In vitro production of interferon-gamma by peripheral blood from patients with Graves' disease, Hashimoto's thyroiditis and rheumatoid arthritis

Immunomodulatory Properties of Adipose-Derived Stem Cells Treated with 5-Azacytydine and Resveratrol on Peripheral Blood Mononuclear Cells and Macrophages in Metabolic Syndrome Animals

Endocrine disorders, including equine metabolic syndrome (EMS), are a serious issue in veterinary medicine and horse breeding. Furthermore, EMS was shown to affect the cytophysiological properties of adipose-derived stem cells, reducing their therapeutic potential. However, it was shown that those cells can be rejuvenated while using a combination of two chemicals: 5-azacytydine (AZA) and resveratrol (RES). In the present study, we decided to evaluate the immunomodulatory properties of AZA/RES-treated adipose-derived stem cells (ASC) isolated from EMS horses (ASCEMS). Thus, we co-cultured ASC with peripheral blood mononuclear cells (PBMC) and RAW264.7 macrophages. Most attention was placed on regulatory T lymphocytes (TREG), as well as the messenger RNA (mRNA) and protein levels of several cytokines (tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-10, and IL-1β). Moreover, we also investigated the expression of genes related to auto- and mitophagy in both PBMCs and ASCs. PBMCs were obtained from healthy and EMS-suffering individuals and were co-cultured with ASCs that were isolated from healthy and EMS horses cultured in control conditions and with AZA/RES. We discovered that cells treated with AZA/RES increase the TREG number while co-cultured with PBMCs. Moreover, the co-culture of PBMCs with AZA/RES-treated ASCEMS induced mitophagy in PBMCs. Furthermore, ASCEMS pre-treated with AZA/RES displayed anti-inflammatory properties, as decreased levels of TNF-α, nitric oxide (NO), and IL-6 were observed in those cells in comparison with their untreated counterparts in the co-culture with RAW264.7 macrophages. In summary, we demonstrated that ASCEMS treated with AZA/RES displayed increased anti-inflammatory properties, and was able to regulate and activate the TREG-related anti-inflammatory response.

Complement activation by direct C4 binding to thyroperoxidase in Hashimoto's thyroiditis

Biosynthesis of thyroid hormones is an oxidative process that generates reactive oxygen species (ROS) and involves thyroperoxidase (TPO) that is one of the main autoantigens involved in autoimmune thyroid diseases. The ectodomain of TPO consists of a large N-terminal myeloperoxidase-like module followed by a complement control protein (CCP)-like module and an epidermal growth factor-like module. The presence of these two additional gene modules suggests that they may play some crucial, hitherto unsuspected role associated with thyroid function. Because the CCP module is a constituent of the molecules involved in the activation of C4 complement component, we investigated the possibility that C4 may bind to TPO and activate the complement pathway in autoimmune conditions. We showed that TPO via its CCP module directly activated complement without any mediation by Ig. We suggested that this additional complement pathway requires the production of ROS and specially hydroxyl radicals that aggregate TPO and oxidize methionines of C4. Moreover, we found, in patients with Hashimoto's thyroiditis, that thyrocytes overexpress C4 and all the downstream components of the complement pathway. These results indicate that TPO has some as yet unknown function, which may contribute along with other mechanisms to the massive cell destruction observed in Hashimoto's thyroiditis. Investigating this complement pathway, therefore, would provide an excellent means of reaching a better understanding of the etiology of other degenerative diseases.

