Why do more women have asthma than men? Blame hormones

November 28, 2017, Cell Press
Obstruction of the lumen of a bronchiole by mucoid exudate, goblet cell metaplasia, and epithelial basement membrane thickening in a person with asthma. Credit: Yale Rosen/Wikipedia/CC BY-SA 2.0

Women are twice as likely as men to have asthma, and this gender difference may be caused by the effects of sex hormones on lung cells. Researchers at Vanderbilt University and Johns Hopkins found that testosterone hindered an immune cell linked to asthma symptoms, such as inflammation and mucus production in the lungs. The study in human cells and rodents appears November 28 in the journal Cell Reports.

"When we started this study, we really thought that ovarian hormones would increase inflammation, more so than testosterone making it better," says senior author Dawn Newcomb, of the Vanderbilt University Medical Center. "I was surprised to see that testosterone was more important in reducing inflammation."

Prior studies have found that, before puberty, boys have approximately 1.5 times higher rate of than girls (DOI: 10.1016/j.jaci.2015.05.046). That trend reverses after puberty, when women are twice likely to have asthma as men. This pattern continues until women hit menopause, and then the asthma rates in women start to decline. Increased are regulated by many different factors, including exposure to allergens and viral infections, and the researchers suspected that sex hormones might also be involved.

Newcomb and her colleagues looked at human and to further study the trend in gender differences that they had observed. They focused on called Group 2 , or ILC2 cells. These cells make cytokines, proteins that cause inflammation and mucus production in the lungs, which makes it harder to breathe. The researchers collected blood from people with and without asthma and found that those with asthma had more ILC2 cells than those without. Of that group, asthmatic women had more ILC2 cells than asthmatic men.

ILC2 cells are also found in the lungs of mice, but they are rare. They make up only about 10,000 of the 10 million cells in a mouse lung. Similar to the results that they found in humans, Newcomb and colleagues always found that they were getting fewer cells from male mice than female mice. They used these mouse cells to experiment with the effects of hormones on ILC2 cells.

When the researchers added ovarian hormones, like estrogen and progesterone, to the ILC2 cells, they did not see much of a change or increase in the ability of the cell to make cytokines. However, when they added testosterone, they saw that the hormone prevented the from expanding and reduced the production of cytokines.

While this study focused on testosterone, Newcomb hopes to expand further studies to explore the effects of more on asthma. "Sex hormones are not the only mechanism but, rather, one of many mechanisms that could be regulating airway inflammation," she says. "This is not the only important mechanism in asthma."

Explore further: Testosterone explains why women more prone to asthma

More information: Cell Reports, Newcomb et al.: "Testosterone attenuates group 2 innate lymphoid cell-mediated airway inflammation" http://www.cell.com/cell-reports/fulltext/S2211-1247(17)31590-5 , DOI: 10.1016/j.celrep.2017.10.110

Dawn C. Newcomb et al. Estrogen and progesterone decrease let-7f microRNA expression and increase IL-23/IL-23 receptor signaling and IL-17A production in patients with severe asthma, Journal of Allergy and Clinical Immunology (2015). DOI: 10.1016/j.jaci.2015.05.046

Related Stories

Testosterone explains why women more prone to asthma

May 8, 2017
An international research team has revealed for the first time that testosterone protects males against developing asthma, helping to explain why females are two times more likely to develop asthma than males after puberty.

Strategy for depleting immune cells implicated in asthma-associated inflammation

May 19, 2016
Patients with asthma have chronic lung inflammation that results in sporadic narrowing of the airways and difficulty breathing. Symptoms and severity are variable among individuals; however, the cells and inflammatory factors ...

Immune and nerve cells work together to fight gut infections

September 7, 2017
Nerve cells in the gut play a crucial role in the body's ability to marshal an immune response to infection, according to a new study from Weill Cornell Medicine scientists.

Man flu is real, but women get more autoimmune diseases and allergies

August 7, 2017
Men and women respond differently to diseases and treatments for biological, social and psychological reasons. In this series on Gender Medicine, experts explore these differences and the importance of approaching treatment ...

Scientists unearth cell 'checkpoint' that stops allergic diseases

August 9, 2017
Scientists from Trinity College Dublin have made a significant breakthrough in understanding the regulation of immune cells that play a pivotal role in allergic diseases such as asthma and eczema. They have identified a 'checkpoint' ...

Drug target for asthma discovered

May 13, 2015
The over-active immune cells responsible for asthma depend on the gene BCL11B to develop into mature cells, according to a study published in the Journal of Experimental Medicine. The identification of this gene's role could ...

Recommended for you

A bad influence—the interplay between tumor cells and immune cells

October 16, 2018
Research at Huntsman Cancer Institute (HCI) at the University of Utah (U of U) yielded new insights into the environment surrounding different types of lung tumors, and described how these complex cell ecosystems may in turn ...

New immunotherapy targeting blood-clotting protein

October 15, 2018
Normally, the blood protein fibrin does not enter the brain. But in several neurological disorders, the blood-brain barrier—which keeps large molecules in the blood from entering the brain—becomes abnormally permeable, ...

Function of neutrophils during tumor progression unraveled

October 15, 2018
Researchers at The Wistar Institute have characterized the function of neutrophils, a type of white blood cells, during early stages of tumor progression, showing that they migrate from the bone marrow to distant sites and ...

Immune health maintained by meticulously ordered DNA

October 15, 2018
Walter and Eliza Hall Institute researchers have revealed how immune health is maintained by the exquisite organisation skills of a protein called Pax5.

Enzyme that triggers autoimmune responses from T-cells in patients with MS found

October 11, 2018
A team of researchers from Switzerland, the U.S. and Spain has isolated an enzyme that triggers an autoimmune response from T-cells in patients with MS. In their paper published in the journal Science Translational Medicine, ...

Scientists reveal new cystic fibrosis treatments work best in inflamed airways

October 11, 2018
A new UNC School of Medicine study shows that two cystic fibrosis (CF) drugs aimed at correcting the defected CFTR protein seem to be more effective when a patient's airway is inflamed. This is the first study to evaluate ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.