High glucose enhances the gene expression of interleukin-8 in human endothelial cells, but not in smooth muscle cells: Possible role of interleukin-8 in diabetic macroangiopathy

We examined the effect of high glucose concentrations on the production of interleukin(IL)-8, which seems to be important for the development of atherosclerosis, in cultured human aortic endothelial cells (AoEC) and smooth muscle cells (AoSMC). After incubating these cells with various concentrations of glucose for 2 days or 7 days, the IL-8 concentration in cell lysates was measured by enzyme-linked immunosorbent assay and the IL-8 mRNA expression was examined by Northern analysis. After 2 days' culture, 42.5 mmol/l glucose enhanced IL-8 mRNA expression in AoEC, but not in AoSMC, compared to 4 mmol/l glucose. After 7 days' culture, the IL-8 concentration in AoEC lysate and the expression of IL-8 mRNA were significantly increased by 20.5 mmol/l glucose, or 42.5 mmol/l glucose compared to 4 mmol/l glucose. On the other hand, the IL-8 concentration in AoSMC lysate was not affected by any glucose concentration and the expression of IL-8 mRNA in AoSMC was diminished by high glucose. These results suggest that the chemotactic gradient by IL-8 is established between arterial intima and media in response to high glucose levels in diabetic patients, and that it may be one of the key factors for SMC migration to the intima leading to diabetic macroangiopathy.