Abstract
BackgroundProstaglandins (PG) are lipid mediators derived from arachidonic acid metabolism. They are involved in cellular processes such as inflammation and tissue homeostasis. PG production is not restricted to multicellular organisms. Trypanosomatids also synthesize several metabolites of arachidonic acid. Nevertheless, their biological role in these early-branching parasites and their role in host-parasite interaction are not well elucidated. Prostaglandin F2α synthase (PGF2S) has been observed in the Leishmania braziliensis secreted proteome and in L. donovani extracellular vesicles. Furthermore, we previously reported a positive correlation between L. braziliensis PGF2S (LbrPGF2S) expression and pathogenicity in mice.MethodsLbrPGF2S gene expression and PGF2α synthesis in promastigotes were detected and quantified by western blotting and EIA assay kit, respectively. To investigate LbrPGF2S localization in amastigotes during bone marrow-derived macrophage infection, parasites expressing mCherry-LbrPGF2S were generated and followed by time-lapse imaging for 48 h post-infection. PGF2S homolog sequences from Leishmania and humans were analyzed in silico using ClustalW on Geneious v6 and EMBOSS Needle.ResultsLeishmania braziliensis promastigotes synthesize prostaglandin F2α in the presence of arachidonic acid, with peak production in the stationary growth phase under heat stress. LbrPGF2S is a cytoplasmic protein enriched in the secretory site of the parasite cell body, the flagellar pocket. It is an enzyme constitutively expressed throughout promastigote development, but overexpression of LbrPGF2S leads to an increase of infectivity in vitro. The data suggest that LbrPGF2S may be released from intracellular amastigotes into the cytoplasm of bone marrow-derived macrophages over a 48-hour infection period, using time-lapse microscopy and mCherry-PGF2S (mChPGF2S)-expressing parasites.ConclusionsLbrPGF2S, a parasite-derived protein, is targeted to the host cell cytoplasm. The putative transfer of this enzyme, involved in pro-inflammatory lipid mediator synthesis, to the host cell suggests a potential role in host-parasite interaction and may partially explain the increased pathogenicity associated with overexpression of LbrPGF2S in L. braziliensis. Our data provide valuable insights to help understand the importance of parasite-derived lipid mediators in pathogenesis.
Highlights
Prostaglandins (PG) are lipid mediators derived from arachidonic acid metabolism
We have shown a positive correlation between LbrPGF2S ectopic overexpression in L. braziliensis and the rate of in vitro infection [4], suggesting that LbrPGF2S has a role in parasite virulence
Prostaglandin F2α synthase (PGF2S) from Leishmania braziliensis (LbrM.31.2410) and all the other Leishmania strains from the subgenus Viannia lost the third domain, all of them carry a valine in the isoleucine position, which differs from the strains of the subgenus Leishmania
Summary
Prostaglandins (PG) are lipid mediators derived from arachidonic acid metabolism. They are involved in cellular processes such as inflammation and tissue homeostasis. Prostaglandin F2α synthase (PGF2S) has been observed in the Leishmania braziliensis secreted proteome and in L. donovani extracellular vesicles. We performed gene expression analyses on two pairs of mucosal and cutaneous L. braziliensis isolates, in which proteomic profile differences between isolates were detected [4]. Comparative proteomic analysis revealed a consistently differential pattern of prostaglandin F2α synthase expression (LbrM.31.2410; LbrPGF2S), with higher protein abundance in cutaneous isolates compared to mucosal isolates [4]. Data deposited on TriTrypDB (tritrypdb.org) indicate that LbrPGF2S has been identified in the secretome of L. braziliensis and exosomes derived from Leishmania donovani. The structure of LmPGF2S protein has been resolved by crystallization [5] facilitating future study for drug design using this protein
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