Testosterone worsens damage caused by a heart attack

Testosterone worsens the damage caused by a heart attack by increasing the number of white blood cells released from the bone marrow, according to a new study led by the University of Gothenburg. The findings are published in the journal Nature Communications and may explain why damage to the heart muscle after a heart attack is more extensive in men than women.

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, a professor of medicine at Gothenburg’s Sahlgrenska Academy and senior physician at Sahlgrenska University Hospital. She said, “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.”

The researchers also analysed 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. The results are thus relevant for ongoing studies of anti-inflammatory drugs to treat heart attacks.

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

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