Abstract:

Objective To investigate the role and mechanism of regulatory T cells (Treg cell) in promoting endothelialization of carotid artery after balloon injury. Methods Treg cells were isolated from rat spleen by Treg cell sorting kit and carotid artery injury model was established. The rats were divided into three groups: control group (the same volume of normal saline), vascular endothelial growth factor (VEGF) group (intravenous injection of VEGF，20 μmol/kg) and Treg cell group (1×105 Treg cells injected via tail vein). HE staining and immunohistochemistry were used to detect endothelialization. The levels of interleukin (IL)-10, transforming growth factor β(TGF-β), IL-1β and tumor necrosis factor α (TNF-α)in serum were detected by ELISA. Flow cytometry was used to detect the proportion of monocytes, T cells and endothelial progenitor cells (EPC). Results Histological staining showed that no endothelial cells were observed in the control group, and more endothelial cells were found in the carotid intima in the Treg cell group. The result of immunohistochemistry showed that the expression of IL-10,TGF-β, IL-1 β and TNF-α protein in the control group and the Treg cell group were significantly different (t=8.252, P<0.01; t=3.254, P<0.05; t=6.237, P<0.01; t=7.529, P<0.01). ELISA result showed that the contents of IL-10, TGF-β, IL-1β and TNF-α in the control group were (17.38±2.595) μg/L, (4.750±1.549) μg/L, (11.65±1.908) μg/L and (1.163±0.3333)μg/L, respectively, while those in the Treg cell group were (58.43±6.060) μg/L, (14.17±2.250) μg/L, (1.550±0.3819) μg/L and (0.2100±0.06938) μg/L, with significant differences (t=6.170, P<0.01; t=3.558, P<0.01; t=5.191, P<0.01; t=2.800, P<0.05). The result of flow cytometry showed that the ratio of CD34+VEGFR-2+EPC in control group was (0.2838±0.01975)%, and that in Treg cell group was (0.5667±0.05993)% (t=4.483, P<0.01).The proportion of EPC in IL-10 blocking group was 0.4807±0.03067, compared with the Treg cell group, there was no significant difference (t=1.278, P>0.05).The proportion of EPC in TGF-β blocking group was(0.3082±0.02291)%, compared with the Treg cell group, the difference was significant (t=4.029, P<0.01). Conclusion Treg cells promote the rapid endothelialization of carotid artery after balloon injury by inducing EPC mobilization.

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