Polymorphisms in the nitric oxide synthase 1 gene are associated with severe chronic rhinosinusitis

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.

Genetics and epigenetics of chronic rhinosinusitis

Discerning the genetics and epigenetics of chronic rhinosinusitis (CRS) may optimize outcomes through early diagnostics, personalized and novel therapeutics, and early prognostication. CRS associated with cystic fibrosis and primary ciliary dyskinesia has well-characterized genetic mutations. Most CRS subjects, however, do not exhibit identifiable monogenic alterations. Clustering in related individuals is seen in CRS with nasal polyps. Spouses of subjects with CRS without nasal polyps also may be at increased risk of the same disease. These observations generate questions on genetic and environmental influences in CRS. Genome-wide association studies have identified variations and polymorphisms between CRS and control subjects in genes related to innate and adaptive immunity. Candidate gene and transcriptomics studies have investigated and identified genetic variations related to immunity, inflammation, epithelial barrier function, stress-response, antigen processing, T-cell regulation, and cytokines in CRS. Epigenetic studies have identified mechanisms through which environmental factors may affect these gene functions. However, causality is not determined for most variations. Inferences drawn from these data must be measured because most investigations report unreplicated results from small study populations. Large, replicated studies in tight cohorts across diverse populations remain a pressing need in studying CRS genetics.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

Taste Receptors in Upper Airway Innate Immunity

Taste receptors, first identified on the tongue, are best known for their role in guiding our dietary preferences. The expression of taste receptors for umami, sweet, and bitter have been demonstrated in tissues outside of the oral cavity, including in the airway, brain, gastrointestinal tract, and reproductive organs. The extra-oral taste receptor chemosensory pathways and the endogenous taste receptor ligands are generally unknown, but there is increasing data suggesting that taste receptors are involved in regulating some aspects of innate immunity, and may potentially control the composition of the nasal microbiome in healthy individuals or patients with upper respiratory diseases like chronic rhinosinusitis (CRS). For this reason, taste receptors may serve as potential therapeutic targets, providing alternatives to conventional antibiotics. This review focuses on the physiology of sweet (T1R) and bitter (T2R) taste receptors in the airway and their activation by secreted bacterial products. There is particular focus on T2R38 in sinonasal ciliated cells, as well as the sweet and bitter receptors found on specialized sinonasal solitary chemosensory cells. Additionally, this review explores the impact of genetic variations in these receptors on the differential susceptibility of patients to upper airway infections, such as CRS.

What is the evidence for genetics in chronic rhinosinusitis?

PURPOSE OF REVIEW

To perform analysis of evidence in current literature on the topic of genetics and chronic rhinosinusitis (CRS), with a particular focus on recent findings in the cystic fibrosis transmembrane regulator (CFTR), genes associated with primary ciliary dyskinesia, and taste receptor T2R38. Other genes that have been found to have association with CRS are also presented and discussed.

RECENT FINDINGS

Recent studies in CFTR and CRS research have investigated possible CFTR-potentiators for treatment of refractory CRS. The T2R38 gene has been shown to be applicable in the clinical setting with a testable phenotype and may have a role in the prognosis and influencing management strategies of CRS patients. Many genes of the immune system have been studied, with genome-wide association studies and candidate-gene approaches identifying new associations that will need replication and further elucidation.

SUMMARY

CRS is a multifactorial disease, with strong evidence of a genetic component in its pathophysiology for some cases. Currently, there are over 70 genes that have been genetically associated with CRS in the past 15 years. Future investigations into genetic causes and predispositions of CRS may allow for improved prognostication and development of disease-prevention strategies as well as novel therapeutic targets.

