Interaction of Nepsilon(carboxymethyl)lysine- and methylglyoxal-modified albumin with endothelial cells and macrophages. Splice variants of RAGE may limit the responsiveness of human endothelial cells to AGEs.
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. Nepsilon-(carboxymethyl)lysine (CML)- and methylglyoxal (MGO)-modified proteins have been identified as major AGEs. 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 MGO-modified 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-alpha 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.
Department of Internal Medicine, University Hospital Maastricht, Debeyelaan 25, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands.
Mariska L M
ML
Lieuw-a-Fa
Casper G
CG
Schalkwijk
Marten
M
Engelse
Victor W M
VW
van Hinsbergh
D017398:Alternative Splicing; D015815:Cell Adhesion Molecules / Q000032:analysis; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology*; D017127:Glycation End Products, Advanced / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives / Q000737:chemistry; D008264:Macrophages / Q000378:metabolism*; D020033:Protein Isoforms; D011765:Pyruvaldehyde / Q000737:chemistry; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000235:genetics*; D012709:Serum Albumin / Q000737:chemistry*
D015815:Cell Adhesion Molecules; D017127:Glycation End Products, Advanced; D020033:Protein Isoforms; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D012709:Serum Albumin; D011765:Pyruvaldehyde; D008239:Lysine