RESUMO
Aquaporins (AQPs) are small integral membrane proteins that are essential for water transport across membranes. AQP9, one of the 13 mammalian AQPs (including AQP0 to 12), has been reported to be highly expressed in hydrarthrosis and synovitis patients. Given that several studies have identified signal transduction as an additional function of AQPs, it is hypothesized that AQP9 may modulate inflammatory signal transduction in chondrocytes. Therefore, the present study used a model of interleukin (IL)1ßinduced inflammation to determine the mechanisms associated with AQP9 functions in chondrocytes. Osteoarthritis (OA) and normal cartilage samples were subjected to immunohistological analysis. In addition, matrix metalloproteinase (MMP)3, MMP13 and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) mRNA and protein analysis was conducted in normal human articular chondrocytes from the knee (NHACKn) stimulated with IL1ß by reverse transcriptionpolymerase chain reaction (RTqPCR) and western blotting, respectively. AQP9 knockdown was also performed by transfection of AQP9specific small interfering RNA using Lipofectamine. AQP1, 3, 7, 9 and 11 mRNA expression levels were detected in OA human chondrocytes and in IL1ßtreated normal human chondrocytes. The levels of AQP9, MMP3, MMP13 and ADAMTS5 mRNA were increased by treatment with 10 ng/ml IL1ß in a timedependent manner, while knockdown of AQP9 expression significantly decreased the mRNA levels of the MMP3, MMP13 and ADAMTS5 genes, as well as the phosphorylation of IκB kinase (IKK). Treatment with a specific IKK inhibitor also significantly decreased the expression levels of MMP3, MMP13 and ADAMTS5 in response to IL1ß stimulation. Furthermore, immunohistochemical analysis demonstrated that AQP9 and inflammatory markers were highly expressed in OA cartilage. In addition, the downregulation of AQP9 in cultured chondrocytes decreased the catabolic gene expression in response to IL1ß stimulation through nuclear factorκB signaling. Therefore, AQP9 may be a promising target for the treatment of OA.
Assuntos
Aquaporinas/genética , Condrócitos/metabolismo , Regulação para Baixo/genética , NF-kappa B/metabolismo , Transdução de Sinais , Idoso , Idoso de 80 Anos ou mais , Aquaporinas/metabolismo , Cartilagem Articular/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Quinase I-kappa B/metabolismo , Mediadores da Inflamação/metabolismo , Interleucina-1beta/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Metaloproteinase 13 da Matriz/metabolismo , Metaloproteinase 3 da Matriz/metabolismo , Fosforilação , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
The nitrofuran antimicrobial agent, furazolidone (FZ), is still used in veterinary medicine in some countries in the Middle and Far Eastern countries. The present study aimed to investigate the effects of successive bolus doses of FZ and its metabolite 3-amino-2-oxazolidinone (AOZ) on cytochrome P450 (CYP)-related activities in the livers of rats and chickens. Female Wistar rats and white Leghorn chickens were orally administered FZ once a day for 4 consecutive days. FZ-treated chickens showed an increase in multiple CYP-related activities, however, rats treated with FZ did not show these changes. In chickens, treatment with FZ also induced production of microsomal CYP2C6-like apoprotein. The present study demonstrated that FZ caused a multiple-type induction of CYP-related activities in chickens, but not in rats.
