This model suggests that acid and bile reflux-induced damage to the oesophagus is ‘repaired’ by the expansion or selection of OSGs, which contain progenitors that may express OLFM4 and have alkaline secretions, and are thus able to play a role in protecting the oesophagus from gastro-oesophageal reflux damage. Here, OLFM4 is linked to bile reflux.