Increased serum interleukin-6 concentration in patients with subacute thyroiditis: relationship with concomitant changes in serum T4-binding globulin concentration

Illustration of Gut-Thyroid Axis in Alcohol Use Disorder: Interplay of Gut Dysfunction, Pro-Inflammatory Responses, and Thyroid Function

(1) Background: Heavy and chronic alcohol drinking leads to altered gut dysfunction, coupled with a pro-inflammatory state. Thyroid-associated hormones and proteins may be dysregulated by heavy and chronic alcohol intake; however, the mechanism for altered gut-derived changes in thyroid function has not been studied thus far. This study investigates the role of alcohol-induced gut dysfunction and pro-inflammatory cytokine profile in the thyroid function of patients with alcohol use disorder (AUD). (2) Methods: Male and female AUD patients (n = 44) were divided into Gr.1, patients with normal thyroid-stimulating hormone (TSH) levels (n = 28, 0.8 ≤ TSH ≤ 3 mIU/L); and Gr.2, patients with clinically elevated TSH levels (n = 16, TSH > 3 mIU/L). Demographics, drinking measures, comprehensive metabolic panels, and candidate thyroid markers (TSH, circulating triiodothyronine (T3), and free thyroxine (fT4)) were analyzed. Gut-dysfunction-associated markers (lipopolysaccharide (LPS), LPS-binding protein (LBP), and soluble LPS-induced pathogen-associated protein (sCD14)), and candidate pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-8, MCP-1, PAI-1) were also evaluated. (3) Results: Patients in both groups presented with a borderline overweight BMI category. Gr.2 reported numerically higher indices of chronic and heavy drinking patterns than Gr.1. The fT4 levels were elevated, while T3 was within normal limits in both groups. The gut dysfunction markers LBP and sCD14 were numerically elevated in Gr.2 vs. Gr.1, suggesting subtle ongoing changes. Candidate pro-inflammatory cytokines were significantly elevated in Gr.2, including IL-1 β, MCP-1, and PAI-1. Gr.2 showed a strong and statistically significant effect on the gut–immune–thyroid response (r = 0.896, 36 p = 0.002) on TSH levels in a multivariate regression model with LBP, sCD14, and PAI-1 levels as upstream variables in the gut–thyroid pathway. In addition, AUROC analysis demonstrated that many of the cytokines strongly predicted TSH in Gr.2, including IL-6 (area = 0.774, 39 p < 0.001) and TNF-α (area = 0.708, p = 0.017), among others. This was not observed in Gr.1. Gr.2 demonstrated elevated fT4, as well as TSH, which suggests that there was subclinical thyroiditis with underlying CNS dysfunction and a lack of a negative feedback loop. (4) Conclusions: These findings reveal the toxic effects of heavy and chronic drinking that play a pathological role in thyroid gland dysregulation by employing the gut–brain axis. These results also emphasize potential directions to carefully evaluate thyroid dysregulation in the overall medical management of AUD.

The Old and the New in Subacute Thyroiditis: An Integrative Review

Subacute thyroiditis (SAT) is the most common cause of neck pain and thyrotoxicosis. Although this disease was recognized already by the end of the 18th century, new concepts regarding pathogenesis have emerged in recent years. Moreover, in the last two years, literature on SAT has increased significantly due to articles describing the possible connection with coronavirus disease 2019 (COVID-19). This integrative review depicts old and new concepts of this disease, proposing a detailed overview of pathogenesis, a practical approach to diagnosis and treatment, and a thorough description of the latest discoveries regarding the association of SAT with COVID-19.

Evaluation of interleukin-29 in autoimmune and inflammatory thyroid diseases

OBJECTIVE

Interleukins play an important role in the development of autoimmune disorders. The aim of this study was to compare the concentration of interleukin-29 (IL-29) between healthy controls (CS) and patients with selected thyroid disorders: Graves' disease (GD), Hashimoto's thyroiditis (HT) and subacute thyroiditis (SAT).

DESIGN AND METHODS

The following parameters were examined in the group of 95 individuals (45 with GD, 22 with HT, 28 with SAT) and 72 CS: thyroid hormones and autoantibodies, inflammatory markers and the concentration of IL-29 in serum.

RESULTS

The concentration of IL-29 in the GD subgroup was higher than that in the CS subgroup [264.0 (62.5-1018.0) vs. 62.5 (62.5-217.0) pg/mL, P = .001]. We found no differences in IL-29 concentrations between the CS and HT or SAT subgroups. Multivariable linear regression analysis indicated that IL-29 was a statistically significant independent predictor of GD presence (r = 0.24; P = .003) after adjustment for TRAb (R2  = 0.45; P < .001). The ROC analysis of IL-29 at GD diagnosis revealed an IL-29 cut-off of 123 pg/mL (sensitivity: 0.689 and specificity: 0.625) as the best value, which significantly indicated the presence of GD [area under the ROC curve (AUC): 0.676; 95% confidence interval (CI): 0.574-0.778, P < .001].

CONCLUSION

This is the first study to demonstrate elevated IL-29 serum levels in patients with GD. Our results suggest that IL-29 might be engaged in one of the pathogenetic pathways of GD, but no HT and SAT. Future studies are required to evaluate the potential of the protein as a therapeutic target in GD.

Hepcidin and Iron Homeostasis in Patients with Subacute Thyroiditis and Healthy Subjects

Purpose

Hepcidin is an acute-phase protein involved also in regulation of iron homeostasis. The aim of the study was to prospectively assess for the first time the hepcidin_EL concentration in patients with subacute thyroiditis (SAT), to identify biochemical determinants of hepcidin_EL concentration and evaluate the potential role of hepcidin in SAT diagnosis and monitoring.

Methods

Out of 40 patients with SAT initially recruited, restrictive inclusion criteria fulfilled 21 subjects aged 45 ± 10 years and 21 healthy control subjects (CS). Hepcidin_EL concentration, thyroid status, and iron homeostasis were evaluated at SAT diagnosis and following therapy and compared with CS.

