Staphylococcus aureus enterotoxin B contributes to induction of nasal polypoid lesions in an allergic rhinosinusitis murine model

Murine model of eosinophilic chronic rhinosinusitis with nasal polyposis inducing neuroinflammation and olfactory dysfunction

BACKGROUND

Chronic rhinosinusitis (CRS) is a common inflammatory condition affecting the nasal and paranasal sinus mucosa, often accompanied by olfactory dysfunction. Eosinophilic CRS with nasal polyps (ECRSwNP) is a subtype of CRS characterized by eosinophilic infiltration. Animal models for ECRSwNP with olfactory dysfunction are necessary for exploring potential therapeutic strategies.

OBJECTIVE

The aim of this study was to establish a mouse model of ECRSwNP combined with olfactory dysfunction in a shorter time frame using intranasal ovalbumin and Aspergillus protease (AP) administration. The efficacy of the model was validated by evaluating sinonasal inflammation, cytokine levels, olfactory function, and neuroinflammation in the olfactory bulb.

METHODS

Male BALB/c mice were intranasally administered ovalbumin and AP for 6 and 12 weeks to induce ECRSwNP. The resultant ECRSwNP mouse model underwent histologic assessment, cytokine analysis of nasal lavage fluid, olfactory behavioral tests, and gene expression profiling to identify neuroinflammatory markers within the olfactory bulb.

RESULTS

The developed mouse model exhibited substantial eosinophil infiltration, increased levels of inflammatory cytokines in nasal lavage fluid, and confirmed olfactory dysfunction through behavioral assays. Furthermore, olfactory bulb inflammation and reduced mature olfactory sensory neurons were observed in the model.

CONCLUSION

This study successfully established a validated mouse model of ECRSwNP with olfactory dysfunction within a remarkably short span of 6 weeks, providing a valuable tool for investigating the pathogenesis and potential therapies for this condition. The model offers an efficient approach for future research in CRS with nasal polyps and olfactory dysfunction.

Novel insights into the immune response to bacterial T cell superantigens

Bacterial T cell superantigens (SAgs) are a family of microbial exotoxins that function to activate large numbers of T cells simultaneously. SAgs activate T cells by direct binding and crosslinking of the lateral regions of MHC class II molecules on antigen-presenting cells with T cell receptors (TCRs) on T cells; these interactions alter the normal TCR-peptide-MHC class II architecture to activate T cells in a manner that is independent of the antigen specificity of the TCR. SAgs have well-recognized, central roles in human diseases such as toxic shock syndrome and scarlet fever through their quantitative effects on the T cell response; in addition, numerous other consequences of SAg-driven T cell activation are now being recognized, including direct roles in the pathogenesis of endocarditis, bloodstream infections, skin disease and pharyngitis. In this Review, we summarize the expanding family of bacterial SAgs and how these toxins can engage highly diverse adaptive immune receptors. We highlight recent findings regarding how SAg-driven manipulation of the adaptive immune response may operate in multiple human diseases, as well as contributing to the biology and life cycle of SAg-producing bacterial pathogens.

Neutrophil extracellular traps promote ΔNp63+ basal cell hyperplasia in chronic rhinosinusitis

BACKGROUND

Neutrophil extracellular traps (NETs) are observed in chronic rhinosinusitis (CRS), although their role remains unclear.

OBJECTIVES

This study aimed to investigate the influence of NETs on the CRS epithelium.

METHODS

Forty-five sinonasal biopsy specimens were immunofluorescence-stained to identify NETs and p63+ basal stem cells. Investigators treated human nasal epithelial cells with NETs and studied them with immunofluorescence staining, Western blotting, and quantitative real-time PCR. NET inhibitors were administered to a murine neutrophilic nasal polyp model.

RESULTS

NETs existed in tissues in patients with CRS with nasal polyps, especially in noneosinophilic nasal polyp tissues. p63+ basal cell expression had a positive correlation with the release of NETs. NETs induced the expansion of Ki-67+p63+ cells. We found that ΔNp63, an isoform of p63, was mainly expressed in the nasal epithelium and controlled by NETs. Treatment with deoxyribonuclease (DNase) I or Sivelestat (NET inhibitors) prevented the overexpression of ΔNp63+ epithelial stem cells and reduced polyp formation.

CONCLUSIONS

These results reveal that NETs are implicated in CRS pathogenesis via basal cell hyperplasia. This study suggests a novel possibility of treating CRS by targeting NETs.

Host-microbe interactions in chronic rhinosinusitis biofilms and models for investigation

Chronic rhinosinusitis (CRS) is a debilitating condition characterized by long-lasting inflammation of the paranasal sinuses. It affects a significant portion of the population, causing a considerable burden on individuals and healthcare systems. The pathogenesis of CRS is multifactorial, with bacterial infections playing a crucial role in CRS development and persistence. In recent years, the presence of biofilms has emerged as a key contributor to the chronicity of sinusitis, further complicating treatment and exacerbating symptoms. This review aims to explore the role of biofilms in CRS, focusing on the involvement of the bacterial species Staphylococcus aureus and Pseudomonas aeruginosa, their interactions in chronic infections, and model systems for studying biofilms in CRS. These species serve as an example of how microbial interplay can influence disease progression and exemplify the need for continued investigation and innovation in CRS research.

Which are the best murine models to study Eosinophilic Chronic Rhinosinusitis? A contemporary review

OBJECTIVE

Mechanisms that lead to Eosinophilic Chronic Rhinosinusitis (ECRS) are not fully established in the literature. It is desirable to assess ECRS in a model that embraces most of the related events. This article reviewed the murine models for ECRS and compared them regarding eosinophilic polypoid formation.

METHODS

The authors reviewed the articles that included the terms "chronic rhinosinusitis" OR "chronic sinusitis" AND "animal model". We analyzed articles in English that evaluated both the number of polyps and the number of eosinophils in the sinus mucosa of mouse models.

RESULTS

We identified a total of 15 articles describing different models of ECRS that used BALB/c or C57BL/6 mice, and different triggers/stimulants such as Staphylococcus aureus Enterotoxin B (SEB) + Ovalbumin (OVA); House Dust Mite (HDM) ± Ovalbumin (OVA); and Aspergillus oryzae Protease (AP) + Ovalbumin (OVA). OVA associated with SEB was the commonest protocol to induce ECRS in both BALB/c and C57BL/6 mice, and it produced a robust response of eosinophilic nasal polyps in both. AP + OVA protocol also led to a good ECRS response. The other models were not considered adequate to produce eosinophilic polyps in mice.

CONCLUSION

In conclusion, OVA associated with SEB seems to produce the most robust eosinophilic sinonasal inflammation.

Hypoxia induces the production of epithelial-derived cytokines in eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Hypoxia plays a significant role in the pathogenesis of chronic rhinosinusitis (CRS). However, the role and mechanism of hypoxia in the type 2 immune response in eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) remain unclear.

METHODS

The expression of hypoxia-inducible factor-1α (HIF-1α) and epithelial-derived cytokines (EDCs), including interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin (TSLP), was detected in nasal polyps via immunohistochemical analysis. The relationship between HIF-1α and EDCs was also elucidated using Pearson's correlation. Moreover, primary human nasal epithelial cells (HNECs) and a mouse model of ECRSwNP were employed to elucidate the role and mechanism of hypoxia in type 2 immune responses.

RESULTS

HIF-1α, IL-25, IL-33, and TSLP expression levels were upregulated in the non-ECRSwNP and ECRSwNP groups compared with the control group, with the ECRSwNP group having the highest HIF-1α and EDC expression levels. Additionally, HIF-1α was positively correlated with IL-25 and IL-33 in the ECRSwNP group. Meanwhile, treatment with a HIF-1α inhibitor, PX-478, inhibited the hypoxia-induced increase in the mRNA and protein expression of EDCs and type 2 cytokines in HNECs. Similarly, in vivo, PX-478 inhibited EDC expression in the sinonasal mucosa of mice with ECRSwNP.

CONCLUSIONS

Hypoxia induces EDC expression by upregulating HIF-1α levels, thereby promoting type 2 immune responses and the development of ECRSwNP. Hence, targeting HIF-1α may represent an effective therapeutic strategy for ECRSwNP.

Murine model for chronic rhinosinusitis: an interventional study

BACKGROUND

Chronic rhinosinusitis (CRS) is a complex inflammatory disease of the sinonasal tract. To understand this disease entity and develop targeted treatments, a reproducible animal model is paramount.

AIMS/OBJECTIVES

To optimize a murine model of eosinophilic CRS by establishing benchmark histological markers and validate its fidelity in evaluating intranasal treatments.

MATERIAL AND METHODS

Forty-five Balb/c mice were included in the 7-week protocol. Experimental animals (n = 20) were induced a CRS disease state upon receiving intraperitoneal sensitization with ovalbumin (OVA), followed by intranasal OVA with Aspergillus oryzae protease. Analysis of complete blood count with differential, peripheral blood smear, and histological markers from the nasal cavity mucosa were performed. CRS mice were additionally treated with intranasal saline (n = 5) or mometasone (n = 10) and compared with control groups of untreated CRS (n = 5) and healthy (n = 5) mice after week 7.

