Department of Vascular Cell Biology
When the immune system comes to the rescue
One heedless moment, a stabbing pain – and you’ve got a rusty nail in your finger. Now your immune system must rush to respond and stop the rapidly proliferating microbes from causing serious infection. As fast as possible, your immune cells must recognize that they have to leave the vascular system and migrate from your blood into the injured tissue to destroy the pathogens.
To achieve this, the immune cells carry out a particularly sophisticated ‘dragnet search’, as Dietmar Vestweber and his team discovered. Wherever inflammation occurs in the body, the inner cell lining of the blood vessels – the endothelium – changes. Suddenly proteins otherwise not found there appear on the surface. And these proteins are what the immune cells target: As soon as they come into contact with them, they stick so tightly to them that they cannot be washed away in the rapidly flowing blood.
The researchers are also beginning to understand how immune cells migrate through the endothelium to reach the source of the inflammation. Findings of MPI scientists indicate that endothelial cells, in order to facilitate immune cell migration, open and shut the specific junctions connecting them in Velcro-like interactions. The immune cells supply the code for this: Once they dock, the endothelium starts the opening process. In future studies, researchers want to elucidate how the body regulates this process. One thing is certain: If inflammation processes like rheumatoid arthritis and multiple sclerosis get out of control, even healthy tissue is not safe from attacks by the immune cells.