Results

The median hepcidin_EL concentration at SAT diagnosis is higher than that in CS (48.8 (15.9-74.5) ng/mL vs. 18.2 (10.2-23.3) ng/mL, p = 0.009) and is significantly lower after treatment (4.0 (1.2-10.0) ng/mL, p = 0.007) compared with CS. The ROC analysis for hepcidin_EL at SAT diagnosis revealed that area under the curve (AUC) is 0.735 (p = 0.009), and the cut-off for hepcidin_EL concentration is 48.8 ng/mL (sensitivity 0.52 and specificity 0.95). Hepcidin_EL in SAT patients correlated with CRP (r = 0.614, p = 0.003), ferritin (r = 0.815, p < 0.001), and aTPO (r = -0.491, p = 0.024). On multiple regression, the correlation between hepcidin_EL and ferritin was confirmed (p < 0.001).

Conclusions

SAT is accompanied by a significant increase in hepcidin, which reflects an acute-phase inflammatory process. Parameters of iron homeostasis improved significantly while inflammatory indices got lower following recovery. The potential role of hepcidin as a predictive factor of the risk of SAT relapse needs to be assessed in studies on larger groups of SAT patients.

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.

Sustained high levels of serum leptin rather than IL-6 observed in patients with postpartum thyroiditis during their first postpartum year

The purpose of the study is to explore the roles of leptin and interleukin-6 (IL-6) during the first postpartum year in the occurrence and development of postpartum thyroiditis (PPT). We retrospectively collected serum samples from 57 PPT patients consisting of 34 overt PPT (O-PPT) and 23 subclinical PPT (S-PPT) in addition to 37 healthy postpartum women at four postpartum time points, i.e., 3-day and 3, 6, 12-month postpartum. Serum leptin and IL-6 levels were measured by radioimmunoassay and ELISA assay, respectively. Leptin level and leptin/BMI (LEP/BMI) ratio were higher in PPT patients than in control during the first postpartum year, but were not significantly different between O-PPT and S-PPT. However, a similar trend but did not reach significant difference in IL-6 level was observed during the postpartum period in PPT patients and control women. We conclude that a sustained high level of serum leptin after delivery may be involved in the pathogenesis of PPT. IL-6 does not contribute to the development of PPT.

Increased expression of IL-37 in patients with Graves' disease and its contribution to suppression of proinflammatory cytokines production in peripheral blood mononuclear cells

Background

Intreleukin-37 (IL-37), a member of IL-1 family, is primarily an anti-inflammatory cytokine, which reduces systemic and local inflammation. However, the expression and role of IL-37 in Graves' disease (GD) remains unknown. This study aims to measure the levels of serum and peripheral blood mononuclear cells (PBMCs) IL-37 in patients with Graves' disease and to examine its association with disease activity. Furthermore, we investigate the effect of IL-37 on proinflammatory cytokines involved in the pathogenesis of GD.

Methods

The expressions of IL-37, TNF-α, IL-6, and IL-17 mRNA in peripheral blood mononuclear cells (PBMCs) of 40 patients with Graves' disease were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR), and the levels of IL-37, TNF-α, IL-6, and IL-17 in serum were detected by enzyme-linked immunoassay (ELISA). The correlation of serum IL-37 levels with cytokines and disease activity in Graves' disease patients were investigated. The expressions of cytokines TNF-α, IL-6, and IL-17 in PBMCs under recombinant IL-37 stimulation were determined by RT-PCR and ELISA respectively.

Results

The levels of IL-37, TNF-α, IL-6, and IL-17 in PBMCs and serum were significantly increased in patients with GD compared with healthy controls (HC). Serum IL-37 were closely correlated with TNF-α, IL-6, IL-17, thyrotropin (TSH), free thyroxine (FT4),free triiodothyronine (FT3) and thyrotropin receptor antibody (TRAB). GD patients with active disease showed higher IL-37 mRNA and serum protein levels compared with those with inactive disease as well as HC. Moreover, IL-37 suppressed the production of IL-6, IL-17 and TNF-α in PBMCs of patients with GD.

Conclusions

Increased level of IL-37 in patients with GD are associated with TNF-α, IL-6, IL-17 and disease activity, and it plays a protective role against inflammatory effect in GD by inhibiting the production of proinflammatory cytokines. Thus, IL-37 may provide a novel research target for the pathogenesis and therapy of GD.

Inflammatory response following a short-term course of chiropractic treatment in subjects with and without chronic low back pain

OBJECTIVE

Inflammatory markers interleukin-6 (IL-6) and C-reactive protein (CRP) have not been evaluated in response to a short course of lumbar spinal manipulation. The purpose of this study is to observe the responses of inflammatory markers (IL-6 and CRP) after a series of 9 chiropractic spinal manipulations.

METHODS

Twenty-one participants were assigned to a treatment or a control group. Only the treatment group received 9 chiropractic interventions. Pre- and postintervention measures were recorded for blood samples for detection of proinflammatory cytokines IL-6 and CRP.

RESULTS

Mediators of inflammation (IL-6 and high-sensitivity CRP) were modified by the intervention received in the treatment group, and the effect size demonstrated a tendency toward the control group values.

CONCLUSION

A total of 9 chiropractic lower back manipulations caused the mediators of inflammation to present a normalization response in individuals suffering from chronic low back pain.

A case report of subacute thyroiditis during pregnancy: difficulties in differential diagnosis and changes in cytokine levels

INTRODUCTION

Thyroid dysfunction during pregnancy may result in both maternal and neonatal complications. Subacute thyroiditis (SAT) is an extremely rare cause of both hyper- and hypothyroidism in pregnant women.

