ABSTRACT
BACKGROUND: Elafin is a potent endogenous neutrophil elastase inhibitor that protects against myocardial inflammation and injury in preclinical models of ischaemic-reperfusion injury. We investigated whether elafin could inhibit myocardial ischaemia-reperfusion injury induced during coronary artery bypass graft (CABG) surgery. METHODS AND RESULTS: In a randomised double-blind placebo-controlled parallel group clinical trial, 87 patients undergoing CABG surgery were randomised 1:1 to intravenous elafin 200â mg or saline placebo administered after induction of anaesthesia and prior to sternotomy. Myocardial injury was measured as cardiac troponin I release over 48â h (area under the curve (AUC)) and myocardial infarction identified with MRI. Postischaemic inflammation was measured by plasma markers including AUC high-sensitive C reactive protein (hs-CRP) and myeloperoxidase (MPO). Elafin infusion was safe and resulted in >3000-fold increase in plasma elafin concentrations and >50% inhibition of elastase activity in the first 24â h. This did not reduce myocardial injury over 48â h (ratio of geometric means (elafin/placebo) of AUC troponin I 0.74 (95% CI 0.47 to 1.15, p=0.18)) although post hoc analysis of the high-sensitive assay revealed lower troponin I concentrations at 6â h in elafin-treated patients (median 2.4 vs 4.1â µg/L, p=0.035). Elafin had no effect on myocardial infarction (elafin, 7/34 vs placebo, 5/35 patients) or on markers of inflammation: mean differences for AUC hs-CRP of 499â mg/L/48 h (95% CI -207 to 1205, p=0.16), and AUC MPO of 238â ng/mL/48 h (95% CI -235 to 711, p=0.320). CONCLUSIONS: There was no strong evidence that neutrophil elastase inhibition with a single-dose elafin treatment reduced myocardial injury and inflammation following CABG-induced ischaemia-reperfusion injury. TRIAL REGISTRATION NUMBER: (EudraCT 2010-019527-58, ISRCTN82061264).
Subject(s)
Coronary Artery Bypass/adverse effects , Coronary Artery Disease/surgery , Elafin/administration & dosage , Intraoperative Complications/drug therapy , Myocardial Reperfusion Injury/drug therapy , Double-Blind Method , Follow-Up Studies , Humans , Infusions, Intravenous , Intraoperative Complications/etiology , Intraoperative Period , Magnetic Resonance Imaging, Cine , Myocardial Reperfusion Injury/diagnosis , Myocardial Reperfusion Injury/etiology , Protease Inhibitors/administration & dosage , Recombinant Proteins , Retrospective StudiesABSTRACT
Objectives. We investigated whether ultrasmall paramagnetic particles of iron oxide- (USPIO-) enhanced magnetic resonance imaging (MRI) can detect experimental chronic allograft damage in a murine renal allograft model. Materials and Methods. Two cohorts of mice underwent renal transplantation with either a syngeneic isograft or allograft kidney. MRI scanning was performed prior to and 48 hours after USPIO infusion using T2(∗)-weighted protocols. R2(∗) values were calculated to indicate the degree of USPIO uptake. Native kidneys and skeletal muscle were imaged as reference tissues and renal explants analysed by histology and electron microscopy. Results. R2(∗) values in the allograft group were higher compared to the isograft group when indexed to native kidney (median 1.24 (interquartile range: 1.12 to 1.36) versus 0.96 (0.92 to 1.04), P < 0.01). R2(∗) values were also higher in the allograft transplant when indexed to skeletal muscle (6.24 (5.63 to 13.51)) compared to native kidney (2.91 (1.11 to 6.46) P < 0.05). Increased R2(∗) signal in kidney allograft was associated with macrophage and iron staining on histology. USPIO were identified within tissue resident macrophages on electron microscopy. Conclusion. USPIO-enhanced MRI identifies macrophage.
