Association of interleukin-4 receptor and interleukin-4 promoter gene polymorphisms with systemic lupus erythematosus

Relationship between the IL-4 gene promoter -590C/T (rs2243250) polymorphism and susceptibility to autoimmune diseases: a meta-analysis

OBJECTIVE

Studies investigating the association between interleukin (IL)-4 gene promoter -590C/T (rs2243250) polymorphism and autoimmune diseases report conflicting results. To derive a more precise estimation of the relationship, a meta-analysis was performed.

METHODS

A systematic literature search was conducted to identify relevant studies. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to estimate the strength of association.

RESULTS

A total of 6001 cases and 6788 controls from 24 studies were analysed. Significant association of the C allele of IL-4 rs2243250 polymorphism with rheumatoid arthritis (RA) was detected (odds ratio (OR) = 0.696, 95% confidence interval (CI) = 0.601-0.807). Stratification by ethnicity indicated an association between the IL-4 rs2243250 polymorphism and RA in Caucasians. Furthermore, the overall ORs of the associations between the C allele and multiple scleorosis (MS) were 1.340 (95% CI = 1.102-1.630). However, we failed to reveal any association between IL-4 rs2243250 polymorphism and systemic lupus erythematosus (SLE), type 1 diabetes (T1D) or Graves' disease (GD).

CONCLUSIONS

The present study suggests that the IL-4 rs2243250 polymorphism might be associated with genetic susceptibility to autoimmune diseases, including RA and MS.

Interleukin 4 and STAT6 gene polymorphisms are associated with systemic lupus erythematosus in Chinese patients

An imbalance between T Helper 1 (TH1) and T Helper 2 (TH2) cytokine production is important for the pathogenesis of systemic lupus erythematosus (SLE). We aimed to investigate gene—gene associations of TH1 and TH2 cytokines genes in Chinese patients with SLE. Twenty single nucleotide polymorphisms (SNPs) in eight cytokines genes were genotyped in 110 SLE patients and 138 healthy controls in a case—control association study. The minor allelic frequencies of interleukin4(IL4) -590 T/C, -33 T/C, 9241C/G, and IL10 -592 A/C were significantly increased in SLE patients compared with those in controls (p < 0.05). None of the separate 20 SNPs showed significant association with SLE after Bonferroni correction. An IL4 haplotype -590C/-33C/9241G/14965C was significantly associated with SLE (odds ratio 3.7, 95% confidence interval [CI] 1.5—8.9, p = 0.004, Bonferroni-corrected p = 0.024). A borderline significant three-locus gene—gene interaction among IL4 9241 C/G, IL4 -33 T/C, signal transducer and activator of transcription 6, IL4-induced (STAT6) 2892 C/T was detected by a multifactor dimensionality reduction test (p = 0.051). However, the presence of two at-risk genotypes lead to increased risk of SLE for two-locus interaction using logistic regression method. The risk of SLE increased significantly when a subject has two at-risk genotypes for IL4 -590C and STAT6 2892C (odds ratio, 3.24, 95% CI 1.5—7.0, p = 0.003, Bonferroni-corrected p = 0.009), IL4 -33C and STAT6 2892C (odds ratio 3.06, 95% CI 1.4— 6.7, p = 0.005, Bonferroni-corrected p = 0.015), as well as IL4 9241G and STAT6 2892C (odds ratio 3.34, 95% CI 1.6—7.1, p = 0.002, Bonferroni-corrected p = 0.006). Further, plasma IL-4 concentrations were significantly lower in SLE patients than in healthy controls (1.59 + 3.53 versus 5.67 + 11.28 pg/ml, p = 0.042). These results indicated that IL4 and STAT6 genes might be involved in the etiology of SLE and potentially increased SLE risk through their interaction effect in Chinese patients.

Association of IL-4 589 C/T promoter and IL-4RalphaI50V receptor polymorphism with susceptibility to HIV-1 infection in North Indians

