Interleukin-1b (IL-1b) induces a crosstalk between cAMP and ceramide signaling pathways in thyroid epithelial cells

Interleukin-1 beta (IL-1b) is an important regulator of the thyroid cell function. This cytokine has been largely described to trigger an important biological signaling cascade: the sphingomyelin/ceramide pathway. In this report, we show that IL-1b induces the transient activation of a neutral sphingomyelinase in porcine thyroid cells. Moreover, IL-1b and ceramides are demonstrated to inhibit the TSH-induced cAMP production via the implication of aGi subunit of the adenylyl cyclase system. This crosstalk between cAMP and ceramide pathways constitutes a preponderant process in the TSH-controlled differentiation state of thyrocytes. All these results argue for the involvement of ceramides and IL-1b in the thyroid function regulation, leading to a cell dedifferentiated state.