CASE DESCRIPTION

A case of first trimester SAT is presented. Diagnosis of SAT was based on fine-needle aspiration biopsy. The disease resolved spontaneously without need for prednisone administration but a hypothyroid phase treated with T4 throughout pregnancy occurred. The pregnancy resulted in a healthy full term infant. We measured various cytokine levels in an attempt to follow their course during SAT as well as throughout the remaining period of pregnancy. Serum thyreoglobulin (Tg) levels correlated best with thyroid function tests (TFTs) and the course of SAT.

CONCLUSIONS

The diagnosis of SAT at a pregnancy setting may be intriguing. The measurement of circulating cytokines is not helpful in the differential diagnosis or monitoring of the disease.

Salivary C-Reactive Protein in Hashimoto's Thyroiditis and Subacute Thyroiditis

C-reactive protein (CRP), an acute-phase reactant, has been identified as a saliva-based biomarker of inflammation. The objective of the study was to estimate and compare salivary CRP levels in Hashimoto's thyroiditis (HT) and Subacute thyroiditis (SAT). The study included 30 HT patients who presented with clinical features of hypothyroidism, 15 SAT patients who presented with clinical features of hyperthyroidism, and 20 healthy age- and sex-matched euthyroid controls. CRP levels in saliva were estimated using an Enzyme-Linked Immunosorbent Assay method with enhanced sensitivity. In HT, the mean salivary CRP levels did not differ significantly from controls. SAT patients had significantly elevated salivary CRP levels compared to HT patients and controls. The rise in salivary CRP levels in SAT patients conceivably reflects the presence of an inflammatory process. Saliva CRP levels appear to serve as inflammatory markers in SAT patients and may aid their clinical evaluation.

Thyrotoxicosis and low iodine uptake in a woman with graves' disease

Thyrotoxicosis factitia is defined as thyrotoxicosis resulting from exogenous ingestion of thyroid hormone, usually in patients with a psychiatric disorder. Diagnosis can be difficult and this entity should be suspected in patients with high free tiroxine (T4) concentrations, low or suppressed thyroglobulin concentrations, normal urinary iodide excretion and low or suppressed (131)I uptake. To establish the differential diagnosis, thyrotoxicosis factitia must be distinguished from several diseases with low (131)I uptake, such as Graves' disease, subacute thyroiditis, hyperthyroidism due to excessive iodine intake, struma ovarii and metastasis from thyroid cancer. Treatment is based on b-blockers to reduce symptoms and avoid iatrogeny. We present a case of thyrotoxicosis factitia treated in our outpatient clinic.

Glucocorticoid response in amiodarone-induced thyrotoxicosis resulting from destructive thyroiditis is predicted by thyroid volume and serum free thyroid hormone concentrations

CONTEXT

Amiodarone-induced thyrotoxicosis (AIT) resulting from destructive thyroiditis (type 2) is commonly treated with glucocorticoids, but time needed to restore euthyroidism may be unacceptable for patients with underlying cardiac disorders.

OBJECTIVE

The objective of this prospective study was to identify factors affecting the response to glucocorticoids in a large cohort of patients with type 2 AIT followed prospectively.

SETTING

This study was conducted at university centers.

PATIENTS

Sixty-six untreated patients with type 2 AIT were enrolled in the study.

INTERVENTION

All patients were treated with prednisone (initial dose, 0.5 mg/kg.d) as long as needed to restore euthyroidism, defined as cure of AIT.

MAIN OUTCOME MEASURE

The main outcome measure was cure time.

RESULTS

The median cure time was 30 d (95% confidence interval, 23-37 d). Serum free T4 concentration (picograms per milliliter) and thyroid volume (milliliters per square meter) (and, to a lesser extent, serum free T3 concentration) at diagnosis were the main determinants of response to glucocorticoids, with a cure hazard ratio of 0.97 (95% confidence interval, 0.95-0.99; P = 0.005) and 0.84 (95% confidence interval, 0.77-0.91; P = 0.000) for unit of increment, respectively. AIT was cured in all patients with a complete follow-up; euthyroidism was reached in 30 d or less in 60% of patients but in more than 90 d in 16%. A prompt control of thyrotoxicosis (<or=30 d of treatment) was more frequent (77%) in patients with serum basal free T4 concentration no greater than 50 pg/ml and thyroid volume (normalized for body surface area) no greater than 12 ml/m2. The cure probability and the mean cure time in an individual patient can be obtained using a formula generated by multiple regression models.

CONCLUSIONS

Baseline serum thyroid hormone concentrations and thyroid volume help identify patients with type 2 AIT at risk of a delayed response to glucocorticoids.

Is steroid therapy needed in the treatment of destructive thyrotoxicosis induced by alpha-interferon in chronic hepatitis C?

OBJECTIVE

Treatment with interferon (IFN) of patients affected by chronic hepatitis C (CH-C) may produce alterations in thyroid function, such as hypothyroidism, Graves'-like hyperthyroidism and destructive thyrotoxicosis (DT). IFN-induced DT is characterized by suppressed serum TSH levels, normal or elevated FT4 and FT3 concentrations, with the presence or absence of thyroid peroxidase antibodies and antithyroglobulin antibodies, the absence of thyroid receptor antibodies and radioactive iodine uptake suppressed or <5%.

DESIGN

IFN-induced DT is a mild clinical disease, because thyroid-destructive processes last for a short time and involve a small portion of the gland. At present, the therapeutic approach in DT suggests IFN withdrawal and 1-2 months of methylprednisolone treatment.

METHODS

In consideration of possible untoward side effects of steroid treatment in patients with CH-C, we studied two groups of patients with CH-C who developed DT after treatments with various preparations of recombinant IFN (with or without ribavirin). Patients sequentially entered the study during a 4-year period, at the time of DT diagnosis, when IFN therapy was discontinued. The first 12 subjects (group A) were treated with 8-16 mg/day methylprednisolone for 30-40 days after IFN withdrawal; in the following 15 patients (group B), IFN withdrawal was not followed by any additional treatment. All patients underwent clinical and laboratory controls of thyroid function at 1, 2, 3 and 6 months after DT diagnosis.

