The IL18 gene and Hashimoto thyroiditis in children

Association between IL-18 gene polymorphisms and Hashimoto thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT), which is also called lymphocytic thyroiditis, is the most frequent autoimmune thyroid disease (AITD), in which T helper-1 lymphocytes mediate the disease. IL-18 is expressed in thyroid follicular cells (TFCs) during HT. The findings of studies aimed at investigating the relationship between IL-18 and HT are highly contradictory. In this study, we aimed to investigate the association between IL-18 gene polymorphisms and HT.

METHODS AND RESULTS

The study included 97 patients diagnosed with HT and 86 volunteers in the healthy control group. The IL18-607C/A (rs1946518) and -137G/C (rs187238) genotypes were determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. No significant difference in the mean age or sex was observed between the groups (p = 0.763 and p = 0.658, respectively). The -137 IL18 CG genotype was more frequent in HT patients than in controls. In HT patients, the risk of the IL-18 CG genotype was more than 2.237 times higher (OR 2.237%95 Cl 1.195-4.187, p = 0.039) than that of the G/G genotype. Additionally, the -607 AC genotype was more frequent in the control group than in the HT group (in individuals with the IL18 CG genotype).

CONCLUSIONS

According to our results, the CG genotype might be a risk factor for HT. Conversely, there is a possibility that the AC genotype plays a protective role against the condition. However, further studies will contribute to new solutions by revealing the molecular and cellular mechanisms of HT.

Dysregulated Interleukin -33/ST2 Pathway Perpetuates Chronic Inflammation in Hashimoto’s Thyroiditis

Objective:

Hashimoto’s Thyroiditis (HT) is an autoimmune disease, characterized by chronic inflammation of the thyroid gland with unknown etiologies. Recently, interleukin-33/ST2 (IL- 33/ST2) pathway reveals its participation in the process of several autoimmune diseases. In this study, the role of IL-33/ST2 pathway in the development of HT is investigated.

Methods:

The levels of plasma IL-33, sST2 and the frequency of circulating CD4+ST2L+T cells in 30 HT patients and 20 healthy controls were determined by enzyme-linked immunosorbent assay (ELISA) and flow cytometry respectively. The mRNA expressions of related molecules in IL-33/ST2 pathway in thyroid tissues (12 HT patients and 10 controls) were detected by real-time quantitative PCR (RTqPCR). The protein expressions of IL-33 and ST2 were determined by Western blot and immunohistochemistry staining.

Results:

The mRNA expressions of plasma IL-33 and sST2 were elevated in HT patients, with an increased ratio of IL-33/sST2. The number of CD4+ST2L+ T cells in PBMCs of HT group was significantly increased when compared to the control group (CON) by Flow cytometry assay. MRNA Expression of IL-33 and ST2 in thyroid tissue and the level of IL-1β and IL-18 were significantly upregulated in HT patients, while IL-5 was down-regulated in HT patients, compared to CON. The expression of IL-1β and IL-18 were positively correlated with the expression of IL-33. Results of western blot and immunohistochemical staining were consistent with qPCR.

Conclusion:

IL-33/ST2 pathway participates in HT via affecting the production of inflammatory cytokines.

Association of Cytotoxic T-Lymphocyte-Associated Protein 4 (CTLA4) Gene Polymorphisms with Autoimmune Thyroid Disease in Children and Adults: Case-Control Study

Autoimmune thyroid disease (AITD), including Graves disease (GD) and Hashimoto disease (HD), is an organ-specific autoimmune disease with a strong genetic component. Although the cytotoxic T-lymphocyte-associated protein 4 (CTLA4) polymorphism has been reported to be associated with AITD in adults, few studies have focused on children. The aim of our study was to investigate whether the CTLA4 polymorphisms, including -318C/T (rs5742909), +49A/G (rs231775), and CT60 (rs3087243), were associated with GD and HD in Han Chinese adults and children. We studied 289 adult GD, 265 pediatric GD, 229 pediatric HD patients, and 1058 healthy controls and then compared genotype, allele, carrier, and haplotype frequencies between patients and controls. We found that CTLA4 SNPs +49A/G and CT60 were associated with GD in adults and children. Allele G of +49A/G was significantly associated with GD in adults (odds ratio [OR], 1.50; 95% confidence interval [CI], 1.21–1.84; corrected P value [Pc] < 0.001) and children (OR, 1.42; 95% CI, 1.15–1.77; Pc = 0.002). Allele G of CT60 also significantly increased risk of GD in adults (OR, 1.63; 95% CI, 1.27–2.09; Pc < 0.001) and GD in children (OR, 1.58; 95% CI, 1.22–2.04; Pc < 0.001). Significant linkage disequilibrium was found between +49A/G and CT60 in GD and control subjects (D’ = 0.92). Our results showed that CTLA4 was associated with both GD and HD and played an equivalent role in both adult and pediatric GD in Han Chinese population.