Demonstration of interleukin-1 beta on perifollicular endothelial cells in the thyroid glands of patients with Graves' disease

Role of chemokines in endocrine autoimmune diseases

Chemokines are a group of peptides of low molecular weight that induce the chemotaxis of different leukocyte subtypes. The major function of chemokines is the recruitment of leukocytes to inflammation sites, but they also play a role in tumoral growth, angiogenesis, and organ sclerosis. In the last few years, experimental evidence accumulated supporting the concept that interferon-gamma (IFN-gamma) inducible chemokines (CXCL9, CXCL10, and CXCL11) and their receptor, CXCR3, play an important role in the initial stage of autoimmune disorders involving endocrine glands. The fact that, after IFN-gamma stimulation, endocrine epithelial cells secrete CXCL10, which in turn recruits type 1 T helper lymphocytes expressing CXCR3 and secreting IFN-gamma, thus perpetuating autoimmune inflammation, strongly supports the concept that chemokines play an important role in endocrine autoimmunity. This article reviews the recent literature including basic science, animal models, and clinical studies, regarding the role of these chemokines in autoimmune endocrine diseases. The potential clinical applications of assaying the serum levels of CXCL10 and the value of such measurements are reviewed. Clinical studies addressing the issue of a role for serum CXCL10 measurement in Graves' disease, Graves' ophthalmopathy, chronic autoimmune thyroiditis, type 1 diabetes mellitus, and Addison's disease have been considered. The principal aim was to propose that chemokines, and in particular CXCL10, should no longer be considered as belonging exclusively to basic science, but rather should be used for providing new insights in the clinical management of patients with endocrine autoimmune diseases.

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.

Detection and localization of chemokine gene expression in autoimmune thyroid disease

OBJECTIVE

Autoimmune thyroid disease (Hashimoto's thyroiditis and Graves' disease) is characterized by lymphocytic infiltration of the thyroid gland. Chemokines are cytokines with chemoattractant properties for a range of immune effector cells and might therefore play a significant role in the initiation and maintenance of the autoimmune process. The aim of this study was to analyse chemokine gene expression in autoimmune thyroid tissue and in cultured thyroid follicular cells (TFC).

DESIGN AND PATIENTS

Immunocytochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR) amplification were used to analyse the expression of monocyte chemoattractant protein (MCP)-1, RANTES (regulated upon activation, normal T cell expressed and secreted), macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, interferon (IFN)-gamma-inducible protein (IP)-10 and monokine induced by IFN-gamma (Mig) in thyroid tissue from patients with Hashimoto's thyroiditis (n = 4), Graves' disease (n = 6) and nonautoimmune multinodular goitre (n = 4). Chemokine gene expression was also examined in cultured TFC by RT-PCR.

RESULTS

Expression of MCP-1, RANTES, MIP-1 alpha, MIP-1 beta, IP-10 and Mig was demonstrated in all Hashimoto's and most Graves' thyroid specimens but very little expression was detected in the nonautoimmune goitre samples. In thyroid tissue from Graves' disease patients, positive staining for chemokines was largely restricted to the lymphocytic cell infiltrate. Within thyroid tissue from Hashimoto's patients, there was evidence for the expression of all chemokines by thyroid follicular cells, suggesting a role for local chemokine synthesis by the glandular epithelial cells in the recruitment of inflammatory cells into the gland in autoimmunity. The present work also showed that expression all the chemokine genes analysed could be induced in cultured thyroid cells by IFN-gamma and interleukin (IL)-1 alpha. Expression of all the chemokines examined was not stimulated by TSH.

CONCLUSION

We postulate that TFC may play a role in the pathogenesis of autoimmune thyroid disease as they are able to express the chemokines MIP-1 alpha, MIP-1 beta, MCP-1, RANTES, IP-10 and Mig that would promote the infiltration of immune cells into the thyroid gland.

