New Australian research has discovered testosterone inhibits the development of asthma, explaining why women are more susceptible to the lung disease.
The hormone testosterone plays a vital role in a man's sex drive, and now new research has found it can protect them against asthma too.
Scientists at Melbourne's Walter and Eliza Hall Institute of Medical Research says the discovery helps to explain why females are two times more likely to develop the lung disease than males after puberty.
"We identified that testosterone is a potent inhibitor of innate lymphoid cells, a newly-described immune cell that has been associated with the initiation of asthma," said Dr Cyril Seillet from the institute.
One in nine Australians, around 2.5 million people, have asthma - a disease that causes inflammation of the airways making it difficult to breathe during an attack.
In adults, asthma is two times more prevalent and more severe in women than men, despite more being more common in boys than girls before puberty.
A study, published in the Journal of Experimental Medicine, found high levels of testosterone in males protect them against the development of allergic asthma by inhibiting the production of immune cells known as ILC2s.
"Testosterone directly acts on ILC2s by inhibiting their proliferation," Dr Seillet said. "So in males, you have less ILC2s in the lungs and this directly correlates with the reduced severity of asthma."
ILC2s are found in the lungs, skin and other organs and are responsible for the production of inflammatory proteins that can cause lung inflammation and damage in response to common triggers for allergic asthma, such as pollen, dust mites, cigarette smoke and pet hair.
Immunologist Professor Gabrielle Belz says understanding the mechanism that drives the sex differences in allergic asthma could lead to new treatments.
"Current treatments for severe asthma, such as steroids, are very broad based and can have significant side effects," Professor Belz said.
"This discovery provides us with a potential new way of treating asthma, by targeting the cells that are directly contributing to the development of allergic asthma," she added.
While more research is needed, findings open up the possibility of mimicking this hormonal regulation of ILC2 populations as a way of treating or preventing asthma.
"Similar tactics for targeting hormonal pathways have successfully been used for treating other diseases, such as breast cancer," said Prof Belz.