The water and ionic permeability induced by polyene antibiotics across plasma membrane vesicles from Leishmania sp

Cohen, Benjamin E.; Ramos, H.; Gamargo, M.; Urbina, Julio A.

doi:10.1016/0005-2736(86)90498-0

Cited by 36 publications

(14 citation statements)

References 29 publications

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“…The toxicity induced by AMB is now believed to involve several different mechanisms: cell membrane permeability due to complexes formed between the antibiotic and sterol (5) and lipid peroxidation induced by the auto-oxidation of antibiotic (3,6). Similar mechanisms of toxicity against Leishmania have been shown (8,33,34).…”

Section: Discussionsupporting

confidence: 68%

Toxicity and Antileishmanial Activity of a New StableLipid Suspension of AmphotericinB

Larabi¹,

Yardley²,

Loiseau

et al. 2003

Antimicrob Agents Chemother

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The aim of the present study was to evaluate the toxicity and the activity of a new lipid complex formulation of amphotericin B (AMB) (LC-AMB; dimyristoyl phosphatidylcholine, dimyristoyl phosphatidylglycerol, and AMB) that can be produced by a simple process. Like other lipid formulations, this new complex reduced both the hemolytic activity of AMB (the concentration causing 50% hemolysis of human erythrocytes, >100 g/ml) and its toxicity toward murine peritoneal macrophages (50% inhibitory concentration, >100 g/ml at 24 h). The in vivo toxicity of the new formulation (50% lethal dose, >200 mg/kg of body weight for CD1 mice) was similar to those of other commercial lipid formulations of AMB. The complex was the most effective formulation against the DD8 strain of Leishmania donovani. It was unable to reverse the resistance of an AMBresistant L. donovani strain. In vivo LC-AMB was less efficient than AmBisome against L. donovani.There is a need for a new treatment for patients with visceral leishmaniasis (VL), particularly those with AIDS, since there is a high incidence of relapse after treatment with pentavalent antimonial drugs (11,19,25,32). Despite the recent success with miltefosine as an antileishmanial drug (17, 36), its use is limited because of the risk of the rapid development of resistance if it is used alone (7). The antifungal drug amphotericin B (AMB), a polyene antibiotic, is commonly used to treat leishmaniasis, but its application is limited because of its acute toxicity, which leads to a low therapeutic index when it is used as the traditional formulation, Fungizone (i.e., micelles mixed with the detergent deoxycholate) (18). In order to reduce this dose-limiting toxicity, different commercial lipid-based formulations have been developed and used in the clinical management of VL: AmBisome (4, 10), Abelcet (38, 39), and Amphotec (12). These have also been used as alternative treatments for mucocutaneous leishmaniasis (35,46). In some developed countries, AmBisome is now indicated as the first-line therapy against VL. However, the high prices of these formulations restrict their use in the regions most affected by these tropical diseases (24,15).Recently, several less expensive AMB formulations have been tested. Such formulations include the AMB derivatives prepared and described by Al-Abdely et al. (1) and Golenser et al. (14), which are water soluble and also less toxic. Heat treatment of Fungizone is an inexpensive technique for reduction of its toxicity (31), as is extemporaneous mixing of Fungizone with Intralipid (20, 40). Another particulate formulation with anionic lipids is stable and has good in vitro and in vivo efficacies (26). However, AmBisome remains the most effective formulation for the treatment of VL (46), and none of these formulations has yet been proved to be more active than the commercial ones.The present study was designed to evaluate the antileishmanial activity of a new lipid formulation of AMB in comparison with those of other commercially available lipid-AMB formula...

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Section: Discussionsupporting

confidence: 68%

Toxicity and Antileishmanial Activity of a New StableLipid Suspension of AmphotericinB

Larabi¹,

Yardley²,

Loiseau

et al. 2003

Antimicrob Agents Chemother

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“…The pellet was suspended in TMEP buffer and stored at -80°C till further use. This preparation has been reported to be highly enriched in plasma membrane vesicles [30,31]. …”

Section: Methodsmentioning

confidence: 99%

Role of Efflux Pumps and Intracellular Thiols in Natural Antimony Resistant Isolates of Leishmania donovani

