Autoinmunidad tiroidea en mujeres con Síndrome de Ovario Poliquístico / Thyroid autoimmunity in women with polycystic ovary syndrome

Introducción: Las bases fisiopatológicas del Síndrome de ovario poliquístico pueden predisponer a mayor riesgo de autoinmunidad a las mujeres que tienen esta condición y existen evidencias, aunque escasas, de mayor prevalencia de autoinmunidad tiroidea en ellas. Objetivos: Determinar la frecuencia de marcadores serológicos de autoinmunidad tiroidea en mujeres con Síndrome de ovario poliquístico e identificar si existe asociación entre la presencia de ellos y las concentraciones de progesterona y testosterona. Métodos: Se realizó un estudio en 50 mujeres con Síndrome de ovario poliquístico y 50 sin el síndrome. Se realizaron determinaciones de autoanticuerpos tiroideos (anti tiroglobulina (Anti-Tg) y anti peroxidasa (anti-TPO) a las mujeres de ambos grupos de estudio. Se realizaron determinaciones de hormonas (testosterona y progesterona) solo al grupo de estudio de mujeres con SOP. Se crearon categorías por anticuerpos: Positivo si los títulos fueron superior al rango de referencia y negativo dentro del rango. Se consideró respuesta autoinmune positiva, cuando al menos uno de los anticuerpos se encontró elevado. Para la asociación entre la presencia de autoinmunidad y las variables independientes se hicieron análisis bivariados mediante comparación de medias y test no paramétricos. Se consideró un nivel de significancia de α = 0,05. Resultados: En las mujeres con Síndrome de ovario poliquístico, 62 por ciento mostraron anticuerpos positivos y 14 por ciento en las sin el síndrome. En las mujeres sin síndrome, de las 7 mujeres con marcadores de autoinmunidad positivos, en 6 (85,7 por ciento) el anti-Tg fue el que dio positivo. No hubo diferencias significativas en cuanto a la asociación con los niveles de testosterona y progesterona. Conclusiones: Las mujeres con Síndrome de ovario poliquístico tienen mayor frecuencia de desarrollar respuesta autoinmune tiroidea, independiente de los niveles de progesterona y testosterona(AU)

Introduction: The physio-pathological bases of polycystic ovary syndrome may predispose women with this condition to a higher risk of autoimmunity and there is evidence, albeit scarce, of higher prevalence of thyroid autoimmunity in them. Objectives: Determine the frequency of serological markers of thyroid autoimmunity in women with polycystic ovary syndrome and identify whether there is an association between the presence of them and progesterone and testosterone concentrations. Methods: A study was conducted in 50 women with polycystic ovary syndrome and 50 without the syndrome. Determinations of thyroid autoantiantibodies (anti-thyroglobulin (Anti-Tg) and anti-peroxidase (anti-TPO) were made to women in both study groups. Hormone determinations (testosterone and progesterone) were made only to the study group of women with PCOS. Categories were created by antibodies: Positive if the titles were greater than the reference range, and negative if within the range. It was considered a positive autoimmune response when at least one of the antibodies was found increased. For the association between the presence of autoimmunity and independent variables, bivariate analyses were performed by means comparison and non-parametric tests. It was considered a significance level of α =0.05. Results: In women with polycystic ovary syndrome, 62 percent showed positive antibodies and 14 percent in those without the syndrome. In women without the syndrome, of the 7 women with positive autoimmune markers, in 6 (85.7 percent) the anti-Tg was the one that tested positive. There were no significant differences in the association with testosterone and progesterone levels. Conclusions: Women with polycystic ovary syndrome are more often able to develop thyroid autoimmune response, independently from the progesterone and testosterone levels(AU)

Oral exposure to dibutyl phthalate exacerbates chronic lymphocytic thyroiditis through oxidative stress in female Wistar rats.

