Association of CD40 gene polymorphism (C-1T) with susceptibility and phenotype of Graves' disease

HLA Class II Allele Groups Involved in Autoimmune Thyroid Diseases: Hashimoto's Thyroiditis and Basedow-Graves Disease

Autoimmune thyroid diseases (AITD), particularly Hashimoto's thyroiditis (HT) and Basedow-Graves disease (BGD) are diseases of global public health concern, characterized by autoimmune attacks on the thyroid gland, leading to hypothyroidism in HT and hyperthyroidism in BGD. We conducted a study between 2019 and 2021 in northwestern Transylvania (Romania) on patients with HT and with BGD compared to the control group. The aim of the study was to investigate the correlations of HLA class II alleles with AITD by identifying potential genetic susceptibility factors such as HLA-DRB1 and HLA-DQB1 genes in patients diagnosed with HT and BGD. Various molecular biology methods, including SSP-PCR low-resolution and PCR-SSO were employed to analyze DNA samples from patients and control subjects. Our study revealed the influence of the HLA-DRB1*03/*16 genotype as a genetic susceptibility factor for HT, a similar influence regarding BGD being observed for the HLA-DRB1*03 allele group, DRB1*03/*16 genotype, and the DRB1*03/DQB1*06 haplotype. The only protective factor detected in our study was the HLA-DRB1*13 allele group, for both HT and BGD. By elucidating any specific allele or genotype associations that might contribute to the development of AITD, our study can contribute to the prevention and early detection of these diseases.

Molecular Mechanisms in Autoimmune Thyroid Disease

The most common cause of acquired thyroid dysfunction is autoimmune thyroid disease, which is an organ-specific autoimmune disease with two presentation phenotypes: hyperthyroidism (Graves-Basedow disease) and hypothyroidism (Hashimoto’s thyroiditis). Hashimoto’s thyroiditis is distinguished by the presence of autoantibodies against thyroid peroxidase and thyroglobulin. Meanwhile, autoantibodies against the TSH receptor have been found in Graves-Basedow disease. Numerous susceptibility genes, as well as epigenetic and environmental factors, contribute to the pathogenesis of both diseases. This review summarizes the most common genetic, epigenetic, and environmental mechanisms involved in autoimmune thyroid disease.

Genetics and epigenetics of autoimmune thyroid diseases: Translational implications

Hashimoto's thyroiditis (HT) and Graves' disease (GD) are prevalent autoimmune disorders, representing opposite ends of the clinical spectrum of autoimmune thyroid diseases (AITD). The pathogenesis involves a complex interplay between environment and genes. Specific susceptibility genes have been discovered that predispose to AITD, including thyroid-specific and immune-regulatory genes. Growing evidence has revealed that genetic and epigenetic variants can alter autoantigen presentation during the development of immune tolerance, can enhance self-peptide binding to MHC (major histocompatibility complex), and can amplify stimulation of T- and B-cells. These gene-driven mechanistic discoveries lay the groundwork for novel treatment targets. This review summarizes recent advances in our understanding of key AITD susceptibility genes (Tg¹, TSHR, HLA-DR3, and CD40) and their translational therapeutic potential.

Precision Medicine in Graves' Disease: CD40 Gene Variants Predict Clinical Response to an Anti-CD40 Monoclonal Antibody

BACKGROUND

CD40, a key co-stimulatory molecule expressed on antigen-presenting cells, is genetically associated with a number of autoimmune diseases including Graves' disease (GD). Therefore, recent therapies targeting CD40 have been developed, including the anti-CD40 monoclonal antibody Iscalimab. In a recent pilot study, Iscalimab was shown to induce clinical remission in ~ 50% of GD patients, but the reason why only 50% of GD patients responded is not known. The aim of our study was to test the hypothesis that specific CD40 single nucleotide polymorphism (SNP) genotypes and haplotypes are associated with clinical response of GD patients to Iscalimab.

METHODS

We extracted genomic DNA from the whole blood of 13 GD patients treated with Iscalimab, and genotyped seven CD40 single nucleotide polymorphisms (SNPs) associated with autoimmunity. Additionally, we analyzed CD40 mRNA expression levels in whole blood. The patients' CD40 SNP genotypes and mRNA levels were tested for association with clinical response to Iscalimab.

RESULTS

Three common haplotypes, designated haplotypes A, B, and C, were identified. Haplotypes B and C were associated with higher CD40 mRNA levels and clinical response to Iscalimab (i.e., patients achieving euthyroidism without need for additional medications), while haplotype A was associated with decreased CD40 mRNA levels and no response to Iscalimab.

CONCLUSION

Our data suggest that genetic polymorphisms in the CD40 gene drive its expression levels and response to Iscalimab. Polymorphisms associated with higher CD40 levels are also associated with clinical response to CD40-targeted therapies. These results set the stage to implementing precision medicine in the therapeutic approach to GD.

Compelling Evidence Linking CD40 Gene With Graves' Disease in the Chinese Han Population

Mutations in CD40 have been widely reported to be risk factors for Graves' disease (GD). The gene, along with its cognate ligand CD40L, may regulate pro-inflammatory and immune responses. Rs1883832, located at the -1 position of the Kozak sequence, is the most well-studied single nucleotide polymorphism (SNP) of CD40, and has been confirmed to predispose those with the alteration to GD, regardless of ethnicity. Our genome-wide association study (GWAS) indicated that several SNPs, including rs1883832 located within the vicinity of CD40 were associated with GD in the Han Chinese population. Aiming at identifying the most consequential SNP and its underlying pathogenic mechanism, we performed a two-stage refined study on 8,171 patients with GD and 7,906 controls, and found rs1883832 was the most significantly GD-associated SNP in the CD40 gene region (P_Combined = 9.17×10^-11, OR = 1.18). Through searching the cis-expression quantitative trait locus database and using quantitative RT-PCR, we further discovered that the rs1883832 genotype can influence CD40 gene transcription. Furthermore, we demonstrated that rs1883832 is a susceptibility locus for pTRAb+ GD patients. In conclusion, the current study provides robust evidence that rs1883832 can regulate CD40 gene expression and affect serum TRAb levels, which ultimately contributes to the development of GD.

