Research shows how a microscopic parasite disrupts brain function

Research shows how a microscopic parasite disrupts brain function

A team of scientists at the University of California, Riverside explains in a paper published inPLOS pathogenslike a microscopic parasite,Toxoplasma gondiican significantly disrupt brain function even if it only infects a small number of neurons. The team found that the parasite disrupts essential communication between brain cells - research that may provide new ways to detect and treat chronic brain infections.

Toxoplasma gondiiCan infect almost any warm-blooded animal and prefers to live in brain cells and form cysts in neurons that can persist for life. The researchers report that they found that infected neurons release fewer extracellular vesicles (EVS) - tiny, membrane-bound packages used by cells to exchange information.

“We found that this disruption of EV signaling can affect the way neurons and glial cells, particularly astrocytes, maintain a healthy brain environment,” said Emma H. ​​Wilson, a professor of biomedical sciences in the UC Riverside School of Medicine, who led the research team. "Even a handful of infected neurons can alter the brain's neurochemical balance. This suggests that communication between neurons and supporting glial cells is not only critical but also vulnerable to hijacking by parasites."

Approximately 10-30% of people in the United States are infected withToxoplasma gondiioften without knowing it. The parasite is usually contracted through undercooked meat or exposure to cat feces. Although the immune system typically keeps the infection at bay, the parasite can lie dormant in the brain for decades. In people with weakened immunity, it can reactivate and cause serious illness.

Current diagnostic tools can only determine whether someone has been exposedToxoplasma gondiiby identifying antibodies. The tools cannot confirm whether the parasite is still present in the brain or how it may affect brain function.

Our research opens the door to using EVs as biomarkers that can be isolated from blood. “

Emma H. ​​Wilson, Professor of Biomedical Sciences, UC Riverside School of Medicine

The study was conducted using mouse models and human cells in a laboratory setting.

Wilson explained that in healthy mice, astrocytes regulate neurotransmitters such as glutamate, ensuring that neurons do not become overexcited. But when neurons are infected withToxoplasma gondiiStop sending the right EV signals, this regulation collapses. The result is increased glutamate levels, which can lead to seizures, neuronal damage, or altered brain connectivity.

“The parasite may play a larger role in neurological and behavioral conditions than before,” she said.

Wilson's research team is now working on analyzing samples from human blood banks to look for EVs that are linked to each otherToxoplasma gondiiBrain infection. The team also hopes to better understand how glial cells detect and respond to parasite proteins - insights that could one day lead to new therapies or even vaccines.

“Our brains have built-in defenses that can detect and respond to neurons infected byToxoplasma gondiiWilson said. If we can learn how to support or improve this process, we may be able to better protect people, especially the most vulnerable. “

Despite its potential impact,Toxoplasma gondii“I am often misunderstood,” Wilson added.

"There is no need to avoid someone who is infected. Most people live their entire lives without symptoms," she said. "Pregnant individuals should be careful as the parasite can cause serious birth defects in pregnancy. The most effective prevention is proper treatment and hygiene. Eating meat, washing vegetables and always washing your hands after handling cat litter, especially from young cats who are more likely to shake the parasite."

Wilson was joined in the study by Emily Z. Tabaie, Ziting Gao, Nala Kachour, Arzu Ulu, Stacey Gomez, Zoe A. Figueroa, Kristina Bergersen and Wenwan Zhong.

The research was supported in part by funding from UCR's Department of Biomedical Sciences.

The research paper is titled “Toxoplasma gondiiInfection of neurons alters the production and content of extracellular vesicles that guide the astrocyte phenotype and contribute to the loss of GLT-1 in the infected brain. “

Sources: