Early intravenous administration of tranexamic acid ameliorates intestinal barrier injury induced by neutrophil extracellular traps in a rat model of trauma/hemorrhagic shock.

Background: Early intravenous administration of tranexamic acid has been shown to protect the intestinal barrier after a model of trauma-hemorrhagic shock in the rat, but the potential mechanism remains unclear. Our previous studies have demonstrated that neutrophil extracellular traps contribute to the intestinal barrier dysfunction during sepsis and other critical conditions. Meanwhile, there are high levels of neutrophil infiltration in the intestine during trauma-hemorrhagic shock. Here, we hypothesized that neutrophil extracellular trap formation played a vital role during trauma-hemorrhagic shock-induced intestinal injury and that tranexamic acid, a serine protease inhibitor, may inhibit neutrophil extracellular trap formation and protect intestinal barrier function in trauma-hemorrhagic shock.

Methods: A model of trauma-hemorrhagic shock in male rats was established. The rats were divided into 6 groups: (1) sham group; (2) trauma-hemorrhagic shock group; (3) trauma-hemorrhagic shock + DNase I group; (4) trauma-hemorrhagic shock + tranexamic acid group; (5) trauma-hemorrhagic shock + tranexamic acid (different time) group; and (6) trauma-hemorrhagic shock + tranexamic acid (different doses) group. The DNase I solution was injected intravenously to disrupt neutrophil extracellular traps immediately after the trauma-hemorrhagic shock model was completed. After 24 hours, the small intestine and blood were collected for analysis. Human neutrophils were harvested and incubated with phorbol-12-myristate-13-acetate or tranexamic acid, generation of reactive oxygen species, and key proteins expression were detected.

Results: Trauma-hemorrhagic shock induced the formation of intestinal neutrophil extracellular traps and disrupted the intestinal tight junction proteins. Clearing of neutrophil extracellular traps by DNase I resulted in increased expression of tight junction proteins and alleviated the intestinal injury. Early intravenous tranexamic acid administration (1 hour after trauma-hemorrhagic shock) decreased neutrophil extracellular trap formation and prevented tight junction protein disruption compared to the non-tranexamic acid group; however, after delayed administration of tranexamic acid (6 hours), there were no changes in neutrophil extracellular trap formation and intestinal injuries compared to the non-tranexamic acid group. Furthermore, tranexamic acid inhibited neutrophil extracellular trap formation and protected the intestinal barrier in a dose-dependent manner and high-dose (20 mg/kg) treatment of tranexamic acid showed a better effect compared with the therapeutic dose (10 mg/kg). The results of thromboelastography demonstrated that the R and K values in the high-dose group decreased (R, 1.85 ± 0.14 vs 3.87 ± 0.16 minutes, P < .001; K, 0.95 ± 0.04 vs 1.48 ± 0.07 minutes, P < .001), accompanied by a decrease in LY30, indicating that treatment with a high dose of tranexamic acid may cause hypercoagulability and shutdown of fibrinolysis. In addition, less neutrophil extracellular trap formation was detected in neutrophils incubated with neutrophils via an reactive oxygen species-dependent pathway.

Conclusion: We first demonstrated a novel role of neutrophil extracellular traps in the pathophysiology of intestinal barrier dysfunction during trauma-hemorrhagic shock. Notably, early but not delayed intravenous administration of tranexamic acid effectively inhibits neutrophil extracellular trap formation and protects intestinal barrier function. Therefore, these results suggested a potential theoretic intervention for the protection of the intestinal barrier during trauma-hemorrhagic shock. In such a process, tranexamic acid appears to regulate neutrophil extracellular trap formation via the classic reactive oxygen species/mitogen-activated protein kinase pathway.