Plasma selectin levels in patients with Graves' disease

Transcriptome Profile of Thyroid Glands in Bile Duct Ligation Mouse Model

Thyroid hormone (TH) contributes to multiple cellular mechanisms in the liver, muscle cells, adipose tissue, and brain, etc. In particular, the liver is an important organ in TH metabolism for the conversion of thyronine (T4) into triiodothyronine (T3) by the deiodinase enzyme. TH levels were significantly decreased and thyroid-stimulating hormone (TSH) levels were significantly increased in patients with liver failure compared with normal subjects. Among liver failure diseases, hepatic encephalopathy (HE) deserves more attention because liver damage and neuropathologies occur simultaneously. Although there is numerous evidence of TH dysregulation in the HE model, specific mechanisms and genetic features of the thyroid glands in the HE model are not fully understood. Here, we investigated the significantly different genes in the thyroid glands of a bile duct ligation (BDL) mouse model as the HE model, compared to the thyroid glands of the control mouse using RNA sequencing. We also confirmed the alteration in mRNA levels of thyroid gland function-related genes in the BDL mouse model. Furthermore, we evaluated the increased level of free T4 and TSH in the BDL mouse blood. Thus, we emphasize the potential roles of TH in liver metabolism and suggest that thyroid dysfunction-related genes in the HE model should be highlighted for finding the appropriate solution for an impaired thyroid system in HE.

Effects of thyroxine on adhesion molecules and proinflammatory cytokines secretion on human umbilical vein endothelial cells

Thyroid dysfunction is associated with elevated cardiovascular risk factors and atherosclerosis. It could be suggested that, hyperthyroidism is related to a higher prevalence of arterial abnormalities. Therefore, evaluating the endothelial dysfunction (ED) related biomarkers seem to be an important issue. It is not clear whether endothelial cells are biologically responsive to thyroid hormones (THs) or how THs induces the production of endothelial cells (EC)-derived proinflammatory mediators. Hence, in this study the effects of thyroxine (T₄) on ED and inflammatory related mediators were evaluated. Human umbilical vein endothelial cells was used as endothelial cell model which was treated with concentrations of 50, 100, 200 nmol/L of T₄ in various exposure times. In the following, gene and protein expression levels of EC-related markers including intercellular adhesion molecule-1 (ICAM-1), vascular endothelial growth factor (VEGF), and E-selectin were determined using real time polymerase chain reaction (RT-PCR) and western blotting methods. Also, interleukin-6 (IL-6) and tumor necrosis factor (TNF-α) protein levels as proinflammatory cytokines were determined by enzyme linked immunosorbent assay (ELISA) method. Gene and protein expression analysis revealed that T₄ treatments up regulated the levels of VEGF, ICAM-1, and E-selectin as ED markers. In addition, T₄-treated cells had higher significant levels of IL-6 and TNF-α versus untreated cells in different incubation times. This study proposed the atherosclerotic effects of thyroid hormone. Based on our findings, T4 had strong effects on the gene and protein expression levels of pro-inflammatory, angiogenesis, and ED major mediators associated with atherosclerosis development.

The expression of microvesicles in the blood of patients with Graves' disease and its relationship to treatment

OBJECTIVE

Graves' disease (GD) is an autoimmune disease characterized by the presence of circulating autoantibodies against thyroid-stimulating hormone (TSH) receptor. Despite extensive research, the pathogenic mechanisms remain unclear. Immune responses associated with the disease may lead to cell activation/apoptosis and the release of microvesicles (MVs) into the circulation. MVs can display biological activities which may aggravate GD further. We studied immune mechanisms in GD by investigating the numbers and phenotype of circulating MVs in patients before and after antithyroid therapy with thiamazole.

PATIENTS AND MEASUREMENTS

Samples were obtained from 15 patients with GD in the acute phase of hyperthyroidism and following 17-26 months treatment and 14 healthy controls. MVs from platelets, endothelial cells and monocytes exposing inflammation/activation markers (P-selectin, CD40 ligand, E-selectin and HMGB1) and MVs containing nuclear molecules were measured with flow cytometry.

RESULTS

Patients had elevated baseline values of MVs (P < 0·001 for all types of MVs), while the levels decreased during thiamazole treatment (P < 0·05 for all types of MVs). The majority of MV populations remained, however, significantly higher in patients after treatment compared to levels in controls.

CONCLUSIONS

GD patients have elevated levels of MVs that carry molecules with potential biological activities. MVs are significantly reduced after antithyroid treatment with thiamazole but still higher compared to levels in healthy controls. Assessment of MV levels and pattern may therefore provide additional information on underlying immune disturbances not obtained by measurements of hormone levels alone.

