Improving the detection of fungi in eosinophilic mucin: seeing what we could not see before

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.

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.

Allergic fungal rhinosinusitis and eosinophilic mucin chronic rhinosinusitis: Differential diagnostic criteria. A two-center comparative study following STROBE methodology

OBJECTIVES

Allergic fungal rhinosinusitis (AFRS) and eosinophilic mucin chronic rhinosinusitis (EMRS) are two forms of chronic sinusitis distinguished by the presence (AFRS) or absence (EMRS) of fungal elements in sinus mucin. Detection of the fungal elements, however, is complex and it is difficult to say whether EMRS is in fact an entity distinct from AFRS. The aim of the present study, based on a retrospective series of AFRS and EMRS, was to identify the specific clinical and radiological elements distinguishing between the two.

MATERIALS AND METHODS

A 2-center retrospective observational study following STROBE guidelines included patients managed for AFRS or EMRS between 2009 and 2022. Clinical, mycological, pathologic and radiological data were collected. Type of treatment and disease progression were also analyzed. Intergroup comparison used Student's test for mean values of quantitative variables, with calculation of P-values, and Pearson's Chi2 test or Fisher's exact test for categoric variables, with calculation of relative risk and 95% confidence intervals.

RESULTS

The AFRS group comprised 41 patients and the EMRS group 34. Demographic data were comparable between groups. EMRS showed a higher rate of asthma (79.4 vs. 31.4%; P<0.001), more severe nasal symptomatology (rhinorrhea, P=0.01; nasal obstruction, P=0.001), and more frequent bilateral involvement (85.3 vs. 58.5%; P=0.021). AFRS showed more frequent complications (19 vs. 0%; P=0.006). Radiologically, mucin accumulation was greater in AFRS, filling the sinus in 84.2% of cases, versus 26.3% (P<0.001), with more frequent sinus wall erosion (19 vs. 5.8%; P=0.073). The recurrence rate was higher in EMRS: 38.2 vs.21.9% (P=0.087).

CONCLUSION

The present retrospective study found a difference in clinical and radiological presentation between AFRS and EMRS, with EMRS more resembling the presentation of severe nasal polyposis.

Update on allergic fungal rhinosinusitis

Allergic fungal rhinosinusitis (AFRS) is a unique clinical entity that falls under the broader umbrella of chronic rhinosinusitis with nasal polyps with type 2 inflammation. It is characterized by nasal polyposis, production of characteristic thick eosinophilic mucin, and expansile change of involved sinus cavities. The diagnosis is classically made using the Bent and Kuhn criteria. However, recent studies have indicated the lack of specificity of some major criteria. The need to fulfill all 5 criteria before diagnosing AFRS partially mitigates this but renders the criteria cumbersome to use, and highlights the need to develop more specific criteria. Our understanding of AFRS pathophysiology has advanced significantly and has helped elucidate the lack of histatins contributing to the inability to clear fungal spores, consequently leading to fungi-induced disruption of the epithelial barrier and stimulation of sinonasal epithelial cells. These trigger a cascade of type 2 inflammatory cytokines driven by both the adaptive and innate immune system. Although more research is needed, these findings could hypothetically point to a limited type 3 immune response at the sinus mucosa, resulting in a compensatory overstimulation of type 2 inflammatory processes. Treatment for AFRS remains centered on surgery and topical corticosteroids. Short courses of systemic corticosteroids may be used with caution, and fungal-specific immunotherapy and systemic antifungals are options in recalcitrant disease. Biologics show early promise, as we await data from randomized controlled trials under way. Finally, new insights into AFRS pathology provide opportunities for novel therapeutic strategies.

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.

Current Insight into Treatment of Chronic Rhinosinusitis: Phenotypes, Endotypes and Implications for Targeted Therapeutics

Chronic rhinosinusitis (CRS) is characterized by persistent locoregional mucosal inflammation of the paranasal sinuses and upper airway that has substantial associated health care costs¹. Personalized approaches to care that incorporate use of molecular biomarkers, phenotypes and inflammatory endotypes is a major focus of research at this time, and the concurrent rise of targeted therapeutics and biologic therapies has the potential to rapidly advance care and improve outcomes. Recent findings suggest that improved understanding of CRS phenotypic and endotypic heterogeneity, and incorporation of these characteristics into clinical care pathways, may facilitate more effective selection of surgical and/or therapeutic interventions². Ultimately, these personalized approaches have the potential to target specific inflammatory pathways, increase efficacy, reduce costs, and limit side effects. This review summarizes recent advances in the identification and characterization of CRS phenotypes, endotypes, and biomarkers and reviews potential implications for targeted therapeutics.

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.

