Polymorphisms in the IL-13 and IL-4R genes are associated with the development of renal cell carcinoma

BACKGROUND

Cytokines are the important modulators that bind to their relevant receptors in response to some stimuli to mediate the homeostasis. It has been suggested that the imbalance of immune system of the host might affect the generation of diseases, including cancers.

PATIENTS AND METHODS

We investigated the association between six functional polymorphisms of IL-4, IL-13, and IL-4R genes and susceptibility to renal cell cancer in a hospital-based study, including 620 renal cell carcinoma (RCC) patients and 623 controls. Logistic regression model was used to assess the genetic effects on the development of RCC.

RESULTS

Overall, individuals with IL-4R Ile50Val CT/TT genotypes had a 0.34-fold significantly decreased RCC risk (CT/TT versus CC), and the T variant allele was associated with a decreased risk of RCC in a dose-response manner (Ptrend=0.009). In addition, we also observed that IL-13 C-1055T and Arg130Gln polymorphisms could decrease the risk of RCC [TT versus

CC/CT

odds ratio=0.36, 95% confidence interval (CI)=0.16-0.78; AA versus GG/GA: 0.66, 0.44-0.97, respectively]. Furthermore, a multiplicative interaction association between the combined IL-4R Ile50Val and IL-13 C-1055T genotypes was observed to decrease the risk of RCC (P=0.036).

CONCLUSION

IL-13 and IL-4R may play an important role in the etiology of RCC.

The differences in the involvements of loci of promoter region and Ile50Val in interleukin-4 receptor α chain gene between atopic dermatitis and Japanese cedar pollinosis

BACKGROUND

Atopic dermatitis (AD) and Japanese cedar pollinosis (JCP) are common chronically allergic diseases associated with the activation of T-helper 2 cells. Recent studies have shown that polymorphisms in the genes for IL-4 receptor α chain (IL4RA) may contribute to susceptibility of AD and JCP, although the differences in the involvements of loci of IL4RA gene between AD and JCP are unclear. In this study, we investigated the role of polymorphisms in IL-4RA gene in conferring susceptibility to the development of AD and/or JCP using a family analysis and an association analysis in a Japanese population.

METHODS

Five polymorphisms in the IL-4RA gene, C-3223T, T-1914C, T-890C, Ile50Val and Glu375Ala, have been genotyped using PCR-based methods in 75 trios families, including 15 AD families, 30 JCP families, and 30 families with combination of AD and JCP in the family analysis. Forty-five AD, 60 JCP and 125 control children constituted the association study.

RESULTS

The transmission disequilibrium test showed that the allele of Ile50 was significantly transmitted to children with JCP alone (p < 0.05). Haplotype analysis showed that the -3223T/Ile50 haplotype was preferentially transmitted to both AD (p < 0.01) and JCP children (p < 0.01), while that the C-3223/Ile50 haplotype was preferentially transmitted to only JCP children (p < 0.01). The association study showed that -3223T and haplotype of -3223T/Ile50 were associated with AD children, but not with JCP. Ile50 was associated with both AD and JCP.

CONCLUSIONS

Our data suggest that -3223T and the -3223T/Ile50 haplotype were risk factors for AD. Ile50 allele seems to be involved in both JCP and AD. Interactions of the IL-4RA loci may play a role both conferring susceptibility and modulating severity of AD.

A predictive model of the association between gene polymorphism and the risk of noise-induced hearing loss caused by gunfire noise

BACKGROUND

Noise-induced hearing loss (NIHL) is one of the common diseases in otology. In general, we assume that most people who are exposed to loud noise constantly, e.g., soldiers, will suffer from hearing loss. Hearing loss is related to the gene polymorphisms, with the Wolfram syndrome type 1 gene (T2500C), interleukin-4 receptor α chain (Q576R) and chloride channel-Kb (T481S) polymorphisms being most related to NIHL.

METHODS

We analyzed the association between the polymorphisms and the risk of NIHL in 119 subjects who were exposed to the same loud gunfire. In the current study, 39 persons with hearing loss and 80 with normal hearing were recruited from military officers and soldiers that were exposed to gunfire.

RESULTS

The results showed that the genetic variation of Wolfram syndrome type 1 gene was a more crucial factor than other genes in causing hearing loss. There was a significant difference (p=0.027) in WFS1 (T2500C) polymorphism between NIHL subjects and controls.

CONCLUSION

In this study, we found that although loud noise could usually result in hearing damage, the clinical characteristics of hearing loss were irrelevant to gunfire noise. The gene polymorphisms provide predictors for us to evaluate the risk of NIHL prior to gunshot training.

