Polymorphisms in the IL4, IL4RA, and FCERIB genes and asthma severity

Targeting IL-13 and IL-4 in Asthma: Therapeutic Implications on Airway Remodeling in Severe Asthma

Asthma is a chronic respiratory disorder affecting individuals across all age groups. It is characterized by airway inflammation and remodeling and leads to progressive airflow restriction. While corticosteroids remain a mainstay therapy, their efficacy is limited in severe asthma due to genetic and epigenetic alterations, as well as elevated pro-inflammatory cytokines interleukin-4 (IL-4), interleukin-13 (IL-13), and interleukin-5 (IL-5), which drive structural airway changes including subepithelial fibrosis, smooth muscle hypertrophy, and goblet cell hyperplasia. This underscores the critical need for biologically targeted therapies. This review systematically examines the roles of IL-4 and IL-13, key drivers of type-2 inflammation, in airway remodeling and their potential as therapeutic targets. IL-4 orchestrates eosinophil recruitment, immunoglobulin class switching, and Th2 differentiation, whereas IL-13 directly modulates structural cells, including fibroblasts and epithelial cells, to promote mucus hypersecretion and extracellular matrix (ECM) deposition. Despite shared signaling pathways, IL-13 emerges as the dominant cytokine in remodeling processes including mucus hypersecretion, fibrosis and smooth muscle hypertrophy. While IL-4 primarily amplifies inflammatory cascades by driving IgE switching, promoting Th2 cell polarization that sustain cytokine release, and inducing chemokines to recruit eosinophils. In steroid-resistant severe asthma, biologics targeting IL-4/IL-13 show promise in reducing exacerbations and eosinophilic inflammation. However, their capacity to reverse established remodeling remains inconsistent, as clinical trials prioritize inflammatory biomarkers over long-term structural outcomes. This synthesis highlights critical gaps in understanding the durability of IL-4/IL-13 inhibition on airway structure and advocates for therapies combining biologics with remodeling-specific strategies. Through the integration of mechanistic insights and clinical evidence, this review emphasizes the need for long-term studies utilizing advanced imaging, histopathological techniques, and patient-reported outcomes to evaluate how IL-4/IL-13-targeted therapies alter airway remodeling and symptom burden, thereby informing more effective treatment approaches for severe, steroid-resistant asthma.

The burden of severe asthma in sub-Saharan Africa: Findings from the African Severe Asthma Project

Background

Severe asthma is associated with high morbidity, mortality, and health care utilization, but its burden in Africa is unknown.

Objective

We sought to determine the burden (prevalence, mortality, and activity and work impairment) of severe asthma in 3 countries in East Africa: Uganda, Kenya, and Ethiopia.

Methods

Using the American Thoracic Society/European Respiratory Society case definition of severe asthma, we analyzed for the prevalence of severe asthma (requiring Global Initiative for Asthma [GINA] steps 4-5 asthma medications for the previous year to achieve control) and severe refractory asthma (remains uncontrolled despite treatment with GINA steps 4-5 asthma medications) in a cohort of 1086 asthma patients who had been in care for 12 months and had received all GINA-recommended medications. Asthma control was assessed by the asthma control questionnaire (ACQ).

Results

Overall, the prevalence of severe asthma and severe refractory asthma was 25.6% (95% confidence interval [CI], 23.1-28.3) and 4.6% (95% CI, 3.5-6.0), respectively. Patients with severe asthma were (nonsevere vs severe vs severe refractory) older (39, 42, 45 years, P = .011), had high skin prick test reactivity (67.1%, 76.0%, 76.0%, P = .004), had lower forced expiratory volume in 1 second percentage (81%, 61%, 55.5%, P < .001), had lower quality of life score (129, 127 vs 121, P < .001), and had higher activity impairment (10%, 30%, 50%, P < .001). Factors independently associated with severe asthma were hypertension comorbidity; adjusted odds ratio 2.21 (1.10-4.47), P = .027, high bronchial hyperresponsiveness questionnaire score; adjusted odds ratio 2.16 (1.01-4.61), P = .047 and higher ACQ score at baseline 2.80 (1.55-5.08), P = .001.

Conclusion

The prevalence of severe asthma in Africa is high and is associated with high morbidity and poor quality of life.

Diagnostic and therapeutic value of EVs in lungs diseases and inflammation

Extracellular vesicles (EVs) are membrane-derived messengers which have been playing an important role in the inflammation and pathogenesis of lung diseases. EVs contain varieties of DNA, RNA, and membrane receptors through which they work as a delivery system for bioactive molecules as well as intracellular communicators. EV signaling mediates tumor progression and metastasis. EVs are linked with many diseases and perform a diagnostic role in lung injury and inflammation so are used to diagnose the severity of diseases. EVs containing a variety of biomolecules communicate with the recipient cells during pathophysiological mechanisms thereby acquiring the attention of clinicians toward the diagnostic and therapeutic potential of EVs in different lung diseases. In this review, we summarize the role of EVs in inflammation with an emphasis on their potential as a novel candidate in the diagnostics and therapeutics of chronic obstructive pulmonary disease, asthma, and sarcoidosis.

Asthma is associated with a lower incidence of metastatic colorectal cancer in a US patient cohort

In previous pre-clinical studies, we examined the contribution of interleukin 4 receptor (IL4R) signaling in the progression and metastasis of colorectal cancer (CRC). Aberrant activation of this receptor can result in atopic diseases such as asthma. We hypothesized that further evidence for the contribution of excessive IL4R being associated with CRC progression could be seen in medical records, and specifically that chronic asthma patients were more likely to be diagnosed with metastatic CRC. To test this hypothesis, we took advantage of the Synthetic Derivative, a resource developed at Vanderbilt University Medical Center that hosts de-identified data taken from the electronic medical record. We developed search protocols that produced retrospective cohorts of invasive CRC patients and cancer-free equivalents. In comparing 787 metastatic CRC patients to 238 non-metastatic patients, we actually found significantly fewer asthmatics went on to develop metastatic CRC (P=0.0381). By comparing these groups together against 1197 cancer-free patients, even fewer asthmatic patients would develop invasive CRC (P<0.0001). While these results are clearly in opposition to our original hypothesis, they still support a link between chronic asthma and metastatic CRC development. One intriguing possibility, that will be examined in the future, is whether treatment for chronic asthma may be responsible for the reduction in metastatic cancer.

The IL-4Rα Q576R polymorphism is associated with increased severity of atopic dermatitis and exaggerates allergic skin inflammation in mice

BACKGROUND

Atopic dermatitis (AD) is characterized by TH2-dominated skin inflammation and systemic response to cutaneously encountered antigens. The TH2 cytokines IL-4 and IL-13 play a critical role in the pathogenesis of AD. The Q576->R576 polymorphism in the IL-4 receptor alpha (IL-4Rα) chain common to IL-4 and IL-13 receptors alters IL-4 signaling and is associated with asthma severity.

OBJECTIVE

We sought to investigate whether the IL-4Rα R576 polymorphism is associated with AD severity and exaggerates allergic skin inflammation in mice.

METHODS

Nighttime itching interfering with sleep, Rajka-Langeland, and Eczema Area and Severity Index scores were used to assess AD severity. Allergic skin inflammation following epicutaneous sensitization of mice 1 or 2 IL-4Rα R576 alleles (QR and RR) and IL-4Rα Q576 (QQ) controls was assessed by flow cytometric analysis of cells and quantitative RT-PCR analysis of cytokines in skin.

RESULTS

The frequency of nighttime itching in 190 asthmatic inner-city children with AD, as well as Rajka-Langeland and Eczema Area and Severity Index scores in 1116 White patients with AD enrolled in the Atopic Dermatitis Research Network, was higher in subjects with the IL-4Rα R576 polymorphism compared with those without, with statistical significance for the Rajka-Langeland score. Following epicutaneous sensitization of mice with ovalbumin or house dust mite, skin infiltration by CD4+ cells and eosinophils, cutaneous expression of Il4 and Il13, transepidermal water loss, antigen-specific IgE antibody levels, and IL-13 secretion by antigen-stimulated splenocytes were significantly higher in RR and QR mice compared with QQ controls. Bone marrow radiation chimeras demonstrated that both hematopoietic cells and stromal cells contribute to the mutants' exaggerated allergic skin inflammation.

