Researchers at the Institute of Science and Technology Austria (ISTA) have made discoveries about how immune cells navigate complex environments, challenging previous notions and revolutionizing understanding of the immune system. The study reveals that immune cells actively create their own guidance system for efficient navigation, contrary to earlier beliefs.
Image credit: flickr.com (User:Sun)
How Do Immune Cells Know Where to Go?
The immune system defends the body against threats like germs. One critical aspect of this involves the coordinated movement of immune cells during infections. Dendritic cells (DCs) are essential players in the immune response, acting as messengers between the initial innate response and the adaptive response. They scan tissues for intruders, and when they detect an infection, they migrate to lymph nodes to initiate the next steps. Traditionally, it was believed that DCs and other immune cells followed external chemical gradients (chemokines) to navigate. However, new research challenges this idea.
The Role of CCR7: More Than Just Sensing
Researchers at ISTA revealed the intriguing dual role of CCR7 found on activated DC's in immune cell migration: not only does it sense chemokines but also actively generates and modulates chemotactic gradients. This mechanism allows immune cells to orchestrate collective migration and adapt to varying environments. As DCs move, they absorb and internalize chemokines through CCR7, reducing the local chemokine concentration. With fewer signalling molecules around, they move toward higher concentrations, effectively creating their own guidance cues. The more cells there are, the sharper the chemokine gradient they generate, emphasizing the collective nature of this phenomenon.
Evolutionary Perspectives and Future Investigations
The study raises questions about the evolutionary significance of chemokine decoy receptors that lost G protein signalling but retained internalization capacity. Understanding how immune cells collectively create and sense chemokine gradients could have far-reaching implications in processes like wound healing, tissue renewal, and immune surveillance.
Phago'Citations':
1. Jonna Alanko, Mehmet Can Uçar, Nikola Canigova, Julian Stopp, Jan Schwarz, Jack Merrin, Edouard Hannezo, Michael Sixt. CCR7 acts as both a sensor and a sink for CCL19 to coordinate collective leukocyte migration. Science Immunology, 2023; 8 (87) DOI: 10.1126/sciimmunol.adc9584
2. Institute of Science and Technology Austria. "Immune cells shape their own path." ScienceDaily. ScienceDaily, 1 September 2023. <www.sciencedaily.com/releases/2023/09/230901143610.htm>
Comments