Role of imbalance of eicosanoid pathways and staphylococcal superantigens in chronic rhinosinusitis

A Decade of Pathogenesis Advances in Non-Type 2 Inflammatory Endotypes in Chronic Rhinosinusitis: 2012-2022

Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by localized inflammation of the upper airways. CRS includes two main phenotypes, namely, CRS with nasal polyps and CRS without nasal polyps. The phenotype-based classification method cannot reflect the pathological mechanism. The endotype-based classification method has been paid more and more attention by researchers. It is mainly divided into type 2 and non-type 2 endotypes. The mechanism driving the pathogenesis of non-type 2 inflammation is currently unknown. In this review, the PubMed and Web of Science databases were searched to conduct a critical analysis of representative literature works on the pathogenesis of non-type 2 inflammation in CRS published in the past decade. This review summarizes the latest evidence that may lead to the pathogenesis of non-type 2 inflammation. It is the main method that analyzing the pathogenesis from the perspective of immunology. Genomics and proteomics technique provide new approaches to the study of the pathogenesis. Due to differences in race, environment, geography, and living habits, there are differences in the occurrence of non-type 2 inflammation, which increase the difficulty of understanding the pathogenesis of non-type 2 inflammation in CRS. Studies have confirmed that non-type 2 endotype is more common in Asian patients. The emergence of overlap and unclassified endotypes has promoted the study of heterogeneity in CRS. In addition, as the source of inflammatory cells and the initiation site of the inflammatory response, microvessels and microlymphatic vessels in the nasal mucosal subepithelial tissue participate in the inflammatory response and tissue remodeling. It is uncertain whether CRS patients affect the risk of infection with SARS-CoV-2. In addition, the pathophysiological mechanism of non-type 2 CRS combined with COVID-19 remains to be further studied, and it is worth considering how to select the befitting biologics for CRS patients with non-type 2 inflammation.

The Unified Airway Hypothesis: Evidence From Specific Intervention With Anti-IL-5 Biologic Therapy

The unified airway hypothesis proposes that upper and lower airway diseases reflect a single pathological process manifesting in different locations within the airway. Functional, epidemiological, and pathological evidence has supported this well-established hypothesis for some time. However, literature on the pathobiologic roles/therapeutic targeting of eosinophils and IL-5 in upper and lower airway diseases (including asthma, chronic rhinosinusitis with nasal polyps [CRSwNP], and nonsteroidal anti-inflammatory drug-exacerbated respiratory disease) has recently emerged. This narrative review revisits the unified airway hypothesis by searching the scientific literature for recent learnings and clinical trial/real-world data that provide a novel perspective on its relevance for clinicians. According to the available literature, eosinophils and IL-5 have important pathophysiological roles in both the upper and lower airways, although the impact of eosinophils and IL-5 may vary in asthma and CRSwNP. Some differential effects of anti-IL-5 and anti-IL-5-receptor therapies in CRSwNP have been observed, requiring further investigation. However, pharmaceutical targeting of eosinophils and IL-5 in patients with upper, lower, and comorbid upper and lower airway inflammation has led to clinical benefit, supporting the hypothesis that these are linked conditions manifesting in different locations. Consideration of this approach may improve patient care and aid clinical decision making.

Pathogenesis of Nasal Polyposis: Current Trends

Chronic Rhinosinusitis (CRS) is characterized by edema of the sub-epithelial layers, but, only specific types of CRS are developing polyps. Nasal polyposis may develop under different pathogenetic mechanisms rendering the typical macroscopic classification of CRS, with or without nasal polyps, rather deficient. Currently, we approach nasal polyposis, in terms of diagnosis and treatment, according to its endotype, which means that we focus on the specific cells and cytokines that are participating in its pathogenesis. It appears that the molecular procedures that contribute to polyp formation, initiating with a Th-2 response of the adaptive immune system, are local phenomena occurring in the sub-epithelial layers of the mucosa. Several hypotheses are trying to approach the etiology that drives the immune response towards Th-2 type. Extrinsic factors, like fungi, Staphylococcus superantigens, biofilms, and altered microbiome can contribute to a modified and intense local reaction of the immune system. Some hypotheses based on intrinsic factors like the elimination of Treg lymphocytes, low local vitamin-D levels, high levels of leukotrienes, epithelial to mesenchymal transition (EMT) induced by hypoxia, and altered levels of NO, add pieces to the puzzle of the pathogenesis of nasal polyposis. Currently, the most complete theory is that of epithelial immune barrier dysfunction. Intrinsic and extrinsic conditions can damage the epithelial barrier rendering sub-epithelial layers more vulnerable to invasion by pathogens that trigger a Th-2 response of the adaptive immune system. Th2 cytokines, subsequently, induce the accumulation of eosinophils and IgE together with the remodeling of the stroma in the sub-epithelial layers leading, eventually, to the formation of nasal polyps.

Determination of orally administered 1,8-Cineol in nasal polyp tissues from chronic rhinosinusitis patients using gas chromatography: mass spectrometry

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common inflammatory disease causing considerable disease burden. The anti-inflammatory monoterpene 1,8-Cineol is a natural plant-based therapeutic agent that is well established to treat chronic and acute airway diseases. Aim of this study was to investigate whether the herbal drug 1,8-Cineol reaches the nasal tissue via the gut and the blood stream upon its oral administration. A highly sensitive gas chromatography mass spectrometry-based method with stir bar sorptive extraction (SBSE) for sample preparation has been developed and validated for the extraction, detection and quantification of 1,8-Cineol in tissue samples of nasal polyps from 30 CRSwNP patients. Data revealed a highly sensitive detection of 1,8-Cineol in nasal tissue samples after 14 days of oral administration of 1,8-Cineol prior to surgical treatment. There was no significant correlation between the measured 1,8-Cineol concentrations and bodyweight or BMI values of the analyzed patients, respectively. Our data indicate a systemic distribution of 1,8-Cineol in the human body after its oral administration. Individual differences in terms of metabolic characteristics and have to be further investigated. The study increases our understanding of the systemic effects of 1,8-Cineol upon its therapeutic application and benefit in patients with CRSwNP.