CONCLUSIONS

The IL-4Rα R576 polymorphism predisposes to more severe AD and increases allergic skin inflammation in mice.

IL-4 receptor alpha signaling alters oral food challenge and immunotherapy outcomes in mice

BACKGROUND

Food allergy diagnosis and management causes a number of social and emotional challenges for individuals with food allergies and their caregivers. This has led to increased interest in developing approaches to accurately predict food allergy diagnosis, severity of food allergic reactions, and treatment outcomes. However, the utility of these approaches is somewhat conflicting.

OBJECTIVE

We sought to develop and utilize a murine model that mimics the disease course of food allergy diagnosis and treatment in humans and to identify biomarkers that predict reactivity during food challenge (FC) and responsiveness during oral immunotherapy (OIT) and how these outcomes are modified by genetics.

METHODS

Skin-sensitized intestinal IL-9 transgenic (IL9Tg) and IL9Tg mice backcrossed onto the IL-4RαY709F background received a single intragastric exposure of egg antigen (ovalbumin), underwent oral FC and OIT; food allergy severity, mast cell activation, and ovalbumin-specific IgE levels were examined to determine the predictability of these outcomes in determining reactivity and treatment outcomes.

RESULTS

Subcutaneous sensitization and a single intragastric allergen challenge of egg antigen to BALB/c IL9Tg mice and Il4raY709F IL9Tg induced a food allergic reaction. Enhanced IL-4Rα signaling altered the symptoms induced by the first oral exposure, decreased the cumulative antigen dose, increased the severity of reaction during oral FC, and altered the frequency of adverse events and OIT outcomes. Biomarkers after first oral exposure indicated that only the severity of the initial reaction significantly correlated with cumulative dose of oral FC.

CONCLUSION

Collectively, these data indicate that single nucleotide polymorphisms in IL-4Rα can alter clinical symptoms of food allergic reactions, severity, and reactive dose during FC and OIT, and that severity of first reaction can predict the likelihood of reaction during FC in mice with IL-4Rα gain of function.

Polymorphisms in the interleukin 4 promoter -589C/T gene and the risk of asthma: a systematic review and meta-analysis

BACKGROUND

To identify the association between polymorphisms in the interleukin 4 (IL-4) promoter -589C/T gene and the risk of asthma.

METHODS

The databases of PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang, Chongqing VIP (CQVIP), and Chinese Biomedical Literature (CBM) were searched and appropriate journal articles on the association between polymorphisms in the IL-4 promoter -589C/T gene and the risk of asthma were retrieved from establishment of the database to April 2021. All relevant randomized controlled trials (RCTs) were included, to the exclusion of duplicate publications, studies with no whole composition, imperfect information or inability to extract data, animal experiments and reviews, and systematic reviews. The software Review manager 5.3 was used to analyze the data.

RESULTS

Literature search led to retrieving of 16 publications containing 3181 cases and 3786 controls. The results show that CT, CC, and T gene polymorphisms were risk factors for asthma [odds ratio (OR) =1.05, 95% confidence interval (CI): 0.89-1.24; OR =1.04, 95% CI: 0.85-1.27; OR =1.98, 95% CI: 1.54-2.53]. Ethnic subgroup analysis showed that genotype CT was associated with the risk of asthma in the Asian population (OR =1.75, 95% CI: 1.01-3.05).

DISCUSSION

Through the study of IL-4 (C-590T) gene polymorphism, it was found that CT, TT, and T gene polymorphism were risk factors for asthma, and the results suggested that this locus polymorphism was related to the risk of asthma. The results of subgroup analysis showed that CC and T gene polymorphisms were risk factors for asthma. Thus, IL-4(C-590T) may be the susceptibility gene of asthma.

Potential Metabolic Biomarkers in Adult Asthmatics

Asthma is the most common chronic airway inflammation, with multiple phenotypes caused by complicated interactions of genetic, epigenetic, and environmental factors. To date, various determinants have been suggested for asthma pathogenesis by a new technology termed omics, including genomics, transcriptomics, proteomics, and metabolomics. In particular, the systematic analysis of all metabolites in a biological system, such as carbohydrates, amino acids, and lipids, has helped identify a novel pathway related to complex diseases. These metabolites are involved in the regulation of hypermethylation, response to hypoxia, and immune reactions in the pathogenesis of asthma. Among them, lipid metabolism has been suggested to be related to lung dysfunction in mild-to-moderate asthma. Sphingolipid metabolites are an important mediator contributing to airway inflammation in obese asthma and aspirin-exacerbated respiratory disease. Although how these molecular variants impact the disease has not been completely determined, identification of new causative factors may possibly lead to more-personalized and precise pathway-specific approaches for better diagnosis and treatment of asthma. In this review, perspectives of metabolites related to asthma and clinical implications have been highlighted according to various phenotypes.

A novel nanogel loaded with chitosan decorated bilosomes for transdermal delivery of terbutaline sulfate: artificial neural network optimization, in vitro characterization and in vivo evaluation

The objective of the present work was to formulate, optimize, and evaluate transdermal terbutaline sulfate (TBN)-loaded bilosomes (BLS) in gel, compared to conventional oral TBN solution and transdermal gel loaded with free TBN, aiming at evading the hepatic first-pass metabolism. A face-centered central composite design was adopted to observe the effects of different formulation variables on TBN-BLS, and artificial neural network (ANN) modeling was employed to optimize TBN-BLS. TBN-BLS were prepared by a thin film hydration method integrating soybean phosphatidylcholine and cholesterol as a lipid phase and sodium deoxycholate (SDC) as a surfactant with or without the coating of chitosan (CTS). After being subjected to physicochemical characterization, TBN-BLS were enrolled in a histopathological study and pharmacokinetic investigation in a rat model. The optimized TBN chitosan-coated bilosomes (TBN-CTS-BLS) were spherical vesicles (245.13 ± 10.23 nm) with adequate entrapment efficiency (65.25 ± 5.51%) and good permeation characteristics (340.11 ± 22.34 μg/cm²). The TBN-CTS-BLS gel formulation was well-tolerated with no inflammatory signs manifested upon histopathological evaluation. The pharmacokinetic study revealed that the optimized TBN-CTS-BLS formulation successively enhanced the bioavailability of TBN by about 2.33-fold and increased t_1/2 to about 6.21 ± 0.24 h as compared to the oral solution. These findings support the prospect use of BLS as active and safe transdermal carrier for TBN in the treatment of asthma. Graphical Abstract.

Interleukin 4 gene polymorphism (-589C/T) and the risk of asthma: a meta-analysis and met-regression based on 55 studies

BACKGROUND

Numerous investigations have previously evaluated the association of interleukin (IL) 4 gene polymorphisms and the risk of asthma, conferring inconsistent results. To resolve the incongruent outcomes yielded from different single studies, we conducted the most up-to-date meta-analysis of IL4 gene -589C/T (rs2243250) polymorphism and susceptibility to asthma.

METHODS

A systematic literature search was performed in ISI web of science, Scopus, Medline/PubMed databases prior to September 2020, and the pooled odds ratio (OR) and their corresponding 95% CI were calculated to determine the association strength.

RESULTS

Literature search led to retrieving of 49 publications (55 case-control studies) containing 9572 cases and 9881 controls. It was revealed that IL4 gene -589C/T polymorphism increased the risk of asthma across all genetic models, including dominant model (OR = 1.22), recessive model (OR = 1.17), allelic model (OR = 1.21), and TT vs. CC model (OR = 1.34), but not the CT vs. TT model. The subgroup analysis by age indicated that IL4 gene -589C/T polymorphism was significantly associated with asthma risk in both pediatrics and adults. Additionally, the subgroup analysis by ethnicity revealed significant association in Asian, American, and Europeans. Finally, subgroup analysis by East Asian and non-East Asian populations indicated significant associations.

CONCLUSIONS

The current meta-analysis revealed that IL4 gene -589C/T polymorphism was a susceptibility risk in both pediatrics and adults in the whole and different ethnic groups.