Taste receptors in the upper airway

Taste receptors were named for their originally-identified expression on the tongue and role in the sensation of taste (gustation). They are now known to be involved in many chemosensory processes outside the tongue. Expression of the receptors for bitter, sweet, and umami was recently identified in many organs, including the brain, airway, gastrointestinal tract, and reproductive systems. We do not yet know the full roles of these receptors in all of these tissues, nor do we know all of the endogenous ligands that activate them. However, taste receptors are emerging as potentially important therapeutic targets. Moreover, they may mediate some off target effects of drugs, as many medications in common clinical use are known to be bitter. The focus of this review is on recent basic and clinical data describing the expression of bitter (T2R) and sweet (T1R) receptors in the airway and their activation by secreted bacterial compounds. These receptors play important roles in innate immune nitric oxide production and antimicrobial peptide secretion, and may be useful targets for stimulating immune responses in the upper respiratory tract via topical therapies. Moreover, genetic variation in these receptors may play a role in the differential susceptibility of patients to certain types of respiratory infections as well as to differential outcomes in patients with chronic rhinosinusitis (CRS). CRS is a syndrome of chronic upper respiratory infection and inflammation and has a significant detrimental impact on patient quality of life. CRS treatment accounts for approximately 20% of adult antibiotic prescriptions and is thus a large driver of the public health crisis of antibiotic resistance. Taste receptors represent a novel class of therapeutic target to potentially stimulate endogenous immune responses and treat CRS patients without conventional antibiotics.

Neutrophil microparticle production and inflammasome activation by hyperglycemia due to cytoskeletal instability

Microparticles are lipid bilayer-enclosed vesicles produced by cells under oxidative stress. MP production is elevated in patients with diabetes, but the underlying cellular mechanisms are poorly understood. We hypothesized that raising glucose above the physiological level of 5.5 mm would stimulate leukocytes to produce MPs and activate the nucleotide-binding domain, leucine-rich repeat pyrin domain-containing 3 (NLRP3) inflammasome. We found that when incubated in buffer with up to 20 mm glucose, human and murine neutrophils, but not monocytes, generate progressively more MPs with high interleukin (IL)-1β content. Enhanced MP production required generation of reactive chemical species by mitochondria, NADPH oxidase, and type 2 nitric-oxide synthase (NOS-2) and resulted in S-nitrosylation of actin. Depleting cells of capon (C-terminal PDZ ligand of neuronal nitric-oxide synthase protein), apoptosis-associated speck-like protein containing C-terminal caspase recruitment domain (ASC), or pro-IL-1β prevented the hyperglycemia-induced enhancement of reactive species production, MP generation, and IL-1β synthesis. Additional components required for these responses included inositol 1,3,5-triphosphate receptors, PKC, and enhancement of filamentous-actin turnover. Numerous proteins become localized to short filamentous actin in response to S-nitrosylation, including vasodilator-stimulated phosphoprotein, focal adhesion kinase, the membrane phospholipid translocation enzymes flippase and floppase, capon, NLRP3, and ASC. We conclude that an interdependent oxidative stress response to hyperglycemia perturbs neutrophil cytoskeletal stability leading to MP production and IL-1β synthesis.

NOS1AP genetic variation is associated with impaired healing of diabetic foot ulcers and diminished response to healing of circulating stem/progenitor cells

It is unclear why many with diabetes develop foot ulcers (DFU) and why some do not heal. It could be associated with genetic variation. We have previously shown that NOS1AP variation is associated with lower extremity amputation in those with diabetes and that circulating stem progenitor cell concentration (SPC) is associated with impaired foot ulcer healing in those with diabetes. The goal of this study was to determine if NOS1AP variation is associated with impaired wound healing and with SPC mobilization in those with DFU. In longitudinal cohort study we demonstrate that NOS1AP variants rs16849113 and rs19649113 are associated with impaired wound healing and with SPC mobilization in those with DFU. We believe that further study of NOS1AP is merited and that it NOS1AP might be associated with a functional impairment.

Flavones modulate respiratory epithelial innate immunity: Anti-inflammatory effects and activation of the T2R14 receptor