MicroRNA-21-5p promotes mucosal type 2 inflammation via regulating GLP1R/IL-33 signaling in chronic rhinosinusitis with nasal polyps

BACKGROUND

It has been known that chronic rhinosinusitis with nasal polyps (CRSwNP) is a type 2 inflammation-dominated disease; however, the reasons causing such type of mucosal inflammation in CRSwNP are not well elucidated.

OBJECTIVE

We sought to investigate the role of microRNA-21-5p (miR-21-5p) in regulating mucosal type 2 inflammation in CRSwNP.

METHODS

miR-21-5p expression was detected in nasal mucosa of patients with CRSwNP. Correlations between miR-21-5p and indicators of type 2 inflammation were further analyzed. miR-21 knockout mice were used to explore the role of miR-21-5p in a murine model of eosinophilic (E) CRSwNP. Target gene of miR-21-5p related to type 2 inflammation in CRSwNP was identified.

RESULTS

The upregulated miR-21-5p in the nasal mucosa of patients with CRSwNP, compared with control subjects, was expressed higher in patients with ECRSwNP than in patients with nonECRSwNP. miR-21-5p expression was positively correlated with mucosal eosinophil infiltrations and the expression of type 2 inflammatory cytokines. In the CRSwNP mice, miR-21 knockout significantly attenuated type 2 inflammation, as indicated by eosinophil infiltrations and expression of cytokines/chemokines in nasal mucosa and lavage fluid; moreover, genes associated with type 2 inflammation were extensively downregulated at the transcriptome level in miR-21 knockout mice. Glucagon-like peptide-1 receptor, which was negatively correlated with miR-21-5p expression in human nasal mucosa, was identified as the target of miR-21-5p. Overexpression of miR-21-5p induced IL-33 expression, whereas glucagon-like peptide-1 receptor agonist decreased IL-33 production in airway epithelial cells.

CONCLUSIONS

miR-21-5p aggravates type 2 inflammation in the nasal mucosa of patients with CRSwNP via targeting glucagon-like peptide-1 receptor/IL-33 signaling, which may be a potential therapeutic target for CRSwNP.

The roles of eosinophils and interleukin-5 in the pathophysiology of chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is generally associated with eosinophilic tissue infiltration linked to type 2 inflammation and characterized by elevated levels of interleukin (IL)-5 and other type 2 inflammatory mediators. Although distinct and overlapping contributions of eosinophils and IL-5 to CRSwNP pathology are still being explored, they are both known to play an important role in NP inflammation. Eosinophils secrete numerous type 2 inflammatory mediators including granule proteins, enzymes, cytokines, chemokines, growth factors, lipids, and oxidative products. IL-5 is critical for the differentiation, migration, activation, and survival of eosinophils but is also implicated in the biological functions of mast cells, basophils, innate lymphoid cells, B cells, and epithelial cells. Results from clinical trials of therapeutics that target type 2 inflammatory mediators (including but not limited to anti-IL-5, anti-immunoglobulin-E, and anti-IL-4/13) may provide further evidence of how eosinophils and IL-5 contribute to CRSwNP. Finally, the association between eosinophilia/elevated IL-5 and greater rates of NP recurrence after endoscopic sinus surgery (ESS) suggests that these mediators may have utility as biomarkers of NP recurrence in diagnosing and assessing the severity of CRSwNP. This review provides an overview of eosinophil and IL-5 biology and explores the literature regarding the role of these mediators in CRSwNP pathogenesis and NP recurrence following ESS. Based on current published evidence, we suggest that although eosinophils play a key role in CRSwNP pathophysiology, IL-5, a cytokine that activates these cells, also represents a pertinent and effective treatment target in patients with CRSwNP.

Trained immunity in type 2 immune responses

Immunological memory of innate immune cells, also termed "trained immunity", allows for cross-protection against distinct pathogens, but may also drive chronic inflammation. Recent studies have shown that memory responses associated with type 2 immunity do not solely rely on adaptive immune cells, such as T- and B cells, but also involve the innate immune system and epithelial cells. Memory responses have been described for monocytes, macrophages and airway epithelial cells of asthmatic patients as well as for macrophages and group 2 innate lymphoid cells (ILC2) from allergen-sensitized or helminth-infected mice. The metabolic and epigenetic mechanisms that mediate allergen- or helminth-induced reprogramming of innate immune cells are only beginning to be uncovered. Trained immunity has been implicated in helminth-driven immune regulation and allergen-specific immunotherapy, suggesting its exploitation in future therapies. Here, we discuss recent advances and key remaining questions regarding the mechanisms and functions of trained type 2 immunity in infection and inflammation.

