Elevated nucleosome levels in systemic inflammation and sepsis*

OBJECTIVE: Multiple organ dysfunction syndrome is a frequent complication of severe sepsis and septic shock and has a high mortality. We hypothesized that extensive apoptosis of cells might constitute the cellular basis for this complication. DESIGN: Retrospective study. SETTING: Medical and surgical wards or intensive care units of two university hospitals. PATIENTS: Fourteen patients with fever, 15 with systemic inflammatory response syndrome, 32 with severe sepsis, and eight with septic shock. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We assessed circulating levels of nucleosomes, specific markers released by cells during the later stages of apoptosis, with a previously described enzyme-linked immunosorbent assay in these 69 patients with fever, systemic inflammatory response syndrome, severe sepsis, or septic shock. Severity of multiple organ dysfunction syndrome was assessed with sepsis scores, and clinical and laboratory variables. Elevated nucleosome levels were found in 64%, 60%, 94%, and 100% of patients with fever, systemic inflammatory response syndrome, severe sepsis, or septic shock, respectively. These levels were significantly higher in patients with septic shock as compared with patients with severe sepsis, systemic inflammatory response syndrome, or fever, and in nonsurvivors as compared with survivors. In patients with advanced multiple organ dysfunction syndrome, nucleosome levels correlated with cytokine plasma levels as well as with variables predictive for outcome. CONCLUSIONS: Patients with severe sepsis and septic shock have elevated plasma levels of nucleosomes. We suggest that apoptosis, probably resulting from exposure of cells to excessive amounts of inflammatory mediators, might by involved in the pathogenesis of multiple organ dysfunction syndrome.