People with asthma seem to have fewer brain tumors. One day, the findings will help us develop better treatments for both conditions.
The connection between asthma and brain tumors was first found in global epidemiological research about 15 years ago, but without a proper mechanism linking the lung condition to the brain condition, some experts have dismissed the findings as random.
A new study suggests the relationship is real.
A study published in 2015 showed that some children with tumors along their brain pathway were not developing asthma at the same rate as the general population.
The research found that the tumors were being driven by an interaction between the brain's immune cells and the nerve.
Given that asthma is considered to be a T-cell mediated inflammatory disease, neurologists began to wonder if these immune cells were how the two conditions were connected.
Researchers used mouse models to test the idea. The authors caused asthma in the litters at 4 and 6 weeks of age after genetically modifying the mice.
There was no evidence of brain tumors in the mice with asthma. The mice with asthma showed the development of brain cancer.
There is something about asthma that hurts the lungs and helps the brain, but what is that?
A closer look at both groups of mice shows a different behavior of their T-cells.
David Gutmann, a neurologist from Washington University in St. Louis, says that asthma can be a lethal disease.
If we could trick the T-cells into thinking they're asthma T-cells when they enter the brain, they wouldn't support brain tumor formation and growth.
When T-cells in the lungs of mice were stopped from producing aprotein known as decorin, the animals showed less inflammation in their respiratory system.
The mice with asthma had an increased expression of decorin in their T-cells.
The expression of decorin is increased in the body's T-cells, where it is found in humans with asthma.
Decorin was not expressed as much in mice without asthma.
This suggests that the T-cell-derived protein may have anti-carcinogenic effects in the brain, even if it isn't great for the lungs.
The authors found that an increase of decorin along the mouse's optical nerve stopped the local T-cells from being activated.
There is a chance that treating the brain with decorin could possibly prevent the growth of cancer in humans, although further research is needed to confirm this.
Eczema and early-childhood infections involve T-cells, so we're looking into that.
"As we understand that T-cells communicate better with the cells that promote brain tumors, we'll be able to find more opportunities to intervene in the process."
Nature Communications published the study.
