Why women are more prone to asthma

Absence of testosterone in women may explain why females are doubly likely to develop asthma post-puberty, a finding that could lead to new treatments for the lung condition among women, research has showed.

The results of research in France revealed that the primary male sex hormone suppresses the production of a type of immune cell that triggers allergic asthma and acts as a barrier against males developing the inflammatory airway condition.

"Our research shows that high levels of testosterone in males protect them against the development of allergic asthma," said Cyril Seillet at the Physiopathology Centre of Toulouse-Purpan in France.

"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," Seillet said.

These innate lymphoid cells or ILC2s 'sense' testosterone and respond by halting production of the cells. "Testosterone directly acts on ILC2s by inhibiting their proliferation. So in males, you have less ILC2s in the lungs and this directly correlates with the reduced severity of asthma," Seillet said in a report published in the Journal of Experimental Medicine.

ILC2s are found in the lungs, skin and other organs. These cells produce 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. Understanding the mechanism that drives the sex differences in allergic asthma could lead to new treatments for the disease, the researchers said.