Researchers seek a detailed look at the link between stress and the immune system

A team is investigating how some semiochemicals involved in the body's "fight-or-flight reaction" impact immune cells. They aim to further explain how stress can make humans more susceptible to infections or cancer.

A greater focus is placed on the sympathetic nervous system and natural killer cells

Stress can make us more susceptible to infections or cancer. The detailed look at the process through which stress affects the immune system is the subject of a new research project by immunologists at the Leibniz Research Centre for Working Environment and Human Factors, Technical University Dortmund, Germany (German acronym: IfADo). The team is investigating the basics of how a group of semiochemicals involved in the body's "fight-or-flight reaction" influences the function of immune cells.

In a new project, IfADo researchers are investigating the basics of how catecholamines influence the function of natural killer cells (NK cells). It is known that NK cells have receptors for catecholamines such as dopamine, noradrenaline, and adrenaline. These “messenger substances” (semiochemicals) are released during psychological stress, for example, when the sympathetic nervous system has been activated. This is responsible for a rapid physical and mental reaction in stressful situations.

"During the project, we will investigate the hypothesis that stress regulates the activity of NK cells via the sympathetic nervous system", explain the IfADo project leaders Prof. Dr. Carsten Watzl and Prof. Dr. Silvia Capellino.

Acute treatment with noradrenaline or dopamine inhibits the ability of NK cells to attack

The IfADo team has already been able to demonstrate in preliminary cell culture experiments that acute treatment with norepinephrine or dopamine inhibits the NK cells' ability to attack. Noradrenalin also suppressed signals that are important for the NK cells to be able to penetrate diseased tissue from the blood. However, none of these signals were suppressed during long-term, chronic treatment with noradrenalin, probably due to the inactivation of the receptor.

The project team will now investigate the physiological significance of these cell culture results. The focus will be on the signals triggered by treatment with norepinephrine and dopamine in NK cells. In addition, the researchers want to determine how these signals precisely influence the defense functions of NK cells.

Effects of acute and chronic stress

"Among other things, we would like to better understand the molecular mechanisms by which acute and chronic stress affects the function of NK cells. This could also lead to the definition of new biomarkers that can indicate the effect of stress on the immune system. In order to do so, however, we still have to carry out many experiments and also investigate the effects of catecholamines on numerous other immune cells," summarised Prof. Watzl and Prof. Capellino.

In addition, the new findings have a certain long-term relevance for drug development because catecholamines are a substance class that is frequently used in intensive and emergency medicine and are a component of many drugs that are used, for example, to stabilize the circulation or in severe allergic reactions.