I-E+ nonobese diabetic mice develop insulitis and diabetes

NOD alleles at Idd1 and Idd2 loci drive exocrine pancreatic inflammation

Non-obese diabetic (NOD) mice spontaneously develop autoimmune diabetes and have enabled the identification of several loci associated with diabetes susceptibility, termed insulin-dependent diabetes (Idd). The generation of congenic mice has allowed the characterization of the impact of several loci on disease susceptibility. For instance, NOD.B6-Idd1 and B6.NOD-Idd1 congenic mice were instrumental in demonstrating that susceptibility alleles at the MHC locus (known as Idd1) are necessary but not sufficient for autoimmune diabetes progression. We previously showed that diabetes resistance alleles at the Idd2 locus provide significant protection from autoimmune diabetes onset, second to Idd1. In search of the minimal genetic factors required for T1D onset, we generated B6.Idd1.Idd2 double-congenic mice. Although the combination of Idd1 and Idd2 is not sufficient to induce diabetes onset, we observed immune infiltration in the exocrine pancreas of B6.Idd2 mice, as well as an increase in neutrophils and pancreatic tissue fibrosis. In addition, we observed phenotypic differences in T-cell subsets from B6.Idd1.Idd2 mice relative to single-congenic mice, suggesting epistatic interaction between Idd1 and Idd2 in modulating T-cell function. Altogether, these data show that Idd1 and Idd2 susceptibility alleles are not sufficient for autoimmune diabetes but contribute to inflammation and immune infiltration in the pancreas.

Severe Autoimmune Thyroiditis in Transgenic NOD.H2h4 Mice Expressing Interleukin-4 in the Thyroid

Background: Hashimoto's thyroiditis is a common autoimmune thyroid disorder characterized by thyroid lymphocytic infiltrates and autoreactive antibodies against thyroglobulin (TgAbs) and thyroperoxidase. Final evolution of the disease can lead to hypothyroidism with destruction of the thyroid architecture. Interleukin-4 (IL-4) is involved in the humoral immune response and B cell activation required in autoimmune thyroiditis (AT) progression. We used our mouse model overexpressing IL-4 by thyrocytes (Thyr-IL4) to study the impact of a local IL-4 expression in AT using transgenic nonobese diabetic (NOD.H2^h4) derived animals treated with iodide-supplemented water to increase the incidence of spontaneous AT (SAT). Methods: Thyr-IL4 NOD.H2^h4 and nonpathogenic C57BL/6 animals aged 8 weeks were exposed to 0.05% sodium iodide (NaI) in their drinking water for 8 and 16 weeks. Circulating TgAbs and expression of intrathyroidal cytokines were quantified. Thyroid inflammation was assessed by classical histological analyses, including identification of some immune cell populations. The most sensitive parameter to evaluate the thyroid function, serum thyrotropin (TSH), was also measured at the end of the treatment. Results: Relative to wild-type (WT) animals, Thyr-IL4 NOD.H2^h4 mice developed severe accelerated SAT with elevated serum TgAbs and numerous thyroid infiltrates mainly composed of CD4⁺/CD8⁺ T cells, B lymphocytes, and monocytes/macrophages. Thyroid expression of T helper (Th) Th1/Th2 cytokines was also enhanced, as well as IL-17. In contrast, excessive iodide supply did not induce TgAbs in WT and Thyr-IL4 SAT-resistant C57BL/6 animals. However, moderate leukocyte infiltrations in transgenic thyroids were evident compared to WT, but associated with a limited number of T and B cells and a different cytokine profile from Thyr-IL4 NOD.H2^h4 mice. Finally, and despite their diverse immune responses, both transgenic strains presented marked thyroid enlargement and elevated serum TSH at the end of the treatment in contrast to their WT littermates. Conclusions: These findings demonstrated that ectopic expression of IL-4 from thyrocytes enhanced the severity of accelerated SAT in disease-prone Thyr-IL4 NOD.H2^h4 animals and promoted thyroid leukocyte infiltration in SAT-resistant transgenic C57BL/6 mice. Moreover, impaired thyroid function emerged in both transgenic strains during the progression of the disease.

The Immune Landscape of Papillary Thyroid Cancer in the Context of Autoimmune Thyroiditis

Simple Summary

The association between papillary thyroid cancer and Hashimoto’s thyroiditis went through a long-standing human debate recently elucidated by the establishment of a novel mouse model. Papillary thyroid carcinoma is an excellent model for studying the tumor immune microenvironment because it is naturally accompanied by immune cells, making it a good candidate for the treatment with immune checkpoint inhibitors.

Abstract

Papillary thyroid cancer (PTC) often co-occurs with Hashimoto’s thyroiditis, an association that has long been reported in clinical studies, remaining controversial. Experimental evidence has recently shown that pre-existing thyroiditis has a beneficial effect on PTC growth and progression by a distinctive expansion of effector memory CD8 T cells. Although the link between inflammation and PTC might involve different components of the immune system, a deep characterization of them which includes T cells, B cells and tertiary lymphoid structures, Mye-loid cells, Neutrophils, NK cells and dendritic cells will be desirable. The present review article considers the role of the adaptive and innate immune response surrounding PTC in the context of Hashimoto’s thyroiditis. This review will focus on the current knowledge by in vivo and in vitro studies specifically performed on animals’ models; thyroid cancer cells and human samples including (i) the dual role of tumor-infiltrating lymphocytes; (ii) the emerging role of B cells and tertiary lymphoid structures; (iii) the role of myeloid cells, dendritic cells, and natural killer cells; (iv) the current knowledge of the molecular biomarkers implicated in the complex link between thyroiditis and PTC and the potential implication of cancer immunotherapy in PTC patients in the context of thyroiditis.

Inhibition of IL-17A Protects against Thyroid Immune-Related Adverse Events while Preserving Checkpoint Inhibitor Antitumor Efficacy

Immune checkpoint inhibitor (ICI) immunotherapy leverages the body's own immune system to attack cancer cells but leads to unwanted autoimmune side effects in up to 60% of patients. Such immune-related adverse events (IrAEs) may lead to treatment interruption, permanent organ dysfunction, hospitalization, and premature death. Thyroiditis is one of the most common IrAEs, but the cause of thyroid IrAEs remains unknown. In this study, we use a new, physiologically relevant mouse model of ICI-associated autoimmunity to identify a key role for type 3 immune cells in the development of thyroid IrAEs. Multiple lineages of IL-17A-producing T cells expand in thyroid tissue with ICI treatment. Intrathyroidal IL-17A-producing innate-like γδT17 cells were increased in tumor-free mice, whereas adaptive Th17 cells were also prominent in tumor-bearing mice, following ICI treatment. Furthermore, Ab-based inhibition of IL-17A, a clinically available therapy, significantly reduced thyroid IrAE development in ICI-treated mice with and without tumor challenge. Finally, combination of IL-17A neutralization with ICI treatment in multiple tumor models did not reduce ICI antitumor efficacy. These studies suggest that targeting Th17 and γδT17 cell function via the IL-17A axis may reduce IrAEs without impairing ICI antitumor efficacy and may be a generalizable strategy to address type 3 immune-mediated IrAEs.

The NOD Mouse Beyond Autoimmune Diabetes

Autoimmune diabetes arises spontaneously in Non-Obese Diabetic (NOD) mice, and the pathophysiology of this disease shares many similarities with human type 1 diabetes. Since its generation in 1980, the NOD mouse, derived from the Cataract Shinogi strain, has represented the gold standard of spontaneous disease models, allowing to investigate autoimmune diabetes disease progression and susceptibility traits, as well as to test a wide array of potential treatments and therapies. Beyond autoimmune diabetes, NOD mice also exhibit polyautoimmunity, presenting with a low incidence of autoimmune thyroiditis and Sjögren's syndrome. Genetic manipulation of the NOD strain has led to the generation of new mouse models facilitating the study of these and other autoimmune pathologies. For instance, following deletion of specific genes or via insertion of resistance alleles at genetic loci, NOD mice can become fully resistant to autoimmune diabetes; yet the newly generated diabetes-resistant NOD strains often show a high incidence of other autoimmune diseases. This suggests that the NOD genetic background is highly autoimmune-prone and that genetic manipulations can shift the autoimmune response from the pancreas to other organs. Overall, multiple NOD variant strains have become invaluable tools for understanding the pathophysiology of and for dissecting the genetic susceptibility of organ-specific autoimmune diseases. An interesting commonality to all autoimmune diseases developing in variant strains of the NOD mice is the presence of autoantibodies. This review will present the NOD mouse as a model for studying autoimmune diseases beyond autoimmune diabetes.