The clinical course and outcome of HIV-1 infection are highly variable among individuals. Interleukin 4 (IL-4) is a key T helper 2 cytokine with various immune-modulating functions including induction of immunoglobulin E (IgE) production in B cells, downregulation of CCR5 and upregulation of CXCR4, the main co-receptors for HIV. Our objective is to investigate whether single-nucleotide polymorphisms (SNPs) in the IL-4 promoter 589 C/T and IL-4 Ralpha I50V affect the susceptibility to HIV infection and its progression to AIDS in North Indian individuals. The study population consisted of 180 HIV-1 seropositive (HSP) stratified on the basis of disease severity (stage I, II, III), 50 HIV-1 exposed seronegative (HES), and 305 HIV-1 seronegative (HSN) individuals. The subjects were genotyped for IL-4 589 C/T promoter polymorphism and IL-4 Ralpha I50V by polymerase chain reaction restriction fragment length polymorphism. The results showed that IL-4 589 C/T was not associated with the risk of HIV infection and disease progression. However, the IL-4Ralpha I50 allele and genotype was significantly increased in HSP compared to HSN and HSP and was associated with risk of HIV infection. The frequency of IL-4Ralpha I50 allele in the HSP group was higher than in HSN (76.11 vs. 64.75%; P = 0.000; OR = 1.734) and HES (76.11% vs. 62.00%; P = 0.007; OR = 1.953). Homozygous IL-4Ralpha I50I genotype was significantly increased in HSP group compared with HSN (58.88% vs. 44.26%; P = 0.002; OR = 1.804) and HES (58.88% vs. 42.00%; P = 0.038; OR = 1.978). The present study for the first time suggests an association of IL-4Ralpha I50 allele with increased likelihood of HIV-1 infection in North Indian population. Further studies are required to confirm these findings and understand the effect of IL-4Ralpha polymorphism on the outcome of HIV-1 infection.

Association of theIL4R single-nucleotide polymorphism I50V with rapidly erosive rheumatoid arthritis

OBJECTIVE

To examine whether single-nucleotide polymorphisms (SNPs) of the interleukin-4 receptor gene IL4R influence susceptibility to, or radiographic progression in, rheumatoid arthritis (RA).

METHODS

The contribution of 2 SNPs (I50V and Q551R) in the coding region of IL4R to RA susceptibility was analyzed by allele-specific polymerase chain reaction in a case-control study of 471 RA patients and 371 healthy controls. Patients with available radiographs of the hands and feet obtained 2 years after disease onset (n = 302) were stratified retrospectively according to radiologic outcome into an erosive and a nonerosive group to evaluate the association between IL4R SNPs and disease progression.

RESULTS

No differences in the genotype and allele frequencies of the I50V or Q551R SNPs were identified between the RA patients and healthy controls. In contrast, significant differences in the distribution of I50V IL4R SNP genotypes between patients with erosive and nonerosive disease were observed (chi2 = 15.68, P = 0.0004). Bone erosions at 2 years after disease onset were present in 68.1% of patients homozygous for the V50 allele compared with 37.0% of patients homozygous for the I50 allele (odds ratio 3.86, P < 0.0001). This association was independent of individual factors previously associated with severe disease, such as rheumatoid factor or the HLA-DR shared epitope. On a cellular level, the V50 allele conferred significantly reduced responsiveness to interleukin-4, providing a possible mechanism for the association of the I50V IL4R polymorphism with early erosions in RA.

CONCLUSION

Our data identify the I50V IL4R SNP as a novel genetic marker in RA, showing high predictive value for early joint destruction.

Genetics of systemic lupus erythematosus: how far have we come?

There are two primary mechanisms for studying the genetic forces at work in systemic lupus erythematosus (SLE). Several groups have collected large numbers of pedigrees in which multiple family members have SLE for use in linkage studies. These linkage studies serve to isolate areas of the genome in which susceptibility genes lie. Other groups have taken a more direct approach of investigating genes that might contribute to disease pathogenesis in sets of lupus subjects and matched controls. These association studies are accumulating in greater numbers as the technology to determine the genotype at a given locus becomes more accessible. This article discusses the results of both types of studies.

The -590 IL-4 promoter polymorphism in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which cytokines play an important role. The aim of the present study was to evaluate the -590 IL-4 promoter polymorphism in patients with RA and its association with disease activity and severity. We enrolled 94 patients with RA diagnosed according to the criteria of the American College of Rheumatology. Polymerase chain reaction amplification was used for analysis of the polymorphism at position -590 of the promoter of the IL-4 gene. The distribution of IL-4 genotypes in RA patients did not differ from control subjects. Nevertheless, the active form of RA was more frequently diagnosed in patients with T allele (genotypes CT and TT) as compared with homozygous CC patients. Moreover, in carriers of the T allele, parameters of disease activity (DAS 28 score, ESR, number of swollen and tender joints) were significantly increased. We suggest that the IL-4 -590 promoter polymorphism may be a genetic risk factor for RA severity.

