Cyclooxygenase-dependent thyroid cell proliferation induced by immunoglobulins from patients with Graves' disease

Association between IL-21 gene rs907715 polymorphisms and Graves' disease in a Southern Chinese population

Interleukin-21 (IL-21) is a pleiotropic cytokine linking innate and adaptive immune responses, which has been reported to play a key role in multiple autoimmune diseases. The aim of the present case-control study was to investigate the genetic association between single nucleotide polymorphisms (SNPs) of rs907715 within the IL-21 gene and Graves’ disease (GD) in a Southern Chinese population. A total of 211 patients with GD and 212 control subjects were recruited for the study. IL-21 gene rs907715 polymorphisms were detected by direct DNA sequencing. The results indicated that the frequencies of the GG genotype and the G allele in GD patients were significantly increased when compared with the frequencies in the controls (P=6.7×10⁻³ and P=2.0×10⁻⁵, respectively). In addition, the frequency of the AA genotype was much lower in the patient group when compared with the control group (16.6 vs. 34.0%; P=4.0×10⁻⁵). Furthermore, the G allele of rs907715 was associated with relapse in GD patients. These observations indicated that polymorphisms of IL-21/rs907715 may affect the susceptibility to GD in a Southern Chinese population. The G allele was significantly associated with an increased risk of GD development, whereas the A allele may lower the susceptibility to GD.

Association between vitamin-D receptor gene FokI polymorphism and Graves' disease among Taiwanese Chinese

1,25(OH)(2)D(3), exerting its biological effects through the vitamin-D receptor (VDR), plays a role in the modulation of the human immune system. The aim of this study was to test for the presence of an association between VDR gene polymorphism and the susceptibility to Graves' disease (GD) for Taiwanese Chinese. Using a polymerase chain reaction (PCR)-based restriction analysis, we screened the VDR exon 2 start codon T/C (VDR-FokI) polymorphism to determine the genotypes for 88 GD patients and 90 normal controls. From the genotype analysis, GD patients featured a greater proportion of the CC genotype (44.3%) and a smaller proportion of the TT genotype (12.5%) than was the case for normal controls (CC: 23.3% and TT: 28.9%; chi-squared test, P=0.003). The odds ratios (ORs) for the risk of the CC genotype's appearance compared with the corresponding values for the TT and TC genotypes, for the GD patient group, were, 4.39 (95% confidence interval [CI]: 1.82-10.61) and 2.10 (95% CI: 1.06-4.18), respectively. With respect to the allelic analysis, we observed significantly increased C-allele (65.9%) and decreased T-allele (34.1%) frequencies among GD patients compared to normal controls (C: 47.2% and T: 52.8%; chi-squared test, P=0.002). The OR for the risk of appearance of the C allele in the GD-patient group was 1.93 (95% CI: 1.27-2.95). In conclusion, the VDR-FokI T/C polymorphism might be able to be used as a genetic marker to predict the likelihood of GD development.

Interleukin-1-beta gene, but not the interleukin-1 receptor antagonist gene, is associated with Graves' disease

Interleukin-1 (IL-1) is considered to be involved in the pathogenesis of Graves' disease. The aim of this study was to test whether the IL-1-beta gene promoter region and exon 5 and IL-1 receptor antagonist (IL-1Ra) gene intron 2 polymorphisms could be useful genetic markers for susceptibility to Graves' disease. A normal control group of 163 healthy people and another group of 95 patients with Graves' disease were examined. Polymerase chain reaction (PCR) was used to analyze the variable number of tandem repeats (VNTRs) at intron 2 of the IL-1Ra gene for the polymorphism. PCR-based restriction analysis was done for the IL-1-beta gene polymorphisms of the promoter region and exon 5 using endonucleases AvaI and TaqI, respectively. We found significantly increased frequencies of the C/C homozygous genotype (chi(2) test, P=0.038; odds ratio (OR)=2.558, 95% confidence interval (CI)=1.205-5.430) and the C allele (chi(2) test, P=0.011; OR=1.589, 95% CI=1.094-2.309) in the IL-1-beta gene promoter (-511 C/T polymorphism) in Graves' disease patients compared to normal controls. There were no significant differences in polymorphisms of IL-1-beta gene exon 5 and IL-1Ra gene intron 2 between the patient and normal control groups. A subgroup analysis also demonstrated no association between the severity of the disease and any polymorphism of IL-1-related genes. We suggest that the IL-1-beta gene promoter polymorphism can be used as a genetic marker for susceptibility to Graves' disease. It is worthwhile to study the cytokine genes further because of the association between cytokines and Graves' disease.

Expression of cyclooxygenase-2 and thromboxane synthase in non-neoplastic and neoplastic thyroid lesions

Cyclooxygenase-2 (COX-2) and thromboxane synthase (TBXAS) are important enzymes involved in the arachidonic acid pathway and synthesis of prostaglandins. We examined COX-2 and TBXAS immunoreactivity in 150 surgically resected thyroid specimens using immunohistochemistry to determine expression in benign and malignant thyroid lesions and to examine their roles in thyroid tumor progression. Papillary thyroid carcinomas and follicular carcinomas expressed higher levels of COX-2 compared to follicular adenomas and adenomatous nodules. We showed for the first time that TBXAS was expressed in thyroid tissues, with higher levels in papillary carcinomas compared to non-neoplastic and benign thyroid tissues. Western blot was performed on seven thyroid samples. These results indicate that both COX-2 and TBXAS are expressed in benign and malignant thyroid tissues. Although some malignant thyroid tumors showed higher levels of COX-2 expression, COX-2 and TBXAS are probably not useful in the immunohistochemical diagnosis of thyroid malignancies. However, the expression of both COX-2 and TBXAS by thyroid tissue may provide insight into the role of these enzymes in progression from benign to malignant thyroid tumors.