The role of CD23 in IgE dependent signaling: implications from pharmacogenetics

The association of immunoglobulin E (IgE) with allergic diseases and asthma is well established. IgE binds to two receptors on various immune and inflammatory cells. The lower-affinity IgE Fc receptor, CD23, has multiple functions in enhancing the regulation of IgE production itself, and that of various pro-inflammatory activities and mediators. The data in this report are derived from an analysis of variation in the CD23 gene that leads to a coding exchange and to a single nucleotide polymorphism (SNP) associated with the substitution of an arginine residue for a tryptophan residue in the protein structure of CD23. This genetic variation is associated with three findings identified in this report. First, the tryptophan exchange is associated with greater expression of RNA for the interleukin (IL)-4 receptor alpha chain and greater expression of RNA for egr-1 transcription factor, both of which are proinflammatory gene products that influence allergy-related immune functions. Second, the exchange is associated with cell surface expression of IL-4R. Third, an analysis of potential arginine-to-tryptophan exchanges in the entire human genome has identified a number of interesting exchanges in immunologic genes of interest for their role in allergic responses. A discussion of these three findings is presented.

[Meta-analysis on interleukin-4 receptor α chain Q576R gene polymorphisms and bronchial asthma susceptibility]

OBJECTIVE

to study the association between interleukin-4 receptor α chain (IL-4RA) Q576R polymorphisms and bronchial asthma susceptibility by Meta-analysis.

METHODS

four medical databases, including Pubmed, Embase, CNKI and Wanfang, were searched for the case-control studies about the IL-4RA polymorphisms and bronchial asthma susceptibility. Odds ratios (OR) of IL-4RA Q576R genotype distributions in asthma patients against healthy controls were analyzed in both RR vs QR + QQ model and QR + RR vs QQ model. Analyses were performed for asthma in general and for subgroups based on the atopy status of the asthma population. The sensitivity analysis and the publication bias tests were conducted.

RESULTS

fifteen case-control studies, with 2675 asthma cases, 1202 atopic asthma cases and 331 nonatopic asthma cases respectively, were identified and all control group genotype frequencies were consistent with Hardy-Weinberg equilibrium. In genotype RR vs QR + QQ model no heterogeneity among the studies was found, while in genotype QR + RR vs QQ model, heterogeneity among these studies was found. These studies were analyzed by fixed-effect model (RR vs QR + QQ model) or random-effect model (QR + RR vs QQ model). The pooled odds ratio of IL-RA Q576R genotype RR vs QR + QQ was 2.02 (95%CI: 1.53 - 2.66), and the pooled odds ratio in this model in the atopic asthma subgroup was 2.26 (95%CI: 1.47 - 3.49), while the pooled odds ratio (QR + RR vs QQ model) was 1.02 (95%CI: 1.06 - 1.53).

CONCLUSION

a meta-analysis of results from case-control studies strongly supports the conclusion that IL-4RA Q576R polymorphisms impart a modest yet significant risk for asthma.

[Syntropic genes of allergic diseases]

Common (syntropic) genes of allergic diseases (ADs) HLA-DQB1, HLA-DRB1, IL4, IL4RA, MS4A2, HLA-DQA1, LTC4S, IL13, IL10, and TGFBL have been identified on the basis of information from the HuGENet internet database. The functional sphere of competence of these genes is associated mainly with the initiation and regulation of an immune response and inflammation. Importance of these processes in the development of ADs is underlined. The results of cluster analysis of allergic diseases obtained using the data on common genes predisposing to their development are presented. Genetic clusterization ofADs confirms their accepted clinical classification.

Differential requirements for interleukin (IL)-4 and IL-13 in protein contact dermatitis induced by Anisakis

BACKGROUND

Exposure to antigens of the fish parasite Anisakis is associated with the development of protein contact dermatitis in seafood-processing workers. Understanding the basic mechanisms controlling allergic sensitization through the skin is critical for designing therapies that will prevent the progression of allergic disease.

OBJECTIVE

To investigate the roles of interleukin (IL)-4, IL-13 and the IL-4Ralpha in both local skin pathology and systemic sensitization following epicutaneous exposure to Anisakis proteins.

METHODS

BALB/c wild-type (WT) mice and mice deficient in IL-4, IL-13 or IL-4 and IL-13, as well as mice with cell-specific impairment of IL-4Ralpha expression, were sensitized to Anisakis antigen by repeated epicutaneous application of Anisakis extract. Following this sensitization, skin pathology was recorded and systemic responses were investigated. Intravenous challenge with Anisakis extract was performed to test for the development of biologically relevant systemic sensitization.

