Shock-Driven Endotheliopathy in Trauma Patients Is Associated with Leucocyte Derived Extracellular Vesicles

Abstract

Endotheliopathy following trauma is associated with poor outcome, but the underlying mechanisms are unknown. This study hypothesized that an increased extracellular vesicle (EV) concentration is associated with endotheliopathy after trauma and that red blood cell (RBC) transfusion could further enhance endotheliopathy. In this post hoc sub study of a multicentre observational trial, 75 trauma patients were stratified into three groups based on injury severity score or shock. In patient plasma obtained at hospital admission and after transfusion of four RBC transfusions, markers for endotheliopathy were measured and EVs were labelled with anti CD41 (platelet EVs), anti CD235a (red blood cell EVs), anti CD45 (leucocyte EVs), anti CD144 (endothelial EVs) or anti CD62e (activated endothelial EVs) and EV concentrations were measured with flow cytometry. Statistical analysis was performed by a Kruskall Wallis test with Bonferroni correction or Wilcoxon rank test for paired data. In patients with shock, syndecan-1 and von Willebrand Factor (vWF) were increased compared to patients without shock. Additionally, patients with shock had increased red blood cell EV and leucocyte EV concentrations compared to patients without shock. Endotheliopathy markers correlated with leucocyte EVs (ρ = 0.263, p = 0.023), but not with EVs derived from other cells. Injury severity score had no relation with EV release. RBC transfusion increased circulating red blood cell EVs but did not impact endotheliopathy. In conclusion, shock is (weakly) associated with EVs from leucocytes, suggesting an immune driven pathway mediated (at least in part) by shock.

Keywords: endotheliopathy; extracellular vesicles; shock; trauma.

Figure 1

Median and interquartile ranges of (A) endothelial activation markers stratified by shock (B) endothelial markers stratified by injury severity score (ISS) and (C) Extracellular vesicles stratified by shock (D) extracellular vesicles stratified by ISS. A bar with asterisk represents a statistically significant difference between the groups, * p < 0.05, ** p < 0.01, *** p < 0.001. Abbreviations: TM: thrombomodulin, vWF: von Willebrand Factor, PEV: platelet derived extracellular vesicle, REV: red blood cell derived extracellular vesicle, LEV: leucocyte derived extracellular vesicles, EEV: endothelial derived extracellular vesicle, aEEV: activated endothelial derived extracellular vesicle.

Figure 2

Median and interquartile ranges of levels of (A) endothelial activation markers on baseline and after transfusion and (B) Extracellular vesicles on baseline and after transfusion. A bar with asterisk represents a statistically significant difference, *** p < 0.001. Abbreviations: TM: thrombomodulin, PEV: platelet derived extracellular vesicle, REV: red blood cell derived extracellular vesicle, LEV: leucocyte derived extracellular vesicles, EEV: endothelial derived extracellular vesicle, aEEV: activated endothelial derived extracellular vesicle.