Role of MiR-126a-3p in Endothelial Injury in Endotoxic Mice

Objective: Sepsis poses a serious global health problem with an overall mortality rate of 30%, in which the vascular injury is a major contributor. The study is to determine the expression profile of micro-RNAs in endotoxic vascular walls and their potential roles in sepsis-related vascular injury.

Design: Prospective randomized study.

Setting: Laboratory investigation.

Subjects: Male C57BL/6 mice, average weight 26.5 ± 1.8 g.

Interventions: Endotoxemia was induced in mice via lipopolysaccharide injection (20 mg/kg, intraperitoneal) (Sigma, St. Louis, MO). The control mice were injected with the same amount of saline (500 μL, intraperitoneal). In a subgroup of mice, a high dose of lipopolysaccharide (30 mg/kg, intraperitoneal) was applied to induce endotoxin-related death.

Measurements And Main Results: The mi-RNA expression profiles in aortas from lipopolysaccharide-induced endotoxic mice were determined. The result demonstrated that some micro-RNAs were aberrantly expressed in endotoxic mouse arteries. Among them, the endothelial cell-enriched/endothelial cell-specific miR-126a-3p was significantly down-regulated in endotoxic mouse arteries, septic human vessels, as well as vascular endothelial cells isolated from endotoxic mice or treated with lipopolysaccharide. The down-regulation of miR-126a-3p occurred at transcriptional level via the decreased expression of Krüppel-like factor 2, which could be inhibited by Krüppel-like factor 2 over-expression via adenovirus expressing Krüppel-like factor 2. The down-regulation of miR-126a-3p in endothelial cells resulted in the increased apoptosis, and decreased proliferation and migration, which were inhibited by miR-126a-3p mimics. In vivo, over-expression of miR-126a-3p via lentivirus attenuated endotoxemia-induced injuries on endothelial function and vascular permeability. We found that SPRED1 and VCAM-1 were two direct target genes of miR-126a-3p related to miR-126a-3p-mediated effects in endotoxemia. Finally, the survival rate of endotoxic mice was significantly increased by the over-expression of miR-126a-3p.

Conclusions: The results suggest that vascular micro-RNAs such as miR-126a-3p may represent novel mechanisms and new therapeutic targets for endotoxemia-induced vascular injury and endotoxic mortality.