Role of caveolae in Leishmania chagasi phagocytosis and intracellular survival in macrophages

Cell Microbiol. 2006 Jul;8(7):1106-20. doi: 10.1111/j.1462-5822.2006.00695.x.

Abstract

Caveolae are membrane microdomains enriched in cholesterol, ganglioside M1 (GM1) and caveolin-1. We explored whether caveolae facilitate the entry of Leishmania chagasi into murine macrophages. Transient depletion of macrophage membrane cholesterol by 1 h exposure to methyl-beta-cyclodextrin (MbetaCD) impaired the phagocytosis of non-opsonized and serum-opsonized virulent L. chagasi. In contrast, MbetaCD did not affect the phagocytosis of opsonized attenuated L. chagasi. As early as 5 min after phagocytosis, virulent L. chagasi colocalized with the caveolae markers GM1 and caveolin-1, and colocalization continued for over 48 h. We explored the kinetics of lysosome fusion. Whereas fluorescent-labelled dextran entered macrophage lysosomes by 30 min after addition, localization of L. chagasi in lysosomes was delayed for 24-48 h after phagocytosis. However, after transient depletion of cholesterol from macrophage membrane with MbetaCD, the proportion of L. chagasi-containing phagosomes that fused with lysosomes increased significantly. Furthermore, intracellular replication was impaired in parasites entering after transient cholesterol depletion, even though lipid microdomains were restored by 4 h after treatment. These observations suggest that virulent L. chagasi localize in caveolae during phagocytosis by host macrophages, and that cholesterol-containing macrophage membrane domains, such as caveolae, target parasites to a pathway that promotes delay of lysosome fusion and intracellular survival.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Caveolae / physiology*
  • Caveolin 1 / metabolism
  • Cholera Toxin / pharmacology
  • Cholesterol / metabolism
  • Gangliosides / metabolism
  • Kinetics
  • Leishmania infantum / pathogenicity*
  • Lysosomes / parasitology
  • Lysosomes / physiology
  • Macrophages / parasitology*
  • Macrophages / ultrastructure
  • Membrane Fusion / physiology
  • Mice
  • Microscopy, Confocal
  • Phagocytosis / drug effects
  • Phagocytosis / physiology*

Substances

  • Caveolin 1
  • Gangliosides
  • Cholera Toxin
  • Cholesterol