Effect of hypoxia on macrophage infection by Leishmania amazonensis.
In the present study, we compared the effect of 5% oxygen tension (hypoxia) with a normal tension of 21% oxygen (normoxia) on macrophage infection by the protozoan parasite Leishmania amazonensis. Macrophages from different sources (human cell line U937, murine cell line J774, and murine peritoneal macrophages) exposed to hypoxia showed a reduction of the percentage of infected cells and the number of intracellular parasites per cell. Observations on the kinetics of infection indicated that hypoxia did not depress L. amazonensis phagocytosis but induced macrophages to reduce intracellular parasitism. Furthermore, hypoxia did not act synergistically with gamma-interferon and bacterial lipopolysaccharides in macrophages to induce killing of parasites. Experiments also indicated no correlation between nitric oxide production and control of infection in macrophages under hypoxic condition. Thus, we have provided the first evidence that hypoxia, which occurs in various pathological conditions, can alter macrophage susceptibility to a parasitic infection.
Departamento de Parasitologia, Instituto de Biologia, Universidade Estadual de Campinas, CxP 6109, 13087-970 Campinas, SP, Brazil.
Marcelle Carolina
MC
Colhone
Wagner Welber
WW
Arrais-Silva
Claudia
C
Picoli
Selma
S
Giorgio
D000818:Animals; D015687:Cell Hypoxia; D002460:Cell Line; D002470:Cell Survival; D002478:Cells, Cultured; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007894:Leishmania mexicana / Q000276:immunology / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology / Q000469:parasitology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000096:biosynthesis; D020298:U937 Cells
D008070:Lipopolysaccharides; D009569:Nitric Oxide; D007371:Interferon-gamma