Inhibition of factor XI activation attenuates inflammation and coagulopathy while improving the survival of mouse polymicrobial sepsis

Abstract

Severe bacterial sepsis often leads to a systemic procoagulant and proinflammatory condition that can manifest as disseminated intravascular coagulation, septic shock, and multiple organ failure. Because activation of the contact proteases factor XII (FXII), prekallikrein, and factor XI (FXI) can trigger coagulation and inflammatory responses, the contact factors have been considered potential targets for the treatment of sepsis. However, the pathogenic role of contact activation in severe infections has not been well defined. We therefore investigated whether an anticoagulant antibody (14E11) that selectively inhibits prothrombotic FXI activation by activated FXII (FXIIa) modifies the course of bowel perforation-induced peritoneal sepsis in mice. Early anticoagulation with 14E11 suppressed systemic thrombin-antithrombin complex formation, IL-6, and TNF-␣ levels, and reduced platelet consumption in the circulation and deposition in the blood vessels. Treatment with 14E11 within 12 hours after bowel perforation significantly improved survival compared with vehicle treatment, and the saturating dose did not increase tail bleeding. These data suggest that severe polymicrobial abdominal infection induces prothrombotic FXI activation, to the detriment of the host. IntroductionInfection-associated intravascular blood coagulation is common in patients with severe sepsis. The resulting coagulopathy is probably driven by bacterial cell components, including peptidoglycans, teichoic acid, polyphosphates, and lipopolysaccharides (LPSs), which have been shown to activate contact proteases and tissue factor-expressing leukocytes. [1][2][3] The host response to bacteria can also produce a systemic inflammatory response syndrome that can contribute to intravascular coagulation and defective fibrinolysis, resulting in disseminated intravascular coagulation (DIC)-associated consumption of platelets, leukocytes, and coagulation factors that cause both thrombosis and secondary hemorrhage. Activation of the contact protease factor XII (FXII) on negatively charged surfaces, including bacterial components, activates prekallikrein and factor XI (FXI) in terrestrial mammals, 4 which results in thrombin generation through the intrinsic coagulation pathway, activation of the complement system, and release of the inflammatory peptide bradykinin from high-molecular-weight kininogen. 5,6 Although the contact proteases appear to play a significant prothrombotic role as part of the intrinsic coagulation pathway, the importance of contact system activation in infection-related hostresponse remains uncertain.Most persons with inherited contact protease deficiencies, including FXII and its substrate prekallikrein, do not have an obvious abnormal phenotype and have normal hemostasis. 7-9 FXI deficiency (hemophilia C) is associated with excessive traumainduced bleeding in a subset of affected persons, 10,11 indicating that FXI can contribute to normal hemostasis. Despite its apparently modest hemostatic role, persons with high plasma FXI levels a...

The Formation of Microthrombi in Parenchymal Microvessels after Traumatic Brain Injury Is Independent of Coagulation Factor XI

“…Inhibition of FXI activation by FXIIa 24 h before trauma using 14E11, which is active for at least 72 h, 38 did not aggravate intracranial hemorrhage; this was consistent with the lack of relevance for FXI in post-trauma hemostasis. The values assessed 15 min and 24 h after injury were similar in the groups receiving 14E11 or control IgG; additionally, there was no increase in hemorrhage in either group over time.…”

“…The antibodies were injected into the femoral vein, which was subsequently ligated (4 mg/kg body weight dissolved in phosphate-buffered saline; a mouse weighing 25 g received a volume of 0.25 mL intravenously). Previously, 14E11 was shown to prolong activated partial thromboplastin time (aPTT) in mice at least for 72 h. 38 We verified the selective inhibition of the intrinsic pathway by determining the aPTT, a test for the intrinsic coagulation pathway, 39 and the prothrombin time (PT), a test for the extrinsic coagulation pathway, [40][41][42] with a coagulation analyzer (ACL 200 Automated Coagulation Laboratory; Instrumentation Laboratory; Bedford, MA). APTT and PT were determined in mice that received control IgG or 14E11 via the femoral vein, and in C57Bl6 and FXI-/-mice (n = 8 per group).…”

“…In our study, we used an antibody specifically designed to selectively inhibit prothrombotic FXI activation by factor XIIa (14E11) 37,38 and a control antibody (control immunoglobulin G [IgG]). The antibodies were injected into the femoral vein, which was subsequently ligated (4 mg/kg body weight dissolved in phosphate-buffered saline; a mouse weighing 25 g received a volume of 0.25 mL intravenously).…”

“…The values assessed 15 min and 24 h after injury were similar in the groups receiving 14E11 or control IgG; additionally, there was no increase in hemorrhage in either group over time. Since 14E11 has been shown to be antithrombotic in rodent and primate models, 37,38 this is of particular importance regarding a second therapeutic approach: the safe prophylactic anticoagulation, which is required, for example, in patients who are immobilized in an intensive care unit; this is usually the case in the first days or weeks following TBI. 27,28 Until now, prophylactic anticoagulation in patients suffering from TBI remains a double edged sword 27,28,[61][62][63][64][65][66][67] : there is the risk of secondary thrombosis due to immobilization and altered coagulation after TBI versus the risk of exacerbating intracranial hemorrhage.…”

“…Previously, 14E11 was demonstrated to be protective in a mouse model of sepsis, 38,59 and in acute ischemic stroke. 60 In the current study, we did not detect any improvement in contusion volume, hemispheric swelling, thrombus formation, and intracranial hemorrhage following FXI inhibition.…”