Platelet-activating factor-like activity isolated from Trypanosoma cruzi.
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.
Gomes
Marta T
MT
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.
Monteiro
Robson Q
RQ
Grillo
Luciano A
LA
Leite-Lopes
Francisco
F
Stroeder
Heleni
H
Ferreira-Pereira
Antonio
A
Alviano
Celuta S
CS
Barreto-Bergter
Eliana
E
Neto
Hugo Castro-Faria
HC
Cunha E Silva
Narcisa L
NL
Almeida
Igor C
IC
Soares
Rosangela M A
RM
Lopes
Angela H
AH
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
D010972:Platelet Activating Factor; D015800:Protozoan Proteins