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Antimonial-mediated DNA fragmentation in Leishmania infantum amastigotes
D Sereno1, P Holzmuller, I Mangot
1Laboratoire de Biologie Parasitaire, Centre IRD (Institut de Recherche pour le Développement), 34032 Montpellier Cedex 1, France.
Abstract:
The basic treatment of leishmaniasis consists in the administration of pentavalent antimonials. The mechanisms that contribute to pentavalent antimonial toxicity against the intracellular stage of the parasite (i.e., amastigote) are still unknown. In this study, the combined use of several techniques including DNA fragmentation assay and in situ and cytofluorometry terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling methods and YOPRO-1 staining allowed us to demonstrate that potassium antimonyl tartrate, an Sb(III)-containing drug, was able to induce cell death associated with DNA fragmentation in axenic amastigotes of Leishmania infantum at low concentrations (10 microg/ml). This observation was in close correlation with the toxicity of Sb(III) species against axenic amastigotes (50% inhibitory concentration of 4.75 microg/ml). Despite some similarities to apoptosis, nuclease activation was not a consequence of caspase-1, caspase-3, calpain, cysteine protease, or proteasome activation. Altogether, our results demonstrate that the antileishmanial toxicity of Sb(III) antimonials is associated with parasite oligonucleosomal DNA fragmentation, indicative of the occurrence of late events in the overall process of apoptosis. The elucidation of the biochemical pathways leading to cell death could allow the isolation of new therapeutic targets.
Insights
Pentavalent antimonials, a key leishmaniasis treatment, induce parasite cell death via DNA fragmentation. This study reveals Sb(III) antimonials trigger programmed cell death in Leishmania infantum amastigotes, offering new therapeutic targets.
Area of Science:
- Parasitology
- Molecular Biology
- Pharmacology
Background:
- Pentavalent antimonials are the primary treatment for leishmaniasis.
- The precise mechanisms of antimonial toxicity against Leishmania parasites remain unclear.
- Understanding these mechanisms is crucial for developing improved therapeutic strategies.
Purpose of the Study:
- To investigate the mechanisms of toxicity of Sb(III) antimonials against Leishmania infantum amastigotes.
- To determine if Sb(III) induces DNA fragmentation and cell death in the parasite.
- To explore the relationship between antimonial toxicity and apoptotic pathways.
Main Methods:
- Utilized DNA fragmentation assays, including terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL).
- Employed YOPRO-1 staining and cytofluorometry for cell death analysis.
- Assessed the involvement of caspases, calpains, cysteine proteases, and proteasomes.
Main Results:
- Potassium antimonyl tartrate induced significant DNA fragmentation and cell death in Leishmania infantum axenic amastigotes at low concentrations (10 microg/ml).
- The toxicity of Sb(III) species correlated with observed cell death (50% inhibitory concentration of 4.75 microg/ml).
- Nuclease activation and DNA fragmentation occurred independently of caspase, calpain, cysteine protease, or proteasome activation.
Conclusions:
- Sb(III) antimonials exert their leishmanicidal effect through parasite oligonucleosomal DNA fragmentation.
- This DNA fragmentation represents a late event in the cell death process, resembling apoptosis.
- Elucidating these pathways may identify novel therapeutic targets for leishmaniasis treatment.