Interferon-gamma gene microsatellite polymorphisms in patients with Graves' disease

Association of variant on the promoter of cluster of differentiation 74 in graves disease and graves ophthalmopathy

The macrophage migration inhibitory factor (MIF)/cluster of differentiation 74 (CD74) plays a role in immunological functions. The present study aims to investigate whether single-nucleotide polymorphisms (SNPs) in the MIF and CD74 are risk factors for developing Graves ophthalmopathy (GO) in patients with Graves disease (GD). A case–control study enrolled 484 patients with GD (203 with and 281 without GO) and 1000 healthy individuals. SNPs were discriminated using real-time polymerase chain reaction. Hardy–Weinberg equilibrium, as well as frequencies of allele and genotype between GD patients with and without GO, were estimated using the Chi-square test. The effects of CD74 on adipocyte proliferation and differentiation were evaluated using 3T3-L1 preadipocytes. Quantitative DNA-immunoprecipitation was used to detect the binding capacity of NR3C1 and FOXP3 to A/G oligonucleotides. The results showed that individuals carrying the GG genotype at rs2569103 in the CD74 had a decreased risk of developing GD (P=3.390 × 10⁻¹¹, odds ratio (OR) = 0.021, 95% confidence interval (CI) = 0.003–0.154); however, patients with GD carrying the AG genotype at rs2569103 in the CD74 had an increased risk of developing GO (P=0.009, OR = 1.707, 95% CI = 1.168–2.495). The knockdown of CD74 reduced adipocyte proliferation and differentiation. NR3C1 had a higher affinity for A, whereas FOXP3 had a higher affinity for G of rs2569103. The results suggested the existence of a link between the genetic variation of CD74 promoter and the risk for developing GD and GO, which should be considered in clinical practice.

Association of IL12B polymorphisms with susceptibility to Graves ophthalmopathy in a Taiwan Chinese population

Background

Interleukin 12B (IL12B) gene polymorphisms have been linked to several inflammatory diseases, but their role in the development of Graves ophthalmopathy (GO) in Graves disease (GD) patients is unclear. The purpose of this study was to investigate the disease association of IL12B single nucleotide polymorphisms (SNPs).

Methods

A Taiwan Chinese population comprising 200 GD patients with GO and 271 GD patients without GO was genotyped using an allele-specific extension and ligation method. Hardy-Weinberg equilibrium was estimated using the chi-square test. Allele and genotype frequencies were compared between GD patients with and without GO using the chi-square test.

Results

The genotype and allele frequencies of examined SNPs did not differ between GD patients with and without GO. Although the genotype distribution remained nonsignificant in the sex-stratified analyses, the frequency of the T allele at SNP rs1003199 was significantly higher in patients with GO in the male cohort (P = 6.00 × 10^-3). In addition, haplotypes of IL12B may be used to predict the risk of GO (P = 1.70 × 10^-2); however, we could not prove the statistical significance of analysis after applying the Bonferroni correction.

Conclusions

Our results provide new information that the examined IL12B gene polymorphisms may be associated with susceptibility to GO in the Taiwan Chinese population in a sex-specific manner. This conclusion requires further investigation.

The genetic basis of graves' disease

The presented comprehensive review of current knowledge about genetic factors predisposing to Graves’ disease (GD) put emphasis on functional significance of observed associations. In particular, we discuss recent efforts aimed at refining diseases associations found within the HLA complex and implicating HLA class I as well as HLA-DPB1 loci. We summarize data regarding non-HLA genes such as PTPN22, CTLA4, CD40, TSHR and TG which have been extensively studied in respect to their role in GD. We review recent findings implicating variants of FCRL3 (gene for FC receptor-like-3 protein), SCGB3A2 (gene for secretory uteroglobin-related protein 1- UGRP1) as well as other unverified possible candidate genes for GD selected through their documented association with type 1 diabetes mellitus: Tenr–IL2–IL21, CAPSL (encoding calcyphosine-like protein), IFIH1(gene for interferon-induced helicase C domain 1), AFF3, CD226 and PTPN2. We also review reports on association of skewed X chromosome inactivation and fetal microchimerism with GD. Finally we discuss issues of genotype-phenotype correlations in GD.

Association between age, IL-10, IFNγ, stimulated C-peptide and disease progression in children with newly diagnosed Type 1 diabetes

AIMS

The relation of disease progression and age, serum interleukin 10 (IL-10) and interferon gamma (IFNγ) and their genetic correlates were studied in paediatric patients with newly diagnosed Type 1 diabetes.

METHODS

Two hundred and twenty-seven patients from the Hvidoere Study Group were classified in four different progression groups as assessed by change in stimulated C-peptide from 1 to 6 months. CA repeat variants of the IL-10 and IFNγ gene were genotyped and serum levels of IL-10 and IFNγ were measured at 1, 6 and 12 months.

RESULTS

IL-10 decreased (P < 0.001) by 7.7% (1 month), 10.4% (6 months) and 8.6% (12 months) per year increase in age of child, while a twofold higher C-peptide concentration at 1 month (p = 0.06), 6 months (P = 0.0003) and 12 months (P = 0.02) was associated with 9.7%, 18.6% and 9.7% lower IL-10 levels, independent of each other. IL-10 concentrations did not associate with the disease progression groups. By contrast, IFNγ concentrations differed between the four progression groups at 6 and 12 months (P = 0.02 and P = 0.01, respectively); patients with rapid progressing disease had the highest levels at both time points. Distribution of IL-10 and IFNγ genotypes was equal among patients from the progression groups.

