Regulation of apoptotic cell death by cytokines in a human salivary gland cell line: distinct and synergistic mechanisms in apoptosis induced by tumor necrosis factor alpha and interferon gamma.
We examined the mechanisms of apoptosis in a human salivary gland (HSG) cell line induced by tumor necrosis factor (TNF) alpha and interferon (IFN) gamma. DNA fragmentation and the activation of caspase-3 were determined in HSG cells cultured with TNF-alpha or IFN-gamma. Mitochondrial dysfunction also appeared to be involved in the process because a disruption of mitochondrial transmembrane potential with the activation of caspase-9 was demonstrated in TNF-alpha- and IFN-gamma-stimulated HSG cells. Activation of caspase-8 was thought to be essential in TNF-alpha--induced apoptosis of HSG cells; however, the activation of caspase-8 was not involved in IFN-gamma-induced apoptosis of HSG cells. In contrast, Bcl-2 appeared to be an indispensable regulatory molecule in IFN-gamma-induced, but not in TNF-alpha-induced, apoptosis of HSG cells because its expression was inhibited in IFN-gamma-stimulated, but not in TNF-alpha-stimulated, cells. The inhibitory effect of IFN-gamma in Bcl-2 expression was enhanced by coadministration of TNF-alpha and, interestingly, apoptosis of HSG cells, as assessed by DNA fragmentation and the activation of caspase-9 and caspase-3, and disruption of mitochondrial transmembrane potential was also synergistically augmented by TNF-alpha and IFN-gamma. Our results suggest that cytokines expressed in the salivary glands of patients with Sjögren syndrome play an important role in regulating apoptosis of acinar-ductal epithelial cells through distinct and synergistic mechanisms, thereby modulating salivary gland function in patients with Sjögren syndrome.
Kamachi
Makoto
M
First Department of Internal Medicine, Nagasaki University School of Medicine, Sakamoto, Nagasaki, Japan.
Kawakami
Atsushi
A
Yamasaki
Satoshi
S
Hida
Ayumi
A
Nakashima
Tomoki
T
Nakamura
Hideki
H
Ida
Hiroaki
H
Furuyama
Masako
M
Nakashima
Koto
K
Shibatomi
Kazutaka
K
Miyashita
Taiichiro
T
Migita
Kiyoshi
K
Eguchi
Katsumi
K
D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D002460:Cell Line; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D012469:Salivary Glands / Q000166:cytology / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D004792:Enzyme Precursors; D019253:Proto-Oncogene Proteins c-bcl-2; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases