Neutrophil gelatinase-associated lipocalin and hepcidin: what do they have in common and is there a potential interaction?

Iron is the fourth most common element in the Earth's crust and is crucial for life. Over the last few years, our understanding of iron metabolism has dramatically increased due to the discovery of hepcidin, which is produced by hepatocytes and modulated in response to anemia, hypoxia and inflammation. It has been found that anemia upregulates lipocalin 2 (NGAL; neutrophil gelatinase-associated lipocalin) in the liver and serum. The aim of this review is to summarize the current knowledge dealing with a possible role of hepcidin and NGAL in iron metabolism and its regulation, particularly in kidney disease. Elevated NGAL a few days after insult is a possible preventive or protective mechanism limiting renal injury. NGAL is an innate antibacterial factor as well as hepcidin. NGAL binds siderophores, thereby preventing iron uptake by bacteria. Hepcidin, an antibacterial defensin, prevents iron absorption from the gut and iron release from macrophages, leading to hypoferremia and anemia. Both proteins sequester iron, but by different mechanisms. However, these proteins involved in iron metabolism do not seem to be independently related. Taking into account the antimicrobial moieties of NGAL, further studies are needed to address the role of NGAL in iron metabolism and inflammation in renal failure. Copyright 2010 S. Karger AG, Basel.