Interleukin-1 receptors on human thyroid cells and on the rat thyroid cell line FRTL-5

Prevalence and correlation of cytokine-specific autoantibodies with epidemiological factors and C-reactive protein in 8,972 healthy individuals: Results from the Danish Blood Donor Study

Natural cytokine-specific autoantibodies (c-aAb) have been measured in healthy and diseased individuals, and have been considered as both endogenous immune-regulators and pathogenic factors. Overall, the etiology and potential pathology of c-aAb are still undefined. To further characterize the sero-prevalence, predictors and consequences of high c-aAb levels, we performed the largest population-based study of c-aAb to date, using participants and epidemiological data from the Danish Blood Donor Study. Using a validated bead-based multiplex assay we assessed plasma levels of IL-1α, IL-6, IL-10, IFNα and GM-CSF-specific c-aAb in 8,972 healthy blood donors. Trace levels of at least one of the investigated c-aAb could be measured in 86% of the participants. The presence of high levels of potentially inhibitory c-aAb was generally associated with increasing age and male or female sex, depending on the c-aAb in question. A negative correlation between high levels of IL-6-specific c-aAb and plasma levels of C-reactive protein was observed, indicating cytokine-neutralizing levels of c-aAb in healthy blood donors. There was no substantial correlation between high levels of the five individual c-aAb investigated in this study. These data suggest that autoimmunity against endogenous cytokines is a relatively common phenomenon in healthy individuals, and that predictive factors for high, potentially neutralizing c-aAb levels vary depending on the cytokine in question, and may differ from predictors of general c-aAb presence.

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.

The role of interleukin-6 and C-reactive protein in non-thyroidal illness in premature infants followed in neonatal intensive care unit

OBJECTIVE

To investigate the role of interleukin-6 (IL-6) and C-reactive protein (CRP) in non-thyroidal illness (NTI) in premature infants.

METHODS

Serum levels of IL-6 and CRP, thyroid-stimulating hormone (TSH), total thyroxine (T4), free T4 (fT4), total triiodothyronine (T3), and free T3 (fT3) were determined at the 1st, 2nd and 4th weeks of postnatal life in 148 premature infants born before 33 weeks of gestation.

RESULTS

At the 1st week, serum T3 was negatively correlated with IL-6 (r= -0.33, p= 0.001) and CRP (r= -0.17, p= 0.03). Serum T3 was negatively and more strongly correlated with IL-6 (r= -0.49, p= 0.001) and CRP (r=- 0.33, p= 0.03) at the 2nd week, at which time sepsis frequency and low T3 rates were the highest. At the 4th week, mortality rate was higher among infants with lower T3 levels.

CONCLUSIONS

High IL-6 and CRP values related to neonatal sepsis might have a significant role in the pathogenesis of NTI in premature infants.

Interspecies differences in membrane-associated protease activities of thyrocytes and their relevance for thyroid cancer studies

Background

To understand the role of proteases involved in human thyroid cancer progression and tissue invasion, thyrocytes from other species could potentially be used provided their characteristics are similar. It is not known whether dipeptidyl peptidase IV and aminopeptidase N activities, which are overexpressed in human thyroid cancer, are, as in human, also absent in normal thyrocytes of other species, making them suitable models for studies on the regulation of these proteases.

Methods

To assess the role of these proteases, activity was measured in thyroid tissue of human, mouse, rat, porcine, bovine and ovine origin. The lysosomal protease, dipeptidyl peptidase II, was used for comparison.

Results

Murine, rat, ovine, bovine and human thyrocytes all lacked dipeptidyl peptidase IV and aminopeptidase N activity, but porcine thyrocytes were found to possess both. In contrast, lysosomal dipeptidyl peptidase II was strongly expressed in all species. These activity patterns were maintained in cultured cells. Cultured porcine thyrocytes formed follicles with typical morphology upon stimulation with TSH but differed from human thyrocytes in their response to thiamazole.

