Capsule structure changes associated with Cryptococcus neoformans crossing of the blood-brain barrier

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Automated Measurement of Cryptococcal Species Polysaccharide Capsule and Cell Body
08:08

Automated Measurement of Cryptococcal Species Polysaccharide Capsule and Cell Body

Published on: January 11, 2018

Caroline Charlier1, Fabrice Chrétien, Marielle Baudrimont

  • 1Unité de Mycologie Moléculaire, CNRS FRE2948, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris cedex 15, France.

The American Journal of Pathology
|February 1, 2005
PubMed

Insights

Cryptococcus neoformans rapidly crosses the blood-brain barrier (BBB) via cortical capillaries, not the choroid plexus, causing microvessel damage. Changes in the fungal capsule influence organ invasion and immune evasion in meningoencephalitis.

Area of Science:

  • * Mycology and Infectious Diseases
  • * Neuroscience and Neuroimmunology

Background:

  • * Cryptococcus neoformans causes life-threatening meningoencephalitis, particularly in immunocompromised individuals.
  • * The fungal polysaccharide capsule is a key virulence factor.
  • * Understanding early dissemination events is crucial for developing effective therapies.

Purpose of the Study:

  • * To investigate the early mechanisms of blood-brain barrier (BBB) penetration by Cryptococcus neoformans in a murine model.
  • * To characterize the structural changes in the BBB and the yeast during dissemination.
  • * To explore the role of cryptococcal capsule alterations in organ invasion and immune evasion.

Main Methods:

  • * Intravenous inoculation of mice with Cryptococcus neoformans.
  • * Time-course analysis (1, 6, 24, 48 hours post-inoculation) using histology, electron microscopy, and double immunofluorescence.
  • * Examination of yeast and host tissue interactions within various organs.

Main Results:

  • * Early BBB crossing occurred through cortical capillaries, causing significant microvessel damage.
  • * Leptomeningeal seeding was a secondary event, following leakage from cortical pseudocysts.
  • * Cryptococcal capsule structure and cell size changed dynamically, varying by organ and capillary bed structure.

Conclusions:

  • * Cryptococcus neoformans breaches the BBB early via direct invasion of cortical capillaries.
  • * Dynamic alterations in the yeast capsule are associated with organ invasion and may hinder host immune responses.
  • * These findings highlight the importance of early BBB integrity and fungal capsule dynamics in cryptococcal meningoencephalitis pathogenesis.

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