RESULTS

In WT mice, epicutaneous sensitization with Anisakis larval antigens induced localized inflammation, epidermal hyperplasia, production of T(H)2 cytokines, antigen-specific IgE and IgG1. Intravenous challenge of sensitized mice resulted in anaphylactic shock. Interestingly, IL-13 deficient mice failed to develop epidermal hyperplasia and inflammation, whilst anaphylaxis was reduced only in strains deficient either in IL-4 only, or deficient in IL-4 and IL-13 concurrently, as well as in mice deficient in IL-4Ralpha or with impaired IL-4Ralpha expression on CD4(+) T cells.

CONCLUSIONS

Interleukin-13 plays a central role in protein contact dermatitis associated with repeated epicutaneous exposure to Anisakis extract, whereas IL-4 drives systemic sensitization and resultant anaphylactic shock.

Polymorphisms in IL4 and iLARA confer susceptibility to asthma

BACKGROUND

Asthma is a complex disease that is caused by genetic and environmental factors. The production of interleukin (IL)-4, which can influence mast cell responsiveness to immunoglobulin (Ig) E--mediated signaling, could be modified by genetic variants in the IL-4 promoter.

OBJECTIVE

To investigate the association between the IL-4 and IL-4RA promoter polymorphisms and asthma in a sample of Iranian patients.

METHODS

We used polymerase chain reaction with sequence-specific primers to investigate the allele and genotype frequencies of 2 polymorphic genes coding for IL-4 and IL-4RA in 59 Iranian patients with asthma and 139 healthy controls.

RESULTS

The most frequent genotypes in the patient group were IL-4TC (-590), IL-4TC (-33), IL-4 GT (-1098), and IL-4RA GA (+1902). In contrast, the frequencies of IL-4 CC (-590), IL-4 CC (-33), IL-4TT (-1098), and IL-4RAAA (+1902) were significantly lower in the patient group than in the control group. The most frequent haplotypes in our patients were IL-4 TCT and GTC at positions -1098,-590,-33. The mean total serum IgE level in patients with the TTT/GCC genotype was 258.8 IU/mL, which was significantly higher than the 95.4 IU/mL observed for other genotypes.

CONCLUSION

We showed a strong association between the polymorphisms of the IL-4 gene promoter at positions -590, -33 and -1098 and bronchial asthma. We also demonstrated an association between their haplotypes and serum total IgE.

Study of gene-gene interactions for endophenotypic quantitative traits in Chinese asthmatic children

BACKGROUND

Asthma is a complex disease resulting from interactions between multiple genes and environmental factors. Study of gene-gene interactions could provide insight into the pathophysiology of asthma.

METHODS

We investigated the interactions among 18 single-nucleotide polymorphisms in eight candidate genes for plasma total immunoglobulin E (IgE) concentration and peripheral blood (PB) eosinophil count in 298 Chinese asthmatic children and 175 controls. Generalized multifactor dimensionality reduction and generalized linear model were used to analyze gene-gene interactions for the quantitative traits.

RESULTS

A significant interaction was found between R130Q in IL13 and I50V in IL4RA for plasma total IgE concentration, with a cross-validation (CV) consistency of nine of 10 and a prediction error of 41.1% (P = 0.013). Plasma total IgE concentration was significantly higher in the high-risk than the low-risk groups (P < 0.0001). For PB eosinophil count, significant interaction was found between C-431T in TARC and RsaI_in2 in FCERIB, with a CV consistency of nine of 10 and a prediction error of 40.2% (P = 0.009). PB eosinophil count was significantly higher in the high-risk group than the low-risk groups (P < 0.0001). Generalized linear model also revealed significant gene-gene interaction for the above two endophenotypes with P = 0.013 for plasma total IgE concentration and P = 0.029 for PB eosinophil count respectively.

CONCLUSIONS

Our data suggest significant interactions between IL13 and IL4RA for plasma total IgE concentration, and this is the first report to show significant interaction between TARC and FCERIB for PB eosinophil count in Chinese asthmatic children.

[Genetics factors determining predisposition to chronic course of virus hepatitis and fibrosis in liver]

Polymorphic variants of several genes IL4 C(-590)T, IL4RA Ile50Val, TNF G(-308)A were studied for their association with extent of the disease chronization which is marked by hepatic fibrosis stage. Gradual decrease in A allele frequency of polymorphic marker G(-308)A in TNF gene, from patients with weak fibrosis to patients with cirrhosis. Group of patients with weak fibrosis was characterized by higher frequency of A allele (24.5%) comparing with patients with moderate and pronounced fibrosis (13.4%) and cirrhosis (8.7%). Differences in heterozygous genotype frequencies of IL4 C(-590)T were found between patients with cirrhosis (68.2%) and groups of patients with moderate and marked fibrosis (39.1%).