Chronic rhinosinusitis has a significant impact on patient quality of life, creates billions of dollars of annual healthcare costs, and accounts for ∼20% of adult antibiotic prescriptions in the United States. Because of the rise of resistant microorganisms, there is a critical need to better understand how to stimulate and/or enhance innate immune responses as a therapeutic modality to treat respiratory infections. We recently identified bitter taste receptors (taste family type 2 receptors, or T2Rs) as important regulators of sinonasal immune responses and potentially important therapeutic targets. Here, we examined the immunomodulatory potential of flavones, a class of flavonoids previously demonstrated to have antibacterial and anti-inflammatory effects. Some flavones are also T2R agonists. We found that several flavones inhibit Muc5AC and inducible NOS up-regulation as well as cytokine release in primary and cultured airway cells in response to several inflammatory stimuli. This occurs at least partly through inhibition of protein kinase C and receptor tyrosine kinase activity. We also demonstrate that sinonasal ciliated epithelial cells express T2R14, which closely co-localizes (<7 nm) with the T2R38 isoform. Heterologously expressed T2R14 responds to multiple flavones. These flavones also activate T2R14-driven calcium signals in primary cells that activate nitric oxide production to increase ciliary beating and mucociliary clearance. TAS2R38 polymorphisms encode functional (PAV: proline, alanine, and valine at positions 49, 262, and 296, respectively) or non-functional (AVI: alanine, valine, isoleucine at positions 49, 262, and 296, respectively) T2R38. Our data demonstrate that T2R14 in sinonasal cilia is a potential therapeutic target for upper respiratory infections and that flavones may have clinical potential as topical therapeutics, particularly in T2R38 AVI/AVI individuals.

Genetic and Immune Dysregulation in Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a prevalent condition that is heterogeneous in disease characteristics and multifactorial in cause. Although sinonasal mucosal inflammation in CRS is often either reversible or well-managed medically and surgically, a significant proportion of patients has a refractory form of CRS despite maximal therapy. Two of the several described factors thought to contribute to disease recalcitrance are genetic influences and dysfunction of the host immune system. Current evidence for a genetic basis of CRS is reviewed, as it pertains to putative abnormalities in innate and adaptive immune function. The role of systemic immunodeficiencies in refractory CRS is discussed.

A comprehensive review of the nasal microbiome in chronic rhinosinusitis (CRS)

Chronic rhinosinusitis (CRS) has been known as a disease with strong infectious and inflammatory components for decades. The recent advancement in methods identifying microbes has helped implicate the airway microbiome in inflammatory respiratory diseases such as asthma and COPD. Such studies support a role of resident microbes in both health and disease of host tissue, especially in the case of inflammatory mucosal diseases. Identifying interactive events between microbes and elements of the immune system can help us to uncover the pathogenic mechanisms underlying CRS. Here we provide a review of the findings on the complex upper respiratory microbiome in CRS in comparison with healthy controls. Furthermore, we have reviewed the defects and alterations of the host immune system that interact with microbes and could be associated with dysbiosis in CRS.

Pathophysiology of chronic rhinosinusitis, pharmaceutical therapy options

Research in immunology has brought great progress in knowledge of inflammatory processes in the last 2 decades, which also has an impact on the upper airways. Our understanding of the pathophysiology of chronic rhinosinusitis developed from a rather mechanistic point of view with a focus on narrow clefts and mucociliary clearance to the appreciation of a complex network of immunological pathways forming the basis of disease. We today differentiate various forms of inflammation, we start to understand complex immune-regulatory networks and the reasons for their failure, and have already developed innovative approaches for therapy for the most severely ill subjects. Due to this new knowledge in inflammation and remodeling processes within mucosal tissue, specifically on the key driving factors, new diagnostic tools and therapeutic approaches for chronic rhinosinusitis have developed; the differentiation of endotypes based on pathophysiological principles will be crucial for the use of innovative therapies, mostly humanized monoclonal antibodies. Several hundred of those antibodies are currently developed for various indications and will impact our specialty as well as pneumology to a great extent.

Risk factors for chronic rhinosinusitis

PURPOSE OF REVIEW

To review the recent literature on risk factors for chronic rhinosinusitis (CRS) with an emphasis on genetic, comorbid diseases and environmental factors associated with CRS. Through identifying potential risk factors for CRS, we aim to glean insights into the underlying pathogenic mechanisms essential for developing effective therapeutic strategies.

RECENT FINDINGS

Recent findings demonstrate that genetics and comorbid medical conditions including airway diseases, gastroesophageal reflux disease, inflammatory and autoimmune diseases, and various demographic and environmental factors are associated with having a CRS diagnosis. Limitations of current studies include variable application of disease definitions, lack of prospective longitudinal studies and a disproportionate focus on tertiary care populations.

SUMMARY

CRS has a broad spectrum of associations ranging from genetics to comorbid diseases and environmental factors. These predisposing factors may provide valuable information for possible designing of therapeutic and preventive interventions. However, to better understand whether these associations cause CRS, further studies are needed to independently replicate findings, establish temporal relationships between exposure and disease onset, evaluate the influence of exposure dose on disease severity, and to understand the biological effects of these risk factors in the context of CRS.