The effect of adding a surfeit of autologous CD8+ T cells to SCID mice after secondary rexenografts of Graves' thyroid tissue

To investigate the effect of adding a surfeit of CD8+ T cells as a potential immunoregulator in Graves' disease (GD), thyroid tissues from 4 patients with GD and 2 normal subjects (N) were initially xenografted into nude mice. Eight weeks after xenografting, the thyroid tissues, which were then devoid of lymphocytes and appeared normal, were retrieved from the nude mouse, and rexenografted (rexenografts) into severe combined immuno-deficient (SCID) mice; 20 x 10(6) of autologous peripheral blood mononuclear cells (PMBC) or 20 x 10(6) of CD8(+)-depleted PBMC ("non-CD8 cells," i.e., CD4-enriched PBMC) were simultaneously engrafted into SCID mice with thyroid rexenografts. In addition, 20 x 10(6) of CD8(+)-enriched PBMC ("CD8-doubled" cells, which were prepared to double the percentage of CD8+ T cells compared to that of PBMC) were engrafted into SCID mice with rexenografts from 2 GD and 2 N; finally, 20 x 10(6) of PBMC plus an extra 10 x 10(6) of CD8+ T cells ("extra-CD8 added" cells, total 30 x 10(6) of CD8-enriched cells) were engrafted into separate SCID mice with rexenografts from 2 GD. The reengraftment of GD rexenografts or N rexenografts alone did not result in the detection of thyroperoxidase (TPO)-antibodies (Abs), thyroglobulin (Tg)-Abs, thyroid-stimulating Ab (TSAb) production, human IgG, or lymphocytic infiltration in the xenografts. However, the engraftment of either autologous PBMC or non-CD8 cells from patients with GD and N into SCID mice with rexenografts caused human IgG to become detectable and then rise further in 10 of 17 SCID mice; when human IgG, TPO-Ab, Tg-Ab, and TSAb were quantitated, GD rexenografts plus non-CD8 cells engrafted into SCID mice showed a higher production of each antibody and human IgG than in GD rexenografts plus PBMC, or GD rexenografts plus CD8-doubled cells, or GD rexenografts plus extra "CD8-added" cells. Moreover, when CD8-doubled cells or extra CD8-added cells with rexenografts were engrafted to SCID mice with rexenografts, they showed generally lower production of human IgG and thyroid antibodies compared to SCID mice into which PBMC were engrafted with rexenografts, despite the fact that 50% more cells (30 x 10(6)) were engrafted in the preparations of extra CD8-added cells. In conclusion, CD8+ T cells from patients with GD appeared to suppress the induction of thyroid antibodies, TSAb, and human IgG. The CD8+ cells thus are acting as suppressor or regulatory T cells. Such cells might be important in the pathogenesis of autoimmune thyroid disease.

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.

Thyroid cell survival in coculture with autologous peripheral or intrathyroidal lymphocytes

OBJECTIVE

We have studied lymphocyte induced cytotoxicity and the production of interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha) during coculture of thyrocytes and autologous lymphocytes from patients with Graves' disease and from normal subjects.

PATIENTS

Thyroid tissues and lymphocytes were obtained from 28 patients with Graves' disease and from 9 control subjects.

MEASUREMENTS

Lymphocyte induced cytotoxicity was evaluated on autologous thyrocytes using 5 metabolic tests: the MTT assay, the neutral red uptake, lactate dehydrogenase measurement and glutathione assay. IFN-gamma and TNF-alpha measurements were performed after 1, 5 or 7 days' coculture.

RESULTS

The lymphocytes isolated from peripheral blood (PB lymphocytes) altered the morphology and the metabolism of autologous thyrocytes. The intrathyroidal lymphocytes isolated after Dispase digestion were not toxic whereas mechanically isolated lymphocytes exerted a little toxicity. No difference was seen between Graves' disease and normal cells. The supernatants from cocultures had higher IFN-gamma levels than those from lymphocyte cultures. In coculture, PB lymphocytes secreted more IFN-gamma and TNF-alpha than intrathyroidal lymphocytes. The PB lymphocyte induced cytotoxicity was not due to IFN-gamma and TNF-alpha alone.

CONCLUSION

Peripheral blood lymphocytes are cytotoxic in vitro to autologous thyrocytes whereas intrathyroidal lymphocytes exert little or no cytotoxicity according to their isolation method. The mechanisms of lymphocyte induced toxicity remain to be explained.

