In evolution, stress ensured survival. But what was once life-saving could be life-threatening today. When the immune system of Stone Age humans kicked in after an injury, such as a sabre-toothed tiger bite, and the body formed useful small blood clots (microthrombi) to trap pathogens, stress hormones such as adrenaline could have helped.

Today, as head of a new DZHK junior research group, Dr. Kami Pekayvaz is investigating whether and how stress promotes thrombosis, i.e. harmful blood clots, in modern humans - and thus cardiovascular diseases such as heart attacks, strokes or pulmonary embolism.

The young doctor treats patients at the LMU Hospital in Munich and conducts research at the same time. "I often see patients here with heart attacks or other thrombotic diseases who have experienced acute stress, for example due to psychological strain. We know that stress and the associated hormones such as adrenaline increase the risk of such diseases. However, it is still unclear how exactly these hormones affect the immune system and thus promote thrombosis. Now I have the chance to get to the bottom of this experience from my everyday clinical work scientifically with my junior research group," says Pekayvaz. The DZHK is funding the junior research group for research into the adrenaline-neutrophil axis for the next six years with 1.65 million euros.

Neutrophils are important defense cells of the immune system that react quickly to infections, germ-free inflammation or environmental stress. At the same time, the body releases acute stress hormones such as adrenaline - known in technical jargon as catecholamines.

"A catecholamine-neutrophil axis could be of evolutionary significance in containing bacterial infections by means of thrombi in small vessels. On the other hand, under modern environmental stress, it could also cause harmful blood clots in large vessels, i.e. macrovascular thrombosis," says Pekayvaz. "This project offers the opportunity to better understand the role of the interaction between stress hormones and the immune system in thrombotic cardiovascular diseases," explains the researcher.

Kami Pekayvaz completed his medical studies in Munich with stays at the University of Oxford, among others. He completed his doctorate on atherosclerosis and has been researching the interface between inflammation and cardiovascular diseases at the LMU Clinic for years using the latest translational analysis methods.

"We are looking in vitro and in vivo - i.e. in the test tube and in animal models - at what happens when neutrophils and adrenaline come together. And we look at what happens when neutrophils cannot react to adrenaline because we block the receptors for these stress hormones," explains Pekayvaz. "We are interested in this: How do harmful vascular occlusions, i.e. venous or arterial thromboses, develop under these conditions? And what consequences does this have for bacterial sepsis, in which the immune system uses microthrombi to contain pathogens?"

Pekayvaz and his team of physicians, biologists and bioinformaticians at LMU University Hospital are using the latest techniques in single-cell analysis and microscopy as well as newly developed genetic mouse models. They analyze blood samples from patients with heart disease - thus creating a bridge between the laboratory and the clinic.