In vitro evidence for immune activating effect of specific AGE structures retained in uremia.
BACKGROUND
Advanced glycation end-products (AGEs) have been identified to be accumulated in blood and tissues of patients with end-stage renal disease (ESRD). AGEs have been shown to modulate immune competent cell activities and in this way they may contribute to the progression of atherosclerosis. All studies in this context have been performed, however, with generated mix of glycation compounds, and not with structures similar to those encountered in uremia. In the present study, the immunologic effect of specific AGE compounds, known to be retained in uremia, has been evaluated.


METHODS
Four albumin preparations, modified chemically at lysine or arginine residues, respectively, to contain N-epsilon-carboxymethyllysine (CML albumin), N-epsilon-carboxyethyllysine (CEL albumin), glyoxal-induced imidazolinones (Arg I albumin) or methylglyoxal-induced imidazolinones (Arg II albumin) were applied. Their effect on chemiluminescence production, CD14 expression, and the DNA synthesis of calcitriol-differentiated HL-60 (monocyte/macrophage phenotype) was studied.


RESULTS
The phorbol 12-myristate 13-acetate (PMA)-stimulated chemiluminescence production of the calcitriol differentiated HL-60 cells was enhanced in the presence of CEL albumin (44.1 +/- 18.5 vs. 64.7 +/- 28.1 counts 10(3)/30 min) (P < 0.05), Arg I albumin (46.4 +/- 18.8 vs. 66.1 +/- 32.6 counts 10(3)/30 min) (P < 0.05) and CML albumin (41.9 +/- 25.5 vs. 60.9 +/- 5.5 counts 10(3)/30 min) (P= 0.0625) pointing to an increase in free radical production. The latter AGE compounds also significantly increased the calcitriol-induced CD14 expression on HL-60 cells (1675 +/- 796 vs. 2075 +/- 1044; 768 +/- 143 vs. 890 +/- 150; 647 +/- 63 vs. 716 +/- 69 mean fluorescence intensity) (P < 0.05, respectively) pointing to an increase in expression of the lipopolysaccharide (LPS) receptor. Finally, the DNA synthesis of the calcitriol-differentiated HL-60 cells was enhanced in the presence of Arg I albumin [34.5 +/- 4.6 vs. 27.7 +/- 9.7% 5-bromo-2'-deoxyuridine (BrdU)-positive cells] (P < 0.05) resulting in an increased cell proliferation.


CONCLUSIONS
Genuine AGE compounds, as they are encountered in the uremic condition, activate leukocyte response, and hence could play a role in uremia related atherogenesis.
Glorieux
Griet
G
Department of Internal Medicine, Renal Division, University Hospital, Ghent, Belgium. griet.glorieux@UGent.be
Helling
Ruediger
R
Henle
Thomas
T
Brunet
Philippe
P
Deppisch
Reinhold
R
Lameire
Norbert
N
Vanholder
Raymond
R
D001973:Bromodeoxyuridine / Q000378:metabolism; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D002845:Chromatography; D004247:DNA / Q000096:biosynthesis; D005609:Free Radicals / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D018922:HL-60 Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007107:Immune System / Q000503:physiopathology*; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008163:Luminescent Measurements; D014511:Uremia / Q000276:immunology* / Q000378:metabolism*
D005609:Free Radicals; D017127:Glycation End Products, Advanced; D018950:Lipopolysaccharide Receptors; D004247:DNA; D001973:Bromodeoxyuridine