Characterization of the natural killer cell activity in Hashimoto's and Graves' diseases

Natural killer (NK) cell activity and blood mononuclear cell subpopulations were characterized in patients with Hashimoto's thyroiditis ( n = 11), Graves' disease ( n = 20), non-toxic goitre ( n = 10) and in normal controls ( n = 22). NK cell activity against K 562 target cells and the capability of IFN-α, Il-2, and indomethacin to enhance NK cell activity in vitro did not differ significantly between the groups. The percentages of large granular lymphocytes, CD5 +, CD4 +, CD8 + and CD16 + cells were normal in patients with non-toxic goitre, Hashimoto's and Graves' diseases. There was no correlation between NK cell activities and TgAb, MAb and TSAb. Although NK cell activity is suppressed in several autoimmune diseases, NK cell function is normal in patients with autoimmune thyroid disorders.     

IgA class and subclass thyroid auto-antibodies in Graves' disease and Hashimoto's thyroiditis

The reported prevalence of IgA class thyroid antibodies in Hashimoto's thyroiditis is variable and the IgA subclass distribution in unknown, despite recent reports of IgG subclass restriction in the thyroid auto-antibody response. Using an ELISA, IgA class antibodies were found against thyroglobulin (Tg) and microsomes (Mic) in 40-52% of patients with Graves' disease and Hashimoto's thyroiditis, and, against thyroglobulin, they were detected in the absence of IgG antibodies in 10% of the cases. Both IgA1 and IgA2 subclasses were detected in all patients with IgA class antibodies, although a significantly higher proportion of IgA2 relative to IgA1 was found in microsomal compared with thyroglobulin antibodies. In view of the high turnover rate and unique complement-fixing properties of IgA2 antibodies, this class of thyroid auto-antibody may play an important role in determining the response in thyroid auto-immunity.     

The contribution of non-MHC genes to susceptibility to autoimmune diseases.

Genetic studies of experimental models of autoimmune diseases, including systemic lupus-like syndromes and organ-specific autoimmunity, provide major information on genetic control of autoimmune diseases. In addition to genes known to be linked to the major histocompatibility complex (MHC), these studies point to multiple genes located outside the MHC that influence the onset and the progression of autoimmune diseases. Identification of these genes and of their interrelationships is now a major task that will be facilitated by recent progress in molecular biology and gene mapping. Among candidate genes, antigen-receptor genes (i.e., immunoglobulin- and T-cell receptor genes) most likely contribute an important part of the autoimmune susceptibility in several of these animal models. Available linkage data suggest a similar involvement of these antigen-receptor genes in several human autoimmune diseases. In addition to a better understanding of pathogenic mechanisms associated with autoimmunity, the knowledge of these disease-predisposing genes is expected to permit a better classification of often complex syndromes as well as the design of new treatments.     

Analysis of HLA class II genes in Hashimoto's thyroiditis reveals differences compared to Graves' disease

Graves' disease (GD) and Hashimoto's thyroiditis (HT) represent the commonest forms of autoimmune thyroid disease (AITD) each presenting with distinct clinical features. Progress has been made in determining association of HLA class II DRB1, DQB1 and DQA1 loci with GD demonstrating a predisposing effect for DR3 (DRB1(*)03-DQB1(*)02-DQA1(*)05) and a protective effect for DR7 (DRB1(*)07-DQB1(*)02-DQA1(*)02). Small data sets have hindered progress in determining HLA class II associations with HT. The aim of this study was to investigate DRB1-DQB1-DQA1 in the largest UK Caucasian HT case control cohort to date comprising 640 HT patients and 621 controls. A strong association between HT and DR4 (DRB1(*)04-DQB1(*)03-DQA1(*)03) was detected (P=6.79 x 10(-7), OR=1.98 (95% CI=1.51-2.59)); however, only borderline association of DR3 was found (P=0.050). Protective effects were also detected for DR13 (DRB1(*)13-DQB1(*)06-DQA1(*)01) (P=0.001, OR=0.61 (95% CI=0.45-0.83)) and DR7 (P=0.013, OR=0.70 (95% CI=0.53-0.93)). Analysis of our unique cohort of subjects with well characterized AITD has demonstrated clear differences in association within the HLA class II region between HT and GD. Although HT and GD share a number of common genetic markers this study supports the suggestion that differences in HLA class II genotype may, in part, contribute to the different immunopathological processes and clinical presentation of these related diseases.     

