Targeted expression of the human thyrotropin receptor A-subunit to the mouse thyroid: Insight into overcoming the lack of response to A-subunit adenovirus immunization

Pavel N. Pichurin, Chun Rong Chen, Gregorio D. Chazenbalk, Holly Aliesky, Nancy Pham, Basil Rapoport, Sandra M. McLachlan

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The thyrotropin receptor (TSHR), the major autoantigen in Graves' disease, is posttranslationally modified by intramolecular cleavage to form disulfide-linked A- and B-subunits. Because Graves' hyperthyroidism is preferentially induced in BALB/c mice using adenovirus encoding the free A-subunit rather than full-length human TSHR, the shed A-subunit appears to drive the disease-associated autoimmune response. To further investigate this phenomenon, we generated transgenic mice with the human A-subunit targeted to the thyroid. Founder transgenic mice had normal thyroid function and were backcrossed to BALB/c. The A-subunit mRNA expression was confirmed in thyroid tissue. Unlike wild-type littermates, transgenic mice immunized with low-dose A-subunit adenovirus failed to develop TSHR Abs, hyperthyroidism, or splenocyte responses to TSHR Ag. Conventional immunization with A-subunit protein and adjuvants induced TSHR Abs lacking the characteristics of human autoantibodies. Unresponsiveness was partially overcome using high-dose, full-length human TSHR adenovirus. Although of low titer, these induced Abs recognized the N terminus of the A-subunit, and splenocytes responded to A-subunit peptides. Therefore, "non-self" regions in the B-subunit did not contribute to inducing responses. Indeed, transgenic mice immunized with high-dose A-subunit adenovirus developed TSHR Abs with thyrotropin-binding inhibitory activity, although at lower titers than wild-type littermates, suggesting down-regulation in the transgenic mice. In conclusion, in mice expressing a human A-subunit transgene in the thyroid, non-self human B-subunit epitopes are not necessary to induce responses to the A-subunit. Our findings raise the possibility that autoimmunity to the TSHR in humans may not involve epitopes on a cross-reacting protein, but rather, strong adjuvant signals provided in bystander immune responses.

Original languageEnglish (US)
Pages (from-to)668-676
Number of pages9
JournalJournal of Immunology
Volume176
Issue number1
DOIs
StatePublished - Jan 1 2006
Externally publishedYes

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Thyrotropin Receptors
Adenoviridae
Immunization
Thyroid Gland
Transgenic Mice
Hyperthyroidism
Autoimmunity
Epitopes
Human Adenoviruses
Protein Subunits
Thyrotropin
Transgenes
Disulfides
Autoantibodies
Down-Regulation
Messenger RNA
Peptides
Proteins

ASJC Scopus subject areas

  • Immunology

Cite this

Targeted expression of the human thyrotropin receptor A-subunit to the mouse thyroid : Insight into overcoming the lack of response to A-subunit adenovirus immunization. / Pichurin, Pavel N.; Chen, Chun Rong; Chazenbalk, Gregorio D.; Aliesky, Holly; Pham, Nancy; Rapoport, Basil; McLachlan, Sandra M.

In: Journal of Immunology, Vol. 176, No. 1, 01.01.2006, p. 668-676.

Research output: Contribution to journalArticle

Pichurin, Pavel N. ; Chen, Chun Rong ; Chazenbalk, Gregorio D. ; Aliesky, Holly ; Pham, Nancy ; Rapoport, Basil ; McLachlan, Sandra M. / Targeted expression of the human thyrotropin receptor A-subunit to the mouse thyroid : Insight into overcoming the lack of response to A-subunit adenovirus immunization. In: Journal of Immunology. 2006 ; Vol. 176, No. 1. pp. 668-676.
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