Cytokines and thyroid function

Cytokines play a crucial role in autoimmune thyroid disease (ATD) through various mechanisms. They are produced in the thyroid by intrathyroidal inflammatory cells, in particular lymphocytes, as well as by the thyroid follicular cells (TFC) themselves and may thus act in a cascade to enhance the autoimmune process (Fig. 1). Cytokines upregulate the inflammatory reaction through stimulation of both T and B cells, resulting in antibody production and tissue injury. In addition, intrathyroidal cytokines induce immunological changes in TFC including enhancement of both major histocompatibility complex (MHC) class I and class II molecule expression, and upregulation of adhesion and complement regulatory molecule expression. Cytokines can also modulate both growth and function of TFC and have a role in extrathyroidal complications of ATD, most importantly thyroid-associated ophthalmopathy (TAO), where they induce fibroblast proliferation and enhance the production of glycosaminoglycans (GAG), resulting in proptosis and the other clinical features of the disease. In addition to these effects, exogenous administration of cytokines has been associated with impairment of thyroid function ranging from the appearance of autoantibodies alone to the development of frank thyroid dysfunction. Cytokines have also been implicated in subacute thyroiditis (SAT) and amiodarone-induced thyroid dysfunction, as well as in thyroid function abnormalities occurring in patients with non-thyroidal illnesses (NTI). Genetic variations in cytokine genes represent potential risk factors for ATD, and disease associations have been described for polymorphisms in IL-1ra and TNF beta genes. Recent experimental evidence suggests the possibility of novel cytokine-based therapeutic approaches for ATD and its complications, in particular TAO.

Increased plasma levels of endothelin-1 in patients with hyperthyroidism

Plasma concentrations of endothelin-1 (ET-1) were measured in 25 hyperthyroid subjects, 15 hypothyroid subjects, and 21 age-matched normal controls. In hyperthyroid patients, plasma concentrations of ET-1 were significantly higher than in the control group (P < .0001) and in hypothyroid patients (P < .0001). In contrast, no differences were found between hypothyroid patients and controls. Plasma levels of ET-1 were similarly elevated as in patients with Graves' disease and those with toxic adenoma. No correlations were found between plasma ET-1 levels, thyroid hormones, and thyrotropin (TSH) in hyperthyroid, hypothyroid, and euthyroid groups. The results of our study clearly indicate that in hyperthyroidism, circulating levels of ET-1 are strongly increased, although the pathogenesis of the increase is unclear.

Increased serum interleukin-1 beta during treatment of hyperthyroidism with antithyroid drugs

Serum interleukin-1 beta (IL-1 beta) and soluble interleukin-2 receptor (sIL-2R) levels were examined in patients with hyperthyroidism due to Graves' disease (GD) and toxic nodular goitre (TNG) before and during antithyroid drug therapy. A total of 32 patients were studied; 23 patients (14 with GD and nine with TNG) were in a hyperthyroid state (group A) and nine patients (four with GD and five with TNG) were in a euthyroid state, under carbimazole or methimazole treatment (group B). Ten hyperthyroid patients from group A (seven with GD and three with TNG) were also examined while euthyroid on treatment (Subgroup A). Serum was taken from all patients for the measurement of sIL-2R, IL-1 beta, total T4 (TT4), total T3 (TT3) and TSH concentrations. The results were compared with those from 30 normal controls. Serum sIL-2R levels were higher in Group A (671.3 +/- 74.0 U mL-1, mean +/- SE), than in Group B (214.1 +/- 61.8 U mL-1) and controls (149 +/- 14.8 U mL-1), P < 0.001. Similarly, the subgroup of 10 patients had higher levels of sIL-2R during the hyperthyroid phase than while euthyroid (P < 0.001). There was a positive correlation between sIL-2R values and levels of T4 and T3. In contrast, serum IL-1 beta levels were higher in Group B patients (197.5 +/- 39.2 pg mL-1) compared with those in Group A (66.5 +/- 17 pg mL-1, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The potential immunological role of the thyroid cell in autoimmune thyroid disease

