Interleukin-6 and transforming growth factor-beta regulate the expression of monocyte chemoattractant protein-1 and colony-stimulating factors in human thyroid follicular cells.

Monocytes and T-lymphocytes, both of which play a pivotal role in immune/inflammatory responses, can be attracted from the circulation into tissues by monocyte chemoattractant protein-1 (MCP-1), and monocytes can be further activated by colony-stimulating factors (CSFs), granulocyte/macrophage CSF (GM-CSF) or macrophage CSF (M-CSF). We examined whether either interleukin-6 (IL-6) or transforming growth factor-beta (TGF-beta), both of which are produced by thyroid follicular cells (TFC), can regulate the production of MCP-1 or CSF(s) in human TFC. IL-6, being effective only in the presence of soluble IL-6 receptor (sIL-6R), stimulated the expression of both MCP-1 and M-CSF, but was inhibitory on GM-CSF expression. On the other hand, TGF-beta stimulated the expression of both MCP-I and GM-CSF, but suppressed M-CSF expression. These results suggest a possible role of IL-6 or TGF-beta on the initiation and/or modulation of thyroid immune/inflammatory responses via MCP-1 production and differential production of GM-CSF or M-CSF by TFC.