CONCLUSION

IL-10 serum levels associate inversely with age and C-peptide. As age and C-peptide also associate, a triangular association is proposed. Genetic influence on IL-10 production seems to be masked by distinct disease mechanisms. Increased serum IFNγ concentrations associate with rapid disease progression. Functional genetic variants do not associate with a single progression pattern group, implying that disease processes override genetically predisposed cytokine production.

Association of the interferon-γ gene (CA)n repeat polymorphism with endometriosis

OBJECTIVE

To investigate whether the interferon-γ (IFN-γ) gene (CA)(n) repeat polymorphism is associated with susceptibility to endometriosis.

DESIGN

Case-control study.

SETTING

University Department of Obstetrics and Gynaecology.

POPULATION

Women with (n = 622) and without (n = 442) endometriosis.

METHODS

Genotyping was performed by fluorescent polymerase chain reaction (PCR) and gene-scan analysis.

MAIN OUTCOME MEASURES

Genotype distribution and allele frequency of the dinucleotide (CA)(n) repeat polymorphism in the IFN-γ gene.

RESULTS

Seven alleles (12-18 repeats) of the IFN-γ gene (CA)(n) repeat polymorphism were found. In both patients with endometriosis and controls the most common allele was composed of 13 repeats, followed by an allele of 15 repeats, and then by an allele of 12 repeats. Patients with endometriosis had a significantly higher incidence of genotypes with alleles composed of fewer repeats (12-13 repeats), compared with the controls (92.0 versus 84.4%, respectively, P < 001).

CONCLUSIONS

Our results suggest that the (CA)(n) repeat polymorphism in the IFN-γ gene may be associated with a risk of endometriosis in the South Korean population.

Genetic contribution of the interferon gamma dinucleotide-repeat polymorphism in South Indian women with endometriosis

AIM

To investigate whether the interferon-gamma (IFNG) gene dinucleotide (CA)-repeat polymorphism is responsible in part for genetic susceptibility to endometriosis in South Indian women.

METHODS

Following extraction of genomic DNA, genotyping of interferon-gamma CA-repeat polymorphism was performed using genescan technology.

RESULTS

The global IFNG allele frequencies in all patients with endometriosis were significantly different from those in the control women (chi(2) = 37.062; 6 degrees of freedom; P < or = 0.0001). Significant difference was observed in global allele frequencies between the control women and each clinical subgroup of patients with endometriosis except for patients suffering from endometriosis associated with adenomyosis. The difference was due to an increase in a12 (112 bp) allele in the patients with endometriosis and each clinical subgroup of patients with endometriosis. The distribution of the IFNG a12 genotypes was significantly different between patients with endometriosis and the control women. (chi(2) = 10.635; 2 degrees of freedom; P = 0.0049). A significant difference in the IFNG a12 genotypes was found only among the three clinical subgroups.

CONCLUSION

These results suggest that the IFNG gene CA-repeat polymorphism is associated with susceptibility to endometriosis in South Indian women.

Interleukin-1beta gene (IL-1beta) polymorphisms (SNP -511 and SNP +3953) in thyroid-associated ophthalmopathy (TAO) among the Polish population

OBJECTIVE

The aim of this study was to evaluate whether the IL-1beta gene could be a genetic marker of the thyroid-associated ophthalmopathy (TAO) development.

MATERIALS AND METHODS

The IL-1beta gene polymorphisms at -511 and +3953 regions in 117 TAO patients of Polish origin (ATA/NOSPECS class III or greater) and in 106 controls were studied.

RESULTS

We found no significant differences in the frequencies of genotypes and allelic variants for SNP -511 and SNP +3953 between the controls and the studied groups.

CONCLUSIONS

No association between the IL-1beta polymorphisms and the TAO existed, so those polymorphisms are not suitable genetic markers for TAO.

Associations of protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene polymorphisms with susceptibility to Graves' disease in a Japanese population

BACKGROUND

The polymorphism of the protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene, which encodes an important negative regulator of T cell activation, has been reported to be associated with susceptibility to Graves' disease (GD) in Caucasians. The objective of this study was to investigate whether PTPN22 gene polymorphisms confer susceptibility to GD and Graves' ophthalmopathy (GO) in a Japanese population.

METHODS

We performed a case-control study of PTPN22 gene polymorphisms in Japanese GD patients (n = 414) and healthy control subjects with no antithyroid autoantibodies or family history of autoimmune disorders (n = 231). The G-1123C polymorphism (rs2488457) in the promoter region, Arg620Trp (C1858T) polymorphism (rs2476601) in exon 14, IMS-JST146695 polymorphism (rs3789607) in intron 19, and SNP37 (rs3789604) downstream of the PTPN22 gene were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism using restriction enzymes and direct PCR sequencing methods.

RESULTS

None of the GD patients or control subjects had the 1858T allele of the PTPN22 gene polymorphism. The AA-genotype and A-allele frequencies of SNP37 were significantly higher in GD patients than in control subjects (A-allele frequency: p = 0.0085, odds ratio = 1.45). The genotype frequencies and allele frequencies of the G-1123C and IMS-JST146695 polymorphisms did not differ between GD patients and control subjects. The -1123G/1858C/JST146695T/SNP37C haplotype frequency was significantly lower in GD patients than in control subjects. There were no associations between PTPN22 gene polymorphisms and GO.

CONCLUSIONS

The results suggest that SNP37 of the PTPN22 gene is associated with susceptibility to GD in a Japanese population. Further studies including functional analyses are required.

L-selectin gene polymorphisms in Graves' disease

OBJECTIVE

Graves' disease (GD) is an autoimmune disorder with genetic predisposition. There is strong evidence that members of the selectin family participate in the interaction between leucocytes and the endothelium, as well as in inflammatory cell recruitment. Moreover, a high serum level of a soluble form of L-selectin (SL-selectin) has been reported in untreated GD patients. However, the impact of L-selectin polymorphisms on GD has not yet been investigated. The aim of the present study was to elucidate whether L-selectin gene polymorphisms were associated with the development of GD.

