Recombinant Treponema pallidum protein Tp47 increases permeability of vascular endothelial cells through inducing uPA

Abstract

Objective To investigate the effect of recombinant Treponema pallidum protein Tp47 (rTpp47) on the expression of uPA by THP-1 macrophages and on the permeability of human umbilical vein/vascular endothelial cells(HUVECs). Methods THP-1 cells were stimulated with rTpp47 for 24 hours and then the culture supernatant and THP-1 cells were collected respectively. The expression of urokinase-type plasminogen activator (uPA) in THP-1 cells was detected by ELISA and Western blot. After stimulation of HUVECs monolayers by THP-1 cell culture supernatant, FITC-dextran was used to evaluate the permeability of HUVECs. Western blot method was used to observe the effect of uPA on the expression of tight junction protein claudin-5 of HUVECs and the protein kinase C(PKC) signaling pathway of THP-1 cells stimulated by rTpp47. Results The synthesis and secretion of uPA of THP-1 cells stimulated by rTpp47 were significantly higher than those in the control group(P＜0.05, P＜0.001). When HUVECs were stimulated by the THP-1 cell supernatant for 12 hours and 24 hours, the relative permeability of vascular endothelial cells in the experimental group was significantly higher than the control group (P＜0.05 for 12 hours and P＜0.000 1 for 24 hours). Amiloride, the synthetic inhibitor of uPA, significantly inhibited the uPA expression and secretion of THP-1 cells stimulated by rTpp47 (P＜0.0001), alleviated the inhibition effect of rTpp47 on claudin-5 expression of HUVECs (P＜0.05), and significantly suppressed PKC phosphorylation(P＜0.05) in THP-1 cells induced by rTpp47. Conclusions The rTpp47 can stimulate the synthesis and secretion of uPA in THP-1 cells through a potential mechanism of activating PKC signaling pathway and uPA may increase the permeability of vascular endothelial cells.

Keywords

• treponema pallidum|recombinant tp protein tp47(rtpp47)|urokinase-type plasminogen activator(upa)|macrophages|human umbilical vein/vascular endothelial cells(huvecs)