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1.
N Engl J Med ; 389(13): 1191-1202, 2023 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-37754284

RESUMO

BACKGROUND: Although the clinical efficacy of antimalarial artemisinin-based combination therapies in Africa remains high, the recent emergence of partial resistance to artemisinin in Plasmodium falciparum on the continent is troubling, given the lack of alternative treatments. METHODS: In this study, we used data from drug-efficacy studies conducted between 2016 and 2019 that evaluated 3-day courses of artemisinin-based combination therapy (artesunate-amodiaquine or artemether-lumefantrine) for uncomplicated malaria in Eritrea to estimate the percentage of patients with day-3 positivity (i.e., persistent P. falciparum parasitemia 3 days after the initiation of therapy). We also assayed parasites for mutations in Pfkelch13 as predictive markers of partial resistance to artemisinin and screened for deletions in hrp2 and hrp3 that result in variable performance of histidine rich protein 2 (HRP2)-based rapid diagnostic tests for malaria. RESULTS: We noted an increase in the percentage of patients with day-3 positivity from 0.4% (1 of 273) in 2016 to 1.9% (4 of 209) in 2017 and 4.2% (15 of 359) in 2019. An increase was also noted in the prevalence of the Pfkelch13 R622I mutation, which was detected in 109 of 818 isolates before treatment, from 8.6% (24 of 278) in 2016 to 21.0% (69 of 329) in 2019. The odds of day-3 positivity increased by a factor of 6.2 (95% confidence interval, 2.5 to 15.5) among the patients with Pfkelch13 622I variant parasites. Partial resistance to artemisinin, as defined by the World Health Organization, was observed in Eritrea. More than 5% of the patients younger than 15 years of age with day-3 positivity also had parasites that carried Pfkelch13 R622I. In vitro, the R622I mutation conferred a low level of resistance to artemisinin when edited into NF54 and Dd2 parasite lines. Deletions in both hrp2 and hrp3 were identified in 16.9% of the parasites that carried the Pfkelch13 R622I mutation, which made them potentially undetectable by HRP2-based rapid diagnostic tests. CONCLUSIONS: The emergence and spread of P. falciparum lineages with both Pfkelch13-mediated partial resistance to artemisinin and deletions in hrp2 and hrp3 in Eritrea threaten to compromise regional malaria control and elimination campaigns. (Funded by the Bill and Melinda Gates Foundation and others; Australian New Zealand Clinical Trials Registry numbers, ACTRN12618001223224, ACTRN12618000353291, and ACTRN12619000859189.).


Assuntos
Antimaláricos , Combinação Arteméter e Lumefantrina , Resistência a Medicamentos , Malária Falciparum , Plasmodium falciparum , Humanos , Amodiaquina/administração & dosagem , Amodiaquina/farmacologia , Amodiaquina/uso terapêutico , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Combinação Arteméter e Lumefantrina/farmacologia , Combinação Arteméter e Lumefantrina/uso terapêutico , Artemisininas/administração & dosagem , Artemisininas/farmacologia , Artemisininas/uso terapêutico , Resistência a Medicamentos/genética , Eritreia/epidemiologia , Malária Falciparum/tratamento farmacológico , Malária Falciparum/epidemiologia , Malária Falciparum/genética , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Prevalência
2.
Antimicrob Agents Chemother ; 66(1): e0132021, 2022 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-34606334

RESUMO

Partial artemisinin resistance, defined in patients as a delayed parasite clearance following artemisinin-based treatment, is conferred by non-synonymous mutations in the Kelch beta-propeller domain of the Plasmodium falciparum k13 (pfk13) gene. Here, we carried out in vitro selection over a 1-year period on a West African P. falciparum strain isolated from Kolle (Mali) under a dose-escalating artemisinin regimen. After 18 cycles of sequential drug pressure, the selected parasites exhibited enhanced survival to dihydroartemisinin in the ring-stage survival assay (RSA0-3h = 9.2%). Sanger and whole-genome sequence analyses identified the PfK13 P413A mutation, localized in the BTB/POZ domain, upstream of the propeller domain. This mutation was sufficient to confer in vitro artemisinin resistance when introduced into the PfK13 coding sequence of the parasite strain Dd2 by CRISPR/Cas9 gene editing. These results together with structural studies of the protein demonstrate that the propeller domain is not the sole in vitro mediator of PfK13-mediated artemisinin resistance, and highlight the importance of monitoring for mutations throughout PfK13.