Effect of FK-506 on xenografted human Graves' thyroid tissue is severe combined immunodeficient mice

OBJECTIVE

We studied the macrolide antibiotic FK-506, an immunosuppressive agent, in an attempt to ameliorate the lesion of autoimmune thyroid disease in human thyroid tissue xenografted into severe combined immunodeficient (SCID) mice. It was not felt appropriate to employ this agent directly in patients with autoimmune thyroid disease because adequate therapeutic modalities are available and the introduction of new, experimental agents could not be justified. Moreover, the study of the tissue before and after treatment could not have been undertaken directly in patients.

DESIGN

Human thyroid xenografts from four patients with Graves' disease and two normal persons were xenografted into SCID mice. Two weeks after xenografting, human immunoglobulin G (IgG) was detectable in all SCID mice xenografted with Graves' thyroid tissue. Mice were divided into two groups with human IgG levels similar to each other. Mice in the first group were treated with FK-506 daily for 6 weeks; mice in the second (similar) group were given phosphate-buffered saline (PBS) only (control group).

MEASUREMENTS

Blood samples were taken every 2 weeks from the tail veins for human IgG, thyroid stimulating antibody, thyroperoxidase antibodies, thyroglobulin antibodies, and interferon-gamma (IFN-gamma). After 8 weeks treatment, animals were sacrificed; thyroid tissue was examined histologically and for thyrocyte HLA-DR expression. FK-506 was also added to thyrocytes in in-vitro tissue culture conditions.

RESULTS

After 4-6 weeks of FK-506 therapy, human IgG, all thyroid antibodies and IFN-gamma were suppressed, while the levels remained elevated in the control group. Lymphocytic infiltration virtually disappeared in the human thyroid tissue of the FK-506-treated mice and thyrocyte HLA-DR expression markedly declined; in the control mice, lymphocytic infiltration remained heavy and HLA-DR expression remained high. On the other hand, FK-506 added directly to thyrocytes in vitro (without lymphocytes) did not reduce thyrocyte HLA-DR expression.

CONCLUSIONS

FK-506 appears to suppress the activation of intrathyroidal lymphocytes, but not thyrocytes. From these observations, it is concluded that this agent, by its action on intrathyroidal lymphocytes, is able to ameliorate the immunologically mediated histological and serological disturbance in human autoimmune thyroid disease, at least under these circumstances.

Reduced activation of suppressor T lymphocytes by specific antigens in autoimmune thyroid disease

In order to study the activation of suppressor T lymphocytes by thyroid-specific antigens in autoimmune thyroid disease (AITD), we have investigated the effects of the organ-specific antigens, thyroperoxidase (TPO), thyroglobulin (Tg), and thyroid microsomal antigen (TMc), as well as renal microsomes (RMc) as a control antigen, on the activation of suppressor T lymphocytes; this was accomplished by measuring major histocompatibility complex class II (HLA-DR) expression on their surfaces by flow cytometric analysis. Peripheral blood mononuclear cells (PBMC), obtained from 33 patients with Graves' disease (GD), 26 with Hashimoto's thyroiditis (HT), 5 with nontoxic nodular goiter (NTG), and 30 normal persons (N), were cultured for 7 days in the presence or absence of TPO, Tg, or RMc at final concentration of 10, 100, and 1000 ng/ml. Cultured cells were stained with fluorescent-conjugated monoclonal antibodies (anti-CD8, anti-CD11b, and anti-HLA-DR), and the activation of CD8+ and CD8+CD11b+ (pure suppressor) T cells by the antigens was analyzed on a flow cytometer. In the absence of antigen, i.e., the autologous mixed lymphocyte reaction (AMLR), CD8+ and CD8+CD11b+ T lymphocytes from patients with GD and HT showed significantly lower activation as compared to N. We measured the Stimulation Index (Sl) of activated T lymphocytes to compare antigen-specific activation between CD8+ and CD8+CD11b+ cells from normal persons and patients. With stimulation of 100 and/or 1000 ng/mL of TPO or Tg, Sl of activated CD8+ cells was significantly (p < 0.05 to 0.01) lower in GD and HT as compared with N.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro secretion of interleukin-1 beta and interferon-gamma by peripheral blood lymphomononuclear cells in diabetic patients

