Estrogen dramatically reduced the amount of flu virus that replicated in infected cells from women but not from men, a new study by researchers at the Johns Hopkins Bloomberg School of Public Health shows.
The findings, reported online last week in the American Journal of Physiology – Lung Cellular and Molecular Physiology, suggest a protective advantage to the quintessential female hormone that naturally circulates in women’s bodies, as well as artificial forms given for hormone replacement therapy and estrogen-like chemicals found in the environment.
Recent studies have shown that estrogen can hamper replication of viruses including HIV, Ebola and hepatitis, which can lessen an infection’s severity and make an infection less likely to spread to other people. But the new study’s leader, Dr. Sabra L. Klein, an associate professor in the departments of molecular microbiology and immunology and biochemistry and molecular biology at the Bloomberg School, says it was unknown whether estrogen might have the same effect on the flu virus.
To investigate, she and her colleagues collected cells from the nasal passage — typically the first cells in the body to get infected with the flu — from female and male volunteers. The researchers exposed batches of these cells to different types of estrogens, including normal levels of naturally occurring estrogen, different types of selective estrogen receptor modulators (SERMs, synthetic estrogen-like chemicals used for hormone replacement therapy and infertility treatment, among other uses) or bisphenol A, an estrogen-like chemical found in many plastics. They then exposed cells to the influenza A virus, a variant of the flu virus that circulates each year during the flu season.