Destiny and intracellular survival of Leishmania amazonensis in control and dexamethasone-treated glial cultures: protozoa-specific glycoconjugate tagging and TUNEL staining.
Leishmania amazonensis, an obligatory intracellular parasite, survives internalization by macrophages, but no information is available on the involvement of microglia. We have investigated microglia-protozoa interactions in mixed glial cultures infected with promastigote forms of L. amazonensis after lipopolysaccharide (LPS) or dexamethasone (DM) treatment. After 2 hr of exposure to parasites in control cultures, there was a small number of infected microglia (1%). Preincubation with LPS or DM led to 14% or 60% of microglial cells with attached parasites, respectively. DM treatment resulted in 39% of microglial cells with internalized parasites (controls or LPS-treated cells had < or =1%). Scanning electron micrographs showed numerous filopodia in DM-treated cells, whereas these projections were rarely observed in LPS-treated or control cells. DM treatment also affected the intramicroglial survival of Leishmania. In control cultures, internalized parasites, tagged with an anti-lipophosphoglycan (anti-LPG) antibody, showed fragmented DNA [terminal deoxyribonucleotide transferase-mediated dUTP-X nick end labeling (TUNEL+)] after 4 hr of interaction, but changes seemed slightly delayed in DM-treated cultures. After 12 hr, there were no LPG+/TUNEL+ profiles in controls, whereas rare LPG+ profiles still persisted in DM-treated cells. Our results suggest that microglia are highly effective in the elimination of Leishmania and that the process can be effectively studied by LPG/TUNEL double labeling.
Baetas-da-Cruz
Wagner
W
Departmento de Ultra-estrutura e Biologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil. Lacav@abc.org.br
Macedo-Silva
Roger M
RM
Santos-Silva
Alessandra
A
Henriques-Pons
Andrea
A
Madeira
Maria F
MF
Corte-Real
Suzana
S
Cavalcante
Leny A
LA
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D002448:Cell Adhesion; D002478:Cells, Cultured; D016054:DNA, Protozoan / Q000032:analysis; D003907:Dexamethasone / Q000494:pharmacology*; D004705:Endocytosis; D006028:Glycosphingolipids; D020287:In Situ Nick-End Labeling; D007700:Kinetics; D007891:Leishmania / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000469:parasitology; D051379:Mice; D009457:Neuroglia / Q000187:drug effects / Q000469:parasitology*; D013194:Staining and Labeling
D000276:Adjuvants, Immunologic; D016054:DNA, Protozoan; D006028:Glycosphingolipids; D008070:Lipopolysaccharides; C008290:lipophosphonoglycan; D003907:Dexamethasone