DNA-histone complexes as ligands amplify cell penetration and nuclear targeting of anti-DNA antibodies via energy-independent mechanisms.

We have generated three monoclonal cell-penetrating antibodies (CPAbs) from a non-immunized lupus-prone (NZB × NZW)F1 mouse that exhibited high anti-DNA serum titres. These CPAbs are polyreactive because they bind to DNA and other cellular components, and localize mainly in the nucleus of HeLa cells, albeit with a distinct nuclear labelling profile. Herein, we have examined whether DNA-histone complexes (DHC) binding to CPAbs, before cell entry, could modify the cell penetration of CPAbs or their nuclear staining properties.

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.

Genes and Environment as Predisposing Factors in Autoimmunity: Acceleration of Spontaneous Thyroiditis by Dietary Iodide in NOD.H2 Mice.

In the field of autoimmune thyroiditis, NOD.H2 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.

The thyroxine-containing thyroglobulin peptide (aa 2549-2560) is a target epitope in iodide-accelerated spontaneous autoimmune thyroiditis.

Enhanced iodide ingestion is known to accelerate the incidence and severity of spontaneous autoimmune thyroiditis [iodide-accelerated spontaneous autoimmune thyroiditis (ISAT)] in NOD.H2(h4) mice. CD4+ cells are required for the development and maintenance of ISAT, but their target epitopes remain unknown.

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.

Identification of pathogenic T cell epitopes near cathepsin cleavage sites in thyroglobulin.

Experimental autoimmune thyroiditis, induced in mice after challenge with thyroglobulin (Tg), is known to be under the genetic control of the H2A(k) locus. Because cathepsins are known to influence proteolytic processing of Tg in vivo, we examined in this study whether putative H2A(k)-binding Tg epitopes, located near cathepsin cleavage sites within mouse Tg, have immunopathogenic properties. Cathepsin L, B, and D cleavage sites in mouse Tg were predicted based on homology with known cathepsin cleavage sites in rabbit Tg.

Fine epitope mapping within the pathogenic thyroglobulin peptide 2340-2359: minimal epitopes retaining antigenicity across various MHC haplotypes are not necessarily immunogenic.

We have previously reported that the 20-mer peptide p2340 (amino acids 2340-2359), of human thyroglobulin (Tg) has the unique feature that it causes experimental autoimmune thyroiditis (EAT) in mouse strains bearing high-responder (HR) or low-responder (LR) MHC haplotypes in Tg-induced EAT. In this study, we have employed fine epitope mapping to examine whether this property of p2340 is the result of recognition of distinct or shared minimal T-cell epitopes in the context of HR or LR MHC class II molecules. Use of overlapping peptides showed that a core minimal 9-mer epitope (LTWVQTHIR, amino acids 2344-2352) was recognized by p2340-primed T cells from both HR (H2(k,s) ) and LR (H2(b,d) ) strains, whereas a second 9-mer epitope (HIRGFGGDP, amino acids 2350-2358) was antigenic only in H2(s) hosts.

Molecular parameters linking thyroglobulin iodination with autoimmune thyroiditis.

Increased iodide intake has been linked to the development of hypothyroidism and/or autoimmune thyroiditis in humans and animals, but the mechanisms involved remain poorly understood. Increased ingestion of iodide is likely to have pleiotropic effects on either metabolic or immunological processes. Within the latter domain, recent interest has been focused on two areas: a) the role of iodinated peptides in thyroglobulin (Tg)--the molecular site of biosynthesis and storage of iodotyrosines and iodothyronines--in triggering an autoimmune cascade, and b) the role of iodine-induced apoptosis/necrosis of thyrocytes in the disease process.

Iodine content of thyroglobulin in Nod.H2h4 mice developing iodine-accelerated autoimmune thyroiditis.

Objective: In NOD.H2h4 mice, high dietary iodine intake has been known to cause iodine-accelerated spontaneous autoimmune thyroiditis (ISAT) via an unknown mechanism. The aim of the study was to examine whether the NOD.

Recognition of thyroglobulin by T cells: the role of iodine.

Among known autoantigens, thyroglobulin (Tg) is unique in its capacity to store iodine, an element provided in our daily diet. Evolutionary pressure has sculpted Tg into a large molecular scaffolding to allow organification of iodide and its incorporation into thyroid hormones. The increase in molecular size and the posttranslational modification by iodine had to exact immunological consequences.

Variable influences of iodine on the T-cell recognition of a single thyroglobulin epitope.

We have previously shown that iodotyrosyl formation within certain innocuous thyroglobulin (Tg) peptides confers on them immunopathogenic properties. In this report, we generated a panel of T-cell hybridoma clones specific for the immunogenic 16 mer Tg peptide p179 (amino acids 179-94) or its iodinated analogue (I-p179), with a view to examining the effects of a single iodine atom at the Y192 amino acid residue on T-cell recognition. We found that the peptide p179 was subdominant, and its binding to both A(k) and E(k) molecules was not significantly influenced by iodine.

Induction of goitrous hypothyroidism by dietary iodide in SJL mice.

Prolonged intake of large amounts of iodide has been reported to increase the incidence of goiter and/or hypothyroidism in humans as well as animals prone to spontaneous autoimmune thyroiditis. In the current study, we investigated the role of dietary iodide on the development of hypothyroidism, as well as thyroiditis, in strains of mice that do not develop spontaneous autoimmune thyroiditis. Intake of 0.

Modifying effects of iodine on the immunogenicity of thyroglobulin peptides.

We have previously shown that iodotyrosyl formation within thyroglobulin (Tg) generates neoantigenic determinants that are immunopathogenic. In the current study, we have examined iodination effects on three tyrosyl-containing Tg peptides that are immunogenic in their non-iodinated form. We found that iodotyrosyl formation can enhance (p179, a.