Pre-existing Thyroiditis Ameliorates Papillary Thyroid Cancer: Insights From a New Mouse Model

Papillary thyroid cancer (PTC) often co-occurs with Hashimoto's thyroiditis, an association that has long been reported in clinical studies yet remains controversial. Some studies, in fact, have suggested a protective effect of thyroiditis while others have not. We generated a mouse model where PTC and thyroiditis develop in a predictable manner, combining the oncogenic drive of the BRAFv600E mutation (inducible by tamoxifen) to the thyroiditis susceptibility of the NOD.H2h4 strain (inducible by iodine). A total of 113 NOD.H2h4_TPO-CRE-ER_BRAFV600E mice (50 followed throughout lifetime and 63 sacrificed at 16 weeks post tamoxifen) were used to determine whether the PTC phenotype differs when thyroiditis precedes or coincides with the onset of PTC. Mice with pre-existing thyroiditis lived longer (median survival of 28.2 weeks post tamoxifen) than those with concomitant (25.6 weeks) or no (24.5 weeks) thyroiditis (P < 0.01 by Laplace regression). PTC developed less frequently (33%) in the pre-existing thyroiditis group than the concomitant (100%) or no (100%) thyroiditis groups (P < 0.001 by chi-squared) and showed less aggressive histopathological features. The intratumoral mononuclear cell infiltration was more prominent in mice with pre-existing thyroiditis (P = 0.002 vs the other groups) and sustained by a significant expansion of effector memory CD8 + T cells and CD19 + B cells. These findings shed light on the controversial PTC-thyroiditis association and emphasize the contribution of intratumoral T and B lymphocytes to the evolution of PTC.

In Vivo Inhibition of MicroRNA-326 in a NOD.H-2h4 Mouse Model of Autoimmune Thyroiditis

Background

Previous studies reported that various miRNAs participate in autoimmune diseases, but the potential regulatory mechanism of miRNAs in autoimmune thyroiditis (AIT) needs further exploration.

Objective

This study aimed to further verify that miR-326 contributes to AIT by regulating Th17/Treg balance through Ets-1 using lentiviral gene delivery through tail vein and thyroid injection in NOD.H-2^h4 mice.

Materials and Methods

Five-week-old NOD.H-2^h4 mice were divided randomly into tail vein and thyroid injection groups, and each received either mmu-miR-326 sponge (LV-sponge) or lentiviral vector control. Mice were divided for tail vein injection: the therapeutic LV-ctrl, therapeutic LV-sponge, prophylactic LV-ctrl, and prophylactic LV-sponge groups. The control group was fed high-iodine water without vein injection. The thyroid infiltration of lymphocytes and serum TgAb value were investigated by thyroid hematoxylin and eosin (HE) staining and ELISA, respectively. Ets-1 and lymphocyte counts were measured by RT-PCR, western blotting, and flow cytometry. The thyroid CD4⁺IL-17a⁺ cells and CD4⁺Ets-1⁺ cells were detected by immunofluorescence, and the serum cytokines were tested by ELISA.

Results

In the tail vein injection groups, the thyroid inflammatory score and serum TgAb titer were significantly lower in the LV-sponge groups than in the control and LV-ctrl groups while Ets-1 protein expression in mouse spleens was increased in the LV-sponge groups. Moreover, Th17/Treg ratio declined in the LV-sponge group and decreased significantly in the prophylactic LV-sponge group (P = 0.036) tested by flow cytometry. Immunofluorescence showed that, in LV-sponge groups, CD4⁺IL-17a⁺ cells were decreased significantly (P = 0.001), while CD4⁺Ets-1⁺ cells were increased significantly in the LV-sponge group (P = 0.029). The serum IL-17/IL-10 was decreased significantly in the LV-sponge group (P < 0.05). In the thyroid injection groups, the thyroid inflammatory score and serum TgAb titer in the LV-sponge group decreased significantly compared with those in the LV-ctrl group (P < 0.05). In addition, in LV-sponge groups, CD4⁺IL-17a⁺ cells were decreased, while CD4⁺Ets-1⁺ cells were increased significantly in the inhibition group evaluated by immunofluorescence. Moreover, tail vein injection of LV-sponge resulted in much lower TgAb levels in thyroiditis compared with thyroid injection.

Conclusion

MiR-326 targeted therapy may be a promising approach for AIT. In addition, tail vein injection may achieve a better intervention effect than thyroid injection.

Evidence of genetic epistasis in autoimmune diabetes susceptibility revealed by mouse congenic sublines

Susceptibility to autoimmune diabetes is a complex genetic trait. Linkage analyses exploiting the NOD mouse, which spontaneously develops autoimmune diabetes, have proved to be a useful tool for the characterization of some of these traits. In a linkage analysis using 3A9 TCR transgenic mice on both B10.BR and NOD.H2^k backgrounds, we previously determined that both the Idd2 and Idd13 loci were linked to the proportion of immunoregulatory CD4^-CD8^- double negative (DN) T cells. In addition to Idd2 and Idd13, five other loci showed weak linkage to the proportion of DN T cells. Of interest, in an interim analysis, a locus on chromosome 12 is linked to DN T cell proportion in both the spleen and the lymph nodes. To determine the impact of this locus on DN T cells, we generated two congenic sublines, which we named Chr12P and Chr12D for proximal and distal, respectively. While 3A9 TCR:insHEL NOD.H2^k-Chr12D mice were protected from diabetes, 3A9 TCR:insHEL NOD.H2^k-Chr12P showed an increase in diabetes incidence. Yet, the proportion of DN T cells was similar to the parental 3A9 TCR NOD.H2^k strain for both of these congenic sublines. A genome-wide two dimensional LOD score analysis reveals genetic epistasis between chromosome 12 and the Idd13 locus. Altogether, this study identified further complex genetic interactions in defining the proportion of DN T cells, along with evidence of genetic epistasis within a locus on chromosome 12 influencing autoimmune susceptibility.

Nanoparticles Bearing TSH Receptor Protein and a Tolerogenic Molecule Do Not Induce Immune Tolerance but Exacerbate Thyroid Autoimmunity in hTSHR/NOD.H2h4 Mice

Transgenic NOD.H2h4 mice that express the human (h) TSHR A-subunit in the thyroid gland spontaneously develop pathogenic TSHR autoantibodies resembling those in patients with Graves disease. Nanoparticles coupled to recombinant hTSHR A-subunit protein and a tolerogenic molecule (ligand for the endogenous aryl-hydrocarbon receptor; ITE) were injected i.p. four times at weekly intervals into hTSHR/NOD.H2h4 mice with the goal of blocking TSHR Ab development. Unexpectedly, in transgenic mice, injecting TSHR A-subunit-ITE nanoparticles (not ITE-nanoparticles or buffer) accelerated and enhanced the development of pathogenic TSHR Abs measured by inhibition of TSH binding to the TSHR. Nonpathogenic TSHR Abs (ELISA) were enhanced in transgenics and induced in wild-type littermates. Serendipitously, these findings have important implications for disease pathogenesis: development of Graves TSHR Abs is limited by the availability of A-subunit protein, which is shed from membrane bound TSHR, expressed at low levels in the thyroid. The enhanced TSHR Ab response following injected TSHR A-subunit protein-nanoparticles is reminiscent of the transient increase in pathogenic TSHR Abs following the release of thyroid autoantigens after radio-iodine therapy in Graves patients. However, in the hTSHR/NOD.H2h4 model, enhancement is specific for TSHR Abs, with Abs to thyroglobulin and thyroid peroxidase remaining unchanged. In conclusion, despite the inclusion of a tolerogenic molecule, injected nanoparticles coated with TSHR A-subunit protein enhanced and accelerated development of pathogenic TSHR Abs in hTSHR/NOD. NOD.H2h4 These findings emphasize the need for sufficient TSHR A-subunit protein to activate the immune system and the generation of stimulatory TSHR Abs in genetically predisposed individuals.

MYMD-1, a Novel Immunometabolic Regulator, Ameliorates Autoimmune Thyroiditis via Suppression of Th1 Responses and TNF-α Release

MYMD-1 is a synthetic derivative of tobacco alkaloids, compounds that possess immunoregulatory properties and have been linked to the epidemiological observation that smoking reduces the odds of developing thyroid Abs and hypothyroidism. To assess the effect and mechanism(s) of the action of MYMD-1, we chose the NOD.H-2h4 mouse model of spontaneous thyroiditis. We began in vitro using T cells isolated from NOD.H-2h4 spleens and found that MYMD-1 suppressed TNF-α production by CD4+ T cells in a dose-dependent manner. We then treated 58 NOD.H-2h4 mice for 12 wk with either unsupplemented water that contained (10 mice) or did not contain (16 mice) MYMD-1 (185 mg/l) or water supplemented with sodium iodide (500 mg/l) that contained (16 mice) or did not contain (16 mice) MYMD-1. Mice were bled at baseline and then every 2 wk until sacrifice. MYMD-1 decreased the incidence and severity (p < 0.001) of thyroiditis, as assessed by histopathology. Similarly, the number of CD3+ T cells and CD19+ B cells infiltrating the thyroid was dampened by MYMD-1, as assessed by flow cytometry. Interestingly, the subset of thyroidal CD3+CD4+Tbet+RORγT- effector Th1 cells and the systemic levels of TNF-α were decreased by MYMD-1. Serum thyroglobulin Abs decreased in the MYMD-1 group. Thyroid hormones did not differ among the four groups, whereas thyroid-stimulating hormone increased upon iodine supplementation but remained normal in MYMD-1-treated mice. Overall, the study suggests that MYMD-1 ameliorates thyroiditis acting on specific lymphoid subsets. Further studies, including other models of autoimmunity, will confirm the potential clinical use of MYMD-1 as a novel immunometabolic regulator.

