Microarray Analysis of Cytokine Activation of Apoptosis Pathways in the Thyroid

Abstract

It has been suggested that Fas-mediated apoptosis plays an important role in the pathogenesis of autoimmune thyroid diseases. Our previous studies have demonstrated that normal primary thyroid epithelial cells are resistant to Fas-mediated apoptosis, but the resistance can be overcome by pretreatment with a combination of interferon-gamma (IFN-gamma) and IL-1beta. To understand the molecular mechanism responsible for the IFN-gamma/IL-1beta effects, we profiled changes in the transcription induced by these two cytokines in normal human thyroid cells, using cDNA microarrays. We found that IFN-gamma/IL-1beta showed a significant increase in apoptosis-related genes such as inducible nitric oxide synthase (iNOS), receptor-interacting protein 2 (RIP2), and caspases 10. These increases were confirmed by other methods, including real-time PCR and Western blot. Furthermore, the sensitization of primary thyroid epithelial cells to Fas-mediated apoptosis by IFN-gamma/IL-1beta was significantly blocked by a general caspase inhibitor, z-VAD, or by the combination of two specific individual caspase inhibitors. In addition, our results showed that IFN-gamma/IL-1beta enhance p38 MAPK phosphorylation and that SB 203580, a p38 MAPK inhibitor, can inhibit IFN-gamma/IL-1beta-induced p38 MAPK phosphorylation. SB 203580 also significantly prevented cytokine-induced iNOS expression and caspase activation and thus blocked Fas-mediated apoptosis of thyroid cells sensitized by IFN-gamma/IL-1beta. In conclusion, our data suggest that both p38 MAPK and iNOS are involved in IFN-gamma/IL-1beta-induced sensitization of the thyroid cells to Fas-mediated apoptosis via the activation of caspases 3, 7, and 10 and that this pathway may be further activated by BID. This hints that inflammatory cytokines regulate death-receptor-mediated apoptosis at multiple points in the process.

TRAIL and DR5 Promote Thyroid Follicular Cell Apoptosis in Iodine Excess-Induced Experimental Autoimmune Thyroiditis in NOD Mice

“…Some studies suggested that TRAIL suppresses the development of autoimmune thyroiditis [32,33]; others considered that apoptosis induced by TRAIL and DR5 can promote the development of autoimmune thyroiditis [34][35][36]. In our study, we found that TRAIL and DR5 promoted follicular cells apoptosis, thus mediating thyroid destruction in experimental autoimmune thyroiditis (EAT), and activated immune cells play an important role during the inflammatory response.…”

“…Activated immune cells may be responsible for inducing thyroid cell destruction during the inflammatory response by producing inflammatory cytokines, and increasing the local production of inflammatory cytokines in the thyroid microenviroment plays a critical role in facilitating thyrocyte apoptosis [34][35][36]. Potential models for the involvement of TRAIL in autoimmune destructive thyroiditis include the following: (a) cytokines produced by activated immune cells induce thyroid cell susceptibility to TRAIL, and immune cells expressing TRAIL can subsequently kill thyroid cells.…”

Changes of B and T lymphocytes and selected apopotosis markers in Hashimoto's thyroiditis

“…Thyrocytes expressing Bcl-2 can be more resistant to Fas-mediated cell death 1 4 16. Fas-mediated apoptosis may include the activation of a variety of caspases such as caspases 1, 2, 3, 7, 8, 9, 10 3 10 18. The Fas pathway is the most important mechanism of T lymphocyte mediated apoptosis.…”

“…Both proliferation and apoptosis are involved in the pathogenesis of Hashimoto disease. The latter can be activated by a wide variety of external or internal stimuli 1 3…”

Overexpression of BID in thyroids of transgenic mice increases sensitivity to iodine-induced autoimmune thyroiditis

“…Although the pathogenesis of autoimmune thyroiditis is not entirely clear, studies have demonstrated that increasing the local production of inflammatory cytokines in the thyroid microenvironment plays a critical role in facilitating apoptosis in thyrocytes, leading to autoimmune thyroiditis [1-3]. Among various inflammatory cytokines, IFN-γ, TNF-α and IL-1β appear to be critical since the combination of two such cytokines can significantly facilitate the development of experimental autoimmune thyroiditis (EAT) in mice [1,3,4], a well-recognized animal model of autoimmune thyroiditis.…”