement. Transcriptionally, mucosal IgD+ B cells reveal an intermediate profile between naïve B cells and ASC. Single cell IgE ASC analysis demonstrates lower mutational frequencies relative to IgG, IgA, and IgD ASC consistent with IgE ASC derivation from mucosal IgD+ B cell with low mutational load. In conclusion, we describe a novel mechanism of GC-independent, extrafollicular IgE ASC formation at the nasal mucosa whereby activated IgD+ naïve B cells locally undergo direct and indirect (through IgG and IgA), IgE class switch.

Involvement of inflammatory cells in chronic rhinosinusitis with nasal polyps

Inflammation plays an important role in the pathogenesis of nasal polyps. Understanding the biomolecular action mechanisms of inflammatory elements can contribute to improving the prognosis of these lesions. The study analyzed the distribution and immunohistochemically quantified eosinophils [eosinophil major basic protein (BMK-13)], lymphocytes [cluster of differentiation (CD) 4, CD8, CD20] and plasmocytes (CD138) in both the epithelial and stromal compartment in relation to composite scores, which included specific histopathological parameters for 50 sinonasal polyps. Inflammatory elements predominated at stromal level, the high histological composite scores being frequently associated with increased expression of inflammatory elements. Also, the numerical distribution of inflammatory elements indicated positive linear relations within the groups BMK-13/CD8 and CD4/CD20/CD138, and a negative linear relation between the two groups. This aspect can support the existence of alternative or sequential pathogenic mechanisms involved in the pathogenesis of sinonasal polyps, and the results obtained can be used for a better stratification of patients in order to optimize the therapy.

B cells and upper airway disease: allergic rhinitis and chronic rhinosinusitis with nasal polyps evaluated

Introduction: The first mucosal site to encounter inhaled allergen, antigen, and microbes is the upper airway. It must perforce have a rapid system of environmental threat recognition and self-defense. B cells play a critical role in such airway host-defense, tissue surveillance, and immune modulation. Several common upper airway diseases can be defined in the expression of either exaggerated or dysregulated B-cell function within T2-high mucosal inflammatory states.Areas covered: In this review, the authors discuss the immunology of allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP) in the context of highlighting key aspects of B-cell biology and function. The review is based on the findings of a literature search using the terms B cells, rhinitis, nasal polyps, and rhinosinusitis.Expert opinion: Despite the emerging role of B-cell overdrive and dysfunction in upper airway disease, studies are lacking specifics to B cells, particularly in association with sinonasal infection and mucosal inflammation. There is a pressing need to focus on how respiratory inflammation, alongside impaired or exaggerated B-cell function, amplifies and further dysregulates immune signaling pathways in the disease setting of AR and CRSwNP.

What is the contribution of IgE to nasal polyposis?

Taking a novel approach, this narrative review collates knowledge about nasal polyposis and the biological functions of IgE in several diseases (allergic rhinitis, allergic asthma, nonsteroidal anti-inflammatory drugs-exacerbated respiratory disease, and chronic spontaneous urticaria) to consider which IgE-mediated mechanisms are relevant to nasal polyposis pathology. A type 2 eosinophil-dominated inflammatory signature is typical in nasal polyp tissue of European patients with nasal polyposis, with a shift toward this endotype observed in Asian populations in recent years. Elevated polyclonal IgE is present in the nasal tissue of patients with and without allergy. It is derived from many different B-cell clones and, importantly, is functional (proinflammatory). Staphylococcus aureus enterotoxins are thought to act as superantigens, inducing production of polyclonal IgE via B-cell and T-cell activation, and triggering release of inflammatory mediators. In some patients, exposure to antigens/triggers leads to production of high levels of antigen-specific IgE, which mediates cross-linking of the high-affinity IgE receptor on various cells, causing release of inflammatory mediators. The efficacy of omalizumab confirms IgE as an important inflammatory mediator in nasal polyposis. By blocking IgE, omalizumab targets the T2 inflammation in nasal polyposis, reduces nasal polyp score and improves symptoms.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

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

METHODS

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

RESULTS

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

CONCLUSION

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

Changes in Clinical and Histological Characteristics of Nasal Polyps in Northern China over the Past 2-3 Decades

INTRODUCTION

Recent studies have shown that inflammatory patterns of nasal polyps from patients with chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) in East Asia have changed over time. However, to date there is a marked lack of similar data for CRSwNP in Northern China. This study thus aimed to assess the changes in the clinical and histological characteristics of CRSwNP patients from Northern China over the past 2-3 decades.

