SHIGA TOXIN 2 (STX2) AND LPS FROM ENTEROHEMORRHAGIC ESCHERICHIA COLI (EHEC) PRODUCE A TLR4-INDEPENDENT MICROGLIAL REACTIVITY AND PRO-INFLAMMATORY CYTOKINES

ALEJANDRO VILLAREAL; PATRICIA A. GEOGHEGAN; JORGE GOLDSTEIN; ANA CELI; ADRIANA CANGELOSI; A. JAVIER RAMOS; LUCAS ELIZAGARAY; ALIPIO PINTO

Congreso; LXV REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2020

Stx2 from EHEC is the main cause of hemolytic uremic syndrome that is defined clinically by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Stx2 can also lead to encephalopathy with motor, cognitive and emotional impairments in 30% of cases. We have studied that Stx2 can bind to neurons through its receptor Gb3. Other authors have reported that Stx2 may bind to TLR4 in leukocytes, which leads to its activation and cytokine release. Given that microglial cells (MC) are CNS resident macrophages, we hypothesize that MC would respond to Stx2 through a TLR4 receptor. Therefore, our aim was to determine by in vivo and in vitro studies whether Stx2 produces MC activation through TLR4 and cytokine release. Mice were subjected to the following sublethal treatments: vehicle (control) or Stx2 (3ng)+LPS (800ng), to determine MC reactivity by immunofluorescence and cytokine release by flow cytometry. In vitro assays of MC were obtained from TLR4 KO rat brains which were treated with either control, LPS (50ng/ml), Stx2 (50 or 200ng/ml) or Stx2+LPS. One way ANOVA analysis, and Bonferroni post-hoc analysis were performed for in vivo and in vitro studies. After 24h of treatment, Stx2+LPS treated mice showed an increase in the expression of IBA1 as well as in the number of MC (p