title: Implications of Glutathione Levels in the Plasmodium berghei Response to Chloroquine and Artemisinin.
abstract: Malaria is one of the most devastating parasitic diseases worldwide. Plasmodium drug resistance remains a major challenge to malaria control and has led to the re-emergence of the disease. Chloroquine (CQ) and artemisinin (ART) are thought to exert their anti-malarial activity inducing cytotoxicity in the parasite by blocking heme degradation (for CQ) and increasing oxidative stress. Besides the contribution of the CQ resistance transporter (PfCRT) and the multidrug resistant gene (pfmdr), CQ resistance has also been associated with increased parasite glutathione (GSH) levels. ART resistance was recently shown to be associated with mutations in the K13-propeller protein. To analyze the role of GSH levels in CQ and ART resistance, we generated transgenic Plasmodium berghei parasites either deficient in or overexpressing the gamma-glutamylcysteine synthetase gene (pbggcs) encoding the rate-limiting enzyme in GSH biosynthesis. These lines produce either lower (pbggcs-ko) or higher (pbggcs-oe) levels of GSH than wild type parasites. In addition, GSH levels were determined in P. berghei parasites resistant to CQ and mefloquine (MQ). Increased GSH levels were detected in both, CQ and MQ resistant parasites, when compared to the parental sensitive clone. Sensitivity to CQ and ART remained unaltered in both pgggcs-ko and pbggcs-oe parasites when tested in a 4 days drug suppressive assay. However, recrudescence assays after the parasites have been exposed to a sub-lethal dose of ART showed that parasites with low levels of GSH are more sensitive to ART treatment. These results suggest that GSH levels influence Plasmodium berghei response to ART treatment.
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico.
authors.forename: Joel
authors.initials: J
authors.lastname: Vega-Rodríguez
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Pastrana-Mena
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico.
authors.forename: Keila N
authors.initials: KN
authors.lastname: Crespo-Lladó
authors.affiliation: Department of Pharmacology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico.
authors.forename: José G
authors.initials: JG
authors.lastname: Ortiz
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico.
authors.forename: Iván
authors.initials: I
authors.lastname: Ferrer-Rodríguez
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico.
authors.forename: Adelfa E
authors.initials: AE
authors.lastname: Serrano
mesh_terms: D000818:Animals; D037621:Artemisinins / Q000494:pharmacology*; D002738:Chloroquine / Q000494:pharmacology*; D004351:Drug Resistance / Q000187:drug effects*; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D008288:Malaria / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D010962:Plasmodium berghei / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism
chemical_list: D037621:Artemisinins; D015800:Protozoan Proteins; D002738:Chloroquine; C031327:artemisinin; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione