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[Influence of hemolytic and non-hemolytic enterococci on TNF-alpha expression in murine macrophage cells]
Qiang Hua1, Zheng Xiaohui, Lin Jianyin
1Department of Medical Microbiology and Parasitology, Fujian Medical University, Fuzhou 350004, China. qianghua66@sina.com
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).
Conclusion:
hemolytic enterococci promoted the generation of inflammatory factor TNF-alpha.
Insights
Hemolytic enterococci significantly increase tumor necrosis factor-alpha (TNF-alpha) production in murine macrophages compared to non-hemolytic strains. This suggests hemolytic enterococci promote inflammatory responses.
Area of Science:
- Immunology
- Microbiology
Context:
- Enterococci are common bacteria, some strains of which can cause disease.
- Tumor necrosis factor-alpha (TNF-alpha) is a key inflammatory cytokine involved in host defense and disease pathogenesis.
Purpose:
- To investigate the differential effect of hemolytic and non-hemolytic enterococci on TNF-alpha expression in murine macrophage cells.
Summary:
- RAW264.7 murine macrophages were infected with hemolytic or non-hemolytic enterococci.
- TNF-alpha protein and mRNA levels were measured using ELISA and RT-PCR, respectively.
- Hemolytic enterococci induced significantly higher TNF-alpha production and mRNA expression compared to non-hemolytic strains.
Impact:
- Hemolytic enterococci actively promote the generation of the inflammatory factor TNF-alpha.
- Findings highlight the importance of bacterial hemolytic activity in modulating host inflammatory responses.
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