The Impact of Climatic, Socioeconomic, and Geographic Factors on the Prevalence of Allergic Fungal Rhinosinusitis: A Worldwide Ecological Study

Characterising the allergic fungal rhinosinusitis microenvironment using full-length 16S rRNA gene amplicon sequencing and fungal ITS sequencing

INTRODUCTION

Allergic fungal rhinosinusitis (AFRS) is a severe phenotype of chronic rhinosinusitis with nasal polyposis (CRSwNP), characterised by localised and exaggerated type 2 inflammation. While fungal antigenic stimulation of unregulated Th2-mediated inflammation is the core pathophysiological mechanism, the direct and synergistic role of bacteria in disease modification is a pervasive hypothesis. We set out to define the microenvironment of AFRS to elucidate virulent organisms that may be implicated in the pathophysiology of AFRS.

METHODOLOGY

We undertook a cross-sectional study of AFRS patients and non-fungal CRSwNP patients. Demographics, disease severity, culture and microbiome sequences were analysed. Multimodality microbiome sequencing included short-read next-generation sequencing (NGS) on the Illumina Miseq (16S rRNA and ITS) and full-length 16S rRNA sequencing on the Oxford Nanopore Technologies GridION (ONT).

RESULTS

Thirty-two AFRS and 29 non-fungal CRSwNP patients (NF) were included in this study. Staphylococcus aureus was the dominant organism cultured and sequenced in both AFRS and NF groups (AFRS 27.54%; NF 18.04%; p = .07). Streptococcus pneumoniae (AFRS 12.31%; NF 0.98%; p = .03) and Haemophilus influenzae (AFRS 15.03%; NF 0.24%; p = .005) were significantly more abundant in AFRS. Bacterial diversity (Shannon's index) was considerably lower in AFRS relative to NF (AFRS 0.6; NF 1.0, p = .008). Aspergillus was the most cultured fungus in AFRS (10/32, 31.3%). The AFRS sequenced mycobiome was predominantly represented by Malassezia (43.6%), Curvularia (18.5%) and Aspergillus (16.8%), while the NF mycobiome was nearly exclusively Malassezia (84.2%) with an absence of Aspergillus or dematiaceous fungi.

CONCLUSION

A low diversity, dysbiotic microenvironment dominated by Staphylococcus aureus, Streptococcus pneumoniae and Haemophilus influenzae characterised the bacterial microbiome of AFRS, with a mycobiome abundant in Malassezia, Aspergillus and Curvularia. While Staphylococcus aureus has been previously implicated in AFRS through enterotoxin superantigen potential, Streptococcus pneumoniae and Haemophilus influenzae are novel findings that may represent alternate cross-kingdom pathophysiological mechanisms.

The Relationship of Climate Change to Rhinitis

Evidence is mounting that climate change is having a significant impact on exacerbations of rhinitis. Concomitantly, the prevalence of allergic rhinitis is increasing at an accelerated rate. We herein explore the impact of carbon dioxide, barometric pressure and humidity changes, and anthropogenic pollutants on aeroallergens and rhinitis hypersensitivity. Important immune mechanisms underlying the climate-driven effects on rhinitis are discussed. Also, climate change is shifting ecological zones and seasons, increasing weather extremes, and altering regional atmospheric and environmental conditions. The direct impact of these factors on promoting allergic and nonallergic rhinitis is reviewed.

Update on the Role of Fungus in Allergy, Asthma, and the Unified Airway

The united airway refers to the combined upper and lower airways and their interconnected pathophysiologic relationships. Inflammatory airway diseases (chronic rhinosinusitis, asthma, and so forth) have been linked to fungal species through type 2 immune responses. These type 2 immune responses involve the cytokines interleukin (IL)-4, IL-5, IL-13, and a myriad of other inflammatory processes that lead to a spectrum of diseases from allergic bronchopulmonary mycosis to chronic rhinosinusitis. Historically, these diseases have been managed primarily with corticosteroids but recent revelations in the molecular pathophysiology provide opportunities for more diverse treatment options for patients with uncontrolled disease.

How Does Climate Change Affect the Upper Airway?

There is mounting evidence that climate change is having a significant influence on exacerbations of airway disease. We herein explore the physical factors of carbon dioxide, temperature increases, and humidity on intensifying allergen and fungal growth, and worsening air quality. The direct influence of these factors on promoting allergic rhinitis, chronic rhinosinusitis, and allergic fungal rhinosinusitis is reviewed.

