Increased prevalence of interleukin-1 receptor antagonist gene polymorphism in patients with chronic rhinosinusitis

Low Diversity and Instability of the Sinus Microbiota over Time in Adults with Cystic Fibrosis

Chronic rhinosinusitis (CRS) is a common, yet underreported and understudied manifestation of upper respiratory disease in people with cystic fibrosis (CF). Recently developed standard of care guidelines for the management of CF CRS suggest treatment of upper airway disease may ameliorate lower airway disease. We sought to determine whether changes to sinus microbial community diversity and specific taxa known to cause CF lung disease are associated with increased respiratory disease and inflammation. We performed 16S rRNA gene sequencing, supplemented with cytokine analyses, microscopy, and bacterial culturing, on samples from the sinuses of 27 adults with CF CRS. At each study visit, participants underwent endoscopic paranasal sinus sampling and clinical evaluation. We identified key drivers of microbial community composition and evaluated relationships between diversity and taxa with disease outcomes and inflammation. Sinus community diversity was low, and the composition was unstable, with many participants exhibiting alternating dominance between Pseudomonas aeruginosa and staphylococci over time. Despite a tendency for dominance by these two taxa, communities were highly individualized and shifted composition during exacerbation of sinus disease symptoms. Exacerbations were also associated with communities dominated by Staphylococcus spp. Reduced microbial community diversity was linked to worse sinus disease and the inflammatory status of the sinuses (including increased interleukin-1β [IL-1β]). Increased IL-1β was also linked to worse sinus endoscopic appearance, and other cytokines were linked to microbial community dynamics. Our work revealed previously unknown instability of sinus microbial communities and a link between inflammation, lack of microbial community diversity, and worse sinus disease. IMPORTANCE Together with prior sinus microbiota studies of adults with CF chronic rhinosinusitis, our study underscores similarities between sinus and lower respiratory tract microbial community structures in CF. We show how community structure tracks with inflammation and several disease measures. This work strongly suggests that clinical management of CRS could be leveraged to improve overall respiratory health in CF. Our work implicates elevated IL-1β in reduced microbiota diversity and worse sinus disease in CF CRS, suggesting applications for existing therapies targeting IL-1β. Finally, the widespread use of highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy has led to less frequent availability of spontaneous expectorated sputum for microbiological surveillance of lung infections. A better understanding of CF sinus microbiology could provide a much-needed alternative site for monitoring respiratory infection status by important CF pathogens.

Cytokine Signature and Involvement in Chronic Rhinosinusitis with Nasal Polyps

Cytokines are well known to play a central role in chronic rhinosinusitis with nasal polyps (CRSwNP), particularly in maintenance of the inflammatory response and the recruitment of eosinophils. The pathophysiological concepts concerning the involvement of inflammatory cytokines in CRSwNP have gradually evolved. Although the Th2 cytokines environment associated with an eosinophilic infiltration has retained a central role in the genesis of polyps, the role of other cytokine subpopulations has also and more recently been detailed, leading to a specific and complex signature in CRSwNP. The purpose of this review is to summarize the current state of knowledge about the cytokine signature in CRSwNP, the role of cytokines in the pathogenesis of this disease and in the intercellular dialog between epithelial cells, fibroblasts and inflammatory cells. Knowledge of this precise cytokine signature in CRSwNP is fundamental in the perspective of potential targeting biotherapies.

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.

IL-1RN VNTR, IL-2(-330), and IL-4 VNTR gene polymorphisms in patients with chronic rhinosinusitis with sinonasal polyposis

Background/aim

Sinonasal polyposis is a complex chronic disease displaying contributions from multiple genetic and environmental factors. In this study, we analyzed possible genetic factors that increase susceptibility to this widespread inflammatory disease.

Materials and methods

A total of 176 adult patients, including 78 patients with sinonasal polyposis and 98 healthy controls, were analyzed for IL-1RN VNTR, IL-2(-330), and IL-4 VNTR gene polymorphisms using polymerase chain reaction and enzyme restriction.