METHODS

This was a retrospective study, which examined data from 2 groups of 150 CRSwNP patients each, who had undergone endoscopic sinus surgery in Beijing Tongren Hospital from 1993 to 1995 (group A) and from 2015 to 2019 (group B). All relevant data for demographic, clinical, and histological parameters were collected for each patient from the 2 groups and compared for overall changes between the 2 groups.

RESULTS

The comorbidity of CRSwNP and asthma increased over time and the cellular phenotype of CRSwNPchanged significantly; in particular, the proportion of eosinophil-dominant CRSwNP increased, lymphocyte-dominant and plasma-dominant CRSwNP decreased significantly, and the proportions of neutrophil-dominant and mixed CRSwNP were not altered. The rate of polyp recurrence increased in CRSwNP but did not in eosinophilic CRSwNP. Smoking and age did not significantly impact the inflammatory patterns of CRSwNP.

CONCLUSIONS

The inflammatory patterns of CRSwNP patients have changed and comorbidity of asthma significantly increased in CRSwNP patients in Northern China over the past 2-3 decades.

Roles of follicular helper and regulatory T cells in allergic diseases and allergen immunotherapy

Allergic diseases are characterized by overactive type 2 immune responses to allergens and immunoglobulin E (IgE)-mediated hypersensitivity. Emerging evidence suggests that follicular helper T (T_FH ) cells, rather than type 2 T-helper (T_H 2) cells, play a crucial role in controlling IgE production. However, follicular regulatory T (T_FR ) cells, a specialized subset of regulatory T (T_REG ) cells resident in B-cell follicles, restricts T_FH cell-mediated help in extrafollicular antibody production, germinal center (GC) formation, immunoglobulin affinity maturation, and long-lived, high-affinity plasma and memory B-cell differentiation. In mouse models of allergic asthma and food allergy, CXCR5⁺ T_FH cells, not CXCR5^- conventional T_H 2 cells, are needed to support IgE production, otherwise exacerbated by CXCR5⁺ T_FR cell deletion. Upregulation of T_FH cell activities, including a skewing toward type 2 T_FH (T_FH 2) and IL-13 producing T_FH (T_FH 13) phenotypes, and defects in T_FR cells have been identified in patients with allergic diseases. Allergen immunotherapy (AIT) reinstates the balance between T_FH and T_FR cells in patients with allergic diseases, resulting in clinical benefits. Collectively, further understanding of T_FH and T_FR cells and their role in the immunopathogenesis of allergic diseases creates opportunities to develop novel therapeutic approaches.

Chronic Rhinosinusitis with Nasal Polyps: Targeting IgE with Anti-IgE Omalizumab Therapy

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex, clinically heterogeneous and persistent inflammatory disorder of the upper airway. Detailed mechanistic insights into disease pathogenesis are lacking, but it is now accepted that local tissue IgE driven T2-high inflammatory pathways are critical to disease. The recent CRSwNP Phase 3 POLYP1 and POLYP2 replicate studies of blocking IgE with omalizumab confirmed rapid improvements in all clinical parameters of sinonasal disease, confirming a pivotal role for IgE driven inflammatory pathways in CRSwNP. This review summarises the biology of IgE in relation to CRSwNP. Insight into how IgE may drive CRSwNP is evaluated in the context of clinical improvements seen with omalizumab. The need for further studies using a broader patient and biomarker specific groups to aid more precise drug-patient selection alongside more detailed mechanistic studies of omalizumab in CRSwNP is highlighted.

