Voltmeter

To study the translocation of AIEC LF82 in human FAE, an in vitro co-culture model was initially used, as described by Kernéis et al., showing that co-culture of Peyer’s patch lymphocytes and intestinal epithelial cells can trigger epithelial cell conversion to an M cell–like phenotype.^{36 (link)} We previously established a modified version of this co-culture.^{37 (link)}Briefly, intestinal epithelial Caco-2cl1 cells were grown for 14–17 days on Matrigel^® Matrix [Corning, USA]–coated 3.0 μm polycarbonate filters [Costar, Baedvenhorp, NL] until confluent, as defined by a transepithelial resistance [TER] of 400–500 Ω × cm², measured using a voltmeter [Millipore, Sweden]. The model FAE was obtained by adding 5 × 10⁵ Raji B cells suspended in DMEM to the basolateral chamber of confluent Caco-2cl1 cell monolayers. Corresponding mono-cultures of Caco-2cl1 epithelial cells on matched filter supports served as controls. The co-culture was maintained for 4–6 days, until M cells were generated.^{37 (link)}