Caco-2 Cell Monolayer Barrier Integrity

The human intestinal epithelial cells (Caco2 cell line) were cultured in RPMI 1640 medium (Sigma, Saint Louis, MO, USA) with 10% fetal bovine serum (Gibco, Brooklyn, NY, USA) at 37 °C in a humidified atmosphere of 5% CO₂. Caco2 cells (2 × 10⁴) were seeded on 24-well culture inserts (0.4 μm pore size; Corning, NY, USA) and grown to confluence. Thereafter, the cells were stimulated in the absence or presence of recombinant human IL-6 (R&D Systems, Minneapolis, MN, USA) or IFN-γ (R&D Systems) in the basolateral chamber up to 72 h later.
Electrical resistance across the stratified epithelium was measured using a Millicell-ERS-2 instrument (Millipore, Bedford, MA, USA) with “chopstick” electrodes, as described previously [19 (link),20 (link)]. The value obtained from a blank insert was subtracted to give the net resistance, which was then multiplied by the membrane area to give the resistance in area-corrected units (Ω·cm²). The values of transepithelial electrical resistance were recorded in a time-dependent manner after stimulation.