Adult chronic rhinosinusitis

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

Local immunoglobulin production in nasal tissues: A key to pathogenesis in chronic rhinosinusitis with nasal polyps and aspirin-exacerbated respiratory disease

OBJECTIVE

Local activation of B cells and antibody production are important for protective and pathogenic immune responses. Furthermore, there is evidence that local activation of B cells and antibody production are important for pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) and a severe subset of CRSwNP, aspirin-exacerbated respiratory disease (AERD). This review summarizes these findings and the potential role of B cells and antibodies in disease pathogenesis.

DATA SOURCES

Published literature from PubMed searches.

STUDY SELECTIONS

Studies relevant to B cell development and the roles of B cells and antibodies in the pathogenesis of CRSwNP and AERD.

RESULTS

Formation of tertiary lymphoid structures plays a key role in the local activation of B cells and antibody production. This process is important for fighting infections, but it also contributes to autoimmune disease. Furthermore, there is evidence to support a role for local B cell activation and antibody production in a variety of allergic diseases. Nasal polyp tissues from patients with CRSwNP and AERD have elevated levels of activated B cell subsets and locally produced antibodies. These locally produced antibodies may contribute to disease pathogenesis in a variety of ways, including activation of innate effector cells, whereas locally activated B cells may contribute to pathogenesis through the activation of T cells.

CONCLUSION

More studies are needed to determine the role of B cells and antibodies in driving disease in these patients. However, targeting the processes that drive local B cell activation and antibody production may provide new therapeutic approaches and could help to reduce chronic inflammation.

Tertiary lymphoid structure related B-cell IgE isotype switching and secondary lymphoid organ linked IgE production in mouse allergy model

Background

Numerous data obtained by different research laboratories indicate that specific IgE production is triggered independently of specific IgG or IgA ones and so it is not linked to fully matured germinal centers formation in the secondary lymphoid organs. The aim of this study was to clarify whether specific IgE production is triggered by low antigen doses administrated in tertiary tissues enriched by lymphoid structures.

Methods

Ovalbumin (OVA) in different doses (100 ng to 10 μg) was administrated three times a week for 4–5 weeks intraperitoneally (i.p.) or subcutaneously (s.c.) to female BALB/c mice in the wither region which is enriched in fat-associated lymphoid clusters or in the foot pad region not containing them.

Results

OVA-specific IgE was predominantly induced by low but not high antigen doses and only after immunization into the withers. IgE isotype switching was triggered exclusively in the withers adipose tissue but not in the regional lymph nodes while mature IgE expressing cells were observed both in the withers and lymph nodes. Anti-proliferative genotoxic stress inducing drugs shifted the balance from IgG1 towards IgE production.

Conclusions

Tertiary lymphoid structures possess unique environment where B-cell antibody isotype switching to IgE predominantly occurs. This phenomenon is partially explained by hampered proliferation of B-cells in these structures.

Linking Complement C3 and B Cells in Nasal Polyposis

Nasal polyposis often is characterized by a persistent inflammation of the sinonasal mucosa, disease recurrence after medical or surgical intervention, and asthma comorbidity. Dysregulated complement activation may contribute to immunologic alterations and disease. To date, there is only scattered knowledge on the source and regulation of the central complement factors in the pathogenesis of nasal polyps. Here, we aim to study complement signatures, especially the C3-C3aR axis, and focus on cellular sources and targets in nasal polyps. Expression of complement factors, including C3, C5, and the anaphylatoxin receptors, was analyzed in nasal polyp tissue samples, the corresponding inferior turbinates, and healthy controls using transcriptomic methods and protein measurements. Distinct patterns of complement expression were found in nasal polyps compared to controls, characterized by an increased C3 activation and an increase in C3aR-bearing cells. In contrast, no difference was shown for epithelial-dependent C3 production. Besides low intracellular C3-expression levels for lymphocytes in general, we could identify an enlarged B lymphocyte population in nasal polyps displaying high amounts of intracellular C3. Our data suggest a prominent role for the C3-C3aR-axis in nasal polyps and, for the first time, describe a B cell population containing high levels of intracellular C3, suggesting a new role of B cells in the maintenance of the inflammation by complement.