Familial risk of chronic rhinosinusitis with and without nasal polyposis: genetics or environment

BACKGROUND

Chronic rhinosinusitis (CRS) is a highly prevalent inflammatory condition, with significant effects on morbidity and quality of life, yet little is known about its pathogenesis. Preliminary evidence suggests there is a heritable component to the multifactorial etiology of CRS; however, our understanding of this genetic susceptibility is limited.

METHODS

Using an extensive genealogical database linked to medical records, the risk of CRS with nasal polyps (CRSwNP) and without polyps (CRSsNP) was calculated for relatives and spouses of adult probands (1638 CRSwNP and 24,200 CRSsNP patients diagnosed between 1996 and 2011) and were compared to random population controls matched 5:1 on sex and birth year from Cox regression models.

RESULTS

First-degree relatives (1stDRs) of CRSwNP patients demonstrated a 4.1-fold increased risk (p < 10(-3) ) of carrying the same diagnosis, whereas second-degree relatives (2ndDRs) demonstrated a 3.3-fold increased risk (p < 0.004), compared to controls. In CRSsNP patients, 1stDRs were at 2.4-fold increased risk (p < 10(-15) ), whereas 2ndDRs were at 1.4-fold increased risk (p < 10(-15) ) of the same diagnosis. Third-degree relatives (3rdDRs) had a slight increased risk at 1.1-fold (p < 10(-7) ). Spouses of CRSsNP patients, who likely share environmental circumstances, exhibited a 2-fold increased risk (p < 10(-15) ). No increased risk was observed in spouses of CRSwNP patients.

CONCLUSION

In the largest population study to date, a significant familial risk is confirmed in CRSwNP and CRSsNP, which may have a shared genetic and environmental component. Further understanding of the genetic basis of CRS and its interplay with environment factors could clarify disease etiology and lead to more effective targeted treatments.

Oxidative stress and nasal polyposis: does it affect the severity of the disease?

BACKGROUND

Nasal polyposis (NP) is a chronic inflammatory disease and the waste products of this inflammation are reactive oxygen species composed of free radicals. Changes in oxidative status have already been revealed in NP. The aim of this study was to investigate the effect of oxidative status to the severity of the disease and the quality of life.

METHODS

The study group included 24 patients with NP and 20 controls. The Turkish version of the Rhinosinusitis Disability Index, visual analog scale (VAS), polyp stage, computed tomography (CT) score, and the eosinophilic cationic protein (ECP) levels in nasal lavage (NAL) fluid were used to assess the severity of the disease. Malondialdehyde, nitric oxide (NO), and the total antioxidant status (TAS) levels in NAL fluids were measured representing the oxidative stress.

RESULTS

NO values were correlated with nasal congestion (p = 0.031). TAS values were correlated with nasal obstruction (p = 0.039). ECP values showed correlation with all the nasal obstruction (p = 0.003), congestion (p = 0.009), rhinorrhea (p = 0.009), and VAS scores (p = 0.039).

CONCLUSION

In NP, ECP levels detected in NAL fluid were significantly high and were correlated with the severity of the disease. Moreover, the severity of oxidative stress, in the forms of TAS and NO, is significantly correlated with the severity of the nasal obstruction and congestion, respectively.

Taste receptors in innate immunity

Taste receptors were first identified on the tongue, where they initiate a signaling pathway that communicates information to the brain about the nutrient content or potential toxicity of ingested foods. However, recent research has shown that taste receptors are also expressed in a myriad of other tissues, from the airway and gastrointestinal epithelia to the pancreas and brain. The functions of many of these extraoral taste receptors remain unknown, but emerging evidence suggests that bitter and sweet taste receptors in the airway are important sentinels of innate immunity. This review discusses taste receptor signaling, focusing on the G-protein-coupled receptors that detect bitter, sweet, and savory tastes, followed by an overview of extraoral taste receptors and in-depth discussion of studies demonstrating the roles of taste receptors in airway innate immunity. Future research on extraoral taste receptors has significant potential for identification of novel immune mechanisms and insights into host-pathogen interactions.