Kawasaki Disease and Allergic Diseases

Background: Kawasaki disease (KD) is an inflammatory disorder with an unknown etiology. It is the leading cause of acquired heart disease, which leads to coronary vasculitis among children. Studies of frequent manifestation of allergic diseases in children with KD have been the subject of mounting clinical interest. However, evidence supporting the association between KD and allergies has yet to be systematically reviewed. Methods: In this article, we reviewed current literature regarding the association between KD and allergic diseases. References for this review were identified through searches of PubMed, Cochrane, and Embase through the end of August 2020. Results: The results of the analyses of immune repertoire, clinical, and epidemiological studies have indicated some of the characteristics of infectious disease for KD. Although some allergic disorders, such as asthma, may be exacerbated by viral infections, allergies are typically caused by an allergen that triggers an immune response, with the potential involvement of type 2 inflammation and immune disturbances leading to tissue remodeling in genetically susceptible hosts. The effect of intravenous immunoglobulin is multi-faceted and results in a decrease in activating Fc gamma receptor IIA and an increase in anti-inflammatory eosinophils. The findings from this review demonstrate that children who have suffered from KD are more likely to have allergic rhinitis than the general population and their siblings, a condition that lasts until the age of 17. When followed up as teenagers and adults, children with KD are more likely to develop urticaria. Conclusions: This review supports that allergic diseases, such as allergic rhinitis, have been demonstrated to increase following KD. Therefore, the importance of allergic diseases in patients with KD should be emphasized in long-term care. Interventions that include strategies for managing allergies in children with KD would be beneficial.

Repeated exacerbation of asthma: An intrinsic phenotype of uncontrolled asthma

Asthma is a chronic disease of the airways affecting a large number of people across the globe. Uncontrolled asthma poses an emotional as well as the physical burden on patients and results in a great economic burden. “Exacerbation-prone phenotype” asthmatics are a cluster of patients who may suffer from more frequent and severe exacerbations than other asthmatics. Factors such as inadequate symptom control, improper adherence to medications, and incorrect use of inhalers are responsible for frequent asthma exacerbations. Caring for the patient with “exacerbation-prone asthma” needs participation from both the doctor as well as the patient. Self-management, improving knowledge about the disease, control of comorbidities, and a stepwise approach with the use of a single inhaler maintenance and reliever therapy in patients with severe asthma could help in delivering better care for the “exacerbation-prone phenotype” of asthmatics.

Preliminary analysis of single-nucleotide polymorphisms in IL-10, IL-4, and IL-4Rα genes and profile of circulating cytokines in patients with gastric Cancer

Background

Gastric Cancer is highly prevalent and deadly worldwide. In Colombia, it is the most lethal form of cancer. Some single-nucleotide polymorphisms in IL-10, IL-4, and IL-4Rα genes have been associated with an anti-inflammatory environment and a Th2 profile in detriment of the antitumor Th1 response. This research sought to detect single-nucleotide polymorphisms in promoter sequences, like − 1082 (G/A), − 592 (C/A), and − 819 (C/T), as well as − 590 (C/T) of the IL-10 and IL-4 genes, respectively; in addition to the IL-4Rα mutation variants, Ile50Val and Q576R, together with circulating levels of IL-4, TNF-α, IL-10, and IFN-γ in patients with gastric carcinoma in Cúcuta, Colombia.

Methods

In a cross-sectional study, 17 patients and 30 healthy individuals were genotyped for the six polymorphisms mentioned through PCR-RFLP of DNA obtained from peripheral blood cells and serum samples were analyzed by sandwich ELISA to quantify cytokines. Statistical difference between groups was determined along with the association between the presence of polymorphisms and the risk of gastric cancer, as well as the mortality in patients, using Mann-Whitney U test and logistic regression analysis, respectively.

Results

An association between the − 1082 (G/A) and the risk of gastric cancer was found (OR = 7.58, range 0.77–74.06, P = 0.08). Furthermore, patients had a significant increase in IL-4 serum levels (P < 0.01) compared to healthy individuals, both variables showed a higher estimated risk of mortality in patients, although without statistical association (P > 0.05).

Conclusion

We infer that two possible biomarkers (one immunological and one genetic) could be considered in association with gastric cancer in our population, which should be confirmed by subsequent studies involving a greater number of individuals.

The vascular endothelial specific IL-4 receptor alpha-ABL1 kinase signaling axis regulates the severity of IgE-mediated anaphylactic reactions

BACKGROUND

Severe IgE-mediated, food-induced anaphylactic reactions are characterized by pulmonary venous vasodilatation and fluid extravasation, which are thought to lead to the life-threatening anaphylactic phenotype. The underlying immunologic and cellular processes involved in driving fluid extravasation and the severe anaphylactic phenotype are not fully elucidated.

OBJECTIVE

We sought to define the interaction and requirement of IL-4 and vascular endothelial (VE) IL-4 receptor α chain (IL-4Rα) signaling in histamine-abelson murine leukemia viral oncogene homology 1 (ABL1)-mediated VE dysfunction and fluid extravasation in the severity of IgE-mediated anaphylactic reactions in mice.

METHODS

Mice deficient in VE IL-4Rα and models of passive and active oral antigen- and IgE-induced anaphylaxis were used to define the requirements of the VE IL-4Rα and ABL1 pathway in severe anaphylactic reactions. The human VE cell line (EA.hy926 cells) and pharmacologic (imatinib) and genetic (short hairpin RNA knockdown of IL4RA and ABL1) approaches were used to define the requirement of this pathway in VE barrier dysfunction.

RESULTS

IL-4 exacerbation of histamine-induced hypovolemic shock in mice was dependent on VE expression of IL-4Rα. IL-4- and histamine-induced ABL1 activation in human VE cells and VE barrier dysfunction was ABL1-dependent. Development of severe IgE-mediated hypovolemia and shock required VE-restricted ABL1 expression. Treatment of mice with a history of food-induced anaphylaxis with the ABL kinase inhibitor imatinib protected the mice from severe IgE-mediated anaphylaxis.

CONCLUSION

IL-4 amplifies IgE- and histamine-induced VE dysfunction, fluid extravasation, and the severity of anaphylaxis through a VE IL-4Rα/ABL1-dependent mechanism. These studies implicate an important contribution by the VE compartment in the severity of anaphylaxis and identify a new pathway for therapeutic intervention of IgE-mediated reactions.

Personalized management of asthma exacerbations: lessons from genetic studies

INTRODUCTION

The genetics of severe asthma and asthma exacerbations are distinct from milder forms of asthma. Gene-environmental interactions contribute to the complexity and heterogeneity of severe asthma and asthma exacerbations, and pharmacogenomic studies have also identified genes that affect susceptibility to asthma exacerbations.

AREAS COVERED

Studies on the genetics, gene-environment interactions, and pharmacogenomics of asthma exacerbations are reviewed. Multiple individual genetic variants have been identified to be associated with asthma exacerbations but each genetic polymorphism explains only a fraction of the disease and by itself is not able to translate into clinical practice. Research is shifting from candidate gene studies and genome wide association studies towards more integrative approaches to translate genetic findings into clinical diagnostic and therapeutic tools.

EXPERT COMMENTARY

Integrative approaches combining polygenic or genomic data with multi-omics technologies have the potential to discover new biologic mechanisms and biomarkers for severe asthma and asthma exacerbations. Greater understanding of genomics and underlying biologic pathways will also lead to improved prevention and treatment, lowering costs, morbidity, and mortality. The utilization of genomic testing and personalized medicine may revolutionize asthma management, in particular for patients with severe, refractory asthma.

A preliminary study on the association of single nucleotide polymorphisms of interleukin 4 (IL4), IL13, IL4 receptor alpha (IL4Rα) & Toll-like receptor 4 (TLR4) genes with asthma in Indian adults

Background & objectives:

Interleukin 4 (IL4) and IL13 genes are believed to be responsible for inflammation of the airways in asthmatics. These share a common receptor component called IL4Rα which is another potentially important candidate gene linked to asthma phenotypes. Another gene Toll-like receptor 4 (TLR4) might affect the incidence or progression of asthma through the expression of proinflammatory genes. Several single nucleotide polymorphisms (SNPs) in IL4, IL13, IL4Rα and TLR4 have been reported to be linked to asthma or related phenotypes in several ethnic populations using linkage studies and association studies. However, the results have not been consistent. We investigated five SNPs (C-589T and C-33T of IL4, G+2044A of IL13, A+1902G of IL4Rα, and A+896G of TLR4) in patients with adult onset asthma to evaluate their role in manifestation and severity of asthma.

Methods:

Adult (>18 yr of age) patients with asthma (n=100) and healthy controls (n=50) were included in the study. Genotyping was performed using sequenom MassARRAY technology.