SUBJECTS AND DESIGN

L-selectin gene polymorphisms were investigated in 230 Chinese GD patients and 208 healthy control subjects without antithyroid autoantibodies or a family history of autoimmune disorders. Two L-selectin SNPs were genotyped by the PCR-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

A C/T polymorphism at position -642 of the promoter region and a Pro213Ser (c.725 C-T) polymorphism in exon 6 were examined using PCR-RFLP. There was a significant increase in -642T allele frequency in GD patients compared with healthy controls (70 vs. 62%; P = 0.0126; P(c) = 0.0252). The frequency of the c.725C allele in exon 6 also appeared higher in GD patients than in controls. Haplotype analysis showed a significant decrease in the -642C/c.725T haplotype in GD patients (26 vs. 34%; P = 0.0095; Pc = 0.0190). However there was no association between polymorphisms and certain GD clinical phenotypes, including age of onset and ophthalmopathy.

CONCLUSIONS

L-selectin gene polymorphisms are associated with GD susceptibility in Chinese patients.

Susceptibility genes in Graves' ophthalmopathy: searching for a needle in a haystack?

The variety of clinical presentations of eye changes in patients with Graves' disease suggests that complex interactions between genetic, environmental, endogenous and local factors influence the development/severity of Graves' ophthalmopathy (GO). At present, the role of genetic factors in the development of GO remains unknown. Based on small case-control association studies with candidate genes, several susceptibility loci in GO have been proposed. These are human leucocyte antigen (HLA, 6p21.3), cytotoxic T-lymphocyte antigen-4 (CTLA-4, 2q33), tumour necrosis factor (TNF, 6p21.3), interferon-gamma (IFN-gamma, 12q14), intercellular adhesion molecule-1 (ICAM-1, 19p13), and thyroid stimulating hormone receptor gene (TSH-R, 14q31). Unfortunately, these results were either not confirmed or require replication in larger studies. There are many reasons for the lack of reproducibility of association studies in GO, including poor characterization of the studied groups and small sample sizes, which may result in both false positive and negative results. Thus, the genetic background of GO remains to be elucidated in future research. However, the possibility that GO may be a genetically heterogeneous disorder, or that the development of GO may be predominantly influenced by environmental factors such as cigarette smoking, can not be disregarded.

Intercellular adhesion molecule 1 gene polymorphisms do not contribute to Graves' disease in Chinese patients

OBJECTIVE

In order to study the association of G241R polymorphism of ICAM-1 gene with an earlier onset of Graves' disease (GD) and the susceptibility of K469E polymorphism to Graves' ophthalmopathy (GO) in Chinese population.

STUDY DESIGN

A case-control and replication study was performed in 212 GD patients and 204 healthy subjects to analyze the genotypes. Furthermore the distribution of ICAM-1 genotypes was investigated in subgroups of patients with GD according to the onset age and the ophthalmopathy.

RESULTS

No G241R polymorphism of ICAM-1 gene was detected in Chinese. No significant differences of allele and genotype frequencies regarding K469E polymorphism were found between GD patients and healthy controls (chi2 = 0.092, P = 0.762; chi2 = 1.089, P = 0.580). In addition, the genotype-phenotype correlation was not identified either.

CONCLUSIONS

We found no association of G241R and K469E polymorphisms of the ICAM-1gene with the development of GD in a Chinese population. However, we could not rule out possible contributions of other polymorphisms of the ICAM-1gene to the pathogenesis of GD. Therefore, further studies are needed to elucidate the role of ICAM-1gene in Graves' disease in different population.

A differential association of interferon-gamma high-producing allele T and low-producing allele A (+874 A/T) with Hashimoto's thyroiditis and Graves' disease

Cytokines play a crucial role in the pathogenesis of autoimmune thyroid disease. The aim of this study was to investigate the relationship of the single base change polymorphic variants identified in the first intron of interferon-gamma (IFN-gamma) (+874 T/A) with susceptibility to thyroid dysfunctions. A total of 340 subjects were included in the study comprising of 190 patients (104 patients with Hashimoto's thyroiditis, 26 with non-Hashimoto's hypothyroidism and 60 Graves' disease) and 150 controls. Genotyping was done by amplification refractory mutation system-polymerase chain reaction using a set of sequence-specific primers. Statistical analysis revealed a significant association between high IFN-gamma-producing genotype TT and Hashimoto's thyroiditis compared to controls (P value < 0.001). On the other hand, the frequency of genotype TT was decreased in patients with Graves' hyperthyroidism with a significant increase in low IFN-gamma-producing genotype AA among this group (P = 0.03). To conclude the results of the study suggest a differential association of high- and low-producing alleles of IFN-gamma gene with Hashimoto's thyroiditis and Graves' disease. The high IFN-gamma-producing allele T was observed to be associated with Hashimoto's thyroiditis in the present study where as in Graves' hyperthyroidism the association was observed to be stronger with the low producing allele A.

