Thyroid function in mice with experimental autoimmune thyroiditis.

Mice of strains high and low responders to thyroglobulin were immunized with mouse thyroglobulin emulsified in Freund's complete adjuvant. Groups of mice were killed at weekly intervals and the serum thyroxine concentration was measured with a solid-phase RIA while the titre of thyroglobulin antibodies was determined by passive haemagglutination and the magnitude of thyroid infiltration with mononuclear cells was scored. In other groups of mice, similarly immunized, radioactive iodine uptake was measured at various times after immunization. In almost all mice the lowest level of thyroxine and the lowest radioiodine uptake were observed 2 weeks after immunization. There was no clear relationship between the thyroid function and the titre of thyroglobulin antibodies or the extent of the cellular infiltrates in the thyroid.     

Induction of experimental autoimmune thyroiditis in B cell-depleted mice

The effect of B cell depletion on the induction and severity of murine experimental autoimmune thyroiditis was investigated. Thirteen CBA mice were given repeated intraperitoneal doses of 700 micrograms purified rabbit anti-mouse Ig antibody from 24 hours to 8 weeks after birth. Controls were given normal rabbit IgG (14 mice) or were left uninjected (10 mice). At six weeks all mice received two doses of 70 micrograms murine thyroid extract in complete Freund's adjuvant. Only 2/13 of the anti-Ig treated mice were fully B cell-deficient as determined by serum IgM, spleen cell immunofluorescence and responsiveness to LPS; however, the levels of anti-thyroglobulin autoantibodies were very low in 7/13 mice. The results demonstrate that thyroiditis can be actively induced in the absence of B cells and autoantibodies but that B cells may play a role in increasing disease severity.     

Adhesion molecule monoclonal antibodies inhibit experimental autoimmune thyroiditis.

To examine the role played by adhesion molecules in thyroid autoimmunity, we have assessed the effect of administering monoclonal antibodies (mAb) against intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) in experimental autoimmune thyroiditis, induced by immunizing rats with thyroglobulin in complete Freund's adjuvant. The antibody against LFA-1, but not against ICAM-1, reduced thyroglobulin antibody production (P < 0.01) and both antibodies caused a significant reduction (P < 0.002) in the severity of the thyroidal lymphocytic infiltration. In vitro, both mAb impaired the proliferative response of splenic and lymph node T cells to thyroglobulin, but only the antibody against LFA-1 reduced thyroid cell killing assessed using splenic lymphocytes as effectors. Monoclonal antibodies against both these adhesion molecules appear to inhibit cell-mediated autoimmunity in vivo, but only the LFA-1 mAb reduced the autoantibody response.     

Spontaneous development of autoimmune uveoretinitis in nude mice following reconstitution with embryonic rat thymus.

This paper describes the spontaneous occurrence of an autoimmune uveoretinitis in nude (nu/nu) mice reconstituted when 4 weeks old by the grafting of rat embryonic thymus. The uveoretinitis was characterized histologically by progressive loss of the photoreceptor layer, observed in 4.0, 17.6, 42.9% and 71.4% of such mice at 3, 5, 7 and 12 months of age, respectively. Mice with uveoretinitis were shown to have serum IgG antibody reactive by indirect immunofluorescence with retinal photoreceptors, and with interphotoreceptor retinoid-binding protein (IRBP), but not retinal S-antigen, by immunoblotting and ELISA. A uveoretinitis could be adoptively transferred to syngeneic ungrafted nude mice by splenic CD4+ T cells from diseased animals. This is the first experimental model of a (T cell mediated) autoimmune uveoretinitis which develops spontaneously and which is not dependent upon deliberate sensitization with retinal antigens and adjuvants.     

