Interleukin-6 production by thyroid epithelial cells. Enhancement by interleukin-1

Aberrant MRP14 expression in thyroid follicular cells mediates chemokine secretion through the IL-1β/MAPK pathway in Hashimoto's thyroiditis

Myeloid-related protein 14 (MRP14) is responsible for inflammatory reactions. However, the correlation between MRP14 and Hashimoto's thyroiditis (HT) is still not clear. In this study, we examined the status of MRP14 in thyroid tissues and sera of HT patients and explored the mechanism of IL-1β-mediated regulation of MRP14 expression, as well as the effects of MRP14 on pro-inflammatory chemokine secretion in thyroid follicular cells (TFCs), to elucidate the role of MRP14 in HT development. Our results showed dramatically increased MRP14 expression in thyroid tissues and sera from HT patients. In addition, IL-1β significantly promoted the expression of MRP14 in TFCs, which was mediated by activation of the MAPK/NF-κB signalling pathway. More importantly, IL-1β induced the secretion of the chemokines GRO-2, CXCL9 and CCL22, which was dependent on the regulation of MRP14 in TFCs. Therefore, these findings suggested that under pro-inflammatory conditions, TFCs secreted chemokines with the help of MRP14 regulation, which might suggest a potential pathological mechanism of lymphocyte infiltration into the thyroid gland in HT.

The flame retardant DE-71 (a mixture of polybrominated diphenyl ethers) inhibits human differentiated thyroid cell function in vitro

BACKGROUND

Normal thyroid function is essential for general growth and metabolism, but can be affected by endocrine disrupting chemicals (EDCs). Polybrominated diphenyl ethers (PBDEs) have been used worldwide to reduce flammability in different materials and are suspected to be EDCs. The production of the commercial Penta- and OctaBDE mixtures is banned, but DecaBDEs and existing products may leak PBDEs into the environment. Our aim was to investigate the effect of the PentaBDE mixture DE-71 on human thyroid cells in vitro.

MATERIALS AND METHODS

Primary human thyroid cells were obtained as paraadenomatous tissue and cultured in monolayers. The influence of DE-71 on cyclic adenosine monophosphate (cAMP) and thyroglobulin (Tg) production was examined in the culture medium by competitive radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Real-time quantitative PCR analysis of thyroid-specific genes was performed on the exposed cell cultures. PBDE concentrations were determined in cellular and supernatant fractions of the cultures.

RESULTS

DE-71 inhibited Tg-release from TSH-stimulated thyrocytes. At 50 mg/L DE-71, mean Tg production was reduced by 71.9% (range: 8.5-98.7%), and cAMP by 95.1% (range: 91.5-98.8%) compared to controls). Expression of mRNA encoding Tg, TPO and TSHr were significantly inhibited (p<0.0001, p = 0.0079, and p = 0.0002, respectively). The majority of DE-71 added was found in the cell fraction. No cytotoxicity was found.

CONCLUSIONS

DE-71 inhibited differentiated thyroid cell functions in a two phase response manner and a concentration-dependent inhibition of Tg and cAMP production, respectively, as well as expression of mRNA encoding Tg, TPO and TSHr. Our findings suggest an inhibiting effect of PBDEs on thyroid cells.

The teleost head kidney: Integrating thyroid and immune signalling

The head kidney, analogous to the mammalian adrenal gland, is an organ unique for teleost fish. It comprises cytokine-producing lymphoid cells from the immune system and endocrine cells secreting cortisol, catecholamines, and thyroid hormones. The intimate organization of the immune system and endocrine system in one single organ makes bidirectional signalling between these possible. In this review we explore putative interactions between the thyroid and immune system in the head kidney. We give a short overview of the thyroid system, and consider the evidence for the presence of thyroid follicles in the head kidney as a normal, healthy trait in fishes. From mammalian studies we gather data on the effects of three important pro-inflammatory cytokines (TNFα, IL-1β, IL-6) on the thyroid system. A general picture that emerges is that pro-inflammatory cytokines inhibit the activity of the thyroid system at different targets. Extrapolating from these studies, we suggest that the interaction of the thyroid system by paracrine actions of cytokines in the head kidney is involved in fine-tuning the availability and redistribution of energy substrates during acclimation processes such as an immune response or stress response.

Elevated interleukin-1β in peripheral blood mononuclear cells contributes to the pathogenesis of autoimmune thyroid diseases, especially of Hashimoto thyroiditis

PURPOSE OF THE STUDY

To explore the relationship between IL-1β expression and two common autoimmune thyroid diseases: Hashimoto thyroiditis (HT) and Graves' disease (GD).

MATERIALS AND METHODS

qRT-PCR, Quantiglo ELISA, and flow cytometry were used to evaluate the expression levels of IL-1β in serum, peripheral blood mononuclear cells (PBMCs), and thyroid tissue samples from patients with HT or GD. Local infiltration of monocytes was assessed by immunohistochemical study of patients' thyroid tissue samples.

RESULTS

Although no significant differences in IL-1β levels were found between samples of serum from patients with HT or GD and normal controls, we found that IL-1β mRNA and protein levels in PBMCs of HT patients were significantly higher than those of patients with GD, which were in turn higher than the level in normal controls. In addition, IL-1β mRNA was also increased in thyroid gland tissue from patients with HT compared to those with GD, and this was accompanied by increased local infiltration of monocytes into thyroid tissues. Correlation analysis of the clinical samples validated the association of high IL-1β levels with the pathogenesis of HT.

CONCLUSION

Our study suggests that IL-1β may be an active etiologic factor in the pathogenesis of HT and thus present a new target for novel diagnostics and treatment.

Phthalates Are Metabolised by Primary Thyroid Cell Cultures but Have Limited Influence on Selected Thyroid Cell Functions In Vitro

Phthalates are plasticisers added to a wide variety of products, resulting in measurable exposure of humans. They are suspected to disrupt the thyroid axis as epidemiological studies suggest an influence on the peripheral thyroid hormone concentration. The mechanism is still unknown as only few in vitro studies within this area exist. The aim of the present study was to investigate the influence of three phthalate diesters (di-ethyl phthalate, di-n-butyl phthalate (DnBP), di-(2-ethylhexyl) phthalate (DEHP)) and two monoesters (mono-n-butyl phthalate and mono-(2-ethylhexyl) phthalate (MEHP)) on the differentiated function of primary human thyroid cell cultures. Also, the kinetics of phthalate metabolism were investigated. DEHP and its monoester, MEHP, both had an inhibitory influence on 3'-5'-cyclic adenosine monophosphate secretion from the cells, and MEHP also on thyroglobulin (Tg) secretion from the cells. Results of the lactate dehydrogenase-measurements indicated that the MEHP-mediated influence was caused by cell death. No influence on gene expression of thyroid specific genes (Tg, thyroid peroxidase, sodium iodine symporter and thyroid stimulating hormone receptor) by any of the investigated diesters could be demonstrated. All phthalate diesters were metabolised to the respective monoester, however with a fall in efficiency for high concentrations of the larger diesters DnBP and DEHP. In conclusion, human thyroid cells were able to metabolise phthalates but this phthalate-exposure did not appear to substantially influence selected functions of these cells.

Influence of phthalates on cytokine production in monocytes and macrophages: a systematic review of experimental trials

Background

Phthalates are a group of endocrine disrupting chemicals suspected to influence the immune system. The aim of this systematic review is to summarise the present knowledge on the influence of phthalates on monocyte and macrophage production and secretion of cytokines, an influence which could affect both pro- and anti-inflammatory abilities of these cells.