Results:

The mutant alleles of the C-589T and C-33T SNPs in the promoter region of IL4 were present in 4 per cent patients with asthma but absent from the control group suggesting that the variations in IL4 may contribute to asthma occurrence. The SNPs of other genes were seen in both controls and patients.

Interpretation & conclusions:

The results suggest the possible association between the genetic distribution of C-589T and C-33T SNPs of IL4 with asthma in Indian adults.

Association of IL4 and IL4R polymorphisms with multiple sclerosis susceptibility in Caucasian population: A meta-analysis

BACKGROUND

Previous studies have suggested a role for interleukin-4 (IL4) and its receptor (IL4R) gene in susceptibility to multiple sclerosis (MS), but the results remain controversial and under-powered.

OBJECTIVES

To investigate the contradictory results, we performed a meta-analysis to assess the possible association between polymorphisms of the IL4 rs2243250 (C/T), variable number of tandem repeat (VNTR) polymorphism in intron-3 (I3(709)VNTR), IL4R rs1801275 (T/C) and MS in Caucasian populations.

METHODS

A comprehensive search was conducted to identify all case-control or cohort design studies. The fixed or random effect pooled measure was selected based on the homogeneity test among studies that was evaluated with I(2). Publication bias was estimated using the Begg's and Egger's test.

RESULTS

A total of ten studies were included in the meta-analysis. The crude odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated to evaluate the association. Overall, after excluding articles deviating from Hardy-Weinberg equilibrium in controls and sensitive analysis, the meta-analysis showed a significant association between polymorphism of IL4 rs2243250 and MS susceptibility in allele model (OR=1.209, 95% CI=1.022-1.429, P=0.026) and dominant model (OR =1.225, 95% CI=1.013-1.480, P=0.036). However, no significant association was found between polymorphisms of IL4 I3(709)*VNTR, IL4R rs1801275 and MS susceptibility, respectively.

CONCLUSIONS

The meta-analysis indicates that the T allele, CT and TT genotype of polymorphism of IL4 rs2243250 (C/T) may reduce the risk of MS in Caucasian populations, while polymorphisms of IL4 I3(709)*VNTR and IL4R rs1801275 may not associated with risk of MS in Caucasian populations.

Polymorphisms of genes encoding interleukin-4 and its receptor in Iranian patients with juvenile idiopathic arthritis

As cytokines, including interleukin-4 (IL-4), seem to have a pivotal role in the pathogenesis of juvenile idiopathic arthritis (JIA), this study is aimed at investigating of association of polymorphisms in IL-4 and IL-4 receptor α (IL-4RA) genes with susceptibility to JIA. A case-control study was conducted on 53 patients with JIA and 139 healthy unrelated controls. Single nucleotide polymorphisms of IL-4 gene at positions -1098, -590, and -33, as well as IL-4RA gene at position +1902 were genotyped using polymerase chain reaction with sequence-specific primers method and compared between patients and healthy individuals. At the allelic level, C allele at IL-4 -33 was found to be more frequent in patients compared to control (P value <0.01). At the genotypic level, CC genotype at IL-4 -590 (P value <0.01), together with CC and TT genotypes at IL-4 -33 (P value <0.01), were significantly higher in patients with JIA, while TC genotypes at IL-4 -590 and -33 positions were found to be lower in case group (P value <0.01). At the haplotypic level, IL-4 (positions -1098, -509, -33) TTC, GCC, and TTT haplotypes were significantly lower than controls (P value <0.01, P value = 0.03, and P value = 0.04, respectively). Although, TCC haplotype at the same positions was found to be higher in patients (P value <0.01). Polymorphic site of +1902 IL-4RA gene did not differ between cases and controls. Polymorphisms in promoter region of IL-4 but not IL-4RA genes confer susceptibility to JIA and may predispose individuals to adaptive immune responses.

Immunobiology of critical pediatric asthma

Asthma is a heterogeneous disease with numerous clinical phenotypes. Severe asthma constitutes about 10 % of all cases of asthma. There is significant geographic and regional variation in the incidence and severity of asthma. Other important factors include gender, ethnicity, living environment, lifestyle, socioeconomic class, and pathophysiology. These factors can often be identified as either genetic or environmental influences on asthma severity. The immune system derangements in severe asthma are poorly understood. Many molecules and cell types have been implicated in severe asthma, including neutrophils, airway epithelial cells, thymic stromal lymphopoietin, and even filaggrin. Recently, vitamin D has been thought to have a role in the severity of asthma. Aspirin exacerbated respiratory disease is an example of a phenotype that includes severe asthma as a feature. This suggests a role of leukotrienes or prostaglandins in the pathogenesis of severe asthma. Both the innate and adaptive immune system may play a role in the development of severe asthma. Besides filaggrin, other factors of the innate immune system, including TLR4 and TLR9 have been implicated in asthma. Airway epithelial cells possess pattern recognition receptors that recognize danger or pathogen-associated molecular patterns, and the result of binding of the ligand is the triggering of a signaling pathway that ultimately can lead to an activation of inflammatory mediators through the action of calcineurin and NF-κB. Components of the adaptive immune system, including TH2 and Th17 cells, have been implicated in the pathogenesis of asthma. The fact that so many molecules and cells may be variably involved in asthma patients, coupled with the presence of redundant pathways that lead to secretion of inflammatory mediators, make the development of effective drugs for the treatment of asthma extremely difficult. A better understanding of the heterogeneity and what drives this diversity on a genetic and epigenetic level will help to develop strategies for novel therapeutic agents or methods.

Rhinovirus-induced IL-25 in asthma exacerbation drives type 2 immunity and allergic pulmonary inflammation

Rhinoviruses (RVs), which are the most common cause of virally induced asthma exacerbations, account for much of the burden of asthma in terms of morbidity, mortality, and associated cost. Interleukin-25 (IL-25) activates type 2-driven inflammation and is therefore potentially important in virally induced asthma exacerbations. To investigate this, we examined whether RV-induced IL-25 could contribute to asthma exacerbations. RV-infected cultured asthmatic bronchial epithelial cells exhibited a heightened intrinsic capacity for IL-25 expression, which correlated with donor atopic status. In vivo human IL-25 expression was greater in asthmatics at baseline and during experimental RV infection. In addition, in mice, RV infection induced IL-25 expression and augmented allergen-induced IL-25. Blockade of the IL-25 receptor reduced many RV-induced exacerbation-specific responses including type 2 cytokine expression, mucus production, and recruitment of eosinophils, neutrophils, basophils, and T and non-T type 2 cells. Therefore, asthmatic epithelial cells have an increased intrinsic capacity for expression of a pro-type 2 cytokine in response to a viral infection, and IL-25 is a key mediator of RV-induced exacerbations of pulmonary inflammation.

Exploring the origins of asthma: Lessons from twin studies

This thesis explores the contribution of twin studies, particularly those studies originating from the Danish Twin Registry, to the understanding of the aetiology of asthma. First, it is explored how twin studies have established the contribution of genetic and environmental factors to the variation in the susceptibility to asthma, and to the variation in several aspects of the clinical expression of the disease such as its age at onset, its symptomatology, its intermediate phenotypes, and its relationship with other atopic diseases. Next, it is explored how twin studies have corroborated theories explaining asthma's recent increase in prevalence, and last, how these fit with the explanations of the epidemiological trends in other common chronic diseases of modernity.

Association between promoter polymorphisms of interleukin-4 gene and allergic rhinitis risk: a meta-analysis

The relationship of interleukin-4 (IL-4) C-33T and C-590T (C-589T) gene polymorphisms with allergic rhinitis was analyzed. Data about the case control studies of IL-4 gene promoter polymorphisms [C-33T and C-590T (C-589T)] and their association with allergic diseases and correlation between serum IL-4 levels and allergic rhinitis were retrieved. The Stata 12.0 statistical software was applied to analyze the correlation between IL-4 gene polymorphisms and allergic rhinitis. The meta-analysis result of TT/CC genotype of -590 (-589) polymorphism showed a significant association with allergic diseases [OR=1.93, 95% CI (1.61-2.31), P=0.00]. Meta-analysis of the TT+TC versus CC genotype of IL-4 C-33/T polymorphism revealed significant associations with allergic diseases [OR=3.23, 95% CI (1.13-9.25), P=0.03]. Meanwhile, there was a significant correlation between serum IL-4 levels and allergic rhinitis [OR=2.52, 95% CI=(1.80-3.23), P=0.00]. IL-4 gene -590 TT genotype may increase the risk of allergic rhinitis and the T allele mutation of -33 might be correlated with allergic rhinitis.

