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Lysozyme activates Enterococcus faecium to induce necrotic cell death in macrophages
Sabine Gröbner1, Evelyn Fritz, Friederike Schoch
1Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany. sabine.groebner@med.uni-tuebingen.de
Cellular and Molecular Life Sciences : CMLS
|May 12, 2010
Summary
Enterococci exposure to lysozyme triggers necrotic cell death in macrophages. This mechanism, independent of bacterial uptake, may facilitate host infections by these opportunistic pathogens.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Enterococci are common gut bacteria but can cause severe hospital-acquired infections.
- Facultative pathogenic bacteria may evade immune responses by inducing host cell death.
Purpose of the Study:
- To investigate if Enterococcus faecium induces host cell death to evade innate immunity.
- To elucidate the mechanism of cell death induced by E. faecium.
Main Methods:
- In vitro and in vivo studies using J774A.1 macrophages and a mouse peritonitis model.
- Flow cytometry, electron microscopy, and lactate dehydrogenase release assays were employed.
- Investigated the role of caspases, bacterial uptake, and intracellular replication in cell death.
Main Results:
- E. faecium induced necrotic cell death in macrophages, characterized by loss of membrane integrity and mitochondrial potential.
- Cell death was independent of caspase activation, bacterial uptake, and intracellular replication.
- Lysozyme pre-treatment of E. faecium reduced cell death, implicating a surface protein.
Conclusions:
- Enterococci can induce necrotic macrophage death under specific conditions (e.g., lysozyme exposure).
- This cell death induction may be a mechanism for enterococci to cause disseminated infections.
- A bacterial surface protein is likely involved in triggering this necrotic cell death.
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