Strategy and Results

A systematic search was performed in Medline, Embase and Toxline in June 2013, last updated 3rd of August 2014. Criteria used to select studies were described and published beforehand online on Prospero (http://www.crd.york.ac.uk/NIHR_PROSPERO, registration number CRD42013004236). In vivo, ex vivo and in vitro studies investigating the influence of phthalates on cytokine mRNA expression and cytokine secretion in animals and humans were included. A total of 11 reports, containing 12 studies, were found eligible for inclusion. In these, a total of four different phthalate diesters, six primary metabolites (phthalate monoesters) and seven different cytokines were investigated. Though all studies varied greatly in study design and species sources, four out of five studies that investigated di-2-ethylhexyl phthalate found an increased tumour necrosis factor-α secretion/production from monocytes or macrophages. A summary of cytokine measurements was not possible since few studies were comparable in study design and due to insufficient reporting of raw data for most of the included studies.

Conclusion

Results from this review have suggested that at least one phthalate (di-2-ethylhexyl phthalate) has the ability to enhance tumour necrosis factor-α production/secretion from monocytes/macrophages in vitro, but also observed ex vivo. Influence of other phthalates on other cytokines has only been investigated in few studies. Thus, in vitro studies on primary human monocytes/macrophages as well as more in vivo studies are needed to confirm or dispute these findings.

Interleukin-8 production from human somatotroph adenoma cells is stimulated by interleukin-1β and inhibited by growth hormone releasing hormone and somatostatin

OBJECTIVE

Pituitary adenomas cause morbidity and mortality due to their localization and influence on pituitary hormone secretion. Although the pathogenesis of pituitary adenomas is unclear, studies have indicated that cytokines are involved. We investigated the role of cytokines, in particular interleukin (IL)-8, in the pathogenesis of growth hormone (GH) producing tumours.

DESIGN

Human somatotroph adenoma tissue was obtained from patients undergoing surgery for acromegaly. The tissue underwent mechanical and enzymatic digestion, was washed, suspended and cultured in 24-chamber plates. After stimulation/inhibition supernatants were harvested. As control of growth hormone producing properties of the cultured cells, GH releasing hormone (GHRH) stimulated and somatostatin inhibited the GH response.

RESULTS

The cultured adenoma cells released both IL-6 and IL-8 and the secretion was inhibited by GHRH and somatostatin. IL-1β dose-dependently stimulated GH, IL-6 and IL-8 secretion.

CONCLUSION

Using cultured primary somatotroph adenoma cells as a dynamic method, we found a consistent release not only of IL-6 as described previously, but also of IL-8. This finding could be important for reassessing a role of these cytokines in the pathogenesis of pituitary tumour growth and function, and thus form a basis for targeted therapy. In line with previous studies, our results further indicated a common physiological or pathophysiological reaction of endocrine cells to cytokine stimulation.

Activation of the cAMP pathway synergistically increases IL-1-induced IL-6 gene expression in FRTL-5 thyroid cells: involvement of AP-1 transcription factors

Interleukin-6 (IL-6) is a multifunctional cytokine involved in autoimmune thyroid diseases such as Hashimoto's thyroiditis and Graves' disease. IL-6 is produced by infiltrating immune cells and by thyrocytes. In the latter cell type, secretion of IL-6 is stimulated notably by interleukin-1 (IL-1), thyroid-stimulating hormone (TSH) or forskolin (Fk), a cAMP elevating agent. We report here that Fk and IL-1 synergistically enhance IL-6 mRNA expression in FRTL-5 thyroid cells by mechanisms involving the cAMP/PKA pathway, and both stabilization of the IL-6 mRNA and activation of the IL-6 promoter. Point mutations or deletions of the main transcription factor binding sites in the IL-6 promoter indicated that the synergistic effect was mainly mediated by the AP-1 site, and that the CRE site contributed to this effect. The DNA binding activity of AP-1 transcription factors and the expression of c-Fos and Fra-2 proteins, were all enhanced when the cAMP and IL-1 signalling pathways were both stimulated. These findings contribute to elucidating the synergistic mechanisms that regulate IL-6 secretion by thyroid cells, and suggest that such mechanisms may be involved in the development of thyroid autoimmune disorders.