CD4+ T cell-specific deletion of IL-4 receptor alpha prevents ovalbumin-induced anaphylaxis by an IFN-gamma-dependent mechanism

IL-4Ralpha-mediated STAT6 activation serves an essential role in various animal models of allergy and asthma at both the sensitization and effector phases. IL-4 and IL-13 signaling via the IL-4Ralpha chain exacerbates murine anaphylaxis, but the cell-specific requirements for IL-4Ralpha expression are unclear. The purpose of this study was to elucidate the mechanisms of systemic anaphylaxis to OVA in gene-targeted mice with a deletion of the IL-4Ralpha chain in the macrophage/neutrophil or CD4+ T lymphocyte population. Results demonstrated that anaphylaxis in this model was entirely dependent upon the FcgammaRII/III and was associated with mast cell degranulation. Expression of the IL-4Ralpha on CD4+ T cells, but not macrophages or neutrophils, was critical for severe anaphylaxis, characterized by diarrhea, hypothermia, and death. Ab depletion experiments demonstrated that IFN-gamma protected against mortality and severe intestinal pathology despite the presence of Ag and specific Ab. This protection was associated with reduced levels of mast cell protease, a marker of mast cell degranulation, suggesting that IFN-gamma may inhibit mast cell degranulation in vivo. These data suggest that it may be possible to limit the severity of anaphylaxis using rational therapies designed to increase numbers of IFN-gamma-producing cells by targeting IL-4Ralpha signaling in CD4+ T lymphocytes.

Confirmation of an Association Between the TNF(−308) Promoter Polymorphism and Stroke Risk in Children With Sickle Cell Anemia

Background and Purpose— The etiology of stroke in children with sickle cell anemia (SCA) is complex and poorly understood. Growing evidence suggests that genetic factors beyond the sickle cell mutation influence stroke risk in SCA. We previously reported risk associations with polymorphisms in several proinflammatory genes in SCA children with ischemic stroke. The aim of this replication study was to confirm our previous findings of associations between the TNF(−308) G/A, IL4R 503 S/P, and ADRB2 27 Q/E polymorphisms and large vessel stroke risk.

Methods— Using previously collected MRA data, we assessed an independent population of SCA children from the multicenter Stroke Prevention Trial in Sickle Cell Anemia (STOP) for the presence or absence of large vessel stenosis. Samples were genotyped for 104 polymorphisms among 65 candidate vascular disease genes. Genotypic associations with risk of large vessel stroke were screened using univariable analysis and compared with results from our original study. Joint analysis of the 2 study populations combined was performed using multivariable logistic regression.

Results— A total of 96 children (49 MRA-positive, 47 MRA-negative) were included in this study. Of the SNP associations previously identified in the original study, the TNF(−308) G/A association with large vessel stroke remained significant and the IL4R 503 S/P variant approached significance in the joint analysis of the combined study populations. Consistent with our original findings, the TNF(−308) GG genotype was associated with a >3-fold increased risk of large vessel disease (OR=3.27; 95% CI=1.6, 6.9; P =0.006). Unadjusted analyses also revealed a previously unidentified association between the LTC4S(−444) A/C variant and large vessel stroke risk.

Conclusions— Similar findings in 2 independent study populations strongly suggest that the TNF(−308) G/A promoter polymorphism is a clinically important risk factor for large vessel stroke in children with SCA. The previously observed association with the IL4R 503 S/P variant and the novel association with the LTC4S(−444) A/C variant suggest that these loci may also contribute to large vessel stroke risk in children with SCA.

Deletion of IL-4Ralpha on CD4 T cells renders BALB/c mice resistant to Leishmania major infection

Effector responses induced by polarized CD4⁺ T helper 2 (Th2) cells drive nonhealing responses in BALB/c mice infected with Leishmania major. Th2 cytokines IL-4 and IL-13 are known susceptibility factors for L. major infection in BALB/c mice and induce their biological functions through a common receptor, the IL-4 receptor α chain (IL-4Rα). IL-4Rα–deficient BALB/c mice, however, remain susceptible to L. major infection, indicating that IL-4/IL-13 may induce protective responses. Therefore, the roles of polarized Th2 CD4⁺ T cells and IL-4/IL-13 responsiveness of non-CD4⁺ T cells in inducing nonhealer or healer responses have yet to be elucidated. CD4⁺ T cell–specific IL-4Rα (Lck^creIL-4Rα^−/lox) deficient BALB/c mice were generated and characterized to elucidate the importance of IL-4Rα signaling during cutaneous leishmaniasis in the absence of IL-4–responsive CD4⁺ T cells. Efficient deletion was confirmed by loss of IL-4Rα expression on CD4⁺ T cells and impaired IL-4–induced CD4⁺ T cell proliferation and Th2 differentiation. CD8⁺, γδ⁺, and NK–T cells expressed residual IL-4Rα, and representative non–T cell populations maintained IL-4/IL-13 responsiveness. In contrast to IL-4Rα^−/lox BALB/c mice, which developed ulcerating lesions following infection with L. major, Lck^creIL-4Rα^−/lox mice were resistant and showed protection to rechallenge, similar to healer C57BL/6 mice. Resistance to L. major in Lck^creIL-4Rα^−/lox mice correlated with reduced numbers of IL-10–secreting cells and early IL-12p35 mRNA induction, leading to increased delayed type hypersensitivity responses, interferon-γ production, and elevated ratios of inducible nitric oxide synthase mRNA/parasite, similar to C57BL/6 mice. These data demonstrate that abrogation of IL-4 signaling in CD4⁺ T cells is required to transform nonhealer BALB/c mice to a healer phenotype. Furthermore, a beneficial role for IL-4Rα signaling in L. major infection is revealed in which IL-4/IL-13–responsive non-CD4⁺ T cells induce protective responses.