RESULTS

Histological analysis of experimental animal nasal mucosa revealed significantly higher levels of eosinophilic tissue infiltration/degranulation, hyaline droplets, Charcot-Leyden crystals, and respiratory epithelial thickness compared to healthy controls. Treatment with mometasone significantly reversed the histopathological changes observed in CRS mice.

CONCLUSION AND SIGNIFICANCE

This murine model induced substantial local eosinophilic inflammation within sinonasal mucosa, that was reversible with mometasone. This model may be used to evaluate the efficacy of therapeutics designed to target CRS.

Hypoxia disrupts the nasal epithelial barrier by inhibiting PTPN2 in chronic rhinosinusitis with nasal polyps

BACKGROUND

Hypoxia is involved in inflammation and immune response; however, its role in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) is not fully understood. We aimed to investigate the mechanisms by which hypoxia disrupts the nasal epithelial barrier in CRSwNP.

METHODS

The expression of hypoxia-inducible factor-1α (HIF-1α), protein tyrosine phosphatase non-receptor type 2 (PTPN2), and tight junction (TJ) components (claudin-4, occludin, and ZO-1) was detected in nasal polyps using immunohistochemistry, western blotting, and qRT-PCR. Primary human nasal epithelial cells (HNECs), BEAS-2B cells, and an eosinophilic CRSwNP (Eos CRSwNP) mouse model were used to explore the potential mechanisms by which hypoxia disrupts the nasal epithelial barrier.

RESULTS

HIF-1α expression in the non-Eos and Eos CRSwNP groups was higher than in the control group, and the expression of PTPN2 and TJs in the non-Eos and Eos CRSwNP groups were lower than those in the control group. Hypoxia decreased the expression of PTPN2 and TJs and increased epithelial cell permeability in HNECs, which was blocked by the HIF-1α inhibitor PX-478. PTPN2 overexpression inhibited hypoxia-induced downregulation of TJ expression in BEAS-2B cells, whereas PTPN2-knockdown aggravated the effects of hypoxia. In the Eos CRSwNP mouse model, both PX-478 and PTPN2 overexpression reduced the formation of nasal polypoid lesions, permeability of the nasal epithelium, and restored TJ expression.

CONCLUSIONS

Our data indicate that hypoxia-induced HIF-1α downregulates TJ expression by inhibiting PTPN2, thereby disrupting the nasal epithelial barrier and promoting CRSwNP development. HIF-1α and PTPN2 may be potential targets for the treatment of CRSwNP.

Scientific Advancements That Empower Us to Understand CRS Pathophysiology

BACKGROUND

Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a multifactorial inflammatory condition that remains poorly understood. Over the past decade, we have witnessed impressive scientific advancements that have allowed us to better understand the molecular and cellular mechanisms that underlie the inflammatory processes in mucosal diseases including asthma, allergic rhinitis, and CRSwNP.

OBJECTIVE

The present review aims to summarize and highlight the most recent scientific advancements that have enriched our understanding of CRSwNP.

METHODS

A comprehensive review of the available literature on the use of new scientific techniques in CRSwNP was performed. We evaluated the most recent evidence from studies using animal models, cell cultures, and genome sequencing techniques and their impact on our understanding of CRSwNP pathophysiology.

RESULTS

Our understanding of CRSwNP has rapidly progressed with the development of newer scientific techniques to interrogate various pathways involved in its pathogenesis. Animal models remain powerful tools and have elucidated the mechanisms behind esinophilic inflammation in CRSwNP; however, animal models reproducing polyp formation are relatively sparse. 3D cell cultures have significant potential to better dissect the cellular interactions with the sinonasal epithelium and other cell types in CRS. Additionally, some groups are starting to utilize single-cell RNA sequencing to investigate RNA expression in individual cells with high resolution and on a genomic scale.

CONCLUSION

These emerging scientific technologies represent outstanding opportunities to identify and develop more targeted therapeutics for different pathways that lead to CRSwNP. An additional understanding of these mechanisms will be critical for developing future therapies for CRSwNP.

Lipopolysaccharide-Initiated Rhinosinusitis Causes Neuroinflammation and Olfactory Dysfunction in Mice

Background

Olfactory dysfunction is a common disease and it may be caused by sinonasal inflammation, toxin inhalation, or neurological disorders. After sinonasal inflammation, if both olfactory neuroinflammation and olfactory dysfunction occur still under investigation.

Objective

This study aimed to investigate whether neuroinflammation and olfactory dysfunction occur after lipopolysaccharide (LPS)-initiated rhinosinusitis.

Methods

Adult C57BL/6 mice were intranasally administered with LPS for 3 weeks. The olfactory function was evaluated with a buried food test. The inflammatory status of sinonasal cavity and olfactory bulb was evaluated with histology and biochemistry.

Results

After 3-week LPS treatment, mice developed olfactory dysfunction, sinonasal cavity, and olfactory bulb inflammation. LPS-treated mice had greater sinonasal mucosal thickness. Besides, pro-inflammatory interleukin-6, the number of goblet cells and neutrophils in the sinonasal cavity was increased after LPS administration. The olfactory sensory neurons in the olfactory epithelium and the olfactory bulb were decreased, and the olfactory function was impaired by LPS administration. Inflammatory cytokines such as interferon-γ and tumor necrosis factor-α were increased in the olfactory bulb.

Conclusion

This study showed that LPS-initiated rhinosinusitis caused olfactory neuroinflammation and olfactory dysfunction in mice.

TIM-4 in macrophages contributes to nasal polyp formation through the TGF-β1–mediated epithelial to mesenchymal transition in nasal epithelial cells

Chronic rhinosinusitis with nasal polyps (CRSwNP) is caused by prolonged inflammation of the paranasal sinus mucosa. The epithelial to mesenchymal transition (EMT) is involved in the occurrence and development of CRSwNP. The T-cell immunoglobulin domain and the mucin domain 4 (TIM-4) is closely related to chronic inflammation, but its mechanism in CRSwNP is poorly understood. In our study, we found that TIM-4 was increased in the sinonasal mucosa of CRSwNP patients and, especially, in macrophages. TIM-4 was positively correlated with α-SMA but negatively correlated with E-cadherin in CRS. Moreover, we confirmed that TIM-4 was positively correlated with the clinical parameters of the Lund-Mackay and Lund-Kennedy scores. In the NP mouse model, administration of TIM-4 neutralizing antibody significantly reduced the polypoid lesions and inhibited the EMT process. TIM-4 activation by stimulating with tissue extracts of CRSwNP led to a significant increase of TGF-β1 expression in macrophages in vitro. Furthermore, coculture of macrophages and human nasal epithelial cells (hNECs) results suggested that the overexpression of TIM-4 in macrophages made a contribution to the EMT process in hNECs. Mechanistically, TIM-4 upregulated TGF-β1 expression in macrophages via the ROS/p38 MAPK/Egr-1 pathway. In conclusion, TIM-4 contributes to the EMT process and aggravates the development of CRSwNP by facilitating the production of TGF-β1 in macrophages. Inhibition of TIM-4 expression suppresses nasal polyp formation, which might provide a new therapeutic approach for CRSwNP.

The role of Staphylococcus aureus enterotoxin B in chronic rhinosinusitis with nasal polyposis

CRS with nasal polyps (CRSwNP) is a multifactorial disease, and various etiological factors like bacterial superantigens are known to develop this disease. Recent studies reported that Staphylococcus aureus nasal colonization was detected in 67% of the patients with CRSwNP. Moreover, it was reported that specific IgE against S. aureus enterotoxins are discovered in almost half of the nasal tissue homogenates from nasal polyps. Thus, investigations have highlighted the role of staphylococcal enterotoxins, especially enterotoxin B (SEB), in pathogenesis of CRSwNP. The destruction of mucosal integrity was reported as a main SEB-related pathogenic mechanisms in CRSwNP. SEB activates Toll Like Receptor 2 and triggers the production of pro-inflammatory cytokines; furthermore, it induces reactive oxygen species and endoplasmic reticulum stress-induced inflammation that may cause epithelial cell integrity disruption and enhance their permeability. SEB-induced Type 2/Th2 pathway results in degranulation of eosinophils, cationic proteins production, and localized eosinophilic inflammation. Furthermore, SEB may be involved in the expression of RORC and HIF-1α in Tregs and by maintaining the inflammation in sinonasal mucosa that could have a main role in the pathogenesis of nasal polyposis. Different in vitro findings were confirmed in animal studies; however, in vivo analysis of SEB-induced nasal polyps and CRS remains unfulfilled due to the lack of appropriate animal models. Finally, after elucidating different aspects of SEB pathogenesis in CRSwNP, therapeutic agents have been tested in recent studies with some encouraging results. The purpose of this article is to summarize the most important findings regarding SEB-induced CRS and nasal polyposis.

The role of fungus in the pathogenesis of chronic rhinosinusitis

PURPOSE OF REVIEW

The etiologic role of fungi in chronic rhinosinusitis remains controversial. The purpose of this review is to further our understanding of molecular immunologic pathways activated by fungi and clinical trials of antifungals in severe subtypes of asthma and allergic fungal rhinosinusitis.