Conclusions

These species differences in the expression of dipeptidyl peptidase IV and aminopeptidase N, indicate that porcine thyrocytes cannot be considered appropriate for the study of proteases in human cancer development.

Differential interactions between Th1/Th2, Th1/Th3, and Th2/Th3 cytokines in the regulation of thyroperoxidase and dual oxidase expression, and of thyroglobulin secretion in thyrocytes in vitro

Hypothyroidism, together with glandular atrophy, is the usual outcome of destructive autoimmune thyroiditis. The impairment in the thyroid function results either from cell destruction or from Th1 cytokine-induced alteration in hormonogenesis. Here, we investigated the impact of the local immune context on the thyroid function. We used two rat thyroid cell lines (PCCL3 and FRTL-5) and human thyrocytes incubated with IL-1alpha/interferon (IFN) gamma together with IL-4, a Th2 cytokine, or with TGF-beta, or IL-10, two Th3 cytokines. We first observed that IL-4 totally blocked IL-1alpha/interferon gamma-induced alteration in dual oxidase and thyroperoxidase expression, and in thyroglobulin secretion. By contrast, TGF-beta and IL-10 had no such effect. They rather repressed thyrocyte function as do Th1 cytokines. In addition, IL-4 blocked IL-10-induced repression of thyrocyte function, but not that induced by TGF-beta. In conclusion, Th1 cytokine- and IL-10-induced local inhibitory actions on thyroid function can be totally overturned by Th2 cytokines. These data provide new clues about the influence of the immune context on thyrocyte function.

Interleukin-1beta (IL-1beta) induces a crosstalk between cAMP and ceramide signaling pathways in thyroid epithelial cells

Interleukin-1 beta (IL-1beta) is an important regulator of the thyroid cell function. This cytokine has been largely described to trigger an important biological signaling cascade: the sphingomyelin/ceramide pathway. In this report, we show that IL-1beta induces the transient activation of a neutral sphingomyelinase in porcine thyroid cells. Moreover, IL-1beta and ceramides are demonstrated to inhibit the TSH-induced cAMP production via the implication of alphaGi subunit of the adenylyl cyclase system. This crosstalk between cAMP and ceramide pathways constitutes a preponderant process in the TSH-controlled differentiation state of thyrocytes. All these results argue for the involvement of ceramides and IL-1beta in the thyroid function regulation, leading to a cell dedifferentiated state.

The role of neuroendocrine immune interactions in the initiation of humoral immunity in chickens

The presence of neuroendocrine immune interaction in mammalian species has been studied extensively and has been established. However, such an interaction is not as well established in avian species. Furthermore, the role of such an interaction in the initiation of humoral immunity is not well understood. Therefore, the present studies were conducted to determine mechanisms involved in the initiation of humoral immunity in chickens. Cornell K-strain White Leghorn immature male chickens were used for all the experiments. Changes in hormonal and leukocyte profiles after antigen stimulation were studied. The ability of different leukocytes to produce ACTH was also investigated. It was concluded that the first step in the initiation of humoral immunity after antigen exposure is the release of interleukin-1 by macrophages, which in turn stimulates the production of CRF by hypothalamus and/or leukocytes. It is important to mention that CRF production could also be a direct effect of antigen stimulation. The CRF will then stimulate ACTH production by anterior pituitary and/or leukocytes. In addition, CRF will directly enhance lymphocyte activities in the spleen. Corticosteroid production will be stimulated by ACTH and will cause redistribution of lymphocytes from circulation to secondary lymphoid organs such as the spleen for antigen processing and eventual production of antibodies against the invading antigens. Finally, both ACTH and corticosteroids will later act in a negative feedback manner to regulate and control the process of antibody production by inhibiting lymphocyte activities and/or reducing the responsiveness to different stimuli.

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.