Results

IL-1RN and IL-4 VNTR polymorphisms were notably associated with sinonasal polyposis (P = 0.0001 and P = 0.036, respectively); however, regarding the IL-2(-330) gene polymorphism, no significant difference was shown between the patient and control groups (P = 0.235).

Conclusions

Our study indicates that the RN2 allele of IL-1RN and the RP1 allele of IL-4 might be risk factors for developing sinonasal polyposis.

Association of IL-1 gene polymorphisms with chronic rhinosinusitis with and without nasal polyp

Background

Chronic rhinosinusitis (CRS) is one of the most common and complex chronic inflammatory disease of sinonasal mucosa. Even though the pathogenesis of CRS is multifactorial and still unclear, the role of cytokines especially interleukin-1 (IL-1) is being investigated worldwide in different population because of varying results obtained.

Objective

To study the association of IL-1 (A and B) gene polymorphisms with chronic rhinosinusitis with nasal polyp (CRSwNP) and without nasal polyp (CRSsNP), and other factors related.

Methods

This is a case-controlled study which include a total of 138 subjects recruited from Otorhinolaryngology-Head and Neck Surgery clinic in Hospital Universiti Sains Malaysia. Genotyping of the IL-1A (+4845G, +4845T) and IL-1B (−511C, −511T) were performed with restriction fragment length polymorphism analysis.

Results

There was a statistical significant association between IL-1B (−511C, −511T) polymorphism with CRSwNP and CRSsNP (p < 0.001). The CT genotype of IL-1B was markedly increased in CRSwNP subjects (52.2%). However, there was no significant association found between IL-1A (+4845G, +4845T) with CRSwNP and CRSsNP (p = 0.093). No association was found in factors related to CRS, which included asthma, atopy, allergy, aspirin sensitivity, and family history of nasal polyp (p value of 0.382, 0.382, 0.144, >0.95, and 0.254, respectively).

Conclusion

This study indicates an association of IL-1B (−511C, −511T) polymorphism with CRSwNP and CRSsNP in our population, hence there is a possibility of IL-1B involvement in modulating pathogenesis of CRS. There was no significant association of IL-1A (+4845G, +4845T) polymorphism with CRSwNP and CRSsNP, and other factors related.

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.

The Allele 2 of the VNTR Polymorphism in the Gene That Encodes a Natural Inhibitor of IL-1β, IL-1RA Is Favorably Associated With Chronic Otitis Media

Objectives

Chronic otitis media (COM) is followed by irreversible tissue damage and destruction of the middle ear structures, with the possibility of complications under the maintenance of inflammation. Inflammatory mediators such as cytokines play a crucial role in the initial stage of inflammation. The aim of this study was to evaluate the association of the polymorphisms in two innate immunity/inflammation cascade genes from interleukin-1 (IL-1) gene cluster with COM with regard to cholesteatoma.

Methods

In the cross-sectional case-control study, DNA samples were collected from 189 patients with COM and 119 controls from a population of Serbia. The +3953 C/T (rs1143634), TaqI polymorphism in interleukin-1 beta (IL-1β) gene and 86 bp variable number tandem repeat (VNTR, rs2234663) polymorphism in the IL-1 receptor antagonist (IL-1RA) gene were analyzed by polymerase chain reaction.

Results

The IL-1β TaqI polymorphism was not significantly different in patients compared with the control group. The significant difference between patients and controls was observed for both, genotype and allele frequencies of IL-1RA VNTR polymorphism (chi-square P<0.01). We found that carriers of IL-1RA allele 2 (odds ratio, 0.47; 95% confidence interval, 0.29 to 0.76; P=0.004) have a favorable association with COM, using multivariate logistic analysis that included both polymorphisms, age and sex. The IL-1RA allele frequency distribution was significantly different with regard to cholesteatoma.

