Cytotoxic effect of Shiga toxin-1 on human glomerular epithelial cells

Abstract

Shiga toxin-1 (Stx-1) has been implicated in the pathogenesis of postdiarrheal hemolytic-uremic syndrome (Stx HUS). Endothelial cells had been felt to be the primary renal target of Stx-1; however, recent studies suggest that renal epithelial cells may also be responsive. To further examine this issue, we evaluated the responsiveness of human glomerular epithelial cells (GECs) to the cytotoxic effects of Stx-1. Cultured GECs were exposed to Stx-1 in the presence and absence of a variety of inflammatory factors likely to be elevated in the kidney or serum of patients with Stx HUS. Cell survival, protein synthesis, total cell Gb3 levels and synthesis, and Stx-1 binding were measured. GECs were sensitive to Stx-1, with an LD50 of approximately 10-7 g/L (1.4 pmol/L). Interleukin-1 (IL-1), lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), and butyrate increased Stx-1 cytotoxicity and total cell Gb3 levels. These agents, with the exception of TNF-alpha, also increased Stx-1 binding to GECs. IL-6 failed to alter Stx-1 toxicity, binding, or Gb3 content. These studies indicate that GECs are sensitive to the cytotoxic effects of Stx-1 and that inflammatory factors can increase toxin responsiveness. GECs may be a target of Stx-1 action in Stx HUS.