Alteration of blood monocyte subsets in chronic rhinosinusitis with regard to anti-inflammatory 1,8-Cineol treatment

Background: Chronic rhinosinusitis (CRS) affects about 10% of the european population causing considerable disease burden. The inflammatory microenvironment is mainly Th2 driven, but the impact of monocytes is still poorly understood. Aim of this study was to comprehensively investigate the composition of circulating monocytes and T cells in CRSwNP and CRSsNP patients, particularly with regard to the therapeutic herbal monoterpene 1,8-Cineol. Methodology: We analyzed the distribution of CD14 and CD16 classified monocyte subsets and the T-cell subset composition with respect to their PD-1 and PD-L1 expression in the peripheral blood of CRS patients using flow cytometry. Additionally, the M1/M2 like macrophage infiltration in nasal tissue and polyps was examined by immunofluorescence staining. Results: Data revealed a decrease of classical monocytes accompanied by a significant increase of intermediate CD16+ monocytes in CRSwNP and CRSsNP patients compared to healthy donors. PD-L1 expression on overall monocytes was also significantly increased in CRSwNP and CRSsNP patients. CRS patients with a severe drop of the proportion of classical monocytes showed a significant restoration of this subset in response to two-week 1,8-Cineol treatment. Conclusions: Our data indicate a CRS-induced shift of peripheral monocyte subsets to more inflammatory phenotypes that might be reversed by the herbal drug 1,8-Cineol.

Staphylococcus aureus Toxins: An Update on Their Pathogenic Properties and Potential Treatments

Staphylococcus aureus is a clinically important pathogen that causes a wide range of human infections, from minor skin infections to severe tissue infection and sepsis. S. aureus has a high level of antibiotic resistance and is a common cause of infections in hospitals and the community. The rising prevalence of community-acquired methicillin-resistant S. aureus (CA-MRSA), combined with the important severity of S. aureus infections in general, has resulted in the frequent use of anti-staphylococcal antibiotics, leading to increasing resistance rates. Antibiotic-resistant S. aureus continues to be a major health concern, necessitating the development of novel therapeutic strategies. S. aureus uses a wide range of virulence factors, such as toxins, to develop an infection in the host. Recently, anti-virulence treatments that directly or indirectly neutralize S. aureus toxins have showed promise. In this review, we provide an update on toxin pathogenic characteristics, as well as anti-toxin therapeutical strategies.

Staphylococcus aureus-Derived α-Hemolysin Evokes Generation of Specialized Pro-resolving Mediators Promoting Inflammation Resolution

Underlying mechanisms of how infectious inflammation is resolved by the host are incompletely understood. One hallmark of inflammation resolution is the activation of specialized pro-resolving mediators (SPMs) that enhance bacterial clearance and promote tissue repair. Here, we reveal α-hemolysin (Hla) from Staphylococcus aureus as a potent elicitor of SPM biosynthesis in human M2-like macrophages and in the mouse peritoneum through selective activation of host 15-lipoxygenase-1 (15-LOX-1). S. aureus-induced SPM formation in M2 is abolished upon Hla depletion or 15-LOX-1 knockdown. Isolated Hla elicits SPM formation in M2 that is reverted by inhibition of the Hla receptor ADAM10. Lipid mediators derived from Hla-treated M2 accelerate planarian tissue regeneration. Hla but not zymosan provokes substantial SPM formation in the mouse peritoneum, devoid of leukocyte infiltration and pro-inflammatory cytokine secretion. Besides harming the host, Hla may also exert beneficial functions by stimulating SPM production to promote the resolution of infectious inflammation.

Jordan et al. reveal that α-hemolysin from Staphylococcus aureus stimulates specialized pro-resolving mediator (SPM) formation through activation of 15-lipoxygenase-1 in human macrophages involving ADAM10. The host may exploit α-hemolysin as an SPM inducer to better cope with S. aureus infections and to promote inflammation resolution and tissue regeneration.

Biology and Function of Eosinophils in Chronic Rhinosinusitis With or Without Nasal Polyps

Chronic rhinosinusitis (CRS) with or without nasal polyposis is a complex medical condition characterized by varying patterns of chronic innate and adaptive mucosal inflammation. Treatment of CRS has been traditionally limited to corticosteroids and sinus surgery; however, novel biologics have more recently been evaluated as steroid- and surgery-sparing options. While it is clear that there are different subtypes or endotypes of CRS, perhaps the most frequent presentation involves the features of type 2 inflammation, including a prominent tissue eosinophilia component. The purpose of this review is to provide an update on eosinophil biology as well as on the potential contribution of eosinophils and their mediators to the pathophysiology of CRS, drawing mechanistic conclusions mainly from studies of human sinus mucosal tissues, nasal secretions, and benefits (or lack thereof) from the use of various pharmacotherapies. The unavoidable conclusion derived from this approach is that eosinophils themselves cannot fully explain the underlying pathophysiology of this complex disorder.

Linking Complement C3 and B Cells in Nasal Polyposis

Nasal polyposis often is characterized by a persistent inflammation of the sinonasal mucosa, disease recurrence after medical or surgical intervention, and asthma comorbidity. Dysregulated complement activation may contribute to immunologic alterations and disease. To date, there is only scattered knowledge on the source and regulation of the central complement factors in the pathogenesis of nasal polyps. Here, we aim to study complement signatures, especially the C3-C3aR axis, and focus on cellular sources and targets in nasal polyps. Expression of complement factors, including C3, C5, and the anaphylatoxin receptors, was analyzed in nasal polyp tissue samples, the corresponding inferior turbinates, and healthy controls using transcriptomic methods and protein measurements. Distinct patterns of complement expression were found in nasal polyps compared to controls, characterized by an increased C3 activation and an increase in C3aR-bearing cells. In contrast, no difference was shown for epithelial-dependent C3 production. Besides low intracellular C3-expression levels for lymphocytes in general, we could identify an enlarged B lymphocyte population in nasal polyps displaying high amounts of intracellular C3. Our data suggest a prominent role for the C3-C3aR-axis in nasal polyps and, for the first time, describe a B cell population containing high levels of intracellular C3, suggesting a new role of B cells in the maintenance of the inflammation by complement.

