Association of cytokine Th2 gene polymorphisms with autoimmune thyroid diseases in Tunisian population.

Autoimmune thyroid diseases (AITD) including Graves' disease (GD) and Hashimoto's thyroiditis (HT) are complex genetic diseases. Th2 cytokines act on the development of AITD. This study was conducted on Tunisian patients with AITD to investigate the association of Th2 cytokine gene polymorphisms and haplotype combination with GD or HT risk. A total of 156 controls, 160 patients with HT and 88 patients with GD were genotyped for IL-4 rs2243250, IL-5 rs2069812, IL-6 rs1800796 and IL-13 rs1800925 polymorphisms by PCR-RFLP. The AITD risk was assessed by a logistic regression analysis using the SNP stats statistical program. False-positive report probability (FPRP) was estimated to evaluate significant findings. IL-13 rs1800925 was associated with GD, after adjustment for age and gender, in codominant, dominant and allele genetic models (p = .0072; p = .0018; p = .012, respectively). Significant association of the IL-6 rs1800796C/G genotype with GD was also detected (p = .025). Furthermore, increased risk of HT was still found for IL-13 rs1800925T allele (p = .039, OR = 1.39) and for IL-4 rs2243250T/T genotype both in codominant (p = .033, OR = 2.59) and recessive (p = .011, OR = 2.73) models after adjustment for age and gender. Interestingly, haplotype analysis performed on the IL-4, IL-5 and IL-13 genes revealed a high risk of HT with CTT haplotype (p = .008, OR = 2.12). However, the CCT haplotype is a protective factor (OR = 0.36). Patients carrying the CT haplotype with only one minor allele had a moderate risk of HT (OR = 1.56). The FPRP analysis showed that the association of IL-13 rs1800925 polymorphism with GD and HT and the association of CTT haplotype with HT were noteworthy. In conclusion, the IL-4, IL-5, IL-6 and IL-13 polymorphism may play a role in susceptibility to GD and HT in the Tunisian population. Furthermore, gene-gene interaction between the IL-4, IL-5 and IL-13 significantly increases the risk of AITD. Further studies with larger numbers of individuals are needed to confirm the results.

Pro- and anti-angiogenic VEGF mRNAs in autoimmune thyroid diseases.

The aim of this study was to assess the relationships between five different splice isoforms of VEGF mRNA and its plasma levels in individuals treated for autoimmune thyroid diseases (AITD); mainly Graves' disease (GD) and Hashimoto's thyroiditis (HT). In a population from Tunisia, levels of thyroid hormones and antibodies were quantified simultaneously with plasma VEGF and VEGF mRNA isoforms after a period of 6 months of patients' treatment. Plasma VEGF was measured in 110 AITD patients (21 GD and 89 HT patients). VEGF isoforms (VEGF121, VEGF165, VEGF145 and VEGF189 pro-angiogenic isoforms and VEGF165b anti-angiogenic isoform) in peripheral blood mononuclear cells were quantified in 71 patients (20 GD and 51 HT patients) and 86 healthy controls. Decreased levels of VEGF189 mRNA were observed in AITD compared to controls. VEGF165 was increased in GD patients compared to controls and the VEGF165b was increased in HT patients compared to GD. We observed increased levels of VEGF165b in hypothyroid AITD patients after treatment. We have also shown that the VEGF145 isoform levels were determined by FT4 in all patients and by the thyroid status after 6 months of treatment only in HT patients. An association was observed for VEGF165 mRNA levels with anti-TPO antibodies in all patients. Finally, FT4 was associated with VEGF plasma levels but only in healthy controls. In conclusion, this descriptive study highlights the specificity of VEGF mRNA isoforms in AITD, a fact underlining the need for novel clinical trials and the development of personalised theranostic approaches.

Association of Interleukin-1B and Interleukin-4 Gene Variants with Autoimmune Thyroid Diseases in Tunisian Population.

