Amiodarone stimulates interleukin-6 production in cultured human thyrocytes, exerting cytotoxic effects on thyroid follicles in suspension culture

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

Amiodarone-induced thyrotoxicosis: state of the art

В обзоре представлены данные литературы последних лет о патогенезе, диагностике, лечении амиодарон-индуцированного тиреотоксикоза (АИТ), который является частым осложнением терапии амиодароном (Ам). Описаны изменения секреции и метаболизма тиреоидныхгомонов под влиянием кратковременной и длительной терапии Ам. Развитие АИТ всегда приводит к ухудшению течения аритмии, усугублению недостаточности кровообращения, утяжелению состояния пациента. Выделяют АИТ 1 типа и АИТ 2 типа, а также смешанную форму. Описаны диагностические критерии АИТ 1 и 2 типа. Наиболее информативным тестом для дифференциальной диагностики АИТ 1, 2 типов и смешанных форм является сонография щитовидной железы с допплеровским исследованием кровотока и сканирование с 99mTc-sestaMIBI. Тактика лечения определяется типом АИТ, состоянием сердечно-сосудистой системы, риском повторных аритмий. Консервативное лечение зависит от типа АИТ и осуществляется тиреостатиками или глюкокортикоидами. Обсуждается возможность продолжения антиаритмической терапии Ам у пациентов, перенесших АИТ. При АИТ 1 типа и смешанной форме требуется отмена препарата, если это невозможно – радикальное лечение тиреотоксикоза (радиойодтерапия, тиреоидэктомия). АИТ 2 типа является самолимитирующимся процессом, при жизненно угрожающих аритмиях прием Ам может быть продолжен. Показана эффективность радиойодтерапии для радикального лечения тиреотоксикоза при АИТ 1 и 2 типа, несмотря на низкий захват радиойода. Однако этот вопрос требует дальнейшего изучения и обсуждения. Для быстрого восстановления эутиреоза у тяжелых больных применяют плазмаферез и тиреоидэктомию.

Cytokines in Endocrine Dysfunction of Plasma Cell Disorders

Monoclonal gammopathies (MG) are classically associated with lytic bone lesions, hypercalcemia, anemia, and renal insufficiency. However, in some cases, symptoms of endocrine dysfunction are more prominent than these classical signs and misdiagnosis can thus be possible. This concerns especially the situation where the presence of M-protein is limited and the serum protein electrophoresis (sPEP) appears normal. To understand the origin of the endocrine symptoms associated with MG, we overview here the current knowledge on the complexity of interactions between cytokines and the endocrine system in MG and discuss the perspectives for both the diagnosis and treatments for this class of diseases. We also illustrate the role of major cytokines and growth factors such as IL-6, IL-1β, TNF-α, and VEGF in the endocrine system, as these tumor-relevant signaling molecules not only help the clonal expansion and invasion of the tumor cells but also influence cellular metabolism through autocrine, paracrine, and endocrine mechanisms. We further discuss the broader impact of these tumor environment-derived molecules and proinflammatory state on systemic hormone signaling. The diagnostic challenges and clinical work-up are illustrated from the point of view of an endocrinologist.

Administration of amiodarone during resuscitation is associated with higher tumor necrosis factor-α levels in the early postarrest period in the swine model of ischemic ventricular fibrillation

To compare the early postarrest inflammatory cytokine response between animals administered amiodarone (AMIO) and lidocaine (LIDO) intra-arrest during resuscitation from ventricular fibrillation (VF). Domestic swine (n=32) were placed under general anesthesia and instrumented before spontaneous VF was induced by balloon occlusion of the left anterior descending coronary artery. After 7 min of VF, standard ACLS resuscitation was performed and animals were randomized to either bolus AMIO (5 mg/kg, n=13) or LIDO (1 mg/kg, n=14) for recurrent or refractory VF. A non-antiarrhythmic (n=5) was also used for comparison. Following return of spontaneous circulation (ROSC), tumor necrosis factor (TNF)-α levels were drawn at 30 and 60 min. Groups were comparable with respect to prearrest hemodynamics and resuscitation variables. In the postarrest period, the LIDO and non-antiarrhythmic group demonstrated virtually identical TNF-α response trajectories. However, TNF-α levels were significantly higher in AMIO- than LIDO-treated animals at 30 min (geometric mean 539 versus 240 pg/mL, 2.2-fold higher, 95% confidence interval [CI] 1.3-3.8-fold higher, P=0.003) and at 60 min (geometric mean 570 versus 204 pg/mL, 2.8-fold higher, 95% CI 1.1-7.0-fold higher, P=0.03). Significant differences in the postarrest TNF-α levels were observed between animals treated with AMIO as compared to those treated with LIDO. Improved rates of ROSC seen with AMIO may come at the expense of a heightened proinflammatory state in the postcardiac arrest period.

