Men, however, are the weaker sex – at least in terms of resistance. Canadian research has just shown, that the female sex hormone, estrogen helps women fight infections better. Information on this subject is provided in the letter “Proceedings of the National Academy of Sciences”. Doctors have been watching for a long time, that women fight infections better and recover faster. In their latest work, researchers at McGill University in Montreal provide an explanation for this phenomenon. The research looked at an enzyme called caspase-12, which inhibits inflammatory processes, being the body's first line of defense against infections. The active caspase-12 gene is present in all known mammals. However, in the course of human evolution, a mutation appeared in him, which makes, that the gene doesn't work in most people. Only 20 proc. people with African roots do not have this mutation. They produce active caspase-12 and are more prone to infections and sepsis. Mice lacking the caspase-12 gene are extremely resistant to infection. Canadian researchers have changed rodents this way, that they began to produce an unmutated variant of the human caspase. Turned out, that thanks to this change, males' resistance to Listeria monocytogenes infections was significantly reduced. However, this had a minimal effect on the female immunity. The analysis showed, that it was estrogen that inhibited female caspase-12 production. Scientists even found the exact place, in which the hormone binds to the caspase gene, blocking its activity.
Injecting male estradiol also inhibited enzyme production and increased their resistance to infection. Since the experiments were performed with the human gene, scientists believe, that the results of their research also apply to humans. In their opinion, it proves it, that women have a stronger inflammatory response than men in response to infections, so they can defend themselves better. This trait of the female immune system may have evolved because of its key role in childbearing and caring. Researchers count, that their discovery will help find new ways to strengthen immunity in humans.