ICON: chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a public health problem that has a significant socio-economic impact. Moreover, the complexity of this disease due to its heterogeneous nature based on the underlying pathophysiology - leading to different disease variants - further complicates our understanding and directions for the most appropriate targeted treatment strategies. Several International/national guidelines/position papers and/or consensus documents are available that present the current knowledge and treatment strategies for CRS. Yet there are many challenges to the management of CRS especially in the case of the more severe and refractory forms of disease. Therefore, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), a collaboration between EAACI, AAAAI, ACAAI, and WAO, has decided to propose an International Consensus (ICON) on Chronic Rhinosinusitis. The purpose of this ICON on CRS is to highlight the key common messages from the existing guidelines, the differences in recommendations as well as the gaps in our current knowledge of CRS, thus providing a concise reference. In this document we discuss the definition of the disease, its relevance, pharmacoeconomics, pathophysiology, phenotypes and endotypes, genetics and risk factors, natural history and co-morbidities as well as clinical manifestations and treatment options in both adults and children comprising pharmacotherapy, surgical interventions and more recent biological approaches. Finally, we have also highlighted the unmet needs that wait to be addressed through future research.

Endogenous Production of Hydrogen Sulfide in Human Sinus Mucosa and its Expression Levels are Altered in Patients with Chronic Rhinosinusitis with and without Nasal Polyps

Background

Chronic rhinosinusitis with nasal polyps (CRSwNPs) or CRS without nasal polyps (CRSsNPs) is characterized by persistent inflammation of sinonasal mucosa. No one causative factor fully explains for the pathological manifestations of CRS. Endogenous hydrogen sulfide (H2S) has been shown to participate in inflammatory diseases, functioning as an inflammatory mediator in various organs. We analyzed the contents and synthesis activity of H2S, the expression and distribution pattern of H2S-generating enzymes, cystathione β-synthase (CBS), and cystathione γ-lyase (CSE) in CRSwNPs and CRSsNPs. The effects of H2S on the expression of CRS-relevant cytokines and the effects of cytokines on the expression of CBS and CSE were assessed in an in vitro experiment.

Methods

The contents and synthesis activity of H2S and the expression and distribution pattern of CBS and CSE in sinus mucosa were evaluated using spectrophotometry, real-time polymerase chain reaction, Western blot, and immunohistochemistry. Cultured epithelial cells were used to elucidate the effects of H2S donor, sodium hydrosulfide (NaHS), on the expression of CRS-relevant cytokines and the effects of cytokines on H2S-generating enzymes expression.

Results

The contents and synthesis activity of H2S were increased in CRSwNPs and CRSsNPs. CBS and CSE were localized to the superficial epithelium and submucosal glands, but CSE was also found in vascular endothelium. N S induced increased expression of IL-4, IL-5, interferon γ, and TNF-α. CBS and CSE expression in cultured cells was up-regulated by CRS-relevant cytokines.

Conclusion

H2S levels are increased in CRS, contributing to increased production of cytokines. These results suggest that H2S may function as inflammatory mediator in CRS.

Nasal and Exhaled Nitric Oxide in Chronic Rhinosinusitis with Polyps

Background

The ciliary epithelial cells in the paranasal sinuses produce nasal nitric oxide (NO) continuously and plays a variety of roles in the paranasal sinuses. The purpose of this study was to assess whether we can use the levels of nasal NO (nNO) and exhaled NO (eNO) as a tool for evaluation in chronic rhinosinusitis (CRS) with nasal polyp patients.

Methods

We used chemiluminescent NO analyzer to measure nNO and eNO among normal controls (32) and CRS with polyp (30) and CRS with polyp and allergic rhinitis patients (27) and compared it with various clinical symptoms, laboratory data, and computed tomography (CT) scores.

Results

Levels of nNO were significantly lower in patients with CRS with polyps (88.5 ± 54.7 ppb) compared with controls (241.0 ± 89.5 ppb). Levels of nNO in CRS with polyps and allergic rhinitis (167.0 ± 47.6 ppb) were significantly higher than CRS with polyps and lower than controls. A significant inverse relationship was observed between nNO and sinus CT scores, severity of nasal obstruction, and purulent rhinorrhea in CRS with polyps. Low values of nNO separated well patients with CRS with polyps, and the cutoff value of <163 ppb was associated with the best com nation of specificity (93%) and sensitivity (81%). A significant positive relationship was observed between eNO and CT scores.

