Finally, in vivo or ex vivo administration of human rACE2 in plasma samples produced an increase not only of Ang (1–9) but also of Ang (1–5) and Ang (1–7) in both healthy subjects [178] and ARDS patients [134], indicating that all three Ang peptides might represent surrogate markers of ACE2 activity. Here, ACE2 is linked to acute respiratory distress syndrome.