Serum IgG4 as a biomarker reflecting pathophysiology and post-operative recurrence in chronic rhinosinusitis

BACKGROUND

Type 2 chronic rhinosinusitis (CRS), especially eosinophilic CRS (ECRS), is an intractable upper airway inflammatory disease. Establishment of serum biomarkers reflecting the pathophysiology of CRS is desirable in a clinical setting. As IgG4 production is regulated by type 2 cytokines, we sought to determine whether serum IgG4 levels can be used as a biomarker for CRS.

METHODS

Association between the serum IgG4 levels and clinicopathological factors was analyzed in 336 CRS patients. Receiver operating characteristics (ROC) analysis was performed to determine the cut-off value of serum IgG4 levels that can be used to predict the post-operative recurrence.

RESULTS

Serum IgG4 levels were significantly higher in patients with moderate to severe ECRS versus those with non to mild ECRS. The levels were also significantly higher in asthmatic patients and patients exhibiting recurrence after surgery compared to controls. ROC analysis determined that the best cut-off value for the serum IgG4 level to predict the post-operative recurrence was 95 mg/dL. The corresponding sensitivity and specificity were 39.7% and 80.5%, respectively. When we combined the two cut-off values for the serum IgG4 and periostin, patients with high serum levels of either IgG4 or periostin exhibited a high post-operative recurrence (OR: 3.95) as compared to patients having low serum levels of both IgG4 and periostin.

CONCLUSIONS

The present results demonstrate that the serum IgG4 level is associated with disease severity and post-operative course in CRS. In particular, the combination of serum IgG4 and periostin could be a novel biomarker that predicts post-operative recurrence.

Efficacy and safety of omalizumab in nasal polyposis: 2 randomized phase 3 trials

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by IgE hyperproduction and eosinophilic inflammation. The anti-IgE antibody, omalizumab, has demonstrated efficacy in patients with CRSwNP and comorbid asthma previously.

OBJECTIVE

Our aim was to determine omalizumab safety and efficacy in CRSwNP in phase 3 trials (POLYP 1 and POLYP 2).

METHODS

Adults with CRSwNP with inadequate response to intranasal corticosteroids were randomized (1:1) to omalizumab or placebo and intranasal mometasone for 24 weeks. Coprimary end points included change from baseline to week 24 in Nasal Polyp Score (NPS) and Nasal Congestion Score. Secondary end points included change from baseline to week 24 in Sino-Nasal Outcome Test-22 (SNOT-22) score, University of Pennsylvania Smell Identification Test, sense of smell, postnasal drip, runny nose, and adverse events.

RESULTS

Patients in POLYP 1 (n = 138) and POLYP 2 (n = 127) exhibited severe CRSwNP and substantial quality of life impairment evidenced by a mean NPS higher than 6 and SNOT-22 score of approximately 60. Both studies met both the coprimary end points. SNOT-22 score, University of Pennsylvania Smell Identification Test score, sense of smell, postnasal drip, and runny nose were also significantly improved for omalizumab versus placebo. In POLYP 1 and POLYP 2, the mean changes from baseline at week 24 for omalizumab versus placebo were as follows: NPS, -1.08 versus 0.06 (P < .0001) and -0.90 versus -0.31 (P = .0140); Nasal Congestion Score, -0.89 versus -0.35 (P = .0004) and -0.70 versus -0.20 (P = .0017); and SNOT-22 score, -24.7 versus -8.6 (P < .0001) and -21.6 versus -6.6 (P < .0001). Adverse events were similar between groups.

CONCLUSION

Omalizumab significantly improved endoscopic, clinical, and patient-reported outcomes in severe CRSwNP with inadequate response to intranasal corticosteroids, and it was well tolerated.

