Hypofibrinolysis induced by tranexamic acid does not influence inflammation and mortality in a polymicrobial sepsis model

Abstract

The biological relevance of fibrinolysis to the host response to sepsis is illustrated by pathogens such as S. pyogenes and Y. pestis, whose virulence factors are proteins that challenge the balance between pro- and anti-fibrinolytic factors of the host, and by the consistent finding of hypofibrinolysis in the early stages of sepsis. Whether this hypofibrinolytic response is beneficial or detrimental to the host, by containing the spread of pathogens while at the same time limiting the access of immune cell to infectious foci, is still a matter of debate. Tranexamic acid (TnxAc) is an antifibrinolytic agent that is being increasingly used to prevent and control bleeding in conditions such as elective orthopedic surgery, trauma, and post-partum-hemorrhage, which are frequently followed by infection and sepsis. Here we used a model of polymicrobial sepsis to evaluate whether hypofibrinolysis induced by TnxAc influenced survival, tissue injury and pathogen spread. Mice were treated with two doses of TnxAc bid for 48h, and then sepsis was induced by cecal ligation and puncture. Despite the induction of hypofibrinolysis by TnxAc, no difference could be observed in survival, tissue injury (measured by biochemical and histological parameters), cytokine levels or pathogen spread. Our results contribute with a new piece of data to the understanding of the complex interplay between fibrinolysis and innate immunity. While our results do not support the use of TnxAc in sepsis, they also address the thrombotic safety of TnxAc, a low cost and widely used agent to prevent bleeding.

Fig 1. Effect of TnxAc on coagulation and fibrinolysis parameters.

Mice were treated with the indicated doses of TnxAc ip, bid, for 48 hours. Platelet poor plasma was obtained from the inferior vena cava for analyses. (a) Plasma levels of thrombin-antithrombin (TAT) complexes and (b) the euglobulin lysis time are shown for TnxAc and vehicle treated mice are shown; n = 6–11 per group; Kruskal-Wallis test.

Fig 2. Survival during polymicrobial sepsis.

Kaplan-Meier curves depicting survival of mice treated with TnxAc 100mg/kg bid (n = 13) or 600mg/kg bid (n = 18) initiated 48h before sepsis induction, for up to 7 days; Vehicle (n = 29); Log-rank test.

Fig 3. Clinical score of the murine experimental sepsis.

Bars indicate daily mean clinical scores (and SEM) of mice treated with TnxAc at 100 mg/Kg, 600 mg/kg or vehicle (each bar represents one day of the follow-up, with data from mice that were remained alive at each time-point). No statistically significant difference could be observed between groups for each day separately (Kruskall-Wallis test with Dunn’s multiple comparison test, comparing each time point between the three experimental groups).

Fig 4. Biochemical markers of tissue damage.

Median serum levels of (a) AST, (b) ALT, (c) BUN, (d) creatinine, (e) LDH and (f) CK in mice treated with TnxAc or vehicle were measured 24 hours after sepsis induction, and no differences were observed between groups; n = 5–12 per group; Kruskal-Wallis test.

Fig 5. Inflammatory cytokines and chemokines during polymicrobial sepsis.

Median serum levels of (a) IL-6, (b) MCP-1, (c) KC/CXCL-1 and (d) TNF- α of mice treated with TnxAc or vehicle measured 24 hours after sepsis induction; n = 6–16 per group; Kruskal-Wallis test.

Fig 6. Bacterial burden in TnxAc treated mice during polymicrobial sepsis.

Mean (log) counts of bacterial colonies per mL in (a) peritoneal fluid, (b) kidneys, (c) liver and (d) whole blood 24 hours after sepsis induction; n = 12–15 per group; Anova test with post-test correction.