Objectives: Oral commensal bacterium Streptococcus intermedius produces intermedilysin (ILY), a human specific cytolysin that binds to CD59. Streptococcus intermedius causes endogenous infections that can lead to liver abscess and strains expressing high levels of ILY are associated with these and other deep-seated abscesses. However, the mechanism of cell death by ILY remains unclear. This aim of this study was to investigate how ILY induces cell death in-vitro in order to clarify its role in the aetiology of liver abscess. Methods: Human hepatoma cell line HepG2 was cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, 100 U/ml penicillin, 0.1 mg/ml streptomycin, incubated at 37 °C in the presence of 5% CO2. Cytotoxicity was assayed by lactate dehydrogenase release. Nuclear shrinkage (pyknosis) was measured by a computer-assisted method following Hoechst 33342 staining. Bromoenol lactone (BEL), a selective inhibitor for all types of calcium-independent phospholipase A2 (iPLA2), and MJ33, a selective inhibitor for secretory PLA2 (sPLA2) isotype, were used to identify the involvement of PLA2. Results: ILY induced pyknosis in HepG2 cells leading to cell death. Pyknosis was partially inhibited both by inhibitor for sPLA2 and iPLA2. Conclusion: These findings suggest that PLA2s might regulate ILY-induced a cell death signalling pathway.
Division: Southeast Asian Division Meeting
Meeting:2007 Southeast Asian Division Meeting (Bali, Indonesia) Location: Bali, Indonesia
Year: 2007 Final Presentation ID: Abstract Category|Abstract Category(s):Scientific Groups
Authors
Susilowati, Heni
( Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Tokushima, N/A, Japan
)
Hirota, Katsuhiko
( Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Tokushima, N/A, Japan
)
Okamura, Hirohiko
( Histology and Oral Histology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Tokushima, N/A, Japan
)
Yoshida, Kaya
( Fundamental Oral Health Science, School of Oral Health and Welfare, Faculty of Dentistry, The University of Tokushima, Tokushima, Tokushima, N/A, Japan
)
Murakami, Keiji
( Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Tokushima, N/A, Japan
)
Tabata, Atsushi
( Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, Tokushima, N/A, Japan
)
Nagamune, Hideaki
( The University of Tokushima, Tokushima, N/A, Japan
)
Haneji, Tatsuji
( Histology and Oral Histology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Tokushima, N/A, Japan
)
Miyake, Yoichiro
( Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Tokushima, N/A, Japan
)
SESSION INFORMATION
Oral Session
Microbiology / Immunology and Infection Control