RECENT FINDINGS

Various fungal components such as protease and chitin are capable of eliciting a type 2 innate and adaptive immune response. However, definitive studies on the etiologic role of fungi in chronic rhinosinusitis (CRS) is dependent on the development of a fungi-induced murine model of CRS. Short of this model, extrapolations of observations and results from clinical trials in fungi-induced asthma subtypes support a key role of fungi in the pathophysiology of allergic fungal rhinosinusitis and possibly other CRS endotypes.

SUMMARY

Fungi plays a key role in the pathophysiology of several subtypes of chronic inflammatory respiratory diseases. However, a fungi-induced murine model of CRS is needed to explicitly investigate the molecular pathways and potential therapeutic targets.

STAT1 mediates the PI3K/AKT pathway through promoting microRNA-18a in nasal polyps

BACKGROUND

Epithelial to mesenchymal transition (EMT) is linked to the pathophysiology of chronic rhinosinusitis with nasal polyps (CRSwNP). The involvement of STAT1 has been reported in CRSwNP. However, its specific role in regulating EMT in CRSwNP is not clear. We sought to evaluate the role of STAT1 in EMT in CRSwNP using clinical samples and a murine model.

METHODS

Comprehensive analysis of differentially expressed genes was performed in nasal polyps from the CRSwNP patients, followed by pathway enrichment analysis. After bioinformatics prediction, the relationships between microRNA-18a (miR-18a) and PTEN or STAT1 were examined using dual-luciferase and RIP assays, respectively. The expression of STAT1, PTEN, and miR-18a in nasal tissues was detected using RT-qPCR, immunohistochemistry, and in situ hybridization. After the alteration of gene expression in mice with CRSwNP, western blot, RT-qPCR, and HE staining were conducted to detect EMT-related proteins, inflammatory factor secretion, inflammatory cell infiltration, and the PI3K/AKT pathway activity in nasal tissues.

RESULTS

STAT1 and miR-18a were highly expressed, and PTEN was poorly expressed in the nasal polyp. STAT1 promoted transcription of miR-18a, which targeted PTEN. Downregulation of STAT1 and miR-18a inhibited the EMT and inflammatory cell infiltration, while depletion of PTEN promoted the EMT and inflammatory cell infiltration in the nasal polyp. The PI3K/AKT pathway was activated in the nasal polyp and regulated by the STAT1/miR-18a/PTEN axis.

CONCLUSIONS

STAT1 acts as a transcription factor to promote transcription of miR-18a, and miR-18a targets PTEN to exacerbate the inflammatory response and EMT in CRSwNP.

Transcription Factor Specificity Protein 1 Regulates Inflammation and Fibrin Deposition in Nasal Polyps Via the Regulation of microRNA-125b and the Wnt/β-catenin Signaling Pathway

Nasal polyps (NPs) are multifactorial soft growths inside the nasal passages and are associated with chronic inflammation that originate from the nasal and paranasal sinus mucosae. This study focused on the role of microRNA (miR)-125b and the molecules associated with NP development. Differentially expressed miRNAs between nasal tissues from patients with chronic rhinosinusitis (CRS) with NP (CRSwNP) and CRS without NP (CRSsNP) were screened using microarray analysis. A murine model of CRSwNP was established. The expression of miR-125b in murine tissues was examined using reverse transcription quantitative polymerase chain reaction. Candidate upstream regulators of miR-125b were predicted using bioinformatics tools, and the binding relationship between specificity protein 1 (Sp1) and miR-125b was validated using luciferase and chromatin immunoprecipitation assays. Altered expression of Sp1 and miR-125b was induced to evaluate their relevance to the progression of NPs. miR-125b expression was significantly upregulated in NP tissues from patients with CRSwNP. Sp1 was confirmed as an upstream regulator that promotes miR-125b transcription in NPs. Overexpression of Sp1 reduced levels of d-dimer (an indicator of fibrinogen degradation products) and tissue-type plasminogen activator (t-PA) but increased eosinophil cationic protein and peroxidase levels, as well as the levels of inflammatory factors interleukin-5 (IL-5) and IL-8 in murine NP tissues. However, these trends were reversed after miR-125b downregulation. Sp1 and miR-125b were found to activate the Wnt/β-catenin signaling pathway in NPs. This study demonstrated that Sp1, an upstream transcription factor of miR-125b, accumulates on the miR-125b promoter to activate its transcription, which induces inflammation and fibrin deposition in NP by activating the Wnt/β-catenin axis.

Activation of STAT6 by intranasal allergens correlated with the development of eosinophilic chronic rhinosinusitis in a mouse model

Eosinophilic chronic rhinosinusitis (ECRS) is a chronic inflammatory disease characterized by prominent eosinophilic infiltration along with a T-helper-2 (Th2) response. It has been well documented that signal transducer and activator of transcription 6 (STAT6) is a nuclear transcription factor that mediates Th2-type immunity and is implicatory of STAT1 and STAT3 in the pathogenesis of allergic airway diseases. However, little is known about the association between STATs and ECRS. Here, we explored the relationship between STAT1, STAT3, and/or STAT6 and eosinophilic inflammation accompanied by Th2-type immunity in a mouse model of ECRS. An ovalbumin (OVA)-staphylococcal enterotoxin B (SEB)-induced ECRS murine model was first established. The mucosal histological alterations were determined using hematoxylin and eosin staining. The number of eosinophils in peripheral blood was measured using a blood cell analyzer. The cytokine (IL-4, IL-5, IL17 A and IFN-γ) expression levels in the sinonasal mucosa and total and OVA-specific IgE from serum were measured using ELISA. Then, the protein levels of STAT1, STAT3, STAT6, phosphorylated STAT1 (p-STAT1), p-STAT3, p-STAT6, T-box expressed in T-cells (T-bet), GATA binding protein 3 (GATA-3), and retinoic acid receptor-related orphan receptor γ (RORγt) in the sinonasal mucosa were examined by immunohistochemical staining or Western blotting. Local administration of OVA combined with SEB (OVA + SEB) induced multiple polyp-like lesions, accompanied by prominent eosinophilic infiltration in the sinonasal mucosa. The OVA- and OVA+SEB-treated groups showed significantly higher eosinophil counts from peripheral blood and total and OVA-specific IgE levels from serum than those in the PBS- and SEB-treated groups. The levels of p-STAT6 were markedly increased by OVA + SEB exposure, as well as GATA-3, IL-4, and IL-5, but did not affect STAT6, p-STAT1, p-STAT3, T-bet, RORγt, IFN-γ, or IL-17A. Furthermore, an eosinophil count in the sinonasal mucosa showed a positive correlation with the level of p-STAT6 in the ECRS mouse model. Signal transducer and activator of transcription 6 signaling could be activated in the OVA+SEB-induced ECRS model and might be a crucial signal transducer in the development of Th2-skewed ECRS.

A Fronto-ethmoidal Sinus Mucocele presenting with optic disc edema

The frontal and anterior ethmoidal sinus mucoceles may enlarge progressively and invade into the orbit by destructing the bony walls of the sinuses leading to diplopia or proptosis, but it rarely result in optic nerve impairment. We report on a case of fronto-ethmoidal sinus mucoceles presenting with unilateral optic disc edema without visual disturbances. Ocular manifestations, radiographic techniques, and histopathological evaluation were used to make the diagnosis. Early diagnosis through a combination of ophthalmological examinations and radiographic techniques is imperative in patients with fronto-ethmoidal sinus mucoceles presenting with optic disc edema. It is important for the ophthalmologist to be aware of the ocular manifestations associated with sinus mucoceles to avoid misdiagnosis.

High chemokine ligand 11 levels in nasal lavage fluid: A potential predictor of and therapeutic target for murine eosinophilic chronic rhinosinusitis

AIM

We aimed to discover whether group 2 innate lymphoid cells (ILC2s) and cytokines in nasal lavage fluid could be used to predict eosinophilic infiltration in mice with eosinophilic chronic rhinosinusitis (ECRS).

METHODS

Ten mice were divided into two groups. The ECRS group received an intranasal challenge of Aspergillus oryzae protease (AP) and ovalbumin (OVA) to establish disease. A control group received intranasal phosphate-buffered saline. Histopathology of nasal cavities and paranasal sinuses, and cytokine and ILC2s levels in nasal lavage fluid were analyzed and compared between the ECRS and control mouse groups.

KEY FINDINGS

ILC2s numbers were not significantly higher in the nasal lavage fluid of the ECRS group mice compared with those of the control group. Eotaxin/chemokine (CC motif) ligand 11 (CCL11) levels were significantly higher in the nasal lavage fluid of mice in the ECRS group compared with those in the control group. However, no statistical differences were seen in the classic proinflammatory cytokines, IL-33, IL-25, and thymic stromal thymopoietin (TSLP), or the classic type 2 cytokines, IL-4, IL-5, and IL-13 between groups.

