A complete screening of the IL4 gene: novel polymorphisms and their association with asthma and IgE in childhood

The Inhibitory Effect and Mechanism of the Histidine-Rich Peptide rAj-HRP from Apostichopus japonicus on Human Colon Cancer HCT116 Cells

Colon cancer is a common and lethal malignancy, ranking second in global cancer-related mortality, highlighting the urgent need for novel targeted therapies. The sea cucumber (Apostichopus japonicus) is a marine organism known for its medicinal properties. After conducting a bioinformatics analysis of the cDNA library of Apostichopus japonicus, we found and cloned a cDNA sequence encoding histidine-rich peptides, and the recombinant peptide was named rAj-HRP. Human histidine-rich peptides are known for their anti-cancer properties, raising questions as to whether rAj-HRP might exhibit similar effects. To investigate whether rAj-HRP can inhibit colon cancer, we used human colon cancer HCT116 cells as a model and studied the tumor suppressive activity in vitro and in vivo. The results showed that rAj-HRP inhibited HCT116 cell proliferation, migration, and adhesion to extracellular matrix (ECM) proteins in vitro. It also disrupted the cytoskeleton and induced apoptosis in these cells. In vivo, rAj-HRP significantly inhibited the growth of HCT116 tumors in BALB/c mice, reducing tumor volume and weight without affecting the body weight of the tumor-bearing mice. Western blot analysis showed that rAj-HRP inhibited HCT116 cell proliferation and induced apoptosis by upregulating BAX and promoting PARP zymogen degradation. Additionally, rAj-HRP inhibited HCT116 cell adhesion and migration by reducing MMP2 levels. Further research showed that rAj-HRP downregulated EGFR expression in HCT116 cells and inhibited key downstream molecules, including AKT, P-AKT, PLCγ, P38 MAPK, and c-Jun. In conclusion, rAj-HRP exhibits significant inhibitory effects on HCT116 cells in both in vitro and in vivo, primarily through the EGFR and apoptosis pathways. These findings suggest that rAj-HRP has the potential as a novel targeted therapy for colon cancer.

Atopy in Kashmir-validation from a case control study with respect to IgE and Interleukin genes

OBJECTIVES

Increased levels of serum Immunoglobulin-E (IgE) and different genetic variants of cytokines are common biochemical manifestation in Allergy. The current study was aimed to study the association of IgE and different variants of Interleukin-4 (IL-4), and Interleukin-13 (IL-13) genes with different kind of allergies.

METHODS

A pre-tested questionnaire was used to collect all the dietary, life style and clinical details by a trained staff. A blood sample of 2 ml each was collected in coagulated and anti-coagulated vials. DNA and serum samples were extracted and stored until further use. Serum IgE were estimated by ELISA while as the genotypic analysis was done by PCR-RFLP methods.

RESULTS

Statistically a significant difference of serum IgE levels were observed among cases and controls (P < 0.05). The observed significant difference of serum IgE levels were retained among subjects who also harboured variant genotypes of IL-4 and IL-13 genes (P < 0.05). Additionally, the above genetic variants significantly modified the risk of allergy when stratification was done based on various clinical characteristics.

CONCLUSION

Our study suggests that increased IgE levels and in association with variant forms of IL-4 and IL-13 genes are significantly associated with different types of allergies in study population.

Association of IL-4 and IL-4R Polymorphisms with Litter Size Traits in Pigs

Simple Summary

The IL-4 and IL-4R cytokine genes are responsible for immune response in the reproductive system and are related to embryonic implantation and fetal survival during pregnancy in females. However, to date, their effects on litter size traits in pigs have been not elucidated. Therefore, the present study was conducted to verify the porcine IL-4 and IL-4R polymorphisms and assess how they affect litter size traits in commercial pigs. The findings suggested that the porcine IL-4 g.134993898T > C and IL-4R c.1577A > T polymorphisms were associated with the litter size traits. Therefore, the porcine IL-4 and IL-4R genes may be potentially effective genetic markers to improve the litter size traits in pigs.

Abstract

The interleukin-4 (IL-4) and interleukin-4 receptor (IL-4R) are cytokines that are involved in the immune and reproductive systems. This study aimed to verify the polymorphisms in the porcine IL-4 and IL-4R genes and to assess their effects on litter size traits in commercial pigs. Single nucleotide polymorphisms (SNPs) in the porcine IL-4 and IL-4R genes were genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A non-coding SNP of IL-4 g.134993898T > C and a non-synonymous SNP of IL-4R c.1577A > T (amino acid change at position 526, Q526L) were found to be segregating in Landrace sows. The IL-4 g.134993898T > C polymorphism was significantly associated with the number of piglets weaned alive (NWA) trait. The IL-4R c.1577A > T polymorphism was significantly associated with the number born alive (NBA) and NWA traits. Moreover, the accumulation of favorable alleles of these two SNP markers revealed significant associations with the NBA, NWA, and mean weight of piglets at weaning (MWW) traits. These findings indicate that the porcine IL-4 and IL-4R genes may contribute to the reproductive traits of pigs and could be used as candidate genes to improve litter size traits in the pig breeding industry.

Advances in asthma genetics

While asthma has a strong genetic component, our current ability to systematically understand and predict asthma risk remains low, despite over a hundred genetic associations. The reasons for this unfilled gap range from technical limitations of current approaches to fundamental deficiencies in the way we understand asthma. These are discussed in the context of genomic advances.

Validation study of the association between genetic variant of IL4 and severe radiation pneumonitis in lung cancer patients treated with radiation therapy

BACKGROUND AND PURPOSE

Recent researches demonstrated that single nucleotide polymorphisms (SNPs) of genes involving inflammation, DNA repair, etc. were associated with risk of radiation pneumonitis (RP). However, these studies were single-centered, from single ethnic origin, without validation from independent cohort studies from other populations. In order to identify clinical valuable SNPs for RP, in this study we selected 19 RP-related SNPs candidates previously published before 2016 for validation in our cohort.

MATERIAL AND METHODS

359 lung cancer patients with radiotherapy were included in our prospective study (NCT02490319). Peripheral blood samples from these patients were genotyped by MassArray and Sanger Sequence method. Multivariate Cox hazard and other analyses were applied to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of all factors possibly related to the risk of RP.