IRAK1 Gene Polymorphism in Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease. The present study intends to specify rs1059703, rs4810485, and rs1883832 gene polymorphisms of interleukin-1 receptor-associated kinase (IRAK1) and cluster of differentiation 40 (CD40) in RA. IRAK1 is a serine/threonine kinase and CD40 is a tumor necrosis factor receptor, both of which are involved in RA. There are conflicting results on functional effects of these polymorphisms, so we performed this research for a more accurate estimation on rheumatoid arthritis risk. Methods: Two-hundred RA patients diagnosed according to ACR criteria and 200 normal controls participated in this case-control study. DNA Purification kit (Gene Transfer Pioneers, GTP) was used for genomic DNA extraction and three SNPs, including IRAK1 rs1059703 (C/T), CD40 rs1883832 (C/T) and rs4810485 (G/T), were genotyped by PCR-RFLP. The genotypes and allele frequencies of SNPs were analyzed by chi-square test to detect their contribution to RA. Results: A significant correlation was found between rs1059703 T allele (OR = 2.36, 95% CI = 1.7-3.1, p = .0001) and TT and CT genotypes (TT genotype, OR = 2.54, 95%CI = 1.2-3.3, P = .0078, CT genotype; OR = 2.18 95%CI = 1.4-3.2P = .0002) of rs1059703 C/T polymorphism in terms of susceptibility to RA in recessive and over-dominant models. Alleles and genotypes of CD40 SNPs were not significantly different between RA cases and controls. The findings showed significant differences in rs1059703 IRAK1 genotypes with medical and laboratory features of patients. Conclusion: Our results showed that the rs1059703 T allele (risk allele) of IRAK1 gene increases the risk of RA and the severity of disease, affecting the onset age of RA in Iranian patients.

Insulin-like Growth Factor-I Receptor and Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a complex disease process presumed to emerge from autoimmunity occurring in the thyroid gland, most frequently in Graves disease (GD). It is disfiguring and potentially blinding, culminating in orbital tissue remodeling and disruption of function of structures adjacent to the eye. There are currently no medical therapies proven capable of altering the clinical outcome of TAO in randomized, placebo-controlled multicenter trials. The orbital fibroblast represents the central target for immune reactivity. Recent identification of fibroblasts that putatively originate in the bone marrow as monocyte progenitors provides a plausible explanation for why antigens, the expressions of which were once considered restricted to the thyroid, are detected in the TAO orbit. These cells, known as fibrocytes, express relatively high levels of functional TSH receptor (TSHR) through which they can be activated by TSH and the GD-specific pathogenic antibodies that underpin thyroid overactivity. Fibrocytes also express insulin-like growth factor I receptor (IGF-IR) with which TSHR forms a physical and functional signaling complex. Notably, inhibition of IGF-IR activity results in the attenuation of signaling initiated at either receptor. Some studies suggest that IGF-IR-activating antibodies are generated in GD, whereas others refute this concept. These observations served as the rationale for implementing a recently completed therapeutic trial of teprotumumab, a monoclonal inhibitory antibody targeting IGF-IR in TAO. Results of that trial in active, moderate to severe disease revealed dramatic and rapid reductions in disease activity and severity. The targeting of IGF-IR with specific biologic agents may represent a paradigm shift in the therapy of TAO.

Graves' disease: Introduction, epidemiology, endogenous and environmental pathogenic factors

Graves' disease is the most frequent cause of hyperthyroidism. Many questions remain about the choice of diagnostic evaluations and treatment strategy according to clinical context (age, gender, pregnancy, etc.) and about the best management of the main extrathyroidal complication that is Graves orbitopathy. The exact pathogenic mechanisms are not fully clear. They associate genetic factors, interactions between endogenous and environmental factors, and immune system dysregulation. Graves' orbitopathy is one of the consequences of this partial understanding. Iatrogenic Graves' disease induced by the new targeted therapies are described and could help to better understand the molecular pathways involved in the disease and to develop new therapeutic approaches.

Association between CD40 rs1883832 and immune-related diseases susceptibility: A meta-analysis

Background/objective

It has been reported that CD40 rs1883832 might be associated with immune-related diseases susceptibility. Owing to mixed and inconclusive results, we conducted a meta-analysis of case–control studies to summarize and clarify this association.

Methods/main results

A systematic search of studies on the association between CD40 rs1883832 and immune-related diseases susceptibility was conducted in databases. Odds ratios and 95% confidence intervals were used to pool the effect size. 40 articles were included in our meta-analysis.

Conclusions

CD40 rs1883832 is associated with decreased risk of Graves’ disease, especially in Asian; CD40 rs1883832 is associated with increased risk of multiple sclerosis; CD40 -1C>T (rs1883832) is not associated with the susceptibility of Hashimoto's thyroiditis, systemic sclerosis or Asthma; there is insufficient data to fully confirm the association between CD40 rs1883832 and systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Behçet's disease (BD), myasthenia gravis (MG), Crohn's disease (CD), ulcerative colitis (UC), Sarcoidosis, Fuch uveitis syndrome (FUS), Vogt-Koyanagi-Harada syndrome (VKH), Kawasaki disease (KD), giant cell arteritis (GCA) or Immune thrombocytopenia (ITP).

CD40 Signaling in Graves Disease Is Mediated Through Canonical and Noncanonical Thyroidal Nuclear Factor κB Activation

CD40, a tumor necrosis factor receptor, is a major immune-modulating susceptibility gene for Graves disease (GD) as well as for a variety of other autoimmune diseases. Its broad association with autoimmunity underscores its paramount role in the development of a normal adaptive immune response, primarily in coordinating effective antigen presentation. The molecular pathways by which CD40 activation in the thyroid induces GD are unknown. In this study, we investigated whether NF-κB, a ubiquitious family of transcription factors, mediates the downstream effects of thyroid-specific CD40 activation. Cultured primary human thyrocytes, from patients with and without GD, underwent CD40 stimulation. Once stimulated, cytokines and transcription factors specific for either the canonical nuclear factor κB (NF-κB)1 pathway [interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α], which primarily recruits cells for innate immunity, or the noncanonical NF-κB2 pathway [B cell-activating factor of the TNF family, CC chemokine ligand (CCL)21], which directs B cell viability, were analyzed. Significant upregulation in the messenger RNA and protein levels of both canonical and noncanonical pathway cytokines was observed. Western blot analyses of the specific transcription factors for the NF-κB1 and NF-κB2 pathways (p65 and p100/p52, respectively) demonstrated that p65 is constitutively expressed. In contrast, CD40 stimulation robustly increased the expression of the NF-κB2 p52 transcription factor, and the upregulation was significantly more profound in the GD tissue than in the normal thyroid tissue. Our data show that CD40 activity in thyrocytes is prominently mediated via NF-κB and furthermore suggest that the NF-κB1 and NF-κB2 pathways both contribute to the triggering and the progression of GD.

