For a long time scientists have been trying to understand why females are more likely than males to develop autoimmune diseases. From the University of Gothenburg, scientists investigate the disproportionate prevalence of autoimmune disease and offer a new, hormone-related theory for female vulnerability.
"It's very important to understand what causes these diseases to be so much more common among women," explained study author Asa Tivesten. This is especially true in the case of lupus, where 90 percent of those affected are women. "In this way, we can eventually provide better treatment for the diseases."
The new study operates under the theory that testosterone provides protection against autoimmune disease. Women have just ten percent of the testosterone that men do, implying that they likely do not receive the same protective effects.
A recent University of Turku study found that estrogen also plays a role in women being more prone to autoimmunity. As opposed to testosterone, women produce a lot more estrogen than men do. Researchers found that estrogen receptor proteins cause dysfunction in regulatory T cell activity. These are cells that maintain the balance between too much inflammation and too little inflammation, and they are often implicated in autoimmune disease pathology.
In the new study, researchers observed testosterone reducing the number of B cells, which produce antibodies. B cells and antibodies are part of the adaptive immune system where, along with T cells, they produce a specific response to bacterial or viral infections. Antibodies are useful during an immune attack on invading pathogens, but when B cells produce antibodies that attack the body’s own cells - called autoantibodies - autoimmune diseases can develop.
Researchers looked specifically at the relationship between testosterone and B cell production in the spleen, taking and analyzing blood samples from 128 men. They found that testosterone suppress activity of a protein called BAFF, which promotes B cell viability.
Similarly, past research has showed that genetic variations in BAFF increase the risk of autoimmune diseases. This includes lupus, which is treated in part with BAFF inhibitors.
“If you eliminate testosterone, you get more BAFF and thereby more B cells in the spleen because they survive to a greater extent,” Tivesten explained. “Recognition of the link between testosterone and BAFF is completely new. No one has reported this in the past.”
The present study was published in the journal Nature Communications.
Source: University of Gothenburg