Diabetic nephropathy patients show hyper-responsiveness to N6-carboxymethyllysine

The aim of this study was to evaluate the impact of N6-carboxymethyllysine (CML) on NF-[kappa]B gene expression and tumor necrosis factor (TNF) production in diabetic nephropathy. This was an observational study comprised of three groups: diabetic nephropathy (n=30), type II diabetes mellitus (n=28), and healthy volunteers (n=30). Blood samples collected from the study participants were cultured for 24 h in the presence of CML or an appropriate control. After incubation, the cultures were centrifuged to separate the cells from the conditioned media. cDNA was prepared from the cell pellet and used to quantify NF-[kappa]B gene expression by quantitative real-time polymerase chain reaction (PCR). The conditioned media were used to measure TNF production by enzyme-linked immunosorbent assay (ELISA). The CML-induced fold change in NF-[kappa]B gene expression was significantly different among the study groups (P=5.4 * [10.sup.-5]). Also, the CML-induced fold change in TNF levels was significantly different among the three groups (P=4.3 * [10.sup.-8]). These results imply that patients with diabetic nephropathy and type II diabetes mellitus showed an elevated response to CML. Key words: Diabetic nephropathy; Receptor for advanced glycation end-product pathway; N6-carboxymethyllysine; Nuclear factor-kappa B; Tumor necrosis factor