Stimulatory effect of glucose on macrophage lipoprotein lipase expression and production.

Abstract

Cardiovascular diseases are the leading cause of morbidity and mortality in diabetes. Lipoprotein lipase (LPL), a major secretory product of macrophages, has been suggested to play a key role in the development of atherosclerosis. In the present study, we evaluated the effect of high glucose on macrophage LPL mRNA expression and secretion. Exposure of murine J774 macrophages to high D-glucose concentrations (20-30 mmol/l) resulted in a dramatic upregulation of LPL mRNA expression and immunoreactive mass. This effect was not observed when these cells were incubated in the presence of L-glucose or mannitol. High glucose concentrations were also found to enhance LPL gene expression and immunoreactive mass in human monocyte-derived macrophages. J774 cells cultured in a high glucose environment expressed increased c-fos mRNA levels. Treatment of these cells with c-fos antisense DNA or protein kinase C inhibitor inhibited the stimulatory effect of glucose on LPL mRNA expression. In J774 cells exposed to high glucose concentrations, enhanced nuclear protein binding to the AP-1-responsive region of the murine LPL promoter was observed, while LPL mRNA stability remained unchanged. Overall, these results demonstrate that high glucose upregulates macrophage LPL gene expression and immunoreactive mass and that this effect involves transcriptional events.