Antioxidant Defense Mechanisms of Endothelial Cells and Renal Tubular Epithelial Cells In Vitro: Role of the Glutathione Redox Cycle and Catalase

Abstract

ABSTRACT. We recently demonstrated that endothelial cells are more susceptible than renal tubular epithelial cells to oxidant injury and that renal tubular epithelial cells with proximal tubular characteristics including porcine proximal tubular epithelial cells, opossum kidney proximal tubular epithelial cells, and normal human kidney cortical epithelial cells are more susceptible to oxidant injury than the distal nephron-derived Madin Darby canine kidney cell line. To determine the basis of this differential response, we evaluated several antioxidant defenses in the five cell lines. Glutathione levels were not significantly different among the five cell lines, but catalase and glutathione reductase levels were significantly (p < 0.01) lower in endothelial cells compared to all renal tubular epithelial cells. Among renal tubular epithelial cells, Madin Darby canine kidney cells had significantly (p < 0.05) higher glutathione peroxidase activity. To further evaluate the role of antioxidant defenses in limiting oxidant injury, we determined two responses to oxidant injury (ATP depletion and 51Cr release) when glutathione was depleted with buthionine sulfoxamine and when catalase was inhibited with aminotriazole. Oxidant-induced ATP depletion was accentuated when catalase was inhibited as well as when glutathione was depleted with buthionine sulfoxamine. In contrast, inhibition of catalase had little or no effect on 51Cr release, whereas glutathione depletion resulted in accentuated 5'Cr release. We conclude that the increased susceptibility of endothelial cells to oxidant injury as compared with epithelial cells is associated with lower antioxidant defenses. Disruption of the glutathione redox cycle results in accentuated ATP depletion and lytic injury, whereas inhibition of catalase results in accentuated ATP depletion with little effect on lytic injury. Augmented oxidant-induced ATP depletion without augmented cell lysis suggests that ATP depletion alone may not be a critical mediator of cell death in oxidant stress.

Generation of reactive oxygen species by human mesothelioma cells

“…Previous studies have indicated that catalase activity is high in alveolar pneumocytes and macrophages, and catalase inhibition significantly reduces H 2 O 2 consumption by these cells (Kinnula et al, 1992b;Pietarinen et al, 1995). On the other hand, endothelial cells appear to protect themselves by the glutathione redox cycle, but not by catalase (Schraufstätter et al, 1985;Andreoli et al, 1992;Kinnula et al, 1992c). To further examine which antioxidant enzyme mechanism plays a major role as a free radical scavenger in these cells, we inhibited catalase with ATZ or γ-GCS with BSO and measured oxidant generation in both intact unexposed cells and cells exposed to menadione.…”

Glomerular inflammation induces resistance to tubular injury in the rat. A novel form of acquired, heme oxygenase-dependent resistance to renal injury.

“…Such possibilities as altered glomerular hemodynamic response, impaired renal concentration of nephrotoxins, less tubular backleak, reduced cast formation, and an inherent resistance of regenerating cells, are all speculative (10,11). Resistance to injury is dictated, in part, by the presence of the appropriate defense mechanisms as exemplified by the relative susceptibility to oxidant injury in different parts of the nephron (21,22). Quite recently, Zager and colleagues have provided significant contributions indicating that the acquisition of resistance is influenced by the setting, in vivo vs in vitro, in which it is explored (23, 24); that an inherent resistance to injury resides in plasma membrane of proximal tubules harvested from kidneys previously conditioned in vivo by ischemia (25,26) or urinary tract obstruction (27); and, as emblematic of one of the few mechanistic explorations for acquired resistance, cellular resistance to ATP depletion is dependent on the disappearance/de-phosphorylation of a 130-kD tyrosine-phosphorylated protein/ protein complex (28).…”

Differential effects of tumor necrosis factor and asbestos fibers on manganese superoxide dismutase induction and oxidant-induced cytotoxicity in human mesothelial cells

“…Adenine nucleotide depletion and purine nucleoside and base accumulation are sensitive methods for the assessment of oxidant-related cell injury; LDH release is not as sensitive and reflects cell membrane damage (Hyslop et al, 1988;Andreoli et al, 1992;Kinnula et al, 1994). Our data on LDH release showed that asbestos fiber exposure results in cell membrane injury, and that the cell membrane damage was similar in amosite-and amosite +TNF-exposed cells.…”