Antimony Uptake Systems in the Protozoan Parasite
            <i>Leishmania</i>
            and Accumulation Differences in Antimony-Resistant Parasites

Brochu, Christian; Wang, Jingyu; Roy, Gaétan; Messier, Nadine; Wang, Xiaoyan; Saravia, Nancy Gore; Ouellette, Marc

doi:10.1128/aac.47.10.3073-3079.2003

Cited by 126 publications

(101 citation statements)

References 36 publications

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“…The role of ABC transporters in resistance to different compounds has been studied previously (5,(19)(20)(21). As mentioned above, the Leishmania LABCG2 transporter is involved in the PS externalization required for macrophage infection (10).…”

Section: Resultsmentioning

confidence: 99%

“…Promastigotes (10 8 /ml) were incubated at 28°C with 100 M Sb III in RPMI 1640 culture medium at 28°C for different times. The parasites were centrifuged and pelleted to measure antimony accumulation after each time period (19). Antimony efflux was determined by incubating the different promastigote lines with compensated Sb III concentrations (100 M for the pUCNEO line and 200 M for the LABCG2 line) for 1 h at 28°C in culture medium in order to attain similar labeling in Leishmania lines.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

The LABCG2 Transporter from the Protozoan Parasite Leishmania Is Involved in Antimony Resistance

Perea

Manzano

Castanys

et al. 2016

Antimicrob Agents Chemother

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Treatment for leishmaniasis, which is caused by Leishmania protozoan parasites, currently relies on a reduced arsenal of drugs. However, the significant increase in the incidence of drug therapeutic failure and the growing resistance to first-line drugs like antimonials in some areas of Northern India and Nepal limit the control of this parasitic disease. Understanding the molecular mechanisms of resistance in Leishmania is now a matter of urgency to optimize drugs used and to identify novel drug targets to block or reverse resistant mechanisms. Some members of the family of ATP-binding cassette (ABC) transporters in Leishmania have been associated with drug resistance. In this study, we have focused our interest to characterize LABCG2's involvement in drug resistance in Leishmania. Leishmania major parasites overexpressing the ABC protein transporter LABCG2 were generated in order to assess how LABCG2 is involved in drug resistance. Assays of susceptibility to different leishmanicidal agents were carried out. Analysis of the drug resistance profile revealed that Leishmania parasites overexpressing LABCG2 were resistant to antimony, as they demonstrated a reduced accumulation of Sb III due to an increase in drug efflux. Additionally, LABCG2 was able to transport thiols in the presence of Sb III . Biotinylation assays using parasites expressing LABCG2 fused with an N-terminal green fluorescent protein tag revealed that LABCG2 is partially localized in the plasma membrane; this supports data from previous studies which suggested that LABCG2 is localized in intracellular vesicles that fuse with the plasma membrane during exocytosis. In conclusion, Leishmania LABCG2 probably confers antimony resistance by sequestering metal-thiol conjugates within vesicles and through further exocytosis by means of the parasite's flagellar pocket.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The LABCG2 Transporter from the Protozoan Parasite Leishmania Is Involved in Antimony Resistance

Perea

Manzano

Castanys

et al. 2016

Antimicrob Agents Chemother

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“…It is not known whether this mechanism occurs in clinical isolates at present. The accumulation of Sb(V) and Sb(III) in promastigotes and amastigotes has been shown to be by different transport systems (22), and although Sb accumulation was lower in resistant forms than in sensitive forms, levels of accumulation could not be correlated to sensitivity in wild-type cells. Aquaglycoporins have recently been demonstrated to mediate uptake of Sb(III) in Leishmania spp.…”

Section: Antimonialsmentioning

confidence: 98%

“…Thus, it is difficult to account for the selective action of Sb(V) against the amastigote stage by a nonenzymatic mechanism. As both stages can take up Sb(III) and Sb(V) the insensitivity of promastigotes to Sb(V) cannot be attributed to drug exclusion (22).…”

Section: Antimonialsmentioning

confidence: 99%

Drug Resistance in Leishmaniasis

2006

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SUMMARY Leishmaniasis is a complex disease, with visceral and cutaneous manifestations, and is caused by over 15 different species of the protozoan parasite genus Leishmania. There are significant differences in the sensitivity of these species both to the standard drugs, for example, pentavalent antimonials and miltefosine, and those on clinical trial, for example, paromomycin. Over 60% of patients with visceral leishmaniasis in Bihar State, India, do not respond to treatment with pentavalent antimonials. This is now considered to be due to acquired resistance. Although this class of drugs has been used for over 60 years for leishmaniasis treatment, it is only in the past 2 years that the mechanisms of action and resistance have been identified, related to drug metabolism, thiol metabolism, and drug efflux. With the introduction of new therapies, including miltefosine in 2002 and paromomycin in 2005-2006, it is essential that there be a strategy to prevent the emergence of resistance to new drugs; combination therapy, monitoring of therapy, and improved diagnostics could play an essential role in this strategy.