Distinct type 2-high inflammation associated molecular signatures of chronic rhinosinusitis with nasal polyps with comorbid asthma

Background

Patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and comorbid asthma have more severe disease and are difficult to treat. However, the molecular endotypes associated with CRSwNP with comorbid asthma (CRSwNP + AS) are not clear. This study aimed to investigate the characteristics of type 2 inflammation and the molecular signatures associated with CRSwNP + AS.

Methods

A total of 195 subjects; including 65 CRSwNP + AS patients, 99 CRSwNP-alone patients, and 31 healthy control subjects; were enrolled in the study. Nasal tissues from patients with CRSwNP + AS, CRSwNP-alone and control subjects were assessed for infiltration of inflammatory cells and concentrations of total IgE. Whole-transcriptome sequencing was performed and differentially expressed (DE) mRNAs and long non-coding RNAs (lncRNAs) and their associated pathways were analyzed. The correlations between type 2 cytokines and local eosinophils, tissue IgE, and transcriptome signatures were evaluated.

Results

Significantly higher local eosinophil infiltration and higher levels of total IgE were found in nasal tissues from CRSwNP + AS patients than in nasal tissues from CRSwNP-alone patients. Furthermore, atopy and recurrence were significantly more frequent in patients with CRSwNP + AS than in patients with CRSwNP-alone (62.5% vs 28.6% and 66.7% vs 26.9%, respectively). RNA sequencing analysis identified 1988 common DE-mRNAs, and 176 common DE-lncRNAs shared by CRSwNP + AS versus control and CRSwNP-alone versus control. Weighted gene coexpression network analysis (WGCNA) identified LINC01146 as hub lncRNA dysregulated in both subtypes of CRSwNP. Overall, 968 DE-mRNAs and 312 DE-lncRNAs were identified between CRSwNP + AS and CRSwNP-alone. Both pathway enrichment analysis and WGCNA indicated that the phenotypic traits of CRSwNP + AS were mainly associated with higher activities of arachidonic acid metabolism, type 2 cytokines related pathway and fibrinolysis pathway, and lower activity of IL-17 signalling pathway. Furthermore, the expression of type 2 cytokines; IL5 and IL13, was positively correlated with local eosinophil infiltration, tissue IgE level, and the expression of DE-mRNAs that related to arachidonic acid metabolism. Moreover, WGCNA identified HK3-006 as hub lncRNA in yellow module that most positively correlated with phenotypic traits of CRSwNP + AS.

Conclusions

Patients with CRSwNP + AS have distinct type 2-high inflammation-associated molecular signatures in nasal tissues compared to patients with CRSwNP-alone.

Montelukast Has no Impact on the Systemic Production of TGFβ-1 in Patients with Nasal Polyposis Associated with Aspirin Intolerance

Introduction  Nasal polyposis is a disease characterized by a mechanical dysfunction of the nasal mucosa, closely related to the unique makeup of its extracellular matrix, which develops as the result of an anomalous tissue remodeling process.

Transforming growth factor beta 1 (TGF-β1) is reduced not only in the nasal polypoid tissue, but also in the plasma of aspirin-intolerant patients. These patients exhibit an imbalance in the production of eicosanoids characterized by an increase in leukotrienes. Thus, it is important that the relationship between the production of leukotrienes and TGF-β1 be assessed.

Objective  To evaluate the effects of the cysteinyl leukotriene (CysLT) receptor antagonist montelukast on the systemic production of TGF-β1 in patients with nasal polyposis, with or without concomitant aspirin intolerance.

Methods  The sample comprised 48 individuals with diagnosis of nasal polyposis and 15 healthy controls for comparison of the baseline TGF-β1 levels in the peripheral blood and after treatment with CysLT receptor antagonist montelukast in the nasal-polyposis group.

Results  There was no difference in the change in TGF-β1 levels after the treatment with montelukast in the subgroup of patients with polyposis and asthma ( p  = 0.82) and in the subgroup with polyposis, asthma, and aspirin intolerance ( p  = 0.51).

Conclusion  we found no impact of the therapy with a leukotriene receptor blocker on the production of TGF-β1, making the antileukotriene therapy a highly questionable choice for the treatment of nasal polyposis, particularly from the standpoint of seeking to modify the remodeling process in this disease.

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.

Alterations in cellular force parameters and cell projections in Nasal polyps-derived fibroblasts

OBJECTIVE

Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) is a disease that features a mechanical dysfunction involving chronic inflammation and altered tissue remodeling. In this study, we aim to evaluate the fibroblast morphology and its cellular traction force in primary fibroblasts cell cultures obtained from both healthy individuals (n=7) and patients with CRSwNP (n=8).

METHODS

Using a Traction-force Microscopy we analyzed parameters of Force/Tension in fibroblasts cultures in both experimental groups.

RESULTS

The analysis of the Projected Area of Cell revealed that fibroblasts derived from nasal mucosa of healthy individuals have an area on average 39.24% larger than the fibroblasts obtained from the nasal polyp tissue. We also observed that the parameters directly related to the force of the cell, Max Cumulative Force and Net Contractile Moment, presented a high Force/Tension per unit of area in the fibroblasts derived from the healthy nasal mucosa (on average 41% and 52.54% higher than the fibroblasts of the nasal polyp respectively).

