Phagocytosis of fungal agents and yeast via macrophage cell surface scavenger receptors.

Abstract

BACKGROUND:

Macrophages mediate phagocytosis via cell-surface pattern-recognition-receptors (PRRs) known to recognize certain fixed patterns on pathogens. Of these PRRs, scavenger receptors class A I and II (SR-A I and II) are known to mediate the binding and internalization of a large variety of Gram +ve and Gram -ve bacteria. Their role in phagocytic clearance of fungal agents has not been described.

METHODS:

Fluorescence microscopy and phagocytosis assays were used on murine macrophage cell lines RAW264.7. Chinese hamster ovarian cell lines (CHO) transfected with SR-A-I or SRA-II and known ligands that block SRA-uptake were used to test the ability of these cells to bind fungal agents. Macrophages from mice genetically deficient in SRA (MSR-knockouts) were used to establish whether absence of these receptors affects fungal uptake.

RESULTS:

We show for the first time that the SR-A I and II on macrophages are involved in both the binding and phagocytosis of S. cerevisiae and Candida albicans. SRA-mediated binding and internalization of these pathogens is specifically inhibited by known ligands of SRA (Fucoidan and Poly G) in a dose-titratable manner. Further, CHO cells transfected with either SR-A-I or SRA-II show an increased ability to bind and internalize S. cerevisiae compared with the non-transfected parental cells. In contrast, the macrophages that are deficient in the scavenger receptor (obtained from MSR-/- mice) do not show a decreased ability to phagocytose fungal agents.

CONCLUSIONS:

Scavenger receptors mediate phagocytosis of fungal agents, representing perhaps an alternative, fall back mechanism.

• Authors: Ruibo Wang, Rajiv Y Chandawarkar
• Journal: The Journal of surgical research (J Surg Res) Vol. 164 Issue 2 Pg. e273-9 (Dec 2010) ISSN: 1095-8673 [Electronic] United States
• PMID: 20888598 (Publication Type: Journal Article)
• Copyright: Copyright © 2010 Elsevier Inc. All rights reserved.

Chemical References

• Lectins, C-Type
• Mannose Receptor
• Mannose-Binding Lectins
• Receptors, Cell Surface
• Receptors, Scavenger
• Scavenger Receptors, Class A
• Scavenger Receptors, Class B
• Fluorescein-5-isothiocyanate

Topics

• Animals
• CHO Cells (physiology)
• Candida albicans (physiology)
• Cell Line
• Cell Membrane (physiology)
• Cricetinae
• Cricetulus
• Fluorescein-5-isothiocyanate
• Lectins, C-Type (physiology)
• Macrophages (physiology)
• Mannose Receptor
• Mannose-Binding Lectins (physiology)
• Mice
• Mice, Knockout
• Microscopy, Fluorescence (methods)
• Phagocytosis
• Receptors, Cell Surface (physiology)
• Receptors, Scavenger (deficiency)
• Saccharomyces cerevisiae (physiology)
• Scavenger Receptors, Class A (genetics, physiology)
• Scavenger Receptors, Class B (genetics, physiology)
• Transfection