There is evidence that cytokines, in particular interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma) might mediate beta cell destruction in type 1 diabetes. Therefore the secretion of these cytokines by peripheral blood lymphomononuclear cells (PBMNC) was investigated in basal conditions and 48 h after stimulation with T-cell mitogen phytohaemagglutinin (PHA) in 33 diabetic patients and in 10 normal controls. The patients were divided in 4 groups (Group 1, 10 controls; Group 2, 13 newly diagnosed type 1 diabetics, the onset had occurred from 5 days to 3 months before the study; Group 3, 10 Long Standing (LS) type 1 diabetics with duration of the disease between 2 years and 10 years; and Group 4, 10 type 2 diabetics). No difference was found among the 4 groups considered in IL-1 beta secretion by unstimulated cultures, although the percentage of TAC+ cells was significantly higher in type 1 newly diagnosed diabetic patients with respect to the LS, the type 2 diabetics and the controls. After PHA stimulation a significant increase of IL-1 beta was found in newly diagnosed type 1 diabetic patients in comparison with the control subjects, the LS and type 2 diabetic patients (P < 0.001). The supernatants of newly diagnosed type 1 diabetics also showed a significant reduction in IFN-gamma production both in basal (P < 0.01) and in stimulated conditions (P < 0.001) in comparison with the controls, the LS (P < 0.002 in basal, and P < 0.001 in stimulated conditions) and the type 2 diabetic patients (P < 0.001 both in basal and stimulated conditions).(ABSTRACT TRUNCATED AT 250 WORDS)

Pathogenesis of autoimmune hypothyroidism induced by lymphokine-activated killer (LAK) cell therapy: in vitro inhibition of human thyroid function by interleukin-2 in the presence of autologous intrathyroidal lymphocytes

Lymphokine-activated killer (LAK) cell therapy frequently results in primary hypothyroidism. To elucidate the responsible mechanism, we investigated the effects of interleukin-2 (IL-2) on thyroid function of cultured human thyroid follicles in the presence or absence of autologous thyroid-derived lymphoid cells (TDLC). Human thyroid follicles, obtained by subtotal thyroidectomy from patients with Graves' disease, were cultured in serum-free medium containing bTSH and various concentrations of human IL-2, with or without TDLC. After 5 days of culture, 125I was added, and after an additional 3 days of culture, 125I incorporated into thyroid follicles and organic 125I (125I-T4 + 125I-T3) released into the culture medium were estimated. In the absence of TDLC, IL-2 did not affect bTSH-induced thyroid function. In the presence of TDLC, however, IL-2 inhibited the bTSH-stimulated thyroid function in a concentration-dependent manner. The minimum IL-2 concentration required to inhibit thyroid function was 1 U/ml. At 100 U/ml, IL-2 inhibited thyroid function completely. IL-2 increased the concentration of IFN-gamma in the culture medium conditioned by TDLC but not by thyroid follicles. When both were cocultured, IL-2 more significantly increased the concentration of IFN-gamma to an extent sufficient for inhibiting thyroid function per se. Furthermore, the addition of anti-IFN-gamma antibody to the medium partially restored the IL-2-inhibited thyroid function. In summary, by coculturing human thyroid follicles and autologous intrathyroidal lymphocytes with IL-2, it was possible to reproduce the thyroid dysfunction associated with LAK cell therapy. Our data indicate that IL-2 inhibits thyroid function, at least partly, by stimulating production of IFN-gamma, a potent inhibitory cytokine for thyroid cells.