Polymorphisms of interleukin 4 receptor gene and interleukin 10 gene are not associated with Graves' disease in the UK

Graves' disease (GD) is an autoimmune disorder of the thyroid gland and both environmental and genetic factors contribute to disease aetiology. Cytokines, such as interleukin 4 (IL-4) and interleukin 10 (IL-10), are involved in the immune response and may be implicated in the autoimmune disease process. Associations have been reported between single nucleotide polymorphisms (SNPs) of IL-10 and the Ile50Val polymorphism of the IL-4 receptor gene (IL-4R) gene and atopy and autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. The autoimmune diseases cluster within families and susceptibility genes may overlap between the different disorders. Therefore, we investigated 5 SNPs (-592C/A, -657G/A, - 819C/T, -1349A/G, and -2013G/A) in the promoter region of the IL-10 and the Ile50Val polymorphism (A/G) in the IL-4R in a large UK population based case-control dataset with GD. No association was found between the polymorphisms studied and GD and no significant differences were found in genotype or allele frequencies between the patients and control subjects. We conclude these polymorphisms of IL-10 and IL-4R previously associated with other immune mediated diseases, do not confer susceptibility to GD in white Caucasians in the United Kingdom.

Systemic sclerosis: the susceptible host (genetics and environment)

It is becoming evident that several genetic factors participate in modulating susceptibility to SSc and its clinical manifestations. Some genes that specifically affect ECM metabolism and vascular function may be unique to SSc and scleroderma-related disorders; others, such as those genes involved in regulating immune tolerance, are likely shared with other autoimmune diseases. The effect of genetic variations (or polymorphisms) that are found in most of these genes taken individually will likely have only a small or modest effect on disease risk; only a few genetic variations are expected to be highly penetrant. Moreover, genetic studies in SSc have to deal with the additional issues of heterogeneous phenotypes, low disease prevalence in the general population, and an even greater paucity of multiplex families that makes traditional linkage studies difficult, if not impossible. Alternative approaches include allelic association studies, but conventional case-controls designs may be subject to selection bias and will require large sample sizes if the genes that are under investigation confer only modest (OR = 1.5-2.0) disease risk (Fig. 2). The simultaneous examination of several genes that are biologically relevant to a specific disease process to attain higher aggregate ORs, is one approach that was used in several reports that were cited in this review. The use of family-based controls, such as in the transmission-disequilibrium test (based on assessment of the transmitted or nontransmitted alleles that are associated with disease from heterozygous parents to affected offspring), would provide more robustness to spurious associations from population stratification, but is actually less powerful and efficient than case-control designs. Furthermore, for many late adult-onset diseases the effort required to obtain samples from living parents are for a variety of reasons not trivial. The success of these allelic association-based approaches depends on the identification of likely candidate disease genes (or at least markers in disequilibrium with disease genes), careful definition/ascertainment of disease phenotypes to minimize genetic heterogeneity, and for case-control designs, strategies to account for population stratification or admixture. The identification of candidate genes will be aided by rapid progress in the Human Genome Project and other genome efforts that will eventually identify all human genetic variations. Although this will lead to better understanding of the genes that might be involved in complex diseases, much work is required to understand the basic biology of how disease genotypes become clinical phenotypes. This is especially daunting in complex diseases, such as SSc, where the phenotype (including disease susceptibility and clinical presentation) is influenced by dynamic interactions between genetic variations and environment. Multi-center collaborative efforts with research paradigms that integrate genetic and environmental factors (including sociodemographic variables) will be required to elucidate the contribution of environment and genetics in the pathogenesis of SSc.

Immunopathology and the gene therapy of lupus

Lupus is a chronic autoimmune inflammatory disease with complex clinical manifestations. In humans, lupus, also known as systemic lupus erythematosus (SLE), affects between 40 and 250 individuals, mostly females, in each 100 000 of the population. There are also a number of murine models of lupus widely used in studies of the genetics, immunopathology, and treatment of lupus. Human patients and murine models of lupus manifest a wide range of immunological abnormalities. The most pervasive of these are: (1) the ability to produce pathogenic autoantibodies; (2) lack of T- and B-lymphocyte regulation; and (3) defective clearance of autoantigens and immune complexes. This article briefly reviews immunological abnormalities and disease mechanisms characteristic of lupus autoimmunity and highlight recent studies on the use of gene therapy to target these abnormalities.

