According to statistics, in women, asthma occurs twice as often as in men. However, there are several age nuances in this statistic.
If you look at children, there will be one and a half times more boys with asthma, and only after puberty the number of women asthmatics begins to grow. Finally, with the onset of menopause, asthma in women begins to occur less and less. It is quite obvious that the whole thing is about hormones: before puberty, the hormones in humans are one, in the reproductive age – the other, and women then withstand another hormonal shake when the time of menopause comes up.
Asthma arises due to the hypertrophic response of immune cells (the so-called congenital lymphoid cells of the second type), which sit in the tissues of the lungs. There are few of them (if you take mice, they will be only 10 thousand per 10 million other lung cells), but their function is extremely important: they must protect the body from pathogens that we can breathe in with the air.
However, sometimes it happens that they launch a strong defensive reaction in response to completely harmless particles. These cells go into the blood, so that their number can be estimated approximately, without climbing into the lungs. And researchers from Vanderbilt University and Johns Hopkins University compared their number in the blood of men and women with asthma – and it turned out that women really have a lot more.
Then they turned to experiments with mouse immune cells in order to compare how they multiply depending on the age of the individual. It was found that the pulmonary immune cells that trigger asthma attacks in females are dividing more actively, and they are just as actively dividing in immature mice, regardless of their gender.
It goes without saying that the whole thing is testosterone. Indeed, as stated in an article in Cell Reports, 5α-dihydrosterone – which is formed in the tissues of the male body from testosterone – reduces the number of “asthmatic” immune cells and at the same time suppresses the synthesis of signal proteins in them, with which they trigger a protective reaction.
In general, the hormone generally reduced in the lungs the concentration of many molecules involved in the inflammatory response, and reduced the number of other immune cells that participate in it. In other words, testosterone and its derivative literally do not allow the immune system to begin full-fledged asthma, which is why sexually mature men are less likely to suffer from it.
But why does the number of women with asthma fall during menopause? The same authors, two years ago, published the Journal of Allergy and Clinical Immunology another article in which they wrote that the female hormones estrogen and progesterone make immune cells more sensitive to molecular signals that work in asthma.
With the onset of menopause, the hormonal background in the female body changes, in particular, the synthesis of estrogenic hormones stops, and it is possible, therefore, for women, the probability of asthma decreases with age.