SIGNIFICANCE

Eotaxin/CCL11 levels in nasal lavage fluid rather than that of ILC2s and classic proinflammatory and type 2 cytokines were significantly higher in ECRS mice compared with control ones. Eotaxin/CCL11 showed diagnostic and therapeutic value; however, more studies are needed to test and verify its value.

Effect of lipopolysaccharide and polyinosinic:polycytidylic acid in a murine model of nasal polyp

Several factors, including bacterial and viral infections, have been associated with rhinosinusitis and nasal tissue remodelling that may result in nasal polyp formation. However, the potential role of bacterial or viral stimuli triggering polyp development is unclear. Here, we used lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid [poly(I:C)] in a murine model of allergic rhinosinusitis to compare different effects of bacterial- and virus-derived stimuli in the pathogenesis of nasal polyp formation. Briefly, BALB/c mice were sensitised and challenged with ovalbumin and staphylococcal enterotoxin, with or without LPS or poly(I:C), and the consequent histopathological profiles, cytokines, and systemic humoral responses were studied. While no significant differences in polyp formations and epithelial disruptions were observed among the experimental groups, the local cell recruitment patterns slightly differed in animals that received either LPS or poly(I:C). Additionally, the local immune environments generated by LPS or poly(I:C) stimulation varied. LPS stimulation induced a marked Th1/Th17 response and predominantly neutrophilic nasal polyp formations, whereas poly(I:C) induced a Th2-skewed environment in neutrophilic nasal polyp development. Overall, our findings show that both cell recruitment patterns and local immune environments induced by these two stimuli differ, which may have implications in the physiopathology of rhinosinusitis with nasal polyp.

Role of specific IgE on staphylococcal enterotoxin B in chronic rhinosinusitis severity

OBJECTIVE

To investigate the clinical significance of specific IgE-staphylococcal enterotoxin B (IgE-SEB) in CRS (chronic rhinosinusitis).

DESIGN

Retrospective analysis of patients who were positive for specific IgE-staphylococcal enterotoxin B.

SETTING

Tertiary rhinology clinic.

PARTICIPANTS

A total of 965 patients who were tested for specific IgE-staphylococcal enterotoxin B from December 2016 to December 2017.

MAIN OUTCOME MEASURES

We retrospectively reviewed the records of 965 patients who were tested for specific IgE-staphylococcal enterotoxin B from December 2016 to December 2017. Patient demographics, titre-specific IgE to staphylococcal enterotoxin B levels, MAST, serologic test and medical records were reviewed.

RESULTS

IgE-SEB (KU/L) was higher in CRS patients than non-CRS patients (0.13 ± 0.37 vs 0.08 ± 0.22, respectively; P-value: .044), and the IgE-SEB (+, ≥0.35) rate was also higher (10.06% vs 4.46%, respectively; P-value: .030). IgE-SEB (KU/L) was higher in the CRS group than in the fungal sinusitis group (0.13 ± 0.37 vs 0.03 ± 0.05, respectively; P-value: <.001), and the IgE-SEB (+, ≥0.35) rate was also higher (10.06% vs 0%, respectively; P-value: .015). Between the CRSsNP (chronic rhinosinusitis without nasal polyps) and CRSwNP (chronic rhinosinusitis with nasal polyps) groups, there were no differences in IgE-SEB (KU/L) or IgE-SEB (+) rates. IgE-SEB positivity was not associated with the presence of polyps, concomitant asthma or postoperative recurrence. As the values of IgE-SEB (KU/L) and the IgE-SEB (+, >0.1) rate increased, the CRS severity also increased.

CONCLUSIONS

IgE-SEB showed a positive correlation with Lund-Mackay CT severity score, but not with postoperative recurrence or nasal polyps. Further studies are needed to obtain clear evidence that IgE-SEB can be considered as an independent CRS endotype.

Therapeutic Effects of Intranasal Tofacitinib on Chronic Rhinosinusitis with Nasal Polyps in Mice

OBJECTIVES

The Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway play a key role in immune modulation, especially in the polarization of T helper cells. JAK inhibitors reduce inflammation by inhibiting the phosphorylation of STAT. We investigated whether a JAK inhibitor, tofacitinib, can reduce inflammation in a mouse model of chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

An eosinophilic CRSwNP model was induced using 4-week-old BALB/c mice. The therapeutic effects of topical tofacitinib were compared with the effects of triamcinolone acetonide (TAC). Polyp formation and eosinophilic infiltration were assessed by histology. Levels of phosphorylated STAT (pSTAT), eosinophil cationic protein, and eotaxin were measured by immunohistochemistry. Gene expression levels of GATA-3 was measured using quantitative PCR. The production of cytokines in sinonasal tissues, including interleukin IL-4, IL-5, IL-12, and interferon-γ, were measured using enzyme-linked immunosorbent assays (ELISA).

RESULTS

Topical tofacitinib administration significantly reduced the number of polyp-like lesions and the degree of eosinophilic infiltration, with an efficacy comparable with that of systemic TAC administration. Similarly, the levels of pSTAT6, eosinophil cationic protein, and eotaxin decreased with tofacitinib treatment. Tofacitinib decreased the gene expression level of GATA-3. Lastly, tofacitinib significantly decreased IL-4 and IL-5 production to a similar extent as that by systemic or topical TAC administration. Tofacitinib, but not TAC, significantly increased the production of interferon-γ.

CONCLUSION

Topical tofacitinib administration may be an effective treatment for eosinophilic CRSwNP by inhibiting phosphorylation of STATs.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 131:E1400-E1407, 2021.

Crosstalk Between Mucosal Inflammation and Bone Metabolism in Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a multifactorial and highly heterogeneous upper airway disease that affects approximately 12% of the general population. There is increasing evidence supporting the impact of osteitis on the pathophysiology of CRS. Osteitis is frequently observed in patients with CRS, and is associated with severe sinonasal inflammation and recalcitrant cases. The overlying inflammatory sinonasal mucosa plays a critical role in the initiation of osteitis; however, the underlying molecular mechanisms and functional significance remain unclear. Increasingly many studies have suggested that immune cells play a crucial role in the bone remodeling process in CRS. The purpose of this review is to summarize the current state of knowledge regarding the specific role of sinonasal inflammation in bone remodeling in CRS patients.

Interleukin-17A Expression Correlated with the Prognosis of Chronic Rhinosinusitis with Nasal Polyps and the Anti-Interleukin-17A Effect in a Murine Nasal Polyps Model

OBJECTIVE

To investigate the expression of interleukin-17A (IL-17A) in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and to analyze its effect on prognosis and to explore the role and mechanism of anti-IL-17A effect in vivo by establishing a murine nasal polyps (NP) model.

METHODS

Patients with CRSwNP who underwent endoscopic sinus surgery and matched control subjects were collected. We investigated IL-17A expression in human NP tissues using immunohistochemistry and analyzed their clinical features, including Lund-Mackay computed tomography scoring (LMCS) before surgery, Lund-Kennedy endoscopic scoring (LKES) before surgery (LKES B), LKES 6 months after surgery (LKES A), and reduction of LKES (LKES R). Then, after establishing the murine NP model to detect the expression and correlation of IL-17A and matrix metalloproteinase-9 (MMP-9) in nasal tissue, we studied nasal lavage fluid and serum by PCR and enzyme-linked immunosorbent assay in vivo. Anti-IL-17A treatment was administered in the murine NP model to confirm the function of IL-17A during the pathogenic processes.

RESULTS

IL-17A expression was upregulated in NP tissues from patients with CRSwNP compared with control subjects (p < 0.001). The number of IL-17A+ cells was significantly negatively correlated with LKES R in patients with CRSwNP (p < 0.01). However, there was no significant correlation between IL-17A and LMCS or LKES B (all p < 0.05). Further, IL-17A and MMP-9 were more abundant in nasal mucosa of the murine NP model compared with that of control mice (all p < 0.05), and severe polypoid lesions were apparently observed in murine NP models. Anti-IL-17A treatment downregulated the mRNA and protein expression of MMP-9 in nasal mucosa and reduced the number of polypoid lesions in the murine NP model (all p < 0.05).

CONCLUSION

Our results suggest that IL-17A plays a crucial role and may affect the prognosis of CRSwNP. Anti-IL-17A treatment may reduce the formation of polypoid lesions through inhibition of MMP-9 expression.

Nuclear Factor κB/MicroRNA-155 Upregulates the Expression Pattern of Cytokines in Regulating the Relapse of Chronic Sinusitis with Nasal Polyps and the Underlying Mechanism of Glucocorticoid

Background

The aim of this study was to explore the upregulated nuclear factor κB (NF-κB)/microRNA-155 (miR-155) in regulating inflammatory responses and relapse of chronic rhinosinusitis (CRS) with nasal polyps (NP), which underlies the molecular mechanism of glucocorticoid treatment.

Material/Methods

The study recruited 25 patients with eosinophilic (Eos) CRSwNP, 25 patients with Non-Eos CRSwNP, 25 patients with CRS without NP (CRSsNP) and 30 patients with nasal septum deviation (control group). The expression of NF-κB/miR-155 and inflammatory cytokines was detected in epithelial tissue specimens. Additionally, a mouse model of Eos CRSwNP was established, and the mice were treated by NF-κB inhibitor, miR-155 antagomir, or dexamethasone (DEX) to explore the role of NF-κB/miR-155 and the anti-inflammatory effects of glucocorticoid treatment.