Co-expression of interleukin-6 (IL-6) and interleukin-6 receptor (IL-6R) in thyroid nodules is associated with co-expression of CD30 ligand/CD30 receptor

Data on the expression of interleukin 6 (IL-6)/interleukin 6 receptor (IL-6R) in thyroid nodules is scarce. Based on our recent data of CD30 ligand (CD30L)/CD30 receptor (CD30) in these nodules and on the knowledge that this signal stimulates IL-6 production in non-thyroid neoplasms, we wanted to evaluate the immunocytochemical expression of these 2 ligand/receptor systems in a large archival series of paraffin-embedded specimens. These specimens included 6 normal thyroids and 130 thyroid nodules. Co-expression of IL-6 and IL-6R in the epithelial (follicular) cells was observed solely in CD30L/CD30 positive nodules: 5/15 (33%) oncocytic adenomas; 6/30 (20%) follicular adenomas which belonged to 2 variants (4/4 microfollicular toxic and 2/2 hyalinizing trabecular); 9/30 (30%) papillary thyroid cancers (PTC), all belonging to the conventional variant. In PTC the proportion of tumor epithelial cells that were IL6 positive was inversely correlated with the pTNM staging (r=-0.549, p=0.01). All 15 follicular cancers (FTC), all 6 anaplastic cancers (ATC) were IL-6/lL-6R negative; 14/15 FTC and 5/6 ATC were CD30L/CD30 negative. In another oncocytic adenoma, another 4 conventional PTC and another 7 non-conventional PTC CD30L/CD30 expression was associated to expression of IL-6 only. IL-6 staining associated to absent expression of CD30L and CD30 was observed in 7 follicular adenomas (all belonging to variants different from toxic and hyalinizing trabecular), 2 oncocytic adenomas, 5 of the 30 colloid nodules and 2 normal thyroids. Of the 6 tumors arising from the parafollicular C cells (medullary thyroid cancer, MTC), all 3 that had metastasized were CD30L/CD30/IL-6 positive and IL-6R negative; only IL-6 expression was lost in both the local and distant metastases. This finding matched the loss of IL-6 expression in one PTC metastasis. All 3 non-metastasized MTC were IL-6/IL-6R negative, and 1/3 was CD30L positive/CD30 negative. We conclude that only in a subset of both benign and malignant thyroid nodules the IL-6/IL-6R signal could be induced by the CD30L/CD30. IL-6 expression is related with aggressiveness in both PTC and MTC. In the normal thyroid tissue, colloid nodules, and another subset of benign and malignant thyroid nodules, IL-6 expression is under control of signals other than CD30L/CD30.

Thyrotropin modifies activation of nuclear factor kappaB by tumour necrosis factor alpha in rat thyroid cell line

We have recently demonstrated that nuclear factor kappaB (NF-kappaB) mediates the tumour necrosis factor alpha (TNF-alpha)-dependent expression of the gene encoding interleukin 6 (IL-6) in rat thyroid FRTL-5 cells cultured in the presence of thyrotropin (TSH). In the present study we investigated how TSH is involved in the activation of NF-kappaB by TNF-alpha in the cells. Electrophoretic mobility-shift assay revealed that, in the absence of TSH, TNF-alpha activated a single protein-DNA complex containing the p50 subunit but not other NF-kappaB subunits such as p65. In contrast, two distinct protein-DNA complexes were activated in the presence of TSH: the faster-migrating complex contained only p50 subunit; the slower-migrating complex consisted of p65-p50 heterodimer. This TSH effect was mimicked by forskolin and thyroid-stimulating antibodies obtained from patients with Graves's disease, suggesting that an increase in intracellular cAMP is responsible for the induction of different NF-kappaBs by TNF-alpha. A transient transfection study with a luciferase reporter gene driven by multimerized NF-kappaB sites demonstrated that TNF-alpha increased the luciferase activities only in the presence of TSH, and that this increase was inhibited by the co-transfection of mutant p65, which prevented the function of wild-type p65 in a dominant-negative manner. Accordingly, TNF-alpha activated the expression of the IL-6 gene in the presence of TSH but not in its absence. Although the expression of the p105 gene, another known target for NF-kappaB, was increased by TNF-alpha in the absence of TSH, the presence of TSH further increased the mRNA level. Taken together, these observations indicate that the presence of TSH is crucial for the NF-kappaB-mediated actions of TNF-alpha on thyroid follicular cells.

