Increase in circulating ACE-positive endothelial microparticles during acute lung injury.

Circulating endothelial microparticles (EMPs) are considered to be markers of endothelial injury, and lung microvascular endothelial cells express higher levels of angiotensin-converting enzyme (ACE). The aim of this study is to examine whether the number of ACE microvascular EMPs could be a prognostic marker for the development of acute respiratory distress syndrome (ARDS) in septic patients.The numbers of EMPs and ACE EMPs in the culture supernatant from human microvascular endothelial cells, as well as in the blood of mouse lung injury models and septic patients (n=82), were examined using flow cytometry.ACE EMPs in the culture supernatant from pulmonary microvascular endothelial cells increased after exposure to an inflammatory stimulus. In the mouse lung injury models, the circulating ACE EMPs and ACE EMP/EMP ratio were higher than in the controls (p<0.001). The ACE EMP/EMP ratio was correlated with the wet/dry lung ratio (r=0.775, p<0.001). The circulating ACE EMPs and ACE EMP/EMP ratio on admission were significantly increased in septic patients who developed ARDS compared with septic patients who did not (p<0.001).Therefore, circulating ACE EMPs may be a prognostic marker for the development of ARDS in the septic patients.