Differential binding of human interleukin-1 (IL-1) receptor antagonist to natural and recombinant soluble and cellular IL-1 type I receptors

A recently described factor, interleukin-1 receptor antagonist binding factor (IL-1raBF), in serum of normal individuals is immunologically related to the interleukin-1 receptor type I (IL-1RI). It is presumably a soluble form of the receptor that binds exclusively to interleukin-1 receptor antagonist (IL-1ra). Recombinant soluble human IL-1RI expressed in COS cells (sIL-1RI) consists of the extracellular part of the receptor and binds all three known IL-1 species but preferentially to Il-1ra. We further characterized the sizes and binding of IL-1raBF and sIL-1RI to IL-1ra by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate, ligand binding interference analyses, N-glycosidase treatment, concanavalin A affinity chromatography, and with the use of monoclonal antibodies (mAb) to human recombinant IL-1ra. We also evaluated the binding of IL-1ra to cellular IL-1RI on MRC5 fibroblasts and the interference afforded by the soluble receptors. The results show that the protein backbones of IL-1raBF and sIL-1RI are of similar size (approximately 35-40 kDa) and that there are differences in the glycosylation of the two molecules. These carbohydrates were necessary for optimal binding of both molecules to IL-1ra. Both factors blocked binding of IL-1ra to cellular IL-1RI, as did mAb to IL-1ra, but the sites on IL-1ra which bound to the mAb, and to IL-1raBF and sIL-1RI, differed. We conclude that there are important differences between the natural and recombinant forms of soluble IL-1RI and that IL-1ra binds differently to these molecules and to cellular IL-1RI.

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.

Cytokines and autoimmunity

Although the immunopathology of most autoimmune diseases has been well defined, the mechanisms responsible for the breakdown of self-tolerance and which lead to the development of systemic and organ-specific autoaggression are still unclear. Evidence has accumulated which supports a role for a disregulated production of cytokines by leucocytes and possibly other cells in the pathogenesis of some autoimmune diseases. However, due to the complexity and heterogeneity of cytokine effects in the regulation of the immune response, it is difficult to determine whether abnormalities in the patterns of cytokine production are primary or secondary to the pathological process. Confusion is also caused by the fact that the biological activities of cytokines are multiple and often overlapping, and consequently it is difficult to focus on a unique effect of any one cytokine. Characterization of the potential and actual involvement of cytokines is important not only for a better understanding of the pathogenesis of autoimmune conditions, but particularly because of the implications for the development of immunotherapeutic strategies for the prevention and treatment of the diseases.

Sex- and age-dependency of IgG auto-antibodies against IL-1 alpha in healthy humans

Naturally occurring anti-interleukin (IL)-1 alpha IgG antibodies (Ab-IL-1 alpha) were measured in sera of 466 healthy Danish blood donors. Ab-IL-1 alpha bound IL-1 alpha with exceptionally high affinity (Kd: 10(-11) M) and neutralized both cell-associated and extracellular IL-1 alpha but not IL-1 beta or IL-1 receptor antagonist. More than 80% of the saturable binding of rIL-1 alpha to serum was to Ab-IL-1 alpha, suggesting that these antibodies are the quantitatively most important IL-1 alpha-binding components in serum. Judged by second antibody precipitation assay, the prevalence of Ab-IL-1 alpha varied between 30% and 75% and correlated positively with age (P = 0.037). The binding capacity of serum also increased with age. Although men were more frequently positive than women (P < 0.001), there were no sex- or age-dependent alterations in the average affinities of the antibodies. Free IL-1 alpha-like molecules were generally not detected in these sera. However, acid treatment showed that 25% of Ab-IL-1 alpha-positive sera contained low amounts of IL-1 alpha-Ab-IL-1 alpha immune complexes. IgG4 represented the main IgG isotype, whereas IgG3 Ab-IL-1 alpha were undetectable. The relative amounts of IgG4 Ab-IL-1 alpha increased while IgG2-and IgG1 Ab-IL-1 alpha decreased in elderly individuals. The presence in normal individuals and the lack of affinity maturation with age suggest that Ab-IL-1 alpha may be regulatory natural auto-antibodies perhaps coded by germline genes.

