Experimental Allergic Thyroiditis Research Articles

Animal models of autoimmune endocrine disease and their uses in developing new methods of intervention

This review provides basic information concerning the major animal models in use for the study of autoimmune endocrine diseases (AEDs). Although several other models exist which parallel human AEDs such as autoimmune orchitis, most research in this area has centred on animal models of insulin-dependent diabetes mellitus (IDDM) and thyroiditis. These models, between them, appear to exhibit most of the disease manifestations of their human counterparts and thereby permit the study of possible methods of intervention in the disease process. While no one model represents a perfect correlation with the human disease it represents, common characteristics are recognizable between them. For instance, the central role of activated T cells in controlling the disease process. The chapter continues by examining the various ways in which models of autoimmunity, specifically IDDM and experimental allergic thyroiditis (EAT), have been used to investigate the possibility of preventing or arresting autoimmune destruction. Several different approaches are described that illustrate the variety of techniques that have proven both potentially, or in reality, effective and those that have proven less efficacious than first hoped.

T-cell vaccination in experimental myasthenia gravis: A double-edged sword

Immunization with antigen-specific T cells has been used successfully in the treatment of several T cell-mediated experimental autoimmune diseases, including experimental allergic encephalomyelitis, thyroiditis, and adjuvant arthritis. The aim of this study was to determine whether T-cell vaccination could be used to down-regulate specifically the antibody response to AChR in experimental autoimmune myasthenia gravis (EAMG), an antibody-mediated disorder. We produced T cells specific for the acetylcholine receptor (AChR) by immunizing Lewis rats with torpedo AChR, harvesting the regional lymph node cells, and restimulating them in vitro with AChR. This cell population was expanded with IL2. The cells were then activated with concanavalin A (Con-A) and exposed to high hydrostatic pressure to augment their immunogenicity. We found that rats vaccinated with these cells did not manifest decreased antibody titers to AChR, when challenged. In fact, the antibody response to AChR was consistently potentiated by the vaccine treatment. This result could not be attributed to antigen carryover by the vaccinating cells or to induction of anti-idiotypic antibodies. Despite these results showing overall enhancement of the AChR antibody response, we found evidence of AChR-specific suppressor cells in the spleens of the vaccinated animals. Our observations indicate that T-cell vaccination can elicit both a positive immune response and a suppressive response in the same animal. If the T-cell vaccination strategy is to be useful for the treatment of MG, methods for amplifying the suppressive effect will need to be developed.

PVG rats, resistant to experimental allergic thyroiditis, develop high serum levels of thyroglobulin after sensitization

Following challenge with rat thyroglobulin and adjuvants, DA rats invariably develop the histological features of severe experimental allergic thyroiditis while the thyroid glands of PVG rats remain histologically normal. It has been reported previously that some PVG rats develop high titers of anti-thyroglobulin antibody when challenged despite apparent resistance to thyroiditis. In the present experiment, PVG rats consistently developed high serum levels of both antibody and thyroglobulin. Although release of thyroglobulin from the thyroid is usually considered an indication of damage to the gland, the thyroid remained completely normal in all challenged PVG rats.

Induction of autoimmunity with dendritic cells: Studies on thyroiditis in mice

The initiation and maintenance of thyroid autoimmunity by professional antigen-presenting cells were assessed by observing thyroiditis and induction of IgG antibodies to thyroglobulin (Tg). Dendritic cells (DC) were purified from spleens of CBA mice and T cells removed with anti-Thy 1 and complement. Some DC were pulsed with 25–500 μg/ml of mouse Tg in vitro and normal syngeneic mice received injections of 10 5 cells intravenously. In untreated animals only 1 thyroid out of 40 showed a lymphocyte infiltrate and antibody to Tg was rarely seen. In animals receiving normal DC without Tg, lymphocyte infiltration was seen 2–6 weeks later in 5 out of 33 thyroids and some animals produced low levels of antibody to thyroglobulin (8 of 33 animals). DC pulsed with 500 μg Tg/ml in vitro caused thyroid infiltration in 6 out of 15 animals but did not increase the incidence of anti-Tg antibodies. Lower doses had no effect. When 10 5 DC were given from animals with experimental allergic thyroiditis (EAT, induced with Tg in complete Freund's adjuvant, CFA) more than half of the recipient animals showed thyroiditis (8 out of 15) and autoantibody production (12 of 15 animals). DC may therefore play a role in the initiation and maintenance of autoimmunity by providing a stimulus for antigen-specific T cells.

Regulation of experimental allergic thyroiditis.

