Interferon-gamma sensitizes the human salivary gland cell line, HSG, to tumor necrosis factor-alpha induced activation of dual apoptotic pathways

Abstract

Activated immune cells secrete proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha), interferon-gamma (IFN-gamma) and Fas ligand (FasL) and these cytokines have been reported to induce apoptosis in numerous cell types. Apoptotic cell death has been associated with the progression of numerous autoimmune diseases. Proinflammatory cytokines are reportedly involved in apoptosis in the salivary glands of patients with Sjögren's syndrome (SS); an autoimmune disorder characterized by the destruction of salivary and lachrymal glands. In this study, we used the HSG cell line to determine if exposure to proinflammatory cytokines induces apoptosis in human salivary gland cells. In addition, we identified the mediators controlling the apoptotic process in response to TNF alpha and IFN gamma. TNF-alpha and IFN-gamma induced apoptosis in HSG cells and resulted in the activation of caspase 8 and the "death receptor" pathway. We further determined that caspase 9 and the "mitochondrial" pathway was also activated. Induction of the intrinsic and extrinsic pathways in HSG cells resulted in substrate cleavage by effector caspases, in particular the cleavage of alpha II spectrin, an autoantigen in Sjögren's syndrome. Our results suggest that HSG cells provide a model system to study processes regulating proinflammatory cytokine-induced apoptotic cell death.

Muscarinic Type 3 Receptor Induces Cytoprotective Signaling in Salivary Gland Cells through Epidermal Growth Factor Receptor Transactivation

“…To examine the cytoprotective effects of M3R in HSG cells, the muscarinic receptor agonist CCh was tested with respect to TNF␣/IFN␥-induced apoptosis, which was reported previously to activate apoptosis signaling in HSG cells (Kamachi et al, 2002;Kulkarni et al, 2006). Consistent with a previous report, the combined TNF␣/IFN␥ treatment reduced cell viability among HSG cells (Fig.…”

“…Therefore, in the following experiments, measurements of caspase 3/7 activity were performed 24 h after TNF␣/IFN␥ challenge. It should be noted that the protocol for incubating HSG cells for 24 h with proinflammatory cytokines to induce caspase activity was published previously (Kulkarni et al, 2006). …”

“…It was reported that levels of proinflammatory cytokines, such as tumor necrosis factor ␣ (TNF␣) and interferon ␥ (IFN␥), are elevated in the affected glands in SjS (Fox et al, 1994;Kolkowski et al, 1999). Those proinflammatory cytokines can induce apoptosis of salivary gland cells through caspase 3 signaling (Kamachi et al, 2002;Kulkarni et al, 2006). In contrast, it is thought that hypofunction of fluid secretion from affected glands is caused by autoantibodies against muscarinic type 3 receptor (M3R) (Li et al, 2004;Koo et al, 2008).…”

Proinflammatory cytokines tumor necrosis factor-α and interferon-γ alter tight junction structure and function in the rat parotid gland Par-C10 cell line

“…Since TNF-␣ and IFN-␥ are known to cause apoptosis of human salivary gland cell lines (34,42) and salivary gland cell apoptosis has been associated with SS (23, 33, 69), we investigated whether Par-C10 cells treated with TNF-␣ and/or IFN-␥ could recover normal function after removal of the cytokines. As shown in Figs.…”

Proteome changes induced by overexpression of the p75 neurotrophin receptor (p75NTR) in breast cancer cells

“…Death effector domain containing DNA binding protein (DEDD), a highly conserved and ubiquitous Fig. 4 Mass (m/z) B C A is well described that both intrinsic and extrinsic pathways of apoptosis can lead to the cleavage of spectrin under a stress treatment (Kulkarni et al, 2006). Spectrin fragment, which acts in tetramer complexes, also regulates the balance between calpains-and caspases-mediated cell death (Bignone and Baines, 2003).…”