Characterization of CD3+ CD4- CD8- (double negative) T cells in patients with systemic lupus erythematosus: production of IL-4

Systemic lupus erythematosus (SLE) is a chronic autoimmune rheumatic disease that may affect every organ or system in the body. We have shown previously that the TCR alphabeta+ subpopulation of CD3+ CD4- CD8-, DN T cells is expanded in patients with SLE and that double negative T cells express increased levels of activation markers compared both with healthy people and with patients with rheumatoid arthritis, (RA) as autoimmune controls. The aim of this study was to characterize these cells in terms of their ability to produce IL4, a Th2 cytokine, both spontaneously and after mitogen stimulation. It was found that a higher percentage of TCR alphabeta+ double negative T cells from patients with SLE contained IL4 constitutively than did the same population of cells from healthy people or from those with RA. After mitogen stimulation, there was no significant difference in the amount of IL4 produced by each of the three groups. Further study of patients producing high levels of IL4 (about one third of the patients) indicated that they had a lower percentage of alphabeta+ T cells in the double negative compartment than did patients with fewer IL4 containing cells.

No linkage of the interleukin-4 receptor locus on chromosome 16p11.2-12.1 with sarcoidosis in German multiplex families

We typed 241 members of 62 sarcoidosis families with 136 affected siblings for three single nucleotide polymorphisms of the interleukin-4 receptor alpha-chain gene (IL4R). Allele frequencies in patients were compared to those of healthy unrelated control individuals. The segregation of the three-point IL4R haplotypes completed by two flanking highly polymorphic microsatellite polymorphisms revealed no evidence for linkage of the IL4R gene locus with sarcoidosis.

Distinct signal transduction processes by IL-4 and IL-13 and influences from the Q551R variant of the human IL-4 receptor alpha chain

BACKGROUND

Although IL-4 and IL-13 share the IL-13 receptor, IL-13 exhibits unique functions. To elicit the cellular basis of these differences, signal transduction processes have been compared. Additionally, the role of the IL-4 receptor alpha (IL-4Ralpha) variant Q551R was investigated.

METHODS

Peripheral blood mononuclear cells from donors were stimulated with IL-4 and IL-13. The phosphorylation status of effector substrates was detected by immunostaining. Binding of SHP-2 to IL-4Ralpha was investigated by using synthetic peptides.

RESULTS

SHP-2 bound IL-4Ralpha synthetic peptide; this binding was reduced in the presence of the R551 variant. Stimulation with IL-4 increased SHP-1 phosphorylation, however, stimulation with IL-13 increased SHP-2 phosphorylation. PI3-kinase phosphorylation was elevated following stimulation with IL-13 in all individuals and with IL-4 only in R551 individuals. Jak1, Tyk2 and IRS-2 signals were reduced after IL-13 stimulation in Q551 individuals. STAT3 phosphorylation was markedly increased in R551 individuals, following stimulation with both IL-4 and IL-13. However, STAT3 was only detected immediately in nuclear extracts from variant individuals after stimulation with IL-13; in wildtype individuals STAT3 was only detected after IL-4 treatment.

CONCLUSION

IL-4 and IL-13 appear to promote distinct signal transduction cascades. SHP-1 seems to be predominately activated by IL-4 and to influence the PI3-kinase, in contrast, SHP-2 seems to be predominately activated by IL-13 and to influence Jak1, Tyk2 and IRS-2. Both phosphatases control STAT3. In the presence of the variant R551, SHP-1/2 activation is reduced and signal transduction is altered. STAT3 signaling appears be further regulated on the level of nuclear translocation.

Cytokine polymorphisms in systemic lupus erythematosus and Sjögren's syndrome

Systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) are defined genetically as complex diseases where multiple genes are involved in their pathogenesis. Among the genes of interest are those coding for the cytokines, molecules involved in immunoregulation that have been shown to play important roles in these diseases. Whether abnormalities in cytokine production are owing to genetic polymorphisms within the genes themselves is a matter of intensive study. The finding of functional polymorphisms within cytokine genes and their potential association with disease will open new avenues in their treatment.

A population genetics study of single nucleotide polymorphisms in the interleukin 4 receptor alpha (IL4RA) gene

Interleukin 4 (IL4) plays a critical role in T helper 2 (Th2) immune responses. Here we report a population genetics study of variation in the gene encoding the alpha-chain of the IL4 receptor (IL4RA) in three ethnic groups: African Americans, European Americans and East Asians. A 2941-bp region spanning exon 12 of IL4RA gene was sequenced in 12 individuals from each group. A total of 24 single nucleotide polymorphisms (SNPs) were identified in the combined sample. The genetic variation of the coding region of exon 12 is two to three times higher than in other reported genes. A significant departure from the expectation of evolutionary neutrality was observed, suggesting that natural selection may have influenced the evolution of this gene. We propose a model in which past selection by pathogens contributed to the increasing prevalence of atopic disorders in Western societies.