Leishmaniasis is a disease induced by a protozoan parasite and transmitted by the sandfly. Several forms of infection are identified, and the different diseases have wide-ranging symptoms from localized cutaneous sores to visceral disease affecting many internal organs. Animal models of human cutaneous leishmaniasis have been established in which disease is induced by infecting mice subcutaneously with Leishmania major. Different strains of inbred mice have been found to be susceptible or resistant to L. major infection. “Healer” C57BL/6 mice control infection with transient lesion development. The protective response to infection in this strain is dominated by type 1 cytokines inducing parasite killing by nitric oxide. Conversely, “nonhealer” BALB/c mice are unable to control infection and develop nonhealing lesions associated with a dominant type 2 immune response driven by cytokines IL-4 and IL-13. However, mice deficient in IL-4/IL-13 signaling are not protected against development of cutaneous leishmaniasis. Here we describe a BALB/c mouse where the ability to polarize to a dominant type 2 response is removed by cell-specific deletion of the receptor for IL-4/IL-13 on CD4⁺ T cells. These mice are resistant to L. major infection similar to C57BL/6 mice, which highlights the role of T helper 2 cells in driving susceptibility and the protective role of IL-4/IL-13 signaling in non-CD4⁺ T cells in BALB/c mice.

Association between Q551R IL4R genetic variants and atopic asthma risk demonstrated by meta-analysis

BACKGROUND

IL4R, the gene encoding the alpha chain of the IL-4 and IL-13 receptors, has received extensive attention as a candidate gene for asthma risk. However, the results from studies testing for associations of the I50V and Q551R IL4R genetic variants are conflicting.

OBJECTIVE

We sought to determine the average risk of asthma associated with the I50V and Q551R IL4R variants based on the results of case-control studies reported in the literature.

METHODS

Meta-analyses were performed with data from case-control association studies that met specified inclusion criteria (9 and 8 studies for I50V and Q551R, respectively). Random-effects models were used to calculate combined odds ratios (ORs) and significance of associations. Analyses were performed for asthma in general and for subgroups based on the atopy status of the asthma population.

RESULTS

The R551 IL4R variant was significantly associated with increased risk of asthma, most notably atopic asthma (combined OR, 1.6; P = .004). Exclusion of the outlier study reporting an OR of less than 1 greatly increased the significance of association (OR, 1.8; P = 3 x 10(-9)). I50V variants were not significantly associated with asthma.

CONCLUSIONS

A meta-analysis of results from case-control studies strongly supports the conclusion that the R551 IL4R variant imparts a modest yet significant risk for atopic asthma.

CLINICAL IMPLICATIONS

Knowledge that the R551 IL4R variant is associated with increased asthma risk should provide a basis for understanding the heterogeneity of asthma pathogenesis and for pharmacogenetic approaches to treat individuals carrying this variant.

Polymorphisms of interleukin (IL)-4 receptor alpha and signal transducer and activator of transcription-6 (Stat6) are associated with increased IL-4Ralpha-Stat6 signalling in lymphocytes and elevated serum IgE in patients with Graves' disease

