Combination effect of antithrombin and recombinant human soluble thrombomodulin in a lipopolysaccharide induced rat sepsis model

INTRODUCTION: Recombinant human soluble thrombomodulin (rhsTM) is newly developed for the treatment of DIC. The purpose of this study was to evaluate the efficacy of the concomitant administration of rhsTM and antithrombin (AT). METHODS: In the first series, rats were treated with either 62.5, 125, 250 or 500 IU/kg (n = 6, each) of AT or 0.125, 0.25, 0.5 or 1.0 mg/kg (n = 6, each) of rhsTM followed by lipopolysaccharide (LPS) injection. 8 h later, the fibrinogen level was examined. In the second series, TM group was pretreated with 0.25 mg/kg of rhsTM, AT group was pretreated with 125 IU/kg of AT, AT/TM group was pretreated with both AT and rhsTM, and control group was pretreated with saline (n = 7, each). The platelet count, fibrinogen, ALT, LDH and high-mobility group box 1 (HMGB1) levels were measured. In addition, histologic changes in liver were examined. In the third series, survival was calculated up to 24 h. RESULTS: Both AT and rhsTM produced a linear dose-response with regard to the fibrinogen level, with 125 IU/kg of AT and 0.25 mg/kg of rhsTM producing equivalent effects. The combined administration of AT and rhsTM significantly reduced the decrease in the platelet count and the fibrinogen level (P < 0.05, 0.01, respectively). The elevations in ALT and LDH were significantly suppressed in all treatment groups. The HMGB1 level and the histologic changes tended to indicate damage reduction. Survival was significantly better only in AT/TM group (P < 0.01). CONCLUSIONS: The coadministration of AT and rhsTM might be effective for the treatment of severe sepsis.