Improvement in coagulation markers with antithrombin— Beneficial in severe sepsis?*

Human Recombinant Antithrombin (ATryn®) Administration Improves Survival and Prevents Intravascular Coagulation After Intraportal Islet Transplantation in a Piglet Model

Human islet transplantation is a viable treatment option for type 1 diabetes mellitus (T1DM). However, pancreatic islet inflammation after transplantation induced by innate immune responses is likely to hinder graft function. This is mediated by incompatibility between islets and the blood interface, known as instant blood-mediated inflammatory reaction (IBMIR). Herein we hypothesized that portal venous administration of islet cells with human recombinant antithrombin (ATryn®), a serine protease inhibitor (serpin), which plays a central role in the physiological regulation of coagulation and exerts indirect anti-inflammatory activities, may offset coagulation abnormalities such as disseminated intravascular coagulation (DIC) and IBMIR. The current prospective, randomized experiment was conducted using an established preclinical pig model. Three groups were constituted for digested pancreatic tissue transplantation (0.15 ml/kg): control, NaCl 0.9% (n = 7); gold standard, heparin (25 UI/kg) (n = 7); and human recombinant ATryn® (500 UI/kg) (n = 7). Blood samples were collected over time (T0 to 24 h), and biochemical, coagulation, and inflammatory parameters were evaluated. In both the control and heparin groups, one animal died after a portal thrombosis, while no deaths occurred in the ATryn®-treated group. As expected, islet transplantation was associated with an increase in plasma IL-6 or TNF-α levels in all three groups. However, DIC was only observed in the control group, an effect that was suppressed after ATryn® administration. ATryn® administration increased antithrombin activity by 800%, which remained at 200% for the remaining period of the study, without any hemorrhagic complications. These studies suggest that coadministration of ATryn® and pancreatic islets via intraportal transplantation may be a valuable therapeutic approach for DIC without risk for islets and subjects.

Gerinnungsaktive Substanzen als Sepsistherapeutika

Whereas antithrombin and tifacogin failed to improve clinical outcome in cases of severe sepsis, drotrecogin alfa (activated) increased the chances of survival of patients with this condition. Concerns about efficacy and safety of drotrecogin alfa have been raised because of internal and external validity and internal consistency problems found in the PROWESS study, and because of the drug's single positive pivotal phase III documentation that led to restricted marketing authorisations for only a subgroup of studied patients whose randomisation had not been stratified. Concerns intensified with data from ADDRESS, the PROWESS follow-up, and paediatric studies. It is difficult to make rational and safe recommendations for drotrecogin alfa use on the available evidence. Further trials have been suggested. The relevant bodies should review product approval in light of their own guidelines for marketing authorisations on the basis of single pivotal trials and request the further study required to prevent the possibility of patients receiving a non-efficacious and potentially lethal drug.

First day dynamic changes in antithrombin III activity after supplementation have a predictive value in critically ill patients

To evaluate the changes in the antithrombin III (antithrombin) values after initial supplementation to predict outcome in critically ill patients, we conducted a retrospective study. All consecutive patients admitted to the intensive care unit (ICU) and treated with antithrombin were enrolled in the study. Initial doses of 1,500 IU or 30 IU/kg antithrombin concentrates were administered over an hour. The clinical backgrounds of the patients were collected from computer-based records. Serial data of antithrombin were collected from the first day of administration (Day 0) to days 1-4. The patients were subdivided into two groups based on whether they demonstrated an increased antithrombin activity of more than 60% on the first day after the initial supplementation (responders) or not (nonresponders). Four hundred thirty-five patients were enrolled in the present study. Two hundred eighty-eight patients could achieve an antithrombin activity of more than 60%. The outcome was significantly different between the two groups. A logistic regression analysis revealed the day 1 antithrombin level and an initial increase of less than 60% after supplementation to be independently associated with ICU mortality. We also found a significant increase in the platelet counts and fibrinogen levels, and a decrease in the disseminated intravascular coagulation (DIC) scores for the responders. In conclusion, our findings demonstrated the first-day dynamic change in antithrombin activity, and not the basal level, to be able to predict critically ill patient death. This dynamic change was associated with an improvement in the platelet counts, fibrinogen levels, and the DIC score.

Global fibrinolytic capacity in pediatric patients with sepsis and disseminated intravascular coagulation

There are many complex pathophysiologic changes of the coagulation system in sepsis. The fibrinolytic system was evaluated in septic children using the global fibrinolytic capacity (GFC), a new technique reflecting the overall fibrinolytic activity. The study consisted of 24 children with sepsis, 36 children with sepsis plus disseminated intravascular coagulation (DIC), and 20 healthy age-matched control individuals. Compared with controls, 86% of sepsis patients and 87% of sepsis plus DIC patients had decreased GFC levels. Between the sepsis plus DIC and sepsis groups there was no significant difference in terms of GFC levels. While 19 patients (52.7%) died in the sepsis plus DIC group, only three patients (12.5%) died in the sepsis group. When survivors and nonsurvivors were compared in terms of coagulation tests, there were significant differences for protein C, antithrombin, platelet, fibrinogen, aspartate aminotransferase, alanine aminotransferase, prothrombin time, and white blood cell values. In conclusion, the level of GFC reduced in most of the pediatric sepsis patients but no difference was observed between patients with sepsis and patients with sepsis plus DIC. While inhibition of fibrinolysis is an important finding in sepsis, the mortality is mainly associated with the presence of end-organ damage and the status of coagulation parameters.

Antithrombin reduces monocyte and neutrophil CD11b up regulation in addition to blocking platelet activation during extracorporeal circulation

BACKGROUND

Patients undergoing cardiac surgery requiring cardiopulmonary bypass develop a systemic inflammatory reaction. Antithrombin III (AT) has anticoagulant effects but also shows evidence of anti-inflammatory activity. The aim of this study was to examine whether exogenous AT could reduce white blood cell activation (CD11b up regulation or elastase release), in addition to inhibiting platelet (PLT) activation and fibrin generation, during simulated cardiopulmonary bypass (sCPB), undertaken in the absence of endothelium.

STUDY DESIGN AND METHODS

sCPB was carried out with minimally heparinized (2 U/mL) human blood for 90 minutes in controls and with supplementation by low-dose (1 U/mL) and high-dose (5 U/mL) AT.

RESULTS

High-dose AT blunted thrombin generation during sCPB (prothrombin fragment 1.2); both doses significantly inhibited thrombin activity (fibrinopeptide A). Complement activation (C3a and C5b-9) was unaffected by AT. High-dose AT inhibited PLT activation (P-selectin expression and P-selectin-dependent monocyte-PLT conjugate formation). AT supplementation at the higher dose significantly abrogated monocyte and neutrophil CD11b up regulation and neutrophil elastase release.

CONCLUSION

In addition to anticoagulant and anti-PLT effects, pharmacologic AT doses significantly blunted monocyte and neutrophil CD11b up regulation and neutrophil elastase release during sCPB, independent of endothelial effects. These data provide evidence for the direct anti-inflammatory activity of AT that has clinical relevance for CPB complications.