et al. 2013

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BackgroundIn view of the recent upsurge in the phenomenon of therapeutic failure, drug resistance in Leishmania , developed under natural field conditions, has become a great concern yet little understood. Accordingly, the study of determinants of antimony resistance is urgently warranted. Efflux transporters have been reported in Leishmania but their role in clinical resistance is still unknown. The present study was designed to elucidate the mechanism of natural antimony resistance in L. donovani field isolates by analyzing the functionality of efflux pump(s) and expression profiles of known genes involved in transport and thiol based redox metabolismMethodology/Principal FindingsWe selected 7 clinical isolates (2 sensitive and 5 resistant) in addition to laboratory sensitive reference and SbIII resistant mutant strains for the present study. Functional characterization using flow cytometry identified efflux pumps that transported substrates of both P-gp and MRPA and were inhibited by the calmodulin antagonist trifluoperazine. For the first time, verapamil sensitive efflux pumps for rhodamine 123 were observed in L. donovani that were differentially active in resistant isolates. RT-PCR confirmed the over-expression of MRPA in isolates with high resistance index only. Resistant isolates also exhibited consistent down regulation of AQP1 and elevated intracellular thiol levels which were accompanied with increased expression of ODC and TR genes. Interestingly, γ-GCS is not implicated in clinical resistance in L. donovani isolates.Conclusions/SignificanceHere we demonstrate for the first time, the role of P-gp type plasma membrane efflux transporter(s) in antimony resistance in L. donovani field isolates. Further, decreased levels of AQP1 and elevated thiols levels have emerged as biomarkers for clinical resistance.

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“…Membranes vesicles were prepared from promastigotes of L. tarentolae as described previously (7). These ported to contain primarily plasma membrane vesicles free from mitochondrial contamination, although a small amount of endoplasmic reticulum could not be excluded (13,14). Membrane vesicles were rapidly frozen in liquid nitrogen in small aliquots and stored at -80°C until use.…”

mentioning

confidence: 99%

Trypanothione overproduction and resistance to antimonials and arsenicals in Leishmania.

Mukhopadhyay

Dey

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

225

166

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Leishmania resistant to arsenicals and antimonials extrude arsenite. Previous results of arsenite uptake into plasma membrane-enriched vesicles suggested that the transported species is a thiol adduct of arsenite. In this paper, we demonstrate that promastigotes of arsenite-resistant Leishmania tarentolae have increased levels of intracellular thiols. High-pressure liquid chromatography of the total thiols showed that a single peak of material was elevated almost 40-fold. The major species in this peak was identified by matrix-assisted laser desorption/ionization mass spectrometry as N',N5-bis-(glutathionyl)spermidine (trypanothione). The trypanothione adduct of arsenite was effectively transported by the As-thiol pump. No difference in pump activity was observed in wild type and mutants. A model for drug resistance is proposed in which Sb(V)/As(V)-containing compounds, including the antileishmanial drug Pentostam, are reduced intracellularly to Sb(III)/As(III), conjugated to trypanothione, and extruded by the As-thiol pump. The ratelimiting step in resistance is proposed to be formation of the metalloid-thiol pump substrates, so that increased synthesis of trypanothione produces resistance. Increased synthesis of the substrate rather than an increase in the number of pump molecules is a novel mechanism for drug resistance.The trypanosomatid protozoan parasite Leishmania is the causative agent of kala azar and other less severe forms of leishmaniasis (1). Between 10 and 15 million people worldwide have clinical symptoms, and 400,000 new cases are diagnosed each year (2). The treatment of choice for all forms of leishmaniasis depends on Sb(V)-containing drugs such as sodium stibogluconate (Pentostam) and N-methylglucamine (Glucantime). Unresponsiveness to antimonial drugs in mucocutaneous and visceral leishmaniasis has long been recognized and is now becoming a common problem, occurring in 5% of patients. Resistance rates as high as 70% have been described in some endemic areas (3).To serve as models for resistance, strains of Leishmania tarentolae resistant to trivalent arsenicals and antimonials have been generated in vitro. The strains used in this study were branes, suggesting that in vivo it is not free arsenite but rather the thiol adducts that are extruded (7). The Pentostamglutathione complex inhibited 73As(III)-glutathione transport, pointing to a single transport system that is involved in extrusion of and resistance to both arsenite and Pentostam. Based on those results, we suggested that resistance entailed formation of a complex of As(III) or Sb(III) with a thiol that the results in this report show to be N1,N8-bis-(glutathionyl)-spermidine (trypanothione) [T(SH)2], the major reduced thiol of trypanosomatidae (8). The ATP-coupled efflux pump would then extrude the As(III)/Sb(III)-T(S)2 conjugate from the cell. Thus, both conjugation and extrusion would be required for resistance.Although resistant cells accumulate less arsenite than wildtype cells as a result of active extrusion (5), in vi...

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The water and ionic permeability induced by polyene antibiotics across plasma membrane vesicles from Leishmania sp

Cited by 36 publications

References 29 publications

Toxicity and Antileishmanial Activity of a New StableLipid Suspension of AmphotericinB

Toxicity and Antileishmanial Activity of a New StableLipid Suspension of AmphotericinB

Role of Efflux Pumps and Intracellular Thiols in Natural Antimony Resistant Isolates of Leishmania donovani

Trypanothione overproduction and resistance to antimonials and arsenicals in Leishmania.

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