RESULTS

The results showed restoration of euthyroidism in both group A and group B patients at 6 months after DT diagnosis, regardless of steroid treatment.

CONCLUSIONS

The simple withdrawal of IFN therapy in patients with CH-C, who had developed DT, appears to be effective in the treatment of the thyroid disease. This therapeutic approach should be preferred in order to avoid possible undesired side effects of steroid therapy in patients with CH-C.

Brain-immune interactions and disease susceptibility

Many studies have established the routes by which the immune and central nervous (CNS) systems communicate. This network of connections permits the CNS to regulate the immune system through both neuroendocrine and neuronal pathways. In turn, the immune system signals the CNS through neuronal and humoral routes, via immune mediators and cytokines. This regulatory system between the immune system and CNS plays an important role in susceptibility and resistance to autoimmune, inflammatory, infectious and allergic diseases. This review focuses on the regulation of the immune system via the neuroendocrine system, and underlines the link between neuroendocrine dysregulation and development of major depressive disorders, autoimmune diseases and osteoporosis.

The prevalence of elevated serum C-reactive protein levels in inflammatory and noninflammatory thyroid disease

C-reactive protein (CRP) levels have not been routinely used to diagnose thyroid disease, although many thyroid conditions involve inflammation. This study was intended to determine whether CRP levels could differentiate between inflammatory and noninflammatory thyroid conditions, especially between type II inflammatory amiodarone-induced thyrotoxicosis (AIT) and type I iodine-induced AIT. Serum high-sensitivity CRP levels were measured in 100 euthyroid controls (7 taking amiodarone) and 353 patients with one of the following thyroid conditions: AIT, subacute thyroiditis, toxic diffuse goiter, nodular goiter, Hashimoto's thyroiditis, shortterm hypothyroidism, or postpartum thyroiditis. No patients with nontoxic multinodular goiter (n = 34), toxic nodular goiter (n = 23), or toxic diffuse goiter, either untreated (n = 49) or euthyroid while taking methimazole (n = 33), had positive CRP levels (>10 mg/L). The occurrence of positive CRP levels among patients with Hashimoto's thyroiditis (n = 35), short-term hypothyroidism (n = 38), and postpartum thyroiditis (n = 70) did not differ significantly from controls. The occurrence of positive CRP values did not differ significantly between patients with type I and type II AIT and controls. Six of 7 patients (86%) with untreated subacute thyroiditis had positive CRP levels (p < 0.00001). These results indicate that there is only a limited role for measurement of CRP levels in the diagnosis of thyroid diseases other than subacute thyroiditis.

Effects of Osteoporotic Cytokines in Ovary-Intact and Ovariectomised Rats with Induced Hyperthyroidism; Is Skeletal Responsiveness to Thyroid Hormone Altered in Estrogen Deficiency?

This experimental study was designed to examine the effects of hyperthyroidism on osteoporotic cytokines such as interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF)-alpha in the physiological concentrations and in the deficiency of estrogen. We investigated the effects of thyroid hormones on cytokines and bone metabolism in L-thyroxine induced ovary-intact and ovariectomised rats, as levels of cytokines were increased in hyperthyroidism. The rats were divided into three groups. In the first group, L-thyroxine-induced hyperthyroid rats were ovariectomised (OVX), while the OVX rats were administered L-thyroxine in the second group. The third group received sham-operation. Blood samples taken from the tail vein of rats were analyzed for plasma T3, T4, TSH and serum IL-1beta, IL-6, TNFalpha, calcium (Ca), phosphorous (P), parathyroid hormone (PTH), alkaline phosphatase (ALP), bone-specific alkaline phosphatase (b-ALP). L-thyroxine administration increased the cytokines, ALP and b-ALP and decreased PTH, while there was no change in Ca and P. However, the ovariectomy of these rats did not change the levels of cytokines, Ca, P, PTH, ALP, and b-ALP. In ovariectomised rats, the cytokines, ALP and b-ALP increased but not Ca and P conversely, PTH decreased. L-thyroxine administration to ovariectomised rats did not change the levels of cytokines, Ca, P, PTH, ALP and b-ALP. In sham-operated rats there was no change in any of the parameters compared with initial values. Thyroid hormones may not be effective on bone metabolism in estrogen deficiency.

Serum concentrations of tumour necrosis factor-alpha (TNF-alpha) and soluble TNF-alpha receptor p55 in patients with hypothyroidism and hyperthyroidism before and after normalization of thyroid function

BACKGROUND

Tumour necrosis factor-alpha (TNF-alpha) is a cytokine with numerous immunological and metabolic activities. Receptors for TNF-alpha have been demonstrated in thyroid follicular cells and TNF-alpha and its receptors have been implicated in the cytotoxic mechanisms that characterize the thyroid destruction in autoimmune thyroid disease. In patients with Graves' disease, serum levels of TNF-alpha have been reported to be elevated and administration of TNF-alpha to humans has been shown to induce hormonal alterations resembling those seen in the nonthyroidal illness syndrome.

OBJECTIVE

To evaluate serum concentrations of TNF-alpha and the soluble receptor for TNF-alpha (sTNFR-I) in a group of patients with thyroid dysfunction before and after normalization of thyroid function with appropriate therapy.

DESIGN

We studied 20 patients with hypothyroidism (18 women and 2 men, mean age +/- SD, 48.8 +/- 16.1 years) and 20 patients with hyperthyroidism (14 women and 6 men, age 44.6 +/- 15.9 years). Patients were assessed at the time of diagnosis and again after normalization of thyroid function tests with appropriate therapy. A group of 20 healthy subjects (15 women and 5 men, age 44.9 +/- 15.1 years) were also studied as a control group.

SETTING

All subjects were ambulatory and were studied as outpatients during visits to the endocrinology clinic.

