The vagal immune reflex: a blessing from above.

The innate immune response is activated upon recognition of infection or injury. A tight regulation of this inflammatory response is vital to ensure that it does not spin out of control and becomes harmful to the host. Recently, a neural circuit has been identified that controls the inflammatory response in a reflex-like manner. This circuit involves the vagus nerve which is able to sense inflammation and to respond to it by releasing acetylcholine which, through an interaction with immune cells, dampens the inflammatory response. The current knowledge regarding this "vagal immune reflex" is discussed with an emphasis on its role in sepsis.