Recombinant Thrombomodulin on Neutrophil Extracellular Traps in Murine Intestinal Ischemia-Reperfusion

In multiple-organ dysfunction, an injury affecting one organ remotely impacts others, and the injured organs synergistically worsen outcomes. Recently, several mediators, including extracellular histones and neutrophil extracellular traps, were identified as contributors to distant organ damage. This study aimed to elucidate whether these mediators play a crucial role in remote organ damage induced by intestinal ischemia-reperfusion. This study also aimed to evaluate the protective effects of recombinant thrombomodulin, which has been reported to neutralize extracellular histones, on multiple-organ dysfunction after intestinal ischemia-reperfusion.

Intestinal ischemia was induced in male C57BL/6J mice via clamping of the superior mesenteric artery. Recombinant thrombomodulin (10 mg/kg) was administered intraperitoneally with the initiation of reperfusion. The mice were subjected to a survival analysis, histologic injury scoring, quantitative polymerase chain reaction analysis of tumor necrosis factor-α and keratinocyte-derived chemokine expression, Evans blue dye vascular permeability assay, and enzyme-linked immunosorbent assay analysis of histones in the jejunum, liver, lung, and kidney after 30- or 45-min ischemia. Neutrophil extracellular trap formation was evaluated by immunofluorescence staining.

Recombinant thrombomodulin yielded statistically significant improvements in survival after 45-min ischemia (ischemia-reperfusion without vs. with 10 mg/kg recombinant thrombomodulin: 0% vs. 33%, n = 21 per group, P = 0.001). Recombinant thrombomodulin reduced the histologic injury score, expression of tumor necrosis factor-α and keratinocyte-derived chemokine, and extravasation of Evans blue dye, which were augmented by 30-min ischemia-reperfusion, in the liver, but not in the intestine. Accumulated histones and neutrophil extracellular traps were found in the livers and intestines of 30-min ischemia-reperfusion-injured mice. Recombinant thrombomodulin reduced these accumulations only in the liver.

Recombinant thrombomodulin improved the survival of male mice with intestinal ischemia-reperfusion injury. These findings suggest that histone and neutrophil extracellular trap accumulation exacerbate remote liver injury after intestinal ischemia-reperfusion. Recombinant thrombomodulin may suppress these accumulations and attenuate liver injury.