Chronic lymphocytic thyroiditis (CLT) is a common autoimmune disorder. The possible pathogenic role and mechanism of dibutyl phthalate (DBP) in CLT is still controversial. Experiments were conducted after 35-days of oral exposure to the three concentrations of DBP or saline, and three immunizations with thyroglobulin (TG). Healthy female Wistar rats were randomly divided into ten exposure groups (n = 8 each): (A) saline control, (B) 0.5 mg/kg/d DBP, (C) 5 mg/kg/d DBP, (D) 50 mg/kg/d DBP, (E) TG-immunized group, (F) TG- combined with 0.5 mg/kg/d DBP, (G) TG- combined with 5 mg/kg/d DBP, (H) TG- combined with 50 mg/kg/d DBP, (I) TG- combined with 50 mg/kg/d DBP plus 100 mg/kg/d vitamin C; (J) 100 mg/kg/d vitamin C. We showed that oral exposure DBP can aggravate CLT in rats. This deterioration was concomitant with increased thyroid auto antibodies, Th1/Th2 imbalance and Th17 immune response, activated pro-inflammatory and apoptosis pathways, and increased thyroid dysfunction in rats. Our results also suggested that DBP could promote oxidative damage. The study also found that vitamin C reduced the levels of oxidative stress and alleviated CLT. In short, the study showed that DBP exacerbated CLT through oxidative stress.

Induction of immune tolerance in mice with a novel mucosal nanoemulsion adjuvant and self-antigen.

AIM: The aim of this study was to investigate the impact of a novel nanoemulsion (NE) adjuvant, a soybean oil emulsion, on autoimmune response. To this end, we used murine thyroglobulin (mTg)-induced experimental autoimmune thyroiditis in mice as a study model. MATERIALS & METHODS: Mice received NE or NE + mTg by nasal delivery. At 1 week after the second nasal delivery of NE with or without mTg, all mice were immunized with mTg and lipopolysaccharides to induce experimental autoimmune thyroiditis. RESULTS: Compared with controls, mTg-NE-treated mice had much more antigens accumulated in the nasal passage and thymus and developed a milder form of thyroiditis. This was accompanied by an increase in IL-10, IL-17 and reduced IFN-γ. The production of anti-mTg antibodies was significantly decreased in mTg-NE-treated mice. The percentage of Tregs in cervical lymph nodes was higher in mTg-NE-treated mice than NE-treated mice. Furthermore, Foxp3 and TGF-ß levels were prominently enhanced in mTg-NE-treated mice. CONCLUSION: This study indicates that a low dose of mTg in NE can significantly enhance antigen uptake and Tregs, resulting in inhibition of experimental autoimmune thyroiditis development.

Uso de la PET-18F-FDG en pacientes con sospecha de recurrencia de cáncer diferenciado de tiroides por anticuerpos anti-tiroglobulina elevados y rastreo 131I negativo / Use of 18FFDG-PET in patients with suspicion of recurrent differentiated thyroid cancer by elevated antithyroglobulin antibodies levels and negative 131I scan

Objetivo. Valorar la utilidad de los estudios PET-18F-FDG en el seguimiento de los pacientes diagnosticados de carcinoma diferenciado de tiroides que presentan riesgo de enfermedad y niveles de tiroglobulina (Tg) no interpretables por la presencia de anticuerpos antitiroglobulina (AbTg). Material y métodos. Estudio retrospectivo de 7 mujeres con edad media de 40 años y diagnóstico histológico de cáncer diferenciado de tiroides (7 carcinomas papilares) que fueron remitidos a nuestro servicio para la realización de estudio PET-18F-FDG por sospecha de enfermedad, debido a rastreo 131I negativo y niveles de AbTg elevados, entre los años 2002 y 2007. Se les realizaron 11 exploraciones PET tras la inyección de 370-434 MBq de 18F-FDG en condiciones de normoglucemia y previa administración de relajante muscular, hidratación y furosemida. Los resultados de la PET se confirmaron por histología y/o por evolución clínico radiológica, con un período de seguimiento mínimo de 24 meses. Resultados. La prevalencia de la recurrencia de la enfermedad en la población estudiada fue del 57,14%. Todas las pacientes presentaban niveles de Tg inferiores a 3 ng/dl y AbTg superiores a 200 UI/ml. Tres pacientes presentaban antecedentes de tiroiditis. De los 11 estudios realizados la PET fue negativa en tres y positiva en 8. Se descartó la existencia de enfermedad en 3 pacientes mientras que en 4 pacientes la PET permitió localizar con éxito la existencia de recidiva. Conclusión. La PET-18F-FDG es una técnica útil para localizar enfermedad, así como para descartar la existencia de recurrencia con una elevada seguridad diagnóstica, en pacientes con antecedentes de carcinoma diferenciado de tiroides con rastreo 131I negativo, pero con elevación patológica de anticuerpos AbTg(AU)