Dupilumab: Clinical Efficacy of Blocking IL-4/IL-13 Signalling in Chronic Rhinosinusitis with Nasal Polyps

In September 2019, The Lancet published details of two large Phase III double-blind placebo-controlled studies (LIBERTY NP SINUS-24 and LIBERTY NP SINUS-52) confirming the clinical efficacy of the biologic dupilumab in simultaneously blocking both IL-4/IL-13 signalling in chronic rhinosinusitis with nasal polyps (CRSwNP). The studies demonstrated that dupilumab (Dupixent^®, Sanofi and Regeneron) 300mg subcutaneously administered was clinically effective when added for patients with moderate to severe CRSwNP already maintained on the standard intranasal steroid mometasone furoate. Duration of treatment ranged from injections either 2 weekly for 24 weeks (SINUS-24) or every 2 weeks for 52 weeks or finally every 2 weeks for 24 weeks stepping down thereafter to every 4 weeks for a further 28 weeks (SINUS-52). Rapid improvements in all important parameters of disease burden were seen with such improvement maintained even where the frequency of injections was decreased. In patients with co-existent asthma, lung function and asthma control scores improved. This is consistent with the one airway hypothesis of shared T2 inflammatory programmes driving both disease syndromes. The studies formed the basis for FDA registration and clinical launch in the US, and EMA approval in Europe. Dupilumab presents a significant new treatment option in an area of urgent unmet therapeutic need in CRSwNP. Should dupilumab prove to be as effective in the real-life clinical environment as it has been in the studies, then a paradigm shift from sinonasal surgery to medical treatment of CRSwNP may need to occur in the ENT community. Questions in relation to best patient selection, combined upper and lower airway therapeutic pathways, long-term safety along with health economics and cost constraints ought now to be addressed.

Staphylococcus aureus and its IgE-inducing enterotoxins in asthma: current knowledge

While immunoglobulin (Ig) E is a prominent biomarker for early-onset, its levels are often elevated in non-allergic late-onset asthma. However, the pattern of IgE expression in the latter is mostly polyclonal, with specific IgEs low or below detection level albeit with an increased total IgE. In late-onset severe asthma patients, specific IgE to Staphylococcal enterotoxins (se-IgE) can frequently be detected in serum, and has been associated with asthma, with severe asthma defined by hospitalisations, oral steroid use and decrease in lung function. Recently, se-IgE was demonstrated to even predict the development into severe asthma with exacerbations over the next decade. Staphylococcus aureus manipulates the airway mucosal immunology at various levels via its proteins, including superantigens, serine-protease-like proteins (Spls), or protein A (SpA) and possibly others. Release of IL-33 from respiratory epithelium and activation of innate lymphoid cells (ILCs) via its receptor ST2, type 2 cytokine release from those ILCs and T helper (Th) 2 cells, mast cell degranulation, massive local B-cell activation and IgE formation, and finally eosinophil attraction with consequent release of extracellular traps, adding to the epithelial damage and contributing to disease persistence via formation of Charcot-Leyden crystals are the most prominent hallmarks of the manipulation of the mucosal immunity by S. aureus In summary, S. aureus claims a prominent role in the orchestration of severe airway inflammation and in current and future disease severity. In this review, we discuss current knowledge in this field and outline the needs for future research to fully understand the impact of S. aureus and its proteins on asthma.

Chinese Society of Allergy and Chinese Society of Otorhinolaryngology-Head and Neck Surgery Guideline for Chronic Rhinosinusitis

The current document is based on a consensus reached by a panel of experts from the Chinese Society of Allergy and the Chinese Society of Otorhinolaryngology-Head and Neck Surgery, Rhinology Group. Chronic rhinosinusitis (CRS) affects approximately 8% of Chinese adults. The inflammatory and remodeling mechanisms of CRS in the Chinese population differ from those observed in the populations of European descent. Recently, precision medicine has been used to treat inflammation by targeting key biomarkers that are involved in the process. However, there are no CRS guidelines or a consensus available from China that can be shared with the international academia. The guidelines presented in this paper cover the epidemiology, economic burden, genetics and epigenetics, mechanisms, phenotypes and endotypes, diagnosis and differential diagnosis, management, and the current status of CRS in China. These guidelines-with a focus on China-will improve the abilities of clinical and medical staff during the treatment of CRS. Additionally, they will help international agencies in improving the verification of CRS endotypes, mapping of eosinophilic shifts, the identification of suitable biomarkers for endotyping, and predicting responses to therapies. In conclusion, these guidelines will help select therapies, such as pharmacotherapy, surgical approaches and innovative biotherapeutics, which are tailored to each of the individual CRS endotypes.