RESULTS

Patients with elder age, MLD ≥15 Gy, V₂₀ ≥24% had higher risk of RP ≥grade 3 compared with their counterparts (HR = 2.020, 95% CI: 1.045-3.906, P = 0.037; HR = 2.502, 95% CI: 1.346-4.652, P = 0.004; HR = 2.256, 95% CI: 1.191-4.272, P = 0.013, respectively). Moreover, patients receiving IMRT were associated with decreased incidence of RP (HR = 0.520, 95% CI: 0.280-0.963, P = 0.037). Importantly, CT + TT genotype of IL4: rs2243250 was strongly related to decreased risk of RP ≥grade 3 (HR = 0.195, 95% CI: 0.090-0.424, P = 0.000037, P_c = 0.0006).

CONCLUSION

IL4: rs2243250 was validated to be significantly related to RP of grade ≥3 in our cohort. Our results further emphasized the prevalence and clinical value of IL4: rs2243250 on RP, and may thus be one of the important predictors of severe RP before radiotherapy.

Sex-moderated interactions between IL4/IL13 pathway genes and prenatal environment on cord blood IgE levels

BACKGROUND

Elevated cord blood IgE (cIgE), a predictor of atopic diseases, is influenced by genetic and environmental factors. However, gene-environment interactions on cIgE elevation and their difference by sex remain largely unexplored.

OBJECTIVE

This study aimed to determine whether there are sex-moderated interactions between genetic variants in the IL4/IL13 pathway and prenatal environments on cIgE elevation.

METHODS

Comprehensive information on environmental tobacco smoke (ETS), home dampness (indexed by combining mildewy odour, visible mould and water stamp on the wall) and other household environments was obtained using a structured questionnaire during the third trimester of pregnancy in 1107 full-term newborns. The cord blood was collected for measuring cIgE levels, with elevation defined as ≥0.5 IU/mL, and for genotyping of five single nucleotide polymorphisms of three candidate genes (IL-13 rs1800925, rs20541, rs848, IL-4 rs2243250 and STAT6 rs324011).

RESULTS

Gene-environment interactions on cIgE elevation were observed in male but not female newborns, including those between ETS and IL13 rs20541, between home dampness and STAT6 rs324011, and between composite environmental exposure (combined ETS and the three home dampness indices) and STAT6 rs324011 (P for interaction = 0.03, 0.006, and 0.001, respectively). Male newborns carrying STAT6 rs324011 CT or TT genotype manifested with a significant dose-response association of the composite environmental exposure with cIgE elevation.

CONCLUSION AND CLINICAL RELEVANCE

Sex moderates the gene-environment interactions involving IL4/IL13 pathway genes and prenatal household environments on cIgE elevation. The absence of prenatal exposure to ETS and home dampness in male neonates carrying the STAT6 rs324011 CT or TT genotype is least likely associated with cIgE elevation.

Immunoglobulin E-Mediated Autoimmunity

The study of autoimmunity mediated by immunoglobulin E (IgE) autoantibodies, which may be termed autoallergy, is in its infancy. It is now recognized that systemic lupus erythematosus, bullous pemphigoid (BP), and chronic urticaria, both spontaneous and inducible, are most likely to be mediated, at least in part, by IgE autoantibodies. The situation in other conditions, such as autoimmune uveitis, rheumatoid arthritis, hyperthyroid Graves’ disease, autoimmune pancreatitis, and even asthma, is far less clear but evidence for autoallergy is accumulating. To be certain of an autoallergic mechanism, it is necessary to identify both IgE autoantibodies and their targets as has been done with the transmembrane protein BP180 and the intracellular protein BP230 in BP and IL-24 in chronic spontaneous urticaria. Also, IgE-targeted therapies, such as anti-IgE, must have been shown to be of benefit to patients as has been done with both of these conditions. This comprehensive review of the literature on IgE-mediated autoallergy focuses on three related questions. What do we know about the prevalence of IgE autoantibodies and their targets in different diseases? What do we know about the relevance of IgE autoantibodies in different diseases? What do we know about the cellular and molecular effects of IgE autoantibodies? In addition to providing answers to these questions, based on a broad review of the literature, we outline the current gaps of knowledge in our understanding of IgE autoantibodies and describe approaches to address them.

Polymorphisms in the interleukin 4, interleukin 4 receptor and interleukin 13 genes and allergic phenotype: A case control study

PURPOSE

Interleukin 4 (IL4), interleukin 4 receptor (IL4R) and interleukin 13 (IL13) play a key role in the pathogenesis of allergy and asthma development. IL4 and IL13 strongly influence bronchial hyperreactivity in response to allergen, airway remodeling, airway inflammation and airway smooth muscle proliferation. Both IL4 and IL13 exert biologic effect via interleukin 4 receptor. The aim of this study was to evaluate the impact of the polymorphisms within interleukin 4 (rs2243250, rs2227284), interleukin 4 receptor α chain (rs1805010, rs1805011) and interleukin 13 (rs20541) genes on the incidence of allergic phenotype in Polish pediatric population.

MATERIAL/METHODS

We compared 177 asthmatic pediatric patients with 194 healthy children. Five polymorphisms within IL4, IL13 and IL4Rα genes were analyzed. Genotypes of four polymorphisms (rs2243250, rs2227284, rs1805011, rs20541) were assigned by TaqMan SNP Genotyping Assays (Applied Biosystems), whereas rs18050100 polymorphism was established using PCR-RFLP method.

RESULTS

We observed an association of rs1805011 polymorphism of IL4Rα gene with allergy (p=0.021), mild asthma (p=0.00005) and atopic dermatitis (p=0.0056). Significant correlation was found between rs20541 in IL-13 gene and the positive skin prick test results (p=0.029), along with rs2243250 polymorphism with clinical atopy (p=0.033) and rs2227284 with total IgE levels (p=0.00047). No associations were found for rs1805010.

CONCLUSIONS

Our results indicate that rs1805011 polymorphism of IL4Rα gene seems to influence allergy risk, especially mild asthma and atopic dermatitis predisposition in Polish children. Subgroup analysis of three other SNPs revealed possible influence on allergy development.

