Smooth muscle cells influence monocyte response to LDL as well as their adhesion and transmigration in a coculture model of the arterial wall

We investigated the possible interference of smooth muscle cells with monoc yte response to LDL as well as with their adhesion and transmigration in a coculture of porcine endothelial and smooth muscle cells. Lysophosphatidylc holine (LPC), a component of oxidized LDL (oxLDL), stimulated the adhesion of THP-1 cells to endothelial cells both in mono- and in coculture with smo oth muscle cells. When THP-1 cells were incubated with endothelial cells in the presence of copper oxLDL, their adhesion was increased, but only in co culture. The addition of sodium nitroprusside (SNP) together with oxLDL mar kedly increased the adhesion of THP-1 cells in coculture. Close proximity b etween endothelial and smooth muscle cells was necessary to observe that ef fect. Furthermore, this increase in adhesion of THP-1 cells can, at least i n part, be attributed to the augmented production of monocyte chemoattracta nt protein-1 (MCP-1) observed in coculture under the influence of oxLDL and SNP. The passage of THP-1 cells through the coculture was stimulated by MC P-1 and LPC. These results show that physical contacts or close proximity b etween endothelial and smooth muscle cells play a key role in the adhesion of monocytes and their infiltration into the intima in response to oxLDL. C opyright (C) 2001 S. Karger AG, Basel.