Lack of acute xenogeneic graft- versus-host disease, but retention of T-cell function following engraftment of human peripheral blood mononuclear cells in NSG mice deficient in MHC class I and II expression

Immunodeficient mice engrafted with human peripheral blood mononuclear cells (PBMCs) support preclinical studies of human pathogens, allograft rejection, and human T-cell function. However, a major limitation of PBMC engraftment is development of acute xenogeneic graft- versus-host disease (GVHD) due to human T-cell recognition of murine major histocompatibility complex (MHC). To address this, we created 2 NOD- scid IL-2 receptor subunit γ ( IL2rg) null (NSG) strains that lack murine MHC class I and II [NSG-β-2-microglobulin ( B2M) null ( IA IE)null and NSG -( Kb Db) null ( IAnull)]. We observed rapid human IgG clearance in NSG- B2Mnull ( IA IE) null mice whereas clearance in NSG -( Kb Db) null ( IAnull) mice and NSG mice was comparable. Injection of human PBMCs into both strains enabled long-term engraftment of human CD4+ and CD8+ T cells without acute GVHD. Engrafted human T-cell function was documented by rejection of human islet allografts. Administration of human IL-2 to NSG -( Kb Db) null ( IAnull) mice via adeno-associated virus vector increased human CD45+ cell engraftment, including an increase in human regulatory T cells. However, high IL-2 levels also induced the development of GVHD. These data document that NSG mice deficient in murine MHC support studies of human immunity in the absence of acute GVHD and enable evaluation of human antibody therapeutics targeting human T cells.-Brehm, M. A., Kenney, L. L., Wiles, M. V., Low, B. E., Tisch, R. M., Burzenski, L., Mueller, C., Greiner, D. L., Shultz, L. D. Lack of acute xenogeneic graft- versus-host disease, but retention of T-cell function following engraftment of human peripheral blood mononuclear cells in NSG mice deficient in MHC class I and II expression.

MicroRNA-326 contributes to autoimmune thyroiditis by targeting the Ets-1 protein

PURPOSE

MicroRNA-326 (miR-326), as a member of the microRNA (miRNA) family, which includes endogenous single-stranded, conserved, noncoding small RNAs, has been reported to play important roles in autoimmune diseases such as multiple sclerosis and systemic lupus erythematosus. However, few studies of the role of miR-326 in autoimmune thyroiditis (AIT) have been published. Here, we explored the roles of miR-326 and the involved pathway in iodine-induced AIT.

METHODS

NOD.H-2^h4 mice, which are a model of human AIT, were randomly divided into a normal water control group and a high-iodine group. Mice in the high-iodine group were administered 0.05% NaI (~1000 times the normal daily iodine intake), and mice in the control group received sterile water. Furthermore, we evaluated small interfering RNA (siRNA) interference in spleen mononuclear cell experiments in vitro.

RESULTS

In this study, we found that Th17 cells were significantly increased with a high expression of miR-326 in an iodine-induced thyroiditis NOD.H-2^h4 mouse model. In addition, the expression of Ets-1 protein, a negative regulator of Th17 differentiation, was significantly decreased. Intriguingly, our analysis showed that Ets-1 protein expression was negatively correlated with miR-326 levels in AIT mice (r = -0.814, p < 0.01). Our study indicated that miR-326 inhibited Ets-1 protein expression and promoted the differentiation of Th17 cells during the onset and development of AIT. The addition of a miR-326 inhibitor reversed Th17 cell production and Ets-1 protein expression, supporting this hypothesis.

CONCLUSIONS

The results of our study suggest that miR-326 may target the Ets-1 protein to contribute to iodide-induced thyroiditis, providing a new theoretical basis for the use of miRNA targeting therapy for the treatment of autoimmune diseases.

Aberrant Iodine Autoregulation Induces Hypothyroidism in a Mouse Strain in the Absence of Thyroid Autoimmunity

We investigated factors underlying the varying effects of a high dietary iodide intake on serum T4 levels in a wide spectrum of mouse strains, including thyroiditis-susceptible NOD.H2h4, NOD.H2k, and NOD mice, as well as other strains (BALB/c, C57BL/6, NOD.Lc7, and B10.A4R) not previously investigated. Mice were maintained for up to 8 months on control or iodide-supplemented water (NaI 0.05%). On iodized water, serum T4 was reduced in BALB/c (males and females) in association with colloid goiters but was not significantly changed in mice that developed thyroiditis, namely NOD.H2h4 (males and females) or male NOD.H2k mice. Neither goiters nor decreased T4 developed in C57BL/6, NOD, NOD.Lc7, or B10.A4R female mice. In further studies, we focused on males in the BALB/c and NOD.H2h4 strains that demonstrated a large divergence in the T4 response to excess iodide. Excess iodide ingestion increased serum TSH levels to the same extent in both strains, yet thyroidal sodium iodide symporter (NIS) messenger RNA (mRNA) levels (quantitative polymerase chain reaction) revealed greatly divergent responses. NOD.H2h4 mice that remained euthyroid displayed a physiological NIS iodine autoregulatory response, whereas NIS mRNA was inappropriately elevated in BALB/c mice that became hypothyroid. Thus, autoimmune thyroiditis-prone NOD.H2h4 mice adapted normally to a high iodide intake, presumably by escape from the Wolff-Chaikoff block. In contrast, BALB/c mice that did not spontaneously develop thyroiditis failed to escape from this block and became hypothyroid. These data in mice may provide insight into the mechanism by which iodide-induced hypothyroidism occurs in some humans without an underlying thyroid disorder.

Autoimmune manifestations in aged mice arise from early-life immune dysregulation

Autoantibodies can be present years to decades before the onset of disease manifestations in autoimmunity. This finding suggests that the initial autoimmune trigger involves a peripheral lymphoid component, which ultimately drives disease pathology in local tissues later in life. We show that Sjögren's syndrome manifestations that develop in aged NOD.H-2h4 mice were driven by and dependent on peripheral dysregulation that arose in early life. Specifically, elimination of spontaneous germinal centers in spleens of young NOD.H-2h4 mice by transient blockade of CD40 ligand (CD40L) or splenectomy abolished Sjögren's pathology of aged mice. Strikingly, a single injection of anti-CD40L at 4 weeks of age prevented tertiary follicle neogenesis and greatly blunted the formation of key autoantibodies implicated in glandular pathology, including anti-muscarinic receptor antibodies. Microarray profiling of the salivary gland characterized the expression pattern of genes that increased with disease progression and showed that early anti-CD40L greatly repressed B cell function while having a broader effect on multiple biological pathways, including interleukin-12 and interferon signaling. A single prophylactic treatment with anti-CD40L also inhibited the development of autoimmune thyroiditis and diabetes in NOD.H-2h4 and nonobese diabetic mice, respectively, supporting a key role for CD40L in the pathophysiology of several autoimmune models. These results strongly suggest that early peripheral immune dysregulation gives rise to autoimmune manifestations later in life, and for diseases predated by autoantibodies, early prophylactic intervention with biologics may prove efficacious.

Genes Outside the Major Histocompatibility Complex Locus Are Linked to the Development of Thyroid Autoantibodies and Thyroiditis in NOD.H2h4 Mice

Thyroiditis and autoantibodies to thyroglobulin (TgAb) and thyroid peroxidase (TPOAb) develop spontaneously in NOD.H2h4 mice, a phenotype enhanced by dietary iodine. NOD.H2h4 mice were derived by introducing the major histocompatibility class (MHC) molecule I-Ak from B10.A(4R) mice to nonobese diabetic (NOD) mice. Apart from I-Ak, the genes responsible for the NOD.H2h4 phenotype are unknown. Extending serendipitous observations from crossing BALB/c to NOD.H2h4 mice, thyroid autoimmunity was investigated in both genders of the F1, F2, and the second-generation backcross of F1 to NOD.H2h4 (N2). Medium-density linkage analysis was performed on thyroid autoimmunity traits in F2 and N2 progeny. TgAb develop before TPOAb and were measured after 8 and 16 weeks of iodide exposure; TPOAb and thyroiditis were studied at 16 weeks. TgAb, TPOAb, and thyroiditis, absent in BALB/c and F1 mice, developed in most NOD.H2h4 and in more N2 than F2 progeny. No linkages were observed in F2 progeny, probably because of the small number of autoantibody-positive mice. In N2 progeny (equal numbers of males and females), a chromosome 17 locus is linked to thyroiditis and TgAb and is suggestively linked to TPOAb. This locus includes MHC region genes from B10.A(4R) mice (such as I-Ak and Tnf, the latter involved in thyrocyte apoptosis) and genes from NOD mice such as Satb1, which most likely plays a role in immune tolerance. In conclusion, MHC and non-MHC genes, encoded within the chromosome 17 locus from both B10.A(4R) and NOD strains, are most likely responsible for the Hashimoto disease-like phenotype of NOD.H2h4 mice.

Exacerbation of Autoimmune Thyroiditis by CTLA-4 Blockade: A Role for IFNγ-Induced Indoleamine 2, 3-Dioxygenase

BACKGROUND

Cytotoxic T-lymphocyte associated protein 4 (CTLA-4) is a negative regulator of immune responses that suppresses the activity of effector T cells and contributes to the maintenance of self tolerance. When blocked therapeutically, CTLA-4 leads to an overall activation of T cells that has been exploited for cancer control, a control associated however with a variety of immune-related side effects such as autoimmune thyroiditis. To investigate the mechanism(s) underlying this form of thyroiditis, we used the NOD-H2(h4) mouse, a model that develops thyroiditis at very high incidence after addition of iodine to the drinking water.