Aim. To evaluate the utility of 18FFDG-PET for patients diagnosed of differentiated thyroid carcinoma who present risk of disease and invaluable levels of thyroglobulin (Tg) by the presence of antibodies antithyroglobulin (AbTg). Material and methods. Retrospective study of 7 women of 40 years old and histological diagnosis of differentiated thyroid cancer (7 papillary tumours) that were sent to our department for the accomplishment of18FFDG-PET study because of suspicion of disease, due to 131I negative and high levels of AbTg, between the year 2002 and 2007. 11 PET scans were obtained after the intravenous injection of 370-434 MBq of 18FFDG in normoglycemia conditions and previous administration of muscle relaxant, hydration and diuretic. The results of 18FFDG-PET scans were confirmed by pathologic examination or clinical outcome and radiographic examination for more than 24 months. Results. The prevalence of recurrence in our population was 57.14%. All patients presented levels of Tg lower than 3 ng/dl and AbTg superior to 200 UI/ml. Three patients had precedent thyroiditis. Out of 11 scans performed 3 of them were negative and 8 cases were found positive. It ruled out the existence of disease in three patients and localized the presence of recurrence in 4 patients. Conclusion. 18FFDG-PET Conclusion. CONCLUSION: 18F-FDG-PET is a useful diagnostic tool for the detection of recurrence as well as to rule out the existence of disease with a high accuracy, in patients with differentiated thyroid carcinoma with 131I whole body scan negative but with pathological elevation of antithyroglobulin antibodies(AU)

Experimental autoimmune thyroiditis in human parvovirus B19 transgenic mice.

Viral infection is implicated as a cause of autoimmune diseases. Whereas its role in Hashimoto's thyroiditis (HT) remains undefined, recent studies suggested a link between human parvovirus B19 (B19) infection and HT. We tested such possibility by using B19 nonstructural protein 1 (NS1) transgenic C57BL/6 mice, which harbor nonpermissive genetic background (H-2(b)). Mice were immunized with either thyroglobulin (Tg) or saline. No thyroiditis developed in saline-treated mice and Tg-immunized males regardless of the presence or absence of NS1. In contrast, thyroiditis was induced by Tg immunization in 25% of transgenic females, but not in wild-type females. However, the thyroiditis incidence in the former did not differ significantly from that of the latter. In addition, intrathyroidal T-cell receptor gene expression was not augmented in Tg-immunized transgenic females. Immunization with Tg led to a comparable increase in serum anti-Tg antibody levels in the wild-type and transgenic mice. Our results indicate that the introduction of B19 NS1 gene into C57BL/6 mice is insufficient to promote the development of autoimmune thyroiditis. Further studies are required, however, before concluding that B19 infection is not involved in HT induction.

Captación torácica de 131I en el seguimiento del cáncer diferenciado de tiroides / Iodine uptake in the chest in the follow-up of well-differentiated thyroid cancer

El cáncer diferenciado de tiroides es una enfermedad con muy buen pronóstico si se trata adecuadamente. El tratamiento ablativo con 131I frecuentemente se asocia al tratamiento quirúrgico en estos pacientes ya que mejora la supervivencia, y el rastreo corporal total con 131I es una de las modalidades de diagnóstico de elección en el seguimiento de esta enfermedad. Tras tratamiento ablativo del tejido tiroideo, cualquier depósito del radiotrazador en una localización no fisiológica representa habitualmente la presencia de metástasis. Así pues, será fundamental el reconocimiento de cualquier posible falso positivo con el fin de evitar la radiación innecesaria debida a tratamientos inadecuados. Presentamos un caso clínico de captación torácica por bronquiectasias que puede malinterpretarse como metástasis pulmonar(AU)

