CHI3L1 on fibrinolytic system imbalance in chronic rhinosinusitis with nasal polyp.

Background: Chronic rhinosinusitis (CRS) is an inflammatory disease affecting more than 10% of the global adult population. It is classified into Th1, Th2, and Th17 endotypes and eosinophilic and non-eosinophilic types. Th2-based inflammation and eosinophilic CRS (ECRS) are associated with tissue remodeling and fibrinolytic system impairment. Objective: To elucidate the role of eosinophils in inducing fibrin deposition in CRS nasal polyp tissues and explore potential regulatory mechanisms. Methods: We analyzed the expression of genes related to the serpin family and fibrinolytic system using Gene Expression Omnibus and Next-generation sequencing data. Differentially expression genes (DEGs) analysis was used to compare control and nasal polyp tissues, followed by KEGG and Gene ontology (GO) analysis. We measured the expression and correlation of plasminogen activator-1 (PAI-1), tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA), and urokinase plasminogen activator surface receptor (u-PAR) in CRS tissues, and evaluated the effect of eosinophils on the fibrinolytic system using a cytokine array and co-culture. Results: Nasal polyp tissues showed upregulated PAI-1, u-PA, and u-PAR expression and downregulated t-PA expression. Fibrinolytic system-related genes positively correlated with Th2 cytokines, except for t-PA. Eosinophil-derived Chitinase-3-like protein 1 (CHI3L1) increased PAI-1 expression and decreased t-PA levels in fibroblasts and epithelial cells. The inhibition of CHI3L1 suppresses these alterations. Conclusion: CHI3L1 contributes to fibrin deposition by impairing the fibrinolytic system during nasal polyp formation. The regulation of CHI3L1 expression may inhibit fibrin deposition and edema in ECRS, presenting a potential treatment for this condition.

[Characterizing immune microenvironment cell composition of chronic rhinosinusitis with nasal polyps based on mass cytometry technology].

Objective: To analyze the cellular composition characteristics of the nasal tissue immune microenvironment in patients with control, chronic rhinosinusitis without nasal polyps (CRSsNP), non-eosinophilic chronic rhinosinusitis with nasal polyps (neCRSwNP), and eosinophilic chronic rhinosinusitis with nasal polyps (eCRSwNP) using mass cytometry flow technology. Methods: Thirteen CRS patients who underwent endoscopic nasal surgery at the Department of Otorhinolaryngology Head and Neck Surgery of Peking Union Medical College Hospital from March to December 2022 were recruited, including 8 males and 5 females, aged 22.3 to 58.3 years. Three control mucosae were obtained from normal ethmoid or sphenoid sinuses of patients with benign tumors of the temporal fossa or non-functional pituitary adenomas who underwent endoscopic surgery, excluding allergic rhinitis and sinusitis. Sixteen clinical tissue samples (3 of control, 3 of CRSsNP, 4 of neCRSwNP, and 6 of eCRSwNP) were prepared into single-cell suspensions. Mass cytometry flow detection was performed using a combination of 42 molecular markers to analyze the differences in cell subpopulations among the groups. Data were analyzed using GraphPad Prism 9. Results: Based on the mass cytometry flow results, cells from control, CRSsNP, neCRSwNP, and eCRSwNP were divided into seven main cell subgroups, with detailed subgrouping of T/NK cells and myeloid cells. In T/NK cells, compared with the control group, the number of NK CD56bright cells increased in the CRSsNP group, while NK CD56dim cells decreased; compared with the CRSsNP group, the eCRSwNP group showed a decrease in NKT cells and CD4+Tem cells; compared with the CRSsNP group, the eCRSwNP group showed a significant increase in CD25 expression within Treg cells; compared with the CRSsNP group, the eCRSwNP group showed a significant decrease in Tbet expression in CD8+Teff cells and CD8+TRM cells; in eCRSwNP, the expression of CD103 in CD8+TRM cells was significantly lower than in CRSsNP. In myeloid cells, compared with the other three groups, the eCRSwNP group showed a significant increase in macrophages and a significant decrease in cDC1 and monocytes; compared with the control group and CRSsNP, the eCRSwNP group also showed a significant decrease in resting state macrophages; compared with the CRSsNP group, the eCRSwNP group showed a significant decrease in the level of CX3CR1 within cDC2 and monocytes; the expression levels of NLRP3 in cDC2 and macrophages in the eCRSwNP group were significantly higher than in the other three groups; compared with the control group, the expression levels of Gata3 in cDC2 and macrophages in the eCRSwNP group were also significantly increased; additionally, the expression of CCR2 within monocytes in the eCRSwNP group was lower than in the CRSsNP group. In ILC, compared with the control group, the expression of CCR6 decreased in the eCRSwNP group. Conclusions: Compared with the control group, CRSsNP, and neCRSwNP, eCRSwNP shows an increase in macrophage number, a decrease in cDC1 and resting state macrophages, and depletion of protective cells CD103+CD8+TRM. Additionally, the expression levels of CCR2 and CX3CR1 in monocytes of eCRSwNP are decreased.

