Induction of Apoptosis in Normal Human Renal Tubular Epithelial Cells by Escherichia coli Shiga Toxins 1 and 2

Abstract

The cytotoxicity of Shiga toxin (Stx) 1 and Stx2 produced by Escherichia coli to human renal cortical epithelial cells (HRCEC) in primary culture was investigated. HRCEC express CD24, the marker of renal distal tubules, as well as globotriaosyl ceramide/CD77, the receptor for Stxs. Binding of Stxs to HRCEC was confirmed by positive staining with specific antibodies to Stxs. Treatment of HRCEC with Stxs induced rapid cell death, which was reversed in the presence of neutralizing antibody specific for Stx. DNA fragmentation was found to be accompanied by Stx-mediated cell death in HRCEC, indicating that apoptosis was part of the process. These data and previous reports indicate that a variety of renal cell types, including tubular epithelial cells as well as glomerular capillary endothelial cells, may be targets for Stx-mediated apoptosis, which could contribute to the pathogenesis of hemolytic-uremic syndrome caused by Stx-producing E. coli infection. In connection with the above reports, we previously demonstrated that Stxs are cytotoxic to the renal carcinoma line as well as the pathogenesis of HUS are still unclear. However, on the basis of histopathologic findings [3] and in vitro experi-ACHN, an in vitro model of human renal tubular epithelial cells, which is 10 6 -to 10 7 -fold more sensitive to Stxs than are ments [4 -7], endothelial damage in the glomeruli and arterioles of the kidney induced by Stx is believed to play a crucial HUVEC [17]. More interestingly, we have recently shown that apoptosis is involved in Stx-mediated cytotoxicity against role in the pathogenesis of Stx-mediated HUS [4, 8]. A few observations on the correlation between apoptosis of glomeru-ACHN cells [18]. To address whether these observations in ACHN represent lar endothelial cells and sporadic (non -Stx-mediated) HUS or the nature of normal tubular epithelial cells in the kidney, we examined the effect of Stxs on normal human renal cortical epithelial cells (HRCEC) by using a primary culture system. in primary culture, derived from a 24-year-old volunteer, were Recent worrisome increases in the incidences

Defensins from Insects and Plants Interact with Fungal Glucosylceramides

“…Globotriaosyl ceramide (Gal␣(1-4)-Gal␤(1-4)-Glc␤1-ceramide) is differentially organized in glycolipid-enriched microdomains in mammalian membranes (44). After internalization of the holotoxin by receptor-mediated endocytosis, verotoxin inhibits protein synthesis resulting in necrosis and/or apoptosis (45)(46)(47). Whether RsAFP2-induced fungal growth arrest is a result of the induced membrane permeabilization or results from its interaction with a putative intracellular target is currently not known.…”

Shiga toxin binding to globotriaosyl ceramide induces intracellular signals that mediate cytoskeleton remodeling in human renal carcinoma-derived cells

“…For example, renal tubular epithelial cells express Gb3, which can bind Stx1 and 2 (Boyd and Lingwood, 1989;Kiyokawa et al, 1998;Taguchi et al, 1998;Uchida et al, 1999). In vitro experiments have revealed that Stx1 induces cell death in renal tubular epithelial cells through protein synthesis inhibition and apoptosis (Karpman et al, 1998;Kiyokawa et al, 1998;Taguchi et al, 1998;Williams et al, 1999).…”

The B Subunit of Shiga Toxin Fused to a Tumor Antigen Elicits CTL and Targets Dendritic Cells to Allow MHC Class I-Restricted Presentation of Peptides Derived from Exogenous Antigens

“…The Shiga toxin receptor, globotriaosylceramide (Gb3), is a neutral glycosphingolipid that was first identified as an Ag of Burkitt's lymphoma and other tumors (54,55). Some human epithelial and endothelial cells and a subset of B lymphocytes located in germinal centers express Gb3 (55)(56)(57), while most other cell types are Gb3 negative. We have also demonstrated in mice that spleen and bone marrow cells do not express significant levels of Gb3.…”