Autoimmune thyroid diseases: genetic susceptibility of thyroid‐specific genes and thyroid autoantigens contributions

Autoimmune thyroid diseases are common polygenic multifactorial disorders with the environment contributing importantly to the emergence of the disease phenotype. Some of the disease manifestations, such as severe thyroid‐associated ophthalmopathy, pretibial myxedema and thyroid antigen/antibody immune complex nephritis are unusual to rare. The spectrum of autoimmune thyroid diseases includes: Graves’ disease (GD), Hashimoto's thyroiditis (HT), atrophic autoimmune thyroiditis, postpartum thyroiditis, painless thyroiditis unrelated to pregnancy and thyroid‐associated ophthalmopathy. This spectrum present contrasts in terms of thyroid function, disease duration and spread to other anatomic location. The genetic basis of autoimmune thyroid disease (AITD) is complex and likely to be due to genes of both large and small effects. In GD the autoimmune process results in the production of thyroid‐stimulating antibodies and lead to hyperthyroidism, whereas in HT the end result is destruction of thyroid cells and hypothyroidism. Recent studies in the field of autoimmune thyroid diseases have largely focused on (i) the genes involved in immune response and/or thyroid physiology with could influence susceptibility to disease, (ii) the delineation of B‐cell autoepitopes recognized by the main autoantigens, thyroglobulin, thyroperoxidase and TSH receptor, to improve our understanding of how these molecules are seen by the immune system and (iii) the regulatory network controlling the synthesis of thyroid hormones and its dysfunction in AITD. The aim of the present review is to summarize the current knowledge regarding the relation existing between some susceptibility genes, autoantigens and dysfunction of thyroid function during AITD.     

Identification of apoptotic proteins in thyroid gland from patients with Graves' disease and Hashimoto's thyroiditis

Apoptosis, i.e. natural programmed cell death, is a physiological phenomenon indispensable for normal functioning of the organism. The signal to apoptosis can be started practically in any cell. Disturbances in the apoptosis regulation determine the essential link of the pathogenesis of many diseases, including autoimmune thyroid disorders.

The aim of the study was to assess the expression of Fas/FasL and caspase eight in the tissues of the thyroid gland in patients with Graves' disease (GD), non-toxic nodular goiter (NTNG) and Hashimoto's thyroiditis (HT). The analysis of Fas/FasL expression was performed by western blot and immunohistochemical investigation with DAB-visualization and Mayer's hematoxylin staining. Caspase-8 expression in thyroid follicular cells was assayed by western blot method.

Identification of the proapoptotic proteins FasL and Fas exhibited their pronounced expression in the thyroid tissue in GD patients (++; ++) and HT (+++; +++) as compared to the NTNG group (0/+; 0/+). Among the study groups, the expression of caspase-8 was revealed in band 55 kDa from patients with autoimmune thyroid diseases.

In GD patients, the percentage of thyrocytes with FasL expression correlated positively with TRAb (R = 0.58, p < 0.02). However, no such correlations were noted in HT or non-toxic multinodular goiter. There were no significant correlations between thyroid hormones and the percentage of thyrocytes with Fas and FasL expression.

In conclusion, our findings suggest that the changes in the expression of apoptotic molecules on the surface of T lymphocytes and thyroid follicular cells in patients with autoimmune thyroid disorders reflect their substantial involvement in the pathogenesis of GD and HT. In addition, analysis of Fas/FasL and caspase-8 expression in thyroid tissue may indicate the disease activity and immunological phenotype.     