Predictive Value of Gene Polymorphisms on Recurrence after the Withdrawal of Antithyroid Drugs in Patients with Graves' Disease

Graves' disease (GD) is one of the most common endocrine diseases. Antithyroid drugs (ATDs) treatment is frequently used as the first-choice therapy for GD patients in most countries due to the superiority in safety and tolerance. However, GD patients treated with ATD have a relatively high recurrence rate after drug withdrawal, which is a main limitation for ATD treatment. It is of great importance to identify some predictors of the higher recurrence risk for GD patients, which may facilitate an appropriate therapeutic approach for a given patient at the time of GD diagnosis. The genetic factor was widely believed to be an important pathogenesis for GD. Increasing studies were conducted to investigate the relationship between gene polymorphisms and the recurrence risk in GD patients. In this article, we updated the current literatures to highlight the predictive value of gene polymorphisms on recurrence risk in GD patients after ATD withdrawal. Some gene polymorphisms, such as CTLA4 rs231775, human leukocyte antigen polymorphisms (DRB1*03, DQA1*05, and DQB1*02) might be associated with the high recurrence risk in GD patients. Further prospective studies on patients of different ethnicities, especially studies with large sample sizes, and long-term follow-up, should be conducted to confirm the predictive roles of gene polymorphism.

Pooled genome wide association detects association upstream of FCRL3 with Graves' disease

Background

Graves’ disease is an autoimmune thyroid disease of complex inheritance. Multiple genetic susceptibility loci are thought to be involved in Graves’ disease and it is therefore likely that these can be identified by genome wide association studies. This study aimed to determine if a genome wide association study, using a pooling methodology, could detect genomic loci associated with Graves’ disease.

Results

Nineteen of the top ranking single nucleotide polymorphisms including HLA-DQA1 and C6orf10, were clustered within the Major Histo-compatibility Complex region on chromosome 6p21, with rs1613056 reaching genome wide significance (p = 5 × 10⁻⁸). Technical validation of top ranking non-Major Histo-compatablity complex single nucleotide polymorphisms with individual genotyping in the discovery cohort revealed four single nucleotide polymorphisms with p ≤ 10⁻⁴. Rs17676303 on chromosome 1q23.1, located upstream of FCRL3, showed evidence of association with Graves’ disease across the discovery, replication and combined cohorts. A second single nucleotide polymorphism rs9644119 downstream of DPYSL2 showed some evidence of association supported by finding in the replication cohort that warrants further study.

Conclusions

Pooled genome wide association study identified a genetic variant upstream of FCRL3 as a susceptibility locus for Graves’ disease in addition to those identified in the Major Histo-compatibility Complex. A second locus downstream of DPYSL2 is potentially a novel genetic variant in Graves’ disease that requires further confirmation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3276-z) contains supplementary material, which is available to authorized users.

Thyrotropin Receptor Epitope and Human Leukocyte Antigen in Graves' Disease

Graves' disease (GD) is an organ-specific autoimmune disease, and thyrotropin (TSH) receptor (TSHR) is a major autoantigen in this condition. Since the extracellular domain of human TSHR (TSHR-ECD) is shed into the circulation, TSHR-ECD is a preferentially immunogenic portion of TSHR. Both genetic factors and environmental factors contribute to development of GD. Inheritance of human leukocyte antigen (HLA) genes, especially HLA-DR3, is associated with GD. TSHR-ECD protein is endocytosed into antigen-presenting cells (APCs), and processed to TSHR-ECD peptides. These peptide epitopes bind to HLA-class II molecules, and subsequently the complex of HLA-class II and TSHR-ECD epitope is presented to CD4+ T cells. The activated CD4+ T cells secrete cytokines/chemokines that stimulate B-cells to produce TSAb, and in turn hyperthyroidism occurs. Numerous studies have been done to identify T- and B-cell epitopes in TSHR-ECD, including (1) in silico, (2) in vitro, (3) in vivo, and (4) clinical experiments. Murine models of GD and HLA-transgenic mice have played a pivotal role in elucidating the immunological mechanisms. To date, linear or conformational epitopes of TSHR-ECD, as well as the molecular structure of the epitope-binding groove in HLA-DR, were reported to be related to the pathogenesis in GD. Dysfunction of central tolerance in the thymus, or in peripheral tolerance, such as regulatory T cells, could allow development of GD. Novel treatments using TSHR antagonists or mutated TSHR peptides have been reported to be effective. We review and update the role of immunogenic TSHR epitopes and HLA in GD, and offer perspectives on TSHR epitope specific treatments.

Immunogenetics of autoimmune thyroid diseases: A comprehensive review

Both environmental and genetic triggers factor into the etiology of autoimmune thyroid disease (AITD), including Graves' disease (GD) and Hashimoto's thyroiditis (HT). Although the exact pathogenesis and causative interaction between environment and genes are unknown, GD and HT share similar immune-mediated mechanisms of disease. They both are characterized by the production of thyroid autoantibodies and by thyroidal lymphocytic infiltration, despite being clinically distinct entities with thyrotoxicosis in GD and hypothyroidism in HT. Family and population studies confirm the strong genetic influence and inheritability in the development of AITD. AITD susceptibility genes can be categorized as either thyroid specific (Tg, TSHR) or immune-modulating (FOXP3, CD25, CD40, CTLA-4, HLA), with HLA-DR3 carrying the highest risk. Of the AITD susceptibility genes, FOXP3 and CD25 play critical roles in the establishment of peripheral tolerance while CD40, CTLA-4, and the HLA genes are pivotal for T lymphocyte activation and antigen presentation. Polymorphisms in these immune-modulating genes, in particular, significantly contribute to the predisposition for GD, HT and, unsurprisingly, other autoimmune diseases. Emerging evidence suggests that single nucleotide polymorphisms (SNPs) in the immunoregulatory genes may functionally hinder the proper development of central and peripheral tolerance and alter T cell interactions with antigen presenting cells (APCs) in the immunological synapse. Thus, susceptibility genes for AITD contribute directly to the key mechanism underlying the development of organ-specific autoimmunity, namely the breakdown in self-tolerance. Here we review the major immune-modulating genes that are associated with AITD and their potential functional effects on thyroidal immune dysregulation.

