Effects of the TREM-1 pathway modulation during mesenteric ischemia-reperfusion in rats

Objectives: The triggering receptor expressed on myeloid cells (TREM)-l, a receptor expressed on the surface of neutrophils and monocytes/macrophages, synergizes with the Toll-like receptors in amplifying the inflammatory response mediated by microbial components. Because the pathogenesis of ischemia-reperfusion-induced gastrointestinal tissue injury and multiple organ failure implies leukocyte activation and bacterial translocation, we hypothesized that the TREM-1 pathway modulation would prove beneficial in this setting. Design: Animal study. Setting: Research laboratory. Subjects: Adult male Wistar rats (250-300 g). Interventions: Rats were subjected to intestinal ischemia-reperfusion induced by occlusion of the superior mesenteric artery during 60 mins and reperfused for 180 mins. At the time of reperfusion, animals were administered with LP17 (a synthetic TREM-1 inhibitor), a control peptide, or a vehicle (normal saline). Plasma concentrations of tumor necrosis factor-alpha, interleukin-6, and soluble TREM-1 were measured by enzyme-linked immunosorbent assay. Hepatic activation of the transcriptional factor nuclear factor-kappa B was assessed by electrophoretic mobility shift assay. Hepatic oxidant-antioxidant balance was estimated by measurement of lipid peroxidation and catalase activity. Heal mucosal permeability was estimated by fluorescein dextran-4 clearance and bacterial translocation by mesenteric lymph nodes culture. Measurements and Main Results: Ischemia-reperfusion was associated with cardiovascular collapse, lactic acidosis, and systemic and hepatic inflammatory response that were partly prevented by LP17 administration. Liver lipid peroxidation and catalase depletion were attenuated by LP17. Ischemia-reperfusion induced a marked increase in ileal mucosal permeability and an associated bacterial translocation that was also prevented by TREM-1 modulation. LP17 delayed mortality. Conclusions: The modulation of the TREM-1 pathway by the means of a synthetic peptide may be useful during acute mesenteric ischemia.