Suppressor of Cytokine Signaling Proteins 3 and 5 Potentially Delineate Polarization of Th cells in Chronic Rhinosinusitis.

Background: Chronic rhinosinusitis (CRS) is an inflammatory condition classified into chronic rhinosinusitis with nasal polyps (CRSwNP) and chronic rhinosinusitis without nasal polyps (CRSsNP). Th cells manage inflammatory cells in CRS. Suppressor of Cytokine Signaling (SOCS) proteins regulate Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway in Th cells by polarizing toward Th1, Th2, and Th17 cells. This study evaluated the levels of SOCS1,3,5 in CRS patients to find associations with Th cells. Methods: In this cross-sectional study, 20 CRSwNP patients, 12 CRSsNP patients, and 12 controls participated. The infiltration of CD4+ T cells was determined using immunohistochemistry. The expression of specific transcription factors and SOCS proteins was assessed using real-time PCR. Cytokine levels were evaluated using ELISA. SOCS protein levels were investigated using western blot analysis. Results: The expression of SOCS3 increased in the CRSwNP group compared to CRSsNP and control groups (p <0.001). SOCS3 protein levels increased in the CRSwNP group compared to CRSsNP (p <0.05) and control (p <0.001) groups. Although there was a significant difference in SOCS5 expression between CRSsNP and control groups, SOCS5 protein levels were significantly different between CRSsNP and control (p <0.001) and CRSwNP (p <0.05) groups. Conclusions: Targeted therapies may be suggested for CRS by modulating SOCS3 and SOCS5 proteins that are responsible for polarization of Th cells toward Th2 or Th1 cells, respectively. JAK-STAT pathway targeting, which encompasses numerous cells, can be limited to SOCS proteins to more effectively orchestrate Th cell differentiation.

Antibody-based therapeutics for chronic rhinosinusitis with nasal polyps.

INTRODUCTION: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a prevalent inflammatory condition with heterogenous underlying endotypes, the most common being type 2 mediated inflammation. Several biologics have been developed to target specific pro-inflammatory cytokines and their receptors with proven efficacy in both quantitative and qualitative outcomes in patients with severe uncontrolled disease. However, there is an ongoing debate on the role of biologics relative to conventional therapies for CRSwNP and their efficacy in patient subgroups with non-polyp type 2 disease. AREAS COVERED: This review examines the evidence on the efficacy and safety of biologics in CRSwNP, recommendations for their use, and discusses the broader economic factors influencing their application in clinical practice. EXPERT OPINION: Emerging real-life data demonstrating the variable efficacy of the available biologics for patients with CRSwNP, coupled with the high cost compared to conventional therapies such as surgery, renders biologics to be considered as an add-on therapy in the majority of cases. However, ongoing research into increasing biologic dose intervals and novel therapies targeting alternative pathways may offer a more cost-effective and sustainable option in future.

Immunological characteristics of CD103+CD161+ T lymphocytes on chronic rhinosinusitis with nasal polyps.