METHODS

NOD-H2(h4) mice were started on drinking water supplemented with 0.05% sodium iodide when 8 weeks old and then injected with a hamster monoclonal antibody against mouse CTLA-4, polyclonal hamster immunoglobulins, or phosphate buffered saline when 11 weeks old. One month later (15 weeks of age), mice were sacrificed to assess thyroiditis, general immune responses in blood and spleen, and expression of indoleamine 2, 3-dioxygenase (IDO) in the thyroid and in isolated antigen-presenting cells after stimulation with interferon gamma. The study also analyzed IDO expression in four autopsy cases of metastatic melanoma who had received treatment with a CTLA-4 blocking antibody, and six surgical pathology Hashimoto thyroiditis controls.

RESULTS

CTLA-4 blockade worsened autoimmune thyroiditis, as assessed by a greater incidence, a more aggressive mononuclear cell infiltration in thyroids, and higher thyroglobulin antibody levels when compared to the control groups. CTLA-4 blockade also expanded the proportion of splenic CD4+ effector T cells, as well as the production of interleukin (IL)-2, interferon gamma, IL-10, and IL-13 cytokines. Interestingly, CTLA-4 blockade induced a strong expression of IDO in mouse and human thyroid glands, an expression that could represent a counter-regulatory mechanism to protect against the inflammatory environment.

CONCLUSIONS

This study shows that CTLA-4 blockade exacerbates the iodine-accelerated form of thyroiditis typical of the NOD-H2(h4) mouse. The study could also have implications for cancer patients who develop thyroiditis as an immune-related adverse event after CTLA-4 blockade.

TCR transgenic mice reveal the impact of type 1 diabetes loci on early and late disease checkpoints

Linkage analysis studies for autoimmune diabetes have revealed multiple non-major histocompatibility complex (MHC) chromosomal regions linked to disease susceptibility. To date, more than 20 insulin-dependent diabetes (Idd) loci linked to diabetes susceptibility have been identified in NOD mice and validated via congenic breeding. Importantly, evidence suggests that Idd loci may regulate at least two pathological steps during autoimmune diabetes development, namely the onset of insulitis and the transition from insulitis to overt diabetes. Here we assess the role of various non-MHC Idd diabetes-resistance loci, which have been validated in the non-transgenic setting, on autoimmune diabetes progression in the transgenic setting. Specifically, we generated multiple Idd congenic strains in the 3A9-TCR:insHEL NOD.H2(k) transgenic model and monitored their diabetes incidence. We show that 3A9-TCR:insHEL NOD.H2(k) mice congenic for Idd3 or Idd5 display a reduction in diabetes development, whereas mice congenic for Idd9 or Idd13 exhibit an increase, in comparison with 3A9-TCR:insHEL NOD.H2(k) mice. These results suggest that the presence of the 3A9-TCR and hen egg lysosyme transgenes can offset the regulatory function of certain diabetes-resistance genetic variants contained within the Idd loci, including Idd9 and Idd13. We propose the antigen-specific 3A9-TCR:insHEL transgenic model as a useful tool for the study of the genetics of autoimmune diabetes development.

Genetic predisposition for beta cell fragility underlies type 1 and type 2 diabetes

Type 1 (T1D) and type 2 (T2D) diabetes share pathophysiological characteristics, yet mechanistic links have remained elusive. T1D results from autoimmune destruction of pancreatic beta cells, whereas beta cell failure in T2D is delayed and progressive. Here we find a new genetic component of diabetes susceptibility in T1D non-obese diabetic (NOD) mice, identifying immune-independent beta cell fragility. Genetic variation in Xrcc4 and Glis3 alters the response of NOD beta cells to unfolded protein stress, enhancing the apoptotic and senescent fates. The same transcriptional relationships were observed in human islets, demonstrating the role of beta cell fragility in genetic predisposition to diabetes.

Genes and environment as predisposing factors in autoimmunity: acceleration of spontaneous thyroiditis by dietary iodide in NOD.H2(h4) mice

In the field of autoimmune thyroiditis, NOD.H2(h4) mice have attracted significant and increasing attention since they not only develop spontaneous disease but they present thyroiditis with accelerated incidence and severity if they ingest iodide through their drinking water. This animal model highlights the interplay between genetic and dietary factors in the triggering of autoimmune disease and offers new opportunities to study immunoregulatory parameters influenced by both genes and environment. Here, we review experimental findings with this mouse model of thyroiditis.

Regulatory T cells in B-cell-deficient and wild-type mice differ functionally and in expression of cell surface markers

NOD.H-2h4 mice develop spontaneous autoimmune thyroiditis (SAT) with chronic inflammation of thyroids by T and B cells. B-cell deficient (B(-/-) ) mice are resistant to SAT but develop SAT if regulatory T (Treg) cells are transiently depleted. We established a transfer model using splenocytes from CD28(-/-)  B(-/-) mice (effector cells and antigen-presenting cells) cultured with or without sorted Treg cells from Foxp3-GFP wild-type (WT) or B(-/-) mice. After transfer to mice lacking T cells, mice given Treg cells from B(-/-) mice had significantly lower SAT severity scores than mice given Treg cells from WT mice, indicating that Treg cells in B(-/-) mice are more effective suppressors of SAT than Treg cells in WT mice. Treg cells from B(-/-) mice differ from WT Treg cells in expression of CD27, tumour necrosis factor receptor (TNFR) II p75, and glucocorticoid-induced TNFR-related protein (GITR). After transient depletion using anti-CD25 or diphtheria toxin, the repopulating Treg cells in B(-/-) mice lack suppressor function, and expression of CD27, GITR and p75 is like that of WT Treg cells. If B(-/-) Treg cells develop with B cells in bone marrow chimeras, their phenotype is like that of WT Treg cells. Addition of B cells to cultures of B(-/-) Treg and T effector cells abrogates their suppressive function and their phenotype is like that of WT Treg cells. These results establish for the first time that Treg cells in WT and B(-/-) mice differ both functionally and in expression of particular cell surface markers. Both properties are altered after transient depletion and repopulation of B(-/-) Treg cells, and by the presence of B cells during Treg cell development or during interaction with effector T cells.

Evidence that MHC I-E dampens thyroid autoantibodies and prevents spreading to a second thyroid autoantigen in I-A(k) NOD mice

NOD.H2^k and NOD.H2^h4 mice carry the MHC class II molecule I-A^k associated with susceptibility to experimentally-induced thyroiditis. Dietary iodine enhanced spontaneous thyroid autoimmunity, well known in NOD.H2^h4 mice, has not been investigated in NOD.H2^k mice. We compared NOD.H2^h4 and NOD.H2^k strains for thyroiditis and autoantibodies to thyroglobulin (TgAb) and thyroid peroxidase (TPOAb) without or with dietary sodium iodide (NaI) for up to 32 weeks. TgAb levels were significantly higher in NOD.H2^h4 than NOD.H2^k mice on NaI and TPOAb developed in NOD.H2^h4 but not NOD.H2^k mice. DNA exome analysis revealed, in addition to the differences in the chromosome (Chr) 17 MHC regions, that NOD.H2^k and particularly NOD.H2^h4 mice have substantial non-MHC parental DNA. KEGG pathway-analysis highlighted thyroid autoimmunity and immune-response genes on Chr 17 but not on Chr 7 and 15 parental B10.A4R DNA. Studies of parental strains provided no evidence for non-MHC gene contributions. The exon 10 thyroglobulin haplotype, associated with experimentally-induced thyroiditis, is absent in NOD.H2^h4 and NOD.H2^k mice and is not a marker for spontaneous murine thyroid autoimmunity. In conclusion, the absence of I-E is a likely explanation for the difference between NOD.H2^h4 and NOD.H2^k mice in TgAb levels and, as in humans, autoantibody spreading to TPO.

NOD.H-2h4 mice: an important and underutilized animal model of autoimmune thyroiditis and Sjogren's syndrome

NOD.H-2h4 mice express the K haplotype on the NOD genetic background. They spontaneously develop thyroiditis and Sjogren's syndrome, but they do not develop diabetes. Although autoimmune thyroid diseases and Sjogren's syndrome are highly prevalent autoimmune diseases in humans, there has been relatively little emphasis on the use of animal models of these diseases for understanding basic mechanisms involved in development and therapy of chronic organ-specific autoimmune diseases. The goal of this review is to highlight some of the advantages of NOD.H-2h4 mice for studying basic mechanisms involved in development of autoimmunity. NOD.H-2h4 mice are one of relatively few animal models that develop organ-specific autoimmune diseases spontaneously, i.e., without a requirement for immunization with antigen and adjuvant, and in both sexes in a relatively short period of time. Thyroiditis and Sjogren's syndrome in NOD.H-2h4 mice are chronic autoimmune diseases that develop relatively early in life and persist for the life of the animal. Because the animals do not become clinically ill, the NOD.H-2h4 mouse provides an excellent model to test therapeutic protocols over a long period of time. The availability of several mutant mice on this background provides a means to address the impact of particular cells and molecules on the autoimmune diseases. Moreover, to our knowledge, this is the only animal model in which the presence or absence of a single cytokine, IFN-γ, is sufficient to completely inhibit one autoimmune thyroid disease, with a completely distinct autoimmune thyroid disease developing when it is absent.