Activated interleukin (IL)-4Ralpha stimulates production of IgE through signal transducer and activator of transcription-6 (Stat6) activation in lymphocytes. Genetic studies have shown an association between polymorphisms in the genes encoding IL-4Ralpha and Stat6 and elevated serum IgE in patients with atopic disease. Some authors, including us, have reported an association of Graves' disease and elevated serum IgE. To analyse the relationship between IL-4Ralpha and Stat6 polymorphisms and elevated serum IgE in patients with Graves' disease, 169 patients with Graves' disease were studied. We investigated whether these polymorphisms affect IL-4Ralpha-Stat6 signalling in cultured human lymphocytes. A high frequency of both the Ile50 polymorphism in IL-4Ralpha and 13GT repeat variants of the Stat6 gene was observed in patients with Graves' disease and elevated serum IgE (Ile50 allele; P < 0.05, 13GT allele; P < 0.01 versus controls) but not in subjects with normal IgE. Cultured human lymphocytes with the Ile50 IL-4Ralpha polymorphism and the 13GT repeat variant of Stat6 showed increased IL-4 (and/or IL-13)-induced Stat6 activation (2.7-fold; P < 0.05 and 2.2-fold; P < 0.05, respectively). These findings suggest that polymorphisms in the IL-4Ralpha and Stat6 genes play an important role in elevation of serum IgE through increased Stat6 action in patients with Graves' disease.

Interaction between variants in the interleukin-4 receptor alpha and interleukin-9 receptor genes in childhood wheezing: evidence from a birth cohort study

BACKGROUND

Several polymorphisms in the IL-4 receptor alpha (IL4RA) gene have been associated with asthma and atopy, but with variable success in different populations. Immunologic studies suggest that IL4RA may interact with other cytokines and receptors, and gene-gene interactions have also been observed with respect to asthma. Such interactions have been proposed to explain partly the difficulties in replicating association studies.

METHODS

Using the prospective birth cohort BAMSE, we examined eight single nucleotide polymorphisms (SNPs) and corresponding haplotypes in the IL4RA gene in relation to wheezing and sensitization up to age 4. We also evaluated potential interaction effects (departure from a multiplicative interaction model) between the IL4RA SNPs and four SNPs in the IL-9 receptor (IL9R) gene previously associated with childhood wheezing.

RESULTS

We found no main effect of the IL4RA SNPs alone and only weak associations to wheezing and sensitization when haplotypes were considered. Gene-gene interactions between several IL4RA and IL9R SNPs with regard to wheezing were observed (P=0.009), especially between IL4RA Q576R (rs1801275) and IL9R rs731476 (P=0.005). An interaction was also seen between IL4RA and IL9R haplotypes.

CONCLUSION

Variants in the IL4RA gene alone may not exert any major influence on susceptibility to asthma-related diseases in childhood, but in combination with other genes, such as IL9R, IL4RA may be an important gene for disease susceptibility.

Polymorphisms in the IL-4, IL-4 receptor alpha chain, TNF-alpha, and lymphotoxin-alpha genes and risk of asthma in Hong Kong Chinese adults

BACKGROUND

Susceptibility to the development of asthma and other atopic diseases is known to be associated with genetic components. However, association studies with interleukin-4 (IL-4), IL-4 receptor alpha subunit (IL-4R alpha), tumor necrosis factor-alpha (TNF-alpha) and lymphotoxin-alpha (LT-alpha) genes were inconclusive, as both positive and negative results were obtained in several populations studied. We aimed to investigate the association of the polymorphisms for IL-4 (C-589T), IL-4R alpha (Gln576Arg), TNF-alpha (G-308A) and LT-alpha (A252G) genes as candidates and asthma in adult Hong Kong Chinese population.

METHODS

The association study was conducted in an age- and smoking status-matched case-control design in asthma patients (n = 292) and healthy controls (n = 292) using polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

No significant differences were found in allele and genotype frequencies of all four genes between patients and controls. After stratification by atopic status, the heterozygous AG genotype of LT-alpha (A252G) was found to increase risk of asthma in atopic population [odds ratio (OR) = 2.00, 95% CI 1.09-3.67, p = 0.024]. When stratified by smoking status, we found increased risk of asthma with subjects carrying the heterozygous AG and homozygous GG genotypes of LT-alpha in ever-smokers (OR = 2.73, 95% CI 1.11-6.69, p = 0.028 for heterozygotes; OR = 3.34, 95% CI 1.16-9.62, p = 0.026 for homozygotes).

CONCLUSION

Our results suggest that the variability of LT-alpha genotypes may have potential implications for individual susceptibility to asthma in atopic or in ever-smoking Chinese adults in Hong Kong.

