Scientists from Harvard University have found that females are more naturally resistant to respiratory infections than males, implying that men may be more likely than women to suffer from pneumonia and other diseases.
In a study published in the journal eLife, a team led by Professor Lester Kobzik at the Harvard University School of Public Health found that increased resistance to bacterial pneumonia in female mice is linked to the enzyme nitric oxide synthase 3 (NOS3), activated by the female sex hormone estrogen.
The researchers introduced Streptococcus pneumoniae into the lungs of mice to mimic the inhalation of bacteria that occurs naturally as we breathe and found that female mice were able to clear the bacteria from their lungs more rapidly than male mice. The team also discovered that male mice treated with estrogen matched the ability of females to clear the bacteria from their lungs.
Female mice defences were also better at killing off Escherichia coli , Staphylococcus aureus, and Streptococcus pneumoniae when tested in vitrio.
The scientists followed up these results by deleting the gene responsible for the production of the NOS3 enzyme in another set of male and female mice, and found that this resulted in neither sex being resistant to infection.
Discussing the results and applications of the study, Kobzik said:
“Ultimately, this work could be especially useful in reducing risk of secondary bacterial pneumonias during seasonal or pandemic influenza. We were quite pleased that the work led us to NOS3-targeting drugs that are already available and that can indeed improve resistance to pneumonia in our mouse model.”