Endotype-driven care pathways in patients with chronic rhinosinusitis

Chronic rhinosinusitis (CRS) has been differentiated clinically into CRS without nasal polyps and CRS with nasal polyps, with both forms subjected to glucocorticosteroid and antibiotic treatments and, if not successful, to nasal and sinus surgery tailored to endoscopic and computed tomographic scan findings. The elaboration of endotypes based on pathomechanisms involving different immune responses offers new possibilities in terms of prediction of prognosis and risks and sophisticated guidance in personalized pharmacotherapy, surgical approaches, and innovative treatment approaches in the CRS field with various biologics. Surgical approaches can vary from classical functional endoscopic sinus surgery to extended and "reboot" approaches, with the idea to completely remove the dysfunctional and inflamed mucosa and replace it with a newly grown healthy mucosa. Biologics in this field are targeting the type 2 cytokines IL-4, IL-5, and IL-13, as well as IgE. Phase I and II study results are promising, and phase III studies are currently being performed. The development of endotype-driven integrated care pathways appreciating these innovations are now needed for the management of CRS.

Pathogenic and protective roles of B cells and antibodies in patients with chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nose and sinuses that affects up to 12% of the population in Europe and the United States. This complex disease is likely driven by multiple environmental, genetic, and inflammatory mechanisms, and recent studies suggest that B cells might play a critical role in disease pathogenesis. B cells and their antibodies have undisputed roles in health and disease within the airway mucosae. Deficient or inadequate B-cell responses can lead to susceptibility to infectious disease in the nose, whereas excess antibody production, including autoantibodies, can promote damaging inflammation. Thus, patients with B-cell defects often have either chronic or recurrent acute infections, and this can be associated with nonpolypoid CRS. In contrast, many patients with CRS with nasal polyps, which is less likely to be driven by pathogens, have excess production of local immunoglobulins, including autoreactive antibodies. These B-cell responses activate complement in many patients and likely contribute to immunopathogenic responses. A better understanding of the B cell-associated mechanisms that drive disease in patients with CRS should be a high priority in the quest to understand the pathogenesis of this disease.

Mucosal IgE immune responses in respiratory diseases

IgE is the less abundant immunoglobulin isotype in serum and displays higher affinity for its cognate Fc receptor (FcεRI) than the rest of antibody isotypes. Moreover, the class switch recombination and the generation of memory responses remarkably differ between IgE and other isotypes. Importantly, class switch recombination to IgE can occur in the mucosae, preferentially through the sequential switching from IgG. Therefore, resident effector cells get rapidly sensitized, and free IgE can be found in mucosal secretions. All these aspects explain the involvement of IgE in respiratory diseases. In allergic rhinitis and allergic asthma, the IgE-sensitization to environmental allergens triggers an eosinophilic inflammation of the airway mucosa of atopic patients. In recent years, growing evidence indicates that some non-atopic patients with nasal reactivity to allergens display nasal eosinophilic inflammation, which could be triggered by the local production of allergen-specific IgE. This phenotype has been termed local allergic rhinitis. Mucosal IgE is also implicated in the pathophysiology of chronic rhinosinusitis with nasal polyps, even though the mechanisms for IgE synthesis might differ in this case. The role of IgE as mediator of airway diseases identify this marker as a therapeutic target. Some biologicals antagonize IgE-mediated inflammation of the airway mucosa, but they have not shown a beneficial long-term effect after discontinuation. In contrast, allergen immunotherapy does not only control the symptoms of airway allergy, but it also induces a long-lasting effect after discontinuation, thus modifying the natural course of the disease.

Sinus Infections, Inflammation, and Asthma

There is an important link between the upper and lower respiratory tracts whereby inflammation in one environment can influence the other. In acute rhinosinusitis, pathogen exposures are the primary driver for inflammation in the nose, which can exacerbate asthma. In chronic rhinosinusitis, a disease clinically associated with asthma, the inflammation observed is likely from a combination of an impaired epithelial barrier, dysregulated immune response, and potentially infection (or colonization) by specific pathogens. This review explores the associations between rhinosinusitis and asthma, with particular emphasis placed on the role of infections and inflammation.