Identification of apoptotic proteins in thyroid gland from patients with Graves' disease and Hashimoto's thyroiditis

Apoptosis, i.e. natural programmed cell death, is a physiological phenomenon indispensable for normal functioning of the organism. The signal to apoptosis can be started practically in any cell. Disturbances in the apoptosis regulation determine the essential link of the pathogenesis of many diseases, including autoimmune thyroid disorders. The aim of the study was to assess the expression of Fas/FasL and caspase eight in the tissues of the thyroid gland in patients with Graves' disease (GD), non-toxic nodular goiter (NTNG) and Hashimoto's thyroiditis (HT). The analysis of Fas/FasL expression was performed by western blot and immunohistochemical investigation with DAB-visualization and Mayer's hematoxylin staining. Caspase-8 expression in thyroid follicular cells was assayed by western blot method. Identification of the proapoptotic proteins FasL and Fas exhibited their pronounced expression in the thyroid tissue in GD patients (++; ++) and HT (+++; +++) as compared to the NTNG group (0/+; 0/+). Among the study groups, the expression of caspase-8 was revealed in band 55 kDa from patients with autoimmune thyroid diseases. In GD patients, the percentage of thyrocytes with FasL expression correlated positively with TRAb (R = 0.58, p < 0.02). However, no such correlations were noted in HT or non-toxic multinodular goiter. There were no significant correlations between thyroid hormones and the percentage of thyrocytes with Fas and FasL expression. In conclusion, our findings suggest that the changes in the expression of apoptotic molecules on the surface of T lymphocytes and thyroid follicular cells in patients with autoimmune thyroid disorders reflect their substantial involvement in the pathogenesis of GD and HT. In addition, analysis of Fas/FasL and caspase-8 expression in thyroid tissue may indicate the disease activity and immunological phenotype.     

Lymphocyte blastogenic response to human thyroglobulin in Graves' disease, Hashimoto's thyroiditis, and metastatic thyroid cancer.

In view of the past contradictory reports concerning in vitro lymphocyte transformation induced by human thyroglobulin (Tg) in thyroid diseases, the present study was undertaken to re-examine the response using improved methods in cell separation, culture, and cell harvesting. It has been found that the optimal dose level of Tg for maximal blastogenesis in culture differs from patient to patient. Consequently, it is inappropriate to use a single dose level of Tg for evaluation of the blastogenesis in study groups. By using serial Tg dose levels of 0.5 through 30 micrograms/ml in cultures, it was found that that incidence of positive responders in Graves' disease was 69.2%, in Hashimoto's thyroiditis 71.4%, and in healthy controls 9.1%. Metastatic thyroid cancer patients responded in a 50% incidence. All of the positive responders in the cancer group had elevated Tg levels, but no anti-Tg antibody in their sera.     

The etiology of autoimmune thyroid disease: A story of genes and environment

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto's thyroiditis (HT) are prevalent autoimmune diseases, affecting up to 5% of the general population. Autoimmune thyroid diseases arise due to complex interactions between environmental and genetic factors. Significant progress has been made in our understanding of the genetic and environmental triggers contributing to AITD. However, the interactions between genes and environment are yet to be defined. Among the major AITD susceptibility genes that have been identified and characterized is the HLA-DR gene locus, as well as non-MHC genes including the CTLA-4, CD40, PTPN22, thyroglobulin, and TSH receptor genes. The major environmental triggers of AITD include iodine, medications, infection, smoking, and possibly stress. Recent data on the genetic predisposition to AITD lead to novel putative mechanisms by which the genetic–environmental interactions may lead to the development of thyroid autoimmunity.     

