Fig. 1

OMVs and free-soluble factors (COF-SN) secreted by EcN and ECOR63 maintain barrier function in EPEC-infected cells. Confluent T-84 and Caco-2 cell monolayers grown in Transwell supports were infected with EPEC (MOI of 100) for 3 h in the absence or presence of EcN or ECOR63 OMVs (0.1 mg/ml) or COF-SN (0.5 mg/ml). Non-treated cells were processed in parallel as a control. Epithelial barrier function was analysed by measuring TER (a) and FD-4 flux (b) as markers of epithelial resistance and barrier permeability. a TER values were measured before and after 3-h infection. Data are presented as percentage of changes in TER (decrease) from the initial value. b After 3-h infection, cell monolayers were washed and treated apically with FD-4 (1 mg/ml). The fluorescence in the basolateral chamber was measured before and 1 h after the addition of FD-4. FD-4 flux values were calculated by subtracting the fluorescence intensity units (FI) measured at 0 h. Data were expressed as fold-change compared with non-infected control cells, whose values were normalized as 1. In all panels, data are from three independent biological experiments performed in triplicate. The TER baseline control values were 1290 ± 98 Ω.cm² for T-84 monolayers and around 920 ± 80 Ω.cm² for Caco-2 cells. a, Significance against untreated control cells (p ≤ 0.05); b, significance against control EPEC-infected cells (p ≤ 0.05)