Chronic rhinosinusitis with nasal polyps (CRSwNPs) is a heterogeneous disease characterized by local inflammation of the upper airway and sinus mucosa. T cell-mediated immune responses play irreplaceable roles in the pathogenesis of nasal polyps. CD161+ T cells have been implicated in the pathology of several diseases through cytokine production and cytotoxic activity. However, the immunological characteristics of CD161+ T cells in nasal mucosa are still not well understood, particularly in CRSwNPs. Our research revealed a notable enrichment of CD161+ T cells in nasal tissues compared to peripheral blood, with a significantly more infiltration of CD161+ T cells in CRSwNPs compared to control nasal samples. Phenotypical analysis found that CD161+ T cells predominantly co-expressed tissue-resident memory surface markers CD103, CD69, and CD45RO. CD161+CD103+ T cells demonstrated complicated effector functions, marked by elevated levels of PD-1, CTLA-4, IL-17, and IFN-γ and diminished expression of FoxP3 and CD25. Interestingly, despite CD161+ T cells was more abundant in polyp tissues compared to normal control tissues, and then further categorizing polyp samples into distinct groups based on clinical characteristics, only the recurrent CRSwNP group showed a significant reduction in CD161+CD8+ T cells compared to the primary CRSwNP group. This finding suggested the necessity for further research to comprehensively understand the underlying mechanisms and the broader significance of CD161+ T cells in the advancement and relapse of CRSwNPs.

Sinonasal immunoglobulin G4-related disease: a case report of an atypical and rare entity.

BACKGROUND: Immunoglobulin G4-related disease is marked by extensive inflammation and fibrosis of an unknown autoimmune component, with an overall incidence ranging from 0.78 to 1.39 per 105 person-years. Sinonasal immunoglobulin G4-related disease is atypical and exceedingly uncommon in the existing literature, frequently manifesting clinically as chronic rhinosinusitis, epistaxis, and facial pain. CASE PRESENTATION: This report describes a 25-year-old Iraqi female who has been suffering from symptoms of chronic rhinosinusitis for 8 years. Despite undergoing several surgeries, there has been no improvement in her symptoms. A tissue biopsy that revealed dense lymphoplasmocytosis with noticeable plasma cell infiltration, storiform fibrosis, and obliterative angitis, along with positive immunohistochemical staining for Immunoglobulin G4 plasma cells, finally confirmed the diagnosis of sinonasal immunoglobulin G4-related disease. The patient responded well to oral prednisolone and methotrexate treatments. CONCLUSIONS: The main objective of the current report is to raise awareness among physicians about the significance of promptly identifying and diagnosing this rarity, thus preventing the adverse consequences linked to delayed diagnosis and treatment initiation.

The role of autophagy regulated by the PI3K/AKT/mTOR pathway and innate lymphoid cells in eosinophilic chronic sinusitis with nasal polyps.

BACKGROUND: The PI3K/Akt/mTOR pathway and autophagy are important physiological processes. But their roles in eCRSwNP remains controversial. METHODS: In this study, we used the eCRSwNP mouse model, PI3K/Akt/mTOR pathway inhibitors, and autophagy inhibitors and activators to investigate the regulatory effects of the PI3K/Akt/mTOR pathway on autophagy, and their effects on eosinophilic inflammation, and tissue remodeling. The role of ILC2s in eCRSwNP was also studied, and the relationship between ILC2s and autophagy was preliminarily determined. RESULTS: Our results show that eosinophilic inflammation in eCRSwNP mice could be inhibited by promoting the autophagy; otherwise, eosinophilic inflammation could be promoted. Meanwhile, inhibition of the PI3K/Akt/mTOR pathway can further promote autophagy and inhibit eosinophilic inflammation. Meanwhile, inhibiting the PI3K/Akt/mTOR pathway and promoting autophagy can reduce the number of ILC2s and the severity of tissue remodeling in the nasal polyps of eCRSwNP mice. CONCLUSIONS: We conclude that the PI3K/Akt/mTOR pathway plays roles in eosinophilic inflammation and tissue remodeling of eCRSwNP, in part by regulating the level of autophagy. The downregulation of autophagy is a pathogenesis of eCRSwNP; therefore, the recovery of normal autophagy levels might be a new target for eCRSwNP therapy. Furthermore, autophagy might inhibit eosinophilic inflammation and tissue remodeling, in part by reducing the number of ILC2s.

The interleukin-4/interleukin-13 pathway in type 2 inflammation in chronic rhinosinusitis with nasal polyps.