Promoter and intron-1 region polymorphisms in the IFNG gene in patients with hepatitis E

Allelic and genotype variations in the promoter region and the dinucleotide (CA)(n) repeat region in intron 1 of the interferon-g (IFNG) gene were analysed by direct sequencing and simple sequence length polymorphism (SSLP), respectively, in patients with acute hepatitis, and the prevalence was compared with that in healthy controls. Our results showed a significant association of heterozygous genotypes (CA)12/(CA)14 and (CA)12/(CA)16 in intron 1 of the IFNG gene in all categories of patients with acute hepatitis, classified on the basis of presence or absence of hepatitis E virus (HEV), in comparison with healthy controls. A novel polymorphism, -288 A-->T [from the translational start site, as per Human Genome Organization (HUGO) nomenclature], in the promoter region of the IFNG gene leading to a loss of the consensus domain for the interferon-stimulated response element (ISRE), as predicted by in silico analysis, was observed in 12.5% of patients with acute HEV infection. However, no significant difference in allele or genotype frequency was observed for the -288 promoter polymorphism, although the heterozygous -288 A/T genotype showed a moderate risk in patients with acute HEV infection alone (P = 0.29, odds ratio = 1.964, confidence interval = 0.46-8.45). The data suggest that the genotype at intron 1 of IFNG might affect susceptibility to acute hepatitis in HEV infection, which warrants further elucidation in a larger sample and also functional studies.

Lack of association of interleukin-18 gene polymorphisms with susceptibility of Japanese populations to Graves' disease or Graves' ophthalmopathy

OBJECTIVE

To investigate whether polymorphisms of interleukin (IL)-18 gene confer susceptibility to Graves' disease (GD) and Graves' ophthalmopathy (GO).

DESIGN

We performed a case control study on polymorphisms of IL-18 gene in Japanese patients with GD (n = 435), and healthy control subjects without antithyroid autoantibodies or family history of autoimmune disorders (n = 255). The C-4675G, C-607A, and G-137C polymorphisms in the promoter region and A105C (exon 5) polymorphism were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using restriction enzymes, sequence-specific PCR, and PCR-direct sequencing methods.

RESULTS

None of the polymorphisms in the IL-18 gene were associated with development of Graves' disease. The CC genotype and C allele frequencies of IL-18 gene G-137C polymorphism tended to be greater in patients with ophthalmopathy than in patients without evident ophthalmopathy. However, the differences were not statistically significant. Although there were three major haplotypes, none of the haplotypes were statistically associated with susceptibility to GD or ophthalmopathy.

CONCLUSIONS

These results suggest that IL-18 gene polymorphisms are not major genetic factors for susceptibility to GD in a Japanese population. Further studies with adequate sized data set in the subset analyses for GO are needed.

The different faces of shared autoimmunity

The concept of shared autoimmunity comprises various forms of disease: rheumatic diseases in several members of the same family, the coincidence of autoimmune rheumatic with non-rheumatic diseases in relatives of patients, the presence of autoantibodies in healthy relatives of autoimmune disease patients, and the development of two or more autoimmune rheumatic diseases in one patient, the so-called overlap syndromes. The genetic and environmental factors that lead to these phenomena interact in a complex fashion and influence the distinct phenotypic characteristics of each patient. In a previous case series, we described 23 Mexican Mestizo patients with overlap syndromes. Interestingly, rhupus tends to develop sequentially while sclerodermatomyositis tends to appear simultaneously. The clinical course of the other overlap syndromes is rather aggressive, although clinical manifestations respond to standard treatment. The second and/or third disease appears while the first one is still active, even with adequate treatment. The distinct course of overlap syndromes may be partially explained by the interplay of environmental factors with genes that predispose to autoimmunity in general and to manifestations of specific diseases. The analyses of genes that will help understand the pathophysiology of these diseases include several MHC complex genes, cytokines, AIRE, and PDCD1 amongst others.

Th1 Cytokine Polymorphisms in Spanish Patients With Type 1 Diabetes

Several polymorphisms in regions where Th1 cytokines (IL12B and IFNG genes) are located were analyzed in 303 Spanish subjects with type 1 diabetes and compared with a control cohort (n = 548). Both groups comprised residents of the Madrid area. The haplotype frequencies were estimated by the expectation-maximization algorithm, and p values were corrected by the number of haplotypes taken into account in the study. Two haplotypes were significantly associated with the disease, one in the IL12B region (D5S2038*8/D5S1352*2/SNP1188C; OR = 3.01, p(c) = 0.0255) and another involved the IFNGgene (D12S313*9/IFNG*1; OR = 1.58, p(c) = 0.0217). Furthermore, a protective IL12B haplotype was found (D5S2038*4/D5S1352*1/SNP1188A; OR = 0.40, p(c) = 0.0405). No association was found for any of IL12B and IFNG markers individually.

A C/T polymorphism in the 5' untranslated region of the CD40 gene is associated with later onset of Graves' disease in Japanese

Graves' disease (GD) is an autoimmune disorder with genetic predisposition. CD40, which stimulates lymphocyte proliferation and differentiation, is an important immunomodulator and is expressed in the thyroid follicular cells as well as antigen-presenting cells. A single nucleotide polymorphism (SNP) at position -1 of the Kozak sequence of the CD40 gene has been reported to be associated with the development of GD. The aim of the present study was to investigate whether CD40 gene polymorphism confers susceptibility to GD in Japanese. CD40 gene polymorphisms were studied in Japanese GD patients (n = 324) and healthy control subjects without anti-thyroid autoantibodies or a family history of autoimmune disorders (n = 229). A C/T polymorphism at position -1 of the CD40 gene was measured using the polymerase chain reaction restriction fragment length polymorphism. There was no significant difference in allele or genotype frequency of the CD40 SNP between GD and control subjects. There was a significant decrease in the TT genotype frequency in the GD patients, who developed GD after 40 years old, than those under 40 year of age. These data suggest that the SNP of CD40 gene is associated with susceptibility to later onset of GD in Japanese.

