Association of G-174C Polymorphism of the Interleukin-6 Gene Promoter with Graves' Ophthalmopathy

The role of IL-6-174 G/C polymorphism and intraocular IL-6 levels in the pathogenesis of ocular diseases: a systematic review and meta-analysis

Interleukin-6 (IL-6) is one of the key regulators behind the inflammatory and pathological process associated with ophthalmic diseases. The role of IL-6-174 G/C polymorphism as well as intraocular IL-6 levels among various eye disease patients differ across studies and has not been systematically reviewed. Thus, this study aims to provide a summary to understand the relationship between IL-6 and ophthalmic disease. In total, 8,252 and 11,014 subjects for IL-6-174 G/C and intraocular levels of IL-6, respectively, were retrieved from PubMed, Scopus and Web of Science. No association was found between IL-6-174 G/C polymorphisms with ocular diseases. Subgroup analyses revealed a suggestive association between the GC genotype of IL-6-174 G/C with proliferative diabetic retinopathy (PDR). Further, the level of intraocular IL-6 among ocular disease patients in general was found to be higher than the control group [standardized mean difference (SMD) = 1.41, 95% confidence interval (CI) 1.24-1.58, P < 0.00001]. Closer examination through subgroup analyses yielded similar results in several ocular diseases. This study thus indicates that the IL-6-174 G/C polymorphism does not predispose patients to ocular disease, although the GC genotype is likely to be a genetic biomarker for PDR. Moreover, intraocular IL-6 concentrations are related to the specific manifestations of the ophthalmic diseases. Further studies with larger sample sizes are warranted to confirm this conclusion.

Differential profiling of lacrimal cytokines in patients suffering from thyroid-associated orbitopathy

The aim was to investigate the levels of cytokines and soluble IL-6R in the tears of patients with thyroid-associated orbitopathy (TAO) disease. Schirmer’s test was adopted to collect tears from TAO patients (N = 20, 17 women, mean age (±SD): 46.0 years (±13.4)) and healthy subjects (N = 18, 10 women, 45.4 years (±18.7)). Lacrimal cytokines and soluble IL-6R (sIL-6R) were measured using a 10-plex panel (Meso Scale Discovery Company) and Invitrogen Human sIL-6R Elisa kit, respectively. Tear levels of IL-10, IL-12p70, IL-13, IL-6 and TNF-α appeared significantly higher in TAO patients than in healthy subjects. Interestingly, IL-10, IL-12p70 and IL-8 levels increased in tears whatever the form of TAO whereas IL-13, IL-6 and TNF-α levels were significantly elevated in inflammatory TAO patients, meaning with a clinical score activity (CAS) ≥ 3, compared to controls. Furthermore, only 3 cytokines were strongly positively correlated with CAS (IL-13 Spearman coeff. r: 0.703, p = 0.0005; IL-6 r: 0.553, p = 0.011; IL-8 r: 0.618, p = 0.004, respectively). Finally, tobacco use disturbed the levels of several cytokines, especially in patient suffering of TAO. The differential profile of lacrimal cytokines could be useful for the diagnosis of TAO patients. Nevertheless, the tobacco use of these patients should be taken into account in the interpretation of the cytokine levels.

Association between polymorphism within interleukin related genes and Graves' disease: a meta-analysis of 22 case-control studies

Graves' disease (GD) is a common autoimmune disorder with a genetic predisposition. There is strong evidence to suggest that both Th1 and Th2 circulating cytokines are involved in the development of GD. In this study, we conducted a meta-analysis to assess the impact of seven variations of five IL-related genes on the susceptibility to GD. A total of 22 case-control studies involving 5338 GD patients and 6446 healthy controls were included. The results showed that only one SNP rs1800795 in IL-6 was significantly associated with GD in homozygous model (CC vs. GG: OR = 2.714, 95% CI = 1.047-7.039, p = 0.04), heterozygous model (CG vs. GG: OR = 1.295, 95% CI = 1.013-1.655, p = 0.039), dominant model (CC+CG vs. GG: OR = 1.418, 95% CI = 1.122-1.793, p = 0.003) and additive model (C vs. G: OR = 1.432, 95% CI = 1.087-1.886, p = 0.011).To explain the heterogeneity, we performed the subgroup analysis by ethnicity. The ethnicity stratification revealed that the association between rs1800795 and GD tended to be much stronger for Asian than European population in homozygous, dominant, recessive, and additive models. The remaining 6 SNPs in 4 genes did not show any significant association with GD in any genetic models. Together, our data support that rs1800795 within the IL-6 gene confers genetic susceptibility for GD. Future large-scale studies are required to validate the associations between IL-6 and others IL-related genes and GD.