Chronic rhinosinusitis with nasal polyps (CRSwNP) is predominantly a type 2 inflammatory disease associated with type 2 (T2) cell responses and epithelial barrier, mucociliary, and olfactory dysfunction. The inflammatory cytokines interleukin (IL)-4, IL-13, and IL-5 are key mediators driving and perpetuating type 2 inflammation. The inflammatory responses driven by these cytokines include the recruitment and activation of eosinophils, basophils, mast cells, goblet cells, M2 macrophages, and B cells. The activation of these immune cells results in a range of pathologic effects including immunoglobulin E production, an increase in the number of smooth muscle cells within the nasal mucosa and a reduction in their contractility, increased deposition of fibrinogen, mucus hyperproduction, and local edema. The cytokine-driven structural changes include nasal polyp formation and nasal epithelial tissue remodeling, which perpetuate barrier dysfunction. Type 2 inflammation may also alter the availability or function of olfactory sensory neurons contributing to loss of sense of smell. Targeting these key cytokine pathways has emerged as an effective approach for the treatment of type 2 inflammatory airway diseases, and a number of biologic agents are now available or in development for CRSwNP. In this review, we provide an overview of the inflammatory pathways involved in CRSwNP and describe how targeting key drivers of type 2 inflammation is an effective therapeutic option for patients.

Manifestation and associated factors of systemic and local allergy among patients with allergic fungal rhinosinusitis: An observational study.

Allergic fungal rhinosinusitis (AFRS) is a subtype of chronic rhinosinusitis, characterized by excessive immune responses to environmental molds or fungi. The diagnosis and classification of AFRS into systemic and local types remain clinically challenging due to overlapping characteristics. This study investigated the prevalence of AFRS, its manifestation and associated factors in systemic and local AFRS. A total of 200 patients diagnosed with fungal rhinosinusitis underwent both skin provocation tests (SPT) and nasal provocation tests (NPT) to confirm AFRS and classify systemic and local types. Patients were considered to have AFRS if either the SPT or NPT was positive. Among these, patients with systemic AFRS were those who had a SPT positive. Local AFRS was when patients had a negative SPT and a positive NPT. Medical history, serum total IgE level, nasal endoscopy examinations, and CT scans were also recorded. Most patients were female (65.8%), with a mean age of 55.6 years (SD = 14.4). Based on the SPT and NPT results, 31% of patients (n = 62) were diagnosed with AFRS. Among these, 54.8% (n = 34) had systemic AFRS, while 45.2% (n = 28) had local AFRS. Patients with AFRS exhibited significantly higher levels of total IgE, eosinophils, and more pronounced signs and symptoms compared to those without AFRS. However, no statistically significant differences were observed between patients with systemic AFRS and those with local AFRS. AFRS was prevalent in our study. Among patients with AFRS, both systemic AFRS and local AFRS were also prevalent. While allergic indicators and clinical presentations can aid in AFRS diagnosis, minimal distinctions were observed between systemic and local AFRS. A comprehensive assessment incorporating both local and systemic allergic responses through provocation tests, such as a combination of skin and nasal tests, is imperative for optimizing AFRS diagnosis and management.

Macrophages in CRSwNP: Do they deserve more attention?

Chronic rhinosinusitis (CRS) represents a heterogeneous disorder primarily characterized by the persistent inflammation of the nasal cavity and paranasal sinuses. The subtype known as chronic rhinosinusitis with nasal polyposis (CRSwNP) is distinguished by a significantly elevated recurrence rate and augmented challenges in the management of nasal polyps. The pathogenesis underlying this subtype remains incompletely understood. Macrophages play a crucial role in mediating the immune system's response to inflammatory stimuli. These cells exhibit remarkable plasticity and heterogeneity, differentiating into either the pro-inflammatory M1 phenotype or the anti-inflammatory and reparative M2 phenotype depending on the surrounding microenvironment. In CRSwNP, macrophages demonstrate reduced production of Interleukin 10 (IL-10), compromised phagocytic activity, and decreased autophagy. Dysregulation of pro-resolving mediators may occur during the inflammatory resolution process, which could potentially hinder the adequate functioning of anti-inflammatory macrophages in facilitating resolution. Collectively, these factors may contribute to the prolonged inflammation observed in CRSwNP. Additionally, macrophages may enhance fibrin cross-linking through the release of factor XIII-A (FAXIII), promoting fibrin deposition and plasma protein retention. Macrophages also modulate vascular permeability by releasing Vascular endothelial growth factor (VEGF). Moreover, they may disrupt the balance between Matrix Metalloproteinases (MMPs) and Tissue Inhibitors of Metalloproteinases (TIMPs), which favors extracellular matrix (ECM) degradation, edema formation, and pseudocyst development. Accumulating evidence suggests a close association between macrophage infiltration and CRSwNP; however, the precise mechanisms underlying this relationship warrant further investigation. In different subtypes of CRSwNP, different macrophage phenotypic aggregations trigger different types of inflammatory features. Increasing evidence suggests that macrophage infiltration is closely associated with CRSwNP, but the mechanism and the relationship between macrophage typing and CRSwNP endophenotyping remain to be further explored. This review discusses the role of different types of macrophages in the pathogenesis of different types of CRSwNP and their contribution to polyp formation, in the hope that a better understanding of the role of macrophages in specific CRSwNP will contribute to a precise and individualized understanding of the disease.

