Neural regulation of innate immunity: a coordinated nonspecific host response to pathogens

Evidence for crosstalk between the central nervous system and innate immune cells is accumulating. As discussed by Esther Sternberg, neural factors that first amplify and then temper pro-inflammatory responses have a crucial role in pathogen defence and in preventing toxic shock. The central nervous system (CNS) regulates innate immune responses through hormonal and neuronal routes. The neuroendocrine stress response and the sympathetic and parasympathetic nervous systems generally inhibit innate immune responses at systemic and regional levels, whereas the peripheral nervous system tends to amplify local innate immune responses. These systems work together to first activate and amplify local inflammatory responses that contain or eliminate invading pathogens, and subsequently to terminate inflammation and restore host homeostasis. Here, I review these regulatory mechanisms and discuss the evidence indicating that the CNS can be considered as integral to acute-phase inflammatory responses to pathogens as the innate immune system.