Amiodarone-induced thyrotoxicosis in children and adolescents is a possible outcome in patients with low iodine intake

BACKGROUND/OBJECTIVE

The identification of the different subtypes of amiodarone-induced thyrotoxicosis (AIT) may provide a rational basis for the choice of the appropriate medical treatment. The aim of this study was to evaluate differential diagnosis and treatment regimens of AIT in children and adolescent.

PATIENTS

We reported 3 patients: A 6.7 years old boy with type I AIT; a 17.9 years old girl with type II AIT and a 14.6 years old girl with mixed type AIT.

CONCLUSIONS

AIT is not an uncommon complication in countries with low iodine intake. AIT can be asymptomatic and can occur at any time in patients receiving amiodarone therapy. It is also very important to distinguish the type of AIT when planning therapy. Steroid therapy should be started when findings indicate type II or mixed-type AIT. Beta blockers may prevent heart thyrotoxicosis and recurrence of primary arrhythmia if amiodarone is discontinued.

Iodide-induced chemokines and genes related to immunological function in cultured human thyroid follicles in the presence of thyrotropin

BACKGROUND

It is well known that iodide exacerbates thyroid function in subclinical hypothyroid patients with autoimmune thyroiditis. To investigate the immunological mechanism of iodine-induced thyroid dysfunction, we studied the effect of iodide in cultured human thyroid follicles, which respond to physiological concentrations of human thyrotropin (TSH) (0.3-10 microU/mL) and maintain the Wolff-Chaikoff effect.

MATERIALS AND METHODS

Thyroid follicles obtained from Graves' patients at subtotal thyroidectomy were precultured in medium containing 0.5% fetal calf serum and 10(-8) M iodide for 5 days, and then cultured with the medium containing bovine TSH (30 microU/mL) and low (10(-8)M) or high (10(-5)M) concentrations of iodide. After 3-72 hours of culture, the effect of iodide on thyroid cell mRNA expression was analyzed by microarray and reverse transcriptase-polymerase chain reaction.

RESULTS

After 48 hours of culture, iodide nearly doubled the mRNA expression levels of the immunity-associated genes (intercellular adhesion molecule-1, transforming growth factor beta 1-induced protein, early growth response gene 1, guanylate-binding protein 1, and annexin A1) and decreased the mRNA expression of sodium-iodide symporter to less than 20%. Further, the mRNA expression levels of chemokines (CCL2, CXCL8, and CXCL14) increased nearly twofold, whereas their receptors did not show any significant response. Real-time polymerase chain reaction analyses confirmed that iodide increased the mRNA expression levels of these genes in a time- and concentration-dependent manner. Immunohistochemical studies revealed that the chemokines were expressed mainly in the thyroid follicular cells in addition to the immune cells. The iodide-induced increase in CCL2 was greater in thyroid follicles obtained from thyroid gland that had been moderately infiltrated with the immunocompetent cells.

CONCLUSION

We have demonstrated that iodide stimulates thyroid follicular cells to produce chemokines, particularly CCL2, CXCL8, and CXCL14. These chemokines and intercellular adhesion molecule-1 would attract immunocompetent cells into thyroid gland. These in vitro findings suggest that iodide at high concentrations may induce thyroid dysfunction through not only biochemical but also immunological mechanisms, particularly in patients with autoimmune thyroid disorders.

Short-term amiodarone treatment attenuates the production of monocyte cytokines and chemokines by C-reactive protein and improves cardiac function in patients with idiopathic dilated cardiomyopathy and ventricular tachycardia

BACKGROUND

Increased expression of cytokines and chemokines has been observed in chronic heart failure (CHF). Amiodarone reduces circulating cytokine levels, so it may attenuate the production of monocyte cytokines and chemokines by C-reactive protein (CRP) and thus improve the left ventricular ejection fraction (LVEF) in dilated cardiomyopathy (DCM) patients with ventricular tachycardia (VT).

