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Updated: Jun 25, 2026
Isolation of Murine Peritoneal Macrophages to Carry Out Gene Expression Analysis Upon Toll-like Receptors Stimulation
Published on: April 29, 2015
Peritoneal macrophages are important for the early containment of Enterococcus faecium peritonitis in mice
Masja Leendertse1, Rob J L Willems, Ida A J Giebelen
1Center for Infection and Immunity Amsterdam, Center for Experimental and Molecular Medicine. m.leendertse@amc.uva.nl
Abstract:
The increasing incidence of infections with multi-drug resistant Enterococcus faecium necessitates studies to increase knowledge on the pathogenesis of these infections. In this study, the contribution of peritoneal macrophages during E. faecium peritonitis was investigated. In an ex vivo setting, peritoneal macrophages harvested from C57BL/6 mice were responsive to, and able to phagocytose and kill, E. faecium. In vivo, peritoneal macrophages were depleted by intraperitoneal injection of clodronate-encapsulated liposomes, prior to inducing E. faecium peritonitis. Depletion of resident peritoneal macrophages caused a clear delay in peritoneal clearance of E. faecium with increased systemic dissemination. Mice depleted of peritoneal macrophages were able to recruit macrophages and neutrophils to the peritoneal cavity after infection, comparable to control mice. Furthermore, increased levels of peritoneal cytokines and chemokines were found in mice depleted of peritoneal macrophages. This study indicates that peritoneal macrophages are important in the early containment of E. faecium peritonitis and for the regulation of the inflammatory response.
Insights
Resident peritoneal macrophages are crucial for controlling multi-drug resistant Enterococcus faecium infections. Their depletion delays bacterial clearance and increases systemic spread during peritonitis.
Area of Science:
- Immunology
- Microbiology
- Pathogenesis
Background:
- Rising incidence of multi-drug resistant Enterococcus faecium infections.
- Need for understanding Enterococcus faecium peritonitis pathogenesis.
Purpose of the Study:
- Investigate the role of peritoneal macrophages in Enterococcus faecium peritonitis.
- Determine the contribution of peritoneal macrophages to bacterial clearance and inflammatory response.
Main Methods:
- Ex vivo assessment of peritoneal macrophage interaction with Enterococcus faecium.
- In vivo depletion of peritoneal macrophages using clodronate-encapsulated liposomes.
- Induction of Enterococcus faecium peritonitis in mice.
Main Results:
- Peritoneal macrophages phagocytosed and killed Enterococcus faecium ex vivo.
- Depletion of peritoneal macrophages delayed bacterial clearance and increased systemic dissemination.
- Macrophage and neutrophil recruitment were comparable in depleted and control mice.
- Elevated peritoneal cytokines and chemokines observed in depleted mice.
Conclusions:
- Peritoneal macrophages are vital for early containment of Enterococcus faecium peritonitis.
- Peritoneal macrophages regulate the inflammatory response during infection.
- Targeting peritoneal macrophages could be a strategy for managing resistant Enterococcus faecium infections.