IL-4 receptor alpha single-nucleotide polymorphisms rs1805010 and rs1801275 are associated with increased risk of asthma in a Saudi Arabian population

BACKGROUND

The IL-4 receptor alpha subunit (IL-4Rα), when associated with the common gamma chain receptor, or the IL-13Rα1 subunit, transduces signals to STAT6 in response to IL-4 and IL-13 stimulations. This results in a number of cell-specific responses including Th2 differentiation, lymphocyte proliferation and IgE production. Given the prominent role of IL-4Rα in allergic disorders, several single-nucleotide polymorphisms (SNPs) have been found associated with asthma and other atopic disorders, including rs1805010 (I75V) and rs1801275 (Q576R) SNPs; however, lack of significant association have also been reported for some ethnic groups. The objective of this study was to determine whether IL-4Rα rs1805010 and rs1801275 polymorphisms are associated with asthma in patients from Saudi Arabia.

MATERIALS AND METHODS

One hundred and ninety severe asthmatic patients (11-70 years old) and 194 healthy subjects of equivalent age range were recruited for blood donation. DNA was purified and genotyping for rs1801275 and rs1805010 polymorphisms in the IL-4Rα gene was performed by PCR amplification, followed by cycle sequencing of the purified PCR fragments using BigDye chain terminator and capillary electrophoresis.

RESULTS

Pearson's Chi-square tests showed that the minor alleles, G, for both rs1805010 and rs1801275 SNPs, were significantly more frequent in asthmatics than in the healthy group (Yates' P < 0.05); conversely, the major alleles, A, were significantly more frequent in healthy than in asthmatics (P < 0.05). Concerning association analysis, odds for A/G-G/G genotypes were significantly higher to be associated with asthma predisposition (rs1801275: OR = 2.12; 95% CI = 1.39-3.22; P < 0.001*; rs1805010: OR = 1.6; 95% CI = 1.01-2.53; P < 0.05*; dominant model). Analysis of gender-genotype interactions, with genders nested within A/G-G/G, indicated higher odds for females than males of significant association with asthma (rs1801275: OR = 5.19, 95% CI = 2.09-12.94*; rs1805010: OR = 3.73, 95% CI = 2.06-6.74*). Rs1805010 and rs1801275 were in linkage disequilibrium (D' = 0.27; P < 0.0004*), with G-G haplotype being more frequent in asthmatics than in healthy subjects (OR = 2.43, 95% CI = 1.59-3.71*).

CONCLUSIONS

The risk alleles, G, of IL-4Rα rs1805010 and rs1801275 SNPs and corresponding A/G-G/G genotypes were significantly associated with asthma predisposition in asthmatics from Saudi Arabia.

Severe asthma and its phenotype

The phenotype of severe, or difficult, asthma is poorly understood, but recent studies have been informative. Factors associated with severe asthma include the presence of co-morbidities such as sinusitis, obesity and gastroesophageal reflux, poor adherence with prescribed medical regimens, and a severe underlying disease process. The worst long-term prognosis in severe asthma is associated with the presence of persistent airflow limitation and exacerbations. Individualization of therapy based on phenotype is highly recommended.

The role of rhinosinusitis in severe asthma

The prevalence of asthma is approximately 5% to 10% in the general population. Of these, approximately 5% to 10% are severe asthmatics who respond poorly to asthmatic drugs, including high-dose inhaled steroids. Severe asthmatics have persistent symptoms, frequent symptom exacerbation, and severe airway obstruction even when taking high-dose inhaled steroids. The medical costs of treating severe asthmatics represent ~50% of the total healthcare costs for asthma. Risk factors for severe asthma are genetic and environmental, including many kinds of aeroallergens, β-blockers, and anti-inflammatory drugs. Gastroesophageal reflux disease and factors such as denial, anxiety, fear, depression, socioeconomic status, and alcohol consumption can exacerbate asthma. Rhinitis and asthma usually occur together. There is increasing evidence that allergic rhinitis and rhinosinusitis may influence the clinical course of asthma. This review discusses the role of rhinosinusitis in severe asthma.

Associations of interleukin-4 receptor gene polymorphisms (Q551R, I50V) with rheumatoid arthritis: evidence from a meta-analysis

BACKGROUND AND AIMS

Published data on the associations between interleukin-4 receptor (IL-4R) gene polymorphisms (Q551R, I50V) and rheumatoid arthritis (RA) risk are controversial. To quantitatively evaluate the relationships, a meta-analysis was performed.

METHODS

Studies were identified from the databases of PubMed, MEDLINE, Chinese Biomedical Literature Database, and Chinese National Knowledge Infrastructure, with the last report up to June 2012. The effect summary odds ratio (OR) and 95% confidence interval (CI) were obtained.

RESULTS

A total of six separate comparisons involving 2173 patients and 1892 controls were included to assess the association of IL-4R gene Q551R polymorphism and RA susceptibility. Overall, no significantly elevated RA risk was found in the meta-analysis. The pooled OR for the minor R allele was 0.942 (95% CI: 0.848-1.047, p=0.268) in patients with RA. After stratification by ethnicity, there was still no significant association detected in the European population (OR=0.979, 95% CI: 0.875-1.094). As for I50V polymorphism, there were four comparisons involving 1653 patients and 1584 controls in this meta-analysis. The pooled OR for the V allele was 1.104 (95% CI: 1.001-1.217) in RA, the V allele of the IL-4R gene I50V variant might be a risk factor for RA. However, the relationship between the V allele of IL-4R gene I50V polymorphism and rheumatoid factor positive in patients with RA was not identified through a minor meta-analysis, including four independent relevant comparisons.

CONCLUSIONS

This meta-analysis indicates that the I50V polymorphism of IL-4R gene may confer susceptibility to RA; up to now, there is still not enough evidence to reveal the association of the IL-4R gene Q551R polymorphism with RA risk.

Inhibition of high-mobility group box 1 in lung reduced airway inflammation and remodeling in a mouse model of chronic asthma

The role of high-mobility group box 1 (HMGB1) in chronic allergic asthma is currently unclear. Both airway neutrophilia and eosinophilia and increase in HMGB1 expression in the lungs in our murine model of chronic asthma. Inhibition of HMGB1 expression in lung in ovalbumin (OVA)-immunized mice decreased induced airway inflammation, mucus formation, and collagen deposition in lung tissues. Analysis of the numbers of CD4(+) T helper (Th) cells in the mediastinal lymph nodes and lungs revealed that Th17 showed greater increases than Th2 cells and Th1 cells in OVA-immunized mice; further, the numbers of Th1, Th2, and Th17 cells decreased in anti-HMGB1 antibody (Ab)-treated mice. In OVA-immunized mice, TLR-2 and TLR-4 expression, but not RAGE expression, was activated in the lungs and attenuated after anti-HMGB1 Ab treatment. The results showed that increase in HMGB1 release and expression in the lungs could be an important pathological mechanism underlying chronic allergic asthma and HMGB1 might a potential therapeutic target for chronic allergic asthma.

Association between interleukin-4 receptor α chain (IL4RA) I50V and Q551R polymorphisms and asthma risk: an update meta-analysis

BACKGROUND

The associations between the interleukin-4 receptor α chain (IL4RA) I50V and Q551R polymorphisms and asthma risk remained controversial.

METHODS

We searched the Pubmed, Embase, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases for studies published before February 2013. The strengths of the associations were calculated using odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

A total of 50 studies were included in this meta-analysis. There was a significant association between the IL4RA I50V polymorphism and asthma risk in a dominant genetic model (OR = 1.13, 95% CI 1.04-1.23, P = 0.005). The IL4RA Q551R polymorphism was associated with a significantly elevated asthma risk in a recessive genetic model (OR = 1.46, 95% CI 1.22-1.75, P<0.0001). Subgroup analyses found that the IL4RA I50V polymorphism was significantly associated with asthma risk in Asians (OR = 1.72, 95% CI 1.31-2.25, P<0.0001), pediatric asthma risk (OR = 1.50, 95% CI 1.13-1.99, P = 0.005), and atopic asthma risk (OR = 1.88, 95% CI 1.27-2.79, P = 0.002).

