[Influence of hemolytic and non-hemolytic enterococci on TNF-alpha expression in murine macrophage cells].
OBJECTIVE
To study the influence of hemolytic and non-hemolytic enterococci on TNF-alpha expression in Murine macrophage cells.


METHODS
The possibility of endotoxin contamination in the cell culture was excluded by polymyxin-B inhibition. RAW264.7 were infected with hemolyticor non-hemolytic enerococci at bacteria: cell ratio of 30:1 for 1 h, followed by washing and re-incubation for 24h in complete medium containing 200 microg/mL Ampicillin. TNF-alpha concentrations in culture supernatants at different time intervals after infection for 3 h, 6 h, 9 h and 24 h were measured by ELISA. TNF-alpha mRNA expression by macrophages infected with hemolytic or non-hemolytic enerococci respectively for 6h was compared by RT-PCR.


RESULTS
TNF-alpha was not detected in culture supernatants from uninfected RAW264.7 cells. The concentrations (pg/mL) of TNF-alpha present in culture supernatants from RAW264.7 cells stimulated by hemolytic enterococci were significantly higher than that stimulated by non-hemolytic enterococci at all time intervals tested, p < 0.01, Student t-test. TNF-alpha mRNA expression measured by RT-PCR brought about similar results: more TNF-alpha mRNA was expressed in RAW 264.7 cells stimulated with hemolytic enterococci as compared with non-hemolytic enterococci stimulation (p < 0.05, Student t-test).


CONCLUSIONS
hemolytic enterococci promoted the generation of inflammatory factor TNF-alpha.
Hua
Qiang
Q
Department of Medical Microbiology and Parasitology, Fujian Medical University, Fuzhou 350004, China. qianghua66@sina.com
Xiaohui
Zheng
Z
Jianyin
Lin
L
D000818:Animals; D002478:Cells, Cultured; D016983:Enterococcus / Q000472:pathogenicity* / Q000502:physiology; D015870:Gene Expression; D006461:Hemolysis; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha