Evaluation of the effect of recombinant thrombomodulin on a lipopolysaccharide-induced murine sepsis model

To evaluate the effect of recombinant human thrombomodulin (rTM) on sepsis, the levels of nucleosome as well as high-mobility group box 1 (HMGB1) and cytokines in sera and peritoneal fluids were measured in a mouse model of lipopolysaccharide (LPS)-induced sepsis after administration of rTM. C57BL/6 mice were intraperitoneally injected with LPS (15 mg/kg; Escherichia coli O111:B4) with or without the intravenous administration of rTM (3 mg/kg; 30 min prior to or 2 h after LPS injection). The survival rates were evaluated and levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, HMGB1 and nucleosome in sera and peritoneal fluids were analyzed by ELISA. Administration of rTM prior to or after LPS improved the survival rate of septic mice. In addition, rTM administered prior to or after LPS suppressed the level of pro-inflammatory cytokine TNF-α in sera at 1-3 h after LPS injection, whereas only the administration of rTM after LPS suppressed the levels of HMGB1 and nucleosome (late-phase mediators of sepsis) (9-12 h) in sera after the LPS injection. Furthermore, administration of rTM prior to or after LPS suppressed the level of TNF-α in the peritoneal fluids at 1-3 h after LPS injection, whereas only the administration of rTM after LPS suppressed the levels of IL-6 and MCP-1 in the peritoneal fluids at 6-9 h after LPS injection. These observations indicated that administration of rTM significantly improves the survival rate and suppresses the increased levels of TNF-α, IL-6, MCP-1, HMGB1 and nucleosome in the LPS-induced septic shock model. Thus, rTM may exert a protective action on sepsis and reduce mortality, possibly by reducing not only the levels of cytokines and chemokine but also the levels of late-phase mediators of sepsis.