Scientists from the University of Glasgow are investigating how brain parasites could help overcome a decades-old challenge of delivering targeted therapies into the brain to treat cognitive conditions.

In a world first project of its kind, the Glasgow-led team working alongside Tel Aviv University and international researchers are examining how modifying a parasite that can cross the blood-brain-barrier could allow targeted treatment for neurological disorders to be carried into specific brain regions.

In the new study published in Nature Microbiology, the research team explains that the specific parasite – the Toxoplasma gondii parasite – naturally travels from a person’s gut to the central nervous system.

It is estimated that a third of the world’s population carry the parasite in its dormant (non-harmful) state. The research team say they could engineer the parasite to safely deliver therapeutic proteins into neurons.

Delivering therapeutics, including targeted proteins, into the correct location inside the brain is difficult and has so far limited the treatment options for these conditions.

Professor Lilach Sheiner, one of the leading authors of the study from the University of Glasgow’s School of Infection and Immunity, says:

“This is a blue-sky project where our collaborative team was thinking out of the box to try to tackle the long-standing medical challenge of finding a way to successfully deliver treatment to the brain for cognitive disorders.”

This is a major challenge for many neurological conditions which have been linked to protein dysfunction, including Alzheimer’s disease, Rett syndrome – a debilitating neurological disorder – and Parkinson’s disease.

By creating key changes to the parasite, the team explored how it could act as a medicine delivery vehicle for one promising therapeutic target by testing it on disease-affected brain cells.

They successfully showed that the modified parasite could produce this therapeutic protein which has been recognised as a promising target for Rett syndrome.

Following this, researchers were able to show that the parasite can in fact “spit” the protein back out specifically into the affected brain cells.

This was confirmed both in the lab in brain models, and in mice models.

Professor Oded Rechavi from the Neurobiology, Biochemistry and Biophysics department in Tel Aviv University says it is about harnessing what already exists in nature:

“Evolution already “invented” organisms that can manipulate our brains, I think that instead of re-inventing the wheel we could learn from them and use their abilities.”

Now, the team are focused on further engineering the parasite to ensure it dies after successfully delivering the therapeutic protein to the brain.

This work will be essential to prevent the parasite from causing harm to healthy cells.

Thereafter, researchers hope to investigate how brain parasites can play a role in delivering a wider range of therapeutic proteins for more neurological conditions.

However, the researchers are clear that lots more research and testing must happen before the parasite would be safe to use as a therapeutic delivery vehicle.

“The concept is not without challenges, considering the dangers involved with Toxoplasma infection,” says Professor Sheiner.

“For our work to become a treatment reality, it will require many more years of careful research and development to enhance efficiency and improve safety.”

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