Prothrombotic alterations in plasma fibrin clot properties in thyroid disorders and their post-treatment modifications

INTRODUCTION

Available data on fibrin clot properties and fibrinolysis in hyperthyroidism and hypothyroidism are inconsistent. Our objective was to assess the impact of effective treatment of hyper- and hypothyroidism on fibrin clot characteristics.

MATERIAL AND METHODS

In a case-control study, ex vivo plasma fibrin clot permeability (Ks) and efficiency of fibrinolysis were assessed in 35 consecutive hyperthyroid and 35 hypothyroid subjects versus 30 controls. All measurements were performed before and after 3months of thyroid function normalizing therapy.

RESULTS

At baseline, hyperthyroid, but not hypothyroid, patients had lower Ks than controls (p<0.0001). Hyperthyroid and hypothyroid groups compared with controls had prolonged clot lysis time (CLT), and lower rate of D-dimer release from clots (D-Drate) (all p<0.05). The regression analysis adjusted for fibrinogen showed that in hyperthyroid patients, pre-treatment thyroid stimulating hormone (TSH) independently predicted Ks, while thrombin activatable fibrinolysis inhibitor (TAFI) antigen predicted CLT. In hypothyroid individuals a similar regression model showed that TSH independently predicts CLT. After 3months of thyroid function normalizing therapy, 32 (91.4%) hyperthyroid and 30 (85.7%) hypothyroid subjects achieved euthyroidism and had improved fibrin clot properties (all p<0.05), with normalization of Ks in hyperthyroid and lysability in hypothyroid patients.

CONCLUSIONS

Both hyper- and mild-to-moderate hypothyroidism are associated with prothrombotic plasma fibrin clot phenotype and restoration of euthyroidism improves clot phenotype. Abnormal fibrin clot phenotype might contribute to thromboembolic risk in thyroid disease.

The new perspectives on genetic studies of type 2 diabetes and thyroid diseases

Recently, genome-wide association studies (GWAS) have led to the discovery of hundreds of susceptibility loci that are associated with complex metabolic diseases, such as type 2 diabetes and hyperthyroidism. The majority of the susceptibility loci are common across different races or populations; while some of them show ethnicity-specific distribution. Though the abundant novel susceptibility loci identified by GWAS have provided insight into biology through the discovery of new genes or pathways that were previously not known, most of them are in introns and the associated variants cumulatively explain only a small fraction of total heritability. Here we reviewed the genetic studies on the metabolic disorders, mainly type 2 diabetes and hyperthyroidism, including candidate genes-based findings and more recently the GWAS discovery; we also included the clinical relevance of these novel loci and the gene-environmental interactions. Finally, we discussed the future direction about the genetic study on the exploring of the pathogenesis of the metabolic diseases.

Genetic variants in ABO blood group region, plasma soluble E-selectin levels and risk of type 2 diabetes

Blood soluble E-selectin (sE-selectin) levels have been related to various conditions such as type 2 diabetes. We performed a genome-wide association study among women of European ancestry from the Nurses' Health Study, and identified genome-wide significant associations between a cluster of markers at the ABO locus (9q34) and plasma sE-selectin concentration. The strongest association was with rs651007, which explained approximately 9.71% of the variation in sE-selectin concentrations. SNP rs651007 was also nominally associated with soluble intracellular cell adhesion molecule-1 (sICAM-1) (P = 0.026) and TNF-R2 levels (P = 0.018), independent of sE-selectin. In addition, the genetic-inferred ABO blood group genotypes were associated with sE-selectin concentrations (P = 3.55 x 10(-47)). Moreover, we found that the genetic-inferred blood group B was associated with a decreased risk (OR = 0.44, 0.27-0.70) of type 2 diabetes compared with blood group O, adjusting for sE-selectin, sICAM-1, TNF-R2 and other covariates. Our findings indicate that the genetic variants at ABO locus affect plasma sE-selectin levels and diabetes risk. The genetic associations with diabetes risk were independent of sE-selectin levels.

The common variants of E-selectin gene in Graves' disease

Adhesion molecules are involved in cell invasion in autoimmune thyroid disease. It was also reported that patients with untreated Graves' disease (GD) had high serum level of soluble form of E-selectin (sE-selectin), the concentration of which correlated with the activity of the disease. The aim of the present study was to elucidate whether the common variants in E-selectin gene (SELE) were associated with the development of GD. Six tagSNPs within SELE were studied in 297 patients with GD and 208 healthy subjects in Chinese population. Our data showed that common SELE variants were associated with GD (P=0.012-0.036). Haplotype analysis of the single nucleotide polymorphisms revealed an association of a haplotype ATAACC with GD (P=0.005). Furthermore, quantitative trait analysis showed a significant association of SELE haplotype with sE-selectin levels (P=0.0438). This study therefore could provide us to a certain degree the insight that common SELE variants may be associated with susceptibility to GD in Chinese population, though the limitation of sample size and multiple test problems exists.

