Abstract
Originally described as a nuclear protein that bends DNA, the high mobility group box 1 protein (HMGB1) has recently emerged as a necessary and sufficient late mediator of severe sepsis. HMGB1 is therefore a molecular target that provides a wide window for clinical intervention in sepsis. Vasoactive intestinal peptide (VIP) and urocortin are two well known anti-inflammatory neuropeptides that protect against several immune disorders by regulating a wide panel of inflammatory mediators. In this study, we demonstrate the therapeutic effect of VIP and urocortin in various models of established sepsis: both agents reduced lethality induced by cecal ligation and puncture or by injection of live Escherichia coli. The therapeutic effect of VIP and urocortin was accompanied by a decrease in systemic levels of HMGB1. In addition, administration of recombinant HMGB1 completely reversed the protective effect of VIP and urocortin in experimental sepsis. In vitro and ex vivo studies show that both VIP and urocortin down-regulate translocation of HMGB1 from the nucleus to the cytoplasm and its subsequent secretion by activated macrophages, suggesting that macrophages are major targets in the inhibitory activity of these neuropeptides. To our knowledge, VIP and urocortin are the first endogenous inhibitors of HMGB1 secretion shown to improve sepsis survival in a clinically relevant time frame.