Proteins undergo a series of nonenzymatic reactions with glucose over time to form advanced glycosylation end products (AGEs). Macrophages have a receptor that recognizes the AGE moiety and mediates the uptake and degradation of AGE proteins. This removal process is associated with the production and secretion of cachectin (tumor necrosis factor) and interleukin-1, two cytokines with diverse and seemingly paradoxical biological activities. The localized release and action of these cytokines could account for the coordinated removal and replacement of senescent extracellular matrix components in normal tissue homeostasis.