Systematic confirmation study of GWAS-identified genetic variants for Kawasaki disease in a Chinese population

Genome-wide association studies (GWASs) have identified multiple single nucleotide polymorphisms (SNPs) associated with Kawasaki disease (KD). In this study, we replicated the associations of 10 GWAS-identified SNPs with KD in a Han Chinese population. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression, and cumulative effect of non-risk genotypes were also performed. Although none of the SNPs reached the corrected significance level, 4 SNPs showed nominal associations with KD risk. Compared with their respective wild type counterparts, rs1801274 AG+GG genotypes and rs3818298 TC+CC genotypes were nominally associated with the reduced risk of KD (OR = 0.77, 95% CI = 0.59-0.99, P = 0.045; OR = 0.74, 95% CI = 0.56-0.98, P = 0.038). Meanwhile, rs1801274 GG genotype, rs2736340 CC genotype or rs4813003 TT genotype showed a reduced risk trend (OR = 0.57, 95% CI = 0.35-0.93, P = 0.024; OR = 0.46, 95% CI = 0.26-0.83, P = 0.010; OR = 0.64, 95% CI = 0.43-0.94, P = 0.022), compared with rs1801274 AG+AA genotypes, rs2736340 CT+TT genotypes or rs4813003 TC+CC genotypes, respectively. Furthermore, a cumulative effect was observed with the ORs being gradually decreased with the increasing accumulative number of non-risk genotypes (Ptrend<0.001). In conclusion, our study suggests that 4 GWAS-identified SNPs, rs2736340, rs4813003, rs3818298 and rs1801274, were nominally associated with KD risk in a Han Chinese population individually and jointly.

rs3827440, a nonsynonymous single nucleotide polymorphism within GPR174 gene in X chromosome, is associated with Graves' disease in Polish Caucasian population

Recently Chu et al. conducted a two-stage genome wide association study in Chinese that identified a novel X-linked Graves' disease (GD) susceptibility marker at rs3827440 - a nonsynonymous (P162S) nucleotide transition (519C<T) within G protein-coupled receptor 174 (GPR174) gene. We aimed to replicate this finding in Caucasians. Using the TaqMan approach we typed rs3827440 in 560 GD patients from Warsaw and 196 patients from Gliwice as well as ethically matched controls (N = 748, N = 198, respectively). We found an association of the rs3827440 T allele with GD using both an allelic and genotype comparison [odds ratio (OR) = 1.19, 95% confidence interval (CI): 1.03-1.38, P = 0.021; OR=1.32, 95% CI: 1.03-1.69, P = 0.03, respectively]. There was no difference in distribution of rs3827440 alleles/genotypes vs gender, tobacco smoking, ophthalmopathy or age at disease onset. Also, no statistically significant differences were observed after stratifying patients for DRB1*03- or GD-associated variants in CTLA4 or TSHR genes. Our study provides the first replication in a Caucasian population of the association between GD and rs3827440 originally reported among Chinese. Our results also validate statistical methodology used by Chu et al. to detect associations with X-linked markers.

Single nucleotide polymorphism of CD40 in the 5'-untranslated region is associated with ischemic stroke

OBJECTIVES

Ischemic stroke is influenced by both environmental and genetic factors. The CD40/CD40L system is related to proinflammatory and prothrombogenic responses, which are involved in the pathophysiology of ischemic stroke. The aim of this study was to evaluate association between the CD40 -1C/T single nucleotide polymorphism (SNP) and ischemic stroke in a Chinese population.

METHODS

We conducted a case-control study including 286 ischemic stroke patients and 336 controls. CD40 -1C/T SNP was genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing methods, and evaluated its relevance to ischemic stroke susceptibility.

RESULTS

Significantly increased ischemic stroke risk was found to be associated with the T allele of CD40 -1C/T (OR=1.273, 95% CI=1.016-1.594). The frequencies of CT and TT/CT genotypes of CD40 -1C/T in ischemic stroke patients were significantly higher than those of controls, respectively (for CT: OR=2.350, 95% CI=1.601-3.449; for TT/CT: OR=2.148, 95% CI=1.479-3.119). And, similar results were obtained after adjusting non-matched variables. We found that the frequency of carried T genotypes (TT and TT/CT) was significantly increased in patients with history of stroke compared with patients without (for TT: OR=6.538, 95%CI=1.655-25.833; for TT/CT: OR=3.469, 95%CI=1.031-11.670), respectively.

CONCLUSIONS

The findings suggested that the CD40 -1C/T polymorphism might contribute to the susceptibility to ischemic stroke in the Chinese population, and might be associated with history of previous stroke.

Association between age at diagnosis of Graves' disease and variants in genes involved in immune response

Background

Graves' disease (GD) is a complex disease in which genetic predisposition is modified by environmental factors. The aim of the study was to examine the association between genetic variants in genes encoding proteins involved in immune response and the age at diagnosis of GD.

Methods

735 GD patients and 1216 healthy controls from Poland were included into the study. Eight genetic variants in the HLA-DRB1, TNF, CTLA4, CD40, NFKb, PTPN22, IL4 and IL10 genes were genotyped. Patients were stratified by the age at diagnosis of GD and the association with genotype was analysed.

Results

Polymorphism in the HLA-DRB1, TNF and CTLA4 genes were associated with GD. The carriers of the HLA DRB1*03 allele were more frequent in patients with age at GD diagnosis ≤30 years than in patients with older age at GD diagnosis.

Conclusions

HLADRB1*03 allele is associated with young age at diagnosis of Graves' disease in polish population.

Genotype and phenotype predictors of relapse of graves' disease after antithyroid drug withdrawal

BACKGROUND

For patients with Graves' disease (GD), the primary goal of antithyroid drug therapy is to temporarily restore the patient to the euthyroid state and wait for a subsequent remission of the disease. This study sought to identify the predictive markers for the relapse of disease.

METHODS

To do this, we studied 262 GD patients with long enough follow-up after drug withdrawal to determine treatment outcome. The patients were divided into three groups by time of relapse: early relapse group (n = 91) had an early relapse within 9 months, late relapse group (n = 65) had a relapse between 10 and 36 months, and long-term remission group (n = 106) were either still in remission after at least 3 years or relapsed after 3 years of drug withdrawal. We assessed the treatment outcome of 23 SNPs of costimulatory genes, phenotype and smoking habits. We used permutation to obtain p values for each SNP as an adjustment for multiple testing. Cox proportional hazards models was performed to assess the strength of association between the treatment outcome and clinical and laboratory variables.

