Enhanced iodine supplementation alters the immune process in a transgenic mouse model for autoimmune thyroiditis.
BACKGROUND
The impact of excessive iodine intake on the development of autoimmune thyroiditis (AIT) is still under debate. Transgenic, antibody-devoid TAZ10 mice spontaneously develop AIT due to autoreactive thyroperoxidase-specific T cells. In this model, development of AIT is determined by a T cell infiltration of the thyroid gland leading to an elevation of serum thyrotropin (TSH) levels and significant weight gain. In the present study we investigated the impact of moderate and high iodine supplementation on the course of disease in these mice, which are immunologically prone to AIT.


METHODS
In addition to normal nutrition, mice were supplemented for 20 weeks with 2.5 μg versus 5 μg iodine per milliliter drinking water, which corresponds to a human daily iodine supplementation of 150 μg, 315 μg, and 615 μg iodine. AIT-defining parameters (weight gain, elevation of serum TSH levels, cellular infiltration of the thyroid) and immunologic effects were analyzed.


RESULTS
No significant differences were displayed when comparing weight and serum TSH levels in the iodine-supplemented versus control groups. Increased thyroid infiltrates with CD8⁺ T cells were detected by fluorescein-activated cell sorter (FACS) and immunofluorescence staining in mice supplemented with elevated iodine amounts (315 μg and 615 μg iodine per day, respectively). Immunologic monitoring revealed selective changes in immune cell frequencies (CD8⁺ and regulatory T cells, natural killer [NK] cells) and cytokine production (interferon-γ, interleukin-1α, and interleukin-17), however, without affecting the overall immune balance.


CONCLUSIONS
Our results demonstrate that elevated iodine supplementation has no physical impact on the course of disease in transgenic, antibody-devoid TAZ10 mice, which are immunologically prone to AIT.
1 Division for Specific Endocrinology, University of Duesseldorf , Duesseldorf, Germany .
Margret
M
Ehlers
Annette
A
Thiel
Claudia
C
Papewalis
Andreas
A
Domröse
Wiebke
W
Stenzel
Christian
C
Bernecker
Matthias
M
Haase
Stephanie
S
Allelein
Sven
S
Schinner
Holger S
HS
Willenberg
Joachim
J
Feldkamp
Matthias
M
Schott
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016207:Cytokines / Q000097:blood / Q000378:metabolism; D019587:Dietary Supplements; D005260:Female; D007111:Immunity, Cellular; D007155:Immunologic Factors / Q000008:administration & dosage / Q000627:therapeutic use*; D007455:Iodine / Q000008:administration & dosage / Q000627:therapeutic use*; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D008822:Mice, Transgenic; D009929:Organ Size; D013047:Specific Pathogen-Free Organisms; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D018417:Th1 Cells / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D013961:Thyroid Gland / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D013967:Thyroiditis, Autoimmune / Q000178:diet therapy* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D013972:Thyrotropin / Q000097:blood; D015430:Weight Gain
D016207:Cytokines; D007155:Immunologic Factors; D013972:Thyrotropin; D007455:Iodine