CONCLUSION

Our results demonstrate a cellular mechanism that may be associated with the mechanical dysfunction found in the Nasal Polyp tissue. The weak traction force of nasal polyp-derived fibroblast may, in lower dimensions, impact on the remodeling of nasal mucosa in CRSwNP.

Nasal Polyposis: More than a Chronic Inflammatory Disorder-A Disease of Mechanical Dysfunction-The São Paulo Position

Introduction  The importance of our study lies in the fact that we have demonstrated the occurrence of mechanical dysfunction within polypoid tissues, which promotes the development of polyps in the nasal cavity. Objective  To change the paradigm of nasal polyposis (NP). In this new conception, the chronic nasal inflammatory process that occurs in response to allergies, to pollution, to changes in the epithelial barrier, or to other factors is merely the trigger of the development of the disease in individuals with a genetic predisposition to an abnormal tissue remodeling process, which leads to a derangement of the mechanical properties of the nasal mucosa and, consequently, allows it to grow unchecked. Data Synthesis  We propose a fundamentally new approach to intervening in the pathological process of NP, addressing biomechanical properties, fluid dynamics, and the concept of surface tension. Conclusion  The incorporation of biomechanical knowledge into our understanding of NP provides a new perspective to help elucidate the physiology and the pathology of nasal polyps, and new avenues for the treatment and cure of NP.

Host Lipid Mediators in Leprosy: The Hypothesized Contributions to Pathogenesis

The spectrum of clinical forms observed in leprosy and its pathogenesis are dictated by the host's immune response against Mycobacterium leprae, the etiological agent of leprosy. Previous results, based on metabolomics studies, demonstrated a strong relationship between clinical manifestations of leprosy and alterations in the metabolism of ω3 and ω6 polyunsaturated fatty acids (PUFAs), and the diverse set of lipid mediators derived from PUFAs. PUFA-derived lipid mediators provide multiple functions during acute inflammation, and some lipid mediators are able to induce both pro- and anti-inflammatory responses as determined by the cell surface receptors being expressed, as well as the cell type expressing the receptors. However, little is known about how these compounds influence cellular immune activities during chronic granulomatous infectious diseases, such as leprosy. Current evidence suggests that specialized pro-resolving lipid mediators (SPMs) are involved in the down-modulation of the innate and adaptive immune response against M. leprae and that alteration in the homeostasis of pro-inflammatory lipid mediators versus SPMs is associated with dramatic shifts in the pathogenesis of leprosy. In this review, we discuss the possible consequences and present new hypotheses for the involvement of ω3 and ω6 PUFA metabolism in the pathogenesis of leprosy. A specific emphasis is placed on developing models of lipid mediator interactions with the innate and adaptive immune responses and the influence of these interactions on the outcome of leprosy.

Biological characteristics of staphylococcal enterotoxin Q and its potential risk for food poisoning

AIMS

To elucidate the biological characteristics and stability of a newly identified staphylococcal enterotoxin Q (SEQ) against heating and digestive enzymes and to evaluate the risk of seq-harbouring Staphylococcus aureus in food poisoning.

METHODS AND RESULTS

Purified SEQ was treated with heating, pepsin and trypsin which are related to food cooking, stomach and intestine conditions, respectively. Superantigenic activity of SEQ was assessed by determining the ability of IL-2 induction in mouse spleen cells. The emetic activity of SEQ was assessed using house musk shrew, a small emetic animal model. The results revealed that SEQ exhibits a remarkable resistance to heat treatment and pepsin digestion and has significant superantigenic and emetic activities. Furthermore, a sandwich ELISA for detection of SEQ production was developed, and the results showed that seq-harboring S. aureus isolates produce a large amount of SEQ.

CONCLUSIONS

The newly identified SEQ had remarkable stability to heat treatment and digestive enzyme degradation and exhibited significant superantigenic and emetic activities. In addition, seq-harbouring S. aureus isolated from food poisoning outbreaks produced a large amount of SEQ, suggesting that seq-harbouring S. aureus could potentially be a hazard for food safety.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study found, for the first time, that SEQ, a nonclassical SE, had remarkable stability to heat treatment and enzyme degradation and exhibited significant emetic activity, indicating that SEQ is a high-risk toxin in food poisoning.

Role of local allergic inflammation and Staphylococcus aureus enterotoxins in Chinese patients with chronic rhinosinusitis with nasal polyps

Objective:

To investigate the role of local allergic inflammation and Staphylococcus aureus enterotoxins in chronic rhinosinusitis with nasal polyps.

Methods:

This study included 36 patients with chronic rhinosinusitis with nasal polyps and 18 controls. Total immunoglobulin E, eosinophil cationic protein, staphylococcal enterotoxin types A and B specific immunoglobulin E, staphylococcal enterotoxin types A and B, and myeloperoxidase levels were determined.

Results:

Four patients with chronic rhinosinusitis with nasal polyps had a local allergy. All chronic rhinosinusitis with nasal polyps patients tested negative for staphylococcal enterotoxin types A and B specific immunoglobulin E. The chronic rhinosinusitis with nasal polyps group had significantly elevated staphylococcal enterotoxin types A and B levels in the supernatant. Fourteen patients belonged to the eosinophilic chronic rhinosinusitis with nasal polyps group and the others were characterised as having non-eosinophilic chronic rhinosinusitis with nasal polyps.

Conclusion:

Local allergy may play a role in chronic rhinosinusitis with nasal polyps, independent of staphylococcal enterotoxin superantigens. Staphylococcal enterotoxins may be important in the pathogenesis of chronic rhinosinusitis with nasal polyps; however, their roles as superantigens were not confirmed in this study. In Chinese subjects, chronic rhinosinusitis with nasal polyps usually manifests as a neutrophilic inflammation.

