Metabolic adjustments of blood-stage Plasmodium falciparum in response to sublethal pyrazoleamide exposure

Shivendra G Tewari,Krithika Rajaram,Sean T Prigge,Jaques Reifman,Rubayet Elahi,Bobby Kwan,Akhil B Vaidya,Anders Wallqvist

doi:10.1038/s41598-022-04985-7

Abstract

Due to the recurring loss of antimalarial drugs to resistance, there is a need for novel targets, drugs, and combination therapies to ensure the availability of current and future countermeasures. Pyrazoleamides belong to a novel class of antimalarial drugs that disrupt sodium ion homeostasis, although the exact consequences of this disruption in Plasmodium falciparum remain under investigation. In vitro experiments demonstrated that parasites carrying mutations in the metabolic enzyme PfATP4 develop resistance to pyrazoleamide compounds. However, the underlying mechanisms that allow mutant parasites to evade pyrazoleamide treatment are unclear. Here, we first performed experiments to identify the sublethal dose of a pyrazoleamide compound (PA21A092) that caused a significant reduction in growth over one intraerythrocytic developmental cycle (IDC). At this drug concentration, we collected transcriptomic and metabolomic data at multiple time points during the IDC to quantify gene- and metabolite-level alterations in the treated parasites. To probe the effects of pyrazoleamide treatment on parasite metabolism, we coupled the time-resolved omics data with a metabolic network model of P. falciparum. We found that the drug-treated parasites adjusted carbohydrate metabolism to enhance synthesis of myoinositol—a precursor for phosphatidylinositol biosynthesis. This metabolic adaptation caused a decrease in metabolite flux through the pentose phosphate pathway, causing a decreased rate of RNA synthesis and an increase in oxidative stress. Our model analyses suggest that downstream consequences of enhanced myoinositol synthesis may underlie adjustments that could lead to resistance emergence in P. falciparum exposed to a sublethal dose of a pyrazoleamide drug.

Highlights

Due to the recurring loss of antimalarial drugs to resistance, there is a need for novel targets, drugs, and combination therapies to ensure the availability of current and future countermeasures
PfATP4-associated drugs at lethal concentrations are known to alter pH homeostasis in malaria parasites, and these results suggest that a sublethal dose of a pyrazoleamide drug may cause alterations in the pH of the treated parasites
Because PfATP4 activity maintains the sodium ion gradient across the P. falciparum plasma membrane[5], these results suggest that sublethal doses of pyrazoleamides disrupt sodium ion homeostasis in P. falciparum

Summary

Introduction

Due to the recurring loss of antimalarial drugs to resistance, there is a need for novel targets, drugs, and combination therapies to ensure the availability of current and future countermeasures. We first performed experiments to identify the sublethal dose of a pyrazoleamide compound (PA21A092) that caused a significant reduction in growth over one intraerythrocytic developmental cycle (IDC). At this drug concentration, we collected transcriptomic and metabolomic data at multiple time points during the IDC to quantify gene- and metabolite-level alterations in the treated parasites. This adjustment constitutes the immediate survival phenotype and highlights the ability of the parasite to survive stress induced by the disruption of sodium ion homeostasis Towards this end, we first identified a dose of PA21A092 that caused a significant reduction in growth of P. falciparum Dd2 strain over a single intraerythrocytic developmental cycle (IDC). The identification of Plasmodium enzymes and pathways associated with drug-resistance development would allow development of rationally motivated drug-combination therapies that can mitigate evolution of drug-resistant progenies of P. falciparum

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