title: Platelet-activating factor-like activity isolated from Trypanosoma cruzi.
abstract: Platelet-activating factor is a phospholipid mediator that exhibits a wide variety of physiological and pathophysiological effects, including induction of inflammatory response, chemotaxis and cellular differentiation. Trypanosoma cruzi, the etiological agent of Chagas' disease, is transmitted by triatomine insects and while in the triatomine midgut the parasite differentiates from a non-infective epimastigote stage into the pathogenic trypomastigote metacyclic form. We have previously demonstrated that platelet activating factor triggers in vitro cell differentiation of T. cruzi. Here we show a platelet activating factor-like activity isolated from lipid extract of T. cruzi epimastigotes incubated in the presence of [14C]acetate. Trypanosoma cruzi-platelet activating factor-like lipid induced the aggregation of rabbit platelets, which was prevented by platelet activating factor-acetylhydrolase. Mouse macrophage infection by T. cruzi was stimulated when epimastigotes were kept for 5 days in the presence of T. cruzi-platelet activating factor, before interacting with the macrophages. The differentiation of epimastigotes into metacyclic trypomastigotes was also triggered by T. cruzi-platelet activating factor. These effects were abrogated by a platelet activating factor antagonist, WEB 2086. Polyclonal antibody raised against mouse platelet activating factor receptor showed labelling for T. cruzi epimastigotes using immunoblotting and immunofluorescence assays. These data suggest that T. cruzi contain the components of an autocrine platelet activating factor-like ligand-receptor system that modulates cell differentiation towards the infectious stage.
authors.affiliation: Instituto de Microbiologia, Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Cidade Universitária, CCS, Bloco I, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil.
authors.forename: Marta T
authors.initials: MT
authors.lastname: Gomes
authors.forename: Robson Q
authors.initials: RQ
authors.lastname: Monteiro
authors.forename: Luciano A
authors.initials: LA
authors.lastname: Grillo
authors.forename: Francisco
authors.initials: F
authors.lastname: Leite-Lopes
authors.forename: Heleni
authors.initials: H
authors.lastname: Stroeder
authors.forename: Antonio
authors.initials: A
authors.lastname: Ferreira-Pereira
authors.forename: Celuta S
authors.initials: CS
authors.lastname: Alviano
authors.forename: Eliana
authors.initials: E
authors.lastname: Barreto-Bergter
authors.forename: Hugo Castro-Faria
authors.initials: HC
authors.lastname: Neto
authors.forename: Narcisa L
authors.initials: NL
authors.lastname: Cunha E Silva
authors.forename: Igor C
authors.initials: IC
authors.lastname: Almeida
authors.forename: Rosangela M A
authors.initials: RM
authors.lastname: Soares
authors.forename: Angela H
authors.initials: AH
authors.lastname: Lopes
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000379:methods; D005455:Fluorescent Antibody Technique; D008018:Life Cycle Stages; D008264:Macrophages / Q000469:parasitology*; D051379:Mice; D010972:Platelet Activating Factor / Q000032:analysis* / Q000494:pharmacology; D010974:Platelet Aggregation; D015800:Protozoan Proteins / Q000032:analysis* / Q000494:pharmacology; D011817:Rabbits; D014349:Trypanosoma cruzi / Q000737:chemistry* / Q000254:growth & development
chemical_list: D010972:Platelet Activating Factor; D015800:Protozoan Proteins