The susceptibility to experimental allergic thyroiditis (EAT) of rats that had previously been immunized against thyroglobulin was examined. Challenge with thyroglobulin 5 weeks previously conferred strong resistance to the induction of EAT after exposure to a sensitization protocol that was otherwise highly effective. Resistance to induction of EAT could also be conferred by the inoculation of spleen cells from thyroglobulin-sensitized donors on the day of birth. Heavily irradiated spleen cells from sensitized donors were able to confer resistance on neonatal recipients, indicating that prolonged survival of the transferred cells was not required.

The relative contributions of immune system and target organ to variation in susceptibility of rats to experimental allergic thyroiditis.

Previous investigations of the cellular basis of genetic susceptibility to experimental allergic thyroiditis (EAT) in semi-allogeneic mice bearing thyroid grafts from resistant, parental strain donors have indicated that these grafts remain relatively resistant to EAT when this is induced in the susceptible bearer. It was concluded that genetic control of susceptibility to EAT is expressed in both the immune system and the thyroid gland. Our experiments in which thyroid grafts were transferred to fully allogeneic, but immunologically tolerant, recipient rats indicate that thyroid tissue from an EAT-resistant strain of rat becomes entirely susceptible when transplanted into a susceptible host. The differing susceptibility of thyroid grafts in semi-allogeneic and tolerant allogeneic hosts may result from restrictions on interaction between host lymphocytes and the graft in the former situation. The present findings call into serious doubt the proposition that genetically determined resistance to EAT is mediated, to any extent, at the level of the target organ.

Lymphocyte locomotion in experimental allergic thyroiditis

Experimental allergic thyroiditis was produced in rats by immunization with homologous thyroglobulin (Tg). The mechanisms of lymphocyte accumulation of the thyroid lesion were analyzed by using this experimental model. The sensitized lymph node cells were cultured with Tg. After 72 hr, the cell-free supernatant was found to contain a chemotactic factor for sensitized lymphocytes. Lymph node lymphocytes from animals immunized 3 weeks previously were the best source of such sensitized lymphocytes while the cells at the latter stage could not produce the factor. The culture supernatant was applied to a Sephadex G-100 gel filtration column. The results indicate that the molecular weight of the factor is around 12,400. Among lymph node lymphocytes, nylon-wool column nonadherent lymphocytes were the most responsive; adherent lymphocytes were not responsive. Thyroglobulin itself did not chemoattract lymphocytes obtained from rats immunized with Tg. This phenomenon was in contrast to macrophage chemotaxis in the same model in which macrophage itself can move toward Tg. In any event, these results seem to indicate that a chemotactic lymphokine may be playing an important role in the pathogenesis of lymphocyte accumulation of the thyroid lesion.

The occurrence of defined idiotypes on autoantibodies to mouse thyroglobulin.

Anti-idiotypic antibodies were raised in rabbits to three monoclonal mouse autoanti-thyroglobulins. Of the idiotypes recognized, one was unique to that monoclonal, while the other two showed evidence of sharing idiotopes with other monoclonal anti-thyroglobulin (TG) idiotypes, the IgM idiotype in particular being found on nearly half of the hybridomas studied. Two of the idiotypes could be detected in the sera of mice with experimental allergic thyroiditis (EAT), but they constituted only a very small percentage of the total anti-TG present. In spite of its low levels in EAT mice the D8 idiotype could be induced by injection of anti-idiotype and TG and in this case it constituted up to 20% of the anti-TG activity in individual mice, showing a strain-related association between the idiotype and autoanti-TG.

Suppression of Experimental Allergic Thyroiditis in Rats Treated with Lithium Chloride

Wistar rats were repeatedly injected with 5 mmol of lithium chloride/kg of body weight before and during sensitization with bovine thyroglobulin in complete Freund’s adjuvant. Treatment with lithium chloride significantly suppressed Arthus and delayed skin hypersensitivity reactions to thyroglobulin, and to a lesser extent production of anti-thyroglobulin antibody and experimental allergic thyroiditis.

Macrophage locomotion in experimental allergic thyroiditis of the rat

Wistar King A rats were immunized with homologous thyroglobulin in complete Freund's adiuvant with pertussis vaccine. The relationship between different parameters of the immune response to thyroglobulin and the inflammatory reaction of the thyroid gland was observed. The severity of thyroiditis reached its peak 3 weeks after immunization in all animals. Regression of both the inflammatory cell reaction and the degree of follicular damage began from the 4th week. Hemagglutinating antibody titer to thyroglobulin reached its peak 3 to 4 weeks after immunization and persisted until the 10th week. Delayed type skin hypersensitivity to thyroglobulin was less well correlated with the degree of thyroiditis. However, the migration inhibition of peritoneal exudate cells by thyroglobulin in vitro correlated with the development of thyroiditis, and approximately 50% inhibition was observed 2 to 5 weeks after immunization. Chemotactic activity of the macrophages to thyroglobulin by the modified Boyden chamber technique was markedly increased in the 3rd week after immunization. No chemotactic response to kidney extract was noticed during the time of observation. These results give a clue to the mechanism of accumulation of macrophages in the thyroid in experimental allergic thyroiditis.

