NGAL (neutrophil gelatinase-associated lipocalin) is a small protein of approximately 25kDa. It is expressed by the LCN2 gene in humans and is conserved in variety of other mammalian species including chimpanzee, monkey, dog, cow, mouse and rat. It is predominantly expressed in neutrophils (as a granule component) and is released by these cells at sites of inflammation and bacterial infection. As NGAL is able to sequester bacterial siderophores (iron-carrying molecules) it has a role in inhibiting bacterial growth as part of an immune response. However, it has since been found to be expressed in other cell types such as kidney, liver and epithelial cells. Furthermore it has also been found that NGAL is involved in a number of processes, including apoptosis, regulation of cell growth and the inflammatory response.
The biology of NGAL has attracted considerable interest in recent years. The molecule itself has been found to exist in three different forms: a monomer, a homodimer and a heterodimer. Furthermore the heterodimer is known to exist in a form which is bound to metallic metalloprotease 9 (MMP-9). Each of these forms has been found to have a potentially distinctive biological role and source, which has led to interest in the use of these variants of NGAL as biomarkers.
Monomeric NGAL is the predominant form released by kidney tubular epithelial cells in response to cellular stress or injury. It is this form of NGAL that has led to considerable recent interest in the use of NGAL as a biomarker for Acute Kidney Injury (AKI) and this feature has considerable potential for exploitation during the drug development process so that attrition due to nephrotoxic effects can be decreased. The dimeric forms of NGAL also have distinct characteristics. The heterodimer (NGAL-MMP9 complex) has been detected in a variety of human solid tumour tissues and its association with malignancies and the attendant prognositic and diagnostic potential is a field of ongoing research. Finally the homodimer is the predominant form released from neutrophils upon degranulation.
While the current state of knowledge about NGAL provides a number of potential applications, it is also true that there is huge scope for further study that will facilitate a full understanding of the biology of this complex molecule. Alpha Laboratories is delighted to supply a wide range of NGAL assays, antigens, antibodies and kits from the BioPorto range that will assist in this work so that a full picture of the nature and potential of NGAL can be obtained.