Actinobacillus actinomycetemcomitans感染によるヒト単球細胞のアポトーシス発現について

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We have reported that Actinobacillus actinomycetemcomitans infection induced apoptosis in a murine macrophage cen line, J774.1 cells. It is known that the human and murine immune cell response is different because of cell surface structure differences. In addition, mitogen - activated protein kinase (MAPK) activity is directly involved in apoptosis of infectd THP-1 cells. Previous studies have implicated protein kinase C (PKC) as an upstream regulator of MAPK. The aim of this study was to clarify whether human immune cells undergo apoptosis following A. actinomycetemcomitans infection. A. actinomycetemcomitans and human monocytic THP-1 cells (1000 : 1) were suspended in microtubes. The tubes were centrifuged at 1000 x g for 10 min and incubated at 37℃ for 30 min. Non-adherent bacterium were washed out by a series of centrifugations. Infected cells were transferred to a 24-well culture plate, and incubated for 24 h. Culture supernatant and nuclei were prepared from the infected cells to measure for LDH activity, DNA fragmentation, MAPK activity and tumour necrosis factor α (TNF-α) levels. A. actinomycetemcomitans-infected THP-1 cells were shown by an increase in the proportion of LDH release, fragmented DNA, p38 MAPK activity and TNF-α levels. The LDH release and DNA fragmentation were inhibited by the addition of p38 MAPK inhibitor (SB203580) or anti-TNF-α antibody or PKC inhibitor (H=7). The TNF=α levels in the infected cells decreased on addition of SB203580 or anti-TNF-α antibody. However, exogenous TNF-α did not induce apoptosis in uninfected THP-1 cells. Further, H-7 suppressed the p38 MAPK activity of the infected cells in a dose-dependent manner, while PKC activator (PMA) enhanced LDH release DNA fragmentation and p38 MAPK activity. These results suggested that the p38 MAPK activity was the most important signal for apoptosis. The p38 MAPK activity was regulated by PKC and TNF-α in A. actinomycetemcomitans-infected THP-1 cells.
北海道医療大学の論文
2005-06-30

Actinobacillus actinomycetemcomitans感染によるヒト単球細胞のアポトーシス発現について

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