Bacterial Pathogens and the Microbiome

Bacterial pathogens and microbiome alterations can contribute to the initiation and propagation of mucosal inflammation in chronic rhinosinusitis (CRS). In this article, the authors review the clinical and research implications of key pathogens, discuss the role of the microbiome, and connect bacteria to mechanisms of mucosal immunity relevant in CRS.

Refractory Chronic Rhinosinusitis with Nasal Polyposis

Chronic rhinosinusitis with nasal polyposis (CRSwNP) represents a subset of chronic sinusitis with various causes. Some forms of the disease are driven by allergy, often in association with asthma. Refractory CRSwNP can be associated with cystic fibrosis and other clinical syndromes. More recent literature is presented regarding roles of innate immunity and superantigens. Effective treatment of CRSwNP requires careful endoscopic sinus surgery followed by an individualized treatment plan that often includes oral and topical steroids. Recidivism of polyps is common, and patients require long-term follow-up.

Nasal Polyp-Derived Mesenchymal Stromal Cells Exhibit Lack of Immune-Associated Molecules and High Levels of Stem/Progenitor Cells Markers

Mesenchymal stromal cells (MSCs) are considered adult progenitor stem cells and have been studied in a multitude of tissues. In this context, the microenvironment of nasal polyp tissue has several inflammatory cells, but their stroma compartment remains little elucidated. Hence, we isolated MSCs from nasal polyps Polyp-MSCs (PO-MSCs) and compared their molecular features and gene expression pattern with bone marrow-derived MSCs (BM-MSCs). Initially, both PO-MSCs and BM-MSCs were isolated, cultivated, and submitted to morphologic, differentiation, phenotypic, immunosuppressive, and gene expression assays. Compared to BM-MSCs, PO-MSCs showed normal morphology and similar osteogenic/adipogenic differentiation potential, but their immunophenotyping showed lack of immune-associated molecules (e.g., CD117, HLA-DR, PDL-1, and PDL-2), which was linked with less immunoregulatory abilities such as (i) inhibition of lymphocytes proliferation and (ii) regulatory T cell expansion. Furthermore, we detected in the PO-MSCs a distinct gene expression profile in comparison with BM-MSCs. PO-MSC expressed higher levels of progenitor stem cells specific markers (e.g., CD133 and ABCB1), while BM-MSCs showed elevated expression of cytokines and growth factors (e.g., FGF10, KDR, and GDF6). The gene ontology analysis showed that the differentially modulated genes in PO-MSC were related with matrix remodeling process and hexose and glucose transport. For BM-MSCs, the highly expressed genes were associated with behavior, angiogenesis, blood vessel morphogenesis, cell–cell signaling, and regulation of response to external stimulus. Thus, these results suggest that PO-MSCs, while sharing similar aspects with BM-MSCs, express a different profile of molecules, which presumably can be implicated in the development of nasal polyp tissue.

Staphylococcus aureus enterotoxin sensitization involvement and its association with the CysLTR1 variant in different asthma phenotypes

BACKGROUND

Sensitization to Staphylococcus aureus enterotoxin (SE) is a known risk factor for asthma susceptibility and severity. However, how SE sensitization is involved in asthma, particularly nonatopic asthma and/or late-onset asthma, remains uncertain.

OBJECTIVE

To clarify the involvement of SE sensitization in nonatopic and/or late-onset asthma and its association with a polymorphism of the cysteinyl leukotriene receptor 1 gene (CysLTR1), which was examined because CysLT signaling is closely associated with late-onset eosinophilic asthma.

METHODS

We assessed associations between sensitization to SE (A and/or B) and clinical indexes in 224 patients with asthma (mean age, 62.3 years; 171 women) from a cohort of the Kinki Hokuriku Airway Disease Conference, particularly those with nonatopic asthma (not sensitized to common aeroallergens) and/or late-onset asthma. Associations between SE sensitization and CysLTR1 polymorphism (rs2806489), a potential regulatory variant for atopic predisposition in women, were also assessed in a sex-stratified manner.

RESULTS

A total of 105 patients (47%) with asthma were sensitized to SE. Among patients with nonatopic asthma (n = 67) or with late-onset asthma (n = 124), those sensitized to SE had significantly higher serum total IgE and periostin levels than those not sensitized. In nonatopic patients, a rapid decrease in forced expiratory volume in 1 second was associated with SE sensitization. In women with asthma, rs2806489 was associated with sensitization to SEB and age at asthma onset.

CONCLUSION

SE sensitization contributes to T_H2 inflammation in nonatopic and/or late-onset asthma. In women with asthma, the CysLTR1 variant might be associated with sensitization to SEB and age at asthma onset.

DNA methylation, bacteria and airway inflammation: latest insights

PURPOSE OF REVIEW

DNA methylation is an epigenetic mechanism that has been implicated in the pathogenesis of chronic inflammatory diseases by regulating differentiation, proliferation, apoptosis, and activation of immune cells. Changes in the methylation status of relevant genes have been linked to the origin, perpetuation, and severity of airway diseases. The DNA methylation profile can be also modified by the action of viral and bacterial colonization. Bacteria and specially Staphylococcus aureus toxins are recognized inflammatory amplifying factors in both lower and upper airway chronic diseases. This review summarizes the existent knowledge about the role of DNA methylation changes in chronic airway diseases and the contribution of bacterial infection on this event.