Editing the genome of Aphanomyces invadans using CRISPR/Cas9

Background

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system is increasingly being used for genome editing experiments. It is a system to add, delete and/or replace parts of a gene in situ in a time- and cost-efficient manner. The genome of many organisms has been edited using this system. We tested the CRISPR/Cas9 system in Aphanomyces invadans, an oomycete, which is the causative agent of epizootic ulcerative syndrome (EUS) in many fish species. Extracellular proteases produced by this oomycete are believed to play a role in EUS virulence.

Methods

We designed three single guide-RNAs (gRNA) to target A. invadans serine protease gene. These gRNAs were individually combined with the Cas9 to form ribo-nucleo-protein (RNP) complex. A. invadans protoplasts were then transfected with RNP complexes. After the transfection, the target gene was amplified and subjected to sequencing. Zoospores of A. invadans were also transfected with the RNP complex. Three groups of dwarf gourami (Trichogaster lalius) were then experimentally inoculated with (i) non-treated A. invadans zoospores; (ii) RNP-treated A. invadans zoospores; and (iii) autoclaved pond water as negative control, to investigate the effect of edited serine protease gene on the virulence of A. invadans in vivo.

Results

Fluorescence microscopy showed sub-cellular localization of RNP complex in A. invadans protoplasts and zoospores. Sequencing results from the protoplast DNA revealed a point mutation in the target gene. A matching mutation was also detected in zoospores after similar treatment with the same RNP complex. In vivo results showed that the CRISPR/Cas9-treated A. invadans zoospores did not produce EUS clinical signs in the fish. These results were then confirmed by histopathological staining of the muscle sections using Gomori’s methenamine silver nitrate and hematoxylin and eosin stains.

Conclusions

Results obtained in this study indicate that the RNP complex caused effective mutation in the target gene. This hindered the production of serine protease, which ultimately impeded the manifestation of EUS in the fish. Our methods thus establish a promising approach for functional genomics studies in A. invadans and provide novel avenues to develop effective strategies to control this pathogen.

Inflammatory and Infectious Lesions of the Sinonasal Tract

The sinonasal tract is frequently affected by nonneoplastic inflammatory diseases. Inflammatory lesions of the sinonasal tract can be divided into 3 main categories: chronic rhinosinusitis, which encompasses a heterogeneous group of entities, all of which result in mucosal inflammation with or without polyps-eosinophils; infectious diseases; and autoimmune diseases and vasculitides, which can result in midline necrosis and facial deformities. This article reviews the common inflammatory lesions of the sinonasal tract with emphasis on infectious diseases, vasculitis, iatrogenic, and diseases of unknown cause. Many of these lesions can result in midline destruction and result in facial deformity.

Pathology of Fungal Rhinosinusitis: A Review

Fungal rhinosinusitis (FRS) comprises a spectrum of disease processes that vary in clinical presentation, histologic appearances, and biological significance. FRS can be acute or chronic and is most commonly classified as non-invasive or invasive based on whether fungi have invaded into tissue. This manuscript will review the pathologic classification of FRS.

The importance of local eosinophilia in the surgical outcome of chronic rhinosinusitis: a 3-year prospective observational study

BACKGROUND

Patients with chronic rhinosinusitis with/without nasal polyps (CRSwNP/CRSsNP) benefit from endoscopic sinus surgery (ESS), with an estimated success rate of 80%. At present, the influence on clinical outcome after ESS of eosinophils, eosinophilic mucin (EM), and fungal hyphae (FH) in secretions remains unclear. By delineating CRS groups and subgroups based on the finding of eosinophils, EM, and FH, differences in recurrence after ESS were investigated.

METHODS

A prospective monocenter study including 221 CRS patients who were unresponsive to medical treatment and underwent ESS was performed. All tissue and sinonasal secretions were microscopically examined for the presence of eosinophils, EM, and FH. Patients were followed for 3 years after surgery. Recurrence was defined according to the European position paper on rhinosinusitis and nasal polyps.

RESULTS

In total, 96 CRSwNP and 125 CRSsNP patients were included. Tissue eosinophils were found in 78% of CRSwNP patients compared with 42% in CRSsNP patients. EM was observed in 52% of the CRSwNP group versus 20% of the CRSsNP group. Furthermore, secretion analysis revealed FH in 7% of CRS. Recurrence in the total group was 22% over 3 years. CRSwNP patients with tissue eosinophilic involvement showed a recurrence rate of 48%, and those with additional EM showed recurrence in 56%.

CONCLUSION

The presence of eosinophils in tissue or airway secretions greatly increases the risk of recurrent disease in CRSwNP patients. The finding of tissue eosinophilia and EM provides valuable information regarding the increased likelihood of CRS recurrence after ESS, whereas the finding of FH does not.