RESULTS

FOUR SNPS WERE SIGNIFICANTLY ASSOCIATED WITH DISEASE RELAPSE: rs231775 (OR 1.96, 95% CI 1.18-3.26) at CTLA-4 and rs745307 (OR 7.97, 95% CI 1.01-62.7), rs11569309 (OR 8.09, 95% CI 1.03-63.7), and rs3765457 (OR 2.60, 95% CI 1.08-6.28) at CD40. Combining risk alleles at CTLA-4 and CD40 improved the predictability of relapse. Using 3 years as the cutoff point for multivariate analysis, we found several independent predictors of disease relapse: number of risk alleles (HR 1.30, 95% CI 1.09-1.56), a large goiter size at the end of the treatment (HR 1.30, 95% CI 1.05-1.61), persistent TSH-binding inhibitory Ig (HR 1.64, 95% CI 1.15-2.35), and smoking habit (HR 1.60, 95% CI 1.05-2.42).

CONCLUSION

Genetic polymorphism of costimulatory genes, smoking status, persistent goiter, and TSH-binding inhibitory Ig predict disease relapse.

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.

The replication of the association of the rs6832151 within chromosomal band 4p14 with Graves' disease in a Polish Caucasian population

Recently Chu et al. conducted a genome-wide association study in a Chinese Han population and identified two novel Graves' disease (GD) susceptibility loci within 4p14 (rs6832151) and 6q27 (rs9355610). Our purpose was to replicate these associations in a Polish Caucasian population. We analyzed rs6832151 and rs9355610 genotypes in a case-control study based on 560 GD patients and 1475 unrelated controls using TaqMan assays. Our study had the power of 0.8 and 0.6 to detect the effects originally reported for rs6832151 and rs9355610, respectively. We found an association between GD and the rs6832151 G allele (odds ratio OR = 1.27, P = 0.002). Analysis of model of inheritance suggested that the dominant model should be preferred (P(fit) = 0.938, OR = 1.39, P = 0.001). For rs9355610 a formally significant effect was observed assuming a recessive model (OR = 1.24, P = 0.028), whereas analysis of allele distribution showed a trend for association (OR = 1.14,95%, P = 0.082). Our findings are the first to show that rs6832151 and possibly rs9355610 contribute to GD pathogenesis also in Caucasians.

Genetically driven target tissue overexpression of CD40: a novel mechanism in autoimmune disease

The CD40 gene, an important immune regulatory gene, is also expressed and functional on nonmyeloid-derived cells, many of which are targets for tissue-specific autoimmune diseases, including β cells in type 1 diabetes, intestinal epithelial cells in Crohn's disease, and thyroid follicular cells in Graves' disease (GD). Whether target tissue CD40 expression plays a role in autoimmune disease etiology has yet to be determined. In this study, we show that target tissue overexpression of CD40 plays a key role in the etiology of autoimmunity. Using a murine model of GD, we demonstrated that thyroidal CD40 overexpression augmented the production of thyroid-specific Abs, resulting in more severe experimental autoimmune GD (EAGD), whereas deletion of thyroidal CD40 suppressed disease. Using transcriptome and immune-pathway analyses, we showed that in both EAGD mouse thyroids and human primary thyrocytes, CD40 mediates this effect by activating downstream cytokines and chemokines, most notably IL-6. To translate these findings into therapy, we blocked IL-6 during EAGD induction in the setting of thyroidal CD40 overexpression and showed decreased levels of thyroid stimulating hormone receptor-stimulating Abs and frequency of disease. We conclude that target tissue overexpression of CD40 plays a key role in the etiology of organ-specific autoimmune disease.

CD40 C/T(-1) and CTLA-4 A/G(49) SNPs are associated with autoimmune thyroid diseases in the Chinese population

This study was to investigate whether the common polymorphisms of CD40 and CTLA4 genes confer susceptibility to AITD in the Chinese population. A set of unrelated subjects including 303 GD patients, 208 HT patients, and 215 matched healthy controls were recruited. SNPs were genotyped by the method of PCR-RFLP. (1) As for CD40 C/T(-1) SNP, only a significant difference was found in allele frequencies between GD and control groups (P = 0.033). (2) On the part of CTLA-4 A/G(49) SNP, significant differences were found in genotype and allele frequencies between GD and control groups (P = 7.0 × 10(-5) and P = 0.002, respectively), and similar results were found between HT and control groups (P = 0.015 and P = 0.003, respectively). (3) The logistic regression analysis showed there was no interaction between CD40 and CTLA4 genotypes (P = 0.262). These results indicate that both CTLA-4 A/G(49) and CD40 C/T(-1) SNPs are associated with genetic susceptibility of GD, and CTLA-4 A/G(49) is also associated with HT.

CD40 C/T-1 polymorphism plays different roles in Graves' disease and Hashimoto's thyroiditis: a meta-analysis

CD40 plays a pathogenic role in various autoimmune diseases. However, studies investigating the association between CD40 C/T-1 polymorphism and autoimmune thyroid diseases risk have reported conflicting results and their relative population effect remains unclear; therefore, a meta-analysis was conducted. The data for this meta-analysis included 14 (4214 cases and 3851 controls) and 4 studies (623 cases and 774 controls) for the association of the CD40 C/T-1 polymorphism with Graves' disease (GD) and Hashimoto's thyroiditis (HT), respectively. Results suggested significant association for CD40 C/T-1 polymorphism (odds ratio 1.267 per C allele, p = 0.000) with GD but without HT. The individuals who carried the C/C or C/T genotype have significantly increased GD risk compared with those who carried T/T genotype (C/C vs. T/T: OR = 1.596, 95% CI, 1.256~2.028; C/T vs. T/T: OR = 1.210, 95% CI, 1.032~1.419; dominant model: OR = 1.366, 95% CI, 1.175~1.587; recessive model: OR = 1.322, 95% CI, 1.147~1.523), while no association was observed in HT. When stratified by ethnicity, the significant association between polymorphism and GD risk of Caucasians was found only in recessive models; but that of Asians was found in all models. In the subgroup analysis of study design, we found thyroid antibody status should be ascertained in controls and euthyroidism subjects with higher levels of thyroid antibody should be excluded from control and included into HT to avoid bias. Our meta-analysis showed that CD40 C/T-1 polymorphism plays different roles in GD and HT. Further studies will be needed to confirm our findings.

Influence of CD40 rs1883832 polymorphism in susceptibility to and clinical manifestations of biopsy-proven giant cell arteritis

OBJECTIVE

To assess the potential association between CD40 rs1883832 polymorphism and biopsy-proven giant cell arteritis (GCA). We also studied the influence of the polymorphism on phenotypic expression of this vasculitis, in particular the development of visual ischemic manifestations.

METHODS

Three hundred five Spanish patients with biopsy-proven GCA and 788 matched controls were assessed. DNA from patients and controls was obtained from peripheral blood. Samples were genotyped for the CD40 rs1883832 C/T polymorphism using a predesigned TaqMan allele discrimination assay and by polymerase chain reaction amplification.

RESULTS

Patients with GCA showed a trend toward a higher frequency of the minor allele homozygote of rs1883832 (TT) compared to healthy controls (12.1% vs 8.3%, respectively; p = 0.05, OR 1.54, 95% CI 0.98-2.40). Also, a marginally significant increased frequency of the minor allele T was observed in patients with GCA who had visual ischemic manifestations (36.9%) compared to those without visual ischemic manifestations (27.7%; p = 0.04, OR 1.53, 95% CI 0.99-2.34). In this regard, patients with GCA carrying the minor allele T (either TT or TC) experienced visual ischemic manifestations more commonly than those carrying the CC genotype (58.5% vs 44.2%; p = 0.04, OR 1.78, 95% CI 0.99-3.22).

CONCLUSION

Our results suggest a potential implication of the CD40 rs1883832 C/T polymorphism in susceptibility to visual ischemic manifestations in individuals with biopsy-proven GCA.

CD40: novel association with Crohn's disease and replication in multiple sclerosis susceptibility

BACKGROUND

A functional polymorphism located at -1 from the start codon of the CD40 gene, rs1883832, was previously reported to disrupt a Kozak sequence essential for translation. It has been consistently associated with Graves' disease risk in populations of different ethnicity and genetic proxies of this variant evaluated in genome-wide association studies have shown evidence of an effect in rheumatoid arthritis and multiple sclerosis (MS) susceptibility. However, the protective allele associated with Graves' disease or rheumatoid arthritis has shown a risk role in MS, an effect that we aimed to replicate in the present work. We hypothesized that this functional polymorphism might also show an association with other complex autoimmune condition such as inflammatory bowel disease, given the CD40 overexpression previously observed in Crohn's disease (CD) lesions.

METHODOLOGY

Genotyping of rs1883832C>T was performed in 1564 MS, 1102 CD and 969 ulcerative colitis (UC) Spanish patients and in 2948 ethnically matched controls by TaqMan chemistry.

PRINCIPAL FINDINGS

The observed effect of the minor allele rs1883832T was replicated in our independent Spanish MS cohort [p = 0.025; OR (95% CI) = 1.12 (1.01-1.23)]. The frequency of the minor allele was also significantly higher in CD patients than in controls [p = 0.002; OR (95% CI) = 1.19 (1.06-1.33)]. This increased predisposition was not detected in UC patients [p = 0.5; OR (95% CI) = 1.04 (0.93-1.17)].

CONCLUSION

The impact of CD40 rs1883832 on MS and CD risk points to a common signaling shared by these autoimmune conditions.

Genetic susceptibility to autoimmune thyroid disease: past, present, and future

BACKGROUND

Autoimmune thyroid diseases (AITD), including Graves' disease and Hashimoto's thyroiditis, arise due to complex interactions between environmental and genetic factors. There are sound data coming from epidemiological, family, and twin studies demonstrating a strong genetic influence on the development of AITD. In this review we summarize the new findings on the genetic susceptibility to AITD focusing on emerging mechanisms of susceptibility.

SUMMARY

Candidate gene analysis, whole-genome linkage screening, genome-wide association studies, and whole-genome sequencing are the major technologies that have advanced this field, leading to the identification of at least seven genes whose variants have been associated with AITD. One of the major ones is the HLA-DR gene locus. Recently, it was shown that substitution of the neutral amino acids Ala or Gln with arginine at position beta 74 in the HLA-DR peptide-binding pocket is key to the etiology of both Graves' disease and Hashimoto's thyroiditis. Several other genes have also been shown to confer susceptibility to AITD. These can be classified into two groups: (i) immune regulatory genes (cytotoxic T lymphocyte-associated protein 4, CD40, protein tyrosine phosphatase-22, and CD25) and (ii) thyroid-specific genes (thyroglobulin and thyrotropin receptor genes). The influence of individual genes on the development of AITD when assessed in a population appears to be weaker than would be expected from the data showing strong genetic susceptibility to AITD. Two possible mechanisms explaining this discrepancy are gene-gene interactions and subset effects.

CONCLUSIONS

Significant progress has been made in our understanding of the immunogenetic mechanisms leading to thyroid autoimmunity. For the first time we are beginning to unravel these mechanisms at the molecular level. It is hoped that these new data will be translated into novel therapies and prevention strategies in AITD, such as costimulatory blockade.

CD40 and autoimmunity: the dark side of a great activator

CD40 is a tumor necrosis factor receptor superfamily member expressed by immune and non-immune cells. CD40:CD154 interactions mediate T-dependent B cell responses and efficient T cell priming. Thus, CD40 is a likely candidate to play roles in autoimmune diseases in which activated T and B cells cause pathology. Diseases in which CD40 plays a pathogenic role include autoimmune thyroiditis, type 1 diabetes, inflammatory bowel disease, psoriasis, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus. This review discusses the role of CD40:CD154 interaction in human and mouse autoimmunity, human polymorphisms associated with disease incidence, and disrupting CD40:CD154 interactions as an autoimmune therapy.

The etiology of autoimmune thyroid disease: a story of genes and environment

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto's thyroiditis (HT) are prevalent autoimmune diseases, affecting up to 5% of the general population. Autoimmune thyroid diseases arise due to complex interactions between environmental and genetic factors. Significant progress has been made in our understanding of the genetic and environmental triggers contributing to AITD. However, the interactions between genes and environment are yet to be defined. Among the major AITD susceptibility genes that have been identified and characterized is the HLA-DR gene locus, as well as non-MHC genes including the CTLA-4, CD40, PTPN22, thyroglobulin, and TSH receptor genes. The major environmental triggers of AITD include iodine, medications, infection, smoking, and possibly stress. Recent data on the genetic predisposition to AITD lead to novel putative mechanisms by which the genetic-environmental interactions may lead to the development of thyroid autoimmunity.

