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

Role of IgG4 Antibodies in Human Health and Disease

Immunoglobulin G4 (IgG4), a unique subclass of IgG antibodies, plays diverse roles in human health and disease. Its distinct features, such as Fab-arm exchange and specific mutations, confer reduced effector functions compared to other IgG subclasses. In health, IgG4 responses contribute to immune tolerance, particularly in the context of allergen-specific immunotherapy (AIT), where they can mediate tolerance to environmental antigens, inhibit IgE-dependent mast cell degranulation, and compete with IgE for allergen binding. This helps in attenuating allergic symptoms and is associated with increased levels of allergen-specific IgG4. However, in disease scenarios, the role of IgG4 is complex. IgG4 lacks complement fixation and, thus, shows a reduced ability to activate immune effector pathways, it was initially thought to be protective against autoimmune diseases. However, emerging evidence suggests that it can contribute to pathology. For instance, IgG4 autoantibodies against specific antigens can aggravate conditions in certain autoimmune disorders. In some cancers, it may play a role in immune evasion, with higher levels correlating with poor patient survival, albeit in others, its exact function remains elusive. Overall, understanding the precise role of IgG4 in various physiological and pathological conditions is crucial for developing targeted therapeutic strategies and improving patient outcomes.

Clinical and Immunological Features of Bronchial Asthma Comorbid Chronic Urticaria: A Retrospective Study

INTRODUCTION

Asthma and chronic urticaria (CU) are two high prevalent diseases and often coexist. The underlying relationship and potential immunological mechanism between the two diseases are still unclear. The objective of this study was to investigate the clinical and immunological feature of asthma comorbid with CU.

METHODS

A retrospective study was conducted. Fifty patients with asthma comorbid CU, 50 patients with asthma, and 50 patients with CU alone were included. Age and sex of the patients enrolled were matched. Data of demographic characteristics, clinical manifestations including disease severity (frequency of symptoms, age of onset, disease duration, symptom score, complication with allergic rhinitis) as well as serum immunological index including total IgE (tIgE), allergen-specific IgE (sIgE), and food-specific IgG4 (FS-IgG4), were collected and analyzed.

RESULTS

No significant differences in the frequency of symptoms, age of onset, and disease duration were found among the three groups. The score of asthma control test (ACT) in patients with asthma comorbid CU was significantly lower than that of asthma (p = 0.005); however, compared with patients with CU, the 7-day urticaria activity score (UAS7) of patients with asthma comorbid CU did not show obvious differences. Immunological index showed that the positive rates of tIgE, house dust mite (HDM)-sIgE, and FS-IgG4 were different among the three groups (p < 0.05). Patients with asthma comorbid CU had the highest rate of positive tIgE, moderate and severe positive sIgE to HDM. Egg-specific IgG4 (egg-sIgG4) had the highest positive rate in all groups. Patients of asthma comorbid CU obtained the highest rate of severe positive of egg-sIgG4.

CONCLUSION

Our results demonstrated that patients with asthma comorbid CU have lower control level of asthma symptoms, higher tIgE and HDM-sIgE level, and highest rate of severe positive egg-sIgG4. These results indicate that comorbidity of CU in asthma obviously increases the severity of allergens.

Hyperuricemia Increases the Risk of Postoperative Recurrence in Chinese Patients with Chronic Rhinosinusitis

Background

Elevated serum uric acid is crucial in the pathophysiology of chronic inflammatory diseases. However, its impact on chronic rhinosinusitis (CRS) recurrence risk is unknown. This study investigates the association between elevated serum uric acid and the risk of CRS recurrence.

Methods

A retrospective cohort study was conducted on 1004 CRS patients (including 638 males and 366 females) who received functional endoscopic sinus surgery. All patients were followed up for more than 2 years, and categorized into subgroups based on phenotype, gender, and postoperative recurrence. Cox regression analysis was performed to evaluate the associations between serum uric acid and the risk of CRS recurrence.

Results

After categorization, 104 males had hyperuricemia, and 54 females presented hyperuricemia. The rate of recurrent CRS in the hyperuricemia group was significantly higher compared to the non-hyperuricemia group in both males and females (P<0.05). In both male and female patients, the rate of hyperuricemia and uric acid levels were elevated in the recurrent CRS group in comparison with the non-recurrent CRS group (P<0.05). Unadjusted and adjusted Cox regression analysis demonstrated that serum uric acid was an independent risk factor for CRS recurrence (P<0.05). The receiver operator characteristic curve showed that serum uric acid was a potential biomarker for predicting the recurrence of CRS and its phenotypes in both genders (P<0.05).

Conclusion

There is a close relationship between elevated serum uric acid and the recurrence risk of CRS and its phenotypes, suggesting that serum uric acid may be a novel biomarker for predicting recurrent CRS.