Association between polymorphisms in selected inflammatory response genes and the risk of prostate cancer

Inflammation represents an important event which facilitates prostate carcinogenesis. Genetic variations in inflammatory response genes could affect the level and function of the protein products, resulting in the differential prostate cancer risk among carriers of different variants. This study attempted to investigate the association of IL-4 rs2243250, IL-6 rs10499563, IL-8 rs4073, as well as NFKBIA rs2233406 and rs3138053 polymorphisms with prostate cancer risk in the Chinese population. Genotyping of the polymorphisms was performed by using polymerase chain reaction-restriction fragment length polymorphism technique on 439 prostate cancer patients and 524 controls, and the association of each polymorphic genotype with prostate cancer risk was evaluated by using logistic regression analysis based on allele, heterozygous, and homozygous comparison models, with adjustment to age and smoking status. We showed that the C allele of IL-4 rs2243250 polymorphism could increase prostate cancer risk (heterozygous comparison model: odds ratio [OR] =1.434, 95% confidence interval [CI] =1.092–1.881, P=0.009; homozygous comparison model: OR =2.301, 95% CI =1.402–3.775, P=0.001; allele comparison model: OR =1.509, 95% CI =1.228–1.853, P<0.001). On the other hand, the C allele of rs10499563 polymorphism could decrease prostate cancer risk (heterozygous comparison model: OR =0.694, 95% CI =0.525–0.918, P=0.010; homozygous comparison model: OR =0.499, 95% CI =0.269–0.926, P=0.028; allele comparison model: OR =0.692, 95% CI =0.553–0.867, P=0.001). No association was observed for the other polymorphisms. In conclusion, IL-4 rs2243250 and IL-6 rs10499563 polymorphisms could serve as potential predictive biomarkers for prostate cancer risk in the Chinese population.

Multifactor-dimensionality reduction reveals interaction of important gene variants involved in allergy

Elevated IgE levels in the atopic triad of asthma, allergic rhinitis and atopic dermatitis is a multifactorial condition whose genetic component involves interaction of several gene loci. One hundred and two matched pairs of allergic and nonallergic individuals were phenotyped for total serum IgE level using enzyme-linked immunosorbent assay (ELISA). Atopic status was defined by serum IgE concentration ≥100 IU mL(-1) . SNPs genotyped include the IL4 -590C>T (rs2243250), FCER1B E237G (rs569108), CD14 -159C>T (rs2569190), IL4RA Q551R (rs1801275) and ADRB2 R16G (rs1042713). Gene-gene interaction was analysed using multifactor-dimensionality reduction (MDR). Significant association between atopic allergy and the IL4 -590C>T polymorphism was confirmed in three genetic models. Interaction among the 5 gene variants was validated by MDR. The five-locus model was chosen as the best to describe the interaction of the SNPs within the context of atopy. The strongest interaction was between IL4 -590C>T and IL4RA Q551R and between FCER1B E237G and ADRB2 R16G. The IL4 variant also interacts synergistically with the FCER1B and ADRB2 coding variants. CD14 -159C>T, in general, interacts antagonistically with the rest of the SNPs. In conclusion, a five-locus interaction exists among IL4 -590C>T, FCER1B E237G, CD14 -159C>T, IL4RA Q551R and ADRB2 R16G in Filipino cases of atopic allergy.

An ADAM33 polymorphism associates with progression of preschool wheeze into childhood asthma: a prospective case-control study with replication in a birth cohort study

BACKGROUND

The influence of asthma candidate genes on the development from wheeze to asthma in young children still needs to be defined.

OBJECTIVE

To link genetic variants in asthma candidate genes to progression of wheeze to persistent wheeze into childhood asthma.

MATERIALS AND METHODS

In a prospective study, children with recurrent wheeze from the ADEM (Asthma DEtection and Monitoring) study were followed until the age of six. At that age a classification (transient wheeze or asthma) was based on symptoms, lung function and medication use. In 198 children the relationship between this classification and 30 polymorphisms in 16 asthma candidate genes was assessed by logistic regression. In case of an association based on a p<0.10, replication analysis was performed in an independent birth cohort study (KOALA study, n = 248 included for the present analysis).

RESULTS

In the ADEM study, the minor alleles of ADAM33 rs511898 and rs528557 and the ORMDL3/GSDMB rs7216389 polymorphisms were negatively associated, whereas the minor alleles of IL4 rs2243250 and rs2070874 polymorphisms were positively associated with childhood asthma. When replicated in the KOALA study, ADAM33 rs528557 showed a negative association of the CG/GG-genotype with progression of recurrent wheeze into childhood asthma (0.50 (0.26-0.97) p = 0.04) and no association with preschool wheeze.

CONCLUSION

Polymorphisms in ADAM33, ORMDL3/GSDMB and IL4 were associated with childhood asthma in a group of children with recurrent wheeze. The replication of the negative association of the CG/GG-genotype of rs528557 ADAM33 with childhood asthma in an independent birth cohort study confirms that a compromised ADAM33 gene may be implicated in the progression of wheeze into childhood asthma.

Implications of cytokine genes in allergic asthma

Asthma is a complex disease involving numerous mediator molecules and effector cells, in combination with a range of environmental determining factors. Cytokines play a key role in the physiopathological mechanisms of asthma; the study of the structure, regulation and variations of the genes that encode for these molecules is therefore crucial. Cytokines have extremely diverse roles, and exert effects both as activators and inhibitors of the innate and adaptive immune response. Certain modifications in the expression or structure of these molecules, resulting from the presence of polymorphisms, may give rise to deregulation of the mentioned effects, and therefore to a predisposition to develop concrete asthma phenotypes.

Beta2 adrenergic receptor (ADRβ2) haplotype pair (2/4) is associated with severe asthma

Background

β2 adrenergic receptor (ADRβ2) polymorphisms including ADRβ2+46G>A have been reported to cause adverse outcomes in mild asthmatics. The extent to which ADRβ2 polymorphisms and in particular their haplotypes contribute to severe asthma is unknown.

Objective

To determine the association of ADRβ2 polymorphisms and haplotypes with asthma severity.

Methods

Caucasians (n = 2979) were genotyped for 11 ADRβ2 polymorphisms. The cohort (mean age 39.6, 60% female) included 2296 non-asthmatics, 386 mild asthmatics, 172 moderate asthmatics and 125 severe asthmatics. Haplotype frequency and haplotype pair for each subject was determined using the PHASE algorithm.

Results

The three asthmatic cohorts were comparable in age and gender but were distinguishable from each other in terms of symptoms, spirometry, medication use and health care utilisation (p <0.001). None of the polymorphisms showed a genotypic or allelic association with asthma diagnosis or severity. Nine haplotypes were identified and no association was found with asthma diagnosis or severity per se. Haplotype pair 2/4 was associated with asthma severity (Trend Test, OR 1.42, p = 0.0008) but not with asthma per se. Prevalence of haplotype pair 2/2 appeared to decrease with asthma severity (Trend Test, OR 0.78, p = 0.067). Two new haplotypes were identified, occurring exclusively in asthmatics at a frequency of ≥ 1%. In addition, a positive association between carriage of ADRβ2 +523*C and increased risk of atopy was discovered.

Conclusions

ADRβ2 haplotype pair 2/4 is associated with severe asthma and is consistent with findings of poor bronchodilator response in mild asthmatics who are also haplotype 2/4.