Differentiated thyroid cancer is a disease having a very good prognosis when treated adequately. Ablation treatment with 131I is frequently adjunct to surgery in these patients since it improves survival. Radioiodine whole-body scan is one of the imaging modality of choice in the follow-up of patients with this kind of pathology. After ablation treatment of the thyroid gland, any radioiodine accumulation in a non-physiological location usually means the presence of functioning metastasis. Recognition of potential false-positives is essential to avoid unnecessary exposure to further radiation from repeated therapeutic doses of radioactive iodine. We report a case of uptake in the chest due to bronchiectasis, potentially masquerading as pulmonary metastasis(AU)

Limitaciones técnicas de los métodos para cuantificar tiroglobulina sérica y su repercusión clínica: [revisión] / Technical limitations of methods to quantify the serum thyroglobulin and its clinical repercussion: [review]

La determinación de tiroglobulina sérica se emplea, sobre todo, como marcador tumoral en el seguimiento posoperatorio de pacientes con cáncer diferenciado del tiroides. Lamentablemente, los métodos de tiroglobulina sérica presentan gran variabilidad en sus cualidades analíticas y padecen problemas técnicos que repercuten sobre la utilidad clínica de esta prueba. Para cuantificar tiroglobulina sérica se emplean 2 tecnologías diferentes: los iniciales radioinmunoensayos competitivos y los mßs recientes métodos inmunométricos no competitivos. Estos últimos son más propensos a sufrir las interferencias provocadas por la presencia de autoanticuerpos tiroglobulina y anticuerpos heterofílicos, a pesar de brindar los beneficios técnicos relativos al uso de reactivos no isotópicos, menor volumen de muestra, tiempos de incubación más cortos, así como mejor sensibilidad y facilidad de automatización. Resulta esencial que los clínicos conozcan y comprendan las limitaciones técnicas inherentes a la determinación de tiroglobulina sérica y su repercusión sobre la utilidad clínica de esta, con la finalidad de hacer un uso efectivo y eficiente de esta prueba en el seguimiento posoperatorio de pacientes con cáncer diferenciado del tiroides(AU)

The serum thyroglobulin assessment is used mainly as tumor marker during the postoperative follow-up of patients presenting with thyroid differentiated cancer. Progressively, the serum thyroglobulin methods have much variability in its analytical qualities and also have technical problems affecting on the technical usefulness of this test. To quantify the serum thyroglobulin we used two different technologies: the initial competitive radioimmunoassays and the most recent non competitive inmunometrical methods. These latter are more prone to have interferences provoked by presence of thyroglobulin antibodies and heterophilic antibodies despite to offer technical beneficial relative to use of non-isotopic reagents, a lower sample volume, shorter incubation times, as well as a better sensitivity and feasibility of automation. It is essential that clinicians know and understand the technical limitations inherent of serum thyroglobulin assessment and its repercussion on its clinical usefulness to an effective and efficient use of this test during the postoperative follow-up of patients presenting thyroid differential cancer(AU)

Tumor regression following DNA vaccination and regulatory T cell depletion in neu transgenic mice leads to an increased risk for autoimmunity.

Modulation of the immune system to amplify anti-tumor immunity carries the risk of developing autoimmune diseases, including hypothyroidism, as seen with cancer patients undergoing clinical trials for immunotherapeutic regimens. Although there is a tendency to view autoimmunity as a positive indicator for cancer immunotherapy, some autoimmune manifestations can be life-threatening and necessitate prolonged medical intervention or removal from trial. We have established murine test models to assess such risks by monitoring, simultaneously, the immune reactivity to tumor-associated rat erbB-2 (neu) and another self Ag, mouse thyroglobulin (mTg). We previously reported that in wild-type, thyroiditis-resistant BALB/c mice that underwent regression of neu(+) TUBO tumors following regulatory T cell (Treg) depletion, immune responses to rat neu and mTg with resultant autoimmune thyroiditis (EAT) were both enhanced. In this study, we tested the balance between tumor immunity and autoimmunity in neu-transgenic BALB NeuT female mice. First, growth and progression of neu(+) tumor were compared in neu tolerant mice treated with either CD25 mAb to deplete Tregs and/or DNA vaccination. Only Treg depletion followed by neu DNA vaccination abrogated tolerance to neu, resulting in complete regression of neu(+) tumors, as well as long-term protection from spontaneous tumorigenesis in 58% of mice. The risk of developing EAT was then assessed by incorporated mTg immunization with or without LPS as adjuvant. In mice with induced tumor regression, mTg response was enhanced with modest increases in EAT development. Therefore, tumor regression induced by Treg depletion and DNA vaccination can exacerbate autoimmunity, which warrants close monitoring during immunotherapy.