Assuntos
Antimaláricos , Artemisininas , Domínio BTB-POZ , Proteínas de Protozoários , Antimaláricos/farmacologia , Artemisininas/farmacologia , Resistência a Medicamentos/genética , Mutação , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Proteínas de Protozoários/genética
3.
PLoS Pathog ; 16(4): e1008482, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32310999

RESUMO

The emergence of artemisinin (ART) resistance in Plasmodium falciparum intra-erythrocytic parasites has led to increasing treatment failure rates with first-line ART-based combination therapies in Southeast Asia. Decreased parasite susceptibility is caused by K13 mutations, which are associated clinically with delayed parasite clearance in patients and in vitro with an enhanced ability of ring-stage parasites to survive brief exposure to the active ART metabolite dihydroartemisinin. Herein, we describe a panel of K13-specific monoclonal antibodies and gene-edited parasite lines co-expressing epitope-tagged versions of K13 in trans. By applying an analytical quantitative imaging pipeline, we localize K13 to the parasite endoplasmic reticulum, Rab-positive vesicles, and sites adjacent to cytostomes. These latter structures form at the parasite plasma membrane and traffic hemoglobin to the digestive vacuole wherein artemisinin-activating heme moieties are released. We also provide evidence of K13 partially localizing near the parasite mitochondria upon treatment with dihydroartemisinin. Immunoprecipitation data generated with K13-specific monoclonal antibodies identify multiple putative K13-associated proteins, including endoplasmic reticulum-resident molecules, mitochondrial proteins, and Rab GTPases, in both K13 mutant and wild-type isogenic lines. We also find that mutant K13-mediated resistance is reversed upon co-expression of wild-type or mutant K13. These data help define the biological properties of K13 and its role in mediating P. falciparum resistance to ART treatment.


Assuntos
Resistência a Medicamentos/genética , Plasmodium falciparum/genética , Antimaláricos/farmacologia , Artemisininas/farmacologia , Resistência a Medicamentos/fisiologia , Humanos , Malária Falciparum/parasitologia , Mutação , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo
4.
PLoS Pathog ; 15(6): e1007722, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31170268

RESUMO

Therapeutics with novel modes of action and a low risk of generating resistance are urgently needed to combat drug-resistant Plasmodium falciparum malaria. Here, we report that the peptide vinyl sulfones WLL-vs (WLL) and WLW-vs (WLW), highly selective covalent inhibitors of the P. falciparum proteasome, potently eliminate genetically diverse parasites, including K13-mutant, artemisinin-resistant lines, and are particularly active against ring-stage parasites. Selection studies reveal that parasites do not readily acquire resistance to WLL or WLW and that mutations in the ß2, ß5 or ß6 subunits of the 20S proteasome core particle or in components of the 19S proteasome regulatory particle yield only hundred-fold decreases in susceptibility. We observed no cross-resistance between WLL and WLW. Moreover, most mutations that conferred a modest loss of parasite susceptibility to one inhibitor significantly increased sensitivity to the other. These inhibitors potently synergized multiple chemically diverse classes of antimalarial agents, implicating a shared disruption of proteostasis in their modes of action. These results underscore the potential of targeting the Plasmodium proteasome with covalent small molecule inhibitors as a means of combating multidrug-resistant malaria.


Assuntos
Antimaláricos/farmacologia , Resistência a Medicamentos/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma/farmacologia , Proteínas de Protozoários , Antimaláricos/química , Resistência a Medicamentos/genética , Sinergismo Farmacológico , Humanos , Plasmodium falciparum/genética , Inibidores de Proteassoma/química , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo
6.
J Am Chem Soc ; 140(36): 11424-11437, 2018 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-30107725

RESUMO

The Plasmodium proteasome is an emerging antimalarial target due to its essential role in all the major life cycle stages of the parasite and its contribution to the establishment of resistance to artemisinin (ART)-based therapies. However, because of a similarly essential role for the host proteasome, the key property of any antiproteasome therapeutic is selectivity. Several parasite-specific proteasome inhibitors have recently been reported, however, their selectivity must be improved to enable clinical development. Here we describe screening of diverse libraries of non-natural synthetic fluorogenic substrates to identify determinants at multiple positions on the substrate that produce enhanced selectivity. We find that selection of an optimal electrophilic "warhead" is essential to enable high selectivity that is driven by the peptide binding elements on the inhibitor. We also find that host cell toxicity is dictated by the extent of coinhibition of the human ß2 and ß5 subunits. Using this information, we identify compounds with over 3 orders of magnitude selectivity for the parasite enzyme. Optimization of the pharmacological properties resulted in molecules that retained high potency and selectivity, were soluble, sufficiently metabolically stable and orally bioavailable. These molecules are highly synergistic with ART and can clear parasites in a mouse model of infection, making them promising leads as antimalarial drugs.


