Iodine and Thyroid Autoimmune Disease in Animal Models

Abstract

Thyroid autoimmune diseases are complex, polygenic afflictions the penetrance of which is heavily dependent on various environmental influences. In their pathogenesis, an afferent stage (enhanced autoantigen presentation), a central stage (excessive expansion and maturation of autoreactive T and B cells), and an efferent stage (effects of autoreactive T cells and B cells on their targets) can be discerned. At each stage, a plethora of inborn, endogenous or exogenous factors is able to elicit the abnormalities characteristic of that stage, thus opening the gateway to thyroid autoimmunity. Iodine is an important exogenous modulating factor of the process. In general, iodine deficiency attenuates, while iodine excess accelerates autoimmune thyroiditis in autoimmune prone individuals. In nonautoimmune prone individuals, the effects of iodine are different. Here iodine deficiency precipitates a mild (physiological) form of thyroid autoimmune reactivity. Iodine excess stimulates thymus development. Iodine probably exerts these effects via interference in the various stages of the autoimmune process. In the afferent and efferent stage, iodine-induced alterations in thyrocyte metabolism and even necrosis most likely play a role. By contrast, in the central phase, iodine has direct effects on thymus development, the development and function of various immune cells (T cells, B cells macrophages and dendritic cells) and the antigenicity of thyroglobulin.

Iodine content of thyroglobulin in NOD.H2h4 mice developing iodine-accelerated autoimmune thyroiditis

“…Furthermore, we could not detect proliferative cell responses of NOD.H2 h4 spleen cells to A k -restricted T cell epitopes of Tg most of which are known to induce thyroiditis either as iodinated 17,20 or non-iodinated peptides. 17,21 Our inability to demonstrate formation of I-Tg in this ISAT model is seemingly at odds with the results of numerous EAT studies 6,11,19,31,32 attributing a critical role for Tg iodination in the disease process. In several studies, iodine-depleted Tg does not activate thyroiditogenic T cells but, by raising the Tg iodine content to normal levels in vitro, the immunopathogenicity of the molecule is re-established.…”

Risk factors and pathogenesis of Hashimoto’s thyroiditis

“…Jodo stygius susilpnina linkusiems į autoimunitetą žmonėms autoimuninio tiroidito pasireiškimą. Ir priešingai, jodo perteklius pagreitina tokiems žmonėms Hašimoto tiroidito pasireiškimą, taip pat pablogina ligos procesą, nes dėl padidėjusio tiroglobulino jodavimo palengvėja paslėpto, patogeninio peptido selektyvus apdorojimas ir pristatymas T ląstelei (39).…”

Effect of processing on iodine content of some selected plants food

“…In very severe iodine deficiency, stunted growth and mental retardation can occur in children (Laurberg, 2004). A number of studies have reported adverse effects on hearing capacity, motor and cognitive function in children associated with moderate and severe iodine deficiency (Venturi et al, 2000;Ruwhof and Drexhage, 2001;Mann and Aitken, 2003).…”