Conclusion

The nNO could be used for another screening of CRS with polyps for the more severe phenotypes, which may eventually have to be treated with surgery.

Mouse nasal epithelial innate immune responses to Pseudomonas aeruginosa quorum-sensing molecules require taste signaling components

We previously observed that the human bitter taste receptor T2R38 is an important component of upper respiratory innate defense because it detects acyl homoserine lactone (AHL) quorum-sensing molecules secreted by Gram-negative bacteria. T2R38 activation in human sinonasal epithelial cells stimulates calcium and NO signals that increase mucociliary clearance, the major physical respiratory defense against inhaled pathogens. While mice do not have a clear T2R38 ortholog, they do have bitter taste receptors capable of responding to T2R38 agonists, suggesting that T2R-mediated innate immune mechanisms may be conserved in mice. We examined whether AHLs activate calcium and NO signaling in mouse nasal epithelial cells, and utilized pharmacology, as well as cells from knockout mice lacking important components of canonical taste signal transduction pathways, to determine if AHL-stimulated responses require taste signaling molecules. We found that AHLs stimulate calcium-dependent NO production that increases mucociliary clearance and thus likely serves an innate immune role against Gram-negative bacteria. These responses require PLCβ2 and TRPM5 taste signaling components, but not α-gustducin. These data suggest the mouse may be a useful model for further studies of T2R-mediated innate immunity.

Chronic rhinosinusitis and sleep: a contemporary review

BACKGROUND

Patients with chronic rhinosinusitis (CRS) exhibit centrally mediated behavioral changes commonly referred to as "sickness behavior." Sleep alteration is a component of sickness behavior which is estimated to affect up to 70 million patients annually. Patients with CRS have poor sleep quality, and little is known about the underlying etiology and pathophysiology. This narrative review aims to further organize and present the current knowledge associating sleep and CRS.

METHODS

A literature search was conducted of the OVID MEDLINE database using key search words including: "chronic rhinosinusitis," "sleep," "sleep disorders," and "sleep dysfunction." Additional keywords "nasal obstruction," "nasal polyp," and "fatigue" were identified and used to further delineate relevant articles.

RESULTS

The articles that specifically addressed sleep and CRS were dissected and presented as follows: (1) chronic rhinosinusitis and sleep; (2) chronic rhinosinusitis and fatigue; (3) chronic rhinosinusitis, nasal obstruction, and sleep; and (4) pathophysiology of sleep in chronic rhinosinusitis (cytokines in both sleep and chronic rhinosinusitis and their association to the neuroimmune biology of chronic rhinosinusitis).

CONCLUSION

Patients with CRS have sleep dysfunction that is associated with their disease severity and overall quality of life. The etiology of sleep dysfunction in CRS is most likely multifactorial. Increasing evidence suggests sleep dysfunction in patients with CRS is partly due to the inflammatory disease process, and sleep physiology in patients with CRS may be actively regulated by the inflammatory component of the disease.

Genetics of chronic rhinosinusitis: state of the field and directions forward

The cause of chronic rhinosinusitis (CRS) remains unclear. Study of the genetic susceptibility to CRS might be a valuable strategy to understand the pathogenesis of this burdensome disorder. The purpose of this review is to critically evaluate the current literature regarding the genetics of CRS in a comprehensive fashion. The most promising findings from candidate gene studies include the cystic fibrosis transmembrane conductance regulator gene (CFTR), as well as genes involved in antigen presentation, innate and adaptive immune responses, tissue remodeling, and arachidonic acid metabolism. We also review the few hypothesis-independent genetic studies of CRS (ie, linkage analysis and pooling-based genome-wide association studies). Interpretation of the current literature is limited by challenges with study design, sparse replication, few functional correlates of associated polymorphisms, and inadequate examination of linkage disequilibrium or expression quantitative trait loci for reported associations. Given the relationship of CRS to other airway disorders with well-characterized genetic components (eg, asthma), study of the genetics of CRS deserves increased attention and investment, including the organization of large, detailed, and collaborative studies to advance knowledge of the mechanisms that underlie this disorder.