Assuntos
Artemisininas/farmacologia , Plasmodium falciparum/enzimologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma/farmacologia , Artemisininas/química , Relação Dose-Resposta a Droga , Estrutura Molecular , Inibidores de Proteassoma/química , Relação Estrutura-Atividade
7.
Microbiol Spectr ; 11(6): e0397622, 2023 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-37800971

RESUMO

IMPORTANCE: In malaria drug discovery, understanding the mode of action of lead compounds is important as it helps in predicting the potential emergence of drug resistance in the field when these drugs are eventually deployed. In this study, we have employed metabolomics technologies to characterize the potential targets of anti-malarial drug candidates in the developmental pipeline at NITD. We show that NITD fast-acting leads belonging to spiroindolone and imidazothiadiazole class induce a common biochemical theme in drug-exposed malaria parasites which is similar to another fast-acting, clinically available drug, DHA. These biochemical features which are absent in a slower acting NITD lead (GNF17) point to hemoglobin digestion and inhibition of the pyrimidine pathway as potential action points for these drugs. These biochemical themes can be used to identify and inform on the mode of action of fast drug candidates of similar profiles in future drug discovery programs.


Assuntos
Antimaláricos , Malária Falciparum , Malária , Humanos , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Plasmodium falciparum , Descoberta de Drogas , Malária Falciparum/tratamento farmacológico , Resistência a Medicamentos
8.
Cell Chem Biol ; 30(5): 470-485.e6, 2023 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-36963402

RESUMO

The Plasmodium falciparum proteasome constitutes a promising antimalarial target, with multiple chemotypes potently and selectively inhibiting parasite proliferation and synergizing with the first-line artemisinin drugs, including against artemisinin-resistant parasites. We compared resistance profiles of vinyl sulfone, epoxyketone, macrocyclic peptide, and asparagine ethylenediamine inhibitors and report that the vinyl sulfones were potent even against mutant parasites resistant to other proteasome inhibitors and did not readily select for resistance, particularly WLL that displays covalent and irreversible binding to the catalytic ß2 and ß5 proteasome subunits. We also observed instances of collateral hypersensitivity, whereby resistance to one inhibitor could sensitize parasites to distinct chemotypes. Proteasome selectivity was confirmed using CRISPR/Cas9-edited mutant and conditional knockdown parasites. Molecular modeling of proteasome mutations suggested spatial contraction of the ß5 P1 binding pocket, compromising compound binding. Dual targeting of P. falciparum proteasome subunits using covalent inhibitors provides a potential strategy for restoring artemisinin activity and combating the spread of drug-resistant malaria.


Assuntos
Antimaláricos , Artemisininas , Malária Falciparum , Plasmodium , Humanos , Antimaláricos/farmacologia , Antimaláricos/química , Complexo de Endopeptidases do Proteassoma/metabolismo , Plasmodium/metabolismo , Artemisininas/química , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Inibidores de Proteassoma/farmacologia , Inibidores de Proteassoma/química
9.
Nat Commun ; 13(1): 5746, 2022 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-36180431

RESUMO

Diverse compounds target the Plasmodium falciparum Na+ pump PfATP4, with cipargamin and (+)-SJ733 the most clinically-advanced. In a recent clinical trial for cipargamin, recrudescent parasites emerged, with most having a G358S mutation in PfATP4. Here, we show that PfATP4G358S parasites can withstand micromolar concentrations of cipargamin and (+)-SJ733, while remaining susceptible to antimalarials that do not target PfATP4. The G358S mutation in PfATP4, and the equivalent mutation in Toxoplasma gondii ATP4, decrease the sensitivity of ATP4 to inhibition by cipargamin and (+)-SJ733, thereby protecting parasites from disruption of Na+ regulation. The G358S mutation reduces the affinity of PfATP4 for Na+ and is associated with an increase in the parasite's resting cytosolic [Na+]. However, no defect in parasite growth or transmissibility is observed. Our findings suggest that PfATP4 inhibitors in clinical development should be tested against PfATP4G358S parasites, and that their combination with unrelated antimalarials may mitigate against resistance development.


