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Macrophage Apoptosis Induced by Salmonella typhi R Plasmid
Yang Sui, Shu-Yan Wu, Guo-Rong Song, Yuan-Yuan Li, Jie Lv, Rui Huang*
Department of Microbiology, Medical College of Soochow University, Suzhou 215123, China
Abstract: The relationship between a virulent gene on Salmonella typhi (S. typhi) R plasmid pRST98 and macrophage apoptosis was explored. pRST98 was transferred into an attenuated strain of S. typhimurium RIA to create a transconjugant pRST98/RIA. Standard S. typhimurium virulence strain SR-11 was used as a positive control， and S. typhimurium RIA as a negative one. Multiplicity of infections (MOI) were detected. The murine macrophage J774A.1 was infected by these three strains of S. typhimurium separately in vitro. J774A.1 apoptosis was detected by flow cytometer at 0， 1， 3， 6， 12 and 24 h respectively. The ultrastructure of J774A.1 was examined using transmission electron microscope. Mitochondria membrane potential was detected by JC-1 staining. It was demonstrated that the MOI was 100∶1. SR-11 resulted in a higher apoptosis in J774A.1 than pRST98/RIA， and a conjugant pRST98/RIA was higher than RIA. Research data demonstrated that chromatin margination occurred 3 h post-infection. The apoptosis body was observed 12 h after infection， particularly in SR-11 infected cells. The majority of cells 24 h post infection were necrotic. These results indicate that the bacteria carrying plasmid pRST98 has the potential to increase macrophage apoptosis.
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