High glucose and Nepsilon-(carboxymethyl) lysine bovine serum albumin modulate release of matrix metalloproteinases in cultured human endothelial cells.

BACKGROUND: Hyperglycaemia may contribute to endothelial dysfunction. Disturbances in endothelial functions include changes in the extracellular matrix underneath the cells. This may result from altered biosynthesis of matrix molecules or from modified biosynthesis and secretion of enzymes involved in the turnover of extracellular matrix. One important class of such enzymes are the matrix metalloproteinases (MMPs). AIM OF THE STUDY: The aim of this study was to investigate whether the condition of high glucose concentration relevant both to diabetes type 1 and 2 and metabolic syndrome, would affect the synthesis and release of MMPs in human umbilical cord endothelial cells (HUVEC) in vitro.
METHODS: The HUVEC were isolated and cultured in vitro. The cells were exposed to medium with either low glucose (LG, 1 g/l) or high glucose (HG, 4.5 g/l) or the advanced glycation end product (AGE) N(epsilon)-(carboxymethyl) lysine bovine serum albumin (CML-BSA), at a concentration of 10 microg/ml. The HUVEC-conditioned media were harvested and subjected to gelatin zymography and Western blotting.
RESULTS: When HUVEC were incubated with HG or CML-BSA under serum free conditions a decreased secretion of pro MMP-2 was observed, both with gelatin zymography and Western blotting. The HUVEC also secreted MMP-9, but at lower levels, and effects of HG treatment were not significant. When HUVEC were stimulated with phorbol 12-myristate 13-acetate (PMA) secretion of pro MMP-2 was not increased, but the activation of pro MMP-2 into lower molecular forms increased, irrespective of culturing in LG, HG or CML-BSA.
CONCLUSION: The HUVEC exposed to high glucose or AGE exhibit decreased secretion of MMP-2. These findings may be relevant in understanding the altered turnover of the endothelial extracellular matrix observed in the diabetic state.