Assuntos
Antimaláricos , Malária Falciparum , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , ATPases Transportadoras de Cálcio , Eritrócitos/parasitologia , Humanos , Indóis , Íons , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Mutação , Plasmodium falciparum , Sódio , Compostos de Espiro
10.
Nat Commun ; 12(1): 530, 2021 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-33483501

RESUMO

The emergence and spread of artemisinin resistance, driven by mutations in Plasmodium falciparum K13, has compromised antimalarial efficacy and threatens the global malaria elimination campaign. By applying systems-based quantitative transcriptomics, proteomics, and metabolomics to a panel of isogenic K13 mutant or wild-type P. falciparum lines, we provide evidence that K13 mutations alter multiple aspects of the parasite's intra-erythrocytic developmental program. These changes impact cell-cycle periodicity, the unfolded protein response, protein degradation, vesicular trafficking, and mitochondrial metabolism. K13-mediated artemisinin resistance in the Cambodian Cam3.II line was reversed by atovaquone, a mitochondrial electron transport chain inhibitor. These results suggest that mitochondrial processes including damage sensing and anti-oxidant properties might augment the ability of mutant K13 to protect P. falciparum against artemisinin action by helping these parasites undergo temporary quiescence and accelerated growth recovery post drug elimination.


Assuntos
Artemisininas/farmacologia , Resistência a Medicamentos/genética , Eritrócitos/metabolismo , Mutação , Plasmodium falciparum/genética , Antimaláricos/farmacologia , Atovaquona/farmacologia , Pontos de Checagem do Ciclo Celular/genética , Eritrócitos/parasitologia , Perfilação da Expressão Gênica/métodos , Humanos , Metabolômica/métodos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Modelos Genéticos , Plasmodium falciparum/metabolismo , Plasmodium falciparum/fisiologia , Proteômica/métodos , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo
11.
Elife ; 102021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-34279219

RESUMO

The emergence of mutant K13-mediated artemisinin (ART) resistance in Plasmodium falciparum malaria parasites has led to widespread treatment failures across Southeast Asia. In Africa, K13-propeller genotyping confirms the emergence of the R561H mutation in Rwanda and highlights the continuing dominance of wild-type K13 elsewhere. Using gene editing, we show that R561H, along with C580Y and M579I, confer elevated in vitro ART resistance in some African strains, contrasting with minimal changes in ART susceptibility in others. C580Y and M579I cause substantial fitness costs, which may slow their dissemination in high-transmission settings, in contrast with R561H that in African 3D7 parasites is fitness neutral. In Cambodia, K13 genotyping highlights the increasing spatio-temporal dominance of C580Y. Editing multiple K13 mutations into a panel of Southeast Asian strains reveals that only the R561H variant yields ART resistance comparable to C580Y. In Asian Dd2 parasites C580Y shows no fitness cost, in contrast with most other K13 mutations tested, including R561H. Editing of point mutations in ferredoxin or mdr2, earlier associated with resistance, has no impact on ART susceptibility or parasite fitness. These data underline the complex interplay between K13 mutations, parasite survival, growth and genetic background in contributing to the spread of ART resistance.


Assuntos
Artemisininas/farmacologia , Resistência a Medicamentos/efeitos dos fármacos , Resistência a Medicamentos/genética , Mutação , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , África , Antimaláricos/farmacologia , Ásia , Camboja , Humanos , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Epidemiologia Molecular
12.
mBio ; 11(6)2020 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-33173001

