Expression of blood vessel growth inhibitory factor and platelet endothelial adhesion molecules 34 in hepatocellular carcinoma tissue and its clinical significance

Abstract

Objective To investigate the effect and mechanism of advanced oxidation protein products (AOPP) on the proliferation of CD4+ CD25+ regulatery T cells (Tregs). Methods Tregs and CD4+ CD25- T cells (worked as effective T cells, Teff) were isolated, and dendrtic cells (DCs) were induced from the human peripheral blood mononuclear cells. Tregs (5×104/well) were co-cultured with Mitomycin-inactivated DCs loaded with allogeneic antigen and IL-2 (100 U/ml), and according to the presence of AOPP into 3 different groups: Control group (200 μg/ml serum albumin), AOPP group (200 μg/ml AOPP), Antioxidant group [pretreated with 100 μmol/L diphenyleneiodonium (DPI) 1 h before AOPP was added]. The incorporation of [3H]thymidine was used to evaluate the proliferation of Tregs and the suppressive function of Tregs on the Teff. Western blotting was used to observe the expression of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), phosphorylated protein kinase B (p-Akt), phosphorylated signal transducer and activators of transcription 5 (p-STAT5) and p27kip1. Results In AOPP group, the incorporation of [3H]thymidine was (36213.3±3 385.9) cpm, which was significantly lower than that [(65 557.0±3 981.6) cpm] of Control group (P=0.001). In Antioxidant group, the value was (44 827.0±3 694.6) cpm, which was significantly higher than that of AOPP group (P=0.041), but lower than that of Control group (P=0.003). When Tregs and Teff were incubated at the ratio of 1∶1 and 1/2∶1, the suppressive ratios of Tregs on the Teff in AOPP group were (27.3±4.0)% and (23.9±3.7)%, which were significantly lower than those [(68.5±7.9)% and (62.9±5.0)%] of Control group (P=0.001, 0.001). Compared with Control group, addition of AOPP significantly downregulated the expression of p-ERK, p-Akt, p-STAT5 and upregulated the expression of p27kip1 in Tregs (P=0.009, 0.021, 0.036, 0.036). After antioxidants was added, the expression of p-ERK, p-Akt, p-STAT5 was significantly upregulated compared with AOPP group (P=0.034, 0.030, 0.042) and lower than that of Control group (P=0.043, 0.039, 0.007); the expression of p27kip1 was significantly doenregulated compared with AOPP group (P=0.048) and higher than that of Control group (P=0.047). Conclusion AOPP significantly inhibits the proliferation of Tregs through downregulating p-ERK, p-Akt and p-STAT5, and upregulating p27kip1 via oxidative stress in vitro. Key words: Advanced oxidation protein products; Regulatory T cells; Proliferation