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.

Impact of single nucleotide polymorphism in IL-4, IL-4R genes and systemic concentration of IL-4 on the incidence of glioma in Iraqi patients

Glioma is the most common and believed to be one of the most aggressive tumors of the central nervous system (CNS) in humans. Very little information is available on the etiology and pathogenesis of these tumors to date. A significant gap remains in our current understanding of the molecular pathways involved in the genesis, progression and clinical behavior of these tumors. Recently, several single nucleotide polymorphisms (SNPs) have been identified in cytokine gene sequences, particularly within the promoter region of these genes, and have been shown to be associated with the development of different types of brain tumors. The present study investigates the association of C-33T SNP in the interleukin-4 (IL-4) gene with systemic IL-4 level and the S503P SNP in the IL-4R gene with the incidence of glioma. Blood samples were collected from 100 histologically confirmed adult patients with glioma, and 30 apparently healthy individuals from the same area. DNA was extracted from each blood sample, and the IL-4 and IL-4R genes were amplified using polymerase chain reaction (PCR) with gene-specific primers. Systemic IL-4 concentration was assessed in serum samples from each participant by enzyme-linked immunosorbent assay (ELISA). We observed a negative association between the homozygous genotype (CC) of the SNP C-33T of the IL-4 gene with the incidence of glioma (OR=0.19, 95% CI=0.035-1.02), while the T allele of the SNP demonstrated a significant protective association against glioma. Similarly, the heterozygous (CT) and homozygous mutant (CC) of the SNP S503P of the IL-4R gene demonstrated a significant association with glioma development (OR=0.405, 95% CI=0.17-0.969 and OR=0.147, 95% CI=0.036-0.6 respectively), while the C allele exhibited a highly significant association with protection from glioma formation. These findings suggest that the T allele of the SNP C-33T in the IL-4 gene and the C allele of the SNP S503P in IL-4R may have a protective role against glioma development.

Gene polymorphisms of Interleukin-4 in allergic rhinitis and its association with clinical phenotypes

BACKGROUND

Allergic rhinitis (AR) is an inflammatory disorder of the upper airway. T-helper (Th)2 cytokines seems to have major roles behind the scene of unpleasant symptoms resulted from AR. Expression of interleukin (IL)-4 and its receptor could be affected by single nucleotide polymorphisms (SNPs). This study assessed the effect of 4 genetic variants within genes of IL-4 and IL-4R in AR.

METHODS

Allele frequencies of one IL-4R variant (rs1801275) and three SNPs of IL-4 (rs2243248, rs2243250, and rs2070874) were investigated in 98 patients with AR, compared to a group of controls, using PCR sequence-specific-primers (PCR-SSP) method.

RESULTS

Homozygosity for the C allele of rs2243250 in IL-4 was significantly overrepresented in the patient group. CC genotype in rs2070874 significantly was correlated with AR. GG/CC/CC and TT/TT/TT (rs2243248, rs2243250, and rs2070874) haplotypes in the IL-4 gene had a significant negative correlation with AR.

CONCLUSION

SNPs in IL-4 are associated with AR and could change the clinical picture of the disease in patients.

Immunopathogenesis of allergic disorders: current concepts

Allergic disorders are a group of immune-mediated disorders that are associated with considerable morbidity and ill health. There has been significant rise in the prevalence of allergy in the last few years. This has heightened interest in uncovering the novel mechanisms involved in etiopathogenesis of allergic disorders. Understanding the pathways underlying allergy will help in developing effective modalities for its prevention and treatment. This review focuses primarily on common IgE-mediated allergic conditions and recent developments in their immunopathogenesis, especially those involving respiratory mucosa.

Mechanisms of sustained signalling in asthma

PURPOSE OF REVIEW

The role of immunological memory formation focusing upon Th2 inflammatory responses in asthma is well supported and reviewed previously. Here, we review data supporting the establishment of a tissue-based signalling memory utilizing examples of in-vitro, in-vivo and clinical reports of sustained extracellular signal regulated kinase 1/2 (ERK1/2) activation in asthma.

RECENT FINDINGS

Endosomal recycling of receptors contributes to chronic signalling activation, presumably through increased receptor availability. This chronic signalling constitutes a bistable state and the formation of a tissue memory. The transition to chronic asthma is marked by the persistence of low-level disease severity and chronic signalling in the apparent absence of an environmental trigger.

SUMMARY

System bistability provides a mathematical explanation for a tissue-based memory. We will have to generate quantitative data about the involved biochemical reactions (substrates, products, dissociation constants of the reactions) to utilize this model. Only then will we be able to understand and interfere with a tissue memory-driven disease and curtail the persistence 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.

Respiratory syncytial virus infection and recurrent wheezing in Chilean infants: a genetic background?

Respiratory syncytial virus (RSV) infection has been associated to recurrent wheezing, but pathogenic mechanisms are unclear. Interleukin-4/Interleukin-13 (IL-4/IL-13) pathway is involved in both conditions. A common host genetic susceptibility may exist in patients whom RSV will trigger severe illness and those who develop recurrent wheezing.

OBJECTIVE

To assess, by a candidate-gene approach, whether genetic polymorphisms in IL-4/IL-13 pathway are associated with RSV infection severity and its outcome in Chilean children. A cohort of 118 RSV-infected infants was analyzed and followed for one year. Severity of acute infection and later recurrent wheezing were characterized. Alleles and genotypes frequencies were determined for two SNP in each of the genes IL-4, IL-13 and IL-4Rα. Association tests and interaction analyses were performed. Enrollment included 60 moderate and 58 severe cases. Two SNP were found associated to severity during acute infection in IL-4Rα gene (Gln551Arg, Ile50Val). The follow up was completed in 71% of patients (84/118). Later recurrent wheezing was 54% in severe group, versus 31% in moderate cases (p=0.035). In relation to outcome, allele Ile50 in IL-4Rα was more frequent in patients with moderate disease and no wheezing outcome. A common protector genotype is proposed for Chilean children: IL-4Rα Ile/Ile.

CONCLUSION

Genetic variations in the host are associated to infection severity and outcome. A common genetic background might be influencing both pathologies.

