In particular, a population of peri-bronchial venous EC expressing COL15A1, and referred as “systemic venous” (SV EC), has been shown to expand in areas of bronchiolization and fibrosis in IPF patients, while this EC subtype was restricted to the bronchial vasculature in healthy lungs15,16. The gene discussed is COL15A1; the disease is idiopathic pulmonary fibrosis.