Inhibitory effects of cariporide on LPC-induced expression of ICAM-1 and adhesion of monocytes to smooth muscle cells in vitro

Abstract

To explore the effects of cariporide on the expression of intercellular adhesion molecule-1 (ICAM-1) and the adhesion of monocytes to vascular smooth muscle cells (SMC) in vitro. Monocytes were isolated from human peripheral blood by the Ficoll-Hypaque method. The expression of ICAM-1 in SMC was detected by ELISA. The adhesion of monocytes to SMC was stimulated by lysophosphatidylcholine (LPC). The adhesion ratio of monocytes was assayed by measuring protein contents. The intracellular pH ([pH]i) of SMC was measured with 2' ,7' -bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). Preincubation of SMC with LPC alone (5 microg/mL) for 4 h markedly enhanced the expression of ICAM-1 in SMC and the rate of the adhesion of monocytes to SMC in a concentration-dependent and time-related manner. LPC simultaneously also induced an increase of [pH]i value in SMC. Cariporide concentration-dependently reduced the adhesion ratio of monocytes to SMC and the expression of ICAM-1 in SMC induced by LPC. The inhibitory effects of cariporide on the expression of ICAM-1 in SMC and the adhesion of monocytes to SMC also were associated with blocking LPC-induced elevation of the [pH]i value in SMC. LPC-induced monocyte-SMC adhesion may be mediated via activation of the Na+/H+ (NHE) exchanger. The action mechanism of cariporide may be related with inhibition of activation of the Na+/H+ exchanger of plasma membranes and ICAM-1 expression on the surface of SMC induced by LPC.