Immunosurveillance of childhood ALL: polymorphic interferon-γ alleles are associated with age at diagnosis and clinical risk groups

Interferon-gamma (IFN-gamma) has been implicated as an important mediator of antitumor immunity in murine model systems. To determine whether a CA-repeat associated with differential NFkappaB-binding and IFN-gamma-expression levels may influence the incidence, manifestation and early clinical treatment response of childhood acute lymphoblastic leukemia, we performed PCR-based genotyping of 393 patients with ALL and 207 healthy controls. We could not find any differences in the allele distribution comparing patients and controls. However, when we further analyzed the allele frequencies with respect to age of clinical manifestation, we found that patients with B-lineage ALL showing the IFN-gamma high-expressing genotype presented at a more advanced age compared to those patients with intermediate and low-expressing genotypes (median 6 vs 4.4 years, P=0.01). Furthermore, we found a significantly higher number of low expressors in the group of high-risk patients (HR n=32 and MR/SR n=266, P=0.025, defined by prednisone response, cytological remission and minimal residual disease (MRD)) with B-lineage ALL. Thus, we provide evidence that polymorphic IFN-gamma alleles are associated with age at clinical presentation and risk groups such as prednisone response in B-lineage ALL, suggesting distinct effects of IFN-gamma in immunosurveillance and early response to steroid therapy.

IL-10 haplotypes as possible predictors of spontaneous clearance of HCV infection

BACKGROUND

In hepatitis C virus infection an inappropriate ratio of pro-inflammatory and anti-inflammatory cytokines may either determine different outcomes of the infection or affect the benefit of antiviral treatment. Given that polymorphisms in regulatory regions of cytokine genes influence cytokine production, we determined frequency of polymorphisms of IL-10, IFNgamma, and TNFalpha genes in HCV-infected patients and healthy controls, and investigated their association with either ongoing or cleared HCV infection, or with response to treatment.

METHODS

Genomic DNA from 270 patients and 145 controls sharing the same ethnic background was studied by polymerase chain reaction, restriction enzyme digestion, direct sequencing, and microsatellite analysis.

RESULTS

The IL-10 ATA haplotype was more frequent in patients with spontaneous HCV RNA clearance (36.0%) than in patients with persistent infection (23%) (p=0.009, p corrected = 0.036). Neither TNF -308 and -238 polymorphisms nor IFNgamma alleles variability were associated with different HCV outcome. However, the combination of ATA homozygous state and IFNgamma 119 allele was more frequent in patients with spontaneous HCV clearance than in patients with ongoing disease (p=0.012; p corrected = 0.048). We could not confirm the reported effect of genetic influence on the response to treatment.

CONCLUSIONS

Our findings indicate that heterogeneity in the promoter region of the IL-10 gene has a role in determining a spontaneous favourable outcome of HCV infection.

The contribution of immune regulatory and thyroid specific genes to the etiology of Graves' and Hashimoto's diseases

The autoimmune thyroid diseases (AITD) are complex diseases which are caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility in combination with external factors (e.g. dietary iodine) are believed to initiate the autoimmune response to thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence on the development of AITD. Various techniques have been employed to identify the genes contributing to the etiology of AITD, including candidate gene analysis and whole genome screening. These studies have enabled the identification of several loci (genetic regions) that are linked with AITD, and in some of these loci putative AITD susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD) and Hashimoto's thyroiditis (HT) and some are common to both diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune modifying genes (e.g. HLA, CTLA-4) and thyroid specific genes (e.g. TSHR, Tg). Most likely these loci interact and their interactions may influence disease phenotype and severity.

New understanding of the role of cytokines in the pathogenesis of Graves' ophthalmopathy

Cytokines play a key role in the development of Graves' ophthalmopathy (GO). These molecules are produced in the orbit of GO patients by infiltrating inflammatory cells as well as orbital fibroblasts. Locally produced cytokines stimulate fibroblast proliferation and their production of glycosaminoglycans, which result in accumulation of extracellular matrix and oedema with consequent proptosis. In addition to these direct effects, cytokines can modulate the immune reaction in GO by increasing major histocompatibility complex (MHC) class II, adhesion molecules, CD40, prostaglandin and heat shock protein expression in the orbit, thereby having a role in localising and augmenting the inflammatory response.

A polymorphism of interferon-gamma gene associated with changes of anti-thyrotropin receptor antibodies induced by antithyroid drug treatment for Graves' disease in Japanese patients

Graves' disease (GD) is an autoimmune disorder with genetic predisposition. Interferon-gamma (IFN-gamma) is an important mediator of inflammatory and immune responses. The aim of the present study was to investigate whether the polymorphism of IFN-gamma gene is associated with the development of GD or with clinical course during the antithyroid drug therapy. We have studied the CA repeat polymorphisms in the first intron of IFN gamma gene in Japanese patients with GD (n = 162) and healthy control subjects without antithyroid autoantibodies or family history of autoimmune disorders (n = 133). There was no difference in allele frequency of IFN-gamma gene polymorphism between patients with GD and control subjects. However, the allele 4 (15 CA repeats) frequency was significantly greater in patients whose antithyrotropin receptor antibody (TRAb) became negative within 3 years by antithyroid drug treatment than those with consistently positive TRAb for more than 3 years (34.1% vs. 15.7%, chi2 = 8.545, p = 0.0035, pc = 0.049). The in vitro production of IFN-gamma by concanavalin A-stimulated peripheral blood mononuclear cells was significantly smaller in control subjects with the allele 4 compared to those with the other alleles. In conclusions, the CA repeat polymorphism of the IFN-gamma gene might be associated with the outcome of anti-thyroid drug treatment.