CONCLUSIONS

The results of this meta-analysis suggested that the IL4RA I50V and Q551R polymorphisms may be risk factors for developing asthma.

Genetic analysis of asthma exacerbations

BACKGROUND

Identifying genetic markers of susceptibility to exacerbations may improve patient management, decrease morbidity, and lead to drug development.

OBJECTIVES

To assess whether genetic markers associated with severe asthma exacerbations in previous reports are associated with less severe events that do not require intensive care and intubation and to identify additional markers in candidate genes and throughout the genome.

METHODS

A total of 199 patients and 502 controls (individuals without an exacerbation) were identified from 4 clinical trials. We genotyped 51 markers from 17 genes previously reported to be associated with exacerbations; a whole genome scan was used to identify additional markers. Admixture analysis was conducted to characterize the presence of ancestral groups. The genetic marker effects were assessed by logistic regression for each study followed by a meta-analysis.

RESULTS

Several coding variants in the IL4R gene had a genetic effect across 3 studies, including rs1805011 in IL4R (P < .0006). In addition, 3 markers in the IFNB1 gene showed evidence of association (P < .002) but only in the study with African Americans. Because these markers did not meet the prespecified multiplicity-adjusted significance level of P = .0002, we were unable to confirm previously published results for less severe events. The whole genome scan identified genes related to mast cell mediator release. The admixture analysis suggests that ancestry was best characterized by the presence of 3 ancestral groups.

CONCLUSION

We were unable to confirm previously reported associations of genetic markers with asthma exacerbations. Although, in general, the patients studied had less severe asthma than patients in earlier reports, these results suggest involvement of similar pathways.

TRIAL REGISTRATION

clinicaltrials.gov Identifiers: NTC00452699, NCT00452348, NTC00102765, NCT00843193.

IL-4 Receptor α Polymorphisms May Be a Susceptible Factor for Work-Related Respiratory Symptoms in Bakery Workers

Purpose

The IL-4 and IL-4 receptor α (IL-4Rα) genes are the key candidate genes for atopy and asthma susceptibility. Exposure to wheat flour can cause IgE sensitization and respiratory symptoms in bakery workers. Therefore, we hypothesized that IL-4 and IL-4Rα single nucleotide polymorphisms (SNPs) may be involved in the pathogenic mechanism of baker's asthma.

Methods

Clinical and genetic data from 373 bakery workers were analyzed. A survey questionnaire, spirometry, and skin prick tests with wheat flour were performed. Serum-specific IgE, IgG1, and IgG4 to wheat flour were determined using ELISA. Five candidate IL-4 (-729 T>G, 589 T>C, and 33 T>C) and IL-4Rα (Ile75Val A>G and Gln576Arg A>G) SNPs were genotyped and analyzed.

Results

Workers with the G allele of IL-4Rα Ile75Val A>G had a significantly higher prevalence of work-related lower respiratory symptoms than those with the AA genotype (P=0.004, 16.0% vs. 2.9%). In the skin prick test, workers with the AA genotype of IL-4Rα Gln576Arg A>G had a significantly higher positive rate to wheat flour (P=0.015, 8.2% vs. 1.1%) than those with AG/GG genotype. No significant associations were found in the three genetic polymorphisms of IL-4. For the predicted probabilities, workers with the AA genotype of Gln576Arg A>G had a higher prevalence of IgG1 and IgG4 in response to wheat flour, according to increased exposure intensity (P=0.001 for IgG1 and P=0.003 for IgG4).

Conclusions

These findings suggest that the IL-4Rα Ile75Val and Gln576Arg polymorphisms may be associated with work-related respiratory symptom development.

Atopy is important in the management of asthma

Allergic diseases are a public health problem in industrialized countries due to the increasing number of allergies related to Western lifestyle. The multiplicity of organs affected by allergy (skin (atopic dermatitis), airway epithelium (respiratory allergy), and digestive tract (food allergy)) worsens the prognosis of each of the allergic diseases and specially asthma. The importance of allergy in management of asthma is also underlined by the risk of fatal or near fatal acute asthma attacks due to multiple allergic sensitizations. Preliminary studies suggest that specific treatment of allergy could change the asthma course.

Can certain genotypes predispose to poor asthma control in children? A pharmacogenetic study of 9 candidate genes in children with difficult asthma

Objective

We tested the hypothesis that patients with difficult asthma have an increased frequency of certain genotypes that predispose them to asthma exacerbations and poor asthma control.

Methods

A total of 180 Caucasian children with confirmed asthma diagnosis were selected from two phenotypic groups; difficult (n = 112) versus mild/moderate asthma (n = 68) groups. All patients were screened for 19 polymorphisms in 9 candidate genes to evaluate their association with difficult asthma.

Key Results

The results indicated that LTA4H A-9188>G, TNFα G-308>A and IL-4Rα A1727>G polymorphisms were significantly associated with the development of difficult asthma in paediatric patients (p<0.001, p = 0.019 and p = 0.037, respectively). Haplotype analysis also revealed two haplotypes (ATA haplotype of IL-4Rα A1199>C, IL-4Rα T1570>C and IL-4Rα A1727>G and CA haplotype of TNFα C-863>A and TNFα G-308>A polymorphisms) which were significantly associated with difficult asthma in children (p = 0.04 and p = 0.018, respectively).

Conclusions and Clinical Relevance

The study revealed multiple SNPs and haplotypes in LTA4H, TNFα and IL4-Rα genes which constitute risk factors for the development of difficult asthma in children. Of particular interest is the LTA4H A-9188>G polymorphism which has been reported, for the first time, to have strong association with severe asthma in children. Our results suggest that screening for patients with this genetic marker could help characterise the heterogeneity of responses to leukotriene-modifying medications and, hence, facilitate targeting these therapies to the subset of patients who are most likely to gain benefit.

The interleukin-4 -589C/T polymorphism and the risk of asthma: a meta-analysis including 7,345 cases and 7,819 controls

BACKGROUND

A number of studies assessed the association of -589C/T polymorphism in the promoter region of interleukin-4 (IL-4) with asthma in different populations. However, the results were contradictory. A meta-analysis was conducted to investigate the association between polymorphism in the IL-4 and asthma susceptibility.

METHODS

Databases including Pubmed, EMBASE, Wanfang Database, China National Knowledge Infrastructure (CNKI) and Weipu Database were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations.

RESULTS

Thirty-four studies involving 7345 cases and 7819 controls were included. Overall, significant association between -589C/T polymorphism and asthma was observed for TT+CT vs. CC (OR=1.26; 95% CI 1.12-1.42; P=0.0001; I(2)=26%). In the subgroup analysis by ethnicity, significant associations were found among Asians (OR=1.36; 95% CI 1.07-1.73; P=0.01; I(2)=0%) and Caucasians (OR=1.30; 95% CI 1.09-1.54; P=0.004; I(2)=53%) but not among African Americans (OR=1.20; 95% CI 0.72-2.00; P=0.48; I(2)=48%). In the subgroup analysis by atopic status, no significant association was found among atopic asthma patients (OR=1.20; 95% CI 0.92-1.34; P=0.27; I(2)=6%) and non-atopic asthma patients (OR=0.97; 95% CI 0.73-1.28; P=0.81; I(2)=0%).

CONCLUSIONS

This meta-analysis suggested that the IL-4 -589C/T polymorphism was a risk factor of asthma.

Association between the interleukin-4 gene C-589T and C+33T polymorphisms and asthma risk: a meta-analysis

BACKGROUND AND AIMS

A large number of studies have investigated the correlation between the interleukin (IL)-4 C-589T and C+33T polymorphisms and asthma susceptibility. However, the results are inconsistent. The objective of this study is to explore the association between the IL-4 C-589T and C+33T polymorphisms and asthma risk using meta-analysis.

METHODS

A total of 35 studies (31 concerning C-589T polymorphism and asthma risk with 4737 asthmatics and 6389 controls and 14 studies regarding C+33T polymorphism and asthma risk with 2544 asthmatics and 4049 controls) were included in this meta-analysis.