Iodination of tyrosyls in thyroglobulin generates neoantigenic determinants that cause thyroiditis.

Thyroglobulin (Tg) is unique in its ability to incorporate and store available iodine in the form of iodotyrosyl residues. Iodination of Tg has been known to increase its immunopathogenicity in experimental animals, presumably through the formation of iodine-containing neoantigenic determinants that can elicit an autoimmune response, but defined pathogenic Tg peptides carrying iodotyrosyls have not yet been identified. We report in this study that a systematic, algorithm-based search of mouse Tg has delineated three iodotyrosyl-containing peptides that activate autoreactive T cells and cause experimental autoimmune thyroiditis in normal CBA/J mice.

Antigen processing by autoreactive B cells promotes determinant spreading.

Acute primary immune responses tend to focus on few immunodominant determinants using a very limited number of T cell clones for expansion, whereas chronic inflammatory responses generally recruit a large number of different T cell clones to attack a broader range of determinants of the invading pathogens or the inflamed tissues. In T cell-mediated organ-specific autoimmune disease, a transition from the acute to the chronic phase contributes to pathogenesis, and the broadening process is called determinant spreading. The cellular components catalyzing the spreading reaction are not identified.

Tolerogenic semimature dendritic cells suppress experimental autoimmune thyroiditis by activation of thyroglobulin-specific CD4+CD25+ T cells.

Ex vivo treatment of bone marrow-derived dendritic cells (DCs) with TNF-alpha has been previously shown to induce partial maturation of DCs that are able to suppress autoimmunity. In this study, we demonstrate that i.v.

Detection of thyroglobulin mRNA as truncated isoform(s) in mouse thymus.

Recent studies employing reverse transription-polymerase chain reaction (RT-PCR) have demonstrated the intrathymic presence of mRNA for various autoantigens, including thyroglobulin (Tg). Deliberations on the mechanisms of central tolerance usually assume that this approach detects intact mRNA transcripts that can be translated to express the whole autoantigen in the thymus. In the present study, we tested this assumption using mRNA transcripts of mouse Tg which encode at least 13 pathogenic peptides, scattered over a large (8.

Thyroxine-binding antibodies inhibit T cell recognition of a pathogenic thyroglobulin epitope.

Thyroid hormone-binding (THB) Abs are frequently detected in autoimmune thyroid disorders but it is unknown whether they can exert immunoregulatory effects. We report that a THB mAb recognizing the 5' iodine atom of the outer phenolic ring of thyroxine (T4) can block T cell recognition of the pathogenic thyroglobulin (Tg) peptide (2549-2560) that contains T4 at aa position 2553 (T4(2553)). Following peptide binding to the MHC groove, the THB mAb inhibited activation of the A(k)-restricted, T4(2553)-specific, mouse T cell hybridoma clone 3.

Experimental autoimmune thyroiditis (EAT) induced by the thyroglobulin peptide (2596-2608): influence of H-2 and non H-2 genes.

We have previously identified five thyroglobulin (Tg) peptides with Ak-binding motifs that induce experimental autoimmune thyroiditis (EAT) in CBA/J (H-2k) mice. In this study, we have examined whether H-2 or non H-2 genes can influence the immunopathogenicity of peptide p2596 (a.a.

The cryptic self in thyroid autoimmunity: the paradigm of thyroglobulin.

Recent studies have increased the number of known thyroiditogenic sites in thyroglobulin (Tg) to thirteen. These sites contain T-cell epitopes and are scattered throughout Tg, with nine of them localized toward the carboxyl terminal third of the molecule. So far, no pathogenic determinant has been found to be dominant, i.

Induction of murine thyroiditis by a non dominant E(k)-restricted peptide of human thyroglobulin.

We have previously shown that the human thyroglobulin (hTg) 20-mer peptide p2340 (aa 2340-2359) contains an epitope recognized by Tg-reactive B cells in patients with Graves' disease. The presence of several Ek-binding motifs within p2340 prompted us to examine whether this peptide can stimulate a T-cell response and elicit experimental autoimmune thyroiditis (EAT) in AKR/J (H-2k) mice. The peptide was found to be immunogenic at the T-cell level since it induced specific proliferative responses as well as interleukin-2 and interferon-gamma secretion in secondary cultures of peptide-primed lymph node cells (LNC).

Contrasting activities of thyrotropin receptor antibodies in experimental models of Graves' disease induced by injection of transfected fibroblasts or deoxyribonucleic acid vaccination.

The development of experimental models of autoimmune hyperthyroid Graves' disease has proved a difficult challenge, but recently two novel methods have led to their successful development in mice. We describe our studies on replicating the adjuvant modified, human TSH receptor (TSHR) and major histocompatibility complex class II transfected fibroblast injection system, and the plasmid DNA vaccination method as models resembling the human disorder. The fibroblast injection model in female AKR/N (H-2k) mice led to 70% of the animals developing thyroid-stimulating antibodies and their thyroid glands showed large goiters with histological features of thyroid cell activation characteristic of Graves' glands.

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.

Enhanced iodination of thyroglobulin facilitates processing and presentation of a cryptic pathogenic peptide.

Increased iodine intake has been associated with the development of experimental autoimmune thyroiditis (EAT), but the biological basis for this association remains poorly understood. One hypothesis has been that enhanced incorporation of iodine in thyroglobulin (Tg) promotes the generation of pathogenic T cell determinants. In this study we sought to test this by using the pathogenic nondominant A(s)-binding Tg peptides p2495 and p2694 as model Ags.