title: Role of caveolae in Leishmania chagasi phagocytosis and intracellular survival in macrophages.
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.
authors.affiliation: Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Nilda E
authors.initials: NE
authors.lastname: Rodríguez
authors.forename: Upasna
authors.initials: U
authors.lastname: Gaur
authors.forename: Mary E
authors.initials: ME
authors.lastname: Wilson
mesh_terms: D000818:Animals; D021941:Caveolae / Q000502:physiology*; D051242:Caveolin 1 / Q000378:metabolism; D002772:Cholera Toxin / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism; D005732:Gangliosides / Q000378:metabolism; D007700:Kinetics; D018314:Leishmania infantum / Q000472:pathogenicity*; D008247:Lysosomes / Q000469:parasitology / Q000502:physiology; D008264:Macrophages / Q000469:parasitology* / Q000648:ultrastructure; D008561:Membrane Fusion / Q000502:physiology; D051379:Mice; D018613:Microscopy, Confocal; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology*
chemical_list: D051242:Caveolin 1; D005732:Gangliosides; D002772:Cholera Toxin; D002784:Cholesterol