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The Endotoxin Delivery Protein HMGB1 Mediates Caspase-11-Dependent Lethality in Sepsis

Deng, M;Tang, Y;Li, W;Wang, X;Zhang, R;Zhang, X;Zhao, X;Liu, J;Tang, C;Liu, Z;Huang, Y;Peng, H;Xiao, L;Tang, D;Scott, MJ;Wang, Q;Liu, J;Xiao, X;Watkins, S;Li, J;Yang, H;Wang, H;Chen, F;Tracey, KJ;Billiar, TR;Lu, B;

Caspase-11, a cytosolic endotoxin (lipopolysaccharide: LPS) receptor, mediates pyroptosis, a lytic form of cell death. Caspase-11-dependent pyroptosis mediates lethality in endotoxemia, but it is unclear how LPS is delivered into the cytosol for the activation of caspase-11. Here we discovered that hepatocyte-released high mobility group box 1 (HMGB1) was required for caspase-11-dependent pyroptosis and lethality in endotoxemia and bacterial sepsis. Mechanistically, hepatocyte-released HMGB1 bound LPS and targeted its internalization into the lysosomes of macrophages and endothelial cells via the receptor for advanced glycation end-products (RAGE). Subsequently, HMGB1 permeabilized the phospholipid bilayer in the acidic environment of lysosomes. This resulted in LPS leakage into the cytosol and caspase-11 activation. Depletion of hepatocyte HMGB1, inhibition of hepatocyte HMGB1 release, neutralizing extracellular HMGB1, or RAGE deficiency prevented caspase-11-dependent pyroptosis and death in endotoxemia and bacterial sepsis. These findings indicate that HMGB1 interacts with LPS to mediate caspase-11-dependent pyroptosis in lethal sepsis. Copyright 2018 Elsevier Inc. All rights reserved.