Environmental dimensionality controls the interaction of phagocytes with the pathogenic fungi Aspergillus fumigatus and Candida albicans

PLoS Pathog. 2007 Feb;3(2):e13. doi: 10.1371/journal.ppat.0030013.

Abstract

The fungal pathogens Aspergillus fumigatus and Candida albicans are major health threats for immune-compromised patients. Normally, macrophages and neutrophil granulocytes phagocytose inhaled Aspergillus conidia in the two-dimensional (2-D) environment of the alveolar lumen or Candida growing in tissue microabscesses, which are composed of a three-dimensional (3-D) extracellular matrix. However, neither the cellular dynamics, the per-cell efficiency, the outcome of this interaction, nor the environmental impact on this process are known. Live imaging shows that the interaction of phagocytes with Aspergillus or Candida in 2-D liquid cultures or 3-D collagen environments is a dynamic process that includes phagocytosis, dragging, or the mere touching of fungal elements. Neutrophils and alveolar macrophages efficiently phagocytosed or dragged Aspergillus conidia in 2-D, while in 3-D their function was severely impaired. The reverse was found for phagocytosis of Candida. The phagocytosis rate was very low in 2-D, while in 3-D most neutrophils internalized multiple yeasts. In competitive assays, neutrophils primarily incorporated Aspergillus conidia in 2-D and Candida yeasts in 3-D despite frequent touching of the other pathogen. Thus, phagocytes show activity best in the environment where a pathogen is naturally encountered. This could explain why "delocalized" Aspergillus infections such as hematogeneous spread are almost uncontrollable diseases, even in immunocompetent individuals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aspergillus fumigatus / immunology*
  • Candida albicans / immunology*
  • Cell Movement
  • Cells, Cultured
  • Dendritic Cells / immunology
  • Environment
  • Humans
  • Luminescent Proteins / genetics
  • Mice
  • Mice, Inbred BALB C
  • Neutrophils / immunology
  • Phagocytes / immunology*
  • Phagocytosis*
  • Promoter Regions, Genetic

Substances

  • Luminescent Proteins
  • fluorescent protein 583