How psychological stress affects the immune system
Stress at work or at home can make us more susceptible to infections or cancer. Immunologists at the Leibniz Research Centre for Working Environment and Human Factors (IfADo) are investigating how stress affects the immune system in detail. In a new research project, they are focusing the basics of how a group of neurotransmitters involved in stress reactions influences the function of certain immune cells. The project is funded by the German Research Foundation (DFG) for the next three years.
Our nervous system and the immune system can influence each other. Both systems use certain messenger substances for this purpose – neurotransmitters in the case of the nervous system. Since the cells of the immune system express docking sites (receptors) for neurotransmitters, the nervous system can influence the immune response. For example, permanent stress or sleeping disorders can make us ill, while acute stress (e.g. before an exam) can activate the immune system. However, the molecular details of this interaction between psychological stress and immune cells are not yet sufficiently understood.
Project start: Sympathetic nervous system and NK cells in focus
In a new project, IfADo researchers are therefore investigating the basics how catecholamines – neurotransmitters involved in the stress response – influence the function of natural killer cells (NK cells). These are immune cells that can kill virus-infected cells or tumor cells immediately on first contact. It is known that NK cells have receptors for catecholamines such as dopamine, noradrenaline and adrenaline. These neurotransmitters are released during psychological stress, for example, when the sympathetic/autonomous nervous system has been activated. This system is responsible for the rapid physical and mental reaction in stressful situations. Catecholamines are therefore a substance class frequently used in intensive care and emergency medicine. „In the project we will investigate the hypothesis that stress regulates the activity of NK cells via the sympathetic nervous system,“ explain IfADo-project leaders Prof. Dr. Carsten Watzl and Prof. Dr. Silvia Capellino.
In preliminary cell culture experiments, they were already able to show that acute treatment with norepinephrine or dopamine inhibits the NK cells‘ ability to kill other cells. Norepinephrine also suppressed signals that are important for the NK cells to be able to enter diseased tissue from the blood. However, none of these signals were suppressed during long-term, chronic treatment with norepinephrine.
The project team will now investigate the physiological significance of these cell culture results. The focus will be on the signals that are triggered in NK cells by treatment with norepinephrine and dopamine. In addition, the project team will determine how these signals precisely influence the immune functions of NK cells.
Effects of acute and chronic stress
„We want to better understand the molecular mechanisms of how acute and chronic stress affects the immune system. This might also lead to new biomarkers in future that can indicate the effect of stress on the immune system. However, we still have to carry out many experiments and investigate the effects of catecholamines on numerous other immune cells,“ note Prof. Watzl and Prof. Capellino. In addition, the new findings have a certain relevance for drug development in the long term since catecholamines are components of many drugs, for example for the stabilization of the circulatory system or in severe allergic reactions.