Flagella facilitate escape of Salmonella from oncotic macrophages.
The intracellular parasite Salmonella enterica serovar Typhimurium causes a typhoid-like systemic disease in mice. Whereas the survival of Salmonella in phagocytes is well understood, little has been documented about the exit of intracellular Salmonella from host cells. Here we report that in a population of infected macrophages Salmonella induces "oncosis," an irreversible progression to eukaryotic cell death characterized by swelling of the entire cell body. Oncotic macrophages (OnMphis) are terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling negative and lack actin filaments (F-actin). The plasma membrane of OnMphis filled with bacilli remains impermeable, and intracellular Salmonella bacilli move vigorously using flagella. Eventually, intracellular Salmonella bacilli intermittently exit host cells in a flagellum-dependent manner. These results suggest that induction of macrophage oncosis and intracellular accumulation of flagellated bacilli constitute a strategy whereby Salmonella escapes from host macrophages.
Sano
Gen-ichiro
G
Department of Microbiology and Immunology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
Takada
Yasunari
Y
Goto
Shinichi
S
Maruyama
Kenta
K
Shindo
Yutaka
Y
Oka
Kotaro
K
Matsui
Hidenori
H
Matsuo
Koichi
K
D000818:Animals; D002460:Cell Line; D003599:Cytoskeleton; D005260:Female; D005407:Flagella / Q000502:physiology*; D008264:Macrophages / Q000166:cytology* / Q000382:microbiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009068:Movement; D009336:Necrosis; D012481:Salmonella Infections, Animal / Q000382:microbiology; D012486:Salmonella typhimurium / Q000166:cytology / Q000502:physiology*