ENTEROAGGREGATIVE Escherichia coli INFECTION INCREASES ADHESION OF ENTEROHEMORRHAGIC Escherichia coli TO EPITHELIAL CELLS

CARPINTERO-POLANCO Y; CANCINO C; MILIWEBSKY E; BERNAL A; SOSA F; RAMOS M; CHENIN I; PALERMO M; FERNÁNDEZ-BRANDO R

Congreso; LXXI Reunión Anual de la Sociedad Argentina de Inmunología; 2023

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes bloody diarrhea andhemolytic uremic syndrome (HUS) in children below 5 years of age. Shiga toxinproduction and bacterial adhesion to intestinal cells are the major pathogenicfactors. In recent years, an increased association of Enteroagreggative E. coli(EAEC) infection with HUS cases was reported by the National ReferenceLaboratory, ANLIS-Malbrán, in Argentina. The aim of this work was to test whetherEAEC infection increases the pathogenic potential of EHEC. . Caco-2 cells wereinfected for 3h with105 - 104 UFC/ml EAEC and 106 UFC/ml EHEC. We evaluatedthe percentage of adherence by CFU counting in agar plates, the presence ofShiga toxin in culture supernatants by cytotoxicity in Vero cells, andIL1ꞵ, IL6, TNF,CCL20 mRNA by qPCR.The infection is carried out an Caco-2 cells and evaluatedby confocal microscopy. The capacity of the strains to form Biofilm at air-liquidinterfaces is determined. When EAEC and EHEC were added simultaneously inCaco-2 cells a decreased adherence percentage of EHEC was observedcompared to control (p≤0.05, Kruskal-Wallis). Otherwise, when EAEC was added1h before EHEC a significantly increased percentage of EHEC adhesion wasevidenced (p≤0.05, Kruskal-Wallis). In addition, preliminary results showed anincreased IL1 mRNA level when Caco-2 cells were pre-infected with EAEC (p≤0.05, t-test). We did not observe differences on Stx production in all theconditions evaluated. In conclusion, the pre-infection of Caco-2 cells with EAECincreases the percentage of EHEC adhesion as well as the production of IL1.EAEC118/19 showed a greater capacity to form Biofilm than EHEC. This capacity wassignificantly diminished when EHEC and EAEC were cultured in equal proportions,which leads us to think that there may be a bacterial communication mediated byquorum sensing that interferes with the ability of EAEC to form Biofilm. EAECinfection induced a change in the morphology of Caco-2 cell, evidenced by cellularrounding with actin filaments aggregates. In addition, bacterial co-aggregation wasobserved on the cells when co-infected with EHEC-EAEC.An increased productionof cytokines in the intestine could contribute to the passage of Stx to the systemiccompartment and this could be related with an increased HUS outcome in children.However, more studies should be conducted.