Expression of listeriolysin O by intracellular Listeria monocytogenes following infection of lipopolysaccharide-treated or untreated J774.1 macrophage-like cells |
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Authors: | Kohji Moriishi Minako Koura Fumio Amano |
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Affiliation: | Department of Veterinary Science, National Institute of Health, Toyama 1-23-1, Shinjuku-ku, Tokyo 162, Japan;Department of Biochemistry and Cell Biology, National Institute of Health, Toyama 1-23-1, Shinjuku-ku, Tokyo 162, Japan |
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Abstract: | Abstract Listeria monocytogenes replicates in a phagocytic cell following escape into the host cytoplasm. Listeriolysin O, secreted by L. monocytogenes , which belongs to the thiol-activated hemolysin family, is known to play an important role in the escape of the bacterium into the host cytoplasm. In this study, we demonstrated that expression of listeriolysin O by infecting L. monocytogenes was lightly induced in J774.1 macrophage-like cells pretreated with lipopolysaccharide, although the growth of the bacteria was suppressed. The number of viable L. monocytogenes decreased until 4 h post-infection and then increased between 4 and 8 h post-infection in untreated J774.1 host cells, but it decreased until 8 h post-infection in lipopolysaccharide-treated host cells. However, expression of listeriolysin O by L. monocytogenes was not induced in the untreated host cells, while it increased between 0 and 4 h post-infection in the lipopolysaccharide-treated host cells. Expression of listeriolysin O mRNA in the lipopolysaccharide-treated host cells was also induced at 2 h post-infection, suggesting that listeriolysin O was newly synthesized in the macrophage-like cells. These results suggest that macrophage activation induced with lipopolysaccharide could lead to the expression of the listeriolysin O gene and the synthesis of listeriolysin O protein under suppression of the intracellular growth of L. monocytogenes . |
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Keywords: | Listeriolysin Listeria monocytogenes Macrophage-like cells Lipopolysaccharide |
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