Circulating myeloperoxidase is elevated in septic shock and is associated with systemic organ failure and mortality in critically ill patients

Neutrophils are elevated in critically ill patients during the systemic inflammatory response to trauma and sepsis. The neutrophil-derived enzyme myeloperoxidase generates reactive oxygen species which can react with host tissue resulting in cell damage and dysfunction. Thus, elevated myeloperoxidase in the circulation may be associated with adverse patient outcomes. Circulating myeloperoxidase concentrations were measured in a cohort of 44 critically ill patients, 55% of whom were diagnosed with septic shock, and 44 healthy controls. Intensive care mortality prediction scores (SOFA, SAPS, APACHE) and ICU and hospital mortality were obtained from the patients’ clinical notes. Hematological and biochemical assessments included blood cell counts, lactate, alanine transaminase, creatinine, bilirubin, C-reactive protein, and PaO2. Myeloperoxidase was measured using a commercial ELISA kit and cell free DNA was detected using SytoxGreen™ fluorescence staining. Myeloperoxidase concentrations were significantly higher in critically ill patients than control samples (234 ± 30 ng/ml versus 15 ± 4 ng/ml, p 234 ng/mL), mortality increased to 71%. Myeloperoxidase is associated with markers of tissue injury and systemic organ failure, particularly in septic patients. The enzyme is also associated with mortality in patients with higher APACHE III scores, and thus has potential as an additional diagnostic marker to improve mortality prediction. [Display omitted] •The neutrophil-derived enzyme myeloperoxidase is elevated in septic shock, independent of neutrophil counts, indicating enhanced ac