Testosterone worsens inflammation

A heart attack occurs when the supply of blood to the heart is blocked, causing damage to the heart muscle. This is followed by a strong inflammatory response, where neutrophils—a type of white blood cell—play a key role in making the injury more severe.

In experiments on mice, the researchers observed that the number of neutrophils in blood within the first few days of a heart attack was higher in males than in females. Further investigations showed that testosterone, which is present in significantly higher levels in males, speeds up the release of neutrophils from the bone marrow.

One of the lead researchers behind the study is Åsa Tivesten, professor of medicine at Sahlgrenska Academy at the University of Gothenburg and senior physician at Sahlgrenska University Hospital:

“We see that testosterone strengthens the inflammatory response in male mice, leading to more extensive heart injury. Testosterone plays a clear role in making inflammation worse following a heart attack”, says Åsa Tivesten.

Greater effect in men

The researchers also analyzed data from a clinical trial in which the anti-inflammatory drug tocilizumab was given to patients shortly after a heart attack. The analysis showed that the drug reduced neutrophil levels and decreased heart damage, with a significantly greater effect in men than in women.

“Our study shows how testosterone affects neutrophils through a mechanism that was previously unknown. The results illustrate the importance of considering sex differences in both research and healthcare. If these differences are overlooked, treatments may be less effective, especially for women, who are often underrepresented in studies”, says Åsa Tivesten.