Graves'disease (GD) is a syndrome caused by as yet unidentified genetic and environmental factors where the thyroid becomes overactive because antibodies (TSI) directed against the thyrotropin receptor (TSHR) drive excess hormone production. GD is also associated with the inflammation, accumulation of hyaluronan (HA), and remodeling of orbital connective tissue. This process is known as thyroid-associated ophthalmopathy (TAO) for which no effective treatment currently exists. A major impediment to our understanding of TAO is the absence of a pre-clinical animal model. We have discovered previously that orbital fibroblasts from patients with TAO exhibit a unique inflammatory phenotype and over-express the insulin-like growth factor-1 receptor (IGF-1R). IGF-1R-activating antibodies (GD-IgGs) are found in virtually all patients with GD. When they bind to this receptor, T cell chemoattractants and HA are synthesized by TAO fibroblasts. We hypothesize that these events underlie lymphocyte infiltration and expansion of the orbital tissue. We have now discovered that GD is also associated with an increased frequency of IGF-1R+ T and B cells and this phenotype conveys a proliferative and survival advantage. Monozygotic (MZ) twins discordant for GD are also discordant for the IGF- 1R+ lymphocyte skew, suggesting an environmental cause. We have also now discovered that patients with GD have increased numbers of circulating CD34+ fibroblast precursors called fibrocytes. Moreover we find fibrocytes infiltrating the TAO orbit and expressing high levels of TSHR and IGF-1R. In orbital fibroblasts and thyroid epithelium, TSHR and IGF-1R form a physical complex and IGF-1R mediates aspects of TSHR signaling. We have succeeded in cloning an adenovirus encoding an IGF-1R1-GFP fusion protein. When female BALB/c mice are immunized with it, they manifest orbital inflammation and produce GD-IgG. We have also implanted TAO fat into SCID NOD3-/- mice and shown that TAO fibrocytes home to that tissue. We hypothesize that IGF-1R represents the second critical auto-antigen in GD and is necessary with TSHR to generate authentic disease. We now propose studies to test our central hypothesis.
Specific aim 1) To characterize profiles of CD4+ IGF-1R+ T cells, CD19+IGF-1R+ B cells, and fibrocytes from patients with GD, determine whether they change longitudinally or predict development of TAO, determine whether IGF-1R+ B cells selectively produce pathogenic Abs such as TSI and GD-IgG, and examine additional MZ twins discordant for clinical GD.
Specific aim 2) To characterize the interaction between IGF-1R and TSHR by cloning IGF-1R2 mutants and performing yeast two-hybrid analysis.
Specific aim 3) To continue exploiting two mouse models of GD created by 1) implanting orbital fat into SCID NOD3-/- mice and 2) double-immunizing mice with adenoviruses encoding IGF-1R and TSHR. We believe that important insights into disease pathogenesis and identification of novel therapeutic targets will emerge from these studies.

Public Health Relevance

Thyroid-associated ophthalmopathy (TAO) is the sight-threatening orbital component of Graves'disease, a syndrome where the thyroid gland becomes over-active. There are currently no effective therapies for TAO because we lack an experimental animal model to study disease mechanisms and test therapies. In this proposal, we identify abnormalities in human immune system that underlie development of TAO, and apply these insights to animal models in which treatments can be developed.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK063121-08
Application #
8134752
Study Section
Integrative and Clinical Endocrinology and Reproduction Study Section (ICER)
Program Officer
Abraham, Kristin M
Project Start
2002-12-01
Project End
2013-08-31
Budget Start
2011-09-01
Budget End
2012-08-31
Support Year
8
Fiscal Year
2011
Total Cost
$373,222
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Smith, Terry J (2018) Challenges in Orphan Drug Development: Identification of Effective Therapy for Thyroid-Associated Ophthalmopathy. Annu Rev Pharmacol Toxicol :
Smith, Terry J; Kahaly, George J; Ezra, Daniel G et al. (2017) Teprotumumab for Thyroid-Associated Ophthalmopathy. N Engl J Med 376:1748-1761
Chen, Hong; Shan, Shannon J C; Mester, Tünde et al. (2015) TSH-Mediated TNF? Production in Human Fibrocytes Is Inhibited by Teprotumumab, an IGF-1R Antagonist. PLoS One 10:e0130322
Lee, Brian J; Atkins, Stephen; Ginter, Anna et al. (2015) Increased CD40+ Fibrocytes in Patients With Idiopathic Orbital Inflammation. Ophthal Plast Reconstr Surg 31:202-6
Stein, Joshua D; Childers, David; Gupta, Shivani et al. (2015) Risk factors for developing thyroid-associated ophthalmopathy among individuals with Graves disease. JAMA Ophthalmol 133:290-6
Kristensen, Birte; Hegedüs, Laszlo; Lundy, Steven K et al. (2015) Characterization of Regulatory B Cells in Graves' Disease and Hashimoto's Thyroiditis. PLoS One 10:e0127949
Kristensen, B; Hegedüs, L; Madsen, H O et al. (2015) Altered balance between self-reactive T helper (Th)17 cells and Th10 cells and between full-length forkhead box protein 3 (FoxP3) and FoxP3 splice variants in Hashimoto's thyroiditis. Clin Exp Immunol 180:58-69
Douglas, Raymond S; Mester, Tünde; Ginter, Anna et al. (2014) Thyrotropin receptor and CD40 mediate interleukin-8 expression in fibrocytes: implications for thyroid-associated ophthalmopathy (an American Ophthalmological Society thesis). Trans Am Ophthalmol Soc 112:26-37
McCoy, Allison N; Kim, Denise S; Gillespie, Erin F et al. (2014) Rituximab (Rituxan) therapy for severe thyroid-associated ophthalmopathy diminishes IGF-1R(+) T cells. J Clin Endocrinol Metab 99:E1294-9
Wang, Yao; Smith, Terry J (2014) Current concepts in the molecular pathogenesis of thyroid-associated ophthalmopathy. Invest Ophthalmol Vis Sci 55:1735-48

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