Inhibitory effect of peripheral blood iTr35 cells on vascular endothelial cell vascular cell adhesion molecule-1 in children with pulmonary artery hypertension

Abstract

Objective To explore the role of iTr35 cells in the pathogenesis of children with pulmonary artery hypertension (PAH) in children, and the percentage of iTr35 cells and serum interleukin(IL)-35 levels in peripheral blood of patients with PAH were investigated.Their inhibitory effects on the expression of vascular cell adhesion molecule-1 (VCAM-1) on vascular endothelial cells were also analyzed. Methods After 3 mL peripheral blood of 30 congenital heart disease (CHD) patients with PAH, 22 CHD patients without PAH and 30 age or gender matched healthy controls (HC) were collected, the percentage of iTr35 cells were detected by flow cytometry and the concentrations of serum IL-35 were detected by Luminex, as well as soluble VCAM-1 (sVCAM-1). Human pulmonary artery endothelial cells (HPAECs) were cultured in vitro and divided into control group, tumor necrosis factor (TNF)-α group and IL-35+ TNF-α group.The expression of VCAM-1 and nuclear factor(NF)-κB P65 protein of each group were detected by flow cytometry and Western blot.The adhesion of peripheral blood mononuclear cells (PBMCs) to HPAECs was observed by fluorescence microscope. Results Compared to CHD patients without PAH, the percentage of iTr35 cells[0.86(0.45-1.63)% vs.1.14(0.46-2.11)%](H=20.52, P<0.05) in peripheral blood and serum IL-35 levels[2.43(1.76-2.85) μg/L vs.3.17(2.92-5.66) μg/L](H=119.56, P<0.05) were significantly decreased in CHD patients with PAH.However, serum sVCAM-1 concentration[923.1(892.6-1 118.7) μg/L vs.776.1(743.5-932.3) μg/L ] in CHD patients with PAH were significant increased (H=65.65, P<0.05). In addition, the concentration of serum IL-35 were negatively correlated with sVCAM-1 in PAH patients (r=-0.374 P=0.042). In vitro, the positive rate of VCAM-1 on HPAECs was significant decreased in IL-35+ TNF-α group as compared to the TNF-α group [(2.07±0.82)% vs.(5.83±1.34)%, F=1 197.18, P<0.05]. In addition, the protein expression of NF-κB P65 in HPAECs was significantly decreased in TNF-α+ IL-35 group as compared to TNF-α group, as well as the adhesion of PBMCs to HPAECs (F=212.04, 2 533.51, all P<0.05). Conclusions The percentages of iTr35 and levels of IL-35 are reduced in the peripheral blood of patients with PAH.Through in vitro experiments, IL-35 is found to reduce PBMCs adhesion by inhibiting VCAM-1 expression in HPAECs. Key words: Pulmonary artery hypertension; iTr35 cell; Pulmonary artery endothelial cell; Vascular cell adhesion molecule-1