RECENT FINDINGS

It has been demonstrated that changes in DNA methylation, either intrinsic or induced by allergen or infection, may be linked to the pathogenesis of asthma and allergy. These changes in methylation may suppress the production of anti-inflammatory mediators and increase the survival and activation of pro-inflammatory cells, as well as modify the immune response in response to bacterial infection, increasing their survival and pathogenicity within the infected organism.

SUMMARY

Understanding the intrinsic epigenetic mechanisms, as well as the effect of environment -for example, bacterial infection in the pathogenesis of airways diseases - will greatly improve the management and the diagnosis of these diseases.

Clinical features of elderly chronic urticaria

BACKGROUND/AIMS

Chronic urticaria (CU) is defined as itchy wheals lasting 6 weeks or more. As the aged population increases worldwide, it is essential to identify the specific features of this disease in the elderly population.

METHODS

We investigated the prevalence and clinical features of CU in elderly patients. Medical records of 837 CU patients from the outpatient Allergy Clinic of Ajou University Hospital, Korea were analyzed retrospectively. Patients with chronic spontaneous urticaria according to the EAACI/GA2LEN/EDF/WAO guidelines were included. Patients older than 60 years were defined as elderly.

RESULTS

Of the 837 patients, 37 (4.5%) were elderly. In elderly versus nonelderly CU patients, the prevalence of atopic dermatitis (AD) was significantly higher (37.8% vs. 21.7%, respectively; p = 0.022), while that of aspirin intolerance was lower (18.9% vs. 43.6%, respectively; p = 0.003) in terms of comorbid conditions. The prevalences of serum specific immunoglobulin E antibodies to staphylococcal enterotoxin A and staphylococcal enterotoxin B were considerably higher in elderly CU patients with AD than in those without AD (37.5% vs. 0%, respectively).

CONCLUSIONS

Elderly patients with CU had a higher prevalence of AD. Therefore, there is a need to recognize the existence of AD in elderly CU patients.

Transforming growth factor-beta 1 pathways in inflammatory airway diseases

Transforming growth factor-beta 1 (TGF-β1) has been reported being involved in the remodeling and immunosuppression processes of inflammatory airway diseases; understanding the regulation of TGF-β1 is therefore a key to unravel the pathomechanisms of these diseases. This review briefly summarizes the current knowledge on the influencing factors for driving TGF-β1 and its regulatory pathways in inflammatory airway diseases and discusses possible therapeutic approaches to TGF-β1 control. The factors include smoking and oxidative stress, prostaglandins (PGs), leukotrienes (LTs), bradykinin (BK), and microRNAs (miRs). Based on the summary, new innovative treatment strategies may be developed for inflammatory airway diseases with an impaired expression of TGF-β1.

Aspirin desensitization in patients with aspirin-induced and aspirin-tolerant asthma: a double-blind study

BACKGROUND

Numerous open trials have demonstrated the beneficial clinical effects of aspirin desensitization (AD) in patients with aspirin-induced asthma (AIA). These beneficial effects might be attributable to aspirin's potent anti-inflammatory properties, but that supposition requires further corroboration.

OBJECTIVE

We sought to compare the clinical and biochemical responses to chronic oral AD in 20 patients with AIA and 14 patients with aspirin-tolerant asthma (ATA). All of the patients had chronic rhinosinusitis and nasal polyposis, and these responses were investigated in a pilot, double-blind, placebo-controlled study.

METHODS

Twelve patients with AIA and 6 patients with ATA were randomly assigned to receive 624 mg of aspirin, and 8 patients with AIA and 8 patients with ATA received placebo. Both aspirin and placebo were administered once daily for 6 months. Nasal symptoms, Sino-Nasal Outcome Test (SNOT20) scores, peak nasal inspiratory flows, Asthma Control Questionnaire scores, spirometric parameters, peak expiratory flows, blood eosinophilia, and corticosteroid doses were assessed on a monthly basis. Levels of urinary leukotriene E4 and the stable plasma prostaglandin (PG) D2 metabolite 9α,11β-PGF2 were evaluated at baseline and after 1, 3, 5, and 6 months.

RESULTS

Only the patients with AIA subjected to AD reported improvements in smell and reductions in sneezing and nasal blockade. The SNOT20 and Asthma Control Questionnaire scores of these patients decreased, and their peak nasal inspiratory flows increased. The dosages of inhaled corticosteroids were reduced. There were no changes in leukotriene E(4) or 9α,11β-PGF(2) levels after AD.

CONCLUSION

The clinically beneficial effects of AD on nasal and bronchial symptoms occurred only in the patients with AIA.

Immunopathogenesis of eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus associated with dysphagia in adults and refractory reflux syndromes in children.

METHODS

Immunological and genetic approaches have been used to better understand the pathophysiology of the underlying inflammation.

RESULTS AND CONCLUSIONS

Evidence has accumulated that EoE represents a T-helper (Th) 2-type inflammatory disease, in which allergens play a role in triggering the disease. The majority of the patients suffer from concurrent allergic rhinitis, asthma, and eczema, and have a history of atopy. The chronic inflammatory response in EoE is associated with tissue damage and remodeling, both of which lead to esophageal dysfunction and bolus impaction. The new insights into the pathophysiology have resulted in the development of the first pharmacological therapies of EoE.

