By deciphering the cell migration mechanism behind the immune response, scientists at the University of Geneva (UNIGE) in Switzerland and the University of Munich (LMU) in Germany have proven that the activation of the immune system depends on time and Affected by the biological clock. For the human body, the immune function is strongest when it is resting, that is, before a day of activities in the morning. The research results were published in the journal Nature Immunology on the 18th. Research suggests that when vaccinating cancer vaccines or performing immunotherapy, time should be considered in order to improve effectiveness.
The immune system has two branches, the innate immune system and the adaptive immune system. The innate immune system responds immediately to common pathogens. The adaptive immune system takes several weeks to form a long-term precise response to specific pathogens that the body has been exposed to. This is also a typical mechanism by which the immune system plays a role during vaccination.
The lymphatic system is one of the pillars of the adaptive immune response. Dendritic cells are located in many peripheral immune organs, including skin. They migrate through lymphatic vessels to lymph nodes and present antigens to trigger an immune response to pathogens. To understand the role of circadian rhythm in immune activation, the researchers observed the migration of dendritic cells from the skin to the lymphatic system.
The scientists first observed the migration of dendritic cells in wild mice 4 times a day, and then observed mice without a normal biological clock. In order for cells to migrate correctly, both dendritic cells and lymphatic cells must respond to circadian rhythms. If there is no biological clock to play a role, the activity peak of the immune system will no longer appear, and it will continue to work “slowly”.
Subsequently, the researchers repeated experiments on human skin cells at different times of the day. Christoph Sherman, a professor at the Department of Pathology and Immunology at UNIGE and the Geneva Center for Inflammation Research, who led the research, said that we have identified many molecules, especially chemokines, which are involved in the migration process and their expression is regulated by the biological clock. . The same factors that are regulated by the circadian clock and participate in the migration process have been found in human and mouse cells, especially chemokines. The activity of the factors varies according to the living habits of different species. This confirms that the immune system controls the rhythm of activities according to the natural activity of the day and night alternation.
Data shows that the peak of the immune system’s activity in the day is in the morning. Sherman said: “The circadian rhythm is an energy-saving system that can make full use of energy according to the most urgent needs. When the risk of exposure to pathogens is greatest, is this a way for the immune system to stay alert? Similarly, Will we be more susceptible to pathogens in the evening and at night? It is still unclear. However, the importance of the circadian rhythm to the immune system has just been revealed, which is useful for preventive vaccination and anti-cancer treatment or autoimmune diseases. The management of all may be important.”
Life on Earth generally has a set of built-in clocks that regulate physiological activities in a 24-hour cycle to adapt to the rotation and day-night changes of our planet. Taking the circadian rhythm as an example, it has a very precise impact on our physiological functions at different times of the day, helping humans to prepare for various daily functions. Scientists have been fascinated by the working mechanism of circadian rhythm for a long time, and even considered the relationship between this mechanism and disease, but this is the first time to reveal in detail its huge impact on the immune system. Perhaps in the future, the research on the “internal clock” will go deep into the pathogenesis of the disease and individual treatment.