The protein aggregation inhibitor YAT2150 has potent antimalarial activity in Plasmodium falciparum in vitro cultures

Abstract

Background By 2016, signs of emergence of Plasmodium falciparum resistance to artemisinin and partner drugs were detected in the Greater Mekong Subregion. Recently, the independent evolution of artemisinin resistance has also been reported in Africa and South America. This alarming scenario calls for the urgent development of new antimalarials with novel modes of action. We investigated the interference with protein aggregation, which is potentially toxic for the cell and occurs abundantly in all Plasmodium stages, as a hitherto unexplored drug target in the pathogen. Results Attempts to exacerbate the P. falciparum proteome’s propensity to aggregation by delivering endogenous aggregative peptides to in vitro cultures of this parasite did not significantly affect their growth. In contrast, protein aggregation inhibitors clearly reduced the pathogen’s viability. One such compound, the bis(styrylpyridinium) salt YAT2150, exhibited potent antiplasmodial activity with an in vitro IC50 of 90 nM for chloroquine- and artemisinin-resistant lines, arresting asexual blood parasites at the trophozoite stage, as well as interfering with the development of both sexual and hepatic forms of Plasmodium. At its IC50, this compound is a powerful inhibitor of the aggregation of the model amyloid β peptide fragment 1-40, and it reduces the amount of aggregated proteins in P. falciparum cultures, suggesting that the underlying antimalarial mechanism consists in a generalized impairment of proteostasis in the pathogen. YAT2150 has an easy, rapid, and inexpensive synthesis, and because it fluoresces when it accumulates in its main localization in the Plasmodium cytosol, it is a theranostic agent. Conclusions Inhibiting protein aggregation in Plasmodium significantly reduces the parasite’s viability in vitro. Since YAT2150 belongs to a novel structural class of antiplasmodials with a mode of action that potentially targets multiple gene products, rapid evolution of resistance to this drug is unlikely to occur, making it a promising compound for the post-artemisinin era.

Effect of the aggregated protein dye YAT2150 on Leishmania parasite viability

“…Previous studies have succeeded with targeted aggregation in live plant cells by inducing the endogenous expression of aggregation-prone peptides, obtaining a visible specific phenotype ( 27 ). However, similar attempts failed to induce toxicity in P. falciparum ( 11 ) or human cell lines ( 32 ), likely by the difficulty of attaining a critical concentration of seeds necessary to sustain intracellular aggregation of the desired protein, discouraging this approach as a therapeutic alternative in Leishmania .…”

“…The detection in live L. infantum of protein aggregates and the identification in the parasite of proteins containing amyloidogenic peptides mirrored similar phenomena recently observed in P. falciparum ( 10 ). In the latter pathogen, low concentrations (<100 nM) of certain β-sheet intercalators, which lowered the in vitro aggregation of amyloid peptides ( 33 ), clearly inhibited its growth ( 11 ). When testing the effect on L. infantum of some of these small molecules known to interfere with protein aggregation ( Fig.…”

“…On the bright side, protein aggregation serves functional purposes in various organisms, e.g., as a rapid mechanism to respond to environmental challenges through stress granule formation ( 6 ) or uncovering genetic diversity needed in starvation ( 7 ), to facilitate the controlled release of peptidic hormones in secretory granules in a pH-dependent manner ( 8 ), or to promote synapse-specific changes that strengthen dendritic spines and contribute to memory consolidation ( 9 ). Recently, we described that in the human malaria parasite Plasmodium falciparum , protein aggregation presumably plays a functional role and that its inhibition is detrimental to the pathogen ( 10 , 11 ). Motivated by these findings, we have explored in the current work the therapeutic potential of inhibiting protein aggregation for other parasitic diseases.…”

“…We evaluated the effect of the aggregated protein dye YAT2150, a potent antiplasmodial drug with a half-maximal inhibitory concentration (IC 50 ) of ca. 90 nM in in vitro P. falciparum cultures ( 11 ), on the viability of L. infantum promastigotes and amastigotes. Malaria and leishmaniasis are the first and second parasitic diseases, respectively, in number of deaths ( 12 ), in many cases with overlapping distribution, although the clinical study of co-infection with both pathogens has been mostly neglected ( 13 ).…”

Heparin-Coated Dendronized Hyperbranched Polymers for Antimalarial Targeted Delivery

“…This alarming scenario calls for the urgent development of new drugs of easy and cost-affordable production, with little-exploited targets in the malaria parasite, having several molecular targets in the pathogen and acting through new mechanisms of action not shared by currently used drugs. New promising compounds, such as the recently discovered YAT2150, might require the availability of nanocarriers such as the heparin-targeted DHPs characterized here in order to improve pharmacokinetic profiles and for targeted delivery to Plasmodium-infected cells. Such specific targeting will be essential to limit the emergence of resistance in the pathogen to future drugs because the administered doses will result in higher local concentrations reaching the parasite and therefore in a reduction of the likelihood of resistance evolution.…”