Clusterin Neutralizes the Inflammatory and Cytotoxic Properties of Extracellular Histones.

RATIONALE: Extracellular histones, released into the surrounding environment during extensive cell death, promote inflammation and cell death and these deleterious roles have been well documented in sepsis. Clusterin (CLU) is a ubiquitous extracellular protein that chaperones misfolded proteins and promotes their removal.

OBJECTIVES: We investigated whether CLU could protect against the deleterious properties of histones.

METHODS: We assessed CLU and histones expression in sepsis patients and evaluated the protective role of CLU against histones in in vitro assays and in vivo models of experimental sepsis.

MEASUREMENTS AND MAIN RESULTS: We show that CLU binds to circulating histones and reduces their inflammatory, thrombotic and cytotoxic properties. We observed that plasma CLU levels decreased in sepsis patients, and that the decrease was greater and more durable in non-survivors than in survivors. Accordingly, CLU deficiency was associated with increased mortality in mouse models of sepsis and endotoxemia. Finally, CLU supplementation improved mouse survival in a sepsis model.

CONCLUSIONS: This study identifies CLU as a central endogenous histone-neutralizing molecule and suggests that, in pathologies with extensive cell death, CLU supplementation may improve disease tolerance and host survival.