A new study published in the Journal of Experimental Medicine this month has reported some interesting results regarding testosterone and asthma. It has long been hypothesized that adult sex hormones, notably estrogen and testosterone, have impacted whether or not a person develops allergic asthma and how severe that asthma is.1 These questions have been driven by basic statistics surrounding asthma and its prevalence in the sexes. Asthma occurs more frequently in boys pre-puberty, however, that trend is flipped after maturation. Not only are women more likely to develop asthma post-puberty, but they are also more likely to develop severe symptoms. It has even been reported that death from asthma-related complications can be up to three-fold greater for women than men.2 The study in JEM sought to investigate these differences, and learn more about the reversal between the sexes before and after puberty.
“We have known for some time that asthma affects more women than men, despite it being more common in boys than in girls during childhood. Although there is evidence to suggest that this may be in part due to female hormones, we don’t yet have a good understanding of why anyone develops asthma, irrespective of sex or age.”
-Dr. Erika Kennington, Head of Research, Asthma UK2
Using mice models, the researchers hypothesized that the male hormone testosterone could suppress the development of a specific immune cell known to trigger asthma. These cells are called ILC2’s (group 2 innate lymphoid cells) and regulate the type two inflammatory pathway in the body, a pathway associated with asthma. These cells can also be found in the skin, lungs, and other organs, and have a special androgen receptor that may be the connection point between the sex hormones and their development. ILC2’s also produce inflammatory proteins in response to common asthma triggers like dust mites, cigarette smoke, pet hair, and pollen.
“Looking at how testosterone could affect asthma is an innovative area of research. However, this study was in mice and further investigation is needed to see whether the results can be replicated in humans before we can draw any solid conclusions.”
Although only tested with mice, the researchers determined that testosterone may shield these cells from proliferating, thus, decreasing the inflammatory response that produces asthma and its symptoms. The researchers also noted that removing the ovaries from female mice did not produce a significant effect, while removing the testicles of mice brought the sexes to a similar rate of asthma development. This indicates that the presence of testosterone could be the key factor. More research needs to be conducted to further strengthen this link and determine its relevance for humans. If this link continues to be strong, it could lead to the development of new, targeted therapies for asthma in the future.
Laffont S, et al. “Androgen signaling negatively controls group 2 innate lymphoid cells.”Journal of Experimental Medicine. 8 May 2017. Available from: http://jem.rupress.org/content/early/2017/05/05/jem.20161807
Russell, Peter. “Does testosterone help protect men from asthma?” Medscape. 9 May 2017. Available from: http://www.medscape.com/viewarticle/879724?nlid=114772_4503&src=wnl_dne_170510_mscpedit&uac=259022DR&impID=1344948&faf=1