Alteration of Fatty Acid and Sterol Metabolism in Miltefosine-Resistant Leishmania donovani Promastigotes and Consequences for Drug-Membrane Interactions

Abstract

Miltefosine (hexadecylphosphocholine [HePC]) is the first orally active drug approved for the treatment of visceral leishmaniasis. In order to investigate the biochemical modifications occurring in HePC-resistant (HePC-R) Leishmania donovani promastigotes, taking into account the lipid nature of HePC, we investigated their fatty acid and sterol metabolisms. We found that the content of unsaturated phospholipid alkyl chains was lower in HePC-R parasite plasma membranes than in those of the wild type, suggesting a lower fluidity of HePC-R parasite membranes. We also demonstrated that HePC insertion within an external monolayer was more difficult when the proportion of unsaturated phospholipids decreased, rendering the HePC interaction with the external monolayer of HePC-R parasites more difficult. Furthermore, HePC-R parasite membranes displayed a higher content of short alkyl chain fatty acids, suggesting a partial inactivation of the fatty acid elongation enzyme system in HePC-R parasites. Sterol biosynthesis was found to be modified in HePC-R parasites, since the 24-alkylated sterol content was halved in HePC-R parasites; however, this modification was not related to HePC sensitivity. In conclusion, HePC resistance affects three lipid biochemical pathways: fatty acid elongation, the desaturase system responsible for fatty acid alkyl chain unsaturation, and the C-24-alkylation of sterols.Leishmania spp. are the protozoan parasites responsible for leishmaniases, a family of diseases including a variety of clinical manifestations classically labeled as visceral, cutaneous, and mucocutaneous leishmaniases (9). Chemotherapy is the main tool for the control of leishmaniasis; however, the standard treatments, including pentavalent antimonials, amphotericin B (AmB), and paromomycin, are toxic and expensive.

Cos-Seq for high-throughput identification of drug target and resistance mechanisms in the protozoan parasite Leishmania

“…MTF is an alkylphosphocholine that mainly interferes with alkyl-lipid metabolism, phospholipid biosynthesis, and membrane composition and fluidity in Leishmania (49-51). Moreover, modification of lipid membrane content has been described in MTF-resistant lines (52). We found two genes, on cosmids LinJ.29b (LinJ.29.2250) and LinJ.…”

“…Cos-Seq nonetheless allows detection of indirect resistance mechanisms resulting from drug transport alterations. For example, modification of membrane lipid content has been described in MTF-resistant lines (52), and the two genes characterized in the MTF Cos-Seq screen, which pertain to ergosterol biosynthesis and phospholipid translocation, might well trigger MTF resistance via membrane fluidity/ permeability changes.…”

Miltefosine: First Oral Drug for Treatment of Visceral Leishmaniasis

“…In laboratory studies it was observed that in wild-type promastigotes of Leishmania donovani, miltefosine is able to induce a cell death process with numerous cytoplasmic, nuclear, and membrane features of metazoan apoptosis, including cell shrinkage, DNA fragmentation into oligonucleosome-sized fragments, and phosphatidylserine exposure. The activity of miltefosine is attributed to interaction with cell signal transduction pathways and inhibition of phospholipids and sterol biosynthesis [4]. Miltefosine does not appear to kill L.donovani promastigotes by direct toxic mechanism.…”

Interaction of Alkylphospholipid Formulations with Breast Cancer Cells in the Context of Anticancer Drug Development

“…Since biological membranes are composed of dynamically condensed domains surrounded by fluid domains, it has been suggested that, above the CMC, alkylphospholipids can insert into both kinds of phases: as monomers into the condensed phase and as a group of monomers into the fluid phase. (Rakotomanga et al, 2005). The presence of albumin in the medium has the effect of increasing the CMC value by binding molecules of lipids and, hence, reducing the concentration of free monomers in the medium (Kim et al, 2007).…”