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Research Interests

My research focuses in drug discovery and translational research for Chagas disease. We have developed high content screening (HCS) assays that permit the triage of chemical compounds for determination of activity against Trypanosma cruzi, the protozoan parasite that causes Chagas disease. These assays are amenable to automation and have been used in high throughput mode to screen chemical libraries. Additionally, these assays are used to provide routine testing and guide hit prioritization and chemical optimization of hit compounds selectivity/antiparasitic properties during structure-activity relationship (SAR) studies, a process also known as lead optimization. A major goal is developing and improving in vitro and in vivo assays that will translate human disease into experimental models applicable to drug discovery programs, ultimately leading to the discovery of novel chemotherapeutic agents for Chagas disease, while generating knowledge about Chagas disease pathogenesis.

 

Cellular models of Chagas disease for drug discovery

One of the major bottlenecks in drug discovery for Chagas disease (as for other neglected tropical diseases) is the paucity of critical path assays that can estimate with confidence the translation of good leads and preclinical candidates into successful drug candidates during clinical trials. Murine models are often used to select and determine whether a promising lead or lead candidate has good in vivo activity. However, although an important component of lead optimization and preclinical studies, Chagas disease murine models differ considerably among laboratories, and it is not currently known which model is the best (most predictive) of drug candidate clinical outcome. Indeed, azole compounds have shown promising results in laboratory murine models however have failed in human clinical trials.

In an attempt to establish, in the long term, critical path assays for Chagas disease, we have been developing a range of in vitro, HCS-based assays to support drug discovery programs. Currently our assay portfolio includes a panel of wild type T. cruzi strains and clones representative of all known six T. cruzi groups (phylogenetic subdivisions known as discrete typing units, or DTUs), and  T. cruzi clones resistant to antichagasic drugs and drug candidates; and time-kill and recovery assays to determine whether compounds are trypanocidal or trypanostatic and the kinetics of antiparasitc activity, influenced by the compound concentration and time of exposure. Altogether these assays can determine whether a compound has broad activity against diverse T. cruzi, check whether new compounds are active against T. cruzi resistant to current drugs, and determine the best combination of compound concentration and time of exposure needed to achieve trypanocidal activity. These are valuable information that aid in the design of in vivo drug administration protocols and establish preliminary compound pharmacodynamics properties.

 

Chemical Genetics of T. cruzi infection and intracellular developmental cycle

Despite decades of research, the molecular players that regulate T. cruzi intracellular developmental cycle remain mostly unknown. This is in part due to the fact that T. cruzi genetic modification is not trivial, and techniques such as RNA interference are not available for this parasite.

To gain a deeper understanding of Trypanosoma cruzi development, we are using phenotypic assays and a Chemical Genetics approach to study T. cruzi and host cell interactions. We have developed a phenotypic high content screening assay for monitoring T. cruzi intracellular development from trypomastigotes after invasion to amastigotes, which replicate, and then back to trypomastigotes, which eventually leave the host cell to infect nearby cells. This assay is combined with small molecule chemical libraries to screen compounds for their ability of modulating T. cruzi infection and development within human cells. Using this approach we have discovered compounds that can arrest parasite development either at the trypomastigote or “early” amastigote stage, leading to previously unknown phenotypes (figure). We are currently characterizing the mechanism of action of these compounds and the cellular bases of the phenotypes observed. In the long term, by deconvoluting the compound target, we aim at discovering parasite proteins that interact with the host cell and possible targets for therapeutic intervention.