Inhibition of transcellular water absorption in human renal microvascular endothelial cells in response to Shiga toxin type 2 (Stx2).

CARBALLO DANIELA; AMARAL MARÍA M; ALVAREZ ROMINA S; IBARRA CRISTINA; REPETTO HORACIO A

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Sociedad Argentina de Fisiología

Post-diarrhea hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children younger than 5 years old in Argentina. Clinical and histological renal damage has been strongly associated to Shiga toxin type 2 (Stx2) mainly produced by E. coli O157:H7. Previously, we have demonstrated an inhibition of the net water transport (Jw) across primary culture of human renal microvascular endothelial cells (HGEC) in response to Stx2 (Alvarez et al Plos One 2016). Jw is the result of water transfer across the paracellular and transcellular pathways induced by the hydrostatic and osmotic pressure gradients, respectively. Hence, the purpose of this study was to evaluate the hydrostatic (Phidr) and the osmotic (Posm) permeability and also FITC-Dextran transport in HGEC monolayers to clarify the mechanisms by which Stx2 inhibits the net absorptive Jw. Cells were cultured on Millicells supports (1.13 cm2) until confluence (TEER: 201.3 ± 4.1 Ω.cm2, n = 3). For Phidr and Posm assays, Millicells were placed in an Ussing chamber and the Jw, automatically registered across HGEC monolayers, was proportionally modified by applying hydrostatic (3 to 10 cm H2O) or osmotic (10-25 mOsm PEG 8000) pressure gradients. The Phidr (cm/seg) and Posm (10-3 cm/seg) before and after 1 h of treatment with Stx2 (10 ng/ml) were estimated from the slope of the corresponding regression lines. The Phidr was similar before and after Stx2 treatment (3.0  1.5 vs. 2.5  0.8, n=3, ns). This result was in agreement with FITC-Dextran transport across HGEC. On the contrary, the Posm showed a significantly decrease in response to Stx2 (3.7  0.5 vs. 4.6 ± 0.3, n=3, p