Current concepts of IgE regulation and impact of genetic determinants

Immunoglobulin E (IgE) mediated immune responses seem to be directed against parasites and neoplasms, but are best known for their involvement in allergies. The IgE network is tightly controlled at different levels as outlined in this review. Genetic determinants were suspected to influence IgE regulation and IgE levels considerably for many years. Linkage and candidate gene studies suggested a number of loci and genes to correlate with total serum IgE levels, and recently genome-wide association studies (GWAS) provided the power to identify genetic determinants for total serum IgE levels: 1q23 (FCER1A), 5q31 (RAD50, IL13, IL4), 12q13 (STAT6), 6p21.3 (HLA-DRB1) and 16p12 (IL4R, IL21R). In this review, we analyse the potential role of these GWAS hits in the IgE network and suggest mechanisms of how genes and genetic variants in these loci may influence IgE regulation.

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.

How aluminum adjuvants could promote and enhance non-target IgE synthesis in a genetically-vulnerable sub-population

Aluminum-containing adjuvants increase the effectiveness of vaccination, but their ability to augment immune responsiveness also carries the risk of eliciting non-target responses, especially in genetically susceptible individuals. This study reviews the relevant actions of aluminum adjuvants and sources of genetic risk that can combine to adversely affect a vulnerable sub-population. Aluminum adjuvants promote oxidative stress and increase inflammasome activity, leading to the release of IL-1β, IL-18, and IL-33, but not the important regulatory cytokine IL-12. In addition, they stimulate macrophages to produce PGE₂, which also has a role in regulating immune responses. This aluminum-induced cytokine context leads to a T(H)2 immune response, characterized by the further release of IL-3, IL-4, IL-5, IL-9, IL-13, and IgE-potentiating factors such as sCD23. Genetic variants in cytokine genes, such as IL-4, IL-13, IL-33, and IL-18 influence the response to vaccines in children and are also associated with atopy. These genetic factors may therefore define a genetically-vulnerable sub-population, children with a family history of atopy, who may experience an exaggerated T(H)2 immune response to aluminum-containing vaccines. IL-4, sCD23, and IgE are common factors for both atopy and the immune-stimulating properties of aluminum adjuvants. IL-4 is critical in the production of IgE and total IgE up-regulation. IL-4 has also been reported to induce the production of sCD23 and trigger resting sIgM+, sIgD+ B-cells to switch to sIgE+ B-cells, making them targets for IgE-potentiating factors. Further, the actions of IgE-potentiating factors on sIgE+ B-cells are polyclonal and unrestricted, triggering their differentiation into IgE-forming plasma cells. These actions provide a mechanism for aluminum-adjuvant promotion and enhancement of non-target IgE in a genetically vulnerable sub-population. Identification of these individuals may decrease the risk of adverse events associated with the use of aluminum-containing vaccines.

Genetic susceptibility to chronic Chagas disease: an overview of single nucleotide polymorphisms of cytokine genes

Chagas disease is a parasitic infection that is a significant public health problem in Latin America. The mechanisms responsible for susceptibility to the infection and the mechanisms involved in the development of cardiac and digestive forms of chronic Chagas disease remain poorly understood. However, there is growing evidence that differences in susceptibility in endemic areas may be attributable to host genetic factors. The aim of this overview was to analyze the genetic susceptibility to human Chagas disease, particularly that of single nucleotide polymorphisms of cytokine genes. A review of the literature was conducted on the following databases: PubMed/MEDLINE and Scopus. The search strategy included using the following terms: "Cytokines", "Single Nucleotide Polymorphisms" and "Chagas Disease". After screening 25 citations from the databases, 19 studies were selected for the overview. A critical analysis of the data presented in the articles suggests that genetic susceptibility to Chagas disease and chronic Chagas cardiomyopathy is highly influenced by the complexity of the immune response of the host. Follow-up studies based on other populations where Chagas disease is endemic (with distinct ethnic and genetic backgrounds) need to be conducted. These should use a large sample population so as to establish what cytokine genes are involved in susceptibility to and/or progression of the disease.

Identification of KIF3A as a novel candidate gene for childhood asthma using RNA expression and population allelic frequencies differences

Background

Asthma is a chronic inflammatory disease with a strong genetic predisposition. A major challenge for candidate gene association studies in asthma is the selection of biologically relevant genes.

Methodology/Principal Findings

Using epithelial RNA expression arrays, HapMap allele frequency variation, and the literature, we identified six possible candidate susceptibility genes for childhood asthma including ADCY2, DNAH5, KIF3A, PDE4B, PLAU, SPRR2B. To evaluate these genes, we compared the genotypes of 194 predominantly tagging SNPs in 790 asthmatic, allergic and non-allergic children. We found that SNPs in all six genes were nominally associated with asthma (p<0.05) in our discovery cohort and in three independent cohorts at either the SNP or gene level (p<0.05). Further, we determined that our selection approach was superior to random selection of genes either differentially expressed in asthmatics compared to controls (p = 0.0049) or selected based on the literature alone (p = 0.0049), substantiating the validity of our gene selection approach. Importantly, we observed that 7 of 9 SNPs in the KIF3A gene more than doubled the odds of asthma (OR = 2.3, p<0.0001) and increased the odds of allergic disease (OR = 1.8, p<0.008). Our data indicate that KIF3A rs7737031 (T-allele) has an asthma population attributable risk of 18.5%. The association between KIF3A rs7737031 and asthma was validated in 3 independent populations, further substantiating the validity of our gene selection approach.

Conclusions/Significance

Our study demonstrates that KIF3A, a member of the kinesin superfamily of microtubule associated motors that are important in the transport of protein complexes within cilia, is a novel candidate gene for childhood asthma. Polymorphisms in KIF3A may in part be responsible for poor mucus and/or allergen clearance from the airways. Furthermore, our study provides a promising framework for the identification and evaluation of novel candidate susceptibility genes.

Genetic regulation of parasite infection: empirical evidence of the functional significance of an IL4 gene SNP on nematode infections in wild primates

BACKGROUND

Susceptibility to parasite infection affects fitness-related processes, such as mate choice and survival, yet its genetic regulation remains poorly understood. Interleukin-4 (IL4) plays a central role in the humoral immune defence against nematode parasite infections, inducing IgE switch and regulation of worm expulsion from the intestines. The evolutionary and functional significance of single nucleotide polymorphisms (SNPs) in IL4-genes is known, yet empirical information on the effect of IL4 SNPs on gastro-intestinal infections is lacking. Using samples from a population of wild red-fronted lemurs (Eulemur fulvus rufus, Primates: Lemuridae), from western Madagascar, we explored the association of IL4-gene promoter polymorphisms with nematode infections and investigated a possible functional role of the IL4 polymorphism on male reproductive success.

RESULTS

Using sequence analyses of lemur DNA we detected a new SNP in the IL4 gene promoter area. Carriers of the genotype T/T showed higher nematode infection intensities than individuals of genotypes C/T and C/C. Genetic population analyses using data from more than 10 years, suggested higher reproductive success of T/T males than expected.

