Role of IL-beta converting enzyme on the induction of apoptosis mediated by the infection of periodontopathic bacteria infection

我们之前已经报道了牙周病细菌放线菌在小鼠巨噬细胞系J774.1中引起细胞凋亡的证据。在这项研究中，我们检测了蛋白激酶在a.t actinomycetemcomitans感染的J774.1细胞诱导凋亡中的作用。蛋白激酶C （PKC）激活剂预培养J774.1细胞后，放线菌酵母感染的J774.1细胞凋亡率升高。相反，PKA激活剂不能模仿PKC激活剂的作用。此外，PKC抑制剂抑制了a.c放线菌comitans感染的J774.1细胞的凋亡细胞死亡。本研究结果提示，通过PKC传递的信号可能在巨噬细胞感染放线菌后的凋亡调控中起重要作用。接下来，我们研究了caspase，白细胞介素-1 β (il -1 β)转换酶家族蛋白酶，在感染的J774.1细胞凋亡调控中的作用。两种半胱天冬酶的肽抑制剂，苄氧羰基-缬氨酸- α - asp (OMe)-氟甲基酮（Z-VAD-FMK； caspase-1抑制剂）和苄氧羰基- asp -葡氨酸-缬氨酸- asp (OMe)-氟甲基酮（DEVD-FMK； caspase-3抑制剂）抑制了a.c ray omycetemcomitans感染的J774.1细胞的凋亡诱导。此外，Z-VAD-FMK还能抑制a.l actinomycetemcomitans感染的J774.1细胞il -1 β的产生。对J774.1细胞进行内源性caspase-3活性分析，发现放线菌感染后caspase-3活性明显升高。此外，Z-VAD-FMK和DEVD-FMK可抑制放线菌感染J774.1细胞的caspase-3活性。这些发现提示caspase-1和caspase- 3参与了a .放线菌感染巨噬细胞凋亡的调控。

We have previously reported the evidence for apoptosis in the mouse macrophage cell line J774.1 by the periodontopathic bacterium Actinobacillus actinomycetemcomitans. In this study, we examined the role of protein kinases in the induction of apoptosis in A.actinomycetemcomitans-infected J774.1 cells. After J774.1 cells were precultured with protein kinase C (PKC) activator, J774.1 cells infected with A.actinomycetemcomitans showed the increased percentage of apoptotic cells. On the contrary, PKA activator do not mimic the effect of PKC activator. In addition, PKC inhibitors suppressed apoptotic cell death in J774.1 cells infected with A.actinomycetemcomitans. The results presented here suggest that the signals through PKC may play crucial roles in the modulation of apoptosis in macrophages infected with A.actinomycetemcomitans. Next, we examined the role of caspases, interleukin-1beta (IL-1beta) converting enzyme family proteases, in the regulation of apoptosis in infected J774.1 cells. TWo peptide inhibitors of caspases, benzyloxycarbonyl-Val-Ala-Asp (OMe)-fluoromethyl ketone (Z-VAD-FMK ; caspase-1 inhibitor)and benzyloxycarbonyl-Asp-Glu-Val-ASP (OMe)-fluoromethyl ketone (DEVD-FMK ; caspase-3 inhibitor) inhibited the induction of apoptosis in J774.1 cells infected with A.actinomycetemcomitans. Furhtermore, Z-VAD-FMK suppressed the production of IL-1beta from A.actinomycetemcomitans-infected J774.1 cells. When endogenous caspase-3 activity of J774.1 cells were analyzed, caspase-3 activity was markedly increased after A.actinomycetemcomitans infection. In addition, Z-VAD-FMK and DEVD-FMK suppressed caspase-3 activity of J774.1 cells infected with A.actinomycetemcomitans. These findings suggest that caspase-1 and-3 are involved in the regulation of apoptosis in macrophages infected with A.actinomycetemcomitans.