The complete mitochondrial genome for an autoimmune thyroiditis mouse strain NOD.H-2h4

Autoimmune thyroiditis is a chronic organ-specific autoimmune disease characterized by mononuclear cell infiltration of the thyroid gland and destruction of thyroid follicles by the infiltrating inflammatory cells. We sequenced the complete mitochondrial genome sequencing of an autoimmune thyroiditis mouse strain NOD.H-2h4 for the first time. The total length of the mitogenome was 16,310 bp and contains 159 SNPs compared with the house mouse reference sequence.

Autoimmunity and antibody affinity maturation are modulated by genetic variants on mouse chromosome 12

Autoimmune diseases result from a break in immune tolerance leading to an attack on self-antigens. Autoantibody levels serve as a predictive tool for the early diagnosis of many autoimmune diseases, including type 1 diabetes. We find that a genetic locus on mouse chromosome 12 influences the affinity maturation of antibodies as well as autoantibody production. Thus, we generated a NOD.H2(k) congenic strain bearing B10 alleles at the locus comprised within the D12Mit184 and D12Mit12 markers, which we named NOD.H2(k)-Chr12. We determined the biological relevance of the Chr12 locus on the autoimmune process using an antigen-specific TCR transgenic autoimmune mouse model. Specifically, the 3A9 TCR transgene, which recognizes a peptide from hen egg lysozyme (HEL) in the context of I-A(k), and the HEL transgene, which is expressed under the rat-insulin promoter (iHEL), were bred into the NOD.H2(k)-Chr12 congenic strain. In the resulting 3A9 TCR:iHEL NOD.H2(k)-Chr12 mice, we observed a significant decrease in diabetes incidence as well as a decrease in both the quantity and affinity of HEL-specific IgG autoantibodies relative to 3A9 TCR:iHEL NOD.H2(k) mice. Notably, the decrease in autoantibodies due to the Chr12 locus was not restricted to the TCR transgenic model, as it was also observed in the non-transgenic NOD.H2(k) setting. Of importance, antibody affinity maturation upon immunization and re-challenge was also impeded in NOD.H2(k)-Chr12 congenic mice relative to NOD.H2(k) mice. Together, these results demonstrate that a genetic variant(s) present within the Chr12 locus plays a global role in modulating antibody affinity maturation.

A minor subset of Batf3-dependent antigen-presenting cells in islets of Langerhans is essential for the development of autoimmune diabetes

Autoimmune diabetes is characterized by inflammatory infiltration; however, the initiating events are poorly understood. We found that the islets of Langerhans in young nonobese diabetic (NOD) mice contained two antigen-presenting cell (APC) populations: a major macrophage and a minor CD103(+) dendritic cell (DC) population. By 4 weeks of age, CD4(+) T cells entered islets coincident with an increase in CD103(+) DCs. In order to examine the role of the CD103(+) DCs in diabetes, we examined Batf3-deficient NOD mice that lacked the CD103(+) DCs in islets and pancreatic lymph nodes. This led to a lack of autoreactive T cells in islets and, importantly, no incidence of diabetes. Additional examination revealed that presentation of major histocompatibility complex (MHC) class I epitopes in the pancreatic lymph nodes was absent with a partial impairment of MHC class II presentation. Altogether, this study reveals that CD103(+) DCs are essential for autoimmune diabetes development.

Apoptosis of NOD.H2 h4 thyrocytes by low concentrations of iodide is associated with impaired control of oxidative stress

BACKGROUND

Enhanced iodide intake in NOD.H2(h4) mice accelerates the incidence and severity of spontaneous autoimmune thyroiditis (SAT) via an unknown mechanism. A plausible hypothesis is that iodide-induced apoptosis of thyrocytes can create imbalances in antigenic load and/or disruption of immunoregulatory mechanisms that facilitate activation of autoreactive T cells in cervical lymph nodes draining the thyroid.

METHODS

We examined whether NOD.H2(h4) thyrocytes, exposed to low NaI concentrations in vitro, are more susceptible to apoptosis compared to thyrocytes from CBA/J mice, which are resistant to iodide-accelerated SAT (ISAT). We also looked, at the transcriptional level, for differential activation of genes involved in apoptosis or oxidative stress pathways that may account for potential differences in iodide-mediated apoptosis between NOD.H2(h4) and CBA/J thyrocytes.

RESULTS

We report that NOD.H2(h4) thyrocytes, cultured for 24 h at very low (4-8 μM) concentrations of NaI, exhibit high levels (40-55%) of apoptosis, as assessed microscopically following staining with fluorescent caspase inhibitors. Similar treatment of thyrocytes from CBA/J mice, which are resistant to ISAT, yielded significantly lower (10-20%) apoptotic rates. Expression analysis by real-time polymerase chain reaction using arrays of apoptosis- and oxidative stress-related genes showed that NaI intake upregulates the expression of 22 genes involved in ROS metabolism and/or antioxidant function in CBA/J thyrocytes, whereas only two of these genes were upregulated in NOD.H2(h4) thyrocytes. Among the set of overexpressed genes were those encoding thyroid peroxidase (Tpo; 5.77-fold), glutathione peroxidases (Gpx2, Gpx4, Gpx7; 2.03-3.14-fold), peroxiredoxins (Prdx1, Prdx2, Prdx5; 2.27-2.97-fold), superoxide dismutase 1 (Sod1; 3.57-fold), thioredoxin 1 (Txn1; 2.13-fold), and the uncoupling proteins 2 and 3 (Ucp2, Ucp3; 2.01-2.15-fold).

CONCLUSIONS

The results demonstrate that an impaired control of oxidative stress mechanisms is associated with the observed high susceptibility of NOD.H2(h4) thyrocytes to NaI-mediated apoptosis, and suggest a contributing factor for the development of ISAT in this strain.

High salt intake does not exacerbate murine autoimmune thyroiditis

Recent studies have shown that high salt (HS) intake exacerbates experimental autoimmune encephalomyelitis and have raised the possibility that a HS diet may comprise a risk factor for autoimmune diseases in general. In this report, we have examined whether a HS diet regimen could exacerbate murine autoimmune thyroiditis, including spontaneous autoimmune thyroiditis (SAT) in non-obese diabetic (NOD.H2(h4)) mice, experimental autoimmune thyroiditis (EAT) in C57BL/6J mice challenged with thyroglobulin (Tg) and EAT in CBA/J mice challenged with the Tg peptide (2549-2560). The physiological impact of HS intake was confirmed by enhanced water consumption and suppressed aldosterone levels in all strains. However, the HS treatment failed to significantly affect the incidence and severity of SAT or EAT or Tg-specific immunoglobulin (Ig)G levels, relative to control mice maintained on a normal salt diet. In three experimental models, these data demonstrate that HS intake does not exacerbate autoimmune thyroiditis, indicating that a HS diet is not a risk factor for all autoimmune diseases.

A ZAP-70 kinase domain variant prevents thymocyte-positive selection despite signalling CD69 induction

Quantitative reductions in T-cell receptor (TCR) signalling are associated with severe immunodeficiency, yet in certain cases can lead to autoimmunity. Mutation of the tyrosine kinase ZAP-70 can cause either of these outcomes, yet the limits of its signal transducing capacity are not well defined. To investigate these limits we have made use of mrtless: a chemically induced mutation of Zap70 associated with T-cell deficiency. Unlike cells devoid of ZAP-70, mrtless thymocytes showed partial induction of CD5 and CD69, and were sensitive to TCR stimulation with a dose-response shifted approximately 10-fold. However, essentially no T cells were able to compensate for the mrtless mutation and mature beyond the CD4⁺ CD8⁺ stage. This outcome contrasts with a ZAP-70 Src Homology 2 domain mutant strain, where high-affinity self-reactive TCR are positively selected rather than deleted. We discuss these data with respect to current models of TCR signalling in thymocyte selection.

Reduced effectiveness of CD4+Foxp3+ regulatory T cells in CD28-deficient NOD.H-2h4 mice leads to increased severity of spontaneous autoimmune thyroiditis

NOD.H-2h4 mice given NaI in their drinking water develop iodine-accelerated spontaneous autoimmune thyroiditis (ISAT) with chronic inflammation of the thyroid by T and B cells and production of anti-mouse thyroglobulin (MTg) autoantibody. CD28(-/-) NOD.H-2h4 mice, which have reduced numbers of CD4(+)Foxp3(+) regulatory T cells (Tregs), were developed to examine the role of Tregs in ISAT development. CD28(-/-) NOD.H2-h4 mice develop more severe ISAT than do wild-type (WT) mice, with collagen deposition (fibrosis) and low serum T4. CD28(-/-) mice have increased expression of proinflammatory cytokines IFN-γ and IL-6, consistent with increased mononuclear cell infiltration and tissue destruction in thyroids. Importantly, transferring purified CD4(+)Foxp3(+) Tregs from WT mice reduces ISAT severity in CD28(-/-) mice without increasing the total number of Tregs, suggesting that endogenous Tregs in CD28(-/-) mice are functionally ineffective. Endogenous CD28(-/-) Tregs have reduced surface expression of CD27, TNFR2 p75, and glucocorticoid-induced TNFR-related protein compared with transferred CD28(+/+) Tregs. Although anti-MTg autoantibody levels generally correlate with ISAT severity scores in WT mice, CD28(-/-) mice have lower anti-MTg autoantibody responses than do WT mice. The percentages of follicular B cells are decreased and those of marginal zone B cells are increased in spleens of CD28(-/-) mice, and they have fewer thyroid-infiltrating B cells than do WT mice. This suggests that CD28 deficiency has direct and indirect effects on the B cell compartment. B cell-deficient (B(-/-)) NOD.H-2h4 mice are resistant to ISAT, but CD28(-/-)B(-/-) mice develop ISAT comparable to WT mice and have reduced numbers of Tregs compared with WT B(-/-) mice.

