Publicação
Genetic determinants of malaria therapeutics’ cross resistance with novel compounds
| Resumo: | In 2019, malaria caused half a million deaths worldwide, being elimination hampered by the ability of Plasmodium falciparum to evolve antimalarial resistance. The efficacy of artemisinin-based combination therapies (ACT) helped to reduce malaria mortality, however, resistance is a reality. Being ACT efficacy threatened, efforts to define the molecular basis of multidrug resistance and the search for new compound, ideally with new mechanisms of action, are urgently in need. Within the parasite, most of the available antimalarials act at the host’s intraerythrocytic stage. Here, many drugs are housed in the digestive vacuole of the parasite with flux promoted by transporter proteins, such as the Plasmodium falciparum multidrug resistance protein 1 (PfMDR1), a well-known ACT resistance player. We explored the interplay of known pfmdr1 resistance markers, namely, gene copy number variation with N86Y and Y184F single nucleotide polymorphisms to unravel the complex traits that might serve to maximize ACT resistance. Using genomic epidemiology, a global prevalence and temporal changes of pfmdr1 polymorphisms were assessed and, taking into account the information from this database, through a gene editing approach, we create in vitro edited parasite lines to evaluate the impact of these polymorphisms in the kinetics of the transporter. This data provided evidence of specific multicopy PfMDR1 with N86/184F haplotype, geographic selection and expansion in Southeast Asia. The genetic tools created could help on finding drugs with potential of reverting a multidrug resistance phenotype, as the herein explored synthetic compounds derived from steroids, a class of molecules with relevant biological activities. Structure–activity relationship led to the synthesis of steroid derivatives with promising antimalarial activity against the blood stage of the parasite’s life cycle with high selectivity and independent of PfMDR1. Exploring possible mechanisms of action of the best compound, revealed induction of oxidative stress inside the parasite and interference with the metabolic process that leads to hemozoin formation inside the digestive vacuole of the parasite. Overall, the findings presented could help tailor and optimize present antimalarial drug usage by taking into account the regional prevalence of pfmdr1 polymorphisms and highlights the high potential of the newly developed compounds, thereby underscoring the possibility to develop new antimalarial drugs based on steroids. |
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| Autores principais: | Calçada, Carla Sofia Martins |
| Assunto: | Malaria Membrane transporter proteins Plasmodium falciparum Resistance Synthetic steroids Esteróides sintéticos Malária Plasmodium falciparum Proteínas transportadoras de membrana Resistência |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | In 2019, malaria caused half a million deaths worldwide, being elimination hampered by the ability of Plasmodium falciparum to evolve antimalarial resistance. The efficacy of artemisinin-based combination therapies (ACT) helped to reduce malaria mortality, however, resistance is a reality. Being ACT efficacy threatened, efforts to define the molecular basis of multidrug resistance and the search for new compound, ideally with new mechanisms of action, are urgently in need. Within the parasite, most of the available antimalarials act at the host’s intraerythrocytic stage. Here, many drugs are housed in the digestive vacuole of the parasite with flux promoted by transporter proteins, such as the Plasmodium falciparum multidrug resistance protein 1 (PfMDR1), a well-known ACT resistance player. We explored the interplay of known pfmdr1 resistance markers, namely, gene copy number variation with N86Y and Y184F single nucleotide polymorphisms to unravel the complex traits that might serve to maximize ACT resistance. Using genomic epidemiology, a global prevalence and temporal changes of pfmdr1 polymorphisms were assessed and, taking into account the information from this database, through a gene editing approach, we create in vitro edited parasite lines to evaluate the impact of these polymorphisms in the kinetics of the transporter. This data provided evidence of specific multicopy PfMDR1 with N86/184F haplotype, geographic selection and expansion in Southeast Asia. The genetic tools created could help on finding drugs with potential of reverting a multidrug resistance phenotype, as the herein explored synthetic compounds derived from steroids, a class of molecules with relevant biological activities. Structure–activity relationship led to the synthesis of steroid derivatives with promising antimalarial activity against the blood stage of the parasite’s life cycle with high selectivity and independent of PfMDR1. Exploring possible mechanisms of action of the best compound, revealed induction of oxidative stress inside the parasite and interference with the metabolic process that leads to hemozoin formation inside the digestive vacuole of the parasite. Overall, the findings presented could help tailor and optimize present antimalarial drug usage by taking into account the regional prevalence of pfmdr1 polymorphisms and highlights the high potential of the newly developed compounds, thereby underscoring the possibility to develop new antimalarial drugs based on steroids. |
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