T细胞疫苗抑制自身免疫性甲状腺炎的发生

目的　研究T细胞疫苗 (TCV)在小鼠实验性自身免疫性甲状腺炎 (EAT)发生中的阻断作用及可能机制。方法　磁珠分离CD4 T细胞 ,体外活化 ,戊二醛处理获得T细胞疫苗 ,体内接种EAT小鼠。通过EAT评价、细胞因子测定及细胞增殖试验了解TCV对EAT的阻断作用 ;流式细胞术测定小鼠CD4 CD2 5 T细胞百分率。结果　TCV接种后小鼠体内自身抗体水平明显下降 ,甲状腺无明显病理变化 ,IL 2和IFN γ水平以及Tg刺激的淋巴细胞增殖能力均显著降低 ,同时CD4 CD2 5 T细胞百分率较EAT组有明显增高。结论　TCV接种能明显抑制小鼠EAT的发生 ,可能与机体内CD4 CD2 5 Treg细胞的增加有关     

Antithyroid drugs ameliorate thymectomy-induced experimental autoimmune thyroiditis

The possible immunosuppressive action of antithyroid drugs in vivo has been assessed using Buffalo (Buf) strain rats with thyroiditis produced by neonatal thymectomy; this model shares many features with spontaneous thyroiditis in man. Both propylthiouracil and methimazole significantly reduced the severity of thyroiditis (P less than 0.01 compared to controls), irrespective of effects on thyroid status. Thyroidal Ox 8 (suppressor/cytotoxic) and W3/25 (helper) T-cells were reduced in number equally in treated animals, and thyroid follicular cell Ia expression was absent in a high proportion of these glands. Neither agent alone altered circulating antithyroglobulin antibody levels but there was a significant fall in antibody levels in animals treated with propylthiouracil and thyroxine. Antithyroid drugs had no effect on circulating T-cell subsets, and there was no direct suppressive action in vitro on Ia expression by the FRTL5 thyroid cell line. These results provide further support for a direct action of antithyroid drugs on autoimmune process in thyroid disease exerted in particular on the thyroid lymphocytic infiltrate.     

Autoimmune murine thyroiditis. VIII. Role of different thyroid antigens in the induction of experimental autoimmune thyroiditis.

Mice of the C57Br strain, which are susceptible to the induction of autoimmune thyroiditis with mouse thyroglobulin, and C57Bl mice, which are resistant, were immunized with human and rabbit thyroglobulins in Freund's complete adjuvant. Susceptible strain C57Br developed higher degrees of thyroid infiltration than the resistant strain. The results indicate that the responses to xenogeneic (foreign) thyroglobulins parallel allogeneic and syngeneic (mouse) thyroglobulin. BSVS mice, which are highly susceptible to thyroiditis, were immunized with mouse thyroid extract from five different mouse strains including syngeneic antigen. Recipients of C57Bl and DBA thyroid extracts showed lower indices of pathology than recipients of similar extracts from C3H, BSVS and non-inbred CF-1 mice. The results suggest that there is a difference in the immunogenicity of mouse thyroid extracts from different strains. Purified thyroglobulin was prepared from congenic strains B10.D2 (H-2d, resistant) and B10Br (H-2k, susceptible). H-2k thyroglobulin gave a greater response in both H-2k and H-2d mice than H-2d thyroglobulin.     

By-stander activation in autoimmune thyroiditis: studies on experimental autoimmune thyroiditis in the GFP+ fluorescent mouse

We have taken advantage of GFP+ fluorescent protein (GFP) tagged lymphocytes to examine by-stander activity in experimental autoimmune thyroiditis in the mouse. To generate GFP-positive EAT-susceptible CBA/J mice (H-2k) (GFP-CBA/J mice), we backcrossed CBA/J (H-2k) with heterozygous GFP+ transgenic mice (C57Bl/6; H-2b). I-Ak and GFP expression on peripheral lymphocytes was used to select the resulting progeny up to the N7 generation. Mixed lymphocyte reactions using spleen cells from N7 GFP-CBA/J mice showed negative responses to spleen cells from CBA/J confirming the inbreeding and with marked reactivity to cells from C57BL/6. Immunization with human thyroglobulin (hTg) in GFP-CBA/J mice induced thyroiditis in 50% of the animals and high titers of Tg antibodies in all the animals. In addition, priming of GFP+ spleen cells in vitro with hTg induced a marked proliferative response (mean stimulation index = 24.7), These proliferating spleen cells were then transferred to CBA/J recipients. Fourteen days after transferring 30 x 10(6) Tg-primed GFP+ spleen cells into irradiated (500 rad) normal syngeneic hosts, a GFP+ lymphocytic infiltration was seen within their thyroid glands along with a GFP- lymphocytic infiltration arising from the host. This suggested that the hTg-specific transferred cells had initiated by-stander activation of naive host lymphocytes. This model of bystander cell detection confirmed that such an effect occurs in EAT and adds weight to the importance of this phenomenon in the initiation of autoimmune thyroid disease.     

