Effects of a non-toxin producing E. coli O157:H7 and Stx2 on a human microvascular endothelial cell line (HMEC-1).

NICOLAS GARIMANO; FRANCISCO PATIN; GABRIEL GONDOLESI; HORACIO A. REPETTO; MARIA MARTA AMARAL; CRISTINA IBARRA

Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

SAIC-SAI-SAFIS-SAIB-SAA-SAB-SAB-SAFE-SAP-SAH

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains areresponsible of bloody diarrhea (hemorrhagic colitis) and hemolyticuremic syndrome (HUS). Hemorrhagic colitis (HC) is a major complication of HUS that sometimes appears prior to the detection ofcharacteristic HUS findings (Rahman et al, 2012). The patients withHC showed severe renal and neurologic disease. It is believed thatHC may be the result of compromise of local blood vessels and thatcould be the cause of the most severe HUS complications. E. coliO157:H7 is, by far, the most prevalent serotype associated withHUS and Stx2 is the major virulence factor associated for the moresevere symptoms of the infection. Our aim was to study the effectsof a non-toxin producing E. coli O157:H7 and Stx2 on HMEC-1 (animmortalized human microvascular endothelial cell line) in order tobetter understand the means by which STEC induce HC. We examined cell viability after 4 h of incubation with purified Stx2, a mutant of E. coli O157:H7 lacking stx2 gene (O157:H7∆stx2), E. coliHB101 (an E. coli strain lacking adhesive capabilities), and filteredO157:H7∆stx2 supernatant (SN), which was used to assess basalcytotoxicity. Cells were grown in 96-well culture plate and viabilitywas measured by neutral red uptake after 24 h under growth-arrested condition. We have also evaluated bacterial adhesion bycolony-forming unit (CFU/ml) assay and Giemsa-staining direct observation. We observed cytotoxic effects induced by Stx2 (CD50:0.01ug/ml) and by O157:H7∆stx2 (CD50: 2x108 CFU/ml). Moreover, significant bacterial adhesion was found with O157:H7∆stx2 comparedwith the other strain (P