Novel Apoptosis-Inducing Activity in <i>Bacteroides forsythus</i> : a Comparative Study with Three Serotypes of <i>Actinobacillus actinomycetemcomitans</i>

DOI Web Site 被引用文献6件
  • Shinichi Arakawa
    <!--label omitted: 1-->Department of Molecular Cellular Oncology and Microbiology1 and
  • Takuma Nakajima
    <!--label omitted: 1-->Department of Molecular Cellular Oncology and Microbiology1 and
  • Hiroaki Ishikura
    <!--label omitted: 1-->Department of Molecular Cellular Oncology and Microbiology1 and
  • Shizuko Ichinose
    <!--label omitted: 3-->Instrumental Analysis Research Center for Life Science,3 Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-Ku, Tokyo 113-8549, Japan
  • Isao Ishikawa
    <!--label omitted: 2-->Department of Periodontology,2 Graduate School, and
  • Nobuo Tsuchida
    <!--label omitted: 1-->Department of Molecular Cellular Oncology and Microbiology1 and
  • D. L. Burns
    editor

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<jats:title>ABSTRACT</jats:title> <jats:p> <jats:italic>Bacteroides forsythus</jats:italic> , which has been reported to be associated with periodontitis but has not been recognized as a key pathogen, was found to induce cytolytic activity against HL-60 and other human leukemic cells. This cytolytic activity was demonstrated according to three different criteria: (i) loss of both mitochondrial membrane potential and membrane integrity in cells treated with bacterial extracts and then with Rh123 and propidium iodide, respectively, as demonstrated by flow cytometry; (ii) damage to cytoplasmic membrane, as revealed by scanning electron microscopy (SEM); and (iii) DNA ladder formation and activation of caspase-3. These results indicate that <jats:italic>B. forsythus</jats:italic> produced an apoptosis-inducing factor(s) found to be composed of protein as judged by heat and trypsin sensitivity. In addition to extracts from <jats:italic>B. forsythus</jats:italic> , the culture supernatant of this bacterium has the ability to induce a cytolytic effect against peripheral white blood cells, especially lymphocytes. For comparison with <jats:italic>B. forsythus</jats:italic> , the same analyses were applied to two strains with different serotypes of <jats:italic>Actinobacillus actinomycetemcomitans</jats:italic> , serotypes a (ATCC 43717) and c (ATCC 43719), in addition to previously reported apoptosis-inducing serotype b (ATCC 43718), which was used as a positive control. The strains of <jats:italic>A. actinomycetemcomitans</jats:italic> serotypes a and b induced apoptosis in HL-60 cells as judged by the above three criteria but to a slightly lesser extent than did <jats:italic>B. forsythus</jats:italic> , while the serotype c strain produced apoptosis to a negligible extent. Detailed SEM images showed that the <jats:italic>A. actinomycetemcomitans</jats:italic> serotype a strain induced large-pore formation and the serotype b strain produced small pores with typical blebbing, while <jats:italic>B. forsythus</jats:italic> induced severe membrane ruffling. Further DNA ladder formation and caspase-3 activation were observed in the serotype a and b strains but not in the serotype c strain. The present paper is the first report of a protein factor(s) from <jats:italic>B. forsythus</jats:italic> and the <jats:italic>A. actinomycetemcomitans</jats:italic> serotype a strain which induces apoptotic cell death. </jats:p>

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