Tie2 mRNA in peripheral blood: a new marker to assess damage of endothelial cells in a rat model of sepsis

Abstract

Objective To evaluate the endothelial cell damage by detecting the circulating Tie2 mRNA level in a rat model of sepsis. Methods The model of sepsis was established by cecal ligation and puncture (CLP) in 90 rats which were divided into 6 groups: normal, sham, CLP-3 h, CLP-6 h, CLP-12 h and CLP-24 h. Serum biochemical markers were detected by automatic biochemical analyzer. Serum IL-6 was measured with enzyme linked immunosorbent assay. The vascular permeability of liver, kidney, lung and heart was detected with Evans blue. Circulating endothelial cells (CEC) were separated using density gradient separation and counted. Total RNA of whole blood were extracted and the mRNA levels of two endothelial specific genes, Tie2 and vascular endothelial growth factor receptor 2 (VEGFR 2), were measured by quantitative real-time PCR. Results The level of serum biochemical indexes increase d after CLP. The amount of s erum IL-6 in C LP-6 h, 12 h, and 24 h group was increased 6.5-fold ( P<0.05), 8.4-fold ( P<0.01), and 13.3-fold ( P<0.001) compared with normal group (170.68 pg/ml±42.46 pg/ml) respectively ( F=14.319, P<0.001). Significantly increased organ vasopermeability of liver, kidney, lung and heart was observed after CLP respectively. The number of CEC peaked (11.83±1.94) 3 hours after CLP compared with normal control (5.33±1.21, P<0.05), and then decreased gradually ( F=54.183, P<0.001). The mRNA level of Tie2 in CLP-3 h group (3.47±1.47) was also markedly higher than that in other groups ( F=10.640, P<0.001). Conclusion Using quantitative real-time PCR to measure the level of Tie2 mRNA in peripheral blood is a simple and relatively sensitive method to evaluate the damage of endothelial cells.