Actinobacillus actinomycetemcomitans induces apoptosis in human monocytic THP-1 cells
Actinobacillus actinomycetemcomitans induces apoptosis in human monocytic THP-1 cells
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DOI：
10.1099/jmm.0.45693-0
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发表时间：
2005-03-01
影响因子：
3
通讯作者：
Kowashi, Y
中科院分区：
文献类型：
--
作者：
Kato, S;Sugimura, N;Kowashi, Y
此前有报道称，小鼠巨噬细胞系J774.1和人口腔上皮细胞系KB因放线菌感染而发生凋亡。最近的研究表明，细胞凋亡的调节是由几种不同蛋白激酶的多重磷酸化所调节的，包括有丝分裂原激活蛋白激酶（MAPK）家族的主要亚型。MAPK家族在生长因子刺激下促进细胞存活和/或增殖，或在各种应激刺激下促进细胞凋亡。本研究的主要目的是澄清人类免疫细胞是否在A.放线菌感染后发生凋亡，如果是的话，确定MAPK家族的参与。放线菌在微管中感染人单核THP-1细胞。监测乳酸脱氢酶在培养上清中的释放情况和细胞内DNA的断裂情况。琼脂糖凝胶电泳还鉴定了DNA片段。放线菌感染后细胞以凋亡方式死亡，DNA片段比例增加，DNA片段呈阶梯状，表明细胞凋亡。此外，p38 MAPK活性和肿瘤坏死因子α (tnf - α)水平在放线菌感染后升高。相反，添加p38抑制剂或抗tnf - α抗体后，感染细胞中的细胞死亡和tnf - α水平降低。然而，外源性tnf - α不能诱导未感染的THP-1细胞凋亡。有趣的是，p38 MAPK活性在抗tnf - α抗体存在下降低。这些结果表明放线菌感染诱导THP-1细胞凋亡，p38 MAPK活性直接参与细胞凋亡。tnf - α可能通过增强p38 MAPK活性间接参与细胞凋亡。放线菌诱导的人类免疫细胞凋亡在牙周病的发生和发展中可能是重要的。
It has previously been reported that the murine macrophage cell line J774.1 and the human oral epithelial cell line KB undergo apoptosis as a result of Actinobacillus actinomycetemcomitans infection. Recent studies have demonstrated that apoptosis regulation is modulated by multiple phosphorylation of several different protein kinases, including the major subtypes of the mitogenactivated protein kinase (MAPK) family. The MAPK family promotes cell survival and/or proliferation in response to growth factor stimulation, or apoptosis in response to various stress stimuli. The primary objective of the present investigation was to clarify whether human immune cells undergo apoptosis following A. actinomycetemcomitans infection and, if so, to establish the involvement of the MAPK family. Human monocytic THP-1 cells were infected with A. actinomycetemcomitans in microtubes. Lactate dehydrogenase release into the culture supernatant and DNA fragmentation in the cells were monitored. DNA fragmentation was also identified by agarose gel electrophoresis. Cell death following A. actinomycetemcomitans infection occurred by apoptosis, shown by an increase in the proportion of fragmented DNA and the typical ladder pattern of DNA fragmentation indicative of apoptosis. Furthermore, p38 MAPK activity and tumour necrosis factor alpha (TNF-alpha) levels increased following A. actinomycetemcomitans infection. In contrast, cell death and TNF-alpha levels in infected cells decreased upon addition of a p38 inhibitor or an anti-TNF-alpha antibody. However, exogenous TNF-alpha could not induce apoptosis in uninfected THP-1 cells. Interestingly, p38 MAPK activity diminished in the presence of anti-TNF-alpha antibody. These findings indicated that A. actinomycetemcomitans infection induces apoptosis in THP-1 cells and that p38 MAPK activity is directly involved in apoptosis. TNF-alpha may play an indirect role in apoptosis via enhanced p38 MAPK activity. A. actinomycetemcomitans-induced apoptosis of human immune cells may be important in terms of initiation and progression of periodontal diseases.