Association of CD40 -1C/T polymorphism in the 5'-untranslated region and chronic obstructive pulmonary disease

BACKGROUND

Chronic inflammation of the airways and lung parenchyma plays a major role in the pathogenesis of chronic obstructive pulmonary disease (COPD). It is influenced by both environmental and genetic factors. CD40 signaling has been linked to pathogenic processes of chronic inflammatory diseases. After interaction with its ligand CD154 (CD40L), CD40 induces a broad variety of chronic inflammatory responses, inducing the release of inflammatory mediators. We investigated whether a CD40 gene (-1C/T) single nucleotide polymorphism (SNP) is associated with COPD in a Chinese population.

METHODS

We analyzed -1C/T SNP of the CD40 gene in 234 patients with COPD, and also in 312 controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing methods.

RESULTS

The frequency of CT and CT+CC of CD40 gene was significantly different from TT in the COPD group compared with the control group (for CT: OR=1.777, 95% CI: 1.117-2.826, p=0.015; for CT+CC: OR=1.614, 95% CI: 1.032-2.526, p=0.035). However, neither the allele frequency of CD40 nor the smoking and clinical stages in CD40 -1C/T genotypes frequency had significant differences between the COPD patients and control.

CONCLUSION

These findings suggest that the CD40 -1C/T polymorphism may contribute to the susceptibility to COPD in a Chinese population.

Autoimmunity risk alleles in costimulation pathways

SUMMARY

The basis for susceptibility to common autoimmune diseases is a complex interplay between multiple genetic and environmental risk factors. We have now entered a new generation of genetic study designs which has not only furthered our understanding of the individual mechanisms involved in the common human autoimmune diseases but also has pointed towards common pathways. In this review we focus on costimulatory mechanisms with the most convincing association results in large collections of patients and control subjects. These include the genes encoding cytotoxic T-lymphocyte antigen-4, CD58, CD40, inducible T-cell costimulator ligand, CD244, CD226, tumor necrosis factor (TNF) (ligand) superfamily member 4, TNF superfamily member 15, and programmed cell death 1. The unbiased genome-wide association scans suggest that indeed immune related genes underlie the pathogenesis of human autoimmune disease with common involvement of costimulatory pathways. The identification of allelic variants associated with disease risk followed by understanding their functional outcomes and affected pathways provides a rationale approach for drug design.

Recent advances in the genetics of autoimmune disease

Extraordinary technical advances in the field of human genetics over the past few years have catalyzed an explosion of new information about the genetics of human autoimmunity. In particular, the ability to scan the entire genome for common polymorphisms that associate with disease has led to the identification of numerous new risk genes involved in autoimmune phenotypes. Several themes are emerging. Autoimmune disorders have a complex genetic basis; multiple genes contribute to disease risk, each with generally modest effects independently. In addition, it is now clear that common genes underlie multiple autoimmune disorders. There is also heterogeneity among subphenotypes within a disease and across major racial groups. The current crop of genetic associations are only the start of a complete catalog of genetic factors for autoimmunity, and it remains unclear to what extent common variation versus multiple rare variants contribute to disease susceptibility. The current review focuses on recent discoveries within functionally related groups of genes that provide clues to novel pathways of pathogenesis for human autoimmunity.

STAT2*C related genotypes and allele but not TLR4 and CD40 gene polymorphisms are associated with higher susceptibility for asthma

Objective: Asthma is caused by a complex interaction between multiple genes and environmental factors. Herein we aimed to investigate whether signal transducer and activator of transcription (STAT2), toll-like receptors 4 (TLRs4) and CD40-related polymorphisms are associated with asthma susceptibility.

Design: Children were divided: (1) asthma (n=117); (2) normal controls (n=60). The polymorphisms of STAT2, TLR4 and CD40 polymorphism were analyzed by PCR-RFLP genotyping. Genotypes, allelic frequencies and association of haplotypes in both groups were compared.

Results: STAT2*C related genotypes, but not TLR4 and CD40 polymorphism, are associated with higher susceptibility for asthma. Distributions of STAT2*CC/CG/GG and C/G allele in both groups are: (1) 0/11.1/88.9 % and 5.6/94.4%; (2) 0/1.7/98.3% and 0.8/99.2% (p<0.05). Proportions of TLR4*rs10983755 AA/AG/GG and rs1927914 CC/CT/TT homozygote are: (1) 35.1/8.5/56.4% and 9.4/56.4/34.2%; (2) 35/8.3/56.7% and 16.7/48.3/35% (non-difference). Proportions of CD40*rs1883832 CC/CT/TT, rs3765459 AA/AG/GG, and rs4810485 TT/GT/GG are: (1) 29.9/53/17.1%, 6.8/47.9/45.3 and 18.8/62.4/18.8%; (2) 36.7/41.7/21.6%, 1.6/46.7/ 51.7 and 15/51.7/33.3% (non-difference). Haplotype analyses for TLR4 and CD40 genes revealed their non-association and non-additional effect upon asthma susceptibilities.

Conclusion: STAT2*C related genotypes and alleles are associated with asthma susceptibilities and pathogenesis. There were non-association and non-additional effects of TLR4/CD40 gene polymorphisms and haplotypes upon asthma risk.

Association and linkage studies of the 20q11.2 region (GRD-2 locus) with Graves' disease in the Tunisian population

OBJECTIVE

A genome-wide screen has shown linkage to the GRD-2 locus in Graves' disease (GD). Furthermore, a positional candidate gene maps to this locus; the CD40 gene has been reported to be associated and may predispose to the disease. The aim of this study was to replicate/reject the GRD-2 and to determine if the single nucleotide polymorphism (SNP) of the CD40 (CD40 C/T-1) confers susceptibility to GD.

METHODS

The present study examined a dataset of 11 families with GD using 10 microsatellite markers and a case-control study consisting of 76 sporadic GD patients and 66 healthy subjects to determine the implication of the GRD-2. Both non-parametric linkage and association tests were performed. Genotyping of the CD40 C/T-1 was carried out using a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The intrafamilial association and the case-control study showed no association between CD40 C/T-1 and GD. In addition, a high percentage of the C allele (96.9%) of CD40 SNP among control data was observed. The linkage analyses showed that the highest non-parametric LOD score was 1.67 at the D20S119 marker and the maximum attainable LOD score was 1.66. This result provides interesting evidence for linkage between GRD-2 and GD.

