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Differential phagocytosis of white versus opaque Candida albicans by Drosophila and mouse phagocytes.

Lohse MB, Johnson AD - PLoS ONE (2008)

Bottom Line: The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients.This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell.We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA.

ABSTRACT
The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients. Many C. albicans strains have the ability to stochastically switch between distinct white and opaque cell types, but it is not known with certainty what role this switching plays in the physiology of the organism. Here, we report a previously undescribed difference between white and opaque cells, namely their interaction with host phagocytic cells. We show that both Drosophila hemocyte-derived S2 cells and mouse macrophage-derived RAW264.7 cells preferentially phagocytose white cells over opaque cells. This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell. We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

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Phagocytosis of white and opaque C. albicans by D. melanogaster S2 and M. musculus RAW cells.White (A,C) or opaque (B,D) C. albicans cells were co-incubated with S2 cells for 3.5 hours (A,B) or RAW cells for 1 hour (C,D), lightly fixed with formaldehyde, stained with rabbit anti-Candida and Cy3-labeled anti-rabbit antibodies. Cells were then stained with a DAPI solution (blue) to localize S2 or RAW cells. C. albicans cells that were not phagocytosed appear orange in these figures.
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pone-0001473-g001: Phagocytosis of white and opaque C. albicans by D. melanogaster S2 and M. musculus RAW cells.White (A,C) or opaque (B,D) C. albicans cells were co-incubated with S2 cells for 3.5 hours (A,B) or RAW cells for 1 hour (C,D), lightly fixed with formaldehyde, stained with rabbit anti-Candida and Cy3-labeled anti-rabbit antibodies. Cells were then stained with a DAPI solution (blue) to localize S2 or RAW cells. C. albicans cells that were not phagocytosed appear orange in these figures.

Mentions: Recent studies have established D. melanogaster as a model system for studying many human pathogens, including C. albicans. Several RNAi screens have revealed a core set of genes required for phagocytosis of many microbes as well as additional genes needed specifically for individual pathogens [13], [15], [17]–[19]. These studies have also revealed differences in the efficiency of phagocytosis among fungi. For example, Stroschein-Stevenson et al., 2006 showed that C. albicans is much more efficiently phagocytosed than the non-pathogenic yeast Saccharomyces cerevisiae [15]. To compare phagocytosis of C. albicans white and opaque cells, C. albicans cells were co-incubated with S2 cells and after variable time intervals the samples were lightly formaldehyde fixed, and phagocytosis was scored using immunofluoresence. For this analysis, the fixed cells were stained with rabbit anti-Candida and anti-rabbit Cy3-labeled antibodies followed by DAPI. Since membranes were not permeabilized until after antibody staining, internalized C. albicans lack Cy3 and are visually distinguishable from the cells that were not phagocytosed. This assay, optimized to study C. albicans white cells [15] (FIG. 1A), also efficiently monitors opaque cell phagocytosis (FIG. 1B).


Differential phagocytosis of white versus opaque Candida albicans by Drosophila and mouse phagocytes.

Lohse MB, Johnson AD - PLoS ONE (2008)

Phagocytosis of white and opaque C. albicans by D. melanogaster S2 and M. musculus RAW cells.White (A,C) or opaque (B,D) C. albicans cells were co-incubated with S2 cells for 3.5 hours (A,B) or RAW cells for 1 hour (C,D), lightly fixed with formaldehyde, stained with rabbit anti-Candida and Cy3-labeled anti-rabbit antibodies. Cells were then stained with a DAPI solution (blue) to localize S2 or RAW cells. C. albicans cells that were not phagocytosed appear orange in these figures.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2198939&req=5

pone-0001473-g001: Phagocytosis of white and opaque C. albicans by D. melanogaster S2 and M. musculus RAW cells.White (A,C) or opaque (B,D) C. albicans cells were co-incubated with S2 cells for 3.5 hours (A,B) or RAW cells for 1 hour (C,D), lightly fixed with formaldehyde, stained with rabbit anti-Candida and Cy3-labeled anti-rabbit antibodies. Cells were then stained with a DAPI solution (blue) to localize S2 or RAW cells. C. albicans cells that were not phagocytosed appear orange in these figures.
Mentions: Recent studies have established D. melanogaster as a model system for studying many human pathogens, including C. albicans. Several RNAi screens have revealed a core set of genes required for phagocytosis of many microbes as well as additional genes needed specifically for individual pathogens [13], [15], [17]–[19]. These studies have also revealed differences in the efficiency of phagocytosis among fungi. For example, Stroschein-Stevenson et al., 2006 showed that C. albicans is much more efficiently phagocytosed than the non-pathogenic yeast Saccharomyces cerevisiae [15]. To compare phagocytosis of C. albicans white and opaque cells, C. albicans cells were co-incubated with S2 cells and after variable time intervals the samples were lightly formaldehyde fixed, and phagocytosis was scored using immunofluoresence. For this analysis, the fixed cells were stained with rabbit anti-Candida and anti-rabbit Cy3-labeled antibodies followed by DAPI. Since membranes were not permeabilized until after antibody staining, internalized C. albicans lack Cy3 and are visually distinguishable from the cells that were not phagocytosed. This assay, optimized to study C. albicans white cells [15] (FIG. 1A), also efficiently monitors opaque cell phagocytosis (FIG. 1B).

Bottom Line: The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients.This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell.We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA.

ABSTRACT
The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients. Many C. albicans strains have the ability to stochastically switch between distinct white and opaque cell types, but it is not known with certainty what role this switching plays in the physiology of the organism. Here, we report a previously undescribed difference between white and opaque cells, namely their interaction with host phagocytic cells. We show that both Drosophila hemocyte-derived S2 cells and mouse macrophage-derived RAW264.7 cells preferentially phagocytose white cells over opaque cells. This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell. We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

Show MeSH