Conclusion

The carriers of allele 2 of VNTR IL-1RA polymorphism had a decreased odds ratio for COM, which is in agreement with findings in other inflammatory disease and its previous association with higher IL-1RA levels. Possible down-regulation of IL-1 mediated proinflammatory signaling pathways via IL-1RA in COM as well as results of our study should be further investigated and replicated.

Chronic rhinosinusitis in Asia

Chronic rhinosinusitis (CRS), although possibly overdiagnosed, is associated with a high burden of disease and is often difficult to treat in those truly affected. Recent research has demonstrated that inflammatory signatures of CRS vary around the world, with less eosinophilic and more neutrophilic inflammation found in Asia compared with Europe and North America. Although in the Western world about 80% of nasal polyps carry a type 2 signature, this might be between 20% and 60% in China and Korea or Thailand, respectively. These differences are associated with a lower asthma comorbidity and risk of disease recurrence after surgery in the Asian population. As a hallmark of severe type 2 inflammation, eosinophils attacking Staphylococcus aureus at the epithelial barrier have been described recently; they also can be found in a subgroup of Asian patients with nasal polyps. Furthermore, the percentage of type 2 signature disease in patients with CRS is dramatically increasing ("eosinophilic shift") in several Asian countries over the last 20 years. Establishing an accurate diagnosis along with considering the current and shifting patterns of inflammation seen in Asia will enable more effective selection of appropriate pharmacotherapy, surgical therapy, and eventually biotherapy. Determining the causes and pathophysiology for this eosinophilic shift will require additional research.

TNF-α and IL-1 β Cytokine Gene Polymorphism in Patients with Nasal Polyposis

Objective

Nasal Polyp (NP) is a benign mass of the paranasal sinuses that protrudes into the nasal cavity. The exact underlying pathogenesis is not known. In this study we aimed to determine the genetic susceptibility of NP formation in relation to TNF-α-308 and IL-1β-511 promoter region gene polymorphisms.

Methods

A total of 71 patients with NP with asthma (n=21) or without asthma (n=50) were taken as the study group, and 91 healthy volunteers were taken as the control group. Blood was gathered into EDTA-containing tubes, and patient DNA was extracted. The polymorphisms of the IL-β and TNF-α cytokine genes were analyzed using real time polymerase chain reaction.

Results

The GG genotype in the TNF-α-308 region and the CC genotype in the IL-1β-511 region were found to be risk factors for NP formation (OR: 9.2, p=0.007 and OR: 33.3, p=0.001, respectively). Regarding allelic frequencies, the G allele at the TNF-α-308 promoter region was a risk factor for NP formation (OR: 6.06, p<0.001).

Conclusion

TNF-α GG genotype in the -308 promoter region and the IL-1β CC genotype in the -511 region are genetic risk factors for NP formation.

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.

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.

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

CONTEXT

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

OBJECTIVE

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

DATA SOURCES

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

CONCLUSIONS

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

Association of IL1β and IL4 gene polymorphisms with nasal polyps in a Polish population

Imbalance between proinflammatory and anti-inflammatory cytokines may regulate the inflammatory reaction in the nasal polyps. Polymorphisms in the regulatory regions of the cytokines genes may influence their expression. The aim of this study was to investigate the relationship between an IL-1β and IL-4 promoter polymorphisms and nasal polyps. The C-511T promoter polymorphism of the IL-1β gene and C-590T promoter polymorphism of the IL-4 gene were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis in 208 Polish patients with nasal polyps and 200 healthy Polish subjects. The risk of susceptibility to NP was significantly higher in patients with NP who had -511 T/T genotype of IL1β than in controls (OR 3.07; 95 % CI 1.18-7.99). No statistically significant differences were found between NP patients and the control group with regard to genotype distribution and allele frequencies of C/T polymorphism of IL4 gene. Our study demonstrated that the TT genotype for C-511T mutation associated with the risk of developing NP in a Polish population.

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.

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.