Association between Social Determinants of Health and Allergic Fungal Rhinosinusitis: A Systematic Review and Meta-analysis

OBJECTIVE

Some previous studies have shown an increased prevalence of allergic fungal rhinosinusitis (AFRS) among young, black patients with poor access to health care; however, results have been mixed. The purpose of this study was to investigate the relationship between social determinants of health and AFRS.

DATA SOURCES

PubMed, Scopus, CINAHL.

REVIEW METHODS

A systematic review was performed searching for articles published from date of inception to September 29, 2022. English language articles describing the relationship   between social determinants of health (i.e., race, insurance status) and AFRS as compared to chronic rhinosinusitis (CRS) were selected for inclusion. A Meta-analysis of proportions with comparison (Δ) of weighted proportions was conducted.

RESULTS

A total of 21 articles with 1605 patients were selected for inclusion. The proportion of   black patients among AFRS, chronic rhinosinusitis with nasal polyps (CRSwNP), and chronic rhinosinusitis without nasal polyps (CRSsNP) groups was 58.0% [45.3%-70.1%], 23.8% [14.1%-35.2%], and 13.0% [5.1%-24.0%], respectively. This was significantly higher among the AFRS population compared to both the CRSwNP population (Δ34.2% [28.4%-39.6%], p < .0001) and the CRSsNP population (Δ44.9% [38.4%-50.6%], p < .0001). The proportion of patients who were either uninsured or covered by Medicaid among the AFRS, CRSwNP, and CRSsNP populations was 31.5% [25.4%-38.1%], 8.6% [0.7%-23.8%], and 5.0% [0.3%-14.8%], respectively. This was significantly higher among the AFRS group than the CRSwNP group (Δ22.9% [15.3%-31.1%], p < .0001) and the CRSsNP group (Δ26.5% [19.1%-33.4%], p < .0001).

CONCLUSION

This study confirms that AFRS patients are more likely to be Black and either uninsured or on subsidized insurance than their CRS counterparts.

Allergic fungal rhinosinusitis: What we can learn from allergic bronchopulmonary mycosis

Allergic fungal rhinosinusitis (AFRS) and allergic bronchopulmonary mycosis (ABPM) are inflammatory disorders of the respiratory tract resulting from type 1 and 3 hypersensitivity reactions against fungi. The hallmark features of both diseases are eosinophil infiltration into the airway mucosa caused by localized type 2 inflammation and concomitant viscid secretions in the airways. Eosinophilic mucin-induced compression of adjacent anatomic structures leads to bone erosion and central bronchiectasis in the upper and lower respiratory tracts, respectively. Although these diseases share common features in their pathogenesis, they also exhibit notable differences. Epidemiologic findings are diverse, with AFRS typically presenting at a younger age, exhibiting less complicated bronchial asthma, and displaying lower total immunoglobulin E levels in laboratory findings compared with ABPM. Furthermore, despite their similar pathogenesis, the rarity of sinio-bronchial allergic mycosis in both AFRS and ABPM underscores the distinctions between these two diseases. This review aims to clarify the similarities and differences in the pathogenesis of AFRS and ABPM to determine what can be learned about AFRS from ABPM, where more is known.

Consideration of the Clinical Diagnosis of Allergic Fungal Sinusitis: A Single-Center Retrospective Study

INTRODUCTION

Allergic fungal rhinosinusitis (AFRS) is characterized by refractory and high recurrence rate. Improper treatment may lead to repeated recurrence and even serious complications, including vision loss, blindness, and intracranial complications. However, AFRS is easy to be misdiagnosed clinically.

OBJECTIVE

To ensure early diagnosis, the clinical presentations of patients with AFRS were studied.

METHODS

Data from patients with sinusitis hospitalized in the First Affiliated Hospital of the University of Science and Technology of China (USTC) from January 2015 to October 2022 were collected. The patients were divided into three groups; group A patients with AFRS, group B patients suspected of AFRS, and group C patients with fungus ball sinusitis (FBS).We retrospectively analyzed the data using IBM SPSS 19.0 to perform the chi-square test and one-way ANOVA test.

RESULTS

In total, 35 cases of AFRS, 91 cases of suspected AFRS, and 661 cases of FBS were rediagnosed. Compared with FBS patients, AFRS patients were younger, the total IgE, the percentage of eosinophils and basophils in peripheral blood were higher, and the proportion of patients with allergic rhinitis, asthma or hypo olfactory was higher. It had a higher recurrence rate. These results were also observed in the comparison between suspected AFRS patients and FBS patients, but no significant difference was found in the comparison between suspected AFRS patients and suspected AFRS patients.