Common Characteristics of Sinonasal Inflammation Associated with IgG4-Related Disease and Other Chronic Inflammatory Diseases: A Retrospective Observational Study

INTRODUCTION

Immunoglobulin G4-related disease (IgG4-RD) is a systemic inflammatory disease characterized by elevated serum IgG4, tissue infiltration of IgG4-positive cells, and fibrosis. Although a number of IgG4-RD patients show sinonasal involvement, there is little known about sinonasal inflammation associated with IgG4-RD. This study aimed to describe the clinicopathological features of sinonasal inflammation associated with IgG4-RD and to compare with other inflammatory diseases, such as eosinophilic chronic rhinosinusitis (ECRS) and granulomatosis with polyangiitis (GPA).

METHODS

A retrospective analysis of clinicopathological features of patients with sinonasal lesions and high serum IgG4 was performed. Patient data were reviewed to determine whether they fulfilled the diagnostic criteria for other inflammatory diseases.

RESULTS

Six of 7 patients were diagnosed with IgG4-RD, while 1 patient was diagnosed with GPA. In the 6 patients with IgG4-RD, intranasal findings showed nasal polyps in 3 patients (50%) and nasal crusting in the 3 patients (50%). Computed tomography showed ethmoid sinus involvement in 5 patients (83%). Five of the 6 patients (83%) were diagnosed with IgG4-RD based on nasal biopsy, whereas 1 patient (17%) was diagnosed based on lacrimal gland biopsy. Four patients fulfilled the Japanese epidemiological survey of refractory ECRS (JESREC) criteria. However, none of the patients showed eosinophil infiltration. Although the patient with GPA showed high levels of serum IgG4 and tissue infiltration of IgG4-positive cells in the nasal biopsy, the patient showed common clinical features of GPA.

CONCLUSION

Patients with sinonasal inflammation associated with IgG4-RD had similar clinical characteristics with ECRS and GPA. Histopathological findings of the nasal biopsy from clinically diagnosed GPA was consistent with that of IgG4-RD. Sinonasal inflammation associated with IgG4-RD should be diagnosed based not only on tissue infiltration of IgG4-positive cells but in conjunction with clinical findings such as local nasal characteristics, involvement of other organs, and serum antineutrophil cytoplasmic antibody levels. IgG4-RD should be ruled out in patients with eosinophilia without histopathological eosinophil infiltration.

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.

Food-specific IgG4-guided diet elimination improves allergy symptoms in children

Allergic diseases in children are major public health concerns due to their widespread and rising prevalence. Food-specific immunoglobulin G4(FS-IgG4) has been detected in patients with allergic diseases, but its clinical significance is still debated. In the present study, 407 children with allergic diseases were recruited and categorized into three groups according to the different systems involved: the respiratory system group, the skin system group, and a multiple system group, with the collection of clinical symptoms and serum antibodies, including total immunoglobulin E (IgE), house dust mite (HDM) IgE, food-specific IgE (FS-IgE), and FS-IgG4. Part of these patients were followed up with the intervention of FS-IgG4-guided diet elimination with or without add-on probiotics supplement. The analysis at baseline revealed distinct serum levels of different antibodies. The positive rate of FS-IgG4 in all groups was more than 80%, and the proportion of total IgE and FS-IgG4 both positive in the multi-system group was the highest (p=0.039). Egg and milk were the foods with the highest positive rate of FS-IgG4 in all groups. After diet elimination for more than 3 months, serum FS-IgG4 in children significantly decreased (P<0.05) along with the improvement of clinical symptoms, regardless of the add-on of probiotics. However, the intervention did not impact the serum levels of total IgE, FS-IgE, and HDM IgE. There was no further decrease of serum FS-IgG4 level in children followed up for more than 1 year, which may be related to noncompliance with diet elimination. Multivariate regression analysis revealed that the decline of serum FS-IgG4 was an independent predictable factor for the improvement of clinical symptoms (adjusted OR:1.412,95%CI 1.017-1.96, p=0.039). The add-on of probiotics showed less efficiency in reducing the FS-IgG4 level in more patients with relief of clinical symptoms. Our results confirmed the correlation between FS-IgG4 and allergic diseases, and the decreased FS-IgG4 could be a useful predictor for the improvement of allergic symptoms. FS-IgG4-guided diet elimination is an efficient treatment for allergic diseases. Our study adds solid data to the clinical significance of FS-IgG4 in allergic diseases.

Systemic inflammation response index predicts the postoperative recurrence of chronic rhinosinusitis with nasal polyps: a retrospective study in the Chinese population

PURPOSE

Endoscopic sinus surgery (ESS) is now frequently used to treat chronic sinusitis with nasal polyps (CRSwNP), but postoperative recurrence plagues many patients. We aimed to assess the value of the systemic inflammation response index (SIRI) and the systemic immune-inflammatory index (SII) for the prediction of postoperative recurrence in patients with CRSwNP.