Technical advances in rhinologic basic science research

Chronic rhinosinusitis (CRS) is the single most common self-reported chronic health condition in the United States and is estimated to affect 16% of the adult population annually. Despite the prevalence of this disease, there still exists an incomplete understanding of CRS pathophysiology. In this review, the authors highlight technological advances in rhinology: real-time polymerase chain reaction, epithelial cell culture, flow cytometry, genomics/single-nucleotide polymorphism detection, microarrays, and genetic/nongenetic animal models of sinusitis. The purpose of this review is to describe these methodologies and their contributions toward achieving a better understanding of CRS.

Genetic polymorphisms in chronic hyperplastic sinusitis with nasal polyposis

OBJECTIVES/HYPOTHESIS

Although many proinflammatory cytokines have been identified in nasal polyp tissue, the initial trigger that causes this inflammation characterized by edema, lymphocytosis, and eosinophilia, is still unknown. The purpose of the present study is to identify the presence of genetic polymorphisms in proinflammatory, anti-inflammatory, and chemokine genes that might contribute to genetic susceptibility to chronic hyperplastic sinusitis with nasal polyposis (CHSwNP).

STUDY DESIGN

Case control study.

METHODS

Buccal swabs were taken from the left and right oral mucosal surfaces from 179 patients with CHSwNP and 153 nonpolyposis controls with the Purgene DNA purification protocol (Gentra). Genotyping assays for cytokine gene loci were performed on 14 cytokine genes using the iPlex Gold and the Mass Array Compact system (Sequenom, San Diego, CA). Tests of Hardy-Weinberg equilibrium proportions were performed separately in the cases and controls. Tests for evidence of association between alleles at each single-nucleotide polymorphism (SNP) and case-control status were performed using unconditional logistic regression.

RESULTS

The frequency of the A allele in a SNP located in tumor necrosis factor (TNF)-alpha (rs1800629) is significantly different in patients with nasal polyposis versus controls without nasal polyposis, 18.6% and 11.5%, respectively with an individuals' odds of susceptibility to nasal polyps increasing almost two-fold (odds ratio, 1.86; confidence interval, 1.4-3.09) given at least one copy of the A allele at this SNP. All other cytokine gene polymorphisms of both inflammatory, anti-inflammatory, and chemokine genes were not statistically different between the two groups.

CONCLUSIONS

TNF-alpha-308, a SNP in the promoter region of this cytokine gene is associated with increased odds of developing nasal polyposis. TNF-alpha is a potent immuno-mediator and proinflammatory cytokine that has been implicated in the pathogenesis of a large number of human diseases. The location of this gene on the short arm of chromosome 6, with the major histocompatibility complex genes and complement, has raised the probability that polymorphism within this locus may contribute to a genetic association of this region of the genome with a wide variety of infectious and autoimmune diseases.

Evidence of Association of Interleukin-1 Receptor-Like 1 Gene Polymorphisms with Chronic Rhinosinusitis

Background

Chronic rhinosinusitis (CRS) is a common complex respiratory disease, with a potential genetic component to its development. The protein encoded by the Interleukin-1 receptor-like 1 (IL1RL1) gene is an important effector molecule of T-helper type 2 responses and may potentially be involved in the persistent inflammatory process observed in CRS. We investigated whether certain polymorphisms in the IL1RL1 gene are differentially present in patients with surgery-unresponsive CRS and in control subjects.

Methods

DNA extracted from an existing population of 206 adult patients with surgery-unresponsive CRS and 196 postal-code-matched controls was used. A set of 15 tagging single nucleotide polymorphisms (SNPs) was selected from the HapMap data set and genotyped. DNA sequencing was performed in a subgroup of 15 CRS patients.

Results

Statistically significant allelic associations with CRS were noted for 5 SNPs (rs10204137, p = 0.04; rs10208293, p = 0.03; rs13431828, p = 0.008; rs2160203, p = 0.03, and rs4988957, p = 0.03). The analysis showed a consistent significant protective effect against CRS for all the SNPs, yielding an odds ratio (OR) ranging from 0.56 to 0.72. The loci rs13431828 showed the highest association with CRS (p = 0.008; OR = 0.56; 95% CI, 0.36–0.86). A subanalysis revealed that the observed associations were stronger among patients with more severe disease. Sequencing identified five additional known nonsynonymous coding SNPs in linkage disequilibrium with genotyped SNPs.