The concept of specific immune treatment against autoimmune diseases

Copolymer 1 (Cop 1, Copaxone) is a synthetic amino acid copolymer effective in suppression of experimental allergic encephalomyelitis (EAE). The suppressive effect of Cop 1 in EAE is not restricted to a certain species, disease type or encephalitogen used for EAE induction. In phases II and III clinical trials Cop 1 was found to slow progression of disability and reduce the relapse rate in exacerbating-remitting multiple sclerosis (MS) patients. To extend this concept we have more recently shown that a similar approach is possible in the case of myasthenia gravis. We used two myasthenogenic T cell epitopes of the human acetylcholine receptor alpha-subunit and demonstrated that they are capable of triggering peripheral blood lymphocytes of the majority (>80%) of myasthenic patients tested. Both single amino acid analogs, and a dual analog composed of the tandemly arranged two single amino acid analogs were able to inhibit in vitro proliferative responses of T cell lines, and in vivo priming of lymph node cells. The dual analog inhibited experimental autoimmune myasthenia gravis even when the mice were treated fourteen days after the injection of the pathogenic T cell line.     

The Contribution of Immune Regulatory and Thyroid Specific Genes to the Etiology of Graves' and Hashimoto's Diseases

The autoimmune thyroid diseases (AITD) are complex diseases which are caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility in combination with external factors (e.g. dietary iodine) are believed to initiate the autoimmune response to thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence on the development of AITD. Various techniques have been employed to identify the genes contributing to the etiology of AITD, including candidate gene analysis and whole genome screening. These studies have enabled the identification of several loci (genetic regions) that are linked with AITD, and in some of these loci putative AITD susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD) and Hashimoto's thyroiditis (HT) and some are common to both diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune modifying genes (e.g. HLA, CTLA-4) and thyroid specific genes (e.g. TSHR, Tg). Most likely these loci interact and their interactions may influence disease phenotype and severity.     

The effects of HLA class II genes on the susceptibility to autoimmune thyroid diseases

Immunogenetic factors such as HLA, C4, T cell receptor and immunoglobulin allotypes were investigated in 115 Japanese patients with Graves' disease. The patients showed strong positive association with HLA-A2 (R.R. = 3.45, chi 2 = 14.93, Pc less than 0.002), Bw46 (R.R. = 6.47, chi 2 = 16.25, Pc less than 0.002), Cw11 (R.R. = 4.47, chi 2 = 9.19, Pc less than 0.04) and DRw8 (R.R. = 2.22, chi 2 = 5.62, P less than 0.03, Pc: n.s.) which form one of the typical HLA haplotypes in Japanese population due to the strong linkage disequilibria. On the other hand, the patients showed negative association with HLA-B7 (R.R. = 0.15, chi 2 = 7.15), Bw52 (R.R. = 0.24, chi 2 = 7.86), DR1 (R.R. = 0.07, chi 2 = 9.71) and DQw1 (R.R. = 0.45, chi 2 = 5.62), which form HLA-B7-DR1-DQw1 and Bw52-DR2-DQw1 haplotypes. Because HLA-A2 -Bw46-Cw11-DR9 haplotype was reported to be associated with Chinese Graves' patients, and because Bw46 showed the strongest association with the Japanese patients, it was suggested that HLA class 1 antigen, Bw46, might be the primary immunogenetic factor involved in the pathogenesis of Graves' disease. Since HLA-DQw6 was reported to be associated negatively with Hashimoto's thyroiditis as same as the current observation in Graves' disease, it was suggested that HLA-DQw6 may determine the resistance to autoimmune thyroiditis. The effect of HLA-DQw6 gene, therefore, on the experimental autoimmune murine thyroiditis (EAMT) was examined, using DQw6-transgenic mouse. F1 with C3H mouse, and backcross progeny between the F1 and C3H mouse which is a susceptible strain to EAMT. The measurement of anti-thyroglobulin antibody indicated that C3H mouse, (C3H x DQ-B6) F1 and backcross progeny between the F1 and C3H were high responders to the thyroglobulin, but that B6 mouse and DQ-B6 mouse were low responders. The histological examination of the thyroid gland of these mice failed to demonstrate the significant difference in susceptibility to EAMT among these mice. These results suggested that the immune response to the thyroglobulin was controlled by H-2k haplotype and that the effect of HLA-DQw6 gene on the immune response to thyroglobulin and on the autoimmune thyroiditis was marginal.     