CONCLUSIONS

Our results suggest a regulatory effect of an IL4 gene promoter polymorphism on the intensity of parasite infections in a natural population of red-fronted lemurs, with a seemingly disadvantageous genotype represented in low frequencies. Long-term population analyses, however, point in the direction of a negative frequency-dependent association, giving a fitness advantage to the rare genotype. Due to low frequencies of the genotype in question conclusive evidence of a functional role of IL4 polymorphism cannot be drawn here; still, we suggest the use of IL4 polymorphism as a new molecular tool for quick assessment of individual genetic constitution with regard to nematode infection intensities, contributing to a better understanding of the actual components of the immune response that mediate protection against gastro-intestinal parasites.

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.

Does genetic regulation of IgE begin in utero? Evidence from T(H)1/T(H)2 gene polymorphisms and cord blood total IgE

BACKGROUND

Elucidation of early life factors is critical to understand the development of allergic diseases, especially those manifesting in early life such as food allergies and atopic dermatitis. Cord blood IgE (CBIgE) is a recognized risk factor for the subsequent development of allergic diseases. In contrast with numerous genetic studies of total serum IgE in children and adults, limited genetic studies on CBIgE have been conducted.

OBJECTIVE

To test the associations between functional or tagging single nucleotide polymorphisms (SNPs) in genes involved in the T(H)1/T(H)2 pathway and CBIgE in a large US inner-city birth cohort.

METHODS

CBIgE, measured by Phadia ImmnunoCAP, was analyzed as a continuous and a binary variable. The association of each SNP with the 2 outcomes was tested using tobit and logistic regression models, respectively, with adjustment for pertinent covariates, ancestral proportion, and multiple testing. Ethnic heterogeneity and gene-gene interactions were also explored.

RESULTS

Three SNPs (rs1800925, rs2069743, and rs1295686) in the IL13 gene were significantly associated with CBIgE concentration (P ≤ 6 × 10(-4), FDR-corrected P < .05). These SNPs jointly influenced CBIgE in a dose-response manner (P for trend = 9 × 10(-8)). Significant associations also were observed for SNPs in the IL-13 receptor α1 (rs5956080) and signal transducer and activator of transcription 6 (rs11172106) genes. Ethnicity-specific genetic effects were observed for SNPs in the IL5 and GATA3 genes. Several gene-gene interactions (including IL13-IL4 receptor and IL13-signal transducer and activator of transcription 6 interactions) were detected in relation to CBIgE.

CONCLUSION

Our data demonstrated that multiple SNPs were individually and jointly associated with CBIgE, with evidence of gene-gene interactions and ethnic heterogeneity. These findings suggest that genetic regulation of IgE may begin in utero.

The landscape of human genes involved in the immune response to parasitic worms

BACKGROUND

More than 2 billion individuals worldwide suffer from helminth infections. The highest parasite burdens occur in children and helminth infection during pregnancy is a risk factor for preterm delivery and reduced birth weight. Therefore, helminth infections can be regarded as a strong selective pressure.

RESULTS

Here we propose that candidate susceptibility genes for parasitic worm infections can be identified by searching for SNPs that display a strong correlation with the diversity of helminth species/genera transmitted in different geographic areas. By a genome-wide search we identified 3478 variants that correlate with helminth diversity. These SNPs map to 810 distinct human genes including loci involved in regulatory T cell function and in macrophage activation, as well as leukocyte integrins and co-inhibitory molecules. Analysis of functional relationships among these genes identified complex interaction networks centred around Th2 cytokines. Finally, several genes carrying candidate targets for helminth-driven selective pressure also harbour susceptibility alleles for asthma/allergy or are involved in airway hyper-responsiveness, therefore expanding the known parallelism between these conditions and parasitic infections.

CONCLUSIONS

Our data provide a landscape of human genes that modulate susceptibility to helminths and indicate parasitic worms as one of the major selective forces in humans.

Genetic variants in inflammation-related genes are associated with radiation-induced toxicity following treatment for non-small cell lung cancer

Treatment of non-small cell lung cancer (NSCLC) with radiotherapy or chemoradiotherapy is often accompanied by the development of esophagitis and pneumonitis. Identifying patients who might be at increased risk for normal tissue toxicity would help in determination of the optimal radiation dose to avoid these events. We profiled 59 single nucleotide polymorphisms (SNPs) from 37 inflammation-related genes in 173 NSCLC patients with stage IIIA/IIIB (dry) disease who were treated with definitive radiation or chemoradiation. For esophagitis risk, nine SNPs were associated with a 1.5- to 4-fold increase in risk, including three PTGS2 (COX2) variants: rs20417 (HR:1.93, 95% CI:1.10-3.39), rs5275 (HR:1.58, 95% CI:1.09-2.27), and rs689470 (HR:3.38, 95% CI:1.09-10.49). Significantly increased risk of pneumonitis was observed for patients with genetic variation in the proinflammatory genes IL1A, IL8, TNF, TNFRSF1B, and MIF. In contrast, NOS3:rs1799983 displayed a protective effect with a 45% reduction in pneumonitis risk (HR:0.55, 95% CI:0.31-0.96). Pneumonitis risk was also modulated by polymorphisms in anti-inflammatory genes, including genetic variation in IL13. rs20541 and rs180925 each resulted in increased risk (HR:2.95, 95% CI:1.14-7.63 and HR:3.23, 95% CI:1.03-10.18, respectively). The cumulative effect of these SNPs on risk was dose-dependent, as evidenced by a significantly increased risk of either toxicity with an increasing number of risk genotypes (P<0.001). These results suggest that genetic variations among inflammation pathway genes may modulate the development of radiation-induced toxicity and, ultimately, help in identifying patients who are at an increased likelihood for such events.

Association of STR polymorphisms in CMA1 and IL-4 with asthma and atopy: the SAPALDIA cohort

Asthma is a chronic pulmonary disorder that is characterized by airway inflammation and bronchial hyperreactivity. Several genetic loci have been associated with asthma, and some of these associations have been replicated in independent studies. However, larger population-based replication studies for the association of short tandem repeat (STR) polymorphisms with asthma are limited. In this study, we investigated the association of STR polymorphisms in genes encoding mast cell chymase (CMA1), uteroglobin (UGB), tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) with asthma and atopic phenotypes in the large population-based Swiss Cohort Study SAPALDIA. Our results show that the STR polymorphism in the CMA1 gene is associated with asthma and that this association is even stronger with atopic asthma. Similarly, we observed a weak association of the IL-4 2-allele with asthma that tended to be stronger for atopic asthma than for nonatopic asthma. This minor IL-4 2-allele was also associated with higher IgE levels, with a higher risk for a positive skin prick test and with a trend for a higher risk for bronchial hyperresponsiveness. These results support previous findings suggesting a role for CMA1 and IL-4 in atopic asthma and for IL-4 in atopy in general.