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“…However, the physiological relevance of this observation is questionable because promastigotes contain higher intracellular concentrations of T[SH] 2 and GSH than amastigotes (Fig. 4), both stages maintain intracellular pH values close to neutral and independent of external pH (30), and both stages can take up Sb III and Sb V (37). A recently identified thiol-dependent reductase (TDR1) that is more highly expressed in amastigotes has been postulated to play a role (8).…”

Section: Effects Of Pentavalent Antimony On the Thiol Metabolism Of Lmentioning

confidence: 99%

Dual Action of Antimonial Drugs on Thiol Redox Metabolism in the Human Pathogen Leishmania donovani

Wyllie

Cunningham

Fairlamb

2004

Journal of Biological Chemistry

264

242

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Despite extensive use of antimonial compounds in the treatment of leishmaniasis, their mode of action remains uncertain. Here we show that trivalent antimony (Sb III ) interferes with trypanothione metabolism in drug-sensitive Leishmania parasites by two inherently distinct mechanisms. First, Sb III decreases thiol buffering capacity by inducing rapid efflux of intracellular trypanothione and glutathione in approximately equimolar amounts. Second, Sb III inhibits trypanothione reductase in intact cells resulting in accumulation of the disulfide forms of trypanothione and glutathione. These two mechanisms combine to profoundly compromise the thiol redox potential in both amastigote and promastigote stages of the life cycle. Furthermore, we demonstrate that sodium stibogluconate, a pentavalent antimonial used clinically for the treatment for leishmaniasis, induces similar effects on thiol redox metabolism in axenically cultured amastigotes. These observations suggest ways in which current antimony therapies could be improved, overcoming the growing problem of antimony resistance.Leishmania parasites cause a wide spectrum of human and animal infections ranging from life-threatening visceral disease to disfiguring mucosal and cutaneous forms of the disease. These "neglected" diseases are a significant cause of morbidity and mortality in 88 countries in the Americas, Africa, Asia, and Southern Europe; millions of people are at risk, and 400,000 new cases are reported annually (1). Leishmania spp. are obligate intracellular parasites of the vertebrate reticuloendothelial system, where they multiply as amastigotes in macrophage phagolysosomes; transmission is by blood-sucking sandflies, in which they proliferate as extracellular promastigotes. Treatment of the leishmaniases is far from ideal, and pentavalent antimonial (Sb V ) 1 preparations such as sodium stibogluconate (Pentostam) have been the front-line drugs for more than half a century. However, the clinical value of antimony therapy is now threatened because of the emergence of drug resistance (2) and co-infection with human immunodeficiency virus (3). Sb V is generally regarded as a pro-drug that first has to be activated by conversion to the trivalent form (Sb III ) (4). However, the site of reduction (host macrophage, amastigote, or both) and the mechanism of reduction (enzymatic or nonenzymatic) remain unclear (4 -8). The mode of action of these drugs is poorly understood. Sb III reversibly inhibits trypanothione reductase in vitro (9), but this has not been demonstrated in the intact parasite. However, inhibition of this unique and essential enzyme (10 -12) is of particular interest, because trypanothione (N 1 ,N 8Ϫ bis(glutathionyl) spermidine (T[SH] 2 )) is a key intermediate in the regulation of thiol redox homeostasis, as well as in defense against chemical (13,14) and oxidative stress (15, 16).Paradoxically, more is known about the mechanism of resistance to Sb III than its mode of action (17). A considerable body of evidence implicates trypanothione a...

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Antimony Uptake Systems in the Protozoan Parasite Leishmania and Accumulation Differences in Antimony-Resistant Parasites

Cited by 126 publications

References 36 publications

The LABCG2 Transporter from the Protozoan Parasite Leishmania Is Involved in Antimony Resistance

The LABCG2 Transporter from the Protozoan Parasite Leishmania Is Involved in Antimony Resistance

Drug Resistance in Leishmaniasis

Dual Action of Antimonial Drugs on Thiol Redox Metabolism in the Human Pathogen Leishmania donovani

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