ABSTRACT
Objective To investigate the effects of tg19320,a small peptide,interfering with IgG-FcγR interaction on the adhesion of neutrophils to endothelium and the expression of intercellular adhesion molecule 1 (ICAM-1)in endothelial cells and its possible mechanism.Methods Tg19320 was prepared by solid-phase peptide synthesis.ANCA IgG was isolated from the serum of active ANCA-associated systemic vasculitis(AASV)patients.When primary human umbilical vein endothelial cells(HUVEC)grew into connuence in cytokine-free eonditions,the cells were stimulated with TNF-α,human normal IgG,ANCA IgG and ANCA IgG+tg19320 respectively.HUVEC were pretreated with tg19320 for 45 minutes before being stimulated by ANCA IgG.Non-activated neutrophils was added to treat HUVEC and adhesion was measured by cell count.The expression of ICAM-1 mRNA and protein was assessed by real-time PCR and Western blot respectively.Soluble ICAM-1(sICAM-1)was determined using ELISA technique.Phosphorylation of IκB-α was assessed by Western blot. Results ANCA IgG significantly up-regulated the expression of ICAM-1 in HUVEC and promoted sICAM-1 release(P＜0.05),and TNF-α enhanced the effect of ANCA.These effects were almost completely abolished by tgl9320 both at protein and mRNA level.Furthermore,ANCA IgG increased the IκB-α phosporylation in HUVEC and tg19320could inhibit the effect. Conclusions ANCA IgG can modulate the expression of ICAM-1 and sICAM-1 release in endothelial cells.FcγR probably play a critical role in the ICAM-1 expression up-regulated by ANCA,which is mediated in part through NF-κB signaling pathway.Tg19320 has protective effect on endothelium in AASV in vitro.