MEASUREMENTS

Serum concentrations of free T4 (FT4), total T3, TSH, TNF-alpha and sTNFR-I were measured in all subjects. TNF-alpha and sTNFR-I were measured using a quantitative enzyme immunoassay.

RESULTS

In patients with hypothyroidism serum concentrations of TNF-alpha (3.17 +/- 1.18 pg/ml) and sTNFR-I (1273 +/- 364 pg/ml) were significantly higher than those found in controls (2.42 +/- 0.76 pg/ml, P < 0.05, and 971 +/- 235 pg/ml, P < 0.01, respectively). Normalization of thyroid function with l-thyroxine therapy did not significantly modify TNF-alpha or sTNFR-I levels. There were no differences in pre- and post-therapy values of TNF-alpha and sTNFR-I in patients with autoimmune (n = 14) or nonautoimmune (n = 6) hypothyroidism. Before therapy, patients with hyperthyroidism showed elevated serum concentrations of TNF-alpha (3.36 +/- 1.21 pg/ml; P < 0.01) and sTNFR-I (2274 +/- 579 pg/ml; P < 0.001) in relation to the control group. Treatment of hyperthyroidism was accompanied by a normalization of TNF-alpha levels (2.46 +/- 0.89 pg/ml; P < 0.001) and by a significant decrease in sTNFR-I concentrations (1369 +/- 475 pg/ml; P < 0.001). Post-therapy levels of TNF-alpha and sTNFR-I showed a significant correlation with loss of weight (r = 0.674, P < 0.01, and r = 0.629, P < 0.01, respectively) in hypothyroid patients. No correlation between these parameters was found in the group of patients with hyperthyroidism.

CONCLUSIONS

In summary, these results confirm the relevance of activation of the TNF-alpha system in patients with thyroid dysfunction, as high plasma concentrations of TNF-alpha and sTNFR-I have been demonstrated in patients with hypothyroidism or hyperthyroidism. Treatment of hyperthyroidism is accompanied by a significant reduction in the previously elevated concentrations of both TNF-alpha and sTNFR-I. However, these changes are not seen when normalizing thyroid function in patients with hypothyroidism.

The various effects of amiodarone on thyroid function

Amiodarone, a benzofuranic-derivative iodine-rich drug used mostly for tachyarrhythmias, often causes changes in the peripheral metabolism of thyroid hormones mainly due to the inhibition of 5'-deiodinase activity: an increase in serum thyroxine and reverse triiodothyronine, and a decrease in serum triiodothyronine concentrations. Overt thyroid dysfunction, either amiodarone-induced thyrotoxicosis (AIT) or amiodarone-induced hypothyroidism (AIH), occurring in 14% to 18% of patients receiving long-term treatment, may develop both in apparently normal thyroid glands and in glands with preexisting abnormalities. AIH is mainly due to the failure to escape from the acute Wolff-Chaikoff effect, and, in patients with thyroid autoimmune phenomena, to concomitant Hashimoto's thyroiditis. AIT is due to excess iodine-induced thyroid hormone synthesis (type I AIT) or to amiodarone-related destructive thyroiditis (type II AIT), although mixed forms often occur. Treatment of AIH consists of levothyroxine replacement therapy while continuing amiodarone therapy; alternatively, amiodarone can be discontinued, if possible, and the natural course toward euthyroidism can be accelerated by a short trial of potassium perchlorate. In type I AIT, the simultaneous administration of thionamides and potassium perchlorate is the treatment of choice, while in type II AIT steroids are the most useful therapeutic option. Mixed forms are best treated with a combination of thionamides, potassium perchlorate, and glucocorticoids. The low thyroidal 131I uptake usually makes radioiodine therapy not feasible, while thyroidectomy is a valid alternative in cases resistant to medical therapy.

The effects of amiodarone on the thyroid

Amiodarone is a benzofuranic-derivative iodine-rich drug widely used for the treatment of tachyarrhythmias and, to a lesser extent, of ischemic heart disease. It often causes changes in thyroid function tests (typically an increase in serum T(4) and rT(3), and a decrease in serum T(3), concentrations), mainly related to the inhibition of 5'-deiodinase activity, resulting in a decrease in the generation of T(3) from T(4) and a decrease in the clearance of rT(3). In 14-18% of amiodarone-treated patients, there is overt thyroid dysfunction, either amiodarone-induced thyrotoxicosis (AIT) or amiodarone-induced hypothyroidism (AIH). Both AIT and AIH may develop either in apparently normal thyroid glands or in glands with preexisting, clinically silent abnormalities. Preexisting Hashimoto's thyroiditis is a definite risk factor for the occurrence of AIH. The pathogenesis of iodine-induced AIH is related to a failure to escape from the acute Wolff-Chaikoff effect due to defects in thyroid hormonogenesis, and, in patients with positive thyroid autoantibody tests, to concomitant Hashimoto's thyroiditis. AIT is primarily related to excess iodine-induced thyroid hormone synthesis in an abnormal thyroid gland (type I AIT) or to amiodarone-related destructive thyroiditis (type II AIT), but mixed forms frequently exist. Treatment of AIH consists of L-T(4) replacement while continuing amiodarone therapy; alternatively, if feasible, amiodarone can be discontinued, especially in the absence of thyroid abnormalities, and the natural course toward euthyroidism can be accelerated by a short course of potassium perchlorate treatment. In type I AIT the main medical treatment consists of the simultaneous administration of thionamides and potassium perchlorate, while in type II AIT, glucocorticoids are the most useful therapeutic option. Mixed forms are best treated with a combination of thionamides, potassium perchlorate, and glucocorticoids. Radioiodine therapy is usually not feasible due to the low thyroidal radioiodine uptake, while thyroidectomy can be performed in cases resistant to medical therapy, with a slightly increased surgical risk.