CONCLUSIONS AND SIGNIFICANCE

AFRS may be misdiagnosed due to the low detection of fungi. To ensure early diagnosis, we recommend that patients with clinical, radiological, and laboratory features similar to those of AFRS but without evidence of fungal staining be treated according to the treatment criteria of AFRS.

New Developments in Allergic Fungal Rhinosinusitis Pathophysiology and Treatment

BACKGROUND

Allergic fungal rhinosinusitis (AFRS) is an endotype of chronic rhinosinusitis (CRS) with nasal polyps characterized by eosinophilic mucin laden with fungal hyphae entrapped in expanded sinus cavities with an exaggerated hypersensitivity to fungal elements. The last decade has elucidated fungi-driven inflammatory pathways contributing to the pathophysiology of chronic inflammatory respiratory diseases. In addition, novel therapeutic biologic options have become available for CRS over the last several years.

OBJECTIVE

To review the current literature examining AFRS, focusing on recent developments in our understanding of its pathophysiology and implications for treatment options.

METHODS

Review article.

RESULTS

Fungi-driven respiratory inflammation has been linked to fungal proteinases and toxin activity. In addition, AFRS patients demonstrate a local sinonasal immunodeficiency in antimicrobial peptides and hence limited antifungal activity, along with an exaggerated type 2 inflammatory response, highlighting a possible imbalanced type 1, type 2, and type 3 profile. The elucidation of these dysregulated molecular pathways has highlighted novel potential therapeutic targets. As such, the clinical management of AFRS, which once included surgery and extended courses of oral corticosteroids, is transitioning away from long courses of oral corticosteroids to incorporate novel delivery mechanisms of topical therapeutic targets and biologics for recalcitrant disease.

CONCLUSION

AFRS is an endotype of CRS with nasal polyps (CRSwNP) for which the molecular pathways leading to its inflammatory dysfunction are beginning to be illuminated. In addition to affecting treatment options, these understandings may shape necessary changes to diagnostic criteria and the extrapolated effects of environmental changes on AFRS. More critically, a better appreciation of fungi-driven inflammatory pathways may have implications for the understanding of broader CRS inflammation.

Climate change, the environment, and rhinologic disease

BACKGROUND

The escalating negative impact of climate change on our environment has the potential to result in significant morbidity of rhinologic diseases.

METHODS

Evidence based review of examples of rhinologic diseases including allergic and nonallergic rhinitis, chronic rhinosinusitis, and allergic fungal rhinosinusitis was performed.

RESULTS

The lower socioeconomic population, including historically oppressed groups, will be disproportionately affected.

CONCLUSIONS

We need a systematic approach to improve healthcare database infrastructure and funding to promote diverse scientific collaboration to address these healthcare needs.

Allergic Fungal Rhinosinusitis: The Role and Expectations of Biologics

Allergic fungal rhinosinusitis (AFRS) is a noninvasive subtype of chronic rhinosinusitis with nasal polyps (CRSwNP) that usually develops in immunocompetent atopic individuals and is more common in geographic regions characterized by warm temperatures and high humidity, conducive to higher environmental fungal presence. Allergic fungal rhinosinusitis usually presents with unique computed tomography findings and significant polyp burden, yet patients often report minimal sinus symptoms. Patients with AFRS often have extremely elevated serum total and fungal-specific IgE levels. Treatment almost always requires surgery, in which adjuvant medical therapy is critical to success. However, until recently the choice of adjuvant therapy has consisted primarily of either oral and/or topical steroids. Although oral corticosteroids decrease recurrence after surgery, data for the effectiveness of other adjunctive pharmacologic agents, including topical and oral antifungal agents and immunotherapy, have remained unclear and hence are not recommended in recent guidelines including the International Consensus of Allergy and Rhinology. Three biologics, omalizumab, dupilumab, and mepolizumab, have recently been approved for treating CRSwNP in general, but clinical trials to date with these biologics did not involve AFRS patients. Recently published case reports and smaller prospective studies have shown good efficacy of these biologics on the AFRS subgroup of patients. This article provides an overview of the understanding of the pathophysiology of AFRS, implications of this understanding on the possible role of biologics, and clinical reports on the use of biologics in treating AFRS. Because biologics are indicated for treating CRSwNP, follow up real-world evidence studies are needed for AFRS.