Factors affecting transfer of experimental autoimmune thyroiditis in rats

Actively induced experimental autoimmune thyroiditis in inbred Lewis rats was comparable using standard Freund's complete adjuvant (FCA) and Perrin's modification of FCA. However, adoptively transferred disease using lymph node cells from rats immunized with Perrin's FCA was significantly more severe. With this adjuvant, and pertussis vaccine as co-adjuvant, transfer was uniformly successful when at least 480 × 10⁶ lymph node cells were taken 10 days after immunization and recipients were killed 3 days after transfer. Lymphocytic infiltrates were seen in recipient thyroids as early as 18 hours after transfer. Whole body irradiation of the recipients at 550 r reduced the severity of transferred disease. The frequency and severity of lesions were higher when the lymph node cells were first incubated with low doses of antigen. Thymectomy of the recipients decreased the severity of transferred disease. Under the conditions tested, transfer of disease could not be accomplished by antiserum alone, even using thyroidectomized donors. Administration of an early immune serum with sensitized lymph node cells significantly depressed the severity of transferred disease, while a late antiserum increased it.     

Spontaneous autoimmune thyroiditis in NOD.H-2h4 mice

NOD.H-2h4 mice, which express I-Ak on the NOD genetic background, spontaneously develop autoimmune thyroiditis (SAT) and anti-mouse thyroglobulin (MTg) autoantibodies. The incidence of SAT is nearly 100% in mice of both sexes 6-8 weeks after administration of 0.05% NaI in the drinking water. After reaching maximum severity, inflammation is chronic over the next 3-4 months. All mice that develop thyroid lesions also produce MTg-specific IgG1 and IgG2b autoantibodies. Thyroid lesions and anti-MTg autoantibodies did not develop in CBA/J (H-2(k)) or NOD.SWR(H-2(q)) mice after administration of NaI water. Both CD4(+)and CD8(+)T cells are involved in the initial development of SAT. Depletion of CD4(+), but not CD8(+), T cells after thyroid lesions have developed also markedly reduced SAT severity, indicating that CD4(+)T cells are required for both developing and maintaining SAT. Analysis of cytokine gene expression indicated that both Th1 and Th2 cytokines were expressed in thyroids of NOD.H-2h4 mice with SAT. Th1 and proinflammatory cytokines were maximally expressed 4-6 weeks after mice began receiving NaI water, while Th2 cytokine gene expression was greatest at 8-15 weeks, when lesions had reached maximal severity and were in the chronic phase. TGF-beta was highly expressed in NOD.H-2h4 thyroids, irrespective of whether the mice had received NaI water or had thyroid lesions.     

The role of the spleen in experimental autoimmune thyroiditis

We have investigated the role of the spleen in the humoral and cellular immune response of rats with experimental autoimmune thyroiditis (EAT) induced by immunization with thyroglobulin and Freund's complete adjuvant. Animals subjected to splenectomy within 4 days of immunization developed lower thyroglobulin antibody levels and less severe thyroiditis compared to sham operated controls. There was no impairment in the ability of the animals to recover spontaneously from the disease after splenectomy. Together with the results obtained using splenocyte infusions, this suggests that suppressor cell production within the spleen plays only a small part in the normal immunological control which is presumably responsible for spontaneous regression of the disease.     

