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

Engineering Nanoplatforms for Theranostics of Atherosclerotic Plaques

Atherosclerotic plaque formation is considered the primary pathological mechanism underlying atherosclerotic cardiovascular diseases, leading to severe cardiovascular events such as stroke, acute coronary syndromes, and even sudden cardiac death. Early detection and timely intervention of plaques are challenging due to the lack of typical symptoms in the initial stages. Therefore, precise early detection and intervention play a crucial role in risk stratification of atherosclerotic plaques and achieving favorable post-interventional outcomes. The continuously advancing nanoplatforms have demonstrated numerous advantages including high signal-to-noise ratio, enhanced bioavailability, and specific targeting capabilities for imaging agents and therapeutic drugs, enabling effective visualization and management of atherosclerotic plaques. Motivated by these superior properties, various noninvasive imaging modalities for early recognition of plaques in the preliminary stage of atherosclerosis are comprehensively summarized. Additionally, several therapeutic strategies are proposed to enhance the efficacy of treating atherosclerotic plaques. Finally, existing challenges and promising prospects for accelerating clinical translation of nanoplatform-based molecular imaging and therapy for atherosclerotic plaques are discussed. In conclusion, this review provides an insightful perspective on the diagnosis and therapy of atherosclerotic plaques.

Antigen-specific immunotherapy to restore antigen-specific tolerance in Type 1 diabetes and Graves' disease

Type 1 diabetes and Graves' disease are chronic autoimmune conditions, characterized by a dysregulated immune response. In Type 1 diabetes, there is beta cell destruction and subsequent insulin deficiency whereas in Graves' disease, there is unregulated excessive thyroid hormone production. Both diseases result in significant psychosocial, physiological, and emotional burden. There are associated risks of diabetic ketoacidosis and hypoglycaemia in Type 1 diabetes and risks of thyrotoxicosis and orbitopathy in Graves' disease. Advances in the understanding of the immunopathogenesis and response to immunotherapy in Type 1 diabetes and Graves' disease have facilitated the introduction of targeted therapies to induce self-tolerance, and subsequently, the potential to induce long-term remission if effective. We explore current research surrounding the use of antigen-specific immunotherapies, with a focus on human studies, in Type 1 diabetes and Graves' disease including protein-based, peptide-based, dendritic-cell-based, and nanoparticle-based immunotherapies, including discussion of factors to be considered when translating immunotherapies to clinical practice.

A transgenic mouse that spontaneously develops pathogenic TSH receptor antibodies will facilitate study of antigen-specific immunotherapy for human Graves' disease

Graves' hyperthyroidism can be treated but not cured. Antigen-specific immunotherapy would accomplish this goal, for which purpose an animal model is an invaluable tool. Two types of animal models are available. First, pathogenic TSHR antibodies (TSHRAb) can be induced by injecting mice with fibroblasts co-expressing the human TSHR (hTSHR) and MHC class II, or in mammals using plasmid or adenovirus vectors encoding the hTSHR or its A-subunit. Second, a mouse model that spontaneously develops pathogenic TSHRAb resembling those in human disease was recently described. This outcome was accomplished by transgenic intrathyroidal expression of the hTSHR A-subunit in NOD.H2^h4 mice that are genetically predisposed to develop thyroiditis but, without the transgene, do not generate TSHRAb. Recently, novel approaches to antigen-specific immunotherapy have been tested, primarily in the induced model, by injecting TSHR A-subunit protein or cyclic TSHR peptides. T-cell tolerance has also been induced in "humanized" HLA-DR3 mice by injecting synthetic peptides predicted in silico to mimic naturally processed TSHR T-cell epitopes. Indeed, a phase 1 study based on the latter approach has been conducted in humans. In the spontaneous model (hTSHR/NOD.H2^h mice), injection of soluble or nanoparticle-bearing hTSHR A-subunits had the unwanted effect of exacerbating pathogenic TSHRAb levels. A promising avenue for tolerance induction, successful in other conditions and yet to be tested with the TSHR, involves encapsulating the antigen. In conclusion, these studies provide insight into the potential outcome of immunotherapeutic approaches and emphasize the importance of a spontaneous model to test future novel, antigen-specific immunotherapies for Graves' disease.

A Mouse Thyrotropin Receptor A-Subunit Transgene Expressed in Thyroiditis-Prone Mice May Provide Insight into Why Graves' Disease Only Occurs in Humans

Background: Graves' disease, caused by autoantibodies that activate the thyrotropin (TSH) receptor (TSHR), has only been reported in humans. Thyroiditis-prone NOD.H2^h4 mice develop autoantibodies to thyroglobulin (Tg) and thyroid peroxidase (TPO) but not to the TSHR. Evidence supports the importance of the shed TSHR A-subunit in the initiation and/or amplification of the autoimmune response to the holoreceptor. Cells expressing the gene for the isolated A-subunit secrete A-subunit protein, a surrogate for holoreceptor A-subunit shedding. NOD.H2^h4 mice with the human TSHR A-subunit targeted to the thyroid (a "self" antigen in such transgenic (Tgic) animals), unlike their wild-type (wt) siblings, spontaneously develop pathogenic TSHR antibodies to the human-TSH holoreceptor. These autoantibodies do not recognize the endogenous mouse-TSH holoreceptor and do not cause hyperthyroidism. Methods: We have now generated NOD.H2^h4 mice with the mouse-TSHR A-subunit transgene targeted to the thyroid. Tgic mice and wt littermates were compared for intrathyroidal expression of the mouse A-subunit. Sera from six-month-old mice were tested for the presence of autoantibodies to Tg and TPO as well as for pathogenic TSHR antibodies (TSH binding inhibition, bioassay for thyroid stimulating antibodies) and nonpathogenic TSHR antibodies (ELISA). Results: Expression of the mouse TSHR A-subunit transgene in the thyroid was confirmed by real-time polymerase chain reaction in the Tgics and had no effect on the spontaneous development of autoantibodies to Tg or TPO. However, unlike the same NOD.H2^h4 strain with the human-TSHR A-subunit target to the thyroid, mice expressing intrathyroidal mouse-TSHR A subunit failed to develop either pathogenic or nonpathogenic TSHR antibodies. The mouse TSHR A-subunit differs from the human TSHR A-subunit in terms of its amino acid sequence and has one less glycosylation site than the human TSHR A-subunit. Conclusions: Multiple genetic and environmental factors contribute to the pathogenesis of Graves' disease. The present study suggests that the TSHR A-subunit structure (possibly including posttranslational modification such as glycosylation) may explain, in part, why Graves' disease only develops in humans.