RESULTS

The IL-4 C-589T polymorphism was associated with increased asthma risk in a dominant genetic model (odds ratio [OR] [95% confidence interval (CI)] = 1.284 [1.131-1.459] for TT + TC vs. CC). In the subgroup analyses by ethnicity, age and atopic status of asthmatics, significantly increased risks of asthma were found both in Asians (OR [95% CI] = 1.301 [1.003-1.689]) and Caucasians (OR [95% CI] = 1.314 [1.061-1.628]) and in both adults (OR [95% CI] = 1.299 [1.098-1.537]) and children (OR [95% CI] = 1.464 [1.044-2.052]). As for the C+33T polymorphism, the results showed that it was correlated with elevated asthma risk in a recessive genetic model (OR [95% CI] = 1.744 [1.215-2.504] for TT vs. CT + CC). After stratifying analyses by ethnicity, age and atopic status of asthmatics, significantly increased asthma risks were observed in Asians (OR [95% CI] = 1.223 [1.037-1.442]), Caucasians (OR [95% CI] = 3.036 [1.224-7.529]), and children (OR [95% CI] = 1.300 [1.075-1.573]) in a recessive genetic model.

CONCLUSIONS

This meta-analysis suggests that the IL-4 C-589T and C+33T polymorphisms may be risk factors for asthma.

Association between the interleukin-4, interleukin-13 polymorphisms and asthma: a meta-analysis

A numbers studies had been reported that the polymorphisms in the Interleukin 4 (IL-4) and Interleukin 13 (IL-13) genes were associated with susceptibility to asthma. However, the results were inconsistent and inconclusive. We carried out a meta-analysis of case-control genetic association studies to assess whether the combined data showed this association by using a genetic model-free approach. Thirty studies (total 12,781 asthma and 11,500 controls) for the IL-4 C-33T and C-589T, IL-13 C-1112T and G+2044A with asthma were included in the meta-analysis. The results indicated that there were an association between the IL-4 C-33T (P = 0.006) and C-589T (P = 0.04), IL-13 C-1112T (P = 0.002) and G+2044A (P = 0.04) and susceptibility to asthma. And the definition of asthma subgroup meta-analysis demonstrates that the IL-4 C-33T is not associated with nonatopic or atopic, and IL-4 C-589T and IL-13 C-1112T polymorphisms are not associated with atopic. In the ethnicity subgroup meta-analysis, the IL-4 -589T (P = 0.003) and the IL-13 -1112T (P < 0.00001) alleles are associated with asthma among Caucasian, but not on the IL-13 +2044A allele. In conclusion, IL-4 C-33T and C-589T, IL-13 C-1112T and G+2044A could be proposed as asthma susceptible SNPs. Further investigation in larger studies and meta-analysis is required.

Cytokines and cytokine-specific therapy in asthma

Asthma is increasing in prevalence worldwide. It is characterized by typical symptoms and variable airway obstruction punctuated with episodes of worsening symptoms known as exacerbations. Underlying this clinical expression of disease is airway inflammation and remodeling. Cytokines and their networks are implicated in the innate and adaptive immune responses driving airway inflammation in asthma and are modulated by host-environment interactions. Asthma is a complex heterogeneous disease, and the paradigm of Th2 cytokine-mediated eosinophilic inflammation as a consequence of allergic sensitization has been challenged and probably represents a subgroup of asthma. Indeed, as attention has switched to the importance of severe asthma, which represents the highest burden both to the patient and health care provider, there is an increasing recognition of inflammatory subphenotypes that are likely to be driven by different cytokine networks. Interestingly, these networks may be specific to aspects of clinical expression as well as inflammatory cell profiles and therefore present novel phenotype-specific therapeutic strategies. Here, we review the breadth of cytokines implicated in the pathogenesis of asthma and focus upon the outcomes of early clinical trials conducted using cytokines or cytokine-blocking therapies.

Pathophysiology of asthma: lessons from genetic research with particular focus on severe asthma

There is good evidence that both inherited and environmental factors influence the risk of developing asthma. Only recently, large well-designed studies have been undertaken with the power to identify the genetic causes for asthma, and methods developed in parallel with the Human Genome Project, such as gene expression and epigenetic studies, have made large-scale analyses of functional genetics possible. In this review, we discuss the recent findings from genetic and genomic research studies of asthma, particularly severe asthma, and highlight specific genes for which there are multiple lines of evidence for involvement in asthma pathogenesis. Bio-ontologic enrichment analyses of the most recently identified asthma-related genes point to attributes such as 'molecular and signal transducer activity' and 'immune system processes', which indicates the importance of immunoregulation and inflammatory response in the pathogenesis of asthma. Finally, we discuss how genetic and environmental factors jointly influence asthma susceptibility and summarize how the results may increase understanding of the pathophysiology of asthma-related diseases.

Steroid response in refractory asthmatics

Inhaled glucocorticosteroids are currently the most effective anti-inflammatory controller medications for treating persistent asthma. The efficacies of glucocorticoids include reducing asthma symptoms, reducing exacerbation frequency, improving quality of life, improving lung function, decreasing airway hyperresponsiveness, controlling airway inflammation, and reducing mortality. However, the treatment response to glucocorticosteroids in asthmatics varies, and certain subtypes of asthma, such as refractory asthma, respond poorly to high-dose inhaled glucocorticoid and systemic steroids. The medical costs of treating refractory asthmatics represent about 50% of the total healthcare cost for asthma. A thorough understanding of the mechanisms of glucocorticoid action, patient responses to glucocorticoids, and steroid resistance observed in refractory asthmatics is necessary for the targeted development of therapeutic drugs. This review discusses the characteristics of severe refractory asthmatics and the mechanisms of steroid response and resistance in asthma treatment.

Interleukin-4 rs2243250 polymorphism is associated with asthma among Caucasians and related to atopic asthma

Published data on the association between interleukin-4 (IL-4) rs2243250 (C-589T) polymorphism and asthma susceptibility are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 17 studies with 3037 asthma patients and 3032 healthy controls were included. Overall, significantly elevated asthma risk was associated with IL-4 T allele when all studies were pooled into the meta-analysis (CT vs. CC: OR=1.187, 95% CI=1.016-1.387; dominant model: OR=1.213, 95% CI=1.046-1.405). In the subgroup analysis by ethnicity, significantly increased risk was only found for Caucasians (TT vs. CC: OR=1.591, 95% CI=1.032-2.452; dominant model: OR=1.292, 95% CI=1.028-1.624). When stratified by asthma type, statistically significantly elevated risk was only found in atopic asthma group (dominant model: OR=1.313, 95% CI=1.033-1.667). Despite some limitations, this meta-analysis suggests that T allele at position -589 of the IL-4 gene promoter region is a low-penetrant risk factor for asthma development especially for Caucasians and atopic type.

Gene-gene and gene-environmental interactions of childhood asthma: a multifactor dimension reduction approach

Background

The importance of gene-gene and gene-environment interactions on asthma is well documented in literature, but a systematic analysis on the interaction between various genetic and environmental factors is still lacking.

Methodology/Principal Findings

We conducted a population-based, case-control study comprised of seventh-grade children from 14 Taiwanese communities. A total of 235 asthmatic cases and 1,310 non-asthmatic controls were selected for DNA collection and genotyping. We examined the gene-gene and gene-environment interactions between 17 single-nucleotide polymorphisms in antioxidative, inflammatory and obesity-related genes, and childhood asthma. Environmental exposures and disease status were obtained from parental questionnaires. The model-free and non-parametrical multifactor dimensionality reduction (MDR) method was used for the analysis. A three-way gene-gene interaction was elucidated between the gene coding glutathione S-transferase P (GSTP1), the gene coding interleukin-4 receptor alpha chain (IL4Ra) and the gene coding insulin induced gene 2 (INSIG2) on the risk of lifetime asthma. The testing-balanced accuracy on asthma was 57.83% with a cross-validation consistency of 10 out of 10. The interaction of preterm birth and indoor dampness had the highest training-balanced accuracy at 59.09%. Indoor dampness also interacted with many genes, including IL13, beta-2 adrenergic receptor (ADRB2), signal transducer and activator of transcription 6 (STAT6). We also used likelihood ratio tests for interaction and chi-square tests to validate our results and all tests showed statistical significance.

Conclusions/Significance

The results of this study suggest that GSTP1, INSIG2 and IL4Ra may influence the lifetime asthma susceptibility through gene-gene interactions in schoolchildren. Home dampness combined with each one of the genes STAT6, IL13 and ADRB2 could raise the asthma risk.