Distinct genetic control of autoimmune neuropathy and diabetes in the non-obese diabetic background

The non-obese diabetic (NOD) mouse is susceptible to the development of autoimmune diabetes but also multiple other autoimmune diseases. Over twenty susceptibility loci linked to diabetes have been identified in NOD mice and progress has been made in the definition of candidate genes at many of these loci (termed Idd for insulin-dependent diabetes). The susceptibility to multiple autoimmune diseases in the NOD background is a unique opportunity to examine susceptibility genes that confer a general propensity for autoimmunity versus susceptibility genes that control individual autoimmune diseases. We previously showed that NOD mice deficient for the costimulatory molecule B7-2 (NOD-B7-2KO mice) were protected from diabetes but spontaneously developed an autoimmune peripheral neuropathy. Here, we took advantage of multiple NOD mouse strains congenic for Idd loci to test the role of these Idd loci the development of neuropathy and determine if B6 alleles at Idd loci that are protective for diabetes will also be for neuropathy. Thus, we generated NOD-B7-2KO strains congenic at Idd loci and examined the development of neuritis and clinical neuropathy. We found that the NOD-H-2(g7) MHC region is necessary for development of neuropathy in NOD-B7-2KO mice. In contrast, other Idd loci that significantly protect from diabetes did not affect neuropathy when considered individually. However, we found potent genetic interactions of some Idd loci that provided almost complete protection from neuritis and clinical neuropathy. In addition, defective immunoregulation by Tregs could supersede protection by some, but not other, Idd loci in a tissue-specific manner in a model where neuropathy and diabetes occurred concomitantly. Thus, our study helps identify Idd loci that control tissue-specific disease or confer general susceptibility to autoimmunity, and brings insight to the Treg-dependence of autoimmune processes influenced by given Idd region in the NOD background.

Transient depletion of B cells in young mice results in activation of regulatory T cells that inhibit development of autoimmune disease in adults

B-cell depletion therapy can be effective for treating B-cell lymphomas as well as many human and murine autoimmune diseases. B-cell-deficient mice are normally resistant to spontaneous autoimmune thyroiditis (SAT), but they develop SAT if regulatory T cells are transiently depleted during the first 3-6 weeks after birth. This was also a critical time when B-cell depletion effectively inhibited development of SAT in adult mice. The current study was undertaken to test the hypothesis that transient depletion of B cells using anti-CD20 would be sufficient to suppress SAT if B cells were depleted early in life and that inhibition of SAT would be due to the activity of Treg that functioned most effectively when B cells were absent or low. The results presented here support this hypothesis and indicate that development of autoimmune disease in adults is effectively inhibited when anti-CD20 is administered 1-3 weeks after birth. After 3 weeks, transient B-cell depletion is no longer effective, and B-cell depletion must be maintained to effectively suppress autoimmune disease. B-cell depletion in 1- to 3-week-old mice depletes all B-cell subsets, whereas B-cell depletion initiated in adults spares many marginal zone B cells. Following early B-cell depletion, splenic Treg increase in number, and depletion of Treg reverses the inhibitory effect of anti-CD20 on disease development. Early transient depletion of B cells could be useful for preventing autoimmune disease in individuals at high risk for developing autoimmune diseases as adults.

TGF-β promotes proliferation of thyroid epithelial cells in IFN-γ(-/-) mice by down-regulation of p21 and p27 via AKT pathway

IFN-γ(-/-) NOD.H-2h4 mice develop an autoimmune disease characterized by hyperplasia and proliferation of thyroid epithelial cells (TEC H/P). Proliferating TECs produce TGF-β, and IFN-γ inhibits TEC H/P. In the present study, cultured TECs were used to directly determine the mechanisms by which these cytokines act on TECs to result in proliferation or inhibition of proliferation. With TECs from IFN-γ(-/-) NOD.H-2h4 mice or mice expressing the dominant negative TGF-β type II receptor on TECs, TGF-β was shown to promote TEC proliferation and IFN-γ was shown to inhibit TEC proliferation in vitro. TGF-β may promote TEC proliferation by down-regulating antiproliferative molecules p21 and p27, whereas IFN-γ may inhibit proliferation by up-regulating antiproliferative molecules p18 and p21 and down-regulating the pro-proliferative molecule cyclin D. Inhibition of AKT abolished the effect of TGF-β on p21 and p27, resulting in similar proliferation of TGF-β-treated and control TECs. Increased expression of proliferating cell nuclear antigen (PCNA), TGF-β, and p-AKT and decreased expression of p21 and p27 by proliferating TECs correlated with the proliferative state of TEC H/P. Taken together, the results suggest that TGF-β promotes TEC proliferation by down-regulating p21 and p27 via the AKT pathway in IFN-γ(-/-) NOD.H-2h4 mice, which may have significant implications for development of effective therapeutic strategies targeting the TGF-β and AKT pathways for treatment of hyperplasia and/or neoplasia.

Induction of autoimmune thyroiditis by depletion of CD4+CD25+ regulatory T cells in thyroiditis-resistant IL-17, but not interferon-gamma receptor, knockout nonobese diabetic-H2h4 mice

Iodine-induced experimental autoimmune thyroiditis in the nonobese diabetic (NOD)-H2h4 mouse is a prototype of animal models of Hashimoto's thyroiditis in humans. Recent studies have shown the resistance to thyroiditis of NOD-H2h4 mice genetically deficient for either IL-17 or interferon (IFN)-γ, implicating both of T helper type 1 (Th1) and Th17 immune responses in disease pathogenesis. However, we hypothesized that robust induction of a single arm of effector T cells (either Th1 or Th17) might be sufficient for inducing thyroiditis in NOD-H2h4 mice. To address this hypothesis, enhanced immune responses consisting of either Th1 or Th17 were induced by anti-CD25 antibody-mediated depletion of regulatory T cells (Treg) in thyroiditis-resistant IL-17 knockout (KO) or IFN-γ receptor (IFN-γR) KO, respectively, NOD-H2h4 mice. Depletion of Treg in IL-17 KO mice (i.e. Th1 enhancement) elicited antithyroglobulin autoantibodies and thyroiditis. Immunohistochemical analysis of the thyroid glands revealed the similar intrathyroidal lymphocyte infiltration patterns, with CD4+ T and CD19+ B cells being dominant between the wild-type and Treg-depleted IL-17 KO mice. In contrast, Treg-depleted IFN-γR KO mice remained thyroiditis resistant. Intracellular cytokine staining assays showed differentiation of Th1 cells in IL-17 KO mice but not of Th17 cells in IFN-γR KO mice. Our findings demonstrate that a robust Th1 immune response can by itself induce thyroiditis in otherwise thyroiditis-resistant IL-17 KO mice. Thus, unlike Th17 cells in IFN-γR KO mice, Th1 cells enhanced by Treg depletion can be sustained and induce thyroiditis.

Current concepts: mouse models of Sjögren's syndrome

Sjögren's syndrome (SjS) is a complex chronic autoimmune disease of unknown etiology which primarily targets the exocrine glands, resulting in eventual loss of secretory function. The disease can present as either primary SjS or secondary SjS, the latter of which occurs concomitantly with another autoimmune disease such as rheumatoid arthritis, systemic lupus erythematosus, scleroderma, or primary biliary cirrhosis. Current advancements in therapeutic prevention and treatment for SjS are impeded by lack of understanding in the pathophysiological and clinical progression of the disease. Development of appropriate mouse models for both primary and secondary SjS is needed in order to advance knowledge of this disease. This paper details important features, advantages, and pitfalls of current animal models of SjS, including spontaneous, transgenic, knockout, immunization, and transplantation chimera mouse models, and emphasizes the need for a better model in representing the human SjS phenotype.

Graded attenuation of TCR signaling elicits distinct autoimmune diseases by altering thymic T cell selection and regulatory T cell function

Mice with a mutation of the zeta-associated protein of 70 kDa gene (skg mutation) are genetically prone to develop autoimmune arthritis, depending on the environment. In a set of mice with the mutation, the amount of zeta-associated protein of 70 kDa protein as well as its tyrosine phosphorylation upon TCR stimulation decreased from +/+, skg/+, skg/skg, to skg/- mice in a stepwise manner. The reduction resulted in graded alterations of thymic positive and negative selection of self-reactive T cells and Foxp3(+) natural regulatory T cells (Tregs) and their respective functions. Consequently, skg/- mice spontaneously developed autoimmune arthritis even in a microbially clean environment, whereas skg/skg mice required stimulation through innate immunity for disease manifestation. After Treg depletion, organ-specific autoimmune diseases, especially autoimmune gastritis, predominantly developed in +/+, at a lesser incidence in skg/+, but not in skg/skg BALB/c mice, which suffered from other autoimmune diseases, especially autoimmune arthritis. In correlation with this change, gastritis-mediating TCR transgenic T cells were positively selected in +/+, less in skg/+, but not in skg/skg BALB/c mice. Similarly, on the genetic background of diabetes-prone NOD mice, diabetes spontaneously developed in +/+, at a lesser incidence in skg/+, but not in skg/skg mice, which instead succumbed to arthritis. Thus, the graded attenuation of TCR signaling alters the repertoire and the function of autoimmune T cells and natural Tregs in a progressive manner. It also changes the dependency of disease development on environmental stimuli. These findings collectively provide a model of how genetic anomaly of T cell signaling contributes to the development of autoimmune disease.

