title: NAD(P)H-oxidase presence in Toxoplasma gondii tachyzoite vacuole during interaction with IFN-gamma-activated human endothelial cells.
abstract: Toxoplasma gondii invades and proliferates in human umbilical vein endothelial cells (HUVEC) where it resides in a parasitophorous vacuole (PV) preventing lysosomal fusion. To study the intracellular outcome of PV containing tachyzoites of T. gondii during interaction with IFN-gamma-activated HUVEC, a quantitative analysis of the T. gondii infection and multiplication was assayed. The quantification of PVs' fusion with lysosomes, ultrastructural examination of phagosome-lysosome fusion, and the localization of NAD(P)H-oxidase activity were also investigated. HUVEC activated with IFN-gamma inhibited T. gondii infection and multiplication by 67.5% and 91.0%, respectively. After 4 hr of infection, 10.2% of IFN-gamma-activated HUVEC exhibited phagosome-lysosome fusion assayed by fluorescence microscopy, which was also observed at the ultrastructural level. Furthermore, the enzyme NAD(P)H-oxidase present at the plasma membrane of activated HUVEC was internalized together with the parasite in 38.0% of the cells. In addition, colocalization of colloidal gold particles and reaction product of NAD(P)H-oxidase in the PV of some activated HUVEC was observed. These results suggest that NAD(P)H-oxidase may participate in a mechanism by which IFN-gamma-activated HUVEC inhibit T. gondii multiplication.
authors.affiliation: Laboratório de Cultura de Células, Departamento de Histologia e Embriologia, IBRAG, Universidade do Estado do Rio de Janeiro, Brazil.
authors.forename: Erika
authors.initials: E
authors.lastname: Cortez
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Stumbo
authors.forename: Técia Maria U
authors.initials: TM
authors.lastname: de Carvalho
authors.forename: Helene Santos
authors.initials: HS
authors.lastname: Barbosa
authors.forename: Laís
authors.initials: L
authors.lastname: Carvalho
mesh_terms: D000818:Animals; D004396:Coloring Agents; D042783:Endothelial Cells / Q000187:drug effects / Q000469:parasitology* / Q000648:ultrastructure; D005260:Female; D017979:Gold Colloid; D006651:Histocytochemistry; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008247:Lysosomes / Q000502:physiology; D051379:Mice; D046529:Microscopy, Electron, Transmission; D019255:NADPH Oxidases / Q000378:metabolism*; D010588:Phagosomes / Q000502:physiology; D014122:Toxoplasma / Q000201:enzymology* / Q000648:ultrastructure; D014471:Umbilical Veins; D014617:Vacuoles / Q000201:enzymology* / Q000469:parasitology* / Q000648:ultrastructure
chemical_list: D004396:Coloring Agents; D017979:Gold Colloid; C058457:Aurodye; D007371:Interferon-gamma; D019255:NADPH Oxidases