A study of asthma severity in adult twins

INTRODUCTION

The tendency to develop asthma runs in families, but whether the severity of asthma symptoms is inherited is not known.

OBJECTIVES

The aim of this study was to examine whether genetic factors influence the variation in the severity of asthma.

METHODS

Of a sample of 21 133 adult twins from the Danish Twin Registry, a total of 575 subjects (256 intact pairs and 63 single twins) who themselves and/or their co-twins reported a history of asthma at a questionnaire survey were clinically examined. The severity of asthma symptoms was graded according to a clinical interview, and markers of airway impairment and allergy were measured.

RESULTS

After adjusting for confounders, genetic factors explained 24% (10%-37%), P = 0.0004, of the variation in overall asthma symptom severity, whereas non-shared environment accounted for the remaining 76% of the variation. A significant genetic component was also found for the severity of specific asthma symptoms; wheezing 12% (3%-22%), P = 0.007 and shortness of breath 17% (7%-27%), P = 0.0006, but not for chest tightness and cough. Asthma symptom severity correlated weakly with rhinitis severity as well as with objective markers of lung function, airway inflammation, airway responsiveness and allergic sensitization.

CONCLUSION

The individual variation in asthma symptom severity is to some degree influenced by genetic factors, but environmental factors explain the main part of the variation. The genetic architectures underlying the severity of asthma symptoms and objectively measured asthma-related traits, respectively, seem to differ.

Asthma phenotypes in adults and clinical implications

It is becoming increasingly recognized that asthma is a heterogeneous disease, whether based on clinical factors, including the patient's age at diagnosis, symptom spectrum and treatment response, triggering factors, or the level and type of inflammation. Attempts to analyze the importance of these characteristics to the clinical presentation of asthma have led to the appreciation of numerous separate and overlapping asthma phenotypes. However, these approaches are 'biased' and based on the clinician/scientist's own experience. Recently, unbiased approaches have also been attempted using both molecular and statistical tools. Early results from these approaches have supported and expanded on the clinician's concepts. However, until specific biologic markers are identified for any of these proposed phenotypes, the definitive nature of any phenotype will remain speculative.

[Asthma control. Possible obstacles along the way]

With current therapeutic regimens, asthma should be well controlled in most patients. However, although asthma-related hospital admissions and mortality have decreased, the potential efficacy of treatments is not translating into optimal asthma control and quality of life. This discrepancy may be due to several factors and is complex to analyze. Poor asthma control can be caused by diverse reasons such as the patient's failure to understand how to take the medication, the presence of an untreated, underlying comorbid condition that aggravates the asthma, and the possibility that the patient has a severe form of glucocorticosteroid-insensitive asthma. The present article reviews the situations in which poor asthma control occurs for human-related reasons. These situations can be due to patients themselves and be independent of the disease or can be due to inadequate intervention by health professionals in specific areas and circumstances linked to asthma. A small but important group of patients with asthma is also analyzed; in this group, the asthma per se is severe and is refractory to routine treatments.

Association of interleukin-4 receptor gene polymorphisms with rheumatoid arthritis in Egyptian female patients

OBJECTIVES

The imbalance between proinflammatory and anti-inflammatory cytokines is a feature of rheumatoid arthritis (RA). The role of interleukin-4 (IL-4) and its receptor in the pathogenesis of RA is conflicting. We aim to investigate the role of polymorphisms in the IL-4Rα gene in susceptibility and severity of RA.

METHODS

One hundred and seventy-two RA patients and 172 controls were enrolled in the study. Genotyping of IL-4Rα I50V (rs1805010) and IL-4Rα Q576R (rs1801275) was determined by restriction fragment length polymorphism-polymerase chain reaction (PCR-RFLP).

RESULTS

IL-4Rα I50V genotype was significantly more frequent in patients with RA than in controls (OR: 1.97, 95% CI: 1-3.7, P: 0.035). Subjects with IL-4Rα V50V genotype were significantly more likely to have erosive arthropathy (OR: 2.6, 95% CI: 1.1-6.1, P: 0.02). The frequencies of IL-4Rα Q576R genotype were significantly decreased in patients with erosive RA compared to patients with nonerosive RA (31.6% versus 48.2%, OR: 2.7, 95% CI: 1-7.7, P: 0.04).

CONCLUSION

IL-4Rα polymorphisms were associated with susceptibility to RA and may be helpful in early detection of erosive RA.

Differences in candidate gene association between European ancestry and African American asthmatic children

BACKGROUND

Candidate gene case-control studies have identified several single nucleotide polymorphisms (SNPs) that are associated with asthma susceptibility. Most of these studies have been restricted to evaluations of specific SNPs within a single gene and within populations from European ancestry. Recently, there is increasing interest in understanding racial differences in genetic risk associated with childhood asthma. Our aim was to compare association patterns of asthma candidate genes between children of European and African ancestry.

METHODOLOGY/PRINCIPAL FINDINGS

Using a custom-designed Illumina SNP array, we genotyped 1,485 children within the Greater Cincinnati Pediatric Clinic Repository and Cincinnati Genomic Control Cohort for 259 SNPs in 28 genes and evaluated their associations with asthma. We identified 14 SNPs located in 6 genes that were significantly associated (p-values <0.05) with childhood asthma in African Americans. Among Caucasians, 13 SNPs in 5 genes were associated with childhood asthma. Two SNPs in IL4 were associated with asthma in both races (p-values <0.05). Gene-gene interaction studies identified race specific sets of genes that best discriminate between asthmatic children and non-allergic controls.

CONCLUSIONS/SIGNIFICANCE

We identified IL4 as having a role in asthma susceptibility in both African American and Caucasian children. However, while IL4 SNPs were associated with asthma in asthmatic children with European and African ancestry, the relative contributions of the most replicated asthma-associated SNPs varied by ancestry. These data provides valuable insights into the pathways that may predispose to asthma in individuals with European vs. African ancestry.

A methodology to establish a database to study gene environment interactions for childhood asthma

BACKGROUND

Gene-environment interactions are likely to explain some of the heterogeneity in childhood asthma. Here, we describe the methodology and experiences in establishing a database for childhood asthma designed to study gene-environment interactions (PAGES--Paediatric Asthma Gene Environment Study).

METHODS

Children with asthma and under the care of a respiratory paediatrician are being recruited from 15 hospitals between 2008 and 2011. An asthma questionnaire is completed and returned by post. At a routine clinic visit saliva is collected for DNA extraction. Detailed phenotyping in a proportion of children includes spirometry, bronchodilator response (BDR), skin prick reactivity, exhaled nitric oxide and salivary cotinine. Dietary and quality of life questionnaires are completed. Data are entered onto a purpose-built database.

RESULTS

To date 1045 children have been invited to participate and data collected in 501 (48%). The mean age (SD) of participants is 8.6 (3.9) years, 57% male. DNA has been collected in 436 children. Spirometry has been obtained in 172 children, mean % predicted (SD) FEV1 97% (15) and median (IQR) BDR is 5% (2, 9). There were differences in age, socioeconomic status, severity and %FEV1 between the different centres (p≤0.024). Reasons for non-participation included parents not having time to take part, children not attending clinics and, in a small proportion, refusal to take part.

CONCLUSIONS

It is feasible to establish a national database to study gene-environment interactions within an asthmatic paediatric population; there are barriers to participation and some different characteristics in individuals recruited from different centres. Recruitment to our study continues and is anticipated to extend current understanding of asthma heterogeneity.

Importance of cytokines in murine allergic airway disease and human asthma

Asthma is a common, disabling inflammatory respiratory disease that has increased in frequency and severity in developed nations. We review studies of murine allergic airway disease (MAAD) and human asthma that evaluate the importance of Th2 cytokines, Th2 response-promoting cytokines, IL-17, and proinflammatory and anti-inflammatory cytokines in MAAD and human asthma. We discuss murine studies that directly stimulate airways with specific cytokines or delete, inactivate, neutralize, or block specific cytokines or their receptors, as well as controversial issues including the roles of IL-5, IL-17, and IL-13Ralpha2 in MAAD and IL-4Ralpha expression by specific cell types. Studies of human asthmatic cytokine gene and protein expression, linkage of cytokine polymorphisms to asthma, cytokine responses to allergen stimulation, and clinical responses to cytokine antagonists are discussed as well. Results of these analyses establish the importance of specific cytokines in MAAD and human asthma and have therapeutic implications.