Inhibition of water absorption in human proximal tubular epithelial cells in response to Shiga toxin-2

Abstract

Postdiarrhea hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children in Argentina. It is well established that Shiga toxin type 2 (Stx2) causes direct damage to glomerular endothelial cells and tubular epithelial cells, leading to a reduction in the water handling capacity of the kidney. In this study, we demonstrate that Stx2 and its B subunit (Stx2B) were able to inhibit water absorption across human renal tubular epithelial cell (HRTEC) monolayers without altering the short circuit current and the (3)H-mannitol permeability. Quantitative evaluation of (14)C-inulin transport across HRTEC monolayers showed a similar transport rate both before and after HRTEC treatment with Stx2 that confirmed the integrity of the paracellular pathway. Furthermore, Stx2 produced significant protein synthesis inhibition of HRTEC at concentrations as low as 0.001 ng/ml and 1 h of incubation, whereas Stx2B did not modify it at concentrations as high as 10,000 ng/ml and 6 h of incubation. Our findings suggest that whereas the action of Stx2 appears to be caused mainly by the inhibition of protein synthesis mediated by the A subunit, the binding of Stx2B subunit to the Gb3 receptor may affect the membrane mechanisms related to water absorption. We speculate that inhibition of water absorption may occur in proximal tubular cells in vivo in response to Stx2 and may contribute to the early event of HUS pathogenesis.

Clostridium perfringens epsilon toxin is cytotoxic for human renal tubular epithelial cells

“…The biophysical characterization of HRTEC monolayers growing on permeable supports together with the expression on these cells of the NHE3 transporter and functional aquaporins demonstrated that these primary cultures conserved, at least, the transport proteins and functional characteristics of proximal tubule cells in vivo. 17 Those results validated the HRTEC as a useful experimental model of human renal proximal tubule.…”

A Glucosylceramide Synthase Inhibitor Protects Rats Against the Cytotoxic Effects of Shiga Toxin 2

“…The binding of Stxs to renal tubular epithelial cells expressing Gb3 in vitro (8,9) and in vivo (10,11) has been shown to inhibit protein synthesis and induce apoptosis and necrosis. We have demonstrated that Stx2 holotoxin and its B subunit (Stx2B) inhibit water absorption across human renal tubular epithelial cell monolayers (12) and human colonic mucosa (13).…”

Epithelial Cells Activate Plasmacytoid Dendritic Cells Improving Their Anti-HIV Activity

“…The removal of the portion of the renal tissue for research purposes was approved by the ethics committee of the University of Buenos Aires. The cortex was dissected from the renal medulla and the primary culture of the HRTEC was performed as previously described [47]. Briefly, the cortical fragments were cultured for 1 h at 37°C in a buffer containing 0.1% collagenase type I.…”

“…To estimate the integrity of the HRTC monolayer, transepithelial electrical resistance (TEER) was measured as described [47], [48] using a Millicell-ERS electric resistance system (Millipore, Bedford, MA, USA). Briefly, HRTC were grown to confluence on a polycarbonate filter (0.2 µm pore size) in the upper chamber of a 24-transwell plate.…”