Cytokines and the immunomodulatory function of the vagus nerve.

Cytokine synthesis and release is an essential component of the innate immune system, but inappropriate, excessive production results in a generalized systemic inflammatory response which damages distant organs. Recent research has identified an immunomodulatory function of the vagus nerve whereby activation of the efferent arm results in regulation of cytokine production. Termed the 'cholinergic anti-inflammatory pathway', this neuro-immune communication provides the host with a fast, discrete, and localized means of controlling the immune response and preventing excessive inflammation. Stimulation of the vagus nerve attenuates cytokine production and improves survival in experimental sepsis, haemorrhagic shock, ischaemia-reperfusion injury, and other conditions of cytokine excess and research is now underway in developing new and novel therapeutics aimed at stimulating the vagus nerve either directly or targeting specific components of the pathway.