Role of immune complexes in thyroid diseases

Institute of Biochemistry, Academy of Sciences of the Uzbek SSR, Tashkent. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. A. Pankov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 2, pp. 168–170, February, 1992.     

The production and characterization of thyroid-derived T-cell lines in Graves' disease and Hashimoto's thyroiditis

Although the thyroid gland itself is a major site of the autoimmune response, the study of T-cell function in autoimmune thyroid disease has usually relied on peripheral blood as a source of cells. In this study, we have established thyroid-derived T-cell lines from six patients with Graves' disease and one patient with Hashimoto's thyroiditis by culturing the thyroid lymphocytes on an autologous thyroid follicular cell monolayer in the presence of exogenous interleukin 2 (IL-2). These T-cell lines have allowed in vitro investigation of thyroid-derived T-cell function, an approach which was previously limited by the number of lymphocytes obtained from the gland. The lines were predominantly OKT3, OKT4, and HLA-DR positive but showed heterogeneous proliferative responses. Some lines gave autologous or allogeneic mixed lymphocyte reactions but other did not. Only one of the seven lines responded well to the thyroid antigens thyroglobulin and microsomes presented by autologous monocytes. However, six of the lines proliferated in the presence of live but not dead autologous thyroid follicular cells, particularly when interferon-gamma (IFN-gamma) was added. This treatment has been shown to enhance HLA-DR and -DQ antigen expression by thyroid follicular cells in vitro. Furthermore, the proliferation induced by IFN-gamma-treated thyroid follicular cells was increased when thyroglobulin was also added. Together these results support the hypothesis that the expression of Ia antigens such as HLA-DR by thyroid follicular cells in autoimmune thyroid disease may be important in enhancing the autoimmune response, conferring on these cells the ability to present thyroid autoantigens to T cells. The use of thyroid-derived T-cell lines should permit a more detailed evaluation of the disordered immuno-regulation in Graves' disease and Hashimoto's thyroiditis than has been possible previously.     

Antigen specific immune response potential and HLA typing of Israeli patients with thyroid autoimmune diseases (TAD).

The immune response potential to the synthetic polypeptide antigen (T,G)-A--L was studied in 35 patients with thyroid autoimmune diseases (TAD). For this purpose the ability of their antigen activated peripheral blood lymphocytes (PBL) to generate a (T,G)-A--L specific helper factor was tested. In addition, the patients were typed for their HLA determinants. The results of the study have shown that 20/35 (57%) patients responded to (T,G)-A--L, a similar proportion to that found among healthy donors that were tested as control. No significant difference was found in the rate of responses between patients with Graves' disease and Hashimoto's thyroiditis. The responses in these groups of patients were shown to be 13/22 (59%) and 7/13 (54%) respectively. HLA typing of 26 patients with TAD did not demonstrate any association of the disease or the immune response potential with any specific HLA determinant. It is proposed that unlike the general lack of regulation that we have previously observed in patients with systemic lupus erythematosus, the abnormal autoimmune reaction in TAD and probably in other organ-specific autoimmune diseases, is towards a specific organ without affecting other arms and functions of the immune system.     

The contribution of proteinase inhibitors to immune defense

The colonization of a potential host by a parasite requires an ability to cross the integuments and then to escape from the host immune defenses. Proteinases are important virulence factors that assist these processes. Host proteinase inhibitors potentially contribute to immunity by inactivating the proteinase virulence factors of pathogens.