Co-culture of human monocytes and thyrocytes in bicameral chamber: monocyte-derived IL-1alpha impairs the thyroid epithelial barrier

Pro-inflammatory cytokines are important mediators in tissue responses to a wide range of endogenous (e.g. autoantigens) and exogenous (e.g. infections, wounds, biomaterials) stimuli. The complex interactions taking place between different cell types in such processes are difficult to examine in vivo. Here we studied the effect of human monocytes on thyroid epithelial cells co-cultured in bicameral chambers. Freshly isolated monocytes (1x10(6)/ml) added to the basal compartment reduced the transepithelial resistance (from 300-600 to <100 Omega.cm(2)) and caused a disruption of the tight junctions in apically grown thyrocyte monolayers after co-culture for 24 h. The barrier function was further attenuated by monocytes exposed to lipopolysaccharide (10 microg/ml) or polystyrene microspheres (size: 3 microm; 1x10(7)/ml). Loss of transepithelial resistance was accompanied by release of interleukin 1alpha (maximally 550 pg/ml) from the monocytes. Conversely, the resistance remained high when co-cultures were simultaneously incubated with neutralizing anti-human interleukin 1alpha antibodies. The results show that the integrity of cultured thyroid epithelium is impaired by monocytes without requirement of direct cell-to-cell contact. This action, mediated by interleukin-1alpha, suggests a mechanism by which hidden (lumenal) autoantigens might be exposed to interstitial antigen-presenting cells in autoimmune thyroid disease. In perspective, the model provides a tool in which humoral and cell-cell dependent processes generated by bioactive agents and particulate materials, for instance, during the healing and repair of tissue around biomaterials and hybrid implants, can be selectively examined.

IL-10 expression in thyroid glands: protective or harmful role against thyroid autoimmunity?

IL-10 is a cytokine which not only suppresses cellular immunity but also stimulates the humoral response. In certain animal models of autoimmunity, IL-10 exerts a protective effect against autodestruction. This study was to ascertain whether there could be a role for IL-10 in human autoimmune thyroid disease. Total RNA was extracted from snap-frozen thyroid blocks from surgical specimens. Five 'normal', five multinodular, six Graves and two Hashimoto thyroids (one euthyroid and one hypothyroid) were studied. Approximately 7 microg of total RNA from each gland were reverse transcribed with oligo-dT primers. Pre-plateau semiquantitative polymerase chain reaction (PCR) was performed with specific IL-10 primers. PCR products were run on a 1-5% agarose gel, blotted onto a N-hybond nylon membrane, hybridized with a specific internal probe labelled with gamma-32P-ATP and autoradiographed. Statistical analysis of densitometric values showed significantly higher IL-10 levels in the autoimmune than in the non-autoimmune glands. In situ hybridization and immunohistochemistry showed that the IL-10 message was located within the infiltrating lymphomononuclear cells. Histological analysis revealed that the autoimmune thyroids with the highest IL-10 levels were characterized by relevant degrees of B and T cell infiltration and also exhibited the greatest percentage of spontaneous HLA class II expression on thyrocytes. IL-10 and neutralizing anti-IL-10 antibodies were not able to regulate in vitro spontaneous or interferon-gamma (IFN-gamma)/phytohaemagglutinin (PHA)-induced HLA class II on thyrocytes. We conclude that in active autoimmune thyroiditis, in addition to the well documented production of Th1 cytokines, Th2-related lymphokines can be detected simultaneously. It can be envisaged that in this condition the role of IL-10 might be directed to the stimulation of B cell proliferation and antibody production rather than to the suppression of proinflammatory cytokine release.

