Role of nerves in asthmatic inflammation and potential influence of gastroesophageal reflux disease.

Inflammation of the lower airways is a defining characteristic of asthma. Microaspiration of refluxate may initiate an inflammatory response in the airways of patients with gastroesophageal reflux disease (GERD), thereby precipitating asthma. Airway nerves are likely to play a role in the pathogenesis of asthma and could potentially mediate airway inflammation initiated by GERD through axonal reflexes. Alternatively, refluxate may initiate airway reflexes from the esophagus that are markedly exaggerated by inflammation-induced enhancement of airway neuronal excitability. The characteristic features of inflammation in asthma are defined, and the potential role of nerves in inflammation is discussed. Mechanisms by which GERD may initiate airway inflammation or act synergistically with airway inflammation to produce asthma also are discussed.