Effect of 1-methyltryptophan on lipopolysaccharide-induced permeability and apoptosis in human umbilical vein endothelial cells / 中华急诊医学杂志

ABSTRACT

Objective:To explore the effect of 1-methyltryptophan (1-MT) on lipopolysaccharide (LPS)-induced permeability and apoptosis of human umbilical vein endothelial cells (HUVECs).Methods:HUVECs were treated with phosphate buffer saline (PBS, control group), 1 μg/mL LPS (LPS group), and LPS combined with 1 mmol/L 1-MT (1-MT group). The expression levels of the p120 concatemer (p120ctn), vascular endothelial (VE) cadherin, caspase-3, and DNA repair enzyme polyadenylate ribose polymerase-1 (PARP) after incubation at 8 h were detected using Western blot. The concentrations of kynurenine (Kyn) after incubation at 2, 4, 6, and 8 h were measured by high-performance liquid chromatography, and indoleamine2, 3-dioxygenase (IDO) activity was calculated. Comparisons among groups were performed using the LSD- t test. Results:Compared with the control group, the expression of caspase-3 [(74.01±7.91)% vs (157.14±7.63)%, P<0.01] and the concentration of Kyn were significantly up-regulated, while the expression of p120ctn [(49.12±2.15)% vs (37.61±1.80)%, P<0.01], VE-cadherin [(107.70±7.01)% vs (90.66±2.58)%, P=0.027], and PARP-1 [(67.95± 3.08)% vs (57.93±5.26)%, P=0.038] were significantly down-regulated, and IDO activity was significantly increased in the LPS group ( P<0.05). Compared with the LPS group, the expression of caspase-3 [(157.14±7.63)% vs (110.74±7.89)%, P<0.01] was significantly down-regulated, while the expression of p120ctn [(37.61±1.80)% vs (47.19±0.82)%, P<0.01], VE-cadherin [(90.66±2.58)% vs (107.27±9.89)%, P=0.029], and PARP-1 [(57.93±5.26)% vs (74.12±4.90)%, P=0.005] were significantly up-regulated, and the activity of IDO was significantly decreased over time in the 1-MT group ( P<0.05). No significant differences were observed between the PBS and 1-MT groups in the protein levels of p120ctn, VE-cadherin, and PARP-1 protein as well as Kyn concentration and IDO activity ( P>0.05), while the expression of caspase-3 was increased in 1-MT group ( P=0.001). Conclusions:LPS aggravates the permeability of HUVECs, which can be reversed by 1-MT via inhibiting IDO activity and reducing Kyn concentrations. Moreover, 1-MT can also reduce apoptosis, which may be via increasing the expression of PARP-1 and reducing the expression of caspase-3, thus protecting endothelial cells.