Results

Results showed that the expression level of NF-κB/miR-155 was significantly elevated in the Eos CRSwNP group, accompanied by the upregulation of cytokines: tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-4, IL-5 (P<0.05) compared with the control group, the CRSsNP group or the Non-Eos CRSwNP group. The upregulation of NF-κB/miR-155 increased inflammatory mediator cyclooxygenase2 (COX2) while decreasing anti-inflammatory mediator Src homology-2 domain-containing inositol 5-phosphatase 1 (SOCS1), which resulted in the aberrant expression pattern of cytokines in the mice model. DEX treatment inhibited the expression of cytokines and decreased the relapse rate of Eos CRSwNP via inhibiting NF-κB/miR-155 (P<0.05).

Conclusions

The upregulation of NF-κB/miR-155 was crucial in mediating the aberrant expression of inflammatory cytokines in Eos CRSwNP. This molecular mechanism is a concern with the high relapse rate of Eos CRSwNP. However, glucocorticoid treatment inhibited the relapse of CRSwNP via downregulation of NF-κB/miR-155.

Development and immunopathological characteristics of an Alternaria-induced chronic rhinosinusitis mouse model

Airborne fungi are associated with upper and lower airway inflammatory diseases. Alternaria is commonly found in nasal secretions and induces the production of chemical mediators from sinonasal mucosa. This study aimed to establish an Alternaria-induced chronic rhinosinusitis (CRS) mouse model and determine the influence of host allergic background on the immunopathological characteristics of CRS. BALB/c mice were used for establishing the CRS model. Alternaria was intranasally instilled for 8 or 16 weeks with or without ovalbumin (OVA) presensitization. Total serum IgE and Alternaria-specific IgE levels were measured by enzyme-linked immunosorbent assay (ELISA). Interleukin (IL)-4, IL-10, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α levels in nasal lavage fluid (NLF) and splenocytes were measured by ELISA and their mRNAs and levels of associated transcription factors in sinonasal mucosa were determined with quantitative reverse-transcriptase polymerase chain reaction (RT-PCR). Hematoxylin-eosin staining and periodic acid-Schiff staining were performed to evaluate histological changes. Total serum IgE was increased in both allergic and non-allergic CRS. IL-4 was strongly expressed in NLF in both allergic and non-allergic CRS at 16 weeks and not only eosinophils but also neutrophils were increased in NLF of non-allergic CRS mice. The levels of Th1, Th2, and Treg cytokines and transcription factor mRNAs were significantly increased in sinonasal mucosa of non-allergic CRS mice. Both inflammatory cell infiltration and goblet cell hyperplasia were increased in CRS mice. Repeated intranasal instillation of Alternaria results in sinonasal inflammation with inflammatory cell infiltration. The sinonasal mucosal immune responses against Alternaria were shown to differ depending on the host allergic background.

Effects of Cigarette Smoke on the Nasal Respiratory and Olfactory Mucosa in Allergic Rhinitis Mice

Objective

Cigarette smoke (CS) exposure reportedly enhances allergic airway inflammation. However, some studies have shown an association between current cigarette smoke exposure and a low risk for allergic rhinitis. Thus, the impact of CS exposure on allergic rhinitis remains poorly understood. The purpose of this study was to investigate the effects of CS on the respiratory mucosa (RM) and the olfactory epithelium (OE) of mice with allergic rhinitis, as the effects may differ depending on the nasal histological compartments.

Methods

Eight-week-old male BALB/c mice were used for this study. We developed a mouse model of smoking by intranasally administering 10 doses of a CS solution (CSS), and a mouse model of allergic rhinitis by sensitization with intraperitoneal ovalbumin (OVA) injection and intranasal challenge with OVA. We examined the effects of CS on the nasal RM and OE in mice with or without allergic rhinitis using histological, serum, and genetic analyses. First, we examine whether CSS exposure induces allergic responses and then, examined allergic responses in the OVA-sensitized allergic rhinitis mice with or without CSS exposure.

Results

Short-term CSS administration intensified allergic responses including increased infiltration of eosinophils and inflammatory cells and upregulation of interleukin-5 expression in the nasal RM of OVA-immunized mice, although only CSS induced neither allergic responses nor impairment of the RM and OE. Notably, repetitive OVA-immunization partially impaired the OE in the upper-lateral area, but CSS administration did not reinforce this impairment in OVA-induced allergic mice.

Conclusion

Short-term CSS exposure strengthened allergic responses in the nasal RM and did not change the structure of the OE. These results suggest that patients with allergic rhinitis could experience exacerbation of allergic symptoms after CS exposure.

Superantigen-related TH2 CD4+ T cells in nonasthmatic chronic rhinosinusitis with nasal polyps

BACKGROUND

Staphylococcus aureus enterotoxin (SAE) superantigens are detected in nasal polyps (NPs), and SAE-specific IgE predicts asthma comorbidity in patients with NPs. However, roles of SAE superantigens and superantigen-related T-cell responses remain to be elucidated in nonasthmatic patients.

OBJECTIVE

We investigated the presence of SAEs and SAE-related T-cell receptor (TCR) Vβ (TCRVβ) in nonasthmatic NPs, the phenotypes and functions of SAE-related T cells, and the clinical implication of SAE-related T-cell expansion.

METHODS

Sinonasal tissue samples were obtained from patients with nonasthmatic chronic rhinosinusitis (CRS) with NPs (CRSwNP), patients with CRS without NPs (CRSsNP), and control subjects. SAE genes were detected by PCR, and the TCRVβ distribution and T-cell phenotypes were examined by flow cytometry.

RESULTS

Various SAE genes were detected not only in NPs but also in sinonasal mucosa from patients with CRSsNP and from controls. The S aureus enterotoxin I (SEI) gene was detected in all NPs. The fraction of SEI-responsive TCRVβ⁺ (TCRVβ1⁺ and Vβ5.1⁺) CD4⁺ T cells was significantly increased only in NPs and the ethmoidal mucosa of patients with CRSwNP, indicating superantigen-induced expansion. The expanded TCRVβ5.1⁺ CD4⁺ T cells expressed proliferation marker Ki-67 and the T_H2 transcription factor GATA3. Furthermore, TCRVβ5.1⁺ CD4⁺ T cells in NPs highly expressed T_H2 markers, including IL-17RB, thymic stromal lymphoprotein receptor, and chemoattractant receptor-homologous molecule expressed on T_H2 cells, with a potent T_H2 cytokine-producing ability. Moreover, the expansion of TCRVβ1⁺ or Vβ5.1⁺ CD4⁺ T cells was associated with the Lund-Mackay computed tomography score, indicating disease extent.

CONCLUSION

In nonasthmatic patients with CRSwNP, superantigen-related expansion of CD4⁺ T cells with T_H2 differentiation was associated with the disease extent.

Chloroquine Treatment Suppresses Mucosal Inflammation in a Mouse Model of Eosinophilic Chronic Rhinosinusitis

PURPOSE

The Toll-like receptor 9 (TLR9) signaling pathway is involved in the pathogenesis of chronic rhinosinusitis (CRS) with nasal polyposis. The aim of this study was to assess the therapeutic potential of the TLR9 pathway inhibitor chloroquine in CRS mice.

METHODS

The expression of type I interferons (IFNs) in human CRS tissues was evaluated using quantitative polymerase chain reaction (qPCR), western blotting, and immunofluorescence. Mice were divided into 4 treatment groups: the control, nasal polyp (NP), chloroquine treatment (NP + Chlq), and dexamethasone treatment (NP + Dexa) groups. The effects of chloroquine on polyp formation and mucosal inflammation were examined by hematoxylin and eosin staining. The expression levels of type I IFN, B-cell activating factor (BAFF), TLR9, high mobility group box 1 (HMGB1), and proinflammatory cytokine expression levels were assessed using qPCR, western blot, or enzyme-linked immunosorbent assay.

RESULTS

IFN-α and IFN-β mRNA levels were significantly higher in patients with eosinophilic NPs (EPs) than in healthy individuals or non-EP patients. The polyp score, epithelial thickness, mucosal thickness, and the number of eosinophils in nasal mucosa were significantly higher in the NP group compared with the control, NP + Chlq, and NP + Dexa groups. NP + Chlq or NP + Dexa significantly suppressed the induction of type I IFN and BAFF expression in the NP group; these treatments also significantly suppressed the induction of TLR9, HMGB1, interferon regulatory factors, interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and Th cytokine expression in the NP group. The secreted levels of anti-dsDNA Immunoglobulin G (IgG) were significantly higher in the NP group than in the control, NP + Chlq, and NP + Dexa groups. There were significant positive correlations between BAFF and mRNA levels of IFN-α/β/the protein levels of anti-dsDNA IgG.

CONCLUSIONS

Chloroquine may be used for the treatment of patients with eosinophilic CRS.