Overexpression of interleukin-13 induces minimal-change-like nephropathy in rats

IL-13 has been implicated in the pathogenesis of minimal-change nephrotic syndrome. This study aimed to investigate the role of IL-13 on the development of proteinuria and expression of podocyte-related genes that are associated with nephrotic syndrome. IL-13 was overexpressed in Wistar rats through transfection of a mammalian expression vector cloned with the rat IL-13 gene, into the quadriceps by in vivo electroporation. Serum IL-13, albumin, cholesterol, and creatinine and urine albumin were measured serially. Kidneys were harvested after day 70 for histology and electron microscopy. Glomerular gene expression of nephrin, podocin, dystroglycan, B7-1, and IL-13 receptor subunits were examined using real-time PCR with hybridization probes and expressed as an index against beta-actin. Protein expression of these molecules was determined by immunofluorescence staining. The IL-13-transfected rats (n = 41) showed significant albuminuria, hypoalbuminemia, and hypercholesterolemia when compared with control rats (n = 17). No significant histologic changes were seen in glomeruli of IL-13-transfected rats. However, electron microscopy showed up to 80% of podocyte foot process fusion. Glomerular gene expression was significantly upregulated for B7-1, IL-4Ralpha, and IL-13Ralpha2 but downregulated for nephrin, podocin, and dystroglycan. Immunofluorescence staining intensity was reduced for nephrin, podocin, and dystroglycan but increased for B7-1 and IL-4Ralpha in IL-13-transfected rats compared with controls. In conclusion, these results suggest that IL-13 overexpression in the rat could lead to podocyte injury with downregulation of nephrin, podocin, and dystroglycan and a concurrent upregulation of B7-1 in the glomeruli, inducing a minimal change-like nephropathy that is characterized by increased proteinuria, hypoalbuminemia, hypercholesterolemia, and fusion of podocyte foot processes.

Ethnicity-specific gene-gene interaction between IL-13 and IL-4Ralpha among African Americans with asthma

RATIONALE

Genes in the interleukin (IL)-4/IL-13/IL-4Ralpha pathway have been shown to be associated with asthma and related phenotypes in some populations, but not in others. Furthermore, interaction between these genes has been shown to affect asthma in white and Chinese populations.

OBJECTIVES

To determine whether there are IL-4/IL-13 and IL-4Ralpha gene-gene interactions that are associated with asthma in African Americans.

METHODS

Eighteen single-nucleotide polymorphisms (SNPs) in IL-4, IL-13, and IL-4Ralpha genes were genotyped in 264 African Americans with asthma and 176 healthy control subjects. We tested the SNPs for genetic associations and gene-gene interactions with asthma, baseline lung function, bronchodilator drug response, and total serum IgE levels.

MEASUREMENTS AND MAIN RESULTS

We identified 94 SNPs in IL-4, IL-13, and IL-4Ralpha genes by directly sequencing these genes in 24 African-American subjects with asthma. Seventeen SNPs were analyzed for association with asthma and related phenotypes. We found no evidence of association in the IL-4 gene. One SNP in the IL-13 gene (A-646G, rs2069743) and two SNPs in the IL-4Ralpha gene (A+4679G, rs1805010, and C+22656T, rs1805015) showed association with lung function (both baseline and post-bronchodilator). Although the association between individual SNPs and asthma-related phenotypes differed from previous studies performed in white and Chinese populations, significant gene-gene interaction was found between the IL-13 (A-646G) and IL-4Ralpha (A+4679G) SNPs for baseline lung function among African-American subjects with asthma.

CONCLUSIONS

Gene-gene interaction between the IL-13 and IL-4Ralpha genes may play an important role in asthma among African Americans.

Diisocyanate asthma and gene-environment interactions with IL4RA, CD-14, and IL-13 genes

BACKGROUND

Diisocyanate asthma (DA) affects 2% to 10% of exposed workers, yet the pathogenetic mechanisms underlying this disorder remain ill defined.

OBJECTIVE

To determine if specific single nucleotide polymorphisms (SNPs) of interleukin 4 receptor alpha (IL4RA), IL-13, and CD14 promoter genes are associated with DA.

METHODS

Sixty-two workers with DA confirmed by specific inhalation challenge (SIC) and 75 diisocyanate-exposed, SIC-negative workers were analyzed for SNPs associated with IL4RA, IL-13, and CD14 promoter genes.

RESULTS

No associations were found with individual SNPs and DA. When stratified according to specific diisocyanate exposure, a significant association was found between IL4RA (I50V) II and DA among individuals exposed to hexamethylene diisocyanate (HDI) (odds ratio [OR], 3.29; 95% confidence interval [CI], 1.33-8.14; P = .01) only. Similarly, the IL4RA (I50V) II and IL-13 (R110Q) RR combination was significantly associated with DA in HDI-exposed workers (OR, 4.13; 95% CI, 1.35-12.68; P = .01), as was the IL4RA (I50V) II and CD14 (C159T) CT genotype combination (OR, 5.2; 95% CI, 1.82-14.88; P = .002) and the triple genotype combination IL4RA (I50V) II, IL-13 (R110Q) RR, and CD14 (C159T) CT (OR, 6.4; 95% CI, 1.57-26.12; P = .01).