Linkage at 12q24 with systemic lupus erythematosus (SLE) is established and confirmed in Hispanic and European American families

Systemic lupus erythematosus (SLE) is a chronic, complex, and systemic human autoimmune disease, with both an environmental component and a heritable predisposition. Clinical studies, reinforced by epidemiology and genetics, show impressive variation in disease severity, expression, prevalence, and incidence by ethnicity and sex. To identify the novel SLE susceptibility loci, we performed a genomewide scan with 318 markers on 37 multiplex Hispanic families, using a nonparametric penetrance-independent affected-only allele-sharing method. Three chromosomal regions (12q24, 16p13, and 16q12-21) exceeded our predetermined threshold (Zlr>2.32; nominal P<.01) for further evaluation. Suspected linkages at 12q24, 16p13, and 16q12-21 were tested in an independent data set consisting of 92 European American (EA-1) and 55 African American (AA) families. The linkage at 12q24 was replicated in EA-1 (Zlr=3.06; P=.001) but not in AA (Zlr=0.37; P=.35). Although neither the 16p13 nor the 16q12-21 was confirmed in EA-1 or AA, the suggestive linkage (Zlr=3.06; P=.001) at 16q12-21 is sufficient to confirm the significant linkage, reported elsewhere, at this location. The evidence for linkage at 12q24 in the 129 combined (Hispanic and EA-1) families exceeded the threshold for genomewide significance (Zlr=4.39; P=5.7x10-6; nonparametric LOD=4.19). Parametric linkage analyses suggested a low-penetrance, dominant model (LOD=3.72). To confirm the linkage effect at 12q24, we performed linkage analysis in another set of 82 independent European American families (EA-2). The evidence for linkage was confirmed (Zlr=2.11; P=.017). Therefore, our results have detected, established, and confirmed the existence of a novel SLE susceptibility locus at 12q24 (designated "SLEB4") that may cause lupus, especially in Hispanic and European American families.

Idiopathic thrombocytopenic purpura in adults

Immune thrombocytopenic purpura (ITP) is an organ-specific autoimmune disorder in which platelets opsonized by antiplatelet antibodies are destroyed by the reticuloendothelial system. As a result the peripheral blood platelet count is low; if sufficiently severe, it may lead to bruising and mucocutaneous bleeding. The disorder may occur in adults and in children; in the former the disease affects primarily females, whereas the childhood type affects the sexes equally. For most individuals the disorder is minor, requiring little treatment, but patients with more severe forms of the disease require therapy to elevate the platelet count to a safe level to prevent serious bleeding. Therapies include corticosteroids, intravenous immunoglobulin, splenectomy, and immunosuppressive agents. Because there have been few trials in ITP, there is little evidence to guide treatment, and all the treatments may have adverse effects in terms of morbidity and mortality. The American Society of Hematology and British Committee for Standards in Haematology guidelines provide a framework for management but nonetheless are based on little evidence. In this paper the authors review the management of ITP in adults, children, and pregnant women and highlight some of the novel therapies being explored in this disorder, in addition to some of the ongoing laboratory research exploring the mechanisms underlying the disease.

Current perspective on the pathogenesis of Graves' disease and ophthalmopathy

Graves' disease (GD) is a very common autoimmune disorder of the thyroid in which stimulatory antibodies bind to the thyrotropin receptor and activate glandular function, resulting in hyperthyroidism. In addition, some patients with GD develop localized manifestations including ophthalmopathy (GO) and dermopathy. Since the cloning of the receptor cDNA, significant progress has been made in understanding the structure-function relationship of the receptor, which has been discussed in a number of earlier reviews. In this paper, we have focused our discussion on studies related to the molecular mechanisms of the disease pathogenesis and the development of animal models for GD. It has become apparent that multiple factors contribute to the etiology of GD, including host genetic as well as environmental factors. Studies in experimental animals indicate that GD is a slowly progressing disease that involves activation and recruitment of thyrotropin receptor-specific T and B cells. This activation eventually results in the production of stimulatory antibodies that can cause hyperthyroidism. Similarly, significant new insights have been gained in our understanding of GO that occurs in a subset of patients with GD. As in GD, both environmental and genetic factors play important roles in the development of GO. Although a number of putative ocular autoantigens have been identified, their role in the pathogenesis of GO awaits confirmation. Extensive analyses of orbital tissues obtained from patients with GO have provided a clearer understanding of the roles of T and B cells, cytokines and chemokines, and various ocular tissues including ocular muscles and fibroblasts. Equally impressive is the progress made in understanding why connective tissues of the orbit and the skin in GO are singled out for activation and undergo extensive remodeling. Results to date indicate that fibroblasts can act as sentinel cells and initiate lymphocyte recruitment and tissue remodeling. Moreover, these fibroblasts can be readily activated by Ig in the sera of patients with GD, suggesting a central role for them in the pathogenesis. Collectively, recent studies have led to a better understanding of the pathogenesis of GD and GO and have opened up potential new avenues for developing novel treatments for GD and GO.

