title: Killing of Paracoccidioides brasiliensis yeast cells by IFN-gamma and TNF-alpha activated murine peritoneal macrophages: evidence of H(2)O (2) and NO effector mechanisms.
abstract: Paracoccidioidomycosis is a deep mycosis, endemic in Latin America, caused by Paracoccidioides brasiliensis. Macrophage activation by cytokines is the major effector mechanism against this fungus. This work aimed at a better understanding of the interaction between yeast cells-murine peritoneal macrophages and the cytokine signals required for the effective killing of high virulence yeast-form of P. brasiliensis. In addition, the killing effector mechanisms dependent on the generation of reactive oxygen or nitrogen intermediates were investigated. Cell preincubation with IFN-gamma or TNF-alpha, at adequate doses, resulted in effective yeast killing as demonstrated in short-term (4-h) assays. Both, IFN-gamma and TNF-alpha activation were associated with higher levels of H(2)O(2) and NO when compared to nonactivation. Treatment with catalase (CAT), a H(2)O(2 )scavenger, and N(G)-monomethyl-L: -arginine (L: -NMMA), a nitric oxide synthase inhibitor, reverted the killing effect of activated cells. Taken together, these results suggest that both oxygen and L: -arginine-nitric oxide pathways play a role in the killing of highly virulent P. brasiliensis.
authors.affiliation: Department of Microbiology and Immunology, Biosciences Institute, UNESP, Rubião Júnior, Botucatu, São Paulo, CEP 18618-000, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Moreira
authors.forename: Luciane Alarcão
authors.initials: LA
authors.lastname: Dias-Melicio
authors.forename: Maria Terezinha S
authors.initials: MT
authors.lastname: Peraçoli
authors.forename: Sueli A
authors.initials: SA
authors.lastname: Calvi
authors.forename: Angela Maria
authors.initials: AM
authors.lastname: Victoriano de Campos Soares
mesh_terms: D000818:Animals; D002374:Catalase / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000494:pharmacology; D008262:Macrophage Activation / Q000187:drug effects; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000378:metabolism; D010228:Paracoccidioides / Q000276:immunology* / Q000472:pathogenicity; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D007371:Interferon-gamma; D006861:Hydrogen Peroxide; D002374:Catalase