Glutathione protects macrophages and Leishmania major against nitric oxide-mediated cytotoxicity.
The aim of this investigation was to examine whether macrophage and Leishmania major glutathione were involved in either host or parasite protection against NO cytotoxicity. Buthionine sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthase, caused a complete and irreversible depletion of macrophage glutathione, but only a 20% and reversible decrease in L. major glutathione. Glutathione-depleted macrophages, when activated with IFN-gamma/LPS, released less than 60% of the NO produced by untreated macrophages, resulting in a corresponding decrease in their leishmanicidal activity. BSO-treated macrophages were more susceptible to the cytotoxic effects of the NO donor SNAP. Treatment of macrophages with 1,3-bis(chloroethyl)-1-nitrosourea (BCNU), an inhibitor of glutathione reductase and trypanothione reductase or with Br-Octane, a glutathione-S-transferase substrate, resulted in a transient decrease in glutathione levels and did not increase the susceptibility of the macrophages to SNAP. Treatment of the promastigote forms of L. major with BCNU resulted in an 80% decrease in total glutathione concentration with no concomitant change in viability. However, this treatment rendered the parasites more susceptible to SNAP. Finally, macrophage glutathione protected the internalized L. major from SNAP. Overall, these results demonstrate that glutathione is an essential protective component against NO cytotoxicity on both macrophages and parasites.
Faculty of Medicine of Ribeirão Preto, Department of Immunology, University of São Paulo, Ribeirão Preto, Brazil.
P R
PR
Romão
S G
SG
Fonseca
J S
JS
Hothersall
A A
AA
Noronha-Dutra
S H
SH
Ferreira
F Q
FQ
Cunha
D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002330:Carmustine / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000187:drug effects / Q000378:metabolism*; D018320:Leishmania major / Q000187:drug effects / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism* / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology
D004791:Enzyme Inhibitors; C110881:S-nitro-N-acetylpenicillamine; D009569:Nitric Oxide; D019328:Buthionine Sulfoximine; D005978:Glutathione; D010396:Penicillamine; D002330:Carmustine