Specific binding of interleukin 1 (IL-1) beta and IL-1 receptor antagonist (IL-1ra) to human serum. High-affinity binding of IL-1ra to soluble IL-1 receptor type I

Molecules that bind recombinant interleukin 1 (rIL-1) beta and rIL-1 receptor antagonist (rIL-1ra) with high affinity were detected in sera of healthy individuals. rIL-1 beta bound with dissociation constants in the nanomolar range, and the serum binding capacity was 40-50 ng/ml. rIL-1ra bound with 30 times higher affinity, and the serum binding capacity was 0.7-1 ng/ml. Rabbit antibodies against the recombinant-derived extracellular part of human IL-1 receptor type I (rsIL-1RI) selectively inhibited the binding of 125I-rIL-1ra to the serum factor(s). Almost 70% of the high-affinity IL-1ra-binding capacity was recovered after immunosorption with these antibodies. Binding of 125I-rIL-1ra to rsIL-1RI was blocked by rIL-1 alpha and by rIL-1 beta. In contrast, the purified rIL-1ra-binding factor (IL-1raBF) failed to bind rIL-1 alpha and rIL-1 beta. Gel filtration chromatography indicated a 1:1 binding of rIL-1 beta and rIL-1ra to their respective serum factors. The apparent molecular size of both serum factors was 70-80 kDa. Using SDS-PAGE and autoradiography, IL-1raBF had a molecular size of 60 kDa. We conclude that IL-1raBF, a serum factor which selectively and with high affinity binds IL-1ra (Kd = 70 pM), is related to or identical with a soluble form of IL-1RI. If upregulated during disease, IL-1raBF may constitute yet another level of natural regulation of IL-1 bioactivities.

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.

High-affinity IgG autoantibodies to IL-6 in sera of normal individuals are competitive inhibitors of IL-6 in vitro

Nano- to picomolar concentrations of high affinity IgG antibody to interleukin 6 (IL-6ab) were detected in sera of 71 of 467 normal Danish blood donors (15%). IL-6 bound to the Fab fragments of IL-6ab, and the antibody specifically and competitively interfered with enzyme-linked immunosorbent assays for human IL-6. Only IL-6ab-positive sera interfered with these ELISAs. A statistically positive correlation was found between total IL-6 binding and specific IL-6 binding to serum (P < 0.0001), suggesting that IL-6ab dominates as IL-6 binding factors in normal human serum. The IL-6ab also inhibited binding of IL-6 to receptors on the human U-937 macrophage-like cell line, the human U-266 myeloma cell line and the mouse hybridoma cell line B13.29, clone B9 (B9 cells). IL-6-induced proliferation of the B9 cells was competitively inhibited by IL-6ab. We conclude that sera of normal individuals may contain appreciable levels of autoantibodies to IL-6. These IgG autoantibodies may be physiologically and pathophysiologically important because they are potent inhibitors of IL-6 in vitro.

Serum-induced suppression of interferon (IFN) activity. Lack of evidence for the presence of specific autoantibodies to IFN-alpha in normal human sera

IgG antibodies binding to different IFN species have been described in sera of healthy and diseased individuals. Human serum immunoglobulins have also been shown to interfere with IFN bioactivity. To characterize these antibodies, human recombinant IFN-alpha 2A (rIFN-alpha) was radioiodinated, and ligand binding studies were performed in human sera as well as on the human cell line A-549 in the presence of human serum. 125I-rIFN-alpha bound to serum factors of healthy individuals. However, less than 3% of the binding was to IgG and the binding was non-saturable and therefore most likely non-specific. 125I-rIFN-alpha bound to receptors on A-549 cells, and the ligand-receptor complexes appeared to internalize. However, both cell binding and internalization of 125I-rIFN-alpha were independent of the presence of human serum. We conclude that normal human sera do not contain detectable autoantibodies to rIFN-alpha.