Over the last decade it has become evident that thyroid follicular cells express a number of immunologically active molecules in autoimmune thyroid disease that may endow them with the capacity to interact with cells of the classical immune system. Expression of major histocompatibility complex class II molecules is induced by gamma-interferon, but there is no evidence yet that thyroid follicular cells can concurrently express the costimulatory signals necessary for class II expression to result in T cell stimulation: in this situation, class II expression may have a protective role, inducing T cell anergy. Thyroid follicular cells also express a variety of cell surface proteins (in particular CD59) that may protect the cells from complement attack. On the other hand, the expression of adhesion molecules and cytokines by thyrocytes would seem to be harmful, as these are likely to exacerbate autoimmune injury. Further study of the immunological role of thyroid follicular cells will shed new light on the pathogenesis of Graves' disease and autoimmune hypothyroidism, and may lead to novel therapeutic approaches to these disorders.

Intercellular adhesion molecule-1 (ICAM-1) in Graves' disease: contrast between in vivo and in vitro results

We have reassessed the possible role of the adhesion molecule ICAM-1 in the pathogenesis of thyroid autoimmunity. In order to do that, we have investigated its expression in eight Graves' thyroids both in vivo (i.e. on cryostat sections and on cell suspensions), and in vitro (i.e. on cells cultured in monolayers for 3 days), and the results were compared with those obtained with similar preparations from four normal glands. On cryostat sections, the expression of ICAM-1, and for comparison that of HLA Class I and Class II molecules, was studied by immunofluorescence (IFL), but the former were also assessed by a distinct immunohistochemical technique. ICAM-1 was not detected in thyrocytes in vivo of both normal and Graves' glands, but solely in endothelial cells and antigen-presenting cells (APC). This selective reaction was confirmed by a four-layer technique using specific markers which identify endothelial cells and thyrocytes. HLA Class II molecules were confirmed to be inappropriately expressed in thyrocytes of Graves' glands, but there was no co-expression of these products and ICAM-1 in the same cells. In contrast, ICAM-1 appeared de novo in a proportion of Graves' and normal thyrocytes soon after the attachment and spreading of these cells in monolayer cultures (36-48 h). Graves' thyrocytes showed a quantitatively higher degree of expression compared with that detected on normal thyroid cells (40-70% versus 12-20%). Under these experimental conditions, the four-layer staining with thyroid microsomal antibodies confirmed that thyrocytes were indeed the positive cells which expressed ICAM-1. Blocking experiments with cultured thyrocytes from two Graves' glands and MoAbs to tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) did not prevent the occurrence of ICAM-1 expression. As a result of our study, we failed to demonstrate that Graves' thyrocytes express ICAM-1 in vivo. The unexpected case of inducing ICAM-1 on thyroid cells under certain in vitro conditions remains intriguing. The phenomenon could be the simple consequence of a mechanical effect rather than exerted by specific biological processes. Further investigations are, therefore, needed to establish whether ICAM-1 is really involved in the pathogenesis of Graves' disease.

Thyroid cells in Graves' disease and Hashimoto's thyroiditis stimulate allogeneic T cells when pretreated with phorbol ester

OBJECTIVE

To assess the capacity of thyroid follicular cells to function as antigen presenting cells, we have examined their ability to stimulate allogeneic T cells.

DESIGN

Thyroid follicular cells were pretreated with interferon-gamma or phorbol myristate acetate, washed thoroughly, and their capacity to induce allogeneic T cell proliferation was determined.

PATIENTS

Thyroid cells were prepared using thyroidectomy specimens from eight patients with Graves' disease, one with Hashimoto's thyroiditis and two with non-toxic multinodular goitre.

MEASUREMENTS

T cell 3H-thymidine incorporation was measured after a 16-hour incubation period with the isotope, 3 days after co-culture of T cells and thyroid cells.

