Induction of novel cytokines and chemokines by advanced glycation endproducts determined with a cytometric bead array.

Advanced glycation endproducts (AGEs) accumulate on long-lived protein deposits, e.g. those composed of beta(2)-microglobulin (in dialysis-related amyloidosis) or beta-amyloid peptide (in Alzheimer's disease). When AGEs bind to the "receptor for advanced glycation endproducts", they activate redox-sensitive transcription factors such as NF-kappaB, and subsequently induce the expression of pro-inflammatory cytokines such as IL-1, IL-6 and TNF-alpha. Using a cytokine bead array, we have further analyzed the Bovine Serum Albumin (BSA)-AGE induced expression of selected cytokines/chemokines in two murine cell lines, RAW 264.7 macrophages and N-11 microglia. Our study showed that monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor (TNF-alpha) were both released in a time-dependent manner from both RAW 264.7 macrophages and N-11 microglia upon stimulation with BSA-AGE or lipopolysaccharide (LPS), which was used as a positive control. Interestingly, MCP-1 was also constitutively expressed by unstimulated cells, although at a lower levels. Much higher levels of IL-6 were secreted by RAW 264.7 macrophages than by N-11 microglia in response to both stimuli. IL-12p70, interferon-gamma and the anti-inflammatory cytokine IL-10 were not induced by either LPS or BSA-AGE. Our results indicate a very similar pattern of chemokine and cytokine expression induced by such different ligands as AGEs and LPS indicating similar or convergent downstream signaling pathways.