Naturally-existing CD4(+)CD25(+)Foxp3(+) regulatory T cells are required for tolerance to experimental autoimmune thyroiditis induced by either exogenous or endogenous autoantigen.

Murine experimental autoimmune thyroiditis (EAT) is a model for Hashimoto's thyroiditis, an organ-specific autoimmune disease characterized by mononuclear cell infiltration and destruction of the thyroid gland. Susceptibility to EAT is MHC-linked, and influenced by CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs). Treg depletion enables thyroiditis induction with mouse thyroglobulin (mTg) in traditionally-resistant mice and mTg-induced, Treg-mediated tolerance protects against EAT induction in genetically-susceptible mice. Here, we demonstrate the existence of naturally-existing CD4(+)CD25(+)Foxp3(+) Tregs (nTregs) influencing thyroiditis development in naive susceptible mice and that induction of thyroiditis in these mice involves overcoming peripheral homeostatic immune suppression by nTregs. Additionally we demonstrate that nTregs are required for induction of antigen-specific tolerance, indicating that induced EAT tolerance is a result of activation of naturally-existing nTregs rather than de novo generation of induced Tregs (iTregs). Examination of several potential costimulatory molecules previously described as involved in peripheral activation of Tregs demonstrates a critical role indeed for CTLA-4 in the activation of nTregs leading to development of EAT tolerance and providing a mechanism for mTg-induced Treg activation during tolerance induction. Together, these data reinforce the important role of Tregs in mediating self-tolerance, and illuminate a potential mechanism for their therapeutic expansion in induced tolerance.

Influence of age and primary tumor size on the risk for residual/recurrent well-differentiated thyroid carcinoma.

BACKGROUND: Though age and primary tumor size predict cancer-specific survival in well-differentiated thyroid carcinoma (WDTC), their influence on residual/recurrent disease has not been elucidated. METHODS: In a retrospective study, residual/recurrent disease was defined by the surrogate outcome of positive (>or=2 microg/L) follow-up stimulated thyroglobulin after surgery and radioactive remnant ablation. Age, primary tumor size, and clinical staging systems were examined in the context of stimulated thyroglobulin outcome. RESULTS: A total of 246 patients were followed up for a mean of 5.8 years. No significant difference in age (t(239) = 0.61, p > .05) or tumor size (t(237) = 0.16, p > .05) was found among patients with positive follow-up stimulated thyroglobulin compared with those with negative results. pTNM staging failed to demonstrate significant, stage-dependent increase in the percentage of patients with positive stimulated thyroglobulin, chi(2)(2, N = 229) = 0.17, p > .05, unlike staging based solely on surgical pathology, chi(2)(2, N = 241) = 34.97, p < .001. CONCLUSION: Age, primary tumor size, and pTNM staging do not predict risk for residual/recurrent WDTC, whereas extrathyroidal extension at initial surgery is predictive.

Immunocompetence in organically fed finishing pigs: effect of corn cob mix.

Two consecutive experiments were performed to evaluate the effects on the immune response of corn cob mix (CCM) in an organic pig diet. The immunoglobulin (Ig) M, IgA and IgG responses against an intramuscularly injected model antigen, bovine thyroglobulin, were used as indicator. The experiments were performed in an organic barn with nine pens of four crossbred pigs (two barrows and two sows) from 45 kg to slaughter. In the first experiment, the organic concentrate was mixed with organic CCM-silage to obtain three concentrate: CCM ratios of 100:0, 80:20 and 60:40 (w:w). In the second experiment, three concentrates were produced to obtain diets with equal nutrient levels on a dry matter basis after 0%, 20% and 40% CCM inclusion. Higher inclusion rates of CCM in the ration were accompanied by lower thyroglobulin-specific IgG responses. These effects could not be attributed to one specific component of the CCM, such as fatty acid composition, although there was a degree of correlation with lower vitamin A concentrations. Mycotoxin concentrations were absent or minimal. The study indicated that dietary ingredient composition may affect immunocompetence.