Cytokines and thyroid epithelial integrity: interleukin-1alpha induces dissociation of the junctional complex and paracellular leakage in filter-cultured human thyrocytes

Locally produced proinflammatory cytokines are likely to play a pathophysiological role in autoimmune thyroid disease. An important feature of the thyroid, not previously considered in cytokine actions, is the barrier created by the follicular epithelium, which secludes two lumenal autoantigens [thyroglobulin (Tg) and thyroperoxidase] from the extrafollicular space. We examined the influence of recombinant cytokines on the barrier function of human thyrocytes cultured as a tight and polarized monolayer in bicameral chambers. Whereas interleukin (IL)-6 (100 U/mL), interferon-gamma (100 U/mL), tumor necrosis factor-alpha (10 ng/mL), and transforming growth factor-beta1 (10 ng/mL) had no effects, exposure to IL-1alpha for 24-48 h reduced the transepithelial resistance from >1000 to <50 omega x cm2 and increased the paracellular flux of [3H]inulin and exogenous 125I-Tg. This response to IL-1alpha, which was dose dependent (1-1000 U/mL) and reversible, was accompanied by dramatic morphological changes of the epithelial junction complex, including aberrant localization of the tight junction protein zonula occludens-1. At the same time, IL-1alpha decreased the apical secretion of endogenous Tg and stimulated the basolateral release of a novel high-molecular-mass protein. We conclude that IL-1alpha reduces the thyroid epithelial barrier without signs of general cytotoxicity. The observation suggests a mechanism by which IL-1alpha may promote the exposure of hidden autoantigens to the immune system in thyroid autoimmunity.

Cytokines and Graves' disease

Cytokines are an extraordinarily diverse group of molecules, with pleiotropic and often overlapping effects. They are crucial to the autoimmune response, and, in particular, regulation of CD4+ and CD8+ T-cell function depends on the balance of cytokines produced during an immune response. It is also now clear that cytokines are produced by a wide array of cells, including the thyroid follicular cells (TFCs). Intrathyroidal lymphocytes produce a heterogeneous pattern of cytokines and we have summarized the likely effects of these. In Graves' disease, TFCs can themselves express immunologically important molecules as the result of cytokine stimulation and these could contribute to the perpetuation of the autoimmune process. In addition, cytokines have a number of generally inhibitory effects on thyroid hormone production which would tend to counter the stimulatory effects of thyroid-stimulating hormone receptor antibodies in Graves' disease.

The effects of interleukin-1beta (IL-1beta) on human thyrocyte functions are counteracted by the IL-1 receptor antagonist

The cytokine interleukin-1beta (IL-1beta) is an important regulator of thyroid cell function. IL-1 receptors are present on normal thyrocytes, but the signaling pathway is not fully clarified. As the adenylate cyclase is presumably not activated, we have in the present study investigated whether the cGMP pathway was involved in the actions of IL-1beta, whether the effects of IL-1beta on cultured human thyrocytes were reversible, and whether the effects were counteracted by IL-1 receptor antagonist (IL-1ra), a naturally occurring, specific blocker of IL-1 receptors on many cells. TSH-stimulated cultured human thyroid cells exposed for 72 h to IL-1beta (0.0002-20 microg/liter = 1-105 IU/liter) exhibited a dose-dependent and reversible inhibition of thyroglobulin and cAMP release and a dose-dependent stimulation of cGMP and IL-6 release. These effects were counteracted by coincubation with 250 or 125 microg/liter, but not with 25 and 2.5 microg/liter, IL-1ra. IL-1ra by itself inhibited the release of cAMP, but did not modulate the release of thyroglobulin, cGMP, or IL-6 from the thyrocytes, and IL-1ra was not produced in the extracellular compartment. The nitric oxide generator, sodium nitroprusside, dose dependently generated a TSH-independent release of nitric oxide and cGMP from the thyrocytes. These results indicate that all of the studied effects of IL-1beta on cultured human thyrocytes were exerted through activation of the IL-1 receptor with a signaling pathway involving activation of cGMP and inhibition of cAMP.

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.

