Brain parasites are something that most people would naturally want to avoid, but maybe they can be used for good. A new study has found that a common brain parasite could be engineered to deliver drugs past the blood-brain barrier.
Toxoplasma gondii is an intriguing and insidious parasite. Its primary host is felines, and it can only sexually reproduce in the intestines of cats – but it can take a roundabout way to get there. It can infect many types of warm-blooded animals, including humans. Once ingested through infected meat, soil or feces, it spreads throughout the body, including the brain.
Once there, it’s been known to release proteins that seem to affect the behavior of its intermediate host. Infected mice, for instance, become bolder and less anxious about cats, meaning they’re more likely to be eaten by them, delivering the parasite right back to its favored breeding ground. It even seems to make rodents more attractive to the opposite sex, increasing its chances of spreading the infection. Stranger still, studies suggest it has similar effects in humans.
Effects aside, T. gondii has naturally overcome a major hurdle that prevents scientists treating a host of neurological conditions – the blood-brain barrier. This defense mechanism keeps almost all molecules circulating in the bloodstream out of the brain, protecting that most vital of organs from harm. But unfortunately, therapeutic molecules are also blocked from entering, which makes it tricky 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 harnessed to deliver drugs. The team engineered T. gondii to produce a protein called MeCP2, which is a promising candidate for treating a rare genetic neurological condition called Rett syndrome.
Once that was done, the researchers tested whether the parasites could deliver MeCP2 to the right cells in the brain. Sure enough, experiments in mice and in lab-grown mini-brains showed that the T. gondii was able to smuggle the goods past the blood-brain barrier.
It’s an interesting idea, and could eventually open a new way to treat neurological disorders like Alzheimer’s and Parkinson’s. It might be simpler than some other methods of bypassing the blood-brain barrier, like magnetic nanoparticles, ultrasound, “Cellbots” or bee venom.
“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,” said Professor Oded Rechavi, an author of the study.
The next step will be engineering the parasite to die off after it makes its delivery. After all, T. gondii can still do harm to brain cells.
The research was published in the journal Nature Microbiology. The team discusses the work in the video below.
Source: University of Glasgow