Conclusion

Pending replication of these results, this study suggests that polymorphisms within the IL1RL1 gene may be associated with CRS, conferring a protective effect, particularly among those with severe disease.

Identification of susceptibility genes for complex diseases using pooling-based genome-wide association scans

The success of genome-wide association studies (GWAS) to identify risk loci of complex diseases is now well-established. One persistent major hurdle is the cost of those studies, which make them beyond the reach of most research groups. Performing GWAS on pools of DNA samples may be an effective strategy to reduce the costs of these studies. In this study, we performed pooling-based GWAS with more than 550,000 SNPs in two case-control cohorts consisting of patients with Type II diabetes (T2DM) and with chronic rhinosinusitis (CRS). In the T2DM study, the results of the pooling experiment were compared to individual genotypes obtained from a previously published GWAS. TCF7L2 and HHEX SNPs associated with T2DM by the traditional GWAS were among the top ranked SNPs in the pooling experiment. This dataset was also used to refine the best strategy to correctly identify SNPs that will remain significant based on individual genotyping. In the CRS study, the top hits from the pooling-based GWAS located within ten kilobases of known genes were validated by individual genotyping of 1,536 SNPs. Forty-one percent (598 out of the 1,457 SNPs that passed quality control) were associated with CRS at a nominal P value of 0.05, confirming the potential of pooling-based GWAS to identify SNPs that differ in allele frequencies between two groups of subjects. Overall, our results demonstrate that a pooling experiment on high-density genotyping arrays can accurately determine the minor allelic frequency as compared to individual genotyping and produce a list of top ranked SNPs that captures genuine allelic differences between a group of cases and controls. The low cost associated with a pooling-based GWAS clearly justifies its use in screening for genetic determinants of complex diseases.

A genomewide screen for chronic rhinosinusitis genes identifies a locus on chromosome 7q

OBJECTIVE/HYPOTHESIS

Chronic rhinosinusitis (CRS) is an important public health problem with substantial impact on patient quality of life and health care costs. We hypothesized that genetic variation may be one factor that affects this disease.

STUDY DESIGN

Identification of genetic variation underlying susceptibility to CRS using linkage analysis in a founder population.

METHODS

We studied a religious isolate that practices a communal lifestyle and shares common environmental exposures. Using physical examination, medical interviews, and a review of medical records, we identified eight individuals with CRS of 291 screened. These eight individuals were related to each other in a single 60 member, nine generation pedigree. A genome-wide screen for loci influencing susceptibility to CRS using 1123 genome-wide markers was conducted.

RESULTS

The largest linkage peak (P = .0023; 127.15 cM, equivalent to limit of detection = 2.01) was on chromosome 7q31.1-7q32.1, 7q31 (127.15 cM; 1-limit of detection support region: 115-135 cM) and included the CFTR locus. Genotyping of 38 mutations in the CFTR gene did not reveal variation accounting for this linkage signal.

CONCLUSIONS

Understanding the genes involved in CRS may lead to improvements in its diagnosis and treatment. Our results represent the first genome-wide screen for CRS and suggest that a locus on 7q31.1-7q32.1 influences disease susceptibility. This may be the CFTR gene or another nearby locus.

Lack of association of Clara cell 10-kDa protein gene variant with chronic rhinosinusitis in a Chinese Han population

BACKGROUND

Clara cell 10-kDa protein (CC10) is an anti-inflammatory molecule and has been implicated in the involvement of the pathogenesis of asthma and chronic rhinosinusitis (CRS). A single nucleotide polymorphism (SNP) in CC10 gene (A + 38G) was previously shown to be associated with asthma and plasma CC10 levels. The purpose of this study is to examine whether there is an association between the CC10 A + 38G SNP, plasma CC10 levels, and CRS in a central Chinese population of Han nationality.

