TB and Malaria collaboration results in potential malaria drug targets

November 2017 --- Scientists at CID Research found novel targets for potential malaria drugs using a technique recently pioneered for studying Mycobacterium tuberculosis (Mtb). In a model of interdisciplinary collaboration, malaria experts teamed up with our tuberculosis researchers to address a gap in malaria research – the metabolically quiet gametocyte stage – and found a class of enzymes that may be druggable in the otherwise inactive gametocyte.

The project is a collaboration between the Kappe and Grundner Labs, whose findings, published in Molecular and Cellular Proteomics, could lead to new treatments for malaria. The original concept won funding from the CID Research 2013 Employee Giving Campaign, when the Center called for ideas that foster innovative and collaborative science. That initial investment resulted in a completed research project with published findings and an application for a significant federal grant for further investigations on yet another family of drug targets for malaria.

The most mysterious stage of a mysterious parasite

When the first malaria drugs were discovered in the mid-20th century, hope was high that malaria could be completely eradicated. Unfortunately, the malaria parasite outsmarted these efforts, taking advantage of inappropriate drug administration and developing drug resistance that soon spread widely. It became clear that a major hurdle was the parasite's complex life cycle, which includes a near-dormant stage in which the parasite is known as a gametocyte. In this stage, the parasite is taken up with human blood by a mosquito and then transmitted to the next human that mosquito bites.

Because the parasite has very little biochemical activity in the transmission stage, it is extremely difficult to identify a biochemical process to target with drugs. As a result, malaria research has long focused on targeting other life-cycle stages of the parasite, but that strategy is increasingly proving inadequate in the face of frequent reinfection.

The collaboration between the Kappe Lab, experts in the life cycle of the P. falciparum malaria parasite, and the Grundner Lab, experts in chemical biology and Mtb, is at the forefront of investigating the gametocyte for drug development.

"Solely focusing on treating the parasite that causes symptoms will not reduce the burden of malaria if we do not control transmission as well."

Dr. Stefan Kappe, professor

Crossing disciplines: applying TB techniques to malaria research

There are natural similarities to one of the world's other most challenging diseases, tuberculosis. Dr. Christoph Grundner is an expert in Mtb, but says, “with my office between two malaria researchers, I am also immersed in malaria and the unique challenges that field faces. But strikingly, not all their problems are unique. In fact, both malaria and TB pathogens produce dormant stages that are difficult to target with drugs because they are metabolically silent. We saw the similarities and realized there could be an opportunity to apply a new technology my lab developed in our study of dormant tuberculosis, and apply it to the dormant malaria parasite,” said Grundner.

The Grundner Lab uses an approach known as activity-based proteomics, often used in cancer research, to measure the activity of entire enzyme families at once in a cell. Grundner and his team have pioneered its application in tuberculosis, realizing that activity-based proteomics also reveals information that can be used to identify the biochemical functions of many Mtb proteins with unknown function that make up large parts of the genome – another feature that Mtb and P. falciparum share.

Considering the similar challenges, Grundner and Kappe put together a proposal for a proof-of-concept project and decided to submit it for the CID Research Employee Giving Fund in 2013, where it was selected for the innovative integration of technology and the strong promise for exploring additional funding. “It is difficult to get this kind of pilot project funded. Without everyone at the Center chipping in, we probably would not have done it,” says Grundner.

From parasite to drug target

The process began in the Kappe Lab with their expertise in growing P. falciparum throughout its complex life cycle. Producing P. falciparum gametocytes requires careful culturing and quality control. For comparison, they also created culture samples for the more commonly studied schizont phase of the parasite, the phase which makes people sick.

The Grundner Lab then used activity-based proteomics to study the biochemical activity of the gametocytes, gathering data about all members of a large family of enzymes, the ATPases. After processing the samples, they sent everything to the Pacific Northwest National Laboratory for further analysis by mass spectrometry. Finally, the two labs analyzed the data, comparing the two stages of the parasite and looking for insight into potential processes for drug targets.

“Both malaria and TB pathogens produce dormant stages that are difficult to target with drugs because they are metabolically silent. We saw the similarities and realized there could be an opportunity to apply a new technology my lab developed in our study of dormant tuberculosis, and apply it to the dormant malaria parasite,” says Dr. Christoph Grundner, above right, with Dr. Stefan Kappe.

Creating momentum with systems biology

The most active enzymes in the otherwise dormant gametocyte are top candidate drug targets that could block transmission of the parasite. At the same time, mapping the activity of the enzymes allowed the researchers to confirm the annotation of 141 known or predicted ATPases, and discover the ATPase activity of 37 previously uncharacterized proteins.

Inspired by the success of this initial work, the two labs applied for a federal R21 grant to further the investigation with a different family of enzymes also known to be druggable for malaria. The research may expand the work into yet another large enzyme family, leading to even more new drug targets for malaria and identifying the biochemical function for many more proteins of unknown function.

“The problem of proteins with unknown function is universal, so it is our hope that this method can be useful for others in infectious disease research,” says Grundner.

As the labs celebrate the publication of their joint paper and prepare to expand this research, Grundner brings attention to a special inclusion in the paper’s Acknowledgements:

“We are especially grateful to the employees of the Center for Infectious Disease Research for generously supporting large parts of this work through donations to the 2013 employee giving campaign.”

Day to day, individual efforts can sometimes get lost in the daily grind. However, the Kappe and Grundner collaboration is really a collaboration between all employees – a reminder that we are all part of something bigger than ourselves. Thanks to all those who made these and other discoveries possible through your generosity and investment in our work.