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

To investigate whether amiodarone increases interleukin-6 (IL-6) production in thyrocytes, human follicles obtained from subtotally thyroidectomized patients with Graves' disease were cultured in serum-free medium supplemented with various concentrations of bovine thyrotropin (bTSH) and amiodarone. The follicles gradually formed monolayer cells and secreted triiodothyronine (T3), thyroglobulin (Tg), and IL-6 for at least 14 days. TSH dose-dependently increased T3 and Tg but not IL-6 levels in the conditioned medium. Amiodarone exerted no significant effect on T3, Tg, or IL-6 concentrations at 0.1-1 microM. In contrast, at 10-20 microM, it decreased T3 and Tg, but increased IL-6 levels, and these changes were accompanied by increased expression of IL-6 mRNA. Amiodarone-induced IL-6 production was inhibited by prednisolone at 10(-7) M. Electron microscopic examination revealed that the thyroid follicles in the suspension culture remained intact at 1 microM, but that cytotoxic effects (decreased microvilli and increased onion-like inclusion bodies) occurred at higher concentrations (10-25 microM). These in vitro findings indicate that amiodarone does not impair thyroid function at clinically attainable serum levels (1 microM), but exerts cytotoxic effect by inducing the production of a proinflammatory cytokine (IL-6) at higher concentrations. Because amiodarone-induced IL-6 production was inhibited by prednisolone, it is reasonable to administer glucocorticoids to patients with amiodarone-induced destructive thyrotoxicosis (type II).

Cytokine gene expression in autoimmune thyroiditis in BioBreeding/Worcester rats

The intrathyroidal cytokine gene expression in human autoimmune thyroid disease is difficult to interpret because surgical specimens mostly reflect the autoimmune disease at a late stage. Because it is not possible to investigate early stages of thyroiditis in humans, the Bio Breeding/Worcester (BB/W) rat was used as a model. To characterize the lymphocytic thyroiditis (LT) of BB/W rats further and to evaluate early increases of cytokine gene expression in LT, we investigated the interleukin (IL)-2, -4, -6, -10, -12p40, interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) gene expression in the thyroids, spleens, and livers of BB/W rats with and without histological evidence for thyroiditis. The gene expression of these cytokines was determined by Genescan (PE Applied Biosystems, Foster City, CA) fragment analysis using reverse polymerase chain reaction (RT-PCR). Serum thyroglobulin (Tg) antibody concentrations were measured and the extent of lymphocytic infiltration of one thyroid lobe was histologically graded. Cytokine gene expression in rats with and without LT was compared in three groups of rats: 55-day-old rats after 24 days of iodine administration, 75-day-old rats after 45 days of iodine administration, and 101-day-old rats. In the thyroids of the BB/W rats no expression of IL-4 or IL-10 was detectable. The number of rats with detectable TNF-alpha, IFN-gamma, IL-2, IL-12p40 gene expression was significantly higher in rats with LT. Rats with LT had significantly higher IL-12p40 mRNA levels. There were no significant differences in the IL-6 gene expression between rats with and without LT. A correlation between the level of lymphocytic infiltration and the TNF-alpha (r = 0.56, p < 0.0065) and TG antibody concentration (r = 0.62, p < 0.0065) was found. Therefore, the early cytokine gene expression in the BB/W rat is characterized by Th1-related cytokines like IL-2 and IFN-gamma. Whether the detected IL-12p40 (10 rats) and IFN-gamma (5 rats) gene expression in animals without LT is an early indicator for the development of LT remains to be determined.

Serum cytokines in thyrotoxicosis

Overproduction of thyroid hormones promotes bone resorption in vivo and in vitro, and we have evaluated whether mediators of such effects could include the osteotropic cytokines. Previous studies have demonstrated raised serum interleukin (IL)-6 in thyrotoxic patients, but differentiating the contribution of the elevated thyroid hormones from that of the autoimmune inflammation present in Graves' disease (GD) has been difficult. We undertook a longitudinal study of 34 patients (19-45 yr old) with GD, toxic nodular goiter (TNG), or a history of thyroid carcinoma but no evidence of disease recurrence, receiving sufficient T4 to suppress TSH. Controls were 12 euthyroid females. The following measurements were made basally and for 6 months after carbimazole treatment: serum free T4, T3, bone-specific alkaline phosphatase (b-ALP), IL-6, IL-8, IL-1beta, tumor necrosis factor-alpha, IL-11, and urinary deoxypyridinoline (Udpd). Compared with controls (IL-6, 1.1 +/- 0.3 ng/L; IL-8, 3.2 +/- 0.8 ng/L), untreated patients with GD and TNG had elevated IL-6 (GD, 7.11 +/- 0.88 ng/L; TNG, 7.30 +/- 0.77 ng/L; P < 0.001) and IL-8 (GD, 10.3 +/- 1.23 ng/L; TNG, 9.81 +/- 1.27 ng/L; P < 0.001). These levels fell after treatment and were then indistinguishable from those in control subjects. Thyroid carcinoma patients on TSH suppressive therapy also had significantly raised levels of IL-6 (2.5 +/- 0.42 ng/L) and IL-8 (4.4 +/- 0.63 ng/L). When data from all the patients were pooled, the levels of IL-6 and IL-8 correlated with serum T3 and free T4 but not with Udpd or b-ALP. IL-1beta, IL-11, and tumor necrosis factor-alpha were not raised in any patient. The elevations in serum IL-6 and -8 that occur in hyperthyroidism seem to result from the chronic effects of thyroid hormone excess rather than the accompanying autoimmune inflammatory condition produced by Graves' thyroid or eye disease. The site of the presumed increased production of IL-6 and -8 is most likely from bone osteoblasts, despite the inability of bone markers (such as Udpd and b-ALP) to correlate with acute changes in thyroid hormone status produced by antithyroid therapy.

Recombinant interferon alpha (rIFN-alpha) does not potentiate the effect of iodine excess on the development of thyroid abnormalities in patients with HCV chronic active hepatitis

OBJECTIVE

To determine whether the administration of pharmacological quantities of iodine during interferon-alpha (rIFN-alpha) treatment of chronic viral hepatitis B and C (HCV) would exacerbate the potential adverse effects of rIFN alpha on thyroid function.

