BACKGROUND Prostaglandins (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. METHODS LbrPGF2S 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. RESULTS Leishmania 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. CONCLUSIONS LbrPGF2S, 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.

中文翻译：

---

巴西利什曼原虫前列腺素F2α合酶影响宿主感染。

背景技术前列腺素（PG）是衍生自花生四烯酸代谢的脂质介质。它们参与细胞过程，例如炎症和组织稳态。PG的生产不限于多细胞生物。锥虫也可合成花生四烯酸的几种代谢产物。然而，尚未很好地阐明它们在这些早期分支寄生虫中的生物学作用及其在宿主-寄生虫相互作用中的作用。已在巴西利什曼原虫分泌的蛋白质组和多诺氏乳杆菌胞外小泡中观察到前列腺素F2α合酶（PGF2S）。此外，我们以前曾报道巴西乳杆菌PGF2S（LbrPGF2S）表达与小鼠致病性之间存在正相关。方法分别用western blotting和EIA法检测和定量定量检测前鞭毛体中LbrPGF2S基因的表达和PGF2α的合成。为了调查LbrPGF2S在骨髓源性巨噬细胞感染过程中在变形虫中的定位，产生了表达mCherry-LbrPGF2S的寄生虫，并在感染后48小时进行延时成像。使用ClustalW在Geneious v6和EMBOSS Needle上对来自利什曼原虫和人类的PGF2S同源序列进行了计算机分析。结果巴西利什曼原虫前鞭毛体在花生四烯酸存在下合成前列腺素F2α，在热胁迫下在静止生长期产生峰值。LbrPGF2S是富含寄生虫细胞体（鞭毛袋）分泌部位的细胞质蛋白。它是在整个前鞭毛体发育过程中组成性表达的酶，但是LbrPGF2S的过表达导致体外感染力的增加。数据表明，使用延时显微镜和表达mCherry-PGF2S（mChPGF2S）的寄生虫，LbrPGF2S可能会在48小时的感染时间内从细胞内的变形虫释放到骨髓巨噬细胞的细胞质中。结论LbrPGF2S是一种寄生虫衍生的蛋白，靶向宿主细胞的细胞质。推定的这种涉及促炎性脂质介体合成的酶向宿主细胞的转移表明了宿主-寄生虫相互作用的潜在作用，并可能部分解释了与巴西乳杆菌中LbrPGF2S的过表达相关的致病性增加。