How Scottish scientists have shown inserting a parasite into your brain would help treat Alzheimer’s Disease

Researchers from the University of Glasgow and Tel Aviv University have been investigating whether a common brain parasite - Toxoplasma gondii - can be engineered to deliver treatments directly to the brain of patients with cognitive disorders.

Researchers said that “while most neurological conditions, including Alzheimer’s Disease, Parkinson's and Rett Syndrome, have been linked in some way to protein dysfunction, targeting the problem at source has proved complex”. 

“Delivering therapeutics, including targeted proteins, across the blood-brain-barrier and into the correct location inside neurons is difficult and has so far limited the treatment options for these neurological conditions,” the researchers said.

However, Toxoplasma gondii has evolved to travel from the digestive system to the brain where it secretes its proteins into neurons, which can potentially be used to safely deliver key therapeutic proteins that could help treat neurological diseases.

Scientists at the University of Glasgow focused on engineering the parasites to deliver the MeCP2 protein, which has already been proposed as a promising therapeutic target for Rett syndrome, a debilitating neurological disorder caused by mutations in MECP2 gene.

Further experiments, in collaboration with the team from Tel Aviv University, confirmed the engineered parasites can deliver the protein to the target cell location in the laboratory, in brain organoids and in mice modes.

Researchers are now focused on further engineering the parasites so they die after delivering the protein, to prevent them from causing harm to cells.

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

However, the researchers said more research and testing would be needed before the parasite would be safe to use in treatments.

Prof Sheiner adds: “The concept is not without challenges, considering the dangers involved with Toxoplasma infection. 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.”

Prof Oded Rechavi, from Tel Aviv University, said: “Evolution has 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.”

Toxoplasma gondii is a parasite that can be carried by all warm-blooded animals, including humans. It is generally transmitted through undercooked meat, soil or from contact with cat faeces. 

Up to one third of the UK population is chronically infected with the parasite, although most experience few harmful effects.

Toxoplasmosis is a disease caused by the Toxoplasma parasite. While most people feel no effects from carrying the parasite, as it lies dormant in the majority of people infected, in those with weakened immune systems this parasite can ‘wake up’ and cause serious complications.

When the Toxoplasma ‘wakes up’ in people with compromised immune systems, it can cause stroke and in infants it can cause severe brain damage.