We determined the effect of CpG-DNA on the inflammatory response of human endothelial cells of aortic or skin microvascular origin (HAoEC, HDMEC and HMEC-1) and compared the effects to those of two identically treated human macrophage cell lines.
Using the same CpG-DNA D19chimera sequence in both cell types, we find the known up-regulation of pro-inflammatory cytokines in macrophages but consistent and significant inhibition of the pro-inflammatory response (IL-6, IL-8, and IFN-beta1) in endothelial cells. This inhibition is accompanied by enhanced proliferation and an increase in IL-10 gene expression. This anti-inflammatory response persists even in the presence of pro-inflammatory cytokines and low LPS concentrations, and is overruled only in the presence of relatively high concentrations of LPS. By testing different sequences, we find the strongest response with phosphorothioate bonds.
Our results demonstrate an important regulatory function of endothelial cells in inflammatory responses, and the apparent Th2-like endothelial response in the human system may contribute significantly to the adjuvant activity of CpG-DNA.