Brain parasites are something most people would naturally want to avoid, but perhaps they could be put to good use. A new study has found that drugs for a common brain parasite can be engineered to bypass the blood-brain barrier.
Toxoplasma gondii It is an intriguing and insidious parasite. Its primary host is cats, and it can only reproduce sexually in their intestines – although it may take a circuitous route to get there. It can infect many species of warm-blooded animals, including humans. When ingested via infected meat, soil or faeces, it spreads throughout the body, including the brain.
Once there, it is known to secrete proteins that affect the behavior of its intermediate host. For example, infected mice become bolder and less anxious around cats, which means they will eat them and return the parasite straight to its preferred breeding ground. It may even make the rodents more attractive to the opposite sex, increasing their chances of spreading the infection. Even stranger, studies have shown it has similar effects in humans.
Putting the effects aside, T. gondii has naturally overcome a major obstacle that has prevented scientists from treating a number of neurological disorders—the blood-brain barrier. This defense mechanism keeps almost all molecules circulating in the bloodstream away from the brain, protecting this most vital organ from harm. But unfortunately, therapeutic molecules are also blocked from entering, making it harder to treat brain cancers and other diseases.
So for the new study, an international team of researchers investigated whether the parasite's ability to cross the blood-brain barrier could be used to deliver drugs. T. gondii To produce a protein called MeCP2, which is a promising candidate for treating a rare genetic neurological disorder called Rett syndrome.
Once that was done, the researchers tested whether the parasites could deliver MeCP2 to the right cells in the brain. Indeed, experiments in mice and lab-grown mini-brains showed that T. gondii managed to smuggle the goods across the blood-brain barrier.
It’s an interesting idea, and could eventually lead to a new way to treat neurological disorders like Alzheimer’s and Parkinson’s. It could be simpler than some other methods of getting past the blood-brain barrier, such as magnetic nanoparticles, ultrasound, “Cellbots,” or bee venom.
“Evolution has already 'invented' organisms that can manipulate our brains. I think we can learn from them and use their abilities rather than reinvent the wheel,” said Professor Oded Rechavi, one of the authors of the study.
The next step is to make sure the parasite dies after it has delivered. After all, T. gondii can still damage brain cells.
The research was published in the journal Nature MicrobiologyWe discuss the team's work in the video below.
Could brain parasites be used to treat cognitive disorders?
Source: University of Glasgow