Significance of IgG4-positive cells in severe eosinophilic chronic rhinosinusitis

BACKGROUND

IgG4 production is regulated by type 2 (IL-4 and IL-13) and regulatory (IL-10) cytokines involved in the pathophysiology of chronic rhinosinusitis (CRS). We sought to determine the pathophysiological characteristics of IgG4-positive cells in sinonasal tissues in CRS, especially eosinophilic CRS (ECRS).

METHODS

IgG4-positive cells in uncinate tissues (UT) and nasal polyps (NP) were examined by immunohistochemistry. Associations between the number of IgG4-positive cells and clinicopathological factors were analyzed. Receiver operating characteristics (ROC) analysis was performed to determine the cut-off value of IgG4-positive cells in tissue that can predict the post-operative course.

RESULTS

IgG4 was mainly expressed in infiltrating plasma and plasmacytoid cells, and the number of IgG4-positive cells was significantly higher in NP, especially those from severe ECRS patients, than in UT. In CRS patients, the number of IgG4-positive cells significantly and positively correlated with blood and tissue eosinophilia, radiological severity, and serum level of total IgE. The number of infiltrating IgG4-positive cells was significantly higher in patients with a poor post-operative course (sustained sinus shadow 6 months after surgery) than in those with a good one. The number of IgG4-positive cells in NP could discriminate patients with a good or a poor post-operative course (area under the curve: 0.769). Also, 73.3% sensitivity and 82.5% specificity were achieved when the cut-off value was set at 17 cells/high-power field.

CONCLUSIONS

Our results suggest that the local expression of IgG4 on cells may be used as a biomarker that reflects the pathophysiology of CRS, including the post-operative course.

Broad IgG repertoire in patients with chronic rhinosinusitis with nasal polyps regulates proinflammatory IgE responses

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is often characterized by local production of polyclonal IgE idiotypes. Although tissue IgE concentrations can be in the range of several thousand kilounits per liter, the regulatory mechanisms by which IgE-mediated inflammation is controlled in patients with nasal polyps are not well understood.

OBJECTIVE

We sought to determine whether locally induced IgG antibodies in patients with nasal polyps can inhibit an IgE-mediated proallergic response.

METHODS

Nasal polyp homogenates were collected from patients with grass pollen allergy with CRSwNP and nonallergic control subjects. IgE levels were measured using the Immuno Solid-phase Allergen Chip assay. IgE-containing nasal polyp homogenates with or without IgG depletion were evaluated for their capacity to promote IgE-facilitated allergen presentation, basophil activation, and histamine release. Local IgE and IgG repertoires were evaluated using Immunoglobulin 454 sequencing.

RESULTS

We show that IgG plays a key role in controlling IgE-mediated inflammatory responses in patients with nasal polyps. Depletion of IgG from nasal homogenates resulted in an increase in CD23-mediated IgE-facilitated allergen binding to B cells but also enhanced FcεRI-mediated allergen-driven basophil activation and histamine release. A similar response was observed in relation to specific IgE antibodies to Staphylococcus aureus enterotoxins. The capacity of IgG in nasal polyps to limit IgE-mediated inflammation is based on the fact that IgG repertoires widely share the antigen targets with the IgE repertoires in both allergic and nonallergic subjects.

CONCLUSION

Polyclonal IgE idiotypes in patients with CRSwNP are functional, promote IgE-mediated proallergic inflammation, and are partially antagonized by corresponding IgG idiotypes. This is most likely due to the fact that IgE and IgG clonotypes are widely shared in patients with nasal polyps.

Comparison of Subtyping Approaches and the Underlying Drivers of Microbial Signatures for Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a major human health problem that significantly reduces quality of life. While various microbes have been implicated, there is no clear understanding of the role they play in CRS pathogenesis. Another equally important observation made for CRS patients is that the epithelial barrier in the sinonasal cavity is defective. Finding a robust approach to subtype CRS patients would be the first step toward unravelling the pathogenesis of this heterogeneous condition. Previous work has explored stratification based on the clinical presentation of the disease (with or without polyps), inflammatory markers, pathology, or microbial composition. Comparisons between the different stratification approaches used in these studies have not been possible due to the different cohorts, analytical methods, or sample sites used. In this study, two approaches for subtyping CRS patients were compared, and the underlying drivers of the heterogeneity in CRS were also explored.

