Gastroesophageal Reflux Disease and Airway Hyperresponsiveness: Mechanisms and Mediators Involved GERD and Asthma

Gastroesophageal reflux disease (GERD) is clearly explained as the unintentional passage of stomach contents through the esophagus that takes place many times during the day both in children and in adults. GERD leads to symptoms of heartburn and regurgitation, these defined esophageal symptoms are in dichotomy with extraesophageal symptoms of GERD. These extra-esophageal symptoms include several respiratory manifestations that include chronic cough, bronchoconstriction and inflammation of airway, main features of asthma. Asthma is a chronic disease defined by variable degree of airflow obstruction, bronchial hyper-responsiveness (AHR) and chronic airway inflammation. Recent papers demonstrated an association between GERD and asthma. There are a lot of mechanisms through GERD can alter the reactivity of airway and lead to bronchoconstriction. Two hypotheses are proposed to explain this effect and different mechanisms may be involved. However many authors suggest bidirectional effect between asthma and GERD. In fact, asthma can lead to onset of GERD through an increase of intrathoracic pressure during breathing and a reduction of lower esophageal sphincter (LES) pressure due to asthma therapy. The correlation between GERD and asthma is more complicated and has not yet been fully elucidated and understood, leaving this field of research open to further investigations.