Polymorphisms of IL-1B, IL-1RN, IL-2, IL-4, IL-6, IL-10, and IFN-γ genes in the Korean population

Cytokines play a crucial role in regulating the immune and inflammatory responses. The collective influence of several cytokines can regulate immune responses as complex as those underlying allograft rejections or autoimmune diseases. Polymorphisms in the regulatory regions of the cytokine genes may influence their expression. Therefore, the polymorphisms of cytokine genes are potentially important as genetic predictors of the disease susceptibility or clinical outcome. In 311 unrelated healthy Korean individuals, we investigated the polymorphisms of cytokine genes (interleukin-1 [IL-1], IL-2, IL-4, IL-6, IL-10, and interferon-gamma [IFN-gamma]), which had been previously reported to be associated with a number of immune diseases, transplant complications, and direct or indirect influences on the level of expression and production. And we also compared the results to those published for other populations. The genotype distributions were consistent with the assumption of the Hardy-Weinberg equilibrium, with the exceptions of IL-1B +3954 and IL-6-174 polymorphisms. The polymorphisms examined in this study were almost similar to that observed in Asian populations. There were significant differences of the polymorphisms, except for IL-4 receptor alpha +1902, between Korean and other populations. Comparing the alleles associated with higher level of expression and production, IL-1B +3954*T, IL-2-330*G, and IL-4-590*T alleles were significantly higher, and IL-1RN*A2, IL-10-1082*G, and IFN-gamma*2 alleles were lower in Koreans than other populations. Especially in IL-6 promoter -174 polymorphism, we found only the G allele associated with higher plasma IL-6 levels. In haplotype analysis of IL-10 promoter polymorphisms, the GCC haplotype, associated with higher expression of IL-10, was significantly lower in Koreans. These results may be helpful for understanding transplant-related complications, immune or autoimmune diseases, and malignant diseases in the Korean population.

Searching for the autoimmune thyroid disease susceptibility genes: from gene mapping to gene function

The autoimmune thyroid diseases (AITD) are complex diseases that are caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility, in combination with external factors (e.g., dietary iodine), is believed to initiate the autoimmune response to thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence on the development of AITD. Various techniques have been used to identify the genes contributing to the etiology of AITD, including candidate gene analysis and whole genome screening. These studies have enabled the identification of several loci (genetic regions) that are linked with AITD, and in some of these loci putative AITD susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD) and Hashimoto's thyroiditis (HT), and some are common to both diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune modifying genes (e.g., human leukocyte antigen, cytotoxic T lymphocyte antigen-4) and thyroid-specific genes (e.g., TSH receptor, thyroglobulin). Most likely these loci interact, and their interactions may influence disease phenotype and severity. It is hoped that in the near future additional AITD susceptibility genes will be identified and the mechanisms by which they induce AITD will be unraveled.

CTLA-4 gene A-G polymorphism and childhood Graves' disease

OBJECTIVE

Graves' disease is associated with a polymorphism at position 49 in exon 1 of the cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene in Caucasians and Japanese. A high incidence of childhood Graves' disease has been documented in Hong Kong Chinese. The aims of this study were to investigate the CTLA-4 gene A-G polymorphism association in Chinese children with Graves' disease.

PATIENTS AND DESIGN

One hundred and twenty-three Chinese children with Graves' disease (104 girls and 19 boys) and 158 racially matched healthy controls were recruited for the study. Genomic DNA was extracted from venous blood samples. The dimorphism at position 49 A-G was analysed by polymerase chain reaction, single-strand conformation polymorphism and restriction fragment-length polymorphism analysis.

RESULTS

The genotype distribution and allele frequencies of children with Graves' disease differed significantly from those of the controls (P = 0.0023 and P = 0.022, respectively). The presence of at least one G allele (GG or AG) was associated with an increased risk of Graves' disease (OR = 6.8, 95% CI = 2.0-36.1; P = 0.001).

CONCLUSIONS

This study confirms that CTLA-4 49 A-G polymorphism is associated with Graves' disease in Chinese children. The CTLA-4 49 G allele confers an increased risk of childhood Graves' disease.

Role of cytokines in the pathogenesis of thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is generally considered to be an autoimmune disorder associated with Graves' disease. However, the nature of autoantigen or mechanism of the development of ophthalmopathy remains unclear. In the present review we focus the accumulating evidence on roles of cytokines in the orbital tissues from patients with TAO and animal models. From the analysis of T-cell clones, T helper 1 (T(H)1)-like clones were predominant in cultures from patients with recent onset hyperthyroidism and T(H)2-like clones were predominant in culture form patients with more remote onset hyperthyroidism. T(H)1-like cytokine profiles are predominant in eye muscle tissue and related to the eye muscle enlargement, while T(H)2-like cytokine profiles are predominant in orbital fat tissue from patients with TAO and negatively related to orbital volume. Therefore, T(H)1-like cytokines, proinflammatory cytokines, may play a role on the development of eye muscle component of TAO in the acute stage. T(H)2-like cytokines, anti-inflammatory cytokines, may play protective role in the chronic stage of TAO. The studies using animal models suggest the genetic background is involved in the pathogenesis of TAO. The studies on polymorphism of the cytokine genes support the proinflammatory role of T(H)1-like cytokines and protective role of T(H)2-like cytokines.

GvHD risk assessment in hematopoietic stem cell transplantation: role of cytokine gene polymorphisms and an in vitro human skin explant model

This present review concentrates on the recent results investigating the role of certain cytokine gene polymorphisms, including tumor necrosis factor alpha, interferon gamma, interleukin-6 (IL-6), IL-10, and IL-1 receptor antagonist, in allogeneic stem cell transplantation. The review discusses their potential role in predicting outcome and the development of a genetic risk index for graft-versus-host disease in human leukocyte antigen matched sibling transplants. By the comparative use of an in vitro human skin explant model, initial results suggest that certain polymorphisms may be associated with more severe disease.

