So the cat parasite is lurking into your brain
Up to every fifth Swedish berries on the parasite toxoplasma. In other countries, such as France, the infection is even more common. However, the natural residence of the parasite is not we humans, but other animals such as cats, birds and mice.
Normally, the parasite causes no symptoms, but it can cause severe illness. Especially in people with impaired immune systems and pregnant women.
– In AIDS patients, for example, or organ -transplanted persons, it can cause brain inflammation that can lead to death. Foster may suffer from water skull or other malformations, says Antonio Barragan, professor at the Department of Molecular Biology at Stockholm University.
Previously, he has And his colleagues have shown that the parasite enters the body with the help of one of the immune system cells. However, how it moves on and into the brain has been something of a mystery. Not least because of the so-called blood-brain barrier, which effectively keeps bacteria, viruses and parasites away from the brain.
With the help of micro -surgery and advanced microscopy the researchers now show that the parasite can « ride taxis » with the immune cells, from the intestine up to the brain. When the parasite reaches the very finest blood vessels, the capillaries, the immune cells manipulate to produce two adhesive-like molecules: ICAM-1 and CD18.
The result is like a Velcro that makes the immune cells get stuck in the vessel wall.
– Then the parasite leaves the immune cells and penetrates into the brain tissue, says Antonio Barragan.
The research, as reported in Nature Communicationsshows that the parasite can in this way infect the brain in just a few hours. Once inside the brain, it can live there for several years, or for the rest of life.
– Most often you get no symptoms, but if for some reason the immune system becomes impaired, it can come to life and cause serious illness, says Antonio Barragan.
Older people often have worse immune systems. Is the parasite more dangerous for them than for younger ones?
– Normally not. The immune system must be more reduced than it usually becomes just because of old age.
How common is the parasite among cats?
– It varies. It jumps between cats, mice and birds. Therefore, it is more common among outdoor cats than it is among indoor cats. Between 15 and 20 percent of Swedes carry the parasite. But meat that has not been properly cooked through is probably a more common path of infection than cats. This is one reason why pregnant women should not eat meat that is not well cooked, says Antonio Barragan.
Previous research has shown a connection between the presence of toxoplasma and schizophrenia and suicidal tendency. A few years ago it was possible to show that toxoplasma makes chimpanzees less afraid of leopards.
– There is a connectionbut there is no evidence of a causal relationship. It may be so, but we don’t know. We will try to find out now, by injecting the parasite directly into the brain of mice, says Antonio Barragan.
Since the researchers now know that the parasite infects the brain using two « adhesive molecules », there is the hope of being able to block these molecules using antibodies so that the infection does not take place.
– There are two antibodies that seem to work. We also plan to test a very common medicine, heparin, which has an anti-adhesive effect that hopefully means that the immune cells do not get stuck, says Antonio Barragan.
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