title: Lipid Body Organelles within the Parasite Trypanosoma cruzi: A Role for Intracellular Arachidonic Acid Metabolism.
abstract: Most eukaryotic cells contain varying amounts of cytosolic lipidic inclusions termed lipid bodies (LBs) or lipid droplets (LDs). In mammalian cells, such as macrophages, these lipid-rich organelles are formed in response to host-pathogen interaction during infectious diseases and are sites for biosynthesis of arachidonic acid (AA)-derived inflammatory mediators (eicosanoids). Less clear are the functions of LBs in pathogenic lower eukaryotes. In this study, we demonstrated that LBs, visualized by light microscopy with different probes and transmission electron microscopy (TEM), are produced in trypomastigote forms of the parasite Trypanosoma cruzi, the causal agent of Chagas' disease, after both host interaction and exogenous AA stimulation. Quantitative TEM revealed that LBs from amastigotes, the intracellular forms of the parasite, growing in vivo have increased size and electron-density compared to LBs from amastigotes living in vitro. AA-stimulated trypomastigotes released high amounts of prostaglandin E2 (PGE2) and showed PGE2 synthase expression. Raman spectroscopy demonstrated increased unsaturated lipid content and AA incorporation in stimulated parasites. Moreover, both Raman and MALDI mass spectroscopy revealed increased AA content in LBs purified from AA-stimulated parasites compared to LBs from unstimulated group. By using a specific technique for eicosanoid detection, we immunolocalized PGE2 within LBs from AA-stimulated trypomastigotes. Altogether, our findings demonstrate that LBs from the parasite Trypanosoma cruzi are not just lipid storage inclusions but dynamic organelles, able to respond to host interaction and inflammatory events and involved in the AA metabolism. Acting as sources of PGE2, a potent immunomodulatory lipid mediator that inhibits many aspects of innate and adaptive immunity, newly-formed parasite LBs may be implicated with the pathogen survival in its host.
authors.affiliation: Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Daniel A M
authors.initials: DA
authors.lastname: Toledo
authors.affiliation: Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil.
authors.forename: Natália R
authors.initials: NR
authors.lastname: Roque
authors.affiliation: Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.|Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil.
authors.forename: Lívia
authors.initials: L
authors.lastname: Teixeira
authors.affiliation: Laboratory of Plasmonic Nanostructures, Molecular Spectroscopy and Structure Group, Department of Chemistry, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Erix A
authors.initials: EA
authors.lastname: Milán-Garcés
authors.affiliation: Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil.
authors.forename: Alan B
authors.initials: AB
authors.lastname: Carneiro
authors.affiliation: Laboratory of Plasmonic Nanostructures, Molecular Spectroscopy and Structure Group, Department of Chemistry, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Mariana R
authors.initials: MR
authors.lastname: Almeida
authors.affiliation: Laboratory of Plasmonic Nanostructures, Molecular Spectroscopy and Structure Group, Department of Chemistry, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Gustavo F S
authors.initials: GF
authors.lastname: Andrade
authors.affiliation: Department of Physics, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Jefferson S
authors.initials: JS
authors.lastname: Martins
authors.affiliation: Department of Physics, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Roberto R
authors.initials: RR
authors.lastname: Pinho
authors.affiliation: Laboratory of Immunomodulation, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil.
authors.forename: Célio G
authors.initials: CG
authors.lastname: Freire-de-Lima
authors.affiliation: Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil.
authors.forename: Patrícia T
authors.initials: PT
authors.lastname: Bozza
authors.affiliation: Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Heloisa
authors.initials: H
authors.lastname: D'Avila
authors.affiliation: Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
authors.forename: Rossana C N
authors.identifier: http://orcid.org/0000-0003-1736-0806
authors.initials: RC
authors.lastname: Melo
mesh_terms: D016718:Arachidonic Acid / Q000378:metabolism*; D014355:Chagas Disease / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D066292:Lipid Droplets / Q000378:metabolism* / Q000648:ultrastructure; D000071876:Prostaglandin-E Synthases / Q000096:biosynthesis; D015800:Protozoan Proteins / Q000096:biosynthesis; D014349:Trypanosoma cruzi / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D015800:Protozoan Proteins; D016718:Arachidonic Acid; D000071876:Prostaglandin-E Synthases; D015232:Dinoprostone