METHODS

The CC10 A + 38G SNP was analyzed by means of polymerase chain reaction with restriction fragment length polymorphism and plasma CC10 levels were measured using enzyme-linked immunosorbent assay in 220 patients with CRS (90 patients with nasal polyps [NPs] and 130 patients without NPs) and 180 healthy control subjects. Among 220 patients with CRS, 108 patients were atopic subjects. Severity of disease was determined by coronal computed tomography (CT) scan in CRS patients, which was graded according to Lund and Mackay.

RESULTS

The frequency of the A allele was 0.394, which was not significantly higher than the frequencies of other reported ethnic groups except for German. No association between the CC10 A + 38G SNP and CRS, any subgroup of CRS, or CRS severity could be found. Although subjects carrying the AA genotype had a significantly lower plasma CC10 concentration than those carrying the GG and GA genotypes in both CRS and control groups (p = 0.00 for all), no association was found between the plasma CC10 levels and CRS phenotype.

CONCLUSION

The CC10 A + 38G SNP may not exert a substantial influence on the development of CRS in the Chinese Han population.

Influence of leukotriene gene polymorphisms on chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is increasingly viewed as an inflammatory condition of the sinonasal mucosa interacting with bacteria and/or fungi. However, factors conferring susceptibility to disease remain unknown. Advances in genomics offer powerful tools to explore this disorder. The goal of this study was to evaluate the effect of single nucleotide polymorphisms (SNP) on CRS in a panel of genes related to cysteinyl leukotriene metabolism.

METHODS

Severe cases of CRS and postal code match controls were recruited prospectively. A total of 206 cases and 200 controls were available for the present study. Using a candidate gene approach, five genes related to cysteinyl leukotriene metabolism were assessed. For each gene, we selected the maximally informative set of common SNPs (tagSNPs) using the European-derived (CEU) HapMap dataset. These SNPs are in arachidonate 5-lipoxygenase (ALOX5), arachidonate 5-lipoxygenase-activating protein (ALOX5AP), leukotriene C4 synthase (LTC4S), cysteinyl leukotriene receptor 1 (CYSLTR1) and cysteinyl leukotriene receptor 2 (CYSLTR2) genes.

RESULTS

A total of 59 SNPs were genotyped to capture the common genetic variations within these genes. Three SNPs located within the ALOX5, CYSLTR1 and ALOX5AP genes reached the nominal p-value threshold (p < 0.05) for association with CRS. However, none of these SNPs resist multiple testing adjustment.

CONCLUSION

While these initial results do not support that polymorphsims in genes assessed involved in the leukotriene pathways are contributing to the pathogenesis of CRS, this initial study was not powered to detect polymorphisms with relative risk of 2.0 or less, where we could expect many gene effects for complex diseases to occur. Thus, despite this lack of significant association noted in this study, we believe that validation with external populations and the use of better-powered studies in the future may allow more conclusive findings.

Interleukin-1beta exon 5 and interleukin-1 receptor antagonist in children with immune thrombocytopenic purpura

Immune thrombocytopenic purpura (ITP) is associated with cytokine response and dysregulation of the cytokine network. We investigated the polymorphisms of interleukin (IL)-1beta exon 5 and IL-1 receptor antagonist (IL-1 Ra) in 50 children with acute ITP, in 30 children with chronic ITP, and in 100 healthy children by polymerase chain reaction-based restriction analysis. No significant differences in either genotype distribution (P=0.52) or allelic frequencies (P=0.70) were found among children with acute ITP, chronic ITP, or controls for IL-1beta exon 5. However, significant differences in genotype distribution (P=0.02) and the allelic frequencies (P=0.007) were found among children with acute ITP, chronic ITP, and controls for IL-1 Ra. We found that the IL-1 Ra but not IL-1beta gene polymorphism was associated with childhood ITP. This finding suggests that the IL-1 Ra gene polymorphism is implicated in the pathophysiology of childhood ITP.