Modulation of human T cell functions by surface sulphydryl groups: differential effects on IL-2 production and responsiveness

An impermeable thiol blocker has been used to investigate the role of sulphydryl (SH) groups in the production of and responsiveness to IL-2 by normal human T lymphocytes. Surface SH blockade of mononuclear cells prior to incubation with mitogen (phytohaemagglutinin, concanavalin A, CD3 MoAb) had no effect on production of IL-2 but markedly impaired cellular responsiveness to exogenous IL-2. Studies using MoAbs indicated that this effect was accompanied by decreased expression of both the CD25 and p75 subunits of the IL-2 receptor. Blocking surface SH groups did not affect binding of IL-2 to p75 on unstimulated mononuclear cells, but inhibited binding to high-affinity receptors on a T lymphoma cell line. The data are consistent with the hypothesis that sulphydryl groups on the IL-2 receptor are required for its function and may be involved in the interaction of the CD25 and p75 subunits leading to generation of the high-affinity binding site. The surface thiol identified on the IL-2 receptor may be a candidate for oxidation on cells from patients with chronic inflammatory diseases such as rheumatoid arthritis and thus contribute to the aberrant function of T cells in these patients.

The role of interleukin 2 in the development of autoimmune thyroiditis

Interleukin 2 (IL-2) is a lymphokine that may disrupt immunological self-tolerance. While being incapable of interfering with intrathymic or peripheral clonal deletion, IL-2 may overcome functional antigen unresponsiveness in anergic T lymphocytes. Anergy of T helper cells of the inflammatory phenotype implies selective silencing of the transcription of the IL-2 gene and thus precludes autocrine IL-2/IL-2 receptor (IL-2R) mediated growth, as well as delivery of help to other T cells or B lymphocytes. Thus, IL-2 serves as a servomodulator regulating post-deletional self-tolerance. IL-2-producing and IL-2-receptive cells are present in a variety of autoimmune lesions, including spontaneous autoimmune thyroiditis developing in the Obese strain (OS) of chickens, in Hashimoto's struma lymphomatosa, and in Graves' disease. Whereas the OS is characterized by a hyperinducibility of the IL-2/IL-2R system that predisposes to the development of severe thyroid infiltration, the state of the IL-2/IL-R system in circulating lymphocytes of patients developing thyroid autoimmunity, or at risk of doing so, remains to be defined. The most frequent autoimmune side-effect of IL-2 treatment concerns the thyroid gland. IL-2 induces a lymphoid thyroiditis leading to primary hypothyroidism, especially in those patients that have pre-treatment antithyroid autoantibodies. The hypothesis is extrapolated that IL-2 induces autoimmune disease in those patients that bear undeleted thyroid-specific T cells, and in which the lack of manifest thyroiditis relies upon peripheral, post-deletional tolerance.

A perspective on human autoimmune thyroid disease: is there an abnormality of the target cell which predisposes to the disorder?

It has been suggested recently that autoimmunity could be regarded as a physiological response of the normal immune system to autoantigens caught up in an inflammatory response to viral or bacterial antigen expressed in the target tissue. Other theories to explain autoimmunity include molecular mimicry whereby a viral or microbial hapten similar to an autoantigen initiates the production of autoantibodies that cross react with an autoantigen, with a subsequent immune response reacting with autologous cell structures which are homologous with the particular microorganism. There has also been a suggestion that there may be a genetic abnormality of the target cell which is necessary for the initiation of autoimmune thyroid disease. The present review examines these proposals and provides evidence against an antigen-driven origin for autoimmune thyroid disease (AITD). Currently, there is no valid evidence for viral involvement, and likewise the evidence for molecular mimicry as an initiating factor does not hold up to scrutiny. While a genetic abnormality of the thyrocyte may be important in certain animal models of AITD, in the human there is no evidence for such an abnormality. Evidence that AITD is derived from a disturbance of immunoregulatory mechanisms has been documented elsewhere and would appear to be the most appropriate explanation for these disorders. The immunoregulatory disturbance itself may be related to an abnormality of the mechanism of specific antigen (i.e. normal autoantigen) presentation to appropriately induce T lymphocytes and that theory will require further illumination.