DESIGN

Thyroid function tests were carried out in 48 euthyroid patients before and during rIFN-alpha therapy of HCV. Twenty-one of these patients were also treated with 10 drops saturated solution of potassium iodine (SSKI, approximately 350 mg iodine daily). Eight patients with HCV but not treated with rIFN-alpha received 10 drops SSKI.

PATIENTS

All patients were enthyroid prior to rIFN-alpha therapy for HCV or iodine and thyroid function tests were similar in the three groups.

MEASUREMENTS

Serum free T4, free T3, and TSH concentrations were measured prior to and at 30 and 60 days of rIFN-alpha therapy in the three groups of patients. The serum TSH response to TRH was assessed before rIFN-alpha therapy and on day 60. Thyroid peroxidase antibodies were measured before and during therapy.

RESULTS

During the 2-month study period, similar small but significant decreases in serum FT4 and FT3 and compensatory small significant increases in TSH concentrations were observed in the patients treated with rIFN-alpha + iodine and iodine alone but not in the patients receiving rIFN-alpha alone. Abnormal thyroid function tests were observed more frequently in patients receiving rIFN-alpha + iodine and iodine alone compared to those receiving rIFN-alpha alone.

CONCLUSIONS

Excess iodine administered to patients treated with rIFN-alpha induced small changes in thyroid function similar to those observed in patients treated with iodine alone. Thus, rIFN-alpha and iodine do not appear to be synergistic in the development of abnormal thyroid function tests over a 2-month treatment period.

Normal serum concentrations of sex hormone binding-globulin in patients with hyperthyroidism due to subacute thyroiditis

Serum concentrations of sex hormone binding-globulin (SHBG) were determined in patients with hyperthyroidism (n = 94; 12 men, 82 women) due to either Graves' disease (n = 59; 11 men, 48 women), autonomous thyroid adenomas (n = 23; 1 man, 22 women), or subacute thyroiditis (n = 12; all women). Elevated serum concentrations of SHBG were initially seen in 57 of 82 patients (69%) with hyperthyroidism due to either Graves's disease or due to autonomous adenoma. Elevated serum SHBG concentration was more frequent in patients with serum total thyroxine (TT4) concentrations greater than 15.0 microg/dL (32/39 [82%]; including 3 patients with autonomous adenoma) compared to those with serum TT4 concentration between 11.0 and 15.0 microg/dL (21/27 [77%]; including 7 patients with autonomous adenoma), or patients with an isolated elevation of serum total triiodothyronine (TT3) concentration (4/16 [25%]; including 2 patients with autonomous adenoma). Serum SHBG concentration normalized when patients became euthyroid. Only 1 of 12 patients in the hyperthyroid phase of subacute thyroiditis had an elevated serum concentration of SHBG. Serum concentrations of thyroid binding globulin (TBG) and transcortin (CBG) were normal in all but 1 patient. In patients with hyperthyroidism as a result of Graves' disease or autonomous adenoma serum SHBG concentrations were elevated with the greatest elevation found in patients with the highest serum T4 concentrations. The normal concentrations of SHBG in the hyperthyroid phase of subacute thyroiditis most likely reflects the shorter duration of exposure to increased thyroid hormone in this condition.

Acute and delayed effects of a single-dose injection of interleukin-6 on thyroid function in healthy humans

Interleukin-6 (IL-6) is produced in response to inflammatory and noninflammatory stress and acts as the principal regulator of the acute-phase protein response. IL-6 stimulates the hypothalamic-pituitary-adrenal axis and may be involved in the thyroid function abnormalities observed in nonthyroidal illness (NTI). This study examined the effects of single-dose IL-6 (3 microg/kg subcutaneously [s.c.]) in healthy human subjects: 19 received IL-6 and 13 received control saline injection. The dose of IL-6 was chosen on the basis of previous studies indicating that the peak IL-6 level after injection reaches concentrations observed with major stress such as abdominal surgery. Plasma levels of thyrotropin (TSH), free thyroxine (FT4), total T4, 3,5-3'-L-triiodothyronine (T3), 3,3'-5'-L-triiodothyronine or reverse T3 (rT3), and thyroxine-binding globulin (TBG) were measured over a 4-hour period and 24 hours after IL-6 injection. Plasma TSH levels were 27% lower 240 minutes after IL-6 relative to control levels (0.93 +/- 0.10 v 1.28 +/- 0.18 mIU/mL, P = .001), but recovered by 24 hours. Plasma FT4 was elevated at 240 minutes compared with the controls (1.16 +/- 0.04 v 1.03 +/- 0.03 ng/dL, P = .0002). T4 levels were also elevated at 240 minutes (7.8 +/- 0.36 v 7.05 +/- 0.37 microg/dL, P = .0003). TBG levels were not significantly changed at this time point. At 24 hours, T3 levels were 19% lower than the control values (87.6 +/- 5.1 v 108.5 +/- 5.4 ng/dL, P = .0002); plasma rT3 levels were elevated by 21% compared with control levels (30.6 +/- 1.7 v 24.3 +/- 1.3 ng/dL, P = .002), while FT4 levels returned to normal. The changes in T3/rT3 levels were reminiscent of the pattern observed in NTI that may be due to inhibition of type-1 5'-deiodinase. Cortisol levels were greatly elevated after IL-6 compared with control values; peak levels were observed 120 minutes after IL-6 injection (28.7 +/- 1.6 v 9.5 +/- 1.0 ng/dL, P < .0001). This elevation in cortisol may have contributed to the suppression of TSH levels and inhibition of type-1 5'-deiodinase activity. Alternatively, IL-6 may have suppressed TSH secretion via a direct suprapituitary action. The elevation of T4 and FT4 levels may have been due to inhibition of T4 degradation at the liver and/or by direct action of IL-6 on the thyroid gland. These findings demonstrate the potent effects of IL-6 on thyroid hormone metabolism in healthy individuals, and suggest that IL-6 may act directly or indirectly at two or more sites on thyroid hormone secretion and metabolism.

