Body-own healing processes after heart attack Scientists discover where the immune response comes from

After a heart attack, the immune system reacts quickly

Every year around 300,000 people in Germany suffer a heart attack. In the acute case, fast action is necessary. Timely help saves lives. Also, the body reacts quickly after an infarction to stimulate the healing process. Researchers have now found out where the immune response comes from.

Restore blood flow to the heart quickly

A heart attack is a dangerous event and can be fatal for those affected. In the acute case, rapid action is necessary to save lives and to avoid consequential damage. Thus, in an infarct, doctors need to restore blood flow to the heart as quickly as possible. But even the body reacts quickly after a heart attack to stimulate the healing process. Researchers at the Ludwig Maximilian University (LMU) Munich have now found out where this immune response comes from.

After a heart attack, the immune system must respond quickly to stimulate the healing process. Researchers have now found out where the immune response comes from. (Image: hriana / fotolia.com)

The immune system has to react quickly after a heart attack

After a heart attack, the immune system must respond quickly to stimulate the healing process.

Researchers led by Sabine Steffens, Professor of Clinical Pathobiochemistry at the Institute of Prophylaxis and Epidemiology of Circulatory Diseases (IPEK) at the LMU Hospital, have now identified the key site for activating the immune response to a heart attack.

There are clusters (accumulations) of lymphocytes, which are located in the so-called pericardial fatty tissue of the pericardium. The researchers currently report in the journal "Circulation".

Where the immune response is activated and controlled

"Clusters of lymphocytes are important sites for adaptive immune response and inflammatory surveillance," explains Sabine Steffens in a statement.

These clusters were first discovered in 2015 in several places in the adipose tissue of the body.

"They probably serve as local monitoring sites, so that the immune response starts as soon as possible."

The pericardial adipose tissue, located close to the heart muscle, has a very high density of lymphocyte clusters.

"After a heart attack, the immune response is activated and controlled," Steffens summarizes her study results.

Inflammatory reaction by neutrophils

It activates lymphocytes and liberates cytokines, which in turn cause other immune cells, the neutrophils, to migrate to the damaged heart muscle.

They initiate an inflammatory reaction there, through which the damaged tissue is broken down by immune cells.

Only last year, LMU physicians led by Prof. Steffens had shown in a study that the amount of neutrophils plays a key role in why heart attacks in the morning are much more dangerous.

"At the beginning of the active phase, more neutrophils are released from the bone marrow. In humans, their active phase is early in the morning. A heart attack at this time leads to an excessive inflammatory response by neutrophils, "Steffens said in a statement.

This worsens the chances of recovery, because as a result of the increased inflammation more scars form in the tissue and the heart muscle expands, which weakens the heart.

Therapeutic treatment of heart attacks

In their current study, Steffens' team was able to demonstrate for the first time in a mouse model the mechanism of how the clusters of lymphocytes in the pericardial adipose tissue control the immune response after a heart attack and what their crucial role in the healing process is.

In addition, the researchers evaluated data from patients with and without coronary heart disease in the study. In those with coronary heart disease, a higher concentration of lymphocytes was detected in the pericardial adipose tissue.

The new findings are also relevant for the therapeutic treatment of heart attacks. For example, changes in pericardial adipose tissue could have an impact on the healing process. (Ad)