Genetic associations with asthma and virus-induced wheezing: a systematic review

Various wheezing phenotypes can be identified based on differences in natural histories, risk factors and responses to treatment. In epidemiologic studies, atopic asthma or virus-induced wheezing can be discriminated by the presence or the absence of sensitization to allergens. Children with asthma have been shown to present lower levels of lung function. Patients with viral respiratory infections evolve from normal lung function to enhanced airway reactivity. The objective of this study was to identify genes and polymorphisms associated with different wheezing phenotypes. Using data obtained from the Genetic Association Database, we systematically reviewed studies on genes and polymorphisms that have been associated with virus-induced wheezing or atopic asthma. The research was carried out in February of 2009. Genes associated with the studied outcomes in more than three studies were included in the analysis. We found that different genes and loci have been associated with virus-induced wheezing or atopic asthma. Virus-induced wheezing has frequently been associated with IL-8 polymorphisms, whereas atopic asthma and atopy have frequently been associated with Th2 cytokine gene (CD14 and IL-13) polymorphisms on chromosome 5. This review provides evidence that different wheezing disorders in childhood can be differently affected by genetic variations, considering their role on airway inflammation and atopy. Future studies of genetic associations should consider the different wheezing phenotypes in infancy. In addition, stratified analyses for atopy can be useful for elucidating the mechanisms of the disease.

Association of IL-4 and ADAM33 gene polymorphisms with asthma in an Indian population

There are more than 100 candidate genes of asthma located on 23 human chromosomes. Interleukin-4 (IL-4), located on chromosome 5q31, and ADAM33, located on chromosome 20p13, and some single nucleotide polymorphisms (SNPs) of these genes have been shown to be associated with asthma and its manifestations in different populations. The most prominent SNPs of IL-4 and ADAM33 are 589C>T and 400A>G, respectively. There are also controversial reports on the association of these SNPs with asthma. In the present study, we analyzed these two SNPs in 100 patients with asthma and 50 controls through PCR amplification and restriction digestion to evaluate association of these two SNPs with asthma. The nonsignificant differences were observed for the IL-4 promoter polymorphism C589T and the ADAM33 T1 polymorphism between asthmatic patients and controls (P = 0.638 and 0.943, respectively). Our data revealed that there is no association of these SNPs with asthma indicating that other SNPs of these genes or other genes might be involved in the manifestation of asthma.

Genetic variants in inflammation pathway genes and asthma in glioma susceptibility

Single nucleotide polymorphisms (SNPs) in inflammation-related genes have previously been shown to alter risks of developing various cancers. However, the effects of such SNPs on glioma risk remain unclear. We used a multistrategic approach to elucidate the relationship between glioma risk, asthma/allergies, and 23 literature-based functional SNPs in 11 inflammation genes. Genotyping was conducted on 373 histologically confirmed adult glioma patients and 365 cancer-free controls from the Harris County Brain Tumor Study. Deviations from the Hardy-Weinberg equilibrium were assessed using the chi(2)-test, and Akaike's information criterion was used to determine the best genetic model for each SNP. Odds ratios (ORs) were calculated both for each SNP individually and for grouped analyses, examining the effects of the numbers of adverse alleles on glioma risk in participants with and without asthma. In the single-locus analysis of the 23 examined SNPs, 1 pro-inflammatory and 2 anti-inflammatory gene SNPs were significantly associated with glioma risk (COX2/PTGS2, rs20417 [OR = 1.41]; IL10, rs1800896 [OR = 1.57]; and IL13, rs20541 [OR = 0.39], respectively). When we examined the joint effects of the risk-conferring alleles of these 3 SNPs, we found a significant trend indicating that the risk increases as the number of adverse alleles increase (P = .005). Stratifying by asthma status, we found that this dose-response-like trend of increasing risk is only present among those without asthma/allergies (P < .0001). Our study indicates that polymorphisms in inflammation genes are associated with glioma susceptibility, especially when a history of asthma/allergies is absent.

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.

Sequencing the IL4 locus in African Americans implicates rare noncoding variants in asthma susceptibility

BACKGROUND

Common genetic variations in the IL4 gene have been associated with asthma and atopy in European and Asian populations, but not in African Americans.

OBJECTIVE

Because populations of African descent have increased levels of genetic variation compared with other populations, particularly with respect to low frequency or rare variants, we hypothesized that rare variants in the IL4 gene contribute to the development of asthma in African Americans.

METHODS

To test this hypothesis, we sequenced the IL4 locus in 72 African Americans with asthma and 70 African American controls without asthma to identify novel and rare polymorphisms in the IL4 gene that may be contributing to asthma susceptibility.

RESULTS

We report an excess of private noncoding single nucleotide polymorphisms (SNPs) in the subjects with asthma compared with control subjects without asthma (P = .031). Tajima's D is significantly more negative in subjects with asthma (-0.375) than controls (-0.073; P = .04), reflecting an excess of rare variants in the subjects with asthma.

CONCLUSION

Our findings indicate that SNPs at the IL4 locus that are potentially exclusive to African Americans are associated with susceptibility to asthma. Only 3 of the 26 private SNPs (ie, SNPs present only in the subjects with asthma or only in the controls) are tagged by single SNPs on one of the common genotyping platforms used in genome-wide association studies. We also find that most of the private SNPs cannot be reliably imputed, highlighting the importance of sequencing to identify genetic variants contributing to common diseases in African Americans.

Oct-1 is responsible for the C-33T polymorphism effect in the IL-4 promoter

IL-4 is a pleiotropic immunoregulatory cytokine secreted by Th2 subset of CD4(+) Th cells. Several transcription factors (TFs) have been determined with various degrees of certainty to bind the IL-4 promoter and to regulate its expression in human. To investigate the mechanisms responsible for phenotypic effects of the C-33T IL-4 promoter polymorphism, we performed a search of TFs binding to this promoter locus and discriminating the -33C and -33T alleles. In silico searches suggest few factors bind this region. Using an electromobility shift assay we found that Jurkat T cells contained proteins which specifically interacted with oligonucleotide probes, corresponding to the -33 region. Considerable binding differences between C and T alleles were demonstrated using competitive conditions, the proteins bound predominantly with -33C allele. We found that the transcription factor Oct-1 produced the major shifted complex. The binding of Oct-1 was not improved using activated nuclear extracts; however, we observed increases in other shifted complexes upon cell activation. We suppose that Oct-1 occupancy may compete for binding of activator proteins to closely or overlapped binding sites. Our findings suggest that the interplay between Oct-1 and unknown TFs may be responsible for the C-33T polymorphism effects.

