Coughing, runny nose, fever, achy joints. These are some of the stereotypical symptoms of the flu. Every year during flu season, about 10% of people will come down with the illness. While most people just take a few days off from work, sleep, and drink lots of fluids to recover, the flu can be associated with much more severe disease. I’m sure we all remember the H1N1 outbreak a few years ago, and the severity that came with that. In that outbreak, as well as previous ones, it was shown that young adult women were more likely to experience severe outcomes associated with the disease than men. Interestingly, during the H1N1 outbreak in 2009, women were 2-6 times more likely to die from the infection than men.
This issue of gender differences in disease has long been of interest to Dr. Sabra Klein, Associate Professor in the Johns Hopkins School of Public Health. She has dedicated years of study to the issue, and recently made an exciting breakthrough that may aid in our treatment of women with influenza.
Dr. Klein’s lab published an article in the American Journal of Physiology - Lung Cellular and Molecular Physiology in late December. The study found that estrogen and estrogen-like compounds could reduce the level of flu virus replication in the human nasal epithelial cells of women, but not men. This seemed to be caused through the action of the genomic estrogen receptor 2. Notably, this reduction in virus level was not associated with an increased production of cytokines, but rather a decrease in cellular metabolism. Since cytokine storms are often associated with adverse outcomes for women with the flu, the fact that this antiviral effect was achieved without excess cytokines is very promising.
The flu virus isn’t the first disease that’s been found to be inhibited by estrogen. Replication of Human Immunodeficiency Virus (HIV), Hepatitis C, and even Ebola has been shown to be inhibited by estrogen. This raises the possibility of new treatments for these diseases. Select estrogen receptor modulators (SERMs) such as clomiphene and raloxifene are already approved by the FDA for treatment of osteoporosis and infertility. It is possible that someday, these or other similar drugs could be repurposed to treat the flu in women, along with these other viral infections. That would certainly be one small step for woman, one giant leap for man and womankind.