Shiga toxin type 1 induce the release of soluble factors on LPS-sensitized astrocytes that alter the integrity and function of endothelial cells with brain endothelial properties.

LANDONI V.I; SCHIERLOH P.; DE CAMPOS-NEBEL M; MALAVER, E; DATRI, P; ROMANIUK, A; LAPPONI, M; SCHATTNER, M; PALERMO M.S; ISTURIZ M.A; FERNANDEZ G.C.

Congreso; First French - Argentine Immunology Congress, LVIII Reunión Anual de la Sociedad Argentina de Inmunología, XIII Jornada Científica del Grupo Rioplatense de Citometría de Flujo, 3º Jornadas Argentinas de Inmunodeficiencias Primaria; 2010

Sociedad Argentina de Inmunología, French Society of Immunology:

Hemolytic uremic syndrome (HUS) is associated to infections with Shiga toxin (Stx)-producing E.coli. 30% of patients show neurophatology related to death. Damage of brain endothelial cells (EC) from the brain blood barrier (BBB) may be involved. Astrocytes (AS) are inflammatory cells surrounding BBB EC. AS interaction with EC determines BBB phenotype and function. Recently, we demonstrated that LPS+Stx induce an inflammatory response on rat AS. Then, the aim was to evaluate the effects of factors released by LPS+Stx-treated AS on EC with brain endothelial properties. EC from human umbilical cord vein (HUVEC) were differentiated to EC with brain properties (HUVECd) using condition medium (CM) of AS. HUVECd were stimulated 24h with CM from untreated AS (CMC) or treated with LPS+Stx (CML+S). We found that HUVECd treated with CML+S caused a 2-fold increase in the expression of the Stx1 receptor compared to CMC, by FACS (p<0,05), correlating with an increased sensitivity to a low dose of Stx1 (p<0,05). Moreover, CML+S caused a decreased expression of tight junction protein ZO1 by FACS (MFI: CMC=3±0,2;CML+S=1±0,1;p<0,05), and the loss of peripheral distribution  by confocal microscopy. Moreover, CML+S increased translocation of Stx through HUVECd seeded on a transwell, quantified using a Stx-sensible cell line (%death:CMC=18±2;CML+S=39±2;p<0,05). Similarly, PMN migration across HUVECd was increased (PMNx105/ml:CMC=5±0,4;CML+S=10±0,9;p<0,05). CML+S activated HUVECd determined by an increased ICAM1 and vWF secretion (p<0,05), and directly promoted the activation of PMN and platelets (PL) (p<0,05). Furthermore, HUVECd exposed to CML+S induced PMN and PL adhesion (p<0,05). Finally, effects induced by CML+S were not seen when inhibiting AS NFkB activation or blocking AS-derived TNF-a(p<0,05). Results demonstrated that AS treated with LPS+Stx1 release factors (possibly TNF-á) that alter the BBB properties and permeability on HUVECd, contributing to EC damage and BBB dysfunction