CONCLUSIONS

Gene-environmental interactions may contribute to the pathogenesis of DA, and gene-gene interactions may modulate this relationship.

Polymorphisms in the IL4 and IL4RA genes in Colombian patients with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is considered a Th1-driven disease. Interleukin 4 (IL-4) binds to its receptor, promoting Th2 differentiation and limiting Th1 responses, but its role in the pathogenesis of RA is conflicting. We analyzed 2 polymorphisms of the IL4 gene and 4 polymorphisms of the IL4RA gene in patients with RA and in a control population, as well as rheumatoid factor (RF) seropositivity, titers of RF, and history of replacement joint surgery among patients with RA.

METHODS

The study population consisted of 102 patients with RA and 102 matched healthy controls. Genotyping of IL4 -590, IL4RA +148, +1124, +1218, and +1902 was determined by restriction fragment length polymorphism-polymerase chain reaction (PCR) and sequence-specific primer-PCR. IL4 variable number tandem repeat polymorphism was determined by direct amplification.

RESULTS

The IL4 -590TT genotype was significantly more frequent in patients with RA than in controls (p = 0.018, OR 3.34, 95% CI 1.08-11.04). The IL4RA +148A allele was significantly associated with the presence of RF (p = 0.0019, OR 2.55, 95% CI 1.55-4.86) and a history of articular joint replacement (p = 0.024, OR 2.08, 95% CI 1.04-4.18). The IL4RA +1902G allele was more frequently seen in patients with RA and high RF titers (p = 0.00067, OR 4, 95% CI 1.64-9.93).

CONCLUSION

Highly complex pathways lead to the development of RA and may not be similar in all patients. Our findings of higher frequency of IL4 and IL4RA genotypes and alleles with RA, presence of RF, RF titers, and history of articular joint replacement support the polygenic expression of RA and the likely role of IL-4 in influencing its initiation and development.

Skeletal muscle IL-4, IL-4Ralpha, IL-13 and IL-13Ralpha1 expression and response to strength training

Interleukin-4 (IL-4) and interleukin-13 (IL-13) are Th2 cytokines involved in various immune responses and only a few reports examine skeletal muscle and the possible role of Th2 cytokines in myoblast fusion and myotube maturation. We hypothesized that IL-4, IL-13 and their receptors are involved in skeletal muscle adaptations to strength training. We investigated the effects of 6 weeks of strength training with different muscle load on IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression in skeletal muscle: training with maximal contractions (Max group, n = 12) and training with lower load combined with ballistic and stretch-shortening contractions (Combi group, n = 12). Muscle samples were taken from triceps brachii before and after the 6 weeks of training. mRNA levels of IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression were determined by real-time PCR and IL-4 protein expression by ELISA. We demonstrate for the first time that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are expressed in skeletal muscle in vivo and are up-regulated after strength training. Higher training load in Max leads to higher cytokine responses, which was significant for IL-4Ralpha though IL-4 protein expression did not change significantly. Although the exact mechanisms have yet to be established, and these results may be preliminary, we speculate that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are involved in muscle hypertrophy, MHC-transformation and anti-inflammatory damage control that occur during strength training.

IL4R alpha mutations are associated with asthma exacerbations and mast cell/IgE expression

BACKGROUND

Severe asthma has been associated with severe exacerbations, lower lung function and greater tissue inflammation. Previous studies have suggested that mutations in interleukin-4 receptor alpha (IL4Ralpha) are associated with lower lung function, higher IgE, and a gain in receptor function. However, an effect on exacerbations and tissue inflammation has not been shown.

HYPOTHESIS

Allelic substitutions in IL4Ralpha are associated with asthma exacerbations, lower lung function, and tissue inflammation, in particular to mast cells and IgE.

METHODS

Two well-characterized cohorts of subjects with severe asthma were analyzed for five single nucleotide polymorphisms (SNPs) in IL4Ralpha. These polymorphisms were compared with the history of severe asthma exacerbations and lung function. In the primary (National Jewish) cohort, these polymorphisms were also compared with endobronchial tissue inflammatory cells and local IgE.

RESULTS

In both cohorts, the presence of the minor alleles at E375A and Q551R, which were more common in African Americans, was associated with a history of severe exacerbations and lower lung function. In the National Jewish cohort, the C allele at E375A was associated with higher tissue mast cells and higher levels of IgE bound to mast cells. The significance for most of these associations remained when whites (the larger racial subgroup) were analyzed separately.

CONCLUSIONS

SNPs in IL4Ralpha, which are more common in African Americans, are associated with severe asthma exacerbations, lower lung function, and increased mast cell-related tissue inflammation. Further studies of the impact of these mutations in African Americans and on receptor function are indicated.