The suppression of the development of experimental thyroiditis and related cellular immunity in the guinea pig following adult thymectomy.

The role of the thymus in the pathogenesis of experimental allergic thyroiditis (EAT) in the guinea pig was studied after the lapse of a sufficiently long period following adult thymectomy. Female Hartley guinea pigs thymectomized or sham-operated at 10 to 12 weeks of age were immunized by a single injection of homologous thyroid extract in complete Freund's adjuvant (CFA) 7 or more months after operation. The animals were sacrificed at 4 or 5 weeks after immunization. Adult thymectomized and subsequently sensitized (ATx-sensitized) animals showed a markedly depressed ability to develop thyroiditis, 18 of the 21 animals having thyroid lesions which could be graded as slight or lower than the sham-operated controls. Delayed skin reaction and macrophage migration inhibitory factor (MIF) production of lymph node cells to thyroid antigen were reduced in the ATx-sensitized animals. On the contrary, enhancement of migration was noted in some of the animals. Anti-thyroid hemagglutinating antibody was not detected in about a quarter of ATx-sensitized animals, in the remainders of which the titers were found to be at the level similar to that of the sham-operated controls. There was a substantial decrease in the percentage of rosette-forming cells (T cells) on unsensitized ATx animals 14 months after operation. Thus, it seems reasonable to conclude that the suppression of the development of thyroiditis and related cellular immunity are a reflection of a decline in peripheral T cell population during the long term after thymectomy, and EAT in the guinea pig is a thymus dependent disease.

Dissociation of MIF activity and in vitro lymphocyte transformation in the development of experimental allergic thyroiditis in guinea pigs.

Macrophage migration inhibitory factor (MIF) activity and in vitro lymphocyte transformation to homologous thyroid antigen were compared in cultures of lymph node cells obtained from 123 guinea pigs at weekly intervals after a single injection of homologous thyroid extracts in complete Freund's adjuvant (CFA). MIF activity was not detectable at the early stage of immunization but became manifest 2 and 3 weeks after sensitization and a high level was maintained during 4-7 weeks. On the other hand, lymphocyte transformation preceded the appearance of MIF activity and attained its maximum 2 weeks after sensitization before the establishment of thyroiditis. It is indicated that MIF activity and lymphocyte transformation predominate separately in the course of immunization. There was a considerable correlation between intensity of MIF activity and severity of thyroiditis in individual animals during the advanced stage (4-6 weeks after sensitization) of the disease. Also, a lower but significant correlation was seen between lymphocyte transformation and severity of thyroiditis. However, about half of animals in the advanced stage of thyroiditis failed to exhibit antigen-stimulated lymphocyte transformation, despite a positive MIF activity.

Studies on Organ Specificity of Experimental Allergic Thyroiditis in Guinea Pigs : I.Histological Comparison of Thyroidal and Extra-Thyroidal Lesions of Thyroiditic Guinea Pigs with Those on Non-Thyroiditic, Sensitized Animals

Studies on Organ Specificity of Experimental Allergic Thyroiditis in Guinea Pigs : I.Histological Comparison of Thyroidal and Extra-Thyroidal Lesions of Thyroiditic Guinea Pigs with Those on Non-Thyroiditic, Sensitized Animals

The Effect of a Long-Term Delay of the Induction of Experimental Allergic Thyroiditis Following Thymectomy in Adult Guinea Pigs on the Development of Disease

The Effect of a Long-Term Delay of the Induction of Experimental Allergic Thyroiditis Following Thymectomy in Adult Guinea Pigs on the Development of Disease

Studies on Organ Specificity of Experimental Allergic Thyroiditis in Guinea Pigs : II.Cellular and Humoral Cross-Reactions between Various Organs

Studies on Organ Specificity of Experimental Allergic Thyroiditis in Guinea Pigs : II.Cellular and Humoral Cross-Reactions between Various Organs

A comparison of autoimmunity and experimental allergic thyroiditis in Strain 2 and Hartley strain guinea pigs

The response of Strain 2 guinea pigs to immunization with thyroid extract in complete adjuvant was compared with the response of the Hartley strain. The Strain 2 did not develop thyroiditis as frequently or in as great a degree as the Hartley strain. This difference in degree of thyroiditis between these two strains occurred consistently even when the animals were immunized with a wide range of doses of thyroid extract and of mycobacteria in adjuvant, and was independent of the strain origin of the antigen used for immunization. Although the Strain 2 made less thyroiditis than the Hartley strain, it made as much agglutinating antibody, and often as much delayed sensitivity as the Hartley strain. The genetic controls regulating autoimminity to the thyroid and production of thyroiditis appear to differ from those regulating production of experimental allergic encephalomyelitis.

