Thrombomodulin

ObjectiveRecent clinical studies have shown that anticoagulant therapy might be effective only in specific at-risk subgroups of patients with sepsis and coagulation dysfunction. The definition of sepsis was recently modified, and as such, old scoring systems may no longer be appropriate for the diagnosis of sepsis-associated coagulopathy. The aim of this study was to evaluate prognostic factors in patients diagnosed with sepsis and coagulopathy according to the new sepsis definition and assess their accuracy in comparison with existing models.DesignRetrospective analysis of the nationwide survey for recombinant human soluble thrombomodulin.SettingGeneral emergency and critical care centres in secondary and tertiary care hospitals.ParticipantsWe evaluated the prognostic value of the newly proposed diagnostic criteria for sepsis-induced coagulopathy (SIC). A total of 1498 Japanese patients with sepsis and coagulopathy complications who were treated with recombinant thrombomodulin were analysed in this study.Main outcome measuresThe platelet count, prothrombin time (PT) ratio, fibrinogen/fibrin degradation products, systemic inflammatory response syndrome score and Sequential Organ Failure Assessment (SOFA) score obtained just before the start of treatment were examined in relation to the 28-day mortality rate.ResultsThe platelet count, PT ratio and total SOFA were independent predictors of a fatal outcome in a logistic regression model. A SIC score was defined using the three above-mentioned variables with a positivity threshold of 4 points or more. The SIC score predicted higher 28-day mortality rate compared with the current Japanese Association for Acute Medicine-disseminated intravascular coagulation score (38.4%vs34.7%).ConclusionThe SIC score is based on readily available parameters, is easy to calculate and has a high predictive value for 28-day mortality. Future studies are warranted to evaluate whether the SIC score may guide the decision to initiate anticoagulant therapy.

Thrombomodulin plays a vital role in maintaining intravascular patency due to its anticoagulant, antiinflammatory, and cytoprotective properties. However, under pathological conditions such as sepsis and systemic inflammation, endothelial thrombomodulin expression is downregulated and its function impaired. As a result, administering thrombomodulin represents a potential therapeutic modality. Recently, the effect of recombinant thrombomodulin administration in sepsis-induced coagulopathy was evaluated in a randomized controlled study (SCARLET). A 2.6% 28-day absolute mortality reduction (26.8% vs. 29.4%) was reported in 800 patients studied that was not statistically significant; however, a post hoc analysis revealed a 5.4% absolute mortality reduction among the patients who fulfilled the entry criterion at baseline. The risk of bleeding did not increase compared to placebo control. Favorable effects of thrombomodulin administration have been reported not only in sepsis-induced coagulopathy but also in disseminated intravascular coagulations with various backgrounds. Interestingly, beneficial effects of recombinant thrombomodulin in respiratory, renal, and cardiovascular diseases might depend on its anti-inflammatory mechanisms. In this review, we summarize the accumulated knowledge of endogenous as well as recombinant thrombomodulin from basic to clinical aspects and suggest future directions for this novel therapeutic agent.

IntroductionCross-talk between the coagulation system and inflammatory reactions during sepsis causes organ damage followed by multiple organ dysfunction syndrome or even death. Therefore, anticoagulant therapies have been expected to be beneficial in the treatment of severe sepsis. Recombinant human soluble thrombomodulin (rhTM) binds to thrombin to inactivate coagulation, and the thrombin-rhTM complex activates protein C to produce activated protein C. The purpose of this study was to examine the efficacy of rhTM for treating patients with sepsis-induced disseminated intravascular coagulation (DIC).MethodsThis study comprised 65 patients with sepsis-induced DIC who required ventilatory management. All patients fulfilled the criteria of severe sepsis and the International Society on Thrombosis and Haemostasis criteria for overt DIC. The initial 45 patients were treated without rhTM (control group), and the following 20 consecutive patients were treated with rhTM (0.06 mg/kg/day) for six days (rhTM group). The primary outcome measure was 28-day mortality. Stepwise multivariate Cox regression analysis was used to assess which independent variables were associated with mortality. Comparisons of Sequential Organ Failure Assessment (SOFA) score on sequential days between the two groups were analyzed by repeated measures analysis of variance.ResultsCox regression analysis showed 28-day mortality to be significantly lower in the rhTM group than in the control group (adjusted hazard ratio, 0.303; 95% confidence interval, 0.106 to 0.871; P = 0.027). SOFA score in the rhTM group decreased significantly in comparison with that in the control group (P = 0.028). In the post hoc test, SOFA score decreased rapidly in the rhTM group compared with that in the control group on day 1 (P ConclusionsWe found that rhTM administration may improve organ dysfunction in patients with sepsis-induced DIC. Further clinical investigations are necessary to evaluate the effect of rhTM on the pathophysiology of sepsis-induced DIC.

Vaso-occlusive episodes (VOEs) in the setting of hyperhemolysis can rapidly evolve into multiorgan failure in sickle cell disease (SCD). Although the mechanisms for rapid progression to multiorgan failure are unclear, a systemic vasculopathy with thrombotic microangiopathy-type features has been described. Reduced thrombomodulin (TM) function is implicated in some thrombotic microangiopathy syndromes. We observed a greater decline in platelet count and hemoglobin concentration and an increase in vascular injury biomarkers within 24 hours of admission for a VOE in 12 patients with SCD with multiorgan failure versus 12 patients without multiorgan failure. We observed decreased TM expression on the lung and kidney vasculature of 3 additional patients with SCD with multiorgan failure compared with a control patient without SCD. Transgenic SCD mice challenged with cell-free hemoglobin had reduced TM function, increased vascular injury biomarkers, and reduced renal cortical blood flow. Infusion of recombinant TM 2 or 24 hours after the challenge restored cortical blood flow and mitigated increases in vascular injury, complement activation, and tubular injury biomarkers, and protected against acute kidney and lung injury. We demonstrated that impaired TM function may be involved in the systemic vasculopathy of SCD-related multiorgan failure, and infusion of recombinant TM may restore vascular function and protect against acute organ damage.