Immunocytochemical localisation of tumor necrosis factor alpha in thyroid tissues from patients with neoplastic or autoimmune thyroid disorders

It is disputed to what extent tumor necrosis factor-alpha is present in the thyroid follicular epithelial cells and/or in the interstitial cells in different disorders of the thyroid gland. We describe the immunohistochemical detection of tumor necrosis factor-alpha using formaldehyde fixed and paraffin embedded tissue and a polyclonal anti-serum with high tumor necrosis factor-alpha neutralising activity. We examined the distribution of tumor necrosis factor-alpha in interstitial cells and follicular epithelial cells in thyroid carcinomas, adenomas, non-toxic multinodular goiters and autoimmune thyroid diseases. Tumor necrosis factor-alpha was demonstrated in thyroid follicular epithelial cells, most frequently in non-toxic multinodular goiters (six of seven patients) and less frequently in adenomas (three of nine patients), papillary carcinomas (two of five patients), follicular carcinomas (one of five patients), Hashimoto's disease (one of six patients) and Grave's disease (one of seven patients). Tumor necrosis factor-alpha producing interstitial cells were found in two thirds of patients with all six thyroid diseases.

Effects of tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 on type I iodothyronine 5'-deiodination in rat thyroid cell line, FRTL-5

Using a functioning rat thyroid cell line (FRTL-5), we studied the effects of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6) on thyroidal type I iodothyronine 5'-deiodination (I-5'-deiodination) and on the expression of I-5'-deiodinase (I-5'-D) mRNA. After 24 h incubation in medium containing 0.5 microM rT3 with a tracer amount of [125I]rT3, radioactivity of released 125I- was counted. Deiodination in live FRTL-5 cells was enhanced about three times from the basal level by the addition of TSH and was inhibited markedly by propylthiouracil and dose dependently by T4. These results suggest the suitability of this model for investigating I-5'-deiodination in live thyroid tissue. Basal and TSH-induced I-5'-deiodination were significantly inhibited by 100 ng/liter of IL-1 beta and IL-6, and the inhibitory effect of TNF-alpha was seen over 1 microgram/liter. I-5'-deiodination was restored by removal of the cytokines. TSH-induced cAMP production and (Bu)2cAMP-induced I-5'-deiodination were also inhibited by the cytokines. Catalase, dexamethasone, and indomethacin did not abolish the inhibitory effects of the cytokines. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed a marked suppression of I-5'-D mRNA expression by IL-1 beta and IL-6. We conclude that these cytokines inhibit the thyroidal type I I-5'-deiodination in the order of potency IL-1 beta > IL-6 >> TNF-alpha, probably by decreasing the I-5'-D mRNA level.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical localisation of interleukin-1 alpha and interleukin-6 in thyroid tissues from patients with neoplastic or autoimmune thyroid disorders

We describe the distribution of interleukin-6 and interleukin-1 alpha in thyroid tissues obtained from patients with autoimmune diseases or neoplastic thyroid disorders employing immunohistochemistry in sections from paraffin embedded tissue blocks. Interleukin-6 was found in thyroid follicular epithelial cells (TFEC) from papillary carcinomas (four of five patients) but not in follicular carcinomas (five patients). Interleukin-6 was also detected in non-toxic multinodular goiters (four of seven patients), in patients with Graves' disease who did not have an early recurrence of hyperthyroidism after surgery (three of four patients), in follicular adenomas (five of nine patients), in Hashimoto's thyroiditis (two out of six patients, both belonging to a group of three with an early stage of the disease), and in paraadenomatous tissues (in three of nine patients). Interleukin-1 alpha positive TFEC were found less frequently than interleukin-6, and only in tissues with interleukin-6 positive TFEC. Only few interleukin-6 and interleukin-1 alpha positive interstitial cells were found, even in the lymphocyte infiltrates (in both the autoimmune, benign or malignant disorders). In conclusion, both interleukin-6 and interleukin-1 alpha could be demonstrated in TFEC from patients with autoimmune diseases, benign neoplasms or papillary carcinoma, whereas follicular cancer tissues were without interleukin-6 and interleukin-1 alpha. In contrast with previous studies, interleukin-6 and interleukin-1 alpha were demonstrated in TFEC from patients with both Graves' disease and Hashimoto's thyroiditis, and the presence of these cytokines was related to the stage of the autoimmune process.