Autoimmune thyroid diseases (AITD) including Graves' disease (GD) and Hashimoto's thyroiditis (HT) are complex genetic diseases. Cytokines IL-1B and IL-4 play a role in the pathogenesis of AITD. This study was conducted on Tunisian patients with GD or HT to investigate the association of IL-1B and IL-4 gene polymorphisms with the risk and the prognosis of AITD. A total of 358 healthy controls and 341 patients with AITDs (249 HT and 92 GD) were genotyped for IL-1B+3953C/T and IL-4 intron 3 VNTR polymorphisms. A significant association was found between IL-1B+3953C/T polymorphism and GD or HT, both in the dominant and additive models. The IL-1B+3953T allele was associated with GD (p = 0.0003, OR = 1.93, CI = 1.34-2.78) and HT (p = 0.009, OR = 1.43, CI = 1.09-1.88). The IL-4 VNTR polymorphism was associated only with HT risk both in additive (p = 0.03, OR = 0.31, CI = 0.11-0.86) and recessive (p = 0.03, OR = 3.04, CI = 1.13-8.17) models. No significant association was found between IL-1B+3953C/T polymorphism and change in the serum concentrations of TSH and FT4 in GD and HT patients. In HT patients, the IL-1B+3953T allele (p = 0.009, OR = 0.42, CI = 0.22-0.83) and the IL-1B+3953T/T genotype (p = 0.03, OR = 0.21, CI = 0.04-1.07) were more frequent in the absence than in the presence of an anti-TPO antibody. The proportion of HT patients with the P1P2 genotype of the IL-4 gene was significantly higher in the absence than in the presence of the anti-TPO antibody (p = 0.04, OR = 0.39, CI = 0.17-0.89). These preliminary results suggest that IL-1B and IL-4 gene polymorphisms may be associated with GD and HT susceptibility and may represent prognostic factors for predicting the severity of HT.

Plasma VEGF-related polymorphisms are implied in autoimmune thyroid diseases.

Autoimmune thyroid diseases (AITD), including Graves' disease (GD) and Hashimoto thyroiditis (HT), are complex multifactorial diseases. Vascular endothelial growth factor (VEGF) is implicated in various inflammatory diseases, especially autoimmune diseases. Our aim was to elucidate the relationships between plasma VEGF levels and four genome-wide association study-identified single nucleotide polymorphisms (SNPs) related to VEGF with AITD in Tunisian patients. A total of 364 healthy controls and 389 patients with AITD were genotyped for the SNPs rs6921438, rs4416670, rs6993770 and rs10738760. Levels of thyroid hormones and antibodies were quantified simultaneously with plasma VEGF after a period of six months of treatment. We found that the minor alleles of rs10738760 and rs6921438 are associated with the presence of GD. A allele of rs10738760 polymorphism is associated with increased plasma levels of free tri-iodothyronin (FT3) while no relationship was found with circulating VEGF plasma levels after six months of treatment. We also showed that the T allele of rs4416670 polymorphism was associated with increased risk of hyperthyroidism in patients treated for six months, independently of their initial diagnosis. There was no significant association between the SNPs and the risk for HT compared with controls. This study shows that AITD are influenced by 3 SNPs linked to VEGF circulating levels. Whereas rs10738760 appeared specific to GD and FT3 production after six months of treatment, rs6921438 and rs4416670 were implicated in the risk for GD. This study opens new ways to test pharmacogenomics concepts in the future especially in GD in which recurrence prognosis is still challenging.

Polymorphisms in TSHR and IL1RN genes and the risk and prognosis of Hashimoto's thyroiditis.

Hashimoto's thyroiditis (HT) is a complex genetic autoimmune thyroid disease (AITD). Thyroid-stimulating hormone receptor (TSHR) is considered as candidate gene in AITD. IL1RN gene is involved in the pathogenesis of a number of autoimmune diseases. These findings prompted us to investigate the association of TSHR and IL1RN genes polymorphism with the risk and the prognosis of HT in Tunisia. A total of 249 healthy controls and 202 patients with HT were genotyped for TSHR D727E and IL1RN(VNTR) polymorphism. No significant difference was found for D727E polymorphism between HT patients and healthy controls. For IL1RN gene, we found an association between HT and IL1RN(VNTR) polymorphism. The A1A3 genotype was more prevalent in HT patients than in controls. However, the A1A4 genotype was associated with HT as a protective factor. Significant association of the TSHR polymorphism with lower plasma TSH level in HT patients has been detected. We found for the first time an association of IL1RN(VNTR) polymorphism with the production of anti-thyroid peroxidase antibody at the onset of disease. These preliminary results suggest that only the IL1RN(VNTR) polymorphism may be associated with HT susceptibility and that TSHR and IL1RN(VNTR) polymorphisms may represent prognostic factors for predicting the severity of HT.