METHODS AND RESULTS

Peripheral blood mononuclear cells (PBMCs) were stimulated by 25 microg/ml CRP in 23 patients with DCM, who were divided into 2 groups based on whether or not amiodarone was included in their treatment (Amiodarone group n=8; No amiodarone group n=15). Tumor necrosis factor (TNF)-alpha and monocyte chemoattractant protein (MCP)-1 on monocytes at baseline and after 4 weeks of treatment was measured by ELISA and expressed as mean+/-SD (pg.ml(-1)x10(-6) PBMCs). The LVEF and the CRP-induced monocyte cytokine and chemokine production were unchanged in the No amiodarone group after 4 weeks; however, LVEF in the Amiodarone group was increased (32.7+/-6.9 to 39.2+/-6.9%; P=0.005), and TNF-alpha and MCP-1 production in the Amiodarone group were decreased (P=0.012, respectively).

CONCLUSIONS

Amiodarone attenuates the production of monocyte cytokines and chemokines by CRP, and improves LVEF in CHF patients with VT.

[Thyroid and treatment with amiodarone diagnosis, therapy and clinical management]

Amiodarone is a frequently used antiarrhythmic drug with a high antiarrhythmic potency. However, beside its antiarrhythmic effects Amiodarone also reveals a variety of adverse effects and drug-related complications. The affected organs include the eyes, skin, lungs, nervous system, liver, gastrointestinal tract and the thyroid. The thyroid is one of the most frequently affected organs by Amiodarone. An altered hormone equilibrium always occurs and has to be distinguished from Amiodarone induced hyperthyroidism and hypothyroidism. The differentiation of these states frequently causes problems and may even be a diagnostic and therapeutic challenge in certain cases. The article gives an overview on the interactions between Amiodarone and the thyroid, the diagnostic and therapeutic options and management strategies of patient on Amiodarone therapy in the view of thyroid function.

Amiodarone reversibly decreases sodium-iodide symporter mRNA expression at therapeutic concentrations and induces antioxidant responses at supraphysiological concentrations in cultured human thyroid follicles

CONTEXT

Amiodarone, a potent antiarrhythmic, iodine-containing agent, is a highly active oxidant exerting cytotoxic effects on thyrocytes at pharmacological concentrations. Patients receiving amiodarone usually remain euthyroid, but occasionally develop thyroid dysfunction. Although there is a general consensus that amiodarone-associated hypothyroidism is iodine induced, the destructive mechanism of thyroid follicles in amiodarone-induced thyrotoxicosis remains unknown.

OBJECTIVE

To elucidate the mechanism by which amiodarone elicits thyroid dysfunction.

DESIGN

Human thyroid follicles were cultured with thyroid-stimulating hormone (TSH) and amiodarone at therapeutic (1-2 microM) and pharmacological (10-20 microM) concentrations, and the drug-induced effect on whole human gene expression was analyzed by cDNA microarray. Microarray data were confirmed by real-time PCR and Western blot.

MAIN OUTCOMES

Amiodarone at 1-2 muM decreased the expression level of the sodium-iodide symporter (NIS) to nearly half, but did not affect genes participating in thyroid hormonogenesis (thyroid peroxidase, thyroglobulin, pendrin, and NADPH oxidase). Higher concentrations (10-20 microM) decreased the expression of all these genes, accompanied by increased expression of antioxidant proteins such as heme oxygenase 1 and ferritin. When thyroid follicles obtained from a patient with Graves' disease who had been treated with amiodarone were cultured in amiodarone-free medium, TSH-induced thyroid function was intact, suggesting that amiodarone at a maintenance dose did not elicit any cytotoxic effect on thyrocytes. The ultrastructural features of cultured thyroid follicles were compatible with these in vitro findings.

CONCLUSION

These in vitro and ex vivo findings suggest that patients taking maintenance doses of amiodarone usually remain euthyroid, probably due to escape from the Wolff-Chaikoff effect mediated by decreased expression of NIS mRNA. Further, amiodarone is not cytotoxic for thyrocytes at therapeutic concentrations but elicits cytotoxicity through oxidant activity at supraphysiological concentrations. We speculate that when amiodarone-induced prooxidant activity somehow exceeds the endogenous antioxidant capacity, the thyroid follicles will be destroyed and amiodarone-induced destructive thyrotoxicosis may develop.