Human thyroglobulin peptide p2340 induces autoimmune thyroiditis in HLA-DR3 transgenic mice.

In a previous study we demonstrated that the human thyroglobulin (hTg) peptide p2340 (aa 2340-2359) can stimulate a T cell response and elicit experimental autoimmune thyroiditis (EAT) in AKR/J (H-2(k)) mice. In the present study we examined whether p2340 can induce EAT in single HLA class II DR3 transgenic mice. This peptide was found to be immunogenic at the T cell level in DR3 mice, since it induced specific proliferative responses, as well as IL-2 and IFN-gamma secretion in secondary cultures of peptide-primed lymph node cells (LNC). Immunization of HLA-DR3 mice with p2340 in CFA elicited EAT (infiltration index of 1 to 2) in eight of nine mice. Peptide-primed LNC responded to intact hTg, whereas, hTg-primed LNC did not respond to p2340 in culture, suggesting that p2340 contains subdominant T cell epitope(s). P2340 was also found to be immunogenic at the B cell level, since strong p2340-specific IgG response was detected in all transgenic mice tested. Thus, we provide evidence for a pathogenic role of an hTg peptide in HLA-DR3 transgenic mice. Therefore, p2340 could be presented by DR3 molecule in patients with Hashimoto's thyroiditis and participate in the development of the disease.

IL-10-producing CD4+CD25+ regulatory T cells play a critical role in granulocyte-macrophage colony-stimulating factor-induced suppression of experimental autoimmune thyroiditis.

Our earlier study showed that GM-CSF has the potential not only to prevent, but also to suppress, experimental autoimmune thyroiditis (EAT). GM-CSF-induced EAT suppression in mice was accompanied by an increase in the frequency of CD4(+)CD25(+) regulatory T cells that could suppress mouse thyroglobulin (mTg)-specific T cell responses in vitro, but the underlying mechanism of this suppression was not elucidated. In this study we show that GM-CSF can induce dendritic cells (DCs) with a semimature phenotype, an important characteristic of DCs, which are known to play a critical role in the induction and maintenance of regulatory T cells. Adoptive transfer of CD4(+)CD25(+) T cells from GM-CSF-treated and mTg-primed donors into untreated, but mTg-primed, recipients resulted in decreased mTg-specific T cell responses. Furthermore, lymphocytes obtained from these donors and recipients after adoptive transfer produced significantly higher levels of IL-10 compared with mTg-primed, untreated, control mice. Administration of anti-IL-10R Ab into GM-CSF-treated mice abrogated GM-CSF-induced suppression of EAT, as indicated by increased mTg-specific T cell responses, thyroid lymphocyte infiltration, and follicular destruction. Interestingly, in vivo blockade of IL-10R did not affect GM-CSF-induced expansion of CD4(+)CD25(+) T cells. However, IL-10-induced immunosuppression was due to its direct effects on mTg-specific effector T cells. Taken together, these results indicated that IL-10, produced by CD4(+)CD25(+) T cells that were probably induced by semimature DCs, is essential for disease suppression in GM-CSF-treated mice.

H2A- and H2E-derived CD4+CD25+ regulatory T cells: a potential role in reciprocal inhibition by class II genes in autoimmune thyroiditis.