The oxidant-antioxidant imbalance was involved in the pathogenesis of chronic rhinosinusitis with nasal polyps.

Background: Although oxidative stress is involved in the pathophysiological process of chronic rhinosinusitis with nasal polyps (CRSwNP), the specific underlying mechanism is still unclear. Whether antioxidant therapy can treat CRSwNP needs further investigation. Methods: Immunohistochemistry, immunofluorescence, western blotting and quantitative polymerase chain reaction (qPCR) analyses were performed to detect the distribution and expression of oxidants and antioxidants in nasal polyp tissues. qPCR revealed correlations between oxidase, antioxidant enzymes and inflammatory cytokine levels in CRSwNP patients. Human nasal epithelial cells (HNEpCs) and primary macrophages were cultured to track the cellular origin of oxidative stress in nasal polyps(NPs) and to determine whether crocin can reduce cellular inflammation by increasing the cellular antioxidant capacity. Results: The expression of NOS2, NOX1, HO-1 and SOD2 was increased in nasal epithelial cells and macrophages derived from nasal polyp tissue. Oxidase levels were positively correlated with those of inflammatory cytokines (IL-5 and IL-6). Conversely, the levels of antioxidant enzymes were negatively correlated with those of IL-13 and IFN-γ. Crocin inhibited M1 and M2 macrophage polarization as well as the expression of NOS2 and NOX1 and improved the antioxidant capacity of M2 macrophages. Moreover, crocin enhanced the ability of antioxidants to reduce inflammation via the KEAP1/NRF2/HO-1 pathway in HNEpCs treated with SEB or LPS. Additionally, we observed the antioxidant and anti-inflammatory effects of crocin in nasal explants. Conclusion: Oxidative stress plays an important role in the development of CRSwNP by promoting various types of inflammation. The oxidative stress of nasal polyps comes from epithelial cells and macrophages. Antioxidant therapy may be a promising strategy for treating CRSwNP.

Butyrate inhibits type 2 inflammation in eosinophilic chronic rhinosinusitis.

Butyrate and other Short-chain fatty acids (SCFAs) are microbial metabolites from Bacteroides and Clostridium species that may suppress type 2 inflammation. However, the mechanisms of SCFAs in the nasal sinuses are not fully understood. We aimed to clarify the in vitro and in vivo roles of SCFAs in eosinophilic chronic rhinosinusitis (ECRS) pathophysiology. We investigated whether SCFAs induced changes in type 2 cytokines, IgE, and apoptosis and the roles of GPR41, GPR43, and histone deacetylase. Analysis of the control subjects demonstrated that butyrate of SCFAs effectively inhibited type 2 cytokine production in PBMCs, ILC2s, and CD4+ T cells and IgE production in CD19+ B cells. In annexin V analysis, butyrate also induced late apoptosis of PBMCs. The butyrate-induced inhibition of type 2 cytokines appeared involved in histone deacetylase inhibition but not in GPR41 or GPR43. In an analysis of ECRS in humans, butyrate inhibited type 2 cytokine production in PBMCs and nasal polyp-derived cells. The butyrate concentration in nasal lavage fluid was significantly decreased in ECRS patients compared to controls and non-ECRS patients. Our findings confirm that butyrate can inhibit type 2 inflammation and may be a potential therapeutic target for ECRS.