CONCLUSION

The CD40 gene seems to be not associated with GD in the Tunisian population, whereas the GRD-2 locus could harbour other candidate gene(s) to the genetic susceptibility of GD.

The genetic basis of thyroid autoimmunity

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto's thyroiditis (HT), are prevalent autoimmune diseases, affecting up to 5% of the general population. AITDs arise due to interplay between environmental and genetic factors. In the past decade, significant progress has been made in our understanding of the genetic contribution to the etiology of AITDs. Excitingly, several AITD susceptibility genes have been identified and characterized. Some of these susceptibility genes are specific to either GD or HT, while others confer susceptibility to both conditions. The first AITD susceptibility gene locus identified was the Human-Leukocyte-Antigen DR (HLA-DR) gene locus. Subsequently, a quintet of non-HLA genes, including the cytotoxic T lymphocyte antigen (CTLA-4), CD40, protein tyrosine phosphatase-22 (PTPN22), thyroglobulin, and thyroid-stimulating hormone receptor (TSHR) gene, has been shown to contribute to the susceptibility to AITDs. Recently, the mechanisms by which these new AITD genes predispose to AITDs have been dissected. In this review, we overview and highlight the recent data on the genes predisposing to AITDs and the putative mechanisms by which they confer susceptibility to disease.

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.

The CD40, CTLA-4, thyroglobulin, TSH receptor, and PTPN22 gene quintet and its contribution to thyroid autoimmunity: back to the future

Autoimmune thyroid diseases (AITD) are common autoimmune diseases, affecting up to 5% of the general population. Thyroid-directed autoimmunity is manifested in two classical autoimmune conditions, Hashimoto's thyroiditis, resulting in hypothyroidism and Graves' disease resulting in hyperthyroidism. Autoimmune thyroid diseases arise due to an interplay between environmental and genetic factors. In the past decade significant progress has been made in our understanding of the genetic contribution to the etiology of AITD. Indeed, several AITD susceptibility genes have been identified. Some of these susceptibility genes are specific to either Graves' disease or Hashimoto's thyroiditis, while others confer susceptibility to both conditions. Both immunoregulatory genes and thyroid specific genes contribute to the pathogenesis of AITD. The time is now ripe to examine the mechanistic basis for the contribution of genetic factors to the etiology of AITD. In this review, we will focus on the contribution of non-MHC II genes.

A CD40 Kozak sequence polymorphism and susceptibility to antibody-mediated autoimmune conditions: the role of CD40 tissue-specific expression

Previously, we and others have demonstrated the association of a C/T single nucleotide polymorphism (SNP), in the Kozak sequence of CD40, with Graves' disease (GD). Here, using an expanded data set of patients, we confirm the association of the CD40 SNP with GD (n=210, P=0.002, odds ratio (OR)=1.8). Subset analysis of patients with persistently elevated thyroid peroxidase (TPO) and/or thyroglobulin (Tg) antibodies (Abs), (TPO/Tg Abs), after treatment (n=126), revealed a significantly stronger association of the SNP with disease (P=5.2 x 10(-5), OR=2.5) than in GD patients who were thyroid antibody-negative. However, the CD40 SNP was not associated with TPO/Tg Abs in healthy individuals. Next, we tested the CD40 SNP for association with Myasthenia Gravis (MG), which, like GD is an antibody-mediated autoimmune condition. Analysis of 81 MG patients found no association of the SNP with disease. Functional studies revealed significant expression of CD40 mRNA and protein in the thyroid (target tissue in GD) but not in skeletal muscle (target tissue in MG). Combined, our genetic and tissue expression data suggest that the CD40 Kozak SNP is specific for thyroid antibody production involved in the etiology of GD. Increased thyroidal expression of CD40 driven by the SNP may contribute to this disease specificity.

Analysis of the C/T(-1) single nucleotide polymorphism in the CD40 gene in multiple sclerosis

The costimulatory CD40-CD40L pathway plays a critical role in the generation and maintenance of adaptive immune responses. Genetic interference of CD40-CD40L interactions strongly influences the onset and course in many autoimmune disease models including experimental autoimmune encephalomyelitis. We analysed the association of a single nucleotide polymorphism of the CD40 gene (C/T(-1)) in 287 patients with multiple sclerosis (MS) and 184 matched controls. No significant differences were found in the frequency of the C/T(-1) polymorphism between the patients with MS and the controls (53% vs 49%) or among different MS subtypes. Cell surface expression of CD40 did not differ within the different genotypes, but carriers of the T allele showed a trend for a lower stimulatory index compared with individuals with the CC genotype. Although these subtle differences indicate functional consequences in the immune stimulatory capabilities related to the CD40 C/T(-1) polymorphism, our population-based study found no association with disease susceptibility or disease course in MS.

Interaction of HLA-DRB1 alleles with CTLA-4 in the predisposition to Graves' disease: the impact of DRB1*07

OBJECTIVE

To study interactions between the two most widely confirmed Graves' disease (GD) loci: HLA-DRB1 and CTLA-4. HLA-DRB1*03 (risk allele) and DRB1*07 (protective allele) were analyzed in this aspect, the linked TNF G(-308)A polymorphism was also considered.

DESIGN

A case-control study of 429 patients with GD compared to 308 healthy subjects. The impact of genes and their interactions were analyzed by stepwise logistic regression.

RESULTS

The independent effects of DRB1*03 and DRB1*07 were confirmed in our study both by stratification studies and logistic regression. CTLA-4 did not appear to be associated with GD when the interactions with other genes were considered. By logistic regression we observed a significant interaction between DRB1*07 and CTLA-4 and revealed that CTLA-4 49G attenuated the DRB1*07-related protection, the effect noticed also in three-way stratification studies. We confirmed that the TNF G(-308)A polymorphism is only a marker of the DRB1 status.

CONCLUSION

Our results stress the importance of complex gene interactions in the multigene predisposition to GD. The interactions between two predisposing loci, DRB1 and CTLA-4, are exerted rather by DRB1*07 than DRB1*03 allele: CTLA-4 acts via switching off the protective DRB1*07 influence, whereas the effect of DRB1*03 is independent.