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Mannose receptor contribution to Candida albicans phagocytosis by murine E-clone J774 macrophages
Isabelle Porcaro1, Michel Vidal, Sylvie Jouvert
1Laboratoire d'Immunologie et de Parasitologie EA 2413, Université Montpellier I, France. UMR CNRS 5539, Université Montpellier II, France.
Abstract:
Mannoproteins, as the main constituents of the outer layer of yeast cell walls, are able to interact with phagocytic cells in an opsonin-independent manner through the mannose receptor (MR) and to induce yeast ingestion by the professional phagocytes. Moreover, the MR also mediates endocytosis of soluble ligands through clathrin-coated pits. Here, we studied some aspects of the interaction between the MR and Candida albicans using murine E-clone macrophages and the consequences on MR trafficking. Using a pull-down assay involving mixture E-clone macrophage detergent lysate with mannosylated Sepharose beads and glutaraldehyde-fixed, heat-killed (HK) C. albicans, we found that binding of solubilized MR to mannosylated particles occurred with characteristics similar to the receptor's cell-surface mannose-binding activity. We then demonstrated that MR expressed on E-clone macrophages contributed to phagocytosis of unopsonized, HK C. albicans and that yeast phagocytosis induced a decrease in MR endocytic activity without concomitant degradation of the receptor in the time lapse studied.
Insights
Mannose receptor (MR) on macrophages binds Candida albicans, promoting yeast ingestion. Phagocytosis reduces MR endocytic activity but not receptor degradation.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Yeast mannoproteins interact with macrophage mannose receptors (MR) for opsonin-independent phagocytosis.
- Mannose receptor (MR) mediates endocytosis of soluble ligands via clathrin-coated pits.
Purpose of the Study:
- Investigate the interaction between MR and Candida albicans.
- Elucidate the consequences of this interaction on MR trafficking in macrophages.
Main Methods:
- Utilized pull-down assays with mannosylated Sepharose beads and E-clone macrophage lysates.
- Employed glutaraldehyde-fixed, heat-killed (HK) Candida albicans for binding studies.
- Assessed MR endocytic activity and receptor degradation in E-clone macrophages.
Main Results:
- Solubilized MR binding to mannosylated particles mirrored cell-surface MR activity.
- MR on E-clone macrophages facilitated phagocytosis of unopsonized, HK C. albicans.
- Yeast phagocytosis led to decreased MR endocytic activity without receptor degradation.
Conclusions:
- Macrophage mannose receptor (MR) plays a role in the direct recognition and phagocytosis of Candida albicans.
- MR trafficking is modulated by yeast phagocytosis, with reduced endocytic activity observed.
- The mannose receptor (MR) is not degraded during the phagocytosis of Candida albicans within the studied timeframe.