ACE-2 is a counter-regulatory enzyme of ACE [56]; specifically, during chronic hypoxemia (typical in severe BPD), ACE is upregulated while ACE-2 is downregulated, tipping the balance towards the pro-inflammatory (pro-fibrotic) effects, thereby promoting vascular remodeling [57, 58]. The gene discussed is ACE2; the disease is bronchopulmonary dysplasia.