METHODS

A total of 143 patients with CRSwNP and 76 age- and sex-matched healthy subjects were enrolled. Patients were divided into the recurrence group and the non-recurrence group according to the recurrence of CRSwNP. Univariate and multivariate analyses showed independent risk factors for the recurrence. A receiver operating characteristic curve analysis was conducted to assess the predictive accuracy of the variables and determine the optimal cut-off values. Finally, a survival analysis was conducted.

RESULTS

Univariate analysis revealed that age, sex, CRP, EOS, SIRI, SII, NLR, ELR, and Lund-Mackay CT scores were significant predictors of the recurrence of CRSwNP. Multivariate analysis confirmed that SIRI (OR = 1.310, p < 0.001) and Lund-Mackay CT scores (OR = 1.396, p < 0.001) were independent predictors. SIRI (AUC = 0.761, 95% CI: 0.685-0.836) had a certain value in predicting the recurrence of CRSwNP.

CONCLUSION

SIRI is a potential predictive marker of the postoperative recurrence of CRSwNP.

Rectal Staphylococcus aureus Carriage and Recurrence After Endoscopic Sinus Surgery for Chronic Rhinosinusitis With Nasal Polyps: A Prospective Cohort Study

OBJECTIVE

Chronic rhinosinusitis with nasal polyps (CRSwNPs) remains a major challenge due to its high recurrence rate after endoscopic sinus surgery (ESS). We aimed to investigate the risk factors of recurrence among patients who underwent ESS for Chronic rhinosinusitis (CRS).

METHODS

Prospective cohort study including 391 cases in a single institution receiving ESS were included for analysis from 2014 and 2017. Baseline characteristics including rectal Staphylococcus aureus (S aureus) carriage in patients receiving ESS for CRSwNPs. The primary outcome was the recurrence of CRSwNPs. Multivariate regression model was established to identify independently predictive factors for recurrence.

RESULTS

Overall, 142 (36.3%) cases with recurrence within 2 years after ESS were observed in this study. After variable selection, multivariate regression model consisted of 4 variables including asthma (odds ratio [OR] = 3.41; P < .001), nonsteroidal anti-inflammatory drug allergy (OR = 2.27; P = .005), previous ESS (OR = 3.64; P < .001), and preoperative carriage of S aureus in rectum (OR = 2.34; P = .001).

CONCLUSIONS

Based on our results, surgeons could predict certain groups of patients who are at high risk for recurrence after ESS. Rectal carriage of S aureus is more statistically related to the recurrence of CRSwNP after ESS compared with skin and nasal carriage.

The functional role and the clinical application of periostin in chronic rhinosinusitis

INTRODUCTION

Chronic rhinosinusitis (CRS) comprises several heterogenous groups, now classified based on endotype more often than on phenotype. A number of studies aimed at finding a useful biomarker for type 2 CRS suggest that periostin is a promising surrogate.

AREAS COVERED

A comprehensive overview of the clinical significance of tissue periostin expression and serum periostin in CRS patients is provided. The effects of comorbid asthma on serum periostin and samples other than serum in which periostin can be detected in CRS patients are also discussed. Moreover, the functional roles of periostin in CRS pathogenesis are summarized.

EXPERT OPINION

The position of periostin as a signature biomarker of type 2 CRS has been well established, enabling us to classify CRS patients by endotyping. Serum periostin is useful not only for endotyping CRS patients, but also for estimating disease severity, comorbidity, prognosis, and response to treatment, and in particular, predicting recurrence after surgery. However, it remains to be addressed how we apply serum periostin to using biologics for CRS patients. Further studies aimed at showing periostin to be a therapeutic target for CRS are awaited.

The clinical significance of allergen-specific IgG4 in allergic diseases

IgG4 is a subclass of IgG antibody with a unique molecular feature of (Fragment antigen- binding) Fab-arm exchange, allowing bispecific antigen binding in a mono-valent manner. With low binding affinity to C1q and Fcγreceptors, IgG4 is incapable of forming immune complexes and activating the complement pathway, exhibiting a non-inflammatory feature. IgG4 is produced similarly to IgE and is considered a modified reaction to IgE class-switching response under certain conditions. It could also counteract IgE-activated inflammation. However, the clinical significance of IgG4 in allergic diseases is complex and controversial. Three viewpoints have been suggested to describe the role of IgG4. IgG4 can act as a tolerance-inducer to play a protective role under repeated and rapid incremental dosing of allergen exposure in allergen immunotherapy (AIT), supported by allergies in cat raisers and venom desensitization in beekeepers. Another viewpoint accepted by mainstream specialists and guidelines of Food Allergy and Management in different countries points out that food-specific IgG4 is a bystander in food allergy and should not be used as a diagnostic tool in clinical work. However, eosinophilic esophagitis (EoE) investigation revealed a direct clinical relevance between physiopathology and serum IgG4 in cow milk and wheat. These factors indicate that allergen-specific IgG4 plays a multifaceted role in allergic diseases that is protective or pathogenic depending on different allergens or exposure conditions.

