Host-derived microvesicles carrying bacterial pore-forming toxins deliver signals to macrophages: a novel mechanism of shaping immune responses
Research output: Contribution to journal › Article › peer-review
Colleges, School and Institutes
- Institute of Anatomy; University of Bern; Baltzerstrasse 2 3012 Bern Switzerland
- Department of Medical Oncology, University Hospital Bern, Bern, Switzerland.
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
Bacterial infectious diseases are a leading cause of death. Pore-forming toxins (PFTs) are important virulence factors of Gram-positive pathogens, which disrupt the plasma membrane of host cells and can lead to cell death. Yet, host defense and cell membrane repair mechanisms have been identified: i.e., PFTs can be eliminated from membranes as microvesicles, thus limiting the extent of cell damage. Released into an inflammatory environment, these host-derived PFTs-carrying microvesicles encounter innate immune cells as first-line defenders. This study investigated the impact of microvesicle- or liposome-sequestered PFTs on human macrophage polarization in vitro. We show that microvesicle-sequestered PFTs are phagocytosed by macrophages and induce their polarization into a novel CD14+MHCIIlowCD86low phenotype. Macrophages polarized in this way exhibit an enhanced response to Gram-positive bacterial ligands and a blunted response to Gram-negative ligands. Liposomes, which were recently shown to sequester PFTs and so protect mice from lethal bacterial infections, show the same effect on macrophage polarization in analogy to host-derived microvesicles. This novel type of polarized macrophage exhibits an enhanced response to Gram-positive bacterial ligands. The specific recognition of their cargo might be of advantage in the efficiency of targeted bacterial clearance.
|Number of pages||13|
|Journal||Frontiers in immunology|
|Publication status||Published - 27 Jul 2018|
- macrophage polarization, microvesicles, liposomes, bacterial pore-forming toxins, host-defense