Immunoregulatory effects of bone marrow-derived mesenchymal stem cells in the nasal polyp microenvironment

Nasal polyposis is a severe, chronic inflammatory condition of the paranasal sinuses and is frequently associated with asthma and aspirin sensitivity. Mesenchymal stem cells exhibit a potent immunosuppressive effect in several inflammatory conditions, and their role in nasal polyposis remains little explored. Hence, we investigated whether bone marrow-derived mesenchymal stem cells could modulate cell phenotype in the nasal polyp milieu. After coculture with mesenchymal stem cells, the frequency of these inflammatory cells was found to decrease. Furthermore, mesenchymal stem cells promoted strong inhibition of CD4+ and CD8+ T cell proliferation, increased the frequency of CD4+CD25+Foxp3 T cells, and changed the global cytokine profile from an inflammatory to an anti-inflammatory response. We believe that mesenchymal stem cells may be a very useful adjunct for investigation of the inflammatory process in nasal polyposis, contributing to better understanding of the inflammatory course of this condition.

CD8(+) T cells producing IL-3 and IL-5 in non-IgE-mediated eosinophilic diseases

The cytokines IL-5, IL-3, and GM-CSF are crucial for eosinophil development, survival, and function. To better understand their role in non-IgE-mediated eosinophilic diseases, we investigated plasma levels of these cytokines as well as cytokine expression in peripheral blood T cells. While we did not find any evidence for an involvement of T-cell-derived GM-CSF, some of these patients did show an increased proportion of IL-5- or IL-3-producing CD4(+) T cells. However, in a significant proportion of patients, IL-5-producing CD8(+) T cells, so-called Tc2 cells, which in healthy donors can only be detected at very low levels, were prominent. Furthermore, increased IL-3 production by CD8(+) T cells was also observed, strongly supporting the notion that CD8(+) T cells, not just CD4(+) T cells, must also be considered as a potential source of the cytokines promoting eosinophilia.

Mechanisms and potential therapeutic targets in allergic inflammation: recent insights

Deeper insight into pathogenetic pathways and into the biological effects of immunomodulatory agents will help to optimize or adopt therapeutic strategies for atopic disorders. In this article, we highlight selected findings of potential therapeutic relevance that emerged from recent mechanistic studies with focus on molecular and cellular aspects of allergic inflammation. Furthermore, the often complex mechanisms of action of pleiotropic immunomodulatory agents, such as glucocorticoids, vitamin D, or intravenous immunoglobulin (IVIG), are discussed, as their dissection might reveal targets for novel therapeutics or lead to a more rational use of these compounds. Besides reporting novel evidence, this article points to areas of current debate or uncertainty and aims at stimulating scientific discussion and experimental work.

Staphylococcus aureus enterotoxin B-induced endoplasmic reticulum stress response is associated with chronic rhinosinusitis with nasal polyposis

OBJECTIVE

Staphylococcus aureus enterotoxin B (SEB) might participate in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). However, the exact mechanism of polyp formation in CRSwNP remains unclear. Since the endoplasmic reticulum (ER) stress response is closely associated with chronic inflammation, we investigated the association between ER stress and SEB in the pathogenesis of CRSwNP.

DESIGN AND METHODS

Twenty-three CRSwNP patients with eosinophilic polyps (EP) or non-eosinophilic polyps (NEP) and 10 healthy subjects who were undergoing septoplasty were enrolled in this study. ER stress response was investigated using immunohistochemical staining and Western blotting.

RESULTS

We show in this study that there are significantly more SEB-positive cells and higher production of reactive oxygen species (ROS) in the epithelial layer of EP than NEP or control tissue. Both SEB and protein A were detected strongly in tissues from patients with CRSwNP. We observed SEB induced the ER stress response in RPMI 2650 cells. GRP78 elevation by SEB was reduced by ROS scavenger pretreatment. In addition, the induction of GRP78 and p47 phox was increased significantly in EP compared with NEP or control mucosa.

CONCLUSIONS

SEB may induce ER stress via ROS production in CRSwNP. Therefore, we suggest that SEB-induced ER stress may play important roles in the pathogenesis of nasal polyposis.

Bone: the final frontier for Staphylococcus aureus penetration in chronic rhinosinusitis

The superantigenic properties of Staphylococcus aureus have been implicated in increasing the inflammatory process in airway diseases. Local formation of IgE antibodies against staphylococcal enterotoxins by secondary lymphoid tissue in nasal polyps has been demonstrated. Staphylococcus aureus is known to colonize the nasal mucosa, and has been found invading the nasal submucosa and intracellularly.

Objective

To evaluate the limits of Staphylococcus aureus invasion in the upper airway.

Material and methods

Inferior turbinate samples from 3 patients without sinus disease, 6 ethmoid samples from patients with chronic rhinosinusitis with nasal polyposis, and 6 ethmoid samples from patients with chronic rhinosinusitis without nasal polyposis were studied. A fluorescein-labeled PNA probe against Staphylococcus aureus was used to test for the presence of the bacterium in bone (after decalcification) and mucosa.

Results

We found Staphylococcus aureus invading the nasal submucosa in patients with nasal polyposis, but no cases of Staphylococcus aureus positivity in bone. In conclusion, we cannot support the hypothesis of nasal bone as a reservoir for Staphylococcus aureus, releasing massive amounts of staphylococcal enterotoxins and eliciting an inflammatory reaction, as occurs with the nasal mucosa.

Understanding resolvin signaling pathways to improve oral health

The discovery of resolvins has been a major breakthrough for understanding the processes involved in resolution of inflammation. Resolvins belong to a family of novel lipid mediators that possess dual anti-inflammatory and pro-resolution actions. Specifically, they protect healthy tissue during immune-inflammatory responses to infection or injury, thereby aiding inflammation resolution and promoting tissue healing. One of the major concerns in modern medicine is the management and treatment of oral diseases, as they are related to systemic outcomes impacting the quality of life of many patients. This review summarizes known signaling pathways utilized by resolvins to regulate inflammatory responses associated with the oral cavity.