Eosinophilic mucus diseases.

Eosinophilic inflammation is primarily characterized by type 2 immune responses against parasitic organisms. In the contemporary human being especially in developed countries, eosinophilic inflammation is strongly associated with allergic/sterile inflammation, and constitutes an undesired immune reaction. This situation is in stark contrast to neutrophilic inflammation, which is indispensable for the host defense against bacterial infections. Among eosinophilic inflammatory disorders, massive accumulation of eosinophils within mucus is observed in certain cases, and is often linked to the distinctive clinical finding of mucus with high viscosity. Eosinophilic mucus is found in a variety of diseases, including chronic allergic keratoconjunctivitis, chronic rhinosinusitis encompassing allergic fungal sinusitis, eosinophilic otitis media, eosinophilic sialodochitis, allergic bronchopulmonary aspergillosis/mycosis, eosinophilic plastic bronchitis, and eosinophilic asthma. In these pathological conditions, chronic inflammation and tissue remodeling coupled with irreversible organ damage due to persistent adhesion of toxic substances and luminal obstruction may impose a significant burden on the body. Eosinophils aggregate in the hyperconcentrated mucus together with cell-derived crystals, macromolecules, and polymers, thereby affecting the biophysical properties of the mucus. This review focuses on the clinically significant challenges of mucus and discusses the consequences of activated eosinophils on the mucosal surface that impact mucus and persistent inflammation.

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.

Exploring the immunopathology of type 2 inflammatory airway diseases.

Significant advancements have been achieved in understanding the roles of different immune cells, as well as cytokines and chemokines, in the pathogenesis of eosinophilic airway conditions. This review examines the pathogenesis of Chronic Rhinosinusitis with Nasal Polyps (CRSwNP), marked by complex immune dysregulation, with major contributions from type 2 inflammation and dysfunctional airway epithelium. The presence of eosinophils and the role of T-cell subsets, particularly an imbalance between Treg and Th17 cells, are crucial to the disease's pathogenesis. The review also investigates the pathogenesis of eosinophilic asthma, a unique asthma subtype. It is characterized by inflammation and high eosinophil levels, with eosinophils playing a pivotal role in triggering type 2 inflammation. The immune response involves Th2 cells, eosinophils, and IgE, among others, all activated by genetic and environmental factors. The intricate interplay among these elements, chemokines, and innate lymphoid cells results in airway inflammation and hyper-responsiveness, contributing to the pathogenesis of eosinophilic asthma. Another scope of this review is the pathogenesis of Eosinophilic Granulomatosis with Polyangiitis (EGPA); a complex inflammatory disease that commonly affects the respiratory tract and small to medium-sized blood vessels. It is characterized by elevated eosinophil levels in blood and tissues. The pathogenesis involves the activation of adaptive immune responses by antigens leading to T and B cell activation and eosinophil stimulation, which causes tissue and vessel damage. On the other hand, Allergic Bronchopulmonary Aspergillosis (ABPA) is a hypersensitive response that occurs when the airways become colonized by aspergillus fungus, with the pathogenesis involving activation of Th2 immune responses, production of IgE antibodies, and eosinophilic action leading to bronchial inflammation and subsequent lung damage. This analysis scrutinizes how an imbalanced immune system contributes to these eosinophilic diseases. The understanding derived from this assessment can steer researchers toward designing new potential therapeutic targets for efficient control of these disorders.

Increased SERPINB2 potentiates 15LO1 expression via STAT6 signalling in epithelial cells in eosinophilic chronic rhinosinusitis with nasal polyps.