Sjögren syndrome: advances in the pathogenesis from animal models

Sjögren syndrome is an autoimmune disease characterized by hyposecretion of the lacrimal and salivary glands, resulting in dryness of the eyes and mouth. Individuals may experience primary Sjögren syndrome or a secondary form accompanying another rheumatic autoimmune disease, such as rheumatoid arthritis or systemic lupus erythematosus. The pathogenic mechanisms of Sjögren syndrome remain largely unknown, in part a consequence of the heterogeneity of the disease. Animal models have shed light on the connections between specific pathways and symptoms, but an ideal system is wanting. Improved disease models will enable a better understanding of Sjögren syndrome, including how immune tolerance is lost and potential therapeutic interventions. Most importantly, an optimal model will enable detection of disease biomarkers, since injury to the salivary glands may precede lymphocytic infiltration. This review aims to characterize available mice models of Sjögren syndrome, including advantages and disadvantages, from the researcher's perspective.

T helper type 17 immune response plays an indispensable role for development of iodine-induced autoimmune thyroiditis in nonobese diabetic-H2h4 mice

T helper type 1(Th1)/Th2 paradigm has been expanded by discovery of a novel effector T cell (T(eff)) subset, Th17 cells, which produce a proinflammatory cytokine IL-17. Th17 cells have recently been shown to play a major role in numerous autoimmune diseases that had previously been thought to be Th1-dominant diseases. We here studied the significance of Th17 cells in iodine-induced autoimmune thyroiditis in nonobese diabetic-H2(h4) mice, a mouse model of Hashimoto's thyroiditis in humans, which spontaneously develop antithyroglobulin autoantibodies and intrathyroidal lymphocyte infiltration when supplied with iodine in the drinking water. We observed increased numbers of Th1 and Th17 cells in spleen and accumulation of both types of T(eff) in the thyroid glands of iodine-fed wild-type mice, indicating that Th17 cells as well as Th1 cells constitute thyroid lesions. Furthermore, the incidence and severity of intrathyroidal lymphocyte infiltration, and the titers of antithyroglobulin autoantibodies were markedly reduced in iodine-treated IL-17(-/-) mice as compared with wild-type mice. Of interest, IL-17(+/-) mice showed an intermediate phenotype. Therefore, the present study, together with a previous report demonstrating the importance of Th1, not Th2, immune response for developing thyroiditis using mice deficient for interferon-gamma or IL-4, clearly indicates that both Th1 and Th17 cells are critical T(eff) subsets for the pathogenesis of spontaneous autoimmune thyroiditis in nonobese diabetic-H2(h4) mice.

CCR7 deficiency in NOD mice leads to thyroiditis and primary hypothyroidism

CCR7 is involved in the initiation of immune responses and has been recently implicated in the control of tolerance. To analyze the role of CCR7 in autoimmunity, we backcrossed CCR7(ko/ko) mice (in which ko signifies deficient) onto the autoimmune-prone NOD background. Surprisingly, NODCCR7(ko/ko) mice never developed diabetes, but showed severe inflammation in multiple tissues including thyroid, lung, stomach, intestine, uterus, and testis. NODCCR7(ko/ko) mice had a marked enlargement of the thyroid gland (goiter) that was associated with circulating autoantibodies against thyroglobulin, and development of primary hypothyroidism (decreased levels of serum thyroxin, and augmented levels of thyroid-stimulating hormone in the pituitary gland), features found in Hashimoto's thyroiditis. Cells isolated from diseased thyroids and activated splenocytes from NODCCR7(ko/ko) animals induced goiter in NOD.SCID recipients, demonstrating that autoreactive cells were generated in the absence of CCR7. Moreover, thyroid disease could be accelerated in young NODCCR7(ko/ko) mice by immunization with thyroglobulin. These results demonstrate the complexity in the generation of multiple autoimmune phenotypes in NOD mice and indicate that CCR7 is a key molecule in their development.

Cutting edge: genetic characterization of IFN-producing killer dendritic cells

The combined phenotypic expression of CD11c(low)B220(+)CD122(+)DX5(+) has been used to define a novel cell type termed IFN-producing killer dendritic cells (IKDC). IKDC readily produce IFN-gamma and demonstrate spontaneous cytotoxic activity toward tumors, suggesting that a modulation of IKDC number may be beneficial in cancer treatment. We examined various mouse strains and found that IKDC number was highly variable between the different strains. A linkage analysis associated the distal arm of chromosome 7 with variations in IKDC number. The genetic contribution of chromosome 7 to the regulation of IKDC number was confirmed through the use of congenic mice. We further demonstrate that IKDC proportion is regulated by intrinsic hematopoietic factors. We discuss the role of various candidate genes in the regulation of this newly described cell type and its implication in therapy.

Expression of immunoregulatory molecules by thyrocytes protects nonobese diabetic-H2h4 mice from developing autoimmune thyroiditis

One approach to prevent tissue destruction by autoimmune attack in organ-specific autoimmune diseases is to protect the target tissue from autoimmune reaction, regardless of its persistent activity. To provide proof-of-principle for the feasibility of this approach, the immunoregulatory molecules, TNF-related apoptosis-inducing ligand (TRAIL) and indoleamine 2, 3-dioxygenase, were expressed in the thyroid glands using adenovirus vector in nonobese diabetic-H2(h4) mice that spontaneously develop thyroiditis. Mice were anesthetized, and the thyroid glands were exposed by neck dissection, followed by in situ infection with adenovirus vector (5 x 10(10) particles per mouse) twice or thrice, starting 1 d or 4 wk before mice were supplied with sodium iodine (NaI) water. After 8 wk NaI provision, the extent of thyroiditis, serum titers of antithyroglobulin antibodies, and cytokine expression in the spleen were examined. In situ infection of adenovirus expressing TRAIL or indoleamine 2, 3-dioxygenase, but not green fluorescent protein, significantly suppressed thyroiditis scores. However, antithyroglobulin antibody titers and expression levels of cytokines (interferon-gamma and IL-4) in the spleen remained unaltered. Importantly, adenovirus infection 4 wk after NaI provision was also effective at suppressing thyroiditis. The suppressive effect of TRAIL appears to be mediated at least partly by accumulation of CD4(+)Foxp3(+) regulatory T cells into the thyroid glands. Thus, localized expression of immunoregulatory molecules efficiently protected the thyroid glands from autoimmune attack without changing the systemic autoimmunity in nonobese diabetic-H2(h4) mice. This kind of immunological intervention, although it does not suppress autoimmune reactivity, may have a potential for treating organ-specific autoimmune diseases.

Exacerbation of autoimmune thyroiditis by a single low dose of whole-body irradiation in non-obese diabetic-H2h4 mice

PURPOSE

To evaluate how irradiation affects thyroid autoimmunity in mouse models of Hashimoto's thyroiditis and Graves' hyperthyroidism.

MATERIALS AND METHODS

Non-obese diabetic (NOD)-H2(h4) mice spontaneously develop anti-thyroglobulin (Tg) antibodies and thyroiditis when supplied with sodium iodine (NaI) in the drinking water. BALB/c mice develop anti-thyrotropin receptor (TSHR) antibodies and hyperthyroidism following immunization with adenovirus expressing TSHR (Ad-TSHR). Mice were irradiated as follows: A single whole-body irradiation with 0.05, 0.5 or 3 Gy one week before or after the beginning of NaI or immunization with Ad-TSHR, fractionated whole-body irradiations with 0.05 Gy twice a week or 0.5 Gy once a week from one week before NaI or Ad-TSHR immunization, or a single regional irradiation to the thyroid gland with 0.5 Gy one week before NaI. The effect of a single irradiation with 0.05, 0.5 or 3 Gy on splenocytes was also evaluated.

RESULTS

A single whole-body irradiation with 0.5 Gy one week before NaI exacerbated thyroiditis and increased anti-Tg antibody titers in NOD-H2(h4) mice. In contrast, any irradiation protocols employed did not affect incidence of hyperthyroidism or anti-TSHR antibody titers in BALB/c mice. High-dose irradiation increased the relative ratios of effector T cells to regulatory T cells (an indication of enhanced immune status) but kills most of T cells.

CONCLUSIONS

These results indicate that a single whole-body low-dose irradiation with 0.5 Gy exacerbates thyroiditis in NOD-H2(h4) mice, data consistent with some clinical evidence for increased incidence of thyroid autoimmunity by environmental irradiation.

