Asthma patient has lower risk of brain tumor – and scientists now think they know why

What is bad news for the respiratory system turns out to be good news for the brain.

There is not much good to say about asthma: a respiratory disease where there are always small inflammations in the lungs. Asthma patients often suffer from shortness of breath, wheezing and coughing. But what’s interesting is that compared to others, people with asthma seem to be less likely to develop a brain tumor. And now researchers have discovered why.

The idea that people with certain inflammatory diseases – such as asthma or eczema – have a lower risk of brain tumors was first suggested about fifteen years ago. This assumption is based on epidemiological observations. But why are the two very different kinds of diseases related? Nobody knew. Some scientists therefore questioned whether the supposed connection really existed.

Study

In a new study published in the journal Nature Communications, researchers took on the challenge of explaining the possible link. The researchers conducted several experiments with genetically modified mice that showed symptoms of asthma. And guess what? Indeed, the mice with asthma did not form brain tumors.

T cells

The researchers now think they know why. It has to do with T cells; white blood cells that play an important role in the immune system. That’s right. Asthma is characterized by inflammatory symptoms. In many cases, these arise because one’s own defenses are activated, while this really shouldn’t be. The T cells play an important role in this. When too many T cells are activated, this can lead to local inflammatory reactions, which is the case with asthma. Reactions normally required to fight germs and allergens have run amok, turning against the body. This causes inflammation in the lungs in asthma patients, but on the other hand can prevent the growth of brain tumors.

decorine

The connection is here: the T cells of asthmatic mice appear to secrete an important protein; called decorin. Decorin is a problem for the respiratory tract. It acts on tissues in the airways and worsens asthma symptoms. But in the brain, the researchers discovered, decorin is beneficial. There the protein acts on microglial cells; immune cells that protect the central nervous system against infections and damage. However, activated microglia can also promote the growth and development of brain tumors. But because decorin exerts an influence on these microglial cells, the chance that asthmatics will develop brain tumors is reduced. In short, what’s bad news for the respiratory system can be good news for the brain.

Therapy

The findings suggest a possible solution for brain tumor patients. “Of course we’re not going to cause asthma in anyone,” said study researcher David Gutmann. “But what if we can trick the T cells into thinking they are asthma T cells when they enter the brain, so that they no longer support the formation and growth of brain tumors? These findings open the door to new types of treatments that target T cells and their interactions with cells in the brain.”

It means that reprogramming T cells in brain tumor patients may offer a solution. “The next step is to see if the same holds true for other types of brain tumors,” Gutmann says. “We are also investigating the role of eczema and infections in early childhood, as they both involve T cells. The better we understand this communication between T cells and the cells that promote brain tumors, the better we will be able to develop good treatment plans.”