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.H2h4 genetic background predisposes to enhanced iodine organification in thyroglobulin (Tg), a target autoantigen in ISAT.


METHODS
To avoid issues associated with an ongoing anti-Tg antibody response, we assessed Tg iodination levels in iodine-fed, B-cell deficient NOD.H2h4 mice. Additionally, we tested whether humoral or cellular immune responses of iodine-fed NOD.H2h4 mice are preferentially directed to Tg with increased iodine content (I-Tg) or known pathogenic Tg peptides that contained iodine.


RESULTS
The iodine content of Tg was not significantly different between control (9.0 +/- 2.7 I atoms per monomer) and iodine-fed mice (10.9 +/- 0.3 I atoms per monomer). Furthermore, in iodine-fed NOD.H2h4 mice developing ISAT, strong but equivalent serum IgG responses were detected to both Tg or I-Tg, whereas their lymphoid cells were stimulated weakly but equally well by Tg or I-Tg in vitro and did not show reactivity against a panel of five pathogenic Tg peptides that contained iodine.


CONCLUSIONS
The results suggest that development of ISAT in NOD.H2h4 mice is not associated with enhanced iodine organification or differential B- or T-cell responses to iodinated determinants in Tg.
Kolypetri
Panayota
P
Division of Endocrinology, Faculty of Medicine, Memorial University of Newfoundland, St. John's NL, Canada.
Noel
Natasha A
NA
Carayanniotis
Karen A
KA
Carayanniotis
George
G
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005260:Female; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007074:Immunoglobulin G / Q000097:blood; D007455:Iodine / Q000097:blood* / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016688:Mice, Inbred NOD; D012974:Sodium Iodide; D013601:T-Lymphocytes / Q000276:immunology; D013954:Thyroglobulin / Q000097:blood* / Q000276:immunology; D013967:Thyroiditis, Autoimmune / Q000097:blood* / Q000139:chemically induced / Q000235:genetics / Q000276:immunology
D007074:Immunoglobulin G; D013954:Thyroglobulin; D007455:Iodine; D012974:Sodium Iodide