Expression and Function of Interleukin-1β-Induced Neutrophil Gelatinase-Associated Lipocalin in Renal Tubular Cells

Acute kidney injury (AKI) is characterized by a sudden loss of renal function. Early recognition of AKI, especially in critically ill patients, is essential for adequate therapy. Currently, neutrophil gelatinase-associated lipocalin (NGAL) is considered to be an effective biomarker of AKI; however, the regulation of its expression and function in renal tubular cells remains unclear. In this study, we investigated the regulation of the expression and function of NGAL in IL-1β-treated Madin-Darby canine kidney (MDCK) cells as a model of renal tubular cells. IL-1β induced a disturbance in the localization of E-cadherin and zonaoccludin-1 (ZO-1). The transepithelial electrical resistance (TER) also decreased 5 days after IL-1β treatment. IL-1β induced NGAL mRNA expression and protein secretion in a time- and dose-dependent manner, which occurred faster than the decrease in TER. In the presence of ERK1/2 and p38 inhibitors, IL-1β-induced NGAL mRNA expression and protein secretion were significantly attenuated. In the presence of recombinant NGAL, IL-1β-induced disturbance in the localization of E-cadherin and ZO-1 was attenuated, and the decrease in TER was partially maintained. These results suggest that NGAL can be used as a biomarker for AKI and that it functions as a protector from AKI.