Glycolaldehyde-modified β-lactoglobulin AGEs are unable to stimulate inflammatory signaling pathways in RAGE-expressing human cell lines.
METHODS
Advanced glycation endproducts (AGEs) are suspected to stimulate inflammatory signaling pathways in target tissues via activation of the receptor for AGEs. Endotoxins are generally recognized as potential contamination of AGE preparations and stimulate biological actions that are very similar as or identical to those induced by AGEs.


RESULTS
In our study, we used glycolaldehyde-modified β-lactoglobulin preparations as model AGEs and employed two methods to remove endotoxin using either affinity columns or extraction with Triton X-114 (TX-114). Affinity column-purified AGEs retained their ability to stimulate inflammatory signaling as measured by mRNA expression of inflammatory cytokines in the human lung epithelial cell line Beas2b. However, glycolaldehyde-modified AGEs purified by extraction with TX-114 did not show any stimulation of mRNA expression of inflammatory cytokines. The presence of a cell stimulating endotoxin-like activity was demonstrated in the detergent phase after extraction with TX-114, thus indicating that not AGEs but a lipophilic contamination was responsible for the stimulation of inflammatory signaling.


CONCLUSIONS
Our results demonstrate that glycolaldehyde-modified AGEs are unable to induce inflammatory signaling in receptor for AGE-expressing cells. The observed cell-activating activity can be ascribed to an endotoxin-like lipophilic contamination present in AGE preparations and affinity column purification was insufficient to remove this contamination.
Buetler
Timo M
TM
Nestlé Research Center, Vers-chez-les-Blanc, Lausanne, Switzerland.
Latado
Hélia
H
Leclerc
Estelle
E
Weigle
Bernd
B
Baumeyer
Alexandra
A
Heizmann
Claus W
CW
Scholz
Gabriele
G
D000079:Acetaldehyde / Q000031:analogs & derivatives* / Q000737:chemistry; D002460:Cell Line; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D003902:Detergents / Q000737:chemistry; D004731:Endotoxins / Q000302:isolation & purification / Q000494:pharmacology; D017127:Glycation End Products, Advanced / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D007782:Lactoglobulins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism*; D015203:Reproducibility of Results; D015398:Signal Transduction
D016207:Cytokines; D003902:Detergents; D004731:Endotoxins; D017127:Glycation End Products, Advanced; D007782:Lactoglobulins; D012333:RNA, Messenger; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D000079:Acetaldehyde; C010972:glycolaldehyde