Effects of interleukin-10 on monocyte/endothelial cell adhesion and MMP-9/TIMP-1 secretion.

OBJECTIVE Monocyte adhesion to endothelial cells and subsequent secretion of matrix metalloproteinases (MMPs) by activated macrophages are key events in arteriosclerosis and restenosis. We tested the hypothesis that interleukin-10 (IL-10), a potent anti-inflammatory cytokine, inhibits monocyte-endothelial cell interactions. METHODS The effect of IL-10 on monocyte/endothelial cell adhesion, as well as on the expression of MMP-9 and the tissue inhibitor of MMP-9, TIMP-1, were first tested in vitro in coculture systems. In addition, we used an ex vivo binding assay to study the inhibitory effect of IL-10 on monocyte adhesion to carotid arteries obtained from either normal, or L-nitro arginine-methyl ester (L-NAME)-treated rats. The effect of IL-10 on the expression of monocyte adhesion molecules (CD18 and CD62-L) was studied by flow cytometry. RESULTS IL-10 (150 ng/ml) inhibits monocyte adhesion to endothelial cells (by 35%) and to carotid arteries (by 40 and 50%, in normal and L-NAME-treated rats, respectively), via direct modulation of the expression of CD18 and CD62-L. Moreover, IL-10 dose-dependently decreases MMP-9 activity and increases TIMP-1 levels in coculture systems, both at the transcriptional level. CONCLUSIONS Our results suggest that IL-10 is an important modulator of monocyte-endothelial cell interactions.