Summary
In diabetes mellitus an increased risk exists for vascular complications. A role for
advanced glycation endproducts (AGEs) in the acceleration of vascular disease has
been suggested. Nε(carboxymethyl)lysine (CML)- and methylglyoxal (MGO)-modified proteins
have been identified as majorAGEs. The interaction of these AGEs with the human endothelial
cells and macrophages was studied. Changes in adhesion molecule expression, i. e.
vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1)
and E-selectin were determined by cell-bound Elisa on human endothelial cells after
incubation with CML-modified albumin and MGO-modified albumin. The presence of the
full-length receptor of AGEs (RAGE) and splice variants of RAGE was determined by
specific RT-PCR. In addition, binding studies were performed with CML- and MGOmodified
albumin to endothelial cells and P388D1 macrophages. We demonstrated that CML-albumin
or MGO-albumin did not induce activation of endothelial cells as measured by the expression
of adhesion molecules, while, under the same conditions, TNF-α did. No specific binding
of CML-albumin and MGO-albumin on these cells was found. In contrast to endothelial
cells, a specific binding of MGO-albumin to P388D1 macrophages was demonstrated, which
could be competed by ligands of scavenger receptors. In human umbilical vein and microvascular
endothelial cells we found the N-truncated and C-truncated splice variants of RAGE.
In conclusion, under our experimental conditions no CML- or MGO-albumin-induced increase
in adhesion molecule expression was found on endothelial cells. In agreement with
this, no binding of these AGEs was found to endothelial cells. The existence of splice
variants of RAGE in endothelial cells might explain the lack of interaction of extracellular
AGEs with these cells.
Keywords
Carboxymethyllysine - methylglyoxal - HUVECs - endothelial activation - adhesion molecules
- human microvascular endothelial cells
