Neuroendocrine immune responses to inflammation: the concept of the neuroendocrine immune loop

Summary The neuroendocrine and immune responses to inflammatory stress represents an integrated circuit whose basis is reviewed in this chapter. Proinflammatory cytokines such as IL-1β, TNF-α, and IL-6 released from inflammatory foci initiate local anti-inflammatory mechanisms and travel via the blood stream to the brain where they trigger a variety of neuroendocrine counter-regulatory mechanisms. There is therefore an important neuroendocrine-immune loop in which stimulatory signals are received by the neural systems from inflammatory foci. These signals are transduced by the hypothalamus which initiates a complex hormonal cascade reaction aimed at modulating inflammation and returning the organism to normal physiological homeostasis once the trigger has been neutralized. Abnormalities in this cross-talk can profoundly influence the susceptibility to developing chronic inflammatory disease. Thus, in conclusion, the neuroendocrine-immune loop has important pathophysiological implications for disease processes.