RESULTS

Four of the eight thyroid cell preparations from thyroid autoimmunity patients failed to stimulate T cells, although there was a significant, weak stimulation for the whole group (P < 0.05): interferon-gamma pretreatment had no effect on this. Phorbol myristate acetate pretreatment significantly increased the ability of thyroid cells (from both autoimmune and multinodular glands) to stimulate T cells (P < 0.05); this was time and concentration dependent. Cell fixation after PMA treatment did not abolish this stimulatory activity, which could be transferred by supernatants from unfixed cells; exogenous interleukin-1 did not mimic the activity.

CONCLUSIONS

Thyroid cells expressing major histocompatibility complex class II molecules only weakly and inconsistently stimulate allogeneic T cells, compared to thyroid cells pretreated with phorbol myristate acetate, a difference which may be due to the expression of an unidentified co-stimulatory signal induced by phorbol ester.

Cytokines in fluids from polycystic kidneys

We sought evidence of cytokine presence and interleukin-1 beta (IL-1 beta) bioactivity in 104 aerobic culture negative cyst fluids (CFs) from 13 kidneys of 13 patients with symptomatic normal to end-stage autosomal dominant polycystic kidney disease (ADPKD). ELISAs were used to detect IL-1 beta, interleukin-2 (IL-2), tumor necrosis factor alpha (TNF alpha) and stromelysin. Prostaglandin E2 (PGE2) was detected by radioimmunoassay. IL-1 beta was present in 65 of 94 (less than 20 to 419 pg/ml, TNF alpha in 54 of 75 (less than 10 to 73 pg/ml), stromelysin in 18 of 23 (less than 1.0 to 56 ng/ml), IL-2 in 7 of 23 (0.1 to 1.3 ng/ml) and PGE2 in 9 of 10 fluids (0.03 to 0.49 ng/ml). Of 51 fluids with immunoreactive IL-1 beta, 36 were mitogenic for thymocytes. IL-1 beta concentrations correlated directly with those of IL-2; IL-1 beta presence was associated with higher stimulation indices, higher mean concentrations of TNF alpha, IL-2, stromelysin, and PGE2, and with positive endotoxin assays, suggesting activation of the cytokine cascade in vivo. Cytokine, stromelysin and PGE2 concentrations did not correlate with sodium or non-sodium solute concentrations, nor with CF blood, osmolality, or endotoxin activity, indicating that differences in concentrations among fluids could not be explained by differences in water content. These data identify cytokines as candidate contributors to the morbidity and pathogenesis of ADPKD.

Detection of interleukin-6 and interleukin-1 production in human thyroid epithelial cells by non-radioactive in situ hybridization and immunohistochemical methods

Human endocrine thyroid epithelial cells have been described to produce cytokines in vitro. In order to determine whether they do so in vivo during thyroiditis, parallel studies on mRNA expression with a non-radioactive in situ hybridization technique and immunohistochemical detection for the protein were performed on frozen sections of thyroid samples from autoimmune thyroiditis (Graves' disease and Hashimoto's thyroiditis), non-toxic goitre and normal thyroid tissue. cDNA probes were sulphonated and their hybridization with mRNA was detected with a sulphonyl-specific monoclonal antibody. This signal was amplified and visualized with the alkaline phosphatase-anti-alkaline phosphatase (APAAP) system. The protein products were detected with immuno-purified rabbit F(ab')2 antibody fragments recognizing recombinant human cytokines, visualized by the immunoperoxidase technique. Each sample was studied at the two levels. Both interleukin-6 mRNA and protein were found in the endocrine cells. There was no obvious difference between autoimmune thyroiditis and non-toxic goitre. However, normal thyroid epithelial cells produced less interleukin-6. Interleukin-1 alpha mRNA and its protein were found in epithelial cells from Hashimoto's thyroiditis samples, but not in the others, except one Graves' disease sample, in which only mRNA was detected. Interleukin-1 beta was not detected in these cells, its mRNA was only found in one of the Graves' disease samples. These cytokines were also detected in some infiltrating cells.