Developments and Emerging Trends in the Global Treatment of Chronic Rhinosinusitis From 2001 to 2020: A Systematic Bibliometric Analysis

Background

Research on the treatment of chronic rhinosinusitis (CRS) has increased in recent decades. We undertook a bibliometric and visualization analysis of studies on CRS treatment to track research trends and highlight current research “hotspots”.

Methods

Original publications related to CRS treatment were obtained from the Science Citation Index-Expanded (SCI-E) and Social Sciences Citation Index (SSCI) databases in the Web of Science Core Collection (WoSCC) of Clarivate Analytics between 2001 and 2020. The country/region, institution, author, journal, references, and keywords involved in this topic were extracted using CiteSpace and VOSviewer to identify and analyze the research focus and trends in this field.

Results

In the previous two decades (especially after 2015), the number of publications on CRS treatment has grown markedly. With regard to publications and access to collaborative networks, the leading country was the USA. High-frequency keywords were “CRS,” “endoscopic sinus surgery,” “sinusitis,” “nasal polyps,” “asthma,” “rhinosinusitis,” “management,” “diagnosis,” “outcomes,” and “quality of life.” Inspection of keyword bursts suggested that “clinical practice guideline,” “adult CRS,” “innate lymphoid cell,” “recurrence,” and “mepolizumab” are the emerging research hotspots. The timeline view of the cluster map revealed that biologic agents have become an up-and-coming “hot topic” in CRS treatment in recent years.

Conclusion

Academic understanding of CRS treatment has improved markedly over the past 20 years. We study analyzed the papers objectively, methodically, and comprehensively, and identified hotspots and prospective trends in the field of CRS treatment. These results will aid rhinologists in gaining greater insight into CRS treatment strategies and identifying the changing dynamics of CRS research.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

The diagnostic importance of periostin as a biomarker in chronic rhinosinusitis with nasal polyp

PURPOSE

The current studies in the literature report that periostin contributes to the formation of nasal polyps and may be a molecular biomarker for chronic rhinosinusitis with nasal polyps (CRSwNP). This study aims to investigate the effect of periostin in determining polyp burden in CRSwNP patients and evaluate its impact on postoperative surgical results and its functionality as a biomarker.

METHODS

The study included 26 patients who underwent endoscopic sinus surgery due to CRSwNP and 30 patients who were scheduled to undergo septoplasty due to isolated nasal septum deviation. We performed preoperative Lund-Mackay scoring and preoperative and postoperative SNOT-22 and Modified Lund-Kennedy scoring for the patients. Tissue and serum samples were collected from all patients in surgery and another serum sample was taken from CRSwNP patients at postoperative month 6.

RESULTS

Tissue eosinophil (p < 0.001), preoperative serum (p < 0.001), and tissue (p = 0.002) periostin were significantly higher in the CRSwNP group. We observed a statistically significant positive correlation between tissue eosinophil values and tissue periostin values in CRSwNP patients (p = 0.004). We found a statistically significant positive correlation between the tissue periostin values and postoperative SNOT-22 scores of the CRSwNP group patients (p = 0.005).

CONCLUSION

According to the results of our study, we think that periostin can be used as a biomarker in the prediction, determination of disease severity, and prognosis of CRSwNP. Comprehensive cohort studies with larger patient series are needed to provide more information on the role and effects of periostin in cases of CRSwNP undergoing surgical treatment.

Relationship between Saliva and Sublingual Immunotherapy

The demand for allergen specific immunotherapy (AIT), especially sublingual immunotherapy (SLIT), is increasing because of its efficacy in inducing clinical remission of allergic diseases and its low risk of side effects. Since not all patients that undergo SLIT demonstrate an improvement in allergic symptoms, the development of biomarkers to predict the outcome and adjuvants for SLIT is desired. Saliva is the first target with which tablets used in SLIT come into contact, and salivary pH, chemical properties or microbiome composition are reported to possibly be associated with the outcome of SLIT. Antibodies such as IgG4 and IgA not only in the serum but also in the saliva are increased after SLIT and may also be associated with the efficacy of SLIT. The development of the metagenomic sequencing technique makes it possible to determine the microbiome composition and ratio of each bacterium, and researchers can investigate the relationships between specific bacteria and the immune response. Some bacteria are reported to improve the SLIT outcome and have the potential to be used as biomarkers for the selection of patients and as adjuvants in SLIT. Here, we introduce biomarkers for SLIT and present recent findings regarding the relationship between saliva and SLIT.