ABSTRACT
The vagus nerve innervates most visceral organs.Upon activation,vagal efferents release acetylcholine,which influences organ function.In addition,vagal afferents convey information regarding the mechanical and chemical environment of the organ to the central nervous system (CNS).This bidirectional communication provides a mechanism for reflex regulation of the biological function of the organ.In the lung,the vagus nerve modulates airway tone,perfusion and secretion,in addition to its effects on breathing pattern.Recently,the vagus nerve has been recognized to play a role in the pathogenesis of lung disease via neuro-immune interactions.The vagus nerve has significant influences in pulmonary diseases,such as asthma,chronic obstructive pulmonary disease (COPD),acute respiratory distress syndrome (ARDS),pulmonary fibrosis and lung cancer.In disease,the nerve is activated by cytokines,chemokines,and other mediators from many cell types to convey immunologic information to the CNS,which may alter disease outcome.Activation of the vagus nerve also releases neuropeptides to modulate immune cell behavior and can evoke the cholinergic anti-inflammatory pathway that regulates lung inflammation.Understanding the role of the vagus nerve in neuro-immune interaction may contribute significantly to the clinical management of pulmonary diseases.