The effect of aprotinin on hypoxia-reoxygenation-induced changes in neutrophil and endothelial function

Background and objective: An acute Inflammatory response associated with cerebral ischaemia-reperfusion contributes to the development of brain injury. Aprotinin has potential, though unexplained, neuroprotective effects in patients undergoing cardiac surgery. Methods: Human neutrophil CD11b/CD18, endothelial cell intercellular adhesion molecule-1 (ICAM-1) expression and endothelial interleukin (IL)-1beta supernatant concentrations in response to in vitro hypoxia-reoxygenation was studied in the presence or absence of aprotinin (1600 KIU mL(-1)). Adhesion molecule expression was quantified using flow cytometry and IL-1beta concentrations by enzyme-linked immunosorbent assay. Data were analysed using ANOVA and post hoc Student-Newman-Keuls test as appropriate. Results: Exposure to 60-min hypoxia increased neutrophil CD11b expression compared to normoxia (17 0 +/- 46% vs. 91 +/- 27%, P = 0.001) (percent intensity of fluorescence compared to time 0) (n = 8). Hypoxia (60 min) produced greater upregulation of CD11b expression in controls compared to aprotinin-treated neutrophils [(170 +/- 4696 vs. 129 +/- 40%) (P = 0.04)] (n = 8). Hypoxia-reoxygenation increased endothelial cell ICAM-1 expression (155 +/- 3.7 vs. 43 +/- 21 mean channel fluorescence, P = 0.0003) and IL-1beta supernatant concentrations compared to normoxia (3.4 +/- 0.4 vs. 2.6 +/- 0.2, P = 0.02) (n = 3). Hypoxia-reoxygenation produced greater upregulation of ICAM-1 expression [(155 +/- 3.3 vs. 116 +/- 0.7) (P = 0.001)] and IL-1beta supernatant concentrations [(3.4 +/- 0.3 vs. 2.6 +/- 0.1) (P = 0.01)] In controls compared to aprotinin-treated endothelial cell preparation (n = 3). Conclusions: Hypoxia-reoxygenation-induced upregulation of neutrophil CD11b, endothelial cell ICAM-I expression and IL-1beta concentrations is decreased by aprotinin at clinically relevant concentrations.