Genetic variants in immunoregulatory genes and risk for childhood lymphomas

To investigate whether single nucleotide polymorphisms (SNPs) in key cytokine and innate immunity genes influence risk for childhood lymphomas, we genotyped 37 children with Hodgkin's (HL) and 48 with non-Hodgkin's lymphoma (NHL), aged (1 month-14 yr), along with their 85 age- and gender-matched controls suffering from mild medical conditions. Genotypic analysis was performed for 10 SNPs from nine genes with important role in immunoregulatory pathways (IL4, IL4R, IL6, IL10, IL12, IL18, TNFalpha, IFNgamma, CD14). Analysis of SNPs genotypes revealed that the CD14 -159 C>T polymorphism was associated with significantly increased risk for HL regarding both the CC and CT genotypes (OR(CC): 5.36; 95% CI, 1.30-22.14; P = 0.02, OR(CT): 3.76; 95% CI, 1.00-14.16; P = 0.05). An indicative association between IL18-137 G>C polymorphism with the CC genotype and NHL did not reach, however, statistical significance (OR(CC), 3.78; 95% CI, 0.87-16.38; P = 0.08). In conclusion, our findings suggest that genetic variation in the CD14-159 loci may be associated with childhood HL risk; these preliminary findings need to be further confirmed in sizeable multi-centre studies along with determination of cytokines, which could provide an insight on the biologic basis underlying these findings.

Genetic variation in CRTh2 influences development of allergic phenotypes

BACKGROUND

Allergic disorders are characterized by an increase in the Th2 cytokines IL-4, IL-5 and IL-13, produced primarily by Th2 cells. These cells are marked by the expression of CRTh2 (chemoattractant receptor-homologous molecule expressed on Th2 cells), a receptor for prostaglandin D(2). As genetic variation plays a significant role in the predisposition for allergic disorders, we investigated the influence of single nucleotide polymorphisms (SNPs) in CRTh2.

METHODS

In a large study population of German children (n = 4264) from the International Study of Asthma and Allergy in Children (ISAAC II), six polymorphisms in CRTh2 were genotyped. Statistical analyses were performed using single SNP and haplotype analyses.

RESULTS

Uncorrected associations among -6373G>A, +1431G>C and +1538A>G were observed with a number of allergic phenotypes (P < 0.05). After correction, association between +1431C and specific IgE to food allergens remained significant (P = 0.04). Associations of haplotype (H)3 (containing +1538G) with reduced risk for asthma and H2 (containing +1431C) with increased risk for specific IgE to food allergens also remained significant after correction for multiple testing (P = 0.004).

CONCLUSIONS

Genetic variation within CRTh2 modifies the development of allergic sensitization and asthma in a population of German children.

Clustering of (auto)immune diseases with early-onset and complicated inflammatory bowel disease

Studies in adult inflammatory bowel disease (IBD) patients have highlighted associations with genetic and serologic markers and suggest an association with disease location, behaviour and natural history. Data on patients with Crohn's disease (CD, n=80), ulcerative colitis (UC, n=15) and indeterminate colitis (n=4) were collected. All individuals were analysed for CARD15 R702W, G908R and L1007fs for toll-like receptor 4 (TLR4) Asp299Gly and for anti-Saccharomyces cerevisiae antibodies (ASCA) and atypical perinuclear antineutrophil cytoplasmatic antibodies (pANCA). After a mean of 10.7 years of follow up, the disease behaviour changed in 45% of CD patients, in contrast to disease location, where only 12.5% had a change (p<0.001). The younger the age at diagnosis, the more patients presented with colonic disease (p=0.021). Also, more TLR4 Asp299 Gly variants were found when the age at onset was younger (p=0.018). A large number of concomitant diseases were observed. There was no difference in the prevalence of TLR4 variants nor ASCA or pANCA between the patients with or without concomitant diseases. Patients who progressed more often needed surgery as compared to patients who remained free of stenosing or fistulising disease (27/32 or 84% versus 3/35 or 8.6%, respectively, p<0.0001) and more often had concomitant immune-mediated diseases and a trend for more seroreactivity towards ASCA.

The -589C>T polymorphism in the interleukin-4 gene (IL-4) is associated with a reduced risk of myocardial infarction in young individuals

BACKGROUND

Inflammatory reactions contribute to the development of arterial disease. We investigated the role of interleukin-4 (IL-4) in the development of myocardial infarction (MI) by genotyping patients with MI and control subjects for the -589C>T (rs2243250) single nucleotide polymorphism (SNP), which tags a functional haplotype of IL-4.

METHODS AND RESULTS

Study of Myocardial Infarctions Leiden (SMILE) included 560 men with a first MI and 646 control subjects. The Valencia study included 305 patients with MI at T genotype was found [odds ratio (OR) 0.84; 95% CI 0.37-1.95 for -589TT and 0.82; 95% CI 0.62-1.07 for -589CT compared with -589CC]. In patients younger than 50 years, carriership of one or two -589T alleles was associated with a reduced risk of MI (OR 0.57: 95% CI 0.34-0.95). This result was replicated in the Valencia study, where carriers of one or two -589T alleles had a reduced risk of MI (OR 0.67: 95% CI 0.47-0.95), with a strong protective effect of the -598T allele in homozygous -589T (OR 0.33: 95% CI 0.10-1.05). In the control subjects of the Valencia study, the -589T allele was associated with reduced levels of F1+2.

CONCLUSION

Our data indicate that the IL-4 haplotype tagged by the -589T allele reduces the risk of MI in young individuals.

Pathogenesis of allergic bronchopulmonary aspergillosis in cystic fibrosis: current understanding and future directions

Allergic bronchopulmonary aspergillosis (ABPA) is an allergic disease characterized clinically by wheezing, pulmonary infiltrates, bronchiectasis, and fibrosis that affects patients with asthma and cystic fibrosis (CF). Although this disease has been characterized by a Th2 immune response to Aspergillus, the disease has some features such as central bronchiectasis which is not seen in other Th2 driven lung diseases such as atopic asthma. Here we will review the current pathophysiology of ABPA in CF and highlight new molecules that may affect immune responses against Aspergillus and ABPA disease pathogenesis.