Chronic rhinosinusitis (CRS) is a heterogeneous condition characterized by persistent sinus inflammation and microbial dysbiosis. This study aimed to identify clinically relevant subgroups of CRS patients based on distinct microbial signatures, with a comparison to the commonly used phenotypic subgrouping approach. The underlying drivers of these distinct microbial clusters were also investigated, together with associations with epithelial barrier integrity. Sinus biopsy specimens were collected from CRS patients (n = 23) and disease controls (n = 8). The expression of 42 tight junction genes was evaluated using quantitative PCR together with microbiota analysis and immunohistochemistry for measuring mucosal integrity and inflammation. CRS patients clustered into two distinct microbial subgroups using probabilistic modelling Dirichlet (DC) multinomial mixtures. DC1 exhibited significantly reduced bacterial diversity and increased dispersion and was dominated by Pseudomonas, Haemophilus, and Achromobacter. DC2 had significantly elevated B cells and incidences of nasal polyps and higher numbers of Anaerococcus, Megasphaera, Prevotella, Atopobium, and Propionibacterium. In addition, each DC exhibited distinct tight junction gene and protein expression profiles compared with those of controls. Stratifying CRS patients based on clinical phenotypic subtypes (absence or presence of nasal polyps [CRSsNP or CRSwNP, respectively] or with cystic fibrosis [CRSwCF]) accounted for a larger proportion of the variation in the microbial data set than with DC groupings. However, no significant differences between CRSsNP and CRSwNP cohorts were observed for inflammatory markers, beta-dispersion, and alpha-diversity measures. In conclusion, both approaches used for stratifying CRS patients had benefits and pitfalls, but DC clustering provided greater resolution when studying tight junction impairment. Future studies in CRS should give careful consideration to the patient subtyping approach used.

IMPORTANCE Chronic rhinosinusitis (CRS) is a major human health problem that significantly reduces quality of life. While various microbes have been implicated, there is no clear understanding of the role they play in CRS pathogenesis. Another equally important observation made for CRS patients is that the epithelial barrier in the sinonasal cavity is defective. Finding a robust approach to subtype CRS patients would be the first step toward unravelling the pathogenesis of this heterogeneous condition. Previous work has explored stratification based on the clinical presentation of the disease (with or without polyps), inflammatory markers, pathology, or microbial composition. Comparisons between the different stratification approaches used in these studies have not been possible due to the different cohorts, analytical methods, or sample sites used. In this study, two approaches for subtyping CRS patients were compared, and the underlying drivers of the heterogeneity in CRS were also explored.

Chronic rhinosinusitis with nasal polyps: insights into mechanisms of disease from emerging biological therapies

Introduction: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex disease of the upper airway, with long-term morbidity. With detailed mechanistic studies currently lacking, understanding of the immunopathogenesis is still limited. However, outcomes from CRSwNP clinical studies using biologics that block key mediators or cells may provide some insights into how immune signaling pathways potentially integrate and modulate each other and contribute to disease. Current treatments are often ineffective and there is an urgent unmet clinical need for effective therapeutic strategies. Emerging biologics hold promise. Areas covered: This review covers the biology of CRSwNP in terms of the clinical outcomes reported from blocking immune cascades with available biologics. Immune amplification mechanisms and how biologics can potentially modulate such 'master' cytokines and signaling proteins that drive inflammation and contribute to tissue remodeling in CRSwNP are discussed. Expert commentary: Biologics have the potential to transform CRSwNP treatment. The ability to predict clinical response in a complex disease as CRSwNP to a biologic cannot necessarily be predicted by measuring a single protein or cell as a biomarker of disease. Further studies with biologics must be carefully undertaken to fully evaluate wider biomarker associated pheno-endotype responses along with any associated asthma outcome measures.