For instance, in healthy lungs, peri-bronchial ECs are restricted to the bronchial vasculature in large airways, while in idiopathic pulmonary fibrosis (IPF), peri-bronchial ECs (characterized by high COL15A1 expression) were enriched in IPF lungs, in particular in areas of bronchiolization and fibrosis [114]. Here, COL15A1 is linked to idiopathic pulmonary fibrosis.