Genetic Associations of Interleukin-related Genes with Graves' Ophthalmopathy: a Systematic Review and Meta-analysis

Graves’ ophthalmopathy (GO) is the commonest extra-thyroidal manifestation of Graves’ disease (GD). Associations between interleukin-related (IL) gene polymorphisms and GO have been reported in different populations. We aim to confirm such associations by conducting a meta-analysis. Totally 382 publications were retrieved in MEDLINE and EMBASE up to 25/2/2015. After removing the duplicates and assessing the studies, we retrieved 16 studies that met the selection criteria for meta-analysis, involving 12 polymorphisms in 8 IL-related genes, and 1650 GO cases and 2909 GD controls. The summary odds ratio (OR) and 95% confidence intervals (CI) were estimated. We found one polymorphism in IL1A (rs1800587, c.-889C>T) showing a suggestive association with GO in the meta-analysis (allelic model [T vs. C]: OR = 1.62, 95% CI: 1.00–2.62, P = 0.050, I² = 53.7%; recessive model [TT vs. TC + CC]: OR = 2.39, 95% CI: 1.07–5.37, P = 0.039, I² = 23.6%; heterozygous model [TC vs. CC]: OR = 1.52, 95% CI: 1.04–2.22, P = 0.034, I² = 37.0%). No association with GO was detected for the other 7 genes (IL1B, IL1RA, IL4, IL6, IL12B, IL13 and IL23R). Our results thus indicate that IL1A is likely to be a genetic biomarker for GO. Further studies with larger sample sizes are warranted to confirm the associations of IL1A and other IL-related genes with GO.

Genetic variations in the SOCS3 gene in patients with Graves' ophthalmopathy

AIMS

To explore the role of the suppressor of cytokine signalling 3 (SOCS3) gene in Graves' ophthalmopathy (GO) patients.

METHODS

A case-control study was conducted in a Chinese Han population by recruiting 114 Graves' disease (GD) patients with GO and 156 GD patients without GO. We determined SOCS3 mRNA and protein levels in Epstein-Barr virus-transformed lymphoblastoid cell lines (EBV-LCLs) from peripheral blood mononuclear cells (PBMCs) by quantitative real-time (QRT)-PCR analysis and western blot analysis. We also genotyped five single nucleotide polymorphisms (SNPs) in the SOCS3 locus (SOCS3 rs12952093, rs4969170, rs4969168, rs4969169 and rs2280148) in all 270 GD patients using ligase detection reaction and multiplex PCR analyses. QRT-PCR and western blot assays were then performed to compare SOCS3 mRNA and protein levels between the rs4969170 AA and GG genotype groups from 20 GO patients.

RESULTS

Basal SOCS3 mRNA and protein expression levels were significantly increased in patients with GO (p<0.05). The SOCS3 rs4969170 AA genotype was strongly associated with GO (OR=3.5, 95% CI 1.6 to 7.5, p=0.001). The AA genotype carriers had significantly higher SOCS3 mRNA and protein levels than those with the GG genotype (p<0.05).

CONCLUSIONS

Patients with GD who carry the AA genotype of the rs4969170 SNP in SOCS3 are more susceptible to the development of GO.

Polymorphisms in the TNFA and IL6 genes represent risk factors for autoimmune thyroid disease

BACKGROUND

Autoimmune thyroid disease (AITD) comprises diseases including Hashimoto's thyroiditis and Graves' disease, both characterized by reactivity to autoantigens causing, respectively, inflammatory destruction and autoimmune stimulation of the thyroid-stimulating hormone receptor. AITD is the most common thyroid disease and the leading form of autoimmune disease in women. Cytokines are key regulators of the immune and inflammatory responses; therefore, genetic variants at cytokine-encoding genes are potential risk factors for AITD.

METHODS

Polymorphisms in the IL6-174 G/C (rs1800795), TNFA-308 G/A (rs1800629), IL1B-511 C/T (rs16944), and IFNGR1-56 T/C (rs2234711) genes were assessed in a case-control study comprising 420 Hashimoto's thyroiditis patients, 111 Graves' disease patients and 735 unrelated controls from Portugal. Genetic variants were discriminated by real-time PCR using TaqMan SNP genotyping assays.

