Researchers have identified a beneficial immune response that occurs after injury to the central nervous system. By harnessing this response, researchers may be able to develop new and better treatments for brain and spinal cord injuries, and tools to predict how patients will respond to treatment, thus improving treatment of degenerative conditions.
The newly-discovered immune response occurs independently of the process that typically spurs the immune system into action. In this process, the body identifies and attacks antigens such as bacteria and viruses. “What we have shown is that the injured central nervous system talks to the immune system in a language that has not been previously recognised in this context,” said Jonathan Kipnis, Department of Neuroscience at the UVA School of Medicine and director of the Center for Brain Immunology and Glia. “It sends danger signals and activates the immune system very rapidly. These danger signals cause immune cells to produce a molecule called interleukin 4, which happens to be indispensable for immune mediated neuroprotection after central nervous system trauma.”
Interleukin 4 helps protect the body’s neurons and promote their regeneration, whereas uncontrolled inflammation can destroy them. As such, understanding how the body responds to damage to the central nervous system is critically important.
“Once CNS neurons die, they are gone for life. They don’t come back. So I think the central nervous system has evolved along with the immune system to respond in this protective fashion,” explained UVA’s James T Walsh, the lead author of the paper outlining the discovery. “[The immune system in the central nervous system] has to be very metered with how it responds. It cannot attack everything like it does in a lot of other tissues, because it causes a lot of collateral damage. You really need the right kind of response. It can be a double-edged sword. The immune system can cause damage to the central nervous system, but it can also be beneficial, and we are showing here how it is beneficial.”