An Australian research team has contributed to experimental studies that help explain why women have twice the rate of asthma as men.

The research showed male sex hormones influence Group 2 innate lymphoid cells (ILC2s) – relatively recently described as key regulators of type 2 inflammatory responses.

Male mice had reduced numbers of ILC2 progenitors and mature ILC2s in peripheral tissues compared with females.

“Testosterone directly acts on ILC2s by inhibiting their proliferation,” Walter and Eliza Hall Institute researcher Dr Cyril Seillet said. “So in males, you have less ILC2s in the lungs and this directly correlates with the reduced severity of asthma.”

Androgens also limited the capacity of ILC2s to expand locally in response to IL-33 mediated lung inflammation.

In an uncomfortable finding, orchiectomy eliminated the sex differences in ILC2 development and restored IL-33–mediated lung inflammation.

The researchers were optimistic about the knowledge leading to more targeted asthma treatments.

“While more research needs to be done, it does 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,” they said.