Suppression of experimental allergic thyroiditis in guinea pigs by homologeous and heterologeous thyroglobulin.

Guinea pigs with experimental allergic thyroiditis, induced by three intradermal injections of thyroglobulin in complete Freund's adjuvant, were treated by daily injections of thyroglobulin emulsified in incomplete Freund's adjuvant over a period of 12 days. Besides lightmicroscopical, ultrastructural and immunohistochemical studies the serum antibody titers were determined and skin tests for delayed hypersensitivity were performed in all animals. The following results were obtained.

Experimental allergic thyroiditis in rats: Suppression by heterologous (rabbit) antilymphocyte sera to lymph node, thymic, and splenic lymphocytes: Macsween, R. N. M., Ono, K., Bell, P. R. F., Thomason, C. M., and Starzl, T. E.: Clin. Exp. Immun. 6: 273, 1970

Heterologous (rabbit) anti-lymphocyte sera, raised by immunization with rat lymph node, thymic and splenic lymphocytes, have been shown to be of equal potency in suppressing experimental allergic thyroiditis in rats sensitized to allogeneic thyroid–adjuvant emulsion and pertussis vaccine.

Cyclophosphamide Inhibition of Experimental Allergic Thyroiditis and Thyroid Antibody Production in Rats

Discussion and Summary The data (Tables I and II) are remarkably similar to our previous findings in EAE (5, 6) in that injections of CY for 2 weeks after sensitization to thyroid in adjuvant inhibited development of EAT and the production of thyroid antibody. These findings also confirm those of Salvin and Liauw (4) concerning EAT in the guinea pig. The therapeutic effects of CY when the drug was given after the EAT lesions had developed also Table IIInhibition of production of hemagglutinating (HA) anti-thyroid antibody in rats sensitized and injected with cyclophosphamide (CY)Rat StrainCY TreatmentaProportion of Rats with HA Antibody at:b15 days21 daysLewis5 mg/k0/5c0/5None5/54/5CFN (Wistar)5 mg/k0/50/5None5/54/4aDaily intraperitoneal injections of CY in doses of 5 mg/kg beginning on day of sensitization and continued through the 15th day after sensitization.bNumerator, number of rats with HA antibody titers of 1:20 or greater; denominator, number of rats sensitized and tsted for HA antibody.cDays after sensitization. agree with the results we obtained with EAE in Lewis rats (7). It is noteworthy that the lesions of EAT did not recur after CY was stopped, in contrast to the relatively prompt recrudescence of EAE under similar therapeutic conditions (manuscript in preparation). The inhibitory effect of CY on the production of anti-thyroid antibody (Table II) provides evidence that this alkylating drug has an immunosuppressive effect on the immune response to thyroid antigens and that CY-induced inhibition of the disease has an immunologic rather than an anti-inflammatory basis. We do not consider that the inhibitory effect of CY on HA antibodies is related causally to its inhibitory effect on EAT. There is no evidence that circulating antibodies against thyroid antigens play a role in EAT in rats. Actually, the available data favor a cell-mediated pathogenesis in this species and in guinea pigs (10–12). Reported serum transfers of EAT in guinea pigs (13) and rabbits (14, 15), however, suggest that thyroid antibodies may well be important in other animal species. Whatever the nature of the primary immune factor responsible for EAT may be in rats, CY has a profound capacity to suppress or inhibit the immunologic response to thyroid antigen. As discussed in our previous work (5–7) and by Many and Schwartz (16), the inhibitory effect of CY probably is due to elimination of rapidly proliferating antigen-reactive cells. The basis for the therapeutic effect of CY is less clear, but is likely to be due to action of the drug on inflammatory cells entering the thyroid glands, which have been shown by Kosunen and Flax (17) to be of hematogenous origin.

The effect of suppression of endogenous thyroid-stimulating hormone secretion on experimental allergic thyroiditis in the guinea-pig.

The effect of suppression of endogenous thyroid-stimulating hormone secretion on experimental allergic thyroiditis in the guinea-pig.