RESULTS

A significant association was found between the allele A in TNFA-308 G/A and Hashimoto's thyroiditis, both in the dominant (OR = 1.82, CI = 1.37-2.43, p-value = 4.4×10(-5)) and log-additive (OR = 1.64, CI = 1.28-2.10, p-value = 8.2×10(-5)) models. The allele C in IL6-174 G/C is also associated with Hashimoto's thyroiditis, however, only retained significance after multiple testing correction in the log-additive model (OR = 1.28, CI = 1.06-1.54, p-value = 8.9×10(-3)). The group with Graves' disease also registered a higher frequency of the allele A in TNFA-308 G/A compared with controls both in the dominant (OR = 1.85, CI = 1.19-2.87, p-value = 7.0×10(-3)) and log-additive (OR = 1.69, CI = 1.17-2.44, p-value = 6.6×10(-3)) models. The risk for Hashimoto's thyroiditis and Graves' disease increases with the number of risk alleles (OR for two risk alleles is, respectively, 2.27 and 2.59).

CONCLUSIONS

This study reports significant associations of genetic variants in TNFA and IL6 with the risk for AITD, highlighting the relevance of polymorphisms in inflammation-related genes in the etiopathogenesis of AITD.

Disease association of the CD103 polymorphisms in Taiwan Chinese Graves' ophthalmopathy patients

OBJECTIVE

To evaluate whether variations in the CD103 gene could be associated with Graves' ophthalmopathy (GO) in patients with Graves' disease.

DESIGN

Case-control study.

PARTICIPANTS

A total of 484 Chinese patients with Graves' disease in Taiwan, including 203 patients with GO and 281 patients without GO, were enrolled.

METHODS

Five single nucleotide polymorphisms (SNPs) in CD103 were genotyped using an assay-on-demand allelic discrimination assay and detection system according to the manufacturer's instructions.

MAIN OUTCOME MEASURES

Association of SNPs in CD103 with the development of GO.

RESULTS

The CD103 SNP rs11652878 was associated with GO, which may decrease the risk of GO by 1.57-fold (P = 0.029). The Ht5-GCGCG haplotype, composed of 5 SNPs in the CD103 gene (rs1716, rs3744679, rs11652878, rs16953477, and rs9905739), were protective haplotypes (P = 0.010). Moreover, the heterozygous genotype (Ht5/non-Ht5) was correlated with a reduced risk of GO and high grades of goiter as compared with the non-Ht5/non-Ht5 genotype (P = 0.006 and P = 0.048, respectively). Logistic analysis confirmed the contribution of CD103 rs11652878 to the protection of GO.

CONCLUSIONS

These data suggest that patients with Graves' disease in the presence of the G allele of SNP rs11652878, especially Ht5-GCGCG, in CD103 are less susceptible toward the development of GO.

Graves' disease and gene polymorphism of TNF-α, IL-2, IL-6, IL-12, and IFN-γ

The role of genetic factors in the pathogenesis of Graves' disease (GD) is not clear. The purpose of this study was to investigate the association between single nucleotide polymorphisms in pro-inflammatory cytokine genes and GD in Iranian patients. A case-control hospital-based study was carried out on 107 GD patients and 140 healthy controls. Cytokine typing was performed by polymerase chain reaction with sequence-specific primers (PCR-SSP) assay. The allele and genotype frequencies of the following cytokine genes were determined: TNF-α (-308A/G, -238A/G), IL-2 (-330T/G, +166G/T), IL-6 (-174C/G, A/G nt565), IL-12 (-1188A/C), and IFN-γ (UTR 5644A/T). The following alleles and genotypes were significantly overrepresented in patients: TNF-α -308A allele (P < 0.01) and AA genotype (P < 0.05), IL-2 -330G allele (P < 0.01) and GG genotype (P < 0.01), IL-6 -174C allele (P < 0.01) and CC genotype (P < 0.01), IL-12 -1188C allele (P < 0.01) and CC genotype (P < 0.01), IFN-γ UTR5644T allele (P < 0.01) and TT genotype (P < 0.01). In conclusion, this is the first study to show a significant association between GD and IL-2 -330G, IL-12 -1188C, and IFN-γ UTR 5644T alleles. Our results support the hypothesis that polymorphism in pro-inflammatory cytokines might be involved in predisposition to GD.

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.