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Interleukin 6 inhibits human thyroid peroxidase gene expression
T Tominaga1, S Yamashita, Y Nagayama
1First Department of Internal Medicine, Nagasaki University School of Medicine, Japan.
Acta Endocrinologica
|March 1, 1991
Summary
Interleukin 6 (IL-6) inhibits thyroid hormone secretion and thyroid peroxidase gene expression in human thyrocytes, similar to other cytokines. This study clarifies IL-6's inhibitory role in thyroid function.
Area of Science:
- Endocrinology
- Immunology
- Molecular Biology
Background:
- Cytokines like interleukin 1 (IL-1) and interferon-gamma (IFN-γ) are known to inhibit thyroid hormone secretion and gene expression.
- Interleukin 6 (IL-6) is increasingly recognized for its role in immunoendocrine interactions, with intrathyroidal IL-6 production reported.
Purpose of the Study:
- To investigate the regulatory effects of IL-6 on thyroid hormone secretion and thyroid peroxidase (TPO) mRNA expression in human thyrocytes.
- To elucidate the functional role of IL-6 within the thyroid gland.
Main Methods:
- Human thyrocytes from Graves' thyroid tissues were incubated with thyroid-stimulating hormone (TSH) ± IL-6.
- TPO mRNA levels were assessed via hybridization, and T3 secretion was measured.
- The effect of IL-6 on DNA synthesis was also evaluated.
Main Results:
- TSH stimulated TPO mRNA expression; IL-6 inhibited TSH-induced TPO mRNA in a dose-dependent manner.
- IL-6 also inhibited cyclic adenosine monophosphate (cAMP)-induced TPO mRNA levels but did not affect basal TPO mRNA or gamma-actin mRNA.
- IL-6 significantly inhibited TSH-induced triiodothyronine (T3) secretion after 72 hours, without impacting DNA synthesis.
Conclusions:
- Interleukin 6 exerts an inhibitory influence on thyroid hormone secretion and TPO gene expression in human thyrocytes.
- These findings establish IL-6 as an additional inhibitory cytokine in the thyroid gland, alongside IL-1 and IFN-γ.