POSTN and idiopathic pulmonary fibrosis: Periostin has been shown to be upregulated in the subepithelial region in asthma (10), AD (37, 49), allergic conjunctivitis (AC) (52), eosinophilic esophagitis (EoE) (31) and familial idiopathic pulmonary fibrosis (IPF) (47, 48).