Interleukin-6 levels are not increased in women with postpartum thyroid dysfunction

Postpartum thyroid dysfunction (PPTD) is an autoimmune-mediated thyroid destructive process. Human interleukin-6 (IL-6) is a cytokine found to be increased in subacute thyroiditis, amiodarone-induced thyrotoxicosis, Graves' disease, and other thyroid destructive processes. We report serum IL-6 levels in PPTD in two independent studies. New York Study: In a previous prospective study we demonstrated that PPTD occurred in 25% (7/28) of women with type 1 diabetes mellitus. IL-6 determinations were made on the frozen serum samples of these 28 women during each trimester of their pregnancy and at 1.5, 3, 6, 9, and 12 months postpartum. IL-6 levels were found to be similar in women with PPTD compared with women without PPTD (mean 3.06+/-2.25 vs. 2.51+/-2.21 pg/mL; p = 0.15). No difference in IL-6 levels was found between the pre- and the postpartum periods (mean 2.67+/-1.82 vs. 3.04+/-2.44 pg/mL; p = 0.30) in all 28 women. Cardiff Study: Serum IL-6 levels were measured on frozen serum samples of 30 women with PPTD. IL-6 levels were below the detection limit (25 fmol/L or 0.65 pg/mL) in 94 (67%) of these samples. No significant difference in the mean serum IL-6 levels were found between any time points in the study. There was no correlation between serum IL-6 levels, thyroid peroxidase (TPO)- antibodies and serum thyrotropin (TSH) levels at any time point. IL-6 levels during pregnancy or postpartum were not found to be significantly different in women with PPTD compared with women without PPTD.

Syndromes of thyrotoxicosis with low radioactive iodine uptake

It is very important to diagnose correctly the etiology of thyrotoxicosis, because the course and treatment of thyrotoxicosis with low radioactive iodine uptake differ significantly from that of hyperthyroidism due to Graves' disease or toxic nodular goiter. Many causes of subacute thyroiditis have been identified producing a characteristic course of transient hyperthyroidism, followed by hypothyroidism, and usually recovery. Ectopic hyperthyroidism includes factitious thyroid hormone ingestion, struma ovarii, and, rarely, large deposits of functioning thyroid cancer metastases. Iodine-induced hyperthyroidism may be associated with low radioiodine uptakes. Amiodarone-associated hyperthyroidism may be the result of subacute thyroiditis or iodine-induced hyperthyroidism; assessment and treatment can be quite challenging.

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.

Relationship of the increased serum interleukin-6 concentration to changes of thyroid function in nonthyroidal illness

Variations in the serum concentration of interleukin-6 (IL-6) have been reported concomitantly with thyroid dysfunction: increased serum IL-6 levels have been found in patients with thyroidal destructive processes, such as subacute thyroiditis, some forms of amiodarone-induced thyrotoxicosis, or after percutaneous ethanol injection into "hot" thyroid nodules, as a result of the cytokine release from the damaged thyrocyte. In addition, recent in vitro evidence suggests that IL-6 might account, at least in part, for changes of thyroid economy found in nonthyroidal illness (NTI). In this cross-sectional study we addressed this problem by measuring serum IL-6 levels in 71 patients with NTI, due to neoplasia (n = 25), chronic liver disease (n = 9), chronic renal failure (n = 28), or other chronic nonthyroidal disorders (n = 9). These patients had reduced mean serum total T3 (TT3) and free T3 (FT3) concentrations, normal total and free T4 levels, normal TSH values, and increased serum reverse T3 (rT3) concentration (with the exception of chronic renal failure patients, who had normal rT3 levels). Serum IL-6 concentration was increased above normal (i.e. > 100 fmol/L) in almost all NTI patients, especially in those with low T3 values (median value: 258 fmol/L, range 73-3210, vs 152 fmol/L, range < 12.5-460, in patients with normal TT3 values, p < 0.001). Serum IL-6 values in NTI patients were negatively correlated with serum FT3 values (r = 0.56, p < 0.001), and positively correlated with serum rT3 values (r = 0.78, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Iodide induced lymphocytic thyroiditis in the BB/W rat: evidence of direct toxic effects of iodide on thyroid subcellular structure

A high dietary iodine intake accelerates the development of lymphocytic thyroiditis (LT) in the BB/W rat. Our previous studies have defined the temporal sequence of the immunological events triggered by excess iodide intake in these animals. It was still not clear, however, whether these observed immunological changes were a direct effect on immune effector cells, or whether they represented a secondary response to a toxic effect of iodine on thyroid tissue. In the present study, the effect of excessive iodine intake on the subcellular structure of the BB/W rat thyroid gland, particularly, whether iodide had a toxic effect independent of its immune response has been examined. BB/W rats were exposed, prenatally through maternal drinking water, to excessive iodide at two doses (Moderate 3 x 10(-6) M iodide/l; High 3 x 10(-3) M iodide/l); a third group of BB/W rats was given tap water; till 12 weeks postnatal age. Two groups of Wistar rats received high dose iodide water or tap water for the same period of time and served as controls. Thyroid gland ultrastructure was determined by electron microscopic (EM) examination. Thyroid 125I uptake and perchlorate discharge tests were also performed in separate experiments. We found that thyroid glands of non-iodine supplemented Wistar rats were morphlogically normal under EM. There were no overt changes in the iodide treated Wistar rats. By contrast, iodide treated BB/W rats exhibited marked accumulation of secondary lysosomes and lipid droplets; markedly swollen and disrupted mitochondria and extreme dilatation of rough endoplasmic reticulum (RER).(ABSTRACT TRUNCATED AT 250 WORDS)