HMGB1 preconditioning: therapeutic application for a danger signal?

High mobility group box 1 (HMGB1) is a nuclear factor released extracellularly as a late mediator of lethality in sepsis and as an early mediator of inflammation following injury. In contrast to the proinflammatory role of HMGB1, recent evidence suggests beneficial applications of HMGB1 in injury states. One such application is the use of HMGB1 as a preconditioning stimulus. Preconditioning is a phenomenon whereby a low level of stressful stimuli confers protection against subsequent injury. Preconditioning has been demonstrated in multiple species, can be induced by various stimuli, and is applicable in different organ systems. Only with the recent introduction of the concept of endogenous molecules, such as HMGB1, as signals and mediators for inflammation during injury states has the use of endogenous molecules been investigated for this use. This review will focus on the use of endogenous molecules, specifically HMGB1, as a preconditioning stimulus and its mechanism of protection, as well as other protective applications for HMGB1.