Dabigatran protection against lipopolysaccharide induced endotoxemia is not mediated through its anticoagulant function
Endotoxemia is a key feature of sepsis pathogenesis and has also been found to mediate the pathophysiology of multiple chronic inflammatory conditions.  In this work, we expand upon a model of endotoxemia due to lipopolysaccharide (LPS) using zebrafish and demonstrate that this model displays activation of inflammatory and pro-coagulant genes, impaired coagulation in response to endothelial injury, and signs of organ dysfunction.  An in silico analysis revealed that there were multiple associations between the RNA-seq signature of LPS treated embryos and the RNA-seq signature of genes and drugs involving diverse pathways.  An in vivo screen involving >1,500 FDA approved drugs identified multiple compounds spanning several drug categories that partially or completely prevented endotoxemic death.  Three small molecules including one anticoagulant dabigatran were identified through both the in vivo and in silico analyses.  Dabigatran, a direct thrombin inhibitor, significantly reduced the upregulation of inflammatory cytokines and pro-coagulant genes and completely protected zebrafish from endotoxemic death due to LPS.  However, other anticoagulants argatroban (direct thrombin inhibitor), and rivaroxaban and apixaban, (factor Xa inhibitors), conferred no such protection.  Lastly, prothrombin mutant fish displayed no increase in survival when treated with LPS.  These data together suggest that dabigatran protects zebrafish from endotoxemia through a mechanism independent of its anticoagulant effect.  In summary, our in silico and in vivo analyses reveals that dabigatran and several other novel small molecules prevent LPS induced endotoxemia and warrant further therapeutic exploration in inflammatory conditions, both acute and chronic. Overall design: Zebrafish larvae that were 3 days post fertilization (dpf) were incubated with a lethal dose of LPS from Salmonella typhi and collected 3 hours post treatment.  Gene expression changes were compared to control untreated larvae.