RESUMO
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-1ß-treated Madin-Darby canine kidney (MDCK) cells as a model of renal tubular cells. IL-1ß 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-1ß treatment. IL-1ß 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-1ß-induced NGAL mRNA expression and protein secretion were significantly attenuated. In the presence of recombinant NGAL, IL-1ß-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.
Assuntos
Interleucina-1beta/metabolismo , Túbulos Renais/citologia , Túbulos Renais/metabolismo , Lipocalina-2/metabolismo , Junções Aderentes/efeitos dos fármacos , Junções Aderentes/metabolismo , Animais , Caderinas/metabolismo , Cães , Impedância Elétrica , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Túbulos Renais/efeitos dos fármacos , Lipocalina-2/genética , Células Madin Darby de Rim Canino , Inibidores de Proteínas Quinases/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Recombinantes/metabolismo , Junções Íntimas/efeitos dos fármacos , Junções Íntimas/metabolismo , Proteína da Zônula de Oclusão-1/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
The proinflammatory cytokine interleukin-1ß (IL-1ß) induced cyclooxygenases-2 (COX-2) mRNA expression and lipid mediator prostaglandin E2 release and in a time- and dose-dependent manner in canine dermal fibroblasts. The MEK inhibitor U0126 and the ERK inhibitor FR180204 clearly inhibited IL-1ß-induced prostaglandin E2 release and COX-2 mRNA expression. IL-1ß enhanced ERK1/2 phosphorylation, which was attenuated by inhibitors of MEK and ERK. The NF-κB inhibitor BAY 11-7082 also suppressed IL-1ß-induced prostaglandin E2 release and COX-2 mRNA expression. Treatment of fibroblasts with IL-1ß led to the phosphorylation of p65 and degradation of IκBα occurred, indicating that IL-1ß treatment activated NF-κB. MEK and ERK1/2 inhibitors had no effect on the phosphorylation of p65 subunit induced by IL-1ß, whereas the NF-κB inhibitor completely blocked IL-1ß-induced phosphorylation of ERK1/2. We also observed that IκBα-knockdown enhanced the phosphorylation of p65 and ERK1/2. These findings suggest that stimulation of MEK/ERK signaling pathway by NF-κB activation regulates IL-1ß-induced COX-2 expression and subsequent prostaglandin E2 release in canine dermal fibroblasts.