TNF-α mediates chemokine and cytokine expression and renal injury in cisplatin nephrotoxicity

Tumor necrosis factor (TNF) is selectively cytotoxic to some types of tumor cells in vitro and exerts antitumor activity in vivo. Reactive oxygen intermediates (ROIs) have been implicated in the direct cytotoxic activity of TNF. By using confocal microscopy, flow cytometry, and the ROI-specific probe dihydrorhodamine 123, we directly demonstrate that intracellular ROIs are formed after TNF stimulation. These ROIs are observed exclusively under conditions where cells are sensitive to the cytotoxic activity of TNF, suggesting a direct link between both phenomena. ROI scavengers, such as butylated hydroxyanisole, effectively blocked the formation of free radicals and arrested the cytotoxic response, confirming that the observed ROIs are cytocidal. The mitochondrial glutathione system scavenges the major part of the produced ROIs, an activity that could be blocked by diethyl maleate; under these conditions, TNF-induced ROIs detectable by dihydrorhodamine 123 oxidation were 5- to 20-fold higher.

We have examined the mechanisms of cell death induced by cisplatin in primary cultures of mouse proximal tubular cells. High concentrations of cisplatin (800 microM) led to necrotic cell death over a few hours. Much lower concentrations of cisplatin (8 microM) led to apoptosis, which caused loss of the cell monolayer over several days. Necrosis was characterized by a cytosolic swelling and early loss of plasma membrane integrity. In contrast, early features of cells undergoing apoptosis included cell shrinkage and loss of attachment to the monolayers. Nuclear chromatin became condensed and fragmented in apoptosing cells. These features were absent in necrotic cells. DNA electrophoresis of cells exposed to 800 microM cisplatin yielded a "smear" pattern, due to random DNA degradation. In contrast, the DNA of apoptosing cells demonstrated a "ladder" pattern resulting from internucleosomal DNA cleavage. Antioxidants delayed cisplatin-induced apoptosis but not necrosis. Thus the mechanism of cell death induced by cisplatin is concentration dependent. Reactive oxygen species play a role in mediating apoptosis but not necrosis induced by cisplatin.

Ischemia/reperfusion (I/R) injury associated with renal transplantation may influence both early graft function and late changes. The initial (