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.

Lung cancer is a major medical problem. Despite advances in molecular biology and pharmacology, the outcome of lung cancer treatment is unsatisfactory. Clinically, inflammation and cancer are closely associated, and, genetically, these two processes are regulated by the same gene loci. Inflammation promotes cancer formation. Increasing evidence shows that neuroimmune interaction involving inflammatory disease and the vagus nerves are crucial in the interaction. Airway sensory receptors are biosensors that detect the lung inflammatory process through various mediators and cytokines. This information is transmitted through vagal afferents to the brain and produces a host of responses that regulate the extent and intensity of inflammation. Tumor cells express receptors for neurotransmitters and provide a substrate for direct interaction with neurons. Thus, neural regulation of the immune response is targeted towards inflammation as well as tumors. The airway sensors can detect cancer-related cytokines, which provides a direct pathway to inform the brain of tumor growth. The knowledge of how these sensors may monitor tumor progression and provide neuroimmune interaction in the control of tumor development and metastasis will improve our treatment of lung cancer.
Carcinogenesis ; Cytokines ; physiology ; Humans ; Inflammation ; pathology ; Lung ; innervation ; pathology ; Lung Neoplasms ; pathology ; Sensory Receptor Cells ; physiology ; Vagus Nerve ; physiology