Suppression of iodide uptake and thyroid hormone synthesis with stimulation of the type I interferon system by double-stranded ribonucleic acid in cultured human thyroid follicles

Although viral infection is thought to be associated with subacute thyroiditis and probably with autoimmune thyroid disease, possible changes in thyroid function during the prodromal period of infection or subclinical infection remain largely unknown. Recently, it was shown that pathogen-associated molecular patterns stimulate Toll-like receptors (TLR) and activate innate immune responses by producing type I interferons (IFN). Using a human thyroid follicle culture system, in which de novo synthesized thyroid hormones are released into the culture medium under physiological concentrations of human TSH, we studied the effects of polyinosinic-polycytidylic acid [Poly(I:C)], a chemical analog of viral double-stranded RNA (dsRNA), on TSH-induced thyroid function. Thyrocytes expressed ligands for dsRNA (TLR 3, CD14, and retinoic-acid-inducible protein-1) comparable with the TSH receptor. DNA microarray and real-time PCR analyses revealed that dsRNA increased the expression of mRNA for TLR3, IFN-beta, IFN-regulating factors, proinflammatory cytokines, and class I major histocompatibility complex (MHC), whereas genes associated with thyroid hormonogenesis (sodium/iodide symporter, peroxidase, deiodinases) were suppressed. In accordance to these data, Poly(I:C) suppressed TSH-induced 125I uptake and hormone synthesis dose dependently, accompanied by a decrease in the ratio of 125I-T3/125I-T4 released into the culture medium, whereas peptidoglycan, lipopolysaccharides, or unmethylated CpG DNA, ligands for TLR2, TLR4, and TLR9, respectively, had no significant effect. These inhibitory effects of Poly(I:C) were not blocked by a neutralizing antibody against TLR3 and an anti-IFN alpha/beta receptor antibody. These in vitro findings suggest that when thyrocytes are infected with certain viruses, dsRNA formed intracellularly in thyrocytes may be a cause for thyroid dysfunction, leading to development of autoimmune thyroiditis.

Mild and short recurrence of type II amiodarone-induced thyrotoxicosis in three patients receiving amiodarone continuously for more than 10 years

Although there are two types of amiodarone-induced thyrotoxicosis (AIT), only type II AIT has been seen at our institution in Japan so far. There have been few case reports of AIT recurrence, probably because of the fact that amiodarone is immediately discontinued once AIT has developed. Our own policy is not to discontinue amiodarone in all AIT patients, unless severe adverse effects such as pulmonary fibrosis develop. Among more than 50 patients with type II AIT we have encountered, three with arrhythmogenic right ventricular cardiomyopathy showed AIT recurrence. In these patients, the first episode of AIT developed 3, 4, and 2 years after the start of amiodarone administration, and recurrence was observed 5, 6, and 8 years after the first episode, respectively. The AIT resolved spontaneously in all cases while the patients continued to take amiodarone. In comparison with the first AIT episode, the second was milder and resolved within a shorter period. These three cases suggest that recurrence of type II AIT may not be rare in iodine-sufficient areas, and that it is relatively mild and may resolve spontaneously. Furthermore, at least in Japan, it may be possible for patients with recurrent type II AIT to continue taking amiodarone.

Iodide inhibits vascular endothelial growth factor-A expression in cultured human thyroid follicles: a microarray search for effects of thyrotropin and iodide on angiogenesis factors

OBJECTIVE

Excess iodide has been administered to hyperthyroid patients before thyroid surgery to reduce intraoperative bleeding and oozing. The purpose of this study was to elucidate the mechanism by which iodide reduces blood flow in the hypervascular thyroid gland.

DESIGN

Human thyroid follicles were cultured in the presence or absence of thyrotropin (TSH), or in medium containing various concentrations of iodide, and TSH-or iodide-regulated gene expression was analyzed by cDNA microarray.

MAIN OUTCOME

TSH stimulated the expression of thyroglobulin, peroxidase, sodium iodide symporter, vascular endothelial growth factor (VEGF)-A, VEGF-B, and placental growth factor (PGF) but decreased that of VEGF-C by half. When thyroid follicles were cultured in high-iodide (10(5) M) medium, TSH-induced expression of VEGF-A, VEGF-B, and PGF was decreased, accompanied by a reduction of VEGF-A release into the medium. Furthermore, expression of putative angiogenesis inhibitors such as urokinase-type plasminogen activator (PLAU) was increased. These findings were confirmed by real-time polymerase chain reaction (PCR) and Northern blot hybridization.

CONCLUSIONS

We have demonstrated for the first time that iodide at high concentration decreases the expression of the angiogenic factors VEGF-A, VEGF-B, and PGF, accompanied by an increase in the expression of possible antiangiogenic factors such as PLAU. These proangiogenic and antiangiogenic factors may at least partly account for the iodide-induced decrease in thyroid blood flow.

