Soluble Tie2 fusion protein decreases peritoneal angiogenesis in uremic rats

Angiogenesis is considered to be one of the most common mechanisms leading to ultrafiltration failure (UFF) in long-term peritoneal dialysis (PD) patients. The angiopoietin (Ang)/Tie system was found to play a role in the initiation of pathological neoangiogenesis and is also involved in peritoneal angiogenesis caused by peritoneal fluid. This aim of this study was to investigate the effects of the soluble Tie2 fusion protein (sTie2/Fc) on peritoneal angiogenesis in PD-treated uremic rats. The rats were divided into 6 groups: normal, sham surgery, uremic rats without PD, uremic PD-treated rats, uremic rats treated with PD and sTie2/Fc (0.25 µg/100 g) and uremic rats treated with PD and sTie2/Fc (0.5 µg/100 g). PD rats were treated once a day for 28 days prior to testing. Real-time polymerase chain reaction (RT-PCR) or tissue immunohistochemical staining was used to detect Ang-2 mRNA or protein expression in the peritoneal tissues of each group. The microvessel density (MVD) of the peritoneum was detected and quantified by immunohistochemical staining using the anti-CD34 antibody. Compared with the control group, Ang-2 mRNA and protein expression was significantly upregulated in the uremic and PD groups (P<0.05). MVD in the experimental group increased compared with the control group. sTie2/Fc treatment decreased the levels of Ang-2 mRNA and protein expression (P<0.05) in a dose-dependent manner and decreased PD-induced MVD in the peritoneum. In conclusion, angiogenesis of the peritoneum induced by PD was inhibited using sTie2/Fc in a uremic rat model.