期刊
MICROBIAL PATHOGENESIS
卷 45, 期 3, 页码 173-180出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.micpath.2008.05.007
关键词
Aggregatibacter actinomycetemcomitans; Biofilm; Dispersin B; HL-60; J774-1; Leukotoxin; Macrophage; Poly-N-acetylglucosamine; THP-1
资金
- American Heart Association
- NIH [DE15124, DE16133]
- NATIONAL INSTITUTE OF DENTAL &CRANIOFACIAL RESEARCH [R01DE015124, R01DE016133] Funding Source: NIH RePORTER
Two virulence factors produced by the periodontopathogen Aggregatibacter actinomycetemcomitans are leukotoxin, a secreted lipoprotein that kills human polymorphonuclear leukocytes and macrophages, and poly-N-acetylglucosamine (PGA), a surface polysaccharide that mediates intercellular adhesion, biofilm formation and detergent resistance. In this study we examined the roles of leukotoxin and PGA in protecting A. actinomycetemcomitans cells from killing by the human macrophage cell line THP-1. Monolayers of THP-1 cells were infected with single-cell suspensions of a wild-type A. actinomycetemcomitans strain, or of isogenic leukotoxin or PGA mutant strains. After 48 h, viable bacteria were enumerated by dilution plating, macrophage morphology was evaluated microscopically, and macrophage viability was measured by a Trypan blue dye exclusion assay. The number of A. actinomycetemcomitans CFUs increased approximately twofold in wells infected with the wild-type strain, but decreased by approximately 70-90% in wells infected with the leukotoxin and PGA mutant strains. Infection with the wild-type or leukotoxin mutant strain caused a significant decrease in THP-1 cell viability, whereas infection with the PGA mutant strain did not result in any detectable changes in THP-1 viability. Pre-treatment of wild-type A. actinomycetemcomitans cells with the PGA-hydrolyzing enzyme dispersin B rendered them sensitive to killing by THP-1 cells. We concluded that both leukotoxin and PGA are necessary for evasion of macrophage killing by A. actinomycetemcomitans. (C) 2008 Elsevier Ltd. All rights reserved.
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