Studies of CD4+ (helper/inducer) T lymphocytes in autoimmune thyroid disease: demonstration of specific induction in response to thyroid peroxidase (TPO) in vitro and its relationship with thyroid status in vivo

We have studied by flow cytometric analysis the antigen specific activation of CD4+ (helper/inducer) T lymphocytes by purified human thyroid peroxidase (TPO). Peripheral blood mononuclear cells were obtained from 26 patients with Graves' disease (GD), 16 with Hashimoto's thyroiditis (HT), 7 with nontoxic nodular goiter (NG), and 14 normal subjects (N). Cells were cultured for 7 days in the presence or absence of TPO at final concentrations of 3, 30, and 300 ng/mL. When harvested, cells were reacted with an FITC-conjugated anti-CD4 and a PE-conjugated anti-HLA-DR murine monoclonal antibodies. The percentage of HLA-DR+ CD4+ cells (activated CD4+ cells) was determined by a flow cytometer. In the absence of TPO, CD4+ cells had been activated without any specific stimulant. This is known as the autologous mixed lymphocyte reaction (AMLR). In the AMLR, CD4+ cells from GD and HT were less activated compared to those from NG and N. Results of TPO-specific activation were expressed as an incremental increase of activated CD4+ cells (II) (percentage of activated CD4+ cells cultured with TPO minus percentage of activated CD4+ cells cultured without TPO). II of N, GD, HT, and NG were 0.37 +/- 0.21, 2.20 +/- 0.45,** 2.0 +/- 0.66,* and 0.35 +/- 0.27 (mean +/- SEM), respectively (**p less than 0.01; *p less than 0.05 vs N). When patients were further subdivided, the highest mean II was found in patients with hyperthyroid GD (p less than 0.01), followed by euthyroid HT (p less than 0.05) and euthyroid GD (p less than 0.05), however there was no significant difference between hypothyroid HT and N. In conclusion (1) AMLR reactivity of CD4+ cells from GD and HT was impaired, (2) however, CD4+ cells from both GD and HT were significantly more induced by TPO compared to N, and (3) this induction depends, in part, on the in vivo thyroid status.

Interleukin 2-activated killer cells do not mediate autologous thyrocyte lysis in autoimmune thyroid disease in vitro

Because of interest in IL-2, and IL-2-activated killer cell-induced hypothyroidism in humans, we attempted to study an in vitro system that might prove to illuminate this disorder. We have thus studied interleukin 2 (IL-2--0, 12.5, 25, or 50 U/mL) activated killer cell-mediated autologous thyrocyte lysis, as well as cytotoxic activity in IL-2-stimulated mononuclear cell supernatants in 7 patients with autoimmune thyroid disease (2 Graves' disease and 5 Hashimoto's thyroiditis) using the 51Cr release assay. Controls included 14 patients with nonautoimmune thyroid disease (3 nontoxic goiter, 8 follicular thyroid adenoma, 2 papillary thyroid carcinoma, and 1 medullary carcinoma of the thyroid). Soluble IL-2 receptor (sIL-2R) in supernatants of peripheral mononuclear cells stimulated by IL-2 from these patients also was measured. Whereas in the control preparations, IL-2-activated killer cell activity was increased in a dose-dependent fashion relative to the IL-2 concentration, as well as to the effector cell/target cell ratio, in preparations from patients with autoimmune thyroid disease, this activity was not elevated as the IL-2 concentration was increased. The susceptibility of thyrocytes to the lytic effect of IL-2-activated killer cells was higher in controls than that in autoimmune thyroid disease (at concentrations of IL-2 of 0, 12.5, 25, and 50 U/mL) (p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)