Hepatic surgical stress promotes systemic immunothrombosis that results in distant organ injury

H Zhang, J Goswami, P Varley… - Frontiers in …, 2020 - frontiersin.org
H Zhang, J Goswami, P Varley, DJ Van der Windt, J Ren, P Loughran, H Yazdani, MD Neal
Frontiers in immunology, 2020frontiersin.org
Innate immunity can initiate platelet activation during the development of thrombosis through
a process, termed immunothrombosis. Neutrophils form neutrophil extracellular traps (NETs)
that have been shown to interact directly with platelets and play pro-coagulant roles in a
variety of infectious and sterile inflammatory settings. Hepatic surgical stress initiated by
ischemia/reperfusion (I/R) injury has wide systemic consequences on distant organs.
However, the mechanisms of this remote injury phenomenon are not well-understood. Here …
Innate immunity can initiate platelet activation during the development of thrombosis through a process, termed immunothrombosis. Neutrophils form neutrophil extracellular traps (NETs) that have been shown to interact directly with platelets and play pro-coagulant roles in a variety of infectious and sterile inflammatory settings. Hepatic surgical stress initiated by ischemia/reperfusion (I/R) injury has wide systemic consequences on distant organs. However, the mechanisms of this remote injury phenomenon are not well-understood. Here, we sought to determine the role of NETs in causing systemic immunothrombosis and distant organ injury following a local inflammatory insult with liver I/R. Postoperative thromboelastographic revealed that the speed of clot formation (alpha-angle) was significantly increased whereas time to clot formation (R-time) were decreased by in patients undergoing liver resection, indicating a hypercoagulable state after surgery. In mice subjected to liver I/R, circulating platelet activation and platelet-neutrophil aggregates were significantly increased. Injured distant organs such as the lung and kidney displayed NETs and platelet-rich micro-thrombi in the microvasculature following liver I/R. The immune-thrombi and organ damage were dramatically decreased when NETs were inhibited by DNase treatment. Depletion of Tlr4 on platelets limited NET-induced activation of platelets but had no effect on NET formation. Furthermore, platelet-specific TLR4 KO mice had significantly reduced distant organ injury with decreased circulating platelet activation, platelet-neutrophil aggregates following liver I/R in comparison to their control counterparts. These data establish that after an acute local inflammatory process, NET-activated platelets can lead to a systemic pro-coagulant state with resultant remote organ injury by immunothrombosis.
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