Evaluation of Neo-Osteogenesis in Eosinophilic Chronic Rhinosinusitis Using a Nasal Polyp Murine Model

Purpose

Osteitis refers to the development of new bone formation and remodeling of bone in chronic rhinosinusitis (CRS) patients; it is typically associated with eosinophilia, nasal polyps (NPs), and recalcitrant CRS. However, the roles of ossification in CRS with or without NPs remain unclear due to the lack of appropriate animal models. Thus, it is necessary to have a suitable animal model for greater advances in the understanding of CRS pathogenesis.

Methods

BALB/c mice were administered ovalbumin (OVA) and staphylococcal enterotoxin B (SEB). The numbers of osteoclasts and osteoblasts and bony changes were assessed. Micro computed tomography (micro-CT) scans were conducted to measure bone thickness. Immunofluorescence, immunohistochemistry, and quantitative polymerase chain reaction were performed to evaluate runt-related transcription factor 2 (RUNX2), osteonectin, interleukin (IL)-13, and RUNX2 downstream gene expression. Gene set enrichment analysis was performed in mucosal tissues from control and CRS patients. The effect of resveratrol was evaluated in terms of osteogenesis in a murine eosinophilic CRS NP model.

Results

The histopathologic changes showed markedly thickened bones with significant increase in osteoblast numbers in OVA/SEB-treated mice compared to the phosphate-buffered saline-treated mice. The structural changes in bone on micro-CT were consistent with the histopathological features. The expression of RUNX2 and IL-13 was increased by the administration of OVA/SEB and showed a positive correlation. RUNX2 expression mainly co-localized with osteoblasts. Bioinformatic analysis using human CRS transcriptome revealed that IL-13-induced bony changes via RUNX2. Treatment with resveratrol, a candidate drug against osteitis, diminished the expression of IL-13 and RUNX2, and the number of osteoblasts in OVA/SEB-treated mice.

Conclusions

In the present study, we found the histopathological and radiographic evidence of osteogenesis using a previously established murine eosinophilic CRS NP model. This animal model could provide new insights into the pathophysiology of neo-osteogenesis and provide a basis for developing new therapeutics.

Role of IL-17A in Chronic Rhinosinusitis With Nasal Polyp

Purpose

Th17-associated inflammation is increased in chronic rhinosinusitis with nasal polyp (CRSwNP), and is associated with disease severity and steroid resistance. Overexpressed interleukin (IL)-17A affects CRSwNP by tissue remodeling, eosinophilic accumulation, and neutrophilic infiltration. We aimed to identify the role of IL-17A in CRSwNP and to evaluate the effects of anti-IL-17A blocking antibody on nasal polyp (NP) formation using a murine NP model. Moreover, we sought to investigate whether the inhibition of mechanistic target of the rapamycin (mTOR) signal pathway could suppress IL-17A expression and NP formation.

Methods

Human sinonasal tissues from control subjects and patients with chronic rhinosinusitis (CRS) were analyzed using immunohistochemistry (IHC) and immunofluorescence staining. The effects of IL-17A neutralizing antibody and rapamycin were evaluated in a murine NP model. Mouse samples were analyzed using IHC, quantitative real-time polymerase chain reaction, and enzyme-linked immunosorbent assay.

Results

IL-17A⁺ inflammatory cells were significantly increased in number in NP from patients with CRSwNP compared to that in uncinate process tissues from control subjects and patients with CRS without NP or CRSwNP. CD68⁺ M1 macrophages dominantly expressed IL-17A, followed by neutrophils and T helper cells, in NP tissues. Neutralization of IL-17A effectively reduced the number of NPs, inflammatory cytokines, and IL-17A-producing cells, including M1 macrophages. Inhibition of IL-17A via the mTOR pathway using rapamycin also attenuated NP formation and inflammation in the murine NP model.

Conclusions

IL-17A possibly plays a role in the pathogenesis of CRSwNP, the major cellular source being M1 macrophage in NP tissues. Targeting IL-17A directly or indirectly may be an effective therapeutic strategy for CRSwNP.

α-Helical cell-penetrating peptide-mediated nasal delivery of resveratrol for inhibition of epithelial-to-mesenchymal transition

In the present study, we examined the potential of cell-penetrating peptide (CPP)-based intranasal drug delivery for the treatment of localized nasal diseases. Many charged or non-hydrophobic drugs have difficulty penetrating into the nasal epithelium due to intrinsic membrane impermeability and rapid mucociliary clearance in the nasal cavity. To treat chronic rhinosinusitis with nasal polyps (CRSwNP), one of the most common localized nasal diseases, we conjugated resveratrol (RSV) to an amphiphilic α-helical leucine (L)- and lysine (K)-rich CPP (LK) and intranasally delivered it to the interior of nasal epithelial cells for inhibiting epithelial-to-mesenchymal transition (EMT) caused by hypoxia-inducible factor 1α. The RSV-LK conjugate could penetrate into the nasal epithelium and efficiently inhibit EMT, nasal polyp formation, epithelial disruption, and related inflammation in an eosinophilic CRSwNP mouse model, at 10-fold lower doses and with 3-fold less frequent administration than free RSV. Due to the rapid penetration into the nasal epithelium and the therapeutic effect of the RSV-LK conjugate at much lower doses than free RSV, this CPP-based delivery system, with the ability to overcome the tight nasal epithelial barrier, may provide a new strategy for the treatment of localized nasal diseases without the systemic side effects of cargo drugs.

An Experimental Model of Eosinophilic Chronic Rhinosinusitis Induced by Bacterial Toxins in Rabbits

Background

The pathophysiology of chronic rhinosinusitis (CRS) is still not well known due to the multifactorial etiologies involved. Bacteria play a role in the pathogenesis of CRS by various means, including biofilm adhesion, intracellular persistence, or inducing inflammation secondary to toxins. Endotoxins and exotoxins, especially Staphylococcus aureus superantigens, can produce significant immune responses in the host and are implicated in patients with CRS. The majority of animal models described for CRS revalidates the pathophysiology of acute sinusitis, ostium occlusion, or foreign body associated infection.

Objectives

To evaluate an experimental model of eosinophilic CRS using prolonged exposure to bacterial toxins. The histological changes in rabbits exposed to S. aureus enterotoxin B (SEB), lipopolysaccharide (LPS), or lipoteichoic acid (LTA) were compared.

Methods

After induction with ovalbumin (OVA) sensitization with subcutaneous injection for 2 weeks, rabbits underwent surgery to insert an indwelling catheter into the maxillary sinus. The sinus was irrigated with OVA 3 times weekly for 2 weeks, followed by sinus irrigation with bacterial toxin (SEB: 1 µg/mL, LPS: 100 ng/mL, or LTA: 100 ng/mL) 3 times weekly for 4 weeks. The histological changes in the treated sinus were compared with control rabbits.

Results

Sinuses exposed to bacterial toxins (SEB, LPS, and LTA) produced significant mucosal thickening with infiltration of inflammatory cells, notably eosinophils. SEB was the only toxin that promoted a mixed pattern of inflammation, including eosinophilic and neutrophilic infiltration.

Conclusion

Our experimental model of eosinophilic CRS in rabbits produced significant mucosal thickening and inflammation in the sinuses exposed to bacterial toxins, with histological changes analogous to what is observed in patients with CRS with nasal polyps. This model may serve as a basis for future investigation of the pathogenesis of eosinophilic CRS in relation to bacterial toxins or as a model for testing new therapeutic modalities for this disease.

Staphylococcus aureus Orchestrates Type 2 Airway Diseases

Staphylococcus aureus persistently colonizes the nostrils of one-third of the population but colonizes the sinus mucosa in up to 90% of patients with nasal polyps, implying a possible role in airway disease. Recent findings give new mechanistic insights into the ability of S. aureus to trigger type 2 inflammatory responses in the upper and lower airways. This novel concept of a S. aureus-driven chronic airway inflammatory disease suggests a new understanding of disease triggers. This article reviews the role of S. aureus in chronic inflammatory airway diseases and discusses possible therapeutic approaches to target S. aureus.

The IFN-γ-p38, ERK kinase axis exacerbates neutrophilic chronic rhinosinusitis by inducing the epithelial-to-mesenchymal transition

Chronic rhinosinusitis (CRS) is a heterogeneous and multifactorial inflammatory disease characterized by involvement of diverse types of inflammatory cells. Asian CRS patients frequently show infiltration of neutrophils and an elevated level of interferon (IFN)-γ; by contrast, western patients exhibit eosinophil infiltration and enhanced levels of Th2-related cytokines. Neutrophilia in tissues decreases sensitivity to corticosteroids, but the mechanisms underlying the progression of neutrophilic CRS are unclear. In this study, we investigated the role of IFN-γ in CRS patients with marked neutrophil infiltration. We report that the IFN-γ level is upregulated in the tissues of these patients, particularly those with non-eosinophilic nasal polyps. The level of IFN-γ was significantly correlated with markers of the epithelial-to-mesenchymal transition (EMT). We further demonstrated that IFN-γ induced the EMT via the p38 and extracellular signal-regulated kinase (ERK) pathways in a manner distinct from the hypoxia-inducible factor (HIF)-1α, SMAD, and NF-κB signaling pathways. In a murine nasal polyp (NP) model, blocking the p38 and ERK signaling pathways prevented NP formation and chemotactic cytokine secretion by neutrophils but not eosinophils. Taken together, our results suggest that IFN-γ can induce the EMT in nasal epithelial cells, and thus blocking the p38 and ERK pathways could be an effective therapeutic strategy against neutrophil-dominant CRS.

