Sieving characteristics of cytokine- and peroxide-induced epithelial barrier leak: Inhibition by berberine

Figure 6 Morphological effects of cytokines and hydrogen peroxide on CACO-2 cell layers. CACO-2 cell layers were cultured at confluent density onto Millipore polycarbonate filters. Seven day post-seeding, the cell layers were refed with control medium or medium containing the combination of 200 ng/mL tumor necrosis factor-α, 200 ng/mL interferon-γ, and 50 ng/mL interleukin-1β (“cytomix”) (apical and basal-lateral compartments) for 48 h, followed by exposure to saline or saline containing 2 mmol/L H₂O₂ for 5 h. Cell layers were then fixed in formalin and stained with hematoxylin and eosin. A: CACO-2 cell layers exposed to control medium and control saline; B: CACO-2 cell layers exposed to cytomix medium and control saline; C: CACO-2 cell layers exposed to control medium and saline containing hydrogen peroxide; D: CACO-2 cell layers exposed to cytomix medium and saline containing hydrogen peroxide. In C and D, black arrows indicate instances of cytoplasmic blebbing. The red arrow points at a gap in the epithelial barrier arising from cell death and detachment.