The inflammatory response of eosinophil-related fungal rhinosinusitis varies with inciting fungi

Earlier studies demonstrated immunological response to Alternaria alternata in patients with eosinophil-related fungal rhinosinusitis (FRS). However, Aspergillus flavus rather than A. alternata is predominantly isolated from such patients in Asia. We compared immunological response to A. flavus and A. alternata in our patients with eosinophil related FRS. Total immunoglobulin E, absolute eosinophil count (AEC), cytokine response, and in vitro eosinophil degranulation in the presence of A. flavus/A. alternata were compared among patients with eosinophil-related FRS, non-eosinophilic rhinosinusitis (NECRS), and healthy individuals. Eosinophil-related FRS patients were subgrouped into: Group A - presence of mucin with fungus in tissues and positive immediate hypersensitivity; group B - presence of mucin with fungus in biopsies and no immediate hypersensitivity; and group C - presence of mucin without fungi and hypersensitivity. A. flavus was the predominant (89%) isolate. Significantly higher major basic protein (MBP) was induced by A. flavus in Group A (279.15 ± 32.29 ng/2.5 × 10(5) cells) compared to Group B (254.9 ± 17.14 ng), Group C (238.33 ± 17.56 ng), NECRS (56.96 ± 10.97 ng), and normal subjects (28.73 ± 7.04 ng). A. alternata - eosinophil interaction failed to induce detectable MBP. AEC and serum cytokines, interleukin (IL)- 2, IL-4, IL-5, IL-10, tumor necrosis factor α, and interferon-γ were significantly higher (P < 0.001) in eosinophil-related FRS compared to NECRS and control. Thus a mixed Th1 and Th2 cytokine response was observed in eosinophil-related FRS. In conclusion, immune response in eosinophil-related FRS depends on locally inciting fungi rather than A. alternata in all instances, and the categorization of this group appears to be arbitrary.

The molecular genetics of inflammatory, autoimmune, and infectious diseases of the sinonasal tract: a review

CONTEXT

The sinonasal tract is frequently affected by a variety of nonneoplastic inflammatory disease processes that are often multifactorial in their etiology but commonly have a molecular genetic component.

OBJECTIVE

To review the molecular genetics of a variety of nonneoplastic inflammatory diseases of the sinonasal tract.

DATA SOURCES

Inflammatory lesions of the sinonasal tract can be divided into 3 main categories: (1) chronic rhinosinusitis, (2) infectious diseases, and (3) autoimmune diseases/vasculitides. The molecular diagnosis and pathways of a variety of these inflammatory lesions are currently being elucidated and will shed light on disease pathogenesis and treatment.

CONCLUSIONS

The sinonasal tract is frequently affected by inflammatory lesions that arise through complex interactions of environmental, infectious, and genetic factors. Because these lesions are all inflammatory in nature, the molecular pathology surrounding them is most commonly due to upregulation and down-regulation of genes that affect inflammatory responses and immune regulation.

Antigen-specific IgE in middle ear effusion of patients with eosinophilic otitis media

BACKGROUND

Eosinophilic otitis media (EOM) is an intractable otitis media characterized by a highly viscous effusion that contains eosinophils. We previously reported that high levels of IgE were detected in middle ear effusion (MEE) of patients with EOM.

OBJECTIVE

To examine antigen-specific IgE in MEE of patients with EOM to clarify the pathogenesis of EOM.

METHODS

Twenty-six patients with EOM associated with bronchial asthma were included in this study. Antigen-specific IgE against inhalant and bacterial antigens were measured in the serum and MEE of these patients.

RESULTS

In patients with EOM, 1 or more antigen-specific IgEs were detected from the MEE of 16 of 26 patients (62%), whereas 1 of 9 control patients (11%) had antigen-specific IgE (P < .01). Total serum IgE concentrations were not different between the groups who tested positive (16 patients) and negative (10 patients) for antigen-specific IgE. None of the fungi-specific IgEs were detected in serum even though 11 patients tested positive for 1 or more fungal antigens detected in MEE. The severity score of EOM in the antigen-specific IgE-positive group was significantly higher than that in the antigen-specific IgE-negative group (P < .05).

CONCLUSION

Antigen-specific IgE against inhalant and bacterial antigens may be locally produced in the middle ear mucosa in patients with EOM. In particular, local sensitization against fungi together with Staphylococcus aureus could result in local IgE production in the middle ear and may be responsible for the severity of EOM.

Allergic sensitization in Canadian chronic rhinosinusitis patients

BACKGROUND

Chronic rhinosinusitis (CRS) is a societal burden and cause of morbidity in Canada; however, the prevalence of allergic sensitization in Canadian CRS patients has remained poorly characterized.

OBJECTIVE

In this study, we used skin prick test (SPT) and specific immunoglobulin E (sIgE) and G (sIgG) titers to regionally relevant allergen sources in order to determine whether allergic sensitization is more prevalent in CRS patients compared to chronic idiopathic urticaria (CIU) control patients.