RESUMO

The recent emergence of Plasmodium falciparum parasite resistance to the first line antimalarial drug artemisinin is of particular concern. Artemisinin resistance is primarily driven by mutations in the P. falciparum K13 protein, which enhance survival of early ring-stage parasites treated with the artemisinin active metabolite dihydroartemisinin in vitro and associate with delayed parasite clearance in vivo However, association of K13 mutations with in vivo artemisinin resistance has been problematic due to the absence of a tractable model. Herein, we have employed CRISPR/Cas9 genome editing to engineer selected orthologous P. falciparum K13 mutations into the K13 gene of an artemisinin-sensitive Plasmodium berghei rodent model of malaria. Introduction of the orthologous P. falciparum K13 F446I, M476I, Y493H, and R539T mutations into P. berghei K13 yielded gene-edited parasites with reduced susceptibility to dihydroartemisinin in the standard 24-h in vitro assay and increased survival in an adapted in vitro ring-stage survival assay. Mutant P. berghei K13 parasites also displayed delayed clearance in vivo upon treatment with artesunate and achieved faster recrudescence upon treatment with artemisinin. Orthologous C580Y and I543T mutations could not be introduced into P. berghei, while the equivalents of the M476I and R539T mutations resulted in significant growth defects. Furthermore, a Plasmodium-selective proteasome inhibitor strongly synergized dihydroartemisinin action in these P. berghei K13 mutant lines, providing further evidence that the proteasome can be targeted to overcome artemisinin resistance. Taken together, our findings provide clear experimental evidence for the involvement of K13 polymorphisms in mediating susceptibility to artemisinins in vitro and, most importantly, under in vivo conditions.IMPORTANCE Recent successes in malaria control have been seriously threatened by the emergence of Plasmodium falciparum parasite resistance to the frontline artemisinin drugs in Southeast Asia. P. falciparum artemisinin resistance is associated with mutations in the parasite K13 protein, which associates with a delay in the time required to clear the parasites upon drug treatment. Gene editing technologies have been used to validate the role of several candidate K13 mutations in mediating P. falciparum artemisinin resistance in vitro under laboratory conditions. Nonetheless, the causal role of these mutations under in vivo conditions has been a matter of debate. Here, we have used CRISPR/Cas9 gene editing to introduce K13 mutations associated with artemisinin resistance into the related rodent-infecting parasite, Plasmodium berghei Phenotyping of these P. berghei K13 mutant parasites provides evidence of their role in mediating artemisinin resistance in vivo, which supports in vitro artemisinin resistance observations. However, we were unable to introduce some of the P. falciparum K13 mutations (C580Y and I543T) into the corresponding amino acid residues, while other introduced mutations (M476I and R539T equivalents) carried pronounced fitness costs. Our study provides evidence of a clear causal role of K13 mutations in modulating susceptibility to artemisinins in vitro and in vivo using the well-characterized P. berghei model. We also show that inhibition of the P. berghei proteasome offsets parasite resistance to artemisinins in these mutant lines.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Resistência a Medicamentos , Malária/parasitologia , Plasmodium berghei/efeitos dos fármacos , Plasmodium berghei/genética , Inibidores de Proteassoma/farmacologia , Proteínas de Protozoários/genética , Animais , Feminino , Humanos , Malária/tratamento farmacológico , Camundongos , Mutação/efeitos dos fármacos , Plasmodium berghei/crescimento & desenvolvimento , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Complexo de Endopeptidases do Proteassoma/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas de Protozoários/metabolismo
13.
Nat Med ; 26(10): 1602-1608, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32747827

RESUMO

Artemisinin resistance (delayed P. falciparum clearance following artemisinin-based combination therapy), is widespread across Southeast Asia but to date has not been reported in Africa1-4. Here we genotyped the P. falciparum K13 (Pfkelch13) propeller domain, mutations in which can mediate artemisinin resistance5,6, in pretreatment samples collected from recent dihydroarteminisin-piperaquine and artemether-lumefantrine efficacy trials in Rwanda7. While cure rates were >95% in both treatment arms, the Pfkelch13 R561H mutation was identified in 19 of 257 (7.4%) patients at Masaka. Phylogenetic analysis revealed the expansion of an indigenous R561H lineage. Gene editing confirmed that this mutation can drive artemisinin resistance in vitro. This study provides evidence for the de novo emergence of Pfkelch13-mediated artemisinin resistance in Rwanda, potentially compromising the continued success of antimalarial chemotherapy in Africa.


Assuntos
Antimaláricos/uso terapêutico , Artemisininas/uso terapêutico , Resistência a Medicamentos/genética , Malária Falciparum/parasitologia , Mutação de Sentido Incorreto , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Substituição de Aminoácidos/genética , Animais , Arginina/genética , Evolução Clonal/genética , Doenças Transmissíveis Emergentes/tratamento farmacológico , Doenças Transmissíveis Emergentes/epidemiologia , Doenças Transmissíveis Emergentes/parasitologia , Genótipo , Histidina/genética , Humanos , Técnicas In Vitro , Repetição Kelch/genética , Malária Falciparum/tratamento farmacológico , Malária Falciparum/epidemiologia , Testes de Sensibilidade Parasitária , Filogenia , Plasmodium falciparum/efeitos dos fármacos , Polimorfismo Genético , Proteínas de Protozoários/química , Ruanda/epidemiologia
14.
Cell Chem Biol ; 27(2): 143-157.e5, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-31978322