Genetic studies of human lupus in families

Systemic lupus erythematosus (SLE) is a complex multigenic disease in which the contributing genetic systems are being rapidly identified. Most of the currently recognized genes have been discovered from case-control association studies, but, increasingly, family linkage studies are being employed to confirm previous genetic associations, to examine their relative contributions, and to identify new susceptibility loci. Most of the loci identified thus far appear to contribute only modest effects on susceptibility overall but rather influence more strongly disease expression and/or severity. MHC class II alleles, for example, seem to show only weak linkage to SLE itself but instead mediate specific T cell driven pathogenic autoantibodies which produce many of the clinical disease features, similar to their effects in many other autoimmune diseases. On the other hand, complete and partial hereditary deficiencies of early complement components are more lupus-specific. Homozygous complement deficiencies, while powerful risk factors, are rare causes of lupus and heterozygous deficiencies exert only modest effects on susceptibility. Other genes, such as low-binding IgG Fc receptor alleles (FcgammaIIa and FcgammaIIIa), appear to promote nephritis by modifying the efficiency of immune complex clearance. A variety of cytokine genes appear also to promote severity, including those for TNFalpha, IL-10, IL1 receptor antagonist, and perhaps others (IL-6, IL-4 and TNFalpha receptor). Family studies and recent genome-wide scans in lupus and other autoimmune diseases support the likelihood that some susceptibility loci, as yet unidentified, predispose to several or many autoimmune diseases. Only thorough the identification and elucidation of function of these many genes is the pathogenic picture of lupus likely to be complete.

Genetic factors in the etiology of systemic sclerosis and Raynaud phenomenon

There is increasing evidence that genetic factors play important roles in susceptibility to and expression of systemic sclerosis (SSc), as well as primary Raynaud phenomenon. Familial aggregation for SSc, although infrequent (1.2%-1.5% of SSc families), has now been established, and when compared with population prevalence represents a significant risk factor for the disease and lays a firmer foundation for genetics in etiopathogenesis. Major histocompatibility complex class II alleles increase disease risk in some populations but are more strongly correlated with specific autoantibody profiles. Microchimerism influenced by human leukocyte antigen also remains an intriguing hypothesis. A variety of extracellular matrix genes, including fibrillin-1, have become additional candidates for contributing to what is likely a complex genetic disease. Reviewed here is evidence relating to these concepts, especially new data reported over the last year.

Genetic factors influencing the development of chronic graft-versus-host disease in a murine model

Graft-versus-host disease (GVHD) is a major complication of bone marrow transplantation that can occur in either acute or chronic forms. Much of the long-term pathology seen in chronic GVHD is a result of autoantibody production. In the DBA/2-->B6D2F1 murine model of chronic GVHD, anti-ssDNA autoantibodies can be detected by 14 days post cell transfer. These autoantibodies are not observed in B6D2F1 recipients of cells from C57BL/6 or B10.D2 donors, which develop acute rather than chronic GVHD. Therefore, in this model, donor genetic factors predispose to the development of chronic GVHD in recipients. We performed a genetic analysis aimed at mapping donor loci that influence the magnitude of early autoantibody production in B6D2F1 recipients of cells from DBA/2 donor mice. Linkage analysis suggested an influence of two loci: a locus on chromosome 11 linked to D11Mit278 and a locus on chromosome 4 linked to D4Mit226. The locus on chromosome 11 also appeared to influence the development of renal pathology associated with chronic GVHD.

Biologic functions and signaling of the interleukin-4 receptor complexes

IL-4 is a pleiotropic cytokine which plays a pivotal role in shaping immune responses. The effects of IL-4 are mediated after binding to high affinity receptor complexes present on hematopoietic as well as non-hematopoietic cells. This review will summarize the current knowledge on the molecular structure of the different types of IL-4 receptor (IL-4R) complexes as well as the signal transduction mechanisms induced by IL-4 leading to cellular proliferation and / or gene activation. IL-4 effects are modulated by soluble forms of the respective receptor molecules which are produced by several immune cells in a regulated manner. The biological impact of recently described IL-4R allotypes of mice and humans as well as the results of studies with IL-4R knockout mice will be particularly emphasized.