METHODS

One hundred and fifty eight subjects (19-70 years of age) were recruited into the study. 101 subjects had a confirmed diagnostic history of CRS and 57 subjects with a clinical diagnosis of CIU were recruited as controls. Enrolled subjects underwent SPT to a panel of perennial and seasonal allergens and sIgE titers were quantified to selected environmental allergen mixes (grass, mold, and tree species) using Phadia ImmunoCAP. sIgG was additionally quantified to Alternaria alternata, Aspergillus versicolor, Cladosporium herbarum, and Stachybotrys atra. Differences between CRS and control CIU patient SPT and serological data were examined by chi-squared analysis and analysis of variance.

RESULTS

Reactivity to at least one SPT extract occurred in 73% of CRS patients. Positive SPT reactivity to A. alternata (odds ratio (OR): 4.34, 95% confidence interval: 1.57, 12.02), cat (OR: 3.23, 95% CI: 1.16, 9.02), and ragweed (OR: 2.31, 95% CI: 1.02, 5.19) extracts were more prevalent in patients with CRS (p < 0.05). Although dust mite and timothy grass sensitization approached statistical significance in the chi-squared analysis of SPT data, other common perennial and seasonal allergens were not associated with CRS. No statistically significant differences were observed between mean sIgE and sIgG titers in CRS and control patients.

CONCLUSIONS

This study supports previous data that suggests A. alternata sensitization is associated with CRS; however, these findings additionally highlight the contribution of other regionally important allergens including cat and ragweed.

Chronic illness associated with mold and mycotoxins: is naso-sinus fungal biofilm the culprit?

It has recently been demonstrated that patients who develop chronic illness after prior exposure to water damaged buildings (WDB) and mold have the presence of mycotoxins, which can be detected in the urine. We hypothesized that the mold may be harbored internally and continue to release and/or produce mycotoxins which contribute to ongoing chronic illness. The sinuses are the most likely candidate as a site for the internal mold and mycotoxin production. In this paper, we review the literature supporting this concept.

Confounding factors in rhinological research

PURPOSE OF REVIEW

Basic science studies directed at understanding the inflammatory mechanisms in chronic rhinosinusitis (CRS) are increasing, yet their relevance to the underlying disease process is often conflicting and confounded by the enrollment of a heterogeneous CRS population. This review is aimed at exploring the issues affecting the basic science mucosal studies of CRS patients, with special attention to the inclusion criteria for CRS and the control group, and the site from which the mucosal tissue sample is obtained.

RECENT FINDINGS

A common confounding factor is an inadequate documentation of selection criteria for patients, controls, and tissue sites examined. Inconsistent definitions for CRS and for maximum medical therapy, and a lack of histopathology confirmation of mucosal inflammation (eosinophilic or neutrophilic) can bias the disease population entering a given study. Further confounding factors include the influence of coexisting diseases, pollution and cigarette smoke, and a need for same-site tissue comparisons, meticulous selection of relevant controls, and consensus on 'nondiseased' mucosal inflammatory cell populations and microbiology.

SUMMARY

Documentation of well defined patient and control groups, standardized specimen collection methods, and detection assays are critical in minimizing the bias and conflicting findings among investigators. With standardized sampling of tissue sites and tight controls on subcategories of CRS patients enrolled, studies will more likely identify the findings that can increase our understanding of the disparate group of CRS patients and identify new therapeutic targets in the CRS subcategories.

From bacteria to human: a journey into the world of chitinases

Chitinases, the enzymes responsible for the biological degradation of chitin, are found in a wide range of organisms from bacteria to higher plants and animals. They participate in numerous physiological processes such as nutrition, parasitism, morphogenesis and immunity. Many organisms, in addition to chitinases, produce inactive chitinase-like lectins that despite lacking enzymatic activity are involved in several regulatory functions. Most known chitinases belong to families 18 and 19 of glycosyl hydrolases, however a few chitinases that belong to families 23 and 48 have also been identified in recent years. In this review, different aspects of chitinases and chi-lectins from bacteria, fungi, insects, plants and mammals are discussed.

Role of fungi in the pathophysiology of chronic rhinosinusitis: an update

The pathogenesis of chronic rhinosinusitis (CRS) is multi-factorial with an infectious process likely at least partly involved. While bacteria have been proposed to play a critical role in CRS, fungi have also been implicated by some investigators, although the pathogenesis of fungi in CRS represents a significant controversy among rhinologists. Fungal-associated factors believed to be involved in CRS include the ability of fungi to induce significant inflammatory reactions by different means through inducing localized cytokine production in the sinonasal tract. Despite these observations, randomized, controlled studies on CRS patients using antifungal therapy have not resulted in significant improvement in CRS patients. The role of fungi in the pathogenesis of CRS remains controversial.