The cytokines, interleukin-1 beta, interleukin-6 and interferon-gamma upregulate the expression of intercellular adhesion molecule-1(ICAM-1) in rat thyroid cell line, FRTL-5

OBJECTIVES

Recently, the role of adhesion molecules in the immune system has been recognized. ICAM-1 plays an important role in a variety of inflammatory and immune mediated mechanisms, including recruitment and targeting of lymphocytes. We observed the effects of cytokines on expression of rat homologue of human intercellular adhesion molecule-1 in rat thyroid cell line, FRTL-5.

METHODS

We have examined expression of rat intercellular adhesion molecule-1 (ICAM-1, CD54), a homologue of human intercellular adhesion molecule-1, by immunocytochemistry (immunoperoxidase staining) in the continuously growing rat thyroid cell line, FRTL-5.

RESULTS

Low level of ICAM-1 expression was noted at basal condition and this basal expression was not influenced by thyrotropin. Expression in rat homologue of ICAM-1 is increased by interferon-gamma, interleukin-1 beta and interleukin-6 with a dose dependent manner.

CONCLUSION

These results show that a pure line of rat thyroid cells can express an ICAM-1 homologue and this is directly enhanced by cytokines such as rat interferon-gamma, human interleukin-1 beta and interleukin-6. Expression of this homologue is partially responsible for lymphocyte adhesion to thyroid cells, which is likely to be a major event in T cell recognition of thyroid antigens in autoimmune thyroiditis.

Autocrine growth factors produced in the thyroid

This catalogue of autocrine growth factors is limited to proteins--metabolites of iodine and prostaglandins are omitted and they are undoubtedly of autocrine importance in the thyroid, as elsewhere. However, this summary of polypeptide growth factors secreted by the thyroid illustrates the potential cells have to condition their environment to modify their responses to external stimuli. This enables cells in different tissues to respond to agonists in different ways. The effects of TSH on IGF, IGFBP and IGF receptor production and the effects of IGFBPs on IGF action are good examples of this amplified response. Many pieces of the jigsaw, however, remain to be found and put in place before a clear picture of the regulation and roles of these factors can be made.

Nitric oxide production is not involved in the effects of interleukin-1 beta on cAMP, thyroglobulin and interleukin-6 in TSH-stimulated human thyroid cells

Interleukin (IL)-1 inhibits the function of insulin-producing rat pancreatic beta-cells in vitro and in vivo, and it has been postulated that the IL-1 effect is mediated through the cytokine inducible nitric oxide (NO) synthase. IL-1 inhibits the function of cultured human thyroid cells too, and in this study human thyroid cell production of NO in response to the TSH-stimulated influence of IL-1 beta (10(5) U/l) and TNF-alpha (10(6) U/l), alone or in combination was measured. IL-1 beta, but not TNF-alpha, induced an increase in nitrite production, which was significantly reduced by the competitive inhibitor of nitric oxide synthase L-NG-monomethyl-arginine (L-NMMA) (0.1 mmol/L and 0.5 mmol/L). However, the nitrite production was unrelated to the IL-1 beta-induced inhibition of thyroglobulin (Tg) and cyclic AMP (cAMP) and the IL-1 beta-induced IL-6 production. Thus, it is unlikely that NO is a second mediator of the demonstrated effects of IL-1 beta and TNF-alpha on human thyroid cells in culture.

The effect of interleukin-1 on the thyroid gland

The inhibitory effect of interleukin (IL)-1 on thyroid cell functions, including cAMP and thyroglobulin production, is well documented. Recently, IL-1 was shown to enhance the production of IL-6 from thyrocytes, and IL-1 receptors were demonstrated on normal thyroid cells. The origin of IL-1 could be from infiltrating monocytes/-macrophages, endothelial cells as well as from the thyrocytes themselves. Thus, IL-1 activated thyrocyte may participate directly in the immunological process by reacting to and producing immunoinflammatory cytokines.