SEL1L microsatellite polymorphism in Japanese patients with autoimmune thyroid diseases

The autoimmune thyroid diseases (AITDs), comprising Graves' disease (GD) and Hashimoto's thyroiditis (HT), appear to develop as a result of complex interactions between predisposing genes and environmental triggers. A recently performed genome-wide linkage study identified six loci that showed evidence for linkage to AITD. One locus, GD-1, on chromosome 14q31 was mapped to within 2 centimorgans (cM) of the recently reported multinodular goiter (MNG)-1 locus. Furthermore, microsatellite markers for the thyroid stimulating hormone receptor gene on chromosome 14q31 were associated with AITDs in the Japanese population. A newly isolated growth factor, SEL1L, was recently mapped to 14q31, and we considered it an interesting candidate gene to examine with respect to both GD and MNG. We therefore have analyzed a dinucleotide (CA)n repeat polymorphism in the intron 20 of the SEL1L gene in patients with AITDs and in normal subjects. The polymorphic marker was analyzed by polymerase chain reaction (PCR) followed by electrophoresis on denaturing polyacrylamide gels. There was no significant difference in the distributions of SEL1L alleles between patients and controls. The present results do not support an association between a dinucleotide repeat polymorphism in intron 20 of the SEL1L gene and AITD in Japanese women.

Association of IFN-gamma and IFN regulatory factor 1 polymorphisms with childhood atopic asthma

BACKGROUND

IFN-gamma and related molecules play important roles in the differentiation and function of TH2 cells.

OBJECTIVE

We sought to determine whether IFNG and related genes contribute to any susceptibility to atopic asthma, a representative TH2-dominant disorder.

METHODS

We investigated the association of IFNG (CA repeat polymorphism within the first intron), IRF1 (GT repeat polymorphism within the intron 7), IFNGR1 (Val 14 Met), and IFNGR2 (Gln 64 Arg) gene polymorphisms with atopic asthma in the Japanese child population.

RESULTS

A significant association (P =.0018) was observed between IFNG gene polymorphism and atopic asthma. The tendency was more prominent in patients with age of onset of 3 years or younger (P =.0004) or patients with a family history of allergic diseases (P =.0038). Furthermore, there was a significant association between IRF1 gene whole-allele distribution and atopic asthma (P =.044). The tendency was more prominent in patients with onset at 3 years of age or less (P =.0058). On the other hand, IFNGR1 and IFNGR2 gene polymorphisms showed no association with atopic asthma.

CONCLUSION

These results suggested that among IFNG and related genes, IFNG and IRF1 genes confer genetic susceptibility to atopic asthma in Japanese children.

Estrogen receptor alpha dinucleotide repeat polymorphism in Japanese patients with autoimmune thyroid diseases

BACKGROUND

The autoimmune thyroid diseases (AITDs), comprising Graves' disease (GD) and Hashimoto's thyroiditis (HT), appear to develop as a result of complex interactions between predisposing genes and environmental triggers. Susceptibility to AITDs is conferred by genes in the human leukocyte antigen (HLA) and genes unlinked to HLA, including the CTLA-4 gene. Recently, an association to some estrogen receptor (ER)alpha genotypes with breast cancer, hypertension, osteoporosis, generalized osteoarthritis, and some autoimmune diseases such as rheumatoid arthritis has been reported. We have analyzed a dinucleotide (TA)n repeat polymorphism lying upstream of the human ERalpha gene in patients with AITDs and in normal subjects.

RESULTS

Seventeen different alleles were found in 130 patients with GD, 93 patients with HT, and 190 control subjects. There was no significant difference in the distributions of ERalpha alleles between patients and controls.

CONCLUSIONS

The present results do not support an association between the ERalpha gene and AITD in the Japanese population.

Association between dinucleotide repeat in non-coding region of interferon-gamma gene and susceptibility to, and severity of, rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis ranges from a mild, non-deforming arthropathy with little long-term disability to severe, incapacitating, deforming arthritis which may be refractory to conventional disease-modifying agents. Epidemiological studies show an important genetic influence in rheumatoid arthritis, and MHC region genes and cytokine genes within and outside this region have been considered as candidates. We did a case-control study to test whether polymorphisms in the interferon-gamma gene are associated with severity of rheumatoid arthritis.

METHODS

Interferon gamma dinucleotide repeat polymorphisms were examined with quantitative genescan technology, and HLA-DR alleles were identified by PCR and restriction-fragment-length polymorphism analysis. We studied 60 patients with severe rheumatoid arthritis, 39 with mild disease, and 65 normal controls.

FINDINGS

Susceptibility to, and severity of, rheumatoid arthritis were related to a microsatellite polymorphism within the first intron of the interferon-gamma gene. A 126 bp allele was seen in 44 (73%) of 60 patients with severe rheumatoid arthritis, compared with eight (21%) of 39 with mild disease (odds ratio 10.66 [95% CI 4.1-24.9]), and with eight (12%) of 65 normal controls (19.59 [7.7-49.9]). Conversely, a 122 bp allele at the same locus was found in four (7%) patients with severe disease compared with 25 (64%) of those with mild disease (0.04 [0.01-0.1]) and with 52 (80%) of controls (0.018 [0.005-0.06]).

INTERPRETATION

This association may be valuable for understanding the mechanism of disease progression, for predicting the course of the disease, and for guiding therapy.

Genetic determinants of Graves disease

Basedow-Graves disease is an autoimmune thyroid syndrome. Genetic factors contribute to the pathogenesis of Graves disease, and current findings confirm that a number of genes may be involved in the development of autoimmune thyrotoxicosis. At present three loci, namely human leukocyte antigen (HLA, 6p21.3), cytotoxic T-lymphocyte-associated esterase-4 (CTLA4, 2q33), and thyroid-stimulating hormone receptor (TSHR, 14q31), are the only well-known genetic determinants for Graves disease. It is difficult to determine clearly the contribution of large multifunctional proteasome genes and transporter genes associated with antigen processing in the disorder, because of strong linkage disequilibrium between these genes and certain HLA alleles. Two recently discovered suspectibility loci, 20q11.2 and Xq21.33-q22, should be studied to find specific genes linked to Graves disease.