Effects of angiotensin II blockade on the development of autoimmune thyroiditis in nonobese diabetic mice

We evaluated the effects of angiotensin II (Ang II) blockers, losartan, an Ang II receptor blocker, and enalapril, an angiotensin converting enzyme inhibitor, on the development of autoimmune thyroiditis in nonobese diabetic (NOD) mice, an animal model of Hashimoto's thyroiditis (HT). Mice were assigned into three groups, untreated, losartan-treated (30 mg/kg/day), and enalapril-treated (10 mg/kg/day) groups. Thyroiditis was induced by iodide ingestion (experiment 1) or mouse thyroglobulin (Tg) immunization (experiment 2). Both procedures effectively induced thyroiditis. While iodide ingestion failed to induce anti-mouse Tg antibody (TgAb) production, Tg immunization resulted in a significant increase in serum TgAb levels. In both experiments, neither losartan nor enalapril interfered with the development of thyroiditis and TgAb production. These results suggest that Ang II may not be associated with the development of autoimmune thyroiditis in NOD mice. Thus, the Ang II blockade may not have therapeutic potential in HT.     

Thyroid hormones fail to influence experimental autoimmune thyroiditis

The effect of thyroid hormones on experimental autoimmune thyroiditis in the rat has been studied to determine whether the autoimmune process is influenced by alteration of thyroid hormone secretion from the diseased gland. Restoration of thyroid hormone levels in vivo had no effect on thyroglobulin antibody production or thyroiditis, and no effect of thyroid hormone on antibody secretion was found with in vitro culture of lymphocytes, suggesting that the pathogenesis of autoimmune thyroiditis is independent of thyroid hormone secretion.     

Effects of interleukin-6 blockade on the development of autoimmune thyroiditis in nonobese diabetic mice

We explored the role of interleukin-6 (IL-6) in the development of autoimmune thyroiditis in nonobese diabetic (NOD) mice, an animal model of Hashimoto's thyroiditis, using anti-mouse IL-6 receptor antibody (MR16-1). Thyroiditis was induced by iodide ingestion or mouse thyroglobulin (Tg) immunization. Mice were injected intraperitoneally with saline, control rat IgG, or MR16-1 (2 or 8 mg). Iodide ingestion did not increase serum IL-6 levels and MR16-1 (2 mg) failed to prevent the development of thyroiditis. In contrast, Tg immunization induced a rapid and significant increase in serum IL-6 levels. While MR16-1 (2 mg) had no effect on Tg-induced thyroiditis, the severity, but not incidence, of thyroiditis was reduced in 8 mg MR16-1-treated mice compared with saline-injected mice. However, thyroiditis development in the 8 mg MR16-1-treated mice was indistinguishable from that in the control IgG-treated mice. MR16-1 (8 mg) did not affect serum anti-Tg antibody levels. These results suggest that IL-6 may play only a minor role in the development of autoimmune thyroiditis in NOD mice.     

Newer insights into the pathogenesis of experimental autoimmune thyroiditis

Experimental autoimmune thyroiditis (EAT), produced in the mouse by immunization with murine thyroglobulin plus complete Freund's adjuvant, represents a valuable model for studying the pathogenesis of human chronic (Hashimoto's) thyroiditis. A major issue requiring clarification is the difference between benign autoimmunity, characterized solely by production of autoantibodies to thyroglobulin, and pathogenic autoimmunity where injury occurs to the thyroid cells. In this article, we describe the role of two key cytokines, IL12 and IFNgamma, in modifying the pathogenic immune response. EAT, defined by cellular infiltration of the thyroid and the development of thyroglobulin-specific autoantibodies, is a dynamic process. Consequently, a cytokine may exert a different effect at different times during the disease process. For purposes of discussion, we propose that there are three stages in the development of EAT: priming; initiation; and progression. Administration of anti-IL12 during the priming stage and initiation dramatically decreases disease and lowers autoantibody levels. In contrast, injection of recombinant IL12 after disease was established significantly decreases the severity of disease and reduces autoantibody levels. Unlike IL-12, IFNgamma was not essential for the priming of EAT. However, the severity of disease in the anti-IFNgamma-treated initiation- and progression-treated animals was higher than in controls, implying a regulatory role for IFNgamma. These findings emphasize that EAT involves a complex array of pathogenic mechanisms. The balance of cytokines produced during the early phase of the autoimmune reaction probably determines the progression from a harmless autoimmune response to autoimmune disease.