RESUMO

Salinipostin A (Sal A) is a potent antiplasmodial marine natural product with an undefined mechanism of action. Using a Sal A-derived activity-based probe, we identify its targets in the Plasmodium falciparum parasite. All of the identified proteins contain α/ß serine hydrolase domains and several are essential for parasite growth. One of the essential targets displays a high degree of homology to human monoacylglycerol lipase (MAGL) and is able to process lipid esters including a MAGL acylglyceride substrate. This Sal A target is inhibited by the anti-obesity drug Orlistat, which disrupts lipid metabolism. Resistance selections yielded parasites that showed only minor reductions in sensitivity and that acquired mutations in a PRELI domain-containing protein linked to drug resistance in Toxoplasma gondii. This inability to evolve efficient resistance mechanisms combined with the non-essentiality of human homologs makes the serine hydrolases identified here promising antimalarial targets.


Assuntos
Antimaláricos/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/química , Hidrolases/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Proteínas de Protozoários/metabolismo , Antimaláricos/química , Antimaláricos/metabolismo , Antimaláricos/uso terapêutico , Produtos Biológicos/síntese química , Produtos Biológicos/farmacologia , Produtos Biológicos/uso terapêutico , Compostos Bicíclicos Heterocíclicos com Pontes/metabolismo , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/uso terapêutico , Química Click , Resistência a Medicamentos/efeitos dos fármacos , Humanos , Hidrolases/antagonistas & inibidores , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Malária Falciparum/patologia , Monoacilglicerol Lipases/antagonistas & inibidores , Monoacilglicerol Lipases/genética , Monoacilglicerol Lipases/metabolismo , Orlistate/química , Orlistate/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/genética
15.
mBio ; 8(2)2017 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-28400526

RESUMO

The emergence and spread in Southeast Asia of Plasmodium falciparum resistance to artemisinin (ART) derivatives, the cornerstone of first-line artemisinin-based combination therapies (ACTs), underscore the urgent need to identify suitable replacement drugs. Discovery and development efforts have identified a series of ozonides with attractive chemical and pharmacological properties that are being touted as suitable replacements. Partial resistance to ART, defined as delayed parasite clearance in malaria patients treated with an ART derivative or an ACT, has been associated with mutations in the P. falciparum K13 gene. In light of reports showing that ART derivatives and ozonides share similar modes of action, we have investigated whether parasites expressing mutant K13 are cross-resistant to the ozonides OZ439 (artefenomel) and OZ227 (arterolane). This work used a panel of culture-adapted clinical isolates from Cambodia that were genetically edited to express variant forms of K13. Phenotypic analyses employed ring-stage survival assays (ring-stage survival assay from 0 to 3 h [RSA0-3h]), whose results have earlier been shown to correlate with parasite clearance rates in patients. Our results document cross-resistance between OZ277 and dihydroartemisinin (DHA), a semisynthetic derivative of ART, in parasites carrying the K13 mutations C580Y, R539T, and I543T. For OZ439, we observed cross-resistance only for parasites that carried the rare K13 I543T mutation, with no evidence of cross-resistance afforded by the prevalent C580Y mutation. Mixed-culture competition experiments with isogenic lines carrying modified K13 revealed variable growth deficits depending on the K13 mutation and parasite strain and provide a rationale for the broad dissemination of the fitness-neutral K13 C580Y mutation throughout strains currently circulating in Southeast Asia.IMPORTANCE ACTs have helped halve the malaria disease burden in recent years; however, emerging resistance to ART derivatives threatens to reverse this substantial progress. Resistance is driven primarily by mutations in the P. falciparum K13 gene. These mutations pose a threat to ozonides, touted as promising alternatives to ARTs that share a similar mode of action. We report that DHA was considerably more potent than OZ439 and OZ277 against ART-sensitive asexual blood-stage parasites cultured in vitro We also document that mutant K13 significantly compromised the activity of the registered drug OZ277. In contrast, OZ439 remained effective against most parasite lines expressing mutant K13, with the exception of I543T that merits further monitoring in field-based OZ439 efficacy studies. K13 mutations differed considerably in their impact on parasite growth rates, in a strain-dependent context, with the most prevalent C580Y mutation being fitness neutral in recently culture-adapted strains from Cambodia, the epicenter of emerging ART resistance.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Resistência a Medicamentos , Compostos Heterocíclicos/farmacologia , Mutação de Sentido Incorreto , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/fisiologia , Camboja , Sobrevivência Celular , Humanos , Malária Falciparum/parasitologia , Plasmodium falciparum/isolamento & purificação , Proteínas de Protozoários/genética , Virulência
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