Project

Discipline

in vivo; Toxoplasmosis; auxotrophies; metabolomics; ruthenium complexes; biodistribution; HRMAS NMR spectroscopy; protozoan parasites

Lead
Nouvelles molécules à base de ruthénium pour le traitement de maladies induites par des parasites apicomplexes (toxoplasmose, malaria)
Lay summary
Les maladies telles que la Malaria, toxoplasmose, neosporose, la maladie du sommeil et bien d'autres sont causées par des parasites dits apicomplexes. Ce sont des maladies qui induisent de graves problèmes, humains et économiques, dans les pays touchés. Malheureusement, le développement de nouveaux médicaments contre ces parasites reste très limité, bien que les traitements actuels soient de moins en moins efficaces, avec en particulier l'apparition de nombreuses résistances. Dans le cadre de ce projet, des spécialistes en chimie, biologie moléculaire et parasitologie vont joindre leurs forces pour exploiter des molécules à bases de ruthénium, actuellement candidates pour être utilisées contre le cancer, afin d'en faire des molécules potentiellement anti parasitiques. Dans ce projet, nous nous concentrerons dans un premier temps sur le parasite T. gondii, car celui-ci est considéré comme un organisme modèle pour les études cliniques et pharmacologiques. Plus précisément, nous envisageons d'exploiter les auxotrophies du parasite T gondii, telles que l'arginine, les purines, les polyamines, que le parasite doit récupérer de son organisme hôte pour survivre. En conjuguant nos complexes de ruthénium à ces molécules, nous espérons augmenter la prise de ces complexes par les parasites. Les plus prometteurs d'entre eux, identifiés par des mesures in vitro, seront également évalués in vivo. Nous tenterons également d'identifier les cibles cellulaires et comprendre le ou les mécanismes d'action. En parallèle, d'autres études in vitro seront effectuées contre les parasites Plasmodium, Trypanosoma, Giardia, afin d'obtenir des informations sur le potentiel de ces complexes comme médicaments antiparasitiques. A la fin du projet, nous espérons être en mesure d'avoir 3-5 complexes actifs et sélectifs contre un ou plusieurs de ces parasites, ainsi que de bonnes efficacités in vivo. Il sera ainsi envisageable de passer aux tests précliniques et cliniques.

Direct link to Lay Summary

Last update: 09.06.2017

Natural persons

Active participation

Title	Year

Number	Title	Start	Funding scheme

Malaria, cryptosporidiosis, coccidiosis, toxoplasmosis, theileriosis, neosporosis, and besnoitiosis, causedby apicomplexan parasites, as well as African sleeping sickness and giardiasis, are diseases of high humanand/or veterinary relevance, and inflict a dramatic medical and economic burden in affected countries worldwide.1While a plethora of drugs has been, and is being, developed against a wide range of cancers, drug developmentagainst parasitic diseases has been largely neglected, despite the fact that many currently employed antiparasitictherapies exhibit adverse side effects, are not very efficacious, and resistance formation has beenrecognized as a serious constraint.2 In this interdisciplinary project, specialists in medicinal and syntheticchemistry, metabolomics, HRMAS NMR, ICP-MS, medical parasitology, and cell and molecular biology will joinforces to exploit the potential of ruthenium-based anti-cancer drugs, aiming to develop novel chemotherapiesagainst a wide range of protozoan parasites and study their mechanism of action.More specifically, this project is based on the highly promising preliminary results obtained by themembers of this consortium with organometallic ruthenium complexes in in vitro studies on the protozoanparasites Toxoplasma gondii, Plasmodium berghei and Trypanosoma brucei. Ruthenium compounds are knownto cause little side effects, they are well suited towards pharmacological applications, and their production is costefficient,which is especially interesting for in vivo studies and clinical trials. We will primarily focus on T. gondiisince this represents a prime model organism for studies on intracellular parasitism and host-parasiteinteractions. A targeted approach for generating novel compounds will exploit the auxotrophies (polyamines,amino acids, purines, cholesterol, folates), and metabolic peculiarities (for instance folate transport systems) of T.gondii, by conjugating arene ruthenium moieties to metabolites that are essential for the parasite and that have tobe scavenged from the host cell. This will increase uptake and will result in higher and more specific anti-parasiticactivities. From a therapeutic perspective, the strategy to force a parasite to acquire toxic compounds coupled toessential moieties has not yet been exploited, although it has a significant potential. In practical terms, the mostpromising complexes generated in this project will be identified by in vitro screening of T. gondii grown infibroblasts, and for selected drugs the pharmacokinetic properties and biodistribution in different organs in micewill be assessed by ICP-MS. Those conjugates showing favorable in vivo features (high exposure, low toxicity)will be assessed in standardized murine infection models for acute and congenital toxoplasmosis. Further studieson the mechanisms of action of these drugs will include (i) assessment of metabolic changes in T. gondiiemploying HRMAS NMR spectroscopy; (ii) transmission electron microscopy of drug-treated parasites; (iii)identification and characterization of drug-binding proteins and putative targets using affinity chromatography ondrug-conjugated matrices; and (iv) CRISPR-Cas9-mediated knock-out or overexpression of putative druginteraction partners to study phenotypic changes and target validation. In vitro activities of selected rutheniumcomplexes will be further assessed in Plasmodium, Eimeria, Trypanosoma, Giardia, Theileria, Besnoitia andGiardia by several interested collaborating laboratories. This will provide information on a broader applicability ofruthenium complexes, and will serve as a condensation point for (i) future research on these novel anti-parasiticcompounds, and (ii) a potentially more widespread relevance of the identified drug targets.At the end of this project, we will have generated 3-5 compounds with highly selective in vitro toxicityagainst one or several of these protozoan parasites, and excellent in vivo efficacy in mouse models of acute andcongenital toxoplasmosis, ready to be tested in larger animals for prospective advancement to clinical trials. Veryimportantly, this project will be annually assessed by an advisory board composed of highly recognized chemistsand drug development specialists from academia and industry.