Clinical, biochemical and therapeutical aspects of amiodarone-induced hypothyroidism (AIH) in geriatric patients with cardiac arrhythmias

The clinical features and the laboratory aspects of the amiodarone-induced hypothyroidism (AIH) in the elderly as well as the effects of amiodarone treatment in aged AIH people have not yet been well clarified. In the present paper, we evaluated 18 subjects of both sexes (7 females, 11 males), aged 65-83 years, affected by AIH, recruited in Central Tuscany, Italy. The patients were divided in two subsets on the basis of thyroid stimulating hormone (TSH) values: mild (TSH < 20 mU/l; Group A, n=11) and severe (TSH > 20 mU/l; Group B, n=7) hypothyroid patients. On the basis of clinical features, hypothyroidism was diagnosed only in two patients (out of Group B). Concerning the hormonal pattern, we found that free tetraiodothyronine (fT4) levels were significantly lower than the normal range only in Group B subjects; TSH and thyroglobulin were higher than normal in both groups; free triiodothyronine (fT3) were always in the normal range. Thyroid autoantibodies were found positive only in one patient out of Group A and in two patients out of Group B. In 5/18 patients T4 substitutive therapy was rapidly assigned, because of severe degree of hypothyroidism. In the remaining 13/18 patients, we evaluated the clinical behavior of AIH. After additional cardiac evaluation, amiodarone was withdrawn in 5/13 patients: during follow-up period (4-10 months) four patients became quickly euthyroid while one worsened. In 8/13 patients, amiodarone treatment had to be carried on; during follow-up (2-48 months), four patients remained mildly hypothyroid, while other four patients became severely hypothyroid. In conclusion, in amiodarone treated elderly people, diagnosis of hypothyroidism is reliable only on the basis of high values of TSH; clinical features and fT3 serum levels never enable diagnosis.

Stimulation of cellular prion protein expression by TSH in human thyrocytes

The cellular isoform of prion protein (PrP(C)) is a cell-surface glycosyl-phosphatidylinositol-anchored protein which is ubiquitously expressed on the cell membrane. It may function as a cell receptor or as a cell adhesion molecule. Thyroid follicles, obtained from patients with Graves' disease at thyroidectomy, were cultured in F-12/RPMI-1640 medium supplemented with 0.5% fetal bovine serum and bovine thyroid stimulating hormone (bTSH). Northern blot analyses revealed that bTSH increased the steady-state expression levels of PrP mRNA in a time- and dose-dependent manner. This increase was reproduced by dibutyryl-cAMP and 12-decanoylphorbol-13-acetate. The mRNA expression was greater in thyroid follicles in suspension culture than in thyrocytes cultured in a monolayer. These findings suggest that TSH stimulates PrP mRNA expression in thyrocytes through the protein kinase A and C pathways. The greater mRNA expression in thyroid follicles than in monolayer cells suggests that PrP(C) may be involved in structure formation or maintenance of thyroid follicles.

Genes regulated by thyrotropin and iodide in cultured human thyroid follicles: analysis by cDNA microarray

Thyrotropin (TSH) regulates a number of genes in thyrocytes, leading to iodide uptake, de novo synthesis and release of thyroid hormones, and cell proliferation, accompanied by increased blood flow. At higher doses of iodide, however, the TSH-induced increases in thyroid hormone release and blood flow are downregulated, and high iodide intake occasionally worsens autoimmune thyroiditis. To elucidate the genes involved in such effects, we cultured human thyrocytes and examined genes modulated by TSH and iodide, using a cDNA microarray study, which can analyze 2400 genes in each run. When thyroid follicles were cultured with TSH for 2 days, more than 100 genes were upregulated. These genes included those for enzymes involved in carbohydrate and lipid metabolism, adenylate and guanylate cyclases, and enzyme involved in cell proliferation. When thyroid follicles were cultured with high iodide concentrations (10(-5) M) for 24 hours, more than 100 genes were upregulated. Interesting genes were interleukin-8, IFP53, 90-kd heat shock protein, osteopontin, and intercellular adhesion molecule-1. These results were confirmed by reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot hybridization. In summary, TSH upregulated a number of genes regulating thyroid functions. It is intriguing that thyroid follicles cultured with a high iodide concentration (10(-5) M) increased the expression levels of genes capable of modulating lymphocyte functions, even though immunocompetent cells were extensively removed by the present experimental culture conditions. Although we have analyzed only approximately 6%-8% of all human genes, the cDNA microarray study is a powerful tool to elucidate the effects of TSH and iodide on thyroid function.