Some Polymorphisms in Epstein-Barr Virus–induced Gene 3 Modify the Risk for Chronic Rhinosinusitis

Background

Forkhead box protein 3 (FOXP3), a transcription factor required for development and function of regulatory T cell, and Epstein-Barr virus–induced gene 3 (EBI3), a downstream target of FOXP3, may be important in the development of chronic rhinosinusitis (CRS) with or without sinonasal polyposis (CRSwNP and CRSsNP, respectively). Our objective was therefore to examine the presence of any associations between specific single nucleotide polymorphisms (SNPs) in/around the FOXP3 and EBI3 genes and risk for CRS in Chinese subjects. A population-based case–control association analysis was performed.

Methods

DNA extracted from peripheral blood leukocytes from 667 subjects with CRS (360 CRSwNP and 306 CRSsNP) and 330 healthy controls was assessed for SNPs selected and complemented with tagging SNPs. A total of seven SNPs (4 in FOXP3 and 3 in EBI3 genes) were genotyped and genetic association tests were performed.

Results

In the single-locus analyses of CRS risk, the allele frequencies of rs428253 (p = 0.0191) in EBI3 gene and rs2232365 (p = 0.0307) and rs3761548 (p = 0.0221) in FOXP3 gene were significantly different between the CRS cases and the controls. Furthermore, genotype association analysis showed a significant protective effect only between EBI3_rs428253 (CG/CC; p = 0.029) and CRS after adjustment. Similarly, stratified analysis of CRS risk on category showed rs428253 of the EBI3 gene to play a protective role among both CRSwNP (CG/CC; p = 0.002) and CRSsNP (GG/CC; p = 0.023) subjects. Haplotype analysis of the FOXP3 gene region further indicated that CRS risk was higher in individuals carrying the haplotype GG in rs2294018–rs2232365 block, compared with wild-type AG haplotype, and AG in rs3761548–4824747 block, compared with wild-type CG haplotype.

Conclusion

The findings of this study suggest that SNPs in FOXP3 and EBI3 genes modify the risk for development of CRS.

Two patterns of changes in nasal nitric oxide after lysine aspirin nasal challenge in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Nasal nitric oxide (nNO) levels after nasal lysine acetylsalicylic acid (lys-ASA) challenge have not been determined. This study was designed to determine a pattern of changes after lys-ASA challenge in aspirin-exacerbated respiratory disease (AERD) patients and to evaluate the usefulness of nNO measurements in the assessment of lys-ASA nasal challenge outcome.

METHODS

Eighteen patients with aspirin hypersensitivity, nasal polyps, and asthma were included. Aspirin-tolerant control groups consisted of 10 healthy volunteers without asthma and nasal polyps and 10 patients with nasal polyps without asthma. All subjects underwent nasal challenge with lys-ASA. nNO was measured before and 1, 2, 4, and 24 hours after control solution and lys-ASA administration.

RESULTS

A significant fall in nNO levels was noted in AERD patients with a positive result to challenges at time points 1 hour (p = 0.0033), 2 hours (p = 0.0033), and 3 hours (p = 0.026) after lys-ASA. A trend toward higher nNO concentrations was observed after lys-ASA challenge at the 2-hour (p = 0.018) and 4-hour (p = 0.018) time points compared with baseline in subjects with AERD and a clinically negative result to the challenge. No significant changes in nNO levels after the challenge were observed in control groups. The combined increase and decrease in nNO levels gave the sensitivity as 0.94 and specificity 1.00 at best.

CONCLUSION

nNO levels decrease after lys-ASA nasal challenge in subjects with AERD and a clinically positive result of the challenge. An unexpected trend toward an increase in nNO levels is observed in subjects with AERD and a clinically negative result of the challenge.

The role of nitrosative stress in the pathogenesis of unexplained chronic cough with cough hypersensitivity

BACKGROUND

Unexplained chronic cough is a common condition without specific causes. A hyperreactivity of the cough reflex has been suggested as a mechanism for inducing chronic cough. We hypothesized that nitrosative stress in the upper airway might play a role in cough hypersensitivity by causing neurochemical abnormalities.

METHODS

Fifty-one patients with unexplained chronic cough and 27 controls were enrolled. A capsaicin cough provocation test was performed to determine cough sensitivity. Nitrosative stress in the upper airway was assessed by quantifying 3-nitrotyrosine (3-NT) immunostaining in nasal epithelial cells (NECs) and measuring nasal nitric oxide (nNO). The effect of NO on airway epithelium was investigated by measuring the levels of substance P (SP) in nasal lavage fluid and evaluating SP expression in airway epithelial cells.