BACKGROUND: SERPINB2, a biomarker of Type-2 (T2) inflammatory processes, has been described in the context of asthma. Chronic rhinosinusitis with nasal polyps (CRSwNP) is also correlated with T2 inflammation and elevated 15LO1 induced by IL-4/13 in nasal epithelial cells. The aim of this study was to evaluate the expression and location of SERPINB2 in nasal epithelial cells (NECs) and determine whether SERPINB2 regulates 15LO1 and downstream T2 markers in NECs via STAT6 signalling. METHODS: SERPINB2 gene expression in bulk and single-cell RNAseq database was analysed by bioinformatics analysis. SERPINB2, 15LO1 and other T2 markers were evaluated from CRSwNP and HCs NECs. The colocalization of SERPINB2 and 15LO1 was evaluated by immunofluorescence. Fresh NECs were cultured at an air-liquid interface with or without IL-13, SERPINB2 Dicer-substrate short interfering RNAs (DsiRNAs) transfection, exogenous SERPINB2, 15-HETE recombinant protein and pSTAT6 inhibitors. 15LO1, 15-HETE and downstream T2 markers were analysed by qRT-PCR, western blot and ELISA. RESULTS: SERPINB2 expression was increased in eosinophilic nasal polyps compared with that in noneosinophilic nasal polyps and control tissues and positively correlated with 15LO1 and other downstream T2 markers. SERPINB2 was predominantly expressed by epithelial cells in NP tissue and was colocalized with 15LO1. In primary NECs in vitro, SERPINB2 expression was induced by IL-13. Knockdown or overexpression SERPINB2 decreased or enhanced expression of 15LO1 and 15-HETE in NECs, respectively, in a STAT6-dependent manner. SERPINB2 siRNA also inhibited the expression of the 15LO1 downstream genes, such as CCL26, POSTN and NOS2. STAT6 inhibition similarly decreased SERPINB2-induced 15LO1. CONCLUSIONS: SERPINB2 is increased in NP epithelial cells of eosinophilic CRSwNP (eCRSwNP) and contributes to T2 inflammation via STAT6 signalling. SERPINB2 could be considered a novel therapeutic target for eCRSwNP.

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.

Uncovering the Cellular Microenvironment in Chronic Rhinosinusitis via Single-Cell RNA Sequencing: Application and Future Directions.

Chronic rhinosinusitis (CRS) is a heterogenic disease characterized by persistent mucosal inflammation of the upper airway. Researches of CRS have progressed from phenotype-based to endotype-based, looking more deeply into molecular biomarkers, signaling pathways, and immune microenvironment. Single-cell RNA sequencing is an effective tool in analyzing composition, function, and interaction of cells in disease microenvironment at transcriptome level, showing great advantage in analyzing potential biomarkers, pathogenesis, and heterogeneity of chronic airway inflammation in an unbiased manner. In this article, we will review the latest advances in scRNA-seq studies of CRS to provide new perspectives for the diagnosis and treatment of this heterogeneous disease.

Galectin-10 in serum extracellular vesicles reflects asthma pathophysiology.

BACKGROUND: Novel biomarkers (BMs) are urgently needed for bronchial asthma (BA) with various phenotypes and endotypes. OBJECTIVE: We sought to identify novel BMs reflecting tissue pathology from serum extracellular vesicles (EVs). METHODS: We performed data-independent acquisition of serum EVs from 4 healthy controls, 4 noneosinophilic asthma (NEA) patients, and 4 eosinophilic asthma (EA) patients to identify novel BMs for BA. We confirmed EA-specific BMs via data-independent acquisition validation in 61 BA patients and 23 controls. To further validate these findings, we performed data-independent acquisition for 6 patients with chronic rhinosinusitis without nasal polyps and 7 patients with chronic rhinosinusitis with nasal polyps. RESULTS: We identified 3032 proteins, 23 of which exhibited differential expression in EA. Ingenuity pathway analysis revealed that protein signatures from each phenotype reflected disease characteristics. Validation revealed 5 EA-specific BMs, including galectin-10 (Gal10), eosinophil peroxidase, major basic protein, eosinophil-derived neurotoxin, and arachidonate 15-lipoxygenase. The potential of Gal10 in EVs was superior to that of eosinophils in terms of diagnostic capability and detection of airway obstruction. In rhinosinusitis patients, 1752 and 8413 proteins were identified from EVs and tissues, respectively. Among 11 BMs identified in EVs and tissues from patients with chronic rhinosinusitis with nasal polyps, 5 (including Gal10 and eosinophil peroxidase) showed significant correlations between EVs and tissues. Gal10 release from EVs was implicated in eosinophil extracellular trapped cell death in vitro and in vivo. CONCLUSION: Novel BMs such as Gal10 from serum EVs reflect disease pathophysiology in BA and may represent a new target for liquid biopsy approaches.