We recently described a novel H2E class II-transgenic model (A(-)E(+)) of experimental autoimmune thyroiditis (EAT) that permits disease induction with heterologous thyroglobulin (Tg), but unlike conventional susceptible strains, precludes self-reactivity to autologous mouse Tg. In transgenic E(+)B10 (A(+)E(+)) mice, the presence of endogenous H2A genes is protective against H2E-mediated thyroiditis, inhibiting EAT development. The suppressive effect of H2A genes on H2E-mediated thyroiditis mirrors previous reports of H2E suppression on H2A-mediated autoimmune diseases, including EAT. The mechanism of the reciprocal-suppressive effect between class II genes is unclear, although the involvement of regulatory T cells has been proposed. We have recently reported that CD4(+)CD25(+) regulatory T cells mediate peripheral tolerance induced with mouse Tg in CBA mice. To determine whether these cells play a role in our E(+)-transgenic model, we first confirmed the existence of CD4(+)CD25(+) T cells regulating thyroiditis in E(+)B10.Ab(0) (A(-)E(+)) and B10 (A(+)E(-)) mice by i.v. administration of CD25 mAb before EAT induction. The depletion of CD4(+)CD25(+) T cells enhanced thyroiditis induction in the context of either H2E or H2A. Moreover, reconstitution of CD4(+)CD25(+) T cells from naive B10 mice restored resistance to EAT. E(+)B10 (A(+)E(+)) mice were also depleted of CD4(+)CD25(+) T cells before the challenge to determine their role in thyroiditis in the presence of both H2A and H2E genes. Depletion of CD4(+)CD25(+) regulatory T cells offset the suppression of H2E-mediated thyroiditis by H2A. Thus, these regulatory T cells may be involved in the reciprocal-suppressive effect between class II genes.

Induction of a TC1-mediated experimental autoimmune thyroiditis by deglycosylated porcine thyroglobulin.

Contribution of cytotoxic T lymphocytes (CTL) to experimental autoimmune thyroiditis (EAT) was well defined (Speidel et al., Eur. J. Immunol. 1997, 27, 2391-2399, Ref. 7). The native porcine thyroglobulin (pTg) showed high sensitivity to endo-o-N-acetylglucosaminidase F (Endo F) and its molecular weights, corresponding to about 330 kDa as a monomer and 660 kDa as a dimer, were reduced to smaller molecular weight forms by Endo F and trifluoromethanesulfonic acid (TMSF). Deglycosylated porcine Tg (dgpTg) and native pTg were injected i.v. into CBA/J mice, without the aid of adjuvants. Both lymphocytic infiltrations of the thyroid glands and levels of Tg-specific CTL were similar to those found in conventional EAT induced by Tg and adjuvants. In contrast, proliferative responses in native pTg and dgpTg-injected mice could not be detected, and titers of antibodies to pTg and dgpTg were 20 times and 30 times lower than that of pTg and adjuvants, respectively. The EAT-inducer CTL belonged to the CD8+ cell subset and exerted their thyroiditogenic potential through release of IFN-gamma. It was concluded that dgpTg-induced EAT is mediated by type 1 cytotoxic T cells (Tcl). Also, results that EAT induction of the glycosylated pTg (gpTg) was much lower than that of dgpTg, suggested that the abberant and incomplete glycosylation of the thyroglobulin is responsible for the induction of autoimmune thyroiditis.

Multiple fragments of human TG are capable of inducing oral tolerance to whole human TG.

Oral tolerance is the mechanism by which the immune system remains unresponsive to orally administered soluble antigens. Mice immunized with human TG (hTG), resulting in the induction of experimental autoimmune thyroiditis (EAT), provide an ideal in vivo system in which to examine oral tolerance to hTG. In the present study, we characterize epitopes of hTG that are capable of inducing oral tolerance. hTG is a large homodimeric protein, 660 Kd. The limited proteolysis of hTG using trypsin (TR) generates several smaller fragments of hTG ranging in size from 29 Kd to 145 Kd. Using hTG fragments h1TR (residues 1-521), h4bisTR (residues 2513-2713), h6TR (residues 522-1626), and h7TR (residues 1627-2512), prepared from both iodine rich and iodine poor hTG, we investigated the ability of these fragments to induce oral tolerance. The oral administration of iodine rich h6TR or h7TR suppresses hTG specific immune responses in a manner similar to whole hTG. In contrast, the oral administration of iodine rich h1TR or h4bisTR exacerbates hTG specific immune responses. Unlike iodine rich h1TR or h4bisTR, the oral administration of iodine poor h1TR or h4bisTR fails to augment hTG specific immune responses. In fact, h4bisTR suppresses hTG specific immune responses. These results indicate that hTG contains multiple epitopes that differentially affect oral tolerization. Tolerogenic epitopes reside within fragments h6TR and h7TR. The removal of iodine, and presumably hormone, from h4bisTR converts an immunogenic epitope to a tolerogenic epitope.