RESULTS

Based on the results of the capsaicin test, patients were divided into two groups: a cough hypersensitivity (CHS) group and a normal cough sensitivity (NCS) group. The levels of 3-NT immunoreactivity in NECs were significantly higher in CHS (49 ± 2.9%) than in NCS (27 ± 3.3%) and controls (12 ± 1.6%), a pattern that was also reflected in the values of nNO (350 ± 43, 215 ± 23, and 138 ± 23 ppb in CHS, NCS, and controls, respectively). SP concentration was also elevated in nasal lavage fluids from CHS (746 ± 28 pg/mL) compared with that from NCS (624 ± 40 pg/mL) and controls (526 ± 41 pg/mL). SP expression in airway epithelial cells was greatly enhanced by exposure to NO donor, which was attenuated by pretreatment with either NO scavenger or NO synthase inhibitor.

CONCLUSION

Increased nitrosative stress in the upper airway may play a role in the pathogenesis of unexplained chronic cough with CHS through enhanced secretion of SP.

Polymorphisms in RYBP and AOAH genes are associated with chronic rhinosinusitis in a Chinese population: a replication study

Background

The development of CRS is believed to be the result of combined interactions between the genetic background of the affected subject and environmental factors.

Objectives

To replicate and extend our recent findings from genetic association studies in chronic rhinosinusitis (CRS) performed in a Canadian Caucasian population in a Chinese population.

Methods

In a case-control replication study, DNA samples were obtained from CRS with (n = 306; CRSwNP) and without (n = 332; CRSsNP) nasal polyps, and controls (n = 315) in a Chinese population. A total of forty-nine single nucleotide polymorphisms (SNPs) selected from previous identified SNPs associated with CRS in Canadian population, and SNPs from the CHB HapMap dataset were individually genotyped.

Results

We identified two SNPs respectively in RYBP (rs4532099, p = 2.15E–06, OR = 2.59) and AOAH (rs4504543, p = 0.0001152, OR = 0.58) significantly associated with whole CRS cohort. Subgroup analysis for the presence of nasal polyps (CRSwNP and CRSsNP) displayed significant association in CRSwNP cohorts regarding to one SNP in RYBP (P = 3.24^E–006, OR = 2.76). Evidence of association in the CRSsNP groups in terms of 2 SNPs (AOAH_rs4504543 and RYBP_rs4532099) was detected as well. Stratifying analysis by gender demonstrated that none of the selected SNPs were associated with CRSwNP as well as CRSsNP. Meanwhile 3 SNPs (IL1A_rs17561, P = 0.005778; IL1A_rs1800587, P = 0.009561; IRAK4_rs4251513, P = 0.03837) were associated with serum total IgE level.

Conclusions

These genes are biologically plausible, with roles in regulation of transcription (RYBP) and inflammatory response (AOAH). The present data suggests the potential common genetic basis in the development of CRS in Chinese and Caucasian population.

Genetics of rhinosinusitis

Suggestion for a potential genetic basis to chronic rhinosinusitis (CRS) is afforded by degree of inheritability suggested from family and twin studies, existence of CRS in simple mendelian diseases, and development of sinusitis as part of the phenotype of certain gene "knockout" murine models. Genetic association studies are expected to identify novel genes associated with CRS and suggest novel mechanisms implicated in disease development. Although these studies are subject to methodologic difficulties, associations of CRS and polymorphisms in more than 30 genes have been published, with single nucleotide polymorphisms in 3 (IL1A, TNFA, AOAH) replicated. While the individual risk conferred by these single nucleotide polymorphisms remains modest, taken as a group, they suggest an important implication of pathways of innate immune recognition and in regulation of downstream signaling in the development of CRS. In a demonstration of these techniques' potential to identify new targets for research, the authors present a functional investigation of LAMB1, the top-rated gene from a pooling-based genome-wide association study of CRS. Upregulation of gene expression in LAMB1 and associated laminin genes in primary epithelial cells from CRS patients implicates the extracellular matrix in development of CRS and offers a new avenue for further study.