Elevated protein carbonyls as plasma markers of oxidative stress in acute pancreatitis

Background: Experimental studies have demonstrated that protein and lipid oxidation is a feature of acute pancreatitis and that antioxidant pretreatment can ameliorate the severity of the disease. Justification for a clinical trial of antioxidant therapy requires stronger evidence for oxidative stress in patients. Aims: To determine if oxidative stress is evident in patients with acute pancreatitis on admission to hospital, if it increases after admission and if it is related to disease severity. Methods: Measurement of plasma concentrations of protein carbonyls and malondialdehyde as markers of protein oxidation and lipid peroxidation, respectively, in a consecutive series of 85 patients with acute pancreatitis 0, 2 and 5 days after admission. Results: Patients with acute pancreatitis had significantly increased concentrations of protein carbonyls in plasma on recruitment (median 27 h after the onset of symptoms) that persisted over 5 days. Protein carbonyls were higher in severe compared with mild disease (median 0.099 and 0.043 nmol/mg protein, respectively, p = 0.0016). They were higher at day 0 in patients recruited with more established pancreatitis than in those presenting early. No increases in malondialdehyde were seen. Receiver operator characteristic curve analysis demonstrated that protein carbonyls at day 0 were comparable with C-reactive protein at predicting pancreatitis severity. Conclusion: Our demonstration of substantial protein oxidation provides further evidence for oxidative stress in patients with severe pancreatitis. Our results suggest that there could be a window for early antioxidant intervention and that protein carbonyls could be a useful plasma marker of oxidative injury.