Type 2/Th2-driven inflammation impairs olfactory sensory neurogenesis in mouse chronic rhinosinusitis model

BACKGROUND

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is a chronic inflammatory disease often accompanied by impairment of sense of smell. This symptom has been somewhat overlooked, and its relationship to inflammatory cytokines, tissue compression, neuronal loss, and neurogenesis is still unclear.

METHODS

In order to elucidate potential mechanisms leading to CRS in humans, we have established a type 2/T helper type 2 cell (Th2)-mediated allergic CRS mouse model, based on house dust mite (HDM) and Staphylococcus aureus enterotoxin B (SEB) sensitization. The inflammatory status of the olfactory epithelium (OE) was assessed using histology, biochemistry, and transcriptomics. The sense of smell was evaluated by studying olfactory behavior and recording electro-olfactograms (EOGs).

RESULTS

After 22 weeks, a typical type 2/Th2-mediated inflammatory profile was obtained, as demonstrated by increased interleukin (IL)-4, IL-5, and IL-13 in the OE. The number of mast cells and eosinophils was increased, and infiltration of these cells into the olfactory mucosa was also observed. In parallel, transcriptomic and histology analyses indicated a decreased number of immature olfactory neurons, possibly due to decreased renewal. However, the number of mature sensory neurons was not affected and neither the EOG nor olfactory behavior was impaired.

CONCLUSION

Our mouse model of CRS displayed an allergic response to HDM + SEB administration, including the type 2/Th2 inflammatory profile characteristic of human eosinophilic CRSwNP. Although the sense of smell did not appear to be altered in these conditions, the data reveal the influence of chronic inflammation on olfactory neurogenesis, suggesting that factors unique to humans may be involved in CRSwNP-associated anosmia.

Eosinophilic Upper Airway Inflammation in a Murine Model Using an Adoptive Transfer System Induces Hyposmia and Epithelial Layer Injury with Convex Lesions

Background: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a refractory upper airway disease, accompanied mainly by eosinophilia and/or asthma. In addition, the disease correlates with a high rate of hyposmia, following a marked infiltration of eosinophils into the inflamed site, the paranasal sinus. Although eosinophils are known to contribute to the development of hyposmia and CRSwNP pathology, the underlying mechanisms remain unclear. This study aimed to investigate whether eosinophilic upper airway inflammation induces hyposmia and CRSwNP in a murine model using an adoptive transfer system. Methods: To induce eosinophilic rhinosinusitis, splenocytes, including a high proportion (over 50%) of activated eosinophils (SPLhEos), were collected from interleukin-5 transgenic mice following double intraperitoneal injections of antigens, such as ovalbumin, house dust mite, or fungus. Activated SPLhEos with corresponding antigens were then transferred into the nasal cavity of recipient mice, which were sensitized and challenged by the corresponding antigen four times per week. Olfactory function, histopathological, and computed tomography (CT) analyses were performed 2 days after the final transfer of eosinophils. Results: Hyposmia was induced significantly in mice that received SPLhEos transfer compared with healthy and allergic mice, but it did not promote morphological alteration of the paranasal sinus. Pathological analysis revealed that epithelial layer injury and metaplasia similar to polyps, with prominent eosinophil infiltration, was induced in recipient tissue. However, there was no nasal polyp development with interstitial edema that was similar to those recognized in human chronic rhinosinusitis. Conclusions: This study supports the previously unsuspected contribution of eosinophils to CRS development in the murine model and suggests that murine-activated eosinophilic splenocytes contribute to the development of hyposmia due to more mucosal inflammation than physical airway obstruction and epithelial layer injury with convex lesions.

C3a receptor antagonism as a novel therapeutic target for chronic rhinosinusitis

Chronic rhinosinusitis with nasal polyps (CRSwNP) is an inflammatory disease with an unknown etiology. Recent studies have implicated the complement system as a potential modulator of disease immunopathology. We performed proteomic pathway enrichment analysis of differentially increased proteins, and found an enrichment of complement cascade pathways in the nasal mucus of individuals with CRSwNP as compared to control subjects. Sinonasal mucus levels of complement 3 (C3) correlated with worse subjective disease severity, whereas no significant difference in systemic C3 levels could be determined in plasma samples. Given that human sinonasal epithelial cells were the predominate sinonasal source of C3 and complement anaphylatoxin 3a (C3a) staining, we focused on their role in in vitro studies. Baseline intracellular C3 levels were higher in CRSwNP cells, and following exposure to Aspergillus fumigatus (Af) extract, they released significantly more C3 and C3a. Inhibition of complement 3a receptor (C3aR) signaling led to a decrease in Af-induced C3 and C3a release, both in vitro and in vivo. Finally, we found in vivo that C3aR deficiency or inhibition significantly reduced inflammation and CRS development in a mouse model of Af-induced CRS. These findings demonstrate that local sinonasal complement activation correlates with subjective disease severity, and that local C3aR antagonism significantly ameliorates Af-induced CRS in a rodent model.

Anti-inflammatory effect of bee venom in an allergic chronic rhinosinusitis mouse model

Bee venom (BV) has long been used as anti-inflammatory agent in traditional oriental medicine; however, the effect of BV on chronic rhinosinusitis (CRS) is not commonly studied. The aim of the present study was to determine the anti-inflammatory effect of BV on an allergic CRS mouse model. An allergic CRS mouse model was established following the administration of ovalbumin with Staphylococcus aureus enterotoxin B (SEB) into the nose. A total of 0.5 or 5 ng/ml of BV were intranasally applied 3 times a week for 8 weeks. Histopathological alterations were observed using hematoxylin and eosin, and Periodic acid Schiff staining. The levels of inflammatory cell infiltration, interleukin (IL)‑4, IL‑10 and interferon (INF)‑γ in nasal lavage fluid (NLF) were measured. Nuclear factor (NF)‑κB and activator protein (AP)‑1 expressions were also determined by immunohistochemical staining. The group treated with BV had significantly decreased inflammatory cell infiltration and PAS‑positive cells. The levels of INF‑γ, and neutrophil and eosinophil counts in NLF were significantly decreased, and the SEB‑induced NF‑κB and AP‑1 expressions in mouse nasal mucosa were significantly suppressed by 0.5 and 5 ng/ml BV. Thus, BV exerted significant anti‑inflammatory effects in an allergic CRS mouse model and may have potential value for the treatment of CRS.

Characterization of a novel, papain-inducible murine model of eosinophilic rhinosinusitis

BACKGROUND

Eosinophilic chronic rhinosinusitis (ECRS) is a disease characterized by eosinophilic inflammatory infiltrate and a local type 2 cytokine milieu. Current animal models fail to recapitulate many of the innate and adaptive immunologic hallmarks of the disease, thus hindering the development of effective therapeutics. In the present study, mice were exposed intranasally to the cysteine protease papain, which shares functional similarities with parasitic proteases and aeroallergens, to generate a rapidly inducible murine model of eosinophilic rhinosinusitis.

METHODS

C57BL/6 mice were intranasally instilled with 20 μg papain or heat-inactivated papain (HP) on days 0-2 and days 7-10, and then euthanized on day 11. Nasal lavage fluid (NALF) was analyzed to quantify eosinophils and inflammatory cytokine secretion. Sinonasal tissue was sectioned and stained for goblet cells or homogenized to analyze cytokine levels. Serum samples were assayed for immunoglobulin E (IgE) by enzyme-linked immunoassay. Sinonasal mucosal tissue was dissociated and analyzed by flow cytometry.

RESULTS

Compared with HP treatment, papain induced significant eosinophilia in NALF, goblet cell hyperplasia, innate and adaptive immune cell infiltration, type 2 cytokine production, and IgE responses. Flow cytometric analysis of sinonasal tissues revealed significant inflammatory cell infiltration and interleukin-13-producing cell populations.

CONCLUSION

In this study, we demonstrated that the cysteine protease papain induces allergic sinonasal eosinophilic rhinosinusitis and resembles T-helper 2 cell inflammation and innate immune characteristics of ECRS. This model permits further study into the molecular mechanisms underlying ECRS pathology and provides a model system for the evaluation of potential pharmacologic interventions.

