acetyl-aspartyl-glutamyl-valyl-aspartal and ebselen

Diabetic nephropathy is the leading cause of end-stage renal disease in the Western world. Poor glycemic control contributes to the development of diabetic nephropathy, but the mechanisms underlying high glucose-induced tissue injury are not fully understood. In the present study, the effect of high glucose on a proximal tubular epithelial cell (PTEC) line was investigated. Reactive oxygen species (ROS) were detected using the fluorescent probes dichlorofluorescein diacetate, dihydrorhodamine 123, and 2,3-diaminonapthalene. Peroxynitrite (ONOO-) generation and nitrite concentrations were increased after 24 h of high glucose treatment (P<0.05). LLC-PK1 cells exposed to high D-glucose (25 mM) for up to 48 h had increased DNA fragmentation (P<0.01), caspase-3 activity (P<0.001), and annexin-V staining (P<0.05) as well as decreased expression of XIAP when compared with controls (5 mM D-glucose). The ONOO- scavenger ebselen reduced DNA fragmentation and caspase-3 activity as well as the high glucose-induced nitrite production and DCF fluorescence. High glucose-induced DNA fragmentation was completely prevented by an inhibitor of caspase-3 (P<0.01) and a pan-caspase inhibitor (P<0.001). Caspase inhibition did not affect ROS generation. This study, in a PTEC line, demonstrates that high glucose causes the generation of ONOO-, leading to caspase-mediated apoptosis. Ebselen and a caspase-3 inhibitor provided significant protection against high glucose-mediated apoptosis, implicating ONOO- as a proapoptotic ROS in early diabetic nephropathy.

Topics: Animals; Antioxidants; Apoptosis; Aspartic Acid; Azoles; Caspase Inhibitors; Caspases; Cell Line; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Epithelial Cells; Glucose; Isoindoles; Kidney Tubules, Proximal; Nitrites; Oligopeptides; Organoselenium Compounds; Oxidative Stress; Peroxynitrous Acid

Alveolar macrophages (AMs) are the principal target cells of silica and occupy a key position in the pathogenesis of silica-related diseases. Silica has been found to induce apoptosis in AMs, whereas its underlying mechanisms involving the initiation and execution of apoptosis are largely unknown. The main objective of the present study was to examine the form of cell death caused by silica and the mechanisms involved. Silica-induced apoptosis in AMs was evaluated by terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling assay and cell cycle/DNA content analysis. The elevated level of reactive oxygen species (ROS), caspase-9 and caspase-3 activation, and poly(ADP-ribose) polymerase (PARP) cleavage in silica-treated AMs were also determined. The results showed that there was a temporal pattern of apoptotic events in silica-treated AMs, starting with ROS formation and followed by caspase-9 and caspase-3 activation, PARP cleavage, and DNA fragmentation. Silica-induced apoptosis was significantly attenuated by a caspase-3 inhibitor, N-acetyl-Asp-Glu-Val-Asp aldehyde, and ebselen, a potent antioxidant. These findings suggest that apoptosis is an important form of cell death caused by silica exposure in which the elevated ROS level that results from silica exposure may act as an initiator, leading to caspase activation and PARP cleavage to execute the apoptotic process.

Topics: Animals; Antioxidants; Apoptosis; Azoles; Caspase 3; Caspase 9; Caspase Inhibitors; Caspases; Cysteine Proteinase Inhibitors; DNA Nucleotidylexotransferase; In Situ Nick-End Labeling; Isoindoles; Macrophages, Alveolar; Male; Oligopeptides; Organoselenium Compounds; Oxidative Stress; Poly(ADP-ribose) Polymerases; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Silicon Dioxide