TFF2 and gastroesophageal reflux disease: In a previous study, we established a guinea pig model with GER by performing repeated esophageal HCl perfusion and observed increased plasma leakage and neuropeptides, such as SP, neurokinin A (NKA), and NKB in lung tissues (Liu et al., 2013), and also the airway hyperresponsiveness and remodeling could be induced (Cheng et al., 2014).