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Infect. Immun., Nov 1997, 4813-4821, Vol 65, No. 11
K Ruckdeschel, A Roggenkamp, V Lafont, P Mangeat, J Heesemann and B Rouot
Suppression of the host defense is one of the hallmarks of Yersinia
enterocolitica infection. This enteric pathogen resists phagocytosis and
interferes with macrophage functions from an extracellular localization
(oxidative-burst generation and tumor necrosis factor alpha production). In
this study, we investigated the fate of the Y. enterocolitica-infected
macrophage. We found that murine J774A.1 macrophages and macrophages
derived from human monocytes were killed by infection with Y.
enterocolitica. Analysis of cellular morphology and DNA fragmentation
revealed that macrophage cell death occurs through the induction of
apoptosis. A total of 92% +/- 5% (mean +/- standard deviation) of murine
J774A.1 macrophages and 74% +/- 6% of human monocyte-derived macrophages
underwent apoptosis upon Yersinia infection after 4 and 20 h, respectively.
The broad-spectrum caspase inhibitor Z-Val-Ala-DL-Asp-fluoromethylketone
blocked completion of the Yersinia-induced apoptotic program but not the
surface exposure of phosphatidylserine as an early-stage apoptotic event.
Analysis of different Yersinia mutants showed that macrophage apoptosis
depends on a functional Y. enterocolitica type III protein secretion
system. Apoptotic cell death of macrophages was not related to the YopE-
mediated cytotoxic effect of Yersinia, since disruption of actin
microfilaments by a Y. enterocolitica strain expressing a restricted
repertoire of yop genes, including YopE, did not result in macrophage
apoptosis. Furthermore, Yersinia-induced cytotoxic alterations in
epithelial HeLa cells, which are conferred by YopE, did not lead to
apoptosis. Our data demonstrate for the first time that Y. enterocolitica
promotes the apoptosis of macrophages, an effect which is clearly distinct
from the morphological alterations mediated by Yersinia on epithelial HeLa
cells.
Copyright © 1997, American Society for Microbiology
Interaction of Yersinia enterocolitica with macrophages leads to macrophage cell death through apoptosis
INSERM U431, Universite Montpellier II, France.
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