TGF-beta promotes thyroid epithelial cell hyperplasia and fibrosis in IFN-gamma-deficient NOD.H-2h4 mice

IFN-gamma(-/-)NOD.H-2h4 mice given 0.05% NaI in their water develop severe thyroid epithelial cell (thyrocyte) hyperplasia and proliferation (TEC H/P) and fibrosis. Proliferating thyrocytes of IFN-gamma(-/-) mice with TEC H/P produce TGF-beta as demonstrated by immunohistochemical staining and in situ hybridization. Strong expression of activating phosphorylated Smad-2/3 and weak expression of inhibitory Smad-7 by proliferating thyrocytes correlate with the severity of TEC H/P. Splenocytes from IFN-gamma(-/-) mice with severe TEC H/P transfer severe TEC H/P to IFN-gamma(-/-)NOD.H-2h4.SCID mice. Mice given anti-TGF-beta had markedly reduced thyrocyte proliferation and decreased fibrosis compared with mouse Ig-treated controls, suggesting that TGF-beta plays an important role in development of TEC H/P induced by activated splenocytes. Moreover, transgenic IFN-gamma(-/-)NOD.H-2h4 mice expressing TGF-beta on thyrocytes all develop fibrosis and moderate to severe TEC H/P with accelerated kinetics, directly demonstrating a role for TGF-beta in severe TEC H/P and fibrosis.

B cell depletion inhibits spontaneous autoimmune thyroiditis in NOD.H-2h4 mice

B cells are important for the development of most autoimmune diseases. B cell depletion immunotherapy has emerged as an effective treatment for several human autoimmune diseases, although it is unclear whether B cells are necessary for disease induction, autoantibody production, or disease progression. To address the role of B cells in a murine model of spontaneous autoimmune thyroiditis (SAT), B cells were depleted from adult NOD.H-2h4 mice using anti-mouse CD20 mAb. Anti-CD20 depleted most B cells in peripheral blood and cervical lymph nodes and 50-80% of splenic B cells. Flow cytometry analysis showed that marginal zone B cells in the spleen were relatively resistant to depletion by anti-CD20, whereas most follicular and transitional (T2) B cells were depleted after anti-CD20 treatment. When anti-CD20 was administered before development of SAT, development of SAT and anti-mouse thyroglobulin autoantibody responses were reduced. Anti-CD20 also reduced SAT severity and inhibited further increases in anti-mouse thyroglobulin autoantibodies when administered to mice that already had autoantibodies and thyroid inflammation. The results suggest that B cells are necessary for initiation as well as progression or maintenance of SAT in NOD.H-2h4 mice.

Intracellular adhesion molecule-1 up-regulation on thyrocytes by iodine of non-obese diabetic.H2(h4) mice is reactive oxygen species-dependent

Intracellular adhesion molecule-1 (ICAM-1) expression on the thyroid follicular cells of non-obese diabetic (NOD).H2(h4) mice is enhanced by iodide treatment, which correlates with autoimmune thyroid disease in genetically susceptible NOD.H2(h4) mice. The current study examines the mechanism of iodine-enhanced up-regulation of ICAM-1 on the surface of thyroid cells. We hypothesized that the up-regulation of ICAM-1 is due to a transient increase in production of reactive oxygen species (ROS). ROS may initiate signalling of the ICAM-1 gene promoter, enhancing up-regulated ICAM-1 protein on the cell surface. Single-cell suspensions of thyroid follicular cells from thyroiditis-susceptible NOD.H2(h4) or non-susceptible BALB/c mice were treated in vitro with sodium iodide. Extracellular and intracellular ROS were assessed by luminol-derived chemiluminescence and flow cytometry assays respectively. Our results demonstrate that thyroid follicular cells of NOD.H2(h4) generate higher levels of ROS compared with cells from non-susceptible strains of mice. Expression of a subunit protein of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, p67(phox), was analysed by Western blot immunoassay. A constitutive expression of the p67(phox) subunit protein was observed in NOD.H2(h4) mice prior to iodine treatment. No such expression was found in BALB/c mice. Treatment of NOD.H2(h4) thyroid cells with diphenyleneiodium, an inhibitor of NADPH oxidase, reduced generation of ROS and of ICAM-1 protein expression. Thus, thyrocytes from NOD.H2(h4) mice produce enhanced levels of ROS that may be mediated by NADPH oxidase. Consequently, in NOD.H2(h4) mice the ROS-induced signal for ICAM-1 up-regulation may contribute to mononuclear cellular infiltration of the thyroid gland and the progression of autoimmune thyroid disease.

CD4+CD25+ naturally occurring regulatory T cells and not lymphopenia play a role in the pathogenesis of iodide-induced autoimmune thyroiditis in NOD-H2h4 mice

NOD-H2(h4) mice, which express I-A(k) on the NOD background, spontaneously develop autoimmune thyroiditis, a model of Hashimoto thyroiditis in humans, by adding iodide in the drinking water. Parental NOD mice have previously been shown to have intrinsic numerical abnormalities in peripheral lymphocytes and lymphocyte subpopulations such as CD4(+)CD25(+) naturally occurring regulatory T cells (Treg). Therefore we first investigated whether the similar abnormalities exist in NOD-H2(h4) mice. We observed that, compared with other non-autoimmune disease prone BALB/c and C57BL/6 mice, NOD-H2(h4) mice have lower numbers of splenocytes, CD3(+)T, CD4(+)T and CD8(+)T cells but the ratios of Treg to CD4(+)T cells were comparable. Increasing the numbers of peripheral lymphocytes by Complete Freund's Adjuvant immunization or splenocyte transfer did not affect development of thyroiditis, indicating that lymphopenia does not play a critical role in the pathogenesis of thyroiditis. We next examined the significance of Treg by depleting this lymphocyte subset with anti-CD25 antibody. Treg depletion, performed 4days before the administration of NaI water for 8 weeks, significantly exacerbated thyroiditis (p<0.01). Anti-thyroglobulin antibody titers also increased by Treg depletion (p<0.01) without changing the IgG2b to IgG1 ratios. In addition, expression levels of mRNA for IFN-gamma and IL-4 were enhanced in parallel. However, T(4) levels were similar between antibody-treated and untreated groups. Additional anti-CD25 administration at 3 weekly intervals did not influence these results. These data, together with previous studies on other mouse models of inducible thyroiditis and Graves' disease, indicate the role played by Treg in keeping anti-thyroid autoimmune reaction in check in experimental autoimmune thyroid diseases.

Herbal medicine Gamgungtang down-regulates autoimmunity through induction of TH2 cytokine production by lymphocytes in experimental thyroiditis model

The crude herbal formulation, Gamgungtang (GGT), has been shown to protect animals against a wide range of spontaneously developing or induced autoimmune diseases. We have previously reported that GGT shows marked down-regulation of several experimental autoimmune diseases. Although very effective at preventing thyroid infiltrates in mice immunized with mouse deglycosylated thyroglobulin and complete Freund's adjuvant and in spontaneous models of thyroiditis, it completely failed to modify experimental autoimmune thyroiditis (EAT) induced in mice immunized with mouse thyroglobulin and lipopolysaccharide. In this study, in an effort to elucidate the mechanisms by which GGT suppresses EAT, and autoimmunity in general, we investigated the in vivo effects of this drug on the Th1/Th2 lymphocyte balance, which is important for the induction or inhibition of autoreactivity. Naive SJL/J mice were treated orally for 5 days with GGT (80 mg/(kg day)). Spleen cells were obtained at various time points during the treatment period and were stimulated in vitro with concanavalin A. Interleukins IL-4, IL-10 and IL-12, transforming growth factor-beta (TGF-beta) and interferon-gamma (IFN-gamma) cytokine production was evaluated at the protein levels of the cytokines in the medium and mRNA expressions. A significant upregulation of IL-4, IL-10 and TGF-beta was observed following treatment with GGT, which peaked at day 5 (IL-10) or day 10 (IL-4). On the other hand, IL-12 and IFN-gamma production were either unchanged or decreased. It seems therefore that GGT induces in vivo a shift towards Th2 lymphocytes which may be one of the mechanisms of down-regulation of the autoimmune reactivity in EAT. Our observations indicate that down-regulation of TH1 cytokines (especially IL-12) and enhancement of Th2 cytokine production may play an important role in the control of T-cell-mediated autoimmunity. These data may contribute to the design of new immunomodulating treatments for a group of autoimmune diseases.

Effect of the traditional Korean immunomodulating formulation, Gamguntang (GGT), on experimental thyroiditis model

The crude herbal formulation, Gamgungtang (GGT), is an immunomodulator showing marked down-regulation of several experimental autoimmune diseases. In this study, its effect on different experimental models of thyroid disease was investigated. Although very effective at preventing thyroid infiltrates in mice immunized with mouse deglycosylated thyroglobulin and complete Freund's adjuvant and in spontaneous models of thyroiditis, it completely failed to modify experimental autoimmune thyroiditis (EAT) induced in mice immunized with mouse thyroglobulin and lipopolysaccharide. There was no significant shift in the observed isotypes of anti-mouse thyroglobulin antibodies and only anti-mouse thyroglobulin antibodies in the spontaneous model were completely down-modulated by the GGT. One surprising fact to emerge was that GGT-treated donor mice, although protected from thyroid lesions themselves, were still able to transfer EAT showing that they must have been effectively primed while being treated with GGT. It is possible that the drug down modulated EAT by interfering with the trafficking of primed effector cells.