L-selectin gene polymorphisms in Graves' disease

OBJECTIVE

Graves' disease (GD) is an autoimmune disorder with genetic predisposition. There is strong evidence that members of the selectin family participate in the interaction between leucocytes and the endothelium, as well as in inflammatory cell recruitment. Moreover, a high serum level of a soluble form of L-selectin (SL-selectin) has been reported in untreated GD patients. However, the impact of L-selectin polymorphisms on GD has not yet been investigated. The aim of the present study was to elucidate whether L-selectin gene polymorphisms were associated with the development of GD.

SUBJECTS AND DESIGN

L-selectin gene polymorphisms were investigated in 230 Chinese GD patients and 208 healthy control subjects without antithyroid autoantibodies or a family history of autoimmune disorders. Two L-selectin SNPs were genotyped by the PCR-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

A C/T polymorphism at position -642 of the promoter region and a Pro213Ser (c.725 C-T) polymorphism in exon 6 were examined using PCR-RFLP. There was a significant increase in -642T allele frequency in GD patients compared with healthy controls (70 vs. 62%; P = 0.0126; P(c) = 0.0252). The frequency of the c.725C allele in exon 6 also appeared higher in GD patients than in controls. Haplotype analysis showed a significant decrease in the -642C/c.725T haplotype in GD patients (26 vs. 34%; P = 0.0095; Pc = 0.0190). However there was no association between polymorphisms and certain GD clinical phenotypes, including age of onset and ophthalmopathy.

CONCLUSIONS

L-selectin gene polymorphisms are associated with GD susceptibility in Chinese patients.

Intercellular adhesion molecule 1 gene polymorphisms do not contribute to Graves' disease in Chinese patients

OBJECTIVE

In order to study the association of G241R polymorphism of ICAM-1 gene with an earlier onset of Graves' disease (GD) and the susceptibility of K469E polymorphism to Graves' ophthalmopathy (GO) in Chinese population.

STUDY DESIGN

A case-control and replication study was performed in 212 GD patients and 204 healthy subjects to analyze the genotypes. Furthermore the distribution of ICAM-1 genotypes was investigated in subgroups of patients with GD according to the onset age and the ophthalmopathy.

RESULTS

No G241R polymorphism of ICAM-1 gene was detected in Chinese. No significant differences of allele and genotype frequencies regarding K469E polymorphism were found between GD patients and healthy controls (chi2 = 0.092, P = 0.762; chi2 = 1.089, P = 0.580). In addition, the genotype-phenotype correlation was not identified either.

CONCLUSIONS

We found no association of G241R and K469E polymorphisms of the ICAM-1gene with the development of GD in a Chinese population. However, we could not rule out possible contributions of other polymorphisms of the ICAM-1gene to the pathogenesis of GD. Therefore, further studies are needed to elucidate the role of ICAM-1gene in Graves' disease in different population.

Expression of very late antigen-4 and lymphocyte function-associated antigen-1 on peripheral blood lymphocytes from patients with graves disease

The aim of the study was to estimate the expression of beta1 integrin CD49d (very late antigen-4), beta2 integrin CD11a (lymphocyte function-associated antigen 1 alpha), L-selectin (CD62L), and intercellular adhesion molecule-1 [ICAM-1 (CD54)] on peripheral blood mononuclear cells in patients with Graves disease (GD) (n = 45, mean age 15.9 +/- 5.9 y), in patients with nontoxic nodular goiter (NTNG) (n = 25, mean age 15.2 +/- 5.7 y), and in sex- and age-matched healthy control subjects (n = 25, mean age 15.9 +/- 2.4 y). The expression of the lymphocyte adhesion molecules was analyzed by the three-color flow cytometry. Decreased percentages of CD49d+ and CD11a+ lymphocytes were observed in untreated Graves' patients in comparison to healthy controls (p < 0.007, p < 0.036) and non-toxic nodular goiter patients (p < 0.006, p < 0.019). The analysis of CD62L+ and CD54+ antigen expression on peripheral blood lymphocytes revealed increased percentages of L-selectin- and ICAM-1-positive cells in patients with GD (p < 0.005 for CD62L, p < 0.008 for ICAM-1) before methimazole therapy, compared with healthy controls. These abnormalities were absent in children with NTNG. In patients with untreated GD, a positive correlation was found between serum levels of free thyroxine and the percentage of CD54+ lymphocytes (r = 0.47, p < 0.036). Statistically significant negative correlations existed between free thyroxine concentration in blood serum and the percentage of CD11a+ lymphocytes (r = -0.39, p < 0.033). No such correlation was detected between the percentage of lymphocyte markers and serum levels of antithyroid antibodies. We conclude that the alterations in the expression of adhesion molecules on peripheral blood mononuclear cells might suggest their role in the development of GD.