Delineation of five thyroglobulin T cell epitopes with pathogenic potential in experimental autoimmune thyroiditis.

Experimental autoimmune thyroiditis (EAT) is a T cell-mediated disease that can be induced in mice after challenge with thyroglobulin (Tg) or Tg peptides. To date, five pathogenic Tg peptides have been identified, four of which are clustered toward the C-terminal end. Because susceptibility to EAT is under control of H-2A(k) genes, we have used an algorithm-based approach to identify A(k)-binding peptides with pathogenic potential within mouse Tg. Eight candidate synthetic peptides, varying in size from 9 to 15 aa, were tested and five of those (p306, p1579, p1826, p2102, and p2596) were found to induce EAT in CBA/J (H-2(k)) mice either after direct challenge with peptide in adjuvant or by adoptive transfer of peptide-sensitized lymph node cells (LNCs) into naive hosts. These pathogenic peptides were immunogenic at the T cell level, eliciting specific LNC proliferative responses and IL-2 and/or IFN-gamma secretion in recall assays in vitro, but contained nondominant epitopes. All immunogenic peptides were confirmed as A(k) binders because peptide-specific LNC proliferation was blocked by an A(k)-specific mAb, but not by a control mAb. Peptide-specific serum IgG was induced only by p2102 and p2596, but these Abs did not bind to intact mouse Tg. This study reaffirms the predictive value of A(k)-binding motifs in epitope mapping and doubles the number of known pathogenic T cell determinants in Tg that are now found scattered throughout the length of this large autoantigen. This knowledge may contribute toward our understanding of the pathogenesis of autoimmune thyroiditis.

Autoimmune thyroid disease induced by thyroglobulin and lipopolysaccharide is inhibited by soluble TNF receptor type I.

Experimental autoimmune thyroiditis (EAT) is inducible in mice by immunization with thyroglobulin and adjuvant. Previous studies have shown that EAT is an autoimmune Th1-mediated disease but its characteristics differ with the adjuvant. Granulomatous lesions with marked follicular disruption develop following administration of thyroglobulin (Tg) and complete Freund's adjuvant (CFA) whereas when lipopolysaccharide (LPS) is used as the adjuvant only focal infiltrates of mononuclear cells are observed. The pro-inflammatory cytokine, TNF-alpha, is associated with Th1 autoimmune-mediated conditions. Cytokine antagonists have been used as potential therapeutic agents in several experimental autoimmune models. Soluble cytokine receptors belong to this category and may naturally be shed from cell membranes to inhibit cytokine activity. We show that the administration of the soluble TNF receptor type I (sTNFR I) in the induction of EAT has very different effects on the two models of induced autoimmune thyroiditis. sTNFR I treatment inhibits the induction of EAT only when mouse Tg is given with LPS not with CFA, suggesting an important difference in the pathogenic processes.

Characterization of the T lymphocyte subsets and lymphoid populations involved in the induction of low-dose oral tolerance to human thyroglobulin.

Using mice deficient in CD8alpha, TCRdelta, CD4, or CD120a, as well as adoptive transfer experiments in wild-type and RAG-1-deficient mice, we characterized the T lymphocyte subsets and lymphoid populations involved in the induction of low-dose oral tolerance to human thyroglobulin (hTg). The oral administration of hTg, but not the intraperitoneal (ip) administration of hTg, generates lymphocytes that can transfer tolerance. Purified CD8alpha+ lymphocytes successfully transfer tolerance, while the depletion of CD8alpha or TCRdelta lymphocytes prevents the transfer of tolerance. Oral tolerance can be induced in CD4-deficient mice and RAG-1-deficient mice reconstituted with cells from CD120a-deficient mice, but not in CD8alpha-, TCRdelta, or CD120a-deficient mice. These findings indicate that CD8alpha and TCRdelta T lymphocytes are necessary for the oral induction and transfer of tolerance to hTg. Additionally, functional Peyer's patches are necessary for the induction of low-dose oral tolerance to hTg.