The role of cysteinyl leukotrienes and their receptors in refractory nasal polyps

Leukotriene signaling is essential in many diseases, including asthma, allergic rhinitis, atherosclerosis and inflammatory bowel disease. Nevertheless, the expression of cysteinyl leukotrienes (CysLTs) and its receptors (CYSLTRs) in different types of nasal polyps (NPs), and the role of their antagonist in the treatment of refractory chronic rhinosinusitis with nasal polyps (CRSwNP) are not well understood. The following study investigates the expression of CysLTs and CYSLTRs in different types of NPs, as well as the role of leukotriene receptor antagonist (montelukast) in refractory NPs. Our data showed that CysLTs and CYSLTRs were significantly elevated in CRSwNP group (p < 0.05), particularly in IL-5⁺NP patients^, compared to patients with chronic rhinosinusitis but without NPs (CRSsNP) and the control group. Furthermore, montelukast have shown the ability to inhibit the expression of MUC5AC, TSLP, IL-4, IL-5, IL-13, and TGF-β in NP explants after treatment with Staphylococcal Enterotoxins B (SEB). In addition, the patients treated by additional montelukast have better outcomes compared to those with INCS only. To conclude, our results demonstrate that the inhibition of CysLTs signaling by montelukast decreases the expression of cytokines and mucin in polyp explants, and in turn promotes the recovery in patients with refractory CRSwNP.

Models for the study of nasal and sinus physiology in health and disease: A review of the literature

Objective

Chronic sinusitis is a very common yet poorly understood medical condition with significant morbidity. Hence, it remains an entity that is difficult to treat with unsatisfactory outcomes of current management options. This necessitates research into the etiology and pathophysiology of the condition to enhance our knowledge and the therapeutic options. Unfortunately, this kind of research is not always feasible on human subjects due to practical and ethical limitations. Therefore, an alternative model that simulates the disease had to be found in order to overcome these limitations. These models could either be in vivo or in vitro. The aim of our review is to summarize the research findings and key discoveries of both in vivo and in vitro models of chronic sinusitis that have enhanced our understanding of the condition today and have paved the way for the future research of tomorrow.

Data Sources: PubMed literature review.

Methods

A review of the literature was conducted to identify the main successful in vivo and in vitro models for chronic sinusitis.

Results

Creating a successful model for chronic sinusitis is no easy task. Over the years, both in vivo animal models and in vitro tissue culture models were proposed, with each model having its accolades and pitfalls, with the ideal model remaining elusive to this day. However, advancing three‐dimensional cell culturing techniques seems to be a promising new way to find a more accurate model.

Conclusion

None of the current models is perfect for a thorough study of chronic sinusitis. However, three‐dimensional cell cultures have the potential to bridge the gap between in vivo and in vitro studies.

Level of Evidence

NA

Establishment of a mouse model of lipopolysaccharide-induced neutrophilic nasal polyps

Research has identified that gram-negative bacteria have an important role in refractory nasal polyps. In the present study, lipopolysaccharide (LPS) was used to establish a mouse model with neutrophilic nasal polyps in order to explore the effect and mechanism of LPS on the formation of neutrophilic nasal polyps in mice. A total of 5 or 10 µg of LPS was dropped into the nasal cavities of C57BL/6J mice in order to establish animal models with neutrophilic nasal polyps. Histological staining, toll-like receptor 4 (TLR4), cluster of differentiation 68 for macrophages and myeloperoxidase for neutrophil immunohistochemistry were used to observe histopathological changes in the nasal mucosa. The expression levels of cytokines, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-4 and IL-17 in the nasal lavage fluid, were detected by ELISA. Compared with the control group, mice in the LPS groups exhibited significant mucosa epithelial cell damage and nasal polyp formation. Furthermore, TLR4⁺ cells, macrophages, neutrophils and significantly increased levels of IFN-γ, TNF-α, and IL-17 in the nasal lavage fluids were indicated (all P=0.008). These findings indicated that LPS is able to activate the TLR4 receptor pathway to induce the formation of neutrophilic nasal polyps in mice. Additionally, LPS administration was accompanied by a significant increase in the number of macrophages, T helper (Th) 1 and Th17-related cytokines (P=0.009, P=0.008 and P=0.008, respectively). Therefore, the present model is commensurate with the characteristics of primary nasal polyps that have been identified in the Asian population.

Classification of chronic rhinosinusitis according to a nasal polyp and tissue eosinophilia: limitation of current classification system for Asian population

Chronic rhinosinusitis (CRS) can be classified according to the presence of a nasal polyp (NP): CRS with NP (CRSwNP) and CRS without NP (CRSsNP). CRSwNP has characteristics with high infiltration of tissue eosinophilia with a burst of Th2 inflammatory cytokine. However recent findings in Eastern Asia countries suggest that CRSwNP can be divided according to the presence of tissue eosinophilia. Thus, CRSwNP can be classified into eosinophilic and noneosinophilic. Eosinophilic CRSwNP seems to have different immunological and clinical feature compared to noneosinophilic CRSwNP. From the same point of view, CRSsNP can also be divided according to tissue eosinophilia. However, the meaning of this dichotomous categorization in CRS seems to be not quite clear. This review focus on the limitations in current subclassification of CRS according to the presence of NP and tissue eosinophilia and discuss other factors related to tissue remodeling and NP generation which may provide clues for the further understanding of CRS pathogenesis.

Endogenous Protease Inhibitors in Airway Epithelial Cells Contribute to Eosinophilic Chronic Rhinosinusitis

RATIONALE

Cystatin A and SPINK5 are endogenous protease inhibitors (EPIs) that may play key roles in epithelial barrier function.

OBJECTIVES

To investigate the roles of EPIs in the pathogenesis of chronic rhinosinusitis (CRS).

METHODS

We examined the expression of cystatin A and SPINK5 in the nasal epithelial cells of patients with CRS. Additionally, the in vitro effects of recombinant EPIs on the secretion of the epithelial-derived cytokines IL-25, IL-33, and thymic stromal lymphopoietin in airway epithelial cells, and the in vivo effects of recombinant EPIs in the nasal epithelium of mice exposed to multiple airborne allergens (MAA) were examined.

MEASUREMENTS AND MAIN RESULTS

Compared with control subjects and patients with noneosinophilic CRS, patients with eosinophilic CRS showed significantly lower protein and mRNA expression of cystatin A and SPINK5 in the nasal epithelium. Allergen-induced production of IL-25, IL-33, and thymic stromal lymphopoietin in normal human bronchial epithelial cells was inhibited by treatment with recombinant cystatin A or SPINK5. Conversely, the production of these cytokines was increased when cystatin A or SPINK5 were knocked down with small interfering RNA. Chronic MAA exposure induced goblet cell metaplasia and epithelial disruption in mouse nasal epithelium and decreased the tissue expression and nasal lavage levels of cystatin A and SPINK5. Intranasal instillations of recombinant EPIs attenuated this MAA-induced pathology.

CONCLUSIONS

Cystatin A and SPINK5 play an important role in protecting the airway epithelium from exogenous proteases. The preservation of EPIs may have a therapeutic benefit in intractable airway inflammation, such as eosinophilic CRS.

The role of interleukin-33 in chronic rhinosinusitis

RATIONALE

Interleukin (IL)-33, a new member of the IL-1 family, is constitutively expressed in epithelial tissues and lymphoid organs and plays an important role in the pathogenesis of allergic disease. However, the role of IL-33 in chronic rhinosinusitis with nasal polyps (CRSwNP) remains unclear.

OBJECTIVE

To investigate the role of IL-33 in the pathophysiology of CRSwNP.

METHODS

We investigated IL-33 expression and its cellular origins in the nasal polyps (NPs) of human subjects by immunohistochemistry (IHC), quantitative reverse transcription PCR (qRT-PCR), and multiplex cytokine assays. Correlations between IL-33 expression and other inflammatory markers were also explored. To investigate the role of IL-33 in CRSwNP, anti-IL-33 antibody was used in a murine model of CRS.

RESULTS

Uncinate process tissues from control (19), CRSsNP (61), CRSwNP (69) and NP tissues (71) were used in this study. Increased expression of IL-33 mRNA and protein in patients with CRSwNP compared with controls was observed. The concentration of IL-33 protein in CRSwNP was positively correlated with the number of neutrophils and the expression of several Th1 and Th17 inflammatory markers, including interferon (IFN)-γ, IL-1β, tumour necrosis factor (TNF)-α, IL-17A, IL-22, and various markers for neutrophil recruitment. However, protein levels of IL-5 and quantity of eosinophils were inversely correlated with levels of IL-33. The expression of tissue inhibitor of metalloproteinase (TIMP)-1 was negatively correlated with IL-33 protein levels, while the expression of matrix metalloproteinase (MMP)-2 and MMP-9 was positively correlated with IL-33 protein levels. In animal studies, IL-33 expression was upregulated in the CRSwNP group compared with controls. Anti-IL-33 treatment reduced the thickness of oedematous mucosa, subepithelial collagen deposition, and infiltration of neutrophils, but infiltration of eosinophils was not reduced. This treatment also inhibited the expression of neutrophilic inflammatory cytokines, but not IL-4. In addition, the expression of intracellular adhesion molecule 1, vascular adhesion molecule 1 and CXCL-2 in the nasal mucosa was suppressed in mice treated with anti-IL-33 antibody.

CONCLUSIONS

Our data suggest a role for IL-33 in the pathogenesis of CRSwNP via neutrophil recruitment. Therefore, anti-IL-33 may provide a new treatment strategy to target infiltrating neutrophils in CRSwNP.